The molecular basis for the role of zinc in developmental biology

Abstract

Zine regulates the gene expression maehinery. It affects the structure of chromatin, the template function of its DNA, the activity of numerous transcription factors and ofRNA polymerases. Hence, it determines both the types of mRNA transcripts synthesized and the rate of transcription itself. Alterations in one or more of these zinc dependent processes have been proposed to account for the proliferative arrest and teratology induced by zinc deficiency. To examine this proposal, studies ofzine duringX laevis development have been initiated. The kinetics of X laevis ooeyte zinc uptake and storage and of zinc utilization during embryogenesis have been examined first. Vitellogenin carries zinc into the ooeyte. Ten % ofthe total zinc (10 ng/egg) remains within the cytosol while 90% (90 ng/egg) is stored in the yolk platelets associated with lipovitellin. The cytosolic pool is the souree of the zinc for all newly formed metalloproteins involved in embryo development. The yolk platelet zinc pool is stored for later use during early metamorphosis. It is now possible to exarnine zinc transfer to moleeules, such as e.g. transcription factors, and the role of the metal in their function in development and organogenesis. (Mol Cell Biochem 188: [41][42][43][44][45][46][47][48]1998)

Endocrine disruptor & nutritional effects of heavy metals in ovarian hyperstimulation

“…High levels of selenium are found in brazil nuts, kidney, seafood and cereals, although this is soil dependent and it has been reported that European intake of selenium is falling [31]. Zinc acts as a co-factor for enzymes promoting DNA transcription and protein synthesis [32], has a role in expression of steroid hormone receptors [33] and has anti-apoptotic [34] and anti-oxidant properties [35]. Studies have demonstrated that a zinc deficiency can lead to subfertility and abnormal reproductive outcomes [36], and to pregnancy complications [37,38].…”

Dietary zinc-deficiency and its recovery responses in rat liver cytosolic alcohol dehydrogenase activities

“…The potential importance of zinc to the gene can be appreciated from the fact that a great percentage of the zinc content of rat liver is found in the nucleus and a sigin vitro (Cousins, 1998). Zinc is also involved in the processes of genetic stability and gene expression in a variety of ways including the structure of chromatin, the replication of DNA and transcription of RNA through the activity of transcription factors and RNA and DNA polymerases, as well as playing a role of DNA repair and programmed cell death (Falchuk, 1998). Further, zinc is known to regulate both enzyme activity and the stability of the proteins as an activator or as an inhibitor ion (Brandt et al, 2009;Kawashima et al, 2006).…”

Cloning and Expression of a Seed-Specific Metallothionein-Like Protein from Sesame

“…24) Being an essential trace element, the zinc ion is required as a co-factor for many biological activities involved in cellular metabolism and gene regulation. 27) Plant Ec genes are conspicuously expressed during embryogenesis, analogous to mammalian MT genes. The hepatic concentration of MTs, primarily zinc MT, is 20-fold greater in neonatal than in adult rats.…”