The genetic background and application of Down syndrome mouse models.

Down syndrome (DS), trisomy chromosome 21 (Hsa21), is the most common genetic disease caused by chromosome aberration in the human genome. Modeling DS in mice has been challenging since the orthologs of Hsa21 genes map to separate segments of three mouse chromosomes, Mmu16, Mmu17, and Mmu10. Although the early Ts65Dn mouse model exhibited various DS phenotypes, the duplicated fragments were randomly generated by ionizing radiation and did not include all Hsa21 orthologs. In 2004, the successful use of the Cre/LoxP recombination technique in chromosomal engineering in the construction of the Ts1Rhr mouse strain solved the problem of duplication of specific chromosome segment, resulting in the establishment of specific DS mouse models with accurate triplication of particular genes and associated phenotypes. In this review, we briefly introduce the different DS mouse models and discuss their advantages and limitations by focusing on the triplication of Hsa21 orthologs and manifestations of DS phenotypes, thereby providing some references for the selection of specific mouse models in DS research.

Exploring the Formation of a Disjunctive Pattern between Eastern Asia and North America Based on Fossil Evidence from Thuja (Cupressaceae).

Thuja, a genus of Cupressaceae comprising five extant species, presently occurs in both East Asia (3 species) and North America (2 species) and has a long fossil record from Paleocene to Pleistocene in the Northern Hemisphere. Two distinct hypotheses have been proposed to account for the origin and present distribution of this genus. Here we recognize and describe T. sutchuenensis Franch., a new fossil Thuja from the late Pliocene sediments of Zhangcun, Shanxi, North China, based on detailed comparisons with all living species and other fossil ones, integrate the global fossil records of this genus plotted in a set of paleomaps from different time intervals, which show that Thuja probably first appeared at high latitudes of North America in or before the Paleocene. This genus reached Greenland in the Paleocene, then arrived in eastern Asia in the Miocene via the land connection between East Asia and western North America. In the late Pliocene, it migrated into the interior of China. With the Quaternary cooling and drying, Thuja gradually retreated southwards to form today's disjunctive distribution between East Asia and North America.

Alteration of gene expression profiling including GPR174 and GNG2 is associated with vasovagal syncope.

Vasovagal syncope (VVS) causes accidental harm for susceptible patients. However, pathophysiology of this disorder remains largely unknown. In an effort to understanding of molecular mechanism for VVS, genome-wide gene expression profiling analyses were performed on VVS patients at syncope state. A total of 66 Type 1 VVS child patients and the same number healthy controls were enrolled in this study. Peripheral blood RNAs were isolated from all subjects, of which 10 RNA samples were randomly selected from each groups for gene expression profile analysis using Gene ST 1.0 arrays (Affymetrix). The results revealed that 103 genes were differently expressed between the patients and controls. Significantly, two G-proteins related genes, GPR174 and GNG2 that have not been related to VVS were among the differently expressed genes. The microarray results were confirmed by qRT-PCR in all the tested individuals. Ingenuity pathway analysis and gene ontology annotation study showed that the differently expressed genes are associated with stress response and apoptosis, suggesting that the alteration of some gene expression including G-proteins related genes is associated with VVS. This study provides new insight into the molecular mechanism of VVS and would be helpful to further identify new molecular biomarkers for the disease.

N-Acetyltransferase 2 genotype, exfoliated urothelial cells and benzidine exposure.

Most studies report an association of the slow N-acetyltransferase 2 (NAT2) status with elevated bladder cancer risk. In this study, NAT2 genotypes and the decades-long records of Papanicolaou's grading of exfoliated urothelial cells in a former benzidine-exposed cohort of the Shanghai dyestuff industry (29 bladder cancer patients; 307 non-cancer cohort members, some of them presenting different grades of pre-malignant alterations of exfoliated urothelial cells) were investigated. The cohort members had been enrolled in regular medical surveillance since mid-1980s. No overall increase of slow NAT2 genotypes in the former benzidine-exposed bladder cancer patients was found, compared with non-diseased members of the same cohort. A lower presentation of the homozygous wild genotype NAT2 4/4 was observed in bladder cancer patients, compared with non-diseased members with averaged Papanicolaou's grading (APG)3 II (OR=0.31, 95 percent CI 0.10-0.96, p=0.034) or with APG less than II (OR=0.36,95 percent CI 0.12-1.10, p=0.063). Nevertheless, neither a protective influence of rapid NAT2 genotypes on bladder cancer risk nor on pre-malignant cytological alterations could be confirmed by the present data.

[Progress of φC31 integrase system in site-specific integration].

Integrase of phage fC31 catalyses the homologous recombination between Streptomyces attachment site attB and the phage attachment site attP. Meanwhile, this integrase can mediate integration of attB-containing donor plasmids into the pseudo attP sites in eukaryotic genomes by a site-specific manner and resulting long-term and robust expression of integrated genes. Nowadays, fC31 integrase system is becoming a potential tool for genome modification, gene therapy and transgenic research. Recent progress of fC31 integrase system in integration mode in mammalian genomes, efficiency improvement and researches concerned on transgenic safety were summarized in this review.

iPS cells produce viable mice through tetraploid complementation.

Since the initial description of induced pluripotent stem (iPS) cells created by forced expression of four transcription factors in mouse fibroblasts, the technique has been used to generate embryonic stem (ES)-cell-like pluripotent cells from a variety of cell types in other species, including primates and rat. It has become a popular means to reprogram somatic genomes into an embryonic-like pluripotent state, and a preferred alternative to somatic-cell nuclear transfer and somatic-cell fusion with ES cells. However, iPS cell reprogramming remains slow and inefficient. Notably, no live animals have been produced by the most stringent tetraploid complementation assay, indicative of a failure to create fully pluripotent cells. Here we report the generation of several iPS cell lines that are capable of generating viable, fertile live-born progeny by tetraploid complementation. These iPS cells maintain a pluripotent potential that is very close to ES cells generated from in vivo or nuclear transfer embryos. We demonstrate the practicality of using iPS cells as useful tools for the characterization of cellular reprogramming and developmental potency, and confirm that iPS cells can attain true pluripotency that is similar to that of ES cells.

[Construction of the oocyte-specific expressing phiC31 integrase vector pZP3-INT and its expression in mouse oocytes].

Streptomyces phage phiC31 integrase is a site-specific recombinase, which can catalyze site-specific, unidirectional recombination between the attP site and attB site. To explore whether it can be used to mediate the recombination of specific gene in oocytes, GV-stage oocytes were collected from 3-week-old Kunming White mice by puncturing antral follocles with a sharp needle, and micro-injected with oocyte-specific expressing phiC31 integrase vector pZP3-INT and site -specific recombination detection vector pBCPB+. phiC31 integrase mRNA were detected by RT-PCR and the recombination of pBCPB+ was evaluated by PCR in mouse oocytes at 48 h after injection. Both can get corresponding bands. These results indicated that the expression of phiC31 integrase can be driven by ZP3 promoter efficiently and phiC31 integrase can mediate the site-specific recombination between attP site and attB site in mouse GV-stage oocytes. It could be a powerful tool for the study of recombination of specific gene in mouse oocytes and would provide an alternative way for the mouse oocyte genome manipulation.

Improved efficiency of bovine cloning by autologous somatic cell nuclear transfer.

Somatic cell nuclear transfer (SCNT) has been used for the cloning of various mammals. However, the rates of successful, healthy birth are generally poor. To improve cloning efficiency, we report the utilization of an 'autologous SCNT' cloning technique in which the somatic nucleus of a female bovine donor is transferred to its own enucleated oocyte recovered by ovum pick up, in contrast to the routine 'allogeneic SCNT' procedure using oocytes from unrelated females. Our results showed that embryos derived from autologous SCNThave significantly higher developmental competence than those derived from allogeneic SCNT, especiallyat the eight-cell (60 vs 44%), morula (45 vs 36%), and blastocyst (38 vs 23%) stages. The pregnancy and birth rates were also higher for the autologous (39 and 23%), compared to the allogeneic (22 and 6%) SCNT groups. Genome-wide histone3-lysine9 methylation profiles reveal that autologous SCNTembryos have less epigenetic defects than the allogeneic SCNTembryos. This study indicates that autologous SCNT can improve the efficiency of bovine cloning with less reprogramming deficiency.

Identification of pseudo attP sites for phage phiC31 integrase in bovine genome.

Streptomyces phage phiC31 integrase was found to mediate site-specific integration of foreign genes at pseudo attP sites of genomes in human, mouse, rat, and Drosophila. This paper reports that phiC31 integrase can also mediate homologous recombination between attB and pseudo attP sites in bovine cells and foreign gene integration was increased at least 2-fold in bovine fibroblasts or Madin-Darby bovine kidney (MDBK) cells. Two intrinsic pseudo attP sites named BpsF1 and BpsM1 located in the inter-gene regions on chromosome 28 and 19, respectively, were identified in bovine genome. These pseudo attP sites shared similar characteristics with those from other species as previously described. Our study demonstrated that the phiC31 integrase system provides a new potential for genetic engineering of the bovine genome and might be beneficial for the research on ruminant.

[Anti-tumor effect of ethanol extracts from Thymus quinquecostatus Celak on human leukemia cell line].

OBJECTIVE: To screen the anti-tumor fraction of ethanol extracts from Thymus quinquecostatus Celak and investigate its anti-tumor effect on human leukemia cell line. METHODS: Ethyl acetate, n-butanol and acetone fractions were separated from the ethanol extracts of wild Thymus quinquecostatus Celak. Growth inhibiting effects of these extracts on human leukemia cell lines K562 and HL-60 were determined by live cell counting and cell growth curve analysis. The possible anti-tumor mechanism was studied by morphological analysis with norcantharidin as a positive control. RESULTS: Ethyl acetate fraction could significantly inhibit the proliferations of K562 and HL-60 cells, and the inhibiting effect depended on the concentration of ethyl acetate fraction. Ethyl acetate fraction could induce apoptosis of K562 and HL-60 cells. The n-butanol and acetone fractions had no significant inhibiting effect on K562 and HL-60 cells. CONCLUSION: Ethyl acetate fraction is the major anti-tumor fraction in ethanol extracts from Thymus quinquecostatus Celak.

An association of UDP-glucuronosyltransferase 2B7 C802T (His268Tyr) polymorphism with bladder cancer in benzidine-exposed workers in China.

UDP-Glucuronyltransferase 2B7 (UGT2B7) is involved in benzidine metabolism, as demonstrated by in vitro experiments with liver slices. To evaluate the possible association of UGT2B7 gene polymorphism with bladder cancer risk for benzidine-exposed subjects, diagnosed bladder cancer cases (n = 36) who were members of a cohort of benzidine-exposed workers in the Chinese dyestuff industry were investigated. UGT2B7 polymorphism at locus C802T (His268Tyr) was detected using a PCR-RFLP based procedure. Nondiseased cohort members (156 men, 95 women) were taken as work-related control, and unexposed healthy individuals (113 men, 105 women) were taken as community control. The data showed that the polymorphism at locus UGT2B7 C802T in a general Chinese population significantly differs from that in a Caucasian population (p = 0.00018), displaying a distinctly lower frequency of T/T genotypes (9.2 vs. 25.3%), while no significant difference to a Japanese population could be detected (p = 0.17). A higher prevalence of T/T genotype carriers was found in the cancer cases, compared with unexposed healthy controls (25 vs. 9%, odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.37-7.98, p = 0.006). A higher presentation of T allele carriers in the patients group was also confirmed (46 vs. 33%, OR 1.73, 95% CI 1.05-2.87, p = 0.03). A higher portion of the T/T genotype was also observed in bladder cancer patients compared with nondiseased members of the same benzidine-exposed cohort, although some of them displayed different degrees of cellular alterations in their exfoliated urothelial cells. This study points for the first time to an association between a homozygous mutant genotype of human UDP-glucuronosyltransferase 2B7 catalyzing the biotransformation of benzidine and an elevated bladder cancer risk for formerly benzidine-exposed workers of the dyestuff industry.

Polymorphism of N-acetyltransferase 2 (NAT2) gene polymorphism in shanghai population: occupational and non-occupational bladder cancer patient groups.

OBJECTIVE: Arylamine N-acetyltransferases (NATs) are involved in the detoxification of aromatic amines and hydrazine. In order to explore the possible association of NAT2 polymorphism with bladder cancer risk in benzidine exposed or non-exposed Chinese individuals, healthy subjects, subjects with bladder cancer of a former benzidine exposed cohort in Shanghai dyestuff industry and a group of bladder cancer patients without known occupational exposure to aromatic amines were genotyped for NAT2 gene polymorphism. METHODS: NAT2 genotyping was performed with a set of RFLP procedures at seven major polymorphic loci of gene coding area: G191A, C282T, T341C, C481T, G590A, A803G and G857A. RESULTS: The wild allele NAT2 *4 was the most prevalent allele (59%) in healthy individuals. The alleles NAT2*6A and NAT2*7B were also frequently observed (21% and 17%, respectively). In contrast to Caucasians, the percentage of slow acetylators was lower (12% in Chinese vs. 58% in Caucasians, P < 0.001). No relevant differences were observed for homogenous rapid, heterogeneous rapid/slow and homogeneous slow acetylation genotypes between the healthy subjects and both groups of bladder cancer patients. CONCLUSION: The present work did not support the association of slow acetylating genotypes of NAT2 gene with elevated risk of bladder cancer in Chinese whereas it was documented as an important genetically determined risk factor in Caucasians. Different mechanisms might play a role in individual susceptibility to bladder cancer related with aromatic amine exposure in various races or ethnic groups.

N-Acetyltransferase 2 gene polymorphism in a group of senile dementia patients in Shanghai suburb.

AIM: To investigate the possible association of hereditary polymorphism of N-acetyltransferase 2 (NAT2) gene with the susceptibility towards senile dementia in farmer population of Shanghai suburb. METHODS: NAT2 gene genotyping was performed at 7 major polymorphic loci (G191A, C282T, T341C, C481T, G590A, A803G, and G857A) with a polymerase chain reaction-based restriction fragment length polymorphism based procedure in 2 groups of farmer subjects in Shanghai suburb. A group of 51 diagnosed dementia patients [comprising 29 sporadic Alzheimer disease (AD) patients and 22 sporadic vascular dementia (VD) patients] and a group of 112 healthy individuals were in the same area. RESULTS: The homogenous rapid genotypes (R/R, including*4/*4, *13 /*13, and *4/*13) was found over-present in both groups of patients, compared with healthy individuals, for all farmer dementia patients, 52.9 % vs 33.0 %, P=0.016, OR (95 % CI): 2.28(1.16-4.48); for AD group only, 51.7 % vs 33.0 %, P=0.063, OR (95 % CI): 2.18 (0.95-4.97); for VD group 54.5 % vs 33.0 %, P=0.055, OR (95 % CI): 2.43 (0.96-2.43). The significant frequency difference of genotype *4/*7B between farmer dementia patients and healthy individuals, and that of solo-alleles *13, and *7B were observed between the healthy individuals and both groups of dementia patients. CONCLUSION: Our data suggest the involvement of various NAT2 rapid-acetylating genotypes in the individual susceptibility to senile dementia. Variant genotypes of NAT2 might serve as a hereditary risk factor for AD and VD in Chinese population.

[Glutathione S-transferase T1, M1 gene polymorphism in leukemia patients in Shanghai area].

OBJECTIVE: To explore the possible association of polymorphisms of glutathione S-transferases T1, M1 genes and leukemia susceptibility. METHODS: AS-PCR procedure was applied to determine the GSTs genotypes in a group of leukemia patients (n=61) in Shanghai area. The genotype frequencies in the leukemia patients and normal controls (183 healthy residents in the same city) were compared. Stratification with leukemia types, age and gender was made for further comparison. RESULTS: The frequencies of GSTT1 0/0 genotype and GSTT1 0/0-GSTM1 0/0 combined genotype were higher in leukemia patients than in controls, and the differences were significant. When stratified with age and gender, this trend still existed in the male ALL patients and in younger ALL patients (age < or = 30). CONCLUSION: Individuals who bear GSTT1 0/0 genotype or GSTT1 0/0-GSTM1 0/0 combined genotypes are more susceptible to leukemia, especially for male and younger carriers.

Polymorphism of alpha-estrogen receptor and aryl hydrocarbon receptor genes in dementia patients in Shanghai suburb.

AIM: To explore the possible association of different polymorphic forms of human alpha-estrogen receptor (ER-alpha) and aryl hydrocarbon receptor gene (Ahr) with the risk to senile dementia in farmers in Shanghai suburb. METHODS: Senile dementia patients (n=52) were examined for ER-alpha and Ahr gene polymorphism genotyping. Healthy individuals (n=125) in the same area were selected as a community control group. Two polymorphic loci, Pvu II locus and Xba I locus, of human ER- a gene were investigated by a PCR-RFLP-based procedure. The population frequencies of two polymorphic loci in exon 10 of Ahr gene, G1721A (R554K) and G1768A (V570I) were compared between patients and healthy controls using an allele-specific PCR (AS-PCR) procedure. RESULTS: The mutant allele frequencies of ER-alpha gene in the AD group were significantly higher than those in the control group (P=0.023, OR=2.94, 95 % CI 1.13-7.71 for Pvu II locus; P=0.046, OR=2.28, 95 % CI 1.003-5.17 for Xba I locus). The mutant allele frequencies among female AD patients were higher than those in the female controls (P=0.016, OR=3.68, 95 % CI 1.22-11.08 for Pvu II locus, P=0.029, OR=2.95, 95 % CI 1.10-7.94 for Xba I locus). The mutant form, neither in the homozygous, nor in the heterozygous form was detected at the locus of Ahr G1768A in a normal local population. No significant difference of Ahr genotype frequency at locus G1721A was noticed between the patients and healthy individuals. CONCLUSION: The distribution of ER polymorphisms was significantly different between Chinese and some other ethnic populations. The results suggested that ER-alpha gene polymorphisms might be related to the individual susceptibility to AD, especially in the females. However, it did not support the association of Ahr gene polymorphism with higher risk of senile dementia.

[Original studies on anti-tumor and immunological effect of extracts from Thymus quinquecostatus Celak in mice].

OBJECTIVE: To study the anti-tumor and immunological effect of extracts from Thymus quinquecostatus Celak on mice transplanted S180 tumor cells. METHODS: Different doses of volatile oil and alcohol extracted substances from Thymus quinquecostatus Celak were given to mice bearing S180 tumor for 9 days. Tumor inhibition rates and coefficients of spleen and thymus were determined. RESULTS: Tumor inhibition rates of the groups with alcohol extracts (40 g crude drug.kg(-1).d(-1) and 20 g crude drug.kg(-1).d(-1)) were 51.5% (P<0.01) and 36.4% (P<0.05) respectively, and those of the groups with volatile oil (40 g crude drug.kg(-1).d(-1) and 20 g crude drug.kg(-1).d(-1))were both 39.4% (P<0.05). CONCLUSION: The extracts from Thymus quinquecostatus Celak have anti-tumor activities. The coefficient of spleen in group with alcohol extracts (40 g crude drug.kg(-1).d(-1))was close to normal value, and its coefficient of thymus was between that of the negative control group and the group with cyclophosphamide (0.02 g.kg(-1).d(-1)). The anti-tumor activity of the alcohol extracts was significantly higher than that of the control group and the tumor inhibition rate was depending on drug concentration. Depending on index of immunity,the extracts from Thymus quinquecostatus Celak may have some influences on immunity.

Polymorphism of glutathione S-transferase T1, M1 and P1 genes in a Shanghai population: patients with occupational or non-occupational bladder cancer.

OBJECTIVE: Glutathione S-transferases are involved in the conjugation of xenobiotics. To explore whether GSTs polymorphisms are involved in the development of occupational or non-occupational bladder cancer, polymorphism frequencies of GSTT1, M1 and P1 were investigated in a normal population, which had been settled in a rural area in Shanghai suburb for at least 5 generations as well as in a group of patients with benzidine exposure related occupational bladder cancer in Shanghai dyestuff industry and a group of patients with non-occupational bladder cancer. METHODS: PCR based procedures were performed in the study populations to confirm the genotypes of GSTT1, M1 and P1. RESULTS: The polymorphisms at locus of GSTP1-A1578G in the normal population differed significantly from those in Caucasians or African Americans. All the subjects genotyped so far (n = 118) bore only homogenous wild genotype (C2293/C2293) at GSTP1-C2293T locus. This locus seemed to be a monomorphic in Shanghai population. No significant difference in GSTT1 and GSTM1 polymorphic form frequencies could be confirmed among three groups of subjects. An overrepresentation of GSTP1 AG or GG genotype corresponding a less stable and less effective isozyme protein was detected in patients with benzidine related occupational bladder cancer, compared with that in the normal population though a statistical significance was not yet reached (P = 0.09, OR = 1.96, 95% CI 0.89-4.32). CONCLUSION: This study suggests that GSTM1 or GSTT1 homozygous deficiency genotypes and their combination do not have a clear impact on bladder cancer incidence in a Shanghai population. It seems that GSTP1 polymorphism is not associated with non-occupational bladder cancer. GSTP1 AG or GG genotype has a higher frequency in the patients with benzidine related occupational bladder cancer, and further work is needed to confirm if GSTP1 AG or GG genotype plays a role in the development of occupational bladder cancer.

Nonassociation of aryl hydrocarbon receptor genotypes with susceptibility to bladder cancer in Shanghai population.

AIM: To assess two polymorphic forms of aryl hydrocarbon receptor (AHR) gene, G1721A (R554K), and G1768A (V570I) in Chinese population and to explore the possible association of human AHR gene polymorphism with elevated incidence of bladder cancer among Chinese Han subjects in east of China. METHODS: An allele specific PCR-based procedure for AHR gene polymorphism genotyping was developed by this work. Genotyping on three groups of subjects in Shanghai area had been performed: a bladder cancer group with the occupational exposure to benzidine, a non-occupational bladder cancer patient group whose members lack an obvious aromatic amine exposure record, and a normal population in the same city as controls. RESULTS: A significant difference (P < 0.01) in frequency distribution at locus G1721A between normal population in Shanghai and a Caucasian population reported by other authors was observed. No mutant allele(A1768) at locus G1768A had ever been detected in our study. The observed frequencies were similar between both genders in the normal population (P = 0.54), and there were no significant difference confirmed between the case group and the control group. CONCLUSION: The locus G1768 of human AHR gene seems to be monomorphic among Chinese in this area. The significant distribution difference at locus G1721A of human AHR gene between Chinese Han and Caucasian was confirmed. This study did not support the association of AHR G1721A polymorphism with higher risk to bladder cancer among the residents in this area, either in a group of occupationally benzidine-exposed individuals or among the persons who never have an obvious aromatic amine exposure record.