Calmodulin Localization and its Effects on Endocytic and Phagocytic Membrane Trafficking in Paramecium multimicronucleatum

ABSTRACT. In ciliates, calmodulin (CaM), as in other cells, has multiple functions, such as activation of regulatory enzymes and modulating calcium‐dependent cellular processes. By immunogold localization, CaM is concentrated at multiple sites in Paramecium. It is seen scattered over the cytosol, but bound to its matrix, and is concentrated at the pores of the contractile vacuole complexes and with at least three microtubular arrays. It was localized peripheral to the nine‐doublet microtubules of the ciliary axonemes. The most striking localization was on the akinetic side only of the cytopharyngeal microtubular ribbons opposite the side where the discoidal vesicles, acidosomes and the 100‐nm carrier vesicles bind and move. CaM was also present at the periphery of the postoral microtubular bundles along which the early vacuole moves and was associated with the cytoproct microtubules that guide the spent digestive vacuoles to the cytoproct. It was not found on the membranes of, or in the interior of nuclei, mitochondria, phagosomes, and trichocysts, and was only sparsely scattered over the cytosolic sides of discoidal vesicles, acidosomes, lysosomes, and digestive vacuoles. Together the associations with specific microtubular arrays and the effects of trifluoperazine and calmidazolium indicate that CaM is involved (i) in vesicle transport to the cytopharynx area for vacuole formation and subsequent vacuole acidification, (ii) in early vacuole transport along the postoral fiber, and (iii) in transporting the spent vacuole to the cytoproct. Higher CaM concentrations subjacent to the cell's pellicle and close to the decorated tubules of the contractile vacuole complex may support a role for CaM in ion traffic.     

The effect of concanavalin A on egestion of food vacuoles in Tetrahymena

The ability of concanavalin A (conA) to disrupt food vacuole elimination at the cytoproct of Tetrahymena pyriformis, strain GL-C, was investigated using fluorescence microscopy and thin section electron microscopy. ConA was found to induce "tails" in Tetrahymena. These tails were specifically stained by fluorescent conA. Thin section observations of conA-treated cells revealed that these tails were the result of abnormal egestion of food vacuole contents at the cytoproct. Tail formation appears to result from an inhibition of endocytosis of food vacuole membrane during egestion. Instead, the food vacuole membrane appears to be cast out of the cell, along with the contents of the vacuole. The mechanism of this inhibition may be related to an apparent absence of microtubules or microfilamentous mat in the cytoproct region of conA-treated cells. Although conA is ingested into food vacuoles in large amounts, conA appears to affect endocytosis only from outside the cell; ingested conA does not appear to be effective. ConA may exert its influence by binding to the cytoproct region. The ability of conA to induce tail formation is inhibited by sugars specific to it. Numerous membranous vesicles are found in association with the oral cilia and cytoproct region of conA-treated cells. These vesicles may be the conA-binding material reported to be secreted by Tetrahymena.     

Le Cortex de la Vacuole Contractile et son Ultrastructure chez les Ciliés

SYNOPSIS. In various ciliates the contractile vacuole is a permanent organelle, delimited by a differentiated cortex.
The cortex is made up of a dense reticulum of anastomosing tubules limited by a smooth membrane, and vesicles. This "spongiome" can be considered as a localized and specialized condensation of the endoplasmic reticulum.     

三种纤毛虫细胞内酸性磷酸酶的定位观察

利用电镜酶细胞化学方法,对大尾柱虫(Urostylagrandis)、冠突伪尾柱虫(Pseudourostylacristata)、魏氏拟尾柱虫(Paraurostylaweissei)三种纤毛虫细胞内的酸性磷酸酶(ACPase)进行了定位观察。发现在它们体内ACPase的阳性反应颗粒除分布在消化腔隙内独立的泡状结构上和被消化的食物组织中外,在细胞质中的小圆泡内也有分布。所得结果证实了消化腔隙和小圆泡都具有消化功能。作者推测消化腔隙主要消化食物,小圆泡则可能与自身物质(如衰老胞器等)的消化有关;并推测这种消化腔隙与小圆泡共存是纤毛虫消化胞器由食物泡演化为消化腔隙系统的中间形式。此外,在大尾柱虫纤毛内部观察到非溶酶体性的ACPase。     

Urotricha psenneri n. sp. and Amphileptus piger (Vuxanovici, 1962) n. comb., two planktonic ciliates (Protozoa, Ciliophora) from an oligotrophic lake in Austria

Two euplanktonic ciliates, Urotricha psenneri n. sp. (Prostomatida) and Amphileptus piger (Vuxanovici, 1962) n. comb. (Pleurostomatida), were discovered in the surface plankton of the oligotrophic Lake Traunsee in Austria. Their morphology and infraciliature were studied in live cells as well as in specimens impregnated with protargol and silver nitrate. Urotricha psenneri is a small urotrichid, less than 50 microm length and with a single caudal cilium. It is unique in having (i) a massive oral basket projecting as a conspicuous bulge with cylindrical microfibrillar annulus and (ii) a curved brosse row 1 in the broad, barren circumoral area. Amphileptus piger (Vuxanovici, 1962) is about 55 x 13 microm in vivo, has two macronuclear nodules with a single micronucleus in between in the posterior body half, has a single contractile vacuole with a terminal excretory pore, and few, but thick and thus highly conspicuous extrusomes. The amphileptid ciliary pattern (spica) is difficult to recognise due to the widely spaced basal bodies.     

Glomeruli and renal tubules are restricted to the cranial kidney of the adult estuarine Sphoeroides testudineus

The kidney of the pufferfish Sphoeroides testudineus , an abundant tropical euryhaline estuarine species of the western Atlantic Ocean found in southern Brazil (in salinities ranging from 0 to 34) has a large and laterally spread cranial red portion, and a very thin and pale caudal portion. When studied under light and transmission electron microscopy, the cranial kidney displayed glomeruli and renal tubules surrounded by haematopoietic tissue. These tubules appeared to drain into a single large convoluted collecting duct with a wide lumen and thick pseudostratified epithelium, the mesonephric duct, which constituted the sole structure of the caudal kidney. Apical microvillae were viewed in the renal tubules, as well as in the mesonephric duct. Basal mitochondria and membrane infoldings were observed in the renal tubules. Abundant more basally‐located mitochondria and electron‐dense vesicles, mainly in the apical cytoplasm, were observed along the entire length of the mesonephric duct. Aposomes (blebs) were frequently observed in the mesonephric duct, both by light‐ and electron‐microscopy. This euryhaline estuarine pufferfish has thus been revealed to possess a rare type of kidney.     

Morphogenesis and fate of the residual body in human spermiogenesis

Summary In the human testis the formation of the residual body of the spermatid and its morphological changes during and after spermiation were studied by means of electron microscopy. The caudal cytoplasmic mass of the late spermatid contains a Golgi complex, mitochondria, annulate lamellae, a chromatoid body, flower-like structures, ribosomes, a few large vacuoles, myelin-like membrane profiles and sporadic lipid droplets. When, by detachment of the caudal cytoplasm from the free spermatozoon, the residual body is formed, the chromatoid body has disappeared; the mitochondria are clustered peripherally; the ribosomes appear as a single complex in contact with a large vacuole containing granular material; in place of the Golgi complex aggregations of vesicles are present. The lipid droplets remain unchanged. The residual bodies or their fragments are either extruded via the seminiferous tubular lumen into the excurrent ducts or they are engulfed by Sertoli cells where in the supranuclear region the successive steps of decomposition can be observed. The participation of the various constituents in the disintegration of the residual body is discussed. In contrast to other mammalian species, in man the sporadic lipid droplets seem to be of minor importance in the fate of the residual body.     

The Fine Structure of Colpoda maupasi with Special Emphasis on Food Vacuoles*

SYNOPSIS. An electron microscope study of Colpoda maupasi Enriques, isolated from the intestine of the blue-tongued skink Tiliqua nigrolutea, showed that the fine structure of this ciliate is similar in all respects to that of free-living ciliates. The correspondence applies particularly to the structure, distribution and number of mitochondria. This organelle has a rich intramitochondrial structure in the form of microvilli; it is found close to the periphery, near the nuclear apparatus and in other parts of the cytoplasm. It was concluded that the association between Colpoda maupasi and Tiliqua nigrolutea was probably accidental and limited to the cyst stage. Thus electron microscopy confirmed a conclusion arrived at by light microscopy. The presence of numerous food vacuoles made it possible to study stages of digestion within this organelle. Four major types of food vacuole were distinguished. Type 1 food vacuoles are characterized by their large size, the presence of intact bacteria and abundance of water. In type 2 the food vacuole is deprived of water, the bacteria are pressed together and the nuclei have lost their structure. Type 3 food vacuoles contain only bacterial ghosts, cytoplasmic and nuclear material having been digested. Food vacuoles of this type are found only occasionally, suggesting their short duration. It is of interest that during this transient stage the bulk of digestion takes place. In type 4 nothing reminiscent of bacteria is found; there are only myelin figures and vesicles of different sizes. Evaginations and invagnations of the vacuolar membrane and vesicles of different size and structure inside and outside the food vacuoles of types 1, 3 and 4 suggest that extensive communication exists between the cytoplasm and the food vacuole. It seems likely that enzymes are delivered to the food vacuole and digested materials are released from the food vacuole to the cytoplasm.     

Observations on the Caudal Cilium of the Tomite of Ichthyophthirius multifiliis Fouquet, 18761,2

Light microscopy of live or silver-impregnated specimens of the fish parasite Ichthyophthirius multifiliis show that the tomites are elongated and claviform with the anterior end broad. The cytostome, indicated by the presence of the organelle of Lieberkühn, is found in the lower part of the broadened anterior third of the tomite. The tapered posterior end bears a rigid, caudal cilium at its pole. Scanning electron microscopy reveals the caudal cilium and associated structures, including the depression from which the cilium protrudes, circumciliary ring, and raised struts on the ring. From these observations it is concluded that a previously reported “apical filament” found on the tomite is actually the posterior caudal cilium described by Canella & Rocchi-Canella in 1976.     

不同发育时期哲罗鱼卵黄的超微结构

应用透射电镜观察了不同发育时期哲罗鱼(Hucho taimen)卵黄的超微结构.根据哲罗鱼卵黄物质在卵母细胞中的加工合成、积累以及卵母细胞中参与卵黄颗粒形成的细胞器的变化,可将该鱼卵黄发生分为4个特征时期,即卵黄发生前期、卵黄泡期、卵黄积累期和卵黄积累完成期.卵黄发生前期是指卵母细胞发育过程中的卵黄物质开始积累前的时期,此时期核仁不断分裂,出现线粒体云和早期的滤泡细胞层、基层和鞘细胞层;卵黄泡期特点主要是细胞器不断变化产生卵黄泡和皮层泡;卵黄积累期的滤泡膜由内向外依次为放射带、颗粒细胞层、基层和鞘细胞层,此时外源性卵黄前体物质不断经过血液汇集于鞘细胞层,后经微胞饮作用穿过胶原纤维组成的基层,经过多泡体作用转运至颗粒细胞内,在细胞内经过加工和修饰形成小的卵黄蛋白颗粒,卵黄蛋白颗粒经微胞饮穿过放射带进入卵母细胞边缘形成的空泡中,不断积累形成卵黄球;进入卵黄积累完成期,卵黄球体积变大,向细胞中心聚集,填满大部分卵母细胞,卵黄积累完毕.     

Ultrastructural localization of basic proteins ofBlastocystis hominis

Summary Basic proteins ofBlastocystis hominis were detected by the ammoniacal silver and ethanolic phosphotungstic acid techniques using electron microscopy. The central vacuole showed many silver grains when treated with ammoniacal silver and an increased electron density when treated with phosphotungstic acid. The intensity of positive reactions correlated with the electron density of the central vacuole, because cells having an electron-lucent central vacuole showed no silver grain deposits. Since it is known that the concentration of electron-dense materials in the central vacuole increases during log phase of growth, and then decreases in stationary phase, this organelle must accumulate basic proteins during cell growth.     

Tubular-vesicular transformation in the contractile vacuole system of Dictyostelium

The contractile vacuole complex of Dictyostelium is the paradigm of a membrane system that undergoes tubular-vesicular transitions during its regular cycle of activities. This system acts as an osmoregulatory organelle in freshwater amoebae and protozoa. It collects fluid in a network of tubules and cisternae, and pumps it out of the cell through transient pores in the plasma membrane. Tubules and vacuoles are interconvertible. The tubular channels are associated with the cortical actin network and are capable of moving and fusing. The contractile vacuole complex is separate from vesicles of the endosomal pathway and preserves its identity in a dispersed state during cell division. We outline techniques to visualize the contractile vacuole system by electron and light microscopy. Emphasis is placed on GFP-fusion proteins that allow visualization of the dynamics of the contractile vacuole network in living cells. Proteins that control activities of this specialized organelle in Dictyostelium have been conserved during evolution and also regulate membrane trafficking in man.     

SELECTIVITY MECHANISM FOR THE DIFFERENTIAL DESTRUCTION OF PLANT TISSUES BY METHYL DECANOATE EMULSION

Methyl decanoate emulsified with Tween 20 and sprayed on chrysanthemum plants kills the immature tissues. The mechanism of selectivity was found to be a property of the cuticle which acts as a penetration barrier to the emulsion. Disruption of cuticles before emulsion application resulted in death of underlying cells due to membrane destruction, as shown by electron microscopy. Small quantities of methyl decanoate, however, do penetrate the unaltered cuticle, resulting in moderate, reversible alterations to the ultrastructure of the cell. These alterations appear as aggregates of vesicles in the cytoplasm and larger aggregates of vesicles in the vacuole. No destruction of organelle membranes occurred, and visual symptoms were not seen. The marginal cuticular penetration was verified by isolated cuticle tests.     

The ultrastructure of primary cilia in the endocrine and excretory duct cells of the pancreas of mice and rats

A primary cilium was frequently observed in the endocrine alpha, beta and delta cells, as well as in the excretory duct cells of the pancreas of normal mice and rats. The characteristic components of the cilium including the basal body, axoneme (shaft), and terminal part were clearly recognizable. The basal body or distal centriole surrounded by Golgi vesicles was perpendicularly oriented to the proximal centriole, and a dense striated band was seen filling the gap between them. The microtubules of the basal body consisted of nine peripheral triplets exhibiting a 9 + 0 pattern, an appearance similar to that of the proximal centriole. Rootlets, basal feet and alar sheets associated with the basal body were occasionally seen. The axoneme usually consisted of a 9 + 0 pattern of microtubule doublets, but other irregular patterns of 7 + 2, 7 + 3, and 8 + 1 were also seen. The microtubules in the terminal part of the cilium became fewer in number and had no peculiar arrangement. The cilium of the endocrine cells always projected into the intercellular canaliculus and was covered by the ciliary sheath, and occasionally, double cilia were visualized in the vicinity of beta cells. In the excretory duct cells, the cilium showed similar features, but it was slightly longer and always projected into the dense secretory content of duct lumen. On the other hand, no primary cilium was ever observed in the acinar cells of mouse and rat pancreas. In conclusion, the present study describes the morphology of primary cilia and its associated components in the endocrine and excretory duct cells of the pancreas of mice and rats. The findings suggest that the primary cilium should be considered as a constant intracellular organelle though its function and significance remain speculative.     

ULTRASTRUCTURE OF SWARMERS IN THE LAMINARIALES (PHAEOPHYCEAE). I. ZOOSPORES1

Zoospores of 17 species in 14 genera of Laminariales, collected in the northeast Pacific Ocean, were studied by electron microscopy. These zoospores are unique in the brown algae in lacking both an eyespot in the single chloroplast and any associated swelling at the base of the shorter, posterior flagellum. Spores of all species examined possess a distal whiplash portion on the longer, mastigoneme-bearing anterior flagellum. This appendage may sometimes be as long as the mastigoneme-bearing portion of the flagellum, but it is only seldom preserved in the preparations for electron microscopy. A microtubular cytoskeleton is probably responsible for maintaining the shape of the spore. It consists of a short band of about 10 microtubules between the two basal bodies, scattered tubules converging at the anterior of the spore, a band of 7–9 tubules directed anteriorly from the anterior basal body, and a band directed posteriorly from the posterior basal body. These anterior and posterior bands may form one continuous band looping around the periphery of the spore. Variation with possible taxonomic significance was found in the ultrastructure of vesicles which apparently contain adhesive material, and which are extruded through the plasmalemma when the zoospores settle.     

牛体外受精的程序及超微结构研究

牛体外成熟卵母细胞体外受精后３小时精子入卵,８小时原核形成,２４小时的核多到卵中央。精子发生顶体反应的部位主要在透明表面,方式是顶体外膜自身囊经,发生顶体反应的粗子可斜向或垂直穿过透明带。卵丘细胞可吞噬大量精子,在阻多精受精中发挥重要作用。高尔基得合体,线料体、环状片层和滑面内质网等在原核周围形成细胞器集团。牛体外受精卵的雌雄原结合比体内受精的要延迟,胞吐到卵周隙中的皮质颗粒内容物扩散不完全。     

Structure of the tegument and ectocommensal microorganisms of Gyliauchen nahaensis (Digenea: Gyliauchenidae), an inhabitant of herbivorous fish of the Great Barrier Reef, Australia

The ultrastructure of the tegument and tegument-associated microorganisms of the gyliauchenid digenean Gyliauchen nahaensis is described by transmission and scanning electron microscopy. The tegument is devoid of surface spines and is characterized by a moderately folded apical membrane, abundant vesicles, basal mitochondria, a folded basal plasma membrane, and a thick basal matrix. Microorganisms form a dense biofilm on the tegument of the posterodorsal surface and the excretory papilla. At least 7 microbial morphotypes were identified, including eubacteria, spirochaetes, and nanobacteria.     

Ultrastructure of the Somatic and Buccal Cortex of the Tetrahymenine Hymenostome Glaucoma chattoni

SYNOPSIS The membranes, epiplasm, and fiber systems are described in the somatic cortex of Glaucoma chattoni strain HZ-1. Kinetodesmal fibers, postciliary and transverse microtubular ribbons, basal microtubules, transverse fibers and transverse accessory material are associated with kinetosomes. Longitudinal microtubular ribbons and mitochondria occur interkinetally. In the buccal cortex, the membranes, epiplasm and fibers of the 3 membranelles, the paroral kinety, the ribbed wall, and the cytostome are described. Comparisons between G. chattoni and other ciliates reveal ultrastructural differences of possible systematic significance. In the somatic cortex of this and other tetrahymenines. Iongitudinal microtubular ribbons and basal microtubules occur concurrently. In the buccal cortex, alveoli are absent in tetrahymenine membranelles. A table is presented of the fiber systems associated with single somatic kinetosomes of various ciliates whose cortical ultrastructure has been studied to date.     

蚕豆保卫细胞中钙调素的免疫电镜定位

以蚕豆横切和平切气孔为材料,对钙调素进行了免疫胶体金电镜定位的结果表明:在蚕豆保卫细胞的细胞核、细胞质、细胞膜、叶绿体、液泡、高尔基体、细胞壁中都有金颗粒分布,在线粒体上的分布较少.     

Transformation in Tetrahymena pyriformis: description of an inducible phenotype.

Transformation of Tetrahymena pyriformis to a rapid-swimming (presumably dispersal) form can be induced by washing cells and suspending them in distilled H2O, Dryl's solution or 10 mM Tris. Transformation is possible with high efficiency in mass cultures of axenically grown cells within approximately 5 h at 30 C. The radically different phenotype produced during transformation is characterized by a more elongate body form, increased numbers of somatic basal bodies and cilia, a long caudal cilium and oral membranelles positioned beneath the cell surface. DNA quantities characteristic of G1, S, and G2 cells are found in these transformed ciliates, suggesting that achievement of a particular stage in the DNA-division cycle is not a prerequisite for transformation. Preliminary observations on cells belonging to syngens 2-12 indicate that they also have a capacity to form a caudal cilium, but that the amicronucleate strain GL-C does not. Possible relevance of the transformed phenotype for taxonomy of Tetrahymena is discussed.