Migratory response of European eel (Anguilla anguilla) phagocytes to the eel swimbladder nematode Anguillicola crassus.

The migratory response of peripheral blood granulocytes and monocytes from the European eel Anguilla anguilla (L.) to infective larvae of the swimbladder nematode Anguillicola crassus Kuwahara, Niimi and Hagaki, 1974 was examined by means of light microscopical histology and with an in vitro assay using a modified Boyden chamber. Histological examination of experimentally infected eels revealed that, already 8 days postinfection, an infiltration of inflammatory cells around L3 of A. crassus in the swimbladder tissue can occur. In the Boyden chamber, in presence of infective larvae of A. crassus (L3), neutrophil granulocytes and monocytes showed a higher migration activity than in the absence of L3. In conclusion, infection of European eels with A. crassus leads to an activation of the defence cells resulting in an increased migration activity compared to uninfected eels.

Trans-species transfer of Wolbachia: microinjection of Wolbachia from litomosoides sigmodontis into Acanthocheilonema viteae.

Intracellular bacteria of the genus Wolbachia are found in most filarial nematodes, but are lacking in some species like Acanthocheilonema viteae. Due to their symbiotic nature and their role in the pathology of filarial infections they are considered to be potential targets for intervention against filarial infections in man. Infection of A. viteae (a species which does not naturally carry Wolbachia) with Wolbachia bacteria could allow comparative studies on the effect of the endobacterium on the parasite and on the host's immune systems. As a step towards such studies we microinjected adult female A. viteae with Wolbachia obtained from Litomosoides sigmodontis. The bacteria were isolated from L. sigmodontis by density-gradient centrifugation, microinjected into A. viteae worms and bacterial DNA detected by PCR with Wolbachia specific primers (ftsZ gene). Microinjected worms were cultured in vitro, and 81% survived for 10 days. Implantation of microinjected worms into Meriones unguiculatus, the rodent host of A. viteae resulted in 38% survival. The DNA of the microinjected worms recovered from jirds 8 weeks after implantation contained Wolbachia DNA as shown by PCR, suggesting that Wolbachia of L. sigmodontis can be horizontally transmitted to A. viteae.

Protective immunity induced by irradiated third-stage larvae of the filaria Acanthocheilonema viteae is directed against challenge third-stage larvae before molting.

Jirds (Meriones unguiculatus) were vaccinated with irradiated L3 third-stage larvae (L3) of Acanthocheilonema viteae, and the time required for killing of the challenge L3 was determined. The number of parasites recovered from vaccinated jirds was reduced to about 10% of the control values on the second day after challenge infection and later on. Histological studies revealed an eosinophil-rich infiltrate containing macrophages, neutrophils, and mast cells in the vicinity of the L3 on day 2 after challenge and destruction of the worms by day 4 after challenge. Ultrastructural studies confirmed these data and showed that eosinophils, macrophages, and mast cells were close to the L3 on day 2 after challenge. Flattening of the eosinophils onto the surface of the worms, degranulation of electron-dense material, and rupture of the L3 surface was observed on day 4 after challenge, followed by invasion of the inner of the worms by phagocytic cells. These data show that immune attack against the challenge L3 in vaccinated jirds is initiated between the first and the second day after challenge and that killing occurs around the fourth day after challenge, before the worms undergo their first molt.

[Laboratory investigation of the chemical disinfection against different developmental stages of the housefly (Musca domestica Linnaeus, 1758)]. / Laboruntersuchungen zur chemischen Desinfektion gegen Entwicklungsstadien der Grossen Stubenfliege (Musca domestica LINNAEUS, 1758).

Possibilities for disinfection of the developmental stages from the housefly (Musca domestica) were investigated under laboratory conditions. The developmental stages (eggs, larvae I, II, III, pupae and adults) were sprayed with solutions of disinfectants on the basis of p-chlorine-m-cresol and o-phenylphenol at different concentrations (0.025%-3%). The effectiveness of both disinfectants was established by determining the emergence rate of eggs and pupae and of the live evidence of larvae and adults. Transmission electron microscopic investigations of the cover of the eggs revealed the bactericidal effect of both disinfectants. These results show the necessity of extending its use also to noxious arthropods.

Transient changes in length and growth of wheat coleoptile segments following treatments with osmotica and auxin.

The dependence of elongation on the osmotic potential of the medium was investigated, using coleoptile segments (CS) of Triticim aestivum L. (cv. Hartri) and an optoelectronic device. The study aimed at separating the osmoelastic response from the irreversible growth response when an osmoticum (mannitol) was added, and to compare both processes in order to consider the possibility of growth-induced reduction in turgor pressure. The prompt inhibition of elongation registered just after addition of 50 mM mannitol as well as the subsequent resumption of the original elongation rate could be quantitatively explained by the extent and the kinetics of the osmoelastic relaxation. An initial reduction in the irreversible elongation component by mild osmotic stress could not be demonstrated. Above a critical value, the irrevesible growth was insensitive to a further increase in water potential. The minimum turgor pressure required to drive steady growth was not far from zero in both the presence and absence of auxin. The rate (r) of osmotically caused shortening per unit change of water potential [Formula: see text] was determined from the kinetics of CS shortening induced by addition of mannitol at nearly isotonic concentration (300 mM). This parameter relates a fractional change in length to the difference in water potential between inside and outside, and was assumed to depend largely on the hydraulic resistance of the tissue and cuticle. It was found to be independent of IAA. The relatively low value of Γ suggests significant reduction of turgor at high growth rates. In accordance with this conclusion, the extent of osmoelastic shortening after a transfer to 300 mM mannitol (dependent on wall strain) was significantly decreased in the presence of IAA. Addition of 100 µM IAA to CS growing at a constant rate induced pronounced oscillations in the rate of elongation, which may be connected with the change in elastic cell wall strain. Whereas the steady state growth rate before the addition of IAA was the same in the presence and in the absence of 50 mM mannitol, the maximum growth rate found after addition of IAA was substantially reduced in the mannitol variant.

Rapid suppression of extension growth in dark-grown wheat seedlings by red light.

Continuous recordings were made using a linear displacement transducer to investigate short-term growth responses of intact dark-grown wheat (Triticum aestivum L. cv Maris Huntsman) seedlings to red light. To eliminate any effect of light prior to the experimental treatments, the seedlings were grown and mounted on the transducer apparatus in total darkness. The growth kinetics after irradiation were complex and appeared to consist of three successive phases of growth deceleration. When the tip of the intact coleoptile was irradiated with red light from two opposite fiber bundles (fluence rate: 2 x 64 micromoles per square meter per second) for varying periods of time (10 seconds, 1 minute, 5 minutes, continuous), a decrease in extension rate was detectable after a latent period of 8 to 10 minutes. Up to 30 minutes after the start of the irradiation treatment, there was no difference in the kinetics of inhibition (about 20 to 25% inhibition) between the different lengths of irradiation. Extension rate reached a minimum (65% inhibition) at about 85 minutes, after which growth acceleration toward the dark control rate was observed. Far-red reversibility of the rapid effect of red light on growth was not observed, even when far-red light was given only 4 seconds after the end of 10 seconds red light. Short (15 seconds) far-red light did not induce a response.