Sorption of polycyclic aromatic hydrocarbons (PAHs) to carbonaceous materials in a river floodplain soil

We report on sorption isotherm of phenanthrene (Phe) for river floodplain soil associated with carbonaceous materials, with particular attention being devoted to the natural loading of Phe. Our sorption experiments with original soil samples, size, and density sub-fractions showed that the light fraction had the highest sorption capacity comparable to low rank coals. In addition, the light fraction contributed most for the sorption of Phe in total soil samples. K_oc values for all fractions were in the same range, thus indicating that coal and coal-derived particles in all samples are responsible for the enhanced sorption for Phe. Sorption was strongly nonlinear and the combined partitioning and pore-filling model gave a better fit than the Freundlich sorption model. In addition, the spiked PAHs did not show the same behavior as the naturally aged ones, therefore the accessibility of indigenous background organic contaminants was reduced when coal and coal-derived particles are associated with the soils.     

In vivo binding of a biologically active oligopeptide in vegetative buds of the scyphozoan Cassiopea andromeda: demonstration of receptor-mediated induction of metamorphosis

Vegetative buds of Cassiopea andromeda (Cnidaria, Scyphozoa) metamorphose into polyps in the presence of short synthetic peptides containing proline as the preterminal amino acid at the carboxyl terminus. In an in vivo assay, the binding of the biologically active hexapeptide ¹⁴C-dansyl-GPGGPA in buds was shown to be specific and saturable. Scatchard plot analysis of the specific binding data revealed a dissociation constant (K _D) of about 7 M. The total number of receptors was calculated to be approximately 1×10¹⁰ bud^-1 under saturation conditions. In correlation with the results of prior investigations, our finding of receptor-mediated induction of metamorphosis strongly supports the hypothesis that binding of biologically active peptides to receptors leads to initiation of phosphatidylinositol breakdown and activation of protein kinase C.     

Anthropogenic impacts on natural nitrogen isotope variations in Pinus sylvestris stands in an industrially polluted area

Natural variations of the nitrogen isotopes 15N/14N (delta15N values) and the N concentrations of one-year-old needles from 7-12-year-old pine trees (Pinus sylvestris L.) were determined on 27 sites in the heavily polluted Leipzig-Halle region (former GDR). At three selected sites measurements were repeated over a period of 2 years. N concentrations and delta15N values in different needle age classes were compared at the three sites. The delta15N values of the N in the humus layer and the potential plant available N in the A(h) horizon of the local soil were determined. The 15N/14N isotope ratios (delta15N values) of one-year-old pine needles in the region of Leipzig-Halle were found to vary depending on their specific location by a factor of up to one order of magnitude (-9.6 per thousand to + 0.4 per thousand ). N concentrations in one-year-old pine needles varied between 0.71 and 1.38 mmol eq N g dw(-1). Pine stands with positive or slightly negative delta15N values and high N concentrations in one-year-old needles were concentrated around the cities of Leipzig and Halle and in the industrial areas. More negative delta15N values and lower N concentrations in one-year-old pine needles were found on sites at greater distances from the industrial agglomerations, mainly in the NE forested part. Site specific differences in the delta15N values of the N in the humus layer from three selected sites were similar to those found for the needles. No site specific differences, however, were found for the delta15N values of the water soluble nitrogen fraction from the mineral soil horizons of the same sites.     

Maturation,epitoky and regeneration in the polychaete Eunice siciliensis under field and laboratory conditions

In the gonochoric polychaetous annelid Eunice siciliensis Grube, germ cells only develop in the posterior segments of the worm; these segments subsequently differentiate into an epitokous portion separating at maturity from the infertile body part. As in the Pacific and Atlantic palolo worms, the epitokous portions die some hours after spawning. Laboratory investigations revealed that the anterior parts of spawned worms survive and regenerate genital segments. After a period of at least 8 months, paired gonads are developed in these segments. Gonia proliferating later from the germinal tissue are released from gonadal sacs into the coelomal cavities, where gamete development occurs. A reproductive epitokous portion does not mature and separate until the second year of cultivation; it is followed by caudal regeneration. These facts and the observation that only about 50% of the individuals obtained from samples of coralligène were sexually differentiated, led to the conclusion that E. siciliensis probably has a bi-annual reproductive cycle. Caudal regeneration does not depend on the presence of a prostomia hormone. The ability to form posterior regenerates is inherent to the parapodial segments of all body regions, except for mature genital segments. This is also valid for the formation of morphologically different secondary prostomia. However, for initiation and further promotion of gametogenesis and epitokous development, at least one gonadotropic factor originating from the prostomium is required. Neurosecretory cells within the brain suggest this factor(s) to be of neuro-endocrine nature. Specimens developing secondary prostomia were found both under field and laboratory conditions. In several cases, sexual development took place, and even epitokous portions were separated from such individuals. From this it appears that the gonadotropic functions are re-established by the regenerated prostomia in order to ensure reproduction in individuals accidentally deprived of the anterior end. The possible rôle of temperature and light as environmental factors involved in the control of normal and regenerative growth, of sexual development and reproduction is discussed.     

Concentrations and vertical fluxes of zooplankton fecal pellets on a continental shelf

The contribution of fecal pellets to the benthos of the southeastern shelf of the USA is investigated through an analytic model which considers pellet production by different stage groups of the genus Paracalanus. Model results indicate that the concentration and vertical flux of pellets is a function of producer size and consumer size and abundance. Nauplii and adults, respectively, produce daily on the average 50 and 13% of total pellet mass, yet contribute 4 and 63%, respectively, to the daily pellet flux. Most of the pellets produced are consumed or degraded in the water column, with only 0.2% of the average daily primary production reaching the seafloor (35 m) as fecal pellets. This contributes to an impoverished benthos, such as that found on the southeastern continental shelf.     

Nachweis der epitokie als fortpflanzungsmodus des polychaeten Eunice siciliensis (Polychaeta: Annelida)

Eunice siciliensis (Grube)¹ is a sedentary polychaete with separate sexes; its germ cells develop only in the posterior part of the body. In March and April, females with whitish or even dark-green oocytes, males with only few spermatogonia, and individuals with no germ cells at all were discovered in the “coralligène” of the Banyuls region (European Mediterranean Sea). In august, besides immature and sexually non-differentiated worms, mature individuals of both sexes were captured: females with dark bluish-green oocytes of diameters up to 250μm, and males with milky genital segments containing spermatozoa. Soon after isolation from the substrate, these individuals performed characteristic movements with their posterior body parts, which then autotomized, and released ova and spermatozoa. Evidence is given that the anterior, atokous body parts survive in their tubes in the “coralligène” after separation from the epitokous portions, and regenerate new genetal segments. The development of gametes observed in these regenerated segments indicates the ability of E. siciliensis to reproduce more than once during its lifetime. Not only caudal, but also prostomial regeneration was observed; the formation of a (morphologically different) secondary prostomium appears to be essential for any development of germ cells in worm fragments. E. siciliensis exhibits surprising similarities in habits and in formation of an epitokous form with Eunice viridis (Gray), the “palolo” worm of the South Pacific Ocean, but nevertheless, lacks the prominent criteria of this famous species: the ventral eye spots on each genital segment in males and females, and the paired areas with brown pigmentation on the ventral side of each epitokous segment in the males.     

Carbon metabolism and strobilation in Cassiopea andromedea (Cnidaria: Scyphozoa): Significance of endosymbiotic dinoflagellates

Scyphopolyps and scyphomedusae of Cassiopea andromeda Forskål (Cnidaria, Scyphozoa) containing dinoflagellate endosymbionts (zooxanthellae) were investigated for rates and pathways of carbon fixation. Photosynthesis by the algae, accounting for 80 and 15 mol C h^-1 on a dry weight basis in medusae and polyps, respectively, by far exceeds dark incorporation of inorganic carbon by the intact association. Photosynthetic carbon fixation is operated via C₃ pathway of carbon reduction. DCMU-treatment (1×10^-6 M and 1×10^-5 M) completely inhibits light-dependent carbon assimilation. Major photosynthates presumably involved in a metabolite flow from algal symbionts to animal tissue are glycerol and glucose. A total of 5–10% net algal photosynthate appears to be seleased in vivo to the host. This is probably less than the energy supply ultimately required for the nutrition of the polyps and medusae. The presence of zooxanthellae proved to be indispensable for strobilation in the scyphopolyps. However, photosynthesis by algal symbionts as well as photosynthate release is obviously not essential for the initiation of ephyrae as is shown by DCMU-treatment, culture in continous darkness, and aposymbiotic controls. It is therefore concluded that strobilation is supported, but not triggered by algal photosynthetic activity. The induction of strobilation thus seems to depend on a more complex system of regulation.     

How <Emphasis Type="Italic">Doratomyces stemonitis</Emphasis> copes with Benzoxazolin-2(3<Emphasis Type="Italic">H</Emphasis>)-one (BOA), its derivatives and detoxification products

Summary. Doratomyces stemonitis (Hyphomycetales, Dematiaceae) is a saprotrophic fungus belonging to the mycobiota of the cereal rhizosphere. The fungus is able to metabolize benzoxazolin-2-(3H)-one and a variety of its derivatives including higher plant detoxification products, microbial degradation products and the chemically rather stable 2-amino-(3H)-phenoxazin-3-one. D. stemonitis can use all of these compounds as sole C-sources but their utilization, especially that of microbial degradation products and 2-amino-(3H)-phenoxazin-3-one, seems to be highly energy consuming, resulting in slow mycelium growth and a change of colony morphology. Benzoxazolin-2-(3H)-one derived compounds induce the synthesis of different isoforms of a glycosylated protein with sequence homologies to the endo-1,3-β-glucanase Asp f2, an allergen from Aspergillus fumigatus and other Asp f2-like proteins e.g., from Verticillium dahliae or PRA1 antigen from Candida albicans. The induction of the protein is regarded as a stress response.