Semen promotes oocyte development in Sebastesschlegelii elucidating ovarian development dynamics in live-bearing fish.

In some vertebrates and invertebrates, semen release factors affecting female physiology and behavior. Here, we report that semen delivered to females is potentially beneficial for promoting oocyte development in a viviparous teleost, Sebastes schlegelii. 88% of mated ovaries develop normally and give birth to larval fish, whereas 61% of non-mated ovaries are arrested in the previtellogenic stage. Semen's significant role (p < 0.0001) in promoting oocyte development may involve remodeling follicular cells and regulating the expression of the extracellular matrix, which facilitates cell communication. Furthermore, the ovarian response to semen may influence the brain, affecting hormone release, follicular cell development and steroid production, and crucial for oocyte growth. This mechanism, which could potentially delay maternal investment in offspring until male genetic input occurs to avoid energy wastage, has not been previously described in teleosts. These findings enhance our understanding of ovarian development in viviparous fish, with broader implications for reproductive biology.

Dissecting the dynamic cellular transcriptional atlas of adult teleost testis development throughout the annual reproductive cycle.

Teleost testis development during the annual cycle involves dramatic changes in cellular compositions and molecular events. In this study, the testicular cells derived from adult black rockfish at distinct stages - regressed, regenerating and differentiating - were meticulously dissected via single-cell transcriptome sequencing. A continuous developmental trajectory of spermatogenic cells, from spermatogonia to spermatids, was delineated, elucidating the molecular events involved in spermatogenesis. Subsequently, the dynamic regulation of gene expression associated with spermatogonia proliferation and differentiation was observed across spermatogonia subgroups and developmental stages. A bioenergetic transition from glycolysis to mitochondrial respiration of spermatogonia during the annual developmental cycle was demonstrated, and a deeper level of heterogeneity and molecular characteristics was revealed by re-clustering analysis. Additionally, the developmental trajectory of Sertoli cells was delineated, alongside the divergence of Leydig cells and macrophages. Moreover, the interaction network between testicular micro-environment somatic cells and spermatogenic cells was established. Overall, our study provides detailed information on both germ and somatic cells within teleost testes during the annual reproductive cycle, which lays the foundation for spermatogenesis regulation and germplasm preservation of endangered species.

Transforming Undesired Corrosion Products into a Nanoflake-Array Functional Layer: A Gelatin-Assistant Modification Strategy for High Performance Zn Battery Anodes.

As corrosion products of Zn anodes in ZnSO4 electrolytes, Zn4 SO4 (OH)6 ·xH2 O with loose structure cannot suppress persistent side reactions but can increase the electrode polarization and induce dendrite growth, hindering the practical applications of Zn metal batteries. In this work, a functional layer is built on the Zn anode by a gelatin-assistant corrosion and low-temperature pyrolysis method. With the assistant of gelatin, undesired corrosion products are converted into a uniform nanoflake array comprising ZnO coated by gelatin-derived carbon on Zn foil (denoted Zn@ZnO@GC). It is revealed that the gelatin-derived carbons not only enhance the electron conductivity, facilitate Zn2+ desolvation, and boost transport/deposition kinetics, but also inhibit the occurrence of hydrogen evolution and corrosion reactions on the zincophilic Zn@ZnO@GC anode. Moreover, the 3D nanoflake array effectively homogenizes the current density and Zn2+ concentration, thus inhibiting the formation of dendrites. The symmetric cells using the Zn@ZnO@GC anodes exhibit superior cycling performance (over 7000 h at 1 mA cm-2 /1 mAh cm-2 ) and without short-circuiting even up to 25 mAh cm-2 . The Zn@ZnO@GC||NaV3 O8 full cell works stably for 5000 cycles even with a limited N/P ratio of ≈5.5, showing good application prospects.

Insight into Sulfur-Containing Zwitter-Molecule Boosting Zn Anode: from Electrolytes to Electrodes.

Numerous organic electrolytes additives have been reported to improve Zn anode performance in aqueous Zn metal batteries (AZMBs). However, the modification mechanism needs to be further revealed in consideration of different environments for electrolytes and electrodes during the charge-discharge process. Herein, sulfur-containing zwitter-molecule (methionine, Met) is used as an additive for ZnSO4 electrolytes. In electrolytes, Met reduces the H2 O coordination number and facilitates the desolvation process by virtue of functional groups (─COOH, ─NH2 , C─S─C), accelerating Zn2+ transference kinetics and decreasing the amount of active water. On electrodes, Met prefers to adsorb on Zn (002) plane and further transforms into a zincophilic protective layer containing C─SOx ─C through an in situ electrochemical oxidization, suppressing H2 evolution/corrosion reactions and guiding dendrite-free Zn deposition. By using Met-containing ZnSO4 electrolytes, the Zn//Zn cells show superior cycling performance under 30 mA cm-2 /30 mA h cm-2 . Moreover, the full cells Zn//NH4 V4 O10 full cells using the modified electrolytes exhibit good performance at temperatures from -8 to 60 °C. Notably, a high energy density of 105.30 W h kg-1 can be delivered using a low N/P ratio of 1.2, showing a promising prospect of Met electrolytes additives for practical use.

Maximum Correntropy Filtering for Complex Networks With Uncertain Dynamical Bias: Enabling Componentwise Event-Triggered Transmission.

This article is concerned with the maximum correntropy filtering (MCF) problem for a class of nonlinear complex networks subject to non-Gaussian noises and uncertain dynamical bias. With aim to utilize the constrained network bandwidth and energy resources in an efficient way, a componentwise dynamic event-triggered transmission (DETT) protocol is adopted to ensure that each sensor component independently determines the time instant for transmitting data according to the individual triggering condition. The principal purpose of the addressed problem is to put forward a dynamic event-triggered recursive filtering scheme under the maximum correntropy criterion, such that the effects of the non-Gaussian noises can be attenuated. In doing so, a novel correntropy-based performance index (CBPI) is first proposed to reflect the impacts from the componentwise DETT mechanism, the system nonlinearity, and the uncertain dynamical bias. The CBPI is parameterized by deriving upper bounds on the one-step prediction error covariance and the equivalent noise covariance. Subsequently, the filter gain matrix is designed by means of maximizing the proposed CBPI. Finally, an illustrative example is provided to substantiate the feasibility and effectiveness of the developed MCF scheme.

Identification, Characterization and Functional Analysis of Fibroblast Growth Factors in Black Rockfish (Sebastes schlegelii).

Fibroblast growth factors (FGFs) are short polypeptides that play essential roles in various cellular biological processes, including cell migration, proliferation, and differentiation, as well as tissue regeneration, immune response, and organogenesis. However, studies focusing on the characterization and function of FGF genes in teleost fishes are still limited. In this study, we identified and characterized expression patterns of 24 FGF genes in various tissues of embryonic and adult specimens of the black rockfish (Sebates schlegelii). Nine FGF genes were found to play essential roles in myoblast differentiation, as well as muscle development and recovery in juvelines of S. schlegelii. Moreover, sex-biased expression pattern of multiple FGF genes was recorded in the species' gonads during its development. Among them, expression of the FGF1 gene was recorded in interstitial and sertoli cells of testes, promoting germ-cell proliferation and differentiation. In sum, the obtained results enabled systematic and functional characterization of FGF genes in S. schlegelii, laying a foundation for further studies on FGF genes in other large teleost fishes.

Transcriptome sequencing reveals ovarian immune response and development during female sperm storage in viviparous black rockfish (Sebastes schlegelii).

Black rockfish (Sebastes schlegelii) is a viviparous teleost fish whose spermatozoa were transferred into the female ovary cavity and stored for up to five months and then fertilized with the matured eggs. There is no clarity about the molecular characteristics of ovarian follicles during female sperm storage in Sebastes schlegelii. In this study, histological observation, transcriptomic analysis and hormone level detection were performed in ovaries at stages of pre-mating (PRM), post-mating (POM) and pre-fertilization (PRF). Histological observation displayed that oocytes developed from the primary growth (PG) stage to the mature stage during the three stages. Furthermore, somatic cells around the oocyte were proliferated and spermatozoa were found near the layer of epithelial cells. Transcriptomic analysis showed that there were 437 and 747 differentially expressed genes (DEGs) in ovarian comparison of PRM-vs-POM and POM-vs-PRF, respectively. GO enrichment and KEGG analysis revealed that lots of DEGs from PRM-vs-POM were linked to immune-related pathways, such as antigen processing and presentation, immune response, and complement and coagulation cascade. Meanwhile, seven DEGs associated with immune response were differentially expressed after spermatozoa treatment in ovarian tissue in vitro. While the DEGs from POM-vs-PRF were mostly enriched in the pathways related to homeostasis maintenance and cellular junction and metabolism. In addition, we found increased estrogen (E2) and 11-ketotestosterone (11-KT) level and decreased testosterone level in ovarian follicles during the sperm storage period by ELISA, suggesting that sex hormones are involved in the dynamic change of ovarian follicles. In total, this study could provide new hints for understanding the immune adaption and developmental signatures of ovarian follicles post copulation in black rockfish and other viviparous fish.

Particle-Filter-Based State Estimation for Delayed Artificial Neural Networks: When Probabilistic Saturation Constraints Meet Redundant Channels.

In this brief, the state estimation problem is investigated for a class of randomly delayed artificial neural networks (ANNs) subject to probabilistic saturation constraints (PSCs) and non-Gaussian noises under the redundant communication channels. A series of mutually independent Bernoulli distributed white sequences are introduced to govern the random occurrence of the time delays, the saturation constraints, and the transmission channel failures. A comprehensive redundant-channel-based communication mechanism is constructed to attenuate the phenomenon of packet dropouts so as to enhance the quality of data transmission. To compensate for the influence of randomly occurring time delays, the corresponding occurrence probability is exploited in the process of particle generation. In addition, an explicit expression of the likelihood function is established based on the statistical information to account for the impact of PSCs and redundant channels. By virtue of the modified operations of particle propagation and weight update, a particle-filter-based state estimation algorithm is proposed with mild restriction on the system type. Finally, an illustrative example with Monte Carlo simulations is provided to demonstrate the effectiveness of the developed state estimation scheme.

Portevin-Le Chatelier Characterization of Quenched Al-Mg Alloy Sheet with Different Mg Concentrations.

In the present study, the PLC characteristic parameters and DSA mechanism of Al-(2.86~9.41) Mg alloy sheets were investigated during tensile testing at room temperature with a tensile rate of 1 × 10-3 s-1. On the basis of the solution Mg concentrations in the α-Al matrix, the initial vacancy concentration, the second-phase particle configuration and the recrystallized grain configuration are almost the same by quenching treatment. The results show that the type of room-temperature tensile stress-strain curves of quenched Al-(2.86~9.41) Mg alloy sheets varied according to the Mg content. The type of stress-strain curve of the Al-2.86 Mg alloy sheet was B + C, while the type of stress-strain curve of the Al-(4.23~9.41) Mg alloy sheets was C. When the quenched Al-(2.86~9.41) Mg alloy sheets were stretched at room temperature, the strain cycle of the rectangular waves corresponding to the high stress flow ΔεTmax and stress drop amplitude Δσ on the zigzag stress-strain curve of alloy sheets increased with increasing the Mg content. Moreover, the strain cycle of ΔεTmax and Δσ on the stress-strain curve of alloy sheets increased gradually with increasing tensile deformation. The yield stress of quenched Al-(2.86~9.41) Mg alloy sheets increased gradually with increasing the Mg content. Moreover, the critical strain corresponding to yield stress εσ and the critical strain corresponding to the occurrence of the PLC shearing band εc of alloy sheets both increased with increasing the Mg content. However, the difference in flow strain value Δεc-σ between εc and εσ of alloy sheets decreased gradually with increasing the Mg content.

Genome-wide identification, characterization and expression profiling of TRAF family genes in Sebastes schlegelii.

Tumor necrosis factor receptor-associated factors (TRAFs) are signaling mediators for Toll-like receptor (TLR) and tumor necrosis factor (TNFR) superfamily that play important roles in organism immune response. However, reports on systematic identification of TRAF gene family in teleost fish and the function of TRAFs in innate immunity of black rockfish (Sebastes schlegelii) are lacked. In our study, eight TRAF genes were identified and characterized, namely, SsTRAF2a, SsTRAF2a-like, SsTRAF2b, SsTRAF3, SsTRAF4, SsTRAF5, SsTRAF6 and SsTRAF7 in S. schegelii. Furthermore, we analyzed their sequences, conserved domains, gene structures, motif compositions, phylogeny, tissue expression patterns in healthy and Vibro. anguillarum challenged individuals. All the SsTRAFs contained typical conserved domain, including C-terminal MATH domain and N-terminal RING finger domain. Analyses of gene structures and motifs showed the distribution of exon-intron and conserved motifs in S. schegelii and serval other teleost fish. We also analyzed the expression file of SsTRAFs in five immune-relate organs, liver, spleen, kidney, gill and intestine in healthy and bacterial challenged fish. The results indicated that all SsTRAF member were widely involved in immune response after pathogenic bacteria infection. In summary, the analyses of TRAFs in S. schegelii will be helpful to better understand the diverse roles of TRAF genes in the innate immune response to bacterial challenge.

Establishment of myoblast cell line and identification of key genes regulating myoblast differentiation in a marine teleost, Sebastes schlegelii.

Skeletal myoblasts are activated satellite cells capable of proliferation and differentiation. Studies on mammalian myoblast differentiation and myogenesis could be carried out in vitro thanks to the availability of mouse myoblast cell line C2C12. Lacking of muscle cell line hinders the studies of teleost fish myogenesis. Here, we established a continuous skeletal muscle cell line from juvenile rockfish (Sebastes schlegelii) muscle using explant method and subcultured more than 50 passages for over 150 days. Stable expression of myoblast-specific marker, MyoD (myoblast determination protein) and the potential of differentiation into multi-nucleated skeletal myotubes upon induction suggested the cell line were predominately composed of myoblasts. Transcriptome analysis revealed a total of 4375 genes differentially expressed at four time points after the switch to differentiation medium, which were mainly involved in proliferation and differentiation of myoblasts. KIF22 (kinesin family member 22) and POLA1 (DNA polymerase alpha 1) were identified as the key genes involved in fish myoblast proliferation whereas MYL3 (myosin light chain 3) and TNNT2 (troponin T2) were determined as the crucial genes responsible for differentiation. In all, the continuous myoblasts cultured in this study provided a cell platform for future studies on marine fish myoblast differentiation and myogenesis. The molecular process of myoblast differentiation revealed in this study will open a window into the understanding of indeterminate muscle growth of large teleost.

A duplicated amh is the master sex-determining gene for Sebastes rockfish in the Northwest Pacific.

Teleost fish are the most diverse group of vertebrates and provide opportunities to study the evolution of sex determination (SD) systems. Using genomic and functional analyses, we identified a male-specific duplication of anti-Müllerian hormone (amh) gene as the male master sex-determining (MSD) gene in Sebastes schlegelii. By resequencing 10 males and 10 females, we characterized a 5 kb-long fragment in HiC_Scaffold_12 as a male-specific region, which contained an amh gene (named amhy). We then demonstrated that amhy is a duplication of autosomal amh that was later translocated to the ancestral Y chromosome. amha and amhy shared high-nucleotide identity with the most significant difference being two insertions in intron 4 of amhy. Furthermore, amhy overexpression triggered female-to-male sex reversal in S. schlegelii, displaying its fundamental role in driving testis differentiation. We developed a PCR assay which successfully identified sexes in two species of northwest Pacific rockfish related to S. schlegelii. However, the PCR assay failed to distinguish the sexes in a separate clade of northeast Pacific rockfish. Our study provides new examples of amh as the MSD in fish and sheds light on the convergent evolution of amh duplication as the driving force of sex determination in different fish taxa.

Genome-Wide Identification, Characterization and Expression Profiling of myosin Family Genes in Sebastes schlegelii.

Myosins are important eukaryotic motor proteins that bind actin and utilize the energy of ATP hydrolysis to perform a broad range of functions such as muscle contraction, cell migration, cytokinesis, and intracellular trafficking. However, the characterization and function of myosin is poorly studied in teleost fish. In this study, we identified 60 myosin family genes in a marine teleost, black rockfish (Sebastes schlegelii), and further characterized their expression patterns. myosin showed divergent expression patterns in adult tissues, indicating they are involved in different types and compositions of muscle fibers. Among 12 subfamilies, S. schlegelii myo2 subfamily was significantly expanded, which was driven by tandem duplication events. The up-regulation of five representative genes of myo2 in the skeletal muscle during fast-growth stages of juvenile and adult S. schlegelii revealed their active role in skeletal muscle fiber synthesis. Moreover, the expression regulation of myosin during the process of myoblast differentiation in vitro suggested that they contribute to skeletal muscle growth by involvement of both myoblast proliferation and differentiation. Taken together, our work characterized myosin genes systemically and demonstrated their diverse functions in a marine teleost species. This lays foundation for the further studies of muscle growth regulation and molecular mechanisms of indeterminate skeletal muscle growth of large teleost fishes.

Pax3 and Pax7 Exhibit Distinct and Overlapping Functions in Marking Muscle Satellite Cells and Muscle Repair in a Marine Teleost, Sebastes schlegelii.

Pax3 and Pax7 are members of the Pax gene family which are essential for embryo and organ development. Both genes have been proved to be markers of muscle satellite cells and play key roles in the process of muscle growth and repair. Here, we identified two Pax3 genes (SsPax3a and SsPax3b) and two Pax7 genes (SsPax7a and SsPax7b) in a marine teleost, black rockfish (Sebastes schlegelii). Our results showed SsPax3 and SsPax7 marked distinct populations of muscle satellite cells, which originated from the multi-cell stage and somite stage, respectively. In addition, we constructed a muscle injury model to explore the function of these four genes during muscle repair. Hematoxylin-eosin (H-E) of injured muscle sections showed new-formed myofibers occurred at 16 days post-injury (dpi). ISH (in situ hybridization) analysis demonstrated that the expression level of SsPax3a and two SsPax7 genes increased gradually during 0-16 dpi and peaked at 16 dpi. Interestingly, SsPax3b showed no significant differences during the injury repair process, indicating that the satellite cells labeled by SsPax3b were not involved in muscle repair. These results imply that the muscle stem cell populations in teleosts are more complicated than in mammals. This lays the foundation for future studies on the molecular mechanism of indeterminant growth and muscle repair of large fish species.

The Bdkrb2 gene family provides a novel view of viviparity adaptation in Sebastes schlegelii.

BACKGROUND: Black rockfish (Sebastes schlegelii) is a viviparous teleost. We proposed that the rockfish ovarian wall had a similar function to the uterus of mammals previously. In the present study, the well-developed vascular system was observed in the ovarian wall and the exterior surface of the egg membrane. In gestation, adaptation of the ovary vasculature to the rising needs of the embryos occurs through both vasodilation and neovascularization. Bdkrb2, encoding a receptor for bradykinin, plays a critical role in the control of vasodilatation by regulating nitric oxide production. RESULTS: Eight Bdkrb2 genes were identified in the black rockfish genome. These genes were located on chromosome 14, which are arranged in a tandem array, forming a gene cluster spanning 50 kb. Protein structure prediction, phylogenetic analysis, and transcriptome analysis showed that eight Bdkrb2 genes evolved two kinds of protein structure and three types of tissue expression pattern. Overexpression of two Bdkrb2 genes in zebrafish indicated a role of them in blood vessel formation or remodeling, which is an important procedure for the viviparous rockfish getting prepared for fertilization and embryos implantation. CONCLUSIONS: Our study characterizes eight Bdrkb2 genes in the black rockfish, which may contribute to preparation for fertilization and embryo implantation. This research provides a novel view of viviparity adaptation and lays the groundwork for future research into vascular regulation of ovarian tissue in the breeding cycle in black rockfish.

Molecular characterization and functional analysis of cyp11a and cyp11b in black rockfish (Sebastes schlegelii).

The cyp11 includes cyp11a and cyp11b in most mammals and teleosts, encoded cholesterol side chain lyase and 11ß-hydroxylase, respectively. It is essential in steroid hormone synthesis. However, studies on the regulation of cyp11 are limited, especially in teleosts. In this study, the molecular characterization and function of cyp11a and cyp11b of black rockfish was investigated. Both of them showed high homology with other teleost counterparts by phylogenetic analysis. The expression of cyp11a and cyp11b exhibited a clear sexually dimorphic pattern, with a higher expression level in testis than that of in ovaries. During the different developmental stages (40 dpf, 80 dpf, 190 dpf, 360 dpf, 720 dpf), the expression of cyp11a was earlier than cyp11b. In situ hybridization results showed that cyp11a and cyp11b were mainly expressed in oogonia and oocytes of the ovary. They were located in spermatogonia and interstitial compartment in the 1.5-year-old gonads, and spermatocytesgonia and the peritubular myoid cell of the testis in the 2.5-year-old gonads. To explore the distinct roles of cyp11a and cyp11b in gonads, oestrogen and androgens were used to stimulate the primary testicular and ovarian cells. The expressions of cyp11a and cyp11b were tested under different dose of 17α-methyltestosterone (17α-MT) and 17ß-estradiol (E2). The results showed cyp11a was significantly increased at 10-6  mol ml-1 of 17α-MT and 10-8  mol ml-1 of E2 in ovary and 10-10  mol ml-1 of 17α-MT and E2 in testis, while cyp11b was significantly decreased after 17α-MT and E2 treatment. These results indicated that cyp11a and cyp11b were likely to have different functions, and also implied they might play an important roles in the differentiation of gonads and the synthesis of steroids in black rockfish.

Neuroprotective effects of the aerial parts of Polygala tenuifolia Willd extract on scopolamine-induced learning and memory impairments in mice.

Alzheimer's disease is a common neurodegenerative disease characterized by progressive cognitive dysfunction and behavioral impairment. Aerial parts of Polygala tenuifolia Willd (APT) is a traditional Chinese medicine used for the treatment of amnesia. The present study aimed to investigate the protective effects of APT on scopolamine-induced learning and memory impairments in mice. Scopolamine-induced mice were used to determine the effects of APT on learning and memory impairment. Mice were orally administered with APT (25, 50 and 100 mg/kg) and piracetam (750 mg/kg) for 14 days, and intraperitoneally injected with scopolamine (2 mg/kg) from days 8 to 14. Morris water maze and step-down tests were performed to evaluate learning and memory. Levels of acetylcholine (ACh), choline acetyltransferase (ChAT), acetylcholinesterase (AChE), interleukin (IL)-1ß, IL-10 and brain-derived neurotrophic factor (BDNF) in the hippocampus and frontal cortex were measured by ELISA. Superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH) were measured via biochemical detection. The results demonstrated that APT ameliorated learning and memory impairment in scopolamine-induced mice. Correspondingly, APT significantly increased ACh and ChAT levels in the hippocampus and prefrontal cortex of scopolamine-induced mice. Additionally, treatment with APT significantly increased BDNF and IL-10 levels, and decreased IL-1ß and AChE levels in the same mice. Furthermore, APT significantly increased SOD activity and GSH content, and decreased MDA levels in brain tissue. These results indicated that APT may ameliorate learning and memory impairment by regulating cholinergic activity, promoting BDNF and inhibiting neuroinflammation and oxidative stress.

Molecular characterization and expression analysis of foxo3l in response to exogenous hormones in black rockfish (Sebastes schlegelii).

As a crucial member of the Forkhead Box family, class O (FoxO) plays an essential role in growth, cell differentiation, metabolism, immunization, and apoptosis. Meanwhile, FoxO3 is the primary regulator and effective inhibitor of primordial follicle activation. In this study, seven foxo genes were identified in black rockfish (Sebastes schlegelii), including two foxo1 genes (foxo1a, foxo1b), two foxo3 genes (foxo3, foxo3l), one foxo4 gene, and two foxo6 genes (foxo6a, foxo6b). foxo3l was derived from teleost-specific whole-genome duplication events. Evaluation of tissue expression pattern revealed that foxo3l displayed sexually dimorphic expression with a high level in the ovary and spatial expression only in the cytoplasm of follicle cells and oocytes. When the ovaries were stimulated by estrogen and gonadotropin, foxo3l expression was remarkably reduced, and the effect of androgen was completely different. We considered that foxo3l lost its ability to inhibit follicular precocity because of mass ovulation by hormone stimulation, resulting in its decreased expression. Such evidence indicated that foxo3l is an important regulator of reproduction-related functions in black rockfish. This study provides new insights into foxo3l genes for further functional research in teleost.

A chromosome-level genome of black rockfish, Sebastes schlegelii, provides insights into the evolution of live birth.

The black rockfish (Sebastes schlegelii) is a teleost in which eggs are fertilized internally and retained in the maternal reproductive system, where they undergo development until live birth (viviparity). In the present study, we report a chromosome-level black rockfish genome assembly. High-throughput transcriptome analysis (RNA-seq and ATAC-seq) coupled with in situ hybridization (ISH) and immunofluorescence reveal several candidate genes for maternal preparation, sperm storage and release, and hatching. We propose that zona pellucida (ZP) proteins retain sperm at the oocyte envelope, while genes in two distinct astacin metalloproteinase subfamilies serve to release sperm from the ZP and free the embryo from chorion at prehatching stage. We present a model of black rockfish reproduction, and propose that the rockfish ovarian wall has a similar function to the uterus of mammals. Together, these genomic data reveal unprecedented insights into the evolution of an unusual teleost life history strategy, and provide a sound foundation for studying viviparity in nonmammalian vertebrates and an invaluable resource for rockfish ecological and evolutionary research.