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Vitellogenin provides the major egg yolk protein that is a source of nutrients during early development of egg-laying vertebrates and invertebrates.Although vitellogenin also carries some lipid for deposition in the yolk, the primary mechanism for deposition of yolk lipid is instead via VLDLs, at least in birds and reptiles. [4]
When estrogen production in the ovary is increased via the activation of the hypothalmo-pituitary axis it leads to heightened vitellogenin production in the liver. [3] Vitellogenin production in the liver is the first step of vitellogenesis. Once Vitellogenins are released into the blood stream where they are then transported to the growing ...
Vitellogenin is released by the maturing female and sequestered by developing oocytes to produce the egg yolk. [25] Males do not normally produce vitellogenin, but when exposed to nonylphenol they produce similar levels of vitellogenin to females. [25] The concentration needed to induce vitellogenin production in fish is 10 ug/L for NP in water ...
The yolk of a chicken egg Diagram of a fish egg; the yolk is the area which is marked 'C'. Among animals which produce eggs, the yolk (/ ˈ j oʊ k /; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo.
In anautogenous mosquitoes, yolk production genes are strongly activated after a blood meal through a process involving the target of rapamycin signal pathway. [9] In particular, certain amino acids found in the blood proteins seem to be necessary for the activation of the vitellogenin gene. [10]
[16] [17] The presence of vitellogenin genes (a protein necessary for egg yolk formation) is shared with birds; the presence of this symplesiomorphy suggests that the common ancestor of monotremes, marsupials, and placentals was oviparous, and that this trait was retained in monotremes but lost in all other extant mammal groups.
Synthetic hormones are endocrine disruptors. Thus, estrogenic compounds like ethinylestradiol (estrogen hormone) at concentrations < 1 ng per litre may cause both vitellogenin production (a frequently used index for feminization of male fish), and structural change in their sex organs.
Vitellogenin (VG), an egg yolk precursor protein, is dependent on juvenile hormone levels. Mated females exhibit higher levels of VG than virgin females 48 hours after emergence; mated females also exhibit significantly higher egg production rates than virgin females at 48–120 hours post emergence. [15]