mtDNA control-region sequence variation suggests multiple independent origins of an "Asian-specific" 9-bp deletion in sub-Saharan Africans.

The intergenic COII/tRNA(Lys) 9-bp deletion in human mtDNA, which is found at varying frequencies in Asia, Southeast Asia, Polynesia, and the New World, was also found in 81 of 919 sub-Saharan Africans. Using mtDNA control-region sequence data from a subset of 41 individuals with the deletion, we identified 22 unique mtDNA types associated with the deletion in Africa. A comparison of the unique mtDNA types from sub-Saharan Africans and Asians with the 9-bp deletion revealed that sub-Saharan Africans and Asians have sequence profiles that differ in the locations and frequencies of variant sites. Both phylogenetic and mismatch-distribution analysis suggest that 9-bp deletion arose independently in sub-Saharan Africa and Asia and that the deletion has arisen more than once in Africa. Within Africa, the deletion was not found among Khoisan peoples and was rare to absent in western and southwestern African populations, but it did occur in Pygmy and Negroid populations from central Africa and in Malawi and southern African Bantu-speakers. The distribution of the 9-bp deletion in Africa suggests that the deletion could have arisen in central Africa and was then introduced to southern Africa via the recent "Bantu expansion."     

Evidence for structural heterogeneity from molecular cytogenetic analysis of dicentric Robertsonian translocations.

Most Robertsonian translocations are dicentric, suggesting that the location of chromosomal breaks leading to their formation occur in the acrocentric short arm. Previous cytogenetic and molecular cytogenetic studies have shown that few Robertsonian translocations retain ribosomal genes or beta-satellite DNA. Breakpoints in satellite III DNA, specifically between two chromosome 14-specific subfamilies, pTRS-47 and pTRS-63, have been indicated for most of the dicentric 14q21q and 13q14q translocations that have been studied. We have analyzed the structure of 36 dicentric translocations, using several repetitive DNA probes that localize to the acrocentric short arm. The majority of the translocations retained satellite III DNA, while others proved variable in structure. Of 10 14q21q translocations analyzed, satellite III DNA was undetected in 1; 6 retained one satellite III DNA subfamily, pTRS-47; and 3 appeared to contain two 14-specific satellite III DNA sub-families, pTRS-47 and pTRS-63. In 10/11 translocations involving chromosome 15, the presence of satellite III DNA was observed. Our results show that various regions of the acrocentric short arm, and, particularly, satellite III DNA sequences, are involved in the formation of Robertsonian translocations.     

Mapping of Unconventional Myosins in Mouse and Human

Myosins are molecular motors that move along filamentous actin. Seven classes of myosin are expressed in vertebrates: conventional myosin, or myosin-II, as well as the 6 unconventional myosin classes -I, -V, -VI, -VII, -IX, and -X. We have mapped in mouse 22 probes encompassing all known unconventional myosins and, as a result, have identified 16 potential unconventional myosin genes. These genes include 7 myosins-I, 2 myosins-V, 1 myosin-VI, 3 myosins-VII, 2 myosins-IX, and 1 myosin-X. The map location of 5 of these genes was identified in human chromosomes by fluorescencein situhybridization.     

Normal and expanded Huntington's disease gene alleles produce distinguishable proteins due to translation across the CAG repeat.

BACKGROUND: An expanded CAG trinucleotide repeat is the genetic trigger of neuronal degeneration in Huntington's disease (HD), but its mode of action has yet to be discovered. The sequence of the HD gene places the CAG repeat near the 5' end in a region where it may be translated as a variable polyglutamine segment in the protein product, huntingtin. MATERIALS AND METHODS: Antisera directed at amino acid stretches predicted by the DNA sequence upstream and downstream of the CAG repeat were used in Western blot and immunohistochemical analyses to examine huntingtin expression from the normal and the HD allele in lymphoblastoid cells and postmortem brain tissue. RESULTS: CAG repeat segments of both normal and expanded HD alleles are indeed translated, as part of a discrete approximately 350-kD protein that is found primarily in the cytosol. The difference in the length of the N-terminal polyglutamine segment is sufficient to distinguish normal and HD huntingtin in a Western blot assay. CONCLUSIONS: The HD mutation does not eliminate expression of the HD gene but instead produces an altered protein with an expanded polyglutamine stretch near the N terminus. Thus, HD pathogenesis is probably triggered by an effect at the level of huntingtin protein.     

Trichloroethylene removal and oxidation toxicity mediated by toluene dioxygenase of Pseudomonas putida.

Whole cells of Pseudomonas putida containing toluene dioxygenase were able to remove all detectable trichloroethylene (TCE) from assay mixtures. The capacity of cells to remove TCE was 77 microM/mg of protein with an initial rate of removal of 5.2 nmol/min/ng of protein. TCE oxidation resulted in a decrease in the growth rate of cultures and caused rapid cell death. Addition of dithiothreitol to assay mixtures increased the TCE removal capacity of cells by up to 67% but did not prevent TCE-mediated cell death. TCE induced toluene degradation by whole cells to a rate approximately 40% of that induced by toluene itself.     

Effect of dietary lipid supplementation on progesterone concentration and reproductive performance in suckled beef cows

Using whole cottonseed as a lipid source, silage-based diets that were isocaloric and isonitrogenous yet varied in lipid level were fed to multiparous cows. In Experiment 1, 48 cows (n = 12 per treatment) were allotted to 1 of 4 treatments where diets were formulated to supply 3.9, 4.3, 5.3 and 6.3% of total lipid. In Experiment 2, 66 cows (n = 22 per treatment) were allotted to 1 of 3 treatments where diets were formulated to supply 3.1, 5.5 and 8.3% of total lipid. Length of the first ovarian cycle, length of the first normal estrous cycle, postpartum intervals to onset of ovarian luteal activity and to first estrus were not affected by diet (P>0.10) in either experiment. Mean progesterone (P(4)) concentrations for first normal estrous cycles were not different (P>0.10) in either experiment. Anestrous periods were divided into 3 phases for analyses: Phase I) parturition to onset of ovarian luteal activity, Phase II) first ovarian luteal activity and Phase III) first normal estrous cycle. No differences were observed in P(4) concentrations during any phase of the postpartum period. In conclusion, isocaloric and isonitrogenous diets with increasing levels of lipid had no effect on reproductive performance in suckled beef in these experiments.