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PubMedDate not supplied

[Molecular marker mapping of the gene resistant to common bunt transferred from Aegilops cylindrica into bread wheat].

Introgression lines 5/55-91 and 378/2000 of bread wheat contain the gene of resistance to Tilletia caries (DC.) Tul. transferred from Aegilops cylindrica Host. Using bulked segregant analysis with ISSR and SSR PCR the lincage of microsatellite locus Xgwm 259 with the gene of common bunt resistance has been identified in F2 population of 378/2000 x Lutestens 23397. DNA mapping made it possible to localize this highly effective gene in the intercalary region of the long arm of wheat chromosome 1B at the distance of 7.6-8.5 cM of the microsatellite Xgwm 259 locus which thus can be used in wheat breeding for selection of genotype resistance to common bunt.

Crosses, Genetic↗

PubMed2006

Region of rat chromosome 8 determines complex nutrigenetic interactions under conditions of sucrose and cholesterol diets.

We have previously established a congenic strain SHR-Lx that carries a differential segment of rat chromosome 8 introgressed from a model of metabolic syndrome--the polydactylous rat strain--on the genomic background of spontaneously hypertensive rat (SHR). We compared the glucose tolerance and lipid profile of adult SHR and SHR-Lx males under conditions of standard diet and diets enriched in sucrose and cholesterol, respectively. While there was no evident difference between the SHR and SHR-Lx on standard diet, the one-week sucrose administration revealed the congenic strain sensitivity to carbohydrate-induced dyslipidemia conferred by the differential segment with only mild derangement of glucose tolerance. On the other hand, the high-cholesterol diet administration for three-weeks resulted in a contrasting pattern as the congenic strain displayed significantly lower concentrations of free fatty acids and improved glucose tolerance compared to SHR. After one-month washout period, the SHR-Lx showed higher insulin, triglyceride and cholesterol concentrations together with diminished insulin sensitivity of visceral adipose tissue. In summary, we have identified a genomic region syntenic to human chromosome 11q23, which determines complex nutrigenetic interactions under conditions of sucrose- and cholesterol-enriched diets.

Animal Nutritional Physiological Phenomena↗

PubMed1991

Genetic and molecular approach for breeding and use of laboratory fish for the detection of agents with carcinogenic and/or promoting activity.

Xiphophorine fish from wild populations are insusceptible to develop neoplasia. In contrast, certain backcrosses of Xiphophorus maculatus (platyfish) with Xiphophorus helleri (swordtail) as the recurrent parent, produce offspring that develop neoplasia in a Mendelian fashion. We concentrated our research on melanoma. The starting signal for the development of melanoma comes from an accessory v-erbB-related oncogene, x-erbB*, which is highly homologous to the human EGF receptor gene, and is part of a platyfish-specific tumor gene-complex designated as Tu. Normally, the platyfish is protected from its own Tu by Tu-specific regulatory gene systems. The swordtail has neither evolved the Tu-complex nor the regulatory gene systems. Therefore, the backcross procedure dismantles the regulatory gene systems thus permitting Tu-directed melanoma formation. x-erbB* derived from the platyfish, together with the swordtail-derived oncogenes src, sis, pdgf-r, ras, myc, erbA are expressed or overexpressed in the melanoma, and inositol lipid turnover is considerably elevated. x-src and inositol lipid turnover have also been found elevated in the healthy tissues (eg brain) of the tumourous fish. To construct a fish strain which is highly susceptible to mutagenic carcinogens, we introduced a particular regulatory gene, ie an oncosuppressor gene (Bs), into the genome of the animals developing Mendelian inherited melanoma, by introgressive breeding. Bs prevents the strain from germ line-inherited melanoma but, following carcinogen-induced impairment in a somatic cell gives rise to the Tu-directed development of clonal melanoma in a particular fish, x-src activity and inositol lipid turnover are elevated in the tumor but, in contrast to the animals bearing the inherited melanoma, are not elevated in the brain. Promoting carcinogens (tumor promoters) do not induce melanoma in this strain. Similarly, in order to breed a fish strain susceptible to tumor promoters, we introduced a regulatory gene (the oncostatic gene g, golden) coding for a pre-transformational arrest of pigment cell differentiation in the stem cell stage of the fish that develop the Mendelian inherited melanoma. The new strain is incapable of developing melanoma. Its x-src activity and inositol lipid turnover is elevated in the brain indicating that the biochemical processes which were found to be correlated with the hereditary melanoma formation, are running in the new strain without the occurrence of melanoma. Following treatment with tumor promoters that overcome the arrest of pigment cell differentiation, melanoma develops within a very short latent period.

Animals↗

PubMed1991

Discrimination of initiating and promoting carcinogens in fish.

Xiphophorine fish from wild populations are insusceptible of developing neoplasia. In contrast, certain backcrosses of Xiphophorus maculatus (platyfish) with Xiphophorus helleri (swordtail) as the recurrent parent produce offspring that develop neoplasia in a Mendelian fashion. We concentrated our research on melanoma. To construct a fish strain which is highly susceptible to mutagenic carcinogens, a particular regulatory gene, ie an oncosuppressor gene (Bs), was introduced into the fish developing the Mendelian inherited melanoma by introgression. Bs prevents the progeny from developing melanoma. However, Bs can be impaired by carcinogen-induced somatic mutation which gives rise to the development of clonal melanoma. Activity of the oncogene x-src (measured on pp60x-src kinase activity) and inositol lipid turnover is elevated in the tumor but, in contrast to the animals bearing the inherited melanoma, not in the brain. Tumor promoters do not induce melanoma in this strain. Similarly, in order to breed a fish strain which is highly susceptible to tumor promoters we introduced a regulatory gene, for instance an oncostatic gene (g) coding for a pretransformational arrest of pigment cell differentiation in the stem cell stage of the fish that develop the Mendelian inherited melanoma. The new strain is incapable of developing melanoma. Its x-src kinase activity and inositol lipid turnover is elevated in the brain, indicating that the biochemical processes which were found to be correlated with the hereditary melanoma formation, operate without the occurrence of melanoma. Following treatment of these animals with tumor promoters, melanoma develops within a very short latent period. Our tester strain can discriminate between tumor-initiating and tumor-promoting activities of agents of unknown carcinogenic potential.

Animals↗

PubMed1978

Genetic distance between two sibling species of the Aedes mariae complex (Diptera, Culicidae).

Two sibling species of the mariae complex of the Aedes genus have been studied: Ae. mariae and Ae. zammitii. Thee mosquitoes are allopatric and show similar adaptations to rocky mediterranean coasts. The isolating mechanisms between the two species are well studied. A partial sterility of hybrid F1, limited to males, has been found with laboratory cross experiments. Strong pre-mating isolating mechanisms were shown in nature by means of release experiments, the frequency of hybrids never exceeding 2% without evidence of introgression. We analyzed genetic variation at 26 enzyme loci in a population of each species: 35% of loci were polymorphic, with an observed mean heterozygosity of 0.07 in Ae. mariae and 0.06 in Ae. zammitii; 6 loci allow discrimination between the two species at a probability of at least .99. Nei's measures of genetic identity and genetic distance are respectively I = 0.6096 and D = 0.2828. The distribution of genetic identities relative to loci is strongly bimodal, reflecting a different contribution of highly variable and fast evolving loci on one side and conservative and slowly evolving loci on the other. We consider, on the base of various experimental data (see Powell, 1975), in the first class ("fast evolving" loci) both variable substrate and regulatory enzymes, in the second ("slow evolving" loci) non regulatory enzymes. Values of genetic distance calculated separately for the "fast" (54% of the loci studied) and "slow" (46%) evolving loci are respectively Df = 0.41 and Ds = 0.03, showing that the main contribution to genetic distance in the first period of divergence is due to fast evolving loci, whose rate of evolution is about ten times more rapid with respect to slow evolving loci.

Aedes↗

PubMed1984

Natural interspecific hybridisation of simulium sanctipauli s.l. with Simulium squamosum and Simulium yahense (Diptera: Simuliidae).

Natural hybridisation between Simulium sanctipauli (sensu Quillevéré et al. 1981) and Simulium squamosum/yahense occurs at a rate of around 0.001. A single larva has been found which is unambiguously a backcross between S. sanctipauli s.l. and a S. sanctipauli s.l. X squamosum/yahense hybrid. This discovery indicates the possibility of genetic introgression between these species. Examination of the polytene chromosomes of this backcross progeny and subsequent re-examination of the type specimens has led to the remapping of fixed interspecific inversions in chromosome arm 1L.

Animals↗

PubMed1980

[Quantitative analysis of melanoma growth in tumorous fish of the genus Xiphophorus after partial-body X-irradiation with therapeutic doses (author's transl)].

Hereditary melanomas in Xiphophorus helleri, caused by the spotted dorsal gene, Sd, and its modifiers, have arisen by introgressive hybridization of X. maculatus X X. helleri-hybrids with X. helleri. 7 of those melanotic poeciliid fish had been X-irradiated, 10 tumorous sibs from the same brood were kept as controls. The total X-ray dose of 9000 R was fractionated into partial doses of 5000 R and 4000 R, respectively. Only the melanomatous regions of the caudal peduncle and those of the dorsal part of the body, the dorsal and caudal fins included, were irradiated. The rest of the trunk was shielded with lead against radiation. The teleosteans were 162 days old when irradiated for the first time; the second exposure followed 193 days later. In intervals of 14 or 21 days, the animals had been photographed, and the melanotic areas of the enlarged prints had been determined by planimetrical measuring. After this, they were calculated as percent of the total body surface, both with and without the dorsal fin area. There was a significant regression of melanoma growth in irradiated fish.

Animals↗

PubMedDate not supplied

[An analysis of the genetic structure of a hybrid population of green frogs, Rana esculenta complex, from the flats of the Danube].

Analysis of genetic structure of geographically isolated population of hybrid complex Rana esculenta L. from Danube delta according to a complex of biochemical gene markers was conducted. A parental species of Rana ridibunda and hybrids ridibunda-lessonae of the first generation only were found in the population. The complete absence of genetic recombination and introgression of genes from the locus Ldh-B, which was found in Dnieper populations, is characteristic of the population. The differences observed may be explained by genetic nonuniformity of geographical forms of R. lessonae. This forms may have taxonomic differences.

Alleles↗

PubMed1995

[Genetic structure and origin of the tetraploid toad Bufo danatensis Pisanetz, 1978 (Amphibia, Bufonidae) from Central Asia. Biochemical polymorphism and comparison of the level of heterozygosity of diploid species with tetraploid species].

Comparison of individual variation at 24 biochemical loci in members of the species complex of Palearctic green toads showed that the heterozygosity of the tetraploid species Bufo danatensis (Hobs + 0.45) was significantly higher than that of the diploid species B. viridis, B. sp., and B. raddei (Hobs = 0.009 - 0.103). Such difference can be explained only by a hybrid origin of the tetraploid species. Individual electrophoretic variability of the polyploid toad species is associated with an allelic variation that is manifested in constantly heterozygous spectra as the gene dosage effect. At the population level, this phenomenon found in Pamir toads is caused by irregular meiosis in founders of the population or by directional changes in gene regulation. Genotypic distributions in zones of contact of the diploid and tetraploid taxons demonstrate the possibility of restricted introgressive hybridization.

Animals↗

PubMed1993

[Genome diagnosis in domestic animals].

Different contributions to the development and applications of genomic diagnosis methods in domestic animals are reported. DNA fingerprints were used to solve parentage disputes in different species, and to reveal leucochimerism in bovine dizygotic twins. In cattle, an embryo sexing method and a freemartinism diagnosis assay were also developed. The search for molecular markers of the MH (muscular hypertrophy) and R (rouan) bovine genes is described. Prion protein gene polymorphisms are investigated in the framework of a research on the genetics of bovine spongiform encephalopathies. The mutation responsible for the autosomal recessive lethal condition BLAD (bovine leucocyte adhesion deficiency) in Holstein cattle is found in our country, and the carries can be detected by a molecular method. The mutation responsible for the halothane sensitivity in pig can also be detected, what is done to control efficiently the introgression of the stress resistance allele in a Piétrain strain.

Animals↗

PubMed1993

[Instructions for the correct use of zoologically relevant species designations for our domestic and laboratory animals, with reference to the current nomenclature of their breed types].

This study is concerned with the correct use of the scientific zoological nomenclature for domesticated and laboratory animals. With the help of four tables, additionally, the most current latin names of all important domesticated animals (animals of economic importance, ranch-bred animals, companion animals, fancy animals, laboratory animals) are given. The authors suggest a formal nomenclature for domesticated animals which should principally be related to the scientific name of the parent species (binomially and in italics), as always followed by the completion "forma domestica/f. dom." (not in italics). Problems arising from the use of such scientific names when hybridization and introgression is concerned are also discussed, and appropriate nomenclature is proposed.

Animals↗

PubMed1996

Distinguishing between primary and secondary intergradation among morphologically differentiated populations of Anolis marmoratus.

Distinguishing between primary and secondary intergradation among differentiated populations, and the relative importance of drift and selection, are persistent problems in evolutionary biology. An historical perspective on population interactions can provide insight into the nature of contacts, and thus help resolve these questions. Continuously distributed populations of Anolis marmoratus from the island of Basse Terre in the Guadeloupean archipelago of the Lesser Antilles show a striking degree of geographic variation in morphology. Initial surveys of mtDNA variation from throughout the Guadeloupean Archipelago revealed one case where levels of sequence difference and phylogenetic relationships of alleles from morphologically differentiated populations from the east coast of Basse Terre were consistent with primary intergradation. In this paper, I examine the genetic population structure of a series of populations spanning this north-south cline in morphological variation to test the hypothesis of primary intergradation. Sequences of the mitochondrial cytochrome-b gene from 50 individuals representing five populations spanning the cline were obtained and fourteen unique haplotypes (differing by 2% or less) were detected. Patterns of nucleotide substitution among haplotypes do not deviate from neutral expectation indicating no effect of selection at the level of mtDNA sequences. Estimates of population structure and gene flow were made using both summary statistics for nucleotide diversity (Nst) and cladistic methods. The results are sensitive to the choice of gene flow model, and this is discussed in detail. Mitochondrial variation in the northern populations may not be at equilibrium, and the phylogeny of alleles is consistent with a recent increase in effective population size. Estimates of nucleotide diversity, gene flow, and the phylogenetic relationships of haplotypes indicate that the southern-most population (representing the extreme of morphological variation along this cline) has been relatively isolated from populations to the north and has experienced a reduced effective population size. The apparent clinal variation between the southern population and the others may therefore reflect secondary contact and introgression rather than primary intergradation.

Animals↗

PubMedDate not supplied

[A genetic analysis of the structure of hybrid populations of the green frog Rana esculenta L. complex (Amphibia, Ranidae) in Volhynia].

Analysis of the genetic structure of two green frog Rana esculenta complex populations from Volyn' was performed for 7 diagnostical loci. Populations of R- and REL-type were detected in which the introgression of Ldh-B allelic gene locus from R. lessonae into genome of R. ridibunda, characteristic for hybrid populations of Dnieper basin, was absent. This may be associated with alterations in gene pools of parental species.

Alleles↗

PubMed1997

Intron-length polymorphism at the actin gene locus mac-1: a genetic marker for population studies in the marine mussels Mytilus galloprovincialis Lmk. and M. edulis L.

A novel intron-length polymorphism at the actin gene locus mac-1 is here reported and used as a genetic marker for population studies in mussels of the genus Mytilus. Two closely related genes subsequently identified as alleles, mac-1a1 and mac-1b1, from a genomic library of M. galloprovincialis were partially cloned and sequenced. They mainly differed from each other by a 65-bp insertion within their first intron. Polymerase chain reaction (PCR) primers were designed outside the insertion. The PCR analysis of 166 individual mussels from M. galloprovincialis and M. edulis populations revealed three size-classes of alleles or allelomorphs, two of which were of the expected sizes for mac1a1 and mac-1b1. One allelomorph was absent from M. edulis samples, although it was present at substantial frequencies in M. galloprovincialis populations. The frequencies of the two other allelomorphs significantly differed between M. galloprovincialis and M. edulis populations. The comparison of six mac-1 intron sequences over 277 bp showed at once that allelomorphs encompassed alleles differing from one another by substantial numbers of mutations, and that identical alleles were present in both M. galloprovincialis and M. edulis individuals, a probable result of the recent introgression between the two species.

Actins↗

PubMed1997

Characterization of mitochondrial DNA and Y-chromosome haplotypes in a Uruguayan population of African ancestry.

We used a set of informative mtDNA and Y-chromosome-specific markers to determine the origin of maternal and paternal lineages in a sample of 41 Uruguayan black individuals. We found that 20 maternal lineages were African, 13 were Amerindian, and 5 were Caucasian. In three individuals we were unable to determine the ethnic origin of the mtDNA lineages. Of the 22 males analyzed we found 4 Y chromosomes of African origin, 5 of Caucasian origin, and 13 of undetermined ancestry. Our results suggest that mtDNA and Y-chromosome-specific DNA variants may be a useful tool in determining the level of mtDNA and Y chromosome ethnic introgression in a population of a given ethnic origin.

Africa↗

PubMed1997

The plasmacytoma resistance gene, Pctr2, delays the onset of tumorigenesis and resides in the telomeric region of chromosome 4.

Mouse plasmacytomas share pathogenetic features in common with both multiple myeloma and Burkitt's lymphoma in humans. Susceptibility to plasmacytoma induction by intraperitoneal pristane in mice is controlled by multiple genes. At least two of these genes reside on mouse chromosome 4 in regions of the genome sharing linkage homology with human chromosomes 9p21, 1p32, and 1p36. A series of congenic strains recombinant for regions of mouse chromosome 4 in the vicinity of the Pctr2 predisposition locus were created and typed for their tumor susceptibility/resistance phenotypes. These strains were derived by introgressively backcrossing alleles from resistant DBA/2 mice onto the susceptible BALB/cAnPt background. Six resistant and two susceptible strains were allelotyped for 10 genes and 49 random DNA markers to identify the smallest region of overlap in the resistant strains. These studies have determined that the Pctr2 locus resides in either a 500-kb interval proximal to Nppa, or in a 1- to 2-centiMorgan (cM) interval distal to Nppa. In these congenic strain analyses, the Nppa and Fv1 loci, in addition to genes within about 1 cM of these loci, have been excluded as candidates for the Pctr2 locus. A relevant locus that may reside in this interval is Rep2; it is associated with the efficiency of repairing X-ray induced DNA damage sustained during the G2 phase of the mitotic cycle. The Pctr2 locus acts in a codominant fashion. F1 hybrids between resistant and susceptible congenic strains exhibit a reduced tumor incidence and a significant delay in the onset of tumorigenesis. Identification and eventual cloning of the Pctr2 locus may assist in the identification of genes involved in many types of cancer showing aberrations in human chromosome 1p36.

Alleles↗

PubMed1998

Pacific Coast Iris species delimitation using three species definitions: biological, phylogenetic and genealogical

Morphological characters are used to discriminate the five Oregon species of the Pacific Coast irises (Iris series Californicae). In nearly every case, fixed differences were found between species, revealing that they are good phylogenetic species. However, when the biological species concept is applied, the whole series is found to be one biological species. Sequence data were generated from the chloroplast DNA region between the atpbeta and rbcL genes. For this 700 bp region, the maximum divergence observed in the series was one percent. These sequences, together with three restriction site characters, were used to produce a cladogram for multiple individuals of all species in the group. On the resulting consensus cladogram, the different individuals from each species do not cluster together. This could result from either introgressive hybridization or the retention of ancestral polymorphism. When the genealogical species concept is applied, only one species can be identified: the whole Series Californicae. There are therefore two natural levels at which taxa can be defined. It is recommended that the phylogenetic species be used as the taxonomic species in this group.Copyright 1998 The Linnean Society of London

Journal Article↗

PubMed1998

Mitochondrial and nuclear DNA sequence variability among populations of rainbow trout (Oncorhynchus mykiss).

Mitochondrial and nuclear DNA variability was examined to assess population genetic structure and phylogeographic relationships in rainbow trout. Single-strand conformation polymorphisms and restriction site differences within 1055 bp of the mitochondrial D-loop region and 1566 bp of nuclear DNA in six single-copy nuclear DNA regions identified 31 mitochondrial genotypes and 50 nuclear alleles. Gene trees were constructed by sequencing each variant allele or mitochondrial genotype identified. Examination of 30 populations in 10 native rainbow trout groups using analysis of molecular variance (AMOVA) indicated that 65% of mitochondrial variability and 35% of nuclear variability was explained by differences among the 10 groups. Phylogenetic patterns evident in mitochondrial and nuclear DNA were not always concordant. Differences in the evolutionary patterns detected by mitochondrial and nuclear DNA may reflect the differential impact of past introgression events on variability in the two genomes.

Alleles↗