| Hairless mouse is new strain that is different from nude mice at the structures of their skin and hair mutant genetically. There are some strains of hairless mice abroad, but in China reports about hairless mice are very few. In 1990, the lab animal center of Medical school of Zhengzhou University obtained 4 mutants of smooth-skinned hairless mice from Kunming experiment mice' reproducing group. After 10 years study the inbred line of this mutant of mice was founded. It has been named Yuyi hairless mice (for short: YYHL). This kind of mice' hair initially show growing normally. After 2-3 weeks of birth their hairs begin to shed. Most of their hairs shed after 2 weeks except of their beard and they keep the hairless state all their lives. In the development of YYHL, with the shedding of their hair, their skins on the head and on both side appear wrinkled. They become senile when they are in their prime of life (7-8 months). The flabby skins on the eyelid even envelope their eyes, so they have difficulty in going and eating. Their span of life is about 1 0 months, only half of wild Kunmingmice. According to the analysis of genetic spectrum it has been confirmed that the character of hairless is caused by a mutation in an autosomal recessive gene. In order to study the changes of corresponding appearance, we start with the hairless gene to investigate the hairless mice. Primer was designed by Using the full length of Hr gene found at GenBank; the place of Hr gene in YYHL mice was detected by the method: ISPCR; the homologous between YYHL and other premature senile mice, such as: rhino mice, hairless mice and so on was compared. Results1. The mutant gene detected on paraffin slides: a pair of primers: primers PI and P2 was designed by using hr gene in gene bank. Primers PI and P2 was marked by biotin. Tissues (thymus and spleen) were obtained from 40 days, 1 month, 2 months and 3 months old YYHL mice. Slides with tissues were trypsinized and fixed for 20 minutes at ambient temperature in a freshly prepared solution of 4%(w/v) paraformaldehyde in PBS. Control was treated by the same procedure. PCR reaction solution was pipetted onto the slides to fully hydrate the tissue sections. The tissues were then covered with siliconized glass cover-slides, excess solution was blotted to prevent the cover-slides from sliding off the tissue. Mineral oil was added to each slide and the slides were placed on the heating block of a thermal cycler. The slides were subjected to 25 cycles of amplification (94 ℃ for 5 minutes, 50℃ for 10 minutes and 72 ℃ for 10 minutes). Control: the paraffin slides ofnormal Kunming mice; paraffin slides of YYHL mice amplified without primer and without Taq DNA polymerase. The marker was detected by immunohistochemistry and observed by microscope. Pictures of the marker were taken.2. Preparation of chromosome: YYHL mice and normal Kunming mice were narcosised by Sodium pentobarbital. Ethanol-sterilizing mice were put onto sterile hood. About 1 ml blood could be drew from mouse heart. The lymphocytes were separated routinely by Ficoll solution, then washed in PBS one or twice. The lymphocytes were cultured in RPM 1640 culture solution with 10% FBS and lOul/lOml Con A for 72 hours. Lymphocytes then were pelleted, treated by 0.05M KC1 for 50 minutes, fixed by methanol/Glacial acetyl acid. 2-3 drops of the lymphocytes were putted onto the slides (slides were treated by poly-L-lysine). Infant YYHL mouse was injected colchicin 0.3ml(lmg/ml) from abdominal cavity. After 4 hours, the injected mouse was killed by cervical vertebra dislocation. Thighbone was separated from the mouse and cavity of the bone was washed in PBS. Marrow cells was pelleted and treated by 0.05MKC1 for 80 minutes, fixed by methanol/glacial acetyl acid. Two or three drops of the marrow cells were put onto the slides (slides were treated by poly-L-lysine).3. G strips of chromosome. Slides with lymphocytes and marrow cells in step 2 were putted in room temperature for 1 week. G banding was displayed by the metho...
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