Plant diseases and their control by biological means in Cuba

Beginning in 1989, the breakup of the Soviet Bloc disrupted trade and cut off Cuba's source of subsidized fuel oil, making many modern agricultural practices impossible, including the wide use of pesticides. Among Cuba's responses was an emphasis on biological control of plant diseases. Research into biological control began in the 1930s, and after the revolution many scientists maintained an unofficial interest. When the 1989 economic crisis occurred, the government placed a high priority on biocontrol, and researchers were in a position to begin immediate implementation. For example, the construction of factories for the mass production of biological agents had been approved in 1988, and are currently in operation. Disease monitoring was undertaken before the current crisis, with more than 90% of Cuban agriculture using it to some extent. Such monitoring has allowed a reduction in pesticide use. Since the 1989 onset of economic crisis the monitor system has not been greatly modified for use with biological control techniques, but an example of a successful transition from chemical treatment to biocontrol in Cuba is in banana plantations. At the various research centers, research is being conducted in the biocontrol of vegetable diseases, tobacco root diseases, nematodes, and pasture weeds. Technical research is being done on mass production of inoculum, the production of application formulations, and storage of biocontrol products. Because wide use of biocontrol agents was urgently desired, the government cooperated at every step of research, including in regulatory matters. Obstacles to successful biocontrol mentioned by Cuban scientists were the lack of taxonomic knowledge and the need for strict quality control. There are few economic studies of biocontrol agents despite the importance of such studies. Cuban scientists are in an excellent position to do such research. Forced by the economic crisis to act, Cuba has made a major change in national agronomic policy that may represent a significant and new direction for “modern” agricultural practices.     

Patterns of participation in farmers’ research groups: Lessons from the highlands of southwestern Uganda

There is increasing interest in farmers’ organizations as an effective approach to farmer participatory research (FPR). Using data from an empirical study of farmers’ research groups (FRGs) in Uganda, this paper examines the patterns of participation in groups and answers questions such as: Who participates? What types of participation? How does participation occur? What are the factors determining participation? Results show that there is no single type of participation, but rather that FPR is a dynamic process with types of participation varying at different stages of the process. Farmers’ participation does not follow the normal adoption curve. Rather, it is characterized by high participation at the initial stages, followed by dramatic decrease and dropping-out, and slow increases toward the end. There is usually significantly higher participation among male farmers at the beginning of the process. However, as FRGs evolve, the proportion of men decreases sharply while the relative proportion of women continues to increase until it dominates the group. The findings do not support the common assumption that groups usually exclude women and the poor. On the contrary, we argue that FRGs are an effective mechanism to provide women and the poor with opportunities to participate in research. However, to be effective, this requires moving beyond head counting to promote more proactive gender and equity perspectives for amplifying the benefits of agricultural research to those who tend to be marginalized or excluded by mainstream development initiatives. This will be critical for making agricultural research more client-oriented and demand-driven.     

Structures of SAS-6 suggest its organization in centrioles

Centrioles are cylindrical, ninefold symmetrical structures with peripheral triplet microtubules strictly required to template cilia and flagella. The highly conserved protein SAS-6 constitutes the center of the cartwheel assembly that scaffolds centrioles early in their biogenesis. We determined the x-ray structure of the amino-terminal domain of SAS-6 from zebrafish, and we show that recombinant SAS-6 self-associates in vitro into assemblies that resemble cartwheel centers. Point mutations are consistent with the notion that centriole formation in vivo depends on the interactions that define the self-assemblies observed here. Thus, these interactions are probably essential to the structural organization of cartwheel centers.     

Bactericidal kinetics of marine-derived napyradiomycins against contemporary methicillin-resistant Staphylococcus aureus

There is an urgent need for new antibiotics to treat hospital- and community-associated methicillin-resistant Staphylococcus aureus (MRSA) infections. Previous work has indicated that both terrestrial and marine-derived members of the napyradiomycin class possess potential anti-staphylococcal activities. These compounds are unique meroterpenoids with unusual levels of halogenation. In this paper we report the evaluation of two previously described napyradiomycin derivatives, A80915A (1) and A80915B (2) produced by the marine-derived actinomycete, Streptomyces sp. strain CNQ-525, for their specific activities against contemporary and clinically relevant MRSA. Reported are studies of the in vitro kinetics of these chemical scaffolds in time-kill MRSA assays. Both napyradiomycin derivatives demonstrate potent and rapid bactericidal activity against contemporary MRSA strains. These data may help guide future development and design of analogs of the napyradiomycins that could potentially serve as useful anti-MRSA therapeutics.     

Simple and sensitive determination of o-phenylphenol in citrus fruits using gas chromatography with atomic emission or mass spectrometric detection

In this work, a simple and sensitive method for the analysis of the pesticide o-phenylphenol (OPP) on citrus fruits was developed. OPP is extracted with dichloromethane by ultrasonication and derivatized with ferrocenecarboxylic acid chloride. Using ferrocene as a label, residues of OPP are determined by gas chromatography with atomic emission detection in the iron selective mode or with mass spectrometric detection. Sample cleanup is simple and rapid and merely involves a removal of excess reagent on an alumina minicolumn. The method detection limit is 2 ng of OPP/g of fruit, and recoveries from lemon samples fortified at levels of 35 and 140 ng/g are 101 and 106%, respectively. The citrus fruits analyzed (oranges, grapefruits, lemons) contained between 60 ng/g and 0.37 microg/g OPP (RSD = 8-13%), and the results were in good agreement with results obtained when OPP was analyzed using an established HPLC-FLD method. Several alcohols could also be identified in the fruit peel.     

Thermography as an early predictive measurement for evaluating epidural and femoral–sciatic block success in dogs

Objective

To evaluate skin temperature increase as an early predictive measure for evaluating epidural and femoral-sciatic block success in dogs.

Development of a method for detection of latent European fruit tree canker (<Emphasis Type="Italic">Neonectria ditissima</Emphasis>) infections in apple and pear nurseries

Fruit tree canker caused by Neonectria ditissima is a serious problem in apple-producing regions with moderate temperatures and high rainfall throughout the year; especially in northwestern Europe, Chile, and New Zealand. Control measures are applied to protect primary infection sites, mainly leaf scars, from invasion by external inoculum. However, latent infections may occur when young apple trees are infected symptomlessly during propagation. This study aimed to develop a method for detection of latent fruit tree canker infections. Inoculations with conidiospore suspensions of N. ditissima were carried out in tree nurseries on the main stems of two-year-old trees of three apple cultivars and one pear cultivar. The inoculations were carried out during the natural abscission period in the autumn. No visible lesion or canker formations were present at the time when the inoculated trees were uprooted. It appeared that the infections may remain latent during the period from infection to uprooting (2 months) and during the subsequent 4 months of cold storage of the trees. Nevertheless, symptoms were generally induced within 8 weeks after transfer of infecting planting material from the nursery field into a climate chamber with high temperature and high relative humidity. The methodology presented is developed to detect latent infections of N. ditissima in nursery trees, prior to planting in the orchards, and it may contribute in reducing the problem with European fruit tree canker in commercial production.     

Soil water storage appears to compensate for climatic aridity at the xeric margin of European tree species distribution

Based on macroecological data, we test the hypothesis whether European tree species of temperate and boreal distribution maintain their water and nutrient supply in the more arid southern margin of their distribution range by shifting to more fertile soils with higher water storage than in their humid core distribution range (cf. soil compensatory effects). To answer this question, we gathered a large dataset with more than 200,000 plots that we related to summer aridity (SA), derived from WorldClim data, as well as soil available water capacity (AWC) and soil nutrient status, derived from the European soil database. The soil compensatory effects on tree species distribution were tested through generalized additive models. The hypothesis of soil compensatory effects on tree species distribution under limiting aridity was supported in terms of statistical significance and plausibility. Compared to a bioclimatic baseline model, inclusion of soil variables systematically improved the models’ goodness of fit. However, the relevance measured as the gain in predictive performance was small, with largest improvements for P. sylvestris, Q. petraea and A. alba. All studied species, except P. sylvestris, preferred high AWC under high SA. For F. sylvatica, P. abies and Q. petraea, the compensatory effect of soil AWC under high SA was even more pronounced on acidic soils. Soil compensatory effects might have decisive implications for tree species redistribution and forest management strategies under anthropogenic climate change. Therefore, soil compensatory effects deserve more intensive investigation, ideally, in studies combining different spatial scales to reduce the uncertainty associated with the precision of soil information.     

日粮中碳水化合物类型对多鳞白甲鱼幼鱼生长性能、体组成及健康状况的影响

为探究多鳞白甲鱼幼鱼日粮中最佳碳水化合物添加类型，以葡萄糖、麦芽糖、糊精、玉米淀粉及纤维素5种碳水化合物为糖源，分别配制5种日粮，对多鳞白甲鱼幼鱼进行了为期56 d的养殖实验。结果显示，(1)生长及饲料利用率方面，麦芽糖组的终末体重、特定生长率、饵料系数以及蛋白质效率等指标最佳，纤维素组最差。(2)体成分方面，纤维素组全鱼粗脂肪水平最低，粗灰分水平显著高于麦芽糖组，麦芽糖组及纤维素组肌糖原含量最低，糊精组肝糖原含量最低。(3)主成分分析表明，C16:0、SFA、MUFA和PUFA比例对肝胰脏脂肪酸比例产生主要影响，其中，C16:0和SFA比例在麦芽糖组显著提高，MUFA比例在糊精组显著提高，而PUFA在纤维素组显著提高；C18:1n-9和MUFA比例对肌肉和脂肪组织总体脂肪酸组成产生主要影响，二者比例在麦芽糖组显著提高。(4)血清生化指标方面，麦芽糖组及纤维素组谷丙转氨酶活性、麦芽糖组谷草转氨酶活性显著较高，葡萄糖组及纤维素组碱性磷酸酶活性、球蛋白含量较高，而血糖含量反之。(5)抗氧化能力方面，麦芽糖组肝胰脏过氧化氢酶、总超氧化物歧化酶、谷胱甘肽过氧化物酶活性最高，纤维素组丙二醛含量最...