Gm and Inv allotypes in French Guiana Indians.

Data from 302 individuals belonging to three populations of French Guiana Indians are reported. All the phenotypes except two can be explained by three haplotypes: Gm1,21, Gm1,2,21 and Gm1,10,11,25. The gene frequencies found in the present study are generally in accordance with those previously described among other South American Indians. For the Inv1,2 gene a high value has been found for the Wayanas and the Oyampis, but a difference appears for the Emerillons who possess a low frequency.     

No evidence for learned mating discrimination in male Drosophila pseudoobscura

Background  

Since females often pay a higher cost for heterospecific matings, mate discrimination and species recognition are driven primarily by female choice. In contrast, frequent indiscriminate matings are hypothesized to maximize male fitness. However, recent studies show that previously indiscriminate males (e.g., Drosophila melanogaster and Poecilia reticulata) can learn to avoid heterospecific courtship. This ability of males to discriminate against heterospecific courtship may be advantageous in populations where two species co-occur if courtship or mating is costly.     

Selection of apoptosis-deficient adenovirus E4orf4 mutants in Saccharomyces cerevisiae

Adenovirus E4orf4 protein has been shown to induce p53-independent, protein phosphatase 2A (PP2A)-dependent apoptosis in transformed cells. Furthermore, E4orf4 also induces toxicity in Saccharomyces cerevisiae in a PP2A-dependent manner (D. Kornitzer and T. Kleinberger, submitted for publication). In this work, we utilized yeast cells to select for nonapoptotic E4orf4 mutants which, in turn, were shown to possess a diminished ability to bind PP2A. The success of this selection system will provide additional apoptosis-relevant mutants for E4orf4 research and strongly supports the relevance of E4orf4-induced toxicity in S. cerevisiae to E4orf4-induced apoptosis in mammalian cells.     

Therapeutic efficacy of differentiated versus undifferentiated mesenchymal stem cells in experimental type I diabetes in rat

Selective MSCs differentiation protocol into pancreatic beta cells was conducted in the present study using exendin-4 and TGF-beta. Differentiated and undifferentiated MSCs were assessed in experimental type I diabetes in rats. Ninety female white albino rats were included in the study and divided equally (n=15/group) into 6 groups: healthy control, healthy control rats received acellular tissue culture medium, diabetic rats, diabetic rats received acellular tissue culture medium, diabetic rats received undifferentiated MSCs and diabetic rats received differentiated MSCs. Therapeutic efficacy of undifferentiated versus differentiated MSCs was evaluated via assessment of quantitative gene expressions of insulin1, insulin 2, Smad-2, Smad-3, PDX-1, PAX-4, neuroD. Blood glucose and insulin hormone levels were also assessed. Results showed that quantitative gene expressions of all studied genes showed significant decrease in diabetic rat groups. Use of undifferentiated and differentiated MSCs led to a significant elevation of expression levels of all genes with more superior effect with differentiated MSCs except smad-2 gene. As regards insulin hormone levels, use of either undifferentiated or differentiated MSCs led to a significant elevation of its levels with more therapeutic effect with differentiated MSCs. Blood glucose levels were significantly decreased with both undifferentiated and differentiated MSCs in comparison to diabetic groups but its levels were normalized 2 months after injection of differentiated MSCs. In conclusion, use of undifferentiated or differentiated MSCs exhibited significant therapeutic potentials in experimental type I diabetes in rats with more significant therapeutic effect with the use of differentiated MSCs.     

A partially histocompatible family of Xenopus borealis

Reciprocal skin allografts were made between siblings of three successive generations in a family of Xenopus borealis and mutually tolerant animals were mated. In the F3 generation of one subfamily, 92% of the siblings were histocompatible.     

Dynamics of limiting cell wall porosity in plant suspension cultures

Changes in the limiting porosity of cell walls, i.e. the size limit for permeation of neutral molecules through the wall, were studied in several higher-plant cell-suspension cultures. For this purpose, samples of biomass fixed at different cultivation times were investigated using a method based on size-exclusion chromatography of polydisperse dextrans before and after equilibration with the extracted cell clusters. In suspension cultures of Chenopodium album L., Dioscorea deltoidea Wall. and Medicago sativa L., the mean size limit (MSL; critical Stokes' radius for exclusion of neutral polymers from half of the intracellular space) was found to vary between 2.4 and 3.8 nm. It decreased significantly during transition from the growth phase to the stationary phase. In the case of the C. album culture this change was found to be irrespective of whether sucrose in the medium was completely depleted at the end of the growth phase or not. The MSL was kept constant for long periods of the stationary phase if cell viability was maintained by repeated sucrose supplement. In a suspension strain of Triticum aestivum L., the MSL of cell wall permeation was comparatively small (1.75 nm) and remained constant during all cultivation phases. Relations between limiting porosity and cell wall growth, loss of pectic compounds to the medium, cross-linking activities and cell wall stiffening are discussed. Received: 19 December 1996 / Accepted: 23 April 1997     

Sensitivity of Rhizobium species to certain fungicides

Summary Thirty-three strains of different species of rhizobia were seeded into medium 79 agar. Discs impregnated with 3, 0.3, 0.03 and 0.003%, corresponding to 10, 1, 1/10 and 1/100 the recommended rate of application, of fungicides TMTD, Rhizoctole, Phygon, Ceresan and Orthocide 75 were placed on the seeded agar. After 120 hrs, zones of inhibition were measured. The 3, 0.3 and 0.03% concentrations of the five fungicides were inhibitory to most rhizobia tested in different degrees. The 0.003% level of these fungicides while toxic to certain strains, was not so for others.Deceased August 6, 1968.