Search Results (235)

Megalobrama terminalis is a significant aquatic fish in South China, renowned for its tasty meat. Nonetheless, related studies are deficient concerning the gonadal development of M. terminalis. This paper presents the first comparative transcriptome analysis of the gonads of female and male M. terminalis. A total of 84,886 unigenes were assembled, with 42,322 effectively annotated to the Nr, SwissProt, KEGG, KOG, and GO databases. Furthermore, comparative transcriptomic analysis of M. terminalis was conducted to examine its gonadal development. A total of 14,972 differentially expressed genes (DEGs) were discovered. In the testis, the expression of 11,928 unigenes was significantly upregulated, while 3044 were significantly downregulated. Numerous DEGs associated with steroidogenesis, gonadal differentiation and development, and gametogenesis in teleost fish were identified. The results provide empirical support for further study of genes and pathways associated with sex determination and gonadal differentiation in teleost fish. Full article

This study elucidates the role of the steroidogenic acute regulatory protein (StAR) in sex steroid hormone dynamics and the gonadal development of the commercially important marine bivalve ark shell Scapharca broughtonii. The sequence of the StAR gene was obtained and verified from the transcriptome of ark shell, then the tissue localization and expression pattern during the gonad development of the StAR gene were detected by in situ hybridization and quantitative real-time PCR, respectively. Additionally, the concentrations of three critical sex steroid hormones (progesterone, testosterone, and estradiol) were measured throughout gonadal development using enzyme-linked immunosorbent assay (ELISA). The results showed that the length of the coding region of StAR was 1446 bp, encoding 481 amino acids. The results of qRT-PCR showed that the expression of the StAR gene varied with gonadal development, increased from the early active stage to the development stage, and decreased from the mature stage to the spent stage. Notably, the expression level in ovaries was higher than that in testes, suggesting the potential involvement of StAR in sex differentiation and gonadal development. Additionally, the results indicated that progesterone, testosterone, and estradiol accounted for 80%, 10%, and 10% of the total hormone content in the gonads, respectively. Correlation analysis revealed a highly significant strong positive correlation between progesterone/estradiol levels and StAR gene expression, demonstrating that StAR serves as a key regulator in sex steroid hormone biosynthesis. These findings provide crucial molecular evidence for StAR-mediated steroidogenesis in bivalve reproduction, offering fundamental insights into invertebrate endocrinology. Full article

Global warming raises surface water temperatures, impacting fish alongside pollutants, such as ubiquitous xenoestrogens. Combined stressor effects are poorly studied but likely to worsen impacts and hinder biota adaptation, warranting further research. Unadapted fish face heightened risks. The liver is a vital metabolic organ, sensitive to temperature and xenoestrogens, eventually adjusting hepatocyte size and number to ensure survival, growth, and reproduction. This study assessed, for the first time, the impact of exposure (45 days) to thermal stress (29 °C versus 26 °C) and ethinylestradiol (EE2, 5 ng/L) on male guppies, primarily on body and quantitative liver morphology. Higher temperature reduced body mass (14%) and standard length (3.6%) gain. EE2 exposure reduced body mass increase (14%), hepatosomatic index (20%), and the volumes of the liver (32%), hepatocytes (16%), and their nuclei (17%). The nucleus-to-cytoplasm ratio and total hepatocyte number remained stable. No histopathological lesions existed. Guppies appear to have adapted to stressors by reducing hepatocyte size and utilizing lipid reserves, yet they exhibited deficits in body growth and hepatosomatic index. Gonadal maturation was unaffected. Only under EE2 at 29 °C did hepatocytes show minimal lipid droplet content (less vacuolation). This indicated exhausted reserves, reinforcing how heat and toxicants interact to exacerbate impacts. Full article

Urogenital cannulation is a traditional method used in aquaculture to achieve sexual differentiation, but it is considered invasive. Ultrasonography is a valuable non-invasive tool for determining sex and gonadal development in fish species like mullet (Mugil liza) and Brazilian sardine (Sardinella brasiliensis) that lack sexual dimorphism. The methodology involves emitting high-frequency sound waves (20 MHz to 20,000 MHz) above the human hearing range. These waves interact with the tissues of the body, producing echoes that are detected by a transducer. The echoes are then processed by computer graphics to generate detailed images of the internal structures of the organism. This allows for the determination of the sex of fish based on the sonographic features of the tissues. For instance, in male fish, hypoechogenic structures reflect fewer sound waves, leading to darker images. Conversely, in female fish, hyperechogenic tissues reflect more sound waves, resulting in lighter images. It is possible to classify the gonadal maturation stage based on differences in image texture. This non-invasive method eliminates the need for specimen dissection. It is especially valuable when the goal is to preserve the spawners’ life and integrity. This review emphasizes the application of this technology in aquaculture, specifically targeting fish from the Clupeidae and Mugilidae families. Full article

The giant freshwater prawn (Macrobrachium rosenbergii, GFP) is a highly valuable crustacean species in global aquaculture. However, a social hierarchy exists among the distinct male morphotypes, specifically blue-clawed males (BC), orange-clawed males (OC), and small males (SMs). In this study, to identify the specific metabolites among BC, OC, and SM, hemolymph samples were collected for the untargeted liquid chromatography–mass spectrometry metabolomics (LC–MS). A total of 172, 546, and 578 significantly different metabolites (SDMs) were identified in OC vs. BC, SM vs. BC, and SM vs. OC, respectively. Notably, creatine and glutamate in BC males likely enhance their aggressive behavior through improved energy metabolism. In the SM group, the up-regulation of prostaglandin E3, testosterone, and arachidonic acid may lead to premature gonadal maturation and enhance immunity. Serotonin, Glu-Pro, and pentanoylcarnitine detected in OC males reflect their physiological need for rapid growth and adaptation to social behaviors. In the SM group, the up-regulation of prostaglandin E3, arachidonic acid, and testosterone may promote premature gonadal maturation and enhance immunodominance. These findings will enhance the understanding of the physiological basis of social hierarchy formation in male GFPs from a metabolomics perspective. Full article

Seabob shrimp Xiphopenaeus kroyeri is under heavy capture-pressure in the western Atlantic, requiring periods of fishing suspension to protect the propagation of the species in the wild. This work aims to describe the stages of gonadal development and the ovaries of X. kroyeri in trawling in the southeastern Atlantic Ocean of Brazil associated with climatic characteristics of temperature and precipitation. In total, 3658 specimens were captured in monthly collections from March 2019 to February 2020. The female gonads were classified macroscopically and microscopically according to the maturation stage and correlated with precipitation and temperature data. Five stages of maturation were observed: immature, initial maturation, advanced maturation, mature, and spawned. The highest percentage of mature females was found in May and July, and the average size of the female cephalothorax at the first gonadal maturation was 1.7 cm. The recruitment period was observed in April, with more juveniles. Precipitation showed a negative correlation with the number of mature females. April, May, and July are essential for the life cycle of the X. kroyeri population on the coast of Espírito Santo, Brazil. The results suggest that the current closed season for the species should be reconsidered. Full article

The age-based life history of two commercially important parrotfishes (Labridae: tribe Scarinae) and one goatfish (Mullidae) were characterized based on the commercial nearshore fishery in Saipan, Commonwealth of the Northern Mariana Islands. Age, growth, reproduction, and mortality were derived from fishery-dependent samples using sagittal otoliths and gonads for the stareye parrotfish Calotomus carolinus, pacific bullethead parrotfish Chlorurus spilurus, and yellowfin goatfish Mulloidichthys vanicolensis. All three species had short lifespans of 10 years or less, with a maximum age of 4 years for C. carolinus, 10 years for C. spilurus, and 7 years for M. vanicolensis. All three species had a fast initial growth to terminal body sizes, early maturation, and spawned throughout the year. The age-based demographic information presented here can be used to inform future stock assessments, fisheries management, and population models. Full article

Precocious puberty, defined as the onset of secondary sexual characteristics before age 8 in girls, presents a diagnostic challenge in distinguishing between normal variants and pathological conditions requiring intervention. Central precocious puberty (CPP) results from early activation of the hypothalamic–pituitary–gonadal axis, whereas peripheral precocious puberty (PPP) arises from excess sex steroid production independent of gonadotropins. Benign variants, including premature thelarche and premature adrenarche, require careful differentiation to prevent unnecessary treatment. This review explores the physiological mechanisms governing puberty, the epidemiological trends influencing its early onset, and the genetic and environmental factors contributing to its variability in female children. A structured diagnostic approach incorporating clinical evaluation, hormone assessments, imaging studies, and genetic insights is discussed. Management strategies vary depending on the etiology, with gonadotropin-releasing hormone analogs recommended for CPP and targeted therapies for PPP. In contrast, benign variants often necessitate observation and periodic follow-up. Given the increasing prevalence of early puberty, further research is essential to refine diagnostic thresholds and optimize treatment protocols. Early and accurate identification of precocious puberty ensures appropriate intervention, mitigating potential risks associated with early maturation, including compromised adult height and psychosocial challenges. Full article

Mini-puberty refers to the transient activation of the hypothalamic–pituitary–gonadal (HPG) axis during early infancy, lasting up to six months in boys and 12–24 months in girls. This phase represents the second activation of the HPG axis, following its initial activation during the second half of fetal life. At birth, the removal of the suppressive effect of placental estrogens on the HPG axis prompts a rise in both gonadotropins and sex steroid hormones, resulting in distinct clinical and laboratory markers of mini-puberty. While the clinical significance of mini-puberty remains partially understood, emerging evidence underscores its essential role in several aspects of human growth and development. In boys, testosterone influences penile growth, increases Sertoli cell numbers in the testes, and lays the foundation for future spermatogenesis. In girls, the increase in estradiol levels promotes follicular maturation and stimulates breast and uterine growth. Beyond the gonadal effects, mini-puberty appears to impact body composition, affecting body weight and promoting accelerated growth. Additionally, it may affect early psychosomatic and neural maturation, playing a role in several key aspects of the infantile brain. This narrative review examines recent findings on the physiology of the activation of the HPG axis before and after birth along with its significance in various aspects of human growth and development. In addition, mini-puberty-unique features in specific groups, such as preterm and small-for-gestational-age infants, are presented. Full article

The Atlanto-Mediterranean sea cucumber Holothuria tubulosa is a species of great ecological and commercial importance, making it a primary target for collection in the Mediterranean region. This study investigated the reproductive biology of H. tubulosa (Gmelin, 1793) in a coastal area of the Central Aegean Sea (Eastern Mediterranean) over a one-year period, from June 2021 to May 2022. Monthly sampling was conducted via dives at depths up to 10 m, alongside the recording of environmental and biometric data. Histological analysis revealed a synchronous annual reproductive cycle, with gonadal maturation beginning in April and peak sexual maturity observed in July and August, followed by a single spawning event from August to September. The sex ratio was 1:1.31 (male: female), and the size at first maturity was 255.3 mm. These findings provide essential insights into the reproductive physiology of H. tubulosa and further contribute to the development of sustainable stock management strategies for sea cucumbers in the Hellenic Seas. Full article

This study investigated the effects of dietary supplementation with the probiotic Pediococcus acidilactici on the reproductive performance and offspring viability of male Atlantic salmon (Salmo salar). A total of 48 mature males were divided into three groups—Group A (control, no probiotic), Group B (60-day supplementation), and Group C (120-day supplementation). The fish were kept in 10 m³ tanks at a constant temperature of 9 °C under a natural photoperiod and evaluated for multiple reproductive and physiological parameters. The results demonstrate that Group C exhibited significantly higher gonad weight, gonadosomatic index (GSI), and sperm concentration than Groups A and B. The blood biochemistry revealed reduced bilirubin and alanine aminotransferase (ALT) levels in Group C; however, values were within normal reference ranges for the species in all groups. While sperm quality parameters such as membrane integrity and motility showed no significant differences, fertility and embryo viability were significantly higher in Group C across all three developmental stages (180, 300, and 380 accumulated thermal units, ATUs). Additionally, Group C showed lower rates of embryonic malformation and mortality at later stages of development. Statistical analyses confirmed a significant interaction between treatment duration and embryo viability, with the 120-day probiotic treatment (Group C) producing the best outcomes. These findings support the hypothesis that P. acidilactici supplementation positively influences male reproductive parameters and improves embryo quality and survival in Atlantic salmon. Full article

Small pelagic fishes such as Sardinella aurita (Valenciennes, 1847) and Sardinella maderensis (R. T. Lowe, 1838) are key intermediate-level components of the marine food web of the southwestern African coast. Their biomass off Angola has shown significant interannual variability, and information about their reproduction is insufficient in the region for adequate stock management. Thus, we aimed to unveil the reproduction period and reproductive traits of these two Sardinella species and establish a link with the prevailing ocean temperature conditions. Adult fish samples were obtained monthly from artisanal and semi-industrial fleets, and the ichthyoplankton samples were collected with a Hydro-Bios Multinet off southwest Angola by Instituto Nacional de Investigação Pesqueira (Angola). The macroscopic inspection of gonads showed that females of both species were more abundant than males. The gonadosomatic index and maturity stages indicate that S. aurita spawns during the Austral summer (December through March), while S. maderensis has a longer spawning period, from October to April. The spawning peak occurs in February for S. aurita and S. maderensis. The mean monthly condition factor of both species was high before and after spawning seasons. The females of S. aurita reach sexual maturity at a smaller size than males, and 50% of the population reaches sexual maturity at a total length of 31.3 cm. The males of S. maderensis reach sexual maturity at a smaller size than females, and 50% of the population reaches sexual maturity at a total length of 28.4 cm. We also found that both species use the southern coast of Angola as a spawning area during the Austral summer and avoid the area during periods of intense upwelling. Currently, these species are managed as a single unit, and the minimum capture size is set at 22 cm, well below the size at sexual maturity registered in the study area. Therefore, we strongly recommend increasing the minimum capture size to guarantee long-term stock viability. Full article

Honey bees are one of the most significant pollinators and contribute to the pollination of various crops. The honey bee, Apis mellifera (Linnaeus, 1758), has unique characteristics that could be successfully used to improve biomonitoring approaches in assessing environmental interactions. Three apiaries with different rates of honey bee colony losses were included in the study—Dimovtsi, Plovdiv, and Krasnovo, Bulgaria. Male individuals (immature and mature) were collected from five colonies for each of the three apiaries and studied for histopathological changes in the gonads. The results concerning the rate of honey bee colony losses in the studied apiaries from 2022 and 2023 showed honey bee losses in the tested colonies due to queen problems, which were reported for Plovdiv, as well as the death of honey bees or a reduction in their number to a few hundred bees in the colony. The chemical analysis showed the presence of different organic substances, such as Coumaphos, DEET (N, N-diethyl-M-toluamide), Fluvalinate, and Piperonyl-butoxide, in the alive and dead honey bee samples and those of food stocks (wax, pollen, and honey) within the hives. Among the sample types, those of the dead honey bees contained the greatest variety of pesticide residues, particularly in Plovdiv and Dimovtsi, reinforcing the link between pesticide exposure and honey bee mortality. The histopathological alterations were mainly associated with the thinning of the covering epithelium of the seminiferous tubules and the detachment of the basement membrane of the seminiferous tubules. The more severe histopathological lesion, necrosis, was observed in a higher degree of expression in the drones from Plovdiv, indicating a higher pollution level in this region. Full article

Background/Objectives: The Pacific oyster Crassostrea gigas has emerged as a promising model system for sex determination studies due to its complex reproduction strategy and sex reversal. Transcription factors (TFs) play crucial roles in sex determination and gonadal differentiation. Despite previous research revealing functions of several conserved sex-determining pathway genes, such as Dmrt1, Foxl2, and SoxH, little is known about the other essential TF regulators driving C. gigas gonadal differentiation and development. Methods: In this study, a systematic identification of TFs revealed 1167 TF genes in the C. gigas genome. Comparative transcriptome analysis of C. gigas female and male gonads demonstrated 123 differentially expressed TF genes. Results: The majority of these sex-related TF genes were up-regulated in female or male gonads from the inactive stage to the mature stage. Moreover, this TF gene set was deeply conserved and showed similar regulation in the Kumamoto oyster Crassostrea sikamea gonads, suggesting their important regulatory roles in gonadal differentiation and development in Crassostrea oysters. Furthermore, two BTB TF gene clusters were identified in the C. gigas genome, both of which were specifically expressed in the male gonad. Gene numbers of each BTB gene cluster showed significant variations among six Crassostrea species. Conclusions: To the best of our knowledge, this study provides the first report of the whole TF family in C. gigas. The sex-related TF gene set will be a valuable resource for further research aimed at uncovering TF gene regulatory networks in oyster sex determination and gonadal differentiation. Full article

Insulin-like growth factors (IGFs) play crucial roles in the regulation of animal growth and reproduction. However, the functional and regulatory mechanisms underlying ovarian growth and oocyte maturation in teleosts remain unclear. In this study, the expression profiles of lncRNAs and mRNAs were analyzed in the ovaries of golden pompano (Trachinotus ovatus) treated with IGF1 and IGF2 proteins to gain insights into the role of these two IGF ligands in the regulation of ovarian development and maturation. A total of 1494 lncRNAs and 8728 mRNAs were differentially expressed following IGF1 treatment compared with the control group. A total of 101 lncRNAs and 377 mRNAs were differentially expressed after IGF2 treatment compared to those in the control group. The results revealed that KEGG pathways enriched by target genes of the DE lncRNAs overlapped significantly with those enriched by the DE mRNAs in both the IGF1 and IGF2 groups. The key overlapping enriched pathways included ECM receptor interaction, gap junction, Hedgehog signaling pathway, Ras signaling pathway, Rap1 signaling pathway, TGF beta signaling pathway, Wnt signaling pathway, GnRH signaling pathway, progesterone-mediated oocyte maturation, oocyte meiosis, cell cycle, and MAPK signaling pathway. The differentially expressed genes (DEGs) involved in ovarian development and oocyte maturation were cyp17a1, cyp19a1, star, hsd17b3, hsd17b7, adam23, slc26a6, htr2b, h2ax, nanos3, krt18, pgr, and inhbb, following IGF1 and IGF2 treatment. Furthermore, four lncRNAs (MSTRG.66521.1, MSTRG.49969.1, MSTRG.59923.1, and MSTRG.13767.1) for IGF1 and two (MSTRG.20896.2 and MSTRG.58123.2) for IGF2 within the lncRNA–mRNA network were found to target DEGs related to ovarian development and maturation. This suggests that IGFs may affect reproductive processes by regulating the expression of lncRNAs and mRNAs. RT-qPCR analysis revealed that these six lncRNAs showed high expression levels in the brain, pituitary, liver, and gonad tissues, indicating their potential involvement in regulating ovarian growth and development. This study elucidates the lncRNA–mRNA regulatory mechanism in response to IGF1 and IGF2 treatment during stage III of ovarian development in golden pompano, thereby deepening our understanding of its functional role. Full article