[Secretion of Phenolic Compounds into Root Exudates of Pea Seedlings upon Inoculation with Rhizobium leguminosarum bv. viceae or Pseudomonas siringae pv. Pisi].

The content of apigenin, naringenin, pisatin, dibutyl-ortho-phthalate, and N-phenyl-2-naphthyl-amine were assayed in root exudates of pea (Pisum sativum L.) seedlings one day after their inoculation with Rhizobium leguminosarum, bv. viceae or Pseudomonas siringae pv. pisi, which represent, respectively, mutualistic and antagonistic strategies of interaction with a host plant. After inoculation with either bacteria, the concentrations of apigenin and pisatin in the root exudates were equal, whereas the concentrations of naringenin and N-phenyl-2-naphthylamine were different and those of dibutyl-o-phthalate were unchanged. A certain role is suggested for the phenolic compounds in an accomplishment of symbiotic relations of bacteria with a host plant.

[The NADPH oxidase activity of pea seedling roots in rhizobial infection depending on abiotic and biotic factors].

The changes in NADPH activity was studied in the roots of 3-4-day-old etiolated pea (cultivar Aksaiskii usatyi) seedlings depending on plant inoculation with Rhizobium leguminosarum bv. viceae (strain CIAM 1026), adverse environmental factors (low temperature and high dose of a mineral nitrogen fertilizer), chemical substances (sodium nitroprusside and methyl viologen, or paraquat), and a biotic factor--the bacterium Escherichia coli (strain XL-1 Blue). It was demonstrated that all exogenous factors increased the activity of microsomal NADPH oxidase. Rhizobial infection removed the activation caused by exogenous factors only in the case of high nitrogen content in the medium, thereby displaying an antagonistic effect. A synergistic action on the enzyme activity was observed in the variants with combined action of rhizobia + paraquat and rhizobia + E. coli. An increased NADPH oxidase activity coincided with a growth inhibition of pea seedling roots. The results are discussed from the standpoint of the roles of NADPH oxidase and reactive oxygen species in the legume-rhizobium symbiosis.

[Reactive oxygen and nitrogen species in legume-rhizobial symbiosis: a review].

Published data on the role of reactive oxygen and nitrogen species (ROS and RNS, respectively) in the formation and functioning of the legume-rhizobial symbiosis are summarized. It is assumed that ROS and RNS fulfill a double function in the legume-rhizobial symbiosis by triggering the mechanisms enabling symbiosis formation and the mechanisms preventing the development of symbiotic structures (i.e., the defensive responses). A hypothetic scheme illustrating the involvement of ROS and RNS in the formation of legume-rhizobial symbiosis is proposed.

[The influence of mineral nitrogen on legume-rhizobium symbiosis].

A literature review synthesizes the data on physiological mechanisms of the influence of high doses of mineral nitrogen (nitrates and ammonium) on the formation and functioning of legume-rhizobium symbiosis. The participation of phytohormonal and phenolic metabolism and active forms of oxygen and nitrogen in the symbiosis is highlighted. Close connection between these metabolic processes in the formation and functioning of legume-rhizobium symbiosis under a redundant supply of plants by mineral nitrogen is underlined.

[Effect of nitric oxide and other nitrogen compounds on the adhesion and penetration of nodule bacteria into root tissues and on growth of etiolated pea seedlings].

The action of sodium nitroprusside, a nitric oxide donor, and other nitrogen compounds (KNO3, KNO2, and (NH4)2SO4) on adhesion and penetration of nodule bacteria into root tissues of etiolated pea seedlings was studied. Only nitroprusside displayed a clearly negative effect on rhizobium adhesion and penetration and seedling growth. This effect was not observed with other nitrogen compounds even at high (20 mM) concentrations. Hemoglobin attenuated the negative effect of nitroprusside on bacteria and seedlings. The results are discussed in the context of the role of nitric oxide in the life of plants and nodule bacteria.

[Oxidation processes at initial stages of interaction of root nodule bacteria (Rhizobium leguminosarum) and pea (Pisum sativum L.): a review].

A possible physiological mechanism of legume-Rhizobium symbiosis, consisting in regulation of the intensity of oxidation processes by the microsymbiont in response to infection with Rhizobium, was analyzed using our own and published data. The results used in the analysis included data on the content of reactive oxygen species (O2*-, and H2O2), activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase), and intensity of lipid peroxidation proceeding with the involvement of lipophilic phenolic compounds of the microsymbiont.

[The defense and regulatory mechanisms during development of legume-Rhizobium symbiosis].

The roles of indolylacetic acid, the peroxidase system, catalase, active oxygen species, and phenolic compounds in the physiological and biochemical mechanisms involved in the autoregulation of nodulation in the developing legume-Rhizobium symbiosis were studied. It was inferred that the concentration of indolylacetic acid in the roots of inoculated plants, controlled by the enzymes of the peroxidase complex, is the signal permitting or limiting nodulation at the initial stages of symbiotic interaction. Presumably, the change in the level of active oxygen species is determined by an antioxidant activity of phenolic compounds. During the development of symbiosis, phytohormones, antioxidant enzymes, and active oxygen species may be involved in the regulation of infection via both a direct antibacterial action and regulation of functional activity of the host plant defense systems.

[Active oxygen species in pea seedlings during the interactions with symbiotic and pathogenic microorganisms].

The level of active oxygen species (AOS)--superoxide anion radical (O2*-) and hydrogen peroxide (H2O2)--in pea (Pisum sativum L.) cultivar Marat seedlings was studied upon their inoculation with symbiotic (Rhizobium leguminosarum bv. viceae strain CIAM 1026) and pathogenic (Pseudomonas syringae pv. pisi Sackett) microorganisms. Different patterns of the changes in AOS in pea seedlings during the interactions with the symbiont and the phytopathogen were recorded. It is assumed that O2*- and H2O2 are involved in the defense and regulatory mechanisms of the host plant.

[Hydrogen peroxide content and catalase activity at inoculation with root tubercle bacteria of pea seedlings with the various nodulation ability].

Hydrogen peroxide (H2O2) content and catalase activity were studied in pea (Pisum sativum L.) seedlings with normal (cultivar Marat) and disrupted (pea mutants) process of nodulation, which were inoculated with the nitrogen-fixing bacterium Rhizobium leguminosarum strain CIAM 1026. Differences in hydrogen peroxide content and catalase activity in pea seedlings with different ability for nodulation, which were inoculated with rhizobia, were found. It was assumed that H2O2 and catalase are involved in defensive and regulatory mechanisms in the host plant.

[Possible involvement of hydrogen peroxide and salicylic acid in the legume-rhizobium symbiosis].

H2O2 content was studied in the roots and epicotyls of pea (Pisum sativum L.) with normal (cultivar Marat) and disturbed (non-nodulating mutant K14 and hypernodulating mutant Nod3) regulation of root nodulation after inoculation with active industrial strain of Rhizobium leguminosarum by. viceae 250a/CIAM 1026. Pea biotypes differed by H2O2 content in the roots and epicotyls. Exogenous salicylic acid (SA) (0.2 mM) affected H2O2 and SA contents in the roots in an inoculation-dependent manner. The involvement of hydrogen peroxide and SA as signaling molecules as well as of antibacterial agents in the pea-rhizobium interaction at the initial stages of symbiosis is proposed.

[The interrelationship of cytomegalovirus infection and immunodeficiencies]. / O vzaimootnoshenii tsitomegalovirusnoi infektsii i immunodefitsitov.

The results of examination of 87 children who died from a generalized cytomegalovirus infection in Elista (66 cases) in 1984-1985, 1988-89, and in Leningrad (21 cases) in 1988-89 are available. In the Elista material a considerable increase (from 21 to 66%) of severe forms of accidental transformation of thymus is observed in the second period comparing to the first one. The causes of a serious worsening of the immunological background remain unclear. Cytomegaly represented 3.85% of all dead children in the pathology department of the First Children Hospital of Leningrad. There was sialadenitis in 4 cases and generalized infection with involvement of the lungs, liver, kidneys, brain, myocardium, pancreas, adrenals in 17 cases. Cytomegaly was diagnosed in 3 of 5 cases of primary immunodeficiency. Diagnosis in some cases was confirmed by the DNA cytomegalovirus detection by means of PCR reaction.

[AIDS in children based on autopsy data from the Kalmyk ASSR]. / SPID u detei po sektsionnym materialam Kalmytskoi ASSR.

6 cases of HIV infection were revealed by enzyme immunoassay and immunoblotting among 144 children who had died in Elista. Another 5 children might have had HIV-infection but laboratory analyses either were lacking or gave doubtful results. Laboratory results were negative in 133 children. Similar severe changes of the lymphoid system typical for immunodeficiency were found in all children. These changes in HIV infection were characterized by lymphogenic generalized RNA infection. Complications (secondary diseases) in the form of DNA-virus infections (cytomegalia and herpes simplex), pneumocystosis and other viral and bacterial processes were observed in children of all groups. The disease was found mainly in Kalmyks. Blood examination of healthy Kalmyks revealed some differences in the form of significant decrease of the lysosomal cationic proteins content and the peroxydase activity of neutrophil leucocytes as compared to the same indexes obtained in Leningrad. There was also a tendency to the decrease of T-lymphocyte content. The children dying from immunodeficiencies lived mainly along the litoral of an ancient sea.