Stereo-structural prediction and IR-characteristic band assignment of amorphous protonated forms of homodipeptides (L)-Phe-(L)-Phe, (L)-Trp-(L)-Trp, (L)-Tyr-(L)-Tyr and the neutral - (L)-Trp-(L)-Trp. Ab initio approximation and solid-state linear-polarized IR-spectroscopy

Stereo-structures of protonated (L)-phenylalanine ((L)-Phe), (L)-tyrosine ((L)-Tyr) and (L)-tryptophan ((L)-Trp) containing homodipeptides ((L)-Tyr-(L)-Tyr, (L)-Phe-(L)-Phe, (L)-Trp-(L)-Trp) are carried out by ab initio calculations. The obtained data in gas phase are compared with experimental ones, received by linear-dichroic infrared (IR-LD) spectroscopy of solids, oriented as suspension in nematic mesophase. An observation of a good correlation between theoretical and spectroscopic geometry parameters established and illustrated the possibilities of this complex study approach for the prediction of the stereo-structures in compounds in solid state. The protonation leads to little variance in the bond lengths and angles, expecting the COO(-) fragment, where a distortion of equalized COO(-) bond lengths, stabilizing a C=O double bond and C-O(H) one is established. Significant deviations of the dihedral angles as a result of the protonation are obtained in the skeletal aliphatic and amide- fragments. In (L)-Tyr-(L)-Tyr and (L)-Phe-(L)-Phe, a deviation of O=C-N-H torsion angle about 10-14(0) is predicted. The calculations show a trans-amide configuration in (L)-Trp-(L)-Trp and a cis-one after its protonation.     

Antimalarial constituents from Nauclea orientalis (L.) L

Bioassay-guided fractionation of the antimalarial-active CHCl3 extract of the dried stem of Nauclea orientalis (L.) L. (Rubiaceae) has resulted in the isolation of two novel tetrahydro-beta-carboline monoterpene alkaloid glucosides, naucleaorine (= (16alpha,17beta)-3,14:15,20-tetradehydro-16-ethenyl-17-(beta-D-glucopyranosyloxy)-19alpha-methoxyoxayohimban-21-one; 1) and epimethoxynaucleaorine (2), as well as the known compounds, strictosidine lactam (= (15beta,16alpha,17beta)-19,20-didehydro-16-ethenyl-17-(beta-D-glucopyranosyloxy)oxayohimban-21-one; 3), 3,4,5-trimethoxyphenol (4), 3alpha-hydroxyurs-12-en-28-oic acid methyl ester (5), 3alpha,23-dihydroxyurs-12-en-28-oic acid (6), 3alpha,19alpha,23-trihydroxyurs-12-en-28-oic acid methyl ester (7), and oleanolic acid (8). Compounds 1, 2, 6, and 8 showed moderate in vitro activities against Plasmodium falciparum. Their structures and configurations were elucidated by spectroscopic methods including 1D- and 2D-NMR analyses.     

Micropropagation of hornbeam (Carpinus betulus L.) and ash (Fraxinus excelsior L.)

Shoot multiplication of hornbeam was stimulated onWPM, QL andDKW medium supplemented with a low concentration of BAP or BPA (0.1-0.2 mg I -1) andIBA (0.1 mg I -1). Low concentration of thidiazuron promoted axillary bud formation, higher concentration inhibited shoot elongation. Microshoots were rooted onWPM supplemented with a low auxin concentration (IBA or NAA 0.2-0.5 mg I -1). High rooting percentages were obtained. Shoot proliferation of ash was stimulated on MS andDKW medium supplemented withBAP orBPA (2.0-5.0 mg I -1) andIBA (0.1 mg I -1). Root formation was promoted onWPM containing a low auxin concentration. Rooted plantlets were transplanted into soil and after hardening off the micropropagated trees were planted in the field. The planted trees grew normally without showing signs of abnormality.     

Karyotypes of Bembidion quadrimaculatum (L.) and Clivina fossor (L.) (Coleoptera: Carabidae)

Bembidion quadrimaculatum possesses 24 chromosomes: 2n male = 22 + XY, 2n female = 22 + XX; their structure is meta- and submetacentric and differences in length between them are slight. Achiasmatic meiosis has been identified in spermatogenesis. The diploid chromosome number in Clivina fossor is 44; 2n male = 42 + XY, 2n female = 42 + XX. The chromosome structure is meta-, submeta-, and subtelocentric and X is the longest element in the set. 1 to 2 chiasmata per bivalent occur in meiosis.     

The life cycles of Leptophlebia vespertina (L.) and L. marginata (L.) (Ephemeroptera) in Llyn Dinas, North Wales

Data is presented on the life cycles of Leptopblehia vespertina (L.) and L. marginata (L.) in Llyn Dinas, an oligotrophic North Wales lake. Both species are univoltine and growth continues throughout the winter although somewhat retarded. Except during July and August there is a clear size separation of the two species, L. marginata being larger and emerging earlier. The egg incubation period was determined directly from laboratory studies. The results are discussed in relation to previous research in the English Lake District.     

Electrophoretic identification of roach (Rutilus rutilus L.), rudd (Scardinim erythrophthalmus L.), bream (Abramis brama L.) and their natural hybrids

Roach, rudd, bream and their natural hybrids of 2 cm standard length or larger can be definitively identified by their enzyme electrophoretic patterns. Zymograms of lactate dehydrogenase and esterases as produced by vertical starch gel electrophoretic analysis of whole fry or adult eye extracts are the most useful in this respect. The lactate dehydrogenase isozymes, containing B sub-units, migrate more anodally in rudd and bream than in roach. Due to the tetrameric structure of lactate dehydrogenase, in hybrid rudd x roach and roach x bream, eleven isozymes can be observed as compared with six in the parental patterns. Esterases show unique patterns for all species and hybrids. With the exception of one fraction in rudd x bream, the esterase patterns of hybrids show summations of the parental phenotypes.     

Natural Plant Chemicals Acting as Oviposition Deterrents on Cabbage Butterflies (Pieris btassicae (L.), P. rapae (L.) and P. napi (L.))

In several growers' reports Solatium lycopersicum, Sambucus nigra. Thymus vulgaris, Salvia officinalis, Artemisia absinthium, A. abrotanum , and Allium cepa are said to decrease the oviposition of Pieris brassicae, P. rapae and P. napi. In the present study the butterflies were fed with honey automats and reared throughout the year in artificial light in an insec-tarium. In a dual-choice chamber with a slow throughflow of air two equally sized cabbage leaves were placed on opposite sides. Significantly fewer eggs were layed on the cabbage leaf on which extracts of the mentioned plants had been applied. Ten butterflies were used in each experiment. The chemoreceptors and the chemicals involved are not identified but the inhibitory substances are surely secondary plant substances. Acceptance or rejection of secondary plant metabolics determines the complicated food relationships between plants and insects. The use of secondary plant substances for ecological control of insect pests is proposed.     

Solution structure of an LNA hybridized to DNA: NMR study of the d(CT(L)GCT(L)T(L)CT(L)GC):d(GCAGAAGCAG) duplex containing four locked nucleotides

We have used two-dimensional (1)H NMR spectroscopy at 750 MHz to determine a high-resolution solution structure of an oligonucleotide containing restricted nucleotides with a 2'-O, 4'-C-methylene bridge (LNA) hybridized to the complementary DNA strand. The LNA:DNA duplex examined contained four thymidine LNA modifications (T(L), d(C1T(L)2G3C4T(L)5T(L)6C7T(L)8G9C10):d( G11C12A13G14A15A16G17C 18A19G20). A total relaxation matrix approach was used to obtain interproton distance bounds from NOESY cross-peak intensities. These distance bounds were used as restraints in molecular dynamics (rMD) calculations. Forty final structures were generated for the duplex from A-form and B-form DNA starting structures. The root-mean-square deviation (RMSD) of the coordinates for the 40 structures of the complex was 0.6 A. The sugar puckerings are averaged values of a dynamic interchange between N- and S-type conformation except in case of the locked nucleotides that were found to be fixed in the C3'-endo conformation. Among the other nucleotides in the modified strand, the furanose ring of C7 and G9 is predominantly in the N-type conformation whereas that of G3 is in a mixed conformation. The furanose rings of the nucleotides in the unmodified complementary strand are almost exclusively in the S-type conformation. Due to these different conformations of the sugars in the two strands, there is a structural strain between the A-type modified strand and the B-type unmodified complementary strand. This strain is relaxed by decreasing the value of rise and compensating with tip, buckle, and propeller twist. The values of twist vary along the strand but for a majority of the base pairs a value even lower than that of A-DNA is observed. The average twist over the sequence is 32+/-1 degrees. On the basis of the structure, we conclude that the high stability of LNA:DNA duplexes is caused by a local change of the phosphate backbone geometry that favors a higher degree of stacking.     

Expression of bacterial cellulase genes in transgenic alfalfa (Medicago sativa L.), potato (Solanum tuberosum L.) and tobacco (Nicotiana tabacum L.)

The genes encoding thermostable cellulases E2 and E3 of Thermomonospora fusca were expressed in plants under the control of the constitutive, hybrid Mac promoter. For both E2 and E3, the genes were modified so as to remove the sequence encoding the bacterial leader peptide. Western blot analysis indicated that expression levels of recombinant cellulase in tobacco lines ranged up to about 0.1% (E2) and 0.02% of soluble protein (E3). No phenotypic effect of cellulase expression was noted. Recombinant E2 expressed in either tobacco or alfalfa was active and retained heat stability. These findings are an important first step in the development of crop plants as a production system for cellulases.