摘要:

In the 36 years since Watson and Crick proposed the double helix structure for DNA, molecular biology has evolved from a highly specialized, academic pursuit into the most dynamic and influential life science of the 20th century.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35555

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

DNA extracted fromMycobacterium paratuberculosis, which had been isolated from a cow with clinical Johne's disease, was used to make a gene library in theEscherichia coliexpression vector phage λgt11. Plaque-lifts were made from the library onto nitrocellulose membranes. These were screened by differential hyhridization using radiolabelled chromosomal DNA fromM. paratuberculosisandMycobacterium phlei.By this method six recomhinants that hybridized toM. paratuberculosisbut not toM. phleiwere identified. Three of these, designated λgt-R3, λgt-R4 and λgt-R5, containing DNA inserts of 2.5,1.5 and 3.7 kilobases (kb), respectively, were chosen for further analysis of their insert specificities. Following restriction with the endonucleases EcoRI and BamHI, the digestion fragments from the three recombinants were transferred to nitrocellulose membranes and probed with radiolabelled DNA fromM. pamtuberculosisandM. phlei.As expected,M. paratuberculosisDNA hybridized to all the fragments.M. phleiDNA hybridized to both the fragments that were generated from λgt-R3, to the single fragment from λgt-R4 and to two of the three fragments generated from λgt-R5. The fragment with whichM. phleiDNA failed to hyhridize was 0.45 kb in length. Multiple copies of this fragment were made in the plasmid pGEM-2; the plasmid DNA was then harvested and radiolabelled. Designated PAM-1, the radiolabelled material hybridized to a 3.7 kb fragment of EcoRI-digestedM. paratuberculosisand to 2.2 kb fragments of similarly digestedM. avium serovars2 and 3. PAM-1 did not hybridize to DNA from the other four mycobacterial species examined or fromNocardia asteroides.The restriction fragment length polymorphism thus demonstrated distinguishesM. paratuberculosisfromM. avium serovars2 and 3.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35556

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35557

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Serum inorganic phosphorus (Pi) and calcium (Ca) concentrations were assessed in 20 cows on each of four Manawatu factory supply dairy farms. Blood was taken from each cow before calving and at six-week intervals during lactation. Bleeding coincided with herd testing. Herds of Friesian or Friesian X cows and Jersey or Jersey X cows were compared on adjacent farms on a Central Yellow-brown Sand and on adjacent farms on a Peat Loam overlying a Central Yellow-brown Earth soil. Pasture mass and composition were estimated to grazing height in the next two paddocks to be grazed in the rotation. Mean serum Pi concentration was higher in cows on sandy soils (1.55 mmol Pi/ℓ) than in cows on the peat loam (1.34 mmol Pi/ℓ (P<0.001). Concentrations were highest before calving (1.69 mmol Pi/ℓ) but fell to low levels at peak lactation (1.17mmol Pi/ℓ) when 70% of cows were below the minima of the ‘normal range’, and during the drought (1.29 mmol Pi/ℓ). Pasture phosphorus (P) concentrations were adequate to support cow nutritional P requirements for lactation (>0.33% DM,ad lib. feeding) until the summer drought when low herbage mass would have restricted milk production. Serum Ca was adequate for lactating cows and changed little between months or between cows (mean 2.12 mmol Ca/ℓ). No metabolic disorders relating to mineral deficiencies were observed. It appears that serum Pi in a high proportion of cows falls below the normal range during peak lactation without cows displaying clinical deficiency symptoms or a depression in butterfat production.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35558

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Goats and sheep were pastured together and held in close contact in yards twice a month for 21 months. The goats had a high prevalence of both the rabbit ear canker mite,Psoroptes cuniculiand the chorioptic mange mite,Chorioptes bovis.The sheep were not infested withP. cuniculiat the beginning of the study and viableC. boviscould not be detected.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35559

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Electrocardiograms (ECG's) were made from cattle and pigs after slaughter using only the “left arm” and “right arm” recording electrodes of a portable electrocardiogram with l2 recording electrodes. Functional heart activity was demonstrated in cattle after stunning with a captive bolt, nonpenetrative percussive methods and a head-only electrical technique. Recordings compatible with ventricular fibrillation were made in the majority of cattle and pigs subjected to a head-to-chest form of electrical stunning. In cases where the placement of stunning electrodes was defective, functional cardiac activity could be detected. Movement artefact on the ECG trace associated with epileptiform seizures following head-only electrical stunning was a technical problem. This was reduced by restunning the animal with a captive bolt before taking an ECG.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35560

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Benzimidazole resistance involving several gastrointestinal nematode genera on a single sheep farm in New Zealand is reported for the first time. A controlled slaughter trial showed that at the recommended dose rate of 12.5 mg/kg, mebendazole had efficacies of 0, 60, 66, 90, 54 and 38% againstHaemonchus contortus, Ostertagiaspp.,Nematodirusspp., intestinalTrichostrongylusspp.,Strongyloidesspp. andOesophagostomum venulosum, respectively. The relevance of such multigeneric resistance to possible future options for controlling anthelmintic resistant sheep trichostrongylids is briefly discussed.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35561

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A number of iron compounds have been shown to protect sheep against the harmful effects of the facial eczema toxin, sporidesmin. Various salts were found to be effective; the oxidation state of the metal was not important although water-solubility did appear to be a prerequisite for prophylactic activity. The effect of iron salts was additive with that of zinc, and it is suggested that the protective action of these compounds results from their ability to inhibit the absorption of copper, consistent with the previously-proposed freeradical mechanism for sporidesmin toxicity.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35562

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Episodes of frenzy lasting approximately 30 minutes were observed among horses confined to enclosures surfaced with sand or soil. The probability of sighting these episodes increased by a factor of three when within 24 hours there was 0.2mm or more of rain, a maximum air temperature between 16.7 – 26.6°and a soil temperature of 16.3 – 23.9°C at 30 cm. High egg counts ofStrongyloides westeriappeared in faeces four to five days later and persisted for several days.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35563

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A case of brodifacoum poisoning is described in a six-year-old male Kelpie cross working dog. The clinical features were severe exercise intolerance, haemorrhage from the oral and nasal cavities, dyspnoea and pale mucous membranes. Diagnosis was confirmed by demonstrating an abnormally long whole blood clotting time. The dog was treated successfully by administering 1 litre of whole blood intravenously, intramuscular vitamin K1and a three week course of oral vitamin K3.

ISSN:0048-0169    

DOI:10.1080/00480169.1989.35564

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor