Regulatory genes of garden pea (Pisum sativum L.) controlling the development of nitrogen-fixing nodules and arbuscular mycorrhiza: a review of basic and applied aspects

The review sums up the long experience of the authors and other researchers in studying the genetic system of garden pea (Pisum sativum L.), which controls sthe development of nitrogen-fixing symbiosis and arbuscular mycorrhiza. A justified phenotypic classification of pea mutants is presented. Progress in identifying and cloning symbiotic genes is adequately reflected. The feasibility of using double inoculation as a means of increasing the plant productivity is demonstrated, in which the potential of a tripartite symbiotic system (pea plants-root nodule bacteria-arbuscular mycorrhiza) is mobilized.     

Genomic organization and chromosomal localization of three members of the UDP-N-acetylgalactosamine: polypeptide N- acetylgalactosaminyltransferase family

A homologous family of UDP- N -acetylgalactosamine: polypeptide N - acetylgalactosaminyltransferases (GalNAc-transferases) initiate O- glycosylation. These transferases share overall amino acid sequence similarities of approximately 45-50%, but segments with higher similarities of approximately 80% are found in the putative catalytic domain. Here we have characterized the genomic organization of the coding regions of three GalNAc-transferase genes and determined their chromosomal localization. The coding regions of GALNT1 , -T2 , and -T3 were found to span 11, 16, and 10 exons, respectively. Several intron/exon boundaries were conserved within the three genes. One conserved boundary was shared in a homologous C. elegans GalNAc- transferase gene. Fluorescence in situ hybridization showed that GALNT1 , -T2 , and -T3 are localized at chromosomes 18q12-q21, 1q41-q42, and 2q24-q31, respectively. These results suggest that the members of the polypeptide GalNAc-transferase family diverged early in evolution from a common ancestral gene through gene duplication.      

Endothelial cell junctions

In the course of a freeze-cleave study on intercellular junctions in the regenerating rat liver, we observed an unusual array of intramembranous particles located in regions of contact between endothelial cells lining the hepatic sinusoids. These arrays were characterized by an accumulation of particles which resembled a zonula occludens in their linear deployment but differed in that the contact regions were composed of individual particles which remained separated from each other by regular particle-free intervals.     

HIV-particles in spermatozoa of patients with AIDS and their transfer into the oocyte

By immunocytochemistry and in situ hybridization at the electron microscopy level, and by the PCR technique, we have shown that HIV-1 binds and enters normal sperm; that viral particles, their antigens, and nucleic acid are present in sperm from HIV-1 infected men; and that such sperm can transfer HIV-1 like particles to normal human oocytes. We also present evidence that a galactosylceramide-like compound is present on the sperm membrane and could function as an alternative receptor for HIV.     

Modelling of myocardial hypertrophy in vitro for solving problems of medicinal correction

The work has been done on primary heart culture from neonatal rat ventricle. Cardiomyocyte hypertrophy was modelled using noradrenaline (NA), angiotensin II (AII) and fetal serum, respectively. Cell hypertrophy of primary heart cultures was assessed by measuring the surface area, the scope of protein synthesis estimated by 3H-leucine autoradiography and the contents of nucleic acids in gallocyanin-chromalum stained cardiomyocytes. The structure of myofibrillar apparatus was studied by rhodamine-conjugated phalloidin and indirect immunofluorescence of muscle alpha-actinin. Treatment with 10(-6) M NA increased 3H-leucine incorporation in 9-day old heart culture by 42% without changing cell size. AII in a dose 1 microM stimulated protein synthesis activity by 1.3 fold and the surface area by 1.7 fold, both in 2- and 9-day old primary heart cultures. The maximum stimulation of cell hypertrophy was provided by the medium supplemented with fetal serum. RNA contents in the cytoplasm of cardiomyocytes increased by 7.8 fold and the myocardial cell size by 2.9 fold in serum-supplemented culture by 9 days of cultivation. In the medium with fetal serum, amounts of cardiomyocytes with tetraploid nuclei reached 33%, against 14% in control. Coculturing of myocardiocytes and fibroblasts rendered effects of fetal serum on the growth of myocardiocytes. Cultivation in the presence of 1 microM enalapril, an ACE inhibitor, suppressed the development of cardiac muscle cells hypertrophy. The effect of enalapril depended on the degree of cellular hypertrophy. Addition of 10 microM amiloride to the medium lowered the protein synthesis by 29% independently on the initial cellular hypertrophy.     

Regulation of nodulin gene expression

The expression of plant genes specifically induced during rhizobial infection and the early stages of nodule ontogeny (early nodulin genes) and those induced in the mature, nitrogen-fixing nodule (late nodulin genes) is differentially regulated and tissue/cell specific. We have been interested in the signal transduction pathway responsible for symbiotic, temporal and spatial control of expression of an early (Enod2) and a late (Leghemoglobin;lb) nodulin gene from the stem-nodulated legumeSesbania rostrata, and in identifying thecis-acting elements andtrans-acting factors involved in this process (De Bruijn and Schell, 1992). By introducing chimericS. rostrata lb promoter-gus reporter gene fusions into transgenicLotus corniculatus plants, we have been able to show that thelb promoter directs an infected-cell-specific expression pattern inLotus nodules. We have been able to delimit thecis-acting element responsible for nodule-infected-cell-expression to a 78 pb region of thelb promoter (NICE Element) and have analyzed this element in detail by site-specific mutagenesis. We have studied the interaction of the NICE element, and further upstreamcis-acting elements, withtrans-acting factors of both plant- and rhizobial origin. We have obtained evidence for the involvement of rhizobial proteins in infected-cell-specific plant gene expression (Welters et al., 1993). We have purified one of the bacterial binding proteins from theS. rostrata symbiontAzorhizobium caulinodans (AcBBP1), and cloned and mutated the corresponding gene, in order to examine its symbiotic phenotype. We have also found that theS. rostrata Enod2 gene is rapidly induced by physiologically significant concentrations of cytokinins, suggesting the role of cytokinin as a potential secondary signal involved in nodulation (Dehio and De Bruijn, 1992). We are examining whether the observed cytokinin induction, as well as the nodule-specific expression pattern, are modulated by theSrEnod2 promoter.     

Features of formation of phases of dual-phase polymeric system in the presence of collagen I, laminin I, and their mixtures

A study was made of the phase formation kinetics of a two-phase aqueous polymer system, consisting of 7.8% (w/w) dextran-500 and 4.6% (w/w) polyethylene glycol-6000, in the presence of various concentrations of collagen (0.07-0.20 mg/ml), laminin I (0.01-0.03 mg/ml) and their mixture. The phase formation was evaluated by registration of its optical density on a spectrophotometer. The obtained two-phase polymer system optical density curves and also the partitioning coefficients for the studied objects depend on surface properties of these objects. It has been shown that the surface properties of collagen I and laminin I differ according to differences in their molecules conformations, and that the phase formation kinetics points to their interaction during a mutual partitioning of these proteins in the system. The authors made a conclusion that collagen I and laminin I in the two-phase polymer system conditions could make complexes.