Parasexuality in Race 65 Colletotrichum lindemuthianum Isolates

ABSTRACT. Heterokaryosis is the initial step of the parasexual cycle, a process that provides genetic variability in filamentous fungi through the production of heterozygous diploid nuclei. To characterize the parasexual cycle in Colletotrichum lindemuthianum, we evaluated the presence of heterokaryosis, vegetative compatibility reactions, and diploid formation among isolates of Race 65 collected from different Brazilian states. Vegetative compatibility groups were identified among the isolates according to their ability to form heterokaryons. Two heterozygous diploids were selected from compatible heterokaryons, which were characterized by the segregation of the parental auxotrophic markers and by RAPD profiles.     

L-citrulline supplementation reverses the impaired airway relaxation in neonatal rats exposed to hyperoxia

Background

Hyperoxia is shown to impair airway relaxation via limiting L-arginine bioavailability to nitric oxide synthase (NOS) and reducing NO production as a consequence. L-arginine can also be synthesized by L-citrulline recycling. The role of L-citrulline supplementation was investigated in the reversing of hyperoxia-induced impaired relaxation of rat tracheal smooth muscle (TSM).

Methods

Electrical field stimulation (EFS, 2–20 V)-induced relaxation was measured under in vitro conditions in preconstricted tracheal preparations obtained from 12 day old rat pups exposed to room air or hyperoxia (>95% oxygen) for 7 days supplemented with L-citrulline or saline (in vitro or in vivo). The role of the L-citrulline/L-arginine cycle under basal conditions was studied by incubation of preparations in the presence of argininosuccinate synthase (ASS) inhibitor [α-methyl-D, L-aspartate, 1 mM] or argininosuccinate lyase inhibitor (ASL) succinate (1 mM) and/or NOS inhibitor [N^ω-nitro-L-arginine methyl ester; 100 μM] with respect to the presence or absence of L-citrulline (2 mM).

Results

Hyperoxia impaired the EFS-induced relaxation of TSM as compared to room air control (p < 0.001; 0.5 ± 0.1% at 2 V to 50.6 ± 5.7% at 20 V in hyperoxic group: 0.7 ± 0.2 at 2 V to 80.0 ± 5.6% at 20 V in room air group). Inhibition of ASS or ASL, and L-citrulline supplementation did not affect relaxation responses under basal conditions. However, inhibition of NOS significantly reduced relaxation responses (p < 0.001), which were restored to control level by L-citrulline. L-citrulline supplementation in vivo and in vitro also reversed the hyperoxia-impaired relaxation. The differences were significant (p <0.001; 0.8 ± 0.3% at 2 V to 47.1 ± 4.1% at 20 V without L-citrulline; 0.9 ± 0.3% at 2 V to 68.2 ± 4.8% at 20 V with L-citrulline). Inhibition of ASS or ASL prevented this effect of L-citrulline.

Conclusion

The results indicate the presence of an L-citrulline/L-arginine cycle in the airways of rat pups. L-citrulline recycling does not play a major role under basal conditions in airways, but it has an important role under conditions of substrate limitations to NOS as a source of L-arginine, and L-citrulline supplementation reverses the impaired relaxation of airways under hyperoxic conditions.     

The action of interferon and reaferon on the functional activity of human thrombocytes

The functional activity of thrombocytes (aggregation, endo- and exocytosis) and erythrocytes (aggregation) in healthy persons given a course of interferon or reaferon treatment has been studied. The results obtained in this study indicate that these preparations produce a modulating effect on the functions of thrombocytes and erythrocytes of donors having shown abnormal functional activity of these blood cells prior to the course of treatment.     

Effect of chemical action on the biological activity of staphylococcal allergen

The authors present the results of study of chemical action on the specific properties of staphylococcus allergen showing that deamination, iodation, and formalinization was accompanied by reduction of the allergenic capacity of the preparation; as to acetylation -- it produced an insignificant reduction of the allergen activity.     

Formation of microfilament bundles in the tumor cell interphase nuclei of a rat neurinoma exposed to dimethyl sulfoxide

The action of 15% dimethyl sulfoxide (DMSO) on the ultrastructure of the rat neurinoma cells (line NGUK-I) has been studied. The agent induced the formation of microfilament bundles in interphase nuclei after 30-60 min of treatment. The microfilament bundles revealed are suggested to be actin.