Effects of GABA(A) receptor modulation on the expression of GnRH gene and GnRH receptor (GnRH-R) gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland of follicular-phase ewes

The effect of prolonged, intermittent infusion of GABA(A) receptor agonist (muscimol) or GABA(A) receptor antagonist (bicuculline) into the third cerebral ventricle on the expression of GnRH gene and GnRH-R gene in the hypothalamus and GnRH-R gene in the anterior pituitary gland was examined in follicular-phase ewes by real-time PCR. The activation or inhibition of GABA(A) receptors in the hypothalamus decreased or increased the expression of GnRH and GnRH-R genes and LH secretion, respectively. The present results indicate that the GABAergic system in the hypothalamus of follicular-phase ewes may suppress, via hypothalamic GABA(A) receptors, the expression of GnRH and GnRH-R genes in this structure. The decrease or increase of GnRH-R mRNA in the anterior pituitary gland and LH secretion in the muscimol- or bicuculline-treated ewes, respectively, is probably a consequence of parallel changes in the release of GnRH from the hypothalamus activating GnRH-R gene expression. It is suggested that GABA acting through the GABA(A) receptor mechanism on the expression of GnRH gene and GnRH-R gene in the hypothalamus may be involved in two processes: the biosynthesis of GnRH and the release of this neurohormone in the hypothalamus.     

Helicobacter pylori Infection and Family History of Gastric Cancer Decrease Expression of FHIT Tumor Suppressor Gene in Gastric Mucosa of Dyspeptic Patients

Background:  The expression of a fragile histidine triad (FHIT) protein is lost in stomach tumors. The study aimed at determining whether FHIT expression is affected by Helicobacter pylori infection, strain virulence ( vacA and cagA genes) and histopathological changes in the gastric mucosa of patients with functional dyspepsia having first-degree relatives with gastric cancer.
Materials and Methods:  Eighty-eight never-smoking patients with functional dyspepsia were selected for the study, and 48 of them had first-degree relatives with gastric cancer. Bacterial DNA amplification was used to identify H. pylori colonization. The level of FHIT gene expression was determined by qRT-PCR (mRNA) and Western blot (FHIT protein) analyses.
Results:  For patients having first-degree relatives with gastric cancer FHIT expression was lower (mRNA by ca. 40–45% and protein by 30%) compared with the control patients ( p  < .05). H. pylori infection decreased the FHIT mRNA level by 10–35% and the protein level by 10–20%. Bacterial strain vacA (+) cagA (+) lowered FHIT mRNA by ca. 30–35% in the antrum samples of both groups and in corpus samples of patients with first-degree relatives with gastric cancer ( p  < .05). The FHIT mRNA level was twice as high in control H. pylori- negative patients with intestinal metaplasia, compared with those with non-atrophic gastritis.
Conclusions:  The decreased FHIT gene expression associated with hereditary factors and with H. pylori infection, especially with vacA (+) cagA (+)-positive strains, may be related to gastric carcinoma development.     

Perturbation of the lipid phase of a membrane is not involved in the modulation of MRP1 transport activity by flavonoids

The expression of transmembrane transporter multidrug resistance-associated protein 1 (MRP1) confers the multidrug-resistant phenotype (MDR) on cancer cells. Since the activity of the other MDR transporter, P-glycoprotein, is sensitive to membrane perturbation, we aimed to check whether the changes in lipid bilayer properties induced by flavones (apigenin, acacetin) and flavonols (morin, myricetin) were related to their MRP1 inhibitory activity. All the flavonoids inhibited the efflux of MRP1 fluorescent substrate from human erythrocytes and breast cancer cells. Morin was also found to stimulate the ATPase activity of erythrocyte ghosts. All flavonoids intercalated into phosphatidylcholine bilayers as judged by differential scanning calorimetry and fluorescence spectroscopy with the use of two carbocyanine dyes. The model of an intramembrane localization for flavones and flavonols was proposed. No clear relationship was found between the membrane-perturbing activity of flavonoids and their potency to inhibit MRP1. We concluded that mechanisms other than perturbation of the lipid phase of membranes were responsible for inhibition of MRP1 by the flavonoids.     

Phthalazinones 2: Optimisation and synthesis of novel potent inhibitors of poly(ADP-ribose)polymerase

We have previously described the discovery of poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors based on a phthalazinone scaffold. Subsequent optimisation of inhibitory activity, metabolic stability and pharmacokinetic parameters has led to a novel series of meta-substituted 4-benzyl-2H-phthalazin-1-one PARP-1 inhibitors which retain low nM cellular activity and show good stability in vivo and efficacy in cell based models.     

Ecological factors influence population genetic structure of European grey wolves

Although the mechanisms controlling gene flow among populations are particularly important for evolutionary processes, they are still poorly understood, especially in the case of large carnivoran mammals with extensive continuous distributions. We studied the question of factors affecting population genetic structure in the grey wolf, Canis lupus, one of the most mobile terrestrial carnivores. We analysed variability in mitochondrial DNA and 14 microsatellite loci for a sample of 643 individuals from 59 localities representing most of the continuous wolf range in Eastern Europe. We tested an array of geographical, historical and ecological factors to check whether they may explain genetic differentiation among local wolf populations. We showed that wolf populations in Eastern Europe displayed nonrandom spatial genetic structure in the absence of obvious physical barriers to movement. Neither topographic barriers nor past fragmentation could explain spatial genetic structure. However, we found that the genetic differentiation among local populations was correlated with climate, habitat types, and wolf diet composition. This result shows that ecological processes may strongly influence the amount of gene flow among populations. We suggest natal-habitat-biased dispersal as an underlying mechanism linking population ecology with population genetic structure.     

Phenotypic landscape of a bacterial cell

The explosion of sequence information in bacteria makes developing high-throughput, cost-effective approaches to matching genes with phenotypes imperative. Using E. coli as proof of principle, we show that combining large-scale chemical genomics with quantitative fitness measurements provides a high-quality data set rich in discovery. Probing growth profiles of a mutant library in hundreds of conditions in parallel yielded > 10,000 phenotypes that allowed us to study gene essentiality, discover leads for gene function and drug action, and understand higher-order organization of the bacterial chromosome. We highlight new information derived from the study, including insights into a gene involved in multiple antibiotic resistance and the synergy between a broadly used combinatory antibiotic therapy, trimethoprim and sulfonamides. This data set, publicly available at http://ecoliwiki.net/tools/chemgen/, is a valuable resource for both the microbiological and bioinformatic communities, as it provides high-confidence associations between hundreds of annotated and uncharacterized genes as well as inferences about the mode of action of several poorly understood drugs.     

Microsatellite identification of ramet genotypes in a clonal plant with phalanx growth: The case of Cirsium rivulare (Asteraceae)

Cirsium rivulare is a perennial plant that forms patches consisting of ramets resulting from sexual reproduction by seeds and asexual propagation by rhizome fragmentation. We examined the relationship between the size of patches and genetic differentiation of ramets within and between patches. Ramet genotypes were identified using microsatellites. From among 216 ramets examined in the studied population, 123 had a unique genotype, while 93 were clonal, i.e., their genotype was present in at least two ramets. The frequency of ramets with clonal genotypes was 43% and the frequency of unique genotypes was 57%. Ramets with identical genotypes were dominant in small patches. Large patches consisted of ramets with both unique and clonal genotypes, usually with the predominance of the latter. A molecular variance analysis showed the highest level of variance between ramets and the lowest between patches. Additionally, 21.02% of the total variance was recorded between ramets and within patches. The size of patches was correlated with the number of clonal ramets and the number of unique ramets, but it was not correlated with the clonality index. This population of C. rivulare is currently in a phase of decline from 30 years of vegetation transformation, and there appears to have been an increase in sexual propagation based growth over clonal propagation based growth. Hence, a predominance of ramets with unique genotypes was observed. This can happen as a result of disintegration of large patches and formation of gaps between them. These gaps become convenient places for seed germination and the subsequent development of seedlings.