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1.
South Med J ; 115(10): 745-751, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36191910

RESUMO

OBJECTIVES: This study aimed to describe, using a statewide trauma registry, the incidence, trends, and injuries for tree stand falls while deer hunting in Pennsylvania. METHODS: Falls from tree stands were abstracted from the Pennsylvania Trauma Systems Foundation registry (1990-2017) and combined with the number of licensed deer hunters, deer hunting days, and deer hunting-related shooting incidents (HRSIs) provided by the Pennsylvania Game Commission to calculate tree stand fall and HRSI rates (per 1 million deer hunting days) and age-group specific fall rates (per 100,000 licensed deer hunters). Poisson regression was used to assess the significance of the annual and age group rate trends (significance P < 0.05). Case fatality rate (percentage of number of deaths per number of injured hunters) also was calculated. RESULTS: There were 1229 victims of tree stand falls and 560 victims of HRSIs between 1990 and 2017. Fall rates increased from 1.5 to 10.4 (P < 0.0001), and HRSI rates decreased from 4.9 to 1.2 (P = 0.001). Fall rates surpassed HRSI rates in 1999 and increased with advancing age (P = 0.007), peaking at 7.2 for hunters aged 50 to 59 years. Most (77%) injured hunters sustained multiple injuries. The case fatality rate was only 0.8%, but 26% of the injured hunters had a dependent functional limitation at hospital discharge. CONCLUSIONS: Tree stand falls are now the leading cause of Pennsylvania deer hunting accidents. Fall victims usually sustain multiple nonfatal but often disabling injuries. Study findings support the need for surveillance of these accidents and additional tree stand safety education.


Assuntos
Cervos , Árvores , Animais , Humanos , Caça , Pennsylvania/epidemiologia , Recreação
2.
J Environ Qual ; 49(4): 1011-1019, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016487

RESUMO

The pharmaceutical compound carbamazepine (CBZ) is a contaminant of emerging concern. Wastewater irrigation can be a long-term, frequent source of CBZ; therefore, understanding the fate and transport of CBZ as a result of wastewater reuse practices has important environmental implications. The objective of this study was to estimate long-term soil transport of CBZ originating from treated wastewater irrigation on plots under different land uses. Field data from a previous study comparing CBZ concentrations in soil under different land uses were used in numerical modeling with HYDRUS-2D for the estimation of CBZ soil transport during 20 yr of irrigation with treated wastewater. This study showed high CBZ retention in soil under all investigated land uses. Adequate modeling results were obtained by using soil organic carbon-water partitioning coefficient (Koc ) for the CBZ linear sorption coefficient (Kd ) estimation, yet an underestimation of CBZ concentration in soil was still noted. Thus, results suggest that, although highly important, organic carbon content is probably not the only soil property governing CBZ sorption at this site, indicating the potential research perspective. Modeling results showed wastewater irrigation containing CBZ for 20 yr increased the CBZ concentration in the soil profile and its vertical movement, with the slowest vertical transport rate occurring on the forested plots. Overall results suggest that a beneficial management practice could be to increase soil organic carbon (e.g., compost addition) when using treated wastewater for irrigation in order to retain CBZ in the surface soil and thus limit its leaching through the soil profile.


Assuntos
Poluentes do Solo/análise , Águas Residuárias , Carbamazepina/análise , Carbono , Solo , Eliminação de Resíduos Líquidos
3.
Genome Biol Evol ; 12(10): 1681-1693, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32653903

RESUMO

Apoptosis is a fundamental feature of multicellular animals and is best understood in mammals, flies, and nematodes, with the invertebrate models being thought to represent a condition of ancestral simplicity. However, the existence of a leukemia-like cancer in the softshell clam Mya arenaria provides an opportunity to re-evaluate the evolution of the genetic machinery of apoptosis. Here, we report the whole-genome sequence for M. arenaria which we leverage with existing data to test evolutionary hypotheses on the origins of apoptosis in animals. We show that the ancestral bilaterian p53 locus, a master regulator of apoptosis, possessed a complex domain structure, in contrast to that of extant ecdysozoan p53s. Further, ecdysozoan taxa, but not chordates or lophotrochozoans like M. arenaria, show a widespread reduction in apoptosis gene copy number. Finally, phylogenetic exploration of apoptosis gene copy number reveals a striking linkage with p53 domain complexity across species. Our results challenge the current understanding of the evolution of apoptosis and highlight the ancestral complexity of the bilaterian apoptotic tool kit and its subsequent dismantlement during the ecdysozoan radiation.


Assuntos
Apoptose/genética , Genes p53 , Genoma , Mya/genética , Filogenia , Animais
5.
Elife ; 52016 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-27218454

RESUMO

Transcriptome and genome data from twenty stony coral species and a selection of reference bilaterians were studied to elucidate coral evolutionary history. We identified genes that encode the proteins responsible for the precipitation and aggregation of the aragonite skeleton on which the organisms live, and revealed a network of environmental sensors that coordinate responses of the host animals to temperature, light, and pH. Furthermore, we describe a variety of stress-related pathways, including apoptotic pathways that allow the host animals to detoxify reactive oxygen and nitrogen species that are generated by their intracellular photosynthetic symbionts, and determine the fate of corals under environmental stress. Some of these genes arose through horizontal gene transfer and comprise at least 0.2% of the animal gene inventory. Our analysis elucidates the evolutionary strategies that have allowed symbiotic corals to adapt and thrive for hundreds of millions of years.


Assuntos
Adaptação Fisiológica/genética , Antozoários/genética , Calcificação Fisiológica/genética , Genoma , Genômica/métodos , Redes e Vias Metabólicas/genética , Animais , Antozoários/classificação , Antozoários/crescimento & desenvolvimento , Antozoários/metabolismo , Evolução Biológica , Carbonato de Cálcio/química , Carbonato de Cálcio/metabolismo , Recifes de Corais , Transferência Genética Horizontal , Concentração de Íons de Hidrogênio , Luz , Fotossíntese/fisiologia , Filogenia , Espécies Reativas de Nitrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Simbiose/fisiologia , Temperatura
6.
Mitochondrial DNA A DNA Mapp Seq Anal ; 27(5): 3553-4, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26260175

RESUMO

We have sequenced and characterized the complete mitochondrial genome of the soft-shell clam, Mya arenaria, an important organism for environmental toxicology and aquaculture. Mya arenaria is located in the taxonomic order Myoida, which lacks any member with a completely annotated mitogenome. The M. arenaria mitochondrial genome is 17 947 bp in length. Like most marine bivalves, the circular mitogenome codes entirely on the heavy strand, with no introns. As with other bivalves, the gene order of the mitochondrion is highly rearranged. The mitogenome contains 12 protein-coding genes but ATP8 is missing, consistent with about half of all bivalve genera. Twenty-three tRNAs were identified. Phylogenetic analysis shows that M. arenaria is related most closely with the bivalves Sinonovacula constricta, and Moerella iridescens, of the infraclass Euheterodonta (unassigned). This, along with the close grouping of the phylogenetic trees, confirms a close tie between Myoida and Euheterodonta (unassigned).


Assuntos
Genoma Mitocondrial , Mitocôndrias/genética , Mya/genética , Análise de Sequência de DNA/métodos , Animais , Composição de Bases , Ordem dos Genes , Genes de RNAr , Tamanho do Genoma , Filogenia , RNA de Transferência/genética
7.
J Environ Qual ; 41(4): 1263-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22751070

RESUMO

Due to its resistance to many wastewater treatment processes, the antiepileptic drug carbamazepine (CBZ) is routinely found in wastewater effluent. Wastewater irrigation is an alternative to stream discharge of wastewater effluent, which utilizes the soil as a tertiary filter to remove excess nutrients and has the potential to remove pharmaceutical compounds. Previous data suggest that CBZ is strongly sorbed to soil; however, it is unknown what its fate is for long periods of irrigation and if land use affects its distribution. Therefore, the objectives of our research were to characterize CBZ concentrations in soils that have been receiving wastewater irrigation for >25 yr under three different land uses: cropped, grassed, and forested. Triplicate soil cores were collected at each of the land uses to a depth of 120 cm. Extractions for CBZ were performed using 5-g soil samples and 20 mL of acetonitrile. The extracted solutions were analyzed on a liquid chromatograph tandem mass spectrometer. The samples were also analyzed for supporting information such as organic carbon, pH, and electrical conductivity. Results suggest that there is accumulation of the CBZ in the surface soils, which have the highest organic carbon content. Average concentrations of CBZ in the surface soils were 4.92, 2.9, and 1.92 ng g, for the forested, grassed, and cropped land uses, respectively. The majority of the CBZ was found in the upper 30 cm of the profile. Our results suggest that the soils adsorb CBZ and slow its movement into groundwater, compared to the movement of nonadsorbed chemicals.


Assuntos
Anticonvulsivantes/química , Carbamazepina/química , Monitoramento Ambiental , Solo/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Produtos Agrícolas , Poaceae , Poluentes do Solo/química , Árvores
8.
Adv Mar Biol ; 59: 1-36, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21724017

RESUMO

The human p53 tumour suppressor protein is inactivated in many cancers and is also a major player in apoptotic responses to cellular stress. The p53 protein and the two other members of this protein family (p63, p73) are encoded by distinct genes and their functions have been extensively documented for humans and some other vertebrates. The structure and relative expression levels for members of the p53 superfamily have also been reported for most major invertebrate taxa. The functions of homologous proteins have been investigated for only a few invertebrates (specifically, p53 in flies, nematodes and recently a sea anemone). These studies of classical model organisms all suggest that the gene family originally evolved to mediate apoptosis of damaged germ cells or to protect germ cells from genotoxic stress. Here, we have correlated data from a number of molluscan and other invertebrate sequencing projects to provide a framework for understanding p53 signalling pathways in marine bivalve cancer and stress biology. These data suggest that (a) the two identified p53 and p63/73-like proteins in soft shell clam (Mya arenaria), blue mussel (Mytilus edulis) and Northern European squid (Loligo forbesi) have identical core sequences and may be splice variants of a single gene, while some molluscs and most other invertebrates have two or more distinct genes expressing different p53 family members; (b) transcriptional activation domains (TADs) in bivalve p53 and p63/73-like protein sequences are 67-69% conserved with human p53, while those in ecdysozoan, cnidarian, placozoan and choanozoan eukaryotes are ≤33% conserved; (c) the Mdm2 binding site in the transcriptional activation domain is 100% conserved in all sequenced bivalve p53 proteins (e.g. Mya, Mytilus, Crassostrea and Spisula) but is not present in other non-deuterostome invertebrates; (d) an Mdm2 homologue has been cloned for Mytilus trossulus; (e) homologues for both human p53 upstream regulatory and transcriptional target genes exist in molluscan genomes (missing are ARF, CIP1 and BH3 only proteins) and (f) p53 is demonstrably involved in bivalve haemocyte and germinoma cancers. We usually do not know enough about the molecular biology of marine invertebrates to address molecular mechanisms that characterize particular diseases. Understanding the molecular basis of naturally occurring diseases in marine bivalves is a virtually unexplored aspect of toxicoproteomics and genomics and related drug discovery. Additionally, increases in coastal development and concomitant increases in aquatic pollutants have driven interest in developing models appropriate for evaluating potential hazardous compounds or conditions found in the aquatic environment. Data reviewed in this study are coupled with recent developments in our understanding the molecular biology of the marine bivalve p53 superfamily. Taken together, they suggest that both structurally and functionally, bivalve p53 family proteins are the most highly conserved members of this gene superfamily so far identified outside of higher vertebrates and invertebrate chordates. Marine bivalves provide some of the most relevant and best understood models currently available for experimental studies by biomedical and marine environmental researchers.


Assuntos
Bivalves/metabolismo , Modelos Animais de Doenças , Neoplasias/metabolismo , Estresse Fisiológico/fisiologia , Proteína Supressora de Tumor p53/metabolismo , Animais , Proteínas Reguladoras de Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Bivalves/genética , Monitoramento Ambiental/métodos , Neoplasias/genética , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/genética
9.
Proc Biol Sci ; 278(1723): 3371-9, 2011 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-21450733

RESUMO

All echinoderms have unique hydraulic structures called tube feet, known for their roles in light sensitivity, respiration, chemoreception and locomotion. In the green sea urchin, the most distal portion of these tube feet contain five ossicles arranged as a light collector with its concave surface facing towards the ambient light. These ossicles are perforated and lined with pigment cells that express a PAX6 protein that is universally involved in the development of eyes and sensory organs in other bilaterians. Polymerase chain reaction (PCR)-based sequencing and real time quantitative PCR (qPCR) also demonstrate the presence and differential expression of a rhabdomeric-like opsin within these tube feet. Morphologically, nerves that could serve to transmit information to the test innervate the tube feet, and the differential expression of opsin transcripts in the tube feet is inversely, and significantly, related to the amount of light that tube feet are exposed to depending on their location on the test. The expression of these genes, the differential expression of opsin based on light exposure and the unique morphological features at the distal portion of the tube foot strongly support the hypothesis that in addition to previously identified functional roles of tube feet they are also photosensory organs that detect and respond to changes in the underwater light field.


Assuntos
Estruturas Animais/fisiologia , Extremidades/fisiologia , Proteínas do Olho/metabolismo , Proteínas de Homeodomínio/metabolismo , Transdução de Sinal Luminoso/fisiologia , Opsinas/metabolismo , Fatores de Transcrição Box Pareados/metabolismo , Proteínas Repressoras/metabolismo , Ouriços-do-Mar/fisiologia , Sequência de Aminoácidos , Estruturas Animais/metabolismo , Animais , Sequência de Bases , Primers do DNA , Proteínas do Olho/genética , Proteínas de Homeodomínio/genética , Imuno-Histoquímica , Microscopia Eletrônica , Dados de Sequência Molecular , Opsinas/genética , Fator de Transcrição PAX6 , Fatores de Transcrição Box Pareados/genética , Filogenia , Reação em Cadeia da Polimerase , Reação em Cadeia da Polimerase em Tempo Real , Proteínas Repressoras/genética , Ouriços-do-Mar/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNA
10.
J Environ Qual ; 39(2): 744-8, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20176847

RESUMO

Despite improvements in analytical techniques for detecting hormones, such as estrogen in environmental samples, there is conflicting information regarding sample filtration before analyses. In addition, there is little information about estrogen adsorption onto other common laboratory materials, including glass, plastic, or stainless steel. Therefore, we have quantified the adsorption of three different types of estrogen (estrone [E1], 17alpha-ethynylestradiol [EE2], and 17beta-estradiol [E2]) onto 11 different types of filters and six other types of materials used for sample storage and laboratory experiments. We observed significant (p < 0.05) differences in the amount of estrogen adsorbed to the different filters. Glass fiber filters adsorbed the lowest amount, whereas nylon filters adsorbed nearly all of the estrogen that contacted them during filtration. Stainless steel and polycarbonate also adsorbed significant amounts of E1, E2, and EE2. The materials with which estrogen comes into contact should be chosen carefully to avoid potential losses due to sorption.


Assuntos
Estrogênios/análise , Adsorção , Estrogênios/química , Vidro , Cimento de Policarboxilato , Politetrafluoretileno , Cloreto de Polivinila , Manejo de Espécimes , Aço Inoxidável
11.
Biol Bull ; 217(3): 306-12, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20040754

RESUMO

The purple sea urchin, Strongylocentrotus purpuratus, is the only non-chordate deuterostome model with a fully sequenced genome. Chromosomal localization of individual genes and resulting gene maps are unavailable for this or for any sea urchin. As a result, the purple sea urchin genome has not been mapped onto specific chromosomes and remains inaccessible to genome-wide approaches addressing questions that require positional information for particular genes. Here we describe the first successful methods for karyotyping and localizing specific gene loci on chromosomes of Strongylocentrotus purpuratus and those of the phylogenetically related Strongylocentrotus droebachiensis. Both species have 42 chromosomes in their diploid genomes (n = 21). There are 2 large, 8 medium, and 10 small pairs, plus one putative sex pair. In both species, bindin genes were localized to 2 pair of homologous chromosomes by fluorescent in situ hybridization. Fluorescently labeled bacterial artificial chromosome clones generated from S. purpuratus for the functionally related genes brachyury, foxa, and foxb were localized to different chromosomes. Our protocols provide previously unavailable tools for developing a gene map for the purple sea urchin genome.


Assuntos
Mapeamento Cromossômico/métodos , Cromossomos , Strongylocentrotus/genética , Animais , Cariotipagem/métodos
12.
Cell Cycle ; 7(15): 2286-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18677101

RESUMO

As Jessani et al.,(1) point out development of cell and animal models that accurately depict human tumorigenesis remains a major goal of cancer research. Clam cancer offers significant advantages over traditional models for genotoxic and non-genotoxic preclinical analysis of treatments for human cancers with a similar molecular basis. The naturally occurring clam model closely resembles an outbreeding, human clinical population and provides both in vitro and in vivo alternatives to those generated from inbred mouse strains or by intentional exposure to known tumor viruses. Fly and worm in vivo models for adult human somatic cell cancers do not exist because their adult somatic cells do not divide. Clam cancer is the best characterized, naturally occurring malignancy with a known molecular basis remarkably similar to those observed in several unrelated human cancers where both genotoxic and non-genotoxic strategies can restore the function of wild-type p53. To further emphasize this point of view, we here demonstrate a p53-induced, mitochondrial-directed mechanism for promoting apoptosis in the clam cancer model that is similar to one recently identified in mammals. Discerning the molecular basis for naturally occurring diseases in non-traditional models and correlating these with related molecular mechanisms responsible for human diseases is a virtually unexplored aspect of toxico-proteomics and genomics and related drug discovery.


Assuntos
Doenças dos Animais/genética , Braquiúros/genética , Doença/etiologia , Neoplasias/genética , Transdução de Sinais/genética , Animais , Antineoplásicos/uso terapêutico , Apoptose/genética , Dano ao DNA/genética , Dano ao DNA/fisiologia , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Dados de Sequência Molecular , Neoplasias/tratamento farmacológico , Piridinas/uso terapêutico , Tiazóis/uso terapêutico , Proteína Supressora de Tumor p53/metabolismo
13.
Biol Bull ; 209(1): 31-48, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16110092

RESUMO

Here we characterize the germinal epithelia of both sexes of Strongylocentrotus droebachiensis, the green sea urchin, throughout its annual gametogenic cycle, using light and electron microscopy and cytochemistry. In both sexes, germinal epithelia include two interacting cellular populations: nutritive phagocytes (NPs) and germ cells. After spring spawning, NPs accumulate nutrients; amitotic oogonia and often mitotic spermatogonia occur in clusters beneath NPs; and subsequent gametogenic stages are residual or absent. During the summer, NP nutrients are mobilized for use in vitellogenesis by residual primary oocytes or to support limited spermatogenesis. In addition, some residual primary oocytes may degenerate and be phagocytized by NPs. Significant nutrient mobilization from NPs and substantial gonial cell mitoses (indicative of new gametogenesis) occur in the fall. In both sexes, all of these changes are facilitated by NPs that form basal incubation chambers near the gonadal wall and within which germ cells are surrounded by nutrients released from the NPs. In females, germ cells at several stages of gametogenesis may be housed in separate chambers in the same NP. Primary oocytes also carry out jelly coat formation, meiosis, and cortical granule translocation within NP incubation chambers. In males, many NPs cooperate to provide large continuous chambers that contain spermatogenic cells at diverse stages. In both sexes these chambers persist throughout the year and isolate gametogenesis from the gonadal lumen. NPs become slender and shorten as their nutrients are depleted. Ova or spermatozoa are stored in the gonadal lumen. Post-spawning, NPs phagocytize differentiated germ cells while simultaneously enclosing intact gonial and residual gametogenic cells in basal chambers near the gonadal wall. In light of our observations, we suggest investigating proteins that may be important in the structural, phagocytic, and nutritive functions of NPs and for which corresponding genes have already been identified in the genome of S. purpuratus, the closely related purple sea urchin.


Assuntos
Gametogênese/fisiologia , Óvulo/fisiologia , Fagócitos/fisiologia , Espermatozoides/fisiologia , Strongylocentrotus/fisiologia , Animais , Feminino , Masculino , Ovário/citologia , Estações do Ano , Strongylocentrotus/citologia , Testículo/citologia
15.
Environ Health Perspect ; 110(4): 377-85, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11940455

RESUMO

The cell-cycle checkpoint protein p53 both directs terminal differentiation and protects embryos from DNA damage. To study invertebrate p53 during early development, we identified three differentially expressed p53 family members (p53, p97, p120) in the surf clam, Spisula solidissima. In these mollusks, p53 and p97 occur in both embryonic and adult tissue, whereas p120 is exclusively embryonic. We sequenced, cloned, and characterized p120 cDNA. The predicted protein, p120, resembles p53 across all evolutionarily conserved regions and contains a C-terminal extension with a sterile alpha motif (SAM) as in p63 and p73. These vertebrate forms of p53 are required for normal inflammatory, epithelial, and neuronal development. Unlike clam p53 and p97, p120 mRNA and protein levels are temporally expressed in embryos, with mRNA levels decreasing with increasing p120 protein (R(2) = 0.97). Highest surf clam p120 mRNA levels coincide with the onset of neuronal growth. In earlier work we have shown that neuronal development is altered by exposure to polychlorinated biphenyls (PCBs), a neurotoxic environmental contaminant. In this study we show that PCBs differentially affect expression of the three surf clam p53 family members. p120 mRNA and protein are reduced the most and earliest in development, p97 protein shows a smaller and later reduction, and p53 protein levels do not change. For the first time we report that unlike p53 and p97, p120 is specifically embryonic and expressed in a time-dependent manner. Furthermore, p120 responds to PCBs by 48 hr when PCB-induced suppression of the serotonergic nervous system occurs.


Assuntos
Bivalves/fisiologia , Dano ao DNA , Poluentes Ambientais/efeitos adversos , Regulação da Expressão Gênica , Genes p53 , Bifenilos Policlorados/efeitos adversos , Sequência de Aminoácidos , Animais , Western Blotting , DNA Complementar/genética , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Homologia de Sequência de Aminoácidos
16.
J Morphol ; 210(1): 1-11, 1991 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29865533

RESUMO

The madreporite regions of two species of starfish were examined by high-resolution light microscopy and transmission electron microscopy. In both, the madreporite gutter epithelium is predominantly composed of ciliated cells, each bearing a single elongate cilium and numerous microvilli that support and are embedded in cuticle. Fine, contractile pores (10-12 µm) open from the gutters into canals that descend mainly to the underlying ampulla and stone canal. Cells at the pore openings lack cuticle, have rounded, sometimes protruding apices, and bear intermeshing cilia that extend outward through the pores. Below them, the pore canal is lined with irregular, granule-containing ciliated cells possessing retractable apical head pieces and secretory cells containing clusters of unstainable vesicles. Above the basal lamina here and elsewhere is a well-developed nerve plexus. Where the pore canals open into the ampulla and connecting axial sinus, the ciliated cells are more cuboidal, vesiculated secretory cells are absent, and free coelomocytes are numerous. The stone canal is lined with tall, densely packed ciliated cells with numerous microvilli and long iuminal extensions. Cells on its central ridge tend to form choanocyte-like collars. The stone canal appears to be a strong ciliary pump that draws fluid from the axial sinus and madreporite pores. It is likely that the complex form of the madreporite gutters and pore canals provides multiple levels of coordinated defense against the entry of undesirable materials, and probably satisfaction of much of the nutritional needs of the parts from incoming and recirculated fluid.

17.
J Morphol ; 179(3): 243-262, 1984 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30041503

RESUMO

The fine structure of the male reproductive system of the hermaphroditic brittle-star, Amphipholis squamata, has been studied in specimens from both the Pacific coast (Washington) and the Atlantic coast (New Hampshire). Each testis is a small (100-µm) sphere and is attached to the internal wall of the bursa by peritoneal suspensor cells. Occasional flagellated cells are found on the external surface of the testis. The testicular wall of A. squamata is a multilayered structure, similar to that of other ophiuroids, but the hemal sinus is PAS negative in this species. Germinal cells are surrounded throughout their development by the filopodia of interstitial cells. Adjacent interstitial cells are interconnected, and thus form a structural network within the testis. Positionally and functionally, the interstitial cells resemble Sertoli cells; however, their origin, behavior and ultrastructure are different in many ways. Spermatogenesis includes a series of cyclical changes (aspermatogenic phase, proliferative phase, differentiative phase, and evacuative phase). Within a single testis, the resulting production of sperm is in short pulses, but if all 10 testes are taken together, sperm are produced continuously throughout the year. The events of spermiogenesis closely follow those that have been described in other echinoderms. However, we have provided new information on the release of excess cell membranes and the fusion process of mitochondria. The mature spermatozoa of A. squamata are flagellated and motile, and have "primitive" structural features, in spite of the fact that they fertilize the eggs inside the genital bursae. The spermatozoa do not, as was previously thought, enter the bursa by rupture of the adjacent walls. Instead, they are ejaculated through a gonoduct into the rapid incurrent flow of water entering the bursa. The locomotion of the spermatozoa is in eccentric spirals, due to the unusually large angle at which the flagellum is inserted into the base of the sperm.

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