Docking and molecular dynamics studies of peripheral site ligand–oximes as reactivators of sarin-inhibited human acetylcholinesterase

In the present work, we performed docking and molecular dynamics simulations studies on two groups of long-tailored oximes designed as peripheral site binders of acetylcholinesterase (AChE) and potential penetrators on the blood brain barrier. Our studies permitted to determine how the tails anchor in the peripheral site of sarin-inhibited human AChE, and which aminoacids are important to their stabilization. Also the energy values obtained in the docking studies corroborated quite well with the experimental results obtained before for these oximes.     

A Nuclear Marker for Mammalian Cells and Its Use with Intracerebral Transplants

The Hoechst dye staining method has been successfully applied to the central nervous system in mammals and its use has been demonstrated in intracerebral transplantation. The technique is rapid, simple and based on intrinsic nuclear properties. It was found to be permanent and valid whatever the animal strains or ages, allowing the distinction of rat cells from those of mouse, studied either separately or in a cross-transplantation model. It permitted the detection of grafted cells in the area of transplantation and the observation of early dispersion around the implantation site. Moreover, it can be combined with immunohistochemistry as demonstrated by a myelin marker in a relevant model. Immunodetection can thus help to directly observe grafted cells, at distance from the locus of transplantation, confirming their presence in the graft-type myelin patches.

Because of its rapid performance, this technique can be used systematically after transplantation to check for the presence of grafted cells in the host.     

Alteration of free amino acid concentrations in insect galls induced by Andricus mukaigawae (Hymenoptera; Cynipidae)

1. Insect galls are abnormal plant growths that develop in response to a stimulus provided by a galling insect. The nutrition hypothesis suggests that the concentrations of nutritive compounds in galls are changed to provide optimum nutrition for the larvae and adults of galling insects. 2. To test the nutrition hypothesis, we determined the concentrations of 20 free amino acids in galls and in galled and ungalled twigs of Quercus fabri during the larval and adult stages of Andricus mukaigawae using high-performance liquid chromatography with ultraviolet–visible detection. 3. At the larval stage, the concentrations of 12 out of 20 amino acids in A. mukaigawae galls were significantly higher than those in galled and ungalled twigs. Asparagine and tryptophan were the most abundant nonessential and essential amino acids, respectively, in A. mukaigawae galls. 4. At the adult stage, the concentrations of most amino acids, except proline, were significantly lower in A. mukaigawae galls than in galled and ungalled twigs. The A. mukaigawae adults may not manipulate amino acid levels because the adults do not feed on galls. The decrease of amino acid levels in adult galls may be viewed as a depletion. 5. The composition of free amino acids in A. mukaigawae galls was significantly different from the composition in galled and ungalled twigs in both the larval and adult stages. 6. Our results may support the nutrition hypothesis. We suggest that a high concentration of proline in A. mukaigawae galls may protect larvae and adults from plant defense responses.     

Shifting abundances of communities associated with nitrogen cycling in soils promoted by sugarcane harvest systems

Sugarcane cultivation supports Brazil as one of the largest world sugar and ethanol producer. In order to understand the impact of changing sugarcane harvest from manual to mechanized harvest, we studied the effect of machinery traffic on soil and consequently soil compaction upon soil microbial communities involved in nitrogen cycling. The impact of sugarcane harvest was dependent on soil depth and texture. At deeper soil layers, mechanized harvesting increases the abundance of nitrogen fixers and denitrifying communities (specifically nosZ clade I and II) while manual harvesting increases the abundance of ammonia oxidizers (specifically AOA) and increases denitrifying communities (nosZ clade I and II) on top and at intermediate depth. The effect of change on the harvest system is more evident on sandy soil than on clay soil, where soil indicators of compaction (bulk density and penetration resistance) were negatively correlated with soil microorganisms associated with the nitrogen cycle. Our results point to connections between soil compaction and N transformations in sugarcane fields, besides naming biological variables to be used as proxies for alterations in soil structure.     

Lytic transglycosylases: concinnity in concision of the bacterial cell wall

The lytic transglycosylases (LTs) are bacterial enzymes that catalyze the non-hydrolytic cleavage of the peptidoglycan structures of the bacterial cell wall. They are not catalysts of glycan synthesis as might be surmised from their name. Notwithstanding the seemingly mundane reaction catalyzed by the LTs, their lytic reactions serve bacteria for a series of astonishingly diverse purposes. These purposes include cell-wall synthesis, remodeling, and degradation; for the detection of cell-wall-acting antibiotics; for the expression of the mechanism of cell-wall-acting antibiotics; for the insertion of secretion systems and flagellar assemblies into the cell wall; as a virulence mechanism during infection by certain Gram-negative bacteria; and in the sporulation and germination of Gram-positive spores. Significant advances in the mechanistic understanding of each of these processes have coincided with the successive discovery of new LTs structures. In this review, we provide a systematic perspective on what is known on the structure–function correlations for the LTs, while simultaneously identifying numerous opportunities for the future study of these enigmatic enzymes.     

Thermal tolerance and recovery behaviour of Thorectes lusitanicus (Coleoptera,Geotrupidae)

1. Population differences in physiological responses are examined in Thorectes lusitanicus, an endemic Iberian dung beetle species, by submitting individuals of different populations to the same experimental and acclimation conditions. 2. An infrared thermography protocol was used, consisting of three assays: start of activity, cold response, and heat response. Individuals of 12 populations were studied and the comparative explanatory capacities of several environmental factors in relation to the observed inter‐population differences were examined. 3. The heating rate from chill coma to the beginning of activity was the variable with the highest discrimination power among the studied populations, accounting for 94% of the observed variance. Regarding the heat response, only six of the 16 thermal variables reached significance (inter‐population differences accounted for 52–74% in these six thermal parameters). 4. From the three considered environmental factors (Mediterranean climate, land cover, and trophic characteristics) only land cover characteristics remain statistically significant, affecting the cold response of individuals. 5. Thorectes lusitanicus is a species characterised by a high diversity of thermotolerance and recovery traits across populations with a low degree of association with broad environmental factors. Finally, it is suggested that the apterous character of this species could be a determinant factor explaining the high diversity of ecophysiological traits related to thermal stress tolerance and the recovery time.     

The corpora lutea proangiogenic state of VEGF system components is turned to antiangiogenic at the later phase of the oestrous cycle in cows

Blood vessel expansion and reduction in the corpus luteum (CL) is regulated by the vascular endothelial growth factor (VEGF) system and linked to the maintenance of the CL. The VEGF system has both angiogenic and antiangiogenic ligands and receptors. Our objective was to evaluate the relationship between the mRNA expression of angiogenic and antiangiogenic members of the VEGF system in the CL, throughout the luteal phase of the oestrous cycle in cows. The CL of 18 cows were collected by transvaginal surgery on days 4, 6, 9, 12, 15 and 18 of the oestrous cycle and the mRNA expression of VEGF system components was evaluated by quantitative real-time PCR. The mRNA expression of VEGF ligands and receptors increased (P<0.05) from the early- and mid-luteal phase (days 4 to 12) reaching its maximum expression on day 15 of the cycle. We found no expression of VEGF164b throughout the cycle. Expression of sVEGFR1 did not change during the oestrous cycle and exceeded that of the VEGFR1 by 100 times. Nonetheless, as VEGFR1 increased, the relationship between the soluble and membrane receptor decreased (P<0.01). In contrast, the expression of VEGFR2 was higher than that of its soluble isoform for all days studied, however, the ratio between the membrane-bound and its soluble counterpart decreased continuously throughout the cycle (P<0.01). Our results show that the expression levels for VEGF ligands, receptors and their antagonistic counterparts are adjusted during CL development and regression, to upregulate angiogenesis early in the oestrous cycle and restrict it at the time of luteolysis.     

V‐antigen homologs in pathogenic gram‐negative bacteria

Gram‐negative bacteria cause many types of infections in animals from fish and shrimps to humans. Bacteria use Type III secretion systems (TTSSs) to translocate their toxins directly into eukaryotic cells. The V‐antigen is a multifunctional protein required for the TTSS in Yersinia and Pseudomonas aeruginosa. V‐antigen vaccines and anti‐V‐antigen antisera confer protection against Yersinia or P. aeruginosa infections in animal models. The V‐antigen forms a pentameric cap structure at the tip of the Type III secretory needle; this structure, which has evolved from the bacterial flagellar cap structure, is indispensable for toxin translocation. Various pathogenic gram‐negative bacteria such as Photorhabdus luminescens, Vibrio spp., and Aeromonas spp. encode homologs of the V‐antigen. Because the V‐antigens of pathogenic gram‐negative bacteria play a key role in toxin translocation, they are potential therapeutic targets for combatting bacterial virulence. In the USA and Europe, these vaccines and specific antibodies against V‐antigens are in clinical trials investigating the treatment of Yersinia or P. aeruginosa infections. Pathogenic gram‐negative bacteria are of great interest because of their ability to infect fish and shrimp farms, their potential for exploitation in biological terrorism attacks, and their ability to cause opportunistic infections in humans. Thus, elucidation of the roles of the V‐antigen in the TTSS and mechanisms by which these functions can be blocked is critical to facilitating the development of improved anti‐V‐antigen strategies.