Potential susceptibility of Australian native plant species to branch dieback and bole canker diseases caused by Phytophthora ramorum

Susceptibility to branch dieback caused by Phytophthora ramorum was tested using a detached branch assay for 66 Australian native plant species sourced from established gardens and arboreta in California. Six of these species were further tested for their susceptibility to bole cankers caused by P. ramorum using a sealed log assay. Isopogon formosus and Eucalyptus denticulata were identified as potentially highly susceptible Australian branch dieback hosts. Thirteen potentially tolerant Australian host species included Banksia attenuata, B. marginata, E. haemastoma, E. regnans, Pittosporum undulatum and Billardiera heterophylla. Eucalyptus regnans was identified as a potentially highly susceptible bole canker host, while E. diversicolor and E. viminalis were considered potentially tolerant species to bole cankers caused by P. ramorum. Phytophthora ramorum was able to infect all 66 species, as confirmed by reisolation. These results extend the known potential host range for P. ramorum, confirm it as a possible threat to Australian plant industries and ecosystems and highlight additional associated hosts that are important in the global horticultural trade, native forests and plantation forestry.     

不同水分条件下苔藓结皮光合能力对氮素添加量的响应

[目的]探究苔藓结皮失水过程中光合能力对不同梯度氮添加的响应,为进一步研究苔藓结皮对氮沉降的响应过程以及为干旱、半干旱区荒漠生态系统的管理提供理论依据。[方法]选取毛乌素沙地的优势藓种拟双色真藓(Bryum pachytheca)为研究对象,在控制条件下采用氮添加的模拟试验手段。[结果]苔藓结皮净光合速率在低于0.2g/(m2·a)的氮添加量时受到促进,在高于0.2g/(m2·a)的氮素添加量下,低水分含量时被抑制,高水分含量时会受促进;同时,0.2g/(m2·a)是苔藓结皮能承受的最优氮添加量,此时苔藓结皮的光合固碳能力达到最大,年光合固碳量为对照条件的2倍。[结论]氮沉降引起的氮素增加对于干旱、半干旱区苔藓结皮的光合能力以及固碳潜力具有显著的影响。     

A cross-sectional study of geriatric horses in the United Kingdom. Part 1: Demographics and management practices

Reasons for performing study: With growing numbers of aged horses, geriatric medicine is becoming increasingly important in equine veterinary practice; however, there is a paucity of information on the UK equine geriatric population. Objectives: To describe the demographic characteristics of the equine geriatric population and to assess management practices undertaken by owners of geriatric horses (aged ≥15 years). Methods: A cross‐sectional study was conducted, surveying a randomly selected sample of veterinary registered owners with horses aged ≥15 years, using a self‐administered postal questionnaire. Results: Horses aged ≥15 years represented 29% of the equine population in the study area. The response rate to the questionnaire survey was 80.2%. Management practices were similar to those previously described for the general equine population. However, the level of exercise and feeding practices changed significantly with increasing age. A summary of the demographic characteristics, feeding and management of horses in a sample of the geriatric equine population is presented. Conclusions and potential relevance: The management of geriatric horses has a direct effect on their health and welfare and this study has provided valuable information on the demographics and management of geriatric horses and ponies in the UK. The information can be used to form targeted owner education programmes for geriatric health and should aid in the investigation and prevention of disease.     

Impact of lower atmospheric carbon dioxide on tropical mountain ecosystems

Carbon-isotope values of bulk organic matter from high-altitude lakes on Mount Kenya and Mount Elgon, East Africa, were 10 to 14 per mil higher during glacial times than they are today. Compound-specific isotope analyses of leaf waxes and algal biomarkers show that organisms possessing CO2-concentrating mechanisms, including C4 grasses and freshwater algae, were primarily responsible for this large increase. Carbon limitation due to lower ambient CO2 partial pressures had a significant impact on the distribution of forest on the tropical mountains, in addition to climate. Hence, tree line elevation should not be used to infer palaeotemperatures.     

New tetromycin derivatives with anti-trypanosomal and protease inhibitory activities

Four new tetromycin derivatives, tetromycins 1-4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001(T) cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy as well as HRESIMS analysis. The compounds were tested for antiparasitic activities against Leishmania major and Trypanosoma brucei, and for protease inhibition against several cysteine proteases such as falcipain, rhodesain, cathepsin L, cathepsin B, and viral proteases SARS-CoV M(pro), and PL(pro). The compounds showed antiparasitic activities against T. brucei and time-dependent inhibition of cathepsin L-like proteases with K(i) values in the low micromolar range.