| Cell polarity is a crucial factor for a variety of cellular and developmental processes. par family contains six par genes, from par-1 to par-6. In Caenorhabditis elegans, mutations in six par genes, par-1 through par-6, cause the earliest and most extensive polarity defects in the zygote, eliminate many early asymmetries. Except par-2, the other PARs have orthologs in mammals and Drosophila. PAR proteins play important roles in cell junction, metabolism and cancer. Furthermore, the cell polarity regulator cdc-42 also plays an important role in this process. But the interaction of these genes is not clear. Thus, using RNA interference and in situ hybridization, we have done some work on the interaction of these genes in C. elegans.RNAi was performed using the bacteria feeding method to produce RNA interference. Double-Stranded RNA expressed by either hair-pin structures in pBluescript II SK(+) vector or L4440 with two T7 promoters, both methods proved via experiments have produced effective and specific RNA interference. To explore the interaction of par gene, we examined their expression of mRNA in C. elegans wild type and par mutants by in situ hybridization. The results show that par-1, par-2, par-3, par-5 and par-6 mRNA are all distributed extensively in oocyte, early embryos and the gonad of hermaphrodits. par-2 and par-4 are essential for other par mRNA expression. par-1, par-3 and par-6 mRNA decreased in par-2 mutant, the expression of par-1 and par-5 mRNA decreased in par-4 mutant. But there is no obvious direct interaction betweem par-2 and par-4. In addition, the absence of par-5 gene results in the increase of par-1 and par-3 mRNA expression. And the absence of par-3 gene also results in the increase of par-2 and par-5 mRNA expression. In par-6 mutant, from about 256 cells of embryo, par mRNA distribution are different, mRNA distributed in the posterior part of the embryo but not even in the embryo. We have conclude that par-4 promotes the expression of par-1, par-3 and par-5; par-1 and par-3 repress par-5, and par-1 represses par-2, but par-2 is required in par-1 expression. par-6 represses the expression of par-3 and par-5 mRNA, while par-2 has obvious stimulation to par-6.To test the distribution of PAR-2, PAR-5 and PAR-6 GFP in C. elegans wild type and par mutant via RNAi, we found that the posterier cortical PAR-2::GFP extend toward the anterior, while the cotical PAR-6::GFP disappeared in par-1 mutant via par-1 RNAi. In par-2 or par-5 mutant via RNAi, the anterior cortical PAR-6::GFP extend to the entire cell cortical. PAR-2::GFP can accumulate in the cortex, but can't get enriched in the posterior in the absence of par-5 or par-6.The distribution of cdc-42 mRNA in C. elegans wild type and par mutants via in situ hybridization shows similar results to par genes'in situ hybridization. cdc-42 mRNA is also distributed extensively in oocyte, early embryos and gonad of hermaphroditism. par activity is required for the expression of cdc-42 mRNA, especially par-4. In par-4 mutant, cdc-42 mRNA distributed in the periphery of zygote while which uniformly distributed in wild type. The expression of cdc-42 mRNA decreased in par-1 or par-5 mutant, but increased in par-2 mutant. Key Words: Caenorhabditis elegans; cell polarity; par; cdc-42...
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