Two different gene loci related to the spatial patterning of brain ventricle in vertebrate

摘要

Observations on living embryonic brains and the microstructure of brain ventricle of goldfish revealed that there are two brain ventricle phenotypes in gynogenetic haploid embryos. One phenotype is as normal as that of the control inbreeding diploid embryos, which has normal differentiated forebrain, midbrain and hindbrain. Another phenotype is obviously abnormal, the brain patterning is irregular, and no distinct brain ventricle can be observed. The ratio of haploid embryos with normal brain patternto that with abnormal brain pattern is 1 : 3. This ratio indicates that there are two gene loci involved in the spatial patterning of the brain ventricle. Since the possibility that deleterious recessive mutant alleles exist on both of the two gene locihad been excluded in this experiment, the phenotype represented the expressional state rather than the genotype of these two genes. Therefore, the ratio of 1 : 3 suggests that the expressing probability for each copy of the two genes is 50 %, and the regulatory mechanism of the expression is based on two sets of chromosomes, controlled by the rule of the diploid-dependent regulatory mechanism.