疫病菌遊走子のうの多量形成培養法(農学部門)

無菌的かつ簡単に多量の遊走子のうを形成させるための新しい方法を試案した。供試菌はPhytophthora capsici No. 65である。培地としては, 菌糸の生育良好で, 良質の遊走子のうを形成するものとしてV8ジュースを選出した。100mlのフラスコに入れた30mlの液体培地中で, 28℃, 3週間, 前培養した菌そうを, ブフナー滬斗を用いて, 殺菌水にてよく洗浄し, あらかじめ, 湿った滬紙2枚を敷いておいたペトリ皿に移し, 障子紙を張った木枠のふたをかぶせ, 螢光灯照明付28℃定温器中に並べておくと, 36∿48時間後, 表面に多量の遊走子のうの形式がみられた。この遊走子のうは気中性で, 小型の薬さじで容易にかき取ることができる。本法はP. palmivolaおよびP. melonisにも適用して多量の遊走子のうを得たが, P. parasitica, P. citrophthoraおよびP. heveaeでは満足すべき結果が得られなかった。A new method for obtaining abundant zoosporangia of Phytophthora spp. is described in this paper. The V-8 juice medium was favorable for both mycelial growth and zoosporangium formation of Phytophthora capsici Leon. No. 65. Thirty ml of the medium in each of 100ml Erlenmeyer flask was sterillized by autoclaving at 121℃ for 15 minutes. This medium was inoculated with a 5mm diam. disk of mycelium grown on potato dextrose agar plate at 28℃ for a week. After 3 week incubation period at 28℃, mycelial mat was removed from the flask, and rinsed with sterilized deionized water through a Buchner funnel with a sheet of filter paper (Fig. 1). The clean mycelial mat then put on 2 sheets of moistened filter paper in a Petri dish. The Petri dish was covered with a special paper lid (Fig. 2), and placed in a 30℃ incubator illuminated with fluoresent lamp. One of the important points of this method is to use the paper lid instead of the ordinary glass lid of Petri dish. The paper lid keeps the surface of mycelial mat in moderately dry condition. The another point is to illuminate with fluorescent lamp. Both dry condition and illumination seems to be very effective for sporangium production by this fungus. Numerous zoosporangia were formed on the surface of mycelial mat after 36-48 hours. They were easilly collected by a small spatula. This method has so far been found to be applicable to P. palmivola and P. melonis, but not to P. parasitica, P. citrophthora and P. heveae. In general, this method seems to be practicable for the fungi which produce aboundant spores on the surface of the host plant in field

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements