微生物菊粉酶基因结构、酶学性质与应用研究进展

综述了微生物菊粉酶基因结构、酶学性质、发酵生产与应用等方面研究的最新进展。     

OBSERVATIONS ON THE ATTACK BY THE STEM EELWORM, DITYLENCHUS DIPSACI, ON STRAWBERRY

Four biologic races of Ditylenchus dipsaci can cause stem eelworm disease on twelve varieties of strawberry, all but one cultivated in Great Britain. The course of attack on strawberry, host reaction and the ways in which the disease originates and is disseminated are described.     

ON THE RELATION BETWEEN TOXICITY,RESISTANCE, AND TIME OF SURVIVAL,AND ON RELATED PHENOMENA

1. A relation between toxicity, resistance, and time of survival has been derived on the basis of the assumption that the time is a function of a parameter which is the difference between the toxicity and the resistance. Toxicity and resistance act like forces which can maintain an equilibrium-like (or stationary) state. If the equilibrium is upset, the time at which the event (death) occurs is proportional to the logarithm of the difference between toxicity and resistance. 2. It was found that if values proportional to the resistance are calculated with the proposed equation and the percentage mortality plotted against them (instead of against the time as is usual) symmetrical curves are obtained even though the corresponding mortality-time curves are asymmetrical. Assuming that the resistance varies like an error, that is, according to probability rules, theoretical mortality-time curves, similar to the experimental curves, can be constructed from the proposed equations. 3. In the case of a toxic agent acting on a unicellular organism suspended in solution, the toxicity is proportional to the adsorbed amount of the agent, as calculated with the aid of the Langmuir equation. In small concentration ranges the toxicity can be taken as approximately proportional to the concentration. 4. The variation of the temperature affects mainly the constant a which is a function of the temperature similar to that of the velocity constant of a chemical reaction (Arrhenius'' law). 5. The proposed equation has been tested in four different combinations of the variables, concentration, resistance, time, and temperature. The agreement with the experiments is satisfactory. 6. Any noxious agent acting on a unicellular organism may be characterized by three constants: r, the resistance, which is the threshold value at which the agent is still fatally toxic for the organism; a, the reciprocal of the rate constant determining the specific rate (that is, the time corresponding to a difference of 1 between the toxicity and the resistance); and finally the constant γ of the function representing the relation between toxicity and concentration.     

云南哀牢山徐家坝中山湿性常绿阔叶林动态和节律的研究

根据多年定位观察资料,包括从组成种的种子萌发、幼苗生长及成年物种的生长规律和物候节律对湿性常绿阔叶林动态和节律的研究,结果表明：林地种子贮量、可萌发种子量和萌发种数,雨季大于旱季。幼苗生长雨季快于旱季。表明雨季是种子萌发、幼苗生长的最佳季节。立木生长是种间竞争、自我调控、自疏的过程。成年物种各物候期长、不明显与温带阔叶林各物候期短、明显不同,而开花、结果、落果终年进行与西双版纳季节雨林物候节律相似。三者的不同在于季节雨林春季（２～３ 月）落叶,常绿阔叶林冬季（１１～１２ 月）落叶,温带阔叶林秋季（９～１０ 月）落叶。依据物种物候节律特点及其对气候环境的反应区分出３ 种生态物候型：１．暖温生态物候型（占总种数（５０）的８２％ ）;２．温性生态物候型（占１２％ ）;３．温凉生态物候型（占０．６％ ）     

ON CONSENSUS, COLLAPSIBILITY, AND CLADE CONCORDANCE

Abstract — Consensus in cladistics is reviewed. Consensus trees, which summarize the agreement in grouping among a set of cladograms, are distinguished from compromise trees, which may contain groups that do not appear in all the cladograms being compared. Only a strict or Nelson tree is an actual consensus. This distinction has implications for the concept of support for cladograms: only those branches supported under all possible optimizations are unambiguously supported. We refer to such cladograms as strictly supported, in contrast to the semistrictly (ambiguously) supported cladograms output by various current microcomputer programs for cladistic analysis. Such semistrictly supported cladograms may be collapsed, however, by a variety of options in various programs. Consideration of collapsibility and optimization on multifurcations leads to some conclusions on the use of consensus. Consensus tree length provides information about character conflict that occurs between, not within, cladograms. We propose the clade concordance index, which employs the consensus tree length to measure inter-cladogram character conflict for all characters among a set of cladograms.     

哀牢山北段主要森林类型凋落物的研究

 本文研究了哀牢山北段东西坡垂直带上分布的7种森林凋落物的数量、组成、动态变化和化学元素归还量,为了解我国西南季风区山地森林凋落物的养份归还规律,对亚热带山地森林的经营、土壤资源合理的开发、保护及生产力的提高提供了依据。     

A NOTE ON THE ACTION OF CURARE,ATROPINE, AND NICOTINE ON THE INVERTEBRATE HEART

1. The alkaloids (curare, atropine, and nicotine) in molluscs and arthropods stimulate and paralyze the central nervous system and peripheral (visceral) ganglia, but do not paralyze the motor nerve endings to skeletal or visceral muscle. 2. They stimulate and paralyze the denervated heart. 3. They paralyze or block the cardioinhibitory nerves, but not the cardioaccelerator nerves. 4. In the Limulus heart these drugs act primarily on the heart ganglion, not on the heart muscle or the intrinsic motor nerve fibers.