Growth of rural and urban children in the Valley of Oaxaca,Mexico

Weight, stature, arm circumference, and the triceps skinfold were measured in 1,410 school children, 6 through 14 years of age, from two urban colonias in the city of Oaxaca de Juarez (n = 479), and from two rural Ladino (n = 467) and two rural Zapotec (n = 464) communities in the Valley of Oaxaca in southern Mexico. Children from rural Ladino communities and urban colonias are significantly taller, heavier, and more muscular than children in rural Zapotec communities. The differences between rural Ladino and urban colonia children favor the former, particularly for weight and stature. These observations thus suggest (1) that children in the rural, indigenous communities in the Valley of Oaxaca are relatively undernourished compared to children in Ladinoized and urban communities, and (2) that rural-to-urban migration does not necessarily result in improved growth status.     

Growth of rural and urban children in the valley of Oaxaca,Mexico

Weight, stature, arm circumference, and the triceps skinfold were measured in 1,410 school children, 6 through 14 years of age, from two urban colonias in the city of Oaxaca de Juarez (n = 479), and from two rural Ladino (n = 467) and two rural Zapotec (n = 464) communities in the Valley of Oaxaca in southern Mexico. Children from rural Ladino communities and urban colonias are significantly taller, heavier, and more muscular than children in rural Zapotec communities. The differences between rural Ladino and urban colonia children favor the former, particularly for weight and stature. These observations thus suggest (1) that children in the rural, indigenous communities in the Valley of Oaxaca are relatively undernourished compared to children in Ladinoized and urban communities, and (2) that rural-to-urban migration does not necessarily result in improved growth status.     

Chromosome Interactions in DROSOPHILA MELANOGASTER. II. Total Fitness

In a large experiment, using nearly 200 population cages, we have measured the fitness of Drosophila melanogaster homozygous (1) for the second chromosome, (2) for the third chromosome, and (3) for both chromosomes. Twentyfour second chromosomes and 24 third chromosomes sampled from a natural population were tested. The mean fitness of the homozygous flies is 0.081 ± 0.014 for the second chromosome, 0.080 ± 0.017 for the third chromosome, and 0.079 ± 0.024 for both chromosomes simultaneously. Assuming that fitnesses are multiplicative (the additive fitness model makes no sense in the present case because of the large selection coefficients involved), the expected mean fitness of the homozygotes for both chromosomes is 0.0066; their observed fitness is more than ten times greater. Thus, it appears that synergistic interactions between loci are considerable; and that, consequently, the fitness function substantially departs from linearity. Two models are tentatively suggested for the fitness function: a "threshold" model and a "synergistic" model.—The experiments reported here confirm previous results showing that the concealed genetic load present in natural populations of Drosophila is sufficient to account for the selective maintenance of numerous polymorphisms (of the order of 1000).     

Uptake and fate of bacteriophage phi W-14 DNA in competent Bacillus subtilis.

Phage phi W-14 DNA (in which one-half of the thymine residues are replaced by alpha-putrescinyl thymine) was taken up by competent Bacillus subtilis cells at a rate threefold higher than the rate of homologous DNA uptake. In contrast to other types of heterologous DNA, the amount of phi W-14 DNA taken up in 15 min exceeded the amount of homologous DNA taken up by a factor of two to three, as measured in terms of acid-precipitable material. The amount of phi W-14 DNA taken up was even greater than this analysis indicated if allowance was made for the fact that phi W-14 DNA was degraded more rapidly after uptake than homologous DNA. Competition experiments showed that the affinity of phi W-14 DNA for homologous DNA receptors was lower than the affinity of homologous DNA and was similar to the affinities of other types of heterologous DNA. The more rapid and more extensive uptake of phi W-14 DNA appeared to occur via receptors other than the receptors for homologous DNA, and these receptors (like those for homologous DNA) were an intrinsic property of competent cells. Uptake of phi W-14 DNA was affected by temperature, azide, EDTA, and chloramphenicol, as was uptake of homologous DNA. This was consistent with entry of both DNAs by means of active transport. After uptake, undegraded phi W-14 [3H]DNA was found in the cells in a single-stranded form, whereas a portion of the label was associated with recipient DNA, presumably as a result of incorporation of monomers resulting from degradation. Acetylation of the amino groups of the putrescine side chains in phi W-14 DNA decreased the affinity of this DNA for its receptors without affecting its ability to compete with homologous DNA.     

In vitro metabolism of C19 steroids in human endometrium

In order to quantitate the extent of intracellular metabolic conversions of C19 steroids in human endometrium, specimens of proliferative and secretory tissue were superfused at a constant rate with several pairs of labeled compounds at low concentrations. About 16% of dehydroepiandrosterone sulfate interacting with endometrial cells was converted to dehydroepiandrosterone and about 3% of this compound was converted to androstenedione. Androstenedione was reversibly reduced to testosterone and the extent of this conversion was shown to be several-fold higher in secretory than in proliferative tissue. About 1% of testosterone entering the cells was reduced to 5 alpha-dihydrotestosterone. These results demonstrate that the conversion of the main circulating C19 steroids in women, i.e. dehydroepiandrosterone sulfate and androstenedione, to 5 alpha-dihydrotestosterone, the compound considered to be the true intracellular androgen, is very small. In contrast, formation of testosterone from androstenedione is extensive and increases during the luteal phase under the influence of progesterone, a hormone known to stimulate the activity of 17 beta-hydroxysteroid dehydrogenase in human endometrium.     

Nitrofurantoin prompts the stringent response in Bacillus subtilis

Nitrofurantoin causes the stringent response in Bacillus subtilis. After exposure of a stringent strain to this drug, the intracellular concentrations of guanosine 3'-diphosphate 5'-diphosphate (ppGpp), guanosine 3'-diphosphate 5'-triphosphate (pppGpp) and ATP increased, while that of GTP decreased. In a relaxed strain no accumulation of ppGpp or pppGpp was observed, but both GTP and ATP declined after the addition of nitrofurantoin. Protein synthesis was equally sensitive to nitrofurantoin in both the stringent and relaxed strains, but the drug inhibited RNA accumulation only in the stringent strain, not in the relaxed strain. Nitrofurantoin also caused the accumulation of ppGpp in Escherichia coli and Serratia marcescens.     

Volatile constituents of Cupressus dupreziana and the sesquiterpenes of Cupressus sempervirens

Analysis of wood essential oil of Cupressus dupreziana revealed 26 components: 13 monoterpenes and 13 sesquiterpenes. The main components were carv     

Reactions between diglycolaldehyde dithioacetals and some nucleophiles

The homogeneous, neutral polysaccharide isolated from the crude polysaccharide of the fruit pulp from bael (Aegle marmelos) contains arabinose, galactose, and glucose in the molar ratios of 2:3:14. The linkages among the different monosaccharide residues were established through methylation analysis and Smith-degradation studies of the polysaccharide. The anomeric configurations of the different glycosyl groups were determined by study of the chromium trioxide oxidation of the acetylated polysaccharide. Results of these experiments have been discussed in order to assess the structure of the neutral polysaccharide.