蚤类足跗节细微结构的扫描电镜观察

本文报道4科18属26种蚤类足附节的扫描电镜观察结果, 发现了蚤类足咐节上的若干种感器和类似于爪垫的结构.感器的形式主要是毛形感器和刺形感器;以爪垫结构位于副爪下方, 具有许多微小棘毛.爪与副瓜对应面上均具有横纹.多数种类第5跗节蹠面上具有许多感觉毛, 其数量和分布在不同种甚至两性之间均有差异, 拟可用于分类鉴定.根据第5跗节侧蹠鬃的数目及本研究第一部分感觉板上感觉室的数目对所观察的4科蚤类进行了分型, 并对其进化地位进行了讨论.     

雄蚤生殖节的扫描电镜观察

本文利用扫描电镜对雄蚤生殖节表面细微结构进行了观察,发现了一些光镜下不易看到的纹理状结构和小棘及一些感器.这些微小的纹理状结构和小棘在不同蚤种之间有差异,这种差异具有相对的稳定性,可望用于蚤的亚显微水平的分类.通过对感器的观察,发现生殖节上具有大量的毛形感器,另外还观察到有锥形感器、短锥形感器、钟形感器、栓锥感器、腔锥感器及刺形感器等.这些感器的数量分布及有无因种而异.这些感器的存在与交配行为密切相关,作者对此也进行了讨论.     

三种蚤臀板的发育(英)

本文研究了缓慢细蚤L.segnis不等单蚤M.anisus和猫栉首蚤指名亚种C.felis felis的臀板发育,详细观察了上述蚤种幼虫至成虫臀板、肛节的内部结构变化。认为在早期三龄幼虫,臀板芽开始出现在第10腹节背板前1/2处中部;在前蛹期第11腹节明显可见并由肛背叶和肛腹叶组成;在蛹期臀板充分发育,臀板载板在雌蚤外面由9背板,内面由10背板融合而成,而在雄蚤外面由9背板,内面由10背板和阳茎副叶基段的背突融合而成。本文对一直有争议的臀板、肛节起源问题进行了讨论。     

雄蚤阳茎体的研究：角叶蚤科三种雄蚤阳茎体的观察

用光镜和扫描电镜观察鞋形共系蚤Syngenopsyllus calceatus (Rothochild)、无值大锥蚤Macrostylophora euteles (Jordan et Rothschiold)和不等单蚤Monopsyllus anisus(Rothechild)的阳茎体侧面、背面和腹面。其中三种蚤阳茎体的背、腹面和无值大锥蚤阳茎体的侧面形态结构是首次报道。鞋形共系蚤有一对明显的阳茎囊突和一对与其相连的"c-骨片", 首次报道该蚤具有前距。无值大锥蚤具一对“茄形骨片”,阳茎钩突末端分为长而宽的腹叶和短而末端尖的背叶,阳茎内突后半部分特化为“后阳茎内突”。三种蚤的钩突桩略呈牛角形,由后弯向前。三种蚤阳茎体的形态结构差异显著,指出了它们是分类上值得注意的特征。认为交配时阳茎杆只在一定范围内作定向滑动。将阳茎体从蚤体内解剖出来,并且观察其背腹面,有助于清晰、完整和准确地观察其形态结构。     

网蝽科十一属昆虫体表感觉结构的电镜观察

对在扫描电子显微镜下观察到的网蝽科(半翅目：异翅亚目)11个属18种网蝽的成虫及2种的若虫体表感觉结构的特征进行了比较,并根据体表感觉器官的主要特征将所观察的11个属大致划分为6个类群;进一步证实了体表感觉结构的差异性在属水平上的分类学意义,认为在属的鉴别上是一类可靠而适用的新型特征依据,在属内某些种的区分上也具有一定的参考价值;对网蝽科昆虫体表感觉器官的发生发展、系统演化作了探讨性分析并提出了见解。     

三种蚤生殖系统的细微结构:雄性外生殖器的发育

本文研究了缓慢细蚤Leptopsylla segnis(Schonherr),不等单蚤Monopsyllus anisus(Rothschild)和猫栉首蚤指名亚种Ctenocephalides felis felis(Bouche)雄性外生殖器的结构,观察了从幼虫、前蛹、蛹至成虫各发育时期的雄性外生殖器的内部结构变化.对有争议的雄蚤上抱器的起源,雄蚤生殖孔的位置,雄性外生殖器芽内陷的腹节以及射精管横切面的细胞数目和阳茎背、腹杆的结构等问题进行了详细的观察和探讨.     

绒螯蟹触角形态特征及其在分类中的应用

基于光镜和扫描电镜的观察,研究了绒螯蟹触角的形态结构,分析了绒螯蟹第1触角内、外肢节的组成,以及外肢节内侧感觉毛的特点;第2触角内肢节的形状以及极长感觉毛和表面鳞片的特征.探讨了在绒螯蟹系统分类中,触角形态特征作为新的分类性状的可能性.     

日本纺织娘消化系统的微细构造

运用光镜及扫描电镜的技术对日本纺织娘Mecopoda niponensi De Haan消化道的内、外结构进行了研究.结果表明日本纺织娘的消化系统可分为前肠、中肠和后肠三大段 ,其前肠的结构较为特殊嗉囊内壁具有排列紧密的大刺,前胃内部则有6列骨化大嵴, 嵴上具大齿.胃盲囊分上、下两叶,上叶又被膜分隔成若干小叶.因这些特征在不同种类的螽斯中均不相同,所以在分类上具有一定的意义,同时也为农业上进行害虫防治及天敌昆虫的研究提供解剖生理学方面的依据.     

多斑岭鳅嗅觉器官表面超微结构及其形态适应

多斑岭鳅(Oreonectes polystigmus)是营洞穴生活的鱼类,嗅觉器官在其生活中发挥了重要作用。本文对保藏于中国科学院动物研究所鱼类标本馆的4尾多斑岭鳅标本进行解剖,利用扫描电镜观察多斑岭鳅嗅囊上皮超微结构,以期了解嗅觉器官适应洞穴黑暗环境而产生的形态适应。多斑岭鳅的嗅囊呈椭圆型,嗅囊长径平均为2.27 mm,嗅囊长径与眼径比平均为1.36,揭示其为"嗅觉"鱼类。其嗅轴为直线型,嗅囊腔内对称紧密排列2排嗅板,嗅板数为22~24个。单个嗅板呈卜状亚型,舌状突起较发达。观察发现,非感觉纤毛连续广布在嗅板各个部位,但在嗅板近嗅轴处较少,此处裸露的表皮多褶皱,其上分布很多细微小孔。感觉纤毛主要分布于非感觉纤毛分布较稀疏的地方。上皮表面微绒毛多,一般在非感觉纤毛下,前后两端嗅板上的微绒毛数量相对较少。多斑岭鳅嗅囊水动力机制应属嗅上皮纤毛运动机制。嗅孔分布不均,中间嗅板上的嗅孔较嗅轴前、后分布的嗅板为多,同一嗅板上近嗅轴处的嗅孔最多。由于纤毛分布不均,嗅上皮可分为裸露区和非裸露区,一般裸露区和非裸露区边界清晰,嗅轴上非感觉纤毛和微绒毛主要分布在非裸露区的凹槽里。嗅轴和嗅板近嗅轴处裸露区面积较大,嗅轴裸露区上皮被一系列的连续的微脊切割成多边形,多边形内具有许多隆起与小孔。嗅轴处正是嗅囊中水流回流的区域,为感受水中气味的重要位置,推测与洞穴生活的习性有密切关系。多斑岭鳅嗅囊形态属于G型,这类鱼类其嗅觉功能在鱼类生命活动中发挥了重要作用。同近缘的地表种相比,多斑岭鳅具有较多的嗅板数目、较多数量感觉纤毛和微绒毛,且其嗅囊长径与眼球径比值大于1,这些都揭示了其为"嗅觉"鱼类,表现出了对洞穴黑暗环境的适应。     

轻,中度体力负荷条件下外加吸气阻力的感觉阈限

以10名健康男青年为被试者,分别于静坐及轻、中度(200、600Kg.m.min~(-1))体力活动条件下观察了外加吸气阻力负荷所引起的面罩腔压力(P)及外呼吸功(w)变化;并采用辨别阈梯级(JND)与多级估量量表(MES)相结合的方法测出了不同体力负荷条件下的呼吸阻力感觉阈限。结果表明:(1)面罩腔压力与外呼吸功分别与呼吸感觉量值呈高度相关关系(P<0.01)但又以压力指标相关程度更为密切,故选用面罩腔压力波动幅度()作为反映呼吸感觉程度的客观生理指标较外吸气功率更为适宜。(2)体力负荷与外加吸气阻力对面罩腔压力、外呼吸功及感觉量值均具有协同的增强效应。(3)随体力负荷的增强,呼吸阻力感觉的阈限值也相应升高。在轻度体力负荷下能引起轻、中度呼吸阻力感觉的面罩腔压力波动幅度阈限值分别为(60、100mmH_2O);在中度体力负荷下,则分别为80、130mmH_2O。述结果对制订航空供氧装备附加呼吸阻力生理学标准具有实际意义。     

Structural and biochemical observations on specialized membranes of the "filter chamber", a water-shunting complex in sap-sucking homopteran insects

Many homopteran insects feed on plant sap which contains solutes in very low concentration. Their digestive tract presents a complex called the "filter chamber" where the excess dietary water is believed to flow directly from the initial part of the midgut to the terminal part of the midgut and the proximal regions of the Malpighian tubules. Freeze-fracture experiments carried out on the filter chamber of Cicadella viridis revealed the presence of intramembrane particles on the whole surface of the microvilli and of basal membrane infoldings of the cells. Examination of negatively stained isolated membranes and of freeze-dried shadowed membranes revealed that the inner surface of the membrane is covered with particles protruding into the cytoplasm; they correspond to the numerous intramembrane particles observed on the P fracture face of the membrane. The outer surface of the membrane exhibits a regular network which corresponds to that observed on the E fracture face. SDS-PAGE analyses were performed on purified membranes of the filter chambers of C. viridis and Philaenus spumarius. In both cases 2 major components, 25 kDa and 75 kDa, were detected. These 2 components appear to be specific for the filter chambers since they were not found in membranes isolated from the other parts of the midgut. Thus, the membranes of these filter chambers, thought to be water-shunting complexes, possess structural and biochemical peculiarities which are probably related to water permeability.     

Structural insights into the secretin PulD and its trypsin-resistant core

Limited proteolysis, secondary structure and biochemical analyses, mass spectrometry, and mass measurements by scanning transmission electron microscopy were combined with cryo-electron microscopy to generate a three-dimensional model of the homomultimeric complex formed by the outer membrane secretin PulD, an essential channel-forming component of the type II secretion system from Klebsiella oxytoca. The complex is a dodecameric structure composed of two rings that sandwich a closed disc. The two rings form chambers on either side of a central plug that is part of the middle disc. The PulD polypeptide comprises two major, structurally quite distinct domains; an N domain, which forms the walls of one of the chambers, and a trypsin-resistant C domain, which contributes to the outer chamber, the central disc, and the plug. The C domain contains a lower proportion of potentially transmembrane beta-structure than classical outer membrane proteins, suggesting that only a small part of it is embedded within the outer membrane. Indeed, the C domain probably extends well beyond the confines of the outer membrane bilayer, forming a centrally plugged channel that penetrates both the peptidoglycan on the periplasmic side and the lipopolysaccharide and capsule layers on the cell surface. The inner chamber is proposed to constitute a docking site for the secreted exoprotein pullulanase, whereas the outer chamber could allow displacement of the plug to open the channel and permit the exoprotein to escape.     

Cultivation of Escherichia coli to high cell densities in a dialysis reactor

High cell density cultivation of Escherichia coli on a glycerol-based mineral medium was studied. The cultivation was done in a dialysis reactor composed of two chambers. The inner chamber is formed and separated from an outer chamber by a membrane. Fresh medium was continuously exchanged with medium in the outer chamber so that both glycerol and other components of the medium were supplied to the inner chamber through the membrane. Inhibitory substances diffused from the inner to the outer chamber and were subsequently removed with effluent from the outer chamber. Initially, mathematical models were used to describe the process. The optimal cultivation parameters, such as the initial glycerol concentrations in the two chambers, the desired transport rate across the membrane, glycerol concentration in the feed/dialysing medium, and the time to start the medium exchange, were determined from preliminary experiments and calculations. The actual cultivation results agreed very well with the model predictions. A very high cell concentration of 174 g dry weight/1 was obtained. This cell concentration is within the range of the maximum theoretical concentration of E. coli in culture broth (160–200 g/l).Dedicated to the 60th birthday of Prof. Dr. D. Vortmeyer Correspondence to: H. Märkl     

The filtration apparatus for food collection in freshwater sponges (Porifera,Spongillidae)

Summary The freshwater sponges (Spongillidae) feed by filtering out small particles from the water passing through them by means of strainer devices in the flagellated chambers. These are filamentous, fine-meshed structures at the distal ends of the choanocyte collars formed of a mucous material similar to that in the glycocalyx. Each strainer separates its flagellated chamber into an outer and an inner zone. The strainers are an extremely efficient filtering mechanism.     

Myocardial stress equations: fiberstresses of the prolate spheroid

There are occasions in physiological research and medical practice where it is desirable to estimate the average fiberstress in a chamber wall, knowing only the pressure and dimensions. Because the contribution of a strained wall element to pressure depends on its location whereas its contribution to average stress is independent of location, an equation of this kind must involve an assumption about the stress distribution. When applied to a particular chamber, it will give an exact result only if the chamber's stress distribution is in some sense like that of the model for which the equation was derived. Since the fibers of biological chambers are continually being deposited and resorbed, they tend to exhibit similar stretches under the average conditions of the chamber. To the extent that this is so, P = (2/3) sigma v ln V0/Vc, is the best simple fiberstress equation for biological chambers. (P = transmural pressure, sigma v = volume-averaged fiberstress, V0 = volume enclosed by outside surface, Vc = cavity volume). It expresses the pressure-dimension-average-fiberstress relation of a chamber of any shape whose stresses exhibit the simplest possible distribution. One can add a term to the right side to account for the influence of stress profile complexities. That term takes the form of a moment whose value is zero at one state of distension. This "stress moment" expresses the unequal weighting of complexities on the two sides of the midwall isobar. Judging from the sarcomere length profile of the left ventricular wall, the stress moment is zero and the average fiberstress equation above is exact for average developed stress (without a second term) when cavity volume is somewhere near end-diastolic. Moreover, the departures from the relation (the effects of stress moment) are small so long as the inner and outer stresses do not differ by a factor greater than two.     

The fine structure of a tri-lamellar body in various species ofAnabaena

Summary A tri-lamellar body has been observed either near or adjacent to the crosswalls in 16 out of 20 different isolates ofAnabaena examined in thin sections. These bodies appear to consist of three discoid lamellae approximately 0.3 m in diameter. The outer lamella (closest to the plasma membrane) is separated from the middle lamella by a 12 nm space and is about 8 nm in thickness. The middle and inner lamellae, spaced about 8 nm apart, are approximately 8 nm in thickness. Electron dense granules, interpreted to be -granules, are associated with the inner lamella. In different species, osmiophilic lines 3 nm wide were observed. The osmiophilic lines run at right angles to the lamellae, either between the outer and middle lamellae, between the middle and inner lamellae or between all three lamellae. In some species, osmiophilic lines are absent. Up to six tri-lamellar bodies have been observed in median longitudinal sections. Pores 20 nm in diameter and 60 nm apart were observed in layer 2 of the cell wall of all the species ofAnabaena examined. All species which had tri-lamellar bodies also had wall pores closely associated with the bodies. Wall pores were also observed in four species lacking tri-lamellar bodies. The possible role of these structures is discussed.     

A note on the hairy achenes of four African species of Scleria Bergius (Cyperaceae)

Surface features of hirsute achenes of four African species of Scleria have been examined by SEM. All bear unicellular, terete hairs with swollen bases. As the achenes mature and dry, the hairs collapse, except for their partly silicified bases, which appear as pit-like depressions from which the now-flattened hairs emerge. If the achene surface is not smooth the hairs are localized on the interlacunar ridges. In addition to the hairs, three of the four species examined show minute papillate protuberances from the silicified outer tangential walls of the epidermal cells. These papillae form a further ornamentation to the achenes visible only at high magnification. The fourth species entirely lacks these papillae.     

荔枝草花的形态发生

在体式显微镜系统观察的基础上,对唇形科鼠尾草属植物荔枝草(Salvia plebeiaR.Br.)的花发育过程进行了扫描电镜观察.发现荔枝草的轮伞花序由多数交互对生的聚伞花序单位组成,花器官发育形式为向心式",各部分花器官从外向内依次形成;共形成4个雄蕊原基,其中2个雄蕊原基在形成后不再发育,另2个雄蕊原基每个均发育出1可育药室和1不育药室,不育药室膨大连接,并在花成熟之前参与组成特殊杠杆结构;子房四深裂"的形成实际是由4个原基分别发育,而后相互靠拢而成.     

蒙古黄兔尾鼠的生态观察

蒙古黄兔尾鼠(Lagurus przewalskii Buechner)是内蒙古和青海等省(区)荒漠草原的代表鼠种,因破坏草原和传播某些动物流行病而被列为重要害鼠之一。迄今为止,国内有关该鼠的生态研究尚无报道,为此,我们在1978年9月至1980年5月于内蒙古四子王旗北部的荒漠草原进行了蒙古黄兔尾鼠的生态学调查。现就观察结果总结如下。     

Antennal sensilla ofNeomysis integer (leach)

Summary The most frequent type of the hair sensilla on the antennae ofNeomysis integer is investigated by electron microscopic methods. The cellular properties of the sensilla are compared with those of other arthropods in order to detect possible homologies.The hairs are innervated by 2, 3, 6, 8, 9, or 10 sensory cells. The dendrites show an inner and outer dendritic segment. Five or six enveloping cells belong to a sensillum. In intermoult stage, processes of all the enveloping cells except the innermost one extend into the hair shaft. The sensory hairs possess only a single liquor cavity, which morphologically is homologous to the inner lymph cavity of insect sensilla. Around the liquor cavity, a supporting structure is located which seems to be identical to the scolopale of chordotonal organs. The six-to tenfold-innervated hairs possess two groups of differently structured dendrites which are regularly arranged on opposite sides of the liquor cavity. The outer dendritic segments are enclosed in a dendritic sheath. It is secreted by the innermost enveloping cell (= dendritic sheath cell of insect sensilla). All the outer dendritic segments terminate in the distal region of the hair shaft which shows a pore at its tip. The possible function of the sensilla is discussed. The double and triple-innervated hairs are considered to be mechano-receptors, whereas the sensilla associated with six to ten sensory cells might be mechano-chemoreceptors.