Aims: The aims of this paper were to examine the association between gene polymorphisms of methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G with levels of plasma folate and tHcy. Methods:Peripheral venous blood samples were obtained from 143 pregnant women, who had been fasted for more than 10 hours. Plasma tHcy and folate concentrations were measured in plasma specimens. The genotypes for polymorphisms were identified by the PCR-restriction fragment length polymorphism (RFLP). Results:Our results demonstrated that MTHFR 677T allele was the predictors of plasma folate levels in pregnant women. While MTHFR 677TT genotype and MTRR 66G allele were the predictors of plasma tHcy concentrations. Plasma folate levels were negatively correlated with tHcy concentrations (Pearson's correlation coefficient r=-0.358, p=0.000012). With the increase of gestational weeks, the levels of plasma folate was first risen and then fall, whereas, there was a downtrend between gestational weeks and tHcy levels. Conclusion:Plasma folate status and total homocysteine level associated with MTHFR C677T and MTRR A66G gene polymorphisms in pregnant women. According to our study, the pregnant women of homozygous mutation of MTHFR 677TT and/or MTRR 66GG genes generally have lower levels of folate. Therefore, we recommend that pregnant women with 677TT and 66GG genotypes should supplement the appropriate dosage of folic acid based on their genotypes.

Steroidogenic factor 1 (sf1) is an important regulator of gonad development and function in mammals. However, study of sf1 in fish is limited to cloning and expression and in vitro experiments. Using antisense RNA we knockout transcription of the sf1 gene in Nile tilapia Oreochromis niloticus, and obtain experimental fish in vivo. We demonstrate that antisense RNA can silence sf1 transcription and protein expression, and report suppression of sf1 transcription to affect gonad development and external genitalia formation in Nile tilapia. We also report disfunction of retinal metabolism and fatty acid metabolism to be important causes of weight gain and gonad abnormality with sf1 suppression. The feasibility of using antisense RNA for gene editing in fish is verified, and a new way of studying gene function and performing biological breeding is presented.