Investigation On The Gene Expression Pattern Of Abnormal Limb Of Mouse Embryo Following Exposure To MNNG

It is estimated that about 3% infants have birth defects.Our knowledge about the cause and mechanisms through which these defects are manifested is limited.Current estimated about 20% of all birth defects are due to genetic factors and 10% are due to environmental factors,the others are obscure and can be contributed to the interaction of genetic and environmental factors. With rapid increase in the number and category of chemicals, their potential teratogenecity can not be ignored.Understanding the molecular control of abnormal development can provid enormous groundwork for detection and extrapolation among species by identifying genes involved in the congenital malformation. With the establishment of a series of molecular strategy ,a detailed understanding of the genome-wide gene expression of abnormal development is becoming a reality. The vertebrate limb is a powerful model system for the cellular and molecular interaction that determine morphological pattern during embryonic development.MNNG is a known teratogen that can induce limb malformation.In this study,we used MNNG as test material to induce ICR mice embryo limb malformation.The result of experiment show that a spectrum of malformation involving the palate,ribs and limbs.Limb defects are prominent with exposure on day 12.When the type of limb malformation are examined,an unusual pattern was observed.Limbs on the left side were more frequently malformed than forelimbs.To analyse the gene expression profiles in abnormal and normal developmental limbs of mice GD14 and GD16 embryo.We employed cDNA microarry method.The PCR products of 8192 genes were spotted onto a kind of chemical-material-coated-glass slide in array.Both the mRNAs from abnormal and normal tissues were reversely transcribed to cDNAs.With the incorporation of fluorescent-labeled dUTP to prepare the hybridization probes.After hybridization, microarray were scanned for the fluorescent intensity.Teratogenicity-related geneexpression was screened through the analysis of difference in gene expression profile.Among 8192 target genes,there were 287 genes whose expression level differed between normal and abnormal tissure of GD14 embryo and 88 genes of GD16 embryo, mainly involved in cell cycle,transcription and metabolism. A few genes of spermatogenesis associated and testis-specfic were expressed in limb development and associated with limb abnormal development. Further analysis of these differentially expressed genes will be helpful for undersdanding the molecular mechanism of teratogenicity.