Genetic diversity affects productivity in early but not late stages of stand development

Recent declines in the genetic diversity of populations have stimulated research on the importance of genetic diversity for the functioning of natural communities. Current studies on this topic are based on the exploration of a limited number of clones and do not allow distinctions to be made between the effects of genetic identity and genetic diversity per se and to evaluate the effects of genetic diversity in genetically diverse communities. Also, most information comes from short-term studies, which are insufficient for evaluating the long-term effects relevant in relatively undisturbed communities of perennial species.We explored the importance of clone diversity vs. clone identity for stand productivity and the changes of the pattern over time. We used 18 clones of a perennial grass, Festuca rubra, to establish a set of communities composed of 1, 6 or 18 clones in two environments and studied the effects of genetic diversity on stand productivity over 3 years.Genetic diversity had a significant effect on stand productivity in the 1st year but not in the 2nd or 3rd year. In most cases, the observed yield was not significantly different from the total expected yield. The biomass of the mixtures never outperformed the biomass of the most productive clone, suggesting that clone identity is an important determinant of total biomass.The results indicate that the effects of genetic diversity on stand productivity may be transient and suggest that the conclusions of short-term studies on diversity effects should be evaluated carefully. They also suggest that individual clones are not complementary and that the properties of the stands are mainly additive results of the properties of the constituent clones.     

Automated egg-collecting and pupa-separator system for medfly mass-rearing facilities

The new automated egg-collecting system and pupa-separator device described here substantially reduces labour during medfly [ Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)] mass production. The egg-collecting system gathers eggs dropping from the cage's oviposition net into a continuous stream of water, after which they accumulate in an egg-collecting sieve. The system provides an optimal environment for eggs, keeping them in a slow stream of well-oxygenated water. A pupa separator was designed to enable the separation of pupae from the pupation medium by sucking off the medium through a slowly moving sieving belt. The smaller particles of pupation medium are removed by a vacuum cleaner located under the circular sieving belt, and the pupae are collected in a collecting box. Quality control tests of the eggs collected and pupae separated have shown that neither system has a negative effect on the quality of the eggs or the pupae.     

Decrease of dehydrogenase activity of cerebral glyceraldehyde-3-phosphate dehydrogenase in different animal models of Alzheimer's disease

Recently, a relationship between glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the β-amyloid precursor protein (βAPP) in relationship with the pathogenesis of Alzheimer's disease (AD) has been suggested. Therefore, we studied the specific activity of GAPDH in the different animal models of AD: transgenic mice (Tg2576) and rats treated with β-amyloid, or thiorphan, or lipopolysaccharides (LPS) and interferon γ (INFγ). We observed that GAPDH activity was significantly decreased in the brain samples from TG mice. The injection of β-amyloid, or thiorphan, an inhibitor of neprilysin involved in β-amyloid catabolism, in rat brains resulted in a pronounced reduction of the enzyme activity. The infusion of LPS and IFNγ, which can influence the progression of the AD, significantly reduced the enzyme activity.     

Prevalence of β-lactam and fluoroquinolone resistance, and virulence factors in Escherichia coli isolated from chickens in Slovakia

The incidence of infections due to organisms resistant to β-lactam antibiotics has increased sharply in recent years. The goal of this study was to investigate the β-lactam resistance in 151 Escherichia coli strains isolated from chickens over a two-year period. Extended spectrum β-lactamases (ESBLs) were present in 24 strains (16%), ESBL phenotype was identified by interpretative reading of minimal inhibitory concentration values of ceftriaxon (CRT ≥ 7.1 mg/L), ceftazidime (CAZ ≥ 3.4 mg/L) and ceftiofur (CFF ≥ 8.7 mg/L). PCR detection revealed the presence of the bla _CMY-2 gene and CTX-M-1 group. We detected high resistance to ampicillin (92%), streptomycin (63%), tetracyclin (70%), ceftiofur (40%), floroquinolones (enrofloxacin 68%, ciprofloxacin 62%), florfenicol (18%), chloramphenicol (21%) and cotrimoxazol (43%). We also investigated the presence of virulence factors and mobile genetic elements, and performed plasmid replicon typing in 24 selected strains. The most prevalent integrase among the isolates was the integrase 1 with gene cassettes dfrA, aadA and genes sul1 and sul2. Plasmid mediated quinolone resistances (qnrS) were also detected in two strains. Plasmid typing showed that the Y and IncI1 were dominant plasmid replicons. The genes iss, kpsII, tsh, iutA were the most frequently detected virulence genes in ESBL-positive strains. These results demonstrate that broilers in Slovakian food markets and farms could be the source of ESBL-producing E. coli, as well as virulent and resistant strains representing a potential risk for the human population.