A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Karyological features of barley callus tissues culturedin vitro

Long-term callus cultures of two barley cultivars have been investigated at the cellular level. One slowly growing, root forming callus of the barley cv. Bulgarische Nackte consists of cells the majority of which contain the diploid chromosome number. Contrarily, a fast growing callus of the cv. Elgina having no regeneration potency at all, is highly polyploid and includes more than two thirds of aneuploid cells. Tn this callus strain, a great number of multinucleate cells has been found. Some problems are discussed with respect to the relationships between growth rate, karyological stability and regeneration capacity in long-term callus cultures of cereals.     

The microtubule skeleton cycle in the higher plant cell division

Five major mictotubule arrays characteristic of cell cycle in the higher plants were noticed: cortical coils, preprophase band, radial array, division spindle, and phragmoplast. The organization of mocrotubules into ordered arrays; their dynamics and function during plant cell division are discussed in this review.     

Extreme cytokinesis phenomenon in the phenotype of meiotic mutation pam of Zea mays

Our study of cytological phenotype of meiotic mutation pam resulted in detecting a failure of cytokinesis in mutant pollen mother cells in the form of a block of fusion of membrane vesicles of the cell plate, and an impossibility of formation of daughter cell membranes. The mutation does not disturb the division spindle structure and function. Asynchrony of meiosis in pam is the result of arrest of pollen mother cells at metaphase 1 and metaphase 2.     

Interzonal microtubules and meiotic restitution in the dycots

Dynamics of the microtubule cytoskeleton at mobile stages of female meiosis in the dycots was studied. A new stage of MT rearrangement was revealed referred to as centrifugal movement of interzone MTs at telophase 1. A disruption of this process leads to the displacement of daughter nuclei to the equatorial region and a common (fused) spindle formation. This is the cause of dyad (instead of tetrads) formation in mutant ps of Beta vulgaris.     

Genetic modulation of PPARgamma phosphorylation regulates insulin sensitivity

Obesity-associated diabetes is epidemic in industrialized societies. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) is highly expressed in adipose tissue and the presumed molecular target for antidiabetic thiazolidinedione drugs that reverse insulin resistance but also promote weight gain. Phosphorylation reduces the activity of PPARgamma in vitro, but physiological relevance has not been demonstrated. We have studied mice homozygous for a mutation (S112A) that prevents PPARgamma phosphorylation. Surprisingly, the weights and adipose mass of PPARgamma-S112A mice are not greater than wild-type. Remarkably, however, genetic prevention of PPARgamma phosphorylation preserves insulin sensitivity in the setting of diet-induced obesity. Underlying this protection are smaller fat cells, elevated serum adiponectin, and reduced free fatty acid levels. Thus, the phosphorylation state of PPARgamma modulates insulin sensitivity. Compounds that prevent PPARgamma phosphorylation or ligands that induce the conformation of nonphosphorylated PPARgamma may selectively enhance insulin sensitivity without increasing body weight.     

Dynamics of cytoskeleton microtubules in higher plant meiosis. III. Early prometaphase stage

The early prometaphase and initial stages of meiotic spindle formation in higher plant PMCs were studied by means of a new approach worked out by the authors: a morphological dissection that consists in the analysis of various abnormalities of the process under study. Wide cereal hybrids F1 were used as a source of such abnormalities: phenotypes with C-, S-shaped and combined spindle, with spindles surrounded by microtubule (MT) ring and phenotypes with chaotic circular MT system in M1. Three stages of early prometaphase not described before (disintegration of perinuclear MT band, straightening of its bundles, and their translocation throughout the cytoplasm) were revealed.     

Dynamics of cytoskeleton microtubules in higher plant meiosis. I. The perinuclear band of microtubules and the meiotic spindle formation

A planar meridional perinuclear band of microtubules was observed at the late meiotic prophase I in a range of higher plant species. A distinct high-organized structure and a long time of existence allow to consider it as a new class of MTs dependent on the cell cycle in plant meiosis. MTs of the perinuclear band convert into meiotic spindle through a complex process of spatial rearrangements.     

Disruption of male meiosis in the pea Pisum sativum L., caused by ms3 mutation

Analysis of morphological phenotype of meimutation ms3 in Pisum sativum was made at the light microscopic level with vizualization of MT cytoskeletal structures. This mutation disrupts simultaneously the chromosome cycle, nuclear envelope breakdown, and MT cytoskeleton cycle during meiosis in pollen mother cells.     

Chaotization of division spindle, phragmoplast, and telophase chromosome groups in wheat x wheatgrass F1 hybrids meiosis

The paper describes the phenomenon of disorganization of completely formed subcellular structures: division spindle, phragmoplast and chromosome telophase groups. These structures disintegrate into their elements (cytoskeletal fibers, chromosomes) that transform into chaotic system. Chaotization of cytoskeleton structures such as prophase spindle in mitosis or perinuclear ring in meiosis is a normal step of wild type plant cell division. Disintegration of division spindle and phragmoplast presumably indicate the abnormality of temporal regulation of cytoskeleton cycle during meiosis. Disintegration of telophase chromosome groups and the migration of the chromosomes backward to the equatorial area might mean the abnormal start of some prometaphase mechanisms, in particular, chromokinesins activation.