Clinicopathological investigation of primary, uncomplicated maedi-visna virus infection.

Maedi-visna virus infection in a flock of sheep in Scotland was associated with respiratory disease, neurological disease, mastitis and lameness. The major clinical signs were dyspnoea (particularly on exercise), progressive fore- and hindlimb ataxia and balance defects, mammary induration and multilimb lameness, occasionally with enlarged carpal joints. Pathological examinations revealed lesions in the lungs, central nervous system, mammary glands and joints which were consistent with those induced by maedi-visna virus. The was no clinical or pathological evidence of concurrent sheep pulmonary adenomatosis, and pulmonary bacterial infections, when they occurred, were superimposed on the lesions due to maedi-visna virus.     

Attempt to control parturition in the sow using an oral progestogen

Analogues of prostaglandin F2 alpha are widely used in the United Kingdom to induce parturition in sows. A disadvantage is that sows are induced to farrow in advance of expected delivery dates. An alternative might be to maintain gestation by the application of a progestogen. Farrowing might then be initiated on the withdrawal of the progestogen. The use of an orally active progestogen (allyl-trenbolone) in an attempt to control the time of parturition in sows is described. In experiment 1, 20 large white cross landrace sows were allocated at random to one of two treatments. Treated sows were fed 16 mg/day of allyl-trenbolone from day 111 of gestation to day 118 of gestation. The farrowing performance of these sows was compared with that of control sows which farrowed naturally. Treated sows farrowed significantly (P less than 0.01) later than the control sows (118.2 and 116.1 days respectively). For treated sows the interval from progestogen withdrawal to farrowing was 29.6 +/- 4.8 hours. The number of stillbirths for treated and control sows respectively was 2.1 and 0.4 per litter. Treatment had no effect either on the birth weight of piglets or on their weaning weight at six weeks old. There was a tendency for more treated sows to show subsequent reproductive malfunction. In a second experiment, under commercial conditions, 81 sows and 12 gilts were allocated to one of four treatments. Treatment A animals were untreated controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nanocatalysis by the tip of a scanning tunneling microscope operating inside a reactor cell

The platinum-rhodium tip of a scanning tunneling microscope that operates inside of an atmospheric-pressure chemical reactor cell has been used to locally rehydrogenate carbonaceous fragments deposited on the (111) surface of platinum. The carbon fragments were produced by partial dehydrogenation of propylene. The reactant gas environment inside the cell consisted of pure H(2) or a 1:9 mixture of CH(3)CHCH(2) and H(2) at 300 kelvin. The platinum-rhodium tip acted as a catalyst after activation by short voltage pulses. In this active state, the clusters in the area scanned by the tip were reacted away with very high spatial resolution.     

High and dry: high elevations disproportionately exposed to regional climate change in Mediterranean-climate landscapes

Context

Predicting climate-driven species’ range shifts depends substantially on species’ exposure to climate change. Mountain landscapes contain a wide range of topoclimates and soil characteristics that are thought to mediate range shifts and buffer species’ exposure. Quantifying fine-scale patterns of exposure across mountainous terrain is a key step in understanding vulnerability of species to regional climate change.

Objectives

We demonstrated a transferable, flexible approach for mapping climate change exposure in a moisture-limited, mountainous California landscape across 4 climate change projections under phase 5 of the Coupled Model Intercomparison Project (CMIP5) for mid-(2040–2069) and end-of-century (2070–2099).

Methods

We produced a 149-year dataset (1951–2099) of modeled climatic water deficit (CWD), which is strongly associated with plant distributions, at 30-m resolution to map climate change exposure in the Tehachapi Mountains, California, USA. We defined climate change exposure in terms of departure from the 1951–1980 mean and historical range of variability in CWD in individual years and 3-year moving windows.

Results

Climate change exposure was generally greatest at high elevations across all future projections, though we encountered moderate topographic buffering on poleward-facing slopes. Historically dry lowlands demonstrated the least exposure to climate change.

Conclusions

In moisture-limited, Mediterranean-climate landscapes, high elevations may experience the greatest exposure to climate change in the 21st century. High elevation species may thus be especially vulnerable to continued climate change as habitats shrink and historically energy-limited locations become increasingly moisture-limited in the future.

     

First detection of Hepatitis E virus (Orthohepevirus C) in wild brown rats (Rattus norvegicus) from Great Britain

In the United Kingdom, there has been an increase in the number of hepatitis E virus (HEV) infections in people annually since 2010. Most of these are thought to be indigenously acquired Orthohepevirus A genotype 3 (HEV G3), which has been linked to pork production and consumption. However, the dominant subgroup circulating in British pigs differs from that which is found in people; therefore, an alternative, potentially zoonotic, source is suspected as a possible cause of these infections. Rodents, brown rats (Rattus norvegicus) in particular, have been shown to carry HEV, both the swine HEV G3 genotype and Orthohepevirus C, genotype C1 (rat HEV). To investigate the prevalence of HEV in British rodents, liver tissue was taken from 307 rodents collected from pig farms (n = 12) and other locations (n = 10). The RNA from these samples was extracted and tested using a pan‐HEV nested RT‐PCR. Limited histopathology was also performed. In this study, 8/61 (13%, 95% CI, 5–21) of brown rat livers were positive for HEV RNA. Sequencing of amplicons demonstrated all infections to be rat HEV with 87%–92% nucleotide identity to other rat HEV sequences circulating within Europe and China (224 nt ORF‐1). Lesions and necrosis were observed histologically in 2/3 samples examined. No rat HEV RNA was detected in any other species, and no HEV G3 RNA was detected in any rodent in this study. This is the first reported detection of rat HEV in Great Britain. A human case of rat HEV infection has recently been reported in Asia, suggesting that rat HEV could pose a risk to public health.     

Recreational exposure to low concentrations of microcystins during an algal bloom in a small lake

We measured microcystins in blood from people at risk for swallowing water or inhaling spray while swimming, water skiing, jet skiing, or boating during an algal bloom. We monitored water samples from a small lake as a Microcystis aeruginosa bloom developed. We recruited 97 people planning recreational activities in that lake and seven others who volunteered to recreate in a nearby bloom-free lake. We conducted our field study within a week of finding a 10-μg/L microcystin concentration. We analyzed water, air, and human blood samples for water quality, potential human pathogens, algal taxonomy, and microcystin concentrations. We interviewed study participants for demographic and current health symptom information. Water samples were assayed for potential respiratory viruses (adenoviruses and enteroviruses), but none were detected. We did find low concentrations of Escherichia coli, indicating fecal contamination. We found low levels of microcystins (2 μg/L to 5 μg/L) in the water and (<0.1 ng/m³) in the aerosol samples. Blood levels of microcystins for all participants were below the limit of detection (0.147μg/L). Given this low exposure level, study participants reported no symptom increases following recreational exposure to microcystins. This is the first study to report that water-based recreational activities can expose people to very low concentrations of aerosol-borne microcystins; we recently conducted another field study to assess exposures to higher concentrations of these algal toxins.