Acid and alkaline phosphatase in macrophages of Tenebrio molitor larvae stimulated with asbestos

The authors studied the activity of acid and alkaline phosphatase in macrophages of Tenebrio molitor larvae stimulated with various types of asbestos: A and B chrysotile, crocidolite, amosite and anthophylite. The activity of the two enzymes increased, as did those of beta-galactosidase and N-acetyl-beta-D-glucosaminidase, two previously assayed enzymes. The increase indicates the toxic action of various types of asbestos and correlates to variations in the mortality curves. The increases of the enzymatic activity and the macrophage response vary with the type of asbestos.     

Feasibility study of detecting surface electromyograms in severely obese patients

The aims of this study were to examine if surface EMG signals can be detected from the quadriceps femoris muscle of severely obese patients and to investigate if differences exist in quadriceps force and myoelectric manifestations of fatigue between obese patients and lean controls.Fourteen severely obese patients (body mass index, BMI, mean ± SD: 44.9 ± 6.3 kg/m²) and fourteen healthy controls (BMI: 23.7 ± 2.5 kg/m²) were studied. The vastus medialis and lateralis of the dominant thigh were concurrently investigated during voluntary isometric contractions (10-s long at submaximal and maximal intensities and intermittent submaximal contractions until exhaustion) and sustained (120-s long) electrically elicited contractions.We found that the detection of surface EMG signals from the quadriceps is feasible also in severely obese subjects presenting increased thickness of the subcutaneous fat tissue. In addition, we confirmed and extended previous findings showing that the volume conductor properties determine the amplitude and spectral features of the detected surface EMG signals: the lower the subcutaneous tissue thickness, the higher the amplitude and mean frequency estimates. Further, we found no differences in the mechanical and myoelectric manifestations of fatigue during intermittent voluntary and sustained electrically elicited contractions between obese patients and lean controls.     

Roe and fallow deer: are they compatible neighbours?

The analysis of the relationships between population density and habitat features is important to evaluate the ecological needs of a species, its potential impact on ecosystems and its interspecific interactions. We analysed the spatial variation of roe deer Capreolus capreolus and fallow deer Dama dama densities in a Mediterranean area in summer 2007 and winter 2007/2008. Previous research has shown that fallow deer can actively displace and exclude roe deer from natural feeding sites. Here we show that both species have the greatest densities in ecotone habitats between wood and open fields (abandoned olive groves and pastures), but with contrasting geographic patterns. The fallow deer showed the greatest densities in the central northern part of the study area near to local historical release sites. The densities of roe deer were great where fallow deer were rare and low where fallow deer were abundant. Spatial overlap was great at the habitat scale, indicating a high potential for competition, but was low at the plot scale, suggesting that partitioning of space occurred at a fine scale. Supporting great numbers of deer, the ecotone areas are crucial for the management of ecosystems. We suggest that roe deer avoid areas with great densities of fallow deer and that interspecific interference from the latter affects the density and distribution of the former both at a fine and at a large scale.     

Ethanol-mediated long-lasting adaptations of the NR2B-containing NMDA receptors in the dorsomedial striatum

We recently found that ethanol-induced long-term facilitation (LTF) of NMDAR activity is mediated by NR2B-NMDARs and is observed in the dorsomedial striatum (DMS) but not in the dorsolateral striatum (DLS). We also showed that repeated administration of ethanol causes a long-lasting increase in NMDAR activity in the DMS, resulting from ethanol-mediated Fyn phosphorylation of NR2B subunits. In this addendum, we report that the different sensitivity of NMDARs to ethanol between the DMS and DLS is not attributed to the abundance of synaptic NR2B-NMDARs or differences in Fyn levels. We further show that LTF is specific for NR2B-, but not NR2A-NMDARs, and that the duration of the in vivo ethanol-mediated increase in NMDAR activity is associated with the period of ethanol exposure, but not with alteration in NR1 or NR2A protein levels. Together, these results suggest that upregulation of NR2B-NMDAR activity by ethanol is selective and that ethanol's effect on NMDAR activity is gradual and cumulative.     

A pool of peptides extracted from wheat bud chromatin inhibits tumor cell growth by causing defective DNA synthesis

Background

We previously reported that a pool of low molecular weight peptides can be extracted by alkali treatment of DNA preparations obtained from prokaryotic and eukaryotic cells after intensive deproteinization. This class of peptides, isolated from wheat bud chromatin, induces growth inhibition, DNA damage, G2 checkpoint activation and apoptosis in HeLa cells. In this work we studied their mechanism of action by investigating their ability to interfere with DNA synthesis.

Methods

BrdUrd comet assays were used to detect DNA replication defects during S phase. DNA synthesis, cell proliferation, cell cycle progression and DNA damage response pathway activation were assessed using 3H-thymidine incorporation, DNA flow cytometry and Western blotting, respectively.

Results

BrdUrd labelling close to DNA strand discontinuities (comet tails) detects the number of active replicons. This number was significantly higher in treated cells (compared to controls) from entry until mid S phase, but markedly lower in late S phase, indicating the occurrence of defective DNA synthesis. In mid S phase the treated cells showed less 3H-thymidine incorporation with respect to the controls, which supports an early arrest of DNA synthesis. DNA damage response activation was also shown in both p53-defective HeLa cells and p53-proficient U2OS cells by the detection of the phosphorylated form of H2AX after peptide treatment. These events were accompanied in both cell lines by an increase in p21 levels and, in U2OS cells, of phospho-p53 (Ser15) levels. At 24 h of recovery after peptide treatment the cell cycle phase distribution was similar to that seen in controls and CDK1 kinase accumulation was not detected.

Conclusion

The data reported here show that the antiproliferative effect exhibited by these chromatin peptides results from their ability to induce genomic stress during DNA synthesis. This effect seems to be S-phase specific since surviving cells are able to progress through their normal cell cycle when the peptide fraction is removed from the culture medium. It is likely that the subsequent apoptosis is a consequence of the failed attempt of the tumour cells to repair the DNA damage induced by the peptides.

     

Non-randomness in the species–area relationship: testing the underlying mechanisms

The species–area relationship (SAR) is one of the best documented patterns in ecology. However, interrelations between the SAR and species distributions are largely unexplored. This research was aimed (1) to assess if the SAR for a group of sedentary insects is associated to a random or non-random distribution of species across islands in a land-bridge archipelago, and (2) to investigate possible factors responsible for the non-randomness. Communities of tenebrionid beetles on the Aegean Islands (Greece) were studied as a case of a relict fauna. Three aspects of non-randomness were analysed: (1) non-random variation of species richness in the SAR, (2) degree of nestedness and (3) presence of special patterns of co-occurrence. Species co-occurrence and nestedness analyses indicated that historical aspects, as opposed to interspecific competition or distance-mediated colonization events, have moulded these species distributions.     

To scan or not to scan? Occurrence of the group‐size effect in a seasonally nongregarious forager

Group‐living requires a compromise between safety and direct/indirect costs for individuals. The larger is the group, the greater is the collective vigilance, leading to a greater net food intake per forager because of the time saved individually from scanning behaviour. In turn, individual alertness usually decreases with increasing group size (“group‐size effect”). Information on the occurrence of group‐size effect is still unclear. Previous studies have shown that it may fail to occur or even reverse, for example when costs of interference between conspecifics are high. In turn, assessing whether the group‐size effect would occur in weakly or seasonally gregarious species may help to understand its drivers. We evaluated the occurrence and the extent of group‐size effect in a seasonally nongregarious herbivore, the roe deer Capreolus capreolus. We examined the roles of sex/age class and season as drivers of vigilance behaviour. In roe deer, the group‐size effect did not depend on sex/age class: time spent foraging increased with increasing group size; in turn, vigilance increased with decreasing group size, in all sex/age classes. Females with fawns were the most vigilant sex/age class, thus revealing the cost of offspring protection. Accordingly, the higher spring vigilance levels of does could be related to reproductive costs (e.g., defence of newborn fawns). Conversely, the greater summer vigilance of bucks could result from patrolling/defence of territories. Both adult males and females also showed the higher vigilance in winter, likely because of an increase in the perception of predation risk and/or, possibly, hormones linked to an increase in intolerance of conspecifics, in males. However, the group‐size effect occurred in all the seasons, for adult males and females. Our findings suggest that foraging benefits provided by the group‐size effect may have overcome costs of group‐living, even in a weakly gregarious forager.