Developmental differences distribution

Boklage CE (1987d) Developmental differences between singletons and twins in distributions of dental diameter asymmetries. Am J Phys Anthro 74(3) 319-332. Boklage CE (1990) The survival probability of human conceptions from fertilization to term. Int J Fertil 35 75-94... 

The information available on UV-susceptibility of different developmental stages in kelps indicate the unicellular zoospores as being most sensitive (Wiencke et al. 2000, 2004). However, zoospore UV-sensitivity varies species-specifically as a function of depth distribution of the sporophyte, i.e. kelps from shallow water are more tolerant than plants from deeper vertical positions. Consequently, any increase in UVB-induced spore mortality will result in impaired reproductive success and finally reduce fitness of the population. In addition, elevated UVB will penetrate deeper into the water column, which may result in a shift of the upper distribution limit of seaweed communities to deeper waters (Wiencke et al. 2006). 

Hoyer K, Karsten U, Sawall T, Wiencke C (2001) Photoprotective substances in Antarctic macroalgae and their variation with respect to depth distribution, different tissues and developmental stages. MarEcol Prog Ser211 117-129... 

There is no information regarding the metabolism of 3,3 -dichlorobenzidine in children. However, N-acetylation (as discussed above) in humans is likely done by one of two families of N-acetyltransferases. One of these families, NAT2, is developmentally regulated (Leeder and Kearns 1997). Some enzyme activity can be detected in the fetus by the end of the first trimester. Almost all infants exhibit the slow acetylator phenotype between birth and 2 months of age. The adult phenotype distribution is reached by the age of 4-6 months, whereas adult activity is found by approximately 1-3 years of age. Also, UDP-glucuronosyltransferase, responsible for the formation of glucuronide conjugates, seems to achieve adult activity by 6-18 months of age (Leeder and Kearns 1997). These data suggest that metabolism of 3,3 -dichlorobenzidine by infants will differ from that in adults in extent, rate, or both. 

Like other steroids, testosterone acts intracellularly in target cells. In skin, prostate, seminal vesicles, and epididymis, it is converted to 5k -dihydrotestosterone by 5K-reductase. In these tissues, dihydrotestosterone is the dominant androgen. The distribution of this enzyme in the fetus is different and has important developmental implications. 

Hormone-treated pea seedlings generate two physically distinct cellulases (EC 3.2.1.4), with similar substrate specificities, Km values, and inhibitor sensitivities. They may be effectively separated by sequential extraction with buffer and salt and they appear to possess identical active sites but different apoprotein structures. The question arises of why this tissue should elaborate two hydrolases which catalyze the same reactions. The cellulase that forms first is synthesized by and accumulates in vesicles, where it would never encounter cellulose, while the other is concentrated on the inner wall microfibrils. It is suggested that only the latter cellulase functions to hydrolyze cellulose. A precursor/ product relationship between them could explain their distribution and developmental kinetics, but physical and chemical differences mitigate against this interpretation. 

Thus, in various insect species, the expression of CSP occurs in many different tissues, especially in the legs and contact sensory organs. The differences between CSPs and OBPs in tissue distribution and developmental expression suggest that the roles of these proteins in chemoreception may also be different. CSPs may have a broader function than OBPs, functioning in more systems than olfaction and taste, perhaps as general molecule carriers but especially involved in the transport of contact sensory molecules. 

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