Choice of social conditions by laying hens

1. To test the preferences of hens for particular social conditions when laying, they were provided with choices of nest‐sites varying in seclusion. Three experimental conditions were used.

2. In Experiment 1, nest‐site selection by members of a group of light hybrids was studied in a complex pen‐system. Eggs were clumped in distribution ; only one individual laid in the most secluded part of the system.

3. Experiment 2 provided light hybrids with an extensive outdoor area, but similarly clumped laying was observed; there was no indication that hens attempted to find concealment for nesting.

4. In Experiment 3, hens from a group of light hybrids just coming into lay and from a group of mature medium hybrids were tested singly, in an area that included a cage containing some of their flockmates. Most subjects from both groups laid near the other birds rather than in isolation.

5. In semi‐intensive conditions, the majority of hens are apparently gregarious rather than solitary in their nesting behaviour.     

Development of multiple cutaneous and follicular neoplasms associated with canine papillomavirus type 3 in a dog

A 12‐year‐old spayed English pointer dog developed multiple skin lesions including pigmented viral plaques, basal cell carcinomas, squamous cell carcinomas and trichoblastomas. Canine papillomavirus type 3 was detected in multiple lesions suggesting common aetiology.

     

A patch—clamp study of the action of a nitromethylene heterocycle insecticide on cockroach neurones growing in vitro

The mode of action of a nitromethylene heterocycle (NMH) insecticide was studied by patch–clamp techniques using cockroach embryonic cultures as an experimental model. Under whole-cell recordings, this compound elicited inward currents resembling those induced by O-acetylcholine (ACh). The reversal potentials for both ACh and the NMH were similar, suggesting that the inward currents induced by both were carried by the same species of ion. Pharmacological investigations of NMH-induced responses revealed that the insecticidal action of this compound is exerted through agonistic action at the nicotinic acetylcholine receptor. Single-channel studies were also performed to study the interaction of NMH with the nicotinic-receptor-coupled ion channel.     

Prevalence of cpb2, encoding beta2 toxin,in Clostridium perfringens field isolates: correlation of genotype with phenotype

Beta2 toxin, encoded by the cpb2 gene, has been implicated in the pathogenesis of porcine, equine and bovine enteritis by type A Clostridium perfringens. By incorporating primers to cpb2 into a multiplex genotyping PCR, we screened 3270 field isolates of C. perfringens. Of these, 37.2% were PCR positive for the cpb2 gene. The majority of isolates from cases of porcine enteritis were positive for cpb2 (>85%), and this was even more true for C. perfringens isolated from cases of porcine neonatal enteritis (91.8%). In contrast, isolates from normal pigs only contained cpb2 in 11.1% of cases. The correlation between enteritis in other animal species and the presence of cpb2 was not so strong. cpb2 was found in 21.4% of C. perfringens isolates from cattle with enteritis, and in 47.3% of isolates from calves with enteritis or abomastitis. The prevalence of cpb2 varied with genotype, with type A isolates being positive for this gene in 35.1% of cases. Furthermore, enterotoxigenic type D or type E strains almost always carried cpb2. We cloned a 6xHIS-tagged beta2 (HIS-beta2) and used this protein to raise antiserum against beta2. Culture supernatants from 68 cpb2-positive and 13 cpb2-negative strains were tested for the presence of beta2 by Western blotting. In cpb2-positive isolates of porcine origin, beta2 was almost always detected (96.9%). However, in cpb2-positive isolates from other animal species, only 50.0% expressed beta2 protein. The high rate of cpb2-positivity among strains from neonatal pigs with enteritis and the high correlation of genotype with phenotype, supports the contention that beta2 toxin plays a role in the pathogenesis of these infections. However, it may be important to consider the use of an additional method for the detection of beta2 toxin in non-porcine cpb2-positive isolates when making claims about the role of beta2 in enteritis in non-porcine species.     

Effects of temperature and time in transit on polymerase chain reaction detection of feline herpesvirus DNA.

The purpose of this study was to report methods currently recommended by commercial laboratories for collecting, shipping, and processing of samples for feline herpesvirus type 1 (FHV-1) testing using polymerase chain reaction (PCR) and to determine the effect of temperature and time on the ability of 1 PCR method to detect FHV-1 DNA in experimental and clinical samples. Eleven laboratories offering FHV-1 PCR were surveyed. There was notable variation in sample types and shipping conditions recommended and PCR protocols used by these laboratories. Subsequently, using a single PCR method, FHV-1 DNA was detected in samples exposed to various temperatures within the laboratory. Finally, FHV-1 PCR was performed on paired clinical samples collected from 25 cats and shipped at ambient temperatures via US Postal Service (USPS) or with an ice pack via a courier. Samples sent by USPS were exposed to significantly longer transit time and arrived at significantly higher temperature than did samples sent by courier. Despite this, all sample pairs yielded concordant results when tested for FHV-1 DNA using this PCR method. Although it may not be necessary for samples collected for detection of FHV-1 DNA using this PCR method to be shipped under the most expedient or temperature-controlled conditions, this should be verified for a variety of PCR assays and sample types.     

Diagnostic cytology of fish.

Cytology is an essential part of a diagnostic workup in cases of aquatic animal diseases. It is simple to perform, inexpensive, and can yield quick and valuable results. External parasites, bacterial and fungal diseases, and gastrointestinal infestations are easily determined with wet mount cytology. Because of the relatively small number of nonlethal diagnostic techniques available for aquatic species, cytologic testing should be considered in every case. Early diagnosis can lead to more effective treatment plans, ensuring a better prognostic outcome in our patients.     

Major gene resistance in Brassica napus (oilseed rape) is overcome by changes in virulence of populations of Leptosphaeria maculans in France and Australia

Resistance of Brassica napus (oilseed rape, canola) conferred by three different major resistance genes has been overcome by changes in virulence of Leptosphaeria maculans populations in France and Australia. In South Australia where B. napus cultivars with major gene resistance derived from Brassica rapa ssp. sylvestris were grown extensively, resistance was rendered ineffective within 3 years of commercial release of the cultivar. Disease severity was higher on cultivars with sylvestris-derived resistance than cultivars with polygenic resistance. This Australian situation is compared to that in France, where resistance conferred by the Rlm1 gene was overcome nation-wide in 5 years under commercial cropping practices, and also where a source of resistance introgressed into B. napus from B. juncea was rendered inefficient in 3 years in experimental field plots near Rennes.