System of innate immunity in plants

The review deals with the mechanisms of innate immunity in plants focusing on families of pattern-recognition receptors and incorporates recent data on complete sequencing of several plant genomes. Plant immune response involves several families of receptors, both membrane-bound and cytoplasmic ones, containing conservative leucine-rich repeats. The lack of adaptive immunity and the associated rearrangements in the immune receptor genes in plants is partly counterbalanced by genetically encoded mechanisms of specific immunity to particular pathogens. There is a certain similarity between intracellular signal transduction and effector mechanisms in plant and animal innate immune systems, although the latter are considerably more complex.     

Intracellular mechanisms of the formation of homo- and heteropolymeric isozymes. I. Kinetics of the formation of the heteropolymeric isozyme of malate dehydrogenase in parasexual hybrids of two Acetabularia species

The isozyme pattern of malate dehydrogenase (MDH) of Acetabularia crenulata and A. mediterranea is characterized by heterogeneity in different regions of the cytoplasm of both algae, as well as by species specificity. The formation of the heteropolymeric MDH isozyme is restricted to a definite region of the cytoplasm of heterokaryons and nuclear-cytoplasmic A.crenulata-A.mediteranea hybrids at different stages of their development. The data obtained suggest that the concentrations of the free subunits of MDH, coded for by homologous genes, are unevenly distributed in the cytoplasm of hybrid cells. The heteropolymeric MDH isozyme in these cells is presumably the result of the de novo synthesis of isozyme subunits. This seems plausible inasmuch as no exchange occurs between the homopolymeric MDH isozymes of both parental types in the cytoplasm. The formation of the heteropolymeric MDH isozyme is tentatively related to the spatial compartmentalization of the mRNAs of homologous genes coding for the MDH subunits.     

Clonal analysis of the development of the pigment epithelium of the eye in chimeric or/or----AKR mice

The development of cell clones was studied in the retinal pigment epithelium of chimaeric mice or/or----AKR. The clonal analysis suggests that on the 13th day of gestation the cells in the retinal pigment epithelium are distributed almost randomly while in the adults they are grouped in small coherent clones. In the retinal pigment epithelium the AKR cell predominated over the or/or cells. The interaction of mutant and normal clones during the eye development leads, in most cases, to the normalization of eyes in chimaeras. Cases of microphthalmia and asymmetry in distribution of clones suggest irregular and random distribution of these clones in the embryo.