Genetic study of the Evens, an ancient human population of eastern Siberia

Three territorial subgroups of reindeer breeders, fishermen, and fur hunters living under conditions of partial isolation in remote parts of the Yakut ASSR, have been investigated with respect to polymorphic genetic systems. Analysis of covariance matrices containing allele frequencies in an array of 12 loci for a large sample of Evens, Nganasans, and reindeer Chukchi indicates that the genetic relationships support known phylogenetic, linguistic, and historical events.     

Populations of Methanogenic Bacteria in a Georgia Salt Marsh

Methanogens represented about 0.5% of the total bacteria in sediments from a Georgia salt marsh in which Spartina alterniflora is the predominant vegetation. The population of methanogens was composed of at least two groups of nearly equal size. One group was represented by cocci which were able to utilize trimethylamine and were unable to use H₂ or acetate. The second group was composed of two subgroups which were able to utilize H₂ but were unable to use trimethylamine or acetate. The more common subgroup included rod- or plate-shaped methanogens which could utilize isopropanol in addition to H₂ and formate. The second subgroup included Methanococcus maripaludis, which utilized only H₂ and formate. Other groups of methanogens were also present, including Methanosarcina sp. which utilized acetate, H₂, and methylamines. In addition to the overall variability in the types of methanogens, the numbers of methanogens in sediments also exhibited significant spatial variability both within and between tall- and short-Spartina zones.     

Radioiodinated 1-(2-fluoro-4-iodo-2,4-dideoxy-beta-L-xylopyranosyl)-2-nitroimidazole: a novel probe for the noninvasive assessment of tumor hypoxia.

1-(2-Fluoro-4-iodo-2,4-dideoxy-beta-L-xylopyranosyl)-2-nitroimidazole (FIAZP) has been synthesized and labeled with radioiodine (125I). Radioiodinated FIAZP is one of a series of sugar-coupled 2-nitroimidazoles developed in our laboratory as probes for noninvasive scintigraphic assessment of tumor hypoxia. An in vivo biodistribution study with [125I]FIAZP in the murine BALB/c EMT-6 tumor model showed a tumor-to-blood ratio of 6, 24 h after injection, with 0.5% of the injected dose present per gram of tumor. These values are several times higher than the respective ratios and distribution values in any of the organs, with the exception of liver. Radioactivity from tissues other than tumor and liver declined with time, following the decline of blood radioactivity. Rapid whole-body elimination of radioactivity was observed (> 96% in 24 h). The thyroid showed little uptake of radioactivity, indicating minimal in vivo deiodination. 1-(2-Fluoro-4-iodo-2,4-dideoxy-beta-L-xylopranosyl)-2-nitroimidazo le appears to undergo hypoxia-dependent binding in tumor tissue at levels comparable to those of other sugar-coupled 2-nitroimidazoles. The potential for imaging with this compound is discussed.     

Seeing sunlit owls in a new light: orienting Snowy Owls may not be displaying

Snowy Owls Bubo scandiacus often face the sun when sitting on the ground or when perched. Such sun‐orienting has been suggested to represent a visual display to conspecifics but other explanations have not been thoroughly examined. We observed the orientation of wintering Snowy Owls to both the sun and the wind, and their perching behaviour during two winters in central Saskatchewan, Canada. We proposed three new explanations for sun orientation in addition to the display hypothesis: thermoregulation, hunting and defence against predators. On sunny days, 44% of 710 Owls faced the sun; this was non‐random because few did so on overcast days. Sun‐ as opposed to wind‐orienting was strongly associated with weather conditions. Logistic regressions indicated that at temperatures below –13 °C and at wind speeds greater than about 18 km/h, Owls tended to orient to the wind rather than to the sun. The likelihood of wind‐orienting increased if the Owl perched above the ground, whereas the likelihood of sun‐orientating increased slightly when the Owl was sitting on the ground. There was no difference between the sexes in orienting behaviour. Snowy Owls seemed to prioritize wind‐orienting for thermoregulation but the results are also consistent with the idea that sun‐orientation can reduce heat loss. Facing into the sun did not support the hunting explanation because the birds would have been blinded and not able to see prey, but was consistent with the protection explanation if it helps to increase vigilance against enemies. Although we cannot completely rule out the display explanation, the spatial context of sunning Owls and a lack of a sex effect makes it unlikely that this is the main function. Instead, Owls seem to trade‐off wind‐ vs. sun‐orienting according to the prevailing weather conditions and do so mainly to thermoregulate and perhaps to maintain vigilance.     

pH oscillations and constant low pH delay the appearance of highly branched (colonial) mutants in chemostat cultures of the quorn(R) myco-protein fungus, Fusarium graminearum A3/5

At pH 5.8, highly branched (colonial) mutants appear in glucose-limited chemostat cultures of Fusarium graminearum A3/5 after ca. 400 h (ca. 107 generations) of growth. The appearance of these mutants was delayed by up to 144 h (45 generations) when the culture was switched at intervals of 120 h between pH 4.8 and 6.6. The concentration of cycloheximide-resistant macroconidia in the culture was used as an indicator of the periodic selection of advantageous mutants and it was found that, in chemostat populations subjected to pH oscillations, the interval (210 +/- 20 h) between peaks was nearly double that observed in chemostat populations cultured at constant pH (124 +/- 12 h at constant pH 5.8 and 120 h +/- 17 h at constant pH 4.5), indicating that the population evolved more slowly under oscillating pH than under constant pH. When grown in mixed culture with the parental strain (A3/5), the selective advantage of two colonial mutants isolated from chemostat cultures grown under conditions of oscillating pH was found to be pH dependent. Compared to cultures grown at constant pH 5.8, a delay of ca. 312 h (87 generations) in the appearance of colonial mutants was observed when F. graminearum A3/5 was grown in glucose-limited chemostat culture at constant pH 4.5. (c) 1996 John Wiley & Sons, Inc.     

Characterization of recombinant human factor VIII

Recently, complete human factor VIII DNA clones have been obtained and subsequently expressed in baby hamster kidney cells (Wood, W. I., Capon, D. J., Simonsen, C. C., Eaton, D. L., Gitschier, J., Keyt, B., Seeburg, P. H., Smith, D. H., Hollingshead, P., Wion, K. L., Delwart, E., Tuddenham, E. G. D., Vehar, G. A., and Lawn, R. M. (1984) Nature 312, 330-337). The recombinant factor VIII (rVIII) protein secreted from these cells has now been purified allowing its structural analysis and comparison to plasma-derived factor VIII (pdVIII). Analysis of purified rVIII by sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that it consists of multiple polypeptides with relative mobilities (Mr) ranging from 80,000-210,000. The same pattern of polypeptides is also observed for pdVIII resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The proteins associated with rVIII are recognized by pdVIII antibodies in a Western blot. When rVIII and pdVIII are subjected to isoelectric focusing they are resolved into a similar pattern of protein bands. Thrombin, factor Xa, and activated protein C, which modulate factor VIII activity by proteolysis, process rVIII in the same manner they do pdVIII. As is the case for pdVIII, thrombin activation of rVIII coagulant activity correlates with the generation of subunits with Mr of 73,000, 50,000 and 43,000. These subunits appear to form a metal-(perhaps Ca2+) linked complex. EDTA inactivates thrombin-activated rVIII and pdVIII, with the activity being regenerated after the addition of a molar excess of MnCl2. The results suggest that rVIII is structurally and functionally very similar to pdVIII.     

The Effect of Short-Term H2S Fumigation on Nitrate Reductase Activity in Spinach Leaves

Short-term exposure of spinach plants to 250 ppb H₂S at a photonfluence rate of 35µmol m^–2s^–1 (within the400–700 nm range) in the ambient air did not affect invitro nitrate reductase activity (NRA) in the leaves. Likewise,H₂S exposure did not significantly affect in vivo NRA measuredunder anaerobic conditions. In vivo NRA of untreated plantswas apparently inhibited in the presence of oxygen. However,shortterm H₂S exposure increased in vivo "aerobic" NRA up tofive fold of that of untreated plants. H₂S induced increaseof in vivo "aerobic" NRA depended on the sulfide concentration.After 24 hours of exposure maximal increase (two to five fold)of in vivo NRA "aerobic" was observed at 220 ppb H₂S. It isproposed that H₂S inhibited NADH oxidizing enzymes, which resultedin an increase in NADH supply to nitrate reductase (NR) in thepresence of oxygen. It was unlikely that the increase in invivo "aerobic" NRA in sulfide exposed plants was due to an alteredcompetition between mitochondrial respiration and NR since leafrespiration was not affected by an exposure to 250 ppb H₂S (Received February 12, 1986; Accepted June 27, 1986)     

Variation in the Fine Structure of a Marine Achromobacter and a Marine Pseudomonad Grown Under Selected Nutritional and Temperature Regimes

Certain features of the fine structure of a marine achromobacter and a marine pseudomonad were dependent upon the conditions of growth. Cells of achromobacter grown at 10 C in a low peptone-seawater (SW) medium displayed the characteristic morphology of the achromobacter: a regularly undulant outer element of the cell wall and a planar inner element, tightly packed ribonucleoprotein (RNP) particles in the cytoplasm, deoxyribonucleic acid (DNA) disposed in a lobate manner, and dense inclusion bodies. Few mesosomes, however, were seen. Cells of achromobacter grown at 10 C in a high peptone-SW medium had larger and more highly organized mesosomes. At 22 C, in a low peptone-SW medium, no mesosomes were seen, but the inclusions were more frequently seen and were larger in the achromobacter cells. At 22 C, in a high peptone-SW medium, these cells revealed the greatest variation in cellular morphology. They contained both small and large mesosomes, or no mesosomes, and both small and large inclusions, or no inclusions. Pseudomonad cells at 10 C in a low peptone-SW medium revealed a typical gram-negative morphology: double-layered, irregularly undulant cell wall; more nearly planar cytoplasmic membrane; densely stained, lightly packed RNP particles; finely fibrillar, axially disposed DNA; simple mesosomes. At 10 C, in a high peptone-SW medium, pseudomonad cells revealed associated strands of material and intracytoplasmic ringlike structures. At 22 C, in a low peptone-SW medium, pseudomonad cells had a more undulant cell-wall and a more nearly planar cytoplasmic membrane. At 22 C, in a high peptone-SW medium, these cells revealed prominent blebs of the cell wall.     

Increased transglutaminase in the aortas of cholesterol-fed rabbits: occurrence of buffer soluble and insoluble forms and an inhibitor.

Rabbits were fed for 10-12 weeks on a normal pellet diet or on the same diet containing 1% cholesterol and 6% peanut oil. The animals were killed and the aortas divided into three layers which were homogenized and extracted. The extracts and the insoluble residues were assayed for transglutaminase activity and tissue transglutaminase antigen. When compared with normal aortas, the inner and middle layers of aortas with atherosclerotic lesions from cholesterol-fed rabbits showed higher transglutaminase activities in the buffer-soluble fraction without a corresponding increase in antigen. The buffer extracts showed two peaks (I and II) of activity and antigen on DE 52 chromatography; peak I was also found, together with lipid, in Triton X-100 extracts of the buffer-insoluble residue. The Triton X-100 insoluble fraction showed higher concentrations of both activity and antigen in the inner and middle layers of atherosclerotic aortas than in normal aortas, but the activity per nanogram of antigen was lower than in the buffer-soluble fraction. The activity in this insoluble residue was largely extracted, together with an inhibitor, by an NaCl-sucrose-dithiothreitol-Triton X-100 solution. DE 52 chromatography of this extract showed a third peak of activity and antigen (peak III) and an inhibitor peak that was distinct from the activity peaks.     

Effect of choline on the morphology, growth and phospholipid composition of Fusarium graminearum

Studies were made of the growth kinetics, morphology and phospholipid composition of two strains of Fusarium graminearum, a wild-type strain (A3/5) and a highly branched variant (C106) which arose spontaneously during cultivation of A3/5. No significant difference was observed between the hyphal diameters of the two strains and therefore increased branching of C106 could not be explained in the terms of an increase in hyphal radius in the absence of a change in hyphal growth unit volume. The two strains had the same specific growth rate in batch culture and this was not affected by the addition of up to 1.5 mM-choline to the medium. However, choline increased the mean hyphal extension rate and colony radial growth rate of both strains and this response was correlated with the formation of mycelia which were more sparsely branched than mycelia grown on medium lacking choline. Addition of betaine, choline, ethanolamine, monomethylethanolamine or dimethylethanolamine (but not serine, glycine, dimethylglycine, methylamine, hydroxylamine or beta-hydroxyethylhydrazine) to the medium also resulted in appreciable increases in the colony radial growth rates of A3/5 (increased by about 130% for choline) and C106 (increased by about 25% for choline). No significant difference was observed between the phospholipid compositions of the two strains, and the addition of 100 microM-choline to the medium had no significant effect on the phospholipid composition of either strain.