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At least 451 records · Page 25Linked to original sources
PubMed1996

[Genetic features of the Brown Carpathian breed--a vanishing local breed of cattle in the Western Ukraine].

A wide range of variation in immunogenetic and biochemical markers was found in thoroughbred Brown Carpathian cattle. Comparative analysis of genetic structure of Brown Carpathian and Swiss cattle, as well as various hybrids of these two breeds, with respect to polymorphic biochemical systems, demonstrated that all hybrids having any gene admixture of the Brown Carpathian breed formed a single cluster in a dendrogram and were readily distinguishable from thoroughbred Swiss cattle. Originally, the Swiss breed participated in forming the gene pool of Brown Carpathian cattle. The selective advantage of some gene associations, which included the loci of the biochemical genetic systems studied, was suggested to be a specific characteristic of the Brown Carpathian breed. Genetic differentiation in the groups of hybrids bred in regions with different ecological conditions (high- and lowland) was revealed.

Animals↗
PubMed1996

Cloning and expression of full-length delta-endotoxin cryIA(c) gene in three kinds of prokaryotic systems using shuttle vector pHT3101.

Two fragments, 6.5kb and 4.3kb encoding 5' end and 3' end of delta-endotoxin cryIA(c) gene, respectively, were selected from the Bacillus thuringiensis kurstaki-HD-73 75kb plasmid gene pool using random primer labelling delta-endotoxin cryIA(b) gene probe. The full-length 3.92kb cryIA(c) gene including 5' end 152 bp promoter sequence and 3' end 198 bp terminater sequence was rebuilt after uncoding sequences were deleted. Three kinds of engineering strains harbouring the same recombinant plasmid pHTY1 were obtained after the cryIA(c) gene had been subcloned in shuttle vector pHT3101 and transformed to E. coli NM522, Bacillus subtilis AS1176 and Bacillus thuringiensis crystal-deficient 4D10(H3ab). SDS-PAGE electrophoresis patterns reveal that the cryIA(c) gene expressed the same 133,300 protoxin proteins in all three host systems with the same molecular weight to the crystal protein from the Bacillus thuringiensis kurstaki HD-73. Immuno-assays indicate that the expression proteins can react with antiserum of HD-73 paraspore crystal protein in the same pattern as the natural crystalprotein. Bioassays using crude expressed products from three host strains reveal that they all showed toxicities to second instar larvae of Plutella xylostella, and their LD50 were calculated to be 0.311 micrograms/cm2, 0.02 micrograms/cm2 and 0.017 micrograms/cm2, respectively.

Bacillus subtilis↗
PubMed2006

Development of simple sequence repeat markers specific for the Lr34 resistance region of wheat using sequence information from rice and Aegilops tauschii.

Hexaploid wheat (Triticum aestivum L.) originated about 8,000 years ago from the hybridization of tetraploid wheat with diploid Aegilops tauschii Coss. containing the D-genome. Thus, the bread wheat D-genome is evolutionary young and shows a low degree of polymorphism in the bread wheat gene pool. To increase marker density around the durable leaf rust resistance gene Lr34 located on chromosome 7DS, we used molecular information from the orthologous region in rice. Wheat expressed sequence tags (wESTs) were identified by homology with the rice genes in the interval of interest, but were monomorphic in the 'Arina' x 'Forno' mapping population. To derive new polymorphic markers, bacterial artificial chromosome (BAC) clones representing a total physical size of approximately 1 Mb and belonging to four contigs were isolated from Ae. tauschii by hybridization screening with wheat ESTs. Several BAC clones were low-pass sequenced, resulting in a total of approximately 560 kb of sequence. Ten microsatellite sequences were found, and three of them were polymorphic in our population and were genetically mapped close to Lr34. Comparative analysis of marker order revealed a large inversion between the rice genome and the wheat D-genome. The SWM10 microsatellite is closely linked to Lr34 and has the same allele in the three independent sources of Lr34: 'Frontana', 'Chinese Spring', and 'Forno', as well in most of the genotypes containing Lr34. Therefore, SWM10 is a highly useful marker to assist selection for Lr34 in breeding programs worldwide.

Alleles↗
PubMed2003

Sexual variation in bucco-lingual dimensions in Turkish dentition.

Sexual differences in the human skeleton have been well studied in many populations. Odontometric analysis of the human sexual variation has been less investigated and mostly derived from the dentition of extinct populations. Turkey is situated in a unique location where populations from different regions mixed with each other and created a rich gene pool. One might anticipate that modern Turkish population is composed of genes from the Balkans, Caucasus, Middle East, Iran and further as well as from ancient Romans, Byzantines, Arabs and Asiatic Turks. It is clear that contemporary Turks are a mixture of these extant and extinct people and ideal to consider it a representative study population. The purpose of this study is to analyze dental dimensions and sexual variation in living Turks and develop forensic techniques to identify human remains from the teeth when any other technique is not available or not reliable. The study is composed of Ankara University dental students (50 male and 50 female casts, average age of 21 years). Bucco-lingual breadths from 14 teeth (I1 through M2 of the maxilla and mandible) are taken from the left side and analyzed using the discriminant function statistics. An intraobserver error test did not indicate any statistically significant difference between any two measurements. Results of the study revealed that males exceeded females significantly (P<0.001) in dimensions. Coefficient of variation was most obvious in I1s and I2s of both jaws in both sexes. Stepwise discriminant function statistics suggested that upper C, and lower C and M2 are the most contributory teeth to the function. Additional formulae were calculated for situation in which only one or a fragmented jaw is available for identification. Overall accuracy of sex diagnosis ranged from 73 to 77%. In conclusion this research supports earlier studies that sexual dimorphism is population specific. While dental difference between the sexes in several human populations has been found highly dimorphic, it was not found so in Turks and accuracy of classification remained low at about 77%. The difficulty or the lack of dimorphism comes from male subjects.

Adult↗
PubMed2024

Interspecific transfer of genetic information through polyploid bridges.

Hybridization blurs species boundaries and leads to intertwined lineages resulting in reticulate evolution. Polyploidy, the outcome of whole genome duplication (WGD), has more recently been implicated in promoting and facilitating hybridization between polyploid species, potentially leading to adaptive introgression. However, because polyploid lineages are usually ephemeral states in the evolutionary history of life it is unclear whether WGD-potentiated hybridization has any appreciable effect on their diploid counterparts. Here, we develop a model of cytotype dynamics within mixed-ploidy populations to demonstrate that polyploidy can in fact serve as a bridge for gene flow between diploid lineages, where introgression is fully or partially hampered by the species barrier. Polyploid bridges emerge in the presence of triploid organisms, which despite critically low levels of fitness, can still allow the transfer of alleles between diploid states of independently evolving mixed-ploidy species. Notably, while marked genetic divergence prevents polyploid-mediated interspecific gene flow, we show that increased recombination rates can offset these evolutionary constraints, allowing a more efficient sorting of alleles at higher-ploidy levels before introgression into diploid gene pools. Additionally, we derive an analytical approximation for the rate of gene flow at the tetraploid level necessary to supersede introgression between diploids with nonzero introgression rates, which is especially relevant for plant species complexes, where interspecific gene flow is ubiquitous. Altogether, our results illustrate the potential impact of polyploid bridges on the (re)distribution of genetic material across ecological communities during evolution, representing a potential force behind reticulation.

Polyploidy↗
PubMed1986

T-cell receptor variable region gene usage in T-cell populations.

We have examined T-cell receptor alpha- and beta-chain variable (V) region gene usage in T-cell populations predicted to have different major histocompatibility complex-restriction specificities. Using a sensitive ribonuclease protection assay to measure T-cell receptor mRNA levels, we found no striking differences in the usage of three V alpha genes and three V beta genes in T-cell populations from three congeneic H-2-disparate strains of mice and between the mutually exclusive Ly2+ L3T4- and Ly2- L3T4+ T-cell subpopulations. These results suggest that major histocompatibility complex restriction cannot be explained by the differential usage of nonoverlapping V alpha or V beta gene pools. In contrast, striking but unpredictable differences were seen in V gene usage in populations of T cells selected by activation with particular alloantigens.

Animals↗
PubMed1985

Identical twins with the Rhnull phenotype of the regulator type in a Finnish Lapp family.

An inbred family A. G. with identical twin sisters having the Rhnull phenotype of the regulator type as confirmed by the maternal family data of Rh inheritance is reported. The family was traced back through church records for six generations. Several connections could be established with a Norwegian Sea Lapp community in which a family with the amorph Rhnull type has been reported. The closeness of the Finnish and the Norwegian Lapps was given special attention since, despite both of the communities are small and share a more or less common gene pool, they nevertheless seem to possess the two ultra rare Rh genes, Xor in the Finnish and r in the Norwegian family, producing, when homozygous, the Rhnull phenotype.

Adult↗
PubMed2000

Production of inbred progenies of diploid potatoes using an S-locus inhibitor (Sli) gene, and their characterization.

To develop inbred lines from self-incompatible, cultivated diploid potatoes, an S-locus inhibitor (Sli) gene derived from a self-compatible variant of a wild potato species, Solanum chacoense, was incorporated into various cultivated diploid potatoes. The progeny was selfed twice by the action of the Sli gene to obtain 74 S2 inbred clones belonging to 8 families. More than 40% of them were either non-flowering or pollen sterile. Among the pollen fertile clones, self-compatible clones occurred with a much lower frequency (20.9%) than expected (83.3%). The result demonstrated that self-compatibility was introduced and expressed in the gene pool of cultivated diploid potatoes by an action of the Sli gene, although serious inbreeding depression associated with selfing occurred. The genotypes of S2 inbreds were surveyed using 46 S. chacoense-specific RFLP (restriction fragment length polymorphism) markers covering the whole potato genome. More than half of the markers (67.4%) showed distorted segregation. Particularly, all markers on chromosome 12 were overrepresented in the S2 inbreds. This confirms our earlier finding that the Sli gene locates on chromosome 12 and the alleles linked with this gene are preferentially transmitted because of its essential requirement for selfing.

Animals↗
PubMedDate not supplied

Genetic variation in two conserved local Romanian pig breeds using type 1 DNA markers.

Analysis of the genetic variation of an endangered population is an important component for the success of conservation. Animals from two local Romanian pig breeds, the Mangalitsa and Bazna, were analysed for variation at a number of genetic loci using PCR-based DNA tests. Polymorphism was assessed at loci which 1) are known to cause phenotypic variation, 2) are potentially involved in trait differences or 3) are putative candidate genes. The traits considered are disease resistance, growth, coat colour, meat quality and prolificacy. Even though the populations are small and the markers are limited to specific genes, we found significant differences in five of the ten characterised loci. In some cases the observed allele frequencies were interesting in relation to gene function and the phenotype of the breed. These breeds are part of a conservation programme in Romania and marker information may be useful in preserving a representative gene pool in the populations. The use of polymorphisms in type 1 (gene) markers may be a useful complement to analysis based on anonymous markers.

Animals↗
PubMed1998

Horizontal gene transfer as a biosafety issue: a natural phenomenon of public concern.

The transfer of genetic information between distantly or even unrelated organisms during evolution had been inferred from nucleotide sequence comparisons. These studies provided circumstantial evidence that in rare cases genes had been laterally transmitted amongst organisms of the domains bacteria, archaea and eukarya. Laboratory-based studies confirmed that the gene pools of the various domains of organisms are linked. Amongst the bacterial gene exchange mechanisms transduction, transformation and conjugation, the latter was identified as the mechanism with potentially the broadest host range of transfer. Previously, the issue of horizontal gene transfer has become important in the context of biosafety. Gene transfer studies carried out under more natural conditions such as in model ecosystems or in the environment established that all gene transfer mechanisms worked under these conditions. Moreover, environmental hot-spots were identified where favourable conditions such as nutrient enrichment increased the probability of genetic exchange among bacteria. In particular, the phytosphere was shown to provide conducive conditions for conjugative gene exchange. Concern has been expressed that transfer of recombinant DNA (e.g. antibiotic resistance genes) from genetically modified organisms (GMOs) such as transgenic plants to phytosphere bacteria may occur and thus contribute to the undesirable spread of antibiotic resistance determinants. Studies which were performed to address this issue clearly showed that such a transfer occurs, if at all, at extremely low frequency.

Biological Evolution↗
PubMed2001

Genetic diversity and differentiation in a southern beech subjected to introgressive hybridization.

Diversity and differentiation among 11 Argentine populations of the South American southern beech, Nothofagus nervosa (Phil.) Dimitri & Milano, were studied using eight isozyme gene markers. Genetic diversity, observed heterozygosity, mean number of alleles per locus, Gregorius' genetic distance, amount of genetic differentiation and mean level of differentiation among populations were estimated. Introgression of N. obliqua into the gene pool of N. nervosa was analysed using two species-specific isozyme gene markers (Adh-A and Pgi-B). As in most forest tree species, the main genetic variation was found within populations. Mean observed heterozygosity for the species was 17.3%, whilst mean level of genetic differentiation (deltage) was 4.6%. The most differentiated locus was Mdh-B with differences in 10% of the effective number of genes. From the analysis of the species distribution pattern it is suggested that genetic variation is geographically structured through the different lake watersheds along which the species is distributed. The occurrence of natural interspecific hybridization in some of the watersheds, together with the unidirectional gene flow along these watersheds sharpens this latitudinal structure. Different evolutionary stages in the introgressive hybridization process are apparently taking place in different lake watersheds.

Gene Frequency↗
PubMed1994

The porA gene in serogroup A meningococci: evolutionary stability and mechanism of genetic variation.

Molecular analyses were applied to the genes encoding variants of the serosubtyping antigen, the class 1 outer membrane protein (PorA), from 55 serogroup A Neisseria meningitidis strains. These genes were evolutionarily stable and exhibited a limited range of genetic variation, primarily generated by recombination. Translation of the gene sequences revealed a total of 19 distinct amino acid sequences in the variable regions of the protein, 6 of which were not recognized by currently available serosubtyping monoclonal antibodies. Knowledge of these amino acid sequences permitted a rational re-assignment of serosubtype names. Comparison of the complete genes with porA gene sequences from serogroup B and C meningococci showed that serogroup A possessed a limited number of the possible porA genes from a globally distributed gene pool. Each serogroup A subgroup was characterized by one of four porA gene types, probably acquired upon subgroup divergence, which was stable over periods of decades and during epidemiological spread. Comparison with other variable genes (pil and iga) indicated that the three alleles were independently assorted within the subgroup, suggesting that their gene types were older than the subgroups in which they occurred.

Alleles↗
PubMed2001

[Analysis of Alu-polymorphism in Buryat populations].

Polymorphism of three populations of the Buryat Republic and a population from Aginskii Buryat Autonomous okrug of Chita oblast was examined using a set of five autosomal Alu insertions at the ACE, PLAT, PV92, APOA1, and F13B loci. The allele frequency distribution patterns revealed in Buryat populations were typical to other Asian populations. Buryats were characterized by relatively low level of intrapopulation diversity (0.369 in the pooled population sample). Analysis of autosomal Alu insertions suggests the uniformity of the Buryat gene pool. The coefficient of genetic differentiation in the four populations studied was 0.8%.

Alleles↗
PubMed1989

Physical mapping of the human cytomegalovirus (HCMV) (Towne) DNA polymerase gene: DNA-mediated transfer of a genetic marker for an HCMV gene.

DNA-mediated transfer of a drug resistance marker (phosphonoacetate resistance) for the HCMV (Towne) DNA polymerase (pol) gene has been used to genetically confirm the physical localization of the HCMV (Towne) DNA pol gene. The HCMV (Towne) genomic region homologous to the pol genes of other herpesviruses was first identified by moderate stringency Southern hybridization. Restriction fragments from this region were molecularly cloned from previously characterized phosphonoacetic acid resistant (PAAr) HCMV genomes (R. T. D'Aquilla and W. C. Summers, J. Virol., 61, 1291-1295, 1987). A high frequency of recombinant PAAr virus was found among the progeny of cotransfections of infectious, wild-type HCMV (Towne) DNA only with pol-homologous restriction fragments cloned from PAAr HCMV. The co-transfection technique described here may facilitate further gene mapping in HCMV. The results presented here provide functional proof that the HCMV pol gene is encoded by the sequences previously identified as homologous to other herpesvirus pool genes.

Cytomegalovirus↗
PubMed2006

Molecular analysis of colonic transformation in the ileum after total colectomy in rats.

BACKGROUND: Colonic transformation is thought to be a phenotypic alteration in the ileum after total colectomy (TC) but has not been well addressed at the molecular level. We previously demonstrated roles of aldosterone in enhancement of ileal sodium absorption after TC. However, the significance of aldosterone in intestinal adaptation has been unknown. METHODS: Rat epithelial gene expression was compared between the ileum and distal colon by complementary DNA microarray. Genes were categorized into "colonic," "common," and "ileal" genes according to signal intensity. Ileal gene expressions in (1) the control and TC rats and (2) the control and aldosterone-infused rats were compared to detect altered genes or to assess the role of aldosterone in intestinal adaptation. Differential expression of MUC3 and lysozyme was confirmed by quantitative reverse transcriptase-polymerase chain reaction. RESULTS: A total of 6109 genes were categorized into "colonic," "common," or "ileal" gene pools. A comparison of the control and TC rats yielded 82 and 91 genes that were induced and suppressed in the ileum after TC, respectively. Thirty-five percent of them were associated with colonlike transformation (ie, the induction of colonic genes or the suppression of ileal genes). The expressions of MUC3 and lysozyme messenger RNAs were enhanced significantly in the TC ileum, compared with the control. In comparison, aldosterone infusion modulated a total of only 21 genes in the ileum. CONCLUSION: Those data demonstrate that altered gene expression after TC is, in part, characterized by colonlike transformation. Furthermore, circulating aldosterone appears to play a part in the altering and/or adapting of gene expression in intestinal epithelium.

Adaptation, Physiological↗
PubMed1991

Penicillin-binding proteins in Streptococcus pneumoniae: alterations during development of intrinsic penicillin resistance.

Four out of the five high molecular weight penicillin-binding proteins (PBPs) of Streptococcus pneumoniae are involved in the development of intrinsic penicillin resistance. In beta-lactam resistant laboratory mutants, point mutations in the PBP 2x-genes were identified that result in low penicillin-affinity mutant proteins. In contrast, PBPs 1a, 2x, and 2b of resistant clinical isolates are highly altered as can be recognized biochemically and immunologically; DNA sequence analysis of the PBP 2x gene from resistant strains confirmed these results. The variability of the three PBPs analyzed implies a very heterogeneous gene pool accessible to the pneumococcus that is used for recruitment of resistant PBP genes in wild type strains.

Anti-Bacterial Agents↗
PubMed1998

Prevalence of vacuolating cytotoxin production and distribution of distinct vacA alleles in Helicobacter pylori from China.

Studies of Helicobacter pylori from the West have linked production of vacuolating cytotoxin and a particular signal sequence (s1a) allele of the underlying vacA gene to peptic ulcer disease (PUD). Among Chinese H. pylori, most isolates from both PUD and gastritis patients were toxigenic (35/46 and 29/35, respectively). Polymerase chain reaction and DNA sequencing showed that 95 of 96 isolates carried vacA s1a alleles. In the mid-region, 78 of 96 isolates carried m2; 14 were m1-like but only 87% identical (DNA-level) to classical m1 and were designated m1b; the other 4 were unusual hybrids (m1b-type proximal, m2-type distal). Isolates with m1b and m1b-m2 alleles produced higher levels of vacuolating activity than did isolates with m2 alleles (P < .01). There was no association between any vacA allele and disease. These results suggest that the composition of H. pylori gene pools varies geographically and that other as-yet-unknown polymorphic H. pylori genes are important in PUD.

Alleles↗
PubMed1996

[Geography of effective size of rural populations of Northern Eurasia. Geographic correlation between effective size and level of heterozygosity of populations].

A significant geographical correlation (r = 0.719) was found between the logarithm of effective size (InNe) and heterozygosity level (H) in populations under the assumption of the Hardy-Weinberg equilibrium. The area of highest positive correlation was positioned meridionally between the Ob and Yenisei rivers, from the Arctic coast of Taimyr Peninsula to eastern Sayans and the southern Cis-Baikal region, i.e., in the same region where the highest distribution density of mean Ne values was found. Two additional areas of high correlations were found on the northern Black Sea coast and in the lower Lena river region. Analysis and mapping of correlation ratios eta H/lnNe2 and eta lnNe/H2 revealed that effective size substantially influenced heterozygosity level (as could be expected in the case of an intense gene drift), and heterozygosity level influenced effective size to the same extent. The latter relationship indicated an intense adaptation, and changes in diversity of the gene pool caused substantial demographic changes. However, this might be accounted for by direct gene migration into a population prevailing over reverse migration, i.e., mechanical population growth prevailing over natural growth.

Adaptation, Physiological↗