Possible relationship between conditions associated with chronic hypoxia and brain mitochondrial DNA deletions.

The brain relies heavily on aerobic metabolism which requires functional mitochondria. Mitochondria are subcellular organelles with their own genome which codes for 13 essential protein subunits. By employing PCR assays to examine brain tissue from 43 age-comparable individuals (between ages 34 and 73), we found a correlation between mitochondrial DNA deletion mutations, mtDNA4977 deletions, and conditions associated with chronic hypoxia. In prior studies, utilizing only 6 to 12 clinical samples, mtDNA4977 deletions were reported to increase in specific regions of the brain with aging. However, we found 12-fold and 5-fold higher levels of mtDNA4977 deletions in the putamen and the superior frontal gyrus of the cortex, respectively, from individuals who had conditions associated with chronic hypoxia when compared with individuals without evidence of such conditions. These findings suggest that chronic hypoxia should be more closely examined in the pathophysiology of central nervous system diseases.

Allelopathic potential ofIpomoea tricolor (Convolvulaceae) in a greenhouse experiment.

The allelopathic potential ofIpomoea tricolor, a plant used in Mexican agriculture to control weeds, and tricolorin A, the major phytogrowth inhibitor present in the so-called "resin glycosides" of this plant, have been evaluated by testing leachates of the plant and the compound on the germination and radicle growth ofAmaranthus hypochondriacus, Echinochloa crusgalli, Senna uniflora, I. tricolor, andI. purpurea. The allelopathic potential ofI. tricolor was evaluated in a greenhouse experiment with dryI. tricolor mixed with sterile and nonsterile soil in pots.A. hypochondriacus was sown in pots containingI. tricolor, 2-chloro-4-(ethylamino)-6-(isopropylamino)-1,3,5 triazine (Gesaprim) or 1-glyphosphate, and the glyphosphate salt of isopropylamine (Faena), two different commercial herbicides used as a comparison toI. tricolor. Number and dry weights of different monocotyledonous and dicotyledonous weeds andA. hypochondriacus growing in the different treatments were measured.Ipomoea and Faena herbicide had a similar inhibitory effect on monocots.

Genetic analysis of temperature-sensitive mutants which define the genes for the major herpes simplex virus type 2 DNA-binding protein and a new late function.

Eleven temperature-sensitive mutants of herpes simplex virus type 2 (HSV-2) exhibit overlapping patterns of complementation that define four functional groups. Recombination tests confirmed the assignment of mutants to complementation groups 1 through 4 and permitted the four groups to be ordered in an unambiguous linear array. Combined recombination and marker rescue tests (A. E. Spang, P. J. Godowski, and D. M. Knipe, J. Virol. 45:332-342, 1983) indicate that the mutations lie in a tight cluster near the center of UL to the left of the gene for DNA polymerase in the order 4-3-2-1-polymerase. The seven mutants that make up groups 1 and 2 fail to complement each other and mutants in HSV-1 complementation group 1-1, the group thought to define the structural gene for the major HSV-1 DNA-binding protein with a molecular weight of 130,000. At 38 degrees C, mutants in groups 1 and 2 synthesize little or no viral DNA, and unlike cells infected with the wild-type virus, mutant-infected cells exhibit no detectable nuclear antigen reactive with monoclonal or polypeptide-specific antibody to the major HSV-2 DNA-binding protein. The four mutants that make up groups 3 and 4 do not complement each other, nor do they complement mutants in group 2. They do, however, complement mutants in group 1 as well as representative mutants of HSV-1 complementation group 1-1. At 38 degrees C, mutants in groups 3 and 4 are phenotypically DNA+, and nuclei of mutant-infected cells contain the HSV-2 DNA-binding protein. Thus, the four functional groups appear to define two closely linked genes, one encoding an early viral function affecting both viral DNA synthesis and expression of the DNA-binding protein with a molecular weight of 130,000 (groups 1 and 2), and the other encoding a previously unidentified late viral function (groups 3 and 4). The former gene presumably represents the structural gene for the major HSV-2 DNA-binding protein.

Genetic analysis of temperature-sensitive mutants which define the gene for the major herpes simplex virus type 1 DNA-binding protein.

We have assigned eight temperature-sensitive mutants of herpes simplex virus type 1 to complementation group 1-1. Members of this group fail to complement mutants in herpes simplex virus type 2 complementation group 2-2. The mutation of one member of group 1-1, tsHA1 of strain mP, has been shown to map in or near the sequence which encodes the major herpes simplex virus type 1 DNA-binding protein (Conley et al., J. Virol. 37:191-206, 1981). The mutations of five other members of group 1-1 map in or near the sequence in which the tsHA1 mutation maps, a sequence which lies near the center of UL between the genes for the viral DNA polymerase and viral glycoprotein gAgB. These mutants can be divided into two groups; the mutations of one group map between coordinates 0.385 and 0.398, and the mutations of the other group map between coordinates 0.398 and 0.413. At the nonpermissive temperature mutants in group 1-1 are viral DNA negative, and mutant-infected cells fail to react with monoclonal antibody to the 130,000-dalton DNA-binding protein. Taken together, these data indicate that mutants in complementation groups 1-1 and 2-2 define the gene for the major herpes simplex virus DNA-binding protein, an early gene product required for viral DNA synthesis.

Transfer of the herpes simplex thymidine kinase gene from human cells to mouse cells by means of metaphase chromosomes.

Thymidine kinase (TK)-deficient human cells were infected with ultraviolet light-inactivated Herpes simplex virus type 1, and "transformed" cells that expressed Herpes TK activity were isolated. Purified metaphase chromosomes were isolated from the transformed human line and incubated with TK-deficient mouse cells. TK+ cells were selected, and it was shown that these cells were gene transferents which expressed Herpes TK activity, identical to that found in the transformed human cells. The gene transferents contained no intact human chromosomes. When removed from selective pressure, the gene transferents rapidly lost the TK+ phenotype. However, upon continued growth in nonselective medium, a subpopulation in which the TK+ phenotype had become more stabilized appeared. These results suggest that the Herpes gene for thymidine kinase has integrated into the genome of the HSV-transformed human cells and that it can be transferred to other cells by means of purified metaphase chromosomes.