نتایج جستجو برای: fish reproduction
تعداد نتایج: 168650 فیلتر نتایج به سال:
We examined the relationship between the pelagic environment and the lunar timing of reproduction and recruitment of a coral reef fish by comparing patterns exhibited by fish under normal oceanographic conditions with patterns exhibited by fish that experienced significantly different pelagic conditions (i.e. encounter with meso-scale, low-salinity North Brazil Current [NBC] rings passing by th...
A 280-d study examined the effects of 17β-estradiol (E2) on reproduction and development of the sheepshead minnow (Cyprinodon variegatus) exposed from the parental (F0) through three subsequent (F1, F2, and F3) generations and evaluated the need for multigenerational assessments of the risks of endocrine-disrupting chemicals. This first three-generation study exposed adult F0 and F1 fish to mea...
Calcitonin (CT) is a calcium regulating hormone produced mainly by the parafollicular C cells of the thyroid gland in mammals. In lower vertebrates, these cells are concentrated primarily in a specialized gland, the ultimobranchial gland. The common structure of CT is 32-amino acid residues with a seven-residue cyclic loop formed by disulfide bond between cysteines at position 1 and 7 and proli...
Triazines are an important group of herbicides, which have been used extensively or selectively both in agricultural and non-agricultural areas worldwide for more than fifty years to control broadleaf and some grassy weeds. As a consequence of their massive application, they have become and remain significant environmental pollutants, especially in aquatic ecosystems. Fish are an integral part ...
The production and trade of ornamental fish is one of the most profitable sectors of aquaculture and is growing and developing in Asia and around the world. Tiger barb is an interesting fish that has long been in Iranian aquariums and has attracted the attention of enthusiasts. The barbs are a subfamily (Cyprinidae) of freshwater fishes native to Southeast Asia. The natural geographical range o...
objective: although key roles for dietary vitamin e (vite) and fatty acid (fa) in fertility have been confirmed, limited data are available on the effects of vite alone, or a constant level of vite supplemented by dietary omega-6 and omega-3 fas in combination on male reproduction. consequently in this paper, the effects of vite, sunflower oil, fish oil and their combination on rat sperm were i...
The purposes of this review are to assess the human exposure and human and experimental evidence for adverse effects of brominated flame-retardants (BFRs) with specific focus on intake from seafood. The leakage of BFRs from consumer products leads to exposure of humans from fetal life to adulthood. Fish and fish products contain the highest levels of BFRs and dominate the dietary intake of freq...
1. Introduction A small-sized grass carp (43 cm long) was caught in Lake Whangape, lower Waikato River basin, in May 1997. This fish was too small to be a recapture from the escapement from trial sites in 1984 (fish which are now mostly longer than 70 cm), so could have been either a recent escapee, or the result of natural reproduction in the river. Either way, the finding of this fish indicat...
Gonadotropin releasing hormone (GnRH) is a neuropeptide known to regulate reproduction in vertebrates. Different analogues of synthetic GnRH are used to induce final sexual maturation in fish breeders. The purpose of this research was to evaluate the expression of recombinant GnRH (rGnRH) in Escherichia coli BL21 to produce recombinant hormone. In the present research, the sequence of DNA relat...
Reproduction in most fish is seasonal or periodic, and the spawning occurs in an appropriate season to ensure maximum survival of the offspring. The sequence of reproductive events in an annual cycle is largely under the control of a species-specific endogenous timing system, which essentially relies on a well-equipped physiological response mechanism to changing environmental cues. The duratio...
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