Cognition in insects

A traditional view of cognition is that it involves an internal process that represents, tracks or predicts an external process. This is not a general characteristic of all complex neural processing or feedback control, but rather implies specific forms of processing giving rise to specific behavioural capabilities. In this paper, I will review the evidence for such capabilities in insect navigation and learning. Do insects know where they are, or do they only know what to do? Do they learn what stimuli mean, or do they only learn how to behave?     

The importance of exposure rate on odds ratios by cigarette smoking and alcohol consumption for esophageal adenocarcinoma and squamous cell carcinoma in the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium

Background: Cigarette smoking is associated with esophageal adenocarcinoma (EAC), esophagogastric junctional adenocarcinoma (EGJA) and esophageal squamous cell carcinoma (ESCC), and alcohol consumption with ESCC. However, no analyses have examined how delivery rate modifies the strength of odds ratio (OR) trends with total exposure, i.e., the impact on the OR for a fixed total exposure of high exposure rate for short duration compared with low exposure rate for long duration. Methods: The authors pooled data from 12 case–control studies from the Barrett's Esophagus and Esophageal Adenocarcinoma Consortium (BEACON), including 1242 (EAC), 1263 (EGJA) and 954 (ESCC) cases and 7053 controls, modeled joint ORs for cumulative exposure and exposure rate for cigarette smoking and alcohol consumption, and evaluated effect modification by sex, body mass index (BMI), age and self-reported acid reflux. Results: For smoking, all sites exhibited inverse delivery rate effects, whereby ORs with pack-years increased, but trends weakened with increasing cigarettes/day. None of the examined factors modified associations, except for ESCC where younger ages at diagnosis enhanced smoking effects (P < 0.01). For EAC and EGJA, ORs with drink-years exhibited inverse associations in <5 drinks/day consumers and no association in heavier consumers. For ESCC, ORs with drink-years increased, with trends strengthening with greater drinks/day. There was no significant effect modification, except for EAC and EGJA where acid reflux mitigated the inverse associations (P = 0.02). For ESCC, younger ages at diagnosis enhanced drinking-related ORs (P < 0.01). Conclusions: Patterns of ORs by pack-years and drink-years, delivery rate effects and effect modifiers revealed common as well as distinct etiologic elements for these diseases.     

A novel strategy for development of recombinant antitoxin therapeutics tested in a mouse botulism model

Antitoxins are needed that can be produced economically with improved safety and shelf life compared to conventional antisera-based therapeutics. Here we report a practical strategy for development of simple antitoxin therapeutics with substantial advantages over currently available treatments. The therapeutic strategy employs a single recombinant 'targeting agent' that binds a toxin at two unique sites and a 'clearing Ab' that binds two epitopes present on each targeting agent. Co-administration of the targeting agent and the clearing Ab results in decoration of the toxin with up to four Abs to promote accelerated clearance. The therapeutic strategy was applied to two Botulinum neurotoxin (BoNT) serotypes and protected mice from lethality in two different intoxication models with an efficacy equivalent to conventional antitoxin serum. Targeting agents were a single recombinant protein consisting of a heterodimer of two camelid anti-BoNT heavy-chain-only Ab V(H) (VHH) binding domains and two E-tag epitopes. The clearing mAb was an anti-E-tag mAb. By comparing the in vivo efficacy of treatments that employed neutralizing vs. non-neutralizing agents or the presence vs. absence of clearing Ab permitted unprecedented insight into the roles of toxin neutralization and clearance in antitoxin efficacy. Surprisingly, when a post-intoxication treatment model was used, a toxin-neutralizing heterodimer agent fully protected mice from intoxication even in the absence of clearing Ab. Thus a single, easy-to-produce recombinant protein was as efficacious as polyclonal antiserum in a clinically-relevant mouse model of botulism. This strategy should have widespread application in antitoxin development and other therapies in which neutralization and/or accelerated clearance of a serum biomolecule can offer therapeutic benefit.     

The utilization of a unified pharmacophore query in the discovery of new antagonists of the adenosine receptor family

Pharmacophore queries from previously known potent selective A3 antagonists were generated by Chem-X. These queries were used to search a pharmacophore database of diverse compounds (CNS-Set). In vitro assays of 186 'hits' yielded over 30 active compounds, for four adenosine receptor subtypes. This search strategy may also be applicable to the discovery of new ligands via receptor homology data.     

Cytogenetically marked clones in human fibroblasts cultured from normal subjects.

Clones of cytogenetically abnormal cells have been recognized in fibroblasts cultured from normal human adult skin. No such clones have been observed in human embryo skin fibroblasts cultured in the same way. Although the culture conditions may have played some part in the emergence of these clones, it is possible that the abnormal cells from which the clones were derived were present in vivo.     

The anti-apoptosis protein, survivin, mediates gastric epithelial cell cytoprotection against ethanol-induced injury via activation of the p34(cdc2) cyclin-dependent kinase

The anti-apoptosis protein, survivin, promotes cell survival and mitosis. Recent studies have demonstrated that survivin is expressed in normal gastric mucosa. Using an in vitro model, we examined whether survivin plays a role in the cytoprotection produced in gastric mucosa by mild irritant ethanol (ETOH) against subsequent exposure to concentrated ETOH. Pre-treatment of rat gastric epithelial cells with 1% ETOH reduced cell death, in response to subsequent incubation with 5% ETOH, by 94% (P < 0.005). This pre-treatment also resulted in increased total and phosphorylated survivin protein levels by 180% (P < 0.0001) and 540% (P < 0.0002), respectively, which required the p34(cdc2) cell cycle-dependent kinase. The cytoprotective effect was abrogated upon siRNA knockdown of survivin protein levels. Further, overexpression of exogenous survivin resulted in significant cytoprotection by 62% (P < 0.02) in the absence of any pre-treatment. We further examined the in vivo relevance of these findings. In fasted rats, administration of 20% ETOH, which we found to be 93% (P < 0.0001) cytoprotective against 50% ETOH challenge, resulted in increased total and phosphorylated survivin protein levels by 234% (P < 0.001) and 214% (P < 0.02), respectively. Administration of 20% ETOH resulted in increased gastric p34(cdc2) activity by 146% (P < 0.01). Inhibition of p34(cdc2) by the potent inhibitor, roscovitine, abolished the increased survivin levels in response to pre-administration of 20% ETOH and reduced the cytoprotection against 50% ETOH challenge by 59% (P < 0.01). These results indicate that survivin is a key mediator of cytoprotection against ETOH-induced gastric injury, acting at the epithelial cell level, by a mechanism that is dependent, in part, on p34(cdc2).     

The cell cycle of the planctomycete Gemmata obscuriglobus with respect to cell compartmentalization

Background  

Gemmata obscuriglobus is a distinctive member of the divergent phylum Planctomycetes, all known members of which are peptidoglycan-less bacteria with a shared compartmentalized cell structure and divide by a budding process. G. obscuriglobus in addition shares the unique feature that its nucleoid DNA is surrounded by an envelope consisting of two membranes forming an analogous structure to the membrane-bounded nucleoid of eukaryotes and therefore G. obscuriglobus forms a special model for cell biology. Draft genome data for G. obscuriglobus as well as complete genome sequences available so far for other planctomycetes indicate that the key bacterial cell division protein FtsZ is not present in these planctomycetes, so the cell division process in planctomycetes is of special comparative interest. The membrane-bounded nature of the nucleoid in G. obscuriglobus also suggests that special mechanisms for the distribution of this nuclear body to the bud and for distribution of chromosomal DNA might exist during division. It was therefore of interest to examine the cell division cycle in G. obscuriglobus and the process of nucleoid distribution and nuclear body formation during division in this planctomycete bacterium via light and electron microscopy.     

Quantitative analysis of SR-BI-dependent HDL retroendocytosis in hepatocytes and fibroblasts

Previous studies have suggested that HDL retroendocytosis may play a role in scavenger receptor class B type I (SR-BI)-dependent selective lipid uptake in a cell-specific manner. To investigate this possibility, we developed methods to quantitatively measure HDL uptake and resecretion in fibroblast (COS-7) and hepatocyte (HepG2) cells expressing exogenous SR-BI. Approximately 17% and 24% of HDL associated in an SR-BI-dependent manner with COS-7 and HepG2 cells, respectively, accumulates intracellularly after a 10 min incubation. To determine whether this intracellular HDL undergoes retroendocytosis, we developed a pulse-chase assay whereby internalized biotinylated (125)I-HDL(3) secreted from cells is quantitatively precipitated from cell supernatants using immobilized streptavidin. Our results show a rapid secretion of a portion of intracellular HDL from both cell types (representing 4-7% of the total cell-associated HDL) that is almost complete within 30 min (half-life approximately 10 min). In COS-7 cells, the calculated rate of HDL secretion ( approximately 0.5 ng HDL/mg/min) was >30-fold slower than the rate of SR-BI-dependent selective cholesteryl ester (CE) uptake ( approximately 17 ng HDL/mg/min), whereas the rate of release of HDL from the cell surface ( approximately 19 ng HDL/mg/min) was similar to the rate of selective CE uptake. Notably, the rate of SR-BI-dependent HDL resecretion in COS-7 and HepG2 cells was similar. BLT1, a compound that inhibits selective CE uptake, does not alter the amount of SR-BI-mediated HDL retroendocytosis in COS-7 cells. From these data, we conclude that HDL retroendocytosis in COS-7 and HepG2 cells is similar and that the vast majority of SR-BI-dependent selective uptake occurs at the cell surface in both cell types.