Genetic differentiation in populations of the cestode Bothriocephalus acheilognathi (Cestoda, Pseudophyllidea) as revealed by eight microsatellite markers

The genetic structure of populations of the fish cestode, Bothriocephalus acheilognathi collected from Bailianhe Reservoir (BLH), Changshou (CSH) and Liangzi (LZH) Lakes was investigated by using 8 microsatellite loci. A total of 108 adult worms were genotyped at each of the 8 loci. For the 3 populations, the mean number of alleles per locus ranged from 2.38 to 5.5, and the mean expected heterozygosity ranged from 0.432 to 0.559. The average polymorphic information content (PIC) was from 0.384 to 0.492. The significant F-is values indicated non-random mating within LZH and BLH populations. On the other hand, when samples were further classified into subpopulations at the level of host fish species, no or little heterozygote deficiency was detected at most loci, showing that cross-fertilization, predominantly, but not exclusively, must have occurred within the subpopulations. Microsatellite markers also revealed an unexpected high level of genetic differentiation, as measured by R-st and N-m values or by deltau(2) genetic distance among subpopulations from different hosts. Factors influencing the population genetic structure and the parasite host specificity are discussed.

Long-term toxic impact of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the reproduction, sexual differentiation, and development of different life stages of Gobiocypris rarus and Daphnia magna

The sexual ratio of Gobiocypris rarus exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 17 beta -estradiol from embryo to sexually mature revealed feminization and overdevelopment of connective tissue in male fish gonad in 2-30 pg/L TCDD concentration range. Daphnia magna was not sensitive to the high dose of TCDD (0.1-1000 ng/ml), but the reproduction of D. magna treated with TCDD decreased after the 8th day. 7-Ethoxyresorufin-O-deethylase (EROD) activities in newly fertilized eggs of G. rarus exposed to TCDD dosage groups (1000-100,000 pg/L) were significantly induced and increased with TCDD concentrations at the early life stage, while no difference was found between low TCDD dosage groups (<100 pg/L), but a good relationship between the EROD activity and the TCDD concentration was observed during a long-term developmental stage. There was a pericardial edema formed in a 2-week yolk-sac at the concentration of 1000 pg/L TCDD. But in the exposure group (2 pg/L TCDD for 120 days), the cell nuclei of hepatocytes was far from the center and packed toward the cell membrane; the cristae of most mitochondria in the cell dropped and collapsed; the rough endoplasmic reticulum broke into fragments; and numerous lipid droplets formed in the cell. (C) 2001 Academic Press.

The influence of fractionation on cell survival and premature differentiation after carbon ion irradiation

Carbon ion radiotherapy/Fractionated irradiation/R-BE/Premature terminal differentiation. To investigate the influence of fractionation on cell survival and radiation induced premature differentiation as markers for early and late effects after X-rays and carbon irradiation. Normal human fibroblasts NHDF, AG1522B and WI-38 were irradiated With 250 kV X-rays, or 266 MeV/u, 195 MeV/u and I I MeV/u carbon ions. Cytotoxicity was measured by a clonogenic survival assay or by determination of the differentiation pattern. Experiments with high-energy carbon ions show that fractionation induced repair effects are similar to photon irradiation. The RBE10 values for clonogenic survival are 1.3 and 1.6 for irradiation in one or two fractions for NHDF cells and around 1.2 for AG1522B cells regardless of the fractionation scheme. The RBE for a doubling of post mitotic fibroblasts (PMF) in the population is I for both single and two fractionated irradiation of NHDF cells. Using I I MeV/u carbon ions, no repair effect can be seen in WI-38 cells. The RBE10 for clonogenic survival is 3.2 for single irradiation and 4.9 for two fractionated irradiations. The RBE for a doubling of PMF is 3.1 and 5.0 for single and two fractionated irradiations, respectively. For both cell lines the effects of high-energy carbon ions representing the irradiation of the skin and the normal tissue in the entrance channel are similar to the effects of X-rays. The fractionation effects are maintained. For the lower energy, which is representative for the irradiation of the tumor region. RBE is enhanced for clonogenic survival as well as for premature terminal differentiation. Fractionation effects are not detectable. Consequently, the therapeutic ratio is significantly enhanced by fractionated irradiation with carbon ions.

NDVI spatial pattern and its differentiation on the Mongolian Plateau

GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north, areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was indicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVI spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0.

Knocking-Down Cyclin A(2) by siRNA Suppresses Apoptosis and Switches Differentiation Pathways in K562 Cells upon Administration with Doxorubicin

Cyclin A(2) is critical for the initiation of DNA replication, transcription and cell cycle regulation. Cumulative evidences indicate that the deregulation of cyclin A(2) is tightly linked to the chromosomal instability, neoplastic transformation and tumor proliferation. Here we report that treatment of chronic myelogenous leukaemia K562 cells with doxorubicin results in an accumulation of cyclin A(2) and follows by induction of apoptotic cell death. To investigate the potential preclinical relevance, K562 cells were transiently transfected with the siRNA targeting cyclin A(2) by functionalized single wall carbon nanotubes. Knocking down the expression of cyclin A(2) in K562 cells suppressed doxorubicin-induced growth arrest and cell apoptosis. Upon administration with doxorubicin, K562 cells with reduced cyclin A(2) showed a significant decrease in erythroid differentiation, and a small fraction of cells were differentiated along megakaryocytic and monocyte-macrophage pathways. The results demonstrate the pro-apoptotic role of cyclin A(2) and suggest that cyclin A(2) is a key regulator of cell differentiation.