Embryonic hemoglobins of different animal species

Summary The existence of embryonic hemoglobins is demonstrated in sheep-, calf and pig embryos. The occurrence and disappearance of these hemoglobins is quantitatively determined by cellulose acetate gel electrophoresis; hemoglobins as well as the globin chains, dissociated in 8 molar urea were quantitated. Sedimentation and diffusion experiments in the analytical ultracentrifuge revealed a S₂₀ of 4.3 and a D₂₀ of 6.6 for the examined hemoglobins. Therefore it is concluded that all hemoglobins occurring at different stages of embryonic and fetal development consist of 4 polypeptide chains with a total molecular weight of 66,000. The subsequent formation of the different polypeptide chains during ontogenesis is shown: At first only -chains are formed as demonstrated by the existence of Hb Gower I, consisting of four identical -chains. Subsequently the -chain appears, which leads to Hb Gower 2 (₂₂). The third polypeptide chain formed during the ontogenesis the -chain results finally in the appearance of HbF.In addition the existence of a HbF pig is demonstrated by the fingerprint technique.     

Immunogenicity of Trypanosoma cruzi in different animal species

The immunogenicity of two fractions (1 500 F and 10 000 F) from epimastigotes of Trypanosoma cruzi as well as the supernatant from culture media (SF) were studied using hens, rabbits and opossums. For comparative purposes, sera from individuals with chronic Chagas' disease were also used. A similar, positive response was obtained for the fractions in all the animal species studied using indirect hemagglutination test. Supernatants from culture media were the least immunogenic. By double immunodiffusion test, it was possible to detect a positive response to a different number as well as to different antigens in the three animal species, but there was response to a common antigen by all the different animal species. The common antigen called here major, was present in all the fractions assayed. Human sera from individuals chronically infected showed a variable response. When assayed by double immunodiffusion technique, the major antigen could be detected in just a few samples.     

Interval estimation of the attributable risk for multiple exposure levels in case-control studies

In case-control studies, exposure to a risk factor often occurs at several levels, so the attributable risk at each level is of interest. In this paper, estimation for the 2 X 2 table (case-control status versus dichotomous exposure) and the 2 X k table (case-control status versus exposure at several levels) are reviewed along with an example. A method for finding confidence intervals for attributable risk in the 2 X k table is proposed, and its application to estimates adjusted across strata (the 2 X k X s case) is indicated. The results of a Monte Carlo study of the procedure demonstrate that the nominal and actual coverage probabilities agree satisfactorily for practical applications.     

不同层次需求的实验动物学教学特点

实验动物学教学已成为医学教育中不可或缺的组成部分。本文从课程设置背景、课程安排、考核方法等方面总结了不同层次的实验动物学教学特点,以供广大实验动物教学工作者参考。     

A simplified system for biotyping Staphylococcus aureus strains isolated from different animal species

D evriese , L.A. 1984. A simplified system for biotyping Staphylococcus aureus strains isolated from different animal species. Journal of Applied Bacteriology 56 , 215–220.
A biotyping system for Staphylococcus aureus strains is proposed which is a simplified version of biotyping procedures described in the literature. It differentiates Staph. aureus strains from man and animals into host-specific ecovars and biotypes which are not host-specific. With the help of tests for βhaemolysin, staphylokinase, coagulation of bovine plasma and the crystal-violet reaction, the origin of many but not all Staph. aureus strains can be determined: 604 of 809 strains from man. poultry, cattle, pigs, goats, rabbits and foods could be alloted to four ecovars which are typically associated with man, poultry, sheep and goats and cattle. The other strains belonged to five non-host specific biotypes.     

Establishment of tight junctions between cells from different animal species and different sealing capacities

Summary Epithelial cells establish tight junctions (TJs) that offer an ample range of transepithelial electrical resistances (TER), in adjustment to physiological requirements. In the present work, we demonstrate that cells from different animal origins, co-cultured in monolayers, can make sealed TJs, suggesting that this structure has a basic universal structure. TJs cannot be established, however, if one of the partners does not normally express TJs, indicating that each neighbor has to contribute its moiety. Furthermore, we observe that clones of the same cell line, with widely different values of TER, do not differ, in the number and length of their junctional trands, suggesting that the difference is due to their ability to express ionic channels traversing their strands. The value of TER achieved in mixed monolayers of cells of the same or different lines is the one that may be expected by taking into account the proportion of each type in the mixture and adding in parallel the electrical resistance that they exhibit in pure monolayers. Therefore, epithelial TJs appear to behave as parallel resistances.     

Genetic trends estimation for body weights of Kermani sheep at different ages using multivariate animal models

The objective of the present study was to estimate genetic trends for body weight traits at different ages in Kermani lambs. Data collected from 1993 to 2006 by the Kermani Breeding Station were analyzed. Genetic trends were estimated for birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and yearling weight (YW). Maximum number of data was 2654 at birth, but only 1124 at yearling. Different appropriate models for investigation of each trait using multivariate analysis were applied. Variance component were estimated using Simplex procedure and breeding values of animals were predicted with Best Linear Unbiased Prediction (BLUP) methodology under multi-trait animal models. Genetic trends of studied traits were estimated by regressing mean of breeding values on birth year. Direct genetic trends were positive and significant for BW (p < 0.05) WW, 6MW, 9MW and YW (p < 0.01) and were 2, 125, 91, 81 and 156 g/year, respectively. Also, maternal trend for BW was positive and highly significant (p < 0.01) and was 3 g/year.     

Comparison of bacteroides-prevotella 16S rRNA genetic markers for fecal samples from different animal species

To effectively manage surface and ground waters it is necessary to improve our ability to detect and identify sources of fecal contamination. We evaluated the use of the anaerobic bacterial group Bacteroides-Prevotella as a potential fecal indicator. Terminal restriction length polymorphism (T-RFLP) of the 16S rRNA genes from this group was used to determine differences in populations and to identify any unique populations in chickens, cows, deer, dogs, geese, horses, humans, pigs, and seagulls. The group appears to be a good potential fecal indicator in all groups tested except for avians. Cluster analysis of Bacteroides-Prevotella community T-RFLP profiles indicates that Bacteroides-Prevotella populations from samples of the same host species are much more similar to each other than to samples from different source species. We were unable to identify unique peaks that were exclusive to any source species; however, for most host species, at least one T-RFLP peak was identified to be more commonly found in that species, and a combination of peaks could be used to identify the source. T-RFLP profiles obtained from water spiked with known-source feces contained the expected diagnostic peaks from the source. These results indicate that the approach of identifying Bacteroides-Prevotella molecular markers associated with host species might be useful in identifying sources of fecal contamination in the environment.     

Characteristics of Enterococcus cecorum strains from the intestines of different animal species

Enterococcus cecorum , originally described as Streptococcus cecorum , from poultry intestines, was isolated from intestinal contents of pigs, cattle, horses, canaries and a mallard duck. Strains from different animal hosts showed differences in biochemical characteristics and can be regarded as belonging to different ecovars of the species. Tests were presented which are useful in the identification of this unusual Enterococcus sp. which lacks the group D antigen and may fail to grow aerobically in the presence of 6·5% NaCl. Enterococcus cecorum appears to be the only cultivable component of the gastrointestinal flora of canaries and was present exclusively in the crop.