Polar wandering on Mars?

Polar wandering during the past 10(8) years may be recorded by unique quasi-circular structures in the polar regions of Mars. Polar wandering on Mars is likely if deep convection is involved in the origin of the very large constructional volcanic features located near the equator. The magnitude of the nonhydrostatic low order components of the gravity field and their correlation with the equatorial volcanic features may be additional evidence of deep convection and associated polar wandering.     

Intraspecific variation in the 16S rRNA gene sequences of Mycoplasma agalactiae and Mycoplasma bovis strains

Intraspecific variation in the 16S rRNA genes of 17 Mycoplasma agalactiae and eight Mycoplasma bovis isolates was investigated to determine the degree of sequence variation in these two species and to determine whether the polymorphisms in the 16S rRNA genes could be used for the construction of an evolutionary tree and as epidemiological markers. A high degree of variation was found within isolates (between operons) and between isolates of both species. In contrast to M. capripneumoniae no distinct evolutionary pattern could be seen, probably because there are functional systems for gene conversion in M. agalactiae and M. bovis. However, the non-European isolates of M. agalactiae shared three characteristic nucleotides and European isolates from the same or neighbouring countries were very similar. Differences within isolates included both polymorphic positions and sequence length differences between operons. The amount of variation within isolates of the respective species ranged from zero to seven polymorphisms for M. agalactiae and from zero to four polymorphisms for M. bovis. The high degree of variation suggests the potential for misdiagnosis of species in diagnostic PCR assays based on the 16S rRNA gene sequences. All isolates of both species had a thymidine in position 912 (E. coli numbering) that causes streptomycin resistance in several bacterial species and which is characteristic for the members of the hominis group. As expected, when five M. agalactiae and three M. bovis isolates were tested for streptomycin susceptibility, they all demonstrated streptomycin resistance. M. agalactiae and M. bovis were found to have high intraspecific variation in their 16S rRNA gene and the polymorphisms patterns indicate that gene conversion takes place.     

Imaging of small-scale features on 433 Eros from NEAR: evidence for a complex regolith

On 25 October 2000, the Near Earth Asteroid Rendevous (NEAR)-Shoemaker spacecraft executed a low-altitude flyover of asteroid 433 Eros, making it possible to image the surface at a resolution of about 1 meter per pixel. The images reveal an evolved surface distinguished by an abundance of ejecta blocks, a dearth of small craters, and smooth material infilling some topographic lows. The subdued appearance of craters of different diameters and the variety of blocks and different degrees of their burial suggest that ejecta from several impact events blanketed the region imaged at closest approach and led to the building up of a substantial and complex regolith consisting of fine materials and abundant meter-sized blocks.     

Net primary productivity-based factors of China's carbon intensity: A regional perspective

Reducing carbon intensity (CI) is one of the core steps of climate change mitigation. This study emphasized the roles of ecological services and regional heterogeneity in determining CI. We considered heterogeneities based on geography and income and explored the roles of net primary productivity (NPP)-based carbon footprint and CI in the changes in China's CI over 2001−2015 using an extended production-theoretical decomposition analysis and matching the socio-economic data sets with NPP data from a remote sensing satellite. We found that group technological change, reflecting the effect of shrinkage or expansion of the group best practice frontier, and the potential NPP-based carbon footprint, reflecting the impact of energy-related CO₂ emissions on ecological carbon absorption, are the most significant factors accounting for the increase and decrease in CI, respectively, while NPP-based CI generally accounts for the decline in CI. We further showed that the technology gap change exhibited by an invert U-shaped curve contributed to the increase in CI under geography-based heterogeneity. We advise that China's policies should be more focused on ecological factors and regional heterogeneity in regions with abundant NPP (e.g., Yunnan and Sichuan) to further reduce CI.     

Anthrax outbreak in a Swedish beef cattle herd - 1st case in 27 years: Case report

After 27 years with no detected cases, an outbreak of anthrax occurred in a beef cattle herd in the south of Sweden. The outbreak was unusual as it occurred in winter, in animals not exposed to meat-and-bone meal, in a non-endemic country.The affected herd consisted of 90 animals, including calves and young stock. The animals were kept in a barn on deep straw bedding and fed only roughage. Seven animals died during 10 days, with no typical previous clinical signs except fever. The carcasses were reportedly normal in appearance, particularly as regards rigor mortis, bleeding and coagulation of the blood. Subsequently, three more animals died and anthrax was suspected at necropsy and confirmed by culture and PCR on blood samples.The isolated strain was susceptible to tetracycline, ciprofloxacin and ampicillin. Subtyping by MLVA showed the strain to cluster with isolates in the A lineage of Bacillus anthracis.Environmental samples from the holding were all negative except for two soil samples taken from a spot where infected carcasses had been kept until they were picked up for transport.The most likely source of the infection was concluded to be contaminated roughage, although this could not be substantiated by laboratory analysis. The suspected feed was mixed with soil and dust and originated from fields where flooding occurred the previous year, followed by a dry summer with a very low water level in the river allowing for the harvesting on soil usually not exposed. In the early 1900s, animal carcasses are said to have been dumped in this river during anthrax outbreaks and it is most likely that some anthrax spores could remain in the area.The case indicates that untypical cases in non-endemic areas may be missed to a larger extent than previously thought. Field tests allowing a preliminary risk assessment of animal carcasses would be helpful for increased sensitivity of detection and prevention of further exposure to the causative agent.     

Strategies for administration of biosurfactant-producing pseudomonads for biocontrol in closed hydroponic systems

Zoospore-producing oomycetes are major plant pathogens of particular concern in hydroponic systems. Compared with pesticides, biocontrol using antagonistic microorganisms is a sustainable approach to control oomycetes. Previous research has demonstrated that biosurfactants and biosurfactant-producing microorganisms are potentially useful components of a sustainable biocontrol strategy.In this study three ways of supplying a biosurfactant-producing strain to a recirculating hydroponic cultivation system infected with a zoospore-producing plant pathogen were evaluated. The strain Pseudomonas koreensis 2.74 was added as washed cells, in its spent KB broth or in a minimal medium adapted from the nutrient solution, and compared with control treatments. A significant reduction in disease with up to 50% was achieved when a high concentration of washed cells was added weekly to the plant cultivation system. The disease suppression obtained through addition of washed cells equalled the effect achieved when the purified biosurfactant was used. Phytotoxicity was observed when the spent broth was included in the treatment.     

Morphology and composition of the surface of Mars: Mars Odyssey THEMIS results

The Thermal Emission Imaging System (THEMIS) on Mars Odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness, implying temporal changes in the processes or environments during or after their formation. Kilometer-scale exposures of bedrock are observed; elsewhere airfall dust completely mantles the surface over thousands of square kilometers. Mars has compositional variations at 100-meter scales, for example, an exposure of olivine-rich basalt in the walls of Ganges Chasma. Thermally distinct ejecta facies occur around some craters with variations associated with crater age. Polar observations have identified temporal patches of water frost in the north polar cap. No thermal signatures associated with endogenic heat sources have been identified.     

北京粮经产业结构调整成效及下一步调整方向思考

北京农业作为特大城市战略性基础产业,其每一阶段的发展调整,都服从和服务于不同时期城市功能定位和城乡建设需要,该研究针对2014年北京开启的以农业节水、减排调粮及做精畜牧水产为主题的新一轮农业结构调整,以北京粮经产业为研究对象,总结了实施农业结构调整政策以来北京粮经产业结构调整的主要做法及成效,结合新形势及北京农业发展实际,提出下一步粮经产业调整的主要发展思路。     

The influence of disturbance and habitat on the presence of non-native plant species along transport corridors

The impact from transportation corridors on surrounding habitat often reaches far beyond the edge of the corridor. The altered disturbance regime in plant communities along corridor edges and vehicle traffic facilitate the spread and establishment of invasive non-native plant species. We compared the frequency of non-native plant species along highways and railways and the ability of these species to invade grasslands and dense forests along these corridors. We measured the frequency of several non-native plant species along transects 0-150 m from the edge of highways and railways in grasslands and forests, as well as at control sites away from corridors. Both transportation corridors had higher frequency of non-native species than respective control sites. Grasslands had higher frequency of non-native species than forested habitats, but the frequency did not differ between the highways and the railways. The frequency of non-native species in grasslands along highways and railways was higher than at grassland control sites up to 150 m from the corridor edge, whereas the frequency in forested habitats along corridors was higher than at forested control sites up to only 10 m from the corridor edge. There was a significant decrease in the frequency of non-native species with increasing distance from both corridors in the forest, while grasslands showed no significant change in non-native species frequency with distance from corridors. This suggests that corridor edges and grassland habitats act as microhabitats for non-native species and are more prone to invasion than forests, especially if disturbed. Our results emphasize the importance of minimizing the disturbance of adjacent plant communities along highways and railways during construction and maintenance, particularly in grassland habitats and in areas sensitive to additional fragmentation and habitat loss.