Genetics and Phenogenetics of Mitochondria

Wagner, Robert P.

doi:10.1126/science.163.3871.1026

Cited by 68 publications

(8 citation statements)

References 45 publications

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“…Finally, insufficient attention to the genetic com-'Supported in part by DeKalb AgResemh, Inc. position of individuals serving as sources of mitochondria may lead to results which are at times confusing and essentially unrepeatable. The wide functismal and structural dissimilarity even within the same species has been discussed recently (12,13). Certainly this fact should be considered very strongly when activities of mitochondria are studied.…”

Section: Idrodnetionmentioning

confidence: 97%

High efficiency of oxidative phosphorylation in mitochondria of wheat

Sarkissian¹,

Srivastava²

1970

Can. J. Biochem.

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efliciency of oxidative phosphoryIation in mitochondria of wheat. Can. J. Biochern. 48,692-698 (1976).Mitochondria of young seedlings of a wheat hybrid 38 MS x 28 exhibited high efficiency of oxidative phosphorylation. The ADP:O ratios estimated polarographical8y approached or were equivalent to 6, 4, and 5 with a-ketoglutarate, succinate, and malate, respectively. The respiratory control vaiues with these substrates were about '7.5, 4.5, and 2.9. When assayed manometrically, the P:O ratios with a-ketoglutarate as substrate and 18 min of reaction time were between 5.4 and 5.8. ABP was utilized almost exclusively in oxidative phosphorylation; microbial contamination in ghosphorylating reaction mixtures had no measurable effect an oxidative phosphorylation. A concentration of 1.7 x 10-' M 2,4-dinitrophenol had no appreciable effect on stimulation of respiration by ADP. ATPase activity was increased a b u t 13 % by dinitrophenol. It appears that high efficiency of oxidative phosphorylation is a true characteristic of the mitochondria used in this study.

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Section: Idrodnetionmentioning

confidence: 97%

High efficiency of oxidative phosphorylation in mitochondria of wheat

Sarkissian¹,

Srivastava²

1970

Can. J. Biochem.

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“…This DNA is completely nuclear in origin, as the cytoplasm is extruded from the germ cells during maturation (13) and the mitochondria, with their associated DNA (14), only occur in the sperm mid piece (15), which is removed during purification of the sperm heads. Table 2 shows that when the amount of purified DNA used for LSC is converted to "sperm head equivalents" (16) (19)(20)(21).…”

Section: A056mentioning

confidence: 99%

Unscheduled DNA Synthesis in the Germ Cells of Male Mice Exposed In Vivo to the Chemical Mutagen Ethyl Methanesulfonate

Sega

1974

Proc. Natl. Acad. Sci. U.S.A.

110

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An unscheduled DNA synthesis has been clearly demonstrated in meiotic and postmeiotic germ cell stages of the male mouse after in vivo treatment with a 250 mg/kg dose of ethyl methanesulfonate. The germ cell stages showing unscheduled DNA synthesis range from early to middle meiotic prophase stages through early to middle spermatid stages. The initiation of this synthesis, taken to be repair of chemically damaged DNA in these germ cells, is rapid, beginning within 1 hour after the injection of ethyl methanesulfonate. Unscheduled DNA synthesis has not been detected in the most mature germ cell stages, which give rise to dominant lethal mutations, nor does it occur in germ cell stages where protamine has replaced the chromosomal histones.In the study ofchemical mutagenesis in a mammalian testsystem it is of great interest to know if the germ cells are capable of repairing damaged DNA (as well as other molecular targets), and the relationship between such a repair system, if it does exist, and the genetic consequences of such repair. Studies have been performed with a limited number of mammalian cell types (not including germ cells), which demonstrated repair of chemically damaged DNA. See, for example (1-4). However, in vivo repair of germ cell DNA after treatment with chemical agents has not been studied.It is possible to study DNA repair in meiotic and postmeiotic germ cells of male mice by making use of the wellstudied sequence of events that occurs during spermatogenesis and spermiogenesis (5-7). In developing male germ cells the last DNA synthesis takes place during a 14-hr period (7) in preleptotene spermatocytes. After DNA synthesis these spermatocytes continue to develop through a series of germ cell stages for about a 28-30 day period (5, 6) before the spermatids finally leave the testes and enter the caput epididymides. Two to three days later, the developing sperm reach the caudal epididymides, and, in two or three days more, they enter the vasa deferentia. If Recovery of Sperm Heads and DNA. At various times after treatment the animals were killed and the reproductive tracts were sectioned into three parts: the caput epididymides, the caudal epididymides, and the vasa deferentia (refer to Fig. 1). After pooling of the tissues from each region, the sperm heads were recovered by procedures already described (8).

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“…The notion that mitochondria evolved from endosymbiotic procaryotes has received much attention (15,20,27). The comparison of E. coli tRNATY' and soybean mitochondrial tRNATYr (Fig.…”

Section: Discussionmentioning

confidence: 99%

Mitochondrial Tyrosyl Transfer Ribonucleic Acid in Soybean Seedlings

Meng

Vanderhoef

1972

Plant Physiol.

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Soybean seedlings were examined for the presence of mitochondrial tRNA. Tyrosyl transfer tRNAs from whole cells, from a well characterized mitochondrial preparation, and from a snake venom phosphodiesterase-treated mitochondrial preparation, were compared by reverse phase chromatography. It was concluded that none of the three previously reported tRNATYr species were mitochondrial. Rather, a fourth tRNATYr species, eluting somewhat later, was of mitochondrial origin. Mitochondrial tRNATYr was chromatographically similar to Escherichia coli tRNATYr.Transfer RNA and tRNA synthetases have previously been purified from mitochondria. Barnett and his colleagues (2, 3) pioneered in this area when their studies of species specificity in the aminoacyl transfer reaction led to the discovery of the localization of certain tRNAs and their synthetases in Neurospora crassa mitochondria (4)(5)(6)(7)(8)(12)(13)(14). Mitochondrial tRNA and/or synthetases have also been discovered in yeast (1,10,11,18,21,29), Tetrahymena (22,23), and rat liver (9, 21).Suyama reported that "a large portion of mitochondrial sRNA is not transcribed from mitochondria DNA" in Tetrahymena; it is clear, however, that mitochondrial DNA does transcribe tRNAL"U and tRNAFM-t in yeast (I 1, 18 were discarded, and the remainder of the seedling was stored in ice-cold 1 % sucrose for not longer than 2 hr before use for extraction of tRNA, enzymes, or mitochondria.Extraction of Mitochondria. A modified method of Flowers and Hanson (16) was used. Tissue was diced with razor blades in 1.5 vol homogenization medium (0.4 M sucrose, 50 mM KH2PO4, 5 mM Na2EDTA, adjusted to pH 7.6 with crystalline tris). A PT1O-35 Polytron homogenizer (generator PT20/ST, setting 3) was used to further disrupt the cells. The homogenate was filtered through four layers of cheesecloth, then centrifuged 10 min at 1,000g. The supernatant fluid was recentrifuged 7 min at 31,000g. The resulting pellet was suspended in 0.4 M sucrose and centrifuged 10 min at 1,000g. The supernatant fluid was saved, the pellet resuspended in 0.4 M sucrose, centrifuged 10 min at 1,OOOg, and that supernatant fluid combined with the first. The combined supernatant fluids were underlaid with 0.6 M sucrose in a centrifuge tube and centrifuged 25 min at 10,000g. The supernatant fluid was discarded and the mitochondria-rich pellet was immediately quick-frozen at -80 C and stored at -20 C for future tRNA extraction.

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Genetics and Phenogenetics of Mitochondria

Cited by 68 publications

References 45 publications

High efficiency of oxidative phosphorylation in mitochondria of wheat

High efficiency of oxidative phosphorylation in mitochondria of wheat

Unscheduled DNA Synthesis in the Germ Cells of Male Mice Exposed In Vivo to the Chemical Mutagen Ethyl Methanesulfonate

Mitochondrial Tyrosyl Transfer Ribonucleic Acid in Soybean Seedlings

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