The structure of bovine secretory component     

D Beale 《Veterinary immunology and immunopathology》1987,17(1-4):37-49

Bovine secretory component (SC) has been cleaved with trypsin into a series of fragments and their N-terminal amino acid sequences have been determined. The close homology with the known sequence of human SC has enabled the sequential order of the fragments to be deduced. The results indicate that bovine SC consists of a single glycosylated polypeptide chain (Mr 74,000) folded into five globular immunoglobulin-like domains. A protein (Mr 94,000) has been isolated from detergent solubilised bovine epithelial membranes from liver, intestine and mammary gland. This membrane protein is specific for the binding of J-chain linked IgM and IgA dimers. It can be proteolytically cleaved into a water soluble SC-like portion and a detergent soluble hydrophobic portion. Bovine SC is therefore most likely to be the extracellular part of an epithelial receptor which mediates the transport of IgA dimers to mucosal surfaces. The various tryptic fragments from bovine SC have been shown to differ in their relative binding affinities for IgM and IgA dimers. The results imply that the first three domains of bovine SC are most involved in binding and domains 4 and 5 play subsidiary roles. Computerized prediction and modelling methods have been used to deduce possible tertiary and quaternary structures for SC. There are good indications that the molecule has an elonaged "zig-zag" structure stabilized by longitudinal inter-domain contacts. A model of SC bound to IgA dimer is presented.  相似文献   

The phenomenon of stress: Concepts and mechanisms associated with stress-induced responses of the neuroendocrine system     

B. Ann Becker 《Veterinary research communications》1987,11(5):443-456

Stress, stressors and the stress response are terms which represent concepts rather than oeing precisely definable. No single theory of stress has been universally accepted. Selye's General Adaptation Syndrome of stress remains the primary theory for the basis of stress research in food-producing animals; however, other concepts and theories have been developed. This paper reviews current theories and suggests that the complexity of research on stress in food-producing animals can be attributed to the lack of concrete theories and concepts regarding identifiable stressors, the endocrine responses stimulated by potential stressors and the complex and integrated biological changes in the neuro-endocrine system resulting from exposure to hypothesized stressors.  相似文献   

Fatty acid profiles and sensory and carcass traits of tissues from steers and swine fed an elevated monounsaturated fat diet   总被引：4，自引：0，他引：4  

L C St John  C R Young  D A Knabe  L D Thompson  G T Schelling  S M Grundy  S B Smith 《Journal of animal science》1987,64(5):1441-1447

Twelve Angus X Hereford steers were assigned to either a control high-energy diet or a test diet consisting of 20% rapeseed at the expense of 20% corn. Twelve pigs were allotted to a control diet and two test diets containing either 10 or 20% canola oil (CO). Both CO and oil in the rapeseed contained 60 to 64% oleic acid. Cattle fed rapeseed exhibited little effect from the diet due to apparent indigestibility of the rapeseed. Total saturated fatty acids decreased from 40% in adipose tissue of the control pigs to 15% in the 20% CO-fed pigs. The ratio of monounsaturated to saturated fatty acids (M/S) increased from 1.19 in adipose tissue from control pigs to 3.63 with the addition of 20% CO to the diet. In muscle, the M/S ratio increased from 1.21 in control pigs to 2.46 in the 20% CO treatment group. The percentage of the saturated fatty acids in muscle decreased from 42% in the control to 23% in the 20% CO treatment. Significant increases in "oiliness" and decreases in fat firmness were observed when increasing levels of canola oil were fed. Sensory traits, cooking loss and shear-force values of pork chops were similar among treatment groups. In conclusion, monounsaturated fatty acid content can be elevated substantially in pork without adversely influencing the quality of the meat, thus producing a product perceived to be more healthful by the consumer.  相似文献   

A case of marked and unresponsive obesity          下载免费PDF全文

Forbes DC  White DE 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(4):187

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Zoonoses in laboratory animals          下载免费PDF全文

Percy DH 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(5):268-269

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Role of Rats in the Transmission of Trichinella spiralis spiralis to Swine          下载免费PDF全文

Smith HJ  Kay ED 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(9):604

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Dr Stowe's Reply          下载免费PDF全文

Stowe JD 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(12):738

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Specifics of veterinary software          下载免费PDF全文

Stowe JD 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(7):413-416

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Factor VIII Deficiency in a Cat          下载免费PDF全文

Johnstone IB  Morton JC  Allen DG 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(10):671-673

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Dark lines formed between colonies of isolates of phoma exigua var. foveata on a semi-selective medium     

L. J. Turkensteen 《European journal of plant pathology / European Foundation for Plant Pathology》1987,93(2):87-90

Samenvatting In het Instituut voor Plantenziektenkundig Onderzoek (IPO) te Wageningen wordt gangreen bij aardappel, veroorzaakt door de schimmelPhoma exigua var.foveata, onderscheiden van ander droogrot door aangetast weefsel uit te leggen op een semiselectief medium. Op dit medium wordt de vorming van kristallen van voor de schimmel kenmerkende anthrachinonen bevorderd. De gemakkelijk waar te nemen geelgroene kristallen in het medium wijzen op de aanwezigheid van de betrokken schimmel. Bij een van deze toetsen vormden zich tussen de zich ontwikkelende kolonies van de schimmel donkere lijnen. Deze lijnen verschilden van reeds eerder beschreven violette lijnen, die zich vormen tussen kolonies van de twee variëteitenexigua enfoveata vanP. exigua. Onderzoek aan 27 isolaten vanP. exigua var.foveata toonde aan dat er met betrekking tot de vorming van donkere lijnen 11 verschillende typenP. exigua var.foveata onderscheiden konden worden. Isolaten van deze typen vormden bij gepaarde groei op het selectieve medium donkere lijnen met andere typen, maar niet met isolaten van het zelfde type. Er bleek geen verband met het groeitype van de cultures noch met de vorming van het antibioticum E te bestaan.  相似文献