Intraspecific priority effects in response to egg hatching delay in a pond-breeding salamander.

As reproduction phenologies shift with climate change, populations can experience intraspecific priority effects, wherein early hatching cohorts experience an advantage over late-hatching cohorts, resulting in altered demography. Our study objective was to identify how variation in egg hatching phenology alters intraspecific interactions in small-mouthed salamanders, Ambystoma texanum. We addressed two research questions: (Q1) How are demographic responses altered by variation in the temporal duration of hatching between cohorts, and (Q2) How does the seasonality of hatching delays affect demographic responses? We manipulated hatching phenologies of A. texanum eggs and reared larvae in outdoor mesocosms to metamorphosis. For Q1, hatching delay exhibited non-linear relationships with survival and body size, with the greatest asynchrony in cohort additions resulting in the highest mortality and largest body sizes. For Q2, hatching delay effects were stronger (i.e., survival was lower and body sizes larger) when they occurred later in the season, potentially due to temperature differences that larvae experienced. Overall, our results demonstrate that changes in intraspecific interactions due to phenological shifts can be context-dependent, depending on the strength (i.e., temporal duration) and seasonality of such processes. Identifying context-dependencies of phenological shifts will be critical for predicting changes in organismal demographics with climatic shifts.

Lipases are differentially regulated by hormones to maintain free fatty acid homeostasis for insect brain development.

BACKGROUND: Free fatty acids (FFAs) play vital roles as energy sources and substrates in organisms; however, the molecular mechanism regulating the homeostasis of FFA levels in various circumstances, such as feeding and nonfeeding stages, is not fully clarified. Holometabolous insects digest dietary triglycerides (TAGs) during larval feeding stages and degrade stored TAGs in the fat body during metamorphosis after feeding cessation, which presents a suitable model for this study. RESULTS: This study reported that two lipases are differentially regulated by hormones to maintain the homeostasis of FFA levels during the feeding and nonfeeding stages using the lepidopteran insect cotton bollworm Helicoverpa armigera as a model. Lipase member H-A-like (Lha-like), related to human pancreatic lipase (PTL), was abundantly expressed in the midgut during the feeding stage, while the monoacylglycerol lipase ABHD12-like (Abhd12-like), related to human monoacylglycerol lipase (MGL), was abundantly expressed in the fat body during the nonfeeding stage. Lha-like was upregulated by juvenile hormone (JH) via the JH intracellular receptor methoprene-tolerant 1 (MET1), and Abhd12-like was upregulated by 20-hydroxyecdysone (20E) via forkhead box O (FOXO) transcription factor. Knockdown of Lha-like decreased FFA levels in the hemolymph and reduced TAG levels in the fat body. Moreover, lipid droplets (LDs) were small, the brain morphology was abnormal, the size of the brain was small, and the larvae showed the phenotype of delayed pupation, small pupae, and delayed tissue remodeling. Knockdown of Abhd12-like decreased FFA levels in the hemolymph; however, TAG levels increased in the fat body, and LDs remained large. The development of the brain was arrested at the larval stage, and the larvae showed a delayed pupation phenotype and delayed tissue remodeling. CONCLUSIONS: The differential regulation of lipases expression by different hormones determines FFAs homeostasis and different TAG levels in the fat body during the feeding larval growth and nonfeeding stages of metamorphosis in the insect. The homeostasis of FFAs supports insect growth, brain development, and metamorphosis.

Comparative analysis of testicular fusion in Spodoptera litura (cutworm) and Bombyx mori (silkworm): Histological and transcriptomic insights.

Spodoptera litura commonly known as the cutworm, is among the most destructive lepidopteran pests affecting over 120 plants species. The powerful destructive nature of this lepidopteran is attributable to its high reproductive capacity. The testicular fusion that occurs during metamorphosis from larvae to pupa in S.litura positively influences the reproductive success of the offspring. In contrast, Bombyx mori, the silkworm, retains separate testes throughout its life and does not undergo this fusion process. Microscopic examination reveals that during testicular fusion in S.litura, the peritoneal sheath becomes thinner and more translucent, whereas in B.mori, the analogous region thickens. The outer basement membrane in S.litura exhibits fractures, discontinuity, and uneven thickness accompanied by a significant presence of cellular secretions, large cell size, increased vesicles, liquid droplets, and a proliferation of rough endoplasmic reticulum and mitochondria. In contrast, the testicular peritoneal sheath of B.mori at comparable developmental stage exhibits minimal change. Comparative transcriptomic analysis of the testicular peritoneal sheath reveals a substantial difference in gene expression between the two species. The disparity in differential expressed genes (DEGs) is linked to an enrichment of numerous transcription factors, intracellular signaling pathways involving Ca2+ and GTPase, as well as intracellular protein transport and signaling pathways. Meanwhile, structural proteins including actin, chitin-binding proteins, membrane protein fractions, cell adhesion, extracellular matrix proteins are predominantly identified. Moreover, the study highlights the enrichment of endopeptidases, serine proteases, proteolytic enzymes and matrix metalloproteins, which may play a role in the degradation of the outer membrane. Five transcription factors-Slforkhead, Slproline, Slcyclic, Slsilk, and SlD-ETS were identified, and their expression pattern were confirmed by qRT-PCR. they are candidates for participating in the regulation of testicular fusion. Our findings underscore significant morphological and trancriptomic variation in the testicular peritoneal sheath of S.litura compared to the silkworm, with substantial changes at the transcriptomic level coinciding with testicular fusion. The research provides valuable clues for understanding the complex mechanisms underlying this unique phenomenon in insects.

Isoforms of terminal selector Mamo control axon guidance during adult Drosophila memory center construction via Semaphorin-1a.

In animals undergoing metamorphosis, the appearance of the nervous system is coincidently transformed by the morphogenesis of neurons. Such morphogenic alterations are exemplified in three types of intrinsic neurons in the Drosophila memory center. In contrast to the well-characterized remodeling of γ neurons, the morphogenesis of α/ß and α'/ß' neurons has not been adequately explored. Here, we show that mamo, a BTB-zinc finger transcription factor that acts as a terminal selector for α'/ß' neurons, controls the formation of the correct axonal pattern of α'/ß' neurons. Intriguingly, specific Mamo isoforms are preferentially expressed in α'/ß' neurons to regulate the expression of axon guidance molecule Semaphorin-1a. This action directs proper axon guidance in α'/ß' neurons, which is also crucial for wiring of α'/ß' neurons with downstream neurons. Taken together, our results provide molecular insights into how neurons establish correct axonal patterns in circuitry assembly during adult memory center construction.

Tadpoles rely on mechanosensory stimuli for communication when visual capabilities are poor.

The ways in which animals sense the world changes throughout development. For example, young of many species have limited visual capabilities, but still make social decisions, likely based on information gathered through other sensory modalities. Poison frog tadpoles display complex social behaviors that have been suggested to rely on vision despite a century of research indicating tadpoles have poorly-developed visual systems relative to adults. Alternatively, other sensory modalities, such as the lateral line system, are functional at hatching in frogs and may guide social decisions while other sensory systems mature. Here, we examined development of the mechanosensory lateral line and visual systems in tadpoles of the mimic poison frog (Ranitomeya imitator) that use vibrational begging displays to stimulate egg feeding from their mothers. We found that tadpoles hatch with a fully developed lateral line system. While begging behavior increases with development, ablating the lateral line system inhibited begging in pre-metamorphic tadpoles, but not in metamorphic tadpoles. We also found that the increase in begging and decrease in reliance on the lateral line co-occurs with increased retinal neural activity and gene expression associated with eye development. Using the neural tracer neurobiotin, we found that axonal innervations from the eye to the brain proliferate during metamorphosis, with few retinotectal connections in recently-hatched tadpoles. We then tested visual function in a phototaxis assay and found tadpoles prefer darker environments. The strength of this preference increased with developmental stage, but eyes were not required for this behavior, possibly indicating a role for the pineal gland. Together, these data suggest that tadpoles rely on different sensory modalities for social interactions across development and that the development of sensory systems in socially complex poison frog tadpoles is similar to that of other frog species.

Effects of temperature on growth, development, and survival of amphibian larvae: macroecological and evolutionary patterns.

Temperature affects the rate of biochemical and physiological processes in amphibians, influencing metamorphic traits. Temperature patterns, as those observed in latitudinal and altitudinal clines, may impose different challenges on amphibians depending on how species are geographically distributed. Moreover, species' response to environmental temperatures may also be phylogenetically constrained. Here, we explore the effects of acclimation to higher temperatures on tadpole survival, development, and growth, using a meta-analytical approach. We also evaluate whether the latitude and climatic variables at each collection site can explain differences in species' response to increasing temperature and whether these responses are phylogenetically conserved. Our results show that species that develop at relatively higher temperatures reach metamorphosis faster. Furthermore, absolute latitude at each collection site may partially explain heterogeneity in larval growth rate. Phylogenetic signal of traits in response to temperature indicates a non-random process in which related species resemble each other less than expected under Brownian motion evolution (BM) in all traits, except survival. The integration of studies in a meta-analytic framework allowed us to explore macroecological and macroevolutionary patterns and provided a better understanding of the effects of climate change on amphibians.

The embryonic role of juvenile hormone in the firebrat, Thermobia domestica, reveals its function before its involvement in metamorphosis.

To gain insights into how juvenile hormone (JH) came to regulate insect metamorphosis, we studied its function in the ametabolous firebrat, Thermobia domestica. Highest levels of JH occur during late embryogenesis, with only low levels thereafter. Loss-of-function and gain-of-function experiments show that JH acts on embryonic tissues to suppress morphogenesis and cell determination and to promote their terminal differentiation. Similar embryonic actions of JH on hemimetabolous insects with short germ band embryos indicate that JH's embryonic role preceded its derived function as the postembryonic regulator of metamorphosis. The postembryonic expansion of JH function likely followed the evolution of flight. Archaic flying insects were considered to lack metamorphosis because tiny, movable wings were evident on the thoraces of young juveniles and their positive allometric growth eventually allowed them to support flight in late juveniles. Like in Thermobia, we assume that these juveniles lacked JH. However, a postembryonic reappearance of JH during wing morphogenesis in the young juvenile likely redirected wing development to make a wing pad rather than a wing. Maintenance of JH then allowed wing pad growth and its disappearance in the mature juvenile then allowed wing differentiation. Subsequent modification of JH action for hemi- and holometabolous lifestyles are discussed.

Characterization of myoinhibitory peptide signaling system and its implication in larval metamorphosis and spawning behavior in Pacific abalone.

Myoinhibitory peptides (MIPs) affect various physiological functions, including juvenile hormone signaling, muscle contraction, larval development, and reproduction in invertebrates. Although MIPs are ligands for MIP and/or sex peptide receptors (MIP/SPRs) in diverse arthropods and model organisms belonging to Lophotrochozoa, the MIP signaling system has not yet been fully investigated in mollusks. In this study, we identified the MIP signaling system in the Pacific abalone Haliotis discus hannai (Hdh). Similar to the invertebrate MIPs, a total of eight paracopies of MIPs (named Hdh-MIP1 to Hdh-MIP8), harboring a WX5-7Wamide motif, except for Hdh-MIP2, were found in the Hdh-MIP precursor. Furthermore, we characterized a functional Hdh-MIPR, which responded to the Hdh-MIPs, except for Hdh-MIP2, possibly linked with the PKC/Ca2+ and PKA/cAMP signaling pathways. Hdh-MIPs delayed larval metamorphosis but increased the spawning behavior. These results suggest that the Hdh-MIP signaling system provides insights into the unique function of MIP in invertebrates.

Neuronal E93 is required for adaptation to adult metabolism and behavior.

OBJECTIVE: Metamorphosis is a transition from growth to reproduction, through which an animal adopts adult behavior and metabolism. Yet the neural mechanisms underlying the switch are unclear. Here we report that neuronal E93, a transcription factor essential for metamorphosis, regulates the adult metabolism, physiology, and behavior in Drosophila melanogaster. METHODS: To find new neuronal regulators of metabolism, we performed a targeted RNAi-based screen of 70 Drosophila orthologs of the mammalian genes enriched in ventromedial hypothalamus (VMH). Once E93 was identified from the screen, we characterized changes in physiology and behavior when neuronal expression of E93 is knocked down. To identify the neurons where E93 acts, we performed an additional screen targeting subsets of neurons or endocrine cells. RESULTS: E93 is required to control appetite, metabolism, exercise endurance, and circadian rhythms. The diverse phenotypes caused by pan-neuronal knockdown of E93, including obesity, exercise intolerance and circadian disruption, can all be phenocopied by knockdown of E93 specifically in either GABA or MIP neurons, suggesting these neurons are key sites of E93 action. Knockdown of the Ecdysone Receptor specifically in MIP neurons partially phenocopies the MIP neuron-specific knockdown of E93, suggesting the steroid signal coordinates adult metabolism via E93 and a neuropeptidergic signal. Finally, E93 expression in GABA and MIP neurons also serves as a key switch for the adaptation to adult behavior, as animals with reduced expression of E93 in the two subsets of neurons exhibit reduced reproductive activity. CONCLUSIONS: Our study reveals that E93 is a new monogenic factor essential for metabolic, physiological, and behavioral adaptation from larval behavior to adult behavior.

Polymodal sensory perception drives settlement and metamorphosis of Ciona larvae.

The Earth's oceans brim with an incredible diversity of microscopic lifeforms, including motile planktonic larvae, whose survival critically depends on effective dispersal in the water column and subsequent exploration of the seafloor to identify a suitable settlement site. How their nervous systems mediate sensing of diverse multimodal cues remains enigmatic. Here, we uncover that the tunicate Ciona intestinalis larvae employ ectodermal sensory cells to sense various mechanical and chemical cues. Combining whole-brain imaging and chemogenetics, we demonstrate that stimuli encoded at the periphery are sufficient to drive global brain-state changes to promote or impede both larval attachment and metamorphosis behaviors. The ability of C. intestinalis larvae to leverage polymodal sensory perception to support information coding and chemotactile behaviors may explain how marine larvae make complex decisions despite streamlined nervous systems.

Ecdysone and gene expressions for chromatin remodeling, histone modification, and Broad Complex in relation to pupal commitment in Bombyx mori.

In the present study, we tried to clarify when and how pupal commitment (PT) better to use PC occurs and what is involved in the PT of Bombyx mori. To clarify this, we examined the responsiveness of a wing disc to ecdysone, referring to metamorphosis-related BR-C, development-related Myc and Wnt, and chromatin remodeling-related genes at around the predicted PT stage of the Bombyx wing disc. Wing disc responsiveness to juvenile hormone (JH) and ecdysone was examined using Methoprene and 20-hydroxyecdysone (20E) in vitro. The body weight of B. mori increased after the last larval ecdysis, peaked at Day 5 of the fifth larval instar (D5L5), and then decreased. The responsiveness of the wing disc to JH decreased after the last larval ecdysis up to D3L5. Bmbr-c (the Broad Complex of B. mori) showed enhanced expression in D4L5 wing discs with 20E treatment. Some chromatin remodeler and histone modifier genes (Bmsnr1, Bmutx, and Bmtip60) showed upregulation after being cultured with 20E in D4L5 wing discs. A low concentration of 20E is suggested to induce responsiveness to 20E in D4L5 wing discs. Bmbr-c, Bmsnr1, Bmutx, and Bmtip60 were upregulated after being cultured with a low concentration of 20E in D4L5 wing discs. The expression of Bmmyc and Bmwnt1 did not show a change after being cultured with or without 20E in D4L5 wing discs, while enhanced expression was observed with 20E in D5L5 wing discs. From the present results, we concluded that PT of the wing disc of B. mori occurred beginning on D4L5 with the secretion of low concentrations of ecdysteroids. Bmsnr1, Bmutx, Bmtip60, and BR-C are also involved.

The Neuropeptide HGAP Regulates Growth, Reproduction, Metamorphosis, Tissue Damage Repair, and Response against Starvation in Pacific Abalone.

INTRODUCTION: Neuropeptides regulate vital physiological processes in multicellular organisms, including growth, reproduction, metamorphosis, and feeding. Recent transcriptome analyses have revealed neuropeptide genes with potential roles in vertebrate and invertebrate growth and reproduction. Among these genes, haliotid growth-associated peptide (HGAP) was identified as a novel gene in abalone. METHODS: This study focused on HGAP in Pacific abalone (Haliotis discus hannai), where the complete cDNA sequence named Hdh-HGAP was identified and characterized. Samples from different experiments, such as metamorphosis, juvenile abalone growth, gonad development stages, muscle remodeling, and starvation, were collected for mRNA expression analysis. RESULTS: The sequence spans 552 bp, encoding 96 amino acids with a molecular weight of 10.96 kDa. Expression analysis revealed that Hdh-HGAP exhibited higher levels in muscle tissue. Notably, during metamorphosis, Hdh-HGAP exhibited greater expression in the trochophore, veliger, and juvenile stages than in the cell division stages. Regarding growth patterns, Hdh-HGAP was highly expressed during rapid growth compared to stunted, minimal, and normal growth. In gonadal development, Hdh-HGAP mRNA reached its highest expression level during the ripening stage, indicating a potential role in gonadal cell proliferation and maturation. The in vivo effects of GnRH on gonad development and the expression of the Hdh-HGAP neuropeptide indicate its involvement in regulating reproduction in Pacific abalone. While tissue remodeling is primarily governed by immune genes, Hdh-HGAP was also upregulated during muscle tissue remodeling. Conversely, Hdh-HGAP was downregulated during prolonged starvation. CONCLUSION: This study marks the first comprehensive exploration of the Hdh-HGAP neuropeptide gene in Pacific abalone, shedding light on its involvement in growth, reproduction, metamorphosis, tissue remodeling, and response to starvation, although regulatory mechanisms are mostly unknown.

Planktonic Duration of the Bryozoan Cyphonautes Larva and Limits on Growth Rate Imposed by Its Form-Limited Maximum Clearance Rate.

AbstractThe form of the cyphonautes larva of bryozoans changes little during development. The ciliated band that generates the feeding current increases nearly in proportion to body length, so that the maximum rate of clearing planktonic food from a volume of water becomes increasingly low relative to body protein. This development is unlike the other larvae that produce a feeding current with bands of simple cilia. The cyphonautes' growth rate has therefore been predicted to be unusually low when food is scarce. As predicted, cyphonautes larvae of a species of Membranipora starved at concentrations of food that supported growth of pluteus larvae. Comparisons between the cyphonautes and plutei of a sand dollar were for growth from first feeding to metamorphosis, with a mix of two algal species. Another comparison was for growth of cyphonautes at an advanced stage and plutei of a regular sea urchin at an early stage, with food in seawater at a reduced concentration. The low maximum clearance rate did not prevent rapid growth and development of some cyphonautes from egg through metamorphosis when food was abundant. Twenty-nine days for development to metamorphosis in the laboratory with abundant food was close to Yoshioka's estimate of larval duration from the time lag between adult zooid density and larval abundance in a population in the Southern California Bight. Despite individual variation in growth rates and other physiological and environmental influences, simple measures of larval form predicted the differences in larval performance: scarce food extended larval duration for the cyphonautes more than for plutei.

Evaluation of survival and metamorphosis of larvae of Caligus rogercresseyi (Boxshall and Bravo, 2000) (Crustacea, Copepoda) in Chile, depending on temperature, salinity and oxygen / Avaliação de sobrevivência e metamorfose de larvas de Caligus rogercresseyi (Boxshall and Bravo, 2000) (Crustacea, Copepoda) no Chile, dependendo da temperatura, salinidade e oxigênio

Abstract The present study assessed the percentage of survival and metamorphosis of larval stages of Caligus rogercresseyi (Boxshall and Bravo, 2000) nauplius I, nauplius II to and nauplius II to copepodite, conducting bioassays in triplicate with 50 larvae each, nauplius I or nauplius II, at temperature of 12 °C, 15 °C and 18 °C; salinity 20, 23, 25, 2729, 31, 33 and 35 g/L and oxygen saturation with ranges between 30-60%, 90-100% and 190 - 200%. Bioassays were performed in station Quillaipe of Fundación Chile, Puerto Montt, Chile. It is concluded that the temperature is inversely proportional to the time of metamorphosis and survival of the larvae of Caligus rogercresseyi . In salinity is observed that increased this, greater is the percentage of survival and metamorphosis is faster, while the larvae do not survive less than 20g/L. Oxygen saturation ranges indicate that the larvae do not survive at saturations between 30-60%, and it had no differences between 90-100% saturation and 190-200%.

Resumo O presente estudo avaliou a percentagem de sobrevivência e metamorfose dos estádios larvais de Caligus rogercresseyi (Boxshall and Bravo, 2000) nauplio I, nauplio II ae nauplio II a copepodita, realizando bioensaios em triplicado com 50 larvas cada, nauplio I ou nauplio II, À temperatura de 12 °C, 15 °C e 18 °C; Salinidade 20, 23, 25, 2729, 31, 33 e 35 g / L e saturação de oxigénio com variações entre 30-60%, 90-100% e 190-200%. Os bioensaios foram realizados na estação Quillaipe da Fundação Chile, Puerto Montt, Chile. Conclui - se que a temperatura é inversamente proporcional ao tempo de metamorfose e sobrevivência das larvas de Caligus rogercresseyi. Na salinidade observa-se que aumentou esta, maior é a percentagem de sobrevivência e metamorfose é mais rápida, enquanto as larvas não sobrevivem menos de 20g / L. Os intervalos de saturação de oxigénio indicam que as larvas não sobrevivem a saturações entre 30-60% e não têm diferenças entre 90-100% de saturação e 190-200%.

There is no pulp necrosis or calcific metamorphosis of pulp induced by orthodontic treatment: biological basis

ABSTRACT To biologically explain why the orthodontic treatment does not induce pulp necrosis and calcific metamorphosis of the pulp, this paper presents explanations based on pulp physiology, microscopy and pathology, and especially the cell and tissue phenomena that characterize the induced tooth movement. The final reflections are as follows: 1) the orthodontic movement does not induce pulp necrosis or calcific metamorphosis of the pulp; 2) there is no literature or experimental and clinical models to demonstrate or minimally evidence pulp alterations induced by orthodontic movement; 3) when pulp necrosis or calcific metamorphosis of the pulp is diagnosed during orthodontic treatment or soon after removal of orthodontic appliances, its etiology should be assigned to concussion dental trauma, rather than to orthodontic treatment; 4) the two pulp disorders that cause tooth discoloration in apparently healthy teeth are the aseptic pulp necrosis and calcific metamorphosis of the pulp, both only induced by dental trauma; 5) the concussion dental trauma still requires many clinical and laboratory studies with pertinent experimental models, to increasingly explain its effects on the periodontal and pulp tissues.

RESUMO Para fundamentar biologicamente por que o tratamento ortodôntico não induz necrose pulpar e metamorfose cálcica da polpa, apresentou-se explicações com base na fisiologia, microscopia e patologia pulpar, bem como, e principalmente, nos fenômenos celulares e teciduais que caracterizam a movimentação dentária induzida. As reflexões finais foram: 1) o movimento ortodôntico não induz necrose pulpar ou metamorfose cálcica da polpa; 2) não há literatura e modelos experimentais e clínicos que comprovem ou minimamente evidenciem alterações pulpares induzidas pelo movimento ortodôntico; 3) quando a necrose pulpar ou metamorfose cálcica da polpa for diagnosticada durante o tratamento ortodôntico ou logo após a remoção dos aparelhos ortodônticos, a sua etiologia deve ser atribuída ao traumatismo dentário do tipo concussão, e não ao tratamento ortodôntico; 4) as duas doenças pulpares que levam ao escurecimento coronário em dentes aparentemente hígidos são a necrose pulpar asséptica e a metamorfose cálcica da polpa, ambas induzidas exclusivamente pelo traumatismo dentário; 5) o traumatismo dentário do tipo concussão requer, ainda, muitos estudos clínicos e laboratoriais, com modelos experimentais pertinentes, para fundamentar cada vez mais os seus efeitos sobre os tecidos periodontais e pulpares.

Influence of natural settlement cues on the metamorphosis of fiddler crab megalopae, Uca vocator (Decapoda: Ocypodidae)

Megalopae of many decapod crab species accelerate their development time to metamorphosis (TTM) when exposed to natural physical and/or chemical cues characteristic of the parental habitat. In the present study, the influence of natural settlement cues on the moulting rates and development TTM in megalopae of the fiddler crab Uca vocator was investigated. The effects of mud from different habitats (including well-preserved and degraded-polluted mangrove habitats) and conspecific adult 'odours' (seawater conditioned with crabs) on the induction of metamorphosis were compared with filtered pure seawater (control). 95 to 100 percent of the megalopae successfully metamorphosed to first juvenile crab stage in all treatments, including the control. However, the development TTM differed significantly among treatments. Settlement cues significantly shortened development, while moulting was delayed in their absence. The fact that megalopae responded to metamorphosis-stimulating cues originating from both adult and non-adult benthic habitats demonstrates that settlement in this species may occur in a wider range of habitats within the mangrove ecosystem, including impacted areas.

Megalopas de muitas espécies de caranguejos decápodes aceleram seu período de desenvolvimento até a metamorfose (TOM) quando são expostas a estímulos naturais físicos e/ou químicos característicos do habitat parental. No presente estudo, a influência de estímulos naturais sobre as taxas de muda e sobre o PDM foi investigada nas megalopas do caranguejo violinista Uca vocator. Os efeitos da (i) lama de diferentes habitats (incluindo habitats de um manguezal bem preservado e de um degradado e poluído) e (ii) 'odores' dos adultos conspecíficos (água do mar acondicionada com caranguejos) sobre a indução da metamorfose foram comparados com (iii) água do mar pura e filtrada (controle). 95 a 100 por cento das megalopas realizaram a metamorfose com sucesso para o primeiro estágio de caranguejo juvenil em todos os tratamentos, incluindo o controle. No entanto, o PDM diferiu significativamente entre os tratamentos. Os estímulos encurtaram significativamente o desenvolvimento, enquanto que a muda foi retardada na ausência deles. O fato de que as megalopas responderam aos estímulos indutores da metamorfose oriundos de ambos os habitats bentônicos dos adultos e de habitats onde eles são ausentes, demonstra que o assentamento nesta espécie pode ocorrer em uma grande variedade de habitats dentro do ecossistema de manguezal, incluindo áreas impactadas.

The tadpole of Hypsiboas leptolineatus (Braun and Braun, 1977), a species in the Hypsiboas polytaenius clade (Anura; Hylidae)

The larval morphology of Hypsiboas leptolineatus was studied. The tadpole has an ovoid body in lateral view, wider than deep; snout rounded with dorsal reniform nostrils; spiracle sinistral with lateral wall attached to body; anal tube dextral; tail fins convex with acuminate tip; oral disc ventral; labial tooth row formula is 2(2)/3(1); moderately developed beaks with serrated jaw sheaths. These external oral features are compared with those of the known tadpoles in the Hypsiboas polytaenius clade. The oral cavity was studied using an electron microscope. Life history aspects are commented.

A morfologia larval de Hypsiboas leptolineatus foi estudada. O girino possui corpo ovóide em vista lateral, mais largo que alto; focinho redondo com narinas dorsais; espiráculo esquerdo, com parede lateral junto ao corpo; tubo anal destro; nadadeiras convexas, com ponta acuminada; disco oral ventral; fórmula dentária 2(2)/3(1); bico córneo moderadamente desenvolvido serrilhado. Estas características externas são comparadas com as dos outros girinos conhecidos do clado Hypsiboas polytaenius. A cavidade oral foi estudada usando microscopia eletrônica. Aspectos de história natural são comentados.

Producción de juveniles de erizo rojo Strongylocentrotus franciscamus (Echinodermata: Echinoidea) en Baja California, México / Juvenile production of the red sea urchin Strongylocentrotus franciscanus (Echinodermata: Echinoidea) in Baja California, Mexico

The red sea urchin Strongylocentrotusfranciscanus (Agassiz 1863) is harvested commercially in Baja California, Mexico, since 1970; however, in the last ten years the capture per unit effort (CPUE) has decreased from 310 kg/fishing unit/day to 120 kg/fishing unit/day. For this reason, actions were taken to develop a culture technology allowing massive production of juveniles for re-stocking natural populations or for growing them commercially. We summarize some of the basic studies and main achievements in this effort. In Baja California, considerably faster larval development (approximately 21 days) has been attained than in the US northwest coast (62 days). Spawning of red sea urchins was routinely induced with KCI while egg fertilization was performed using a 100,000-sperm/ml solution. Six microalgae species were tested and Rhodomonas sp. produced the best larval development. The mean survival rate at the end of the larval period was 25%, but results varied widely with bactch. From the feed ratios tested, best results were obtained using 7000 cel/ml during the first week of larval development, followed by 10,000 cel/ml during the second and 15,000 cel/ml during the third week. KCl proved the most consistent metamorphic inducer, regularly yielding metamorphosis percentages higher than 90%. Metamorphosis was considered complete when the functional jaw that juveniles use for first benthic feeding appeared (as soon as 20 days after induction). With this method several thousands of red sea urchin juveniles were produced. They reached up to 1.5 mm in size during the first 50 days of culture after metamorphosis, showing the great potential for mass production of this species in the laboratory

Desarrollo embrionariolarval y tiempo de metamorfosis del pez tropical Xenomelaniris brasiliensis (Pisces: Atherinidae) / Development of the tropical fish Xenomelaniris brasiliensis (Pisces: Atherinidae) from embryo to larva and time to metamorphosis

Embryoniclarval development, and metamorphosis larval time, were studied in the tropical fish Xenomelaniris brasiliensis. Twenty nine sexually mature specimens were used, 16 females (10.86 ± 1.01 cm and 7.63 ± 2.62 g) and 13 males (10.43 ± 0.57 cm and 6.54 ± 1.44 g) which produced gametes through abdominal massage. Fertilized eggs were spherical (1.18 ± 0.44 mm diameter), greenish, transparent, benthonic and vitelusrich; rugose striated chorion with numerous external filaments randomly distributed and abundant oil globules (0.11 ± 0.07 mm diameter). The embryonic development was finished at 26.36 ± 2.03ºC, 39.67 ± 0.58 PSU and pH 8.30 ± 0.10. Larvae (4.56 ± 0.97 mm total length) hatched at 143 hours and 19 minutes, with vitteline sac vestiges and a single oil globule. The larvae were fed on Brachionus plicatilis and Isochrysis galbana. After the second week Artemia nauplii were added and I. galbana maintained. Flexion started 13 days after larvae hatched (6.10 ± 1.54 mm total length) and was completed 32 days later (11.25 ± 1.87 mm total length) with the hipural complex completely developed. In conclusion, X. brasiliensis showed direct larval development and started larval metamorphosis (13.08 ± 2.07 mm total length) to juvenile 40 days after hatching

Se describe el desarrollo embrionario y larval hasta la metamorfosis de Xenomelaniris brasiliensi. Un total de 29 ejemplares sexualmente maduros, 16 hembras (10.86 ± 1.01 cm y 7.63 ± 2.62 g) y 13 machos (10.43 ± 0.57 cm y 6.54 ± 1.44 g), liberaron sus productos sexuales mediante masaje abdominal. Los huevos fértiles fueron esféricos de 1.18 ± 0.44 mm de diámetro, verdosos, translúcidos, bentónicos, ricos en vitelo, corion rugoso y estriado, con numerosos filamentos coriónicos, distribuidos aleatoriamente por toda la superficie externa y numerosas gotas lipídicas con un diámetro de 0.11 ± 0.07 mm. El desarrollo embrionario se realizó a 26.36 ± 2.03 ºC, 39.67 ± 0.58 PSU y pH 8.30 ± 0.10 eclosionando larvas de 4.56 ± 0.97 mm a las 143 hrs: 19 min, con vestigios del saco vitelino y una gota lipídica interna. Las larvas fueron alimentadas diariamente con Brachionus plicatilis e Isochrysis galbana, a partir de la segunda semana se incorporó nauplios de Artemia, manteniendo la adición diaria de I. galbana. A los 13 días después de la eclosión de larvas (6.10 ± 1.54 mm) se inició la flexión, completándose a los 32 días (11.25 ± 1.87 mm) con un complejo hipural completamente desarrollado. Se concluye que X. brasiliensis presentó desarrollo larval directo, iniciándose la metamorfosis de larva (13.08 ± 2.07) a juvenil a los 40 días de edad

The Tadpoles of Hyla rufitela (Anura: Hylidae)

The validity of the published description of Hyla rufitela is questioned because the origin of the described tadpoles does not correspond to the distribution of this species. The present description, based on tadpoles that were hatched from two egg masses from the Caribbean lowland of Costa Rica, includes tadpoles raised to adult frogs to verify the species. The newly described tadpoles differ from the previously described and illustrated ones not only in color but also by its more slender body shape (body height:body length, 0.43:0.47), the more slender tail (% tail length of total length, 69%:63%), the more conspicuous spiracle and its position, as well as by the larger oral disk width (oral disk width:body width, 0.44:~0.33). The young tadpoles continually ingest mud as is typical of bottom feeders. Nevertheless, older larvae feed on plant material like rotting mellow leaves of Piper auritum. The tadpoles metamorphosed between 44 and 114 days (x=80.3 days) under the described breeding conditions

La existencia de dudas sobre la validez de la descripción de las larvas de Hyla rufitela realizada por Duellman en 1970 motivaron una nueva descripción con base en renacuajos criados de dos masas de huevos de H. rufitela de la zona caribeña de Costa Rica. Algunos se criaron hasta la edad adulta para verificar la identidad de la especie. Los renacuajos difieren de la descripción e ilustración original por su color, la esbeltez (proporción entre altura y longitud del cuerpo 0.43 vs. 0.47), la cola más delgada (% longitud de la cola de la longitud total del renacuajo 69% vs. 63%), por la posición y forma conspicua del espiráculo, por el disco oral más ancho (ancho del disco: ancho del cuerpo 0.44 vs. ~ 0.33) y por algunos datos alométricos. Las larvas pequeñas permanecen en el fondo alimentándose con materia orgánica del lodo. Los renacuajos mayores se alimentan de material vegetal en descomposición. En cautiverio las renacuajos terminaron su desarrollo en 44-114 días (promedio 80.3 días)