In vitro incorporation of 2′-deoxyadenosine and 3′-deoxyadenosine into yeast tRNAPhe using tRNA nucleotidyl transferase,and properties of tRNAPhe-C-C-2′dA and tRNAPhe-C-C-3′dA

2′-Deoxyadenosine and 3′-deoxyadenosine (cordycepin) can be incorporated into the 3′-terminal position of tRNA^Phe by tRNA nucleotidyl transferase. tRNA^Phe-C-C-2′dA and tRNA^Phe-C-C-3′dA, missing the cis-diol group at the 3′-terminal end are resistant to periodate oxidation and are not able to form borate complexes. In aminoacylation experiments only the tRNA^Phe-C-C-3′dA proved to be chargeable.     

Nucleic Acids of Entamoeba histolytica

This review will concentrate on certain aspects of the nucleic acids of Entamoeba histolytica. Utilization and synthesis of purines and pyrimidines will initially be briefly discussed, e.g. salvage vs. de novo pathways, uptake studies and recognition of at least 4 transport loci. Data will be presented which show that the distribution and synthesis of RNA (to a lesser extent DNA) in the nucleus is basically the opposite one finds in other eukaryotes, viz. most RNA (ribosomal?) is synthesized (or accumulates) in the peripheral chromatin (functional equivalent of nucleolus?). The DNA is distributed and synthesized primarily throughout the nucleus. It is usually so dispersed that it will not stain with e.g. the standard Feulgen technique, unless the DNA condenses around the endosome (not a nucleolar equivalent) prior to nuclear division. Isolation of rRNA was difficult due, in part, to potent and difficult to inhibit RNase(s), some of which are apparently intimately bound to ribosomal subunits. The 25S (1.3 kDa), 178 (0.8 kDa) and 58 rRNA were recovered after isolation with a high salt SDS-DEP technique. This is the only procedure which enables us to obtain high yields of 258 rRNA: guanidine or guanidinium which permits isolation of intact functional mRNA results in isolation of small amounts of 28 RNA relative to 178 RNA. The 258 RNA is “nicked” (apparently during nuclear processing) and dissociates readily into 1 78 (0.7 kDa) and 168 (0.6 kDa) species, and a more rigidly bound 5.88 species. A small amount of “unnicked” 258 RNA was recovered with guanidine. Two DNA-dcpendent RNA polymerases (I and II) with a pronounced preference for denatured DNA as template were eluted from DEAE-Sephadex in reverse order of what occurs in other eukaryotes, except Physarum polycephalum. This conclusion was based on salt optima and alpha-amanitin sensitivity studies. Initial characterization of DNA isolated with a procedure capable of isolating > 100-kbp Leishmania DNA showed that undigested DNA migrates as a broad band between markers 6 and 24 kbp. The persistent recovery of such a “band” by us and Perez-Mutul et al. no larger than ca. 24 kbp (with the exception of >48 kbp DNA isolated by Hernandez et al. using an in situ lysis technique which did not include a proteinase) may be due to nicks introduced during isolation; or, perhaps much of the amebal DNA exists in vivo as gene sized fragments. However, preliminary data generated using orthogonal pulse-field agarose gel electrophoresis do suggest that amebal DNA may be in small chromosomes.     

Litter fall and decomposition in a Pinus halepensis forest on Mallorca

Abstract. Litter fall and decomposition in a Pinus halepensis forest was studied in order to help understand nutrient cycles in this ecosystem, threatened as it is by fire and tourism. The study was done over two years in an experimental forest stand at Cap des Pinar on Mallorca, Spain. The woodland area has not been disturbed for about 40 yr. Total litter fall amounted to 3.44 ton ha^-1 yr^-1 and 2.52 ton ha^-1 yr^-1 in the first and second year, and leaf fall to 2.00 ton ha^-1 yr^-1 and 1.93 ton ha^-1 yr^-1 respectively with a maximum in July. As to litter fall, there was a summer maximum for brown needles and kernels, a spring maximum for inflorescences and bud scales, and an autumn maximum for bark. Erratic maxima occurred for fall of green needles, cones and branches, linked to strong winds in winter. The total amount of litter mass on the forest soil reached 12.68 ton/ha: 5.75 ton/ha in the L organic horizon, 3.46 ton/ha needles, and 6.93 ton/ha in the F organic horizon. Weight loss from annual decomposition, measured using litter bags, was 18.1 % in year 1 and 26.8% in year 2. Over 365 days, an Olson (1963) decomposition rate of 0.045 %/day was found in year 1 and of 0.084 %/day for year 2. Decomposition half-time was 1529 for year 1 and 827 days for year 2.     

Statistics of RNA melting kinetics

We present and study the behavior of a simple kinetic model for the melting of RNA secondary structures, given that those structures are known. The model is then used as a map that. assigns structure dependent overall rate constants of melting (or refolding) to a sequence. This induces a landscape of reaction rates, or activation energies, over the space of sequences with fixed length. We study the distribution and the correlation structure of these activation energies. Correspondence to: P. Schuster     

Biotype-specific expression of dsRNA in the sweetpotato whitefly

This study was conducted to evaluate the effect of two different biotypes of the sweetpotato whitefly,Bemisia tabaci (Gennadius), on the induction of squash silverleaf (SSL), and to determine if double-stranded RNA (dsRNA) occurs in geographically remote populations of the two biotypes. Recently collected B-biotype whiteflies from Florida, Arizona, Mississippi, and Texas (SPW-B) all contained a 7.0 kb dsRNA molecule. Kb dsRNA molecule. Laboratory colonies of A-biotype whiteflies that were originally collected in 1981 from cotton in Arizona and California did not contain the 7.0 Kb dsRNA. When the two biotypes were compared only the SPW-B induced rapid onset, grade 5, SSL. DsRNA similar to that found in adult SPW-B was concentrated in whitefly nymphs, but host plant leaf tissue did not contain any consistent dsRNA molecules. SPW-A only induced low-grade SSL and progeny of SPW-A that were fed on pumpkin plants displaying SSL did not acquire the ability to express dsRNA or induce SSL. Our data suggest that dsRNA is not directly involved in the induction of SSL and that SSL is a host-specific response, to a feeding injury induced by B-biotype whiteflies. The origin and source of the 7.0 Kb dsRNA molecule remains enigmatic but its expression is constant in the whitefly biotype that is responsible for the induction of SSL and several other plant disorders in the U.S.     

Response of root mRNA population to sulphate shortage in maize seedlings

Roots of ten-days-old seedlings obtained from a maize hybrid grown in complete or in sulphate-deprived medium were used to extract Poly(A)+RNA. The response to sulphate deprivation, which is known to increase the uptake capacity up to ten times, was manifested also by the expression of three mRNA species, as shown by the in vitro translation of the mRNA population. One hour after transfer to complete nutrient medium all three mRNAs were still present.Abbreviations BSA Bovine Serum Albumine - DTT 1,4-Dithio-DL-Threitol - EDTA Ethylenediaminetetraacetic-acid - MES 2-(N-Morpholino) ethane sulfonic acid - SDS Sodium Dodecyl Sulfate - TCA Trichloracetic acid - TRIS Tris(hydroxy-methyl)-aminomethane     

High-temperature gas chromatography and gas chromatography-mass spectrometry of glycoprotein and glycosphingolipid oligosaccharides

High-temperature gas chromatography and gas chromatography-inass spectrometry for the analyses of oligosaccharides derived from glycoproteins or glycosphingolipids has been developed. Pcrmethylatcd oligosaccharides with up to about 12 sugar residues and masses up to 2500 Daltons can be analyzed. This approach is discussed and exemplified.     

Mouse blastocyst immunosurgery with commercial antiserum to mouse erythrocytes

Summary Immunosurgery is a useful technique for the isolation of inner cell masses from murine blastocysts. Conventionally, rabbit antisera made ad hoc against murine splenic or fetal cells or fibroblasts have been used as antibody sources. We investigated the feasibility of using commercially available rabbit antiserum to murine erythrocytes (anti-RBC) and compared it with rabbit antiserum generated ad hoc to murine L-cells (anti-L-cell). Our results indicate that anti-RBC is at least as effective as anti-L-cell serum for the immunosurgical isolation of inner cell masses, which became either miniblastocysts (later forming outgrowths) or embryoid bodies (undergoing ectoderm-endodermlike differentiation within 48 h). Because anti-RBC is commercially available, the technical modification described herein increases the accessibility of the immunosurgical protocol for the isolation of murine inner cell masses.     

Antibacterial Compound Isolation and Characterization from the Plant Cynotis axillaris Schult

A novel flavone glycoside was isolated from the methanolic extract of Cynotis axillaris Schult. Various analysis and characterization techniques were used to determine its structure and properties. The compound exhibited a melting point range of 231–232 °C and had a molecular formula of C₂₇H₃₀O₁₄. Several spectral characterization techniques were employed to establish the isolated compound's structure. These included UV-visible spectroscopy, FT-IR, LC-ESI-MS, and NMR spectroscopy. Based on these analyses, the structure of the isolated compound was determined to be 5,7,4’-trihydroxyflavone-8-α-L-rhamnopyranoside-4’-O-β-D-galactopyranosyl. This structure indicates that it is a flavone glycoside consisting of a flavone (5,7,4’-trihydroxyflavone) moiety attached to a sugar molecule (galactopyranosyl) at position 4’, which further bears a rhamnose group at position 8 of the flavone. In addition, to the structural characterization, the compound also demonstrated significant antibacterial efficacy against various bacterial pathogens, including Gram-positive bacteria such as Bacillus subtilis MTCC441 and Gram-negative bacteria such as Escherichia coli MTCC1098, Proteus vulgarize MTCC426, and Salmonella Typhimurium MTCC3224. The antimicrobial activity was evaluated by measuring the zone of inhibition in millimetres, which provides an indication of the compound's ability to inhibit bacterial growth. The study successfully identified and characterized a novel flavone glycoside from Cynotis axillaris Schult. and its antimicrobial activity.