Telomeric P elements associated with cytotype regulation of the P transposon family in Drosophila melanogaster

P elements inserted at the left end of the Drosophila X chromosome were isolated genetically from wild-type P strains. Stocks carrying these elements were tested for repression of P-strain-induced gonadal dysgenesis in females and for repression of transposase-catalyzed P-element excision in males and females. Both traits were repressed by stocks carrying either complete or incomplete P elements inserted near the telomere of the X chromosome in cytological region 1A, but not by stocks carrying only nontelomeric X-linked P elements. All three of the telomeric P elements that were analyzed at the molecular level were inserted in one of the 1.8-kb telomere-associated sequence (TAS) repeats near the end of the X chromosome. Stocks with these telomeric P elements strongly repressed P-element excision induced in the male germline by a P strain or by the transposase-producing transgenes H(hsp/CP)2, H(hsp/CP)3, a combination of these two transgenes, and P(ry(+), delta2-3)99B. For H(hsp/CP)2 and P(ry(+), delta2-3)99B, the repression was also effective when the flies were subjected to heat-shock treatments. However, these stocks did not repress the somatic transposase activity of P(ry(+), delta2-3)99B. Repression of transposase activity in the germline required maternal transmission of the telomeric P elements themselves. Paternal transmission of these elements, or maternal transmission of the cytoplasm from carriers, both were insufficient to repress transposase activity. Collectively, these findings indicate that the regulatory abilities of telomeric P elements are similar to those of the P cytotype.     

Approaches to interval mapping of QTL in a multigeneration pedigree: the example of porcine chromosome 4

Quantitative trait loci (QTLs) have been mapped in many studies of F2 populations derived from crosses between diverse lines. One approach to confirming these effects and improving the mapping resolution is genetic chromosome dissection through a backcrossing programme. Analysis by interval mapping of the data generated is likely to provide additional power and resolution compared with treating data marker by marker. However, interval mapping approaches for such a programme are not well developed, especially where the founder lines were outbred. We explore alternative approaches to analysis using, as an example, data from chromosome 4 in an intercross between wild boar and Large White pigs where QTLs have been previously identified. A least squares interval mapping procedure was used to study growth rate and carcass traits in a subsequent second backcross generation (BC2). This procedure requires the probability of inheriting a wild boar allele for each BC2 animal for locations throughout the chromosome. Two methods for obtaining these probabilities were compared: stochastic or deterministic. The two methods gave similar probabilities for inheriting wild boar alleles and, hence, gave very similar results from the QTL analysis. The deterministic approach has the advantage of being much faster to run but requires specialized software. A QTL for fatness and for growth were confirmed and, in addition, a QTL for piglet growth from weaning at 5 weeks up to 7 weeks of age and another for carcass length were detected.     

The occurrence of malolactic fermentation in brandy base wine and its influence on brandy quality

AIMS: In this study we determined the extent to which lactic acid bacteria (LAB) occurred in brandy base wines, their ability to catalyse the malolactic fermentation (MLF) and the effect of MLF on the quality of the base wine and the brandy distillate. METHODS AND RESULTS: Lactic acid bacteria were isolated and enumerated from grape juice, experimental and commercially produced brandy base wines. Spontaneous MLF occurred in approximately 50% of the commercial base wines. The occurrence of MLF had an influence on the quality of the base wines and the resulting distillates. In samples where MLF occurred there was a loss of fruitiness and in the intensity of aroma. Volatile compounds like iso-amyl acetate, ethyl acetate, ethyl caproate, 2-phenethyl acetate and hexyl acetate decreased in samples having undergone MLF, while ethyl lactate, acetic acid and diethyl succinate increased in the same samples. CONCLUSIONS: Spontaneous malolactic fermentation does occur in commercial brandy base wines and it has an influence on base wine and brandy quality. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed that MLF influences the quality of the base wine and the resulting distillate and with this in mind commercial base wine producers should be able to produce brandy of higher quality.     

Purification and characterization of a glucoamylase secreted by the plant pathogen Scierotinia sclerotiorum

Among the lytic enzymes secreted by the phytopathogen fungus Sclerotinia sclerotiorum, a starch-degrading enzyme has been isolated and characterized. This glycoprotein of 72 kDa is composed of several isoforms ranging from pI 4.8 to 5.4. The enzymatic parameters have been determined. Specificity studies together with the analysis of the reaction products show that it is an alpha-1,4-glucanohydrolase. This result is also corroborated by the analysis of the N-terminal and two inner amino acids sequences that are very similar to fungal glucoamylase genes or enzymes so far sequenced.     

Distinction between cultivated and wild chicory gene pools using AFLP markers

The cultivation area of industrial chicory, Cichorium intybus L. cv Sativum, coincides with the natural distribution area of its wild relative, C. intybus L., which could lead to gene flow between wild and cultivated types. The genetic diversity within and between the two types has therefore been studied using AFLP genotyping of samples from 12 wild populations collected in Belgium and ten commercial varieties. The genotyping of 233 individuals allowed the identification of 254 AFLP markers. Similar levels of genetic diversity were observed within wild populations and cultivated varieties, suggesting the absence of any strong bottleneck in the history of the cultivated types. The phylogenetic analysis pointed to a monophyletic origin of cultivated varieties as compared to the local wild populations studied, hence the two types of chicory form two separate gene pools. The genotyping of some individuals sampled in ruderal sites clearly showed that they belong to the cultivated gene pool, which suggests the existence of feral or weedy types. The low differentiation observed among wild populations indicates that gene flow might be important in this species.     

Analysis of IL-12 p40 subunit gene and IFN-γ G5644A polymorphisms in Idiopathic Pulmonary Fibrosis

Background

Genes encoding cytokine mediators are prime candidates for genetic analysis in conditions with T-helper (Th) cell disease driven imbalance. Idiopathic Pulmonary Fibrosis (IPF) is a predominantly Th2 mediated disease associated with a paucity of interferon-gamma (IFN-γ). The paucity of IFN-γ may favor the development of progressive fibrosis in IPF. Interleukin-12 (IL-12) plays a key role in inducing IFN-γ production. The aim of the current study was to assess whether the 1188 (A/C) 3'UTR single nucleotide polymorphism (SNP) in the IL-12 p40 subunit gene which was recently found to be functional and the 5644 (G/A) 3' UTR SNP of the IFN-γ gene were associated with susceptibility to IPF.

Methods

We investigated the allelic distribution in these loci in UK white Caucasoid subjects comprising 73 patients with IPF and 157 healthy controls. The SNPs were determined using the polymerase chain reaction in association with sequence-specific primers incorporating mismatches at the 3'-end.

Results

Our results showed that these polymorphisms were distributed similarly in the IPF and control groups

Conclusion

We conclude that these two potentially important candidate gene single nucleotide polymorphisms are not associated with susceptibility to IPF.     

Measurement of dissociation constants of inhibitors binding to Src SH2 domain protein by non-covalent electrospray ionization mass spectrometry

A mass spectrometric protocol for identifying ligands with a wide range of affinities (3-101 microM) and quantitative spectral analysis for non-covalent interactions have been developed using Src SH2 as a target. Dissociation constants of five compounds, three with a phospho moiety, one with a sulphonic acid group and one with carboxylic acid groups only, were determined using one-ligand one-binding-site, two-ligands one-binding site and one-ligand two-binding-sites models. The Kd values determined by ESI-MS of the three compounds containing the phospho moiety (3.2-7.9 microM) were comparable to those obtained from a solution equilibrium fluorescence polarization assay. The compound with a sulphonate group is a much weaker binding ligand (Kd=101 microM by ESI, >300 microM by FP) towards the Src SH2 protein. Two complexes with different stoichiometric ratios 1:1 and 2:1 (ligand-protein) were observed by ESI-MS for the ligand GIXXX630X. Analysis of binding isotherms indicated the presence of two binding sites for the ligand with Kd values of 9.3 and 193 microM. These data confirmed that, for these polar compounds, non-covalent ESI-MS can measure affinity which very closely reflects the affinity measured under true solution equilibrium conditions. ESI-MS has several key advantages over many solution methods: it can identify the existence of and measure the affinity of complexes other than simple 1:1 ligand-enzyme complexes. Moreover, ESI-MS competition experiments can be readily performed to yield data on whether two ligands bind simultaneously or competitively at the same time as measuring the affinity of the ligand.