Asunto(s)
5-Hidroxitriptófano/farmacología , Caenorhabditis/efectos de los fármacos , Dopamina/farmacología , Animales , Caenorhabditis/fisiología , Esófago/efectos de los fármacos , Femenino , Fertilidad/efectos de los fármacos , Masculino , Movimiento/efectos de los fármacos , Vulva/efectos de los fármacosRESUMEN
Cotton (Gossypium hirsutum) seedlings, uniformly infected with Meloidogyne incognita, were exposed for periods of 1-15 days to a nutrient solution containing tritium-labelled thymidine. Syncytium formation began with the amalgamation of cells near the nematode head, and was followed by synchronized mitoses of the nuclei which had been incorporated into a single cell. Syncytial nuclei synthesized DNA in roots harvested 3, 6, 9, 12, and 15 days after inoculation. Seedlings transferred from unlabelled to labelled nutrient solution 9 days after inoculation, and grown for 6 more days, contained some syncytial nuclei which did not become labelled. Giant-cell nuclei increased in size and, in many cases, all nuclei in one giant cell of a set showed active DNA synthesis at about the time the nematode molted to the adult stage.
RESUMEN
Host-parasite relationships of Meloidogyne incognita acrita and Pratylenchus penetrans were compared on three closely related cultivars of tomato: 'Nemared', resistant to root-knot nematodes; 'Hawaii 7153', moderately resistant; and 'B-5', susceptible. Root-knot nematode larvae induced typical galls on the roots of B-5; larvae that entered Nemared were walled-off by necrotic cells; both reactions occurred in Hawaii 7153. Lesion nematodes caused surface lesions which were initially similar on all cultivars. Five weeks after infection, they penetrated into the stele of the B-5 roots, whereas in Nemared and Hawaii 7153, injury was confined to the cortex. Chlorogenic acid was identified as the major phenofic compound in healthy tomato roots. Nemared contained the highest concentration of the acid and B-5 the lowest. Histochemical tests showed that chlorogenic acid was concentrated in the endodermis. The localized accumulation of chlorogenic acid and its oxidized products in host root cells infected by nematodes was concluded to be an important mechanism of resistance.
RESUMEN
Histochemical study of cabbage roots axenically parasitized by Pratylenchus penetrans revealed a five-fold increase in peroxidase activity (localized near lesions), pectic xylem plugs (resembling those caused by Fusarium), and accumulation of oxidase-mediated polyphenols in the region of mechanical injury. Fusarium-resistant cabbage was more susceptible to Pratylenchus than the Fusariunt-susceptible varieties, particularly in the formation of oxidized phenolic compounds. Of 13 fluorescent compounds detected by paper chromatography, one major spot was found to be ferulic acid and a minor one, catechin.
RESUMEN
Respiration of selected nematode species was measured relative to CO level, temperature, osmotic pressure, humidity, glucose utilization and high ionic concentrations of sodium and potassium.In general, respiration was stimulated most by the dominant environmental factors at levels near those expected in the nematode's "natural" habitat. Soil-inhabiting nematodes utilized O, most rapidly with high (1-2%) CO whereas a foliar nematode (Aphelenchoides ritzemabosi) did so with 0.03% CO, the concentration typically found in air. Temperature optima for respiration corresponded closely to those for other activities. Ditylenchus dipsaci and Pratylenchus penetrans adults and Anguina tritici and A. agrostis second-stage larvae respired within the range of osmotic pressures from 0 to 44.8 arm and respiration of their drought-resistant stages was stimulated by increasing osmotic pressure which accompanies the onset of drought. Rehydration of A. tritici and A. agrostis larvae with RH as low as 5% stimulated measurable respiration. Glucose utilization from liquid medium by A. tritici larvae or A. ritzembosi was not detectable. Supplemental Na stimulated respiration of Anguina tritici, K did not.
