scholarly journals DNA fingerprinting demonstrates extremely low levels of genetic variation among blackberry cultivars grown in Finland

1997 ◽  
Vol 6 (3) ◽  
pp. 241-245
Author(s):  
Kristiina Antonius ◽  
Gun Werlemark ◽  
Hilde Nybom
Keyword(s):  
Genetic Variation ◽  
Dna Fingerprinting ◽  
Somatic Mutation ◽  
Dna Fingerprints ◽  
Low Levels ◽  
The University

Most blackberry plants cultivated in Finland closely resemble the American species Rubus allegheniensis. Thirty nine such blackberry accessions in the University of Helsinki clone collection were studied by hybridization-based DNA fingerprinting and compared with some known cultivars of R. allegheniensis derivation. ‘lmperial’ appears to be identical to the old cultivar ‘Majestät’, but ‘Earliest of All’ differs considerably. In addition, 37 of the accessions analysed also have DNA fingerprints that appear to be completely identical to that of ‘Majestät’! The remaining two accessions, although identical to each other, exhibit one band not found in ‘Majestät’ that is probably caused by a somatic mutation.

High Levels of Genetic Variability in an Isolated Colony of Rock-wallabies (Petrogale assimilis): Evidence from Three Classes of Molecular Markers

1997 ◽  
Vol 45 (2) ◽  
pp. 199 ◽  
Author(s):  
Peter B. S. Spencer ◽  
Mark Adams ◽  
Helene Marsh ◽  
David J. Miller ◽  
Mark D. B. Eldridge
Keyword(s):  
Genetic Variation ◽  
Molecular Markers ◽  
Genetic Variability ◽  
Mating Systems ◽  
Selective Pressure ◽  
Multiple Mating ◽  
Dna Fingerprints ◽  
Average Heterozygosity ◽  
Low Levels ◽  
High Level

Estimates of genetic variation for a small (Ne = 39) colony of allied rock-wallabies (Petrogale assimilis) were calculated with three different categories of molecular marker. Average heterozygosity was estimated at 3·8% for allozymes, 47·3% for multilocus ‘DNA fingerprints’ and 85·5% for microsatellite markers. Overall these values indicate that this small isolated colony of rock-wallabies maintains a high level of genetic variation despite its relative isolation and the apparently low levels of migration between colonies. It is likely that mechanisms exist (such as kin avoidance, multiple mating systems, high and variable selective pressure in extreme and fluctuating environmental conditions) that promote the maintenance of high levels of genetic variation in isolated colonies of P. assimilis. These mechanisms are discussed in the context of the results obtained from the molecular markers.

Genetic diversity in Puccinia striiformis Westend. f.sp. tritici revealed by pathogen genome-specific repetitive sequence

1998 ◽  
Vol 76 (4) ◽  
pp. 587-595 ◽  
Author(s):  
Wei-xing Shan ◽  
Shou-yi Chen ◽  
Zhen-sheng Kang ◽  
Li-ren Wu ◽  
Zhen-qi Li
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Dna Fingerprinting ◽  
Puccinia Striiformis ◽  
Phenotypic Diversity ◽  
Molecular Evidence ◽  
Polymorphism Analysis ◽  
Dna Fingerprints ◽  
High Level ◽  
Virulence Variation

DNA fingerprinting was used to examine genetic variation in populations of Puccinia striiformis Westend. f.sp. tritici, an obligate fungus that causes wheat stripe rust, using as a probe a moderately repetitive DNA sequence PSR331 that shows species specificity in the genome of this pathogen. One hundred and sixty isolates sampled from six provinces throughout China were examined for genetic variation over 26 putative genetic loci defined by PSR331 and the restriction enzyme BglII. Because of the dikaryotic nature of this fungus, DNA fingerprints can not differentiate heterozygotes from homozygotes. We refer to the PSR DNA fingerprints as phenotypes rather than genotypes. Phenotypic diversity analysis revealed a high level of genetic variation. A total of 97 phenotypes was detected among 160 isolates. Phenotypic diversity varied among regions, ranging from 0.3742 in Shaanxi to 0.9380 in Gansu, as calculated with the normalized Shannon's index. Genetic subdivision analysis revealed a low level of genetic differentiation (GST = 0.0084) among regions (Gansu, Henan, Shaanxi, Sichuan, and Yunnan provinces) as well as within regions (Gansu and Sichuan provinces). This, together with the detection of the same phenotypes among regions, provided the molecular evidence for gene flow in P. striiformis f.sp. tritici. The results support conclusions from virulence surveys that Tianshui of southern Gansu is probably the most important "hotspot" area with respect to the potential to generate and maintain virulence variation. DNA polymorphism analysis also detected potential hotspot areas in addition to southern Gansu. This may result in more difficulties in management of genetic variation and thus the potential virulence variation in P. striiformis f.sp. tritici as well as providing opportunities for searching disease resistance factors.Key words: genetic diversity, Puccinia striiformis, DNA fingerprinting, virulence variation.

Population Genetics ofCaenorhabditis elegans: The Paradox of Low Polymorphism in a Widespread Species

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 147-157 ◽  
Author(s):  
Arjun Sivasundar ◽  
Jody Hey
Keyword(s):  
Genetic Variation ◽  
Microsatellite Loci ◽  
Population Expansion ◽  
Widespread Species ◽  
C Elegans ◽  
Model Research ◽  
The World ◽  
Natural Isolates ◽  
History Of ◽  
Low Levels

AbstractCaenorhabditis elegans has become one of the most widely used model research organisms, yet we have little information on evolutionary processes and recent evolutionary history of this widespread species. We examined patterns of variation at 20 microsatellite loci in a sample of 23 natural isolates of C. elegans from various parts of the world. One-half of the loci were monomorphic among all strains, and overall genetic variation at microsatellite loci was low, relative to most other species. Some population structure was detected, but there was no association between the genetic and geographic distances among different natural isolates. Thus, despite the nearly worldwide occurrence of C. elegans, little evidence was found for local adaptation in strains derived from different parts of the world. The low levels of genetic variation within and among populations suggest that recent colonization and population expansion might have occurred. However, the patterns of variation are not consistent with population expansion. A possible explanation for the observed patterns is the action of background selection to reduce polymorphism, coupled with ongoing gene flow among populations worldwide.

Genetic Relationships of Cory's Shearwater: Parentage, Mating Assortment, and Geographic Differentiation Revealed by DNA Fingerprinting

The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 651-662 ◽  
Author(s):  
Corinne Rabouam ◽  
Vincent Bretagnolle ◽  
Yves Bigot ◽  
Georges Periquet
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Dna Fingerprinting ◽  
Genetic Relatedness ◽  
Isolation By Distance ◽  
Genetic Relationships ◽  
Cory’S Shearwater ◽  
Genetic Structure Of Populations ◽  
The Social ◽  
Calonectris Diomedea

Abstract We used DNA fingerprinting to assess genetic structure of populations in Cory's Shearwater (Calonectris diomedea). We analyzed mates and parent-offspring relationships, as well as the amount and distribution of genetic variation within and among populations, from the level of subcolony to subspecies. We found no evidence of extrapair fertilization, confirming that the genetic breeding system matches the social system that has been observed in the species. Mates were closely related, and the level of genetic relatedness within populations was within the range usually found in inbred populations. In contrast to previous studies based on allozymes and mtDNA polymorphism, DNA fingerprinting using microsatellites revealed consistent levels of genetic differentiation among populations. However, analyzing the two subspecies separately revealed that the pattern of genetic variation among populations did not support the model of isolation by distance. Natal dispersal, as well as historic and/or demographic events, probably contributed to shape the genetic structure of populations in the species.

Genetic variation of Colletotrichum magnum isolated from Carica papaya as revealed by DNA fingerprinting

2018 ◽  
Vol 56 (11) ◽  
pp. 813-821
Author(s):  
Daisy Pérez-Brito ◽  
Alberto Cortes-Velázquez ◽  
Teresita Valencia-Yah ◽  
Anuar Magaña-Álvarez ◽  
Cuauhtémoc Navarro ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Dna Fingerprinting ◽  
Carica Papaya

Low levels of genetic variation inPhenakospermum guyannense (Strelitziaceae), a widespread bat-pollinated Amazonian herb

1996 ◽  
Vol 199 (1-2) ◽  
pp. 1-15 ◽  
Author(s):  
Cheryl S. Roesel ◽  
W. John Kress ◽  
Brunella Martire Bowditch
Keyword(s):  
Genetic Variation ◽  
Low Levels

scholarly journals University dropout. Causes and solution

2019 ◽  
Vol 1 (1) ◽  
pp. 71-75
Author(s):  
Camelia Stăiculescu ◽  
Richiteanu Nastase Elena Ramona
Keyword(s):  
Retention Rate ◽  
Academic Training ◽  
Counseling Services ◽  
Prior Training ◽  
Student Background ◽  
Social Nature ◽  
Personal Level ◽  
Low Levels ◽  
University Dropout ◽  
The University

The phenomenon of university dropout is met in all universities in the world and its effects are felt both at the economic level, at the level of society and at the personal level of students who abandon the university. Factors leading to university dropout may be of a social nature (student background, income level, so on.), psycho-pedagogical (inadequate academic training, inconsistency between prior training and university studies, lack of counseling services, so on)and personal (poor adaptability to the university, low levels of socio-emotional intelligence, so on). Universities need to cope with this phenomenon and adapt and develop prevention and intervention services so that students' retention rate rises. The paper analyzes this phenomenon in The Bucharest University of Economic Studies and identifies possible solutions for diminishing the phenomenon.

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