The pulmonary clearance of Pasteurella haemolytica in calves infected with bovine virus diarrhea or Mycoplasma bovis.

Based on current literature which commonly associates bovine virus diarrhea virus and Mycoplasma bovis with "pneumonic pasteurellosis," an investigation was conducted into the effect of these two pathogens on the capacity of bovine lung to clear inhaled Pasteurella haemolytica. There was no significant effect (p less than 0.05) of either bovine virus diarrhea virus or M. bovis on the mean clearance rate of P. haemolytica, nor did the time interval of three, five or seven days between the first inoculation and exposure to P. haemolytica and adversely affect the lung clearance rates. However, it was found that the left lungs and a higher bacterial retention (p less than 0.05) than the right lungs.     

An exploration of the drivers to bio-security collective action among a sample of UK cattle and sheep farmers

At present, collective action regarding bio-security among UK cattle and sheep farmers is rare. Despite the occurrence of catastrophic livestock diseases such as bovine spongiform encephalopathy (BSE) and foot and mouth disease (FMD), within recent decades, there are few national or local farmer-led animal health schemes. To explore the reasons for this apparent lack of interest, we utilised a socio-psychological approach to disaggregate the cognitive, emotive and contextual factors driving bio-security behaviour among cattle and sheep farmers in the United Kingdom (UK). In total, we interviewed 121 farmers in South-West England and Wales. The main analytical tools included a content, cluster and logistic regression analysis.The results of the content analysis illustrated apparent ‘dissonance’ between bio-security attitudes and behaviour.¹ Despite the heavy toll animal disease has taken on the agricultural economy, most study participants were dismissive of the many measures associated with bio-security. Justification for this lack of interest was largely framed in relation to the collective attribution or blame for the disease threats themselves. Indeed, epidemic diseases were largely related to external actors and agents. Reasons for outbreaks included inadequate border control, in tandem with ineffective policies and regulations. Conversely, endemic livestock disease was viewed as a problem for ‘bad’ farmers and not an issue for those individuals who managed their stock well. As such, there was little utility in forming groups to address what was largely perceived as an individual problem.Further, we found that attitudes toward bio-security did not appear to be influenced by any particular source of information per se. While strong negative attitudes were found toward specific sources of bio-security information, e.g. government leaflets, these appear to simply reflect widely held beliefs. In relation to actual bio-security behaviours, the logistic regression analysis revealed no significant difference between in-scheme and out of scheme farmers.We concluded that in order to support collective action with regard to bio-security, messages need to be reframed and delivered from a neutral source. Efforts to support group formation must also recognise and address the issues relating to perceptions of social connectedness among the communities involved.     

Transformation of Digitaria sanguinalis: A model system for testing maize streak virus resistance in Poaceae

Digitaria sanguinalis, an African grass, was micropropagated from immature inflorescences and callus was transformed by particle gun bombardment. Integration and expression of the bar and uidA genes was shown in the T₀ generation. Transformants were shown to be fertile by the production of viable seeds. The time taken from bombardment to the setting of seed was approximately four months. D. sanguinalis and its transformants were shown to be sensitive to maize streak virus (MSV). Therefore this is an ideal model system for testing genetically engineered resistance to MSV. This revised version was published online in August 2006 with corrections to the Cover Date.     

Trial of a novel experimental Toxoplasma iscom vaccine in pregnant sheep

Fifteen vaccinated ewes (group 1) and 13 unvaccinated ewes (group 2) were each challenged orally with 2000 sporulated Toxoplasma gondii oocysts at 91 (+/- 1) days' gestation. Another four pregnant ewes acted as unvaccinated unchallenged controls. Lamb mortality in group 1 was 36.4% after a mean gestation of 141 days while in group 2 it was 64.7% after a mean gestation of 131.5 days. These differences were not statistically significant. However, substantially more specific antibody was detected in precolostral sera from live lambs from vaccinated ewes than in live lambs from unvaccinated ewes in group 2.     

Catastrophic decline of a top carnivore in the gulf of california rocky intertidal zone

The predatory sun star, Heliaster kubiniji, once the commonest rocky intertidal asteroid of the Gulf of California, has been rare throughout this region since summer 1978 when a devastating disease outbreak occurred. This unprecedented phenomenon and several other exceptional ecological events in marine communities of the northeastern Pacific appear to be linked to large-scale climatic changes that occurred during 1977 and 1978. Implications of the decline in Heliaster kubiniji are discussed.     

The Origin of Membrane Vesicles in Ram Seminal Plasma

The hypothesis tested in this study was that the membrane vesicles present in ram seminal plasma are of testicular origin, rather than being secreted by the accessory sex glands as has been previously reported for a number of species. Membrane vesicles were present in cellular extracts from reproductive organs and accessory sex glands of six rams, and in the seminal plasma of a further eight rams. When four of the latter rams were subjected to vasectomy, to isolate ejaculate contents to only the secretions of the accessory sex glands, the vesicles were largely eliminated from their ejaculates, while vesicles were still present in the ejaculates of the four control rams. The constituents of the cytoplasmic droplets and membrane vesicles derived from the seminal plasma were compared by transmission electron microscopy (TEM). Vesicles present in the cytoplasmic droplets were similar in morphology but smaller on average than those in the seminal plasma. It was concluded that the membrane vesicles in ram seminal plasma originate from either the cytoplasmic droplets, or a combination of vesicles from the droplets and the epididymis.     

Autologous Whole Ram Seminal Plasma and its Vesicle-free Fraction Improve Motility Characteristics and Membrane Status but not In Vivo Fertility of Frozen–Thawed Ram Spermatozoa

Motility characteristics (assessed subjectively and with computer-assisted semen analysis) and membrane status (after staining with chlortetracycline) of washed and non-washed frozen-thawed ram spermatozoa were evaluated after incubation in buffer and buffer containing autologous whole seminal plasma or one of its two fractions: the pellet of membrane vesicles obtained by ultracentrifugation (and used at three times normal protein concentration) or the vesicle-free supernatant fraction. Whole seminal plasma and supernatant, but not membrane vesicles, improved the motility characteristics of spermatozoa after 3 and 6 h of post-thaw incubation compared with the control buffer. Resuspension and incubation with whole seminal plasma, supernatant or membrane vesicles lowered the proportion of acrosome-reacted frozen-thawed spermatozoa compared with the control buffer. Unwashed frozen-thawed semen from three rams, incubated with autologous whole seminal plasma or its fractions and inseminated using cervical or intrauterine artificial insemination, had no effect on pregnancy rates of ewes in synchronized oestrus. However, fertility was higher after laparoscopic than cervical insemination (44.9 vs 12.3%, p < 0.001). In conclusion, resuspension and incubation of frozen-thawed ram spermatozoa in autologous whole seminal plasma or its vesicle-free supernatant fraction improved their motility characteristics and, with membrane vesicles, membrane status, but these benefits were not reflected in improved fertility after cervical or intrauterine insemination.