A survey of aphelenchid nematodes (Nematoda: Aphelenchida) associated with maritime pine, Pinus pinaster, was conducted in Portugal in 1996 and 1999. A Bursaphelenchus species has been identified for the first time in the Iberian Peninsula. B. xylophilus is reported for the first time in Europe. It was found in very high numbers - up to 38 000 per 10 g of pine wood - inside a few declining trees infested with curculionid, cerambycid and scolytid beetles. Morphological observations, including shape of spicules, bursa, vulva, female tail end and stylet as well as morphometrics, were in accordance with the species description. Species-specific DNA fragment patterns were obtained using ITS-RFLP analysis, with five different restriction enzymes. The importance and implications of this finding are discussed. Premiere signalisation de Bursaphelenchus xylophilus au Portugal, at en Europe - Une enquete sur les nematodes Aphelenchides (Nematoda: Aphelenchida) associes au pin maritime (Pinus pinaster) a ete realisee au Portugal de 1996 a 1999. Une espece de Bursaphelenchus a ete identifiee pour la premiere fois dans la Peninsule Iberique. B. xylophilus est signale pour la premiere fois en Europe. Il a ete trouve en tres grand nombre - jusqu'a 38 000 individus pour 10 g de bois de pin - dans des arbres deperissants infestes par des Coleopteres Curculionides, Cerambycides et Scolytides. Les observations concernant la morphologie - en particulier la forme des spicules, la bourse, la vulve, l'extremite de la queue de la femelle et le stylet - de meme que les donnees morphometriques correspondent a la description de l'espece. Des sequences de fragments d'ADN specifique de l'espece ont ete obtenus par analyse ITS-RFLP a l'aide de cinq enzymes de restriction. L'importance et les implications de cette decouverte sont discutees.

Beet necrotic yellow vein virus (BNYVV)-infected sugarbeets were obtained from many parts of Europe and also from some sites in Asia and the U.S.A. Reverse transcription (RT)-PCR products of more than I kbp were obtained for four different regions of the viral genome which may be particularly important with respect to the pathogenic properties of the virus, i.e. for the coat protein and the 42K protein-encoding regions on RNA 2 and for major parts ofRNAs 3 and 4. Restriction fragment length polymorphism (RFLP) patterns obtained with these PCR products revealed the existence of two major strain groups of BNYVV, named type A and type B. The A type was detected in Greece, the former Yugoslavia, Slovakia, parts of Austria, Italy, Spain, parts of France, Belgium, The Netherlands and England as well as in Asia (Turkey, Kazachstan, China and Japan) and the U.S.A. The B type occurs in Germany and parts of France. Mixed infections were detected at the borderline regions between areas of the A and B types. Comparisons of published and newly determined nucleotide sequences of the respective parts of the BNYVV genome indicate that the percentage of nucleotide differences between the A and the B type is approximately 3 % for the respective regions of RNAs 2 and 3 and approximately 1.5 % for RNA 4. Nucleotide sequences appear to be remarkably stable within each of the two strain groups. The majority of the nucleotide differences between the A and B types occur in the third triplet position. The amino acid changes in the coat protein area are outside the four previously determined antigenic regions that are accessible on the surface of the virus particles and are involved in the formation of continuous and presumably also discontinuous epitopes. This may explain why serological differences between the two strain groups have not been found.

Histrionicotoxin from the Colombian frog Dendrobates histrionicus and its perhydro derivative reversibly block the acetylcholine-sensitive ion conductance system in frog neuromuscular preparations. The perhydro derivative ana [3Hlperhydrohistrionicotoxin, like histrionicotoxin, caused a significant decrease in the peak amplitude of the end-plate current and shortened its rise time and half-decay time. In membrane preparations from Torpedo electroplax, [3Hjperhy-drohistrionicotoxin bound reversibly to a limited number of high-affinity sites [dissociation constant, (KD) = 0.4 ,uMM. The ratio of perhydrohistrionicotoxin to acetylcholine binding sites in these membrane preparations approached 2. Histrionicotoxins, local anesthetics, and certain cholinergic agonists inhibited binding of perhydrohistrionicotoxin. Binding of perhydrohistrionicotoxin to membranes was decreased bylheat or treatment with proteases. Treatment of membranes with Triton X-100 solubilized acetylcholine binding proteins and apparently also perhydrohistrionicotoxin-binding proteins. However, the detergent Triton X-100 also bound [3H perhydrohistrionicotoxin. This nonspecific binding was not saturable and complicated studies on the antagonism by drugs of binding of [3Hjperhydrohistrionicotoxin. In solubilized preparations the binding protein for acetylcholine could be removed by affinity chromatography or immunoprecipitation without affecting binding ofrperhydrohistrionicotoxin. Sephadex chromatography also separated acetylcholine-from perhydrohistrionicotoxinbinding proteins. Perhydrohistrionicotoxin did not bind significantly to purified acetylcholine-receptor protein but presumably bound to an ion conductance modulator protein that was associated with the acetylcholine-receptor in intact membrane and readily separable from the receptor protein after solubilization.The excitatory action of acetylcholine (ACh) at the postsynaptic membrane involves its binding to a specific recognition site followed by activation of the ion conductance modulator (1) and a marked increase in ionic conductance. The ion conductance modulator may represent an ionic channel or ionophore comprising part of the same macromolecule as the ACh receptor or it may be separate from, but somehow coupled with, the receptor. The ACh receptor, purified in several laboratories (2-5), has generally been assumed to contain, as part of the molecule, the ion conductance modulator. However, in no case did the purified ACh receptors, in the presence of lipid membranes, recover the specificity, magnitude, and kinetics of the ion flux or conductance increase characteristic of the intact system (6-8). This may be due either to lack of incorporation of the receptor molecules into the lipid bilayer or to the absence of parts or all of the ion conductance modulator in the purified receptor preparation.It has been proposed that histrionicotoxin (HTX), an alkaloid isolated from the skin extracts of the Colombian frog, Dendrobates histrionicus (9), modifies responses to ACh in neuromusc...

SUMMARYNorthern blot hybridization experiments with cDNAs to the four RNA species of a Yugoslavian isolate of beet necrotic yellow vein virus (BNYVV) revealed identical virus RNA patterns in root extracts from field-grown sugarbeets and sugarbeet seedlings grown in soil from rhizomania-afftected fields in various regions in Germany and abroad. In contrast, in leaf extracts from mechanically infected Chenopodium quinoa, Tetragonia expansa and sugarbeet and from a naturally infected sugarbeet we observed great variations in the number, size and relative concentration of the small BNYVV RNAs, which suggests that they may undergo deletion mutations when the virus is propagated in leaf tissues.

Wood samples were taken from pine tree plantations in different regions of Malaysia and investigated for the occurrence of Bursaphelenchus species. Among 13 samples collected from damaged or dead pines in West Malaysia (near Kuala Lumpur) and Sabah (Kinabalu National Park and Sepilok), only one sample of a dead Pinus caribaea tree with bark beetle attack from a plantation near Kuala Lumpur revealed the presence of a new species of Bursaphelenchus. Bursaphelenchus rainul sp. n. is characterised by a relatively small stylet lacking distinct basal knobs but with slight basal swellings, lateral eld with two lines, female with a small vulval ap, postuterine branch occupying about 33-50% of vulva-anus distance, female tail slim, conoid, with a nely rounded, ventrally bent terminus, male spicules relatively small with high condylus, distinct rostrum but no cucullus, and a small terminal 'bursa' on the male tail. It is similar to B. hellenicus, B. hylobianum and B. abietinus in the shape of the spicules and the female tail as well as in the presence of only two lines in the lateral eld. It is distinguished by a number of characters including spicule size, shape of the 'bursa', female tail shape and excretory pore position. Bursaphelenchus rainul sp. n. is further distinguished from these morphologically similar species by molecular studies using the ITS-RFLP technique.