Comparative study on the karyotype of chromosome of Barbus capito with two methods

Chromosome karyotyping is the main content in cytogenetic study. Manual analysis, image systemic analysis and software analysis are the most commonly used methods in chromosome karyotyping. But all three methods have their own disadvantage, which are large measurement error, high quality metaphase image requirement and uncontrollable detail error, respectively. In order to obtain accurate and convenient chromosome karyotype analysis method, the introduced salt-tolerant varieties, Barbus capito, was used as experimental fish. The metaphase chromosomes of B. capito were obtained from head kidney tissue by the method of PHA and colchicine injection and then the chromosome samples were prepared by air-drying technique. We presented a method for chromosome karyotyping by combining two software E-ruler and Photoshop, and compared the measure and karyotyping results from the regular method. The results showed that there is no significant difference in the measurement of stretched straight chromosomes by E-ruler software and conventional methods, however, the former is more accurate in the measurement of curved chromosome. Photoshop software can quickly and conveniently complete the chromosome, because it can accurately judge the location of centromere by eliminating the background of karyotype. It can be concluded that E-ruler and Photoshop combining method achieved much more accurate and clear karyotyping results. As an accurate and convenient method, this new method can also be used in chromosome analysis of other fish species and even other organisms. The results showed that the chromosome ploidy of B. capito was diploid, and no gender-related heterotypical chromosomes were found. The karyotype formula was: 2n=100=12m+38sm+38st+12t, NF=150. Compared with other species from Barbinae family, B. capito has similar karyotypes to several domestic species, which shows the karyotype evolutionary characters.