动物基因转移技术

Grodon首先于1980年报道,转移克隆化的外源DNA到小鼠体中,而使小鼠的所有细胞都含有外源基因。随后又有很多类似报道,被整合的外源基因,即转基因被稳定地整合到转基因动物的基因组中,并按孟德尔方式遗传。然而,转基因动物内在的潜力却首先是由Palmiter等(1982)证明的。他们发现,当转移到小鼠体内的生长激素基因表达时,明显增加了生长速度。近十年来,转基因小鼠通常都用做研究工具,很多实验室试图应用这一技术来改变家畜的基因型。到本世纪末或下世纪     

Effects of challenge dose on the clinical and immune responses of cattle vaccinated with reduced doses of Brucella abortus strain 19

Fifty-seven pregnant beef heifers that were unvaccinated or previously vaccinated with Brucella abortus S19, at a dose of either 10⁹ or 10¹⁰ colony-forming units (CFU), were challenge-exposed intraconjunctivally with virulent B. abortus S2308 at a dose of 9.4 × 10⁶ CFU (Experiment 1) or 5.2 × 10⁷ CFU (Experiment 2). In Experiment 1, S19 afforded significant protection (P < 0.01) against challenge exposure in that 8 of 9 unvaccinated heifers, 1 of 11 vaccinated with 10⁹ CFU, and 3 of 10 vaccinated with 10¹⁰ CFU aborted or delivered weak, non-viable calves. In Experiment 2, vaccination did not afford significant protection (P> 0.05) in that 9 of 9 unvaccinated heifers, 8 of 10 vaccinated with 10⁹ CFU, and 8 of 8 vaccinated with 10¹⁰ CFU aborted. Serologic responses to B. abortus were determined by three standard tests, as well as a quantitative fluorometric immunoassay (FIAX) and an enzyme-linked immunosorbent assay. In Experiment 1, the early serologic response, 0–8 weeks after challenge, appeared greater for controls than for vaccinates, but in Experiment 2, the early response, 0–6 weeks after challenge exposure, appeared greater for vaccinates than for controls. The lymphocyte blast transformation assay, using heat-killed B. abortus as an antigen, was performed sequentially after challenge exposure. In general, mean responses were significantly higher (P < 0.05) for vaccinated than for non-vaccinated heifers. For individual heifers, an association could not be established between the lymphocyte blast transformation assay and the clinical response to challenge exposure.     

Guidelines on the recognition of pain, distress and discomfort in experimental animals and an hypothesis for assessment

Under the 1876 Cruelty to Animals Act it is necessary to recognise pain so that an assessment may be made to determine if it is 'an experiment calculated to give pain' and 'to prevent the animal feeling pain'. Under the conditions of the licence it is also necessary to recognise 'severe pain which is likely to endure' and 'suffering considerable pain'. In the White Paper May 1983 (Command 8883) it is stated that: 'in the application of controls the concept of pain should be applied in a wide sense' and 'the Home Secretary's practice has been to interpret the concept of pain to include disease, other disturbances of normal health, adverse change in physiology, discomfort and distress'. The draft European Convention for the Protection of Vertebrate Animals used for Experimental and other Purposes, aims to control, subject to specific exceptions, any experimental or other scientific procedure which 'may cause pain, suffering, distress or lasting harm'. (The White Paper states that UK control will be stricter than the Council of Europe proposals.) Thus, there is a considerable onus on the experimenter to recognise pain (not to define it) and to alleviate it. It is intended that this article should be of help, not only to newcomers inexperienced in the recognition of pain, but also possibly to those relatively experienced workers who may be called upon to evaluate the pain involved in a new model or an individual animal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Polyarthritis in wild mice (Mus musculus) caused by Streptobacillus moniliformis

SUMMARY Mice trapped on farms in south-eastern Queensland had chronic abscessating osteoarthritides mainly involving the carpi and tarsi. Pleomorphic bacteria were shown by silver staining to be plentiful within lesions. Streptobacillus moniliformis was isolated from the joints, and streptobacillary polyarthritis was diagnosed. Other lesions observed included subcutaneous and hepatic abscesses.     

A serological survey of Ehrlichia canis, Ehrlichia equi, Rickettsia rickettsii, and Borrelia burgdorferi in dogs in Oklahoma

Serum samples from 259 dogs were tested for antibodies to Ehrlichia canis, Ehrlichia equi, Rickettsia rickettsii, and Borrelia burgdorferi using the indirect fluorescent antibody test. The sera were obtained from submissions to the Oklahoma Animal Disease Diagnostic Laboratory during a 14-month period from June 1986 through July 1987. The rate for positive antibody titers to E. canis was 53%, to E. equi was 33%, to R. rickettsii was 38%, and to B. burgdorferi was 18%. Higher percentages of sera serologically positive to E. canis were found in the spring through the fall months, but there were no seasonal variations for E. equi, R. rickettsii, and B. burgdorferi. There was no consistent pattern of titers to the 4 antigens when age-groups of the dogs were compared. Forty-four different breeds were tested.     

Acute tularemia in three domestic cats.

Acute Francisella tularensis infection in 3 domestic cats was presumptively diagnosed on the basis of clinical signs and lesions and confirmed by culturing or immunofluorescent demonstration of the organism. Clinical findings include marked signs of depression, oral/lingual ulceration, regional or generalized lymphadenomegaly, hepatosplenomegaly, panleukopenia with severe toxic change of neutrophils, and hyperbilirubinemia with bilirubinuria. Lesions found at necropsy included icterus, oropharyngeal and lingual ulceration, multiple foci of necrosis in lymph nodes, spleen, liver, and lung, and severe segmental or diffuse enterocolitis. Results of serologic testing for F tularensis was positive in only 1 of the 3 cats. The organism was cultured aerobically from several tissues, including aspirated bone marrow obtained before death in 1 cat. Results of an indirect fluorescent antibody test, performed on fresh and formalin-fixed tissues of all cats, were positive. Because of the severe clinical course, opportunity to evaluate therapeutic regimens was not possible. Until now, confirmed diagnosis of feline tularemia only has been made retrospectively, in instances when cats were suspected to have transmitted infection to human beings in whom the primary diagnosis was made. The findings in this report provide a basis for presumptive diagnosis that will help to minimize public health risk associated with this potentially fatal zoonotic disease.     

The ‘Electrodyn’ sprayer: first studies of spray coverage in cotton

A programme of investigation was started in mid-1977 in Spain into the performance of the ‘Electrodyn’ sprayer for the control of insect pests on cotton. The first stages of the programme, reported in this paper, evaluated the effect on spray deposition and distribution of emission height, speed of travel, wind speed, and position of the ‘Electrodyn’ sprayer nozzle relative to the row, in order to define the optimum method of use. In replicated field trials ultra-low-volume low volatile formulations were applied and performance was measured by assessing subjectively fluorescent spray deposition and distribution over samples of all plant structures at two heights in the plant. Plants were sampled from one row upwind and three rows downwind from each single spray run. The overall distribution of fully charged spray from the ‘Electrodyn’ sprayer was, in general, similar to that of discharged spray applied by the ‘Electrodyn’, with more than 80% deposited on ‘top’ leaves. A smaller proportion of the fully charged spray cloud penetrated to the lower half of the crop than did discharged spray. Variability from leaf to leaf was less and, of the total spray recovered, the proportion deposited on the main stem and branches in the top of the plant was four times greater, with charged than discharged spray. Cover of a greater part of the circumference of stems and branches and the only significant underleaf cover (the ‘wrap-around’ effect) was achieved by charged spray in the top of the plant and there was a concentration of spray at the tips and edges of leaves and bracts. Subjective assessments of deposition showed that 2·5 times more spray was recovered in the crop when charged than when discharged In practice the improvement could range from about 1·25 to 5 times depending upon the efficiency of the conventional system. Different speeds of travel, between 0·5 and 1·5 m/s (the highest reported) did not affect pest-control performance. An optimum mode of use was devised to facilitate subsequent comparisons of pest control between the ‘Electrodyn’ sprayer, rotary atomizers, and hydraulic nozzle sprayers. The ‘Electrodyn’ sprayer should be held downwind of the operator. At a nominal walking speed of 1·0 m/s in cotton less than 0·4 m tall, the nozzle is held 0·2 m directly above the row and all rows are sprayed: in taller cotton (0·4–1·5 m) the nozzle is held above the inter-row space and either taken along every inter-row with the nozzle 0·2–0·4 m above the crop, or, for low input/high risk crops (minimum levels of pest control) the nozzle is taken along alternate inter-rows, 0·4–0·5 m above the crop.     

Studies on the mechanism of inhibition of adrenal steroidogenesis by organophosphate and carbamate compounds

The observation was made that adrenal steroidogenesis in rat adrenal cells is inhibited in vitro by organophosphate and phosphorothioate esters and carbamates. The order of inhibitory potency is organophosphate ? phosphorothioate > carbamate. The inhibition of steroidogenesis by dichlorvos is accompanied by a parallel inhibition of [1-¹⁴C]oleic acid incorporation into the esterified cholesterol fraction of the adrenal cell. At a lower concentration of the inhibitor, adrenocorticotrophic hormone reverses the inhibition of cholesterol esterification. There is no correlation between changes in adenosine 3′,5′-cyclic monophosphate levels and inhibition of steroidogenesis. One insecticide, diazinon, produced a lowering of the cyclic nucleotide levels at concentrations of the compound which produced steroidogenic inhibition. Subinhibitory levels of this insecticide produced a significant elevation of cellular adenosine 3′,5′-cyclic monophosphate levels and yet inhibited steroidogenesis. Both of these insecticides inhibited adenosine 3′,5′-cyclic monophosphate binding to rat adrenal adenosine 3′,5′-cyclic monophosphate-binding protein. Dichlorvos inhibited the diurnal increase in plasma corticosteroid by 49.2% when administered to rats at a dose of 2 mg/100 g body weight/24 hr for a 2-week period.