pH track of expanding bacterial populations

A method of pH distribution measurements in agar nutrient media containing expanding bacterial populations is described. It is based on measuring pH microsamples taken at different points of the media. The sample volume was 10 microliters. A pH sensitive field effect transistor was used as a measuring electrode. Acidification was found to occur in glucose media, while alkalization occurred in the media containing peptone.     

Genetic variation for foot-rot and Fusarium head-blight resistances among full-sib families of a self-incompatible winter rye (Secale cereale L.) population

The amount of genetic variation for resistance to foot rot caused by Pseudocercosporella herpotrichoides, Fusarium spp., and Microdochium nivale and for resistance to head blight caused by Fusarium culmorum are important parameters when estimating selection gain from recurrent selection in winter rye. One-hundred and eighty-six full-sib families of the selfincompatible population variety Halo, representing the Petkus gene pool, were tested for foot-rot resistance at five German location-year combinations (environments) and for head-blight resistance in three environments with artificial inoculation in all but one environment. Foot-rot rating was based on 25 stems per plot scored individually on a 1–9 scale. Head-blight resistance was plotwise scored on a 1–9 scale and, additionally, grain-weight per spike was measured relative to the non-inoculated control plots. Significant estimates of genotypic variance and medium-sized heritabilities (h ²=0.51–0.69) were observed in the combined analyses for all resistance traits. In four out of five environments, the amount of genetic variance was substantially smaller for foot-rot than for head-blight rating. Considerable environmental effects and significant genotype-environment interactions were found for both foot-rot and head-blight resistance. Coefficients of error-corrected correlation among environments were considerably closer than phenotypic correlations. No significant association was found between the resistances to both diseases (r=-0.20 to 0.17). In conclusion, intra-population improvement by recurrent selection should lead to substantial higher foot-rot and head-blight resistances due to significant quantitative genetic variation within Halo. Selection should be carried out in several environments. Lack of correlation between foot-rot and head-blight resistance requires separate infection tests for improving both resistances.     

Genetic variation of Sherardia arvensis L. – How land use and fragmentation affect an arable weed

The distribution of arable weeds extends over regions, where the species occur naturally in different kinds of habitats and regions, where they are mainly limited to arable fields.Here, we present a comparative study on the genetic structure of the arable weed Sherardia arvensis L. comprising populations from Mediterranean grasslands in Southern France and populations from arable fields in Germany. Enhanced by intensified land use since the 1960th, overall population density in Germany is very low compared to the density of populations in Southern France. We tested whether genetic variation within and among populations differ between France and Germany due to different patterns of distribution and land use. Therefore, we analysed 231 individuals of S. arvensis from 24 populations using AFLPs. Based on fragment analysis data we compared spatial genetic structure and genetic variation of populations from the two regions.Genetic variation within populations from the two regions (Shannon Index = 0.13 for both) and genetic variation among populations (26.8% and 30.0% in an analysis of molecular variance) were comparable. In both regions a drift-migration model supported the assumption of gene flow between populations. However, a clear correlation of geographical and genetic distances could only be reported for the indigenous populations from France (r = 0.46; P = 0.02), whereas in Germany a spatial genetic relationship between populations was missing (r = 0.16; P = 0.21).Our study revealed that neither French nor German populations are genetically impoverished. For French populations further the spatial genetic structure suggests that there is current gene flow between populations through pollinators and seed dispersal by cattle. For German populations comparable levels of genetic diversity and gene flow were detected, but gene flow was random. This can be traced back in all likelihood to diffuse dispersal by agriculture and the mechanical reshuffling of the individuals from the soil seed bank.     

Low mtDNA Cytb diversity and shallow population structure of Eleutheronema tetradactylum in the East China Sea and the South China Sea

Eleutheronema tetradactylum is an economically important fish species in China water. To investigate the genetic diversity and describe population structure of it, an 1151 base pair (bp) fragment of the mitochondrial DNA Cytb sequence was analyzed in 120 individuals from four populations in the East China Sea and the South China Sea. A total of 16 haplotypes were defined by 24 variable nucleotide sites. High level of haplotype diversity and low nucleotide diversity were observed in all populations. The results of AMOVA detected that 89.44% of the genetic variation occurred within populations. Significant genetic differentiations were detected among populations (0.05097, P < 0.05), but no large-scale regional differences were detected. Analysis of neutral evolution and mismatch distribution suggested no recent population expansion happened. The present results provided new information for genetic assessment, fishery management and conservation of this species.     

Discovering Precise Temporal Patterns in Large-Scale Neural Recordings through Robust and Interpretable Time Warping

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Mitochondrial DNA variation and population genetic structure in the small yellow croaker at the coast of Yellow Sea and East China Sea

Small yellow croaker is one of the most important fishery species in China. The mass–scale artificial propagation of this fish species was initially developed in 2015 with the aim of facilitating the fish production stock enhancement and aquaculture programs in the future. In the present study, the wild broodfish and its corresponding progeny along with three other wild populations were sampled and subjected to sequence analysis of the mitochondrial cytochrome c oxidase subunit I gene. The genetic diversity and population genetic structure were evaluated with a total sample size of 141 individuals representing the populations of the Yellow Sea (Qingdao and Lvsi populations) and the East China Sea (Xiangshan and Ningde populations). The wild populations were characterized by high haplotype diversity (0.925–0.976) and low nucleotide diversity (0.376%–0.560%). The hierarchical analysis of molecular variance (AMOVA) analysis and the values of pairwise Ф-statistics (Ф_ST) indicated non-significant genetic differentiation among the four wild populations. The hatchery stock XSH exhibited lower indices of genetic diversity compared with the wild populations that could be attributed to the small effective population size. The findings of the present study have valuable insight to the sustainable management and utilization of this resource.     

Population-level cure of colorectal cancer in Malta: An analysis of patients diagnosed between 1995 and 2004

AimThe aim of this study was to estimate the population-level ‘cure’ of Maltese colorectal cancer patients diagnosed between 1995 and 2004, and to estimate the median survival time for the ‘uncured’ patients.Methods and study populationAnalysis was conducted on 1470 cases registered by the Malta National Cancer Register between 1995 and 2004 and followed up to end of 2010. The mean age of the patients was 66.4 (95%CI 65.8–67.1), and the number of men and women were equal. Background mortality for 1995–2010 was extracted from publicly available life tables. A mixture model with Weibull survival distribution and identity link was used to model ‘cure’.ResultsThe overall ‘cured’ proportion for the patients diagnosed in 1995–1999 was 45.3% (95%CI 40.2–50.5) while the ‘cured’ proportion for the patients diagnosed in 2000–2004 was 52.3% (95%CI 47.2–57.5). Median survival time for the ‘uncured’ patients increased in the second calendar period from 1.25 years (95%CI 1.04–1.45) to 1.42 years (95%CI 1.15–1.76).ConclusionIn Malta, as in the rest of Europe, improvements have been made in short- and long-term survival over the 15-year period under study. To continue this improvement, differences by age that still persist must be investigated and efforts focused to reduce any gaps between Malta and other European countries.     

Genetic differentiation of Elysia timida (Risso, 1818) populations in the Southwest Mediterranean and Mar Menor coastal lagoon

Genetic variation at 10 enzyme loci was analysed in Elysia timida sacoglossan mollusc samples, originating from both coastal lagoon and marine sites. The observed heterozygosity ranged from 0.390 (Los Urrutias) to 0.277 (Tabarca). Marine and coastal lagoon populations were characterised by exclusive alleles.     

Maintaining diversity in an artificially propagated population

Populations may suffer unexpected loss or distortion of biodiversity as a consequence of strategies employed in artificial propagation programs. The Trinity River Fish Hatchery may have inadvertently experienced this while attempting to preserve diversity in a return time within a Chinook salmon population. We develop a model for this system and prove that the long-term distribution of return types converges and that it is strongly tied to the management strategy. Given estimates of heritabilities for return type and differential survival rates, an estimate of this long-term distribution can be computed easily.