Birth spacing and infant mortality: evidence for eighteenth and nineteenth century German villages

Data from an historical population in which fertility control was minimal and modern health services were mostly unavailable are used to show that there appears to have been a strong association between previous birth interval length and infant mortality, especially when the previous child survived. Although only imperfect proxies for breast-feeding practices and other potentially confounding factors are available for this population, the results suggest that the association between previous interval length and infant mortality in this population is not solely, or primarily, a function of differences in breast-feeding behaviour or socioeconomic status. Other factors, e.g. maternal depletion or sibling competition, are more likely to explain the observed association.     

Methionine regeneration and aminotransferases in Bacillus subtilis,Bacillus cereus,and Bacillus anthracis

The conversion of ketomethiobutyrate to methionine has been previously examined in a number of organisms, wherein the aminotransferases responsible for the reaction have been found to be members of the Ia subfamily (L. C. Berger, J. Wilson, P. Wood, and B. J. Berger, J. Bacteriol. 183:4421-4434, 2001). The genome of Bacillus subtilis has been found to contain no subfamily Ia aminotransferase sequences. Instead, the analogous enzymes in B. subtilis were found to be members of the If subfamily. These putative aspartate aminotransferases, the yugH, ywfG, ykrV, aspB, and patA gene products, have been cloned, expressed, and characterized for methionine regeneration activity. Only YkrV was able to convert ketomethiobutyrate to methionine, and it catalyzed the reaction only when glutamine was used as amino donor. In contrast, subcellular homogenates of B. subtilis and Bacillus cereus utilized leucine, isoleucine, valine, alanine, phenylalanine, and tyrosine as effective amino donors. The two putative branched-chain aminotransferase genes in B. subtilis, ybgE and ywaA, were also cloned, expressed, and characterized. Both gene products effectively transaminated branched-chain amino acids and ketoglutarate, but only YbgE converted ketomethiobutyrate to methionine. The amino donor preference for methionine regeneration by YbgE was found to be leucine, isoleucine, valine, phenylalanine, and tyrosine. The B. subtilis ybgE gene is a member of the family III of aminotransferases and falls in a subfamily designated here IIIa. Examination of B. cereus and Bacillus anthracis genome data found that there were no subfamily IIIa homologues in these organisms. In both B. cereus and B. anthracis, two putative branched-chain aminotransferases and two putative D-amino acid aminotransferases were discovered as members of subfamily IIIb. These four sequences were cloned from B. cereus, expressed, and characterized. Only the gene product from the sequence designated Bc-BCAT2 was found to convert ketomethiobutyrate to methionine, with an amino donor preference of leucine, isoleucine, valine, phenylalanine, and tyrosine. The B. anthracis homologue of Bc-BCAT2 was also cloned, expressed, and characterized and was found to be identical in activity. The aminooxy compound canaline was found to be an uncompetitive inhibitor of B. subtilis YbgE and also inhibited growth of B. subtilis and B. cereus in culture.     

Comparative evaluation and economic potential of ecorational versus chemical insecticides for crucifer flea beetle (Coleoptera: Chrysomelidae) management in Canola

From 2001 to 2004, field studies were conducted to evaluate the effect of the ecorational insecticides SpinTor (spinosad), BotaniGard (Beauveria bassiana), Neemix (azadirachtin), and Surround (kaolin) against crucifer flea beetle on canola, Brassica napus L., at the cotyledon stage. The ecorational treatments were compared with a standard foliar chemical insecticide, Capture (bifenthrin), and the chemical seed treatment insecticide Helix XTra (thiamethoxam). This study indicated that flea beetle injury was lower for Helix XTra, Capture, and the ecorational insecticide SpinTor. SpinTor was less effective when flea beetle populations were relatively high (200-300 per trap-week). Yields for chemical insecticide treatments were always greater than SpinTor, with differences being the smallest (68-374 kg/ha) at low levels of flea beetle feeding injury. Differences were greatest when canola seedling injury was high (775-1,364 kg/ha). Yield differences between the conventional insecticides and BotaniGard, Neemix, and Surround were 119-439 and 61-2,248 kg/ha at low and high flea beetle feeding injury, respectively. Although yield differences between SpinTor and chemical insecticides were relatively small at lower levels of flea beetle injury, net losses ranged from $47 to $151/ha when SpinTor was used as an alternative to a standard chemical seed treatment, Helix XTra. This suggests that SpinTor would not be a viable alternative to the chemical insecticide. Net losses ranged from $30 to $266/ha when BotaniGard, Neemix, and Surround were used as alternatives to the seed treatment.