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T A Ezhova

Publications and source records attributed to T A Ezhova.

At least 19 recordsLinked to original sources
PubMed2005

[Effect of the ABRUPTUS/PINOID gene on expression of the LEAFY gene in Arabidopsis thaliana].

The nucleotide sequence was analyzed for the temperature-sensitive allele abruptus (abr), which distorts polar auxin transport (PAT) in the floral shoot. The mutation C-->T was found in the second exon and led to an amino acid substitution (glycin-->glutamic acid) in the conserved domain of protein kinase encoded by the ABRUPTUS/PINOID (ABR/PID) gene. RT--PCR revealed a 100-fold decrease in transcription of the LEAFY (LFY) gene in the abr mutant with high expressiveness of the mutant character; transcription of the fused LFY::GUS gene was also low in the mutant. The results agree with data of the phenotypic analysis of the abr lfy double mutant and testify to an important role of auxin gradients in regulating expression of the LFY gene.

Amino Acid Substitution↗
PubMed2005

[Gene TAENIATA is a novel negative regulator of the Arabidopsis thaliana homeobox genes KNAT1, KNAT2, KNAT6, and STM].

Mutant Arabidopsis thaliana taeniata (tae) plants are characterized by an altered morphology of leaves and the inflorescence. At the beginning of flowering, the inflorescence produces fertile flowers morphologically intermediate between a shoot and a flower. The recessive mutation tae also causes the formation of ectopic meristems and shoot rosettes on leaves. The expressivity of the mutant characters depend on the temperature and photoperiod. Analysis of the activity of KNOX class I genes in the leaves of the tae mutant has demonstrated the expression of genes KNAT2 and STM and an increase in the expression of genes KNAT1 and KNAT6 compared to wild-type leaves. These data indicate that the TAE gene negatively regulates the KNAT1, KNAT2, KNAT6, and STM genes.

Arabidopsis↗
PubMed2004

[The roles of the NANA and LEPIDA genes in regulating the stem growth in 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.

Arabidopsis↗
PubMed2002

[Nana gene--a regulator of cell division and elongation of stem cells in 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.

Arabidopsis↗
PubMed2001

[A novel gene Bractea (bra) controls the formation of an indeterminate bractless inflorescence in Arabidopsis thaliana].

The morphological and genetic studies of the bra mutant of Arabidopsis thaliana (L.) Heynh. from the collection of the Department of Genetics and Breeding, Moscow State University, showed that the BRA gene controls the main stages of inflorescence development: it suppresses the development of leaflike organs subtending flowers (bracts) and inhibits the formation of the terminal flower. Inactivation of the BRA gene leads to the transition from the indeterminate bractless inflorescence characteristic of the family Cruciferaceae to the determinate bracteose inflorescence. The BRA gene plays a regulatory role and was probably involved in the conversion of the bracteose determinate inflorescence to the bractless indeterminate inflorescence during the origin of ancestral crucifers.

Arabidopsis↗
PubMed2000

[Interaction of ABRUPTUS/PINOID and LEAFY genes during floral morphogenesis in Arabidopsis thaliana (L.) Heynh].

Analysis of interactions between mutations abruptus and leafy and previous data on interaction of abruptus with homeotic mutations apetala1, apetala2, and apetala3 showed that the functions of the ABRUPTUS/PINOID (ABR/PID) gene are as follows: (1) it directs pattern formation in inflorescence axis specifying the development either of floral meristem (FM) or of cauline leaves; (2) in concert with the leafy gene, it participates in the formation of FM; (3) it is involved in the determination and the formation of floral organ primordia in the first, second, and third whorls. Auxin accumulation in the abr mutant cells in callus culture was shown indicating the involvement of the ABR/PID gene in regulation of auxin efflux from cells. It is suggested that the ABR/PID expression in the sites of formation of FM and floral organs leads to local reduction in auxin level, which in turn, enhances expression of the LFY and homeotic genes responsible for FM formation and differentiation.

Arabidopsis↗
PubMed1999

[Arabidopsis thaliana (L.) Heynh. as a model object for studying genetic control of morphogenesis].

A vast amount of information on the genetic control of plant development has been obtained in Arabidopsis thaliana with classical genetic and molecular biological methods. The genes involved in multistep regulation of floral morphogenesis have been identified. The formation of floral meristem is controlled by the LEAFY (LFY), UNUSUAL FLORAL ORGANS (UFO), APETALA1 (AP1), and APETALA2 (AP2) genes. Studies of the abruptus and bractea recessive monogenic mutants from the collection of the Department of Genetics and Selection, Moscow State University, showed that the ABRUPTUS (ABR) and BRACTEA (BRA) genes also play an important role in inflorescence differentiation. The ABR gene controls the early formation of organ primordia on the inflorescence and the formation of floral organ primordia after floral initiation. Further differentiation of inflorescence organ primordia in vegetative or generative organs depends on the activity of the LFY gene, and floral organ identity is determined by the homeotic genes. Presumably, the major function of the ABR gene is to determine the auxin polar transport. The BRA gene suppresses the development of bracts on the inflorescence and constrains cell division at the base of primordia of rosette and cauline leaves.

Arabidopsis↗
PubMedDate not supplied

[The enzymatic activity of the antioxidant system in the ontogeny of mutant norflurazone-tolerant Arabidopsis thaliana].

The activities of superoxide dismutase and guaiacol-dependent peroxidase were studied in the ontogenesis of recessive homozygous mutants of Arabidopsis thaliana Heynh. le-2 and nfz24, which are characterized by two- to threefold increases in tolerance to the herbicide norflurazone. The mutants le-2 and nfz24 differed from the initial race Dijon in some phenotypic features, duration of ontogenetic stages, and dynamics of the superoxide dismutase and peroxidase activities in ontogenesis. A single treatment of plants with norflurazone induced an accelerated increase in the level of both enzymes in the mutants as compared to the wild type plants. Under the conditions of multiple treatment with norflurazone, the mutants le-2 and nfz24 displayed a higher tolerance to the bleaching effect of the herbicide and were characterized by a higher level of superoxide dismutase. The data obtained suggest that the superoxide dismutase and peroxidase activities are controlled by both ontogenetic factors and stress signals. Mutations in the lines le-2 and nfz24 increase sensitivity to a stress signal or increase efficiency of an adaptive response due to long-term maintenance of a high level of the antioxidant enzymes under the conditions of stress.

Arabidopsis↗
PubMedDate not supplied

[Distribution of lethal haemosporidoses pathogens in poultry].

Peculiarities of geographical distribution and distribution among hosts of the haemosporidian parasites, which cause lethal diseases in poultry, are specified. So far, 11 species of such parasites have been described. This represents about 5% of bird haemosporidian parasites. The haemosporidians cause the lethal epizooties in turkeys, chickens, ducks, geese, pigeons and domesticated ostriches. One species of parasites belongs to the family Haemoproteidae, six--to Plasmodiidae, and four--to Leucocytozoidae. The agents of lethal haemosporidioses have been recorded in domestic birds of the orders Galliformes, Anseriformes, Columbiformes and Struthiorniformes. The majority of these parasites (eight species of 73%) occurs in the galliform birds. Each other order obtaines only one species of parasites. Five species parasitize turkey, which is the main host of the agent of lethal haemosporidioses. The majority of highly virulent haemosporidian species have been recorded throughout a global territory, which includes the Holarctic, Ethiopian and Oriental zoogeorgaphical regions. Three species of these parasites have been found in the Neotropical region, while none species has been recorded in Australia. The majority of highly virulent haemosporidian species have quite clear outlined areas, that is important to know for the prophilactic purposes including the quarantine of bird introducing from endemic territories.

Animals↗
PubMedDate not supplied

[High prevalence and diversity of blood parasites of passerine birds in Southern Turkmenistan].

Thirty nine specimens of passerine birds belonging to 19 species and eight families were investigated by blood smear technique in four localities of Southern Turkmenistan in 3-18 August 1991. The overall prevalence of infection was 59%. Protists from the orders Haemosporida (genera Haemoproteus, Plasmodium, Leucocytozoon), Kinetoplastida (Trypanosoma), and Adeleida (Hepatozoon), as well as Microfilaria were found. Haemoproteids (the prevalence of infection is 44%), leucocytozoids (23%), malarial parasites (13%) and trypanosomes (13%) were most frequently recorded. Only low chronic infections (< 1% of infected cells for the great majority of intracellular parasites, and a few trypanosomes and Microfilaria in each blood smear) were seen. Haemoproteus belopolskyi, H. balmorali, H. dolniki, H. magnus, H. minutus, H. fringillae, H. majoris, Leucocytozoon dubreuili, and Trypanosoma avium were recorded for the first time in Turkmenistan. The former five above-mentioned species of haemoproteids are new records for the fauna of Middle Asia. Gametocytes of leucocytozoids in fusiform host cells were found for the first time in passerine birds in the Holarctic. The host is Parus bokharensis. Due to the wide distribution and the opportunity to collect a large parasitological material using harmless for hosts methods, bird haemosporidian parasites can be used as convenient models for ecological and evolutionary biology studies in South Turkmenistan. The heavily infected Orphean Warbler Sylvia hortensis is an especially convenient host for such purposes.

Animals↗
PubMedDate not supplied

[Genes controlling inflorescence structure and their possible role in evolution].

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.

Biological Evolution↗
PubMedDate not supplied

[The principles of data formalization for building the genetic-morphological model of shoot development in flowering plants].

Shoot system of a plant can be divided into elementary molecules composed of phyllome, internode, and meristem of the lateral bud. The capacity of plants for open growth is manifested as multiple reproductions of the modules. These main principles of plant structural organization can be used to formalize and integrate the data from various disciplines studying the shoot development--genetics of development, morphology, etc. At the example of model species Arabidopsis thaliana we show that the data on genetic control of shoot development can be considered in terms of individual modules reorganization. Several variants of the modules structural reorganization are allowed: reduction or transformation of phyllome, change in the internode length, and triggering active/inactive status of the lateral shoot meristem. Each variant of the module structure corresponds to specific pattern of genes activity. Such integration of the data on genetic and structural aspects of morphogenesis can form a basis for mathematical modeling of plant development.

Arabidopsis↗
PubMedDate not supplied

[PXD gene controls synthesis of the three anionic peroxidase isoforms in Arabidopsis thaliana].

The pxd mutant of Arabidopsis thaliana had a changed spectrum of anionic peroxidases: three anionic isoforms in the pxd mutant plant had the same enzymatic activity but relatively high electrophoretic mobility as compared to the analogous isoforms in the wild type plants. These isoforms were the most active anionic peroxidases and could be found in most plant organs. Genetic analysis showed that all three isoforms were controlled by the PXD gene. The activity of one isoform was affected by indolyl-3-acetic acid and other stress factors. Expressed sequence tags (EST) analysis of all putative peroxidase genes of A. thaliana revealed the group of the most actively and nonspecifically expressed genes. The promoter sequences of these genes were screened to find the cis-elements. We propose that the PXD gene encodes one of the nonspecific anionic peroxidases or a protein involved in posttranscriptional or posttranslational modification of the peroxidases.

Anions↗
PubMedDate not supplied

[Genetic control of totipotency of plant cells in vitro].

The main approaches have been considered to studying the genetic control of plant cell totipotency in an in vitro culture. The capacity of cultured plants for callusogenesis, organ formation, and somatic embryogenesis depends on the activity of genes that determine and maintain the meristematic state of cells, level of hormones in the cells, and sensitivity to hormones, as well as on the activity other genes that control different stages of plant morphogenesis.

Arabidopsis↗
PubMedDate not supplied

[Basic principles of terminal flower formation].

Studies of efflorescences of the mutants bractea and terminal flower1 and double mutant bra tfl1 of Arabidoipsis thaliana (L.) Heynh. have shown that the presence of a developed leaf in the node preceding the terminal flower is a necessary condition for the formation of the terminal flower perianth. This means that perianth cannot develop in an abracteose efflorescence of terminal flower. The second necessary condition for the terminal flower formation is a sufficient level of expression of the genes responsible for floral morphogenesis. Combination of these two conditions suffices for the development of a terminal flower with perianth. Since the general principles of organization are close for most flower plants, it can be stated that if the abracteose efflorescence is terminated by a flower with perianth, this is a consequence of forcing the lateral flower into the terminal position.

Arabidopsis↗
PubMedDate not supplied

[Collection of Arabidopsis thaliana mutants with altered sensitivity to oxidative stress inductors].

Selective systems for screening Arabidopsis thaliana (L.) Heynh. mutants with altered sensitivity to the oxidative stress (OS) inductors norflurazon (NF), acifluorfen (AF), and plumbagin (PB) were developed and a collection of 28 mutants was obtained. Dwarf and necrotic forms predominated among the NF-tolerant mutants, while pigment mutants and those with changed root morphology prevailed among the AF-tolerant and PB-sensitive mutants, respectively. Genetic and biochemical analysis of certain mutants was performed; quantitative and qualitative changes in the content of superoxide dismutase and peroxidase isoforms have been revealed. These data, complemented by the data on the cross-tolerance (sensitivity) of the mutants to paraquat, indicate a correlation between tolerance to the OS inductors and the functions of antioxidant systems.

Arabidopsis↗