No description available.

No description available.

Allozyme data and DNA strand break frequencies were compared among populations of Pleurocera canaliculatum from five sites with varying mercury contamination on the North Fork Holston River (NFHR) in southwestern Virginia, USA. Allozyme genotype frequencies for four loci were significantly different between populations from the three most highly contaminated sites and those from two lesser contaminated sites. In addition, heterozygosity at three of these loci was significantly lower in the populations from the most highly contaminated sites. The DNA strand break frequency was significantly correlated to whole-body total mercury concentration in snails from three sites. These data add to the evidence supporting the use of DNA strand breakage as an indicator of chemical contamination and the use of allozyme analysis as a marker of contamination and possible selection for pollution resistance. However, the relationship between contaminant-induced changes in the genetic variation of enzymes of central metabolism and the functionalities upon which selection for resistance may act remain unclear, and mechanisms other than selection for resistance must be considered. Use of enzymes from other biochemical pathways may be appropriate for other species or for those under other chemical pollution pressures.

The brook trout <i>Salvelinus fontinalis</i> is the only salmonid native to the southern Appalachian Mountains, and is distributed across eastern North America from Canada to Georgia. This species was once abundant in coldwater lakes and streams throughout its range, but environmental disturbances and the introduction of non-native species have drastically reduced the number and sizes of wild populations. Genetic evidence suggests a division at the subspecies level between southern- and northern-derived brook trout populations, with the break between the two forms occurring roughly at the New River watershed. Before the subspecies structure was recognized, brook trout of northern origin were widely stocked throughout the Southeast. The primary objective of this study was to determine the phylogenetic origin of all wild brook trout populations in southwestern Virginia using allozyme markers. Seventy-eight streams believed to contain brook trout in the New, James, Holston, and Yadkin river drainages were sampled by backpack electrofishing. Muscle tissue samples were collected from 916 individuals from 56 populations using a non-lethal biopsy technique. The samples were analyzed by cellulose acetate gel electrophoresis and histochemical staining techniques. Variation at four polymorphic loci, including the diagnostic creatine kinase (<i>CK-A2*</i>) locus, was quantified in terms of genetic diversity and population genetic differentiation. Allele frequencies indicated that 19 populations were of putative southern origin, 5 of northern origin, and 32 of mixed genetic origin. The secondary objective was to determine the geographic distribution of southern- and northern-form brook trout populations throughout the native range using data compiled from all known genetic studies. A map of these data showed that the break between the southern and northern form is sharp, occurring at the New/Roanoke-James watershed divide. Populations from the New River drainage expressed the southern allele at a frequency of 85%, suggesting that their historic native character is southern, and that the presence of northern alleles is due to stocking or stream-capture events. The persistence of the southern form, despite the heavy stocking of northern-derived individuals, may be evidence of an adaptive advantage for the southern form of the species. Existence of adaptive genetic differentiation supports the case for conservation of the southern form of the species in future management of brook trout. / Master of Science

Not much is known about the mechanisms affecting the genetic composition of populations of different species. To investi­gate one of these potential mechanisms, mating behaviour, the fruit fly Drosophila melanogaster, was chosen as an experimen­tal animal. To quantify mating behaviour in easily measurable parameters, it was subdivided into several distinct components; mating activity, mating time, mating competition ability and male mating capacity. As behavioural components to a great extent are influenced by environmental conditions all experiments were performed under controlled temperature and humidity. All components of mating behaviour were estimated by introducing females and males into mating chambers. Mating behaviour seems to be one of the major factors affect­ing the genetic composition of Drosophila melanogaster popula­tions. The experiments performed showed that differences in mating properties led to a substantial sexual selection among the genotypes. This selection was of a stabilizing type with regard to characters associated to bristle number and Y chromo­somal chromatin. This selection situation seems to warrant the retention of intermediate phenotypes in a population and will therefore contribute to the genetic variation present. Differences in mating properties were also shown to be able to maintain a balanced polymorphism for allozyme variants in populations. This maintenance was obtained through different forms of balancing selection as heterozygous superiority in sexual activity and balancing selection between female and male genotypes. Heterozygous superiority or overdominance in fitness always leads to balanced polymorphism through segre­gation of individuals with lowered fitness. The balancing selection between the female and male genotypes is best looked upon as a form of marginal overdominance, conferring the aver­aged highest fitness to the heterozygous genotype, thereby maintaining the polymorphism of the population. / <p>Härtill 5 uppsatser</p> / digitalisering@umu

Phosphoglucomutase (PGM) is one of the central enzymes in energy metabolism at a branch point at the head of the metabolic pathway leading into glycogen metabolism, pentose shunt and the main glycolytic cycle, catalyzing the reversible interconversion of glucose-1-phosphate to glucose-6-phosphate. Whole year, month to month analysis of pattern of allozyme variation at Pgm and Hk loci in Apis mellifera L. from three provinces / Kirklareli, Artvin, and Hatay revealed that there is significant seasonal variation of allozyme frequencies at Pgm locus (P&lt / 0.001). The difference in genotype frequencies between summer and winter samples is apparent in Pgm, whereas at Hk locus, which is analyzed as a control there is seasonal variation in genotype frequencies. Biochemical measurements of the enzyme activities and glycogen content of different Pgm genotypes were performed to determine the effect of different Pgm genotypes on the physiological performance of the honeybees and it was observed that both enzyme activity and glycogen amount is higher in heterozygote individuals which are in high frequency during winter months (P&lt / 0.0001). Furthermore, PGM enzyme activity and glycogen content was found to be significantly correlated. These findings clearly demonstrate that biochemical differences between different Pgm genotypes have functional correlates that lead to significant variations in glycogen content of the honeybees and may have adaptive consequences.

Evolutionary models addressing interaction between genetics and morphology propose that during development, morphological traits of organisms are under canalization selection resulting in constancy in morphology through evolutionary time. The hypothesis of genetic homeostasis predict that because of developmental buffering effects of heterosis, high level heterozygosity results in low level of morphological variance from the norms of canalized shape of the population. The aim of the present study is to test whether the variation in shape of organisms is negatively correlated with genetic variation in Pseudophoxinus populations. Sample collection was performed from eight localities for four different Pseudophoxinus species (P. crassus, P. battalgili, P. egridiri, P. sp) in Central and South Anatolia in summer period of 2006. Shape variation of the specimens was determined using geometric morphometric methods. Genetic variation was based on six microsatellite and ten allozyme loci. All the microsatellite loci were found to be polymorphic. However, the percentage of monomorphic locus for allozymes varied from 90% to 60% per population. Statistically significant negative correlation was observed between shape and genetic variation derived from microsatellite data. However, this was not the case for allozyme heterozygosity / there wasn&rsquo / t any significant relationship between shape variation and allozymes heterozygosity. Low number of polymorphic loci observed in allozymes may prevent to reveal possible relationship between shape and genetic variations. As a result, the present study confirmed the hypothesis of genetic homeostasis for microsatellite data.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Allozyme frequencies and general protein patterns were surveyed among selected Texas marine fishes and shellfishes to illustrate the application of biochemical genetic techniques to stock and species identification in fisheries management.

A method has been developed for the rapid, quantitative separation of normal and abnormal phosphoglucose isoemrase allozymes from individuals heterozygous for genetic variant forms of the enzyme. The method utilizes a substrate gradient elution of the enzyme from carboxymethyl Biogel and is far superior in terms of resolution and recovery to methods based on electrophoresis and isoelectric focusing. Four different genetic variant forms of the enzyme were isolated and subjected to a systematic comparison of their physical, catalytic and stability properties. The physical and catalytic properties of the variants were similar; however, clear differences in the stability of the allozymes were apparent.