中国华北地区瓜类尖孢镰刀菌对咪鲜胺的敏感性及抗药突变株生物学性状研究

为明确中国华北地区瓜类尖孢镰刀菌Fusarium oxysporum Schl.对咪鲜胺的抗药性现状及抗药突变株的生物学性状,采用菌丝生长速率法,分别测定了采自北京、山东、河北等地未使用过咪鲜胺的112株瓜类尖孢镰刀菌对咪鲜胺的敏感性,并通过药剂驯化的方法获得尖孢镰刀菌抗咪鲜胺突变株。结果表明:咪鲜胺对112株瓜类尖孢镰刀菌的平均EC50值为（0.030 1±0.030 4）μg/mL,菌株频率呈连续单峰曲线分布,未发现敏感性明显下降的亚群体,因此,可将该EC50值作为瓜类尖孢镰刀菌对咪鲜胺的敏感基线。药剂驯化共获得7株抗咪鲜胺突变株,其抗性倍数介于6.2~26.8之间;突变株在菌丝生长速率、菌丝干重和致病力等方面均明显低于亲本菌株,差异显著;仅突变株HG13052701-R1的抗药性可以稳定遗传,其他6株抗咪鲜胺突变株的抗药性均不能稳定遗传。室内交互抗性测定结果表明,咪鲜胺仅与戊唑醇之间有交互抗性,与多菌灵和齅霉灵之间均无交互抗性关系。研究表明,瓜类尖孢镰刀菌在药剂选择压下可以形成抗咪鲜胺群体,具有低等抗药性风险。     

Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis

In ruminants, the ruminal epithelium not only has the function of absorbing nutrients but also is an important tissue to prevent harmful substances in the rumen from entering the blood circulation. Thus, the normal function of ruminal epithelium is critical for ruminants. However, subacute ruminal acidosis induced by high-concentrate diets often damages the barrier function of ruminal epithelium in ruminants. Recently, many studies have shown that dietary supplementation with thiamine is an effective method to alleviate subacute ruminal acidosis. In order to provide theoretical reference for the in-depth study of subacute ruminal acidosis and the application of thiamine in the future, this review introduces the effects of subacute ruminal acidosis on morphological structure, inflammatory response, and tight junction of ruminal epithelium. In addition, this paper summarizes the role of thiamine in maintaining ruminal epithelial function of ruminants during subacute ruminal acidosis challenge.     

Application of an electrometric method for measurement of blood cholinesterase activities in sheep, goats and cattle treated with organophosphate insecticides

A modified electrometric cholinesterase method has been described for use in ruminants exposed to organophosphate insecticides. The method was used to measure cholinesterase activities in the plasma and erythrocytes of sheep, goats and cattle treated with organophosphate insecticides under field conditions. The animals were treated topically to control ectoparasites with malathion (0.05%) or diazinon (0.06%). The treated animals did not suffer from adverse effects related to cholinesterase inhibition. However, 2 h after treatments, plasma and erythrocyte cholinesterase activities significantly decreased in sheep by 20% and 39% and in goats by 18% and 30%, respectively, when compared with respective untreated control values. Diazinon did not significantly affect plasma and erythrocyte cholinesterase activities in the cattle. The results suggest that the described electrometric method could be efficiently used for detecting cholinesterase inhibition in ruminants exposed to organophosphate insecticides.     

Resource allocation tradeoffs in Manila’s peri-urban vegetable production systems: An application of multiple objective programming

This paper designed and developed a multi-objective programming (MOP) model to illustrate the dynamic relationship among technologies, productive activities, constraints and farmers’ objectives in the peri-urban vegetable production system and use the model as an economic tool in analysing probable consequences of a given action or innovation on the farm. The best compromise solution was generated using four analytical steps, as follows: single-objective optimization (to determine the ideal and anti-ideal values of the objective functions); constrained optimization (to generate the set of Pareto non-dominated solutions); cluster analysis (to trim down efficient set into smaller homogeneous groups); and compromise programming (to determine where the best compromise solution lies).     

Antimycotic Screening of 58 Malaysian Plants against Plant Pathogens

Ethanolic extracts of 58 Malaysian plants belonging to 24 different families were screened for antifungal activity against seven plant pathogens using the filter paper disc diffusion technique. Two varieties of Piper betle, showed strong activity against all the pathogens tested (Colletotrichum capsici, Fusarium pallidoroseum, Botryodiplodia theobromae, Alternaria alternata, Penicillium citrinum, Phomopsis caricae-papayae and Aspergillus niger), with inhibition diameters significantly (P<0·01) bigger than 2·5 mg ml⁻¹ prochloraz or 10 mg ml⁻¹ clotrimazole. The minimum inhibitory concentrations of the ethanolic extracts of P. betle against these plant pathogens ranged between 0·01 mg ml⁻¹ and 1 mg ml⁻¹. Thirty-four other plants (Kucing gala, Limau batik, Bertholletia excelsa, Bixa orellana, Caesalpinia pulcherrima, Cerbera odollam (fruits and leaves), Colocasia gigantea, Curcuma domestica, Curcuma manga, Derris eliptica, Elephantopus scaber, Eleusine indica, Eugenia polyantha, Euphorbia hirta, Euphorbia tirucalli, Gardenia florida, Hedyotis auricularia, Hibiscus rosa-sinensis, Juniperus chinensis (three varieties), Lawsonia inermis, Lecythis ollaria, Mentha arvensis, Mimusops elengi, Ocimum sanctum, Phyllanthus niruri, Piper nigrum, Piperomia pellucida, Pedilanthus tithymaloides, Polygonum minus, Spondias dulcis, Solanum nigrum, Tinospora tuberculata) showed selective antifungal activity, while 21 species were inactive.     

Ecological and Industrial Implications of Dynamic Seaweed-Associated Microbiota Interactions

Seaweeds are broadly distributed and represent an important source of secondary metabolites (e.g., halogenated compounds, polyphenols) eliciting various pharmacological activities and playing a relevant ecological role in the anti-epibiosis. Importantly, host (as known as basibiont such as algae)–microbe (as known as epibiont such as bacteria) interaction (as known as halobiont) is a driving force for coevolution in the marine environment. Nevertheless, halobionts may be fundamental (harmless) or detrimental (harmful) to the functioning of the host. In addition to biotic factors, abiotic factors (e.g., pH, salinity, temperature, nutrients) regulate halobionts. Spatiotemporal and functional exploration of such dynamic interactions appear crucial. Indeed, environmental stress in a constantly changing ocean may disturb complex mutualistic relations, through mechanisms involving host chemical defense strategies (e.g., secretion of secondary metabolites and antifouling chemicals by quorum sensing). It is worth mentioning that many of bioactive compounds, such as terpenoids, previously attributed to macroalgae are in fact produced or metabolized by their associated microorganisms (e.g., bacteria, fungi, viruses, parasites). Eventually, recent metagenomics analyses suggest that microbes may have acquired seaweed associated genes because of increased seaweed in diets. This article retrospectively reviews pertinent studies on the spatiotemporal and functional seaweed-associated microbiota interactions which can lead to the production of bioactive compounds with high antifouling, theranostic, and biotechnological potential.     

Response of industrial hemp to Salsola kali subsp. tragus densities under organic and conventional fertilisation

A 2-year field study was conducted to determine the effects of different nutrition systems and Salsola kali subsp. tragus densities on industrial hemp yield and its components. Experiments were conducted as a split plot in a randomised complete block design with three replicates. Factors were fertilisation (poultry manure, vermicompost and nitrogen fertiliser) as the main plot and weed density (0, 5, 10, 15 and 20 plants/m²) as the subplot. Results indicated that the maximum number of racemes per plant, seeds per raceme, 1000-seed weight, biomass, grain yield and harvest index (HI) of industrial hemp were obtained using vermicompost and were reduced with nitrogen fertiliser application. All measured properties in hemp plants decreased due to increasing S. kali subsp. tragus density, especially at 15 and 20 plants/m². The most significant reduction in hemp grain yield and its components was observed by increasing weed density with the application of nitrogen fertiliser. The application of vermicompost at high weed densities resulted in greater hemp grain yield and its components compared with nitrogen fertiliser. It is recommended to apply organic fertilisers, especially vermicompost at high S. kali subsp. tragus densities.