Phenotypic variation in infectivity of Diplostomum spathaceum cercariae within a population

The present study examined phenotypic variation in infectivity of Diplostomum spathaceum (Trematoda) cercariae within a natural population. Twelve infected Lymnaea stagnalis were collected from the field, and the infectivity of cercariae from individual snails was assessed under constant laboratory conditions. At a water temperature of 16.3 C, the mean infectivity of cercariae from the snails varied between 55.5% and 87.5%. Depending on the source of variation, this may have important ecological and evolutionary implications for both natural parasite populations and those occurring in aquaculture.     

WDR12, a Member of Nucleolar PeBoW-Complex,Is Up-Regulated in Failing Hearts and Causes Deterioration of Cardiac Function

Aims

In a recent genome-wide association study, WD-repeat domain 12 (WDR12) was associated with early-onset myocardial infarction (MI). However, the function of WDR12 in the heart is unknown.

Methods and Results

We characterized cardiac expression of WDR12, used adenovirus-mediated WDR12 gene delivery to examine effects of WDR12 on left ventricular (LV) remodeling, and analyzed relationship between MI associated WDR12 allele and cardiac function in human subjects. LV WDR12 protein levels were increased in patients with dilated cardiomyopathy and rats post-infarction. In normal adult rat hearts, WDR12 gene delivery into the anterior wall of the LV decreased interventricular septum diastolic and systolic thickness and increased the diastolic and systolic diameters of the LV. Moreover, LV ejection fraction (9.1%, P<0.05) and fractional shortening (12.2%, P<0.05) were declined. The adverse effects of WDR12 gene delivery on cardiac function were associated with decreased cellular proliferation, activation of p38 mitogen–activated protein kinase (MAPK)/heat shock protein (HSP) 27 pathway, and increased protein levels of Block of proliferation 1 (BOP1), essential for ribosome biogenesis. Post-infarction WDR12 gene delivery decreased E/A ratio (32%, P<0.05) suggesting worsening of diastolic function. In human subjects, MI associated WDR12 allele was associated significantly with diastolic dysfunction and left atrial size.

Conclusions

WDR12 triggers distinct deterioration of cardiac function in adult rat heart and the MI associated WDR12 variant is associated with diastolic dysfunction in human subjects.     

Identification of amino acids important for substrate specificity in sucrose transporters using gene shuffling

Plant sucrose transporters (SUTs) are H(+)-coupled uptake transporters. Type I and II (SUTs) are phylogenetically related but have different substrate specificities. Type I SUTs transport sucrose, maltose, and a wide range of natural and synthetic α- and β-glucosides. Type II SUTs are more selective for sucrose and maltose. Here, we investigated the structural basis for this difference in substrate specificity. We used a novel gene shuffling method called synthetic template shuffling to introduce 62 differentially conserved amino acid residues from type I SUTs into OsSUT1, a type II SUT from rice. The OsSUT1 variants were tested for their ability to transport the fluorescent coumarin β-glucoside esculin when expressed in yeast. Fluorescent yeast cells were selected using fluorescence-activated cell sorting (FACS). Substitution of five amino acids present in type I SUTs in OsSUT1 was found to be sufficient to confer esculin uptake activity. The changes clustered in two areas of the OsSUT1 protein: in the first loop and the top of TMS2 (T80L and A86K) and in TMS5 (S220A, S221A, and T224Y). The substrate specificity of this OsSUT1 variant was almost identical to that of type I SUTs. Corresponding changes in the sugarcane type II transporter ShSUT1 also changed substrate specificity, indicating that these residues contribute to substrate specificity in type II SUTs in general.     

Production of mold lactase

A process for production of mold lactase was developed. Tests were carried out in pilot and industrial scale with an Aspergillus niger strain selected after screening a number of molds.A computer coupled autoanalyzer system was used for monitoring enzyme formation in the pilot fermentor. Lactase production was investigated using different pH- and temperature-profiles. A. niger lactase has an acid pH optimum, a high temperature optimum and good stability. It does not require any metal ions. It is suitable for immobilization for hydrolysis of lactose in acid whey.Three-fold enhancement of lactase production was obtained by mutagenizing A. niger using NTG as mutagenic agent.The lactases produced by the mutants have the same pH and temperature optima and stability but the growth properties of the mutants were different from those of the original strain.Sufficient specific activity of the enzyme preparation for immobilization was obtained by purifying the enzyme by selective adsorption on Na-Ca-silicate.     

Do molecular markers reflect patterns of differentiation in adaptive traits of conifers?

We have examined patterns of variation of several kinds of molecular markers (isozymes, RFLPs of ribosomal DNA and anonymous low-copy number DNA, RAPDs and microsatellites) and an adaptive trait [date of bud set in Scots pine (Pinus sylvestris L.)]. The study included Finnish Scots pine populations (from latitude 60°N to 70°N) which experience a steep climatic gradient. Common garden experiments show that these populations are adapted to the location of their origin and genetically differentiated in adaptive quantitative traits, e.g. the date of bud set in first-year seedlings. In the northernmost population, bud set took place about 21 days earlier than in the southernmost population. Of the total variation in bud set, 36.4% was found among the populations. All molecular markers showed high levels of within-population variation, while differentiation among populations was low. Among all the studied markers, microsatellites were the most variable (H_e=0.77). Differences between populations were small, G_ST was less than 0.02. Our study suggests that molecular markers may be poor predictors of the population differentiation of quantitative traits in Scots pine, as exemplified here by bud-set date.     

Population genetic structure in the Temminck’s stint <Emphasis Type="Italic">Calidris temminckii</Emphasis>, with an emphasis on Fennoscandian populations

Temminck’s stint breeds in Eurasian arctic tundra and subarctic and temperate boreal zones in a range extending from Fennoscandia to easternmost Siberia. In contrast to the favourable global conservation status of the species, it has been classified as vulnerable in Finland and near threatened in Sweden. A fragment of the control region of mtDNA was sequenced from 127 individuals from breeding areas in Fennoscandia in the west (three populations) and in the eastern end of the range. The mtDNA variability and structuring were among the lowest values reported for waders (F _ST −0.02616). The mtDNA sequences revealed seven haplotypes, of which four were present in single individuals. The most common haplotype occurred in 81% of all individuals and in all birds in the Siberian sample. There was evidence of two maternal lineages. The most common lineage occurred in 95% of the individuals and was the only one present in the Siberian sample. The lineages coexisted in all three Fennoscandian populations, indicating a secondary contact of two previously isolated populations. The mtDNA variation and the mitochondrial nucleotide and haplotype diversities indicated panmixis of the populations. However, a higher degree of population differentiation was detected in microsatellite allele frequencies (125 birds, six loci) in Fennoscandia between the Bothnian Bay population and the two inland populations (Lapland and southern Norway). The difference may be caused by the female-biased dispersal pattern of the species. In addition, the Bothnian Bay population appeared to be genetically bottlenecked, an observation in concordance with the recent decimation of the population.     

Relaxin-3 and RXFP3 expression, and steroidogenic actions in the ovary of teleost fish

Relaxins are peptides similar in secondary structure to insulins. In teleost genomes, five or six relaxin genes have been identified. Two relaxins group closely with mammalian relaxin-3 on phylogenetic analysis and are named relaxin-3a and b. We refer to the remainder as relaxins c to f. Ovarian expression of relaxin-3a, d and f genes, and the relaxin-3 receptor gene Rxfp3, was studied in Danio rerio using RT-PCR. Immunohistochemistry was used to determine the distribution of relaxin-3 peptides and RXFP3 in the ovary of Fundulus heteroclitus (killifish). Thirdly, enzyme immunoassays and ovarian follicular culture were used to determine the effect of treatment with human recombinant relaxin-3 on the production of 17beta-estradiol and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one in killifish ovarian follicles. Relaxin-3a, d, f, and Rxfp3 genes were expressed regardless of sex or reproductive condition. Relaxin-3 immunostaining was present in mid to late follicular stages within cortical alveoli of the oocyte cytopasm, whereas receptor staining was localized to follicular cells. Treatment with relaxin-3 enhanced 17beta-estradiol production in early and late maturing follicles, but did not have an effect in vitellogenic follicles. Relaxin-3 appeared to suppress the release of MIS production. This suggests that relaxin peptides may be involved with estradiol-dependant events in follicular development.