Rats chronically injected with urine from Huntington's chorea patients do not striatal damage

Rats were injected subcutaneously for 147 consecutive days with large volumes of urine from control subjects and from patients with Huntington's chorea (HC) in an effort to test for presence of a possible neurotoxic substance in HC. No evidence of illness was observed in animals treated with HC urine, and their behavior did not differ from animals treated with control urine. After rats were sacrificed, striatum was examined for the biochemical and neuropathological changes seen in human striatum in HC. No deficiency of γ-aminobutyric acid content, nor reduction in activities of glutamic acid decarboxylase and choline acetyltransferase, was found in striatum of rats chronically treated with HC urine. Also, no significant differences were found between striatum of control and experimental rats by light or electron microscopy. These results neither support for exclude the possibility of a neurotoxic mechanism for the neuronal loss characteristic of HC.     

Glycolate Excretion and the Oxygen to Carbon Dioxide Net Exchange Ratio during Photosynthesis in Chlamydomonas reinhardtii

Chlamydomonas reinhardtii cells were grown in high (5% v/v) or low (0.03% v/v) CO₂ concentration in air. O₂ evolution, HCO₃⁻ assimilation, and glycolate excretion were measured in response to O₂ and CO₂ concentration. Both low- and high-CO₂-grown cells excrete glycolate. In low-CO₂-grown cells, however, glycolate excretion is observed only at much lower CO₂ concentrations in the medium, as compared with high-CO₂-adapted cells. It is postulated that the activity of the CO₂-concentrating mechanism in low-CO₂-grown cells is responsible for the different dependence of glycolate excretion on external CO₂ concentration in low- versus high-CO₂-adapted cells.     

The construction in vitro of derivatives of bacteriophage lambda carrying the amidase genes of Pseudomonas aeruginosa

Summary The amidase genes of Pseudomonas aeruginosa were inserted into a replacement vector following cleavage with the restriction endonuclease HindIII. The recombinant ami was detected by enhanced growth of Escherichia coli around plaques of the recombinant phage on minimal medium containing acetamide as the nitrogen source. Low levels of amidase activity were detected in E. coli cultures infected with ami and these were sufficient to allow growth with acetamide as nitrogen source. Lysis-defective derivatives of ami were made by introducing Q ^-, S ^- mutations. Cultures of E. coli infected with amiQ ^- S ^- synthesised amidase as the major protein. The amidase produced by these cultures was identical to that produced by PAC strains of P. aeruginosa in substrate specificity, thermal stability and immunological crossreaction.     

Membrane phospholipid phase separations in plants adapted to or acclimated to different thermal regimes

The phase separation temperatures of total leaf phospholipids from warm and cool climate plants were determined in order to explore the relationship of lipid physical properties to a species' thermal habitat. The separation temperatures were determined by measuring the fluorescence intensity and fluorescence polarization of liposomes labeled with the polyene fatty acid probe trans-parinaric acid. To focus on a single climatic region, Mojave Desert dicots (chiefly ephemeral annuals) were examined, with plants grown under identical conditions whenever possible. Winter active species showed lower phase separation temperatures than the summer active species. A group of warm climate annual grasses showed separation temperatures distinctly higher than those of a group of cool climate grasses, all grown from seed under the same conditions. Growth at low temperature seems correlated with (and may require) a low phase separation temperature. Winter active ephemerals appear genetically programmed to synthesize a mixture of phospholipids which will not phase separate in the usual growth conditions. When the lipids of desert perennials were examined in cool and warm seasons, there was a pronounced seasonal shift in the phase separation temperature, implying environmental influences on lipid physical properties. The relationship of these results to high and low temperature tolerance is discussed.     

Comparative in vitro activity of moxalactam (LY127935), other beta-lactam antibiotics,and aminoglycosides

Moxalactam (LY127935), a novel beta-lactam antibiotic, was compared with semisynthetic penicillins, cephalosporins, and aminoglycosides by the agar dilution method against 5,317 recent clinical isolates of facultative and anaerobic bactria. At 0.5 μg/ml, moxalactam inhibited 90% of all Gram-negative bacilli tested except forPseudomonas aeruginosa (81% inhibited by 32 μg/ml) andAcinetobacter calcoaceticus (88% inhibited by 32 μg/ml). More than 90% ofBacteroides fragilis andStaphylococcus aureus were inhibited by 4 μg/ml and 8 μg/ml, respectively. Moxalactam was at least 16-fold more active by weight than cephalothin, cefamandole, and cefoxitin forEscherichia coli, Klebsiella pneumoniae, andEnterobacter species, and 2- to 4-fold more active than cefoxitin forB. fragilis. Moxalactam was 4-fold less active than cefamandole and cephalothin forS. aureus and 2- to 4-fold less active than piperacillin forP. aeruginosa. Moxalactam was as active or more active than the aminoglycosides for all facultative Gram-negative bacilli except forP. aeruginosa. Moxalactam was inhibitory (minimal inhibitory concentration <16 μg/ml) for 20/27 gentamicin-resistant isolates and 8/13 amikacin-resistant organisms. Moxalactam’s in vitro activity against Gram-negative bacilli is markedly superior to presently available cephalosporins and, except forP. aeruginosa, is comparable to the aminoglycosides.     

VARIABILITY OF SHORT-TERM CULTURES OF HeLa S-3 CELLS: CHANGES IN DNA DISTRIBUTIONS AND RATES OF DNA SYNTHESIS

DNA distributions of HeLa S-3 cells in spinner culture exhibit significant time—dependent changes. The major differences appear to occur in the S-phase region. Significant changes in the rates of DNA synthesis in several S-phase subcompartments correlated well with the changes in the DNA distributions. It is proposed that fluctuations in these rates of DNA synthesis are a reflection of the inherent instability of these abnormal, heteroploid cells.     

In vitro translation of maize ADH: Evidence for the anaerobic induction of mRNA

Total cellular RNA from anaerobically stressed maize seedling roots was used to stimulate in vitro translation of authentic maize alcohol dehydrogenase (ADH) in a rabbit reticulocyte lysate system. Total products from such reactions were displayed on NEPHGE-SDS two-dimensional gels and the Adhl-specific translation products were identified by using RNA from sib seedlings segregating for Adhl charge and size variants. The application of a rapid RNA isolation procedure allowed the efficient isolation of biologically active RNAs from small amounts of seedling material. Maize ADHs translated in vitro are identical in size to in vivo ADH. Further, no ADH was detected in the products of an in vitro translation reaction stimulated by total RNA from aerobically grown seedlings. This suggests that induction of ADH protein by anaerobic stress is accomplished by production of Adh mRNA rather than activation of sequestered mRNA. The mRNAs for maize ADH1 and ADH2 are among a small class of mRNAs induced during anaerobiosis.Research was supported by NSF Grant PCM 76-11009. M.D.B. is supported by National Institute of Health Grant PHS 5 T32 GM07227-04. R.J.F. is a Predoctoral Trainee in Genetics supported by National Institute of Health Training Grants 82 and 7757 from the National Institute of General Medical Sciences.     

Somatic hybrids between unilateral cross-incompatible Petunia species

Summary Somatic hybrid plants regenerated following the fusion of leaf mesophyll protoplasts of Petunia parodii with those isolated from a cell suspension of albino P. inflata. These two species exhibit a unilateral cross-incompatability with a pre-zygotic mode of reproductive isolation preventing hybridizations with P. inflata as the maternal parent. Selection of somatic hybrids relied on the fact that unfused or homokaryon protoplasts of P. parodii did not develop beyond the cell colony stage while those of the putative somatic hybrids and albino P. inflata parent produced callus. Green somatic hybrid calluses were readily identified against the white background of P. inflata following complementation to chlorophyll synthesis proficiency and continued growth in hybrid cells. Shoots, and ultimately flowering plants, were identified as somatic hybrids based on their floral morphology and colour, chromosome number and the fact that they segregated for parental characters. The frequency of somatic hybrid production was comparable to that previously established for two sexually compatible Petunia species.     

Ionic basis of different synaptic potentials mediated by an identified dopamine-containing neuron in Planorbis.

A specified dopamine neuron in Planorbis corneus produces dopamine-mediated e.p.s.ps, i.p.s.ps or biphasic, depolarizing-hyperpolarizing p.s.ps in different follower neurons. The excitatory potentials were of three types. Some follower neurons exhibited slow e.p.s.ps (ca 1 s), and a long-lasting, slowly desensitizing, depolarizing response to iontophoresed dopamine. Others showed rapid (ca. 150 ms) e.p.s.ps, often of variable amplitude, and a rapid, quickly desensitizing, response to iontophoresed dopamine. The rapid e.p.s.ps were sometimes followed by the inhibitory response (biphasic potential). The e.p.s.ps were potentiated by hyperpolarization and reduced by depolarization, though they could not be inverted. The slow e.p.s.p. was shown to be associated with an increase in membrane conductance, but it has proved difficult to elucidate the ions involved. A third type of e.p.s.p. was produced by electrical transmission. The inhibitory potentials were generally reduced in amplitude by artificial hyperpolarization but could rarely be inverted. This is probably due in part to the presence of of electrotonic coupling between these follower neurons. The i.p.s.ps were associated with an increase in conductance which appeared small when measured in the cell body. However, the i.p.s.ps produced considerable shunting of electrotonic transmission between coupled followers indicating a large increase in conductance at the synapse. I.p.s.ps were unaffected by Cl-free solution but they were greatly reduced, though rarely inverted, by increasing the external K concentration. They were blocked by intracellular tetraethylammonium, or cooling. The effects on corresponding responses to iontophoresed dopamine were in each case the same as on the i.p.s.ps. It is concluded that the i.p.s.ps mediated by the dopamine neuron are produced by an increase in permeability to K+. On a few occasions i.p.s.ps mediated by the dopamine neuron were potentiated by hyperpolarization. This appeared to be caused by a sharp increase in membrane resistance with hyperpolarization of these particular neurons. However, mediation by a mechanism of conductance decrease could not be completely excluded.     

A radioimmunoassay method for the rapid detection of Candida antibodies in experimental systemic candidiasis

Rabbits were employed as experimental models to evaluate a solid-phase radioimmunoassay (RIA) method for the diagnosis of systemic candidiasis. Ten rabbits were inoculated subcutaneously to mimic superficial candidiasis and were found to produce no antibodies to Candida as determined by both immunodiffusion and RIA procedures. However, 94 per cent of 18 rabbits systemically infected by intravenous injection of Candida cells were observed to produce antibody as assessed by the RIA technique. These data encourage further tests with human sera and the continued development of this RIA procedure as a useful tool in the early serodiagnosis of systemic candidiasis.