Fish reproduction

The organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) is an endocrine-disrupting compound (EDC) that has been banned by most countries for decades. However, it continues to be detected in nearly all humans and wildlife due to its biological and environmental persistence. The ovarian dysgenesis syndrome hypothesis speculates that exposure to EDCs during sensitive developmental windows such as early gonadal differentiation lead to reproductive disorders later in life. Yet, mechanisms by which DDT affects developing gonads remain unclear due to the inherent challenge of getting developmental exposure data from adults presenting with reproductive disease...

Effective wild cat conservation programs with assisted reproductive technologies are being developed in different parts of the world. The flat-headed cat, fishing cat, and Asiatic golden cat are three species among nine wild Felidae in Thailand that are in need of urgent conservation efforts. Here, we assessed routine sperm characteristics and we report the detection of protein biomarkers related to the fertilization process, IZUMO1 and the CRISP family, and apoptotic markers, active or cleaved caspase-3, in semen samples collected from these wild cats...

Elasmobranch species show low resilience in relation to anthropogenic stressors such as fishing efforts, loss of habitats, and climate change. In this sense, the elasmobranch populations appear to be at risk of extinction in many cases. Despite conservation researchers making efforts to implement knowledge, the information on the biology, reproduction, distribution, or genetic structure of some species is still scattered, often caused by the occurrence of species in inaccessible habitats. Echinorhinus brucus is a deep benthic shark evaluated as "Endangered" on which little information is available, particularly about its geographical range and genetic structure, while E...

Low temperature stress has adverse effects on fish growth and reproduction, causing huge economic losses to the aquaculture industry. Especially, black porgy (Acanthopagrus schlegelii) farming industry in north of Yangtze River has been severely affected by low temperature for a long time. To explore the tolerance mechanism of black porgy to low temperature stress, the experiment was designed. The liver and gill tissues of black porgy were taken from the water temperature point of 15 °C (control group named as CG), 3...

BACKGROUND: In fisheries, hypoxia stress is one of the most common environmental stresses that often lead to the death of large numbers of fish and cause significant economic losses. The pituitary, an important endocrine gland, lies below the hypothalamus region of the brain. It plays a crucial part in controlling vital physiological functions in fish, such as growth, reproduction, and responses to stress. However, the detailed mechanisms of how hypoxia affects these physiological processes via the pituitary remain largely unknown...

Groupers (Epinephelidae and Serranidae) have attracted special attention to fish farming, and their species offer good opportunities for successful hybridizations. Cytogenetic data allow a better understanding of the role of karyotypic diversification in the acquisition of post-zygotic reproductive isolation (RI). Thus, chromosomal analyses were performed on E. striatus (Caribbean Sea), E. coioides and E. tauvina (Indo-Pacific Region), using standard procedures and mapping of six repetitive DNA classes by the in situ hybridization...

The cellular and molecular mechanisms governing sexual reproduction are conserved across eukaryotes. Nevertheless, hybridization can disrupt these mechanisms, leading to asexual reproduction, often accompanied by polyploidy. In this study, we investigate how ploidy level and ratio of parental genomes in hybrids affect their reproductive mode. We analyze the gametogenesis of sexual species and their diploid and triploid hybrids from the freshwater fish family Cobitidae, using newly developed cytogenetic markers...

The high dynamism of repetitive DNAs is a major driver of chromosome evolution. In particular, the accumulation of repetitive DNA sequences has been reported as part of the differentiation of sex-specific chromosomes. In turn, the fish species of the genus Megaleporinus are a monophyletic clade in which the presence of differentiated ZZ/ZW sex chromosomes represents a synapomorphic condition, thus serving as a suitable model to evaluate the dynamic evolution of repetitive DNA classes. Therefore, transposable elements (TEs) and in tandem repeats were isolated and located on chromosomes of Megaleporinus obtusidens and M...

Sexual dimorphism allows species to meet their fitness optima based on the physiological availability of each sex. Although intralocus sexual conflict appears to be a genetic constraint for the evolution of sex-specific traits, sex-linked genes and the regulation of sex steroid hormones contribute to resolving this conflict by allowing sex-specific developments. Androgens and their receptor, androgen receptor (Ar), regulate male-biased phenotypes. In teleost fish, ar ohnologs have emerged as a result of teleost-specific whole genome duplication (TSGD)...

Theory describing evolution of offspring size often assumes that the production cost per unit volume is the same for small and large offspring. However, this may not be true if indirect costs of reproduction (e.g., material and energetic costs of supporting offspring development) scale disproportionately with offspring size. Here we show how direct and indirect costs of reproduction can be explicitly modeled within the Smith-Fretwell framework and how observations of size-number relationships can thus be used to evaluate indirect costs...

OBJECTIVE: A Mediterranean dietary pattern, sleeping habits, physical activity, and lifestyle appear to affect reproductive health. There are few reports about whether fertility-specific quality of life (QOL) is linked to infertility treatment outcomes. The aim of this study is to investigate when lifestyle factors and fertility-specific QOL are comprehensively considered, which factors influence assisted reproductive technology (ART) outcomes. METHODS: This prospective cohort includes 291 women undergoing a first ART treatment at multiple centers in Japan and was designed to evaluate the influence of diet, physical activity, sleeping pattern, computer use duration, and fertility-specific quality of life tool (FertiQoL) score on ART treatment outcomes using a questionnaire...

Conflicting results remain on the impacts of climate change on marine organisms, hindering our capacity to predict the future state of marine ecosystems. To account for species-specific responses and for the ambiguous relation of most metrics to fitness, we develop a meta-analytical approach based on the deviation of responses from reference values (absolute change) to complement meta-analyses of directional (relative) changes in responses. Using this approach, we evaluate responses of fish and invertebrates to warming and acidification...

Gestodene (GES) is widely used in human therapy and animal husbandry and is frequently detected in aquatic environments. Although GES adversely affects aquatic organisms at trace levels, its effects on the reproductive biology of fish remain inconclusive. In this study, female zebrafish (Danio rerio) were exposed to environmentally relevant levels of GES for the evaluation of the effects of GES on the reproductive system by using endpoints including gene expression, plasma steroid concentrations, histological and morphological analyses, copulatory behavior, and reproductive output...

This study aimed to understand the reproductive biology and migrative behavior of the largehead hairtail Trichiurus lepturus in a tropical area, specifically off Pernambuco coast, northeastern Brazil. Commercial catches from fish corrals provided samples for analysis, including measurements, weight recording, and examination of gonads to determine its maturation stage. Reproductive analyses were performed, such as sex ratio, gonado-somatic index, and sizes at first maturity. There was a slightly higher proportion of females among the 141 largehead hairtail specimens analysed...

Fish bioacoustics, or the study of fish hearing, sound production, and acoustic communication, was discussed as early as Aristotle. However, questions about how fishes hear were not really addressed until the early 20th century. Work on fish bioacoustics grew after World War II and considerably in the 21st century since investigators, regulators, and others realized that anthropogenic (human-generated sounds), which had primarily been of interest to workers on marine mammals, was likely to have a major impact on fishes (as well as on aquatic invertebrates)...

Live foods such as phytoplankton and zooplankton are essential food sources in aquaculture. Due to their small size, they are suitable for newly hatched larvae. Artemia and rotifer are commonly used live feeds in aquaculture; each feed has a limited dietary value, which is unsuitable for all cultured species. Whereas, copepod and cladocerans species exhibit favorable characteristics that make them viable candidates as sources of essential nutrients for hatchery operations. Due to their jerking movements, it stimulates the feeding response of fish larvae, and their various sizes make them suitable for any fish and crustacean...

The reproductive diversity of extant cartilaginous fishes (class Chondrichthyes) is extraordinarily broad, reflecting more than 400 million years of evolutionary history. Among their many notable reproductive specialisations are viviparity (live-bearing reproduction) and matrotrophy (maternal provision of nutrients during gestation). However, attempts to understand the evolution of these traits have yielded highly discrepant conclusions. Here, we compile and analyse the current knowledge on the evolution of reproductive diversity in Chondrichthyes with particular foci on the frequency, phylogenetic distribution, and directionality of evolutionary changes in their modes of reproduction...

Climate change has myriad impacts on ecosystems, but the mechanisms by which it affects individual species can be difficult to pinpoint. One strategy to discover such mechanisms is to identify a specific ecological factor related to survival or reproduction and determine how that factor is affected by climate. Here we used Landsat imagery to calculate water clarity for 127 lakes in northern Wisconsin from 1995 to 2021 and thus investigate the effect of clarity on the body condition of an aquatic visual predator, the common loon (Gavia immer)...

In seasonally breeding mammals and birds, the production of the hormones that regulate reproduction (gonadotropins) is controlled by a complex pituitary-brain-pituitary pathway. Indeed, the pituitary thyroid-stimulating hormone (TSH) regulates gonadotropin expression in pituitary gonadotropes, via dio2-expressing tanycytes, hypothalamic Kisspeptin, RFamide-related peptide, and gonadotropin-releasing hormone neurons. However, in fish, how seasonal environmental signals influence gonadotropins remains unclear...

Epigenetics plays a vital role in the interaction between living organisms and their environment by regulating biological functions and phenotypic plasticity. Considering that most aquaculture activities take place in open or natural habitats that are vulnerable to environmental changes. Promising findings from recent research conducted on various aquaculture species have provided preliminary evidence suggesting a link between epigenetic mechanisms and economically valuable characteristics. Environmental stressors, including climate changes (thermal stress, hypoxia, and water salinity), anthropogenic impacts such as (pesticides, crude oil pollution, nutritional impacts, and heavy metal) and abiotic factors (infectious diseases), can directly trigger epigenetic modifications in fish...