Cytological studies of the nematocysts of Hydra. II. The stenoteles

Entire hydras or tentacles were prepared for electron microscopy as described in the preceding paper. The stenotele capsule has been observed to be composed of an external membrane, a thick chitinous or keratin layer, and an inner membrane. A sac-like extension of the capsular wall into the capsule bears spines and stylets on its inner surface and evagination of this structure occurs on discharge. Profiles of tubular or membranous structures often are seen within the capsules of resting stenoteles. These structures are presumably related to the external filament. The spines often reveal a flattened aspect which suggests that at least some of them might more accurately be called "vanes." A cnidocil has been found to accompany each stenotele. This study revealed several aspects of the developmental stages of stenoteles: A vacuole is formed which is nearly surrounded by the nematocyte nucleus. The vacuole content changes in density and a capsular wall is formed at the periphery of the vacuole. Tubules differentiate from the capsular matrix, and spines and stylets develop somewhat later. An operculum is formed from the nematocyte cytoplasm.     

Cytological Studies of the Nematocysts of Hydra : II. The Stenoteles

Entire hydras or tentacles were prepared for electron microscopy as described in the preceding paper. The stenotele capsule has been observed to be composed of an external membrane, a thick chitinous or keratin layer, and an inner membrane. A sac-like extension of the capsular wall into the capsule bears spines and stylets on its inner surface and evagination of this structure occurs on discharge. Profiles of tubular or membranous structures often are seen within the capsules of resting stenoteles. These structures are presumably related to the external filament. The spines often reveal a flattened aspect which suggests that at least some of them might more accurately be called "vanes." A cnidocil has been found to accompany each stenotele. This study revealed several aspects of the developmental stages of stenoteles: A vacuole is formed which is nearly surrounded by the nematocyte nucleus. The vacuole content changes in density and a capsular wall is formed at the periphery of the vacuole. Tubules differentiate from the capsular matrix, and spines and stylets develop somewhat later. An operculum is formed from the nematocyte cytoplasm.     

金雕肾脏的组织学观察

利用生物显微技术观察了金雕Aquila chrysaetos肾脏的组织结构.结果表明,金雕肾实质由许多肾小叶构成,每个肾小叶可分为皮质和髓质两部分.肾单位由一个肾小体和一条与其相连的肾小管构成.肾小体由肾小囊和肾小球组成.肾小管分为近曲小管、髓袢、远曲小管和连接小管.集合管分为小叶周集合小管和髓质集合管两部分.具有发达的极周细胞.     

ELECTRON MICROSCOPE OBSERVATIONS ON THE STRUCTURE AND DISCHARGE OF THE STENOTELE OF HYDRA

Sections of the stenotele type of nematocyst of Chlorohydra hadleyi have revealed that the stenotele, upon firing, completely everts its stylets and spines and the long, thin tubule, much as the eversion of the tubule of the nematocyst of the jewel anemone (Picken, 1953; Robson, 1953). Alternative mechanisms for supplying the energy necessary to forcefully discharge the stenotele contents are discussed as well as the possible significance of several regions containing highly ordered periodic structure. The origin of nematocysts as kinetosomal derivatives is discussed as a possibility suggested by the symmetry of the stenotele contents and the structure, location, and function of the cnidocil.     

中华花龟五种器官组织学观察

利用石蜡切片法对中华花龟的心脏、肝脏、脾脏、肺和肾脏等组织器官进行了组织学观察.结果显示心肌的特点是暗带较窄,心肌纤维束状排列.肝脏分3叶,肝实质内结缔组织少,肝小叶分界不清楚.脾脏分被膜和实质两部分,实质由白髓和红髓构成,白髓包括椭球周围淋巴鞘(PELS)和动脉周围淋巴鞘(PALS),红髓由脾索和脾窦组成,未发现淋巴小结和生发中心.肺一对,为长形扁平囊,肺泡囊状,肺泡内可见管壁的结节状膨大.肾脏由肾小体、颈段、近曲小管、中间段、远曲小管和收集管6部分构成,肾小体由肾小球和肾小囊组成,在肾小体附近可见致密斑样结构.     

Quantitative intravital microscopy using a Generalized Polarity concept for kidney studies

In this article, we describe a ratiometric intravital two-photon microscopy technique for studying glomerular permeability and differences in proximal tubule cell reabsorption. This quantitative approach is based on the Generalized Polarity (GP) concept, in which the intensity difference between two fluorescent molecules is normalized to the total intensity produced by the two dyes. After an initial intravenous injection of a mixture of 3-, 40-, and 70-kDa fluorescently labeled dextrans into live Munich-Wistar-Frömter (MWF) rats, we were able to monitor changes in the GP values between any two dyes within local regions of the kidney, including the glomerulus, Bowman's capsule, proximal tubule lumens and proximal tubule cells, and individual capillary vessels. We were able to quantify accumulations of different dextrans in the Bowman's space and in tubular lumens as well as reabsorption by proximal tubular cells at different time points in the same rat. We found that for 6- to 8-wk-old MWF rats that developed spontaneous albuminuria, the 40- and 70-kDa dextrans, with hydrodynamic radii larger than albumin, were differentially filtered, but both were able to pass the glomerular filtration barrier and enter into the urinary space of the Bowman's capsule within a few seconds after intravenous infusion. Using GP image analysis, we found that negatively charged dextrans of both 40 and 70 kDa were better reabsorbed by the proximal tubule cells than the neutrally charged 40-kDa dextran. These results demonstrate the potential power of the GP imaging technique for quantitative studies of glomerular filtration and tubular reabsorption. glomerular permeability; tubular reabsorption; charge selectivity; two-photon excitation; multiphoton     

Structure Organization of Urinary System in the Yellow Spotted Mountain Newts （Salamandridae： Neurergus microspilotus）

This study deals with the histomorphology of the mesonephros in male and female Neurergus microspilotus. The slender and narrow kidneys are positioned in the retro peritoneal position up against the ventral aspect of vertebral column and may extend the length from the esophagus-stomach junction to cloaca. The kidney in both sexes is composed of sexual（anterior） and pelvic（posterior） parts. The duct of sexual kidney is a narrow duct which is lying alongside its lateral edge. In the female, it is connected to the ureters and then the duct of defi nitive kidney. Before entering the cloaca, two ureters are joined together and open to the apex of the cloaca. In the male, after entering the sexual kidney, the sperm leave the testis through efferent ducts, then these ducts join together and eventually form Bidder＇s duct. The Bidder＇s duct joins the Bowman＇s capsule of the nephrons in the sexual kidney and the nephrons make collecting ducts which are fi lled with both sperm and urine. After leaving the kidney, all the collecting ducts are connected to the Wolffi an duct. Wolffi an duct joins the ureters（merge from defi nitive kidney） just before entering the cloaca. Based on serial paraffi n sections, nephrons consist of a fi ltration unit, the Malpighian corpuscle, and a renal tubule, which can be divided into 4 morphologically distinct segments： proximal tubule（first and second segment）, distal tubule, and collecting tubule. Collecting tubules merge and form a branch system that opens into collecting ducts.     

Mechanical and salivary aspects of potato leafhopper probing in alfalfa stems

Studies were conducted to separate the salivary and mechanical aspects of probing damage by the potato leafhopper,Empoasca fabae (Harris) (Homoptera: Cicadellidae), to stem vascular tissue of alfalfa,Medicago sativa L. Implantation of salivary gland tissue or fed-upon artificial diet under the stem epidermis yielded no evidence, three days later, of hopperburn-associated, anatomical changes. Mechanical puncturing of stems with implements approximating the size and shape of leafhopper stylets caused some anatomical changes, three days later, similar to those underlying hopperburn, i.e. tracks of necrosis, chlorosis, cell enlargement, and cell division. These changes, however, were much less severe than those observed in tissues three days after potato leafhopper probing. In contrast, puncturing through salivary gland or Malpighian tubule tissues produced extreme hyperplasia and other symptoms of wounding in cells near the puncture. This was similar to but more severe than effects from leafhopper probing, and was probably caused by leafhopper structural tissues or larger amounts of saliva being conveyed into the plant than normally occurs during leafhopper probing. We conclude that both salivation and mechanical wounding by leafhopper stylets are probably necessary to cause hopperburn-associated anatomical changes to vascular tissue in stems of alfalfa. This conclusion supports our hypothesis that hopperburn is a saliva-enhanced wound response.     

Über die Entstehung des Nesselschlauches der Nematocysten vonDipurena reesi (Hydrozoa)

Zusammenfassung 1. Histochemische und autoradiographische Untersuchungen über die Entstehung des Neeselschlauchs in den Nematocysten des HydroidpolypenDipurena reesi Vanucci haben gezeigt, daß das Zentralsekret der Kapselanlage für die funktionsgerechte Lage des Nesselfadens in der Kapsel sorgt. Die Entstehung des Nesselfadens außerhalb der Kapselanlage ist sehr wahrscheinlich.2. Das Zentralsekret hat weiterhin die Funktion eines Materialspeichers. Es löst sich nach der Aufspulung des Nesselfadens im peripheren Kaspelinhalt auf. Das im Zentralsekret nachgewiesene Histidin gelangt in die Stilettanlagen.3. Die Stilette und Borsten des Schaftes werden auf einem PJS-positiven Achsenfaden angelegt. Die Schaftwand umwächst vom Apikalpol der Kapselanlage her die Stilett- und Borstenanlagen.

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On the formation of the stinging tube in the nematocysts ofDipurena reesi (Hydrozoa)

The differentiation of the stinging tube of a stenotele was studied by light microscopy in the hydroidDipurena reesi Vannucci. It was found, that the central body of the matrix cares for the correct position of the thread in the capsule, and that thereafter the stylets are formed from its material. The stylets and bristles of the shaft arise along a PJA-positive axial thread. The wall of the shaft grows down from the apical pole of the capsule, and envelops the primordia of the stylets and bristles.

     

韦氏缩腹榕小蜂的产卵行为

通过对聚果榕上一种非传粉榕小蜂———韦氏缩腹小蜂ApocryptawestwoodiGrandi的产卵行为的详细观察 ,发现该小蜂的产卵行为与具有可伸缩的腹节这种奇特的腹部结构高度相关。该小蜂的产卵过程主要分为 3个阶段 :( 1 )寻找产卵位置 ,小蜂在果面快速搜索 ,以触角或口器触须感受产卵位点 ;( 2 )刺壁 ,小蜂将产卵针垂直于果面 ,刺入果壁 ,进入果腔 ;( 3 )产卵与拉出产卵针。通过与Ansari对于韦氏缩腹小蜂的产卵行为的描述进行比较 ,发现有如下不同之处 :( 1 )在产卵针刚刺入果面时 ,伸长的腹部末端超过头 ,整个伸长的腹部几乎与果面平行 ;( 2 )后足具有下拉产卵鞘的行为 ,并且后足除下拉产卵鞘时与果面分离外 ,均抓住果面 ;( 3 )产卵针不需要产卵鞘支撑时 ,产卵鞘与产卵针分离。     

安南龟肝脏和肾脏的组织学观察

采用常规石蜡切片对安南龟的肝脏和肾脏进行了组织学观察。研究结果发现,肝脏分为3叶,肝实质内结缔组织少。肝脏由无数肝小叶构成,肝小叶分界不清。肝细胞为多角形的腺上皮细胞,细胞核圆球形,位于中央。胆小管沿着肝细胞索向肝小叶四周放射并连成细长的微细管道。肾脏由肾小体、颈段、近曲小管、中间段、远曲小管和收集管6部分构成,肾小体由肾小球和肾小囊组成,在肾小体附近可见致密斑样结构,未见髓袢结构。肾小球由盘曲的毛细血管构成。肾小囊是肾小管的起始端,由内、外两层壁层构成,内层与肾小球的毛细血管紧贴,外层为单层扁平上皮细胞。     

THE COLUMNAR CELLS OCCURRING IN THE PARIETAL LAYER OF BOWMAN'S CAPSULE : Cellular Fine Structure and Protein Transport

The renal corpuscles of adult, C3H Swiss, male mice contain testosterone-sensitive, columnar cells in the parietal layer of Bowman's capsule. A study of the normal fine structure of these cells reveals several distinctive characteristics: a microvillous brush border; apical tubular invaginations and apical tubules; an elaborate infolding of the basal surface membrane forming cellular compartments, which contain numerous mitochondria; and a complex group of membrane-limited cytoplasmic inclusions. This appearance is remarkably similar to the fine structure of cells in the proximal convoluted tubule. 1 hr after an in vivo injection of horseradish peroxidase, numerous protein-absorption droplets occur in the columnar cell cytoplasm. The speed and cytomorphology of protein transport by these capsular cells closely resemble the handling of peroxidase by the proximal convoluted tubule. Origins for these testosterone-sensitive cells are discussed briefly. Morphological evidence is presented for the differentiation of squamous cells in Bowman's parietal capsule into columnar cells, which appear structurally and functionally identical with proximal convoluted tubular epithelium.     

Observations on penetration of Barley leaves by the aphidRhopalosiphum maidis (Fitch)

Summary Penetration of leaves of barley,Hordeum vulgare L., by the corn leaf aphid,Rhopalosiphum maidis (Fitch), was studied with light, phase, and electron microscopes. Penetration of epidermis and mesophyll was largely intercellular, that of vascular bundles or veins largely intracellular. Like other aphids,R. maidis secretes a salivary sheath which surrounds the stylets. When mesophyll cells and parenchymatous elements of the veins were penetrated by stylets, their protoplasts were pushed to one side by intruding sheath material; hence, the protoplasts were not punctured by the stylets, although sometimes the plasmalemma of penetrated cells was ruptured by sheath material. The salivary sheaths ended more or less abruptly outside the walls of sieve elements being fed upon, the maxillary stylets projecting beyond the sheaths and into the sieve elements. Before penetrating a functional sieve element the aphid apparently flushes its stylets in order to clear them for ingestion of food. Salivary and food canals merge near the tips of the maxillary stylets to form a single canal, which ends short of the tips.This research was supported by the U.S. National Science Foundation (GB-8330).     

Remodelling during the development of nematocysts in a siphonophore

Remodelling of a smoothly tapering internal tubule to form the enlarged shaft of microbasic mastigophores of the siphonophore Rosacea takes place very late in development. It occurs after deployment of the nematocyst in its final position, and after the pleats of the internal tubule have been completely obliterated in the shaft region by the growth of spine material. The optical and mechanical properties of the internal tubule at the earlier (bedspring) stage give no hint that a shaft will develop. The possible ways in which remodelling might occur inside the capsule and remote from the cytoplasm are discussed.     

Electrical recording of plant penetration by western flower thrips

Plant penetration by western flower thrips (Frankliniella occidentalis (Pergande)) was analysed with the electrical penetration graph technique (EPG, DC-system). Thrips attached to a gold wire were included in an electrical circuit to record EPGs when penetrating the plant tissues with their stylets. Three basic EPG waveforms have been distinguished, correlated with stylet penetration into cells, salivation, and ingestion, respectively. The main difference with EPGs of Homoptera is the occurrence of continued separate penetrations that are not necessarily followed by ingestion. Insertion of the stylets causes strong voltage fluctuations in the EPG. We could confirm earlier evidence that penetration of cells and subsequent ingestion of (part of) the protoplast takes less than 20 seconds. Repeated short penetrations can be followed by a continuous feeding pattern during which the stylets are not withdrawn. The same sequence of waveforms is produced on other plant parts such as fruits or pollen grains. The specific waveforms are mainly caused by electromotive force (emf). The emf component was recorded with high resolution and the correlation of waveform details with activities of the cibarial muscle system is discussed.     

A Non-sulfated Chondroitin Stabilizes Membrane Tubulation in Cnidarian Organelles

Membrane tubulation is generally associated with rearrangements of the cytoskeleton and other cytoplasmic factors. Little is known about the contribution of extracellular matrix components to this process. Here, we demonstrate an essential role of proteoglycans in the tubulation of the cnidarian nematocyst vesicle. The morphogenesis of this extrusive organelle takes place inside a giant post-Golgi vesicle, which topologically represents extracellular space. This process includes the formation of a complex collagenous capsule structure that elongates into a long tubule, which invaginates after its completion. We show that a non-sulfated chondroitin appears as a scaffold in early morphogenesis of all nematocyst types in Hydra and Nematostella. It accompanies the tubulation of the vesicle membrane forming a provisional tubule structure, which after invagination matures by collagen incorporation. Inhibition of chondroitin synthesis by β-xylosides arrests nematocyst morphogenesis at different stages of tubule outgrowth resulting in retention of tubule material and a depletion of mature capsules in the tentacles of hydra. Our data suggest a conserved role of proteoglycans in the stabilization of a membrane protrusion as an essential step in organelle morphogenesis.     

Structure/function analysis of spinalin, a spine protein of Hydra nematocysts

The nematocyst capsules of the cnidarians are specialized explosive organelles that withstand high osmotic pressures of approximately 15 MPa (150 bar). A tight disulfide network involving cysteine-rich capsule wall proteins, like minicollagens and nematocyst outer wall antigen, characterizes their molecular composition. Nematocyst discharge leads to the expulsion of a long inverted tubule that was coiled inside the capsule matrix before activation. Spinalin has been characterized as a glycine-rich, histidine-rich protein associated with spine structures on the surface of everted tubules. Here, we show that full-length Hydra spinalin can be expressed recombinantly in HEK293 cells and has the property to form disulfide-linked oligomers, reflecting its state in mature capsules. Furthermore, spinalin showed a high tendency to associate into dimers in vitro and in vivo. Our data, which show incomplete disulfide connectivity in recombinant spinalin, suggest a possible mechanism by which the spine structure may be linked to the overall capsule polymer.     

Immunohistochemical evidence for neural mediation of VIP activity in the dogfish rectal gland

Vasoactive intestinal peptide (VIP) has been shown to increase chloride secretion from the rectal gland of the spiny dogfish, Squalus acanthias. Immunohistochemistry was used to localize the distribution of immunoreactive VIP (iVIP). Rectal glands were perfused with either buffered acrolein or paraformaldehyde/glutaraldehyde, sectioned (20 micron) and processed by either avidin-biotin complex (ABC) or peroxidase anti-peroxidase (PAP) methods. At the light microscopic level, iVIP was observed in thick fibers which traversed the fibromembranous capsule of the rectal gland. In the parenchyma, smaller iVIP-containing fibers were noted within connective tissue and in close approximation to tubule cells. At the ultrastructural level, iVIP axons in the fibromembranous capsule were unmyelinated. Immunoreactive fibers within the parenchyma frequently terminated on the basal side of tubule cells. Within the glands, iVIP bouton terminals were observed and contained vesicles of different sizes, with reaction product in dense core vesicles (60-120 nm). We conclude that iVIP is distributed in nerve fibers throughout the dogfish rectal gland. The anatomic distribution suggests that VIP may act as a neurotransmitter in this model of chloride ion transport.     

佩妃延腹榕小蜂的产卵行为

榕树与传粉榕小蜂之间的互惠共生关系是协同进化研究领域中的热点之一。榕树除了与传粉榕小蜂共生外,它还为许多非传粉榕小蜂提供食物和生境。佩妃延腹榕小蜂Philotrypesis pilosa Mayr腹部第8～9节背板极度延伸,形似长长的产卵鞘,其后更长的才是真正的产卵鞘。它将产卵针刺入榕果的果壁,产卵于果内。该蜂是对叶榕Ficus hispida L. 的传粉榕小蜂Ceratosolen solmsi （Mayr）的盗食性寄生蜂。我们利用数码照相机记录了佩妃延腹榕小蜂产卵的全过程,详细描述了其产卵行为。发现了前人没有发现的下列行为特点： (1）当雌蜂找到合适的产卵位点时,身体呈倒立状,后足扶持产卵鞘到选定的产卵位点;2）从开始插入产卵针到产卵鞘向后弹出,腹部第8～9节背板延伸部分与产卵鞘之间有两次大幅度的靠拢与分开,第一次靠拢与分开是保证产卵针以最佳的垂直角度插入果内,第二次是使产卵鞘向后弹出,将暴露在外的产卵针顺利地插入果内;3）雌蜂产卵针沿榕果直径方向（最短距离）插入果壁;4）前足与后足比中足发达,与整个产卵过程中支撑身体的行为有关 。     

Minicollagen-15, a novel minicollagen isolated from Hydra, forms tubule structures in nematocysts

Minicollagens constitute a family of unusually short collagen molecules isolated from cnidarians. They are restricted to the nematocyst, a cylindrical explosive organelle serving in defense and capture of prey. The nematocyst capsule contains a long tubule inside of its matrix, which is expelled and everted during an ultrafast discharge process. Here, we report the cloning and characterization of a novel minicollagen in Hydra, designated minicollagen-15 (NCol-15). NCol-15, like NCol-3 and NCol-4, shows deviations from the canonical cysteine pattern in its terminal cysteine-rich domains (CRDs). Minicollagens share common domain architectures with a central collagen sequence flanked by polyproline stretches and short N- and C-terminal CRDs. The CRDs are involved in the formation of a highly resistant cysteine network, which constitutes the basic structure of the nematocyst capsule. Unlike NCol-1, which is part of the capsule wall, NCol-15 is localized to tubules, arguing for a functional differentiation of minicollagens within the nematocyst architecture. NMR analysis of the altered C-terminal CRD of NCol-15 showed a novel disulfide-linked structure within the cysteine-containing region exhibiting similar folding kinetics and stability as the canonical CRDs. Our data provide evidence for evolutionary diversification among minicollagens, which probably facilitated alterations in the morphology of the nematocyst wall and tubule.