Background: Mitochondrial DNA (mtDNA) haplotypes have become popular tools for tracing maternal ancestry, and several companies offer this service to the general public. Numerous studies have demonstrated that human mtDNA haplotypes can be used with confidence to identify the continent where the haplotype originated. Ideally, mtDNA haplotypes could also be used to identify a particular country or ethnic group from which the maternal ancestor emanated. However, the geographic distribution of mtDNA haplotypes is greatly influenced by the movement of both individuals and population groups. Consequently, common mtDNA haplotypes are shared among multiple ethnic groups. We have studied the distribution of mtDNA haplotypes among West African ethnic groups to determine how often mtDNA haplotypes can be used to reconnect Americans of African descent to a country or ethnic group of a maternal African ancestor. The nucleotide sequence of the mtDNA hypervariable segment I (HVS-I) usually provides sufficient information to assign a particular mtDNA to the proper haplogroup, and it contains most of the variation that is available to distinguish a particular mtDNA haplotype from closely related haplotypes. In this study, samples of general AfricanAmerican and specific Gullah/Geechee HVS-I haplotypes were compared with two databases of HVS-I haplotypes from sub-Saharan Africa, and the incidence of perfect matches recorded for each sample.
Glomerular filtration rate (GFR), urine flow (UV), renal tubular transport maximum for glucose (TMG), and single nephron glomerular filtration rate (SNGFR), determined in anesthetized norepinephrine-infused trout (Salmo gairdneri), were 18.51 +/- 5.78 microliter x min-1 x kg body wt-1, 5.31 +/- 1.38 microliter x min-1 x kg body wt-1, 105.21 +/- 46.84 microgram x min-1 x kg body wt-1, and 3.74 +/- 1.12 nl/min, respectively, when in seawater (SW) and 140.39 +/- 17.24, 76.38 +/- 10.41, 626.16 +/- 77.46, and 1.31 +/- 0.20 in freshwater (FW). Angiotensin II infusions, to reduce UV, GFR, and TMG by 50%, had no effect on the average SNGFR of FW trout, but reduced that of SW fish to 1.42 +/- 0.19 nl/min. Infusions of 20% ferrocyanide, visualized as Prussian blue (PB), identified three glomerular populations: filtering (F) with PB in glomerular vessels and tubular lumen; nonfiltering (NF)--PB in glomerular vessels only; nonperfused (NP)--no PB associated with the nephron. SW and FW kidneys contained about 40% NF tubules. In FW, 45% were F tubules compared with 5% in SW, whereas NP tubules comprised 51% of SW tubules and 13% of FW. During angiotensin II infusions the distributions were 9% and 46% NF in FW and 6% F and 12% NF in SW trout.
Although there are numerous ethnic groups in Sierra Leone, the Mende and Temne together account for approximately 60% of the total population. To see if genetic differences could be observed among ethnic groups in Sierra Leone, the nucleotide sequence of the hypervariable 1 (HV1) region of mitochondrial DNA (mtDNA) was determined from samples of the two major ethnic groups, the Mende (n=59) and Temne (n=121), and of two minor ethnic groups, the Loko (n=29) and Limba (n=67). Among these 276 HV1 sequences, 164 individual haplotypes were observed. An analysis of molecular variance indicated that the distribution of these haplotypes within the Limba sample was significantly different from that of the other ethnic groups. No significant genetic variation was seen between the Mende, Temne, and Loko. These results indicate that distinguishing genetic differences can be observed among ethnic groups residing in historically close proximity to one another. Furthermore, we observed some mitochondrial DNA haplotypes that are common among the Sierra Leone ethnic groups but that have not been observed in other published studies of West African ethnic groups. Therefore, we may have evidence for mtDNA lineages that are unique to this region of West Africa.
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