Use of Brassica callus culture to induce sporulation in Alternaria brassicae (Berk.) Sacc.

A non-sporulating isolate of Alternaria brassicae, inoculated on callus culture of Brassica juncea cv. Kranti, colonized the callus and produced spores. When captafol, a fungicide, was added (100 mg/l) to the callus culture medium, if effectively checked fungal contamination and saprophytic growth of A. brassicae on culture medium, without adversely affecting callus growth or establishment of dual culture.     

Transformations of acetates of citronellol,geraniol, and linalool by Aspergillus niger: regiospecific hydroxylation of citronellol by a cell-free system

Summary Incubation of acetates of geraniol, citronellol and linalool with Aspergillus niger resulted in their hydrolysis to corresponding alcohols which were further hydroxylated to their respective 8-hydroxy derivatives. In the case of linalyl acetate, besides linalool and 8-hydroxylinalool, small amounts of geraniol and -terpineol were also formed. Microsomes (105 000xg sediment) prepared from induced cells of A. niger were found to convert (1-³H)citronellol to 8-hydroxy citronellol in the presence of NADPH and O₂. The pH optimum for the hydroxylase was found to be 7.6.     

An estimate of the physical distance between two linked markers inHaemophilus influenzae

Using DNA clones, the physical distance between the linked genesnov andstr inHaemophilus influenzae was estimated. Although none of the cloned inserts contained both the markers, pJ1-8Str^R 13 (insert of 18·7 kb) includedstr gene at one end and part ofnov gene at the other end of the insert. By EcoRI restriction analysis and by Southern hybridization, the distance between the two EcoRI sites, cutting at which inactivates the two genes, was estimated to be 17·7 kb. A single continuous EcoRI fragment (containing 4EcoRI sites within it) carrying both the genes intact would need to be 20·4 kb in size. These estimates were confirmed independently using different clones ofnov ^r andstr ^r alleles as probes for hybridization with BamHI-digested chromosomal DNA.     

Effect of Maternal Alcohol Consumption on the Lipid Composition of CNS in the Offspring

Maternal alcohol consumption at a level that does not affect calorie intake increases cholesterol concentration and content as well as incorporation of labeled glucose into cholesterol in the brain and spinal cord of newborn rat pups. Continued consumption of alcohol during lactation also affects the galactolipid concentration in the brain and spinal cord of pups at 21 days of age, and this increase seems mainly to be due to an increase in content of myelin lipids. Analysis of myelin shows that the concentration of phospholipids also increases in this fraction. The increase in incorporation of labeled glucose into these membrane lipids suggests an increase in the synthesis of these lipids, which prevents fluidization of the membrane by alcohol. That in the brainstem the increase in levels of cholesterol and galactolipids is higher than in other regions and that there is also an increase in content of sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine suggest that the brainstem needs better protection against fluidization.     

Sister-chromatid exchanges induced by triethylenemelamine: in vivo and in vivo/in vitro studies in mouse and Chinese hamster bone marrow and spleen cells

This study was designed to obtain sister-chromatid exchange (SCE) frequencies in bone marrow and spleen cells of mice and Chinese hamsters under in vivo and in vivo/in vitro systems following treatment of animals with varying doses (15-405 micrograms/kg) of triethylenemelamine (TEM). A dose-related SCE response was found in both species, tissues, and systems analyzed following TEM treatment. In vivo, similar responses were noted for both tissues in both species. However, in vivo/in vitro, the response was lower than in vivo and it varied with the tissue. The spleen cells were more sensitive and gave higher numbers of SCEs than bone marrow of both species at the two highest doses tested (135 and 405 micrograms/kg). These differences may be attributed to cell-culturing effects, type of cells analyzed, species and tissue specificities, and pharmacokinetic properties of the chemical. This study lends support to recently established in vivo/in vitro cell culture methodologies employing mice and Chinese hamsters for comparative cytogenetic analysis.     

Yolk proteins from nematodes, chickens, and frogs bind strongly and preferentially to left-handed Z-DNA

Yolk proteins purified from the nematode Caenorhabditis elegans, from the frog Xenopus laevis, and from chicken eggs all have the unexpected property of binding strongly and preferentially to a left-handed Z-DNA probe, brominated poly(dG-dC). We estimate that the nematode proteins bind to Z-DNA with an association constant of at least 10(4) (M-1) and that this association constant is at least 40-50-fold higher than the association constant to B-DNA. Thus, yolk proteins have a higher Z-DNA specificity than most of the Z-DNA binding proteins previously isolated from other sources. Although yolk protein binding to Z-DNA is poorly competed by a wide variety of nucleic acids, the interaction is strongly competed by the phospholipids cardiolipin and phosphatidic acid (500-1000-fold better than by the same mass of B-DNA). We suggest that Z-DNA interacts with the yolk protein phospholipid binding site. In general, our results emphasize the danger of using physical properties to infer biological function. In particular, our results should raise serious questions about the biological relevance of previously isolated Z-DNA binding proteins.     

Ionic conditions for the cleavage of the tRNA-like structure of turnip yellow mosaic virus by the catalytic RNA of RNase P

The 3'-end of the RNA genome of turnip yellow mosaic virus can form a pseudoknotted tRNA-like structure that can be recognized by several tRNA-specific enzymes. We have found that the catalytic RNA component of Bacillus subtilis RNase P can cleave this structure in unusually low ionic strength buffers at a site analogous to the 5'-end of an aminoacyl stem of a tRNA. Most other precursors can only be processed under low ionic strength conditions if the RNase P holoenzyme is used; processing by the catalytic RNA component alone requires a higher ionic strength buffer. The cleavage of the turnip yellow mosaic virus tRNA-like structure demonstrates the importance of the substrate in determining the optimal buffer conditions for this reaction and also shows that high ionic strength buffers are not always necessary for cleavage by the catalytic RNA.     

Distribution of FMRFamide-like immunoreactivity in the forebrain of the catfish, Clarias batrachus (Linn.).

The anatomical distribution of FMRFamide-like immunoreactivity in the forebrain and pituitary of the catfish, Clarias batrachus, was investigated. Immunoreactive cells were observed in the ganglion cells of the nervus terminalis (NT) and in the medial olfactory tracts. In the preoptic area, FMRFamide-containing perikarya were restricted to the lateral preoptic area, paraventricular subdivision of the nucleus preopticus, nucleus suprachiasmaticus and nucleus preopticus periventricularis posterior. In the postoptic area, some cells of the nucleus postopticus lateralis and nucleus of the horizontal commissure showed moderate immunoreactivity. In the tuberal area, immunoreactivity was observed in few cells of the nucleus hypothalamicus ventralis and nucleus arcuatus hypothalamicus (NAH). Nucleus ventromedialis thalami was the only thalamic nucleus with FMRFamide immunoreactivity. Immunoreactive processes were traceable from the NT through the medial as well as lateral olfactory tracts into the telencephalon and the area ventralis telencephali pars supracommissuralis (Vs). Further caudally, the immunoreactive fibers could be traced into discrete areas, including habenular and posterior commissures, neurohypophysis and pituitary; isolated fibers were also observed in the pineal stalk. A loose network of immunoreactive processes was observed in the olfactory bulbs and the entire telencephalon, with higher densities in some areas, including Vs. A dense plexus of immunoreactive fibers was seen in the pre- and postoptic areas and around the paraventricular organ, while relatively few were observed in the thalamus. A high concentration of fiber terminals was found in the caudal tuberal area.     

Nitroxide-mediated protection against X-ray- and neocarzinostatin-induced DNA damage.

The stable free radical Tempol (4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy) has been shown to protect against X-ray-induced cytotoxicity and hydrogen peroxide- or xanthine oxidase-induced cytotoxicity and mutagenicity. The ability of Tempol to protect against X-ray- or neocarzinostatin (NCS)-induced mutagenicity or DNA double-strand breaks (dsb) was studied in Chinese hamster cells. Tempol (50 mM) provided a protection factor of 2.7 against X-ray-induced mutagenicity in Chinese hamster ovary (CHO) AS52 cells, with a protection factor against cytotoxicity of 3.5. Using the field inversion gel electrophoresis technique of measuring DNA dsb, 50 mM Tempol provides a threefold reduction in DNA damage at an X-ray dose of 40 Gy. For NCS-induced damage, Tempol increased survival from 9% to 80% at 60 ng/mL NCS and reduced mutation induction by a factor of approximately 3. DNA dsb were reduced by a factor of approximately 7 at 500 ng/mL NCS. Tempol is representative of a class of stable nitroxide free radical compounds that have superoxide dismutase-mimetic activity, can oxidize metal ions such as ferrous iron that are complexed to DNA, and may also detoxify radiation-induced organoperoxide radicals by competitive scvenging. The NCS chromophore is reduced by sulfhydryls to an active form. Electron spin resonance (ESR) spectroscopy shows that 2-mercaptoethanol-activated NCS reacts with Tempol 3.5 times faster than does unactivated NCS. Thus, Tempol appears to inactivate the NCS chromophore before a substantial amount of DNA damage occurs.     

Inhibition of human immunodeficiency virus type 1 multiplication by antisense and sense RNA expression.

Human immunodeficiency virus type 1 (HIV-1) primarily infects CD4+ lymphocytes and macrophages and causes AIDS in humans. Retroviral vectors allowing neomycin phosphotransferase (npt) gene expression were engineered to express 5' sequences of HIV-1 RNA in the antisense or sense orientation and used to transform the human CD4+ lymphocyte-derived MT4 cell line. Cells expressing antisense or sense RNA to the HIV-1 tat mRNA leader sequence, as part of the 3' untranslated region of the npt mRNA, remained sensitive to HIV-1 infection. In contrast, resistance to HIV-1 infection was observed in cells expressing antisense RNA to the HIV-1 primer-binding site or to the region 5' to the primer-binding site as part of the 3' region of the npt mRNA. Cells expressing the tat mRNA leader sequence in the sense orientation as a precise replacement of the 5' untranslated region of npt mRNA were also resistant to HIV-1. These results indicate that sense and antisense approaches can be used to interfere with HIV-1 multiplication.