Twin death and mourning worldwide: a review of the literature.

Cultural beliefs about the nature of multiples appear in the mourning practices of many civilizations. Ethnographic literature suggests common themes that echo modern concepts. Many societies viewed twins as fragile, likely to die without preferential or meticulously equal treatment. A shared soul between twins is a common tenet, and the death of one is often felt to herald the other's prompt demise. The close relationship between multiples influences funerary rites. Honor, fear and mysticism are often evident in rituals. Twin infanticide was widely practiced, yet mourning customs were still observed. Many peoples recognize the special status of multiples and their families after one, two or more die.     

TOOLS FOR STUDYING THE CHLOROPLAST GENOME IN THE TRITICEAE (GRAMINEAE): AN ECORI MAP,A DIAGNOSTIC DELETION,AND SUPPORT FOR BROMUS AS AN OUTGROUP

Data on variation in the chloroplast genome can be used to estimate the phylogeny of the wheat tribe (Triticeae), but two tools have been needed—a restriction site map for at least one frequent-cutting enzyme, and a well-supported outgroup. This paper presents an EcoRI map, as well as maps for six other restriction enzymes, for two members of the tribe (Elytrigia repens and Secale cereale). These are compared to the maps for Bromus tectorum, a possible outgroup, and for Briza maxima, Lolium perenne, and Festuca rubra, other members of the same subfamily (Pooideae). A unique deletion of ca. 700 base pairs was discovered that provides a distinctive marker for the cytoplasm of plants with the S genome. The deletion also appears in Dasypyrum villosum (V genome). Cladograms based on restriction site data are unequivocal in the support for Bromus tectorum as a near relative of the Triticeae; the chloroplast phylogeny is very similar to the morphological cladogram for a comparable set of taxa.     

Distinguished Lecture in Archeology: Breaking and Entering the Ecosystem—Gender, Class, and Faction Steal the Show

This article was presented as the third annual Distinguished Lecture in Archeology at the 90th annual meeting of the American Anthropological Association, November 22, 1991, in Chicago, Illinois.     

Chemical Contamination of California Drinking Water

Drinking water contamination by toxic chemicals has become widely recognized as a public health concern since the discovery of 1,2-dibromo-3-chloropropane in California''s Central Valley in 1979. Increased monitoring since then has shown that other pesticides and industrial chemicals are present in drinking water. Contaminants of drinking water also include naturally occurring substances such as asbestos and even the by-products of water chlorination. Public water systems, commercially bottled and vended water and mineral water are regulated, and California is also taking measures to prevent water pollution by chemicals through various new laws and programs.     

Identification of HLA-B44 subtypes associated with extended MHC haplotypes

The HLA class I antigen B44 is found in each of two different extended major histocompatibility haplotypes (allele combinations of HLA-B, HLA-DR, and complement genes BF, C2, C4A, and C4B in linkage disequilibrium). Using isoelectric focusing, two variants of HLA-B44 were identified. The basic variant was found in all cell lines with the extended haplotype HLA-B44, DR7, FC31, and the acidic variant in all cell lines with the extended haplotype HLA-B44, DR4, SC30. The occurrence of each antigen variant with a unique extended haplotype explains previous observations concerning the nonrandom association of B44 variants with DR antigens.     

Effect of hydrophobicity of utilization of peptides by ruminal bacteria in vitro

When mixed ruminal bacteria were incubated with a pancreatic casein hydrolysate and free amino acids of a similar composition, rates of ammonia production were much greater for peptides than for amino acids. The pancreatic digest of casein was then fractionated with 90% isopropyl alcohol. Hydrophobic peptides which dissolved in alcohol contained an abundance of phenolic and aliphatic amino acids, while the hydrophilic peptides which were precipitated by alcohol contained a large proportion of the highly charged amino acids. The Km values of the mixed ruminal bacteria for each fraction were similar (0.88 versus 0.98 g/liter), but the Vmax of the hydrophilic peptides was more than twice that of the hydrophobic peptides (18 versus 39 mg of NH3 per g of bacterial protein per h). Pure cultures of ruminal bacteria had a similar preference for hydrophilic peptides and likewise utilized peptides at a faster rate than free amino acids. Since peptide degradation rates differed greatly, hydrophobicity is likely to influence the composition of amino acids passing unfermented to the lower gut of ruminant animals.     

Transport and phosphorylation of disaccharides by the ruminal bacterium Streptococcus bovis

Toluene-treated cells of Streptococcus bovis JB1 phosphorylated cellobiose, glucose, maltose, and sucrose by the phosphoenolpyruvate-dependent phosphotransferase system. Glucose phosphorylation was constitutive, while all three disaccharide systems were inducible. Competition experiments indicated that separate phosphotransferase systems (enzymes II) existed for glucose, maltose, and sucrose. [14C]maltose transport was inhibited by excess (10 mM) glucose and to a lesser extent by sucrose (90 and 46%, respectively). [14C]glucose and [14C]sucrose transports were not inhibited by an excess of maltose. Since [14C]maltose phosphorylation in triethanolamine buffer was increased 160-fold as the concentration of Pi was increased from 0 to 100 mM, a maltose phosphorylase (Km for Pi, 9.5 mM) was present, and this activity was inducible. Maltose was also hydrolyzed by an inducible maltase. Glucose 1-phosphate arising from the maltose phosphorylase was metabolized by a constitutive phosphoglucomutase that was specific for alpha-glucose 1-phosphate (Km, 0.8 mM). Only sucrose-grown cells possessed sucrose hydrolase activity (Km, 3.1 mM), and this activity was much lower than the sucrose phosphotransferase system and sucrose-phosphate hydrolase activities.     

Regulation of beta-glucosidase in Bacteroides ruminicola by a different mechanism: growth rate-dependent derepression

Bacteroides ruminicola B(1)4, a predominant ruminal and cecal bacterium, was grown in batch and continuous cultures, and beta-glucosidase activity was measured by following the hydrolysis of p-nitrophenyl-beta-glucopyranoside. Specific activity was high when the bacterium was grown in batch cultures containing cellobiose, mannose, or lactose (greater than 286 U/g of protein). Activity was reduced approximately 90% when the organism was grown on glucose, sucrose, fructose, maltose, or arabinose. The specific activity of cells fermenting glucose was initially low but increased as glucose was depleted. When glucose was added to cultures growing on cellobiose, beta-glucosidase synthesis ceased immediately. Catabolite repression by glucose was not accompanied by diauxic growth and was not relieved by cyclic AMP. Since glucose-grown cultures eventually exhibited high beta-glucosidase activity, cellobiose was not needed as an inducer. Catabolite repression explained beta-glucosidase activity of batch cultures and high-dilution-rate chemostats where glucose accumulated, but it could not account for activity at slow dilution rates. Maximal beta-glucosidase activity was observed at a dilution rate of approximately 0.35 h-1, and cellobiose-limited chemostats showed a 15-fold decrease in activity as the dilution rate declined. An eightfold decline was observed in glucose-limited chemostats. Since inducer availability was not a confounding factor in glucose-limited chemostats, the growth rate-dependent derepression could not be explained by other mechanisms.