Analysis of the DNA Marker Specific to the Wheat G Genome

A RAPD marker specific for the G genome of wheat was identified. The corresponding 1171-bp DNA sequence was cloned and analyzed. Screening of the database did not reveal any homologies with the known plant DNA sequences. Using the primers specific to the flanking regions of the marker sequence, PCR analysis of the polyploid wheat species and the diploid species of the section Sitopsis was carried out. In addition, using the cloned sequence as a molecular hybridization probe, RFLP analysis of the genomic DNA of these species was performed.     

Mutational specificity and the influence of excision repair: insights into the mechanisms of error-avoidance and error-fixation

The excision repair process controlled by the uvrABC gene in Escherichia coli is the major pathway for the repair of a diverse series of DNA damages. To achieve a better understanding of the mechanics of this repair pathway and its impact upon mutagenesis, we have applied a recently developed technology by which the nature of mutation is determined at the DNA sequence level. A comparison of the classes and distribution of mutation in excision-repair-proficient and excision-repair-deficient strains of E. coli reveals that the absence of excision repair can alter both the nature of the mutations recovered as well as their distribution. This can occur in one of several ways. For example, under some circumstances the action of the UvrABC pathway can lead to interruptions of DNA strand continuity and an enhancement of both frameshift and deletion events. Such an effect is seen following damage by psoralen plus near UV (PUVA) treatment that produces crosslinks in the DNA. In comparison, several other treatments produce similar distributions within the classes of mutations recovered but demonstrate an alteration in site specificity. Such is the case following UV irradiation. In this case, the data indicate that while the premutagenic lesions may be the same, mutation fixation in the presence and absence of excision repair may involve different mechanisms. Similarly, evidence from the repair of damage by ethylating agents indicates that while the nature of the mutations recovered is not altered, the preferred location of these events is altered in the absence of excision repair. These results indicate that local DNA sequence can affect on the efficiency of excision repair.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of live Saccharomyces cerevisiae cells as a biological response modifier in experimental infections

Abstract A short-term oral administration of live Saccharomyces cerevisiae cells, strain Sillix Hansen DSM 1883, resulted in enhanced resistance of mice toward infections with K. pneumoniae, S. pneumoniae and S. pyogenes A produced by intranasal inoculation. Yeast pre-treatment also increased the efficacy of antibiotic therapy in bacterial infections and of antiviral drugs in viral infections. Yeast treatment of animals stimulated phagocytosis, activated the complement system and induced interferon which are likely to represent the main mechanisms of action whereby pretreatment of mice with live S. cerevisiae cells increases resistance to infection. It is concluded that preventive administration of live Saccharomyces cerevisiae cells should be used for increasing resistance to bacterial infections, in particular of the respiratory tract, or to viral infections, as well as an adjunct to antibiotic and antiviral drug therapy.     

A nuclear magnetic resonance study of the glucose metabolism of Hymenolepis diminuta exposed to histamine and serotonin in vitro.

The direct effects of the inflammatory mediators, histamine (HI) and serotonin (SE), on the glucose metabolism of Hymenolepis diminuta in vitro were studied by analyzing the excretory products from culture media, containing D-1-13C-glucose and various concentrations of HI and/or SE, by 1H-nuclear magnetic resonance (n.m.r.) spectroscopy. The results revealed that HI markedly accelerated the glycolysis process by increasing the amount of lactate production. The increased glycolytic activity was reflected in a concentration-dependent increase in glucose uptake. Excretion of acetate was also stimulated by HI. A low concentration of SE significantly increased succinate, acetate and lactate excretions, whereas a high concentration had little effect on lactate production and significantly decreased succinate and acetate excretions. A combination of HI and SE treatment at a low concentration had no significant effect, but at a high concentration showed an additive effect, with an increase in lactate production, a decrease in succinate production and an increase in glucose uptake. Thus this work confirms that HI and SE directly influence, albeit differently, energy metabolism of the tapeworm H. diminuta.     

Surface contact modulation of inflammatory macrophage antibody dependent cytotoxicity and prostanoid release.

Adherence to extracellular matrix proteins modulates the functional and secretory activities of mononuclear phagocytes, although the mechanisms regulating these adherence-dependent changes are poorly understood. In this study, the ability of rat inflammatory peritoneal macrophages (PM) to adhere to an endothelial cell-derived extracellular matrix or a denatured collagen/fibronectin-coated surface and perform antibody dependent cell cytotoxicity (ADCC) and secrete reactive oxygen intermediates was compared with PM adherent to tissue culture plastic. Prostaglandin E2 (PGE2) and thromboxane B2 (TxB2), two major cyclooxygenase products released by inflammatory macrophages, were also measured by PM adherent to the protein coated surfaces. Rat exudate PM were equally adherent to tissue culture plastic or wells coated with either endothelial cell derived matrix or denatured collagen (gelatin)/fibronectin. PM adherent to a denatured collagen/fibronectin-coated wells demonstrated significantly less cytolytic activity (15 +/- 2% lysis) when compared with either tissue culture plastic adherent PM (43 +/- 7% lysis) or PM adherent to extracellular matrix (59 +/- 11% lysis). PM adherent to extracellular matrix released twofold more TxB2 than plastic adherent PM, while PM adherent to denatured collagen/fibronectin released 40% more PGE2 than cells adherent to tissue culture plastic or 80% more PGE2 than PM adherent to the extracellular matrix. PM adherent to denatured collagen/fibronectin release less superoxide anion (27 +/- .9 nmoles/10(6) PM) than PM adherent to either tissue culture plastic (43 +/- 1 nmoles/10(6) PM) or the extracellular matrix (60 +/- 0.5 nmoles/10(6) PM). Furthermore, incubation of plastic adherent PM with exogenous PGE2 reduced superoxide production in a dose-dependent manner. These results demonstrate that the inhibition of ADCC and secretion of reactive oxygen intermediates by PM adherent to a denatured collagen/fibronectin surface correlated with an increased release of the immunosuppressive prostanoid PGE2. Furthermore, the addition of exogenous PGE2 to plastic adherent PM reproduced the depression in ADCC and superoxide anion production observed by PM adherent to a denatured collagen/fibronectin surface. These studies suggest that the increased production and release of PGE2 by inflammatory macrophages adherent to a denatured collagen surface may act to suppress cytotoxic mechanisms and thereby constitutes part of an autocrine feedback mechanism regulating macrophage function during wound injury.