scholarly journals Unusually Low Levels of Genetic Variation among Giardia lamblia Isolates

2007 ◽  
Vol 6 (8) ◽  
pp. 1421-1430 ◽  
Author(s):  
Smilja Teodorovic ◽  
John M. Braverman ◽  
Heidi G. Elmendorf
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Giardia Lamblia ◽  
Diarrheal Disease ◽  
Regulation Of Gene Expression ◽  
Genetic Exchange ◽  
Disease Etiology ◽  
Noncoding Regions ◽  
Low Genetic Diversity ◽  
Low Levels

ABSTRACT Giardia lamblia, an intestinal pathogen of mammals, including humans, is a significant cause of diarrheal disease around the world. Additionally, the parasite is found on a lineage which separated early from the main branch in eukaryotic evolution. The extent of genetic diversity among G. lamblia isolates is insufficiently understood, but this knowledge is a prerequisite to better understand the role of parasite variation in disease etiology and to examine the evolution of mechanisms of genetic exchange among eukaryotes. Intraisolate genetic variation in G. lamblia has never been estimated, and previous studies on interisolate genetic variation have included a limited sample of loci. Here we report a population genetics study of intra- and interisolate genetic diversity based on six coding and four noncoding regions from nine G. lamblia isolates. Our results indicate exceedingly low levels of genetic variation in two out of three G. lamblia groups that infect humans; this variation is sufficient to allow identification of isolate-specific markers. Low genetic diversity at both coding and noncoding regions, with an overall bias towards synonymous substitutions, was discovered. Surprisingly, we found a dichotomous haplotype structure in the third, more variable G. lamblia group, represented by a haplotype shared with one of the homogenous groups and an additional group-specific haplotype. We propose that the distinct patterns of genetic-variation distribution among lineages are a consequence of the presence of genetic exchange. More broadly, our findings have implications for the regulation of gene expression, as well as the mode of reproduction in the parasite.

scholarly journals Genetic diversity of rice stem borer (Chilo suppressalis Walker) from Northern Iran and comparison with other countries

2016 ◽  
Vol 48 (3) ◽  
pp. 360 ◽  
Author(s):  
M. Shayanmehr ◽  
E. Yoosefi-Lafooraki
Keyword(s):  
Genetic Diversity ◽  
Stem Borer ◽  
Chilo Suppressalis ◽  
Mazandaran Province ◽  
Northern Iran ◽  
Low Genetic Diversity ◽  
High Gene ◽  
Major Pest ◽  
Different Populations ◽  
Low Levels

Rice striped stem borer, <em>Chilo suppressalis</em> Walker (Lepidoptera: Crambidae) is considered the major pest of rice in Iran. Because of the serious damage on rice in Northern Iran, the present study was conducted to investigate genetic diversity within populations of <em>C. suppressalis</em>, from Mazandaran using a template of cytochrome oxidase I gene, 750 bps, (<em>COI</em>). Later the haplotypes from Iran were compared with those found in other countries. According to the results of this study, there is very low genetic diversity (two haplotypes) among different populations of this pest in populations of Northern Iran. The genetic similarity and low levels of genetic diversity of these populations suggest that the pest colonization occurred relatively recently and there is high gene flow between these populations of the province. In addition, haplotypes of Mazandaran province are different with those found in other countries. The similarity of Iranian population (Simorgh) with one population from China indicated that China might be the origin of <em>C. suppresalis</em>.

Analysis of genetic variation within clonal lineages of grape phylloxera (Daktulosphaira vitifoliae Fitch) using AFLP fingerprinting and DNA sequencing

Genome ◽  
2007 ◽  
Vol 50 (7) ◽  
pp. 660-667 ◽  
Author(s):  
S. Vorwerk ◽  
A. Forneck
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Chloroplast Dna ◽  
Aflp Fingerprinting ◽  
Daktulosphaira Vitifoliae ◽  
Banding Patterns ◽  
Grape Phylloxera ◽  
Noncoding Regions ◽  
Polymorphic Bands ◽  
Fingerprinting Methods

Two AFLP fingerprinting methods were employed to estimate the potential of AFLP fingerprints for the detection of genetic diversity within single founder lineages of grape phylloxera ( Daktulosphaira vitifoliae Fitch). Eight clonal lineages, reared under controlled conditions in a greenhouse and reproducing asexually throughout a minimum of 15 generations, were monitored and mutations were scored as polymorphisms between the founder individual and individuals of succeeding generations. Genetic variation was detected within all lineages, from early generations on. Six to 15 polymorphic loci (from a total of 141 loci) were detected within the lineages, making up 4.3% of the total amount of genetic variation. The presence of contaminating extra-genomic sequences (e.g., viral material, bacteria, or ingested chloroplast DNA) was excluded as a source of intraclonal variation. Sequencing of 37 selected polymorphic bands confirmed their origin in mostly noncoding regions of the grape phylloxera genome. AFLP techniques were revealed to be powerful for the identification of reproducible banding patterns within clonal lineages.

scholarly journals Microsatellite analysis of genetic diversity and structure of Bruguiera gymnorrhiza and Kandelia obovate

2018 ◽  
Vol 52 ◽  
pp. 00027 ◽  
Author(s):  
Mohammad Basyuni ◽  
Shigeyuki Baba ◽  
Hirosuke Oku
Keyword(s):  
Genetic Diversity ◽  
Allelic Diversity ◽  
Geographic Range ◽  
Microsatellite Analysis ◽  
Bruguiera Gymnorrhiza ◽  
Low Genetic Diversity ◽  
Genetic Diversity And Structure ◽  
Low Levels ◽  
High Level ◽  
F Statistics

Microsatellite loci were used for estimating genetic diversity and structure for three populations of B. gymnorrhiza and K. obovata (Rhizophoracea) in Okinawa, Japan. Thirty propagules of individual samples representing the population of both species were genotyped at five microsatellites. The level of observed heterozygosity (HO) was observed for several population, overall loci, ranged 0.422-0.800 with an average 0.627 for B. gymnorrhiza and 0.477-0.822 with an average 0.665 for K. obovata, indicating both species had relatively low genetic diversity. Both species showed low levels of allelic diversity, 3-5 and 3-5 alleles per locus, respectively. Gene diversitywas also maintained within populations (HS: 0.741 and 0.954). Additionally, an analysis of molecular variance (AMOVA) based on the immeasurable alleles model (F-statistics), for B. gymnorrhiza and K. obovata found that most of the variation resided within individuals in the total populations, i.e. 79.78 % and 69.90 % respectively, and among individuals within populations, i.e.14.30 % and 27.95 % respectively. There was little variation between populations, i.e. 5.92 % and 2.15 % for B. gymnorrhiza and K. obovata, respectively. The high-level genetic differentiation within individuals and populations both species may be due to the geographic range of the species, mating system, and environmental factors.

scholarly journals Low Genetic Diversity of Haemophilus influenzae Type b Compared to Nonencapsulated H. influenzae in a Population in Which H. influenzaeIs Highly Endemic

1998 ◽  
Vol 66 (7) ◽  
pp. 3403-3409 ◽  
Author(s):  
Heidi C. Smith-Vaughan ◽  
Kadaba S. Sriprakash ◽  
Amanda J. Leach ◽  
John D. Mathews ◽  
David J. Kemp
Keyword(s):  
Genetic Diversity ◽  
Haemophilus Influenzae ◽  
Genetic Exchange ◽  
Haemophilus Influenzae Type ◽  
Haemophilus Influenzae Type B ◽  
Nasopharyngeal Carriage ◽  
Type B ◽  
Genetic Characteristics ◽  
Low Genetic Diversity ◽  
Typing Methods

Immunization with Haemophilus influenzae type b (Hib) conjugate polysaccharide vaccines has dramatically reduced Hib disease worldwide. As in other populations, nasopharyngeal carriage of Hib declined markedly in Aboriginal infants following vaccination, although carriage has not been entirely eliminated. In this study, we describe the genetic characteristics and the carriage dynamics of longitudinal isolates of Hib, characterized by using several typing methods. In addition, carriage rates of nonencapsulated H. influenzae(NCHi) are high, and concurrent colonization with Hib and NCHi is common; we also observed NCHi isolates which were genetically similar to Hib. There is a continuing need to promote Hib immunization and monitor H. influenzae carriage in populations in which the organism is highly endemic, not least because of the possibility of genetic exchange between Hib and NCHi strains in such populations.

Application of DNA markers in determination of fusarium resistance and genetic diversity in chickpea

2018 ◽  
Author(s):  
S. M. Babayeva ◽  
J. A. Nasibova ◽  
Z. I. Akparov ◽  
K. B. Shikhaliyeva ◽  
A. D. Mammadova ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Resistance Gene ◽  
Dna Markers ◽  
Rapd Markers ◽  
Molecular Characterisation ◽  
Fusarium Resistance ◽  
Low Genetic Diversity ◽  
Screening For Resistance

Genetic diversity and fusarium resistance of 50 cultivated chickpea genotypes was studied using ISSR and RAPD markers. The results of both marker systems were consistent with each other, but was somewhat higher for RAPDs. A total of 48 fragments were obtained with both markers together, 32.7% of which were polymorphic. Molecular characterisation through ISSR and RAPD data indicated low genetic variation (GDI=0.39; PIC=0.21) among local and introduced chickpea accessions. The genetic distance values ranged from 0 to 0.134, with a mean of 0.05. The low genetic diversity indicated that new genotypes must be introduced to increase the variability of chickpea germplasm in Azerbaijan. As a result of screening for resistance to fusarium most of genotypes were found to have 600 bp fragment of OPJ20 linked with Foc01 resistance gene, while none of them had resistance gene to Foc4. The results could provide information for future chickpea breeding activities and conservation.

Low levels of genetic diversity in red pine confirmed by random amplified polymorphic DNA markers

1992 ◽  
Vol 22 (9) ◽  
pp. 1332-1337 ◽  
Author(s):  
A. Mosseler ◽  
K.N. Egger ◽  
G.A. Hughes
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Rapd Markers ◽  
Black Spruce ◽  
Random Amplified Polymorphic Dna ◽  
Red Pine ◽  
Gene Markers ◽  
Island Populations ◽  
Oligonucleotide Primers ◽  
Low Levels

Random amplified polymorphic DNA (RAPD) markers were used to characterize genetic variation in disjunct Newfoundland populations of red pine (Pinusresinosa Ait.) for comparison with individuals from throughout the mainland range of red pine. Red pine demonstrated a largely monomorphic profile for 69 arbitrary oligonucleotide primers. DNA samples from white spruce (Piceaglauca (Moench) Voss) and black spruce (Piceamariana (Mill.) B.S.P.) that were screened together with red pine for 11 oligonucleotide primers showed abundant polymorphisms, confirming the genetic heterogeneity that characterizes these Boreal Zone spruces. Results with RAPD markers correspond with genetic diversity estimates using isozyme gene markers for both spruce species and red pine. RAPD markers provided further confirmation of low levels of genetic variation for a random sample of the red pine genome. A period of between 8000 and 10 000 years of isolation on the island of Newfoundland has resulted in very little detectable genetic differentiation of island populations from mainland populations, and the mainland populations have not recovered from losses of genetic diversity following a hypothesized genetic bottleneck that may have been experienced during glacial episodes of the Holocene. The low levels of genetic variation observed in red pine demonstrate the long time periods required for recovery following a loss of genetic diversity in long-lived, long-generation organisms like trees.

Already at the bottom? Demographic declines are unlikely further to undermine genetic diversity of a large Arctic ungulate: muskox, Ovibos moschatus (Artiodactyla: Bovidae)

2019 ◽  
Vol 129 (2) ◽  
pp. 459-469
Author(s):  
Erin Prewer ◽  
Susan Kutz ◽  
Lisa Marie Leclerc ◽  
Christopher J Kyle
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Allelic Richness ◽  
Evolutionary Potential ◽  
Ovibos Moschatus ◽  
Low Genetic Diversity ◽  
Expected Heterozygosity ◽  
Large Populations ◽  
Victoria Island ◽  
Demographic Patterns

Abstract Low genetic diversity is associated with low fitness and evolutionary potential, yet the demographic and life-history traits of some species contribute to low genetic diversity, without empirical evidence of negative impacts on fitness. Modelling past and future trajectories of genetic diversity under different demographic scenarios can provide insight into how genetic variation might impact population fitness. The muskox is an Arctic species that has undergone multiple population bottlenecks and, although populations have rebounded repeatedly, two large populations have recently declined by &gt; 50%. It is unclear how these demographic patterns influence muskox genetic diversity and fitness. We compared the genetic diversity of Canadian muskox populations undergoing opposing population trends. Genotyping 84 mainland and 244 Victoria Island individuals at ten microsatellite loci revealed low genetic variation (Victoria Island, mean allelic richness 1.66, expected heterozygosity 0.16; mainland, mean allelic richness 2.58, expected heterozygosity 0.41), with no evidence of further reductions in diversity subsequent to recent demographic declines. Bayesian modelling showed that a 1900s bottleneck contributed to the lack of diversity in contemporary populations, and forward-in-time simulations suggested little effect on genetic diversity over the next 100 years. Muskoxen might have reached a genetic diversity minimum, and additional research will be needed to determine their capacity to adapt to rapid changes in selective pressures in a rapidly changing Arctic.

scholarly journals Selection of progenitors for increase in oil content in soybean

Revista CERES ◽  
2016 ◽  
Vol 63 (5) ◽  
pp. 661-667 ◽  
Author(s):  
Josiane Isabela da Silva Rodrigues ◽  
Klever Márcio Antunes Arruda ◽  
Newton Deniz Piovesan ◽  
Everaldo Gonçalves de Barros ◽  
Maurilio Alves Moreira
Keyword(s):  
Genetic Diversity ◽  
Glycine Max ◽  
Genetic Distance ◽  
Oil Content ◽  
Infrared Spectrometry ◽  
Low Genetic Diversity ◽  
Soybean Genotypes ◽  
Glycine Max L ◽  
Low Levels ◽  
Selection Of

ABSTRACT The low genetic diversity brings limitation to breeding, because genetically similar genotypes share alleles in common, causing little complementarity and low vigor due to the low levels of heterozygosity in crosses. The objective of this work was to analyze the oil content and genetic diversity of soybean genotypes (Glycine max (L.) Merrill) based on QTL regions of this trait for choice of progenitors for increase in oil content. Twenty-two genotypes with wide variation in oil content, including cultivars with high oil contents, were cultivated in different Brazilian conditions and the oil content of the grains was quantified by infrared spectrometry. Microsatellite markers selected based on QTL regions for oil content in soybean were analyzed to estimate the genetic diversity. In these studies, a wide variation in oil content (17.28-23.01%) and a reasonable diversity among the genotypes were observed, being PI181544 the most divergent genotype, followed by Suprema. The genotypes PI371610/Suprema and Suprema/CD01RR8384 showed genetic distance and higher oil contents in the grains, while the cultivars Suprema and CD01RR8384 had the highest oil contents and proved to be little genetically related. These genotypes are promising progenitors for selection of high oil content in soybean.

scholarly journals Genetic Analysis of Pinus sylvestris L. and Pinus sylvestris forma turfosa L. Using RAPD Markers

2010 ◽  
Vol 2 (1) ◽  
pp. 129-132 ◽  
Author(s):  
Beáta ÁBRAHÁM ◽  
Ildikó MIKLÓSSY ◽  
Erika KOVÁCS ◽  
Éva TAMÁS ◽  
Ildikó MÉSZÁROS ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Pinus Sylvestris ◽  
Gene Diversity ◽  
Random Amplified Polymorphic Dna ◽  
Raised Bogs ◽  
Low Genetic Diversity ◽  
Genetic Differentiation Of Populations ◽  
Fossil Records ◽  
Continental Glaciation

The purpose of the present study was to determine the level of genetic diversity within and among Ciuc basin, Romania (populations from Mohos and Luci raised bogs in Harghita Mountain and Sumuleu in Ciuc Mountain) Pinus sylvestris populations using molecular markers. Two of populations (Mohos and Luci) seems to be the descendants that survived the continental glaciation. Genetic diversity was analyzed by RAPD (Random Amplified Polymorphic DNA). Nine primers were selected for analysis, which generated reproducible bands. On base of presence or absence of homologues bands Nei’s gene diversity, the percentage of polymorphic loci and Nei’s unbiased genetic distance were calculated. The level of genetic variation among populations was found to be low. For both populations the variation values among populations were higher than within populations. The fossil records and geological historical data explain the extremely low genetic diversity of this species. Pinus sylvestris experienced strong bottlenecks during its evolutionary history, which caused the loss of genetic variation. Genetic drift and breeding in post-bottlenecked small populations may be the major forces that contribute to low genetic diversity and genetic differentiation of populations. Human activities may have accelerated the loss of genetic diversity in Pinus sylvestris.

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