Pro-inflammatory cytokine IL1ß1 participates in promoting parturition related pathways in the ovoviviparous teleost black rockfish (Sebastes schlegelii).

Along with the evolution process, the reproductive strategies evolved including oviparity, viviparity and ovoviviparity, to fit the residential environment maximize the survival rate of the off spring. In mammals, the key to the initiation of parturition is the inflammatory response at the maternal-fetal interface. As a pro-inflammatory cytokine, interleukin 1 beta (IL1ß) plays an important role in the process of human parturition. While less is known about IL1ß1 in teleost parturition, identification of the functions of IL1ß1 in inducing the parturition, black rockfish, an ovoviviparity teleost, which provides over 60% nutrition supply for over 50 000 embryos though a placenta like structure during pregnant, was employed as the research model. In the present study, based on the gene cloning, we detected the expression pattern of both Il1b1 and its receptor perinatal period, as well as the localization to the ovary by in situ hybridization. The different expression genes in transcriptomic data of perinatal primary ovarian cells treated with the recombinant IL1ß1 (rIL1ß1) obtained by prokaryotic expression system were analyzed. Differentially expressed genes, functional enrichment and pathway analysis mainly included immune response, signal transduction and cell death. In summary, our research provides novel insights into the potential role of IL1ß1 in the parturition of ovoviviparity teleost.

Function of secretoneurin in regulating the expression of reproduction-related genes in ovoviviparous black rockfish (Sebastes schlegelii).

Secretoneurin (SN), a conserved peptide derived from secretogranin-2 (scg2), also known as secretogranin II or chromogranin C, plays an important role in regulating gonadotropin in the pituitary, which affects the reproductive system. This study aimed to clarify the mode of action of scg2 in regulating gonad development and maturation and the expression of mating behavior-related genes. Two scg2 cDNAs were cloned from the ovoviviparity teleost black rockfish (Sebastes schlegelii). In situ hybridization detected positive scg2 mRNA signals in the telencephalon and hypothalamus, where sgnrh and kisspeptin neurons were reported to be located and potentially regulated by scg2. In vivo, intracerebral ventricular injections of synthetic black rockfish SNa affected brain cgnrh, sgnrh, kisspeptin1, pituitary lh and fsh and gonad steroidogenesis-related gene expression levels with sex dimorphism. In vitro, a similar effect was found in primary cultured brain and pituitary cells. Thus, SN could contribute to the regulation of gonadal development, as well as reproductive behaviors, including mating and parturition.

Comparative transcriptomic analysis and genome-wide characterization of the Semaphorin family reveal the potential mechanism of angiogenesis around embryo in ovoviviparous black rockfish (Sebastes schlegelii).

To guarantee the quality and survival rate of their offspring, ovoviviparous teleost evolved special characteristics of in vivo fertilization and embryo development. Maternal black rockfish, having over 50 thousand embryos developing within the ovary simultaneously, provided around 40% nutrition throughout oocyte development, while the capillaries around each embryo contributed the rest 60% during pregnancy. Since fertilization, capillaries started to proliferate and developed into a placenta-like structure that covered over half of each embryo. Aimed to characterize the potential mechanism behind, comparative transcriptome analysis of samples collected according to the process of pregnancy. Three important time point in the process, including mature oocyte stage, fertilization and sarcomere period, were chosen for the transcriptome sequencing. Our study identified key pathways and genes involved in the cell cycle as well as DNA replication and repair, cell migration and adhesion, immune, and metabolic functions. Notably, several of the semaphoring gene family members were differently expressed. To confirm the accuracy of these genes, total of 32 sema genes were identified from the whole genome and distinct expression pattern of sema genes was observed in different pregnant stages. Our results revealed a novel insight for further investigating the functions of sema genes in reproduction physiology and embryo processes in ovoviviparous teleost.

Reproductive performance in successive generations of the brine shrimp Artemia salina (Crustacea: Anostraca) from the Sebkha of Sidi El Hani (Tunisia).

Artemia salina cysts collected from the Sebkha of Sidi El Hani hatched and cultivated in the laboratory were investigated. Nauplii were acclimated to laboratory conditions until reproductively mature (Generation 1; G1). Reproductive performance in terms of total cysts and nauplii offspring, days between brood production, and cyst and nauplii numbers was evaluated. Nauplii produced by specimens in the G1 were defined as those of G2 with there also being third (G3) and fourth (G4) generations. The aims were to evaluate Artemia salina in aquaculture conditions with the long-term aim of developing a system for "artemiculture". There was a larger number of cysts or nauplii per brood between G1 (60.7 ±â€¯10.9 nauplii or cysts/female) and subsequent generations, notably G2 (122 nauplii or cysts/female, P <  0.05). The mean number of cysts and nauplii per female increased from the first and last brood. Number of cysts produced per female increased markedly (P <  0.05) from G1 (54.5 ± 14.2) to G3 (128.9 ± 39.2). Percentage of females producing nauplii increased from G1 (20 %) to G4 (100 %). There was, therefore, an increase in percentage of ovoviviparous offspring (nauplii) per female (P <  0.05) from G1 (7%) to G4 (71 %). There were no differences, however, between mean numbers of broods per female, and numbers of days between broods. The results indicate there are variations in reproduction from oviparity to ovoviviparity as consecutive generations of Artemia salina are cultivated. In summary, there was a rapid adaptation of Artemia salina of Sidi El Hani to laboratory conditions.

Report on fetal mummification in the scalloped hammerhead shark Sphyrna lewini.

This study describes the fetal mummification process in two embryos of a 310 cm total length scalloped hammerhead shark Sphyrna lewini caught in southeastern Brazil, in December 2017. Fourteen embryos were observed in total, in which two males in the left uterus presented different stages of mummification. Both mummified embryos were covered by an exudate (i.e., a mucous substance), indicating a hematic mummification process. All embryos were at the placentotrophic stage of development, indicating that they were close to parturition. An intrinsic characteristic is suggested as possible etiology for this condition, such as umbilical torsion, because both embryos were at different sizes and, therefore, at different development stages. In addition, the sample size did not allow the authors to presume any pollution effect once only one female was observed. Finally, fetal mummification and other embryonic development disorders might have populational impacts due to reduction in embryo survival and, consequently, recruitment. For this reason and considering that S. lewini is categorized as a "critically endangered species," this study's results have conservational relevance.

Reversals in complex traits uncovered as reticulation events: Lessons from the evolution of parity-mode, chromosome morphology, and maternal resource transfer.

Complex traits include, among many others, the evolution of eyes, wings, body forms, reproductive modes, human intelligence, social behavior, diseases, and chromosome morphology. Dollo's law states that the evolution of complex traits is irreversible. However, potential exceptions have been proposed. Here, we investigated whether reticulation, a simple and elegant means by which complex characters may be reacquired, could account for suggested reversals in the evolution of complex characters using two datasets with sufficient genetic coverage and a total of five potential reversals. Our analyses uncovered a potential reversal in the evolution of parity mode and a potential reversal in the evolution of placentotrophy of fish (Cyprinodontiformes) as reticulation events. Moreover, in a reptile that exhibits a potential reversal from viviparity to oviparity (Zootoca vivipara), reticulation provided the most parsimonious explanation for sex chromosome evolution. Therefore, three of the five studied potential reversals were unraveled as reticulation events. This constitutes the first evidence that accounting for reticulation can fundamentally influence the interpretation of the evolution of complex traits, that testing for reticulation is crucial for obtaining robust phylogenies, and that complex ancestral characters may be reacquired through hybridization with a lineage that still exhibits the trait. Hybridization, rather than reappearance of ancestral traits by means of small evolutionary steps, may thus account for suggested exceptions to Dollo's law. Consequently, ruling out reticulation is required to claim the evolutionary reversal of complex characters and potential exceptions to Dollo's rule.

Precocious egg development in wild Calliphora vicina (Diptera: Calliphoridae) - An issue of relevance in forensic entomology?

The list of factors influencing the development of forensically important insects and the related effects on minimum post mortem (PMImin) estimations is long and well established by various authors in forensic entomology over the last decades. Despite the fact that several authors mention precocious egg development, i.e. first instar larva in the genital tract of some species of Calliphoridae, as a potential error source for PMImin estimations just two studies were performed to examine the occurrence of precocious eggs both in laboratory and field populations of blow flies. In the present study the occurrence of gravid females with precocious eggs in a wild population of Calliphora vicina in Frankfurt am Main was surveyed over 152 days and their seasonal distribution was analyzed as well as the influence of abiotic variables on their abundance. During the sampling occasions, 5.216 females were sampled of which 44 % were gravid. 54 % of all gravid females had a precocious egg/first instar larva in their genital tract. This number varied depending on the season and showed the highest amount in spring with almost 64 % of all gravid females. Hence, precocious eggs in wild populations of blow flies can occur much more frequently than mentioned in forensic literature. Consequences for the evaluation of entomological evidence in forensic casework should not be overrated since focusing alone on the largest larva in a sample is not recommended as the sole reference in an entomological PMImin estimation. The entomological report has to justify its findings, discuss different options and finally state what is considered to be the most likely scenario based on the complete evidence (e.g. including all species and relevant age cohorts as well as succession data) and the case specific history.

Premature birth stunts early growth and is a possible driver of stress-induced maternal effects in the guppy Poecilia reticulata.

We tested the effects of gestational stress, principally in the form of alarm cue extracted from the skin of conspecifics, on reproduction in female guppies (Poecilia reticulata) and the growth and behaviour of their offspring. Offspring from mothers exposed to alarm cue exhibited stunted growth in the first few days post-partum, which appeared to be mediated by shortening of the gestation period, the length of which directly correlated with growth rate within the first 6 days post-partum. Mature offspring did not differ in behaviour or stress responses compared with controls and so the effects of maternal predation stress did not appear to persist into adulthood. A different form of gestational stress, dietary restriction, did not significantly affect offspring growth, though brood size was reduced, suggesting that the effects of predation stress were not mediated by differences in resource demand or consumption.

Development of germplasm repositories to assist conservation of endangered fishes: Examples from small-bodied livebearing fishes.

Germplasm repositories are a necessary tool for comprehensive conservation programs to fully preserve valuable genetic resources of imperiled animals. Cryopreserved germplasm can be used in the future to produce live young for integration into other conservation projects, such as habitat restoration, captive breeding, and translocations; thus compensating for genetic losses or negative changes that would otherwise be permanent. Although hundreds of cryopreservation protocols for various aquatic species have been published, there are great difficulties in moving such research forward into applied conservation projects. Successful freezing of sperm in laboratories for research does not guarantee successful management and incorporation of genetic resources into conservation programs in reality. The goal of the present review is to provide insights and practical strategies to apply germplasm repositories as a real-world tool to assist conservation of imperiled aquatic species. Live-bearing (viviparous) fishes are used as models herein to help explain concepts because they are good examples for aquatic species in general, especially small-bodied fishes. Small live-bearing fishes are among the most at-risk fish groups in the world, and need urgent conservation attention. However, development of germplasm repositories for small live-bearing fishes is challenged by their unusual reproductive characteristics, such as formation of sperm bundles, initiation of spermatozoa motility in an isotonic environment, internal fertilization and gestation, and the bearing of live young. The development of germplasm repositories for goodeids and Xiphophorus species can provide examples for addressing these challenges. Germplasm repositories must contain multiple basic components, including frozen samples, genetic assessment and information systems. Standardization and process generalization are important strategies to help develop reliable and efficient repositories. An ideal conservation or recovery program for imperiled species should include a comprehensive approach, that combines major concerns such as habitat (by restoration projects), population propagation and maintenance (by captive breeding or translocation projects), and preservation of genetic diversity (by repository projects). In this context, strong collaboration among different sectors and people with different expertise is a key to the success of such comprehensive programs.

Ovaries and oogenesis in an epizoic dermapteran, Hemimerus talpoides (Dermaptera, Hemimeridae): Structural and functional adaptations to viviparity and matrotrophy.

The Dermaptera are traditionally classified in three taxa: the free living Forficulina and two viviparous (matrotrophic) groups, the Hemimerina and Arixeniina. Recent molecular and histological analyses suggest that both matrotrophic groups should be nested among the most derived taxon of the Forficulina, the Eudermaptera. We present results of ultrastructural analyses of ovary/ovariole morphology and oogenesis in a representative of the Hemimerina, Hemimerus talpoides (Walker, 1871). Our results strongly reinforce the idea that the Hemimerina should be classified within the Eudermaptera. We show additionally that the ovaries of the studied species are characterized by two peculiar modifications, i.e. the presence of numerous tracheoles in contact with the basement lamina covering the ovarioles, and an unusual development of the ovariole stalks. We believe that both characters are related to viviparity and unconventional "intra-ovariolar" embryo development. Finally, our study also indicates that the oocytes of H. talpoides reveal characters apparently associated with a matrotrophic type of embryo nourishment. They are completely yolkless and devoid of the typical, multilayered egg envelopes; instead, they comprise unconventional organelles (para-crystalline stacks of endoplasmic reticulum cisternae and translucent vacuoles) that seem to function after initiation of embryonic development. Thus, the ovaries as well as the oocytes of H. talpoides are characterized by an exceptional mixture of features shared with derived dermapterans and adaptations to matrotrophy.

The Regulation of Uterine Proinflammatory Gene Expression during Pregnancy in the Live-Bearing Lizard, Pseudemoia entrecasteauxii.

The evolutionary transition from egg-laying to live-bearing in amniote vertebrates (reptiles and mammals) requires the development of a closer association between the maternal and embryonic tissue to facilitate gas and nutrient exchange with the embryo. Because the embryo is an allograft to the father and mother, it could be considered foreign by the maternal immune system and thus be immunologically rejected during pregnancy. In eutherian ("placental") mammals, the proinflammatory genes interleukin 1B (IL1B), tumor necrosis factor (TNF) and tumor necrosis factor receptor superfamily 1A (TNFRSF1A) are tightly regulated in the pregnant uterus to prevent embryonic rejection. We tested whether inflammation is similarly regulated in pregnant viviparous reptiles by comparing the expression of IL1B, TNF, and TNFRSF1A in the pregnant and nonpregnant uterus of the viviparous lizard, Pseudemoia entrecasteauxii. We found statistically significant support for the downregulation of pregnant uterine TNF mRNA expression in P. entrecasteauxii, but no statistically significant changes in mRNA expression of TNFRSF1A or IL1B between pregnant and nonpregnant uteri. Although these genes are apparently not regulated at the transcriptional level, our immunofluorescence microscopy analyses nonetheless demonstrate that the IL1B proteins are stored intracellularly during pregnancy, possibly resulting in inhibition of inflammatory response. We therefore conclude that processes of both transcriptional (TNF) and posttranslational (IL1B) gene regulation may reduce inflammation in the pregnant uterus of this viviparous reptile. Our study is important because it demonstrates that regulating the maternal immune system to prevent embryonic rejection may be important in reptilian pregnancy as it is in mammalian pregnancy.

Reproductive cycle and maternal-embryonic nutritional relationship of shovelnose guitarfish Pseudobatos productus in the Gulf of California.

Samples of the shovelnose guitarfish Pseudobatos productus were collected on board a vessel and at landings of artisanal commercial fisheries in the Gulf of California from May 2004 to June 2007. Samples of 650 females, 2047 embryos and 484 uterine eggs were examined. The reproductive cycle is annual, ovulation and parturition occur in July, the uterine eggs are in diapause for 9 months (July-March) before an accelerated growth of embryos of 3 months. Histological analyses of the uterine wall of pregnant females suggested that no secretions were used for embryo nourishment. The standard percentage of water content was 48·6% in fertilized eggs and 80·75% in full-term embryos. Dry mass loss during embryonic development was 16·3% and the chemical balance of development was 0·84. This indicates that P. productus is a strictly lecithotrophic, viviparous species, that makes no maternal contribution of nutrients during embryonic development.

Immune variation during pregnancy suggests immune component-specific costs of reproduction in a viviparous snake with disparate life-history strategies.

Growing evidence suggests the existence of trade-offs between immune function and reproduction in diverse taxa. Among vertebrates, however, there is still a taxonomic bias toward studies in endotherms, particularly birds. We tested the hypothesis that reproduction entails immune-related costs in the viviparous garter snake, Thamnophis elegans, from populations that exhibit two life-history strategies, termed ecotypes, with contrasting paces of life. Between the two ecotypes, we predicted lower immune function in gravid than non-gravid females of both strategies, but with relatively larger immunity costs in the ecotype that generally invests more in current reproduction. Across individuals, we predicted greater immune costs for females investing more in the present specific reproductive event (i.e., higher fecundity) irrespective of their ecotype. We assessed leukocyte profiles and measured bactericidal capacity of plasma (innate immunity) and T- and B-lymphocyte proliferation (adaptive immunity) in gravid and non-gravid females in their natural habitats. We also collected data on reproductive output from these same gravid females brought into captivity. Gravid females of both ecotypes showed lower T-lymphocyte proliferation responses to concanavalin A than non-gravid females, but no differential costs were observed between ecotypes. The remaining immune variables did not vary between gravid and non-gravid females. Among gravid females within each ecotype, those with larger reproductive output showed lower total leukocyte counts, suggesting a fecundity-dependent trade-off. Our study contributes to the comparative ecoimmunology of vertebrates by highlighting the immune component-specificity of trade-offs between reproduction and immune function and showing that costs can be fecundity-dependent in some, but not all cases.

Mechanisms underlying maternal care in a viviparous snake, Sistrurus miliarius: Does maternal body condition, corticosterone, or arginine vasotocin mediate post-birth maternal investment?

The level of parental investment in free-living offspring varies greatly within and among vertebrate taxa, and the mechanisms that mediate investment are likely targets of selection in the evolution of reproductive strategies. In mammalian and avian systems, individual investment is adjusted according to parental energetic status, and regulatory mechanisms have been described. Parental care is also a component of the life history of several groups of squamates and archosaurs, but little to nothing is known regarding the mechanisms that underlie individual variation in parental investment in these groups. Therefore, we examined the relationships among maternal body condition, corticosterone, arginine vasotocin (AVT), and maternal care in postparturient pigmy rattlesnakes. Energetic status was manipulated in pregnant females by supplemental feeding, and AVT was manipulated in postparturient mothers by intraperitoneal injection. Circulating corticosterone and body condition were recorded in postparturient mothers. Mother-offspring spatial relationships were analyzed to determine the closeness of mother-offspring associations. No significant relationship between maternal body condition and baseline corticosterone was observed in mothers, and no significant relationship was found between corticosterone and the level of maternal association with offspring. Manipulation of AVT did not stimulate maternal care. There was a strong and repeatable positive relationship between maternal postparturient body condition and the level of maternal association with offspring. The lack of a significant correlation between body condition and corticosterone does not support the hypothesis that a postparturient glucocorticoid response drives the observed condition-dependence of maternal offspring association.

Ultrasonography: a method used for pregnancy imaging of the fire salamander (Salamandra salamandra).

Ultrasound imaging has more frequently been used in veterinary medicine of amphibians and reptiles. In this study, we have verified the usefulness of ultrasound imaging in pregnancy determination of the fire salamander Salamandra salamandra. We have also undertaken to estimate the number of larvae and their developmental stage directly in the oviducts. Three gravid females from Lower Silesia (southern Poland) were examined. Due to the small size of the scanned animals, and the particular arrangement of embryos in the oviducts and ultrasound beams dispersal, the method proved to be inaccurate. Therefore, the minimum number of well-visualized larvae was determined. The maximum number of larvae was established on the basis of the visible fragments of embryos. After birth, we found that the number of larvae born was included in the "min-max" range in only one case. In the remaining two salamanders the number of larvae was higher than estimated in 3 to 7 individuals. The results showed that ultrasound imaging allows the minimum number of larvae in salamander; oviducts to be specified. However, total length measurements were possible only for single and clearly visible embryos.

Characterisation of kisspeptin system genes in an ovoviviparous teleost: Sebastes schlegeli.

Kisspeptins are neuropeptides that play important roles in the reproduction and the onset of puberty in vertebrate by activating their receptor, Kissr. In the present study, we first isolated kiss1 and kissr4 genes from an ovoviviparous fish, the black rockfish (Sebastes schlegeli) by homologue cloning. Phylogenetic analysis indicated that the kiss and kissr of S. schlegeli belonged to kiss1 and kissr4 respectively. Quantitative real-time PCR analysis showed that the kissr4 was expressed mainly in the brain and testis, while the kiss1 was expressed predominantly in the heart of both sexes. As for the different gonadal maturation stages the kiss1 showed different expression patterns in different tissues. During the early development stage, expression levels of the ligand and receptor genes showed similar increasing trends. The promoter region of kissr4 contained several putative transcription factor (TF) binding sites which may have the function of regulating kisspeptin system gene expression, providing potential targets for future in-depth investigation. These results together confirmed that the kisspeptin system in S. schlegeli may be involved in reproduction and other activities. Furthermore, our study laid the groundwork for further learning about the evolution and function of kisspeptin system in fish even vertebrate.

Effects of anthropogenic salinization on biological traits and community composition of stream macroinvertebrates.

Salinization of rivers resulting from industrial discharge or road-deicing can adversely affect macroinvertebrates. Trait-based approaches are a promising tool in ecological monitoring and may perform better than taxonomy-based approaches. However only little is known how and which biological traits are affected by salinization. We investigated the effects of anthropogenic salinization on macroinvertebrate communities and biological traits in the Werra River, Germany and compared the taxonomic and trait response. We found a change in macroinvertebrate community and trait composition. Communities at saline sites were characterized by the three exotic species Gammarus tigrinus, Apocorophium lacustre and Potamopyrgus antipodarum. The frequencies of trait modalities long life cycle duration, respiration by gill, ovoviviparity, shredder and multivoltinism were statistically significantly increased at saline sites. The trait-based ordination resulted in a higher explained variance than the taxonomy-based ordination, indicating a better performance of the trait-based approach, resulting in a better discrimination between saline and non-saline sites. Our results are in general agreement with other studies from Europe, indicating a trait convergence for saline streams, being dominated by the traits ovoviviparity and multivoltinism. Three further traits (respiration by gill, life cycle duration and shredders) responded strongly to salinization, but this may primarily be attributed to the dominance of a single invasive species, G. tigrinus, at the saline sites in the Werra River.

Reproduction in female copperhead snakes (Agkistrodon contortrix): plasma steroid profiles during gestation and post-birth periods.

We investigated levels of plasma progesterone (P4), 17ß-estradiol (E2), testosterone (T), and corticosterone (CORT) during gestation and post-birth periods in wild-collected female copperhead snakes (Viperidae; Agkistrodon contortrix). We also sought to determine whether CORT levels at (or near) birth dramatically increase and were correlated with duration of labor and litter size. Specifically, pregnant subjects (N = 14) were collected during early- to mid-gestation, held in the laboratory, and repeatedly bled to obtain plasma for steroid analyses. Progesterone showed significant changes during gestation, with the highest levels at the onset of sampling (circa 50 days prior to birth); P4 progressively declined up to parturition, and basal levels were observed thereafter. At the onset of sampling, E2 was at peak levels and fell sharply at circa 30 days prior to birth, a trend observed throughout the post-birth sampling period. Throughout the entire sampling period, T was undetectable. Although CORT showed no significant changes during gestation and several days following parturition, there was a highly significant peak at the time of birth. Our findings mirror the results of previous studies on pregnancy and steroid hormones of other live-bearing snakes, lizards, and mammals. As expected, there was a significant relationship between duration of labor and litter size; however, although levels of CORT did not achieve significance, there was a positive trend with litter size. We suggest that elevation of CORT at birth is involved in the mobilization and regulation of energy stores necessary for the physiological process of parturition and as a possible mechanism to trigger birth.

Innate immune performance and steroid hormone profiles of pregnant versus nonpregnant cottonmouth snakes (Agkistrodon piscivorus).

Squamates (lizards and snakes) have independently evolved viviparity over 100 times, and exhibit a wide range of maternal investment in developing embryos from the extremes of lecithotrophic oviparity to matrotrophic viviparity. This group therefore provides excellent comparative opportunities for studying endocrine and immune involvement during pregnancy, and their possible interactions. We studied the cottonmouth (Agkistrodon piscivorus), since they exhibit limited placentation (e.g., ovoviviparity), allowing comparison with squamate species hypothesized to require considerable maternal immune modulation due to the presence of a more extensive placental connection. Furthermore, the cottonmouth's biennial reproductive cycle provides an opportunity for simultaneously comparing pregnant and non-pregnant females in the wild. We document significantly elevated concentrations of progesterone (P4) and significantly lower concentrations of estradiol (E2) in pregnant females relative to non-pregnant females. Pregnant females had lower plasma bacteria lysis capacity relative to non-pregnant females. This functional measure of innate immunity is a proxy for complement performance, and we also determined significant correlations between P4 and decreased complement performance in pregnant females. These findings are consistent with studies that have determined P4's role in complement modulation during pregnancy in mammals, and thus this study joins a growing number of studies that have demonstrated convergent and/or conserved physiological mechanisms regulating viviparous reproduction in vertebrates.

The physiology functions of estrogen receptor α (ERα) in reproduction cycle of ovoviviparous black rockfish, Sebastes schlegeli Hilgendorf.

This paper revealed the expression pattern of ERα in the ovoviviparous teleost, Sebastes schlegeli. In this paper, we isolated the cDNA encoding for estrogen receptor alpha of black rockfish (S. schlegeli) from its ovary, named as black rockfish ERα (brfERα). The cDNA sequence of brfERα consists of 2972bp with an open reading frame encoding a 624 amino acid putative protein which exhibits high identities with other teleosts'. The tissue distribution of brfERα mRNA was examined using RT-PCR. BrfERα showed generally expressions in most tissues of female black rockfish, besides, the higher degree of expressions were seen in ovary, liver, duodenum and fat, whereas it had a more restricted distribution in male fish. In ovary, the expression level of brfERα was as similar as the serum levels of E2 and P in female. However, it was a different situation in male, where the serum concentration of E2 showed higher levels after spermiation and Serum concentration of P did not show any significant changes during a year. Based on the present study, it is supposed that brfERα plays an important role in ovary and other target organs during the reproductive cycle, Further studies will focus on the transcriptional regulation and localization of brfERα in gonad in order to get a better understand of the physiological function of brfERα in ovoviviparous teleost. This study indicates that the black rockfish may be a good candidate for understanding the mechanism of estrogen in ovoviviparous fish.