A comparison of the effects of various spindle toxins on metaphase arrest and formation of micronuclei in cell-suspension cultures ofNicotiana plumbaginifolia.

The effects of the spindle toxins colchicine, oryzalin and amiprophos-methyl (APM) on metaphase arrest, chromosome scattering, and on the induction and yield of micronuclei were compared in suspension cells ofNicotiana plumbaginifolia (kanamycin-resistant "Doba" line). The inhibition of spindle formation is stronger with oryzalin and APM than with colchicine, which resulted in a more efficient accumulation of meta-phases with well-scattered chromosomes, allowing the isolation of single chromosomes. Further, APM and oryzalin treatments resulted in a higher frequency of micro-nucleated cells and greater yield of micronuclei than after colchicine treatment.

Bloodmeal digestion by strains of Anopheles stephensi liston (Diptera: Culicidae) of differing susceptibility to Plasmodium falciparum.

Blood digestion was studied in strains of Anopheles stephensi which had been genetically selected for either refractoriness or susceptibility to infection by Plasmodium falciparum. Females of the refractory Pb3-9a strain ingested more blood than selected (Sda-500) and unselected (Punjab) susceptible females and began to degrade the haemoglobin soon after feeding. In susceptible females, haemoglobin degradation started only after a significant post-feeding lag period.

Long-term survival of and plasmid stability inPseudomonas andKlebsiella species and appearance of nonculturable cells in agricultural drainage water.

One year after introduction into agricultural drainage waterPseudomonas fluorescens R2f (RP4),Pseudomonas putida CYM318 (pRK2501), andKlebsiella aerogenes NCTC418 (pBR322) could be recovered on agar media. Survival of the introduced strains depended on competition with the indigenous microflora, the presence of nutrients, and the availability of air.In contrast toK.

Frequent spontaneous deletions of Ri T-DNA in Agrobacterium rhizogenes transformed potato roots and regenerated plants.

The presence of T-DNA was examined by Southern blot analysis in 16 regenerated shoot lines derived from 6 Agrobacterium rhizogenes-transformed root clones of Solanum tuberosum L. cv. Bintje.

Habitable pore space and survival ofRhizobium leguminosarum biovartrifolii introduced into soil.

The hypothesis that the population size of introduced bacteria is affected by habitable pore space was studied by varying moisture content and bulk density in sterilized, as well as in natural loamy sand and silt loam. The soils were inoculated withRhizobium leguminosarum biovartrifolii and established and maintained at soil water potentials between -5 and -20 kPa (pF 1.7 and 2.

Role of Microniches in Protecting Introduced Rhizobium leguminosarum biovar trifolii against Competition and Predation in Soil.

The importance of microniches for the survival of introduced Rhizobium leguminosarum biovar trifolii cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. The recolonized soils contained several species of soil microorganisms but were free of protozoa. Part of these soil samples was inoculated with the flagellate Bodo saltans, precultured on rhizobial cells.

Location of a gene conferring DDT resistance but no pyrethroid cross-resistance in larvae of Anopheles stephensi.

In larvae of Anopheles stephensi, DDT resistance of 30 to 40-fold, involving no cross-resistance to pyrethroids, showed fully dominant monofactorial inheritance. The gene, termed DDT, is located 36.6 cross-over units from the morphological mutant, black larvae (Bl), on chromosome III.

Fate of introduced genetic markers in transformed root clones and regenerated plants of monohaploid and diploid potato genotypes.

Agrobacterium transformation of stem internodes of four monohaploid (839-79, 849-7, 851-23, 855-1) and two diploid (M9 and HH260) potato genotypes using hairy root-inducing single (LBA 1020, LBA 9365, LBA 9402) and binary (LBA 1060KG) vectors is reported. Various media and successive culture steps were tested for plant regeneration from different transformed root clones. The fate of introduced genetic markers in root clones and regenerated plants (hairy root phenotype, hormone autotrophy, opine production, kanamycin resistance, β-glucuronidase activity), the ploidy stability and protoplast yield were analysed.

A screening for the presence of four different crystal protein gene types in 25 Bacillus thuringiensis strains.

25 different strains of Bacillus thuringiensis, belonging to 18 different serotypes were screened by Southern hybridization analysis for the presence of nucleotide sequences of four different gene types coding for crystal proteins showing different insecticidal spectra. Many but not all strains showed sequences homologous to any of the probes used. Homology with sequences of the gene type present in strain kurstaki HD1 occurred in all positive strains, whereas the other gene types were much less abundant.

Selection of Anopheles stephensi for refractoriness and susceptibility to Plasmodium falciparum.

Variation in susceptibility of the vector Anopheles stephensi Liston to the human malaria parasite Plasmodium falciparum (Welch) was demonstrated using twelve strains of mosquitoes and one strain of parasites cultured in vitro. The Beech strain of An. stephensi exhibited greatest natural refractoriness, but with high intrapopulation variability.

Vital DNA staining of agarose-embedded protoplasts and cell suspensions of Nicotiana plumbaginifolia.

The DNA of agarose-embedded protoplasts of Nicotiana plumbaginifolia was stained with Hoechst 33342 by immersing microscope slides, coated with immobilized protoplasts, into Erlenmeyer flasks containing consecutively dye solution, pH-correcting washing solutions and culture medium. After staining, protoplasts regenerated cell walls, started to divide and proliferated to calli. The culture system with immobilized protoplasts permits rapid change of culture media and accurate control of experimental conditions.

Temporary disturbance of translocation of assimilates in douglas firs caused by low levels of ozone and sulfur dioxide.

Douglas firs (Pseudotsuga menziesii [Mirb.] Franco) are suffering strongly from air pollution in western Europe. We studied the effect of low concentrations of ozone (200 micrograms per cubic meter during 3 days) and sulfur dioxide (53 micrograms per cubic meter during 28 days) on translocation of assimilates in 2 year old Douglas firs.

Accumulation of thiophenes by cell cultures of tagetes patula and the release of 5-(4-Hydroxy-1-butynyl)-2,2'-bithiophene into the medium.

Calli of TAGETES PATULA, subcultured one or two times, were used to start liquid cultures. Calli of both subcultures contained thiophene-biocides, mainly 5-(but-3-en-1-ynyl)-2,2'-bithiophene (BBT) and 5-(4-acetoxy-1-butynyl)-2,2'-bithiophene (BBTOAc). Secondary calli contained about 3 times higher concentrations of thiophenes than tertiary calli.

Molecular cloning and analysis of four potato tuber mRNAs.

Tuberization in potato is a complex developmental process involving the expression of a specific set of genes leading to the synthesis of tuber proteins. We here report the cloning and analysis of mRNAs encoding tuber proteins. From a potato tuber cDNA library four different recombinants were isolated which hybridized predominantly with tuber mRNAs.

Introduction of foreign genes into potato cultivars Bintje and Désirée using an Agrobacterium tumefaciens binary vector.

Tuber discs of Solanum tuberosum cv Bintje and Désirée were cocultivated with an Agrobacterium tumefaciens binary vector, carrying both the neomycine phosphotransferase and the E. coli β-glucuronidase gene fused to resp. the nopaline synthase and Cauliflower mosaic virus 35S promotor.

Reduced susceptibility to permethrin and its relationship to DDT resistance in larvae of Anopheles stephensi.

Permethrin selection of DDT resistant Anopheles stephensi Liston mosquito larvae produced a reduction in susceptibility to knockdown (2 h exposure) of 17-fold, but only 1.6-fold to kill (24 h exposure). Genetic analysis, incorporating visible mutant markers, was interpreted as indicating that, through multigenic inheritance, several interacting genetic factors were collectively responsible for reduced larval susceptibility to knockdown.

Efficient induction by amiprophos-methyl and flow-cytometric sorting of micronuclei in Nicotiana plumbaginifolia.

Amiprophos-methyl (APM) is a potential herbicide which acts at the level of microtubules. By exposure of suspension cells of Nicotiana plumbaginifolia to this agent, a high degree of metaphase arrest was observed and single as well as groups of chromosomes were scattered throughout the cell, offering good prospects for application in cytology and chromosome isolation. After prolonged exposure to the drug, the chromosomes decondensed and micronuclei were formed.

Somatic hybrid potato plants after electrofusion of diploid Solanum tuberosum and Solanum phureja.

Protoplasts from diploid S. tuberosum and diploid S. phureja were electrofused followed by selection of the heterokaryons with a micromanipulator.

Genetic sexing in the mediterranean fruit fly, Ceratitis capitata, using the alcohol dehydrogenase locus.

Using the alcohol dehydrogenase (ADH) locus a genetic sexing system is being developed in the Mediterranean fruit fly Ceratitis capitata based on the sensitivity of ADH null mutations to environmental ethanol. A series of null mutants have been induced at this locus, however, none proved viable as homozygotes. One of these null mutants was translocated to the male determining chromosome and this line can be used for genetic sexing.

Flow cytometric analysis of polysomaty and in vitro genetic instability in potato.

The analysis of nuclear DNA contents in various tissues of potato genotypes showed that flow cytometry is a rapid method to characterize large populations of cells for polysomaty, that is, the occurrence of cells with normal DNA levels together with cells containing endoreduplicated nuclei. The proportion of endoreduplicated nuclei varied in different tissues and genotypes of potato. The analysis of callus and cell cultures showed that the temporal changes in nuclear DNA contents during in vitro growth can be followed and the degree of polyploidization quantified.

Electrofusion, a simple and reproducible technique in somatic hybridization of Nicotiana plumbaginifolia mutants.

Electrofusion of protoplasts from two complementary nitrate reductase deficient mutants of Nicotiana plumbaginifolia has resulted in somatic hybrid lines. Mesophyll protoplasts isolated from the cofactor mutant CNX 20 and fluorescein diacetate stained protoplasts derived from a cell suspension culture of the NA 36 line, being defective in the apoenzyme, were used in the fusion experiments. In total, 594 lines were recovered which could proliferate on a selective medium with nitrate as the sole nitrogen source.

Variant Cell Lines of Haplopappus gracilis with Disturbed Activities of Nitrate Reductase and Nitrite Reductase.

Selected variant cell lines of Haplopappus gracilis (Nutt) Gray that showed disturbed growth after transfer from an alanine medium to NO(3) (-) medium were characterized. The in vivo NO(3) (-) reductase activity (NRA) was lower in these lines than in the wild type. In vitro NRA assays suggest that decreased in vivo NRA was not caused by a lower amount of active enzyme.

Effect of Explant Origin on Growth and Differentiation of Calli from Tagetes species.

Tertiary leaf callus from 13-week-old Tagetes minuta showed 5 to 6-fold higher fresh weight increment than callus from 3 to 7-week-old plants. No such differences were observed in the primary and secondary calli. Similarly, tertiary leaf callus of T.