Allelic polymorphism of the CGG repeat region in the <Emphasis Type="Italic">FMR1</Emphasis> gene in patients with impaired natural and stimulated ovulation

The frequency of heterozygote carriers of risk zone alleles of the FMR1 gene (40–47 CGG repeats) was significantly higher in the group of patients with ovarian dysfunctions compared to control group I. The frequency of these alleles shows an increasing tendency in patients poorly responding to superovulation induction in IVF cycles. The average number of oocytes and follicles obtained from the stimulation of superovulation was significantly decreased in FMR1 gene heterozygous risk zone allele carriers as compared to patients with normal alleles of the FMR1 gene. The general average dosage of exogenous gonadotrophin necessary for superovulation induction was significantly higher in heterozygote carriers of FMR1 gene risk zone alleles than in patients with normal genotype. As well, the FMR1 gene risk zone alleles can be one of the hereditary susceptibility factors of impaired natural and stimulated ovulation.     

Microbial community shifts influence patterns in tropical forest nitrogen fixation

The role of biodiversity in ecosystem function receives substantial attention, yet despite the diversity and functional relevance of microorganisms, relationships between microbial community structure and ecosystem processes remain largely unknown. We used tropical rain forest fertilization plots to directly compare the relative abundance, composition and diversity of free-living nitrogen (N)-fixer communities to in situ leaf litter N fixation rates. N fixation rates varied greatly within the landscape, and ‘hotspots’ of high N fixation activity were observed in both control and phosphorus (P)-fertilized plots. Compared with zones of average activity, the N fixation ‘hotspots’ in unfertilized plots were characterized by marked differences in N-fixer community composition and had substantially higher overall diversity. P additions increased the efficiency of N-fixer communities, resulting in elevated rates of fixation per nifH gene. Furthermore, P fertilization increased N fixation rates and N-fixer abundance, eliminated a highly novel group of N-fixers, and increased N-fixer diversity. Yet the relationships between diversity and function were not simple, and coupling rate measurements to indicators of community structure revealed a biological dynamism not apparent from process measurements alone. Taken together, these data suggest that the rain forest litter layer maintains high N fixation rates and unique N-fixing organisms and that, as observed in plant community ecology, structural shifts in N-fixing communities may partially explain significant differences in system-scale N fixation rates.     

Behavioural Ecology: Niche Construction via Grooming and Extortion?

A recent study shows that brood parasitic cowbirds employ Mafia-like tactics to discourage rejection of their broods by a common host. This may be a new example of animals adaptively 'constructing' key features of their ecological niches.     

Invertebrate neurobiology: sensory processing in reverse for backward walking

Humans and many other animals can readily walk forward or backward. In insects, the nervous system changes the effects of sense organs that signal forces on a leg when the direction of walking is reversed.     

Express hybridization of molecular colonies with fluorescent probes

DNA colonies formed during PCR in a polyacrylamide gel and RNA colonies grown in an agarose gel containing Qβ replicase can be identified using the procedure of transfer of molecular colonies onto a nylon membrane followed by membrane hybridization with fluorescent oligonucleotide probes. The suggested improvements significantly simplify and shorten the procedure. By the example of a chimeric AML1-ETO sequence, a marker of frequently occurring leukemia, the express hybridization method was shown to allow the rapid identification of single molecules and the determination of titers of DNA and RNA targets. Hybridization with a mixture of two oligonucleotide probes labeled with different fluorophores complementary to components of the chimeric molecule ensures the identification of molecular colonies containing both parts of the chimeric sequence and improves the specificity of diagnostics.     

Assessing plant-nutrient relationships in highly invaded Californian grasslands using non-normal probability distributions

Question: Is native species occurrence related to soil nutrients in highly invaded Californian annual grasslands? What is the best method to analyze this relationship, given that native species occur in very low numbers and are absent from many locations? Location: California, USA. Methods: We investigated the effects of soil characteristics and livestock grazing on native plant occurrence at 40 plots from six sites during the period 2003–2005. Low absolute cover (< 5.8%) of native species resulted in strongly skewed, zero-inflated data sets. To overcome problems in the analysis created by non-normality and correlations within plots, we used GLMs and GLMMs, either with a Poisson or a negative binomial distribution, to analyse native species richness and Nassella pulchra cover. Results: N. pulchra cover was strongly associated with low phosphorus in sandy soils, whereas native species richness was highest in soils with low available nitrogen (high C:N). Conclusion: Under current conditions, phosphorus seems to be a critical factor influencing abundance of N. pulchra. Low fertility soils may provide refugia for native species in highly invaded California grasslands as they may be below a threshold required for non-native annuals to completely dominate. By using non-normal distributions in linear models with random components, we report well fitted models with more accurately tested significant covariates.     

Oncolytic Viruses in the Therapy of Lymphoproliferative Diseases

Molecular Biology - Cancer is a leading causes of death. Despite significant success in the treatment of lymphatic system tumors, the problems of relapse, drug resistance and effectiveness of...