Distribution Pattern Of Genotypes Research Articles

Flowering Ecotypes of Capsella bursa-pastoris(L.) Medik. (Brassicaceae) Analysed by a Cosegregation of Phenotypic Characters (QTL) and Molecular Markers

Capsella bursa-pastoris(Brassicaceae) is an annual to biennial predominantly autogamous species distributed worldwide. Using a linkage map with RAPDs and isozymes we studied quantitative trait loci (QTL) controlling phenotypic traits in this invasive species. To obtain a mapping population we crossed two plants occurring in different climatic regions in California, USA (Central Valley and Sierra Nevada) with the most diverse ecotypes (phenotypic parameters) and genotypes (isozyme multilocus genotypes). A hundred and thirteen F2individuals were raised and analysed for segregation at 107 RAPDs, six isozyme loci, and one locus determining leaf type. The number, location and magnitude of genes underlying 13 traits were determined by using both interval and composite interval mapping. Two to five QTL affecting one character have been detected. Altogether the 13 quantitative traits produced 48 QTL. The inheritance patterns of traits ranged from those controlled by one QTL with a major effect to those controlled by several QTL with only minor effects. Closely linked QTL, e.g. onset of flowering with rosette leaf number, were interpreted as pleiotropic. Three major QTL account for onset of flowering. These loci were linked to at least three isozyme loci and several other QTL responsible for developmental traits like rosette leaf number. Heritability of quantitative traits, segregation of the leaf type, and segregation of the allozymes was tested in the F3generation. We conclude that historical events alone are insufficient to explain the distribution pattern of isozyme multilocus genotypes during the colonization of new regions and habitats. The present evidence indicates that ecotypic adaptation and genetic linkage of isozyme loci with adaptive characters are involved.

TT virus (TTV) genotypes in native and non-native prostitutes of Irian Jaya, Indonesia: implication for non-occupational transmission.

We investigated prostitutes in Irian Jaya, an Indonesian territory of New Guinea, to know whether TT virus (TTV) is sexually transmitted and what genotypes of TTV exist there. An ORF2 region of the TTV genome was analyzed for 44 isolates from prostitutes (19 were Irian Jaya natives but 25 were immigrants from Java or other islands of Indonesia) and 26 isolates from women of child-bearing age in Surabaya as a control. The WX(7)HX(3)CX(1)CX(5)H motif sequence of the ORF2 was compared across the 70 Indonesian isolates with a reference of 47 Japanese isolates (filed in databases) and the prototype TTV isolate TA278. A total of 77 different sequences were generated from the comparison, but a phylogenetic analysis suggested that they could be divided into three categories: group A, group B and others (the third group was highly diverse). Interestingly, most of the Indonesian isolates belonged to group B (74%): this rate was considerably higher than that observed previously in Japanese isolates. Group B isolates were further compared for the N-terminal 95 amino acids of the ORF2, with a result that the natives of Irian Jaya had a different pattern of genotype distribution from other groups. In particular, 9 out of 19 isolates from the Irian Jaya-natives were co-classified under a distinct branch, to which none of the other Indonesian and Japanese isolates belonged. Our data indicate that TTV genotypes reflect the birth place of the infected prostitutes rather than their work environment, and thus suggest that an infection is more likely during the early period of life than through sexual transmission. In addition, the presence of an Irian Jaya-specific genotype is intriguing from an anthropological and viral evolutionary point of view, because Irian Jaya has been isolated from contact with other areas for a long time.

The colonizing history ofCapsella in Patagonia (South America)—Molecular and adaptive significance

Twenty-two provenances ofCapsella bursa-pastoris (Brassicaceae) from Patagonia and Tierra del Fuego and 13 provenances from the middle part of South America have been investigated for phenotypic traits (flowering, growth form parameters, fruit characters), isozymes (AAT, GDH, LAP), and RAPDs.Capsella is native to Europe and was introduced into South America in the 16th century. In Patagonia, we detected 23 different multilocus associations, but only five occurred in a frequency of more than 5%. By comparison with the geographic distribution patterns of multilocus genotypes in Europe, we inferred the ancestral European gene pools and the possible introduction routes. A particular multilocus genotype (MMG) was most frequent in the investigated area, and is native to the Iberian Peninsula. This genotype was with all probability introduced by Spaniards into central and northern South America, and it could have reached Patagonia from the north step by step. Other genotypes probably used a direct route from Europe, most likely via British sheep farmers in the second half of the 19th century. Rare genotypes in Patagonia may have been introduced recently by chance, or might be due to multilocus rearrangements in connection with rare outcrossing events. RAPD markers helped to trace colonial gene pools outside Europe and ancestral European gene pools and support the isozyme studies. Correlations between the life history traits and allozyme markers give evidence of the role adaptation may play in the colonizing process.

Colonization history and introduction dynamics of capsella bursa-pastoris (Brassicaceae) in north america: isozymes and quantitative traits

Multilocus isozyme genotypic composition for aspartate aminotransferase (AAT), leucine aminopeptidase (LAP) and glutamate dehydrogenase (GDH) was studied for Capsella in the source continent, Europe (9000 plants from 593 populations), and in the colonized continent, North America (2700 plants from 88 populations). North America was depauperate in the number of genotypes (by approximately 50%), but in terms of frequencies, a few genotypes were common and shared by both continents. Although some, very rare, genotypes were, however, unique for North America, our data provided no evidence to indicate that the introduced gene pools were reconstructed on a multilocus genetic basis after introduction. Instead, they argued for a considerable number of independent introduction events. Geographical distribution patterns of multilocus genotypes in Europe and North America were pronounced and enabled us to trace the colonization history of Californian Capsella back to Spanish ancestral populations and those of temperate North America back to temperate European gene pools. A random-block field experiment with 14 Californian populations from different climatic regions revealed that variation patterns of quantitative traits reflect ecotypic variation, and the ecological amplitude of Capsella in North America is similar to that in Europe, which can be traced back to the introduction of preadapted genotypes. It appears that certain multilocus isozyme genotypes are associated with certain ecotypes. The variable European gene pool of Capsella was essentially introduced into North America without major genetic changes.

Estimating population size by genotyping faeces.

Population size is a fundamental biological parameter that is difficult to estimate. By genotyping coyote (Canis latrans) faeces systematically collected in the Santa Monica Mountains near Los Angeles, California, we exemplify a general, non-invasive method to census large mammals. Four steps are involved in the estimation. First, presumed coyote faeces are collected along paths or roadways where coyotes, like most carnivores, often defaecate and mark territorial boundaries. Second, DNA is extracted from the faeces and species identity and sex is determined by mitochondrial DNA and Y-chromosome typing. Third, hypervariable microsatellite loci are typed from the faeces. Lastly, rarefaction analysis is used to estimate population size from faecal genotypes. This method readily provides a point count estimate of population size and sex ratio. Additionally, we show that home range use paternity and kinship can be inferred from the distribution and relatedness patterns of faecal genotypes.

Postglacial recolonization and the biogeography of Palmaria mollis (Rhodophyta) along the Northeast Pacific coast

We used random amplified polymorphic DNA (RAPD) markers to examine the distribution of genotypes of Palmaria mollis (Setchell et Gardner) van der Meer et Bird, a red alga. We sampled populations along the Northeast Pacific coast from northern Washington to southwestern Alaska, an area extensively glaciated during the last ice age. Our objective was to determine whether the tracks of postglacial recolonization could be extracted from the extant pattern of genotype distribution in a species with limited dispersal capabilities. Thirty-eight individuals from 14 sites were sampled for RAPD markers using nine different random primers. As expected, individuals from the same population were more closely related to each other than to individuals from other populations. Relationships among populations, however, did not necessarily reflect geographic proximity. Rather, populations fell into groups corresponding approximately to outer and inner coastal sites: the northwestern end of Vancouver Island and the Queen Charlotte Islands formed one outer coast group, which associated with sites from Prince William Sound, the Alaska Peninsula, and Sitka, Alaska; the eastern side of Vancouver Island and Ketchikan, Alaska, represented one group of inner sites, which associated with sites near Juneau, Alaska and the eastern end of the Strait of Juan de Fuca. We conclude that this pattern does not represent a single postglacial recolonization event. Key words: biogeography, dispersal, genetic distance, Palmaria mollis, RAPDs, Rhodophyta.

Heterogeneity of Hepatitis C Virus Genotypes in Hemophilia: Relationship With Chronic Liver Disease

In this study we have determined the hepatitis C virus (HCV) serotype and genotype in a cohort of 96 HCV-infected hemophiliacs and have examined the relationship between HCV genotype and severity of chronic liver disease as determined by liver biopsy. HCV serotype was determined by specific enzyme-linked immunosorbent assays (ELISAs) and genotype by restriction fragment length polymorphism (RFLP) and HCV viral sequencing. The pattern of genotype distribution was quite unlike that of HCV-infected United Kingdom (UK) blood donors in that five of the six known HCV genotypes were represented, 50% were type 1, 13% type 2, and 18% type 3. An unexpected observation was the presence of HCV genotype 4 in four patients and type 5 in two patients. An additional feature was the presence of mixed infection, detected in 14% and 7% by serotype and genotype analysis, respectively. Liver biopsies were available from 51 patients. Cirrhosis was present in five of 27 (19%) of individuals with type 1, in 2 of 9 (22%) with type 2, and 5 of 8 (63%) of those with type 3. The heterogeneous pattern of HCV genotype distribution in this cohort of patients and the observed relationship between the severity of the related liver disease and specific HCV genotype may have important implications with respect to the natural history and treatment of HCV-related chronic liver disease in infected hemophiliacs worldwide.

The evolution of mitochondrial DNA in Partula

The mitochondrial DNA of species of land snails of the genus Partula from the Society Islands has been analysed by means of restriction enzymes to determine relationships within the genus. Seventeen variable restriction sites were mapped onto the 14.5 kb mtDNA. These sites are highly variable within species. In P. suturalis, those genotypes occurring within a population are usually separated by single-step changes, and the differences between populations are geographically coherent. There is no detectable association between the distribution of mitochondrial genotypes and the occurrence of dextral or sinistral populations, confirming that chirality does not constitute a genetic barrier in this species. P. taeniata also shows a coherent geographic pattern of genotype distribution within and between populations. The mitochondrial differences between morphologically similar populations in the northeast and northwest suggest that the similarity may be the result of convergence. Despite the regular patterns of distribution within species, some genotypes are widely shared among species. One pattern was found in four species on Moorea and two species on the neighbouring island of Tahiti. Shared genotypes may represent ancestral forms or they may have resulted from hybridization. However we believe that the most attractive hypothesis is that they are subject to selection. Studies of Partula demonstrate that the evolution of the morphological, electro-phoretic, and mitochondrial phenotypes occur at variable rates, independently of one another.