Fetus Protein synthesis

Retinoids increase cellular mitotic activity, DNA and RNA synthesis, and protein synthesis. The primary toxicity of concern is female-mediated teratogenesis. Isotretinoin alters cell differentiation and placement in developing fetuses that are exposed to it in the first... 

This section has reviewed the effects of a tryptophan-deficient diet or of tryptophan administration or supplementation on pregnancy, on the fetus, and on postnatal animals or humans. It is apparent that tryptophan does play a role in the fetal state and postnatally. Its effects are probably through the levels of blood free tryptophan levels in the mother, the fetus, and the infant. The blood free tryptophan levels influence the brain tryptophan levels and also the brain serotonin levels. Thus, blood tryptophan levels can influence protein synthesis in various tissues, especially in the brain, along with serotonin synthesis, in the fetus and in the infant. Other amino acids can also affect protein synthesis, but tryptophan is unique in its effect on serotonin levels. 

In the mammalian egg, the synthesis of RNA starts shortly after fertilization. There is also a rapid increase in protein synthesis after fertilization, and the evidence reviewed suggests that this is probably the result of both the initiation of new mRNA synthesis as well as the activation of masked maternal mRNA in the cytoplasm or the assemblage of active ribosomes. The first morphological differentiation which may be observed is a distinction between the inner cell mass and the trophoblast cells which, in the normal mouse embryo, occurs at the late blastocyst stage at a time when the embryo contains between 30 and 60 cells. The outer trophoblast develops into the placenta and extraembryonic membranes, while the inner cell mass continues to differentiate to give rise to the fetus. 

Ability of Mouse Blastocysts to Form Viable Fetuses after in vitro Cultivation (2-4 Cell Stage Blastocyst) in the Presence of Inhibitors op Mitochondrial Nucleic Acid or Protein Synthesis"... 

Protein— Most of the growth of the fetus takes place in the latter half of pregnancy, when the rate of protein synthesis is high, as indicated by Fig. P-67. 

The essentiality of cysteine for the fetus and newborn may underlie their low or nonexistent ability to convert cysteine to taurine, another low molecular weight sulfur containing confound apparently required in large amounts by developing brain (Sturman et al., 1978). The supply of cysteine may all be required for protein synthesis and none spared for taurine formation. Cystelnesulflnic acid decarboxylase (EC 4.1.1.12), the enzyme chiefly responsible for taurine biosynthesis in mammals, develops slowly after birth and reaches maximum activity in mature brain (Agrawal et al.,1971 Pasantes-Morales et al.,1976 Rassin et al., 1979), although the concentration of taurine decreases over this same period (Fig. 4). Cystelnesulflnic acid decarboxylase also uses pyridoxal 5 -phosphate as coenzyme, and is extremely sensitive to a dietary deficiency of vitamin Bg (Hope, 1955 Rassin and Sturman, 1975). 

The mechanism of action of insulin and its role in protein synthesis is not well understood. It appears that, on a physiologic level, insulin functions as a growth hormone in the human fetus (Villee, 1975) but... 

Microorganisms sometimes control the synthesis of surface proteins using segments of invertible DNA. The pathogenic bacterium Campylobacter fetus utilizes DNA rearrangements to allow one of a large family of surface layer (S-layer) proteins to be formed.597 The yeast FLP recombinase, mentioned in the preceding section, also inverts the sequence flanked by the 599-bp repeats.589... 

An adequate dietary supply of zinc is essential for normal growth. The role of zinc in the synthesis of proteins makes the need for the metal especially pronounced for fetuses and newborn infants. For an adult, a daily intake of 11 mg zinc is recommended, corresponding to 0.15 mg per kilogram body weight. The recommendation for newborns is 6 mg per day, i.e. 1.5 mg zinc per kg body weight. In relation to body weight, the recommended zinc intake is thus 10 times greater for infants than for adults. 

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