Population genetics of invasive common carp Cyprinus carpio L. in coastal drainages in eastern Australia.

The common carp Cyprinus carpio introduced in two drainages in eastern Australia are largely descended from European common carp, and in a third drainage they descend largely from East Asian common carp. The partial genetic differentiation among the species in those drainages is consistent with their origins.

Population genetics and management units of invasive common carp Cyprinus carpio in the Murray-Darling Basin, Australia.

Common carp Cyprinus carpio were introduced into Australia on several occasions and are now the dominant fish in the Murray-Darling Basin (MDB), the continent's largest river system. In this study, variability at 14 microsatellite loci was examined in C. carpio (n = 1037) from 34 sites throughout the major rivers in the MDB, from 3 cultured populations, from Prospect Reservoir in the Sydney Basin and from Lake Sorrell in Tasmania. Consistent with previous studies, assignment testing indicated that the Boolara, Yanco and koi strains of C. carpio are present in the MDB. Unique to this study, however, the Prospect strain was widely distributed throughout the MDB. Significant genetic structuring of populations (Fisher's exact test, AMOVA and distribution of the different strains) amongst the MDB sub-drainages was detected, and was strongly associated with contemporary barriers to dispersal and population history. The distributions of the strains were used to infer the history of introduction and spread of C. carpio in the MDB. Fifteen management units are proposed for control programmes that have high levels of genetic diversity, contain multiple interbreeding strains and show no evidence of founder effects or recent population bottlenecks.

Microevolution and mega-icebergs in the Antarctic.

Microevolution is regarded as changes in the frequencies of genes in populations over time. Ancient DNA technology now provides an opportunity to demonstrate evolution over a geological time frame and to possibly identify the causal factors in any such evolutionary event. Using nine nuclear microsatellite DNA loci, we genotyped an ancient population of Adélie penguins (Pygoscelis adeliae) aged approximately 6,000 years B.P. Subfossil bones from this population were excavated by using an accurate stratigraphic method that allowed the identification of individuals even within the same layer. We compared the allele frequencies in the ancient population with those recorded from the modern population at the same site in Antarctica. We report significant changes in the frequencies of alleles between these two time points, hence demonstrating microevolutionary change. This study demonstrates a nuclear gene-frequency change over such a geological time frame. We discuss the possible causes of such a change, including the role of mutation, genetic drift, and the effects of gene mixing among different penguin populations. The latter is likely to be precipitated by mega-icebergs that act to promote migration among penguin colonies that typically show strong natal return.

Defective in vitro gamma interferon production and elevated serum immunoreactive thymosin beta 4 levels in patients with inflammatory bowel disease.

Gamma interferon (IFN-gamma) production by peripheral blood mononuclear cells (PBM) was measured in 21 patients with Crohn's disease, in 15 patients with ulcerative colitis, in 12 patients with non-IBD gastrointestinal disease (disease control), and in 28 healthy controls. T-cell subset proportions and serum levels of thymosin alpha 1 and thymosin beta 4, two hormonelike thymic peptides, were also determined. No differences were seen in T-cell subset proportions in patients with Crohn's disease or ulcerative colitis when compared to healthy controls or to the disease-control group. In vitro IFN-gamma production was markedly decreased in Crohn's disease and in untreated, but not treated, patients with ulcerative colitis. Preincubation of PBM prior to the addition of inducer mitogen resulted in enhanced IFN-gamma production in patients with Crohn's disease or ulcerative colitis which significantly exceeded that seen either in healthy controls or in the disease-control group. Serum thymosin alpha 1 levels were comparable in all study groups; however, serum thymosin beta 4 concentrations were significantly higher in all patient groups than in the healthy controls. These results confirm a defective in vitro IFN-gamma production in patients with IBD which is apparently independent of endocrine thymus regulation.