Stages Of Gonadal Development Research Articles

Reproductive Characters of the Ricefield Eel (Monopterus albus Zuieuw) in Babakan Village, Karang Lewas District, Banyumas, Central Java

One of the villages in Banyumas Regency which provides a high potential habitat for ricefield eel (Monopterus albus Zuieuw), a protogynous hermaphrodite, is Babakan. However, information concerning their reproduction cycles is lacking. This research aimed to understand the reproductive characters including Gonad Maturity Level (GML), Gonad Maturity Index (GMI), fecundity, egg diameter, and to examine the correlation of body length with both GML and GMI of the fish. We applied the survey method with purposive sampling design. The sampling was done once in a month for four times from November 2017 to March 2018. There were 30 samples for each sampling time (total of 120 eels). The results showed that the ricefield eels underwent intersex phase at a body length of 30.5-30.7 cm. The fish less than 30.5 cm were females, and those more than 30.7 cm was a male. The ricefield eel sex based on stages of gonad development was GML I (there were oocytes equipped with nucleus and cytoplasm), GML II (the presence of cortical alveoli stage), GML III (the stage of vitellogenesis), and GML IV (mature stage). The presence of degenerated oocytes and testicular lobes characterized their intersex stage. A testicular lobe characterized the male stage. The dominant GML during November, December, January, and March were GML I and II, GML I and II, GML III, and GML IV, respectively. Fecundity of the ricefield eels during the research was between 207 and 370 eggs, with an average of 252 eggs. The egg diameter of 0.22-2.5 mm indicated that the ricefield eel was on the batch spawner. The highest GMI of the eels occurred in January between 00017 and 0.0242 during the entire month of sampling. The body length of the fish did not correlate to their GML. On the other hand, their body length correlated to their GMI.

First comparative assessment of the reproductive cycle of three species of Chiton on a temperate rocky shore of the southeastern Pacific

AbstractThe present study provides the first assessment of the reproductive cycle of three common and widespread species of the genus Chiton, sympatric in rocky shores of Coquimbo, northern Chile (~30°S): C. granosus, C. cumingsii, and C. magnificus. From specimens seasonally sampled during a 2‐year period, a histological study was performed in order to describe the gonad structure and stages of gonadal development for each species. The morphological structure of the gonad was similar in the three species, with sexual cells developing from the gonad wall towards its center. The three species were gonochoric and iteroparous, with asynchronous gamete maturation at population level; in all seasons, sexual maturity was evident in small to large individuals of each species (≥25 mm in total length for C. cumingsii and C. granosus, and ≥47 mm for C. magnificus).

Molecular characterization and expression pattern of inhibin α and βb in Chinese tongue sole (Cynoglossus semilaevis)

Inhibin plays important roles in vertebrate reproduction and development. In this study, we have cloned two genes encoding inhibin subunits, inhα and ihnβb, in Chinese tongue sole. inhα consists of 1032 bp, encoding a 343 amino-acid protein. inhβb is composed of 1275 bp, encoding a 424 amino-acid protein. Phylogenetic tree analysis indicated that INHα and INHβB were independently evolved. qPCR showed that inhα expression of in male testis was higher than that in ovary and pseudomale testis, while the expression of inhβb in ovary was higher than that in male and pseudomale testis. During gonadal developmental stages, inhα expression reached highest at 120 days post hatching (dph) both in ovary and testis, then showed decline in ovary but it was first decreased and then increased in the testis. Similarly, inhβb expression in ovary was low at 50–80 dph. At 120 dph, its expression was significantly increased to the peak level, and then gradually decreased. inhβb expression in testis maintained at a low level. During the embryonic developmental stages, inhα displayed the highest expression at 32-cell stage, whereas inhβb reached the highest expression at blastula stages. In situ hybridization data showed that both of inhα and inhβb were detected in oocytes of all stages. In male testis, inhα and inhβb was localized in spermatogonia, spermatocytes, spermatozoa, sertoli and leydig cells. In pseudomale testis, inhα showed the similar pattern in male testis, while the inhβb was detected in spermatocytes and spermatozoa. These data suggested that inhα may participate the spermatogenesis and oogenesis of Chinese tongue sole, while inhβb might predominantly function in oogenesis.

Acute and chronic effects of environmental realistic concentrations of clofibric acid in Danio rerio: Behaviour, oxidative stress, biotransformation and lipid peroxidation endpoints

Due to their widespread use, pharmaceuticals can be metabolized, excreted and ultimately discarded in the environment, thereby affecting aquatic organisms. Lipid-regulating drugs are among the most prescribed medications around the world, controlling human cholesterol levels, in more than 20 million patients. Despite this growing use of lipid-regulating drugs, particularly those whose active metabolite is clofibric acid, the potential toxicological effects of these pharmaceuticals in the environment is not fully characterized. This work intended to characterize the toxicity of an acute (120 hours post-fertilization) and chronic (60 days post-fertilization) exposures to clofibric acid in concentrations of 10.35, 20.7, 41.4, 82.8, and 165.6 μg L-1 in zebrafish (Danio rerio). The concentrations which were implemented in both exposures were based on predicted environmental concentrations for Portuguese surface waters. The acute effects were analysed focusing on behavioural endpoints (small and large distance travelled, swimming time and total distance travelled), biomarkers of oxidative stress (activity of the enzymes superoxide dismutase, Cu/Zn- and Mn SOD; catalase, CAT; glutathione peroxidase, Se- and total GPx), biotransformation (activity of glutathione S-transferases, GSTs) and lipid peroxidation (thiobarbituric acid reactive substances, TBARS). Chronically exposed individuals were also histologically analysed for sex determination and gonadal developmental stages. In terms of acute exposure, significant alterations were reported, in terms of behavioural alterations (hypoactivity), followed by an overall increase in all tested biomarkers. Chronically exposed organisms did not show alterations in terms of sex ratio and maturation stages, suggesting that clofibric acid did not act as an endocrine disruptor. Moreover, the metabolism of clofibric acid resulted in increased levels of both forms of SOD activity, especially for animals exposed to higher levels of this drug. An increase of CAT activity was observed in fish exposed to low levels, and a decrease in those exposed to higher amounts of clofibric acid. Both GPx forms had their activities increased. The enzyme of biotransformation GSTs were increased at low levels of clofibric acid but inhibited at higher amounts of this substance. Lipid peroxidation levels were also changed, with an induction of this parameter with increasing amounts of clofibric acid. Changes also occurred in behavioural endpoints and patterns for control organisms and for those exposed to clofibric acid were significantly distinct, for all types (light and darkness) of exposure, and for the two analysed endpoints (small and large distance). Results from this assay allow inferring that clofibric acid can have an ecologically relevant impact in living organisms exposed to this substance, with putative effects on the metabolism of individuals, affecting their behaviour and ultimately their survival.

Multifaceted linkages among eco-physiological factors, seasonal plankton dynamics and selective feeding behavior of the green mussel (Perna viridis) in the south-east coast of the Bay of Bengal

Feeding behavior of marine bivalves is largely regulated by the interactive effects of various intrinsic biological factors and extrinsic ecological factors. Therefore, an integrated multivariate approach was applied to explore a deeper knowledge about the feeding biology of the green mussel (Perna viridis), collected from the south-east coastal regions of the Bay of Bengal in Bangladesh, by interlinking among ecological factors, seasonal plankton dynamics, reproductive traits and plankton ingestion data. The correlation test, multivariate approaches and cluster analysis displayed that both the water parameters and ingested gut plankton abundance and their compositions were predominantly influenced by the seasonality and ecological factors of the environment. The selectivity indices analysis confirmed that green mussels preferentially ingested on the selective taxa of plankton. The multivariate analyses revealed that plankton ingestion by green mussels was not discriminated by their sexual dimorphism, however, it displayed an enhancement during their gonad development and maturation stages confirming that P. viridis espouses opportunistic patterns to build up their gonads by utilizing energy from the ingested planktons available in the water column. The correlation outcomes consistently demonstrated that the quantitative ingestion of plankton was positively correlated with the gonadosomatic index value of the green mussels. Although, green mussels predominantly ingested the Coscinodiscophyceae (20–60% of total ingestion), they also selectively ingested an increased amount of Bacillariophyceae, Fragillariophyceae, Dinophyceae and zooplankton during their gonad development and maturation stages to meet the special and unique metabolic requirements of crucial gametogenesis stages. Taken together all datasets, principal component analysis (PCA) was applied: the first two principal components showed that seasonality and reproductive cycle explained >47% of the variability. In both cases, PCA analysis revealed that the multiplex scenario of selective ingestion of P. viridis on different plankton taxa were predominantly interlinked with the seasonality, ecological drivers, and plankton biomass and their community structure in the water column depending on the metabolic energy requirement during their crucial gametogenesis stages. Finally, the outcomes from these broad datasets provide a better understanding about the selective feeding behavior of P. viridis, which is essential to maintain the sustainability of the ecosystems as well as to improve the growth and productivity of the existing production systems of this important species.

Reproductive Biology of Marine Catfish, Arius latiscutatus (Günther, 1864) and Arius gigas (Boulenger, 1911) from the Bays of Guinea

Background and Objectives: Marine catfish are abundant in the bays of Tabounsou and Sangareah in Republic of Guinea, but the knowledge on their biology is still scanty. The reproductive biology of Arius latiscutatus Günther, 1864 and A. gigas Boulenger, 1911 was studied through monthly sampling, from January to December 2016.
 Methodology: Fish were caught using gill nets in several sampling sites. Five gonadal stages were described, based on macroscopic observation of gonad form, size, weight, color and oocyte diameter.
 Results: The population was dominated by males (61%) in A. latiscutatus and females (53%) in A. gigas, showing a sex-ratio of 1:1.54 (Chi-square, P < 0.05) and 1:0.88 (P > 0.05), respectively. The length-weight relationship was a positive allometry for A. latiscutatus and A. gigas, and males (35.37 and 35.47 cm, respectively) reached first maturity earlier than females (39.7 and 40.8 cm, respectively). Changes in the gonadosomatic index (GSI) and in stages of gonadal development showed that A. latiscutatus spawned between April and October, while A. gigas spawned in May to November. The peak of condition factor was observed in June (0.68±0.05) and July (0.55±0.04) in females of A. latiscutatus and A. gigas, respectively.
 Conclusion: Both species, having only one annual breeding season, A. latiscutatus spawns earlier than A. gigas. Coastal fisheries should be restricted in cold season to preserve the ability of broodstock renewal for these species.

Dimorphic Expression of Selected Genes in Lepidocephalus thermalis using Cross-Specific Primers

Background: The existence of two distinct forms within a species that differ in one or more characteristics is known as dimorphism. The gonads are the primary organs in teleost to show sexual dimorphism. Lepidocephalus thermalis belongs to the Cobitidae family. No expression study on the developmental stages was done on this species. Since there is no specific primers reported for L. thermalis, the study has been carried out with the help of the specific primers of catfish. Methods: qRT- PCR is an acknowledged method for gene expression analysis due to its precision and reproducibility. In the current study, the expression of 14 different transcription factors involved in sex differentiation of Indian spiny loach during different developmental stages was analyzed using qRT- PCR and has been compared among the different stages of gonadal development for that transcription factor. Results: Gene expression patterns have been obtained from the total RNA isolated from MSG (Meso nephric gonadal complex), medium stage ovary, medium stage testis, large stage ovary and large stage testis. From the study, it has been analyzed that only sf1 has higher expression in testis and all the other transcription factors has shown higher expression in ovary.

Differential responses in the biotransformation systems of the oyster Crassostrea gigas (Thunberg, 1789) elicited by pyrene and fluorene: Molecular, biochemical and histological approach – Part II

Pyrene (PYR) and fluorene (FLU) are among the sixteen priority Polycyclic Aromatic Hydrocarbons (PAH) of the United States Environmental Protection Agency and are both frequently detected in contaminated sites. Due to the importance of bivalve mollusks in biomonitoring programs and the scarce information on the biotransformation system in these organisms, the aim of this study was to investigate the effect of PYR and FLU at the transcriptional level and the enzymatic activities of some biotransformation systems in the Pacific oyster Crassostrea gigas, and to evaluate the histological effects in their soft tissues. Oysters C. gigas were exposed for 24 h and 96 h to PYR (0.25 and 0.5 μM) and FLU (0.6 and 1.2 μM). After exposure, transcript levels of cytochrome P450 coding genes (CYP1-like, CYP2-like, CYP2AU2, CYP356A1, CYP17α-like), glutathione S tranferase genes (omega GSTO-like and microsomal, MGST-like) and sulfotransferase gene (SULT-like), and the activity of ethoxyresorufin O-deethylase (EROD), Glutathione S-transferase (GST) and microssomal GST (MGST) were evaluated in gills. Histologic changes were also evaluated after the exposure period. PYR and FLU bioconcentrated in oyster soft tissues. The half-life time of PYR in water was lower than fluorene, which is in accordance to the higher lipophilicity and bioconcentration of the former. EROD activity was below the limit of detection in all oysters exposed for 96 h to PYR and FLU. The reproductive stage of the oysters exposed to PYR was post-spawn. Exposure to PYR caused tubular atrophy in digestive diverticula, but had no effect on transcript levels of biotransformation genes. However, the organisms exposed for 96 h to PYR 0.5 μM showed higher MGST activity, suggesting a protective role against oxidative stress in gills of oysters under higher levels of PYR in the tissues. Increased number of mucous cells in mantle were observed in oysters exposed to the higher FLU concentration, suggesting a defense mechanisms. Oysters exposed for 24 h to FLU 1.2 μM were in the ripe stage of gonadal development and showed higher transcript levels of CYP2AU2, GSTO-like and SULT-like genes, suggesting a role in the FLU biotransformation. In addition, after 96 h of exposure to FLU there was a significant increase of mucous cells in the mantle of oysters but no effect was observed on the EROD, total GST and MGST activities. These results suggest that PAH have different effects on transcript levels of biotransformation genes and enzyme activities, however these differences could also be related to the reproductive stage.

Chronology of Gonadal Development in the Malayan Snail-eating Turtle Malayemys macrocephala.

The snail-eating turtle, Malayemys macrocephala, is a common freshwater turtle that can be used as an animal model for developmental biology. However, a thorough investigation of its development is needed before this species can be used as a model. Thus, this study aimed to examine the gonadal development of M. macrocephala. Turtle eggs were collected from rice fields in Phra Nakhon Si Ayutthaya Province, Thailand, and transported to the laboratory. Eggs were incubated in microprocessor-controlled incubators and randomly dissected on a weekly basis to reveal the developing embryos, then their developmental stage was identified according to Yntema (1968). Primordial germ cells and gonad structure were processed through the paraffin method. Moreover, the dynamics of germ cell proliferation and apoptosis were examined by immunohistochemical detection of proliferating cell nuclear antigen (PCNA) and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), respectively. Examination of the gonad revealed four main stages of gonadal development: (i) germ cell migration, (ii) genital ridge appearance, (iii) testicular formation, and (iv) ovarian formation. In the male turtle (incubated at 26°C), gonad developed into the testis with medullary sex cords starting at Yntema stage 17. In the female turtle (incubated at 32°C), these sex cords then degenerated, followed by cortical development into an ovarian structure starting at Yntema stage 19. Subsequently, testicular and ovarian development occurred independently, and distinct sex organs were apparent at Yntema stage 25. In addition, the presumptive testis showed germ cell proliferation in the medulla at Yntema stages 17, 19, and 25 and germ cell apoptosis in the cortex at Yntema stages 19 and 25. The presumptive ovary showed germ cell proliferation in the cortex at Yntema stages 19 and 25, and germ cell apoptosis in the medulla at Yntema stages 19 and 25.

Gonadal Maturation and Main Spawning Period of Haliotis gigantea (Gastropoda: Haliotidae).

This study was carried out to obtain information on the developmental biology and the management of biological resources of the abalone Haliotis gigantea in Korea. The sex ratio (female:male) in the present study was 1:1.7 and the proportion of females was 36.6% (n=106/290). Their gonadal structures displayed definitive seasonal changes which were similar in pattern to the changes in the gonad index (GI). The GI showed a pattern of definitive seasonal changes in both males and females it was high in the fall and low in the spring. The reproductive cycle could be categorized into the following six stages: inactive, early active, late active, ripe, spent, and degenerative stage. Based on the monthly changes in GI and stages of gonadal development, October to November was determined to be the main spawning period for H. gigantea on Jeju Island, Korea.

Reproduction of fishes of the Verde River, upper Paraná River Basin, Brazil

Abstract. Introduction: Understanding the various aspects of the reproductive biology of fish is a key step towards applying effective strategies for sustainable management of fishery resources. Objective: We aimed to evaluate the sex ratio, reproductive period and lengths at first maturity for 30 fish species caught in the Verde River, upper Paraná River Basin, Brazil. Methods: Fish were sampled monthly from November 2010 to March 2011 and from October 2011 to February 2012, and sampled quarterly from May to August in 2011 and 2012; totaling 14 samples. Fish were measured and weighed in the laboratory. In addition, gender and gonadal developmental stage were identified macroscopically. Subsequently, the sex ratio was determined and significant differences were tested using the chi-square (χ²) method. The reproductive period was determined with the use of gonadal developmental stages and the gonadosomatic index. Lastly, length at first maturity was estimated only for the species that presented individuals with sufficient immature and mature gonads to adjust the model. Results: Of the captured individuals, 51.5 % were male, and 48.5 % were female. Fifteen species showed significant differences in their sex ratios. The reproductive period for most species occurred from October to February, with reproductive peaks in November, December and January. The length at first maturity was estimated for only five species, including Salminus brasiliensis, a keystone species. Conclusions: The sex ratios revealed that for many species, there is a predominance of males over females, which was not expected for this parameter. The reproductive period follows the same pattern observed in Neotropical fish. However, it is noteworthy that some species are starting their reproduction in August.

Gonad development in mature females of tidal spray crab Plagusia depressa (Brachyura: Plagusiidae)

AbstractInformation on crustacean ovary development is important to properly understand many life story traits. This study aimed to describe macroscopic and microscopic stages of gonad development in females of Plagusia depressa (Fabricius, 1775). Thirty females of P. depressa were captured manually and underwent analgesia by decreasing temperature to collect the gonads, which underwent standard histological techniques. The macroscopic and microscopic appearance of the ovaries and the frequency of germ cells and their location in the organ were used to determine the stage of gonadal development. A total of four stages were defined. Stage 1: marks the end and beginning of gonadal maturation cycle. The germinal zone is tightly reduced with few oogonia and pre‐vitellogenic oocytes are rarely observed. Stage 2: yellow to orange colour and firm consistency. Oogonias and pre‐vitellogenic oocytes can be observed at this stage, as well as a few vitellogenic oocytes at organ limits. Stage 3: colour between red and dark brown. The gonad already presents many mature oocytes. Stage 4: characterized by the abundance of mature oocytes that occupy almost the entire organ. Macroscopic appearance of the female reproductive system, cell characteristics and changes during maturation of P. depressa corroborate with the normally found in Malacostraca.

Divergent density feedback control of migratory predator recovery following sex-biased perturbations.

Uncertainty in risks posed by emerging stressors such as synthetic hormones impedes conservation efforts for threatened vertebrate populations. Synthetic hormones often induce sex‐biased perturbations in exposed animals by disrupting gonad development and early life‐history stage transitions, potentially diminishing per capita reproductive output of depleted populations and, in turn, being manifest as Allee effects. We use a spatially explicit biophysical model to evaluate how sex‐biased perturbation in life‐history traits of individuals (maternal investment in egg production and male‐skewed sex allocation in offspring) modulates density feedback control of year‐class strength and recovery trajectories of a long‐lived, migratory fish—shovelnose sturgeon (Scaphirhynchus platorynchus)—under spatially and temporally dynamic synthetic androgen exposure and habitat conditions. Simulations show that reduced efficiency of maternal investment in gonad development prolonged maturation time, increased the probability of skipped spawning, and, in turn, shrunk spawner abundance, weakening year‐class strength. However, positive density feedback disappeared (no Allee effect) once the exposure ceased. By contrast, responses to the demographic perturbation manifested as strong positive density feedback; an abrupt shift in year‐class strength and spawner abundance followed after more than two decades owing to persistent negative population growth (a strong Allee effect), reaching an alternative state without any sign of recovery. When combined with the energetic perturbation, positive density feedback of the demographic perturbation was dampened as extended maturation time reduced the frequency of producing male‐biased offspring, allowing the population to maintain positive growth rate (a weak Allee effect) and gradually recover. The emergent patterns in long‐term population projections illustrate that sex‐biased perturbation in life‐history traits can interactively regulate the strength of density feedback in depleted populations such as Scaphirhynchus sturgeon to further diminish reproductive capacity and abundance, posing increasingly greater conservation challenges in chemically altered riverscapes.

Reproductive cycle and gonadal development of the Atlantic sea urchin Arbacia punctulata in the Gulf of Mexico: changes in nutritive phagocytes in relation to gametogenesis

ABSTRACTThe annual reproductive cycle comprises steady gametogenic activities that synchronize gonadal maturation and spawning rhythms, which are important for aquatic organisms including marine echinoderms (Echinodermata, Echinoidea). In this study, we report the annual reproductive cycle, gonadal development, and changes in nutritive phagocytes (NPs, which accumulate nutrients in germ cells) in relation to gametogenesis of the Atlantic sea urchin (Arbacia punctulata, an edible echinoid) in the Gulf of Mexico. Monthly changes in gonadal development and maturation were observed morphologically and histologically. We calculated gonadosomatic index (GSI) and compared the stages of gonadal development in order to determine the NPs index, and characteristics of germ cells (eggs and sperm) during the annual reproductive cycle. According to GSI and histological analyses, gametogenic activities were classified into four stages of both sexes: mature (June–August), spent (September–November), recovery (December–March), and growing (April–May). The GSI values in both sexes were high during summer months. In males, testicular lobules were densely packed with sperm from June to August. In females, however, mature eggs first appeared in some ovaries in May, numerically increased from June to July, and decreased in August. During gametogenesis, on the other hand, NPs in both testes and ovaries were depleted from June to August. Collectively, our results suggest that the Atlantic sea urchin spawns during summer months in the Gulf of Mexico. This is the first report, to the best of our knowledge, on gonadal development and changes in NPs during the annual reproductive cycle of any Arbacia species in the Gulf of Mexico.

Reproductive traits and age of barbeled plunderfishes from the Weddell Sea

AbstractThe genus Pogonophryne is the most species-rich genus of barbeled plunderfishes (Artedidraconidae) and includes more than 25 poorly known species endemic to the Southern Ocean. In this study, we provide new data on the age and reproductive traits of some species of Pogonophryne from the southern Weddell Sea, inferred through otolith reading and histological analyses of gonads. Individual age estimates ranged between 16 and 18 years for Pogonophryne barsukovi and Pogonophryne immaculata and between 10 and 22 years for Pogonophryne scotti. As is commonly found in notothenioids, P. barsukovi followed a group-synchronous type of ovarian development, with pre-vitellogenic and vitellogenic oocytes forming two well-separated egg-size groups. A single spawning female in the sample produced ~1097 eggs and 7.9 eggs g-1. The sample of P. immaculata consisted exclusively of developing males, with testes composed of cysts of spermatogonia, spermatocytes and spermatids. Pogonophryne scotti was the most abundant species, including relatively small males at immature or developing stages of gonad development. Larger females were regressing, being characterized by ovaries with postovulatory follicles and atretic oocytes. Based on the macroscopic and histological analyses of gonads, the spawning season would take place in autumn for P. barsukovi and P. immaculata and in spring–early summer for P. scotti.

In vitro effects of androgen on testicular development by the AR-foxl3-rec8/fbxo47 axis in orange-spotted grouper (Epinephelus coioides)

In orange-spotted grouper, androgen can promote the development of testis and spermatogenesis, but the effect of androgen on testis development is unclear. Forkhead box L 3 (Foxl3) is important in the development of fish testis. Rec8 and fbxo47 are involved in meiosis, which impacts spermatogenesis. The present study investigated the plausible role of testis development through the Foxl3 transcriptional regulation of rec8 and fbxo47. The results of tissue distribution showed that rec8 and fbxo47 are highly expressed in gonad. In addition, the highest expression of foxl3, rec8, and fbxo47 was in the testis and intersex compared with the other stages of gonadal development, suggesting that foxl3, rec8, and fbxo47 are important in testis development. In addition, by using dual-luciferase assays, we found that the androgen can increase foxl3 promoter activity and Foxl3 can upregulate rec8 and fbxo47 promoter activity. Furthermore, the addition of β-testosterone significantly increased foxl3, rec8, and fbxo47 promoter activity. Together, these results suggest that foxl3 plays a decisive role in testis development by regulating the expression of rec8 or fbxo47 and imply that AR-foxl3-rec8/fbxo47 affects the testis development pathway.

Molecular cloning, characterization and expression profiles of a SoxB2 gene related to gonadal development in mud crab (Scylla paramamosain)

ABSTRACT The molecular mechanisms underlying sex differentiation and gonad development remain elusive in crustaceans. Here, we report the cloning and characterization of a Sry-related high-mobility group family B2 gene (SpSoxB2) from an economic crustacean species, the mud crab Scylla paramamosain. The SpSoxB2 encodes a putative HMG-box protein (317 amino acids) clustered with invertebrate Sox14 homologues in the SoxB2 subgroup, but shared low similarity with SpSox14. SpSoxB2 was expressed in the hepatopancreas, thoracic ganglion, and gonads (relatively higher expression in testis than ovary). In hepatopancreas, SpSoxB2 expression was not significantly affected by sex or gonadal development stages. In testis, it was demonstrated that the SpSoxB2 expression level increased from Stage I to Stage III and then decreased afterwards. During ovarian development, the SpSoxB2 expression level continually increased from Stage I to Stage V. Furthermore, fluorescence in-situ hybridization showed that SpSoxB2 transcripts were present in both somatic and developing germ cells in the gonads. In testis, SpSoxB2 transcripts were strongly localized in spermatocytes and spermatids. In ovary, SpSoxB2 transcripts were detected in follicle cells, oogonia and oocytes, with the strongest signal in follicle cells. Our results demonstrated that the SpSoxB2 gene may play an important role during gonadal development in mud crab.

The MEDITS maturity scales as a useful tool for investigating the reproductive traits of key species in the Mediterranean Sea

Maturity is one of the most important biological parameters used in stock assessment programmes. Indeed, the macroscopic stage of gonadal development is an essential feature in estimating the maturity ogive and spawning stock biomass. It is also useful for determining the spawning season of a species and for monitoring long-term changes in the spawning cycle as well as for many other research needs related to the biology of fish. Despite the efforts made during the last few decades to standardize maturity stage data among all the researchers, marine biologists continue without a manageable and unique maturity scale to describe the reproductive development of fish gonads. For these reasons, the objectives of this article are 1) to investigate the biological parameters of five selected key species (Mullus barbatus, Galeus melastomus, Etmopterus spinax, Aristeus antennatus, Loligo vulgaris) with different reproductive strategies following the macroscopic maturity scales based on the same univocal criteria adopted in the MEDITS programme and described in this work; and 2) to compare them among some Mediterranean geographical sub-areas (GSAs) involved in the programme. Neither spawning periods nor size at first maturity (SFM50) for the studied species showed particular differences in the investigated GSAs.

Gonadosomatic index and weight/length relationship in females of three penaeoidean shrimps impacted by fisheries on the southeastern Brazilian coast

Abstract The aim of this study was to evaluate the gonadosomatic index (GSI) and the weight/length ratio in important shrimp populations (Xiphopenaeus kroyeri (Heller, 1862), Litopenaeus schmitti (Burkenroad, 1936), Rimapenaeus constrictus (Stimpson, 1874)) from the northern littoral of Sao Paulo State. The samples were collected between 2015 and 2016, with 212 females that were identified, classified according to their gonadal development stage, and measured (CL). The gonads were macroscopically classified into immature, spent and developed, and were then removed. Both body (BodW) and gonad (GonW) dry weights were obtained in order to calculate the gonadosomatic index. Weight/length relationship and weight gain rate were assessed. The weight gain presented negative allometry, indicating that the animals grow faster than they gain weight. The weight/length relationship showed a pattern of continuous reproduction, as previously determined for tropical species. From the GSI values, it was possible to separate the three predetermined gonadal stages, proving that macroscopic evaluation is reliable for evaluating the reproductive period of these shrimps. These results can be used as a guide for fishery stocks management and monitoring.

Reproductive biology of the swimming crab Achelous spinimanus (Decapoda, Portunoidea): a potential fishing resource

ABSTRACT This study describes the reproductive and recruitment patterns of the swimming crab Achelous spinimanus (Latreille, 1819) in the Ubatuba region of the northern coast of São Paulo, Brazil. Crabs were captured monthly from January 1998 to December 1999 in 18 sites located in three bays (Ubatumirim, Ubatuba, and Mar Virado), using a commercial fishing boat. In each sampling area, bottom temperature, salinity, and organic matter content were recorded. A total of 1,911 individuals were captured: 350 adult males, 475 non-ovigerous adult females, 584 adult ovigerous females, and 502 immature individuals. Reproductive females were more abundant in deeper areas; this migration might be a strategy to improve larval dispersion and survival. Ovigerous females were found year-round, indicating a continuous reproduction, and their abundance was positively correlated with temperature. During the 2-year survey, crabs with all gonadal development stages were found. We can infer that this region provides suitable resources for the development of A. spinimanus.