Molecular phylogeny of the Raphidiidae (Raphidioptera)*

We present a molecular phylogeny of the family Raphidiidae including representatives of 21 of the 26 genera. Sequences from the nuclear gene for the large subunit ribosomal RNA (28S rRNA) and the mitochondrial cytochrome c oxidase subunit 3 gene (cox3) were used. For the phylogenetic reconstructions we applied automated and manual approaches for sequence alignment and different evolutionary models and tree building algorithms. The trees based on the two alignment approaches were rather similar in their overall topology. A combination of both marker sequences increased the resolution of the trees. The six clades within the raphidiid family that emerged represent either single genera or groups of genera, namely: (i) the Nearctic genus Agulla Navás, (ii) the Nearctic/Central American genus Alena Navás, (iii) the Central Asiatic and Eastern Palaearctic genus Mongoloraphidia H. Aspöck & U. Aspöck, (iv) the Palaearctic Puncha clade, (v) the western Mediterranean Ohmella clade, and (vi) the Palaearctic Phaeostigma clade. The New World taxa Agulla and Alena are placed as successive out‐groups to a monophyletic Palaearctic clade. The Mongoloraphidia clade is distributed in the eastern Palearctic while the remaining three clades are exclusively (Ohmella clade) or mainly distributed in the western Palaearctic. The early radiation of extant Raphidiidae is interpreted based on the phylogenetic tree obtained in the present study, and the geological and palaeobiological processes around the K–T boundary.     

Resistance of tomatoes to late blight (Phytophthora infestans)

Race T₁ of Phytophthora infestans was first isolated in Central Europe. Tomato varieties carrying the dominant gene Ph were easily infected by T₁ but showed a different degree of field resistance. In September 1967 more than 80% of all isolations from the experimental plots at Greifswald were determined as the aggressive race T₁. This race was also isolated in a large screening test over several provinces of the GDR from potato and tomato fields where no plants carrying dominant resistance genes were present in the neighbourhood. The fungus was able to pass from potato leaves or tubers to detached tomato leaves or intact tomato plants (cv. Fanal) without any reduction in sporulation. The field-resistant tomato variety Ru?ový Ker and the highly field-resistant variety Atom were crossed. In F₂ and subsequent generations, young plants were selected following inoculation of 14 mm leaf-discs. Weak sporulations on the leaf-discs were almost invariably correlated with a reduced level of infection of fruit in the field. Data from crosses of Atom with more or less susceptible varieties suggested the presence of incompletely dominant genes. It is concluded that at least two genes in the variety Atom control field resistance and the gene-symbols Phf and Phf-2 are proposed for them.     

The influence of the extraction procedure on yield of indole-3-acetic acid in plant extracts

Different types of plant material, including both dry and swollen maize kernels, swollen bean seeds, bean seedlings and dry rose seeds, were extracted by different methods and the yield of IAA was determined with the indolo-α-pyrone method. Extraction of dry maize kernels during short time experiments, varying from 3 to 24 h, gave the highest IAA yield when methanol was the extractant and a significant lower yield when diethyl ether or dichloromethane were used. The duration of the extraction period increased the yield with all the extractants. Progressive extractions for several days or weeks had little effect on the yield when 100% acetone was used in contrast to methanol and ether as extractants, which increased the yield during prolonged extraction. Extractions of tissue treated to 100°C for 1 h contradicted the hypothesis that IAA is enzymatically liberated during ether extraction. Water in the extractant solvents increased the yields. This was most pronounced when aqueous acetone was used instead of 100% acetone. Increased extraction temperature augmented the IAA yields. The yield of IAA from other types of tissue extracted with methanol for periods of 3 or 24 h was, however, independent of the duration of the extraction time. This indicates that some tissues contain less not easily extractable IAA than dry maize kernels. The terms “free” and “bound” IAA are discussed; they should be replaced by “easily extractable” and “not easily extractable” IAA. The results also show that IPyA in vitro can partly be converted to IAA during extraction and fractionation.     

The Productivity of Salix glauca L. in Arctic Norway

The productivity of a stand of Salix glauca at 68° N inArctic Norway was investigated. The biomass was 18.4 t ha^–1and the annual production was 1.34–1.56 t ha^–1 year^–1.These low values are attributed to the short growing season.The mean age of the stems was 23.4 years. The prostrate-ascendinggrowth form of the plants is regarded as an adaptation to thesevere winter climate.     

Nucleolus size varies with sex,ploidy and gene dosage in insects

The nucleolus constitutes a cytologically visible phenotype for ribosomal DNA (rDNA). Nucleolar size, as determined by silver staining, is a good indicator of cell proliferation rate and biosynthetic activity. Nevertheless, the relationship between rDNA content and sexual dimorphism for nucleolar size is not well documented. In the present study, the impact of sex and ploidy level on nucleolar size is investigated in three haplo/diploid and three diplo/diploid species of insect. Nucleolar sizes are found to be proportional to ploidy level in the haplo/diploid hymenopterans Trypoxylon albitarse and Nasonia vitripennis. Conversely, in the ant Messor barbarus, nucleolar sizes are larger in haploid males (winged) than diploid females (apterous). Among the diplo/diploid species, evidence for gene dosage compensation on nucleolar activity is suggested by the absence of sex differences in Drosophila simulans, a species in which rDNA is limited to the X chromosome. By contrast, in the grasshopper Stenobothrus festivus, another species with rRNA genes restricted to the X chromosome, the size of the nucleolus is significantly larger in females than in males. Additionally, in the grasshopper Chorthippus parallelus, where rDNA is distributed evenly on several autosomes of males and females, the females also show larger nucleoli than males. In both grasshopper species, the magnitude of the female/male ratio for nucleolus area is very similar to the body size ratio, suggesting that body size, as well as sex, ploidy, gene dosage and physiological activity, may be an important determinant of nucleolus area.     

An Abscisic Acid-like Substance in Dry and Soaked Phaseolus vulgaris Seeds Determined by the Lemna Growth Bioassay

An acid inhibitor, probably abscisic acid (ABA) in low concentrations was found to be present in bean seeds. The evidence is based on data from paper electrophoresis, chromatography, UV absorption and growth inhibition in the Lemna bioassay, sensitive down to a concentration of 10^-11M ABA or 0.02–0.03 ng/flask. The inhibitor level as measured by this bioassay decreases considerably with increasing soaking time. Acid ether-soluble inhibitors could even be detected in the soaking water from the soaked seeds.