Regulation of the catalytic activity of preexisting tyrosinase in black and Caucasian human melanocyte cell cultures

The activity of tyrosinase, the rate-limiting enzyme for melanin synthesis, is higher in Black skin melanocytes than in melanocytes derived from Caucasian skin. This variation in enzyme activity is not due to differences in tyrosinase abundance or tyrosinase gene activity, but, rather, is due to differences in the catalytic activity of preexisting tyrosinase. In melanocytes, tyrosinase is localized to the membrane of melanosomes and in Caucasian melanocytes the melanosome-bound enzyme is largely inactive. Conversely, in melanosomes of Black melanocytes, tyrosinase has high catalytic activity. Treatment of Caucasian melanocytes with the lysosomotropic compound ammonium chloride or with the ionophores nigericin and monensin results in a rapid and pronounced increase in tyrosinase activity. This increase occurs without any change in tyrosinase abundance, indicating that these compounds are increasing the catalytic activity of preexisting enzyme. Inhibition of the vacuolar proton pump V-ATPase by treatment of Caucasian melanocytes with bafilomycin also increases tyrosinase activity. In contrast to the 10-fold increase in tyrosinase observed in Caucasian melanocytes, neither ammonium chloride, monensin, nigericin, nor bafilomycin is able to increase the already high level of tyrosinase activity present in melanosomes of melanocytes derived from Black skin. Finally, staining of Caucasian melanocytes with the fluorescent weak base acridine orange shows that melanosomes of Caucasian, but not Black, melanocytes are acidic organelles. These data support a model for racial pigmentation that is based on differences in melanosome pH in Black and Caucasian skin types. The models suggests that melanosomes of Caucasian melanocytes are acidic, while those of Black individuals are more neutral. Since tyrosinase is inactive in an acid environment, the enzyme is largely inactive in Caucasian melanosomes but fully active in Black melanosomes.     

Mitochondrial DNA variation in Asian Shepherd Dogs

The hypervariable region of the mitochondrial DNA (mtDNA) control region has been studied in several guardian dog breeds. The genetic diversity is high in the Central Asian Shepherd Dog and the Northern Caucasian Volkodav (an native group of breeds) and low in the Caucasian Shepherd Dog. Haplotypes of groups A, B, C, and E/W have been found in Central Asian Shepherd Dogs; haplotypes of groups A and B, in Caucasian Shepherd Dogs. The data indicates a gene flow from Scandinavian dog populations to the Northern Caucasus. The results of the analysis allow the Caucasian Shepherd Dog, Northern Caucasian Volkodav, Central Asian Shepherd Dog, and the Turkish breeds akbash and kangal to be combined into a single group with an extremely low degree of differentiation.     

Mitochondrial DNA variation in Asian guardian dogs

The hypervariable site of the mitochondrial DNA (mtDNA) control region has been studied in several sheepdog breeds. The genetic diversity is high in the Central Asian guardian dog and the Northern Caucasian wolf dog (an aboriginal group of breeds) and low in the Caucasian guardian dog. Haplotypes of groups A, B, C, and E/W have been found in Central Asian guardian dogs; haplotypes of groups A and B, in Caucasian guardian dogs. There is evidence suggesting a gene flow from Scandinavian dog populations to the Northern Caucasus. The results of the analysis allow the Caucasian guardian dog, Northern Caucasian wolf dog, Central Asian guardian dog, and the Turkish breeds akbash and kangal to be combined into a single group with an extremely low degree of differentiation.     

Genogeographic analysis of subdivided population. The Adyge gene pool in the Caucasian gene pool system]

A gene geographic analysis of the indigenous population of the Caucasian historical cultural province was carried out with a set of genetic markers extensively studied in the Adyges (39 alleles of 18 loci): AB0, ACP, C3, FY, GC, GLO, HP, KEL, LEW, MN, MNS, P, PGD, PGM1, RH-C, RH-D, RH-E, and TF. Genetic information on 160 Caucasian populations was used (on average, 65 populations per locus). A synthetic map of the first principal component clearly showed a division into two gene geographic provinces: Northern Caucasus and Transcaucasia. The component significantly differed across the Greater Caucasian Ridge. One of the major regions of extreme values corresponded to the Adyge region. A map of the second component revealed two poles, Northwestern (the Adyges) and Caspian, in gene pool variation of the Caucasian population. The analysis of the maps and the space of principal components showed that the Adyge population is an important component of the Caucasian gene pool. A map of genetic distance from all Caucasian populations to the Adyges showed that the north Caucasian populations (excluding the Ossetes) are the most genetically similar to the Adyges, while Georgians from the Kolkhida Valley and Azerbaijanians from the lowlands near the Caspian Sea and highland steppes are the most genetically remote from the Adyges. The genetic diversity (GST x 10(2)) of the entire Caucasian gene pool was studied. The average diversity of subpopulation within a Caucasian ethnos was GS-E = 0.81, the diversity of ethnoses within a linguistic family was GE-L = 0.83, and the diversity of linguistic families was GL-T = 0.58. The race classification of the Caucasian populations (GS-E = 0.81, GS-R = 0.80, GR-T = 0.76) proved to be more genetically informative than the linguistic one. The major parameters of the Adyges (total diversity HT = 0.364, heterozygosity HS = 0.361, and subpopulation diversity within the ethnos GS-E = 0.69) were similar to those averaged over the entire Caucasian population. A comparison with the same set of genetic markers showed that the interethnic diversity in the Caucasian region was lower than in the other north Eurasian regions (GS-E was 1.24 in the European region, 1.42 in the Ural region, 1.27 in Middle Asia, and 3.85 in Siberia).     

Pseudoautosomal repeat displays higher variability in Blacks than in Caucasians

Summary DNA patterns from a pseudoautosomal variable number tandem repeat-like minisatellite (locus DXYS20) were compared in two samples: a Caucasian and a Black sample. We defined 3 types of DNA patterns named A, B and C, and found that these patterns have different frequencies in the Caucasian and Black groups. A set of alleles (the C group) in 48% of the Black sample is not found in the Caucasian sample. We also found a greater degree of fragment-size variability among Black individuals than among those of Caucasian origin. The large degree of ethnic variation indicates that this locus will be useful in population genetic studies.     

Similarities and differences in Chinese and Caucasian adults' use of facial cues for trustworthiness judgments

Background

All cultural groups in the world place paramount value on interpersonal trust. Existing research suggests that although accurate judgments of another''s trustworthiness require extensive interactions with the person, we often make trustworthiness judgments based on facial cues on the first encounter. However, little is known about what facial cues are used for such judgments and what the bases are on which individuals make their trustworthiness judgments.

Methodology/Principal Findings

In the present study, we tested the hypothesis that individuals may use facial attractiveness cues as a “shortcut” for judging another''s trustworthiness due to the lack of other more informative and in-depth information about trustworthiness. Using data-driven statistical models of 3D Caucasian faces, we compared facial cues used for judging the trustworthiness of Caucasian faces by Caucasian participants who were highly experienced with Caucasian faces, and the facial cues used by Chinese participants who were unfamiliar with Caucasian faces. We found that Chinese and Caucasian participants used similar facial cues to judge trustworthiness. Also, both Chinese and Caucasian participants used almost identical facial cues for judging trustworthiness and attractiveness.

Conclusions/Significance

The results suggest that without opportunities to interact with another person extensively, we use the less racially specific and more universal attractiveness cues as a “shortcut” for trustworthiness judgments.     

Genetic and morphological variation in a partially isolated population of Caucasian shrew sorex Satunini (Mammalia)

Morphological and genetic variation at microsatellite loci of Caucasian shrew Sorex satunini Ogn. is examined and compared with that of the common shrew S. araneus L. Genetic distance at microsatellite loci between the common shrew and Caucasian shrew proved to be threefold higher than between chromosome races of the common shrew. The Caucasian shrew manifested low polymorphism in studies of both microsatellites and morphometric mandibular traits. The heterozygote deficit was also typical. These properties may be a consequence of partial isolation of the population and gene drift.     

Frequency of an electrophoretic variant of hair alpha keratin in human populations.

A previously reported electrophoretic variant in hair keratin was looked for in a number of different racial groups. Only Caucasian samples showed the variant with the exception of one American black and one American Indian where Caucasian admixture is likely.     

Genetic and morphological variation in a partially isolated population of Caucasian shrew <Emphasis Type="Italic">Sorex satunini</Emphasis> (Mammalia)

Morphological and genetic variation at microsatellite loci of Caucasian shrew Sorex satunini Ogn. is examined and compared with that of the common shrew S. araneus L. Genetic distance at microsatellite loci between the common shrew and Caucasian shrew proved to be threefold higher than between chromosome races of the common shrew. The Caucasian shrew manifested low polymorphism in studies of both microsatellites and morphometric mandibular traits. The heterozygote deficit was also typical. These properties may be a consequence of partial isolation of the population and gene drift.     

Ways of the fleas (Siphonaptera) fauna formation in the Caucasus

Fleas fauna of the Caucasus is considered, possible ways of its formation are discussed. Caucasian fleas belong to 155 species and 40 genera; 23 species are endemics. Hypothesis on Western Palearctic and Eastern Palearctic sources of the Caucasian fleas' fauna formation are proposed.     

Adults scan own- and other-race faces differently

It is well established that individuals show an other-race effect (ORE) in face recognition: they recognize own-race faces better than other-race faces. The present study tested the hypothesis that individuals would also scan own- and other-race faces differently. We asked Chinese participants to remember Chinese and Caucasian faces and we tested their memory of the faces over five testing blocks. The participants' eye movements were recorded with the use of an eye tracker. The data were analyzed with an Area of Interest approach using the key AOIs of a face (eyes, nose, and mouth). Also, we used the iMap toolbox to analyze the raw data of participants' fixation on each pixel of the entire face. Results from both types of analyses strongly supported the hypothesis. When viewing target Chinese or Caucasian faces, Chinese participants spent a significantly greater proportion of fixation time on the eyes of other-race Caucasian faces than the eyes of own-race Chinese faces. In contrast, they spent a significantly greater proportion of fixation time on the nose and mouth of Chinese faces than the nose and mouth of Caucasian faces. This pattern of differential fixation, for own- and other-race eyes and nose in particular, was consistent even as participants became increasingly familiar with the target faces of both races. The results could not be explained by the perceptual salience of the Chinese nose or Caucasian eyes because these features were not differentially salient across the races. Our results are discussed in terms of the facial morphological differences between Chinese and Caucasian faces and the enculturation of mutual gaze norms in East Asian cultures.     

Breast cancer,lactation, and genetics

Abstract

A review of mortality rates from breast cancer in several nations indicates that most Caucasian populations have higher rates than do most non‐Caucasian. The only environmental factor shown to affect breast cancer rates consistently is parity, and its mechanisms of actuation are unknown. The higher risks of breast cancer among relatives of patients are reviewed, and a multifactorial genetic control is assumed in which the effects of genetic and environmental factors may be in part additive. While genetic effects are evident in both breast cancer and lactation, it is not clear whether they depend on two distinct sets of genetic factors or on a single set. Assuming that the higher frequencies of breast cancer in Caucasian populations are in some way associated with abnormal genetic factors in hypolactation, the hypothesis is suggested that their rate of elimination by natural selection might have become relaxed or diminished in remote prehistoric times only in Caucasian populations through their widespread development of domestic animal milk as an artificial infant food. Relaxed selection of genetic factors for hypolactation might have caused them to accumulate among Caucasian populations in sufficient frequencies to produce appreciably higher rates of breast cancer in these populations today, even where breast‐feeding is the rule.     

Early weaning among Japanese women in Hawaii

This study examined factors associated with early weaning among Japanese women in comparison with Caucasian women in Hawaii. A mailed survey was sent to all women who delivered an infant in Hawaii between January 1st 1989 and March 31st 1989. Only Japanese (N=228) and Caucasian women (N=439) were included in this study. All Japanese breast-feeding women in the study introduced formula at some point in time. Cox multivariate regression analysis was conducted in two separate models of Japanese and Caucasian women, respectively. Higher maternal age and working part-time among Japanese women, and multiparity, college education, rural island and long-term Hawaii residence among Caucasian women were protective against early weaning. Introduction of formula was strongly associated with early weaning for both groups, the association being stronger for Japanese women. The early practice of partial breast-feeding may play an important role for early weaning among Japanese women in Hawaii.     

Ethnic differences in in vitro glyceride synthesis in subcutaneous and omental adipose tissue

Considerable evidence suggests that there are ethnic differences in lipid metabolism between African American and Caucasian women, which may result in increased synthesis of fat in adipose tissue. The purpose of this study was to measure the in vitro rates of [14C]glucose incorporation into the glyceride-glycerol backbone of triglycerides (TG) and diglycerides (DG) in abdominal subcutaneous (SAT) and omental adipose tissue (OAT). Morbidly obese [African American (n = 15): body mass index (BMI) = 45 +/- 2.3; Caucasian (n = 18): BMI = 51 +/- 2.3] and preobese [African American (n = 7): BMI = 27 +/- 1.0; Caucasian (n = 7): BMI = 25 +/- 1.0] women were examined in this study. There were no significant differences in the rates of synthesis of either TG or DG in SAT of either preobese or obese women. On the other hand, both preobese and obese African American women had higher rates of synthesis of TG in OAT compared with their Caucasian counterparts. This increase in TG synthesis in OAT was not due to differences in cell size or rates of reesterification. Thus African American woman have an increased capacity to synthesize TG in OAT compared with Caucasian women, which may contribute to the higher prevalence of obesity in African American women.     

Novel alleles of 31-bp VNTR polymorphism in the human cystathionine β-synthase (<Emphasis Type="Italic">CBS</Emphasis>) gene were detected in healthy Asians

A 31-bp variable number of tandem repeats (VNTR) polymorphism of the cystathionine β-synthase (CBS) gene was earlier reported in Caucasians of predominantly European descent and Indo-Caucasoid populations.We report here for the first time, the detection of allele 20, which was absent in Caucasian and Indo-Caucasoid populations, as a common allele present in Singaporean Chinese (6.25%), Indians (11.7%), and Malays (11.5%). Hence, allele 20 might be a specific allele for Asian populations. A relatively common allele 19 found in the Caucasian and Indo-Caucasoid populations (10.4%–10.6%) was absent in the Asian samples of this study. Therefore, allele 19 might be a specific allele for the Caucasian populations. A novel and rare allele 13, which was not reported before in the Caucasian and Indo-Caucasoid populations, was found in 0.5% of Singaporean Chinese as genotype 13/17 heterozygotes. The presence of alleles 13 and 20 were verified by DNA sequencing. There were five new genotypes (13/17, 16/20, 17/20, 18/20 and 20/20) not reported before in the Caucasian and Indo-Caucasoid populations, detected in this study. Nine genotypes (15/18, 16/18, 16/21, 17/19, 18/19, 18/21, 19/19, 19/21 and 21/21) which were present in the Caucasian and/or Indo-Caucasoid populations were absent in this study. Our results showed that CBS 31-bp VNTR polymorphism has a distinct genetic difference in allele and genotype frequencies between the European Caucasians, Indo-Caucasoid and Asian populations.     

Glyoxalase I polymorphism and racial admixture in the Cuban population

Summary The polymorphism of glyoxalase I (GLO I) was demonstrated in the three main racial groups (Caucasian, Mulattoes, and Negroes) of the Cuban population. The GLO I gene frequencies were used to estimate the relative contribution of Negro and Caucasian genes to the genetic makeup of these three groups.Banco de Sangre Provincial     

Adaptive-compensatory responses in the adolescents belonging to indigenous northern ethnic groups in Irkutsk oblast

The pro- and antioxidant statuses of apparently healthy adolescent Tofalar and Evenks of both sexes has been estimated and compared to those of the newcomer Caucasian people. Both girls and boys display an activation of adaptive-compensatory response relative to Caucasian newcomers, which manifests itself as a statistically significant increase in nonenzymatic components of the antioxidant defense system.     

DNA polymorphisms and linkage disequilibrium in the angiotensinogen gene

A number of recent studies have implicated the angiotensinogen gene in the aetiology of essential hypertension in Caucasian, Japanese and African Caribbean subjects. We have genotyped 153 healthy white Caucasian subjects at a dinucleotide repeat polymorphism and seven diallelic sites in the coding or flanking regions of the angiotensinogen gene, including one polymorphism not previously studied. We have also documented patterns of linkage disequilibrium between polymorphisms. There is evidence of variation in the frequency of several mutations when compared with published results from other Caucasian control populations, possibly due to cryptic ethnic differences between these groups. This should be considered in the design and interpretation of studies of the angiotensinogen gene. Received: 10 November 1995 / Revised: 25 March 1996     

Cultural Diversity and Saccade Similarities: Culture Does Not Explain Saccade Latency Differences between Chinese and Caucasian Participants

A central claim of cultural neuroscience is that the culture to which an individual belongs plays a key role in shaping basic cognitive processes and behaviours, including eye movement behaviour. We previously reported a robust difference in saccade behaviour between Chinese and Caucasian participants; Chinese participants are much more likely to execute low latency express saccades, in circumstances in which these are normally discouraged. To assess the extent to which this is the product of culture we compared a group of 70 Chinese overseas students (whose primary cultural exposure was that of mainland China), a group of 45 participants whose parents were Chinese but who themselves were brought up in the UK (whose primary cultural exposure was western European) and a group of 70 Caucasian participants. Results from the Schwartz Value Survey confirmed that the UK-Chinese group were culturally similar to the Caucasian group. However, their patterns of saccade latency were identical to the mainland Chinese group, and different to the Caucasian group. We conclude that at least for the relatively simple reflexive saccade behaviour we have investigated, culture cannot explain the observed differences in behaviour.     

On the track of the bog people

The amount of radiographically detectable cortical bone, as determined by measurements of the second metacarpal, was evaluated in 42 male and 45 female Guamanian Chamorros and compared with the degree of bony demineralization in U.S. Caucasians participating in the Baltimore Longitudinal Study on Aging of the Gerontology Research Center. All Chamorros were individually matched to the Caucasian participants for age, sex, and menopause status. Chamorros of both sexes showed bilateral asymmetry in bone measurements and in the amount of cortical bone. Both Chamorro and Caucasian males had longer second metacarpals and more cortical bone than females. Caucasian males, however, had longer and larger second metacarpals than Chamorro males. Despite differences in the length and total width, Chamorro and Caucasian participants generally showed no significant differences in the amount of cortical bone or percent cortical area in the second metacarpal, suggesting that larger bones may not always indicate greater cortical mass. Although cross-sectional data suggested apparent age differences in the onset and rate of bone loss between Chamorros and Caucasians, the numbers of participants were too small to allow meaningful age-by-age statistical comparisons.