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Search Results: 1 - 10 of 13976 matches for " genetic characterization. "
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Molecular Characterisation Reveals the Existence of a Hybridogenous Intermediary Form between Sweet Watermelon and Cow Melon Forms of Watermelon  [PDF]
Claid Mujaju, Rudo Musango, Larisa Garkava-Gustavsson
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.96092
Abstract: Watermelon research in Southern Africa, has predominantly observed the clear existence of the sweet watermelon and cow melon forms of watermelon, cultivated on farm and even some occurring in the wild. Molecular characterization of 48 watermelon accessions collected from National Genebank of Zimbabwe using 9 SSR markers generated a total of 49 putative alleles. The average number of alleles detected by each primer was 5.4. Analysis of molecular variance within and among accessions of watermelons revealed that only 39% of the total variation resides between these two groups (cow-melons and sweet watermelons), 24% between accession within groups and 37% within accessions. Multivariate analyses employed provide evidence of the existence of introgression between sweet water melons and cow melons, as reflected by some accessions of cow melons, clustering into a hybridogenous group. Most of watermelon accessions within the hybridogenous group [A (II)] were collected from drier communal areas, while those accessions within the cow melon group [A (I)] are mostly from research centers. The separation of cow melons into distinct groups could be indicative of a possible formation of an isolated evolutionary unit.
Molecular Diversity in Selected Banana Clones (Musa AAA “Cavendish”) Adapted to the Subtropical Environment of Formosa Province (Argentina)  [PDF]
José Luis Ermini, Gerardo Carlos Tenaglia, Guillermo Raúl Pratta
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.912181
Abstract: Banana production dates from the 1920s in Argentina. Rhizomes were introduced and dispersed by immigrants from bordering countries in the Northern provinces. There is scarce information on its genetic diversity to assist in crop breeding programs; hence studies of genetic structure between populations and individuals are fundamental for future use. Molecular markers assess the diversity of the crop. This study employed Amplified Fragment Length Polymorphism to investigate the genetic variation in local banana plants from farmer’s fields. Forty-four rhizomes (selected from a total of 860 plants for being stable for production) were used as plant material and 6 primer combinations selected in a previous report were used. Polymorphic fragments present in a given genotype were assigned 1 and those absent were assigned 0. The matrix generated was analyzed by univariate and multivariate analysis. A total 540 bands were scored, of which 100% were polymorphic. The number of the pattern duplicated bands was 23 and twenty-one amplicons were exclusive to banana plants collected in the same farmer’s field. Hierarchical clustering and principal coordinates analyses showed differences between genotypes. The cophenetic correlation of the cluster was 0.63 while the 18% of the total molecular variation was explained by the two principal coordinates. These analyses evidence genetic diversity of the crop according to farmer’s field. In agreement to this observation, analysis of molecular variance revealed that 8.9% of the variation was found among farmer populations and 91.1% within farmer populations. In conclusion, introduction of banana into the subtropical zone was associated with a broader genetic variation in order to increase the genetic homeostasis necessary for adapting the crop to the suboptimal environment of Northeastern Argentinean Formosa Province.
Molecular characterization of Trypanosoma cruzi Mexican strains and their behavior in the mouse experimental model
Gómez-Hernández, César;Rezende-Oliveira, Karine;Nascentes, Gabriel Ant?nio Nogueira;Batista, Lara Rocha;Kappel, Henrique Borges;Martinez-Ibarra, José Alejandro;Trujillo Contreras, Francisco;Lages-Silva, Eliane;Ramírez, Luis Eduardo;
Revista da Sociedade Brasileira de Medicina Tropical , 2011, DOI: 10.1590/S0037-86822011005000058
Abstract: introduction: for a long time, the importance of chagas disease in mexico, where many regarded it as an exotic malady, was questioned. considering the great genetic diversity among isolates of trypanosoma cruzi, the importance of this biological characterization, and the paucity of information on the clinical and biological aspects of chagas disease in mexico, this study aimed to identify the molecular and biological characterization of trypanosoma cruzi isolates from different endemic areas of this country, especially of the state of jalisco. methods: eight mexican trypanosoma cruzi strains were biologically and genetically characterized (pcr specific for trypanosoma cruzi, multiplex-pcr, amplification of space no transcript of the genes of the mini-exon, amplification of polymorphic regions of the mini-exon, classification by amplification of intergenic regions of the spliced leader genes, rapd - (random amplified polymorphic dna). results: two profiles of parasitaemia were observed, patent (peak parasitaemia of 4.6×106 to 107 parasites/ml) and subpatent. in addition, all isolates were able to infect 100% of the animals. the isolates mainly displayed tropism for striated (cardiac and skeletal) muscle. pcr amplification of the mini-exon gene classified the eight strains as tci. the rapd technique revealed intraspecies variation among isolates, distinguishing strains isolated from humans and triatomines and according to geographic origin. conclusions: the mexican t. cruzi strains are myotrophic and belong to group tci.
Molecular characterization of rabies virus isolated from non-haematophagous bats in Brazil
Albas, Avelino;Campos, Angélica Cristine de Almeida;Araujo, Danielle Bastos;Rodrigues, Camila Seabra;Sodré, Miriam Martos;Durigon, Edison Luiz;Favoretto, Silvana Regina;
Revista da Sociedade Brasileira de Medicina Tropical , 2011, DOI: 10.1590/S0037-86822011000600006
Abstract: introduction: rabies is an important zoonosis that causes thousands of deaths worldwide each year. although the terrestrial cycle, mainly transmitted by dogs, is controlled in brazil, the aerial cycle remains a serious public health issue, besides the economic problem. in the aerial cycle, the haematophagous bat desmodus rotundus is the main source of infection, where several different species of non-haematophagous bats can be infected and can transmit the virus. methods: the aim of this work was to study the epidemiological pattern of rabies using antigenic characterization with monoclonal antibodies and genetic characterization by reverse-transcriptase polymerase chain reaction followed by sequencing and phylogenetic analysis of non-haematophagous bats' and herbivorous animals' central nervous system samples from the western region of the state of s?o paulo, brazil. results: from 27 samples, 3 antigenic variants were identified: agv-3, agv-4, and agv-6; and from 29 samples, 5 different clusters were identified, all belonging to the rabies virus species. conclusions: although only non-haematophagous bats were evaluated in the studied region, the majority of samples were from antigenic and genetic variants related to haematophagous bats desmodus rotundus. samples from the same antigenic variant were segregated in more than one genetic cluster. this study demonstrated the diversity of rabies virus genetic lineages presented and circulating in non-haematophagous bats in the studied region.
Agrobiodiversity in Cucurbita spp. landraces collected in Rio de Janeiro assessed by molecular markers
Santos, Marilene Hilma dos;Rodrigues, Rosana;Gon?alves, Leandro Sim?es Azeredo;Sudré, Cláudia Pombo;Pereira, Messias Gonzaga;
Crop Breeding and Applied Biotechnology , 2012, DOI: 10.1590/S1984-70332012000200001
Abstract: diversity and genetic relationship in forty landraces of cucurbita spp. collected at small farms in rio de janeiro, brazil, were analyzed by rapd and issr markers, using 20 and 15 primers, respectively. both markers were efficient to cluster the accessions separating among species, but not so much to the detection of intra-specific variability, considering the event of different pairs of accessions comprising null genetic distances observed for both markers in c. moschata. low values observed for genetic distance among the c. moschata landraces showed that most likely genetic losses is in progress in that region of cultivation due to anthropic and market pressure, which are stimulating the small farmers to abandon their local varieties in order to use commercial seeds, including hybrids, which is causing risk of genetic erosion.
Agrobiodiversity in Cucurbita spp. landraces collected in Rio de Janeiro assessed by molecular markers
Marilene Hilma dos Santos,Rosana Rodrigues,Leandro Sim?es Azeredo Gon?alves,Cláudia Pombo Sudré
Crop Breeding and Applied Biotechnology , 2012,
Abstract: Diversity and genetic relationship in forty landraces of Cucurbita spp. collected at small farms in Rio de Janeiro, Brazil, were analyzed by RAPD and ISSR markers, using 20 and 15 primers, respectively. Both markers were efficient to cluster the accessions separating among species, but not so much to the detection of intra-specific variability, considering the event of different pairs of accessions comprising null genetic distances observed for both markers in C. moschata. Low values observed for genetic distance among the C. moschata landraces showed that most likely genetic losses is in progress in that region of cultivation due to anthropic and market pressure, which are stimulating the small farmers to abandon their local varieties in order to use commercial seeds, including hybrids, which is causing risk of genetic erosion.
Microsatellite variability analysis in farmed catfish (Ictalurus punctatus) from Tamaulipas, Mexico
Perales-Flores, Laura E.;Sifuentes-Rincón, Ana María;León, Francisco J. García de;
Genetics and Molecular Biology , 2007, DOI: 10.1590/S1415-47572007000400011
Abstract: analysis of cultured catfish from six farms in tamaulipas, mexico was achieved using a combination of microsatellite pcr analysis and semiautomatic fluoresce-based detection, in order to provide a first assessment of the genetic variability on cultured catfish in mexico. five microsatellites showed extensive polymorphism with allele numbers ranging from 10 and 20. overall observed heterozygosity at each locus ranged between 0.76 and 0.91 and the average polymorphic information content (pic) for the five loci was 0.811, indicating that these loci can be used for studies of paternity identification, linkage and population genetics. on the basis of the fst values (fst = 0.03829; p = 0.00000) it appears that there was a small amount of genetic differentiation between the channel catfish stocks. the high intrapopulation allelic diversity was the most remarkable parameter.
Caracteriza??o genotípica dos isolados de Escherichia coli provenientes de frangos de corte
Silva, I.M.M.;Evêncio-Neto, J.;Silva, R.M.;Lucena-Silva, N.;Magalh?es, J.;Baliza, M.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2011, DOI: 10.1590/S0102-09352011000200010
Abstract: the isolates of escherichia coli from chicken livers from two slaughterhouses were genotypically characterized in 62 samples. thirty samples were macroscopically unchanged and 32 demonstrated alterations that led to the disposal of carcass for sanitary inspection. thirty escherichia coli strains from 21 unchanged and 9 from carcasses that were rejected were isolated through the classical method. polymerase chain reaction was performed to verify e. coli virulence of the following genes: serum resistance (iss), to identify avian pathogenic e. coli; shiga cytotoxin 1 and 2 (stx), to identify enterohaemorrhagic e. col; bfpa, to identify enteropathogenic e. coli; lt-i (elt) and st-i (sti) toxins to identify enterotoxigenic e. coli. iss gene was identified in 83.3% (25/30), being 76.2% (16/21) from e. coli isolated strains from healthy animals. stx gene was identified in 13.3% (4/30) of e. coli isolates, and in three of these samples was identified as stx and iss, featuring a mixed infection. the genes were not identified in one e. coli isolated from the classic method. thus, it is necessary to use advanced technologies to identify and prevent escherichia coli contamination in poultry farms and slaughterhouses.
Genetic variability among cassava accessions based on SSR markers
Ribeiro, Márcia de Nazaré Oliveira;Carvalho, Samuel Pereira de;Santos, Jo?o Bosco dos;Antonio, Rafaela Priscila;
Crop Breeding and Applied Biotechnology , 2011, DOI: 10.1590/S1984-70332011000300009
Abstract: the aim of this study was to characterize and estimate the genetic similarity among 93 cassava accessions. the dna amplification was performed with 14 microsatellite primers. the amplification products were separated by a polyacrylamide gel electrophoresis, showing a polymorphism formation, through which the accessions were discriminated against. the genetic similarity among accessions of cassava was estimated by the dice coefficient. cluster analysis was carried out using the upgma method. the polymorphic primers amplified a total of 26 alleles with 2-4 alleles per loci. the genetic similarity ranged from 0.16 to 0.96. the average values for observed and expected heterozygosity were 0.18 and 0.46, respectively. twenty genetic similarity clusters were determined, demonstrating diversity among accessions, suggesting the possibility of heterotic hybrid generation.
Caracteriza??o genética de popula??es naturais de araticunzeiro (Annona crassiflora Mart. - Annonaceae) no Estado de Goiás
Telles, Mariana P.C.;Valva, Fabrizio D.;Bandeira, Ludmila F.;Coelho, Alexandre S.G.;
Brazilian Journal of Botany , 2003, DOI: 10.1590/S0100-84042003000100013
Abstract: the level and distribution of the genetic variability in natural populations of "araticunzeiro" were estimated using a sample of six natural populations, collected in two different regions of the state of goiás, brazil. samples comprising 30 individuals from each population were genetically evaluated for four allozyme loci: 6-phosphogluconate dehydrogenase (6pgd), phosphoglucomutase (pgm), malate dehydrogenase (mdh) and leucine aminopeptidase (lap). two dimeric loci were detected for the 6pgd isozyme system while all the other systems evaluated showed typical monomeric loci pattern. no polymorphism was detected for the mdh enzymatic system. the estimated average number of alleles per polymorphic loci was two. the estimated total heterozygosity (averaged across loci) was 0.357, suggesting that a high level of genetic variability is present in the species along the sampled geographic region. about 19% of the total genetic variation was found to be due to differences at the population level, suggesting the existence of a high genetic divergence among populations. accordingly, the analysis of variance of allelic frequencies for each polymorphic loci showed a strong genetic structure at the population level. significant values for the average coefficients of coancestry among individuals within populations and for total inbreeding were found. the genetic divergences between pairs of populations showed to be partially correlated to the geographic distances between pair members. results obtained here suggested that a. crassiflora is preferentially alogamous, in conformity with other authors findings.
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