Effect of tetracycline residues in pig manure slurry on tetracycline-resistant bacteria and resistance gene tet(M) in soil microcosms

Effects of tetracycline residues from pig manure slurry on the prevalence of tetracycline-resistant bacteria and the tetracycline resistance gene, tet(M), were studied in soil microcosms. Four types of soil microcosms were established for a period of 152 days, supplemented with combinations of pig manure slurry and a tetracycline-resistant Enterococcus faecalis, CG110, containing the tetracycline resistance gene tet(M) (on the conjugative transposon, Tn916). The prevalence of both tetracycline-resistant aerobic bacteria and tetracycline-resistant enterococci declined rapidly until day 45 where no significant differences in the levels of tetracycline-resistant bacteria in any of the four types of microcosms could be detected. tet(M) could be detected in microcosms supplemented with either pig manure slurry and/or E. faecalis CG110 (tet(M)) for the whole period (152 days). tet(M) could be detected longer than tetracycline-resistant enterococci could be isolated (limit of detection 100 CFU/g soil) probably due to viable but not culturable (VBNC) bacteria with tet(M), horizontal gene transfer of tet(M) to indigenous soil bacteria or presence of "free" DNA. The concentration of chlortetracycline and oxytetracycline were almost stable through out the experimental period, but the tetracycline concentrations had no effect on prevalence of tetracycline-resistant bacteria. The presented microcosm approach simulated natural farmland conditions well and supported results from previous field studies.     

Annoyance due to aircraft noise has increased over the years—Results of the HYENA study

In the HYENA study (HYpertension and Exposure to Noise near Airports) noise annoyances due to aircraft and road traffic noise were assessed in subjects that lived in the vicinity of 6 major European airports using the 11-point ICBEN scale (International Commission on Biological Effects of Noise). A distinction was made between the annoyance during the day and during the night. L_den and L_night were considered as indicators of noise exposure. Pooled data analyses showed clear exposure–response relationships between the noise level and the noise annoyance for both exposures. The exposure–response curves for road noise were congruent with the EU standard curves used for predicting the number of highly noise annoyed subjects in European communities. Annoyance ratings due to aircraft noise, however, were higher than predicted by the EU standard curves. The data supports other findings suggesting that the people's attitude towards aircraft noise has changed over the years, and that the EU standard curve for aircraft noise should be modified.     

How floral odours are learned inside the bumblebee (Bombus terrestris) nest

Recruitment in social insects often involves not only inducing nestmates to leave the nest, but also communicating crucial information about finding profitable food sources. Although bumblebees transmit chemosensory information (floral scent), the transmission mechanism is unknown as mouth-to-mouth fluid transfer (as in honeybees) does not occur. Because recruiting bumblebees release a pheromone in the nest that triggers foraging in previously inactive workers, we tested whether this pheromone helps workers learn currently rewarding floral odours, as found in food social learning in rats. We exposed colonies to artificial recruitment pheromone, paired with anise scent. The pheromone did not facilitate learning of floral scent. However, we found that releasing floral scent in the air of the colony was sufficient to trigger learning and that learning performance was improved when the chemosensory cue was provided in the nectar in honeypots; probably because it guarantees a tighter link between scent and reward, and possibly because gustatory cues are involved in addition to olfaction. Scent learning was maximal when anise-scented nectar was brought into the nest by demonstrator foragers, suggesting that previously unidentified cues provided by successful foragers play an important role in nestmates learning new floral odours.     

Bees use three-dimensional information to improve target detection

Bumblebee detection of a flat circular disc (two-dimensional (2D) presentation) and a disc which was presented 10 cm in front of a structured background (and thus provided three-dimensional (3D) cues) was compared. A dual choice test using a Y-maze apparatus was conducted to estimate the minimum visual angle at which the bees were able to detect the disc. At large visual angles of 15, 10 and 5° bees’ performance between the 2D and the 3D presentation did not differ. However, when the disc subtended 3° at the bee’s eye, the bees performed significantly better when 3D information was available. Overall, bees were able to detect a target subtending a 40% smaller visual angle when it was presented in front of the structured background compared to a 2D presentation. This suggests that previous reports on the limits of target detection in bees using flat stimuli might have underestimated the bees’ ability to locate small flowers under natural conditions. Bees use motion parallax, i.e. the apparent relative motion of a stationary object against a background, for perceiving the third dimension. Our data suggest that bumblebees can integrate information from at least two types of feature detectors, motion and area, to improve single target detection.     

Size-resolved simulation of particulate matters and CO2 concentration in passenger vehicle cabins

Environmental Science and Pollution Research - The main aim of this study is to develop a mathematical size-dependent vehicle cabin model for particulate matter concentration including PM2.5...     

Altered menstrual cycles in women with a high dietary intake of persistent organochlorine compounds

Dietary exposure to persistent organochlorine compounds (POCs) has been found to affect the menstrual cycle in both animals and humans. In Sweden, the major exposure route for POCs is the consumption of fatty fish from the Baltic Sea. Thus, women who eat relatively large amounts of this fish constitute a suitable study group when investigating a possible association between dietary exposure to POC and menstrual cycle disruption. Questionnaires were sent to the exposed women, as well as to a socioeconomically similar cohort of controls, and information was collected on their menstrual cycles. Since the exposed women tended to smoke more than the controls, all results were adjusted for smoking habits. A cohort comparison found that the exposed women on average had 0.46 (95% confidence interval: 0.03, 0.89) days shorter menstrual cycles than controls. However, within the exposed cohort no effects were found of the proxy variables early life exposure and high consumption of Baltic Sea fatty fish. The results give some support to previous results from studies on women with similar exposure, but are not conclusive with respect to whether there is a causal association between POC exposure and menstrual cycle disruption.