Cadmium exposure of rainbow trout, Salmo gairdneri Richardson: effects on immune functions

Differential leucocyte counts, phagocytosis, humoral antibody response and the in vitro blasto-genetic response to mitogens (lipopolysaccharide and Concanavalin A) and to an antigen ( Vibrio anguillarum ) were studied in rainbow trout exposed to 0,0.7 or 3.6 μg Cd 1⁻¹ for 12 weeks.
Although the fish did not exhibit any clinical or histological changes, cadmium exposure was found to affect two of the immune parameters measured. The cellular response of fish immunized with V. anguillarum to the homologous antigen was significantly lower for splenocytes obtained from fish exposed to cadmium for 9 weeks (3.6 μg Cd 1⁻¹ group) than for splenocytes obtained from non-exposed fish. Conversely, the humoral antibody response to V. anguillarum O-antigen was higher in the 3.6 μg Cd 1⁻¹ group than in the non-exposed group. Protective immunity of fish vaccinated against V. anguillarum was equally as good in the cadmium-exposed group as in the non-exposed group. No cadmium-induced changes in differential leucocyte counts or in the proportions of phagocytic cells were observed.     

Correlation between two components of parental investment: nest defence intensity and nestling provisioning effort of willow tits

Nest defence intensity and nestling provisioning effort of female willow tits (Parus montanus) were significantly correlated at the end of nestling period: well-fed young were defended most intensely. Increased effort was rewarded, since broods with the highest female per-offspring provisioning rates were the most likely to produce local recruits. This suggests that the feeding ability is an important cue for parental investment decisions, at least in a species like the willow tit which has adopted the clutch adjustment strategy. Thus, the most valuable broods would not necessarily be the largest ones, but the ones in which the original number of young could be fed most adequately. However, no associations were found between the level of parental effort and offspring weight, size or condition, nor did the broods producing recruits differ from other broods in timing of breeding or number and size of offspring. The female behaviour may suggest that they invest the most time, energy and risk in the young whose chances of joining the winter flock are the best. The first well-fed young also gain an advantage of prior residency in joining the flock. The first to join normally obtain higher social status, and hence better winter survival, than latecomers. The corresponding patterns in male parental investment behaviour were weak or absent, which suggested that the male effort was affected by the female behaviour. Males seemed to invest in nestling provisioning in such a way as to supplement the female effort. During nest defence action males also seemed to invest in protection of females against predation.     

Chemo- and karyotaxonomic studies on some rhizomatous species of the genusSymphytum (Boraginaceae)

InS. tuberosum subspp.tuberosum andnodosum, S. grandiflorum andS. ibericum the presence of the pyrrolizidine alkaloids lycopsamine, echimidine and symphytine could be demonstrated. The taxonS. tuberosum contains an unknown compound that seems to be specific for this taxon. This compound is not the pyrrolizidine alkaloid anadoline which has previously been reported for this species. It is possibly represented by a peak on GC/MS with a molecular ion peak at m/z 623 (as TMS derivative) and can be used as a chemotaxonomic marker for the speciesS. tuberosum. The pyrrolizidine alkaloid pattern of the two subspecies ofS. tuberosum reinforces the close relationship. Fresh material ofS. tuberosum contained the triterpene isobauerenol, but in herbarium material isobauerenol was lacking. InS. grandiflorum, neither fresh nor dried material contains isobauerenol. In herbarium material ofS. ibericum also no isobauerenol could be found. More extensive chemotaxonomical research is necessary to support the view thatS. abchasicum is more closely related toS. ibericum than toS. grandiflorum.     

Tests of associational defence provided by hairy plants for glabrous plants of Arabidopsis halleri subsp. gemmifera against insect herbivores

1. Trichome‐producing (hairy) and trichomeless (glabrous) plants of Arabidopsis halleri subsp. gemmifera were investigated to test whether plant resistance to herbivory depends on the plants' phenotypes and/or the phenotypes of neighbouring plants (associational effects). 2. A common garden experiment was conducted in which the relative frequency of hairy and glabrous plants was manipulated. Two species of leaf‐chewing insects (larvae of a white butterfly and a cabbage sawfly) were found less often on hairy plants than on glabrous plants. By contrast, the numbers of aphids and flea beetles did not differ significantly between hairy and glabrous plants. For none of these insects did abundance depend on the frequency of the two plant morphs. 3. A field survey was conducted in two natural populations of A. halleri. In the first population, a species of white butterfly was the dominant herbivore, and hairy plants incurred less leaf damage than glabrous plants across 2 years. By contrast, in the other population, where flea beetles were dominant, there were no consistent differences in leaf damage between the two types of plants. In neither of the two populations was any evidence found of associational effects. 4. This study did not provide any conclusive evidence of associational effects of anti‐herbivore resistance, but it was discovered that trichomes can confer resistance to certain herbivores. Given the results of previous work by the authors on associational effects against a flightless leaf beetle, such associational effects of the trichome dimorphism of A. halleri were herbivore‐specific.     

Actin pegs and ultrastructure of presumed sensory receptors of Beroë (Ctenophora)

Summary We have investigated the actin content and ultrastructure of two kinds of presumed sensory projections on the lip epidermis of beroid ctenophores. Transmission electron microscopy showed that conical pegs contain a large bundle of densely packed, parallel microfilaments. Rhodamine-phalloidin brightly stained the pegs, confirming that they contain filamentous actin. Epidermal cells with actin pegs also bear a single long cilium with an onion-root structure, previously described as arising from a different type of cell. The actin peg and onion-root cilium project side-by-side, defining a polarized axis of the cell which is shared by neighboring cells. The onion-root body is surrounded by a flattened membranes sac which lies immediately below the plasma membrane. The perimeter of the membrane sac is encircled by aggregates of dense material. An extra layer of dense material is found along the side of the membrane sac facing the peg; this material often makes direct contact with the adjacent actin filament bundle. Cells with actin pegs and onion-root cilia synapse onto adjacent neurites and secretory gland cells, indicating that one or both types of projections are sensory elements. Since the feeding responses of beroids are reported to depend on chemical and tactile stimuli to the lips, the cells bearing pegs and cilia may function as both mechanoreceptors and chemoreceptors, that is, as double sensory receptors.     

In Situ emulsification and mobilization of gasoline range hydrocarbons using surfactants

In this article the conditions that govern surfactant‐enhanced emulsification and mobilization of petroleum hydrocarbons in soil are reviewed. The effect of soil properties, groundwater constituents, and differing surfactant solutions on the emulsification process is discussed. A constant head soil flushing apparatus used to characterize surfactant‐enhanced mobilization of m‐xylene is described. Data showing the effect of surfactant‐enhanced mobilization on m‐xylene removal efficiency in washed sand is presented. Flushing solutions were used at concentrations from below to well above the critical micelle concentration (CMC) of the surfactants used. Removal efficiencies are shown to vary with surfactant concentration and with surfactant type. Flushing solutions of anionic, nonionic, and anionic/nonionic surfactant mixtures were evaluated.