Surface and deep ocean interactions during the cold climate event 8200 years ago

Evidence from a North Atlantic deep-sea sediment core reveals that the largest climatic perturbation in our present interglacial, the 8200-year event, is marked by two distinct cooling events in the subpolar North Atlantic at 8490 and 8290 years ago. An associated reduction in deep flow speed provides evidence of a significant change to a major downwelling limb of the Atlantic meridional overturning circulation. The existence of a distinct surface freshening signal during these events strongly suggests that the sequenced surface and deep ocean changes were forced by pulsed meltwater outbursts from a multistep final drainage of the proglacial lakes associated with the decaying Laurentide Ice Sheet margin.     

SV2 is the protein receptor for botulinum neurotoxin A

How the widely used botulinum neurotoxin A (BoNT/A) recognizes and enters neurons is poorly understood. We found that BoNT/A enters neurons by binding to the synaptic vesicle protein SV2 (isoforms A, B, and C). Fragments of SV2 that harbor the toxin interaction domain inhibited BoNT/A from binding to neurons. BoNT/A binding to SV2A and SV2B knockout hippocampal neurons was abolished and was restored by expressing SV2A, SV2B, or SV2C. Reduction of SV2 expression in PC12 and Neuro-2a cells also inhibited entry of BoNT/A, which could be restored by expressing SV2 isoforms. Finally, mice that lacked an SV2 isoform (SV2B) displayed reduced sensitivity to BoNT/A. Thus, SV2 acts as the protein receptor for BoNT/A.     

Clinical Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum infections in dogs

Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum are related apicomplexans that can cause systemic illness in many species of animals, including dogs. We investigated one breeder's 25 Basset Hounds for these infections. In addition, tissues from dogs and other non-canine hosts previously reported as S. canis infections were studied retrospectively. Schizonts resembling those of S. neurona, and recognized by polyclonal rabbit anti-S. neurona antibodies, were found in six of eight retrospective cases, as well as in two additional dogs (one Basset Hound, one Springer Spaniel) not previously reported. S. neurona schizonts were found in several tissues including the central nervous system, lungs, and kidneys. Fatal toxoplasmosis was diagnosed in an adult dog, and neosporosis was diagnosed in an adult and a pup related to the one diagnosed with S. neurona. No serological reactivity to S. neurona antibodies occurred when S. canis-like liver schizonts were retrospectively assayed from two dogs, a dolphin, a sea lion, a horse, a chinchilla, a black or either of two polar bears. Sequencing conserved (18S) and variable (ITS-1) portions of nuclear ribosomal DNA isolated from the schizont-laden liver of a polar bear distinguished it from all previously characterized species of Sarcocystis. We take this genetic signature as provisionally representative of S. canis, an assumption that should be tested with future sequencing of similar liver infections in other mammalian hosts. These findings further extend the uncharacteristically broad intermediate host range for S. neurona, which also causes a neurologic disease in cats, mink, raccoons, skunks, Pacific harbor seals, ponies, zebras, lynxes, and sea otters. Further work is necessary to delineate the causative agent(s) of other cases of canine sarcocystosis, and in particular to specify the attributes of S. canis, which corresponds morphologically to infections reported from wide range of terrestrial and marine mammals.     

Neonicotinoid pesticide reduces bumble bee colony growth and queen production

Growing evidence for declines in bee populations has caused great concern because of the valuable ecosystem services they provide. Neonicotinoid insecticides have been implicated in these declines because they occur at trace levels in the nectar and pollen of crop plants. We exposed colonies of the bumble bee Bombus terrestris in the laboratory to field-realistic levels of the neonicotinoid imidacloprid, then allowed them to develop naturally under field conditions. Treated colonies had a significantly reduced growth rate and suffered an 85% reduction in production of new queens compared with control colonies. Given the scale of use of neonicotinoids, we suggest that they may be having a considerable negative impact on wild bumble bee populations across the developed world.     

Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest. To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio calculations, we observed the formation of reduced and structurally distorted metal sites consistent with small polarons. Comparisons between different phases (hematite, maghemite, and ferrihydrite) revealed that short-range structural topology, not long-range order, dominates the electron-hopping rate.     

An AC-5 cathepsin B-like protease purified from Haemonchus contortus excretory secretory products shows protective antigen potential for lambs

The immunogenic properties of cysteine proteases obtained from excretory/secretory products (ES) of Haemonchus contortus were investigated with a fraction purified with a recombinant H. contortus cystatin affinity column. The enrichment of H. contortus ES for cysteine protease was confirmed with substrate SDS-PAGE gels since the cystatin-binding fraction activity was three times higher than total ES, despite representing only 3% of total ES. This activity was inhibited by a specific cysteine protease inhibitor (E64) and by recombinant cystatin. The one-dimensional profile of the cystatin-binding fraction displayed a single band with a molecular mass of 43 kDa. Mass spectrometry showed this to be AC-5, a cathepsin B-like cysteine protease which had not been identified in ES products of H. contortus before. The cystatin binding fraction was tested as an immunogen in lambs which were vaccinated three times (week 0, 2.5 and 5), challenged with 10 000 L3 H. contortus (week 6) before necropsy and compared to unvaccinated challenge controls and another group given total ES (n = 10 per group). The group vaccinated with cystatin-binding proteins showed 36% and 32% mean worm burden and eggs per gram of faeces (EPG) reductions, respectively, compared to the controls but total ES was almost without effect. After challenge the cystatin-binding proteins induced significantly higher local and systemic ES specific IgA and IgG responses.     

Review of antimicrobial therapy of selected bacterial diseases in broiler chickens in Canada

This paper reviews common therapeutic applications of antimicrobials in broiler chicken production in relation to Canadian guidelines, surveillance data, and emerging public health concerns about antimicrobial use (AMU). Escherichia coli, Clostridium perfringens, and Staphylococcus spp., were reviewed because of their animal health and economic significance. Enterococcus cecorum and Salmonella were included because of their importance in antimicrobial resistance (AMR) surveillance. This review identified that i) antimicrobials are available in Canada to treat infections by these agents, but may be through over the counter or extra-label use, ii) prevalence rates for these diseases are unknown, iii) antimicrobial use estimates in broilers are lacking, and iv) AMR has emerged in clinical isolates, though data are very sparse. This review highlights the need for surveillance of AMU and AMR in broiler chickens in Canada.