Lampyridae (Coleoptera): A plethora of mollicute associations

Beetles (Coleoptera) harbor many species ofAcholeplasma andSpiroplasma (division Tenericutes, class Mollicutes). Mollicutes were isolated from guts and/or hemocoels of firefly beetles (Lampyridae) from the United States (Maryland and West Virginia), Ecuador, and Tobago. Firefly beetles were frequent hosts for the group XIV spiroplasma, isolated from Ellychnia corrusca, and the group XIX spiroplasma, isolated fromPhoturis spp. The most unusual feature of the firefly-mollicute association is the carriage of four Mycoplasma species. Recent phylogenetic studies indicate that these species are members of a clade that includes a vertebrate pathogen,Mycoplasma mycoides. The high rate of occurrence ofMycoplasma species (which are, otherwise, infrequent in insects) in lampyrid beetles suggests that the association is significant. The unusual light-producing physiology of lampyrids (which is dependent on large pools of energy) and the production of large amounts of cardenolides from cholesterol (a critical growth factor for many mollicutes) may favor colonization by mollicutes. Offprint requests to: K. J. Hackett.     

Brucella Cyclic β-1,2-Glucan Plays a Critical Role in the Induction of Splenomegaly in Mice

Brucella, the etiological agent of animal and human brucellosis, is a bacterium with the capacity to modulate the inflammatory response. Cyclic β-1,2-glucan (CβG) is a virulence factor key for the pathogenesis of Brucella as it is involved in the intracellular life cycle of the bacteria. Using comparative studies with different CβG mutants of Brucella, cgs (CβG synthase), cgt (CβG transporter) and cgm (CβG modifier), we have identified different roles for this polysaccharide in Brucella. While anionic CβG is required for bacterial growth in low osmolarity conditions, the sole requirement for a successful Brucella interaction with mammalian host is its transport to periplasmic space. Our results uncover a new role for CβG in promoting splenomegaly in mice. We showed that CβG-dependent spleen inflammation is the consequence of massive cell recruitment (monocytes, dendritics cells and neutrophils) due to the induction of pro-inflammatory cytokines such as IL-12 and TNF-α and also that the reduced splenomegaly response observed with the cgs mutant is not the consequence of changes in expression levels of the characterized Brucella PAMPs LPS, flagellin or OMP16/19. Complementation of cgs mutant with purified CβG increased significantly spleen inflammation response suggesting a direct role for this polysaccharide.     

Identification of active site residues of the inverting glycosyltransferase Cgs required for the synthesis of cyclic beta-1,2-glucan, a Brucella abortus virulence factor

Brucella abortus cyclic glucan synthase (Cgs) is a 320-kDa (2868-amino acid) polytopic integral inner membrane protein responsible for the synthesis of the virulence factor cyclic beta-1,2-glucan by a novel mechanism in which the enzyme itself acts as a protein intermediate. Cgs functions as an inverting processive beta-1,2-autoglucosyltransferase and has the three enzymatic activities required for the synthesis of the cyclic glucan: initiation, elongation, and cyclization. To gain further insight into the protein domains that are essential for the enzymatic activity, we have compared the Cgs sequence with other glycosyltransferases (GTs). This procedure allowed us to identify in the Cgs region (475-818) the widely spaced D, DxD, E/D, (Q/R)xxRW motif that is highly conserved in the active site of numerous GTs. By site-directed mutagenesis and in vitro and in vivo activity assays, we have demonstrated that most of the amino acid residues of this motif are essential for Cgs activity. These sequence and site-directed mutagenesis analyses also indicate that Cgs should be considered a bi-functional modular GT, with an N-terminal GT domain belonging to a new GT family related to GT-2 (GT-84) followed by a GH-94 glycoside hydrolase C-terminal domain. Furthermore, over-expression of inactive mutants results in wild-type (WT) production of cyclic glucan when bacteria co-express the mutant and the WT form, indicating that Cgs may function in the membrane as a monomeric enzyme. Together, these results are compatible with a single addition model by which Cgs acts in the membrane as a monomer and uses the identified motif to form a single center for substrate binding and glycosyl-transfer reaction.     

Immunomodulating properties of MDMA alone and in combination with alcohol: a pilot study

Cell-mediated immune response after the administration of MDMA alone and in combination with alcohol was evaluated in a randomized, double-blind, double-dummy, cross-over pilot clinical trial conducted in four healthy MDMA consumers who received single oral doses of 75 mg MDMA (n = 2) or 100 mg MDMA (n = 2), alcohol (0.8 mg/kg), MDMA and alcohol, or placebo. Acute MDMA treatment produced a time-dependent immune dysfunction associated with MDMA plasma concentrations. Although total leukocyte count remained unchanged, there was a decrease in the CD4 T/CD8 T-cell ratio as well as in the percentage of mature T lymphocytes, probably because of a decrease in both the percentage and absolute number of T helper cells. The decrease in CD4 T-cell counts and in the functional responsiveness of lymphocytes to mitogenic stimulation was dose-dependent. The correlation between MDMA pharmacokinetics and the profile of MDMA-induced immune dysfunction suggests that alteration of the immune system may be mediated by the central nervous system. Alcohol consumption produced a decrease in T helper cells, B lymphocytes, and PHA-induced lymphocyte proliferation. Combined MDMA and alcohol produced the greatest suppressive effect on CD4 T-cell count and PHA-stimulated lymphoproliferation. Immune function was partially restored at 24 hours. These results provide the first evidence that recreational use of MDMA alone or in combination with alcohol alters the immunological status.     

Naturally occurring secondary nutritional hyperparathyroidism in cattle egrets (Bubulcus ibis) from central Texas

Naturally occurring secondary nutritional hyperparathyroidism is described in the nestlings of two colonies of cattle egrets (Bubulcus ibis) from Central Texas (Bryan and San Antonio, Texas, USA). Nestlings from a third colony (Waco, Texas, USA) were collected in a subsequent year for comparison. Birds from the first two colonies consistently had severe osteopenia and associated curving deformities and folding fractures of their long bones. These birds also had reduced bone ash, increased osteoclasia, a marked decrease in osteoblast activity, variable lengthening and shortening of the hypertrophic zone of the epiphyseal cartilage, decreased and disorganized formation of new bone, and a marked hypertrophy and hyperplasia of the parathyroid glands as compared to birds collected from the third colony. Fibrous osteodystrophy was found in all of the birds from San Antonio and Bryan. Evidence of moderate to severe calcium deficiency was also identified in 33% of the cattle egrets collected from Waco. Gut contents of affected chicks contained predominately grasshoppers and crickets; vertebrate prey items were absent from the Bryan birds. Grasshoppers and crickets collected from fields frequented by the adult egrets in 1994 had 0.12-0.28% calcium and 0.76-0.81% phosphorus. Pooled grasshoppers and crickets collected during a subsequent wet early spring averaged 0.24% calcium and 0.65% phosphorus. Although the phosphorus content of the insect prey was adequate for growth, calcium was approximately one-third the minimum calcium requirement needed for growth for other species of birds. It was postulated that cattle egrets breeding in Central Texas have expanded their range into habitat that contains less vertebrate prey, and as a result, many nestling egrets are being fed diets that contain suboptimal calcium. Therefore, in years where vertebrate prey is scarce and forage for insect prey is reduced in calcium, nestling egrets are at risk for developing secondary nutritional hyperparathyroidism.     

Next‐generation monitoring of aquatic biodiversity using environmental DNA metabarcoding

Global biodiversity in freshwater and the oceans is declining at high rates. Reliable tools for assessing and monitoring aquatic biodiversity, especially for rare and secretive species, are important for efficient and timely management. Recent advances in DNA sequencing have provided a new tool for species detection from DNA present in the environment. In this study, we tested whether an environmental DNA (eDNA) metabarcoding approach, using water samples, can be used for addressing significant questions in ecology and conservation. Two key aquatic vertebrate groups were targeted: amphibians and bony fish. The reliability of this method was cautiously validated in silico, in vitro and in situ. When compared with traditional surveys or historical data, eDNA metabarcoding showed a much better detection probability overall. For amphibians, the detection probability with eDNA metabarcoding was 0.97 (CI = 0.90–0.99) vs. 0.58 (CI = 0.50–0.63) for traditional surveys. For fish, in 89% of the studied sites, the number of taxa detected using the eDNA metabarcoding approach was higher or identical to the number detected using traditional methods. We argue that the proposed DNA‐based approach has the potential to become the next‐generation tool for ecological studies and standardized biodiversity monitoring in a wide range of aquatic ecosystems.     

Prevención de las úlceras de talón en un hospital de media estancia. Estudio comparativo de vendaje clásico almohadillado respecto a las taloneras hidrocelulares de poliuretano

Introduction

The aim of the study is to determine the incidence of heel pressure ulcers (UPPT) and to compare the two systems for UPPT prevention: classic padded bandage and polyurethane heel.

Material and methods

Prospective intervention study in a medium-long hospital stay of all people admitted that had no UPPT but had a risk of UPPT according to the Braden Scale or clinical judgment. The patients were randomized to prevention with classic padded bandage or polyurethane heel. The outcome variable was the incidence of UPPT for each study group, which was recorded every 15 days or when there were clinical changes.

Results

Of the 940 patients evaluated, 409 with a mean age of 80.5 years and 59.1% women,were included in the study. Of these, 78% had Barthel score ≤30; 28.6% dementia; delirium 37.6%; 27.6% diabetes; and 19.6% other UPP. The overall incidence was 2.9% UPPT; 2.49% in the classic padded bandage and 3.37% in the polyurethane heel group (p=0.82).

Conclusions

No statistically significant differences were observed between the group with the classical dressing and the group with the polyurethane heel dressing. The use of multiple measures to prevent UPPT achieved a low incidence of these.