摘要:

Growth hormone genotype was determined using polymerase chain reaction (PCR) amplification of the growth hormone gene. Amplified DNA was digested with MspI, the resulting fragments separated by agarose gel electrophoresis and visualized with UV light following ethidium bromide staining. Undesired preferential amplification of alleles initially led to genotype misclassification. Two of 32 animals were misclassified when PCR products were compared to genomic digests probed with radiolabeled, full‐length cDNA of the bovine growth hormone gene. Intensity of allelic bands was quantified by densitometry. One allelic form (A1) consistently exhibited greater band intensity. Relative intensity of the A1allele to the A2allele varied from 1.5:1 to 18:1, depending on size of PCR amplified DNA and length of the 72°C phase of PCR. Differential intensity increased with increasing size of PCR amplified DNA and length of the 72°C phase of PCR. Subsequent analyses indicated that the apparent differential amplification was not primer dependent. Optimization of PCR conditions for a specific gene may result in optimization for a specific allele. This phenomenon is undesirable in genotypic analyses.

ISSN:1049-5398    

DOI:10.1080/10495399109525744

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1049-5398    

DOI:10.1080/10495399109525743

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This study was conducted to determine if human growth hormone (hGH) could be produced in the milk of transgenic mice at high levels without adverse effects on growth and reproduction. Twenty‐four transgenic mice were generated carrying hGH coding sequences linked to a mouse whey acidic protein (WAP) promoter. Of 17 mice that gave rise to offspring hGH was detected in the milk of four with levels ranging from 65 ng/ml to 0.41 mg/ml. The high expressing line was propagated to generate homozygous offspring. These expressed hGH in milk at levels greater than 1 mg/ml. Although low levels of hGH were detected in serum during lactation in this line, growth and reproduction were normal. These results demonstrate the feasibility of producing commercially important levels of hGH in the milk of transgenic animals.

ISSN:1049-5398    

DOI:10.1080/10495399109525745

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A comparison between the nucleotide sequences of the A and B variants of cattle β‐lactoglobulin (BLG) indicates that the electrophoretic difference between the variants corresponds to anHphI restriction fragment length polymorphism (RFLP) in exon III. In contrast, aHaeIII RFLP recently reported by Lienet al. (1990) and Medrano and Aguilar‐Cordova (1990), occurring in exon IV, is silent with respect to the electrophoretic variation. However, since theHaeIII enzyme gives rise to larger diagnostic fragments, and is also currently 10‐fold cheaper than theHphI enzyme, it would be preferable to use theHaeIII site as a marker for the A and B variants. But this can be done only if there is strong linkage disequilibrium between the causative (HphI) and marker (HaeIII) sites, which are 1.178 kb apart. In this paper, we presentHphI andHaeIII RFLPs obtained by the use of cattle genomic probes specifically developed for each site, and show that complete linkage disequilibrium between the two polymorphic sites exists in samples from two populations of Australian cattle (55 Holstein‐Friesian and 11Bos taurusxBos indicuscrossbreds). If more extensive studies confirm complete linkage disequilibrium between the two sites, then the more convenient and cheaperHaeIII marker can be used for BLG genotyping of A.I. sires. As the B variant of BLG has been found to be associated with better cheesemaking properties, availability of the genotypes of A.I. sires may be useful to the dairy cattle breeding industry.

ISSN:1049-5398    

DOI:10.1080/10495399109525746

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Experiments were conducted to determine the efficiency of visualizing pronuclei in living zygotes. Oocytes aspirated from ovaries of slaughtered cows were matured for 24 hr, fertilized, and examined by differential interference contrast microscopy (DICM) to identify pronuclei, then fixed, stained and examined by phase contrast microscopy (PCM) for stage of development. In the first experiment, 1028 oocytes were examined at 3‐hr intervals between 10 and 22 hr after exposure to sperm. In the second experiment, 759 oocytes were classified by type of cumulus investment (complete, incomplete, and all others, such as loose, expanded, or no investment) and examined at 13 or 19 hours. The proportion of oocytes and embryos in which two pronuclei were seen by DICM increased from 5% at 10 hr to 38% at 19 and 22 hr, with greatest increase between 10 and 13 hours. In exp. 2, oocytes with incomplete investments had the highest proportion of zygotes with two pronuclei. Over both experiments, the proportion of embryos in which one pronucleus was seen by DICM ranged from 14 to 18%. Examination of stained oocytes and embryos indicated that, over both experiments, the fertilization rate was 68%, and the proportion of fertilized oocytes with 0, 1 or 2 pronuclei was 16%, 11% and 57%; 15% of fertilized oocytes were polyspermic. The proportion of embryos with two pronuclei increased over time. Examination of stained ova agreed with DICM of live ova in assessing the number of pronuclei in 67% of oocytes and embryos. Evaluation of ova by PCM, which was considered to provide the more accurate assessment of the state of embryonic development, agreed most frequently with DICM evaluation in embryos with two pronuclei (85%) and ova with no pronuclei (70%) and least frequently in ova with one pronucleus (30%). Of ova in which DICM and PCM disagreed, 55% of those in which no pronucleus was found by DICM showed two after being stained, and 73% of those in which one pronucleus was found by DICM showed two after being stained. Results suggest that all embryos in which at least one pronucleus is seen by DICM will often contain two pronuclei and should be treated accordingly.

ISSN:1049-5398    

DOI:10.1080/10495399109525747

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Multi‐locus probes are of great potential for identification purposes, gene mapping and breeding programs in farm animals. However, the number of loci detected by the available multi‐locus probes is insufficient for any major mapping or breeding projects in most of the large farm animals such as cattle, sheep and horses. We present here the development of a multi‐locus probe for large farm animals by screening a bovine genomic library with multi‐locus and bovine genomic probes. This screening procedure was applied for the isolation of highly repetitive, highly polymorphic, non‐satellite sequences. The resulted microsatellite probe (R18.1) consists of seven 35bp repeat units, with a mean divergence of 15% between repeats, separated by poly(CA) sequences. Probe R18.1 hybridizes efficiently to digested DNA from poultry and sheep yielding highly polymorphic DNA fingerprint patterns. The rational by which this probe was developed is presented and discussed.

ISSN:1049-5398    

DOI:10.1080/10495399109525748

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Restriction fragment length polymorphism (RFLP) analyses of swine leukocyte antigen (SLA) class I and class II genes from Swiss Large White and American Hampshire families were performed using porcine DNA probes. Class I and class II RFLPs associated with the serologically‐defined haplotypes SLA H1, H8, H16 and H24 and with serotypes SLA 15, 16; SLA 14; and SLA 6, SB 19, were identified. Seven allelic class I RFLP patterns were observed. For genes in the SLA class II region, six allelic RFLP patterns of DQA and DQB; five allelic RFLP patterns of DRA; and seven allelic RFLP patterns of DRB were observed. The serologically‐defined H8 haplotype was subtyped based on differences in class II RFLPs.

ISSN:1049-5398    

DOI:10.1080/10495399109525749

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1049-5398    

DOI:10.1080/10495399109525742

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor