Grooming and touching behaviour in captive ring-tailed lemurs (Lemur catta L.)

The distribution of grooming and touching behaviours was recorded in a group of captive ring-tailed lemurs. Grooming was found to be performed chiefly by older, higher ranking animals; touching (i.e., “reach out and touch” behaviour) was directed primarily by younger, low ranking animals to older, high ranking individuals. It is suggested that such touching is a submissive gesture in this species.     

A predictive model for freshwater bioassessment (Mondego River,Portugal)

We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model. At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207 taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality, substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model, the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and increasing the number of ellipses that define quality bands. Handling editor: K. Martens     

The Peculiar Facets of Nitric Oxide as a Cellular Messenger: From Disease-Associated Signaling to the Regulation of Brain Bioenergetics and Neurovascular Coupling

In this review, we address the regulatory and toxic role of ^·NO along several pathways, from the gut to the brain. Initially, we address the role on ^·NO in the regulation of mitochondrial respiration with emphasis on the possible contribution to Parkinson’s disease via mechanisms that involve its interaction with a major dopamine metabolite, DOPAC. In parallel with initial discoveries of the inhibition of mitochondrial respiration by ^·NO, it became clear the potential for toxic ^·NO-mediated mechanisms involving the production of more reactive species and the post-translational modification of mitochondrial proteins. Accordingly, we have proposed a novel mechanism potentially leading to dopaminergic cell death, providing evidence that NO synergistically interact with DOPAC in promoting cell death via mechanisms that involve GSH depletion. The modulatory role of NO will be then briefly discussed as a master regulator on brain energy metabolism. The energy metabolism in the brain is central to the understanding of brain function and disease. The core role of ^·NO in the regulation of brain metabolism and vascular responses is further substantiated by discussing its role as a mediator of neurovascular coupling, the increase in local microvessels blood flow in response to spatially restricted increase of neuronal activity. The many facets of NO as intracellular and intercellular messenger, conveying information associated with its spatial and temporal concentration dynamics, involve not only the discussion of its reactions and potential targets on a defined biological environment but also the regulation of its synthesis by the family of nitric oxide synthases. More recently, a novel pathway, out of control of NOS, has been the subject of a great deal of controversy, the nitrate:nitrite:NO pathway, adding new perspectives to ^·NO biology. Thus, finally, this novel pathway will be addressed in connection with nitrate consumption in the diet and the beneficial effects of protein nitration by reactive nitrogen species.

     

Frequency of Escherichia coli O157:H7 isolation from stool specimens

During a 6-month period, 7252 faeces specimens were examined for Escherichia coli serotype O157:H7. Forty-nine specimens (0.7%) from 19 patients yielded this organism. Escherichia coli O157:H7 was the third most frequently isolated bacterial pathogen, following Campylobacter jejuni and (or) Salmonella sp. Although regional variation between laboratories determined whether Campylobacter jejuni or Salmonella was the primary bacterial pathogen isolated, E. coli O157:H7 was consistently isolated more frequently than either Shigella or Yersinia enterocolitica.     

Molecular Probing of the HPV-16 E6 Protein Alpha Helix Binding Groove with Small Molecule Inhibitors

The human papillomavirus (HPV) HPV E6 protein has emerged as a central oncoprotein in HPV-associated cancers in which sustained expression is required for tumor progression. A majority of the E6 protein interactions within the human proteome use an alpha-helix groove interface for binding. The UBE3A/E6AP HECT domain ubiquitin ligase binds E6 at this helix-groove interface. This enables formation of a trimeric complex with p53, resulting in destruction of this tumor suppressor. While recent x-ray crystal structures are useful, examples of small molecule probes that can modulate protein interactions at this interface are limited. To develop insights useful for potential structure-based design of ligands for HPV E6, a series of 2,6-disubstituted benzopyranones were prepared and tested as competitive antagonists of E6-E6AP helix-groove interactions. These small molecule probes were used in both binding and functional assays to evaluate recognition features of the E6 protein. Evidence for an ionic functional group interaction within the helix groove was implicated by the structure-activity among the highest affinity ligands. The molecular topographies of these protein-ligand interactions were evaluated by comparing the binding and activities of single amino acid E6 mutants with the results of molecular dynamic simulations. A group of arginine residues that form a rim-cap over the E6 helix groove offer compensatory roles in binding and recognition of the small molecule probes. The flexibility and impact on the overall helix-groove shape dictated by these residues offer new insights for structure-based targeting of HPV E6.     

Geographic isolation and evolution of Mediterranean endemic Cyclamen: insights from chloroplast trnL (UAA) intron sequence variation

 In this study we construct a phylogenetic hypothesis for the relatedness among disjunct subspecies of Cyclamen repandum and its two allopatric congeners, C. creticum and C. balearicum in order to examine the evolutionary divergence of currently isolated populations across the western Mediterranean. The most parsimonious phylogenetic tree obtained from sequencing the cpDNA trnL (UAA) intron suggests a major phylogeographic divide in southern Greece between two clades. The first clade comprises samples of C. repandum subsp. peloponnesiacum (from the Peloponnese) and C. creticum (from Crete). The second comprises samples of C. repandum subsp. repandum (from Croatia, Italy, southern France, Corsica, Sardinia and Sicily), C. repandum subsp. rhodense (from Rhodes and Kos) and C. balearicum (from the Balearic Islands and southern France). These data suggest that C. creticum has evolved in allopatry from C. repandum subsp. peloponnesiacum and that C. balearicum and C. repandum ssp. rhodense have diverged from C. repandum subsp. repandum at its western and eastern distribution limits. At one small site on Corsica, a population of C. repandum may have introgressed with relictual populations of C. balearicum. These divergence patterns illustrate how a phylogenetic perspective can be used to better understand the evolution of endemism in the Mediterranean flora. Received February 19, 2001 Accepted August 22, 2001     

Cyclic nucleotide alterations in mixed leukocyte reaction: a preliminary report

Endogenous cyclic adenosine and guanosine monophosphate (cAMP, cGMP) levels were studied in human peripheral blood lymphocytes during mixed leukocyte reactions (MLR). cAMP level was consistently elevated in one-way MLR, with good correlation to 3H-thymidine uptake in these reactions. In contrast, cGMP level was practically unchanged. Irradiation of reacting cell populations resulted in inhibition of cyclic nucleotide phosphodiesterase (PDE) activity. These results suggest that metabolic alterations in cAMP may be associated with immune reactions of cellular recognition.     

Presence of prostaglandins E2 and A2 in canine gastric secretions

The presence of prostaglandins (PGs) was determined in gastric juice obtained from 3 conscious dogs, provided with a chronic gastric fistula. Outputs of acid (mequiv min^?1) and PGs (pg min^?1) were measured in gastric secretions stimulated by pentagastrin (100 or 200 ng kg^?1min^?1). Prostaglandin activity was estimated, after extraction and thin layer chromatography, by radioimmuno-assay of the PGB formed by treatment with alkali. Tritiated PGs were added to gastric juice for the purpose of correcting for PGs recovery. Using this method, the minimum mass of PGB which could be satisfactorily distinguished from zero was 25 pg. Prostaglandins A₂ and E₂ were present in pentagastrin-activated gastric secretions and averaged (mean ± SE, n = 8) 200.7 ± 18.1 and 260.1 ± 18.0 pg min^?1 respectively. The identity of PGA₂ and PGE₂ was confirmed by gas liquid chromatography combined with mass spectrometry. The amount of PGE₂ converted to PGA₂ during extraction, separation and conversion procedures was estimated from the amount of [³H] PGA₂ found when only [³H] PGE₂ had been added to a sample of gastric juice and averaged 14.5% ± 2.0. Our preliminary results support the possibility that PGE₂ and PGA₂ may be of physiological importance in the regulation of canine gastric secretions.     

Single-molecule fluorescence measurements reveal the reaction mechanisms of the core-RISC,composed of human Argonaute 2 and a guide RNA

In eukaryotes, small RNAs play important roles in both gene regulation and resistance to viral infection. Argonaute proteins have been identified as a key component of the effector complexes of various RNA-silencing pathways, but the mechanistic roles of Argonaute proteins in these pathways are not clearly understood. To address this question, we performed single-molecule fluorescence experiments using an RNA-induced silencing complex (core-RISC) composed of a small RNA and human Argonaute 2. We found that target binding of core-RISC starts at the seed region of the guide RNA. After target binding, four distinct reactions followed: target cleavage, transient binding, stable binding, and Argonaute unloading. Target cleavage required extensive sequence complementarity and accelerated core-RISC dissociation for recycling. In contrast, the stable binding of core-RISC to target RNAs required seed-match only, suggesting a potential explanation for the seed-match rule of microRNA (miRNA) target selection. [BMB Reports 2015; 48(12): 643-644]