Molecular Cloning and Construction of agp Gene Deletion-mutant in Cyanobacterium Synechocystis sp. PCC 6803

The agp gene encoding the ADP-glucose pyrophosphorylase involved in cyanobacterial glycogen synthesis was amplified by PCR. The resulting agp fragment was cloned in plasmid pUC118 to generate plasmid pUCA. Part of the fragment within the agp DNA was deleted and replaced by an erythromycin resistance cassette to generate plasmid pUCAE, which was used to transform the Synechocystis sp. PCC 6803 wild-type strain and a mutant with resistance to erythromycin was obtained. PCR analysis of the genomic DNA from the resulting mutant indicated that the appropriate deletion and insertion indeed had occurred. The cell growth and Chl a, glycogen content in the mutant showed difference from those in the wild-type strain. The obtained biomass as well as the Chl a content in the mutant strain was higher than that of the wild-type strain, which suggested that the photosynthesis efficiency in the agp(-) strain was higher than that in the wild-type strain. No glycogen was found in the mutant, providing evidence for the correction of the mutant in physiological level.

Hypertrophic cardiornyopathy: from gene defect to clinical disease

Major advances have been made over the last decade in our understanding of the molecular basis ofseveral cardiac conditions. Hypertrophic cardiomyopathy (HCM) was the first cardiac disorder in whicha genetic basis was identified and as such, has acted as a paradigm for the study of an inherited cardiacdisorder. HCM can result in clinical symptoms ranging from no symptoms to severe heart failure andpremature sudden death. HCM is the commonest cause of sudden death in those aged less than 35 years,including competitive athletes. At least ten genes have now been identified, defects in which cause HCM.All of these genes encode proteins which comprise the basic contractile unit of the heart, i.e. the sarcomere.While much is now known about which genes cause disease and the various clinical presentations, very littleis known about how these gene defects cause disease, and what factors modify the expression of the mutantgenes. Studies in both cell culture and animal models of HCM are now beginning to shed light on thesignalling pathways involved in HCM, and the role of both environmental and genetic modifying factors.Understanding these mechanisms will ultimately improve our knowledge of the basic biology of heart musclefunction, and will therefore provide new avenues for treating cardiovascular disease in man.

Detection of Homozygous Deletions and Mutations in the CDKN2A Gene in Hydatidiform Moles

OBJECTIVE To investigate homozygous deletions and mutations in the CDKN2A gene(p16 INK4a and p14 ARF gene)in hydatidiform moles. METHODS A total of 38 hydatidiform mole samples and 30 villi samples were examined for homozygous deletions in the CDKN2A gene by PCR and for mutations by DHPLC. RESULTS i)Among 38 hydatidiform mole samples, homozygous deletions in the p16 INK4a exon 1 were identified in 5 cases(13.2%),while no homozygous deletions were found in the p16I NK4aexon 1 of 30 early-pregnancy samples.The rates of those deletions in hydatidiform compared to early-pregnancy villi samples was statistically significant(P=0.036).ii)No homozygous deletions in the p14 ARF exon 1 or p16 INK4a exon 2 were found in any of the hydatidiform moles or early-preganancy samples.iii) In all hydatidiform moles and early-pregnancy villi samples,no mutations were detected by DHPLC. CONCLUSION We suggest there may be a close correlation between homozygous deletions in the CDKN2A gene and occurrence of hydatidiform moles variation in the CDKN2A gene is mainly caused by homozygous deletions,while mutations may be not a major cause.

宫内感染致脑性瘫痪的机制研究进展

宫内感染是小儿脑性瘫痪最常见的病因之一，其对脑组织的损伤包括直接机制和间接机制。随着直接溶细胞感染、脑水肿和脑室扩大以及脑室管膜炎等直接机制的阐明，宫内感染所致脑性瘫痪的间接机制研究成为该领域的热点。除炎症介质和神经发育相关因子下凋学说外，胎盘分泌激素紊乱、Notch穿膜受体活性改变以及基因突变／缺失等也是导致脑损伤的重要因素，且各机制之间相互作用，形成网络化效应。

Two unrelated patients with rare Crigler-Najjar syndrome type I:two novel mutations and a patient with loss of heterozygosity of UGT1A1 gene

Cdgler-Najjar syndrome type Ⅰ （CN-I） is the most severe type of hereditary unconjugated hyperbilirubinemia. It is caused by homozygous or compound heterozygous mutations of the UDP-glycuronosyltransferase gene （UGT1A1） on chromosome 2q37. Two patients clinically diagnosed with CN-I were examined in this paper. We sequenced five exons and their flanking sequences, specifically the promoter region of UGT1A 1, of the two patients and their parents. Quantitative real-time polymerase chain reaction （qRT-PCR） was used to determine the UGT1A1 gene copy number of one patient. In patient A, two mutations, c.239_245delCTGTGCC （p.Pro80HisfsX6; had not been reported previously） and c.1156G〉T （p.Va1386Phe）, were identified. In patient B, we found that this patient had lost heterozygosity of the UGTIA1 gene by inheriting a deletion of one allele, and had a novel mutation c.1253delT （p.Met418ArgfsX5） in the other allele. In summary, we detected three UGTIA 1 mutations in two CN-I patients： c.239_ 245delCTGTGCC （p.Pro80HisfsX6）, c.1253delT （p.MeH18ArgfsX5）, and c.1156G〉T （p.Va1386Phe）. The former two mutations are pathogenic; however, the pathogenic mechanism of c.1156G〉T （p.Va1386Phe） is unknown.