Stabilization of Z-RNA by chemical bromination and its recognition by anti-Z-DNA antibodies

Limited chemical bromination of poly[r(C-G)] (32% br8G, 26% br5C) results in partial modification of guanine C8 and cytosine C5, producing a mixture of A- and Z-RNA forms. The Z conformation in the brominated polynucleotide is stabilized at much lower ionic strength than in the unmodified polynucleotide. More extensive bromination of poly[r(C-G)] (greater than 49% br8G, 43% br5C) results in stabilization of a form of RNA having a Z-DNA-like (ZD) CD spectrum in low-salt, pH 7.0-7.5 buffers. Raising the ionic strength to 6 M NaBr or NaClO4 results in a transition in Br-poly[r(C-G)] to a Z-RNA (ZR) conformation as judged by CD spectroscopy. At lower ionic strength Z-DNA-like (ZD) and A-RNA conformations are also present. 1H NMR data demonstrate a 1/1 mixture of A- and Z-RNAs in 110 mM NaBr buffer at 37 degrees C. Nuclear Overhauser effect (NOE) experiments permit complete assignments of GH8, CH6, CH5, GH1', and CH1' resonances in both the A- and Z-forms. GH8----GH1' NOEs demonstrate the presence of both A- and Z-form GH8 resonances in slow exchange on the NMR time scale. The NMR results indicate that unbrominated guanine residues undergo transition to the syn conformation (Z-form). Raman scattering data are consistent with a mixture of A- and Z-RNAs in 110 mM NaCl buffer at 37 degrees C. Comparison with the spectrum of Z-DNA indicates that there may be different glycosidic torsion angles in Z-RNA and Z-DNA [Tinoco, I., Jr., Cruz, P., Davis, P., Hall, K., Hardin, C. C., Mathies, R. A., Puglisi, J. D., Trulson, M. O., Johnson, W. C., & Neilson, T. (1986) in Structure and Dynamics of RNA, pp 55-68, Plenum, New York].(ABSTRACT TRUNCATED AT 250 WORDS)     

Current utilization and further development of the palmyra palm (Borassus flabellifer L., Arecaceae) in Tamil Nadu state,India

The palmyra palm Borassus flabellifer,), a multipurpose tree of great utility, occurs extensively in Tamil Nadu state, India. Figuring in history, literature, and folklore of the state, it is exploited for food from the fruit and tuberous seedlings; beverage and sugar from the sap; fiber from the leaf and leafbase for brushes, cordage, weaving, and plaiting; trunk wood for construction and fuel; and numerous minor products. Increasing exploitation of the palmyra threatens the future supply of palm raw materials so important to rural populations. Integrated development of palmyra products for local and export markets, as well as management/conservation measures, are needed both to maximize the economic value of the products and to assure sustained yield from native stands.     

Apolipoprotein composition of bovine lipoproteins isolated by gel filtration chromatography

1. Bovine lipoproteins were isolated from plasma by gel filtration and apolipoprotein composition determined by SDS-polyacrylamide gel electrophoresis. 2. Bovine triglyceride-rich lipoproteins contained a novel low mol. wt protein Mr = 22,000 and low mol. wt proteins that may be analogous to non-ruminant apolipoproteins A-I, A-IV, and E. 3. Apolipoprotein C appeared to be a minor constituent of bovine triglyceride-rich lipoproteins. 4. Triglyceride-rich lipoproteins contained two high mol. wt proteins of approx. Mr = 220,000 and 290,000. 5. The predominant bovine low density lipoprotein apolipoprotein was approx. Mr = 290,000, however, greater then 25 proteins were often observed between Mr = 110,000 and 370,000. 6. Bovine high density lipoprotein contained proteins analogous to apolipoprotein A-I and C apolipoproteins. 7. Differences in apolipoprotein profiles between non-lactating and lactating cows were not apparent.     

Isolation ofAcholeplasma oculi from human amniotic fluid in early pregnancy

Acholeplasmas have been isolated from a variety of animals, insects, and plants, but onlyAcholeplasma laidlawii has previously been found in humans. We have isolatedAcholeplasma oculi in pure culture from the amniotic fluid of a woman at 19 weeks of gestation. The organism was positively identified by growth inhibition, epi-immunofluorescence, and arbutin hydrolysis. Demonstration of organisms directly in amniotic fluid by DNA fluorochrome and immunofluorescence staining provided additional evidence that the isolate was genuine and not a medium contaminant. The remainder of the pregnancy was unremarkable, and a full-term male infant was delivered without complications. Even though there is some evidence possibly associatingA. oculi with various diseases in livestock, the prevalence and significance ofA. oculi in humans has not been determined.     

Comparison of the gastrointestinal syndrome after total-body or total-abdominal irradiation

In pathogen-free mice, but not standard conventionally housed laboratory rodents, two distinctly different modes of early radiation lethality can be identified by modifying the irradiation technique (total-body versus abdominal irradiation) or by therapeutic intervention such as rescue of total-body-irradiated mice with syngeneic bone marrow or spleen. While damage to the gastrointestinal tract is usually designated as the predominant cause of death occurring within 10 days of radiation exposure, it was demonstrated that damage to the hematopoietic/lymphopoietic system can result in animal lethality over the same period as the gastrointestinal syndrome and that this target cell population is more radiation-sensitive than the gastrointestinal epithelium.     

Efficacy of triclabendazole against fascioloidiasis (Fascioloides magna) in naturally infected white-tailed deer (Odocoileus virginianus)

The efficacy of triclabendazole was evaluated in the treatment of naturally acquired Fascioloides magna infections in white-tailed deer (Odocoileus virginianus). Twenty white-tailed deer were captured on the Welder Wildlife Refuge (Sinton, San Patricio County, Texas, USA) and maintained in a 64 x 64 m deer enclosure. Ten deer were given a 5% suspension of triclabendazole orally at a dosage of 10 mg/kg body weight and 10 deer were given a placebo. Three wk later the deer were euthanized and examined for parasites. At necropsy 19 deer were infected. All specimens of F. magna from the tissues of the triclabendazole treated deer were dead or severely affected by the drug as indicated by changes in their size, color, movement and texture relative to those from control deer. The drug was considered 100% effective against this parasite. Adverse reactions of the deer to the drug were not observed.     

Responses against antigens encoded by theH-3 histocompatibility locus: Antigens stimulating class I MHC- and class II MHC-restricted T cells are encoded by separate genes

The purpose of this work was to study the genetic basis of histocompatibility antigens encoded by the mouse minor histocompatibility (H) locusH-3. Both class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) and class II MHC-restricted helper T cells (TH) specific for antigens encoded by genes within theH-3 locus were isolated and analyzed. Typing a number of mouse strains for expression of antigens recognized by these TH and CTL suggested that there was a different strain distribution pattern of expression of the antigens recognized by TH compared with those recognized by CTL. Separation of the genes whose products stimulate TH from those whose products stimulate CTL was suggested by: (1) analysis of the strain B10.FS(92NX)/Grf that has undergone recombination within theH-3 region; (2) genetic segregation studies of (B10.UW-H-3 ^b/Sn×C57BL/10Sn)F₂ mice; and (3) F₁ complementation studies in which CTL specific for products of the TH-defined gene(s) could not be detected, even in the absence of immune responses to products of the CTL-defined genes. Taken together, these data suggest that in addition to two genes (B2m andCd-1) within theH-3 region whose products typically stimulate class I MHC-restricted CTL, there is at least one additional gene whose product selectively stimulates class II MHC-restricted TH. This new gene is located telomeric from the CTL-defined genes and between the lociwe andun on chromosome 2. These data demonstrate a novel degree of complexity of theH-3 “locus” and suggest selective presentation of minor H gene products in the context of class I or class II MHC proteins.     

Factors responsible for the differences in cultural estimates and direct microscopical counts of populations of bacterivorous nanoflagellates

Bacterivorous nanoflagellates (microflagellates) have been routinely enumerated in marine and freshwater samples using either a Most Probable Number (MPN) culture method or by a direct microscopical counting method (DC). These two techniques typically yield highly disparate estimates of the density of nanoflagellates in natural samples. We compared these methods with seawater and marine snow (macroscopic detrital aggregate) samples collected from surface waters throughout the North Atlantic and in freshwater samples collected at three stations in Lake Ontario. Densities of nanoflagellates determined by the two methods differed by as much as four orders of magnitude; the MPN estimate rarely exceeded 10% of the microscopical count, and averaged 1% of this count. The MPN estimate constituted a higher percentage of the DC value in environments with high concentrations of nanoflagellates relative to environments with low concentrations of nanoflagellates. The ratio of the culture count to the microscopical count (MPNDC) increased along an environmental gradient from oligotrophy to eutrophy, and was positively correlated with the density of bacteria in the samples. In laboratory experiments with two species of bacterivorous nanoflagellates, the MPN count constituted a much greater percentage of the DC count during the exponential growth phase of the nanoflagellate than during the stationary growth phase. Differences in the estimates of nanoflagellate density obtained with these two techniques probably can be explained by the trophic mode of these protozoa, their growth stage, and the amenability of these species to laboratory culture.     

Intermolecular disulfide bonds are not required for the expression of the dimeric state and functional activity of the transferrin receptor.

The human transferrin receptor is expressed as a disulfide-linked dimer at the cell surface. The sites of intermolecular disulfide bonds are Cys-89 and Cys-98. We have examined the functional significance of the covalent dimeric structure of the transferrin receptor by substitution of Cys-89 and Cys-98 with serine residues. Wild-type and mutated transferrin receptors were expressed in Chinese hamster ovary cells (clone TF-) that lack detectable endogenous transferrin receptors. The rates of receptor endocytosis and recycling were measured and the accumulation of iron by cells incubated with [59Fe]diferric transferrin was investigated. No significant differences between these rates were observed when cells expressing wild-type and mutated receptors were compared. The structure of the mutant receptor lacking intermolecular disulfide bonds was investigated. The presence of a population of mutant receptors with a non-covalent dimeric structure was indicated by cross-linking studies using diferric [125I]transferrin and the bifunctional reagent disuccinimidyl suberimidate. However, sucrose density gradient sedimentation analysis of Triton X-100 solubilized transferrin receptors demonstrated that the mutant receptor existed as a monomer in the absence of diferric transferrin and as an apparent dimer in the presence of this receptor ligand. We conclude that the covalent dimeric structure of the transferrin receptor is not required for the expression of the dimeric state and functional activity of the receptor.     

Temperature and concentration behavior of anomalous microwave resonances in DNA

We have calculated the expected absorption of microwave radiation in the gigaHertz frequency range by fixed-length DNA polymer molecules dissolved in saline solution. While the effects of counterions and solvent dynamics have been accounted for in detail, the features of the absorption are completely dominated by the interaction between the charged polymer and the so-called first hydration layer, that is, the nearest layer of solvent water molecules not actually bonded to the polymer. The relevant parameters of the interaction are the strength of the water-to-polymer coupling and the average persistence time of the individual water-to-polymer bonds. These are presumably hydrogen bonds to the oxygen atoms of the backbone phosphate structure. Using a given parameterization we can obtain the structured absorption corresponding to compressional wave phonon excitations on the polymer, "organ pipe" modes, such as have been claimed to be seen by Edwards, Davis, Swicord, and Saffer. While further studies have not confirmed these resonances, at some frequency and hydration these modes must become visible because of the high relaxation time measured by Lindsay, the existence of the resonances in relatively dry fibers and films of DNA, and the existence of underdamped modes in the ir spectrum of DNA in solution. We have examined the effects of varying salt concentration and the system temperature.(ABSTRACT TRUNCATED AT 250 WORDS)