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Biomedical subjects

A Atanassov

Publications and source records attributed to A Atanassov.

At least 19 recordsLinked to original sources
PubMed2006

Improved phytoaccumulation of cadmium by genetically modified tobacco plants (Nicotiana tabacum L.). Physiological and biochemical response of the transformants to cadmium toxicity.

The response of tobacco plants (Nicotiana tabacum L.)--non-transformed and transformed with a metallothionein gene MThis from Silene vulgaris L.--to increase cadmium supply in the nutrient solution was compared. The transgenic plants accumulated significantly more Cd both in the roots and the leaves. Visual toxicity symptoms and disturbance in water balance were correlated with Cd tissue content. Treatment with 300 microM CdCl(2) resulted in inhibition of photosynthesis and mobilization of the ascorbate-glutathione cycle. Treatment with 500 microM CdCl(2) led to irreversible damage of photosynthesis and oxidative stress. An appearance of a new peroxidase isoform and changes in the leaf polypeptide pattern were observed at the highest Cd concentration. The level of non-protein thiols gradually increased following the Cd treatment both in transgenic and non-transformed plants.

Antioxidants↗
PubMed2006

Multiple origins of cultivated grapevine (Vitis vinifera L. ssp. sativa) based on chloroplast DNA polymorphisms.

The domestication of the Eurasian grape (Vitis vinifera ssp. sativa) from its wild ancestor (Vitis vinifera ssp. sylvestris) has long been claimed to have occurred in Transcaucasia where its greatest genetic diversity is found and where very early archaeological evidence, including grape pips and artefacts of a 'wine culture', have been excavated. Whether from Transcaucasia or the nearby Taurus or Zagros Mountains, it is hypothesized that this wine culture spread southwards and eventually westwards around the Mediterranean basin, together with the transplantation of cultivated grape cuttings. However, the existence of morphological differentiation between cultivars from eastern and western ends of the modern distribution of the Eurasian grape suggests the existence of different genetic contribution from local sylvestris populations or multilocal selection and domestication of sylvestris genotypes. To tackle this issue, we analysed chlorotype variation and distribution in 1201 samples of sylvestris and sativa genotypes from the whole area of the species' distribution and studied their genetic relationships. The results suggest the existence of at least two important origins for the cultivated germplasm, one in the Near East and another in the western Mediterranean region, the latter of which gave rise to many of the current Western European cultivars. Indeed, over 70% of the Iberian Peninsula cultivars display chlorotypes that are only compatible with their having derived from western sylvestris populations.

DNA, Chloroplast↗
PubMed2005

Microsatellite analysis of Rosa damascena Mill. accessions reveals genetic similarity between genotypes used for rose oil production and old Damask rose varieties.

Damask roses are grown in several European and Asiatic countries for rose oil production. Twenty-six oil-bearing Rosa damascena Mill. accessions and 13 garden Damask roses were assayed by molecular markers. Microsatellite genotyping demonstrated that R. damascena Mill. accessions from Bulgaria, Iran, and India and old European Damask rose varieties possess identical microsatellite profiles, suggesting a common origin. At the same time, the data indicated that modern industrial oil rose cultivation is based on a very narrow genepool and that oil rose collections contain many genetically identical accessions. The study of long-term vegetative propagation of the Damask roses also reveals high somatic stability for the microsatellite loci analyzed.

Cluster Analysis↗
PubMed2005

Chlorsulfuron resistant transgenic tobacco as a tool for broomrape control.

Broomrape (Orobanche ramosa L.) is the most important parasitic plant that infests tobacco (Nicotiana tabacum L.). Chemical treatment of the soil is not effective and crop rotation is not acceptable to solve this problem because of the long viability period of Orobanche seeds in the soil. Application of systemic herbicides in the field with herbicide resistant tobacco could be a successful tool for broomrape control. Several tobacco cultivars were transformed with a mutant ahas3R gene for resistance to the herbicide chlorsulfuron (Glean, DuPont). Transformed plants were selfed and the segregation of resistance was followed in the next generation. The efficiency of the herbicide was demonstrated in greenhouse and field trials. An Orobanche/tobacco growth system was used in order to prove the lethal effect of the herbicide to the attached broomrape plants.

Agrobacterium tumefaciens↗
PubMed2001

Assessment of polysomaty, embryo formation and regeneration in liquid media for various species of diploid annual Medicago.

To avoid polyploidy in regenerants the source of explant material should be monosomatic. Therefore, the leaf and petiole tissue of five diploid Medicago species (Medicago ciliaris, Medicago murex, Medicago orbicularis, Medicago polymorpha and Medicago truncatula cv. Jemalong, and the ecotype R108-1) was assessed for polysomaty by flow cytometry. For the species studied the frequency of 2C nuclei was about 90% in leaves compared with that in petioles. Embryos were readily formed from tissue of leaves in liquid media containing 1 mg l(-1) or 4 mg l(-1) dichlorophenoxyacetic acid (2,4-D). For embryo development two procedures were tested - prolonged use of induction medium and treatment with polyethylene glycol Mw 6000 (PEG). The highly regenerable genotypes M. truncatula cv. Jemalong and R108-1 showed efficient conversion of embryos after maturation in liquid medium. The regenerated plants were diploid and with normal phenotype.

Journal Article↗
PubMed2001

Variability of the N-protein and the intergenic region of the S RNA of tomato spotted wilt tospovirus (TSWV).

The genetic heterogeneity of the N protein gene and the intergenic region (IGR) of the S RNA from tomato spotted wilt virus (TSWV) isolates, collected in Bulgaria, were compared with isolates from other parts of the world. The results substantiated the highly conserved nature of the N protein. Twenty six independent sequences revealed only seven variable amino acid positions, common to all isolates. The type of amino acids present in these positions seems to be independent of the geographical origin. In contrast to the structural N protein, comparisons of the related IGR-sequences led to clusters correlated with the geographical origin of the isolates. Although the overall sequence homology in the IGRs was much lower than for the N proteins, three conserved parts within this region were identified. The outstanding part was a central area of 31 nucleotides with a significantly increased GC-content. This was located in both viral- and viral-complement RNA at structures with similar foldings, which led to the assumption that this stabilised structure, rather than a sequence motive, might serve as a transcription terminator during the synthesis of the two mRNAs from the ambisense segments.

Amino Acid Sequence↗
PubMed2000

New members of a cold-responsive group-3 Lea/Rab-related Cor gene family from common wheat (Triticum aestivum L.).

A Cor (cold-responsive) cDNA that belongs to the group-3 Lea (late embryogenesis abundant)/Rab (responsive to abscisic acid, ABA) family was isolated from a winter-hardy cultivar of common wheat (Triticum aestivum L.). Screening of a cold-acclimated cDNA library was performed using an ABA- and other stress-responsive barley cDNA clone, Hva1, as a probe. A wheat cDNA clone (designated as Wrab19) putatively encoded a basic (pI = 10.3) and hydrophobic protein with 179 amino acids. The deduced protein showed characteristics of the group-3 LEA/RAB protein family. In contrast to the single copy barley Hva1, Wrab19 belonged to a multigene family in the hexaploid wheat genome and six loci were assigned to the homoeologous group 1 chromosomes. Using Wrab19 as a probe, four homologous cDNAs (designated as Wrab17) were isolated that encoded acidic (pI = 4.6-4.7) and hydrophobic proteins, all with 166 amino acids. The deduced proteins showed high homology (a mean of 84% identity) with a barley gibberellic acid (GA3)-inducible protein, ES2A, and several other group-3 LEA/RAB proteins. Wrab17 was considered to be a three-copy gene and each copy was assigned to chromosome 5A, 4B or 4D of hexaploid wheat. Transcripts of both Wrab19 and Wrab17 accumulated within 1 day of cold acclimation at 4 degrees C. They were responsive to ABA and/or GA3, but showed some cultivar differences in their response to these plant hormones. We conclude that the two genes are new members of the group-3 Lea/Rab-related Cor gene family in wheat.

Abscisic Acid↗
PubMed2000

A cold-responsive wheat (Triticum aestivum L.) gene wcor14 identified in a winter-hardy cultivar 'Mironovska 808'.

A cDNA library was constructed from a cold-acclimated winter-hardy common wheat (Triticum aestivum L.) cultivar 'Mironovska 808'. Using this library and a cold- and light-responsive barley cDNA clone cor14b as a probe, cDNAs of a homologous wheat gene wcor14 were isolated. Two identical cDNAs designated as wcor14a had an open reading frame encoding an acidic (pI = 4.71) and hydrophobic polypeptide with 140 amino acids (MW = 13.5 kDa). The deduced WCOR14a polypeptide showed 70% identity with the barley chloroplast-imported COR14b and had a nearly identical N-terminal, putative chloroplast transit peptide of 51 amino acid residues. Another cDNA clone wcor14b was assumed to encode a polypeptide WCORb which had 5 substitutions and a frame shift in the C-terminal region as compared with WCOR14a. RACE PCR, genomic PCR and Southern blot analyses suggested that wcor14 and its related sequences constitute a small multigene family with and without an intron in the hexaploid wheat genome. Northern blot analysis showed that transcripts of wcor14 accumulated within 3-6 hours of cold acclimation at 4 degrees C and the level reached a maximum at day 3. The transcripts became non-detectable within 3 hours after de-acclimation at room temperature. Contrary to the barley cor14b, a similar level of wcor14 transcripts was detected under the continuous darkness. Neither treatment with NaCl, ABA nor dehydration induced its expression. Based on these results we conclude that wcor14 is a wheat orthologue of the barley cor14b and specifically induced by low temperature.

Amino Acid Sequence↗
PubMed1998

Expression of an anther-specific chalcone synthase-like gene is correlated with uninucleate microspore development in Nicotiana sylvestris.

Two cDNA clones, specifically expressed in Nicotiana sylvestris anthers during uninucleate microspore development, were isolated using a subtractive hybridization approach. Sequence analysis showed that one of them, NSCHSLK, displayed a high level of similarity to several anther-specific chalcone synthase-like (CHSLK) proteins and an ORF from chromosome I of Arabidopsis thaliana. A lower, but significant, similarity to chalcone synthases and closely related enzymes (CHSRE) was also detected. The structure of the nschslk gene was found to be typical of the chalcone (chs)/stilbene (sts) synthase family. Expression of NSCHSLK mRNA was confined to microspores and tapetal cells. UV-irradiation or infection with Phytophthora parasitica var. nicotianae of transgenic Nicotiana benthamiana plants carrying a chimeric nschslk/GUS gene indicated that the nschslk promoter exhibits the same anther-specific, developmentally regulated expression pattern. Comparison of CHSRE and CHSLK polypeptide sequences revealed some important similarities and differences between the two groups. The data presented in this study, suggest that the anther-specific chslk genes represent a separate sub-family of plant polyketide synthases related to chs/sts in terms of gene structure, polypeptide sequence and the possible catalytic mechanism, but differing in substrate/product specificity. The putative role of CHSLK enzymes in anther development and particularly in exine synthesis is discussed.

Acyltransferases↗
PubMed1998

Arthrosonography in the evaluation of osteoarticular and soft-tissue structures in rheumatology.

BACKGROUND: Real-time ultrasonography is a widely available, reliable, diagnostically sensitive and specific noninvasive modality which allows measuring of the thickness of different anatomical landmarks which form joints, of the periarticular soft tissue and connective tissue structures, of their echogenicity and the amount of joint effusion. The present study was designed to assess the clinical and diagnostic applicability of high-frequency ultrasonography in rheumatology. METHODS: We used SONOACE 1500 (Medison Europe GmbH) with a 7.5 MHz transducer. RESULTS: We demonstrate the most characteristic ultrasonographic patterns which have diagnostic significance in the seven most common rheumatologic disorders. DISCUSSION: The pathological ultrasonographic patterns of the joints, periarticular and soft-tissue structures in rheumatologic disorders we present give an insight into the clinical applicability of arthrosonography and its inherent advantages over the conventional radiological examination--namely, ultrasonography is noninvasive, uses no radiation, which allows reproducibility and follow-up, widely available and relatively inexpensive and as such can be performed at bedside or on an outpatient basis.

Adolescent↗
PubMed1995

Blood gases, electrolytes and metabolic monitoring in children with acute failure of vital functions.

The priority of direct monitoring of blood gases in Paediatric Intensive Care Units (PICU) increased substantially after introduction of the Deep Picture method and Oxygen Status Algorithm (OSA) (1) into medical practice. We used the advantages of these methods as a prerequisite for a more detailed and deeper analysis of the blood oxygen profile (2, 3). The aims of the present paper were: 1. To illustrate the applicability of the capacity coefficients beta 1.0, beta 2.3, beta 5-4 of the transported oxygen and the "Useful Ratio" (UR) index of the haemoglobin oxygen, previously described by us, and the benefit derived from differentiation of the states of hyperoxia, normoxia and hypoxia; hyperoxaemia, normoxaemia and hypoxaemia on the Blood Oxygen Binding Curve (BOBC) in critically ill newborns, infants and children. 2. To expand the diagnostic capacity of the Blood Gas Map (BGM) used with the OSA in children and to supplement the arterial oxygen diagnostics with new indices that reflect the relationship between oxygen uptake and oxygen transported in the body. 3. To share our experience in PICU related to the acid-base-electrolytes relationship and to the possibility of assessing the reno-hepatic regulation according to the changes of the acid-base status in critically ill children.

Acid-Base Equilibrium↗
PubMed1994

Characterisation and expression of the mitochondrial genome of a new type of cytoplasmic male-sterile sunflower.

A new cytoplasmic male sterile sunflower, CMS3 [44], was characterised in relation to the Petiolaris (PET1) cytoplasmic male-sterile sunflower, CMS89 [25]. Southern blot analysis showed that the mitochondrial genome of CMS3 contains unique rearrangements in at least five loci (atp6, atp9, atpA, nad1 + 5 and coxIII) compared to the PET1 sterile and the fertile cytoplasms. Transcripts of two (coxIII and atp6) of the five rearranged loci differed in CMS3 when compared to the corresponding loci in the PET1 and fertile cytoplasms. In organello protein synthesis experiments showed that the ca. 15 kDa mitochondrial polypeptide, characteristic of PET1, is not present in the CMS3 line. These data suggest that the molecular basis of male sterility in the CMS3 line differs from that of the PET1 cytoplasm. The nucleotide sequences of the coding and the immediate flanking regions of the coxIII and atp6 genes of CMS3 were compared to the corresponding regions from the fertile sunflower. In CMS3 the ORFB-coxIII locus is located immediately 3' to the atpA gene whereas in the fertile cytoplasm these two loci are ca. 60 kb apart. This DNA rearrangement probably involved a 265 bp repeat which may be implicated in the DNA recombination associated with PET1 CMS. The atp6 gene in CMS3 contains a 5'-terminal extention which results in an extended ORF. The potential involvement of the rearrangements associated with the coxIII and atp6 loci in relation to the CMS phenotype is discussed.

Amino Acid Sequence↗
PubMed1992

Molecular analysis of a new cytoplasmic male sterile genotype in sunflower.

Mitochondrial DNA from 1 fertile and 6 cytoplasmic male sterile (CMS) sunflower genotypes was studied. The CMS genotypes had been obtained either by specific crosses between different Helianthus species or by mutagenesis. CMS-associated restriction fragment length polymorphisms (RFLPs) were found in the vicinity of the atpA locus, generated by various restriction enzymes. The organization of the mitochondrial genes 26S rRNA, 18S + 5S rRNA and coxII was investigated by Southern blot analysis. These genes have similar structures in fertile and all studied sterile sources. Using the atpA probe, 5 from the 6 investigated CMS genotypes showed identical hybridization patterns to the Petiolaris CMS line, which is used in all commercial sunflower hybrids. Only 1 cytoplasm derived from an open pollination of Helianthus annuus ssp. texanus, known as ANT1, contained a unique mitochondrial DNA fragment, which is distinguishable from the fertile and sterile Petiolaris genotypes and from all investigated CMS genotypes. Male fertility restoration and male sterility maintenance of the ANT1 line are different from the Petiolaris CMS system, which is a confirmation that a novel CMS genotype in sunflower has been identified.

Blotting, Southern↗
PubMed1980

[Physiological reactions in catharsis].

By employing catharsis as a psychotherapeutic method after Krestnikoff, respiration, pulse rate, blood pressure, body temperature, sweat secretion and urinary constituents were studied in groups of different numbers of patients. While the values of respiration, pulse rate and sweat secretion were found to be subject to a pronounced influence, blood pressure and body temperature were relatively stable. Urinalysis showed in many cases an increase in excretion with a decrease in the specific weight and a change from the acid to a slightly alkaline milieu.

Abreaction↗