Circular mitochondrial DNA species from Oenothera with unique sequences

Summary Closed circular DNAs have been isolated from Oenothera and analysed by gel electrophoresis. A number of different size classes could be observed in the supercoiled fraction from the density gradient. The five smallest size classes of 6.3, 7.0, 8.2, 9.9, and 13.5 kilobases linear length were purified and their restriction fragment sizes compared. These five mtDNA species appear to be distinct homologous populations with no detectable large homologies between thedifferent classes. Hybridization data confirm this result; the smallest species hybridizes to itself and very weakly to some of the larger DNA molecules indicating only very little common sequence arrangement between the different circular DNAs. A restriction map of the smallest size class was constructed and confirms the circular arrangement of this DNA.Abbreviations used kb kilobases or kilobasepairs - mtDNA mitochondrial DNA - EthBr Ethidium bromide - SSC 150 mM NaCl, 15 mM sodium citrate (pH 7.0)     

Diurnal Variations in Swimming Activity of Rutilus rutilus (Cyprinidae) in a Group under Tank Conditions

Measurements of the swimming activity of a group of roach (12–19 cm TL, average) in a circular swimming chamber revealed two distinct activity patterns: a diurnal and a nocturnal one. The experiments showed that, having the choice, two factors stimulated the rhythmicity of the swimming behaviour of the fish, i.e. light intensity and the presence of a current field in the proximity of the fish. During daytime (bright light conditions) the fish moved into the current field and swam on average at 0.4 BL/s (resting swimming). The roach remained swimming at this speed even if no current field was established, however, then distributed evenly in the basin. By contrast, during night (dim light conditions) the fish predominantly chose the still water section but swam on average with a cruising speed of 1.6 BL/s (night swimming). Accordingly, they did not seek the still water section for night swimming if the light was kept on. Then again, the fish distributed more or less evenly in the basin. The results support the hypothesis that the fish migrate during night-time and do this preferably in still water.     

Degradation of Ciprofloxacin by Basidiomycetes and Identification of Metabolites Generated by the Brown Rot Fungus Gloeophyllum striatum

Ciprofloxacin (CIP), a fluoroquinolone antibacterial drug, is widely used in the treatment of serious infections in humans. Its degradation by basidiomycetous fungi was studied by monitoring ¹⁴CO₂ production from [¹⁴C]CIP in liquid cultures. Sixteen species inhabiting wood, soil, humus, or animal dung produced up to 35% ¹⁴CO₂ during 8 weeks of incubation. Despite some low rates of ¹⁴CO₂ formation, all species tested had reduced the antibacterial activity of CIP in supernatants to between 0 and 33% after 13 weeks. Gloeophyllum striatum was used to identify the metabolites formed from CIP. After 8 weeks, mycelia had produced 17 and 10% ¹⁴CO₂ from C-4 and the piperazinyl moiety, respectively, although more than half of CIP (applied at 10 ppm) had been transformed into metabolites already after 90 h. The structures of 11 metabolites were elucidated by high-performance liquid chromatography combined with electrospray ionization mass spectrometry and ¹H nuclear magnetic resonance spectroscopy. They fell into four categories as follows: (i) monohydroxylated congeners, (ii) dihydroxylated congeners, (iii) an isatin-type compound, proving elimination of C-2, and (iv) metabolites indicating both elimination and degradation of the piperazinyl moiety. A metabolic scheme previously described for enrofloxacin degradation could be confirmed and extended. A new type of metabolite, 6-defluoro-6-hydroxy-deethylene-CIP, provided confirmatory evidence for the proposed network of congeners. This may result from sequential hydroxylation of CIP and its congeners by hydroxyl radicals. Our findings reveal for the first time the widespread potential for CIP degradation among basidiomycetes inhabiting various environments, including agricultural soils and animal dung.     

Assessing the drivers of syphilis among men who have sex with men in Switzerland reveals a key impact of screening frequency: A modelling study

Over the last decade, syphilis diagnoses among men-who-have-sex-with-men (MSM) have strongly increased in Europe. Understanding the drivers of the ongoing epidemic may aid to curb transmissions. In order to identify the drivers of syphilis transmission in MSM in Switzerland between 2006 and 2017 as well as the effect of potential interventions, we set up an epidemiological model stratified by syphilis stage, HIV-diagnosis, and behavioral factors to account for syphilis infectiousness and risk for transmission. In the main model, we used ‘reported non-steady partners’ (nsP) as the main proxy for sexual risk. We parameterized the model using data from the Swiss HIV Cohort Study, Swiss Voluntary Counselling and Testing center, cross-sectional surveys among the Swiss MSM population, and published syphilis notifications from the Federal Office of Public Health. The main model reproduced the increase in syphilis diagnoses from 168 cases in 2006 to 418 cases in 2017. It estimated that between 2006 and 2017, MSM with HIV diagnosis had 45.9 times the median syphilis incidence of MSM without HIV diagnosis. Defining risk as condomless anal intercourse with nsP decreased model accuracy (sum of squared weighted residuals, 378.8 vs. 148.3). Counterfactual scenarios suggested that increasing screening of MSM without HIV diagnosis and with nsP from once every two years to twice per year may reduce syphilis incidence (at most 12.8% reduction by 2017). Whereas, increasing screening among MSM with HIV diagnosis and with nsP from once per year to twice per year may substantially reduce syphilis incidence over time (at least 63.5% reduction by 2017). The model suggests that reporting nsP regardless of condom use is suitable for risk stratification when modelling syphilis transmission. More frequent screening of MSM with HIV diagnosis, particularly those with nsP may aid to curb syphilis transmission.     

Limbic frontal cortex in hominoids: A comparative study of area 13

The limbic frontal cortex forms part of the neural substrate responsible for emotional reactions to social stimuli. Area 13 is one of the cortical areas long known to be part of the posterior orbitofrontal cortex in several monkey species, such as the macaque. Its presence nevertheless in the human brain has been unclear, and the cortex of the frontal lobe of the great and lesser apes remains largely unknown. In this study area 13 was identified in human, chimpanzee, bonobo, gorilla, orangutan, and gibbon brains, and cortical maps were generated on the basis of its cytoarchitecture. Imaging techniques were used to characterize and quantify the microstructural organization of the area, and stereological tools were applied for estimates of the volume of area 13 in all species. Area 13 is conservative in its structure, and features such as size of cortical layers, density of neurons, and space available for connections are similar across hominoids with only subtle differences present. In contrast to the homogeneity found in its organization, variation is present in the relative size of this cortical area (as a percentage of total brain volume). The human and the bonobo include a complex orbitofrontal cortex and a relatively smaller area 13. On the contrary the orangutan stands out by having a shorter orbitofrontal region and a more expanded area 13. Differences in the organization and size of individual cortical areas involved in emotional reactions and social behavior can be related to behavioral specializations of each hominoid and to the evolution of emotions in hominids. Am J Phys Anthropol 106:129–155, 1998. © 1998 Wiley-Liss, Inc.     

Dual function and associated costs of a highly exaggerated trait in a cichlid fish

Exaggerated secondary sexual characteristics are apparently costly and seem to defy natural selection. This conundrum promoted the theory of sexual selection. Accordingly, exaggerated secondary sexual characteristics might be ornaments on which female choice is based and/or armaments used during male–male competition. Males of many cichlid fish species, including the adaptive radiation of Nicaraguan Midas cichlids, develop a highly exaggerated nuchal hump, which is thought to be a sexually selected trait. To test this hypothesis, we conducted a series of behavioral assays in F2 hybrids obtained from crossing a species with a relatively small hump and one with an exaggerated hump. Mate‐choice experiments showed a clear female preference for males with large humps. In an open‐choice experiment with limited territories, couples including large humped males were more successful in acquiring these territories. Therefore, nuchal humps appear to serve dual functions as an ornament for attracting mates and as an armament for direct contest with rivals. Although being beneficial in terms of sexual selection, this trait also imposes fitness costs on males possessing disproportionally large nuchal humps since they exhibit decreased endurance and increased energetic costs when swimming. We conclude that these costs illustrate trade‐offs associated with large hump size between sexual and natural selection, which causes the latter to limit further exaggeration of this spectacular male trait.     

Comparison of subtraction arthrography, radionuclide arthrography and conventional plain radiography to assess loosening of total knee arthroplasty.

The value of plain radiographs, digital subtraction arthrography and radionuclide arthrography was analysed in 23 cases of failed total knee arthroplasty. The preoperative diagnosis was compared with the intraoperative assessment. Sensitivity, specificity and the positive and negative predictive value for assessing a loose component were determined separately for the femoral and tibial components. At revision we found 13 loose femoral and 12 loose tibial implants. In eight cases both components were unstable. Plain radiography had a sensitivity of 77% for loosening of the femoral and 83% for the tibial component; digital subtraction arthrography 77% for the femoral and 8% for the tibial component and radionuclide arthrography 31% and 8%. The specificity for plain radiography was 90% for the femoral and 72% for the tibial implant. For subtraction arthrography it was 50% and 82% and for subtraction arthrography 70% and 82%. Radiography had the highest positive and negative predictive values for both components compared with the other two techniques. As a diagnostic tool to detect implant loosening, plain radiography is the most effective in this study. Subtraction arthrography and radionuclide arthrography are not suitable for use as routine methods for detection of total knee arthroplasty loosening.