TfmLac: a second isolation of testicular feminization in mice.

TfmLac, a new occurrence of the X-linked mutation testicular feminization, has been isolated in a stock of mice and mapped to the same region as the original TfmH mutation. We compared these two mutants to determine if there are differences in their putative residual androgen receptors or androgen responsiveness. Such differences have been reported for Tfm mutations in humans.

Specific translational activation by nuclear gene products occurs in the 5' untranslated leader of a yeast mitochondrial mRNA.

Translation of the yeast mitochondrial mRNA encoding cytochrome c oxidase subunit III (coxIII) is specifically activated by the products of at least three nuclear genes, PET494, PET54, and PET122. To investigate whether the target site for translational activation is within the 5' untranslated leader of the coxIII mRNA, we asked whether translation of another mitochondrial protein, apo-cytochrome b, from a chimeric mRNA bearing the coxIII mRNA leader required PET494, PET54, or PET122. Mutations in any of these three genes abolished translation of cytochrome b from an mRNA bearing the 5' two-thirds of the coxIII mRNA 5' untranslated leader, showing that all three gene products are required for translation of the chimeric mRNA and must act within the 5' two-thirds of the coxIII mRNA leader.

Activities of isolated mitochondria and mitochondrial enzymes from aerobically and anaerobically germinated barnyard grass (echinochloa) seedlings.

Activity of mitochondria isolated from whole seedlings of Echinochloa crus-galli (L.) Beauv. var oryzicola germinated under aerobic and anaerobic conditions for 5 to 7 days was investigated.

Studies on the role of catecholamines in the regulation of the developmental pattern of hypothalamic aromatase.

Experiments were conducted to study the regulation of the developmental pattern of aromatase in the forebrain of the perinatal rat. Two experimental designs were used: aromatase measured in primary cultures of fetal hypothalamic cells and in cell-free preparations of forebrain tissue excised at varying ages. In cultured cells, aromatase decreased logarithmically at a slow rate (t1/2 = 7.

Saccharomyces cerevisiae positive regulatory gene PET111 encodes a mitochondrial protein that is translated from an mRNA with a long 5' leader.

The yeast nuclear gene PET111 is required specifically for translation of the mitochondrion-coded mRNA for cytochrome c oxidase subunit II. We have determined the nucleotide sequence of a 3-kilobase segment of DNA that carries PET111. The sequence contains a single long open reading frame that predicts a basic protein of 718 amino acids.

Nuclear Overhauser effect studies of the conformations of MgATP bound to the active and secondary sites of muscle pyruvate kinase.

MgATP binds both at the active site (site 1) and at a secondary site (site 2) on each monomer of muscle pyruvate kinase as previously found by binding studies and by X-ray analysis. Interproton distances on MgATP bound at each site have been measured by the time-dependent nuclear Overhauser effect in the absence and presence of phosphoenolpyruvate (P-enolpyruvate), which blocks ATP binding at site 1. Interproton distances at site 2 are consistent with a single conformation of bound ATP with a high antiglycosidic torsional angle (chi = 68 +/- 10 degrees) and a C3'-endo ribose pucker (delta = 90 +/- 10 degrees).

Research strategy in industrial toxicology.

While much of industrial toxicology is observational in character, pursuit of specific research is needed to facilitate the overall evaluation of potential toxicity for man. Two such areas are the application of physiologic pharmacokinetic models to inter-species extrapolation of toxic effects and an understanding of the role of cellular oncogenes in the process of spontaneous tumor formation in animals. A physiologic pharmacokinetic model was developed for methylene chloride (MeCl2) which describes the fate of MeCl2 and its metabolic products in numerous species including the mouse, rat, hamster and man.

PET111, a Saccharomyces cerevisiae nuclear gene required for translation of the mitochondrial mRNA encoding cytochrome c oxidase subunit II.

Mutations in the nuclear gene PET111 are recessive and specifically block accumulation of cytochrome c oxidase subunit II (coxII), the product of a mitochondrial gene. However, the coxII mRNA is present in pet111 mutants at a level approximately one-third that of wild type. The simplest explanation for this phenotype is that PET111 is required for translation of the coxII mRNA.

Activation of a cellular proto-oncogene in spontaneous liver tumor tissue of the B6C3F1 mouse.

The controversy surrounding the interpretation of observed increases in the high spontaneous liver tumor incidence of the B6C3F1 mouse after administration of certain chemical agents necessitates a mechanistic understanding into the nature of tumor development in this particular strain of mouse. Recently, cancer genes (oncogenes) have been detected in the DNA from a variety of human tumors and tumor cell lines. These genes have been implicated to play a role in the transformation of normal cells into cancerous ones.

The yeast nuclear gene CBS1 is required for translation of mitochondrial mRNAs bearing the cob 5' untranslated leader.

Mitochondrial translation of the cob mRNA to yield apocytochrome b is specifically dependent on the nuclear gene CBS1, while mitochondrial translation of the oxi2 mRNA to yield cytochrome oxidase subunit III (cox III) is specifically dependent on the nuclear gene PET494. Chimeric oxi2 mRNAs bearing the 5' leaders of other mitochondrial mRNAs, transcribed from rho- mitochondrial DNAs termed MSU494, are translated in pet494 mutants. In this study, we examined translation of coxIII from MSU494-encoded chimeric mRNAs in zygotes of defined nuclear and mitochondrial genotype.

At least two nuclear gene products are specifically required for translation of a single yeast mitochondrial mRNA.

Mitochondrial translation of the oxi2 mRNA, encoding yeast cytochrome c oxidase subunit III (coxIII), has previously been shown to specifically require the mitochondrially located protein product of the nuclear gene PET494. We show here that this specific translational activation involves at least one other newly identified gene termed PET54. Mutations in PET54 cause an absence of the coxIII protein despite the presence of normal levels of its mRNA.

Differences in the androgen response between two mouse species.

Renal weight and beta-glucuronidase activity are two of several well-characterized androgen-responsive parameters in Mus musculus. A similar sexual dimorphism was not reported for a second mouse species, Mus caroli, however. Since this was not associated with a general absence of androgen action, we considered whether a localized defect in androgen receptors or a difference in renal androgen-responsive endpoints in the two species existed.

Growth hormone-secretory patterns in androgen-resistant (testicular feminized) rats.

To investigate the role of androgen receptors in the expression of the male GH-secretory pattern in adult rats, the GH-secretory patterns in androgen-resistant (testicular feminized) rats were compared with their normal male and female littermates. All animals were prepared with intraatrial Silastic catheters and bled every 15 min for 8 h (0800-1600 h). Normal male littermates displayed a characteristic low frequency, high amplitude pattern of GH secretion with bursts of GH occurring every 2.

Mitochondrial genome rearrangement leads to extension and relocation of the cytochrome c oxidase subunit I gene in sorghum.

The mitochondrial gene (COXI) encoding cytochrome c oxidase subunit I (COI) was isolated from two cytoplasmic genotypes of sorghum that synthesize different COI polypeptides. The Milo COI (Mr approximately 38,000) is encoded by a 530 codon structural gene sharing 98% homology with the corresponding maize gene. A variant COI observed in 9E cytoplasm (Mr approximately 42,000) is encoded by a 631 codon structural gene that diverges completely from the Milo COXI gene both 100 bp 5' to the presumed initiator methionine and within the 3' coding sequence.

Product of Saccharomyces cerevisiae nuclear gene PET494 activates translation of a specific mitochondrial mRNA.

The product of Saccharomyces cerevisiae nuclear gene PET494 is known to be required for a posttranscriptional step in the accumulation of one mitochondrial gene product, subunit III of cytochrome c oxidase (coxIII). Here we show that the PET494 protein probably acts in mitochondria by demonstrating that both a PET494-beta-galactosidase fusion protein and unmodified PET494 are specifically associated with mitochondria. To define the PET494 site of action, we isolated mutations that suppress a pet494 deletion.

Estrogen binding in nuclear and cytosolic extracts from brain and pituitary of middle-aged female rats.

Estrogen binding was compared in brain and pituitary of long-term ovariectomized young and middle-aged (MA) female rats. Binding was quantified in both cytosolic and nuclear extracts to ascertain whether fractions of estrogen binding are altered in MA females. Estrogen binding detected in nuclear extracts from hypothalamus/preoptic area and anterior pituitary of MA females was significantly lower than levels detected in young females.

Developmental Changes in Photosynthetic Gas Exchange in the Polyol-Synthesizing Species, Apium graveolens L. (Celery).

Developmental changes in photosynthetic gas exchange were investigated in the mannitol synthesizing plant celery (Apium graveolens L. ;Giant Pascal'). Greenhouse-grown plants had unusually high photosynthetic rates for a C(3) plant, but consistent with field productivity data reported elsewhere for this plant.

Localization of aromatase and 5 alpha-reductase to neuronal and non-neuronal cells in the fetal rat hypothalamus.

Experiments were designed to identify the neural cell type(s) responsible for the aromatization and 5 alpha-reduction of androgens in the rat hypothalamus. Primary cultures of fetal rat hypothalamic cells, which had enhanced neuronal morphology, were treated at various times after plating with kainic acid (KA), a neurotoxic agent which selectively destroys neuronal cells. Neuronal morphology was disrupted in a time (0-6 days)- and dose (10(-4)-10(-2) M)-dependent fashion after KA treatment, with no apparent change in the appearance of the flattened, underlying non-neuronal cells.

Enumeration of total bacteria and coliforms in milk by dry rehydratable film methods: collaborative study.

Eleven laboratories participated in a collaborative study to compare the dry rehydratable film (Petrifilm SM and Petrifilm VRB) methods, respectively, to the standard plate count (SPC) and violet red bile agar (VRBA) standard methods for estimation of total bacteria and coliform counts in raw and homogenized pasteurized milk. Each laboratory analyzed 16 samples (8 different samples in blind duplicate) for total count by both the SPC and Petrifilm SM methods. A second set of 16 samples was analyzed by the VRBA and Petrifilm VRB methods.

Sex differences in the shape of the sexually dimorphic nucleus of the preoptic area and suprachiasmatic nucleus of the rat: 3-D computer reconstructions and morphometrics.

Three-dimensional images of nuclei facilitate morphological comparisons between differing animal groups. As revealed by computer-assisted techniques, the greater volume in male rats of the sexually dimorphic nucleus of the preoptic area was not proportional in all directions. The nucleus was more elongated in males than females, indicating a sex-dependent shape.

Biosynthesis of the Torpedo californica acetylcholine receptor alpha subunit in yeast.

Yeast cells were transformed with a plasmid containing complementary DNA encoding the alpha subunit of the Torpedo californica acetylcholine receptor. These cells synthesized a protein that had the expected molecular weight, antigenic specificity, and ligand-binding properties of the alpha subunit. The subunit was inserted into the yeast plasma membrane, demonstrating that yeast has the apparatus to express a membrane-bound receptor protein and to insert such a foreign protein into its plasma membrane.

Primary structure of wild-type and mutant alleles of the PET494 gene of Saccharomyces cerevisiae.

The product of the yeast nuclear gene PET494 is required specifically for the translation of the mitochondrially encoded subunit III of cytochrome c oxidase. We have determined the DNA sequence of a 1.9 kb fragment carrying PET494.