Sexual Plasticity And Gametogenesis In Fishes

Sex determination, differentiation and gamete maturation are well organized molecular events in vertebrates. In vertebrates, sex determination and differentiation are two important events in the development of gonads (testis or ovary). Sex determination is the genetic (sex chromosomes) or environmental process by which the sex (male or female) of an individual is established. During embryonic development, primordial germ cells migrate from the site of origin to the gonadal primordia where they differentiate along with somatic cells and finally form the indifferent/bipotential gonads. Depending on the action of various factors the bipotential gonads give rise to either testis or ovaries. In most vertebrates, excluding fishes and some amphibians, the event of sex determination is controlled genetically and later the progression of gonadal development is controlled by hormones and other factors. Interestingly, these processes in fishes are controlled not only genetically but also through hormones or environmental factors. These characteristics make fish the champions of sex reversal and serve as excellent animal models to precisely understand sexual development. The next interesting aspect is meiotic maturation which is essentially mediated by gonadotropins and progesterone metabolites to trigger final gamete maturation in fishes which is different from mammals. The novel aspects pertaining to gamete maturation has been studied in great detail in fish which depicts precise regulatory events of gamete maturation.

Sex determination, differentiation and gamete maturation are well organised molecular events in vertebrates. In vertebrates, sex determination and differentiation are two important events in the development of gonads (testis or ovary). Sex determination is the genetic (sex chromosomes) or environmental process by which the sex (male or female) of an individual is established. During embryonic development, primordial germ cells migrate from the site of origin to the gonadal primordia where they differentiate along with somatic cells and finally form the indifferent/bipotential gonads. Depending on the action of various factors the bipotential gonads give rise to either testis or ovaries. In most vertebrates, excluding fishes and some amphibians, the event of sex determination is controlled genetically and later the progression of gonadal development is controlled by hormones and other factors. Interestingly, these processes in fishes are controlled not only genetically but also through hormones or environmental factors. These characteristics make fish the champions of sex reversal and serve as excellent animal models to precisely understand sexual development. The next interesting aspect is meiotic maturation which is essentially mediated by gonadotropins and progesterone metabolites to trigger final gamete maturation in fishes which is different from mammals. The novel aspects pertaining to gamete maturation has been studied in great detail in fish which depicts precise regulatory events of gamete maturation.

The unprecedented level of diversity recorded among the clones of self-fertilizing gynogenetic unisexuals and self-fertilizing simultaneous hermaphrodites challenges current ideas on the predominant role of recombination in promoting evolution of biological diversity. Though limited to a few species, the existence of self-fertilizing and cyclical sex changing hermaphrodites remians a puzzle to many geneticists and endocrinologists. Within a few days after the removal of a harem master or mistress, a successor changes sex and takes over the harem; the causes for the sex changing mechanism pose many challenges to socio-ecologists and behaviour specialists.This book is a synthesis of relevant and recent information on sexuality of fishes and points towards new directions of desired research.

Aquaculture Pharmacology is a reliable, up-to-date, "all inclusive" reference and guide that provides an understanding of practical drug information for the aquaculture industry. This book covers the sources, chemical properties, and mechanisms of action of drugs, and the biological systems upon which they act. It covers various drug interactions, therapeutic uses of drugs, as well as legal considerations within the industry as a whole. It presents the four main groups of drugs used in fish, crustaceans and molluscs and includes disinfectants, antimicrobial drugs, antiparasitic agents, and anesthetics, and identifies areas where more research is needed to generate more knowledge to support a sustainable aquaculture industry. With the burgeoning international aquaculture expansion and expanding global trade in live aquatic animals and their products this book is useful to bacteriologists, mycologists, aquaculturists, clinical practitioners in aquatic animal health and all those in industry, government or academia who are interested in aquaculture, fisheries and comparative biology. Presents clinical information for the three major aquatic food animals (fish, crustaceans and molluscs) Facilitates research to develop vaccines or other similar pathogen mitigation measures Provides the latest advancements in the field including regulated pharmaceuticals for use in fisheries and aquaculture

Awarded Bookauthority's "Best Aquaculture Books of all Time" A comprehensive resource that covers all the aspects of sex control in aquaculture written by internationally-acclaimed scientists Comprehensive in scope, Sex Control in Aquaculture first explains the concepts and rationale for sex control in aquaculture, which serves different purposes. The most important are: to produce monosex stocks to rear only the fastest-growing sex in some species, to prevent precocious or uncontrolled reproduction in other species and to aid in broodstock management. The application of sex ratio manipulation for population control and invasive species management is also included. Next, this book provides detailed and updated information on the underlying genetic, epigenetic, endocrine and environmental mechanisms responsible for the establishment of the sexes, and explains chromosome set manipulation techniques, hybridization and the latest gene knockout approaches. Furthermore, the book offers detailed protocols and key summarizing information on how sex control is practiced worldwide in 35 major aquaculture species or groups, including fish and crustaceans, and puts the focus on its application in the aquaculture industry. With contributions from an international panel of leading scientists, Sex Control in Aquaculture will appeal to a large audience: aquaculture/fisheries professionals and students, scientists or biologists working with basic aspects of fish/shrimp biology, growth and reproductive endocrinology, genetics, molecular biology, evolutionary biology, and R&D managers and administrators. This text explores sex control technologies and monosex production of commercially-farmed fish and crustacean species that are highly in demand for aquaculture, to improve feed utilization efficiency, reduce energy consumption for reproduction and eliminate a series of problems caused by mixed sex rearing. Thus, this book: Contains contributions from an international panel of leading scientists and professionals in the field Provides comprehensive coverage of both established and new technologies to control sex ratios that are becoming more necessary to increase productivity in aquaculture Includes detailed coverage of the most effective sex control techniques used in the world's most important commercially-farmed species Sex Control in Aquaculture is the comprehensive resource for understanding the biological rationale, scientific principles and real-world practices in this exciting and expanding field.

Of all vertebrates, fish exhibit unparalleled diversity of sexual plasticity and flexibility, ranging from gonochorism to unisexualism, and exceptional patterns of functional hermaphroditism. Fish farming and monosex aquaculture have led to reproductive dysfunction with males producing less milt, and females failing to ovulate and spawn. This book brings together relevant information on the role of the endocrine system on sexual differentiation in fish, and bridges the gap between molecular endocrinologists and fishery scientists.

Biology and Physiology of Freshwater Neotropical Fish is the all-inclusive guide to fish species prevalent in the neotropical realm. It provides the most updated systematics, classification, anatomical, behavioral, genetic, and functioning systems information on freshwater neotropical fish species. This book begins by analyzing the differences in phylogeny, anatomy, and behaviour of neotropical fish. Systems such as cardiovascular, respiratory, renal, digestive, reproductive, muscular, and endocrine are described in detail. This book also looks at the effects of stress on fish immune systems, and how color and pigmentation play into physiology and species differentiation. Biology and Physiology of Freshwater Neotropical Fish is a must-have for fish biologists and zoologists. Students in zoology, ichthyology, and fish farming will also find this book useful for its coverage of some of the world’s rarest and least-known fish species. Features chapters written by top neotropical fish researchers and specialists Discusses environmental effects on neotropical fishes, including climate change and pollution Details the phylogenetic occurrence of electroreceptors and electric organs in fish

This book is dedicated to present different aspects of reproductive physiology and molecular endocrinology of commercially important as well as potential aquaculture fish species. The existing aquaculture generation is looking for species diversification for efficient utilization of available diverse water resources. The knowledge of reproductive physiology of fish will help in development of breeding strategy for use in commercial aquaculture. Reproductive system is highly coordinated and governed by means of complex network of nervous, endocrine system and environmental factor as well. This book emphasize on different key aspects of reproductive endocrine system such as basic gonadal biology in the events of climate vulnerability, sex determination, sex reversal, stimulatory hormones, inhibitory hormones and receptors, environmental and chemical factor guiding reproduction, puberty, neuroendocrine regulation of reproduction etc. This book further describes how reproduction is not just indispensable for the existence or survival of an individual, but it is important for the survival of species. Chapters also address the concerns of anthropogenic activities on fish and the aquatic environment lead main trouble on physiological and reproductive processes of aquatic animals. This book offers an attractive compilation of highly relevant aspects of current and future of aquaculture, especially in view of the growing awareness of aquaculture, to food scientists working on commercial fish, animal biologists, fish geneticists etc. This book is very timely, and relevant to the sustainable development goals. The contents would be relevant to policy makers, working towards blue revolution and blue economy.