Characterization of Sarcocystis species in domestic animals using a PCR-RFLP analysis of variation in the 18S rRNA gene: a cost-effective and simple technique for routine species identification

Thirteen restriction endonucleases were used to investigate nucleotide sequence variation in the 18S rRNA DNA of 88 individuals from ten Sarcocystis taxa collected as cysts from their intermediate hosts, swine, cattle and water buffalo. A DNA sequence of

Phylogeographic analysis of mtDNA variation in four ethnic populations from Yunnan Province: new data and a reappraisal

Two sets of mitochondrial DNA (mtDNA) hypervariable segment I (HVS-I) data from four ethnic populations (Tibetan, Va, Dai, and Lahu) from Yunnan Province, China, were analyzed here by using phylogeographic methods. The results suggest that more attention

Mitochondrial DNA variation, effective female population size and population history of the endangered Chinese sturgeon, Acipenser sinensis

The anadromous Chinese sturgeon (Acipenser sinensis), mainly endemic to the Yangtze River in China, is an endangered fish species. The natural population has declined since the Gezhouba Dam blocked its migratory route to the spawning grounds in 1981. In the near future, the completion of the Three Gorges Dam, the world's largest hydroelectric project, may further impact this species by altering the water flow of the Yangtze River. Little is currently known about the population genetic structure of the Chinese sturgeon. In this study, DNA sequence data were determined from the control region (D-loop) of the mitochondrial genome of adult sturgeons (n = 106) that were collected between 1995-2000. The molecular data were used to investigate genetic variation, effective female population size and population history of the Chinese sturgeon in the Yangtze River. Our results indicate that the reduction in abundance did not change genetic variation of the Chinese sturgeon, and that the population underwent an expansion in the past. AMOVA analysis indicated that 98.7% of the genetic variability occurred within each year's spawning populations, the year of collection had little influence on the diversity of annual temporary samples. The relative large effective female population size (N-ef) indicates that good potential exists for the recovery of this species in the future. Strikingly, the ratio of N-ef to the census female population size (N-f) is unusually high (0.77-0.93). This may be the result of a current bottleneck in the population of the Chinese sturgeon that is likely caused by human intervention.

Mitochondrial DNA control region and cytochrome b sequence variation in the genus Mystacoleucus Gunther (Pisces : Cyprinidae : Barbinae) from China

Mitochondrial DNA (mtDNA) hypervariable segment I sequences (HVSI, 471 bp) of the control region and partial cytochrome b sequences (Cytb, 403 bp) were analyzed in three tentative species of the genus Mystacoleucus in China (M. chilopterus, M. marginatus, and M. lepturus). Not more than two mutations were found in both the HVSI and Cytb fragments among the samples from M. chilopterus and M. marginatus. However, M. lepturus differed from each of them by at least 25 mutations in Cytb and 51 mutations in HVSI. Moreover, the HVSI sequence variation within M. lepturus was larger than that between M. chilopterus and M. marginatus. Given that M. chilopterus and M. marginatus are very similar in morphology, it is reasonable to consider M. chilopterus and M. marginatus as conspecific. Our results also suggest a recent radiation of M. marginatus from downstream to upstream of the Lancangjiang (Mekong) River.

Intra- and interspecific variation of the CCR5 gene in higher primates

We have evaluated the molecular evolution of the chemokine receptor CCR5 in primates. The chemokine receptor CCR5 serves as a major co-receptor for human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) infection. Knowledge of evolution of the CCR5 molecule and selection on the CCR5 gene may shed light on its functional role. The comparison of differences between intraspecific polymorphisms and interspecific fixed substitutions provides useful information regarding modes of selection during the course of evolution. There is marked polymorphism in the CCR5 gene sequence within different primate species, whereas sequence divergence between different species is small. By using contingency tests, we compared synonymous (SS) and nonsynonymous (NS) CCR5 mutations occurring within and between a broad range of primates. Our results demonstrate that CCR5 evolution did not follow expectations, of strict neutrality at the level of the whole gene. The proportion of NS to SS at the intraspecific level was significantly higher than that observed at the interspecific level. These results suggest that most CCR5 NS polymorphisms are slightly deleterious. However, at domains more closely correlated with its known biological functions, there was no obvious evidence to support deviation from neutrality.

Mitochondrial variation of the "eyed" turtles (Sacalia) based on known-locality and trade specimens

Bryan L. Stuart is thanked for his hard work to collect wild specimens, as well as providing insightful and useful comments on the data. We thank Abigail Wolf of the Field Museum for providing photographs of specimens. Robert Murphy of the Royal Ontario M

Mitochondrial control region sequence variation within the argali wild sheep (Ovis ammon): evolution and conservation relevance

The phylogenetic relationship of several subspecies of Ovis ammon were analyzed by comparing DNA sequences within the entire mitochondrial D-loop region. Five putative subspecies of ammon (dalai-lamae, darwini, hodgsoni, sairensis and adamerzi) were sampled from four provinces in China [Xinjiang, Qinghai, Gansu and Xizang (Tibet)] and two (servertzovi and nigrimontana) from Uzbekistan. The argalis sampled represent most of the currently recognized putative Subspecies of argali. Analysis of mtDNA sequences revealed high variability within ammon (7.7%), ranging from 2.4 to 11.5%. MaxiMUM-Parsimony tree indicated that nigrimontana from Uzbekistan diverged First, followed by severtzovi from Uzbekistan. The dispersal of argalis into China gave rise to three clades, suggesting that the argali originated in Western Asia and then dispersed throughout the central Asian highlands on a southeastward course. Among the Chinese argalis, mtDNA analysis places dalailamae genetically closer to hodgsoni than to darwini. Severtzovi and.. nigrimontana are two separate subspecies and genetically distinct from the Chinese argali.

Lack of mtDNA control region variation in Hainan Eld's deer: Consequence of a recent population bottleneck?

We find no genetic variation at 550bp of mtDNA control region among 55 Hainan Eld's deer in an island population that has suffered recent population contractions. Congeneric species show high levels of variation at this locus. We use a simulation approach to test the likelihood of various bottleneck scenarios, and show, in the context of what is known about the recent demographic history of this population, that there are credible scenarios for a bottleneck driven by hunting pressure in the 1960s that could account for the lack of variation at this locus.

Species Variation in the Mechanisms of Mesenchymal Stem Cell-Mediated Immunosuppression

Bone marrow-derived mesenchymal stem cells (MSCs) hold great promise for treating immune disorders because of their immunoregulatory capacity, but the mechanism remains controversial. As we show here, the mechanism of MSC-mediated immunosuppression varies

Effect of variation in mesh size on trawl efficiency

Result of comparative fishing trials with a bulged belly design with three different mesh ranges in the body and wing to study the effect of mesh size difference on the performance of gear is discussed. While there is no significant difference in catch rate, predictably the 40 mm mesh size trawl fared wen when small sized fish like anchovies formed the major catch. The trawls with 60 and 80 mm mesh size gave better horizontal spread at a lower resistance showing savings in fuel.

Nucleotide variation and recombination along the fourth chromosome in Drosophila simulans

The fourth chromosome of Drosophila melanogaster and its sister species are believed to be nonrecombining and have been a model system for testing predictions of the effects of selection on linked, neutral variation. We recently examined nucleotide variat