Study of possible genetic predisposition to endemic goitre among the Fur and Baggara tribes of the Sudan

The overall prevalence rate of endemic goitre among the Fur and Baggara tribes of Western Sudan was found to be 74%. Family studies in 60 nuclear families showed a significantly higher incidence of endemic goitre among the offspring of affected parents than among the offspring of normal parents. This suggests a possible genetic predisposition to endemic goitre. The proportion of phenylthiocarbamide (PTC) non-tasters was found to be 13% among the goitrous subjects compared to 17.5% among the non-goitrous subjects. However, the association with PTC as well as with 6 blood-genetic markers, was not statistically significant.     

Some blood genetic characteristics of several Sudanese tribes

The distribution of ABO and Rhesus blood groups, serum haptoglobin, and transferrin; red cell glucose-6-phosphate dehydrogenase and acid phosphatase; and hemoglobin was studied among the two aboriginal negroid tribes (Nuba and Fur); the Nilotic tribe; five tribes of Arab ancestory; and a mixed group of other minor tribes of Arab origin. The Nilotic and Nuba tribes were genetically quite distinct from the rest, with lower R1, R2, and r in the Rhesus system and low HbS and Gd-. The Arab tribes had a genetic structure which was intermediate between that of the original negroid population of the Sudan and the Arabs to the north. However, some of the Arab tribes had special genetical characteristics, e.g., Messeria had high TfD1; both Messeria and Hawazma had high HbS and Gd-, while GdA was higher only in the Hawazma. The Gaalin had very low HbS, Ro, GdA, and Gd-, suggestive of less negroid admixture compared to Messeria and Hawazma. The Fur, though an aboriginal negroid tribe, had genetic characteristics similar to Arabs.     

Complement C3 polymorphism in sixteen populations of Colombia. Results of “Expedicion humana”

Blood samples of 1.022 individuals of both sexes, collected during the “Expedicion Humana” programme. Twelve Indian group, two Negroes, two urban and one mestizo populations of Colombia were C3 typed. The results showed the urban samples have C3*F genotype frequencies (17 and 20%) similar to the Spanish population. The Negroe system, with lower C3*F gene frequencies (3.5 and 7%) also resembled their parental populations in Africa. The Mestizo population reported in this study showed a lower value of the C3*F gene (2.2%) than previously studied. suggesting that the degree of admixture may vary in different regions of the country. As regards the Indian populations, there was a wide range of variation of the C3*F gene (0–19%) many tribes being monomorphic. This gene may be a marker of recent admixture in Amerindians, but there may be other genetic factors, such as selection and inbreeding in maintaining high levels of genetic polymorphism in tribes such as Guahibo.     

Genetic heterogeneity and population structure of Gond-related tribes in the Vidarbha region of Maharashtra.

Genetic heterogeneity in nine polymorphic loci is observed among Gond-related tribes in the Vidarbha region of Maharashtra. Pardhans, with their high ABO*A2 gene frequency (4.01%), low m gene frequency (57%), high P*1 gene frequency (42.7%), and high HbS trait (31.58%), differ significantly from other tribes. Per locus average heterozygosity among the studied tribes ranged from 36.24% to 40.37%, with Pardhans being more heterozygous. Analysis by FST and the empirical relationship between average allele frequencies and the ratio of within-gene to total gene diversity show that the tribes are isolated and that differentiation among them is at an early stage and approximately in conformity with expected differentiation under genetic drift. However, distances and principal components analysis reveal that Pardhans are far removed from the other tribes and from other central Dravidian tribes. Furthermore, of the various demographic parameters estimated, the high average heterozygosity in Pardhans is significantly correlated with mean marital distance (MMD), regression of MMD on wife's age, and effective population size. There is congruence between genetic and demographic data, showing that Pardhans are distinct. This conforms with Haimendorf's (1979) contention based on cultural traits that Pardhans are Gonds by historical accident and are later migrants to the Gond area from the north. The most significant and practical observation of the present study is that migration from an originally nontribal (Pardhan) to a tribal (Gond) area and admixture lead to severe disease course, differential selection pressure, and hence highly elevated HbS trait frequency.     

Genetic heterogeneity among the Negroid and Arab tribes of the Sudan

Genetic distance analysis was carried out among seven tribes of the Sudan comprising three Negroid (Nuba, Fur, and Nilotes) and four Arab tribes (Beja, Gaalin, Hawazma, and Messeria) on the basis of six polymorphic loci (ABO and Rhesus blood groups; haemoglobin and red cell glucose-6-phosphate dehydrogenase; serum haptoglobin and transferrin polymorphisms) controlling 21 alleles and compared with the Arab and Negroid populations in neighbouring countries. The Nuba and Nilotes have been found to have Negroid genetic characteristics, while the Fur are intermediate between the Arabs and Negroids. The Beja and Gaalin tribes have more pronounced Arab genetic characteristics than the Hawazma and Messeria, who have a great deal of Negroid admixture.     

Characterization of the Vibrio anguillarum fur gene: role in regulation of expression of the FatA outer membrane protein and catechols.

The chromosomally encoded Vibrio anguillarum fur gene was characterized. The amino acid sequence of the Fur protein showed a very high degree of homology with those of V. cholerae and V. vulnificus. The degree of homology was lower, although still high, with the Escherichia coli and Yersinia pestis Fur amino acid sequences, while the lowest degree of homology was found with the Pseudomonas aeruginosa Fur protein. The C-terminal portion of Fur is the least conserved region among these Fur proteins. Within this portion, two regions spanning amino acids 105 to 121 and 132 to the end are the least conserved. A certain degree of variation is also present in the N termini spanning amino acids 28 to 46. Regulation of expression of the V. anguillarum fur gene by iron was not detected by immunoblot analysis. Mutations in the cloned fur gene were generated either by site-directed mutagenesis (the Lys-77 was changed to a Gly to generate the derivative FurG77) or by insertion of a DNA fragment harboring the aph gene in the same position. FurG77 was impaired in its ability to regulate a reporter gene with the Fur box in its promoter, while the insertion mutant was completely inactive. V. anguillarum fur mutants were obtained by isolating manganese-resistant derivatives. In one of these mutants, which encoded a Fur protein with an apparent lower molecular weight, the regulation of the production of catechols and synthesis of the outer membrane protein FatA were partially lost. In the case of another mutant, no protein was detected by anti-Fur serum. This derivative showed a total lack of regulation of biosynthesis of catechols and FatA protein by iron.     

Genetic differences between Chibcha and Non-Chibcha speaking tribes based on mitochondrial DNA (mtDNA) haplogroups from 21 Amerindian tribes from Colombia

We analyzed the frequency of four mitochondrial DNA haplogroups in 424 individuals from 21 Colombian Amerindian tribes. Our results showed a high degree of mtDNA diversity and genetic heterogeneity. Frequencies of mtDNA haplogroups A and C were high in the majority of populations studied. The distribution of these four mtDNA haplogroups from Amerindian populations was different in the northern region of the country compared to those in the south. Haplogroup A was more frequently found among Amerindian tribes in northern Colombia, while haplogroup D was more frequent among tribes in the south. Haplogroups A, C and D have clinal tendencies in Colombia and South America in general. Populations belonging to the Chibcha linguistic family of Colombia and other countries nearby showed a strong genetic differentiation from the other populations tested, thus corroborating previous findings. Genetically, the Ingano, Paez and Guambiano populations are more closely related to other groups of south eastern Colombia, as also inferred from other genetic markers and from archeological data. Strong evidence for a correspondence between geographical and linguistic classification was found, and this is consistent with evidence that gene flow and the exchange of customs and knowledge and language elements between groups is facilitated by close proximity.     

Plasma cholinesterase studies on south-eastern Bantu of Mozambique.

Blood samples from four Bantu tribes in South-East Mozambique have been phenotyped for the plasma cholinesterase variants of the E1 locus. A control roup of 153 Portuguese residents in Mozambique have also been phenotyped. The frequencies of both the E1a and E1f genes in the Portuguese population is very similar to those in other Caucasian populations. The absence of the E1a gene in the four Bantu tribes provides more evidence of the rarity of this gene in Negroid populations. There is an increased frequency of E1f gene in all tribes as compared with previous surveys. The Ronga and Bitonga tribes have similar E1f frequencies of 0.047 and 0.048, respectively. The Shangana has an E1f frequency of 0.060, and the corresponding figure for the Chopi tribe is 0.089. The latter is the highest recorded frequency for this gene. The results give some support to the doubts concerning the affiliation of the Chopi tribe.     

Blood groups and ABH saliva secretion in Koya Dora and Konda Kammara tribes of Andhra Pradesh

The present paper reports the distribution of blood groups and ABH saliva secretion in two Andhra tribal populations: the Koya Dora and the Konda Kammara. 100 Koya Dora and nearly 110 Konda Kammara adults of both sexes were tested for A1A2BO, MN, Rh (CcDEe) blood groups and ABH saliva secretion. The gene frequencies for A1A2BO, MN and ABH and the gene as well as chromosome frequencies for Rh (CcDEe) systems were calculated. Koya Doras show a higher incidence of A gene than B gene, while the reverse trend is seen in Konda Kammaras. Both the tribes show a high M gene frequency. No Rh(D) negative individual was found in Koya Doras, while 4.59% of Konda Kammaras are Rh(D) negative. The chromosomes CDE, CdE, cDe, cdE, Cde and cde are absent in Koya Doras, while only the four chromosomes CDE, CdE, cDe and cdE are absent in Konda Kammaras. The chromosome CDe shows the highest frequency in both the tribes. The frequency of secretors is, as usual, higher than that of nonsecretors in both the tribes. The intergroup variation between the two tribes is not statistically significant for MN, Rh (CcDEe) and ABH systems, while the difference is significant for the A1A2BO blood groups. Suitable comparisons have also been made with all the other available data from Andhra Pradesh tribal populations with respect to different systems studied. Finally Fi estimates have been calculated after Harpending et al. (1973) and Workman et al. (1974) for Koya Doras and Konda Kammaras to assess their degree of endogamy, considering the codominant systems studied, which suggest that Koya Doras are relatively more isolated than Konda Kammaras.     

Members of the Fur protein family regulate iron and zinc transport in E. coli and characteristics of the Fur-regulated fhuF protein

The regulator Fur represses with Fe2+ as cofactor iron uptake genes. The fhuF gene reacts very sensitive to minor changes of Fe2+ and Fur. It is assumed that FhuF helps in the mobilisation of iron out of the hydroxamate siderophores transported into the cell. Analysis of the protein revealed an unusual [2Fe-2S] cluster bound to a Cys-Cys-X10-Cys-X2-Cys motif in FhuF. suf genes responsible for the synthesis of the iron sulfur center were identified. The Zur protein shows 27% identity to the Fur protein of E. coli. It regulates as a repressor the high affinity uptake system znuACB. Only two additional Zur binding sites in the promoter region of genes with unknown function were found. Properties of Zur and Fur proteins from different bacteria are compared.     

Some blood genetic markers of the Nuba and Hawazma tribes of western Sudan

Two hundred eighty subjects comprising 112 Nuba and 168 Hawazma of the Sudan were tested for the distribution of hemoglobins, eight red cell enzymes, and four serum proteins. The Nuba, the indigenous negroid tribe, had no HbS, HbO-Arab, or GdB(Khartoum) compared to the Hawazma tribe of Negro-Arab descent. The gene frequencies of the above polymorphic systems in the latter were as follows: HbS, 0.13; HbO-Arab, 0.01; GdB(Khartoum), 0.03. The frequency of GdA was higher in the Hawazma than in the Nuba. A high frequency of glucose 6-phosphate dehydrogenase (G6PD) deficiency and HpO was present in both the tribes. Essentially similar gene frequencies of Hp1, TfD, PGDC, pC, and PGM1 were observed in both Nuba and Hawazma. The average heterozygosity at five polymorphic loci was the same (0.23) in both the tribes. The above results agree with the social practice whereby people of mixed Hawazma and Nuba descent are considered members of the Hawazma tribe and confirm that racial admixture between the two groups can be seen as a process of gene flow from the Nuba to the Hawazma, even though the Nuba are the indigenous group, while the Hawazma are the new settlers.     

Cloning and characterization of the fur gene from Moraxella bovis

A homologue of the ferric uptake regulator gene (fur) was isolated from Moraxella bovis by degenerate polymerase chain reaction and cloning. Fur protein of M. bovis exhibited 72.1% amino acid identity with Acinetobacter calcoaceticus Fur. Western blot analysis showed a decrease of Fur expression in response to sufficient-iron conditions compared with deficient-iron conditions. An electrophoretic mobility-shift assay indicated that Fur protein binds to DNA fragments containing a putative Fur-box derived from the upstream region of the M. bovis fur gene. Fur of M. bovis may regulate the expression of iron transport systems in response to iron limitation in the environment.     

Genetic studies among the sedentes and migrant Oraons of eastern India

A total of 334 Oraons of both sexes from two localities in eastern India were tested for 11 polymorphic and six monomorphic blood genetic markers. The sample comprised 130 sedentes from the Gumla district in Bihar and 204 migrants to the Jalpaiguri district of North Bengal. At the hemoglobin locus one example of HbAS was observed in the Gumla sample, while two cases of HbAS were found in the Jalpaiguri group. The Oraons are a distinct tribe and are characterized by a very low frequency of Hp1, TFC2, and a high frequency of TfD1 and GcIF at the serum protein loci. In the red cell enzyme systems the Oraons have a higher frequency of pa at the acid phosphatase locus and GLO1 at the Glyoxalase I locus. Absence of red cell lactate dehydrogenase and very low HbS and GdB- is also characteristic of the Oraons. A probable new nondeficient slow variant of Gd has been observed in polymorphic frequency in the Oraons of Gumla. There was an excess of homozygotes at the Gc locus. No significant difference in the gene frequency between the two groups of Oraons was observed at any of the loci. Genetic distance estimates using the gene frequency data indicate that the Oraons of the two localities are genetically homogeneous and form one cluster with the Bhils. They are nearer to the Irula and Kurumba tribes of the Nilgiris rather than the other Dravidian tribes, Tamils, or Nayars.     

Sickle cell disease among tribes of Andhra Pradesh and Orissa,India

Sickle cell disease is observed to occur in significantly high frequencies amongst the tribes of India. It has surged to the fore as an important public health problem among tribal groups, which needs serious attention. This paper presents the distribution of this abnormal genetic problem among scheduled tribes of India, in general and among those of Andhra Pradesh and Orissa states, in detail. Though the prevalence of sickle cell trait is high, the sickle cell disease cases are found to be very low, since all these surveys are made among adults. Most of the sickle cell disease cases might have expired during their early states. Hence, it is attempted to estimate the expected frequencies of disease cases from HbS gene frequencies. Estimations were also made by considering higher levels of inbreeding among these populations.     

Characterization of the bacterial flora of Sudanese sorghum flour and sorghum sourdough

The microflora of a Sudanese sorghum flour, a spontaneously fermented sourdough and along-term sourdough produced in a Sudanese household by consecutive re-inoculations, wasstudied. The dominant contaminants of sorghum flour were Gram-negative, catalase-positive,rod-shaped bacteria with counts of about 10⁵ cfu g⁻¹. Thespontaneously fermented sorghum sourdough showed a bacterial succession from Gram-negative,catalase-positive contaminants to Enterococcus faecalis , Lactococcus lactis , Lactobacillus fermentum and Lact. reuteri . The total bacterial countreached about10¹⁰ cfu g⁻¹ and the pH dropped from6·4 to 3·35 in about 42 h. In this phase, only the latter two species remaineddominant in a ratio of 1:1. From the Sudanese long-term dough, seven strains of Lactobacillus were isolated, representing the dominant flora. Sequence comparison ofpartial 16S rRNA gene sequences were used to clarify their phylogenetic positions. Five strainswere classified as Lact.vaginalis and could be regarded as heterogenous biovars of thisspecies. The other two strains could be assigned to Lact. helveticus .RAPD-PCR and sugar fermentation patterns were useful in differentiation of these strains.     

Genogeographic analysis of a subdivided population. II. Geography of random inbreeding (from frequency of surnames in Adygs)

An important characteristic of the genetic structure of populations, random inbreeding (interpopulation variation), was evaluated on the basis of quasi-genetic markers (surnames). The following methodological issues are considered: estimation of random inbreeding using the coefficient of isonymy fr in a subdivided population; a comparison of inbreeding levels calculated on the basis of surname frequencies using fr and Wright's FST; a comparison of inbreeding estimates obtained on the basis of surnames and genetic markers; inbreeding variation in populations of the same hierarchical rank; and planning of genetic studies of a subdivided population. The population of Adygs (an indigenous ethnic group of Northern Caucasus) was examined as a model subdivided population. The population system of Adygs is hierarchical. Parameters of random inbreeding were examined at each level of the system "ethnic group==>tribe==>geographic group of auls==>aul." Frequencies of surnames were collected subtotally. Data on frequencies of 1340 surnames in 61 auls representing all Adyg tribes were analyzed. In total, 60,000 people were examined. The inbreeding estimates obtained on the basis of Wright's FST and the coefficient of isonymy fr virtually coincided: for Adygs in general, FST x 10(2) = 2.13 and fr x 10(2) = 2.09. At the same time, the inbreeding level exhibited marked differences among tribes: in Shapsugs, these differences were an order of magnitude higher than in Kabardins (fr x 10(2) = 2.53 and 0.25, respectively). The inbreeding estimates for auls differed by two orders of magnitudes: fr x 10(2) = 0.07 and fr x 10(2) = 7.88. An analysis of ten auls yielded fully coinciding inbreeding estimates based on quasi-genetic (fr x 10(2) = 0.60) and classical (FST x 10(2) = 0.69) gene markers. Computer maps of surname distributions in Adygs (1340 maps) were constructed for the first time ever. Based on these maps, the map of random inbreeding in the Adyg population was obtained.     

Inbreeding reveals interpopulation differences in inversion polymorphism of Drosophila subobscura

The adaptive significance of inversion polymorphism of Drosophila subobscura is well established. However, little is known about gene combinations within inversions which are coadapted because of population-specific effects. We studied this aspect of Dobzhansky's coadaptation hypothesis, using the systematic inbreeding method. Differences in magnitude and quality of inversion polymorphism in two ecologically and topologically distinct habitats were compared after several generations of continuous full-sib inbreeding. Populations from the two habitats differ in frequency of homokaryotypes after third and fifth generation of inbreeding and in the levels of homozygosity of different gene arrangements. The effect of homozygosity appears population and chromosome specific.