Endocrine regulation of reproductive biology in echinoderms: An evolutionary perspective from closest marine invertebrate relatives to chordates.

Echinoderms are a phylum of invertebrate deuterostomes, which contain echinoids, asteroids, holothuroids, crinoids, and ophiuroids. Echinoderms have special evolutionary position and unique characteristics, including pentamerous radial body structure, elaborate calcareous endoskeletons, and versatile water vascular system. Echinoderms exhibit extraordinarily diverse reproductive modes: asexual reproduction, sexual reproduction, sexual reversal, etc. Endocrine regulation plays important well-known roles in sex differentiation, gonadal development and maturation, gametogenesis, and reproductive behavior in vertebrates. However, the entire picture of reproductive endocrinology in echinoderms as an evolutionary model of the closest marine invertebrate relatives to chordates has not been revealed. Here, we reviewed previous and recent research progress on reproductive endocrinology in echinoderms, mainly including two sections: Sex steroids in echinoderms and neuropeptide regulation in echinoderm reproduction. This review introduces a variety of endocrine regulatory mechanisms in reproductive biology of echinoderms. It discusses the vertebrate-like sex steroids, putative steroidogenic pathway and metabolism, and reproduction-related neuropeptides. The review will provide a deeper understanding about endocrine regulatory mechanisms of gonadal development in lower deuterostomes and the application of endocrine control in economic echinoderm species in aquaculture.

Changes in gonadotropin-releasing hormone in the cerebral ganglion of the Manila clam Ruditapes philippinarum during gonadal development.

Gonadotropin-releasing hormone (GnRH) plays an important role in reproduction in both vertebrates and invertebrates; however, little is known about GnRH during gonadal development in bivalves. We developed a time-resolved fluoroimmunoassay (TR-FIA) for Manila clam Ruditapes philippinarum GnRH (rpGnRH) and measured the amount of rpGnRH in the cerebral ganglion (CG) and sex steroid hormones in the hemolymph during gonadal development. The cross-reactivity of the anti-rpGnRH antibody against other forms of GnRH was <0.15%, and the displacement curve obtained for serially diluted CG extracts was parallel to the rpGnRH standard curve, confirming the suitability of the TR-FIA system. Based on histological observation, gonadal development of the clams was classified into early developing (stage 1), late developing (stage 2), ripe (stage 3), and partially spent (stage 4). In female clams, rpGnRH levels in the CG peaked at stage 1, and 17ß-estradiol (E2) levels in the hemolymph peaked at stage 2. The rpGnRH levels in males and hemolymph testosterone levels in both sexes did not differ significantly across stages. Hemolymph E2 levels in males were below the detection limit for the TR-FIA. These results suggest that rpGnRH and E2 secretion in females can activate ovarian development of the Manila clam at the early and late developing stages, respectively.

Molecular characterization, computational analysis and expression profiling of Dmrt1 gene in Indian major carp, Labeo rohita (Hamilton 1822).

Sexual dimorphism of fish morphology, physiology and behavior is diverse and complex in nature. Doublesex and mab-3 related transcription factor (Dmrt) is a large protein family whose function is sexual development and differentiation in vertebrates. Here, we report a full-length cDNA sequence of Labeo rohita (rohu) Dmrt1 of 907 bp length having 798 bp of open reading frame encoding 265 amino acids. The molecular weight of rohu DMRT1 protein was found to be 28.74 KDa and isoelectric point was 7.53. DMRT1 protein contains 23 positively and 24 negatively charged amino acids with a GRAVY score of -0.618. A characteristic DM domain was found in DMRT1 protein, which is a novel DNA-binding domain. Phylogenetic analysis showed maximum similarity with Cyprinus carpio when compared with DMRT1 of other vertebrates. Molecular docking study identified active sites to be targeted for drug designing. Rohu DMRT1 was observed to interact with other proteins such as FOXL2, CYP19a1a, AMH and SOX9a. Differential expression study revealed higher expression in testis tissue implying its role in male sex differentiation and testicular development. The information generated in the present work could facilitate further research to resolve the issues related to gonadal maturation and reproduction of commercially important aquaculture species.

Broodstock development and captive maturation of hilsa (Tenualosa ilisha) in a brackishwater pond-based system.

Successful captive broodstock development of clupeid fish, hilsa, is one of the major challenges for the artificial propagation of this economically valued fish. The present study provides novel insights into the pond-reared captive broodstock development of hilsa using artificial feed. In the present study, wild collected hilsa fry (weight 1.35 ± 0.13 g, length 53.84 ± 0.95 mm) were reared in grow-out ponds for 6 months followed by maintaining them as broodstock in other ponds using formulated feed in both cases. After 6 months of pond rearing, the average body weight and length of fish were 66.76 ± 4.53 g and 184.75 ± 3.65 mm, respectively. In broodstock ponds, hilsa subadults fed with formulated feed (crude protein 41.06%) ensured significant advancement in ovarian maturity with gonado somatic index of 9.09%, enhanced secondary yolk stage oocytes of 91.66% and enlargement of oocyte diameters up to 570 µm. The broodstock reached somatic growth such as average body weight and average body length of 383.80 ± 27.38 g and 339.33 ± 9.68 mm, respectively, with a condition factor of 1.06 ± 0.15. Gut content analysis revealed the better acceptability of the artificial feed. Lipid profiling of muscle and ovary during gonadal maturation revealed mobilization of fat from muscle to ovary and selective retention of some fatty acids (i.e., C14:0, C18:0, C20:5, C22:6 and C20:4) in the ovary, which might help in gonadal maturation. STATEMENT OF SIGNIFICANCE: Successful rearing of wild-caught hilsa juvenile in captive condition using formulated feed showed its potential as aquaculture species in low saline conditions. Advance stage of maturation in low saline captive conditions showed the possibility for induced breeding of hilsa, a high priced anadromous fish. Mobilization of fat from muscle to ovary and selective retention of some fatty acids in the ovary showed the scope of dietary manipulation for broodstock development of hilsa.

Molecular Identification, Characterization, and Expression Analysis of a Gonadotropin-Releasing Hormone Receptor (GnRH-R) in Pacific Abalone, Haliotis discus hannai.

A full-length cDNA sequence encoding a GnRH receptor was cloned from the pleuropedal ganglion of the Pacific abalone, Haliotis discus hannai. The cloned sequence is 1499-bp in length encoding a protein of 460 amino acid residues, with a molecular mass of 52.22 kDa and an isoelectric point (pI) of 9.57. The architecture of HdhGnRH-R gene exhibited key features of G protein-coupled receptors (GPCRs), including seven membrane spanning domains, putative N-linked glycosylation motifs, and phosphorylation sites of serine and threonine residues. It shared 63%, 52%, and 30% sequence identities with Octopus vulgaris, Limulus polyphemus, and Mizuhopecten yessoensis GnRH-R II sequences, respectively. Phylogenetic analysis indicated that HdhGnRH-R gene was clustered with GnRH-R II of O. vulgaris and O. bimaculoides. qPCR assay demonstrated that the mRNA expression level of this receptor was significantly higher in the pleuropedal ganglion than that in any other examined tissue. Transcriptional activities of this gene in gonadal tissues were significantly higher in the ripening stage. The mRNA expression of this gene was significantly higher in pleuropedal ganglion, testis, and ovary at higher effective accumulative temperature (1000 °C). In situ hybridization revealed that HdhGnRH-R mRNA was expressed in neurosecretory cells of pleuropedal ganglion. Our results suggest that HdhGnRH-R gene synthesized in the neural ganglia might be involved in the control of gonadal maturation and gametogenesis of H. discus hannai. This is the first report of GnRH-R in H. discus hannai and the results may contribute to further studies of GPCRs evolution or may useful for the development of aquaculture method of this abalone species.

¿Qué sabemos de los esteroides sexuales y las gonadotropinas en la reproducción de teleósteos neotropicales? / What do we know about sex steroids and gonadotropins regarding Neotropical teleost reproduction? / O que sabemos sobre os esteroides sexuais e as gonadotrofinas na reprodução de teleósteos neotropicais?

Resumen Esta revisión provee un resumen general de las investigaciones realizadas en los últimos 10 años acerca de los esteroides sexuales (17β-Estradiol, Testosterona, 11 Ketotestosterona y 17α, 20β-DHP), las gonadotropinas (Fsh y Lh) y sus principales reguladores (GnRH1-3 y GnIH1-3); y su respectiva función en la modulación de la reproducción. Específicamente sobre el eje Hipotálamo - Pituitaria - Gónada (HPG), en teleósteos modelo y neotropicales (Astyanax altiparanae, Steindachneridion parahybae, Salminus hillarii, Centropomus undecimalis). Mostramos que el papel regulador de éstos continúa siendo tema de discusión, pues varía en función de múltiples características, entre ellas, las estrategiareproductivas de la especie en cuestión y/o las condiciones en las que éstas son mantenidas durante el estudio. Históricamente, se ha descrito que la Fsh actúa en las fases tempranas de la reproducción, estimulando la biosíntesis de estradiol y testosterona necesarios para la gametogénesis; mientras la Lh está implicada en las fases finales del ciclo reproductivo (maduración final de los gametos y desove). Sin embargo, en especies con desarrollo asincrónico y desove múltiple, la Lh se produce durante todo el ciclo en paralelo con la Fsh, sugiriendo la necesidad de ambas hormonas en la gametogénesis y maduración final. Adicionalmente, investigaciones recientes en especies con comportamiento migratorio reproductivo, han evidenciado una disminución significativa en la expresión del ARNm de la subunidad β de Lh (lhb) cuando los individuos son mantenidos en cautiverio, lo que podría ocasionar alguna disfunción reproductiva bajo los actuales sistemas de cultivo, considerado hoy el gran problema de la acuicultura contemporánea. Desafortunadamente, los estudios de estos tópicos en especies suramericanas son aún incipientes, por lo que se hace necesario centrar las investigaciones hacia el esclarecimiento del control neuroendocrino de la reproducción en especies nativas, más aún cuando estas especies son mantenidas en cautiverio.

Abstract This review summarises research over the last 10 years regarding sex steroids (17β-estradiol, testosterone, 11 ketotestosterone and 17α, 20β-DHP), gonadotropins (Fsh and Lh), their main regulators (GnRH1-3 and GnIH1-3) and their functions in modulating reproduction. It focuses specifically on the hypothalamic-pituitary-gonadal (HPG) axis in model and Neotropical teleosts (Astyanax altiparanae, Steindachneridion parahybae, Salminus hillarii and Centropomus undecimalis). Their regulatory role continues to be a subject of discussion since it varies, depending on multiple characteristics such as the reproductive strategies of the species in question and/or the conditions in which these were maintained during the study period. It has been described that Fsh acts during the early stages of reproduction by stimulating the biosynthesis of estradiol and testosterone which are necessary for gametogenesis, whilst Lh is involved in the reproductive cycle's final stages (final gamete maturation and spawning). However, Lh occurs throughout the cycle, in parallel with Fsh, in species having asynchronous development and multiple spawning, suggesting the need for both hormones during gametogenesis and final maturation. Recent research regarding species having reproductive migratory behaviour has highlighted a significant decrease in Lh β subunit (LHβ) mRNA expression when individuals are kept in captivity; this may have led to reproductive dysfunction in current culture systems, considered today as being the greatest problem facing contemporary aquaculture. Unfortunately, studying such topics related to South American species is still in its early stages so research must be focused on clarifying native species' neuroendocrine control of reproduction, especially when these species are kept in captivity.

Resumo Esta revisão apresenta um resumo geral das pesquisas realizadas nos últimos 10 anos sobre os esteroides sexuais (17β-Estradiol, Testosterona, 11 Ketotestosterona e 17α, 20β-DHP), as gonadotrofinas (Fsh e Lh), seus principais reguladores (GnRH1-3 e GnIH1-3); e sua respetiva função na modulação da reprodução. Especificamente, sobre o eixo Hipotálamo - Pituitária - Gónada (HPG), em teleósteos modelos e neotropicais (Astyanax altiparanae, Steindachneridion parahybae, Salminus hillarii, Centropomus undecimalis). Mostra-se que o papel regulador deles continua sendo assunto de discussão, pois varia em função de múltiplas caraterísticas, por exemplo, as estratégias reprodutivas da espécie mencionada e/ou as condições experimentais. Historicamente, tem sido descrito que a Fsh atua nas fases iniciais da reprodução, estimulando a biossíntese de estradiol e testosterona necessários para a gametogéneses; enquanto a Lh está implicada nas fases finais do ciclo reprodutivo (maduração final das gametas e desova). No entanto, em espécies com desenvolvimento assíncrono e desova múltipla, a Lh é produzida durante o ciclo em paralelo com a Fsh, sugerindo a necessidade de ambos hormônios na gametogénese e a maduração final. Adicionalmente, pesquisas recentes em espécies com comportamento migratório reprodutivo evidenciam uma diminuição significativa na expressão do mRNA da subunidade β da Lh (lhb) quando os indivíduos são mantidos em cativeiro, o que poderia resultar em alguma disfunção reprodutiva sob os atuais sistemas de cultura, sendo considerado hoje o grande problema da aquicultura contemporânea. Desafortunadamente, os estudos desses tópicos em espécies sul-americanas ainda são incipientes, pelo que é necessário concentrar as pesquisas para o esclarecimento do controle neuroendócrino da reprodução em espécies nativas, principalmente quando essas espécies são mantidas em cativeiro.

Análise dos efeitos do glifosato e sua formulação Roundup® nas células e gônadas dos peixes Danio rerio (Cyprinidae) / Analysis of the effects of glyphosate and its formulation Roundup® on the cells and gonads of fish Danio rerio (Cyprinidae)

Os herbicidas estão entre os insumos químicos mais utilizados na agricultura e apresentam ação toxicológica para as plantas. Dentre os herbicidas existentes, o glifosato e a sua formulação comercial Roundup® são os mais utilizados devido à eficácia no controle de ervas daninhas. Entretanto, estudos sugerem que estes herbicidas podem provocar distúrbios a organismos aquáticos, principalmente o Roundup®, que além do glifosato ativo, apresenta na composição componentes surfactantes que aumentariam o seu potencial toxicológico para os seres vivos. Desta forma, o presente estudo teve como objetivo comparar o potencial mutagênico e desenvolvimento gonadal do princípio ativo glifosato e sua formulação Roundup® em peixes Danio rerio. Para isso, exemplares adultos de D. rerio permaneceram em aquários expostos à concentração de 65 µg/L de cada herbicida. Foram realizadas contagens de micronúcleos, calculado o índice gonadossomático (IGS) e verificado os estágios de maturação gonadal. Os resultados demonstraram que os peixes expostos aos herbicidas apresentaram aumentos significativos na frequência de micronúcleos, bem como no IGS, e maior ocorrência de ovários com estágios em maturação e maduros. Não foram verificadas diferenças significativas na comparação dos herbicidas, exceto um aumento na frequência de ovários maduros nas fêmeas expostas ao glifosato. Observou-se que, mesmo em pequenas concentrações, os herbicidas poderiam ter ocasionado efeitos nocivos para os peixes D. rerio, podendo induzir efeitos clastogênicos nos eritrócitos, assim como distúrbios reprodutivos, aumentando a preocupação sobre os impactos que estes herbicidas podem acarretar sobre o ciclo de vida destes organismos.(AU)

The herbicides are among the most used chemical inputs in the agriculture and present a great toxicological action for the plants. Among the existing herbicides, glyphosate and its commercial formulation Roundup® are the most used due to their effectiveness in control of weeds. However, studies suggest that these herbicides can cause disturbances to aquatic organisms, mainly the Roundup®, that besides active glyphosate, it presents in the composition components surfactants that would increase its toxicological potential for the alive beings. Therefore, the aim of this study is to compare the mutagenic potential and gonadal development of the active principle glyphosate and its formulation Roundup® in fish Danio rerio. Thus, adult copies of D. rerio stayed in aquariums exposed to a concentration of 65 µg / L of each herbicide. Micronucleus counts were performed and the Gonadossomatic index (GSI) was calculated and the stages of gonadal maturation were verified. The results demonstrated that the fish exposed to the herbicides, presented significant increases in the micronucleus frequency, as well as in GSI and larger occurrence of ovaries with stages in maturation and mature. There were no significant differences in herbicide comparison, except an increase in the frequency of mature ovaries in the exposed females to glyphosate. It was observed that even in small concentrations, the herbicides could presented harmful effects for the fish D. rerio, could have caused clastogenic effects in the erythrocytes, as well as, reproductive disturbances, increasing the concern about the impacts that these herbicides can have on the life cycle of these organisms.(AU)

Photoperiodic effects on somatic growth and gonadal maturation in Mickey Mouse platy, Xiphophorus maculatus (Gunther, 1866).

Photoperiod is important in initiation or suppression of reproductive timing and gonadal maturation which varies with species. The aim of the present study was to investigate the effect of two photoperiodic manipulating regimes, i.e., long (18L:6D) and short (10L:14D) photoperiods for a period of 60 days on somatic growth and gonadal maturation of a live-bearer ornamental fish, Mickey Mouse platy (Xiphophorus maculatus). The control fish were further kept under the laboratory environmental condition. The results showed a significant increase in weight gain, specific growth rate, and gonadosomatic index in fish under long photoperiod than those exposed to short photoperiod and control condition (P < 0.05). A condition factor showed significant variations between long photoperiod and control groups. Furthermore, a long photoperiod also induced a significant increase in the number of fish with mature embryo and middle-eyed embryo in the ovary. Similarly, histological analysis of testes of males showed an increase in the number of mature spermatid and spermatozoa under long photoperiod when compared to those of control and short photoperiod ones. Thus, it can be concluded that long-day photoperiodic manipulation may be applied for healthy growth and early gonadal maturation of live-bearer ornamental fishes.

Comparative analysis of the reproductive activity of Leporinus piau (Characiformes: Anostomidae) in lentic and lotic environments

In this study, we determined the main reproductive parameters of piau gordura, Leporinus piau, in two sections of the São Francisco River basin. Between May 2015 and April 2016, a total of 573 specimens were captured from a lentic environment (section 1), the Três Marias Reservoir (TMR), and a lotic environment (section 2), downstream of the TMR at the confluence of the São Francisco River (SFR) with the Abaeté River. Analysis of reproductive activity showed that L. piau from both sections reproduced, but females and males from section 1 exhibited higher total length, body weight, Fulton condition factor, and gonadosomatic index values, as compared to section 2. Sexual dimorphism was evident in the species, with females being larger than males. Moreover, males reached first gonadal maturation at a smaller size than females. The peak maturation/mature stage was observed in November/April for females and males in section 1 and in November/December in section 2, coinciding with high temperatures and precipitation in the region. In both sections of the river, L. piau exhibited the typical characteristics of partial spawning, with a prolonged spawning period, and preferential reproduction in lentic environments.(AU)

Neste estudo, determinamos os principais parâmetros reprodutivos do piau gordura, Leporinus piau, em duas seções da bacia do rio São Francisco. Entre maio de 2015 e abril de 2016, um total de 573 espécimes foram capturados de um ambiente lêntico (seção 1), o reservatório de Três Marias (RTM), e um ambiente lótico (seção 2), à jusante da RTM na confluência do rio São Francisco (RSF) com o rio Abaeté. A análise da atividade reprodutiva mostrou que L. piau se reproduz nas duas seções, mas fêmeas e machos da seção 1 apresentaram maiores valores de comprimento total, peso corporal, fator de condição de Fulton e índice gonadossomático em comparação com a seção 2. O dimorfismo sexual foi evidente na espécie com as fêmeas sendo maiores do que os machos. Além disso, os machos atingiram a primeira maturação gonadal em tamanho menor do que as fêmeas. O pico do estágio de maturação/maduro foi observado em novembro/abril para fêmeas e machos na seção 1 e em novembro/dezembro na seção 2, coincidindo com altas temperaturas e precipitação na região. Em ambas as seções do rio, L. piau apresentou características típicas de desova parcelada com período de desova prolongada e reproduz preferencialmente em ambientes lênticos.(AU)

Effect of photoperiod on ovarian maturation in Cheirodon interruptus (Teleostei: Characidae) / Efeito do fotoperíodo na maturação dos ovários em Cheirodon interruptus (Teleostei: Characidae)

Abstract Cheirodon interruptus is a ubiquitous small characid that inhabits the Pampean region and commonly used as bait. Its vast market is supplied from the wild population causing a significant environmental impact. In this study, we assess the effect of photoperiod on ovarian maturation in order to evaluate its potential as a tool to manipulate reproduction under artificial conditions. Four treatments in triplicate (light: dark, L: D) were tested: 24L: 0D, 12L: 12D, 0L: 24D and a progressive photoperiod corresponding to the daily photoperiod increments in wild during winter-spring transition, accelerated three times. The experiment was conducted for 45 days. Gonadosomatic index (GSI), oocyte mean diameter, vitellogenic oocyte proportions, plasma estradiol concentrations (E2), condition factor (Kn) and standard length were estimated. Values of mean GSI, oocyte diameter, vitellogenic oocyte proportions and E2 concentration were maximum in the progressive treatment indicating vitellogenesis stimulation. In turn the same parameters were minimum in the 24L: 0D, revealing the vitellogenesis inhibition. This study showed that photoperiodic regime play an important role in the onset of ovarian maturation in C. interruptus.

Resumo Cheirodon interruptus é um pequeno caracídeo amplamente distribuído na região Pampeana e comumente usado como isca. Seu vasto mercado se abastece de populações silvestres causando um impacto ambiental significativo. Neste estudo, investigamos o efeito do fotoperíodo no amadurecimento do ovário para avaliar o potencial deste fator como ferramenta para manipular a reprodução em condições artificiais. Quatro tratamentos foram testados por triplicado (luz: escuro, L: D): 24L: 0D, 12L: 12D, 0L: 24D e um fotoperíodo progressivo que simula as mudanças das horas luz na natureza e na transição de inverno a primavera, acelerado três vezes. O experimento se realizou durante 45 dias. O índice gonadossomático (GSI), o diâmetro médio dos ovócitos, a proporção de ovócitos vitelogênicos, as concentrações plasmáticas de estradiol (E2), o fator de condição (Kn) e o comprimento padrão foram estimados. Os valores médios de GSI, o diâmetro dos ovócitos, as proporções de ovócitos vitelogênicos e a concentração de E2 foram maximizados no fotoperíodo progressivo, indicando estimulação de vitelogênesis. Por outro lado, esses mesmos parâmetros resultaram mínimos no tratamento 24L: 0D, revelando um efeito inibidor da vitelogênesis. Este estudo mostrou que as variações de fotoperíodo exercem um papel importante no início vitelogênesis reprodutiva em C. interruptus .

Reproductive biology of pequira Bryconamericus stramineus (Eigenmann, 1908) in Funil Reservoir-MG, Brazil / Biologia reprodutiva da Pequira Bryconamericus stramineus (Eigenmann, 1908) no reservatório de Funil-MG, Brasil

Abstract In order to evaluate aspects of reproductive biology of the "pequira" ( Bryconamericus stramineus) in the elevator of the Funil Dam - MG, fish capture was carried out from November 2008 to January 2009 and 317 individuals were collected. The mean standard length (SL) of the population was 4.96 cm and mean weight 1.80 g. The females had SL of 5.0 cm, while males had a SL of 4.6 cm. A sex ratio of 2.20: 1 (females: male) was observed. Our results show that 73% of the individuals analyzed were considered adults. The species presented low fecundity, mean of 470.9 oocytes per female and a mean diameter of 221.08 μm, with an increase in oocyte diameter over the evaluation period. The length of the first gonadal maturation was estimated at 5.0 cm. The results obtained in this work suggest that the reproductive cycle of the species occurs in the analyzed period. Although this species does not have migratory reproductive habits, the presence of adults in the reproductive stage was observed in the transposition area, which suggests a search for new environments for spawning.

Resumo Com o objetivo de avaliar aspectos da biologia reprodutiva da pequira Bryconamericus stramineus no elevador da represa do Funil - MG foram realizadas capturas entre os meses de novembro de 2008 a janeiro de 2009, sendo coletados 317 indivíduos. O comprimento padrão (CP) médio da população foi de 4,96 cm e peso médio de 1,80 g. As fêmeas apresentaram CP de 5,0 cm, enquanto que os machos obtiveram um CP de 4,6 cm. Foi observada proporção sexual de 2,20:1(fêmeas:macho). Dos indivíduos analisados, 73% foram considerados adultos. A espécie apresentou baixa fecundidade, com média de 470,9 ovócitos por fêmea e diâmetro médio de 221,08 μm, ocorrendo aumento no diâmetro de ovócitos com o decorrer do tempo no período avaliado. O comprimento de primeira maturação gonadal foi estimado em 5,0 cm. Os resultados obtidos neste trabalho sugerem que o ciclo reprodutivo da espécie ocorre no período analisado. Embora esta espécie não tenha hábitos reprodutivos migratórios, a presença de adultos no estágio reprodutivo foi observada na área de transposição, o que sugere a busca de novos ambientes para a reprodução.

Starvation Promotes Autophagy-Associated Maturation of the Testis in the Giant Freshwater Prawn, Macrobrachium rosenbergii.

Autophagy is a degradative process of cellular components accomplished through an autophagosomal-lysosomal pathway. It is an evolutionary conserved mechanism present in all eukaryotic cells, and it plays a fundamental role in maintaining tissue homeostasis both in vertebrates and invertebrates. Autophagy accompanies tissue remodeling during organ differentiation. Several autophagy-related genes and proteins show significant upregulations following nutrient shortage (i.e., starvation). In our previous study, we found that in female giant freshwater prawns subjected to a short period of starvation autophagy was up-regulated in consonant with ovarian maturation and oocyte differentiation. Whether and how starvation-induced autophagy impacts on testicular maturation and spermatogenesis of the male prawns remained to be investigated. In this study, we analyzed the effects of starvation on histological and cellular changes in the testis of the giant freshwater prawn Macrobrachium rosenbergii that paralleled the induction of autophagy. Under short starvation condition, the male prawns showed increased gonado-somatic index, increased size, and late stage of maturation of seminiferous tubules, which contained increased number of spermatozoa. Concurrently, the number of autophagy vacuoles and autophagy flux, as monitored by transmission electron microscopy and the autophagic marker LC3, increased in the testicular cells, indicating that a short period of starvation could induce testicular maturation and spermatogenesis in male M. rosenbergii along with modulation of autophagy.

Gonadal microRNA Expression Profiles and Their Potential Role in Sex Differentiation and Gonadal Maturation of Mud Crab Scylla paramamosain.

Although the sexual dimorphism in terms of gonadal development and gametogenesis of mud crab has been described, the internal regulating mechanism and sex differentiation process remain unclear. A comparative gonadal miRNA transcriptomic study was conducted to identify miRNAs that are differentially expressed between testes and ovaries, and potentially uncover miRNAs that might be involved in sex differentiation and gonadal maturation mechanisms of mud crabs (Scylla paramamosain). A total of 10 known miRNAs and 130 novel miRNAs were identified, among which 54 were differentially expressed. Target gene prediction revealed a significant enrichment in 30 KEGG pathways, including some reproduction-related pathways, e.g. phosphatidylinositol signalling system and inositol phosphate metabolism pathways. Further analysis on six differentially expressed known miRNAs, six differentially expressed novel miRNAs and their reproduction-related putative target genes shows that both miRNAs and putative target genes showed stage-specific expression during gonadal maturation, suggesting their potential regulatory roles in sex differentiation and reproductive development. This study reveals the sex-biased miRNA profile and establishes a solid foundation for understanding the sex differentiation and gonadal maturation mechanisms of S. paramamosain.

Expression patterns and immunolocalisation of IGF-I and IGF-II in male and female gonads of the Neotropical characid fish Astyanax fasciatus.

The insulin-like growth factor (IGF) system plays important roles in fish reproduction, but the expression pattern and cellular location of IGF-I and IGF-II during gonadal maturation are uncertain. The present study reports a stage-specific assessment of gonadal expression levels and immunolocalisation of IGF-I and IGF-II in Astyanax fasciatus, a characid fish from South America. Adult fish in different maturity stages were caught in the Furnas Reservoir, Grande River, Brazil. Gonad samples were processed for histology, immunohistochemistry, and ELISA for IGF-I and IGF-II. Ovarian levels of IGF-I were low during ripening and ripe stages, higher in totally spent, and then decreased in resting. Levels of IGF-II increased during ovarian maturation, reaching significantly higher values at stage totally spent. In males, IGF-I levels followed gonadal maturation, with higher values in ripening and ripe stages, whereas IGF-II levels showed higher values in stage ripening and partially spent. A positive correlation was found between IGF-I and gonadosomatic index (GSI) for males (r = 0.59), while females showed a negative correlation (r = - 0.43), but IGF-II showed no correlation to GSI. IGF-I was expressed mainly in oogonia nests whereas IGF-II stained the follicular cells in the perinucleolar follicles, cortical vesicles in the previtellogenic follicles, and oogonia nests. In males, IGF-I was evident in spermatogonia and spermatocytes while IGF-II stained Sertoli cells surrounding spermatids cysts and spermatogonia in late stages. Together, these findings support a hypothesis that the balance between IGF-I and IGF-II levels is important in the regulation of gonad maturation in Astyanax fasciatus.

Molecular identification of steroidogenesis-related genes in scallops and their potential roles in gametogenesis.

Sex steroids are crucial for controlling gametogenesis and germ cell maturation in vertebrates. It has been proposed that Yesso scallop (Mizuhopecten yessoensis) has the same sex steroids as those animals, but the scallop biosynthetic pathway is unclear. In this study, we characterized several steroidogenesis-related genes in M. yessoensis and proposed a putative biosynthetic pathway for sex steroids that is similar to that of vertebrates. Specifically, we identified several steroidogenesis-related gene sequences that encode steroid metabolizing enzymes: StAR-related lipid transfer (START) protein, 17α-hydroxylase, 17,20-lyase (cyp17a), 17ß-hydroxysteroid dehydrogenase (hsd17b), and 3ß-hydroxysteroid dehydrogenase (hsd3b). We sampled adult scallops throughout their reproductive phase to compare their degree of maturation with their intensity of mRNA expression. Semi-quantitative RT-PCR analysis revealed a ubiquitous expression of transcripts for steroid metabolizing enzymes (i.e., star, cyp17a, hsd17b, and hsd3b) in peripheral and gonadal tissues. Real-time PCR analysis revealed a high level of expression of star3 and cyp17a genes in gonadal tissues at the early stage of cell differentiation in scallops. Interestingly, mRNA expression of hsd3b and hsd17b genes showed a synchronous pattern related to degree of gonad maturity. These results indicate that both hsd3b and hsd17b genes are likely involved in steroidogenesis in scallops. We therefore believe that these steroid-metabolizing enzymes allow scallops to endogenously produce sex steroids to regulate reproductive events.

Transcriptomic response of the Crassostrea virginica gonad after exposure to a water-accommodation fraction of hydrocarbons and the potential implications in reproduction.

The Crassostrea virginica oyster has biological and economic importance in the Gulf of Mexico, an area with a high extraction and production of hydrocarbons. Exposure to hydrocarbons affects the reproductive processes in bivalves. In C. virginica, the effect of hydrocarbons on the gonad of the undifferentiated organism has not been evaluated to determine the possible damage during the maturation process. To evaluate this effect, RNA-seq data was generated from C. virginica gonads exposed to a 200 µg/L of hydrocarbons at different exposure times (7, 14 and 21 days) and a control treatment (without hydrocarbons). The analysis of the gonad transcriptome showed the negative effect of hydrocarbons on maturation, with a sub-expression of 22 genes involved in different stages of this process. Additionally, genes in the immune system were down-regulated, which may indicate that exposure to hydrocarbons causes immunosuppression in bivalves. A group of oxidative stress genes was also reduced. These data contribute to a better understanding of the effect of hydrocarbons on the reproductive process in bivalves and, at the same time, allow us to identify possible biomarkers associated with hydrocarbon contamination in the gonad of C. virginica.

The influence of a large reservoir on the reproductive activity of the white piranha, Serrasalmus brandtii (Lütken, 1875) in Southeast Brazil / A influência de um grande reservatório na atividade reprodutiva da piranha branca, Serrasalmus brandtii (Lütken, 1875) no sudeste do Brasil

Abstract: In order to assess the influence of the Três Marias dam on the reproduction of the white piranha, Serrasalmus brandtii, 1569 specimens captured from June 2011 to May 2012 in three sections of the São Francisco River basin were analyzed: section 1 = Três Marias reservoir (TMR); section 2 = São Francisco River (SFR) segment immediately downstream of TMR; and section 3 = SFR segment at the confluence with the Abaeté River. Total length (TL), body weight (BW), gonadosomatic index (GSI), and gonadal maturation stages were determined for each specimen, while vitellogenic follicle diameter, and absolute (AF) and relative (RF) fecundities were also determined for females. Reproductive activity, including spawned females and spermed males, was recorded throughout the year in the three river segments. Higher frequencies of females and males at the maturing/mature stage were found in the November/December and January/February, which coincided with the period of higher temperature, rainfall, and dissolved oxygen concentration. Mean GSI and vitellogenic follicle diameter were higher in sections 1 and 3 than in section 2 (P <0.05), while AF and RF were higher in section 1 (P <0.05) than in sections 2 and 3. The results of the present study showed that S. brandtii had lower reproductive performance in section 2, probably due to thermal disturbances caused by the dam, thus confirming the influence of dams on the reproduction of fish downstream from hydroelectric plant reservoirs.

Resumo: Com o objetivo de avaliar a influência da barragem de Três Marias na reprodução da piranha branca, Serrasalmus brandtii, foram analisados 1569 exemplares capturados de junho de 2011 a maio de 2012 em três trechos da bacia do rio São Francisco: seção 1 = reservatório de Três Marias (RTM); seção 2 = segmento do rio São Francisco (SRF) imediatamente a jusante do RTM; e seção 3 = segmento RSF na confluência com o rio Abaeté. O comprimento total (CT), peso corpóreo (PC), índice de gonadossomático (IGS) e estágio de maturação gonadal foram determinados para cada amostra, enquanto o diâmetro do folículo vitelogênico, fecundidade absoluta (FA) e relativa (FR) foram determinadas para fêmeas. Nas três seções estudadas, a atividade reprodutiva foi registrada ao longo do ano, incluindo fêmeas desovadas e machos espermiados. Maiores frequências de fêmeas e machos na fase de maturação/maduro foram encontradas nos meses de novembro/dezembro e janeiro/fevereiro, coincidindo com o período de maior temperatura, precipitação e concentração de oxigênio dissolvido. O IGS médio e o diâmetro do folículo vitelogênico foram maiores nas seções 1 e 3 do que na seção 2 (P <0,05), enquanto FA e FR foram maiores na seção 1 (P <0,05) do que nas seções 2 e 3. Os resultados do presente estudo mostraram que S. brandtii teve menor desempenho reprodutivo na seção 2, provavelmente devido a perturbações térmicas causadas pela barragem, confirmando a influência das barragens na reprodução de peixes a jusante de reservatórios de usinas hidrelétricas.

Downstream effects of a large reservoir on the reproductive activity of Prochilodus hartii (Pisces: Prochilodontidae).

To analyze the effect of the Irapé reservoir on the reproduction of "curimba", Prochilodus hartii, a migratory species, 503 specimens were collected during the reproductive period from February 2012 to January 2013. Specimens were collected from two river sections within the Jequitinhonha River Basin: Site 1 - a section of the Itacambiruçu River, a tributary of the Jequitinhonha River upstream of the Irapé reservoir; and Site 2 - a section of the Jequitinhonha River immediately downstream from the Irapé dam. Specimens (n = 270) were captured at Site 1 (160 males and 110 females), and 233 specimens at Site 2 (136 males and 97 females). The following were determined for each specimen: gonadosomatic index (GSI), hepatosomatic index (HSI), stomach repletion index (SRI), coelomic fat index (CFI) and condition factor (K). Both male and female fish were captured at all stages of gonadal maturation at Site 1, whereas only fish in the inactive and initial maturation stages were captured at Site 2. Length and mean GSI were greater (P < .05) at Site 1. Mean HSI and SRI of females was less in the advanced maturation stage. There were lesser values ​​for temperature and dissolved oxygen at Site 2 than 1. It is possible that the lesser values ​​for the physical and chemical characteristics of the water at Site 2 failed to promote advanced gonadal maturation, spawning, and spermiation of P. hartii, thus there are associations that are indicative of a negative effect of the Irapé reservoir on the reproduction of this migratory species.

Effect of photoperiod on ovarian maturation in Cheirodon interruptus (Teleostei: Characidae)

Abstract Cheirodon interruptus is a ubiquitous small characid that inhabits the Pampean region and commonly used as bait. Its vast market is supplied from the wild population causing a significant environmental impact. In this study, we assess the effect of photoperiod on ovarian maturation in order to evaluate its potential as a tool to manipulate reproduction under artificial conditions. Four treatments in triplicate (light: dark, L: D) were tested: 24L: 0D, 12L: 12D, 0L: 24D and a progressive photoperiod corresponding to the daily photoperiod increments in wild during winter-spring transition, accelerated three times. The experiment was conducted for 45 days. Gonadosomatic index (GSI), oocyte mean diameter, vitellogenic oocyte proportions, plasma estradiol concentrations (E2), condition factor (Kn) and standard length were estimated. Values of mean GSI, oocyte diameter, vitellogenic oocyte proportions and E2 concentration were maximum in the progressive treatment indicating vitellogenesis stimulation. In turn the same parameters were minimum in the 24L: 0D, revealing the vitellogenesis inhibition. This study showed that photoperiodic regime play an important role in the onset of ovarian maturation in C. interruptus.

Resumo Cheirodon interruptus é um pequeno caracídeo amplamente distribuído na região Pampeana e comumente usado como isca. Seu vasto mercado se abastece de populações silvestres causando um impacto ambiental significativo. Neste estudo, investigamos o efeito do fotoperíodo no amadurecimento do ovário para avaliar o potencial deste fator como ferramenta para manipular a reprodução em condições artificiais. Quatro tratamentos foram testados por triplicado (luz: escuro, L: D): 24L: 0D, 12L: 12D, 0L: 24D e um fotoperíodo progressivo que simula as mudanças das horas luz na natureza e na transição de inverno a primavera, acelerado três vezes. O experimento se realizou durante 45 dias. O índice gonadossomático (GSI), o diâmetro médio dos ovócitos, a proporção de ovócitos vitelogênicos, as concentrações plasmáticas de estradiol (E2), o fator de condição (Kn) e o comprimento padrão foram estimados. Os valores médios de GSI, o diâmetro dos ovócitos, as proporções de ovócitos vitelogênicos e a concentração de E2 foram maximizados no fotoperíodo progressivo, indicando estimulação de vitelogênesis. Por outro lado, esses mesmos parâmetros resultaram mínimos no tratamento 24L: 0D, revelando um efeito inibidor da vitelogênesis. Este estudo mostrou que as variações de fotoperíodo exercem um papel importante no início vitelogênesis reprodutiva em C. interruptus .

Reproductive biology of pequira Bryconamericus stramineus (Eigenmann, 1908) in Funil Reservoir-MG, Brazil

Abstract In order to evaluate aspects of reproductive biology of the pequira ( Bryconamericus stramineus) in the elevator of the Funil Dam - MG, fish capture was carried out from November 2008 to January 2009 and 317 individuals were collected. The mean standard length (SL) of the population was 4.96 cm and mean weight 1.80 g. The females had SL of 5.0 cm, while males had a SL of 4.6 cm. A sex ratio of 2.20: 1 (females: male) was observed. Our results show that 73% of the individuals analyzed were considered adults. The species presented low fecundity, mean of 470.9 oocytes per female and a mean diameter of 221.08 m, with an increase in oocyte diameter over the evaluation period. The length of the first gonadal maturation was estimated at 5.0 cm. The results obtained in this work suggest that the reproductive cycle of the species occurs in the analyzed period. Although this species does not have migratory reproductive habits, the presence of adults in the reproductive stage was observed in the transposition area, which suggests a search for new environments for spawning.

Resumo Com o objetivo de avaliar aspectos da biologia reprodutiva da pequira Bryconamericus stramineus no elevador da represa do Funil - MG foram realizadas capturas entre os meses de novembro de 2008 a janeiro de 2009, sendo coletados 317 indivíduos. O comprimento padrão (CP) médio da população foi de 4,96 cm e peso médio de 1,80 g. As fêmeas apresentaram CP de 5,0 cm, enquanto que os machos obtiveram um CP de 4,6 cm. Foi observada proporção sexual de 2,20:1(fêmeas:macho). Dos indivíduos analisados, 73% foram considerados adultos. A espécie apresentou baixa fecundidade, com média de 470,9 ovócitos por fêmea e diâmetro médio de 221,08 m, ocorrendo aumento no diâmetro de ovócitos com o decorrer do tempo no período avaliado. O comprimento de primeira maturação gonadal foi estimado em 5,0 cm. Os resultados obtidos neste trabalho sugerem que o ciclo reprodutivo da espécie ocorre no período analisado. Embora esta espécie não tenha hábitos reprodutivos migratórios, a presença de adultos no estágio reprodutivo foi observada na área de transposição, o que sugere a busca de novos ambientes para a reprodução.