Biosolid-borne tetracyclines and sulfonamides in plants

Tetracyclines and sulfonamides used in human and animal medicine are released to terrestrial ecosystems from wastewater treatment plants or by direct manure application. The interactions between plants and these antibiotics are numerous and complex, including uptake and accumulation, phytometabolism, toxicity responses, and degradation in the rhizosphere. Uptake and accumulation of antibiotics have been studied in plants such as wheat, maize, potato, vegetables, and ornamentals. Once accumulated in plant tissue, organic contaminants can be metabolized through a sequential process of transformation, conjugation through glycosylation and glutathione pathways, and ultimately sequestration into plant tissue. While studies have yet to fully elucidate the phytometabolism of tetracyclines and sulfonamides, an in-depth review of plant and mammalian studies suggest multiple potential transformation and conjugation pathways for tetracyclines and sulfonamides. The presence of contaminants in the vicinity or within the plants can elicit stress responses and defense mechanisms that can help tolerate the negative effects of contaminants. Antibiotics can change microbial communities and enzyme activity in the rhizosphere, potentially inducing microbial antibiotic resistance. On the other hand, the interaction of microbes and root exudates on pharmaceuticals in the rhizosphere can result in degradation of the parent molecule to less toxic compounds. To fully characterize the environmental impacts of increased antibiotic use in human medicine and animal production, further research is essential to understand the effects of different antibiotics on plant physiology and productivity, uptake, translocation, and phytometabolism of antibiotics, and the role of antibiotics in the rhizosphere.     

Soil-Atmosphere exchange of radiatively and chemically active gases

Exchanges between the soils and the atmosphere may control or significantly affect the global budgets of many environmentally important trace gases, both natural and man-made. Flux measurements, taken in several ecosystems, show that soils are a substantial source of chloroform (8 ± 4 μg/m²/d) and a sink for methyl chloride (-10 _-3 ⁺⁶ μg/m²/d). The known sources and sinks of these gases are insufficient to explain the observed concentrations. Our findings will help to balance the global budget of chloroform but may put the budget of methyl chloride further out of balance. We also found, consistent with previous research, that soils are a substantial source of nitrous oxide and carbon monoxide and take up hydrogen and methane. The uptake of man-made chlorocarbons was observed, but the rates are small. Observed fluxes of non-methane hydrocarbons showed few patterns except that soils may be a source of ethane and butane.     

Sex linkage among genes controlling sexually selected traits

Using literature data on reciprocal crosses I estimated the influence of sex-chromosomal genes on morphological and behavioral traits. To determine a special role of the sex chromosomes for sexually selected traits, I compared the estimated influence of X-chromosomal genes on sexually selected traits with their estimated influence on traits not under sexual selection. About one-third of the phenotypic variation in sexually selected traits is caused by X-chromosomal genes. There was, in contrast, no significant influence of X-chromosomal genes on traits that were classified as not sexually selected. Sexually selected traits thus seem to be influenced significantly more by X-chromosomal genes than traits not under sexual selection. Though this differential influence of X-chromosomal genes cannot readily be explained with current theoretical knowledge, it may shed some light on X-linked hybrid sterility and on the discussion between arbitrary and good-gene models for the evolution of female choice. Received: 30 January 1998 / Accepted after revision: 20 June 1998     

Expositionsszenarien nach REACH

Object and Background

Production and use of substances and formulations can result in exposures on humans and the environment. In October 2003, the European Commissions presented a proposal for the registration, evaluation, assessment and restriction of chemicals (REACH). Assessment of exposures will become an essential element of REACH for certain substances. For many manufacturers and users of substances and formulations these tasks are new. Pilot projects to REACH have shown so far that solutions and instruments for these tasks which meet the requirements of real life situations have yet to be developed.

Discussion and Conclusions

Within the REACH proposal, exposure scenarios are a main element of the chemical safety assessment. This article outlines the contents of exposure scenarios. It reflects experiences with exposure scenarios and discusses possibilities of standardization. It covers exposure steps/categories and possibilities to build product groups. Non-branch specific types of exposure situations are an important element of exposure scenarios. Therefore, exposure steps/categories should be contained in exposure scenarios. Nevertheless, these elements structure only a specific part of the information contained in exposure scenarios. Hence they cannot replace exposure scenarios. Exposure categories do not reveal the uses, the processes and the activities connected with the intended use of substances. These information are important parts of a complete exposure scenario. They are the basis for the following step of risk characterisation. In addition, they provide the necessary transparency regarding the use patteern of substances.     

Evolution of a new sense for wind in flying phasmids? Afferents and interneurons

The evolution of winged stick insects (phasmids) from secondarily wingless ancestors was proposed in recent studies. We explored the cuticle of flying phasmids for wind sensors that could be involved in their flight control, comparable to those known for locusts. Surprisingly, wind-sensitive hairs (wsH) occur on the palps of mouthparts and on the antennae of the winged phasmid Sipyloidea sipylus which can fly in tethered position only when air currents blow over the mouthparts. The present study describes the morphology and major functional properties of these “new” wsH with soft and bulging hair bases which are different from the beaker-like hair bases of the wsH on the cerci of phasmids and the wsH described in other insects. The most sensitive wsH of antennae and palps respond with phasic-tonic afferents to air currents exceeding 0.2 ms⁻¹. The fields of wsH on one side of the animal respond mainly to ventral, lateral, and frontal wind on the ipsilateral side of the head. Afferent inputs from the wsH converge but also diverge to a group of specific interneurons at their branches in the suboesophageal ganglion and can send their integrated input from wsH fields of the palps and antennae to the thoracic central nervous system. Response types of individual wsH-interneurons are either phasic or phasic-tonic to air puffs or constant air currents and also, the receptive fields of individual interneurons differ. We conclude that the “new” wsH system and its interneurons mainly serve to maintain flight activity in airborne phasmids and also, the “new” wsH must have emerged together with the integrating interneurons during the evolution from wingless to the recent winged forms of phasmids.