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Q Dai

Publications and source records attributed to Q Dai.

At least 19 recordsLinked to original sources
PubMed2006

Ultrasonographic image attributes of non-ovulatory follicles and follicles with different luteal outcomes in gonadotropin-releasing hormone (GnRH)-treated anestrous ewes.

Ultrasonographic images are composed of multiple square picture elements called pixels. Quantitative changes in numerical pixel values (echotexture) determined by computer-assisted analysis of digital images reflect discrete changes in the microscopic structure and physiological status of ovarian antral follicles. The objective of the present study was to determine and compare the ultrasonographic attributes of non-ovulatory antral follicles that grew to an ostensibly ovulatory diameter (> or =5mm) and follicles with different luteal outcomes in response to gonadotropin-releasing hormone (GnRH) in anestrous Western White Face ewes (n=34). All animals received GnRH injections (250ng i.v. every 2h for 24h) followed by a bolus injection of 125microg of GnRH i.v. Ovarian images obtained by repeated transrectal ultrasonography were digitized and subjected to computerized analyses to determine the changes in follicular size and echotexture of the follicular antrum and wall. At the beginning of GnRH treatment, follicles that formed inadequate corpora lutea following ovulation (ICL; n=22) had higher (P<0.001) pixel intensity of the central and peripheral antrum compared with non-ovulatory follicles (n=40). Pixel intensity of the central follicular antrum was greater (P<0.01) in follicles that formed ICL compared with follicles that formed normal (full-lifespan) CL post-treatment (NCL; n=20) and mean pixel heterogeneity of the follicular wall was greater (P<0.05) in non-ovulatory follicles compared with follicles that gave rise to NCL. At the time of GnRH bolus injection (i.e., induction of a synchronous LH surge), the mean diameter of non-ovulatory follicles was greater (P<0.01) than that of all ovulating follicles, and pixel heterogeneity of the central follicular antrum was lowest (P<0.05) in non-ovulatory follicles. The mean diameter of luteinized unovulated follicles (n=9) tended to be greater (P<0.10) at 2.5 and 3 days after emergence, and pixel intensity of the follicular wall was lower (P<0.05) compared with non-luteinized follicles (n=8) at 1.5 and 2.5 days after emergence (beginning of the growth from approximately 3mm onwards). In conclusion, ovarian antral follicles with different outcomes after GnRH treatment (in seasonally anestrous ewes) had distinctive ultrasonographic characteristics.

Anestrus↗
PubMed2006

Animal food intake and cooking methods in relation to endometrial cancer risk in Shanghai.

We evaluated animal food intake and cooking methods in relation to endometrial cancer risk in a population-based case-control study in Shanghai, China. A validated food frequency questionnaire was used to collect the usual dietary habits of 1204 cases and 1212 controls aged 30-69 years between 1997 and 2003. Statistical analyses were based on an unconditional logistic regression model adjusting for potential confounders. High intake of meat and fish was associated with an increased risk of endometrial cancer, with adjusted odds ratios for the highest vs the lowest quartile groups being 1.7 (95% confidence interval: 1.3-2.2) and 2.4 (1.8-3.1), respectively. The elevated risk was observed for all types of meat and fish intake. Intake of eggs and milk was not related to risk. Cooking methods and doneness levels for meat and fish were not associated with risk, nor did they modify the association with meat and fish consumption. Our study suggests that animal food consumption may play an important role in the aetiology of endometrial cancer, but cooking methods have minimal influence on risk among Chinese women.

Adult↗
PubMed2002

Weight at birth and adolescence and premenopausal breast cancer risk in a low-risk population.

We assessed breast cancer risk in relation to weight at birth and adolescence. In-person interviews were completed with the biological mothers of women aged 45 years and younger who participated in the Shanghai Breast Cancer Study in 1996-98 (288 cases, 350 controls). After adjustment for confounding, women who were 4000 g or more at birth were not at increased risk of breast cancer (odds ratio=0.7; 95% confidence interval 0.4-1.4) relative to women whose birth weight was 2500-2999 g. Compared with women of average perceived weight at age 15 years, no relation was apparent for heavier than average weight based on maternal report (odds ratio=0.7; 95% confidence interval 0.5-1.2) or self-report (odds ratio=1.0; 95% confidence interval 0.7-1.6). Perceived adolescent weight and height did not modify the association of birth weight with breast cancer risk. These results suggest that weight early in life is not related to premenopausal breast cancer risk in this low-risk population.

Adolescent↗
PubMed2002

Cigarette and alcohol consumption and the risk of colorectal cancer in Shanghai, China.

The relation of cigarette smoking and alcohol drinking to colorectal cancer risk has been inconsistent in the epidemiological literature. In a population-based case-control study of colorectal cancer in Shanghai, China, where the incidence rates are rising sharply, we examined the association with tobacco and alcohol use. Cases were aged 30-74 years and newly diagnosed with cancers of the colon (N = 931) or rectum (N = 874) between 1990 and 1992. Controls (N = 1552) were randomly selected among Shanghai residents, frequency-matched to cases by gender and age. Information on lifetime consumption of tobacco and alcohol, as well as demographic and other risk factors, was obtained through in-person interviews. Associations with cigarette smoking and alcohol use were estimated by odds ratios (ORs) and 95% confidence intervals (CIs). Among women, the prevalence of smoking and alcohol drinking was low, and no significant association with colon or rectal cancer was observed. Although cigarette smoking among men was not related overall to colon or rectal cancer risk, there was a 50% excess risk of rectal cancer (OR 1.5, 95% CI 0.9-2.5) among those who smoked 55 or more pack-years. Among men, former alcohol drinkers had an increased risk of colon cancer (OR 2.3, 95% CI 1.4-3.7) but not rectal cancer, while current drinkers had a 30-50% excess risk of colon cancer only among those with long-term (30+ years) and heavy (>560 g ethanol/week) consumption. The excess risks were mainly associated with hard liquor consumption, with no material difference in risk between proximal and distal colon cancer. Although cigarette smoking and alcohol drinking in general were not risk factors for colorectal cancers in Shanghai, there were small excess risks for rectal cancer among heavy smokers and colon cancer among heavy drinkers.

Adult↗
PubMed2001

Association of body size and fat distribution with risk of breast cancer among Chinese women.

Most previous studies addressing the association of body size, weight change and body fat distribution with the risk of breast cancer were conducted in Western societies with a high proportion of overweight people. It remains unclear whether the dose-response relation observed in earlier studies can be extended to women with "normal" weight based on prevailing Western standards. To address this issue, we analyzed data from a population-based case-control study of breast cancer recently completed among Chinese women in urban Shanghai. In-person interviews and anthropometric measurements were completed for 1,459 women newly diagnosed with breast cancer from 25 to 64 years of age and 1,556 controls frequency-matched to cases on age. Unconditional logistic regression was employed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI) related to anthropometric variables and self-reported body weight. Currently measured weight, body mass index [BMI: weight (kg)/height(m)(2)] or height was each found to be positively related to risk of postmenopausal breast cancer in a dose-response manner, with ORs (95% CI) being 2.0 (1.4-3.0), 2.0 (1.2-3.2) or 1.7 (1.2-2.5), respectively, for the highest category of weight, BMI or height compared to the lowest category of these variables. These variables were unrelated to premenopausal breast cancer risk. Reported weight at ages >40 years and weight gain after age 20 were more predictive for postmenopausal breast cancer than weight at an earlier age. After adjustment for BMI, waist-to-hip ratio was related to an increased risk of premenopausal [OR = 1.7 (1.3-2.3) for the highest category compared to the lowest category] but not postmenopausal breast cancer. This study suggests that, even in a relatively thin Chinese population, weight gain and height are related to an increased risk of postmenopausal breast cancer, while central fat distribution was associated with premenopausal breast cancer. General weight control may be an effective measurement for breast cancer prevention.

Adipose Tissue↗
PubMed2001

Dietary folate intake and breast cancer risk: results from the Shanghai Breast Cancer Study.

Folate is involved in DNA synthesis, repair, and methylation. It has been hypothesized that high intake of folate may reduce the risk of human cancers, including cancer of the breast. Using data from a population-based case-control study of breast cancer conducted in urban Shanghai during 1996-1998, we evaluated the association of dietary folate intake and breast cancer risk among 1321 cases and 1382 controls, 25-64 years of age, who never drank alcohol regularly or used vitamin supplements. Usual dietary habits were assessed with an in-person, interviewer-administered food frequency questionnaire developed and tested for use in this population. Unconditional logistic regression models were used to calculate odds ratios (ORs) and their 95% confidence intervals (95% CIs) after adjusting for potential confounding factors. Dietary folate intake was inversely associated with breast cancer risk (P for trend, 0.05) with an adjusted OR of 0.71 (95% CI, 0.56-0.92) observed among women who were in the highest quintile of intake. The inverse association was stronger after further adjusting for total fruit and vegetable and animal food intakes (OR, 0.62; 95% CI, 0.46-0.82; P for trend, 0.01). A more pronounced inverse association between folate intake and breast cancer risk (OR, 0.47; 95% CI, 0.25-0.88; P for trend, 0.01) was observed among women who consumed high levels of folate cofactors (methionine, vitamin B(12), and vitamin B(6)) than those whose intake levels of these nutrients were low. Dietary intake of methionine, vitamin B(12), and vitamin B(6) were not independently related to risk of breast cancer after adjusting for confounding factors. Thus, our study adds additional support to the protective role of dietary folate in breast carcinogenesis and suggests further that the effect of folate may be modified by dietary intake of methionine, vitamin B(12), and vitamin B(6).

Adult↗
PubMed2001

CHIP is a U-box-dependent E3 ubiquitin ligase: identification of Hsc70 as a target for ubiquitylation.

Proper folding of proteins (either newly synthesized or damaged in response to a stressful event) occurs in a highly regulated fashion. Cytosolic chaperones such as Hsc/Hsp70 are assisted by cofactors that modulate the folding machinery in a positive or negative manner. CHIP (carboxyl terminus of Hsc70-interacting protein) is such a cofactor that interacts with Hsc70 and, in general, attenuates its most well characterized functions. In addition, CHIP accelerates ubiquitin-dependent degradation of chaperone substrates. Using an in vitro ubiquitylation assay with recombinant proteins, we demonstrate that CHIP possesses intrinsic E3 ubiquitin ligase activity and promotes ubiquitylation. This activity is dependent on the carboxyl-terminal U-box. CHIP interacts functionally and physically with the stress-responsive ubiquitin-conjugating enzyme family UBCH5. Surprisingly, a major target of the ubiquitin ligase activity of CHIP is Hsc70 itself. CHIP ubiquitylates Hsc70, primarily with short, noncanonical multiubiquitin chains but has no appreciable effect on steady-state levels or half-life of this protein. This effect may have heretofore unanticipated consequences with regard to the chaperoning activities of Hsc70 or its ability to deliver substrates to the proteasome. These studies demonstrate that CHIP is a bona fide ubiquitin ligase and indicate that U-box-containing proteins may comprise a new family of E3s.

Animals↗
PubMed2001

Population-based case-control study of soyfood intake and breast cancer risk in Shanghai.

We evaluated the association of soyfood intake and breast cancer risk in a population-based case-control study among Chinese women in Shanghai. Included in the study were 1459 cases and 1556 age-matched controls, with respective response rates of 91.1% and 90.3%. Usual soyfood intake was assessed using a food frequency questionnaire (FFQ). Separate analyses were performed for all subjects and for the subset who reported no recent change in soyfood intake. The intake levels of soyfoods among women in Shanghai are high, with 96.6% women reporting soyfood consumption at least once a week. A statistically non-significant reduced risk (odds ratio (OR) = 0.78 95% CI = 0.52-1.16) of breast cancer was observed among those who reported eating soyfood at least once a week. Compared to those in the lowest decile intake group, women in the highest decile intake group had a 30% reduced risk of breast cancer (OR = 0.66, 95% CI = 0.46-0.95), but no monotonic dose-response relation was observed (P for trend, 0.28). Stratified analyses showed that the inverse association was restricted primarily among women who had a high body mass index (BMI), with an adjusted OR of 0.30 (95% CI = 0.10-0.94) observed for the highest intake group. The reduction in risk was stronger for breast cancer positive for both oestrogen receptor (ER) and progesterone receptor (PR) (OR = 0.44, 95% CI = 0.25-0.78) than those with other ER/PR status. More pronounced inverse associations were observed in analyses among those who reported no recent change in soyfood intake than those conducted in all subjects. A dose-response relation between soyfood intake and breast cancer risk was observed in this subset of women (P for trend, 0.02), with an OR of 0.46 (95%CI = 0.28-0.75) for those in the highest decile intake group. No clear monotonic dose-response relation was found between soyfood intake and breast cancer risk among regular soy eaters, but nevertheless the results suggest that regular soyfood consumption may reduce the risk of breast cancer, particularly for those positive for ER and PR; the effect may be modified by body mass index.

Body Constitution↗
PubMed2001

Abortion history and breast cancer risk: results from the Shanghai Breast Cancer Study.

Studies of the association between induced abortion and breast cancer risk have been inconsistent, perhaps due to underreporting of abortions. Induced abortion is a well-accepted family planning procedure in China, and women who have several induced abortions do not feel stigmatized. The authors used data from a population-based case-control study of breast cancer among women age 25-64 conducted between 1996 and 1998 in urban Shanghai to assess whether a history of and the number of induced abortions were related to breast cancer risk. In-person interviews were completed with 1,459 incident breast cancer cases ascertained through a population-based cancer registry, and 1,556 controls randomly selected from the general population in Shanghai (with respective response rates of 91% and 90%). After adjusting for confounding, there was no relation between ever having had an induced abortion and breast cancer (odds ratio [OR] = 0.9, 95% confidence interval [CI] 0.7-1.2). Women who had 3 or more induced abortions were not at increased risk of premenopausal breast cancer (OR = 0.9, 95% CI 0.6-1.4) or postmenopausal breast cancer (OR = 1.3, 95% CI 0.8-2.3). These results suggest that a history of several induced abortions has little influence on breast cancer risk in Chinese women.

Abortion, Induced↗
PubMed2001

Lifetime physical activity and breast cancer risk in the Shanghai Breast Cancer Study.

Overall physical activity in adolescence and adulthood, and changes in activity over the lifespan were analysed by in-person interviews among 1459 women newly diagnosed with breast cancer and 1556 age-matched controls in urban Shanghai. Physical activity from exercise and sports, household, and transportation (walking and cycling) was assessed in adolescence (13-19 y) and adulthood (last 10 y), as was lifetime occupational activity. Logistic regression was used to estimate odds ratios (OR) and 95% confidence limits (OR (95% CL)) while controlling for confounders. Risk was reduced for exercise only in adolescence (OR = 0.84 (0.70-1.00)); exercise only in adulthood (OR = 0.68 (0.53-0.88)), and was further reduced for exercise in both adolescence and adulthood (OR = 0.47 (0.36-0.62)). Graded reductions in risk were noted with increasing years of exercise participation (OR(1-5 yrs)= 0.81 (0.67-0.94); OR(6-10 yrs)= 0.74 (0.59-0.93); OR(11-15 yrs)= 0.55 (0.38-0.79); OR(16 + yrs)= 0.40 (0.27-0.60);P(trend,)< 0.01). Lifetime occupational activity also was inversely related to risk (P(trend)< 0.01). These findings demonstrate that consistently high activity levels throughout life reduce breast cancer risk. Furthermore, they suggest that women may reduce their risk by increasing their activity levels in adulthood.

Adolescent↗
PubMed2001

A common deletion at chromosomal region 17q21 in sporadic prostate tumors distal to BRCA1.

Prostate cancer is the most common cancer in males in the United States, yet the etiology of this disease is still poorly understood. In previous work from our laboratory, one or more deleted regions were found in prostate tumors distal to the breast and ovarian cancer susceptibility gene (BRCA1) on chromosome 17. This suggested that genes at 17q21 may play a pivotal role in prostate cancer progression, and there may be new tumor suppressor genes at this locus. We now present a physical map built with P1, P1 artificial chromosome, and bacterial artificial chromosome clones encompassing a DNA sequence anchored by multiple STS markers. The analysis of prostate tumors indicated an 85-kb novel commonly deleted interval flanked by D17S1184-D17S183-D17S1203-D17S1860, which is at least 470 kb distal to the BRCA1 gene. Fifty-four of 126 prostrate cancer cases (43%) showed a deletion by a direct FISH technique using P1 probes in this region. Searching with clone end sequences in the sequence database BLAST, the deleted clone covered genomic DNA sequence that contained upstream binding factor (UBF), EPB3 genes, SHCL1, ASB-4-like sequence, and acidic protein-like sequence. PCR for the ESTs confirmed that these genes or ESTs are within the deletion region. Our results will be helpful for finding candidate tumor suppressor genes in prostate cancer.

Chromosome Deletion↗
PubMed2001

Effect of ligustrazine on hematopoiesis in bone marrow transplantation mice.

The effect of Ligustrazine on the hematopoiesis after bone marrow transplantation (BMT) in allogenic BMT mice was investigated. After the typical mice model of allogenic BMT had been established, the mice were randomly divided into three groups: BMT group, Ligustrazine group and normal group. The BMT group was given normal saline (0.2 ml, twice a day) through gastric tube, while the Ligustrazine group was given Ligustrazine through gastric tube (0.2 ml, twice a day). At the 1st, 7th and 14th day after BMT, we observed the peripheral blood cells and bone marrow nuclear cells (BMNC), as well as the expression level of Heparan Sulfate (HS) and stromal cell derived factor-1 (SDF-1) on bone marrow sections by using immunohistochemistry (SABC-AP), the expression of CXCR4 on the BMNC. The results showed that on the 7th and 14th day, the peripheral blood white cells, platelets, BMNC and the expression levels of CXCR4, HS and SDF-1 were significantly higher in Ligustrazine group than in the BMT group (P < 0.05). It was concluded that Ligustrazine could promote hematopoiesis at the early stage of hematopoietic reconstitution after BMT.

Animals↗
PubMed2001

Mitochondrial DNA polymorphisms in Yunnan nationalities in China.

Nucleotide sequences of the D-loop region of human mitochondrial DNA from four Yunnan nationalities, Dai, Wa, Lahu, and Tibetan, were analyzed. Based on a comparison of 563-bp sequences in 99 people, 66 different sequence types were observed. Of these, 64 were unique to their respective populations, whereas only 2 types were shared between the Lahu and Wa nationalities. The D-loop sequence variation and phylogenetic analysis suggested that the 99 mtDNA lineages were classified into eight clusters in the phylogenetic tree. All lineages that had a 9-bp deletion in the COII/tRNALYs intergenic region appeared in one cluster in the D-loop tree, suggesting a single event of the deletion in the Yunnan nationalities studied. Genetic distances, based on net nucleotide diversities between populations including Han Chinese and mainland Japanese, revealed that the Dai, Wa, Lahu, and Han Chinese are closely related to each other, while Tibetan and mainland Japanese formed a single cluster. The bootstrap probability of separation between the Dai-Wa-Lahu-Chinese clade and the Tibetan-Japanese clade was 99%, indicating that there are at least two different origins among minority groups in Yunnan province. Although the genetic distance between Tibetan and Japanese within the clade is rather long, the results may shed light on the origins of mainland Japanese.

Base Sequence↗
PubMed2001

Improved clinical outcome of paediatric bone marrow recipients using a test dose and Bayesian pharmacokinetic individualization of busulfan dosage regimens.

In order to control busulfan pharmacokinetic variability and toxicity, a specific monitoring protocol was instituted in our bone marrow transplant BMT paediatric patients including a test dose, daily Bayesian forecasting of busulfan plasma levels, and Bayesian individualization of busulfan dosage regimens. Twenty-nine children received BMT after a busulfan-based conditioning regimen. Individual pharmacokinetic parameters were obtained following a 0.5 mg*kg test dose and were used for daily individualization of dosage regimens during the subsequent 4-day course of treatment. Doses were adjusted to reach a target mean AUC per 6 h between 4 and 6 microg.h.ml(+1). Plasma busulfan assays were performed by liquid chromatography. Pharmacokinetic analysis used the USC*PACK software. The performance of the test dose to predict AUC during the busulfan regimen was evaluated. Incidence of toxicity, chimerism and relapse, overall Kaplan-Meier survival, and VOD-free survival were compared after matching our patients (group A) with patients conditioned by using standard doses of busulfan (group B). Busulfan doses were decreased in 69% of patients compared to conventional doses. Expected AUC was significantly correlated with observed AUC and predictability of the test dose was 101.9 +/- 17.9%. Incidence of VOD in group A was 3.4% vs 24.1% in group B, while the incidence of stomatitis was similar. Engraftment was successful in all patients in group A. The rate of full engraftment at 3 months post-BMT was higher in group A (P = 0.012). Long-term overall survival did not differ between the two groups, in contrast to the 90-day survival. VOD-free survival was higher in group A (P = 0.026). Pharmacokinetic monitoring and individualization of busulfan dosage regimen are useful in improving clinical outcome and reducing early mortality in paediatric bone marrow transplant recipients.

Adolescent↗
PubMed2001

The basic helix-loop-helix transcription factor Cph2 regulates hyphal development in Candida albicans partly via TEC1.

Candida albicans undergoes a morphogenetic switch from budding yeast to hyphal growth form in response to a variety of stimuli and growth conditions. Multiple signaling pathways, including a Cph1-mediated mitogen-activated protein kinase pathway and an Efg1-mediated cyclic AMP/protein kinase A pathway, regulate the transition. Here we report the identification of a basic helix-loop-helix transcription factor of the Myc subfamily (Cph2) by its ability to promote pseudohyphal growth in Saccharomyces cerevisiae. Like sterol response element binding protein 1, Cph2 has a Tyr instead of a conserved Arg in the basic DNA binding region. Cph2 regulates hyphal development in C. albicans, as cph2/cph2 mutant strains show medium-specific impairment in hyphal development and in the induction of hypha-specific genes. However, many hypha-specific genes do not have potential Cph2 binding sites in their upstream regions. Interestingly, upstream sequences of all known hypha-specific genes are found to contain potential binding sites for Tec1, a regulator of hyphal development. Northern analysis shows that TEC1 transcription is highest in the medium in which cph2/cph2 displays a defect in hyphal development, and Cph2 is necessary for this transcriptional induction of TEC1. In vitro gel mobility shift experiments show that Cph2 directly binds to the two sterol regulatory element 1-like elements upstream of TEC1. Furthermore, the ectopic expression of TEC1 suppresses the defect of cph2/cph2 in hyphal development. Therefore, the function of Cph2 in hyphal transcription is mediated, in part, through Tec1. We further show that this function of Cph2 is independent of the Cph1- and Efg1-mediated pathways.

Amino Acid Sequence↗
PubMed2001

Epidemiological study of urinary 6beta-hydroxycortisol to cortisol ratios and breast cancer risk.

The ratio of urinary 6beta-hydroxycortisol:cortisol is a measure of the activity of cytochrome p450 3A4 (CYP3A4). CYP3A4 catalyzes the formation of the genotoxic estrogen, 16alpha-hydroxyestrone. It is also involved in the activation of many other mammary carcinogens, such as the polycyclic aromatic hydrocarbons and heterocyclic amines. We evaluated the association between urinary cortisol ratios and breast cancer risk in a subgroup of women who participated in a population-based case-control study in Shanghai. Overnight urine samples from 246 case-control pairs were assayed for 6beta-hydroxycortisol (6beta-OHC) to cortisol. The urine samples from all of the breast cancer patients were collected before any chemotherapy or radiotherapy. In-person interviews were conducted to obtain comprehensive information on dietary habits, reproductive history, and other lifestyle factors. The median levels of 6beta-OHC:cortisol ratios were 2.61 in cases and 2.16 in controls, a 20.8% difference (P < 0.001). The case-control difference was larger in women over 45 years of age (31.3% difference; P < 0.001) than younger women (6.0%; P = 0.45). After adjusting for confounding variables, the risks of breast cancer were increased from 1.0 (reference) to 1.6 [95% confidence interval (CI), 0.9-3.1], 2.2 (95% CI, 1.1-4.2), and 3.7 (95% CI, 1.9-7.4; P for trend, <0.001) with increasing levels of 6beta-OHC:cortisol ratios. The positive association was more pronounced among older women (>45 years) than among younger women (< or = 45 years). The adjusted odds ratios associated with the highest cortisol ratio were 6.0 (95%CI, 2.2-16.1) among older women and 2.2 (95%CI, 0.8-6.1) among younger women. The association of the 6beta-OHC:cortisol ratio was stronger among older women who had a high body mass index, late age at menopause, and early age at menarche (factors related to high endogenous estrogen exposure) than those who did not have these factors. These findings are consistent with the role of CYP3A4 in estrogen and carcinogen metabolism and suggest that high CYP3A4 activity may be a risk factor for breast cancer risk.

Adult↗
PubMed2001

[Genetic relationship among four Yunnan populations revealed by sequence of mtDNA D-loop].

mtDNA D-loop noncoding region 16048-16569 and the following 1-41 (563 bp) in 99 individuals of four Yunnan ethnic minorities (Dai, Wa, Lahu and Tibetan) were sequenced and then a phylogenetic tree was reconstructed by Neighbor-Joining method. These 99 mtDNA lineages were classified into 3 genotype groups in the tree. All lineages with 9 bp deletion in the COII/tRAN(Lys) intergenic region were clustered in group I, some individuals of Dai, Lahu, Wa and only 2 Tibetan individuals clustered in group II, individuals of all four populations were included in group III. A phylogenetic tree of the four populations was constructed by NJ method on the basis of estimate of net genetic distance among them. Our results showed, the genetic distance among Dai, Wa and Lahu is very close, but far from Tibetan, their genetic distance is similar to their geographic distance. Although both as descendants of ancient Di-Qiang tribe in history and speaking similar language, Lahu and Tibetan are not closely related. This result indicates that there are different origins of these two populations.

China↗