Abundancia, densidad y estructura de tallas de Mellitella stokesii (Echinolampadacea: Mellitidae) en playones del estero El Tamarindo, El Salvador / Abundance, density and size structure of Mellitella stokesii (Echinolampadacea: Mellitidae) in sandbanks of El Tamarindo estuary, El Salvador

Resumen Introducción: Los equinoideos irregulares se caracterizan por tener una selección del sustrato en fondos blandos principalmente. En El Salvador se han registrado siete especies de equinoideos irregulares en las principales playas arenosas del país, M. stokesii es una de ellas. Objetivo: Determinar la abundancia, densidad y estructura de tallas, en playones de la bocana del estero El Tamarindo, El Salvador. Métodos: La investigación se realizó en época seca en el oriente del país en playones del estero El Tamarindo que se caracteriza por presentar grandes extensiones de arena mezclada con materia orgánica. En cada sitio, se trazaron transectos en banda paralelos a la costa mediante 9 cuadrantes de 10 m2 separados entre sí por 10 m (área total de 90 m2), en donde se contabilizaron y midieron los individuos de M. stokesii que se encontraran dentro del área delimitada. Resultados: Se contabilizaron 958 individuos de M. stokesii con una densidad total de 10.64 ± 13.22 ind/m2. El rango de tamaños fue de 1-6.5 cm. El hábitat se caracterizó por presentar arena con materia orgánica en los primeros mm del sustrato en compañía de otros invertebrados. Conclusiones: La abundancia y densidad de M. stokesii es similar a la registrada en otros estudios de la región.

Abstract Introduction: Irregular echinoids are characterized by having a selection of the substrate mainly on soft bottoms. In El Salvador, seven species of irregular echinoids have been recorded on the main sandy beaches of the country, M. stokesii is one of them. Objective: Determine the abundance, density and size structure of M. stokesii on beaches at the mouth of the El Tamarindo estuary, El Salvador. Methods: The research was carried out in the dry season in the east of the country on the beaches of the El Tamarindo estuary, which is characterized by large extensions of sand mixed with organic matter. At each site, band transects parallel to the coast were plotted by 9 quadrants of 10 m2 separated from each other by 10 m (total area of 90 m2), where individuals of M. stokesii found within the delimited area were counted and measured. Results: 958 individuals of M. stokesii were counted with a total density of 10.64 ± 13.22 ind/m2. The size range was 1-6.5 cm. The habitat was characterized by presenting sand with organic matter in the first mm of the substrate in the company of other invertebrates. Conclusions: The abundance and density of M. stokesii are similar to the ones recorded in other studies in the region.

Phylogeography, colouration, and cryptic speciation across the Indo-Pacific in the sea urchin genus Echinothrix.

The sea urchins Echinothrix calamaris and Echinothrix diadema have sympatric distributions throughout the Indo-Pacific. Diverse colour variation is reported in both species. To reconstruct the phylogeny of the genus and assess gene flow across the Indo-Pacific we sequenced mitochondrial 16S rDNA, ATPase-6, and ATPase-8, and nuclear 28S rDNA and the Calpain-7 intron. Our analyses revealed that E. diadema formed a single trans-Indo-Pacific clade, but E. calamaris contained three discrete clades. One clade was endemic to the Red Sea and the Gulf of Oman. A second clade occurred from Malaysia in the West to Moorea in the East. A third clade of E. calamaris was distributed across the entire Indo-Pacific biogeographic region. A fossil calibrated phylogeny revealed that the ancestor of E. diadema diverged from the ancestor of E. calamaris ~ 16.8 million years ago (Ma), and that the ancestor of the trans-Indo-Pacific clade and Red Sea and Gulf of Oman clade split from the western and central Pacific clade ~ 9.8 Ma. Time since divergence and genetic distances suggested species level differentiation among clades of E. calamaris. Colour variation was extensive in E. calamaris, but not clade or locality specific. There was little colour polymorphism in E. diadema.

Heart urchins from the depths: Corparva lyrida gen. et sp. nov. (Palaeotropidae), and new records for the southwestern Atlantic Ocean / Erizos corazón de las profundidades: Corparva lyrida gen. et sp. nov. (Palaeotropidae) y nuevos registros para el Océano Atlántico sudoccidental

Introduction: Sea urchins in the order Spatangoida are the most diverse group of extant echinoids. Objective: Describe a new genus and species of Spatangoida from abyssal depths, and add new records for known species. Methods: Specimens were collected during several cruises at different areas of the southwestern Atlantic Ocean (SWAO), among 37-55° S latitude at depths ranging from 55 to 3 000 m. We present morphological and ultrastructure analyses. Results: Corparva lyrida gen. et sp. nov. (Palaeotropidae) is described from the Mar del Plata Canyon on the Argentine continental slope (2 950 m depth), the first record of this family from Argentina. Corparva gen. nov. differs in having an apical system semi-ethmolytic, and labrum reaching to rear part of second adjacent ambulacral plate. We also report the northernmost distribution and deepest record for Brisaster moseleyi (38° S latitude, 2 212 m depth), the northward extension of the distribution range of Tripylus excavatus (39° S latitude, 74 m depth), and the first record of Abatus philippii and Abatus agassizii at the Burdwood Bank/MPA Namuncurá. Conclusions: The present work brings novel and updated data about the diversity and distribution of spatangoids from the SWAO, including the description of C. lyrida gen. et sp. nov., and new records of species. This shows how much remains to be known about the diversity and distribution of heart urchins in the SWAO, especially from the deep-sea.

Introducción: Los erizos de mar del orden Spatangoida son el grupo más diverso de equinoideos recientes. Objetivo: Describir un nuevo género y una nueva especie de Spatangoida de profundidades abisales, y reportar nuevos registros para especies conocidas. Métodos: Los ejemplares fueron recolectados durante varias expediciones a diferentes áreas del Océano Atlántico sudoccidental (OAS), entre las latitudes 37-55° S y abarcando profundidades desde 55 a 3 000 metros. Presentamos análisis morfológicos y de ultraestructura. Resultados: Corparva lyrida gen. et sp. nov. (Palaeotropidae) fue descripta para el cañón submarino Mar del Plata en el talud continental de Argentina (2 950 m de profundidad), el primer registro de esta familia para Argentina. Corparva gen. nov. difiere en tener un sistema apical semi-etmolítico y labrum que llega a la parte posterior de la segunda placa ambulacral adyacente. También informamos la distribución más septentrional y el registro más profundo para Brisaster moseleyi (latitud 38° S, 2 212 m de profundidad), la extensión hacia el norte del rango de distribución de Tripylus excavatus (latitud 39° S, 74 m de profundidad) y el primer registro de Abatus philippii y Abatus agassizii en el Banco Burdwood/AMP Namuncurá. Conclusiones: El presente trabajo aporta datos novedosos y actualizados sobre la diversidad y distribución de erizos de mar espatangoideos del OAS, incluyendo la descripción de C. lyrida gen. et sp. nov., y nuevos registros para especies conocidas. Esto muestra cuánto queda por conocer sobre la diversidad y distribución de los erizos corazón en el OAS, especialmente de las profundidades marinas.

Diversity and biostratigraphy of the late Oligocene-late Miocene sand dollars (Echinoidea: Scutelliformes) of Argentina and Uruguay / Diversidad y bioestratigrafía de las galletas de mar (Echinoidea: Scutelloida: Scutellifomes) del Oligoceno tardío-Mioceno tardío de Argentina y Uruguay

Introduction: Scutelliforms were diverse and widespread in shallow marine environments during Neogene times in South America. Nevertheless, they have almost never been used as biostratigraphic tools. Objective: To provide a refined stratigraphic frame useful for calibrating temporal dimensions of scutelliform diversity from Argentina and Uruguay and its correlation with the molluscan assemblages previously proposed. Methods: A detailed survey of their geographic and stratigraphic provenance was carried out. We revised both the bibliography and collections (institutional and from our own field work). Results: The group is represented by 14 species belonging to six genera, and four assemblages were identified. Numerical dates of the Neogene marine rocks obtained recently allowed their placement in a chronological scheme: "Iheringiella" sp. A is restricted to the late Oligocene, the genera Camachoaster and "Eoscutella" and the species Monophoraster telfordi to the early Miocene, Abertella gualichensis and Abertella miskellyi to the middle Miocene, and Monophoraster duboisi, Amplaster coloniensis and Amplaster ellipticus to the late Miocene. Non-lunulate scutelliforms are not restricted to the late Oligocene as previously supposed. The oldest occurrence of the genus Monophoraster corresponds to the early Miocene, and along with Iheringiella are long-living taxa that embrace the 25.3 Ma-18.1 Ma (Iheringiella patagonensis) and approximately 15 Ma-6.48 Ma (Monophoraster darwini) intervals. The presence of Iheringiella in the early Miocene of northeastern Patagonia is corroborated, reaching there its northernmost distribution. Monophoraster darwini has a temporal range from the late Miocene (where it was previously thought to be restricted) back to the middle Miocene, since this is the species yielded in the well-known and discussed "Monophoraster and Venericor Beds". Conclusions: The Paleogene-Neogene scutelliforms of Argentina and Uruguay range from the late Oligocene to the late Miocene. There is a good correspondence among the numerical ages, molluscan biozones and scutelliform assemblages.

Introducción: Realizamos una síntesis actualizada de la composición taxonómica de las asociaciones de escutélidos del Oligoceno tardío-Mioceno tardío de Argentina y Uruguay. Objetivo: Ubicar los escutélidos en un marco estratigráfico refinado, a los efectos de observar su diversidad a lo largo del tiempo y la correlación de sus ensambles con los ya conocidos de moluscos. Métodos: Revisamos en detalle la procedencia geográfica y estratigráfica de los ejemplares y su asignación taxonómica, basándonos tanto en la bibliografía como en colecciones institucionales y producto de nuestras campañas de colecta. Resultados: El grupo está representado por 14 especies agrupadas en seis géneros, siendo identificadas en cuatro ensambles. Las edades numéricas recientemente obtenidas permitieron su ubicación en un esquema cronológico: "Iheringiella" sp. A se restringe al Oligoceno tardío, Camachoaster y "Eoscutella", y Monophoraster telfordi al Mioceno temprano, Abertella gualichensis y Abertella miskellyi al Mioceno medio, y Monophoraster duboisi, Amplaster coloniensis y Amplaster ellipticus al Mioceno tardío. Los escutélidos sin lúnula no están restringidos al Oligoceno tardío como se suponía. Monophoraster aparece en el Mioceno temprano y junto con Iheringiella abarcan largos períodos de tiempo, encontrándoselos entre los 25.3 Ma-18.1 Ma (Iheringiella patagonensis) y aproximadamente los 15 Ma-6.48 Ma (Monophoraster darwini). Se corrobora la presencia de Iheringiella en el Mioceno temprano del noreste de Patagonia, donde alcanza su punto más septentrional. Monophoraster darwini se encuentra desde el Mioceno medio hasta el Mioceno tardío (lapso para el cual previamente se consideraba restringido), ya que se trata de la especie presente en los bien conocidos "estratos con Monophoraster y Venericor". Conclusiones: Los escutélidos del Paleógeno-Neógeno de Argentina y Uruguay se encuentran desde el Oligoceno tardío hasta el Mioceno tardío. Hay una buena correspondencia entre las edades numéricas, las biozonas de moluscos y los ensambles de escutélidos.

Redescription of the sea urchin Eucidaris thouarsii (Cidaroida: Cidaridae) based on material from the Mexican Pacific / Redescripción del erizo de mar Eucidaris thyarsii (Cidaroida: Cidaridae) basado en material del Pacífico mexicano

Introduction: Eucidaris thouarsii is a cidaroid sea urchin found from the Gulf of California to Ecuador. Its taxonomy is based on general descriptions of test shape, primary and secondary spines, the Aristotle's lantern, apical system, and peristome. Objective: To redescribe E. thouarsii with detailed descriptions, adding new taxonomic characters. Methods: We examined and reidentified 792 specimens, measuring and analyzing in detail structures of taxonomic value. Results: The horizontal diameter of the test ranges from 2.8 to 48.45 mm; the peristome corresponds to 40-60 % of that diameter, proportionally bigger than the apical system; the interambulacral areas are four times larger than the ambulacral areas. The variation of the pedicellariae is shown with scanning electron microscopy. The specimens of the Mexican oceanic islands are markedly different when compared to those of the mainland. Conclusions: Eucidaris thouarsii has five well differentiated secondary spines, and also specific regionalization; the apical system varies according to the size of the Horizontal Diameter of the Test; the globiferous pedicellariae have intraspecific differences; and the tridentate pedicellariae are specifically regionalized.

Introducción: Eucidaris thouarsii es una especie de erizo de mar, cidárido presente desde el Golfo de California hasta Ecuador. Su taxonomía está basada en descripciones generales de la forma de la testa, espinas primarias y secundarias, la linterna de Aristóteles, el sistema apical y peristoma. Objetivo: Redescribir E. thouarsii con descripciones detalladas, añadiendo nuevos caracteres taxonómicos. Método: Examinamos y reidentificamos 792 ejemplares, midiendo y analizando a detalle estructuras de valor taxonómico. Resultados: El diámetro horizontal de la testa va de 2.8 a 48 mm; el peristoma corresponde entre el 40-60% del diámetro horizontal de la testa, proporcionalmente más grande que el sistema apical; el área interambulacral es cuatro veces más grande que el área ambulacral. La variación en los pedicelarios se muestra con microscopía electrónica de barrido. Los ejemplares de las islas oceánicas mexicanas son claramente diferentes, comparados con los de la costa. Conclusiones: Eucidaris thouarsii tiene cinco tipos bien definidos de espinas secundarias que se encuentran regionalizadas en la testa, el sistema apical varía de acuerdo con el diámetro horizontal de la testa, los pedicelarios globíferos tienen diferencias intraespecíficas y los pedicelarios tridentados estas específicamente regionalizados.

Morfología y crecimiento relativo en Clypeaster europacificus (Clypeasteroida: Clypeasteridae) del Golfo de California / Morphology and relative growth in Clypeaster europacificus (Clypeasteroida: Clypeasteridae) from the Gulf of California

Introducción: Clypeaster europacificus es una especie de galleta de mar que se distribuye de 0 a 200 m en el Golfo de California. Objetivo: Describir la morfología y el crecimiento relativo en la testa de C. europacificus. Métodos: Medimos 1 846 especímenes de museo de C. europacificus (N = 1 846) y analizamos el patrón de crecimiento en 32 especímenes de Baja California Sur, México (64 m de profundidad). Estudiamos cinco variables: radio mayor (R) (variable independiente), radio menor (r), longitud del pétalo anterior (LP), área total de prueba (A) y peso seco (P). Resultados: El área de cobertura del petaloide y el contorno de la testa son los caracteres taxonómicos importantes para C. europacificus: los especímenes van desde casi redondos en especímenes pequeños (≤ 3 cm de radio) a ondulados, enfatizando un contorno pentagonal, en organismos más grandes (≥ 3,1 cm de radio). Conclusiones: Existe un crecimiento alométrico negativo en las relaciones R vs. r, R vs. A y R vs. P; mientras que la relación R vs. LP tiene un crecimiento alométrico positivo.

Introduction: Clypeaster europacificus is a species of sand dollar found from 0 to 200 m in the Gulf of California. Objective: Describe the morphology and relative growth in the test of C. europacificus. Methods: We measured 1 846 museum specimens of C. europacificus (N = 1 846) and analyzed growth pattern in 32 specimens from Baja California Sur, Mexico (64 m depth). We studied five variables: major radius (R) (independent variable), minor radius (r), length of anterior petal (LP), total test area (A) and dry weight (P). Results: The petaloid cover area and the outline of the test are the important taxonomic characters for C. europacificus: they range from almost round in small specimens (≤ 3 cm in radius) to wavy, emphasizing a pentagonal outline, in larger organisms (≥ 3.1 cm in radius). Conclusions: There is negative allometric growth in the relationships R vs. r, R vs. A, and R vs. P; while the relationship R vs. LP has positive allometric growth.

MITF: an evolutionarily conserved transcription factor in the sea urchin Paracentrotus lividus.

Microphthalmia-associated transcription factor (MITF) is a member of MYC superfamily, associated with melanocyte cells, as it was discovered in depigmented mice. However, over the last years it was found to be involved in many cellular signaling pathways, among which oncogenesis, osteoclast differentiation, and stress response. In mammals, Mitf gene mutations can cause diverse syndromes affecting pigmentation of eyes or skin, bone defects and melanomas. As MITF protein homologs were also found in some invertebrates, we have isolated and characterized the MITF cDNAs from the sea urchin Paracentrotus lividus, referred to as Pl-Mitf. The in silico study of the secondary and tertiary structure of Pl-Mitf protein showed high conserved regions mostly lying in the DNA binding domain. To understand the degree of evolutionary conservation of MITF, a phylogenetic analysis was performed comparing the Pl-Mitf deduced protein with proteins from different animal species. Moreover, the analysis of temporal and spatial expression pattern of Pl-Mitf mRNA showed that it was expressed from the onset of gastrulation of the sea urchin embryo to the pluteus larva, specifically in primary mesenchymes cells (PMCs), the sea urchin skeletogenic cells, and in the forming archenteron, the larval gut precursor. In silico protein-protein interactions analysis was used to understand the association of MITF with other proteins. Our results put in evidence the conservation of the MITF protein among vertebrates and invertebrates and may provide new perspectives on the pathways underlying sea urchin development, even if further functional analyses are needed.

Possible cooption of a VEGF-driven tubulogenesis program for biomineralization in echinoderms.

Biomineralization is the process by which living organisms use minerals to form hard structures that protect and support them. Biomineralization is believed to have evolved rapidly and independently in different phyla utilizing preexisting components. The mechanistic understanding of the regulatory networks that drive biomineralization and their evolution is far from clear. Sea urchin skeletogenesis is an excellent model system for studying both gene regulation and mineral uptake and deposition. The sea urchin calcite spicules are formed within a tubular cavity generated by the skeletogenic cells controlled by vascular endothelial growth factor (VEGF) signaling. The VEGF pathway is essential for biomineralization in echinoderms, while in many other phyla, across metazoans, it controls tubulogenesis and vascularization. Despite the critical role of VEGF signaling in sea urchin spiculogenesis, the downstream program it activates was largely unknown. Here we study the cellular and molecular machinery activated by the VEGF pathway during sea urchin spiculogenesis and reveal multiple parallels to the regulation of vertebrate vascularization. Human VEGF rescues sea urchin VEGF knockdown, vesicle deposition into an internal cavity plays a significant role in both systems, and sea urchin VEGF signaling activates hundreds of genes, including biomineralization and interestingly, vascularization genes. Moreover, five upstream transcription factors and three signaling genes that drive spiculogenesis are homologous to vertebrate factors that control vascularization. Overall, our findings suggest that sea urchin spiculogenesis and vertebrate vascularization diverged from a common ancestral tubulogenesis program, broadly adapted for vascularization and specifically coopted for biomineralization in the echinoderm phylum.

Understanding trophic relationships among Caribbean sea urchins

ResumenLas especies Echinometra lucunter, Echinometra viridis, Lytechinus variegatus, Tripneustes ventricosus, and Diadema antillarum son los erizos de mar más comunes en los hábitat litorales del Caribe. Los erizos de mar T. ventricosus y L. variegatus habitan generalmente los pastos marinos mientras que las otras tres especies se encuentran asociadas a sustratos rocosos. Los hábitos alimentarios de estas especies han sido bien documentados y son reconocidas como herbívoros - omnívoros; sin embargo, pocas de estas especies han sido caracterizadas isotópicamente. Utilizamos los isótopos estables para caracterizar estas cinco especies de erizos y establecer las posiciones tróficas para las especies que cohabitan los mismos ecosistemas. También cuantificamos la contribución de los recursos alimentarios para E. lucunter. Los erizos T. ventricosus y D. antillarum mostraron los mayores valores de δ15N y valores similares de δ13C que variaron desde -11.6 ± 0.63 a -10.4 ± 0.99 %; donde el erizo E. lucunter mostró los valores más negativos con -15.40 ± 0.76 %. Las comunidades de algas no mostraron diferencias en valores promedio de δ15N (F= 1.300, df= 3, p= 0.301), pero sí mostraron variaciones en los valores de δ13C (F= 7.410, df= 3, p= 0.001). Los estudios de amplitud de elipses de nicho determinaron que las especies de los biotopos rocosos (D. antillarum, E. lucunter y E. viridis) no mostraron solapamiento de nicho. Similar resultado también se encontró en las especies de erizos que habitan en los pastos marinos. Sin embargo, la distancia entre estas dos especies fue menor respecto a la distancia entre las especies de erizos que habitan en los sustratos rocosos. Nuestros resultados muestran que las especies que habitan en los pastos marinos mostraron valores más elevados de δ13C en comparación con las especies de los sustratos rocosos. No se encontraron diferencias espaciales para E. lucunter en δ15N, pero sí en δ13C. Los modelos de mezcla bayesianos demuestran la plasticidad alimentaria de E. lucunter, especie capaz de utilizar múltiples recursos algales dependiendo de la disponibilidad por sitio. Semejanzas en δ15N entre D. antillarum y T. ventricosus parecen indicar similitudes tróficas entre ambas especies. Si bien T. ventricosus es reconocido como omnívoro, D. antillarum siempre ha sido considerado un herbívoro generalista. Finalmente, la falta de solapamiento entre las especies en los dos biotopos parece indicar una estrategia de partición de recursos para evitar la competencia de nicho entre especies concurrentes.

AbstractThe species Echinometra lucunter, Echinometra viridis, Lytechinus variegatus, Tripneustes ventricosus, and Diadema antillarum are the most common sea urchins of littoral habitats in the Caribbean. T. ventricosus and L. variegatus are associated with seagrass beds, while the other three species usually inhabit hardground substrates. Food preferences of these species are well documented and they are commonly accepted as being primarily herbivorous-omnivorous; nevertheless, few of them have previously been characterized isotopically. We used this approach for assessing the isotopic characterization of five echinoids. We established the trophic position of two groups of co-occurring species and quantified the contribution of food resources in the diet of Echinometra lucunter, considered the most common sea urchin in the Caribbean region. The species T. ventricosus and D. antillarum showed the highest values of δ15N. Sea urchins exhibited similar values of δ13C varying from -11.6 ± 0.63 to -10.4 ± 0.99%. The echinoid E. lucunter displayed the lowest values of carbon, from -15.40 ± 0.76%. Significant differences among species were found for δ15N and δ13C. Seaweed communities exhibited no differences among sites for overall δ15N (F= 1.300, df= 3, p= 0.301), but we found spatial differences for δ13C (F= 7.410, df= 3, p= 0.001). The ellipse-based metrics of niche width analysis found that the hardground biotope species (D. antillarum, E. lucunter, and E. viridis) did not overlap each other. Similar results were obtained for the co-occurring species of the seagrass biotope; however, the distance between these species was closer than that of the hardground biotope species. The Bayesian mixing models run for E. lucunter at all four localities found differences in food resources contribution. The algae D. menstrualis, C. crassa and B. triquetrum dominated in CGD; whereas C. nitens, Gracilaria spp., and D. caribaea represented the main contributor algae to the diet of E. lucunter at LQY. In Culebra Island, no dominance of any particular algae was detected in TMD, where six of the eight species exhibited a similar contribution. Similarities in δ15N between D. antillarum and T. ventricosus may hint towards a similar trophic level for these species, although T. ventricosus is widely accepted as an omnivore, while D. antillarum is considered a generalist herbivore. The lack of overlap among species in the two biotopes seems to indicate a resource partitioning strategy to avoid niche competition among co-occurring species. Rev. Biol. Trop. 64 (2): 837-848. Epub 2016 June 01.

Polysaccharide Constituents of Three Types of Sea Urchin Shells and Their Anti-Inflammatory Activities.

As a source of potent anti-inflammatory traditional medicines, the quantitative chromatographic fingerprints of sea urchin shell polysaccharides were well established via pre-column derivatization high performance liquid chromatography (HPLC) analysis. Based on the quantitative results, the content of fucose and glucose could be used as preliminary distinguishing indicators among three sea urchin shell species. Besides, the anti-inflammatory activities of the polysaccharides from sea urchin shells and their gonads were also determined. The gonad polysaccharide of Anthocidaris crassispina showed the most potent anti-inflammatory activity among all samples tested.

Actividad antibacteriana y antifúngica de la estrella de mar Oreaster reticulatus (Valvatida: Oreasteridae) y de los erizos de mar Mellita quinquiesperforata (Clypeasteroida: Mellitidae) y Diadema antillarum (Diadematoida: Diadematidae) del Caribe Colombiano / Antibacterial and antifungal activity of the starfish Oreaster reticulatus (Valvatida: Oreasteridae) and the sea urchins Mellita quinquiesperforata (Clypeasteroida: Mellitidae) and Diadema antillarum (Diadematoida: Diadematidae) from the Colombian Caribbean

Resumen Como organismos bentónicos, estrellas de mar y erizos de mar están constantemente expuestos a un gran número de bacterias, hongos y virus, algunos de ellos potencialmente dañinos. Para sobrevivir, estos equinodermos dependen de su sistema inmunológico, que ha desarrollado una serie de compuestos que actúan como estrategias de defensa antimicrobianos. En este trabajo se evaluaron las actividades antibacteriana y antifúngica de los extractos metanólicos de la estrella de mar Oreaster reticulatus y de los erizos de mar Mellita quinquiesperforata y Diadema antillarum recolectados en el Caribe Cordobés, frente a las bacterias Escherichia coli, Staphylococcus aureus y Klebsiella pneumoniae, y frente a los hongos fitopatógenos Fusarium sp., Scleortium sp., y Rhizoctonia sp. Los resultados obtenidos mostraron que O. reticulatus y D. antillarum, son organismos capaces de producir compuestos con capacidad antibiótica generando inhibición bacteriana a bajas concentraciones (< 100 µg / ml), mientras que M. quinquiesperforata no presentó inhibición a ninguna de la concentraciones evaluadas. Específicamente, la cepa de S. aureus fue la que presentó mayor susceptibilidad frente a los extractos evaluados, es decir, los metabolitos producidos por los equinodermos inhiben con mayor facilidad las bacterias Gram +. Por su parte, solo el extracto de diclorometano de D. antillarum presentó inhibición frente a Fusarium sp., con porcentajes de inhibición de 78.2 % y 56.5 % a concentraciones de 2 000 y 100 µg / ml. Se encontró que las cepas de los hongos Sclerotium sp. y Rhizoctonia sp., presentaron resistencia frente a todos los.extractos de los organismos estudiados, con excepción del extracto de diclorometano de D. antillarum.

Abstract As benthic organisms, sea stars and sea urchins are constantly exposed to a large number of bacteria, fungi and viruses, some of them potentially harmful. To survive, these echinoderms depend on their immune system, which has developed a number of compounds which act as antimicrobial defense strategies. In this work, the antibacterial and antifungal activities of the extracts of the starfish Oreaster reticulatus and sea urchins Diadema antillarum and Mellita quinquiesperforata collected in the Caribbean Cordobés were evaluated against the bacteria Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae and against the phytopathogenic fungi Fusarium sp., Scleortium sp., and Rhizoctonia sp. Our results show that O. reticulatus and D. antillarum produce compounds producing bacterial inhibition at low concentrations (< 100 μg / ml), while, M. quinquiesperforata extracts showed no inhibition at any of the concentrations tested. Specifically, the strain of S. aureus was the one with greater susceptibility to the extracts evaluated, i.e. the metabolites produced by echinoderms inhibit more easily gram + bacteria. Only the D. antillarum dichloromethane affected Fusarium sp. with inhibition of 78.2 % and 56.5 % at concentrations of 2 000 and 100 μg / ml. Strains of the fungi Sclerotium sp. and Rhizoctonia sp. had resistance to all extracts. Rev. Biol. Trop. 63 (Suppl. 2): 329-337. Epub 2015 June 01.

Consecuencias de la mortandad masiva del erizo Diadema mexicanum (Diadematoida: Diadematidae) sobre la comunidad íctica arrecifal en bahía La Entrega, Huatulco, México / Consequences of a mass mortality event of the sea urchin Diadema mexicanum (Diadematoida: Diadematidae) on the reef icthic community in Bahía La Entrega, Huatulco, Mexico

Resumen En los arrecifes de coral, existen especies claves que mantienen en equilibrio las comunidades. La ausencia de una especie clave genera cambios importantes en la estructura y dinámica comunitaria de los taxa coexistentes. En este estudio se analizó la comunidad íctica arrecifal durante un periodo posterior al evento de mortandad masiva del erizo Diadema mexicanum, reportado en mayo de 2009 en La Entrega, Huatulco. Se realizaron censos visuales mensualmente de agosto 2009 a julio 2010. Con datos previos (febrero 2006-enero 2007) en los que se usó la misma metodología y los de este estudio, se comparó la abundancia y riqueza de especies y se calcularon los índices de Diversidad de Shannon, Equidad de Pielou y Dominancia de Simpson entre el periodo previo y posterior al evento de mortandad. Se probó la existencia de diferencias significativas entre ambos periodos mediante MDS, PERMANOVA y SIMPER. Los resultados mostraron que existió un incremento significativo en la abundancia después del evento y el MDS y PERMANOVA mostraron que existen diferencias estadísticamente significativas en el ensamblaje de peces en La Entrega entre los dos periodos analizados. De acuerdo con el análisis SIMPER, la disimilitud observada entre periodos fue determinada por las especies Haemulon maculicauda, Thalassoma lucasanum, Selar crumenophthalmus y Stegastes acapulcoensis. Los resultados indican que el disturbio generado por la mortandad de D. mexicanum tuvo efectos importantes en la comunidad íctica de hábitos alimenticios similares, afectando importantemente a S. acapulcoensis y en menor grado a otros herbívoros como Scarus gobban y Prionurus punctatus, mientras que algunas especies carnívoras también incrementaron en abundancia, lo cual sugiere que la desaparición del erizo y en consecuencia su efecto competitivo, probablemente propició el incremento en otros invertebrados que constituyen alimento para las especies carnívoras.

Abstract Coral reefs have key species that control the community structure and composition, and exert influence on the stability and permanence of the reefs. When a key species is lost, there are important effects in the structure and diversity of the coexistent taxa. We analyzed the reef fish community in a period subsequent to the mass mortality event of the sea urchin Diadema mexicanum, reported in May 2009 in La Entrega, Huatulco, Mexico. Visual censuses were carried out monthly from August 2009 to July 2010 in order to record abundance and species richness. The data were used concurrently with data generated previously (February 2006-January 2007) in La Entrega using the same methodology in order to obtain community ecological Indices (Shannon´s diversity, Pielou´s evenness and Simpson´s dominance). Significant differences in fish assemblages regarding the periods before and after the die-off were tested using MDS, PERMANOVA, and SIMPER. The results showed a significant increase of abundance of fishes after the event of mass mortality, compared to the period previous to the event. There were significant differences in fish assemblages between periods.The dissimilarity between the periods was explained by the presence of Haemulon maculicauda (28.96%), Thalssoma lucasanum (22.17%), Selar crumenophthalmus (12.93%) and Stegastes acapulcoensis (11.44%). Our results suggest that the disturbance produced by the disappearance of D. mexicanum had important effects on the icthic community with feeding habits similar to those of the urchin, affecting more importantly to S. acapulcoensis and in less intensity to other herbivores such as Scarus gobban and Prionurus punctatus; meanwhile other fishes which are carnivores (for instance H. maculicauda) also increased importantly in abundance, suggesting that the disappearance of the urchin and in consequence its competitive effect, probably also propitiated a significant increase of other invertebrates which constitute the food source for carnivores. Rev. Biol. Trop. 63 (Suppl. 2): 159-171. Epub 2015 June 01.

Diadema mexicanum, erizo de mar clave en los arrecifes coralinos del Pacífico Tropical Oriental: lo que sabemos y perspectivas futuras (Diadematoida: Diadematidae) / Diadema mexicanum, a key species of sea urchin in coral reefs of the Eastern Tropical Pacific: state of knowledge and future perspectives

Resumen En esta revisión se presenta el estado de conocimiento de Diadema mexicanum en el Pacífico Tropical Oriental con base en estudios realizados principalmente en Panamá, Costa Rica y México. La densidad de D. mexicanum es baja, con valores entre 0.008 y 9.5 ind m-2, sin embargo, bajo condiciones particulares como la presencia de El Niño, las densidades pueden alcanzar hasta 150 ind m-2, por otra parte se ha reportado solo un evento de mortandad masiva a nivel local de esta especie en México. La bioerosión de D. mexicanum es más marcada en arrecifes más sureños, mientras que en localidades de México existen valores más bajos. De acuerdo con los estudios realizados en Panamá y México se ha determinado que D. mexicanum se reproduce entre abril y noviembre y su reproducción está influenciada por la dinámica oceánica de vientos y corrientes. Hace falta ampliar las áreas de estudio para determinar si las poblaciones de D. mexicanum siguen el mismo comportamiento reproductivo en toda su distribución geográfica. Finalmente, hace falta cuantificar el grado en que esta especie es afectada por extracción con distintos fines, e identificar c las medidas que se deben tomar para proteger a sus poblaciones.

Abstract Diadematids are among the most ecologically important sea urchin families. This review presents the state of knowledge of an important member of that family, Diadema mexicanum, in the Tropical Eastern Pacific based on studies carried out mainly in Panama, Costa Rica and Mexico. Density of D. mexicanum is low, fluctuating between 0.008 and 9.5 ind m-2, however under particular conditions such as El Niño, densities reach up to 150 ind m-2. On the other hand, just one event of mass mortality at a local level has been reported for this species in Mexico. Bioerosion caused by D. mexicanum is more intense in southern reefs, whereas in localities from Mexico values are lower. According to studies carried out in Panama and Mexico it has been determined that D. mexicanum reproduces between April and November and its reproduction is influenced by ocean dynamics of winds and currents. It is necessary to extend the study areas in order to determine if populations of D. mexicanum have a similar behavior along its entire geographical distribution. Finally, it is necessary to assess the effect of extraction for different purposes on this species and identify the actions that should be taken in order to protect its populations. Rev. Biol. Trop. 63 (Suppl. 2): 135-157. Epub 2015 June 01.

Checklist of echinoderms (Echinodermata) from the Southern Mexican Pacific: a historical review / Listado de los equinodermos (Echinodermata) del Pacífico sur de México: una revisón histórica

Resumen Los equinodermos del Pacífico Sur mexicano han sido estudiados por tres siglos, sin embargo discrepancias en la nomenclatura de algunas especies han prevalecido a través del tiempo. El objetivo de este trabajo es presentar la primera lista de especies actualizada de todos los nombres válidos y sinonimias, así como una revisión histórica del estudio de los equinodermos en el Pacífico Sur mexicano. La lista de especies se basa en una exhaustiva búsqueda de registros de literatura y de especímenes depositados en colecciones de referencia. Existen 162 especies válidas de equinodermos en el Pacífico Sur mexicano incluidas en 96 géneros, 54 familias y 20 órdenes. El estado de Guerrero presentó 135 especies, Oaxaca, 94 y Chiapas, 15. Se actualizó la lista de especies y se añadieron cinco nuevos registros de especies (Microphiopholis platydisca, Ophiostigma tenue, Arbacia stellata, Thyone bidentata, Chiridota rigida) para el Pacífico Sur mexicano y uno para el Pacífico mexicano (Encope laevis). Esta lista de especies incrementa el número de especies para el área de estudio, sin embargo, los estudios sugieren que aún existen más especies por ser descubiertas.

Abstract The echinoderms of the Southern Mexican Pacific have been studied for three centuries, but discrepancies in the nomenclature of some species have pervaded through time. The objective of this work is to present the first updated checklist of all valid species and synonyms, and a historical review of the study of the echinoderms of the Southern Mexican Pacific is also presented. The checklist is based on an exhaustive published literature search and records of specimens deposited in museum and curated reference collections. There are 162 species of echinoderms in the Southern Mexican Pacific from 96 genera, 54 families and 20 orders. The State of Guerrero presented a total of 135 species, Oaxaca 94 and Chiapas 15. We updated the list and added five new records of the species (Microphiopholis platydisca, Ophiostigma tenue, Arbacia stellata, Thyone bidentata, Chiridota rigida) for the Southern Mexican Pacific and one for the Mexican Pacific (Encope laevis). This checklist expands the number of species known for the study area; nevertheless studies suggest that still more species are yet to be discovered. Rev. Biol. Trop. 63 (Suppl. 2): 87-114. Epub 2015 June 01.

Chemical defense in the red seaweed Plocamium brasiliense: spatial variability and differential action on herbivores / Defesa química na macroalga marinha vermelha Plocamium brasiliense: variabilidade espacial e diferentes ações sobre herbívoros

Species of Plocamium are known as prolific sources of halogenated secondary metabolites exhibiting few explored ecological roles. In this study the crude extracts from specimens of P. brasiliense collected in two distinct places, Enseada do Forno and Praia Rasa, Búzios, Estado do Rio de Janeiro, were evaluated as defense against the sea urchin Lytechinus variegatus and the crab Acanthonyx scutiformis. These specimens produce a similar amount of crude extract and also halogenated monoterpene compound-types, but individuals of P. brasiliense from Praia Rasa exhibit a major compound representing about 59% of the total chemicals. Natural concentrations of the crude extracts obtained from both specimens of P. brasiliense significantly inhibited the herbivory by the sea urchin L. variegatus, but had no significant effect on the feeding by A. scutiformis, a crab commonly associated to chemically defended host. Crude extract from P. brasiliense collected at Praia Rasa was more efficient as defense against L. variegatus than that crude extract from populations of this alga from Enseada do Forno, probably due to presence of a major secondary metabolite. These two studied population live under different environmental conditions, but they are only about 30 Km apart. However, it is impossible to affirm that environmental characteristics (abiotic or biotic) would be responsible for the difference of defensive potential found in the two populations of P. brasiliense studied here. Further genetic studies will be necessary to clarify this question and to explain why populations of a single species living in different but close locations can exhibit distinct chemicals.

Espécies de Plocamium são conhecidas como fontes prolíficas de metabólitos secundários halogenados com significados ecológicos pouco conhecidos. Neste trabalho extratos brutos de espécimes de P. brasiliense coletados em duas localidades distintas, Enseada do Forno e Praia Rasa, Búzios, Estado do Rio de Janeiro, foram avaliados como defesa química contra o ouriço Lytechinus variegatus e o caranguejo Acanthonyx scutiformis. Estes espécimes produzem teores similares de extrato bruto e tipos de substâncias monoterpenos halogenados, mas os indivíduos da Praia Rasa possui um componente majoritário representando 59% do total de metabólitos. Concentrações naturais dos extratos brutos destes espécimes inibiram significativamente o consumo por L. variegatus, mas não causaram qualquer efeito sobre A. scutiformis, um caranguejo comumente associado a P. brasiliense, um hospedeiro quimicamente defendido. O extrato bruto de P. brasiliense coletada na Praia Rasa foi mais eficiente como defesa frente a L. variegatus do que aquele obtido de população desta alga da Enseada do Forno, provavelmente pela presença de uma substância majoritária. Estas duas populações de P. brasiliense estudadas vivem sob diferentes condições ambientais, mas distantes somente cerca de 30 km. Entretanto, é impossível afirmar que características ambientais (abióticas ou bióticas) seriam responsáveis pelas diferenças de potencial defensivo encontrados nestas duas populações de P. brasiliense estudadas. Futuros estudos genéticos são necessários para esclarecer esta questão e para explicar porque populações de uma mesma espécie vivendo em regiões tão próximas, mas ambientalmente distintas, produzem substâncias distintas.

Diadema ascensionisMortensen, 1909 (Echinodermata: Echinoidea) is not restricted to Oceanic Islands: evidence from morphological data / Diadema ascensionisMortensen, 1909 (Echinodermata: Echinoidea) não está restrito a Ilhas Oceânicas: evidências de dados morfológicos

The genus Diadema presently consists of seven species, two of which are known from the Brazilian coast: D. antillarum and D. ascensionis. The first is usually known for shallow coastal areas, while the second was apparently restricted to oceanic islands. In February 2011, a dense population of D. ascensionis was observed on the coastal reefs of Praia do Francês (Alagoas State, northeastern Brazil). Five specimens were collected and transported to the laboratory where morphological studies of the test and pedicellariae were conducted. Subsequently, visits were made to scientific collections in order to compare and confirm species identifications. Our observations confirm the presence of tridentate pedicellariae with narrow and strongly curved valves. The axial cavity in the tips of the spines is filled with dense nonreticular tissue. This taxonomic data confirms the occurrence of D. ascensionis in coastal areas. On the coastal reefs of Praia do Francês, animals were observed from the beach to the reef formations about 200 m offshore in areas with a sandy substrate and in reef cavities, usually in clear and well illuminated waters. Solitary individuals or groups of up to 15 individuals formed dense populations in the area. We stress the importance of pedicellariae for the specific identification of the Diadematidae, considering that they are quite constant and reliable at this taxonomic level. Our results demonstrate that D. ascensionis is not restricted to insular environments and that this species may be common in shallow coastal habitats.

O gênero Diadema é composto por sete espécies, das quais duas são conhecidas para o litoral brasileiro: D. antillarum e D. ascensionis. A primeira é principalmente conhecida em áreas costeiras, enquanto que a segunda está aparentemente restrita a ilhas oceânicas. Em fevereiro de 2011, uma densa população de D. ascensionis foi observada nos recifes costeiros da Praia do Francês, no Estado de Alagoas, Região Nordeste do Brasil. Cinco espécimes foram coletados e transportados ao laboratório, onde estudos morfológicos da carapaça e das pedicelárias foram desenvolvidos. Subsequentemente, foram realizadas visitas a coleções científicas para a comparação e a confirmação da espécie. As observações, neste trabalho, evidenciaram a presença de uma pedicelária tridentada com valvas estreitas e fortemente curvadas. A cavidade axial nas pontas dos espinhos é preenchida por um denso tecido não reticular. Estes dados taxonômicos confirmam a ocorrência de D. ascensionis em áreas costeiras. Nos recifes costeiros da Praia do Francês, os animais foram observados a partir da praia em direção às formações recifais localizadas a 200 m da praia, em áreas de substrato arenoso, e nas cavidades do recife, geralmente em águas claras e bem iluminadas. Os indivíduos estavam solitários ou formando grupos de até 15 indivíduos. Destaca-se a importância das pedicelárias na sistemática dos Diadematidae, tendo em vista que as mesmas são bastante constantes e confiáveis para a identificação em nível específico. Os resultados do presente trabalho demonstram que D. ascensionis não está restrita a ambientes insulares e que esta espécie pode ser comum em habitats costeiros rasos.

Diadema ascensionis / Diadema ascensionis

The genus Diadema presently consists of seven species, two of which are known from the Brazilian coast: D. antillarum and D. ascensionis. The first is usually known for shallow coastal areas, while the second was apparently restricted to oceanic islands. In February 2011, a dense population of D. ascensionis was observed on the coastal reefs of Praia do Francês (Alagoas State, northeastern Brazil). Five specimens were collected and transported to the laboratory where morphological studies of the test and pedicellariae were conducted. Subsequently, visits were made to scientific collections in order to compare and confirm species identifications. Our observations confirm the presence of tridentate pedicellariae with narrow and strongly curved valves. The axial cavity in the tips of the spines is filled with dense nonreticular tissue. This taxonomic data confirms the occurrence of D. ascensionis in coastal areas. On the coastal reefs of Praia do Francês, animals were observed from the beach to the reef formations about 200 m offshore in areas with a sandy substrate and in reef cavities, usually in clear and well illuminated waters. Solitary individuals or groups of up to 15 individuals formed dense populations in the area. We stress the importance of pedicellariae for the specific identification of the Diadematidae, considering that they are quite constant and reliable at this taxonomic level. Our results demonstrate that D. ascensionis is not restricted to insular environments and that this species may be common in shallow coastal habitats.

O gênero Diadema é composto por sete espécies, das quais duas são conhecidas para o litoral brasileiro: D. antillarum e D. ascensionis. A primeira é principalmente conhecida em áreas costeiras, enquanto que a segunda está aparentemente restrita a ilhas oceânicas. Em fevereiro de 2011, uma densa população de D. ascensionis foi observada nos recifes costeiros da Praia do Francês, no Estado de Alagoas, Região Nordeste do Brasil. Cinco espécimes foram coletados e transportados ao laboratório, onde estudos morfológicos da carapaça e das pedicelárias foram desenvolvidos. Subsequentemente, foram realizadas visitas a coleções científicas para a comparação e a confirmação da espécie. As observações, neste trabalho, evidenciaram a presença de uma pedicelária tridentada com valvas estreitas e fortemente curvadas. A cavidade axial nas pontas dos espinhos é preenchida por um denso tecido não reticular. Estes dados taxonômicos confirmam a ocorrência de D. ascensionis em áreas costeiras. Nos recifes costeiros da Praia do Francês, os animais foram observados a partir da praia em direção às formações recifais localizadas a 200 m da praia, em áreas de substrato arenoso, e nas cavidades do recife, geralmente em águas claras e bem iluminadas. Os indivíduos estavam solitários ou formando grupos de até 15 indivíduos. Destaca-se a importância das pedicelárias na sistemática dos Diadematidae, tendo em vista que as mesmas são bastante constantes e confiáveis para a identificação em nível específico. Os resultados do presente trabalho demonstram que D. ascensionis não está restrita a ambientes insulares e que esta espécie pode ser comum em habitats costeiros rasos.

Reconstruction of Diadema mexicanum bioerosion impact on three Costa Rican Pacific coral reefs / Reconstrucción del impacto de la bioerosión de Diadema mexicanum en tres arrecifes de coral del Pacífico costarricense

The 1982-83 El Niño event produced a high coral mortality (50-90%) in several localities in the Eastern Tropical Pacific, which resulted in an outbreak of the sea urchin populations of Diadema mexicanum A. Agassiz, 1863 in some reefs, leading to an increase in coral framework bioerosion. In Costa Rica, El Niño impact varied among three of the most important coral reefs localities, being higher in Cocos Island, moderate in Caño Island, and lower in Culebra Bay; D. mexicanum densities followed the same pattern. To understand the historic role of this sea urchin on the balance between bioerosion and bioacretion, we made a reconstruction of bioerosion impact based on current patterns of carbonate ingestion by the sea urchins, growth rates and skeletal density of the main coral builders, and historical information of sea urchin population density and coral cover. The reconstruction model varied depending on locality. At Cocos Island, the effect on the reef carbonate budget ranged from negative to positive, improving coral recruitment and the recovery of the reef. At Caño Island, there was no apparent effect. In Culebra Bay, the effects ranged from a positive-neutral effect to a negative one, the latter possibly associated with an increase of eutrophic conditions that facilitated bioerosion of the coral framework. The importance of this sea urchin in reef dynamics varies with amount of reef protection, overfishing, and coastal management, and it has a large influence on the carbonate balances of the Pacific Costa Rican coral reefs.

El fenómeno de El Niño de 1982-83 produjo una alta mortalidad coralina (50-90%) en varias localidades del Pacífico Tropical Oriental, lo que en algunos arrecifes trajo como consecuencia una explosión en la poblaciones de erizos de mar, Diadema mexicanum, y por consiguiente un aumento en la bioerosión del basamento coralino. En Costa Rica, el impacto fue diferencial en tres localidades arrecifales, siendo mayor en la Isla del Coco, intermedio en la Isla del Caño, y menor en Bahía Culebra, con similares patrones en la presencia del erizo D. mexicanum. Con el fin de poder entender el papel histórico que desempeña este erizo de mar en el balance entre bioerosión y bioacreción, se reconstruyó el impacto bioerosivo basándose en patrones actuales de ingestión de carbonatos por parte del erizo, tasas de crecimiento y densidad del esqueleto coralino, y datos históricos de densidad poblacional del erizo y cobertura coralina. Los resultados de las reconstrucciones variaron dependiendo de la localidad. En la Isla del Coco, el efecto de los erizos de mar varío de un efecto negativo sobre el balance arrecifal de carbonatos a un efecto positivo, favoreciendo el reclutamiento coralino y la recuperación del arrecife. En la Isla del Caño, Diadema presentó un efecto neutro, al no tener una participación preponderante en el balance de carbonatos de esta isla. Mientras, que en Bahía Culebra, los efectos de los erizos de mar pasaron de tener un efecto positivo-neutro, a uno negativo, posiblemente asociado a un incremento en condiciones eutróficas de la bahía que están favoreciendo un incremento en la bioerosión del basamento coralino. El valor de este erizo en la dinámica arrecifal y su relación con la protección, sobrepesca, y manejo costero, posee una gran influencia en el balance de carbonatos en los arrecifes coralinos del Pacífico de Costa Rica.

Abundance, distribution and size structure of Diadema antillarum (Echinodermata: Diadematidae) in South Eastern Cuban coral reefs

The 1983-1984 mass mortality event of Diadema antillarum affected more than 93% of the total Caribbean population. Although there are no records about the status of Diadema populations before and after die-off on Cuban reefs, anecdotal information suggests that populations were struck. We analyzed spatial variation in the abundance and size structure of D. antillarum in 22 reefs sites in Jardines de la Reina, from June 2004 to September 2005. Counts of Diadema were performed in five 30x2m transects at each sampling site and sampling time, and test diameters were measured in September 2005 at the same fore reefs. Abundances were higher at reef crests (mean densities 0.08-2.18 ind./m²), while reef slope populations reached a maximum site level of 0.13 ind./m² at only one site and showed values up to three orders of magnitude lower than those from reef crests. Highest abundance occurred at the west margin of major channels between keys where larval recruitment seems to be favored by local oceanographic features and facilitated by the abundance of Echinometra lucunter. The size frequency distribution of D. antillarum indicates that recruitment began to be noticeable three years before September 2005, suggesting these populations were depleted in the past and they are recovering now. Rev. Biol. Trop. 58 (2): 663-676. Epub 2010 June 02.

La mortalidad de Diadema antillarum en 1983-1984 afectó más del 93% de la población del Caribe. Aunque no existen datos publicados sobre el estado de sus poblaciones en arrecifes cubanos antes y después de la mortalidad, se conoce anecdóticamente que fueron afectadas. En el presente trabajo se analizan las variaciones espaciales de la abundancia y estructura de tallas de D. antillarum en 22 arrecifes frontales en Jardines de la Reina, para lo cual se realizaron cinco recorridos de 30x2m en cada sitio entre Junio de 2004 y Septiembre de 2005. Las densidades de Diadema fueron mayores en las crestas arrecifales (0.08-2.18 ind./m²) mientras que en las pendientes fueron hasta tres órdenes de magnitud menor y la densidad máxima fue 0.13 ind./m². Las crestas con mayor abundancia de Diadema están ubicadas en los márgenes de las grandes pasas existentes entre cayos donde el reclutamiento parece estar favorecido por las condiciones oceanográficas locales y facilitado por la abundancia de Echinometra lucunter. La distribución de frecuencia de tallas de Diadema sugiere que el reclutamiento comenzó a ser notable aproximadamente tres años antes del muestreo, indicando que en el pasado sus poblaciones estuvieron afectadas y ahora están recuperándose.

The genomic repertoire for cell cycle control and DNA metabolism in S. purpuratus.

A search of the Strongylocentrotus purpuratus genome for genes associated with cell cycle control and DNA metabolism shows that the known repertoire of these genes is conserved in the sea urchin, although with fewer family members represented than in vertebrates, and with some cases of echinoderm-specific gene diversifications. For example, while homologues of the known cyclins are mostly encoded by single genes in S. purpuratus (unlike vertebrates, which have multiple isoforms), there are additional genes encoding novel cyclins of the B and K/L types. Almost all known cyclin-dependent kinases (CDKs) or CDK-like proteins have an orthologue in S. purpuratus; CDK3 is one exception, whereas CDK4 and 6 are represented by a single homologue, referred to as CDK4. While the complexity of the two families of mitotic kinases, Polo and Aurora, is close to that found in the nematode, the diversity of the NIMA-related kinases (NEK proteins) approaches that of vertebrates. Among the nine NEK proteins found in S. purpuratus, eight could be assigned orthologues in vertebrates, whereas the ninth is unique to sea urchins. Most known DNA replication, DNA repair and mitotic checkpoint genes are also present, as are homologues of the pRB (two) and p53 (one) tumor suppressors. Interestingly, the p21/p27 family of CDK inhibitors is represented by one homologue, whereas the INK4 and ARF families of tumor suppressors appear to be absent, suggesting that these evolved only in vertebrates. Our results suggest that, while the cell cycle control mechanisms known from other animals are generally conserved in sea urchin, parts of the machinery have diversified within the echinoderm lineage. The set of genes uncovered in this analysis of the S. purpuratus genome should enhance future research on cell cycle control and developmental regulation in this model.