The delineation of fertility strategies in a tribal population of India: the Koyas of Koraput District,Orissa

Demographic data collected for a tribal population of India, the Koyas of Koraput District, Orissa, were examined in light of 2 models of reproductive behavior associated with the economic value of children: the replacement effect and son survivorship motivation. Both models are united in the concept that infant/child mortality affects subsequent fertility. The database consists of retrospective fertility histories of Koya women who had completed their reproductive period. The total number was 260, with the total offspring numbering 1407. 2 distinct cohorts of women were formed for the purpose of analysis, separated only by the criterion of offspring survival: women who had experienced infant child mortality (129 women with 739 children); and women who completed their reproductive period without suffering offspring loss of this nature (132 women with 668 children). The cohort without child loss had a mean parity of 5.10, lower than the average parity of 5.73 recorded for the cohort whose reproductive histories included at least 1 infant/child death. Age specific marital fertility and birth interval analyses indicated that this differential was because of biological, not behavioral, factors. The age pattern of fertility of females suffering offspring mortality failed to demonstrate a high rate of childbearing in the later age intervals of the reproductive period, a characteristic pattern of couples attempting to "replace" lost offspring. Birth interval analysis pointed to biological "interval effect," whereby infant/child mortality caused a cessation of lactation and hence a shortening of postpartum amenorrhea. Computer simulation further indicated that the higher fertility differential of the cohort experiencing offspring loss still did not result in high son survivorship values. The findings agree with earlier studies indicating that for predemographic transitional populations, economically motivated fertility strategies are ineffectual.     

Isoenzyme differences between three closely related species of Lineus (Heteronemertea)

Starch-gel electrophoresis was employed to compare six enzymes in three closely related species of nemertean worms, Lineus ruber (Müller, 1774), Lineus sanguineus (Rathke, 1799), and Linens viridis (Müller, 1774). Differences in mobility recorded for most of the enzyme loci examined support the hypothesis that these nemerteans are distinct taxa.     

Translation of insulin-related polypeptides from messenger RNAs with tandemly reiterated copies of the ribosome binding site

Plasmids have been constructed containing reiterated copies of a 66 bp fragment, loosely referred to as the ribosome binding site, that includes the AUG initiator codon of preproinsulin. The extreme test involved plasmid 255/17, which carried four tandem copies of the ribosome binding site, with all four AUG triplets in the same reading frame as the preproinsulin coding sequence downstream. Initiation at any potential start site would generate a polypeptide precipitable with anti-insulin antiserum, and its size would reveal the AUG(s) active in initiation. One insulin-related polypeptide was synthesized in cells transfected by p255/17; its size corresponded to the product initiated at the first ribosome binding site in the tandem array. Inasmuch as the three downstream AUG triplets, which are not used, occur in a sequence context identical with that around the 5'-proximal AUG triplet, which is used, the position of an AUG triplet relative to the 5' end of the mRNA appears to be important in identifying it as a functional initiator codon.     

Neocarzinostatin chromophore: Presence of a highly strained ether ring and its reaction with mercaptan and sodium borohydride

Spectroscopic evidence suggests the presence of a highly strained ether ring (Fig. 1) (possibly an epoxide) in the C₁₂-subunit of the previously determined partial structure $\text{2a}$ (Fig. 2) of the major neocarzinostatin chromophore (NCS-Chrom $\text{A}$) which completes assignment of all the oxygens in the molecule. The main product from mercaptan treatment suggests opening of the ether ring involving the addition of one molecule of mercaptan as well as reduction of the C₁₂-substructure, whereas a parallel two-step reduction occurs on NaBH₄ treatment. Both reactions occur with rearrangement of the C₁₂-substructure and the implication for the mechanism of action of NCS-Chrom $\text{A}$ in DNA strand scission activity is discussed. The evidence suggests a downward revision of the molecular formula for NCS-Chrom $\text{A}$ as well as minor components $\text{B}$ and $\text{C}$ by two protons.     

Role of membrane-associated thiol groups in the functional regulation of gastric microsomal (H+ + K+)-transporting ATPase system.

The distribution of free thiol groups associated with the membrane proteins of the purified pig gastric microsomal vesicles was quantified, and the relation of thiol groups to the function of the gastric (H+ + K+)-transporting ATPase system was investigated. Two different thiol-specific agents, carboxypyridine disulphide (CPDS) and N-(1-naphthyl)maleimide (NNM) were used for the study. The structure-function relationship of the membrane thiol groups was studied after modification by the probes under various conditions, relating the inhibition of the (H+ + K+)-transporting ATPase to the ATP-dependent H+ accumulation by the gastric microsomal vesicles. On the basis of the extent of stimulation of the microsomal (H+ + K+)-transporting ATPase in the presence and absence of valinomycin (val) about 85% of the vesicles were found to be intact. CPDS at 1 mM completely inhibits the valinomycin-stimulated ATPase and the associated p-nitrophenyl phosphatase with a concomitant inhibition of vesicular H+ uptake. Both the enzyme and dye-uptake activities were fully protected against CPDS inhibition when the treatment with CPDS was carried out in the presence of ATP. ATP also offered protection (about 65%) against NNM inhibition of the (H+ + K+)-transporting ATPase system and vesicular H+ uptake. Under similar conditions ATP also protected about 10 and 6 nmol of thiol groups/mg of protein respectively from CPDS and NNM reaction. Our data suggest that the thiol groups on the outer surface of the vesicles are primarily involved in gastric (H+ + K+)-transporting ATPase function. Furthermore, at least about 15% of the total microsomal thiol groups appear to be associated with the ATPase system. The data have been discussed in terms of the structure-function relationship of gastric microsomes.     

Proteins of the sieve-tube exudate of Cucurbita maxima

Summary Sieve-tube exudate which appears on cut surfaces of stems of Cucurbita maxima as distinct droplets has been depicted in electron micrographs of longitudinal sections of the phloem. The exudate, which was produced from mature sieve tubes only, contained filaments of P-protein, but no mitochondria or vesicles of endoplasmic reticulum. The water-soluble part of the exudate contained at least 12 proteins, as shown by disc-electrophoresis. Enzymic activity was found for peroxidases, acid phosphatases, and aldolases. Color tests and assays for other enzymes, including ATPase, fructokinase, several dehydrogenases, and UDP-glucose: D-fructose-2-glucosyl transferase, gave negative results. With repeated cutting of a stem, the protein content of the exudate increased, while the amount of exudate decreased.Supported by Deutsche Forschungsgemeinschaft and Stiftung Volkswagenwerk. During part of this investigation the senior author held a U.S. National Science Foundation Senior Foreign Scientist Fellowship at the University of Wisconsin.     

Effect of Temperature on the Fatty Acid Composition of Thermus aquaticus

Thermus aquaticus contains four major fatty acids, iso-C(15) (28%), iso-C(16) (9%), normal-C(16) (13%), and iso-C(17) (48%), when grown at 70 C, as determined by gas chromatography and mass spectrometry. Small amounts of iso-C(12), normal-C(12:1), iso-C(13), normal-C(14), iso-C(14), and normal-C(15:1) were also detected. A change in growth temperature (50 to 75 C at 5-C intervals) affects a shift in the proportions of some of the fatty acids. The proportions of the monoenoic and branched-C(17) fatty acids decreased and the proportions of the higher-melting iso-C(16) and normal-C(16) fatty acids increased. Cells grown at 75 C contained 70% more total fatty acids than cells grown at 50 C. The largest increases, in absolute amounts, were in the content of iso-C(16) and normal-C(16) fatty acids, with only a 1.6-fold increase in the major iso-C(15) and iso-C(17) fatty acids. There was a 2.5-fold decrease in normal-C(15:1) and at least a 24-fold decrease in anteiso-C(17), which is present at 50 and 55 C but not at higher temperatures. There was no difference in proportion or amount of fatty acids between exponential and stationary-phase cells grown at 70 C. When cells were grown on glutamate instead of yeast-extract and tryptone at 70 C, the total fatty acid content remained constant, but there was an increase in the proportions of iso-C(16) and normal-C(16) fatty acids concomitant with a decrease in the proportions of the iso-C(15) and iso-C(17) fatty acids.     

Liberation and Development of Allomyces arbuscula Mitospores Viewed by Scanning Electron Microscopy

Scanning electron microscopy has been employed to examine events in the release and development of mitospores of the aquatic fungus, Allomyces arbuscula. Among the salient features of spore release from the mitosporangium is the digestion of the inner matrix of the exit papillum. Hydrolysis appears to begin at the outer layer of the papillum plug matrix and probably results from activation of localized hydrolytic enzymes. The plug clearly consists of at least two different component layers. Elaboration of mitospores from the mitosporangium is depicted in several micrographs. Motile spores were induced to begin development, and the sequence of surface changes associated with the encystment process was studied. Time course studies show the retraction of the flagellum, the change from elipsoidal to spherical shape, and the deposition of the cell wall. Early in encystment, small vesicles accumulate on the surface of the plasma membrane. These enlarge and fuse to form the mature cyst wall. This surface view of cell wall deposition appears to support the possible role of gamma particles in cell wall synthesis during encystment.