附加性状在奶牛育种中的应用

当前国内外多数学者认为,家畜的附加性状(亦称标记性状或遗传标记)应包括生化遗传标记和细胞遗传标记两个方面(实际上还应包括生理学的和免疫学的两个方面)。它们是研究品种内和品种间差异的遗传、选择优秀家畜个体或群体、查清地方品种的遗传潜力的一种有效方法,其主要用途是在家畜育种中可作为标记基因来充实常规的选种方法,特点是在种畜的早期选择中具有重要意义。     

CANINE ANTISERUMS ANALOGOUS TO HUMAN ALLERGIC AND "BLOCKING" ANTISERUMS

The serums of dogs that are allergic to ragweeed can passively sensitize normal dogs. Cutaneous reactions or systemic anaphylaxis may be produced by appropriate challenge with ragweed extract. Canine antiserum produced by immunization of normal dogs with ragweed extract is shown to inhibit these reactions of the passively sensitized dogs.     

Foot-and-mouth disease virus: a long known virus, but a current threat

Foot-and-mouth disease virus (FMDV) was the first animal virus identified. Since then, FMDV has become a model system in animal virology and a considerable amount of information on its structure, biology and vaccinology has been obtained. However, the disease that this virus produces (FMD) still constitutes one of the main animal health concerns. In this review, we have attempted to summarise the state of the knowledge in different basic and applied areas of FMDV research, with emphasis on those aspects relevant to the control of the disease.     

Ethyl cellulose polymer microspheres for controlled release of norfluazon

The pesticide norfluazon has been microencapsulated using ethyl cellulose to develop controlled-release formulations that decrease its mobility through the soil and protect it from photodegradation. Ethyl cellulose microspheres loaded with norfluazon were prepared by the solvent-evaporation method. To obtain the microspheres, certain conditions (pesticide/polymer ratio, percentage of emulsifying agent and solvent) were varied. The shape and size of the microspheres obtained were studied by scanning electron microscopy. Other parameters, such as solids recovery, encapsulation efficiency and pesticide loading, were also studied. The release rate of norfluazon from the different microspheres was slower than that of pure norfluazon. In particular, microspheres obtained with o-xylene, which provided the largest diameter, retarded the initial release of the pesticide relative to microspheres obtained with chloroform, or to pure norfluazon. Moreover, the studies showed that the pesticide/polymer ratio controlled the release of norfluazon, which was slower when this ratio was low. Release rates conformed to a generalised kinetic equation for a diffusion-controlled release mechanism, and the time taken for 50% of the active ingredient to be released into water, t50, was calculated.     

Identification of a novel collagen-like protein, SclC, in Streptococcus equi using signal sequence phage display

Strangles is a serious disease in horses caused by Streptococcus equi subspecies equi. In this study, genes encoding putative extracellular proteins in this subspecies have been identified using signal sequence phage display. Among these, one showed similarities to the SclB protein, a member of the collagen-like proteins of Streptococcus pyogenes. The novel gene denoted sclC encodes a protein, SclC, of 302 amino acids, containing typical features found in cell wall-anchored proteins in Gram-positive bacteria. Based on similarities to the S. pyogenes collagen-like proteins the mature SclC protein can be divided into various domains: an N-terminal non-repetitive region (A), a highly repetitive collagen-like region (CL), and a C-terminal proline-rich wall-associated region (W). Using PCR, the sclC gene was detected in all studied strains of S. equi subsp. equi and S. equi subsp. zooepidemicus. Further, antibodies against recombinant SclC were detected in a collection of sera from horses with no history of strangles as well as horses previously infected with S. equi subsp. equi. Interestingly, the sera from convalescence horses were found to have significantly increased antibody titers against the SclC protein indicating that this protein is expressed during infection of S. equi subsp. equi.     

Systemic mycosis due to Aspergillus deflectus in a dog

A 4-year-old, entire female, German Shepherd Dog was referred with a 3-month history of right foreleg lameness that partially responded to nonsteroidal anti-inflammatory and antimicrobial therapy. The bitch lost weight, was polydipsic and had reduced exercise tolerance. On referral, the animal was in poor condition, pyrexic and exhibited moderate pain on full extension of the right shoulder. Blood, urine and joint fluid were obtained and radiographs were taken of the right shoulder and chest. The bitch was lymphopaenic, hyperfibrinogenaemic, hyperglobulinaemic, mildly azotaemic, mildly proteinuric and isosthenuric. Branching fungal hyphae were present in the urine. On radiography, the thorax contained a large ventral mediastinal mass and the humeral head had extensive areas of radiolucency. An aspirate from the right humeroscapular joint exhibited branched fungal hyphae and numerous neutrophils and macrophages. A diagnosis of disseminated mycosis was made and euthanasia was performed. At necropsy, numerous caseating granulomas were present, especially in the kidneys, adrenal glands, heart and lymph nodes. Extensive osteomyelitis involved the head of the right humerus, the sternebrae and the fifth intervertebral disc. Fungal hyphae were detected in sections of granulomas in all affected organs and a diagnosis of disseminated fungal granulomatosis was made. Aspergillus deflectus was readily isolated from affected lymph nodes, but confirming its identity as A deflectus using standard procedures proved difficult. The identity of the fungus was finally confirmed by sequencing part of the 185 rRNA of the isolate. This is the first report in Australia of a disseminated mycosis caused by A deflectus. Previously, the involvement of A deflectus as a cause of disseminated mycosis was limited to 5 cases from the West Coast of the USA, four of which occurred in German Shepherd Dogs.     

Study of Fuzzy Control for Broom's Speed Adjustment

This paper deals with the adjustment of broom's speed of the sweeper. The Fuzzy control theory was utilized to study and design of the Fuzzy Controller.