On the role of p53 in the cellular response to aneuploidy

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The effect of bovine serum albumin on partial reactions of palmitoyl-CoA chain elongation by rat liver microsomes.

In the absence of albumin, v/s curves for both condensation and overall chain elongation demonstrated that the specific activity for overall chain elongation was 3.7 times that of condensation. When the molar ratio of palmitoyl-CoA to albumin was greater than 2 : 1, the specific activity of chain elongation exceeded that of condensation. At these low albumin concentrations, in the absence of NADPH, the beta-ketostearoyl-coA was converted back to palmitate. This cleavage reaction is inhibited by albumin in a concentration-dependent manner. When the palmitoyl-CoA to albumin molar ratio was less than 2 : 1, the specific activity for condensation exceeded that for overall chain elongation and some beta-ketostearate was shown to accumulate under chain elongation conditions. The specific activity for dehydration of beta-hydroxystearoyl-CoA was maximal when the acyl-CoA to albumin molar ratio was between 10 : 1 and 4 : 1 but the rate of this reaction was not markedly influenced by variations in albumin concentration. The specific activity for the NADPH-dependent reduction of 2-trans-octa-decenoyl-CoA was 18 nmol . min(-1) . mg(-1) in the absence of albumin and increased to a maximum of 112 when the substrate to albumin molar ratio was 2 : 1. At higher albumin concentrations the reductase reaction was inhibited. Conversely, the specific activity for the reverse dehydrase was maximal at low albumin concentrations and the rate of this reaction declined as the albumin concentration increased. Our results demonstrate that albumin not only alleviates a substrate induced inhibition but also regulates the metabolic fate of 2-trans-octadecenoyl-CoA and in this regard may possibly substitute for acyl-CoA binding proteins.     

Beta-globin gene cluster haplotype distribution in five Brazilian Indian tribes

Haplotypes derived from five polymorphic restriction sites in the beta-globin gene cluster were investigated in 139 individuals from five different Brazilian Indian tribes by the polymerase chain reaction (PCR). Eight haplotypes were identified. Haplotypes 2 (+????) and 6 (?++?+) were the most frequent and were common to all tribes. Their prevalences ranged from 60% to 93% and from 3% to 18%, respectively. Average heterozy-gosity measured by the Gini-Simpson index is markedly reduced among these Brazilian Indians when compared with Europeans (56%), but much less (8%) in relation to Asiatics, suggesting the absence of an important bottleneck effect in the early colonization of South America. The coefficient of gene differentiation (GST′) was estimated as 0.082 among six Brazilian Indian tribes, but when only three Tupi-Mondé-speaking tribes were considered, this estimate was reduced to 0.030. © 1995 Wiley-Liss, Inc.     

Theoretical analysis of lethal factors in plant populations

In this article, we are interested in the problem of the existence of a few linkage groups in which lethal infertile genes associated with yield factors are present. This hypothesis is supported by the finding of natural balanced lethal systems, which keep a short heterotic chromosome segment. It is very important to predict the number of generations that a balanced lethal system maintains in its linkage, in order to get a permanent heterozygosis without any problem with recombination. For theoretical analysis we have used the theory of absorbing Markov chains, discrete in space and time, because this is well suited to crops like barley. It results from studying some experimental data obtained by Ewald A. Favret in the CICA, INTA, Castelar, Argentina.     

Differential Accumulation of Translatable mRNA Species During a Specific Host-pathogen Interaction Between Puccinia recondita tritici and Triticum aestivum

The time-course of mRNA induction in specific cultivar-race combinations was examined using a criss-cross interaction system consisting of nearly isogenic lines of wheat (Sinvalocho M.A. and Gamma 1R) and genetically related pathogenic races of leaf rust Puccinia recondita f. sp. tritici . Infection stimulated the differential accumulation of mRNA species, identified by in vitro translation, after only three days of inoculation with rust spores. Comparisons of different host-pathogen combinations showed polypeptide pattern changes likely to be associated with gene-for-gene relationships. At least two specific mRNAs which code for polypeptide bands of 34 and 24 kDa are associated with the compatible interaction mediated by genes A₁,/A₂ from Gamma 1R wheat line and virulence gene p_t/p₂ of rust race FO₁. Comparisons made using a mutant clone of rust, which elicits an inverse criss-cross relationship with the same wheat lines, are consistent with the proposed specificity of the detected changes.
In addition, two wheat mRNAs (coding for polypeptide bands of 20.5 and 32.5 kDa) were elicited by infection with rust race FO₁ regardless the plant genotype or reaction type. A cDNA clone involved in this kind of race specific induction has been isolated.     

Antibiotic decontamination of the dog and its consequences.

An isolation-decontamination regimen was developed which effectively reduced the numbers of resident flora of the dog. Bacterial counts in four dogs before treatment were 3.8 X 10(9) per gram of feces; no organisms were detectable in these same dogs after treatment, however, the intestinal flora had returned to slightly above normal levels 1 week after treatment. Decontamination was accomplished in a laminar air flow system designed to minimize the area that had to be under controlled conditions. By determining the antibiotic sensitivities of 67 isolated organisms representing eight species or groups of bacteria recovered from the four dogs, a standardized antibiotic regimen was developed consisting of bacitracin and neomycin administered as a dry powder in the food. The decontamination treatment apparently did not affect host metabolism because no alterations in serum levels of urea nitrogen, glucose, phosphate, total protein, chloride, sodium, potassium, serum glutamic oxalacetic transaminase, or serum glutamic pyruvic transaminase were found in the antibiotic-treated dogs. The decontamination process did, however, reduce normal granulopoietic stimulation.     

Advances in tissue culture of adult larch

Summary This paper reviews some of the recent research on micropropagation of mature larch (Larix) trees. Different methods are reported concerning the use of the organogenic and embryogenic potential of adult plant material. Successful plant regeneration of adult larch trees by combining tissue culture methods is presented. The growth behavior of regenerated plants was compared with seedlings. Special attention was focused on preconditioning of donor material. Possible basic principles, responsible for a successful propagation of adult donor trees, are discussed. Based on a presentation at the IUFRO Meeting (Somatic Cell Genetics, and Molecular Genetics of Trees) held in Quebec City, PQ, Canada, August 12–16, 1997.