Autoradiographic localization of ornithine decarboxylase in mouse kidney by use of radiolabeled α-difluoromethylornithine

Summary Ornithine decarboxylase, a key enzyme in polyamine biosynthesis and cell growth, has been localized in mouse kidney by autoradiography after administration of radiolabeled -difluoromethylornithine. This drug is an enzyme-activated irreversible inhibitor of ornithine decarboxylase and forms a covalent bond with the enzyme. It was found that ornithine decarboxylase is present in all cell types studied but that the highest content occurs in the proximal convoluted tubules followed by the distal convoluted tubules and the collecting tubules. The majority of the enzyme is located in the cytoplasm but about 10–15% is present in the nuclei (often associated with nucleolus-like components) of the cells of the proximal and distal convoluted tubules. The labeled ornithine decarboxylase was lost rapidly from both nucleus and cytoplasm of all the cell types examined, and labeling by radioactive -difluoromethylornithine was greatly reduced if the mice were pretreated for 5 h with cycloheximide to block protein synthesis. These results indicate that ornithine decarboxylase turns over rapidly in all of the cells.     

Effects of triiodothyronine and propylthiouracil on plasma lipoproteins in male rats

Hyperalphalipoproteinemia, characterized by increased plasma concentrations of apoA-I and of HDL lipid and protein, was observed in rats treated with triiodothyronine (T(3)) for 7 days. The increase in the plasma HDL apoproteins was general for apoC, apoE plus A-IV, and apoA-I, as determined by isoelectric focusing. Hypotriglyceridemia, characterized by decreased concentrations of VLDL and apoB, was also observed in the hyperthyroid state. Although in the mildly hypothyroid animals (propylthiouracil-treated), hepatic metabolism of free fatty acid is shifted toward esterification to triglyceride and VLDL formation, as we reported previously, plasma HDL and apoA-I concentrations were not different from control plasma values, while the d 1.006-1.063 g/ml (IDL + LDL) lipoprotein fraction tended to be increased. In general, the proportion of apoE in the (IDL + LDL) fraction of the hypothyroid rat was greater than in controls and hyperthyroid animals, while the proportion of apoE tended to be lower in VLDL from both hypo- and hyperthyroid rats than in VLDL from controls. An enhanced release of apoA-I by perfused livers isolated from rats treated with T(3) was also observed; this enhanced output of apoA-I may explain, in part, the hyperalphalipoproteinemia observed in these rats. The depressed net output of apoA-I in vitro by perfused livers from rats treated with propylthiouracil (PTU) was not expressed in a statistically significant diminished plasma concentration of HDL or apoA-I in the intact animals. Treatment with T(3) also resulted in modification of the content of essential fatty acids in various lipid classes. Linoleic acid residues were significantly reduced and arachidonic acid content was increased in plasma phospholipids and esterified cholesterol in T(3)-treated rats. However, the relative fatty acid composition of unesterified fatty acids and triglyceride fatty acids was not altered by T(3) treatment. PTU treatment had no effect on fatty acid distribution in any of the plasma lipids. Secretion of biliary lipids was increased in perfused livers from T(3)-treated rats, while treatment with PTU did not affect release of lipids in the bile. These observations suggest a regulatory role for thyroid hormones that determine concentration and composition of plasma HDL and other lipoproteins.-Wilcox, H. G., W. G. Keyes, T. A. Hale, R. Frank, D. W. Morgan, and M. Heimberg. Effects of triiodothyronine and propylthiouracil on plasma lipoproteins in male rats.     

The spatial relationship of the viral and H-2 antigens recognized by anti-viral CTLs

With the use of monospecific rabbit anti-G protein and mouse monoclonal anti-H-2K^k, we have analyzed the spatial relationship of the serologically defined H-2K^k antigens and the major surface glycoprotein (G protein) of vesicular stomatitis virus (VSV) to those antigens recognized by B10.A (k, d) anti-VSV cytotoxic T lymphocytes (CTLs). The ability of monoclonal anti-H-2K^k or rabbit anti-G protein to inhibit specifically the cytolytic activity of B10.A anti-VSV CTLs indicates that the G protein and the H-2K^k molecules are in close proximity to the viral and H-2K^k antigens recognized by the anti-VSV (CTLs. By the method of sequential immunoprecipitation, we also demonstrated that only 10–30 percent of the serologically defined G and H-2K^k molecules are in theG-H-2K ^k complexes.Abbreviations used in this paper Con A Concanavalin A - cpm counts per minure - CTLs cytotoxic T lymphocytes - E: T ratio effector: target ratio - G major surface glycoprotein of VSV - MHC major histocompatibility complex - MOI multiplicity of infection - NP40 Nonidet-P40 - PAGE polyacrylamide gel electrophoresis - PBS phosphate-buffered saline - SaCI Staphylococcus aureus, Cowan I strain - SDS sodium dodecyl sulfate - UV ultraviolet light     

Controlling vitrification of petunia in vitro

Summary Nodal segments from in vitro culturedPetunia hybrida were grown under varying cultural conditions. The origin of nodal explants influenced vitrification. Basal segments formed a higher percentage of vitreous shoots than did the upper nodes. A method was developed for including polyethylene glycol with Gelrite to obtain gelled media of varying water potentials. Media water potential from −0.31 to −1.2 MPa had no effect on controlling the level of vitrification. Gelrite promoted vitrification but GIBCO agar, alone or in combination with Gelrite, reduced its occurrence. Lowering media NH₄ content reduced vitrification, whereas sealing culture vessels with parafilm increased it. As it is now possible to control normal and vitreous plant development inPetunia, this can be used as a model system for studying the physiology and biochemistry of this developmental abnormality.     

Right-side dominance for song control in the zebra finch.

Adult male zebra finches underwent unilateral denervation of the syrinx or unilateral lesion of the forebrain nucleus HVC known to be important for song control. Disruptive effects on song were greater after right-side than after left-side operations. After denervation of the right half of the syrinx, the fundamental frequencies of all syllables within a song converged on a value near 500 Hz, and nearly all syllables were altered in type. In contrast, the syllables produced after denervation of the left side of the syrinx largely maintained their preoperative frequencies, and fewer syllables changed in type. Unlike nerve sections, HVC lesions did not result in strikingly lateralized effects on syllable phonology; however, HVC lesions did affect the temporal patterning of a bird's song, whereas nerve sections did not, and changes in temporal patterning were more marked after right than after left HVC lesions. Right-side dominance for zebra finch song control is the reverse of that described in other songbird species with lateral asymmetry for vocal communication. We suggest that the need for a dominant side is more important than the side of dominance.     

Genetic differentiation ofDrosophila melanogaster populations as assessed by two-dimensional electrophoresis

Seven populations ofDrosophila melanogaster, representing a worldwide distribution, were compared using two-dimensional protein gel electrophoresis. A total of 611 protein spots was scored, which probably represent a sample of over 500 loci that were surveyed. Of the protein spots scored, 521 spots were found to be invariant, but another 90 spots were found to be variable among the populations. Of these variable protein spots, 12 were found to be present in only one population. All the populations, except one, had at least one protein spot restricted to itself. However, the Japanese population had by far the most, with five protein spots restricted to this one population, which has been observed in previous studies of private alleles in oriental populations. The mean genetic similarity (F) found among the seven populations was 0.965, with a range of between 0.956 and 0.977. This is similar to previous reports of lower variation found in population genetic surveys using two-dimensional electrophoresis. It was found that the historical relationships among these populations was somewhat congruent with the geographic distribution of the populations, but as in previous studies, it was not exactly coincident.     

HOST EFFECTS ON FERTILITY AND REPRODUCTIVE SUCCESS OF DENDROCTONUS PONDEROSAE HOPKINS (COLEOPTERA: SCOLYTIDAE)

Mountain pine beetles from lodgepole and limber pine in western Canada were crossbred. We compared data about reproductive success and fecundity of parents as well as development, mortality, and fertility of their progeny to determine whether there was reproductive isolation among beetle populations in these hosts. Three factors, directly or indirectly related to the host, influenced reproductive performance of parents (reproductive success, egg gallery length, fecundity, and number of eggs laid per centimeter of gallery) as well as the mortality, dry weight, and fat content of the progeny: (1) the host species in which progeny were reared, (2) the host species in which the female parent was reared, and (3) whether both parents originated from the same or different host species. Limber pine appears to be a better host for Dendroctonus ponderosae reproduction and survival than lodgepole pine. Nonetheless, beetles reared from lodgepole and limber pine can reproduce in either host and will mate with each other. Progeny of all crosses were fertile. Thus, there is no apparent barrier to prevent beetles from the two host species from interbreeding in the field.     

Met-enkephalin effects on associations formed in utero

Rat fetuses exposed to an odor stimulus and an aversive stimulus in utero showed an aversion to the odor when tested 16 days postnatally. Fetuses that also received 80 μg/kg Met-enkephalin showed a greater aversion to the odor stimulus than those subjects that did not receive the peptide. The difference between these groups was marginally significant. Control subjects did not show an aversion. But, subjects exposed to the odor and Met-enkephalin without the aversive stimulus, when tested, showed a significant preference for the odor over other control groups. These data show that associative learning in rat fetuses at 20 days of gestation may be enhanced by administration of Met-enkephalin.     

Precision of the all-glass impinger and the andersen microbial impactor for air sampling in solid-waste handling facilities.

A method was devised to determine the precision of the all-glass impinger and the Andersen six-stage microbial impactor over a wide range of aerosol concentrations like those found in facilities which process solid waste. Simultaneous samples were collected inside a municipal solid-waste recovery system, and the data were treated statistically to estimate the precision of each air-sampling device. All-glass impingers yielded colony counts which indicated a linear relationship between samplers over an observed aerosol concentration of 1.1 X 10(3) to 2.8 X 10(7) colony-forming units per m3 of air. Impactors also yielded colony counts which indicated a linear relationship over an observed aerosol concentration range of 3.9 X 10(3) to 1.9 X 10(5) colony-forming units per m3 of air. The coefficients of variation for the all-glass impinger and the six-stage impactor in an environment with a high and variable dust level were determined to be 0.38 and 0.23, respectively.