Relationship between the virulence of a culture and the presence of common (non-type-specific) antigens in strains of group A streptococcus of different types]

In studying common (nontypespecific) antigens sensitivity to trypsin there was shown their wide distribution among the cultures of streptococcus, group A, belonging to different types and containing M-proteins. The antigen No. 1, identical to one of the antigens of the thermostable fraction was found in the cultures, irrespective of the degree of their virulence. The antigen No. 2 was characteristic of only virulent cultures obtained after the increase of the virulence and forming matt-form colonies. Both of the antigens were referred to the category of R-antigens. The presence of the nonspecific antigens in the hydrochloric extracts should be taken into consideration in typing streptococci of group A and determination of M-antigens.     

Evidence for Symbiont-induced Alteration of a Host's Gene Expression: Irreversible Loss of SAM Synthetase from Amoeba proteus

ABSTRACT. Symbiont-bearing xD amoebae no longer produce a 45-kDa cytoplasmic protein that functions as S-adenosylmethionine synthetase in symbiont-free D amoebae. The absence of the protein in xD amoebae is attributable to xD amoeba's failure to transcribe the corresponding gene as a result of harboring bacterial symbionts. However, xD amoebae have about half the level of enzyme activity found in D amoebae, indicating that they use an alternative source for the enzyme. xD amoebae originated from D amoebae by bacterial infection and now depend on their symbionts for survival. xD amoebae exhibit irreversible nucleolar abnormalities when their symbionts are removed, suggesting that X-bacteria supply the needed enzyme. A monoclonal antibody against the 45-kDa protein was produced and used as a probe in cloning its corresponding cDNA. The product of the cDNA was found to have S-adenosylmethionine synthetase activity. These results show how symbiotic X-bacteria may become essential cellular components of amoebae by supplementing a genetic defect for an amoeba's house-keeping gene that is brought about by an action of X-bacteria themselves. This is the first reported example in which symbionts alter the host's gene expression to block the production of an essential protein.     

Role of Glutamate and GABA in Mechanisms Underlying Respiratory Control

This review deals with modern concepts on the mechanisms of involvement of main central excitatory and inhibitory neurotransmitters, glutamate and GABA, in the control of the respiratory function.     

Effect of palmitate on energy coupling in lymphocyte mitochondria

In the presence of 0.1 micrograms/ml of oligomycin, DNP (40-60 microM) increases lymphocyte respiration 10-fold and more. Palmitate taken at the same concentration stimulates the respiration of isolated mitochondria (1-2 mg prot/ml) in the presence of 1 mg/ml of BSA and the respiration of lymphocytes (10(8) cells/ml). When BSA and EGTA are absent in mitochondria isolation media, the mitochondrial respiration does not increase after DNP or ADP addition. Lymphocyte preparations are mostly distinguished by mitochondrial morphology in the presence of the uncoupler; they differ less by changes in dis-C3-(5) fluorescence after addition of 5-10 microM DNP and only insignificantly by the stimulation of respiration by DNP and palmitate. These results may be explained by the increase in the uncoupler-induced permeability of mitochondria for K+ and by partial transformation of delta psi m into delta pH in some cells, which may increase the cell resistance to damaging influences.     

Stereological analysis of the ultrastructural organization of the cardiomyocytes in the red-cheeked suslik in different seasons of the year

The myocardium of red-cheeked sousliks was studied at different seasons with the use of stereological analysis. The volume and surface densities of the myofibrils, mitochondria, T system, sarcoplasmic reticulum as well as the surface-volume ratios of the main organelles were measured. Pronounced seasonal changes in physiological activity of the heterothermal animals were accompanied by marked reorganization of the spatial ultrastructure of the cardiomyocytes. The seasonal regression of the heart weight and diminution of the cardiomyocyte diameter were recorded during hibernation. The authors believe that the increased volume ratio of the cytoplasmic organelles to the myofibrils forms the basis for a rapid adaptive reaction of the heart during hibernation and waking up.     

Liver engraftment potential of hepatic cells derived from patient-specific induced pluripotent stem cells

Human induced pluripotent stem cells (iPSCs) are potential renewable sources of hepatocytes for drug development and cell therapy. Differentiation of human iPSCs into different developmental stages of hepatic cells has been achieved and improved during the last several years. We have recently demonstrated the liver engraftment and regenerative capabilities of human iPSC-derived multistage hepatic cells in vivo. Here we describe the in vitro and in vivo activities of hepatic cells derived from patient specific iPSCs, including multiple lines established from either inherited or acquired liver diseases, and discuss basic and clinical applications of these cells for disease modeling, drug screening and discovery, gene therapy and cell replacement therapy.     

Drosophila SUUR protein associates with PCNA and binds chromatin in a cell cycle-dependent manner

Drosophila SUUR (Suppressor of UnderReplication) protein was shown to regulate the DNA replication elongation process in endocycling cells. This protein is also known to be the component of silent chromatin in polyploid and diploid cells. To mark the different cell cycle stages, we used immunostaining patterns of PCNA, the main structural component of replication fork. We demonstrate that SUUR chromatin binding is dynamic throughout the endocyle in Drosophila salivary glands. We observed that SUUR chromosomal localization changed along with PCNA pattern and these proteins largely co-localized during the late S-phase in salivary glands. The hypothesized interaction between SUUR and PCNA was confirmed by co-immunoprecipitation from embryonic nuclear extracts. Our findings support the idea that the effect of SUUR on replication elongation depends on the cell cycle stage and can be mediated through its physical interaction with replication fork.     

Nipah Virus Entry and Egress from Polarized Epithelial Cells

Highly pathogenic Nipah virus (NiV) infections are transmitted via airway secretions and urine, commonly via the respiratory route. Epithelial surfaces represent important replication sites in both primary and systemic infection phases. NiV entry and spread from polarized epithelial cells therefore determine virus entry and dissemination within a new host and influence virus shedding via mucosal surfaces in the respiratory and urinary tract. To date, there is no knowledge regarding the entry and exit sites of NiV in polarized epithelial cells. In this report, we show for the first time that NiV can infect polarized kidney epithelial cells (MDCK) from both cell surfaces, while virus release is primarily restricted to the apical plasma membrane. Substantial amounts of basolateral infectivity were detected only after infection with high virus doses, at time points when the integrity of the cell monolayer was largely disrupted as a result of cell-to-cell fusion. Confocal immunofluorescence analyses of envelope protein distribution at early and late infection stages suggested that apical virus budding is determined by the polarized sorting of the NiV matrix protein, M. Studies with stably M-expressing and with monensin-treated cells furthermore demonstrated that M protein transport is independent from the glycoproteins, implying that the M protein possesses an intrinsic apical targeting signal.     

Microorganisms form exocellular structures, trophosomes, to facilitate biodegradation of oil in aqueous media

Cytochemical staining and microscopy were used to study the trophic structures and cellular morphotypes that are produced during the colonization of oil-water interfaces by oil-degrading yeasts and bacteria. Among the microorganisms studied here, the yeasts (Schwanniomyces occidentalis, Torulopsis candida, Candida tropicalis, Candida lipolytica, Candida maltosa, Candida paralipolytica) and two representative bacteria (Rhodococcus sp. and Pseudomonas putida) produced exocellular structures composed of biopolymers during growth on petroleum hydrocarbons. Four of the yeasts including S. occidentalis, T. candida, C. tropicalis and C. maltosa excreted polymers through modified sites in their cell wall ('canals'), whereas C. lipolytica and C. paralipolytica and the two bacterial species secreted polymers over the entire cell surface. These polymers took the form of fibrils and films that clogged pores and cavities on the surfaces of the oil droplets. A three-dimensional reconstruction of the cavities using serial thin sections showed that the exopolymer films isolated the ambient aqueous medium together with microbial cells and oil to form both closed and open granules that contained pools of oxidative enzymes utilized for the degradation of the oil hydrocarbons. The formation of such granules, or 'trophosomes,' appears to be a fundamental process that facilitates the efficient degradation of oil in aqueous media.