The Model Karyotype And FISH Studies Of Bmrbp1 On The Chromosomes Of Silkworm

Chromosomes are the carriers of genetic substances. Their structure, conformation, function are the cores of cytogenetics. Karyotype analysis has been one important tool in studying heredity, diversity, variation and evolvement. With the development of modern biology techniques, molecular biology techniques are now being increasingly applied in studies on chromosome. Fluorescence in situ hybridization (FISH) has become a bridge between cytogenetics and molecular genetics, which enable us to do researches more detailedly at molecular level.Based on previous studies, this dissertation is to enrich cytogenetics of silkworm through establishing model karyotype, on the other hand is to carry out FISH to determine the location of one sex-determining gene Bmrbp1 on silkworm chromosomes. The results are summed up as follows:1.The establishment of model karyotype of silkwormPachytene chromosomes from silkworm variety Dazao oocytes were investigated. 14 meiotic chromosomes with clear configuration and intact amount were selected. Karyotype analysis softwares Lucia and Image J were used to measure the length and carry out karyotype analysis. Results showed that there was a relative big distinction of total absolute length among different cells, the average value of chromosome total length of 14 cells was 360.015 μm and the longest was 433.469μm, the shortest was 273.183μm, which showed a margin of 160.μm. In the same cell, the absolute length of each chromosome was also different, the ratio between the longest and the shortest was 2.984, the average ratio was 2.603; the absolute length with same sequence number in different cells also showed a obvious distinction. For example, in 14 cells, as far as the eighth chromosome was concerned ,the shortest was11.088μm, while the longest was18.345μm,showing a margin of 7.257μm.Consequently, absolute length was unfit to be a parameter in silkworm karyotype analysis.The relative length with same sequence number in 14 cells was relatively close, the highest SD value was 0.435 , while the lowest was only 0.136.Compared with absolute length, relative length has smaller difference, which showed the average relative length of pachytene chromosomes...