Fish Ovaries And Fully Grown Follicles

Methods for Gene Expression Profiling A number of methods are currently used for gene expression profiling. They differ in scale, economy, and sensitivity. The delineation of the transcriptome of teleost fish ovaries has been evaluated using large-scale expressed sequence tags (ESTs) sequencing (Boguski et al., 1993) of cDNA libraries of zebrafish (Zeng and Gong, 2002 Li et al., 2004) and Atlantic salmon (Davey et al., 2001 Rise et al., 2004), subtractive hybridization of cDNA libraries...

VTG Gene Clusters and Their Expression in Fish

Vtg genes and their expression sites The presence of multiple Vtg genes (vtgs) has been demonstrated in the genome of some teleost fish species (Buisine et al., 2002 Wang et al., 2005). Comparative genomics analyses suggested two whole genome duplication events occurring, one before and the other after the divergence of ray-finned and lobe-finned fishes, prior to teleost radiation (Amores et al., 1998 Postlethwait et al., 1998 Jaillon et al., 2004 Brunet et al., 2006). The additional...

Endocrine Disruption Of Nongenomic Steroid Actions

Teleost gametes and gonads have proven to be excellent models for examining the potential of environmental estrogens (xenoestrogens) and other contaminants to interfere with nontraditional steroid actions (Thomas, 2000a). The first clear evidence for chemical interference with this mechanism was obtained with Atlantic croaker oocytes, which failed to undergo oocyte maturation in response to 20P-S in an in vitro assay in the presence of several xenoestrogens (Ghosh and Thomas, 1995)....

Endocrine And Paracrine Regulation

OF SYNCHRONIZED FOLLICULAR DEVELOPMENT GnRH AS A CENTRAL PLAYER IN FOLLICULAR DEVELOPMENT In each reproductive cycle, a large number of oocytes develop as a group and undergo synchronous maturation and ovulation either as a whole or in several batches depending on the species. Environmental cues including temperature, photoperiod, lunar cycle, or the amount of rainfall are perceived and conveyed as endogenous stimuli to regulate endocrine system to synchronize growth and reproduction. Early...

Preface

Fish and their prolific nature serve as symbols in diverse human cultures, religions, and societies. Fish eggs not only serve as food, with caviar as one of the most famous luxuries on our menus, but they also form the basis for aquaculture that produces fish as a plentiful food source. Obtaining good-quality eggs is crucial and essential for successful production of fish in captivity. Aquaculture production already accounted for almost 22 of fish produced worldwide in 2002 (http www.fao.com),...

Conclusions And Prospects

During the last two decades, the availability of molecular cloning techniques has helped establish the dual nature of the gonadotropic action also in fish. Yet, due to the variety of reproductive strategies found among fishes, the specific functions of the GtHs in general, and in particular those of the newly discovered member, the FSH, are still ambiguous. In salmonids (synchronous spawners), which represent a relatively simple reproductive model, the FSH is predominant during early oogenesis...

The Supergene Family of LDL Receptor Relatives LRs

The LDLR family comprises a large and growing number of genes, whose products contain a characteristic set of structural domains. As stated above, attempts to delineate the evolutionary history of this gene family must take into consideration newly discovered functions, including binding a still expanding list of ligands by the extracellular domains, ligand uptake through clathrin-mediated mechanisms, and signal transduction via the cytoplasmic regions of the receptors. As will become apparent...

Info

Have been used as sentinels for the presence of estrogenic substances in water. The induction of Vtg is predominantly used as a biomarker, although recently the use of ZP proteins has been suggested as an alternative indicator for estro-genic endocrine-disrupting substances (Arukwe et al., 1997, 2001, 2002 Celius and Walther, 1998 Celius et al., 1999 Oppen-Berntsen et al., 1999). Studies have shown that the expression of ZPs precedes that of Vtg, thus implicating a higher sensitivity for...

Regulation Of Zp Expression

The regulation of ZP genes varies among different vertebrates, probably reflecting the differences in oogenesis, fertilization mechanisms, and embryonic development between species. The formation of fertilizable oocyte is a process requiring coordination between several different factors and cell types. Mammals and fish display differences in the transcriptional and translational regulation of eggshell components. Furthermore the sites of synthesis of eggshell components vary from species to...

Oocyte Development And Molecular Staging By Proteomics

Until recently, oocyte development was mostly followed by visual inspection of the different stages of the oocytes, either under a microscope (Selman et al., 1993 Maack and Segner, 2003), or by following the activity of enzymes involving with the maturation process with their corresponding maturation stages. Oocyte growth and development are accompanied by changes in the opacity of the oocyte, as well as changes in color, size, and density. These changes are mostly attributed to the...

Production And Accumulation Of Maternal Products During Oogenesis

Oogenesis Teleosts

Oogenesis and the Animal-Vegetal Pattern of Polarity Most maternal products appear to be produced endogenously by the oocyte during its development see Chapters 1-3 , although some products are taken up by the oocyte from the surrounding tissue see Chapters 1 and 2 . Oocyte growth is massive, as the oocyte increases a few hundred fold in volume, and shows increases in RNA and protein content of several orders of magnitude Chaudhuri and Mandal, 1980 Selman et al., 1993 . At the same time,...