Exogastrulation and interference with the expression of major yolk protein by estrogens administered to sea urchins

Comparative Transcriptome Analysis of Differentially Expressed Genes in the Testis and Ovary of Sea Urchin (Strongylocentrotus intermedius)

The quality of sea urchin gonad is important to consumers with high standards for nutrition and taste. However, few studies have been conductedon the molecular mechanisms that determine the quality of male and female sea urchins. In this study, our goal was to understand the differences and characteristics of gonad quality between sea urchin (Strongylocentrotus intermedius) males and females. The transcriptomes of males and females were obtained, with totals of 43,797,146 and 56,222,782 raw reads, respectively, comprising 128,979 transcripts and 85,745 unigenes. After comparative transcriptome analysis, a total of 6736 differentially expressed genes (DEGs) between the males and females were identified, of which 2950 genes were up-regulated and 3786 genes were down-regulated in males. We compared the expression of twelve DEGs with significant differences their expression levels and functional annotations to confirm the reliability of the RNA-Seq data. Five DEGs related to gonadal quality were found through enrichment analysis of KEGG pathways: 17β-HSD8, PGDH, FAXDC2, C4MO, and PNPLA7. Our study analyzes genes related to the taste and flavor of sea urchin gonads among the sexes and provides reference sequences and fundamental information concerning the nutrition and taste of S. intermedius gonads.

Initial report of γ-aminobutyric acidergic locomotion regulatory system and its 3-mercaptopropionic acid-sensitivity in metamorphic juvenile of sea urchin, Hemicentrotus pulcherrimus

The γ-aminobutyric acid (GABA) signal transmission system (GSTS) contributes to larval swimming through the regulation of ciliary beating. However, whether this system also contributes to the primary podia (PP)-generated motility of juveniles remained unclear. The present study aimed to elucidate the involvement of the GSTS in the motility of metamorphic juveniles (juveniles) (1) by immunohistochemically elucidating the location of molecular constituents of the PP, and (2) by inhibiting the activity of GΑΒΑ decarboxylase (GAD) with 3-mercaptopropionic acid (3-MPA). During metamorphosis, the echinus rudiment protrudes its PP out of the body surface in 8-arm plutei. The PP expresses immunopositive signal (-IS) of GAD, GABA, GABA_A receptor and tropomyosin, and is constituted with the GABA-IS negative distal tip and the GABA/GAD-IS gaiter region. The latter radiates distal projections to the disc that contains a GAD-IS cellular network. The juvenile body cavity houses a GABA/βIII-tubulin-IS Penta-radial ring (PrR) that extends branches into each PP and several bridges to the GAD/GABA-IS Penta-radial plate (PrP) on the oral side but does not reach to the gaiter region. 3-MPA reversibly inhibits the juvenile motility and GABA-IS expression in the PrR/PrP complex. This indicates that the complex is the major contributor to the GABAergic motility in juveniles.

Long-term preservation of echinoderm sperm under non-cryo condition for ecotoxicological bioassay

The preservation of sea urchin gametes was examined to make them more convenient material for research and education, especially on the embryology and ecotoxicology field. The possibility of egg preservation for enough period, two weeks to one month, were reported (Epel et al., 2004; Kiyomoto et al., 2014). The sperm storage is usually done without seawater (dry sperm) for several days. This storage period is lengthened by the addition of antibiotics up to 10 days (Hata, 1998). To maximize the preserved period, we examined the dilution or replacement of seminal plasma with seawater containing antibiotics. Because the activation of sperm is induced by dilution, the condition to inhibit flagella motility was also investigated. Neither high potassium nor low pH improved the period of sperm preservation. The dilution of dry sperm around 100 times with normal seawater containing antibiotics was enough to keep the motility and fertilization ability for longer period, where sperm motility was prevented possibly by the effect of carbon dioxide.

Regulamentação do estrogênio sintético 17α-etinilestradiol em matrizes aquáticas na Europa, Estados Unidos e Brasil

O estrogênio sintético 17α-etinilestradiol, principal componente utilizado em formulações de contraceptivos orais, tem sido apontado como um dos principais compostos responsáveis por provocar efeitos adversos no sistema endócrino de várias espécies. O objetivo deste estudo foi analisar o estado da arte dos dispositivos legais e normativos referentes ao controle desse estrogênio sintético nas águas da Europa e dos Estados Unidos, e traçar um paralelo com a realidade brasileira. No geral, os países têm buscado ampliar a regulamentação e monitoramento de alguns micropoluentes emergentes que antes não eram objeto de atenção por parte dos dispositivos legais. A Europa está mais avançada no que tange à qualidade dos corpos hídricos, enquanto que nos Estados Unidos esta substância é alvo de regulamentação apenas para a água destinada ao consumo humano. No Brasil, ainda não há nenhum dispositivo legal ou normativo que aborde esse estrogênio, o que pode ser associado a uma baixa maturidade do sistema brasileiro quanto ao controle de poluentes hídricos.

Preserved echinoderm gametes as a useful and ready-to-use bioassay material

Marine animals, and sea urchin species in particular, have several advantages for use in environmental research. However, the spawned eggs of the sea urchin quickly lose fertility, although the fertile period can be lengthened by the addition of antibiotics to the sea water (Epel et al., 2004). We evaluated five species of Japanese sea urchin and the gametes of Hemicentrotus pulcherrimus could be maintained for 2 weeks or more at low temperature with the addition of antibiotics to sea water. We also demonstrated the practicality of shipping these preserved gametes as experimental material for universities and schools to use immediately for bioassays of physical and chemical impacts on the marine environment.

Distinct embryotoxic effects of lithium appeared in a new assessment model of the sea urchin: the whole embryo assay and the blastomere culture assay

Early embryogenesis is one of the most sensitive and critical stages in animal development. Here we propose a new assessment model on the effect of pollutant to multicellular organism development. That is a comparison between the whole embryo assay and the blastomere culture assay. We examined the LiCl effect on the sea urchin early development in both of whole embryos and the culture of isolated blastomeres. The mesoderm and endoderm region were capable to differentiate into skeletogenic cells when they were isolated at 60-cell stage and cultured in vitro. The embryo developed to exogastrula by the vegetalizing effect of the same LiCl condition where ectodermal region changed their fate to endoderm, while the isolated blastomeres from the presumptive ectoderm region differentiated into skeletogenic cells in the culture with LiCl. The effect of LiCl to the sea urchin embryo and to the dissociated blastomere is a unique example where same cells response distinctly to the same agent depend on the condition around them. Present results show the importance of examining the process in cellular and tissue levels for the exact understanding on the morphological effect of chemicals and metals.

Sea urchin embryos exposed to thalidomide during early cleavage exhibit abnormal morphogenesis later in development

BACKGROUND

Clinical use of thalidomide has increased drastically, pushing the questions concerning the teratogenic mechanisms of this drug back to the forefront. Progress in understanding the teratogenic mechanisms has been slow, with the lack of non-primate vertebrate animal models susceptible to the classic reduction deformities remaining a concern. Sea urchin embryos have been used as model organisms for developmental studies for the last century. Like vertebrates, they are deuterostomes and share similar developmental and signaling pathways suggesting they may be an effective system for thalidomide studies. Therefore, we tested sea urchin embryos to see if they were sensitive to the effects of thalidomide.

METHODS

Sea urchin embryos were obtained using standard spawning and fertilization techniques. Thalidomide dissolved in DMSO was added to embryo cultures either at fertilization or during early cleavage. Samples of the embryos were evaluated during specific development stages.

RESULTS

Lytechinus pictus embryos exposed to 400 microM thalidomide at fertilization or within a window during early cleavage (2-6 hours post-fertilization) exhibit significant levels of abnormal embryos (60-82%) at the pluteus stage, compared to controls levels (< or =10%). Strongylocentrotus purpuratus embryos exposed at initial fertilization or during early cleavage (2-6 hours post-fertilization) exhibit similar responses with significant abnormal levels ranging from (55-70%) at pluteus stage.

CONCLUSIONS

Both species of sea urchin tested were susceptible to thalidomide-induced teratogenesis during cleavage (4-16 cell stages). This response during cleavage stages warrants further study and indicates that sea urchin embryos may prove to be a useful tool for studying thalidomide effects early in development.