Role of histone H3 lysine 9 methylation in epigenetic control of heterochromatin assembly

The assembly of higher order chromatin structures has been linked to the covalent modifications of histone tails. We provide in vivo evidence that lysine 9 of histone H3 (H3 Lys9) is preferentially methylated by the Clr4 protein at heterochromatin-associated regions in fission yeast. Both the conserved chromo- and SET domains of Clr4 are required for H3 Lys9 methylation in vivo. Localization of Swi6, a homolog of Drosophila HP1, to heterochomatic regions is dependent on H3 Lys9 methylation. Moreover, an H3-specific deacetylase Clr3 and a beta-propeller domain protein Rik1 are required for H3 Lys9 methylation by Clr4 and Swi6 localization. These data define a conserved pathway wherein sequential histone modifications establish a "histone code" essential for the epigenetic inheritance of heterochromatin assembly.     

Soils of Eagle crater and Meridiani Planum at the Opportunity Rover landing site

The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.     

Laboratory earthquakes along inhomogeneous faults: directionality and supershear

We report on the experimental observation of spontaneously nucleated ruptures occurring on frictionally held bimaterial interfaces with small amounts of wave speed mismatch. Rupture is always found to be asymmetric bilateral. In one direction, rupture always propagates at the generalized Rayleigh wave speed, whereas in the opposite direction it is subshear or it transitions to supershear. The lack of a preferred rupture direction and the conditions leading to supershear are discussed in relation to existing theory and to the earthquake sequence in Parkfield, California, and in North Anatolia.     

提高杂交稻种子纯度海南种植鉴定质量的关键措施

根据多年从事杂交稻种子纯度海南种植鉴定的工作经历,分析了影响海南种植鉴定结果准确性的主要因素,提出了提高鉴定质量的关键措施: 严把种子扦样关、建立稳定的鉴定基地、调配高素质有经验的鉴定人员、采用科学的鉴定技术、实行集中鉴定制度、加强鉴定技术交流和培训.     

Reducing insecticide and fungicide loads in runoff from plastic mulch with vegetative-covered furrows

A common management practice for the production of fresh-market vegetables utilizes polyethylene (plastic) mulch because it increases soil temperature, decreases weed pressure, maintains soil moisture, and minimizes soil contact with the product. However, rain events afford much more erosion and runoff because 50-75% of the field is covered with an impervious surface. A plot study was conducted to compare and to quantify the off-site movement of soil, insecticides, and fungicides associated with runoff from plots planted with Sunbeam tomatoes (Lycopersicon esculentum Mill) using the conventional polyethylene mulch management practice vs an alternative management practice-polyethylene mulch-covered beds with cereal rye (Secale cereale) planted in the furrows between the beds. The use of cereal rye-covered furrows with the conventional polyethylene system decreased runoff volume by more than 40%, soil erosion by more than 80%, and pesticide loads by 48-74%. Results indicate that vegetative furrows are critical to minimizing the negative aspects of this management practice.     

Adenosquamous Carcinoma of the Trachea in a Domestic Ferret (Mustela putorius furo)

A 4-year-old, castrated, male domestic ferret (Mustela putorius furo) was evaluated for a possible upper respiratory tract infection and wheezing for approximately 3 weeks. Supportive care for a suspected upper respiratory tract infection was initiated; however, the patient became progressively more dyspneic over the next 48 hours. A possible tracheal mass was identified upon thoracic radiographic imaging of the ferret. Tracheoscopy and a computed tomography scan of the neck and thorax confirmed the presence of a tracheal mass approximately 3 cm from the larynx obstructing 80% of the tracheal lumen. Rather than pursuing surgical resection, the owners elected humane euthanasia. An adenosquamous carcinoma of the trachea was diagnosed after histologic analysis. This tumor type has been diagnosed in the lungs of ferrets that were experimentally exposed to carcinogens found in cigarette smoke; however, there are no previous reports of this or any other tumor type associated with the ferret trachea. A tracheal mass causing a partial upper airway obstruction should be considered within the differential disease diagnosis list when a ferret is presented with dyspnea.     

A framework for evaluating management plans comprehensively

We present a framework for evaluating fisheries management plans comprehensively, both rebuilding plans and others. The framework includes a first rapid appraisal of the likelihood that the plan will result in management meeting its objectives, and guides subsequent quantitative analyses of potential weaknesses in the proposed plan. The framework includes four steps: (i) evaluating if a set of management objectives, if achieved, would result in a sustainable fishery, (ii) using qualitative analysis of a bio‐economic model to evaluate whether the set of stock management tactics might be capable of achieving the specified fisheries objectives, (iii) using empirical criteria derived from the literature to evaluate if other management measures in the plan related to the ecological, social or economic context of the fishery actually contribute to sustainability, and (iv) carrying out quantitative simulations to compare alternative implementation options. Generally, several management measures have to be combined to increase stock size without sacrificing the economic benefits to the fishers remaining in the fishery. We demonstrate application of the framework for evaluating the stock rebuilding plan for plaice (Pleuronectes platessa) and sole (Solea solea) in the North Sea and, the management measures currently in place for the roundnose grenadier (Coryphaenoides rupestris) stock exploited to the west of the British Isles.     

水稻品种与稻瘟病菌分子指纹聚类互作分析初探

本试验进行了41个水稻品种的 GRA-PCR 和15个稻瘟病菌的 REP-PCR 分子指纹扩增和聚类分析;完成了品种和病菌互作人工接种试验。结果表明,供试品种的 GRA-PCR 指纹聚类后,以0.56遗传相似距离点划分时,供试的41个品种可分为两个遗传相似组,其中一组的19个品种大多数为云南省地方老品种,另一组的23个品种多数为近年来生产上的栽培品种。病菌 REP-PCR 指纹聚类后,在不同的相似距离划分时,获得不同的遗传相似组,当以0.08相似距离划分时,各遗传相似组的致病性与供试品种之间有一定的互作关系。