[The roles of the NANA and LEPIDA genes in regulating the stem growth in Arabidopsis thaliana]. / Rol' genov NANA i LEPIDA v reguliatsii rosta steblia Arabidopsis thaliana.

Genetic, physiological, and morphological studies of dwarf mutants of Arabidopsis thaliana (L.) Heynh. from the collection of the Department of Genetics and Breeding, Moscow State University, showed that the NA and LE genes are involved in regulating elongation of internode cells and sensitivity to various hormones. The na mutation suppressed stem growth only in the presence of the active LE gene. The absence of the LE activity (in the lele homozygote) restored stem growth of the na mutant to the level characteristic of the le-2 mutant, and a decrease in LE activity (in LEle heterozygote) almost completely suppressed the na phenotype. Phenotypic analysis of homozygous double mutants and heterozygotes obtained by crossing the na and le-2 mutants showed that the recessive le-2 allele has an epistatic effect on the semidominant na allele and that the genes possibly control consecutive steps of one biochemical pathway or one morphogenetic process. A hypothetical scheme was proposed for the interaction of the NA and LE gene products.

[Nana gene--a regulator of cell division and elongation of stem cells in Arabidopsis thaliana (L.) Heynh]. / Gen nana--reguliator delenii i rastiazhenii kletok steblia Arabidopsis thaliana (L.) Heynh.

The dominant nana (na) mutation localized to the upper arm of Arabidopsis thaliana chromosome 1 blocks cell proliferation in apical meristem (AM) of the flower-bearing stem at its early development and suppresses the subsequent elongation of its internode cells. The na mutation reduces the sensitivity of cells of the flower-bearing stem to gibberellin (GA) and paclobutrazole (PBZ) and prevents resting and immature seeds from restoring the germinating ability in response to exogenous GA. On the other hand, exogenous GA and PBZ affects the onset of flowering, hypocotyl length, and leaf color; i.e., the na mutant displays a distortion of only several, rather than all, GA-dependent processes. Based on the results obtained, the product of the NA gene was assumed to play a role in the negative regulation of GA signaling and to act later than the products of the known GAI and SPY genes.

[Genes controlling inflorescence structure and their possible role in evolution]. / Geny, kontroliruiushchie strukturu cotsvetiia, i ikh vozmozhnaia rol' v c'voliutsii.

Structural features of the shoot system and inflorescence are the most important morphological features, on which plant systematics are based. The present review provides information on the genetic control of shoot morphogenesis in the model plant Arabidopsis thaliana. The results obtained made it possible to reveal a small group of genes responsible for the main taxonomic features of the shoot structure in this species. Cloning of these genes opened new avenues for directed search of homologous genes in other plants. Comparative analysis of the shoot structure and studies of the function and expression of these genes in various plants suggest that morphological evolution may be based on changes in the pattern of expression of single regulatory genes.

[Epidemiologic significance of detecting shigellae during examination of a healthy population]. / K voprosu ob épidemiologicheskoi znachimosti vyiavleniia shigell pri obsledovanii zdorovogoo naseleniia.

The authors present the results of examination of the healthy population for shigellae carrier state. The efficacy of detection of shigellae depending on the season of the year and indications to the examination was compared. Analysis of the data obtained indicated that any examination for shigellae during the extraepidemic period was inexpedient. This conclusion was confirmed by the results of selective examination with the use of bacteriological and serological methods.