高度杂波空间中 CF-FM 蝙蝠下丘回声定位的神经机制

蝙蝠是回声定位的专家。对于在高度杂波空间中捕食的CF-FM蝙蝠,面临着如何从发声和众多由背景环境物体反射的杂波回声中分辨和判断来自靶物的回声所携带信息的问题。已有研究表明,CF-FM蝙蝠可通过发出复杂成分的声脉冲,并通过听中枢的时相和频率整合来处理杂波环境下发声-回声对中包含的靶物距离和相对移动速度的信息。就以上方面在听中脑下丘的神经机制进行概述,以促进人们对听中枢在复杂听环境下对回声定位信号加工原理的认识。     

综述与专论: 蝙蝠，听觉和回声定位研究的模型动物

科学家以蝙蝠为模式动物,从听觉、回声定位和生态适应与演化等方面开展了研究,取得了令人瞩目的成果。为适应回声定位,蝙蝠听觉系统的结构和功能产生了明显的特化。从外周到中枢形成了对声频率极为有序的表征,甚至在恒频-调频（constant frequency-frequency modulation,CF-FM）蝙蝠耳蜗形成了所谓的听觉凹,以及听皮质功能组构也模块化,成为了具有代表性的特化象征。神经元反应的潜伏期对蝙蝠不仅是基本特性,也是回声定位行为调控的一部分;研究发现,有较长潜伏期的神经元具有较尖锐的回声-延迟调谐特性,而较短潜伏期的神经元则有较宽的回声-延迟调谐特性。蝙蝠听神经元对频率调谐的精准度亦远胜于人类和其他非回声定位动物;而且,源于耳蜗听觉凹的传入在各级听中枢均显示出对回声定位信号第二谐波CF成分的过度表征,以满足对靶物回声多普勒频移探测的需要。时程是回声定位蝙蝠发声信号主动改变的参数之一,而时程调谐神经元则提供了一种编码声音时相特征的重要神经机制,匹配了对回声定位信号时相信息加工的需要。在多种回声定位蝙蝠的听中枢还发现,有回声-延迟调谐神经元,它们不仅能对靶物距离进行调谐,而且...     

普氏蹄蝠下丘单反应和双反应神经元加工多普勒频移补偿信号的特点及生理机制

恒频-调频(constant frequency-frequency modulation,CF-FM)蝙蝠独特的多普勒频移补偿(Doppler-shift compensation,DSC)行为可保证其对回声信息的精确提取.那么听中枢加工DSC信号的适应性机制是什么?本实验模拟CF-FM蝙蝠DSC后的回声定位信号,研究下丘(inferior colliculus,IC)神经元加工DSC信号的特点及生理机制.实验共获得117个IC神经元,在CF-FM声刺激下,神经元表现为single-on(SO,n=83)和double-on(DO,n=34)两种反应模式.无论是在蝙蝠的正向还是负向补偿过程中,SO和DO神经元对回声反应恢复到50%时的双声刺激间隔(inter-pulse interval,IPI)值,均会随补偿条件的改变而发生变化.当双声刺激由无补偿转变为最佳补偿条件时,两类神经元的50%IPI显著缩短(P0.001),但SO神经元50%IPI缩短率超过70%的神经元数目较DO神经元多,且偏好正向补偿的IC神经元中,SO神经元的平均DSC范围也要显著宽于DO神经元(P0.05).该研究结果提示,IC中SO神经元可能较DO神经元更能充分利用蝙蝠DSC行为,来提高对回声反应的恢复能力,以最大程度地获取猎物信息并准确判断与猎物的相对速度.     

马铁菊头蝠不同行为下的回声定位叫声

蝙蝠回声定位的研究自50年代以来在世界范围内经久不衰,从行为生态学及神经生物学两方面研究回声定位又是该领域最近十几年的热点.其中从行为生态学角度主要研究蝙蝠回声定位对其所处生境及捕食行为的适应性;神经生物学则研究蝙蝠通过回声定位而"观察"周围世界的神经生理学基础.相比之下我国对蝙蝠的回声定位行为研究较少,孙心德等对鲁氏菊头蝠(Rhinolophus rouxi)进行过回避障碍物及听觉神经机理的研究,而对于蝙蝠回声定位超声波信号的研究则基本是空白.     

回声定位蝙蝠及其声通讯

综述了回声定位蝙蝠种类及其发声方式,回声定位信号的主要类型及回声定位信号声学特征,多普勒频移对长CF／FM蝙蝠的主要作用,简介了蝙蝠求偶和母婴识别等内声通讯行为,提出了一些尚待解决的重要问题。     

东方蝙蝠在交通噪声环境中的回声定位行为

环境噪声会降低动物声信号可探测性,是动物声信号进化的压力。为了避免人工噪声干扰,多数脊椎动物调整其叫声的频谱-时间结构,如采用延长叫声持续时间、提高频率和增加强度等策略。本研究选择回声定位声波频率范围与交通噪声频率范围相互重叠的东方蝙蝠(Vespertilio sinensis)为研究对象,在自然条件下开展实验,研究交通噪声对蝙蝠回声定位声波的影响。本实验选择交通噪声强度存在差异的两个样点,分别录制东方蝙蝠的回声定位声波,分析其结构参数。在交通噪声强度较高的样点,东方蝙蝠回声定位声波的持续时间、斜率均未显著改变,但起始频率、主频、终止频率及带宽均显著提高。结果表明,东方蝙蝠的回声定位行为在交通噪声干扰下具有明显的可塑性。     

马铁菊头蝠对同种咀嚼声的反应研究

咀嚼是哺乳动物食物吸收的重要组成部分,对动物的生存和繁殖极其重要。动物咀嚼时会发出低频低强度的咀嚼声,研究表明人类的咀嚼声可以增强自身或他人的食欲和愉悦度。蝙蝠作为哺乳动物中的第二大类群,其咀嚼声的特征和功能仍不清楚。本研究以吉林省集安市治安村的马铁菊头蝠Rhinolophus ferrumequinum为研究对象,通过回放蝙蝠咀嚼声和空白对照实验,同步录制蝙蝠的进食行为和回声定位声波,试图阐明蝙蝠咀嚼声对其进食行为和回声定位声波的影响。结果表明:进食次数在2种回放条件下的差异无统计学意义,但捕食尝试在2种回放条件下的差异有统计学意义。因此,咀嚼声能够显著地提高蝙蝠的进食欲望。此外,在蝙蝠咀嚼声的刺激下,其回声定位声波的频率增加,持续时间延长,脉冲速率减慢。这可能是因为蝙蝠在咀嚼声的影响下改变发声动机,从而改变了其回声定位声波的频谱时间结构。本研究第一次报道了蝙蝠咀嚼声对其进食行为的影响,为进一步阐明蝙蝠咀嚼声的功能和进化具有重要意义。     

食鱼蝙蝠形态和行为特化研究

总结了食鱼蝙蝠种类、分布 ,及其形态结构、回声定位功能和捕食行为的研究成果。比较食鱼蝙蝠与近水面“拖网式”食虫蝙蝠在形态、回声定位信号及捕食行为方面的异、同 ,推测食鱼蝙蝠起源于“拖网式”食虫蝙蝠类 ;体形和回声定位信号的几种特异性是捕食行为进化压力 ,而环境是决定因素。     

恒频-调频蝙蝠特化的听觉系统对回声定位的适应

在漫长的生物演化过程中,蝙蝠演化出了能飞行和高度适应生存环境的生物声纳系统和行为.蝙蝠属于哺乳动物纲的翼手目(Chiroptera),是唯一能真正飞行的哺乳动物,其种类超过1000种,位列哺乳类动物的第二大目.根据其体型大小和形态特征将其分成大蝙蝠亚目(Megachiroptera)和小蝙蝠亚目(Microchiroptera).对蝙蝠的研究具有重要的科学意义和实际应用价值,如在听感觉方面与人类共享听觉的某些基本原理,研究结果有助于认识人类听觉.它们发出的回声定位信号规整,便于模拟后用于研究听觉系统对声信号加工的机制,尤其是在听中枢对复杂声信号处理方面,认识其细胞和分子机制才刚开始,它们是极好的模型动物.另外,在仿生学方面也具有极其重要的价值,回声定位蝙蝠的生物声纳系统具有极高的时间和空间分辨率,是极具诱惑力的研究课题.有关恒频-调频蝙蝠听觉结构和功能的研究,已有相当的时日,获得了不少新的认识,窥探到敏锐的听觉与回声定位行为之间的某些适应性的机制,本文对这方面的研究进展做了简要介绍和评述.     

声刺激时程和模式影响大蹄蝠下丘神经元的恢复周期

本文旨在探讨声刺激时程及模式参量对恒频-调频(constant frequency-frequency modulation,CF-FM)蝙蝠下丘(inferior colliculus,IC)神经元恢复周期的影响。实验选用5只听力正常的大蹄蝠为实验动物,采用不同时程或不同模式的双声刺激,记录IC神经元的反应和恢复周期。结果共记录到169个IC声敏感神经元。依据神经元恢复率达到50%时的双声刺激间隔(interpulse interval,IPI)将神经元恢复周期分为三种类型:快速恢复型(fast,F),50%IPI为0～15ms;短时恢复型(short,S),50%IPI为15.1～30ms;长时恢复型(long,L),50%IPI30ms。在2、5和7ms时程的CF声刺激下,神经元50%IPI平均值随声刺激时程的增加,分别为(30.2±27.6)、(39.9±29.1)和(49.4±34.7)ms,F和S型神经元比例逐渐下降,而L型神经元比例逐渐上升。当声刺激模式由2msCF声转变为2msFM声时,F、S和L三种类型神经元比例分别由32.3%、41.5%、26.2%转变为47.7%、24.6%、27.7%,平均恢复周期缩短,由(30.2±27.6)减至(23.9±19.0)ms(P0.05,n=65)。与7msCF声刺激相比,5+2msCF-FM声刺激使F型神经元比例上升(18.2%→29.1%),S型神经元(29.1%→27.3%)和L型神经元(52.7%→43.6%)比例下降,平均恢复周期缩短,由(49.4±34.7)减至(36.3±29.4)ms(P0.05,n=55)。结果提示,CF-FM蝙蝠回声定位信号中的CF和FM成分在蝙蝠导航和捕食过程中分别扮演不同的角色,其中终末相中的FM成分主要使F型神经元数量增多,平均恢复周期缩短。FM成分在蝙蝠靠近靶物的过程中发挥重要作用以快速处理高脉冲重复率回声信息,它有利于准确计算目标距离和识别目标表面质地。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

真菌类遗传学分析的知识结构教学

本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。 Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

The mechanism of hatching of eggs of Haemonchus contortus

Fluid collected from hatching eggs of Haemonchus contortus contained a lipase which hydrolysed 2-naphthyl laurate (about 0·7 μmol naphthol freed /h/10⁶ eggs). The fluid also hydrolysed l-leucinamide (about 2·3 μmol leucine freed/h/10⁶ eggs). The fluid when added to normal or heated eggs caused ‘hatching’. ‘Hatching’ also occurred in exsheathing fluid from infective juveniles and in a preparation of pancreatic lipase containing leucine aminopeptidase. A purified mammalian leucine aminopeptidase in combination with several different lipases did not attack egg shells.The ‘spontaneous’ hatching of eggs of H. contortus was strongly inhibited by 1,10-phenanthroline, 10^?3M, and this inhibition was reversed by Zn²⁺. However, the inhibition of ‘hatching’ of eggs in externally applied hatching fluid, or the hydrolysis of leucinamide in hatching fluid was generally less marked.