Selection of aquatic microbiota exposed to the herbicides flufenacet and metazachlor

Herbicides are important, ubiquitous environmental contaminants, but little is known about their interaction with bacterial aquatic communities. Here, we sampled a protected natural freshwater habitat and characterised its microbiome in interaction with herbicides. We evolved the freshwater microbiomes in a microcosm assay of exposure (28 days) to flufenacet and metazachlor at environmental concentrations of 0.5, 5 and 50 μg L⁻¹. Inhibitory effects of herbicides were exemplarily assessed in cultured bacteria from the same pond (Pseudomonas alcaligenes, Paenibacillus amylolyticus and Microbacterium hominis). Findings were compared to long-term concentrations as provided by local authorities. Here, environmental concentrations reached up to 11 μg L⁻¹ (flufenacet) and 76 μg L⁻¹ (metazachlor). Bacteria were inhibited at minimum inhibitory concentrations far above these values; however, concentrations of 50 μg L⁻¹ of flufenacet resulted in measurable growth impairment. While most herbicide-exposed microcosm assays did not differ from controls, Acidobacteria were selected at high environmental concentrations of herbicides. Alpha-diversity (e.g., taxonomic richness on phylum level) was reduced when aquatic microbiomes were exposed to 50 μg metazachlor or flufenacet. One environmental strain of P. alcaligenes showed resistance to high concentrations of flufenacet (50 g L⁻¹). In total, this study reveals that ecologic imbalance due to herbicide use significantly impacts aquatic microbiomes.     

Oxytocin Influences Male Sexual Activity via Non-synaptic Axonal Release in the Spinal Cord

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frizzled 9 is expressed in neural precursor cells in the developing neural tube

The wnt signaling pathway has important functions in nervous system development. To better understand this process we have cloned and analyzed the expression of the wnt receptor, frizzled 9, in the developing nervous system in mouse, chick and zebrafish. The earliest expression of mouse frizzled 9 mRNA expression begins at E8.5 with expression throughout the entire rostral-caudal neuraxis. This early expression pattern within the neural tube appears to be conserved between chick and zebrafish. Expression becomes restricted to a ventral domain in the mouse ventricular zone at E11.5, a region specified to give rise to neurons and glia. Using a polyclonal antibody to MFZ9 further shows expression limited to neural restricted precursors cells.     

Image analysis of the stomatal cell walls of Picea abies (L.) Karst. in pure and ozone-enriched air

 The method of image analysis was used to re-investigate previously described structural changes in spruce needles following their exposure to ozone. The changes observed in fumigation experiments were compared with the modifications observed at a site with a similar ozone load. Use was made in each case of needles for which the varying behavioural patterns were known from physiological experiments. In samples with reduced ability to regulate stomatal aperture, the cell walls of the stomatal apparatus showed a reduction in absorptive power at 280 nm. This was interpreted to be a result of delignification of the cell walls in question due to the direct impact of ozone on the surface of the needle. Received: 21 May 1997 / Accepted: 30 June 1997     

The unique lungworms (Nematoda: Metastrongyloidea) of the opossum (Didelphis marsupialis linnaeus)

Summary Prestwoodia delicata (Travassos, 1946) Anderson, 1978, Heterostrongylus heterostrongylus Travassos, 1925 and Didelphostrongylus hayesi Prestwood, 1976 are redescribed on the basis of new collections of specimens from Didelphis marsupialis from North and South America. The three genera are unique to the opossum. Prestwoodia from the nasal sinuses is most similar to Troglostrongylus of Felidae. Heterostrongylus and Didelphostrongylus are similar in size and certain other features such as their six prominent lips and reduced bursae. The dorsal ray in the former, however, consists of a large, rounded lobe whereas in the latter, it is divided into two long branches. Didelphostrongylus is found under the pleura whereas Heterostrongylus is found in the bronchi. ac]19790102     

In vitro protein synthesizing activity of rat liver as influenced by a physiological dose of cortisone and dibutyryl cyclic AMP.

A single administration of a low dose of cortisone acetate (0.2 mg/100 g) into adrenalectomized rats reduces the cell-free protein synthesizing activity of isolated total liver polysomes by 60 % after 90 min. DBcAMP also inhibits markedly the protein synthesizing activity but its effect is due to an inactivation of soluble fraction. Combined administration of both drugs yields polysomes active more than twice than those of untreated control. Inhibition by the glucocorticoid was restricted only to the membrane-bound polysomes.