Phylogenetic relationships of Asian and European pig breeds determined by mitochondrial DNA D-loop sequence polymorphism

Phylogenetic relationships among Asian and European pig breeds were assessed using 1036 bp of mitochondrial DNA (mtDNA) D-loop sequences. An unweighted pair-group method with arithmetic mean (UPGMA) tree was constructed on the basis of maximum likelihood distances using sequences determined for three Cheju (Korea), 11 Chinese, one Westran (Australian feral origin) and two European pigs (Berkshire and Welsh), and also published sequences for four Japanese (including two Wild Boars), one Yucatan miniature, five European (including Large White, Landrace, Duroc, Swedish and Wild Boar) and two Meishan pigs. The Colombian collared peccary (Tayassu tajacu) sequence was also determined and used as an outgroup. The maximum parsimony with heuristic search method was used to determine bootstrap support values. Asian-type pigs clustered together (bootstrap support 33%), but were separate from European-type pigs that also clustered together (93%). The Westran pig, derived from the feral descendants of pigs inhabiting Kangaroo Island of South Australia, clustered with Asian pigs, demonstrating Asian origin of their mitochondria. Berkshire and Large White clustered with Asian pigs, indicating that Asian pigs were involved in the development of these breeds. Our findings clearly demonstrate that pigs indigenous to China, Korea and Japan are only recently diverged from each other and distinctly different from European-type pigs. European pig breeds consist of pigs with mitochondria of Asian and non-Asian type, some of which were formed from closely related maternal ancestors, if not from a single ancestor.

Detection of usual and atypical aldehyde dehydrogenase alleles by mismatch amplification mutation assay

The genotypes of liver mitochondrial high-affinity aldehyde dehydrogenase-2 (ALDH2) are strongly associated with the drinking behavior and the alcohol liver diseases, since the individuals with atypical ALDH2(2) allele have higher levels of acetaldehyde in their plasma. The atypical ALDH2(2) allele has a nucleotide base transition (G-->A) in its exon 12. Based on this point mutation, we developed a rapid, reliable and inexpensive method, mismatch amplification mutation assay (MAMA), for the determination of human ALDH2 usual and atypical alleles. Two pairs of primers were designed for the amplification of the usual ALDH2(1) allele and the atypical ALDH2(2) allele, respectively. If the sample for the detection was heterozygous, it could be amplified by both of the primers. The product of polymerase chain reaction (PCR) of ALDH2 exon 12 could be easily screened by electrophoresis on a 2% agarose gel. The results of the MAMA method were further confirmed by sequencing. In the total of fifty samples from unrelated healthy Chinese Han people from Wuhan, China, the frequency of atypical ALDH2(2) allele was found to be 12%.

Mitochondrial cytochrome b gene sequence diversity in the Korean hare, Lepus coreanus Thomas (Mammalia, Lagomorpha)

Partial sequences of the mitochondrial cytochrome b gene of the Korean hare (Lepus coreanus) were analyzed to determine the degree of genetic diversity. Nine haplotypes were observed, and the maximum Tamura-Nei nucleotide distance among them was 2.8%, indicating that genetic diversity of L. coreanus is moderate. In order to clarify the Korean hare's taxonomic status and relationship with the Manchurian hare (L. mandshuricus) and the Chinese hare (L. sinensis), these nine haplotypes of the Korean hare were compared with 13 haplotypes from five other species of eastern Asian Lepus including L. mandshuricus and L. sinensis. The Korean hare was distinct in its cytochrome b gene, and it is confirmed that L. coreanus is a valid species, as noted by Jones and Johnson (1965, Univ. Kansas Publ. (Mus. Nat. Hist.) 16:357). Further analyses of mtDNA cytochrome b gene with additional specimens of L. coreanus from North Korea and other species of Lepus from eastern Asia are needed to clarify the taxonomic status of the divergent mtDNA clades of L. mandshuricus and L. sinensis.

A polyalanine-based peptide cannot form a stable transmembrane alpha-helix in fully hydrated phospholipid bilayers

The conformation and amide proton exchangeability of the peptide acetyl-K(2)-A(24)-K(2)-amide (A(24)) and its interaction with phosphatidylcholine bilayers were examined by a variety of physical techniques. When dissolved in or cast from methanol as a dried film, A(24) is predominantly alpha-helical. In aqueous media, however, A(24) exists primarily as a mixture of helical (though not necessarily alpha-helical) and random coiled structures, both of which allow rapid H-D exchange of all amide protons. When incorporated into phospholipids in the absence of water, A(24) also exists primarily as a transmembrane alpha-helix. However, upon hydration of that system, rapid exchange of all amide protons also occurs along with a marked change in the amide I absorption band of the peptide. Also, when dispersed with phosphatidylcholine in aqueous media, the conformation and thermal stability of A(24) are not significantly altered by the presence of the phospholipid or by its gel/liquid-crystalline phase transition. Differential scanning calorimetric and electron spin resonance spectroscopic studies indicate that A(24) has relatively minor effects on the thermodynamic properties of the lipid hydrocarbon chain-melting phase transition, that it does not abolish the lipid pretransition, and that its presence has no significant effect on the orientational order or rates of motion of the phospholipid hydrocarbon chains. We therefore conclude that A(24) has sufficient alpha-helical propensity, but insufficient hydrophobicity, to maintain a stable transmembrane association with phospholipid bilayers in the presence of water. Instead, it exists primarily as a dynamic mixture of helices and other conformers and resides mostly in the aqueous phase where it interacts weakly with the bilayer surface or with the polar/apolar interfacial region of phosphatidylcholine bilayers. Thus, polyalanine-based peptides are not good models for the transmembrane alpha-helical segments of natural membrane proteins.

Eye irritation caused by formaldehyde as an indoor air pollution--a controlled human exposure experiment

OBJECTIVE

The present study focuses on health assessment of wood based panels which are widely used in interior decoration practices over the recent years in China. Formaldehyde has been identified as chemical indicator of (IAO) and an indoor air pollutant. To test its health effects experiment was undertaken.

METHOD

A small environmental test chamber (60/L) was used as the generator of emission gas from new panels, and was operating at a temperature of 22.7 +/- 0.6 degrees C and a humidity of 44.4 +/- 2.5% with an air exchange rate of 1.0 +/- 0.15 h-1. On the three experimental days the values of product loading in chamber were 4, 2 and 6 m2/m3, respectively. Eight people were selected randomly from the students and employees of Wuhan Health and Anti-epidemic Station as subjects, with an average age of 21.9 +/- 5.9 years, and a gender ratio of 1:1, and two of them were smokers (one male and one female). The subjects' eyes were exposed to formaldehyde through a pair of goggles. Each goggle had its flow inlet and outlet, and connected to chamber exhaust of emission gas and to an exhaust from the room. The exposure time was very short, just 5 minutes and the formaldehyde doses were at 1.65 +/- 0.01, 2.99 +/- 0.07 and 4.31 +/- 0.02 ppm. A 60-mm linear visual analogue rating scales was used to measure the intensity of sensory eye irritation and a video tape recorder was used to record eye blinking frequency.

RESULTS

The results demonstrated that tests of sensory eye irritation and eye blinking can be used for materials testing, and that a dose-effect as well as a time-variance of the effect can be measured.

CONCLUSION

The tests showed that eye irritation was perceived at all of the three levels.

[Application of capillary electrophoresis in the analysis of pesticides]

Capillary electrophoresis has proved to be a suitable microseparation technique for the analysis of a wide variety of chiral and achiral pesticides. In this paper, the applications and developments in the field of pesticide separation by HPCE are reviewed with 50 references, including different operating models and chiral agents. Furthermore, the advantage and trend of development are also pointed out.

[Studies of genetic diversity of Zhejiang native chicken breeds]

A total of 539 bases of mitochondrial DNA D-loop region of five native chicken breeds of Zhejiang province and the white leghorn chicken (as the control) were sequenced by DNA sequencing technique, and the phylogenetic trees of the chicken breeds were constructed. The results showed that 24 variation sites i.e. 4.45% sequence divergence were detected among the 30 DNA sequences, and the six breeds belonged to two different maternal lineage, one included Xianju chicken and White Leghorn chicken which had the same maternal origin, the other included Lingkun chicken, Baiyiner chicken, Wugu chicken and Xiaoshan chicken which had the same matriarchic ancestor. Among the latter lineage, Lingkun chicken, Baiyiner chicken and Wugu chicken had a closer relationship to each other than to Xiaoshan chicken.

Identification of Sarcocystis hominis-like (Protozoa: Sarcocystidae) cyst in water buffalo (Bubalus bubalis) based on 18S rRNA gene sequences

DNA templates were extracted from isolates of Sarcocystis hominis-like cysts collected from cattle and water buffalo, as well as from Sarcocystis fusiformis cysts and Sarcocystis suihominis cysts. The 18S rRNA genes were amplified using DNA from a single cyst as the templates. Approximately 1,367-1,440 bp sequences were obtained. The sequence difference in isolates of Sarcocystis hominis-like cysts from water buffaloes, and isolates of S. hominis cysts from cattle were very low, only about 0.1%, much lower than the lowest value (1.7%) among different species. Combined with their morphological structure, these sequence data indicate that the 4 isolates from cattle and water buffalo might be the same species, i.e., S. hominis, suggesting that both cattle and water buffalo may serve as the intermediate hosts for this parasite. Apparently, this is the first report using a single cyst to do such work and is a useful way to distinguish the Sarcocystis cyst in an intermediate host that may be simultaneously infected by several different Sarcocystis species.

[Mitochondrial DNA sequence variations of Shui ethnic group]

The mtDNA hypervariable segment I sequences (HVS I) were sequenced in 64 Shuis from Guizhou Province. 73 sites were polymorphic in the 495 bp fragment that sequenced, identified 48 different haplotypes. Phylogenetic analysis of the haplotypes suggested that there were some ancestral haplotypes in current Shuis, and these haplotypes were also present in Eurasia populations as well as in other ethnic groups. Demographic analysis of the Shuis demonstrated a unimodal distribution that is typical for a population undergone expansion in the past and with a high Tau value, which suggested that the Shui group might be a ancestral population. Combined with the analysis of the reported data, the Shui ethnic group showed a generally similar genetic component with the Zhuang from Guangxi, but it is also different from these typical south populations as Zhuang, Cantonese.

Comparative seven-day clinical evaluation of two tooth whitening products

A 1-week study was conducted to compare the tooth whitening efficacy of two carbamide peroxide-based products (one containing 5% carbamide peroxide and one containing 10% carbamide peroxide). In addition, the perception of transient tooth hypersensitivity associated with the use of these products was subjectively evaluated. Sixty participants took part in a double-blind, randomized, parallel clinical study. Change in tooth color was measured by chroma meter and Vita shade guide at the initiation of the study and after 7 days of product use. Color change (delta E) was calculated using the color-difference equation established by the Commission Internationale de L'Eclairage. Data concerning dental hypersensitivity was assessed by subjective panelist questionnaires administered after the day 7 recall examination. Results of the whitening data showed that there was no significant difference between the two products. After 1 week, the mean delta E for the product containing 5% carbamide peroxide was 4.43 +/- 1.89 and the mean delta E for the product containing 10% carbamide peroxide was 4.05 +/- 1.84. However, the subjective data collected on tooth hypersensitivity showed that the product containing 5% carbamide peroxide was associated with less discomfort. Of the group using the 5% carbamide peroxide product, 20% reported transient sensitivity of their teeth after product use for 1 week compared with 53% of the group using the product with 10% carbamide peroxide. Statistical analysis using a 2-tailed t test showed significant differences between the two groups (P < .05). The data suggest that these products are clinically equivalent for tooth whitening; however, the product containing 5% carbamide peroxide was associated with less tooth hypersensitivity after 1 week of application.

Molecular evolution of GH in primates: characterisation of the GH genes from slow loris and marmoset defines an episode of rapid evolutionary change

Pituitary growth hormone (GH), like several other protein hormones, shows an unusual episodic pattern of molecular evolution in which sustained bursts of rapid change are imposed on long periods of very slow evolution (near-stasis). A marked period of rapid change occurred in the evolution of GH in primates or a primate ancestor, and gave rise to the species specificity that is characteristic of human GH. We have defined more precisely the position of this burst by cloning and sequencing the GH genes for a prosimian, the slow loris (Nycticebus pygmaeus) and a New World monkey, marmoset (Callithrix jacchus). Slow loris GH is very similar in sequence to pig GH, demonstrating that the period of rapid change occurred during primate evolution, after the separation of lines leading to prosimians and higher primates. The putative marmoset GH is similar in sequence to human GH, demonstrating that the accelerated evolution occurred before divergence of New World monkeys and Old World monkeys/apes. The burst of change was confined largely to coding sequence for mature GH, and is not marked in other components of the gene sequence including signal peptide, 5' upstream region and introns. A number of factors support the idea that this episode of rapid change was due to positive adaptive selection. Thus (1) there is no apparent loss of function of GH in man compared with non-primates, (2) after the episode of rapid change the rate of evolution fell towards the slow basal level that is seen for most mammalian GHs, (3) the accelerated rate of substitution for the exons of the GH gene significantly exceeds that for introns, and (4) the amino acids contributing to the hydrophobic core of GH are strongly conserved when higher primate and other GH sequences are compared, and for coding sequences other than that coding for hydrophobic core residues the rate of substitution for non-synonymous sites (K(A)) is significantly greater than that for synonymous sites (K(S)). In slow loris, as in most non-primate mammals, there is no evidence for duplication of the GH gene, but in marmoset, as in rhesus monkey and man, the putative GH gene is one of a cluster of closely related genes.

[Studies of the origin of Chinese domestic fowls]

A total of 539 bases fragment of mitochondrial DNA D-loop region of six domestic chicken breeds (30 individuals) were sequenced and compared to that of red junglefowl, grey junglefowl, green junglefowl and Lafayette's junglefowl issued in GenBank, and the phylogenetic trees for the chickens constructed based on the D-loop sequences. The results indicated that the four species of genus Gallus had great differences between each other, the G. g. domesticus was the next of kin to red junglefowl in Thailand and its adjacent regions, and near of kin to red junglefowl in Indonesian, Lafayette's junglefowl, grey junglefowl and green junglefowl one by one in proper order, suggesting that the red junglefowl in Thailand and its neighbour areas sufficed as the matriarchic ancestor of Chinese domestic fowls. It was also discovered that the two subspecies of Thailand i.e. G. g. gallus and G. g. spadiceus should belong to one subspecies because of their far lower differentiation compared to that among the domestic breeds.

The enhanced anticaries efficacy of a sodium fluoride and dicalcium phosphate dihydrate dentifrice in a dual-chambered tube. A 2-year caries clinical study on children in the United States of America

PURPOSE

To clinically evaluate and compare a dentifrice system in a dual-chambered tube, wherein one chamber contained sodium fluoride in a silica base and the other chamber contained dicalcium phosphate dihydrate (Test Dentifrice delivering 0.243% sodium fluoride), to a dentifrice containing 0.243% sodium fluoride in a silica base (Positive Control Dentifrice).

MATERIALS AND METHODS

This study was conducted in harmony with the published 1988 American Dental Association guidelines for studies geared toward the comparison of fluoride dentifrices. This 2-yr caries clinical study employed a double-blind, parallel-group design, and involved 5-17 yr-old children from the Central and South areas of Florida and from the Lares area of Puerto Rico. Qualifying subjects were stratified according to age and sex, and were randomly assigned to the two treatment groups, with multiple subjects in the same household all assigned to the dentifrice randomly allocated to the first among them. Caries examinations were conducted in accordance with U.S. Food and Drug Administration guidelines for the clinical evaluation of drugs to prevent dental caries. Two calibrated examiners performed all the measurements. After treatment assignment, study participants were instructed to brush their teeth at home with their assigned dentifrice at least twice daily. Brushing instructions were reinforced by indoctrination in proper oral hygiene techniques by dental professionals, supplemented by pamphlets supplied by the sponsor and yearly mailings to participants, emphasizing good oral hygiene and the need to enforce compliance with the study. Post-baseline examinations were performed after 1 yr of product use, and again after 2 yrs of product use.

RESULTS

Two thousand five hundred six (2,506) subjects completed this 2-yr study. For these subjects, the mean caries scores (DMFS, decayed, missing and filled tooth surfaces) at baseline were 2.29 for the Test Dentifrice group, and 2.47 for the Positive Control Dentifrice group. For caries increments after 1 yr, the respective means were 0.69 for the Test Dentifrice group and 0.81 for the Positive Control Dentifrice group. Finally, after 2 yrs, the mean caries increments were 1.25 for the Test Dentifrice group, and 1.46 for the Positive Control Dentifrice group. No statistically significant difference was indicated between the treatment groups at baseline or between the 1-yr caries increment scores. However, there was a statistically significant difference in the 2-yr caries increment scores between the treatment groups. Relative to the Positive Control Dentifrice group, the Test Dentifrice group presented a 14.38% reduction in caries increment scores at 2 yrs. In accordance with the procedures and standards provided by the published guidelines of the American Dental Association for the comparison of the anticaries efficacy of fluoride dentifrices, the results of this study support the conclusion that the dentifrice system in a dual-chambered tube, wherein one chamber contained sodium fluoride in a silica base and the other chamber contained dicalcium phosphate dihydrate, delivering 0.243% sodium fluoride, provided a superior level of anticaries efficacy than did the dentifrice containing 0.243% sodium fluoride in a silica base.

Incidence rates and populations at risk for spinal cord injury: A regional study

STUDY DESIGN

A 6 year retrospective study was conducted.

OBJECTIVES

The populations at risk for spinal cord injury (SCI) in the northwestern Kentucky (KY) and southern Indiana (IN) regions were identified following examination of the causes and factors associated with SCI.

SETTING

The database included patients primarily from the surrounding KY and IN counties admitted to the University of Louisville (U of L) Hospital.

METHOD

Specification of SCI patient demographics, injury causes and related factors was achieved utilizing the hospital's trauma institute database and an extensive review of patient medical records.

RESULTS

An adjusted average incidence rate of 27.1 cases per million per year was obtained for this region. A high rate of SCI was found for the youngest age group, 14-24 year olds, and for African Americans. A high frequency of injuries was also observed for adults between the ages of 25-39 years. Motor vehicle accidents (MVA) were the leading cause of SCI. Contributing factors included alcohol and widespread non-use of vehicle safety precautions.

CONCLUSIONS

In addition to the high proportion of youth at risk for SCI, a higher proportion of older adults with SCI was observed for this region compared to other studies. Because the primary source of transportation in this area is the use of private vehicles, rather than public transportation, greater effort is warranted in emphasizing the potential risks of combining driving with alcohol consumption and non-use of seatbelts.

[Molecular evolution of the Thr-Gly region of the period gene in Drosophila and some dipterans]

In this study, the molecular evolution of the Thr-Gly region of the period gene was characterized, using dipteran groups with close, medium, and long distance phylogenetic relationship. No sexual selection or other positive selection was found to be acting on the Thr-Gly region. The evolutionary rate of the Thr-Gly region in nasuta subgroup was 10.4 x 10(-9) synonymous substitution/site/year. The divergence time of the nasuta subgroup of Drosophila was estimated to be 1-3 mya. A phylogenetic tree of Drosophila genus was reconstructed, which is well supported by evidences from archaebiological and biogeographical studies, The molecular evolutionary pattern of Thr-Gly region was discussed.

Embryonic brain precursors transplanted into kainate lesioned rat spinal cord

Embryonic day 14 rat cerebral cortex-derived precursors were expanded with FGF2 and labeled with BrdU prior to being transplanted into the kainic acid-lesioned adult rat spinal cord. While these precursors give rise to cells with neuronal, astrocytic and oligodendroglial phenotypes vitro, they remained largely undifferentiated up to 12 weeks in vivo. Numerous BrdU-labeled cells were found in injured gray matter, and also lining the dilated central canal that sometimes accompanies these lesions. BrdU-labeled cells never co-expressed Map2ab, rarely co-expressed GFAP but often co-expressed nestin, even after 12 weeks in vivo. These observations suggest that the environment of the kainic acid-injured spinal cord is not hostile to transplanted embryonic cerebral cortex-derived precursors, but also is not conducive to their neuronal differentation.

Function and regulation of cholecystokinin octapeptide, β-endorp hin and gastrin in anorexic infantile rats treated with ErBao Granules

AIM: To study the role of cholecystokinin octapeptide (CCK-8), β-endorphin (β-EP), and gastrin in an anorexic infantile rat model and no subsequent regulation of nose peptides by the Yunpi complex prescription ErBao Granule.

METHODS: We fed infantile rats with special prepared forage. A liquid extract of ErBao Granule was administered to the rats daily for 3 weeks, CCK-8, β-EP, and gastrin concentrations in hypothalamus, gastric antrum, and plasma of the rats were measured by radioimmunoassay, and were compared with controls.

RESULTS: Treatment of rats with ErBao Granule inhibited CCK-8 secretion and increased β-EP and gastrin secretion. CCK-8 concentration in hypothalamus and plasma of model control group increased significantly and correlated negatively with food intake of models, respectively. β-EP concentration in gastric antrum and plasma of model control group decreased significantly and showed a positive correlation with food intake of models, respectively. Hypothalamus concentration of β-EP was similar in models and controls. Gastrin concentration in gastric antrum of models was lower than in the blank control group, and correlated positively to food intake of models. Finally, CCK-8 concentrations in plasma of rats showed a positive correlation with plasma β-EP (r = -0.68, P < 0.05).

CONCLUSION: The increased plasma and hypothalamus concentration of CCK-8, decreased gastric antrum and plasma level of β-EP, and decreased gastric antrum concentration of gastrin are associated significantly with the anorexia of infantile anorexic rat models produced by special forage. ErBao Granule can reverse these changes, which may be the major mechanisms of ErBao Granule simulating feeding.

[Effects of running armored car on dynamic posture equilibrium]

Objective. To study the effects of training in running armored car on dynamic posture equilibrium. Method. Dynamic posture was tested pre- and post running armored car in 56 healthy men. Result. Compared to pre-training, certain equilibrium scores of sensory organization test condition 1 (P<0.05), 2 (P< 0.001), and 3 (P< 0.001) decreased significantly, while those of condition 4 (P<0.001) and 6 (P< 0.001) increased significantly. The static proprioception score (SOT2/SOT1 x 100) (P< 0.01) decreased significantly, while visual sensory score (SOT4/SOT1 x 100, P <0.01) and dynamic proprioception (SOT (4+5+6)/SOT(1+2+3) x 100, P<0.001) increased significantly post-training. The motor strategy scores of sensory organization test condition 2 (P<0.01) and 3 (P<0.001) significantly decreased. Conclusion. The results demonstrated that training in a running armored car influenced postural equilibrium and sensory organization.

[Mitochondrial DNA sequence variations of Zhuang ethnic group in Guangxi]

The mtDNA hypervariable segment I sequences (515bp) were sequenced in 83 Zhuangs from Gunngxi Province, with the aim to learn more about the origin and genetic structure of the current Zhuangs. 66 haplotypes were identified in the samples, with 71 sites showing polymorphism. Phylogenetic analysis of the 66 haplotypes suggests that there are geographic differentiation in current Zhuangs, and those from the 4 geographic regions (Nanning, Hechi, Baise and Liuzhou) have different distribution frequencies in the cluster I, II and III in the tree. More than 50% individuals from Liuzhou and Hechi converge into cluster II, while those from Nanning and Baise have high frequency in cluster I. Combined with the analysis of the reported data, the Zhuang ethnic group shows remote affinity to those from North China, whereas it is close to those in South China. The frequencies of the radiation groups in Zhuangs, together with the phylogenetic relationship of the Zhuang ethnic group in the tree suggest that the Zhuang is a typical south population.

[Different evolution rule of SRY gene between hominoid and Old World monkey]

The complete SRY gene of P. nemaeus and M. arctiodes were amplified by using PCR and sequenced. Combined with the same regions of other primate animals, sequence analysis confirmed the conservation of HMGbox. In molecular phylogenetic tree constructed, we made the Ka/Ks value pairwise comparison of HMGbox flanking sequences both intra- and inter- Hominoid and the Old World monkey. To our interest, the pairwise comparison of species in Hominoid suggested a higher Ka/Ks ratio than that in the Old World monkey or between the Old World monkey and marmoset, which showed existent of different pattern of evolution. In addition, in Hominoid Ka/Ks ratio for HMGbox sequences was obviously on the increase. The rate of nonsynonymous substitutions per nonsynonymous site is faster than that of synonymous substitutions per synonymous site in Hominoid (driven by positive directional selection). Our analysis suggested that it might be resulted from functional change of this gene and the system error or the close relationship among Hominoid species. It is also supposed that the positive selection was functioned at the beginning of the divergence of Hominoid species.

[The development and application of HP-I closed thoracic cavity drainer]

The closed thoracic cavity drainer is equipped with a general standard infusion bottle as the drainage bottle, which can be easily supplied by all hospitals. Therefore, the new drainer is a very practical, cheap medical device of easy operation.

Melanocortin-1 receptor gene variants in four Chinese ethnic populations

There is strong relationship between melanocortin-1 receptor (MC1R) gene variants and human hair color and skin type. Based on a sequencing study of MC1R gene in 50 individuals from the Uygur, Tibetan, Wa and Dai ethnic populations, we discuss the occurrence of 7 mc1r variants consisting of 5 nonsynonymous sites (Val60Leu, Arg67Gln, Val92Met, Arg163Gln and Ala299Val) and 2 synonymous sites (C414T and A942G), among which C414T and Ala299Val were reported for the first time. Confirmation and analysis were also made of 122 individuals at three common point mutations (Val92Met, Arg163Gln, A942G) using PCR-SSCP. The frequency of Arg163Gln variant varies in the four ethnic populations, with percentage of 40%, 85.0%, 66.2% and 72.7%, respectively, while those of Val92Met and A942G are roughly similar in these four populations. The different environments, migration and admixture of various ethnic groups in China might have impact on the observed frequency of Arg163Gln.