KATABLEPHARIS OVALIS,A COLORLESS FLAGELLATE WITH INTERESTING CYTOLOGICAL CHARACTERISTICS1

Katablepharis ovalis Skuja, isolated from an impoundment in Colorado, has a cell covering composed of two layers over the cell body and flagella. The outer component of the cell covering contains 25-nm-diameter hexagonal scales arranged in rows. The inner component of the cell covering is composed of a layer of interwoven microfibrils. The inner component of the cell covering is joined to the plasma membrane by one or more attachment strips that always occur outside, and along, one of the microtubular groups of the outer array. The attachment strips resemble hemidesmosomes and are composed of rows of electron-dense material, 12 nm apart, that protrude through the plasma membrane into the extracellular space, to attach to the inner wall. The two flagella are inserted subapically into a raised area of the cell. The flagella do not have any fibrillar or tubular hairs and are covered only by the two-layered cell covering. The cell has an inner and outer array of microtubules, both of which are spindle-shaped, arising at the anterior end of the cell and continuing into the posterior end of the cell. A single large Golgi apparatus occurs in the anterior cytoplasm. The nucleus is in the center of the cell. Two rows of large ejectisomes occur posterior to the area of flagellar attachment. Smaller ejectisomes occur under the plasma membrane in the posterior and medial areas of the cell. Each ejectisome is composed of a single body containing a spirally wound, tapered ribbon. On discharge, the ejectisome ribbon rolls inward, creating a tubular structure. The possible relationship between Katablepharis, the green algae, and the cryptophytes is discussed.     

Observations with the Electron Microscope on the Cell Structure of the Antheridium and Spermatozoid of Sphagnum

Sectioned antheridia of Sphagnum have been investigated withthe electron microscope at magnifications up to 50, 000 diametersand anatomical features of the main protoplasmic organs in twotypes of cells are described and illustrated. In the parenchymatouscells of the antheridial wall the main components encounteredare: nucleus, starch-laden plastids, mitochondria, fat bodies,tubules, putative golgi areas, vesicles, membranes, and granules.In the coiled spermatozoid the main observations concern thecoiled nucleus, the vestigial plastid, putative mitochondriaat the two extremities of the cell, the distribution of vesiclesand fibres in the cytoplasm, and the structure and mode of attachmentof the two flagella. In a comparative discussion it is suggestedthat the parenchymatous cells show resemblance to cells of thehigher plants, notably in details of their plastids and mitochondria.The extreme specialization of the spermatozoid impedes closecomparisons with other plants but a homology is tentativelysuggested between a peculiar organ referred to here as the ‘fibrousband’ to which the nucleus and both flagella are attachedand certain intercalary fibres originating in a comparable positionbetween the bases of the flagella in green and brown algae.     

FINE STRUCTURE OF THE ZOOSPORE OF OEDOCLADIUM CAROLINIANUM (CHLOROPHYTA) WITH SPECIAL REFERENCE TO THE FLAGELLAR APPARATUS1, 2

Ultrastructure of the motile zoospore has been investigated in Oedocladium catolinianum & Hoffman. An unwalled zoospore is usually produced from the contents of a terminal vegetative cell and consists of two principal regions: a small anterior dome and a larger body region; a ring of flagella marks the juncture of these two areas. Chloroplast inclusions consist of thylakoids, mature and incipient pyrenoids, starch and striated microtubules; no eyespot has been observed. Zoospores appear to possess permanent contractile vacuoles with numerous accessory vacuoles, coated vesicles and occasionally coated tubules. The cytoplasm of the dome contains numerous mitochondria ER and golgi bodies, as well as two distinct types of vesicles. The first contains an electron-dense; granular core and is surrounded by a loose, sinuate membrane. The second vesicle is electron-opaque and is found at the apex of the dome: it contains mucopolysaccharides employed during zoospore adhesion. A complex flagellar apparatus encircles the lower region of the dome. It consists of ca. 30–65 flagella, a ring-shaped fibrous band, flagella roots and additional supporting material. The flagella and roots alternate with one another beneath the fibrous band. The compound flagellar roots consist of two superimposed components: an outer ribbon-like unit composed of three microtubular elements and a single striated inner component. A band of support material lies beneath the proximal end of the basal bodies. It is a continuous fibrous band, although it often appears as three distinct, repetitive units.     

Observations with the Electron Microscope on a Species of Saprolegnia

Electron micrographs are presented to show the morphology ofthe flagella in each of the two motile phases of Saprolegniaferax, and one visual light photograph of a stained cell ofthe second stage is added. The front flagellum of both phasesis a Flimmergeissel with hairs between 2µ and 3µlong arranged in two rows and each ending in a thin hair-point.The axis is covered by a wide transparent sheath made of somematerial which appears to liquefy after death. The hind flagellum,which is devoid of Flimmer, is covered by a similar sheath,though there are signs that this is flattened into a fin inthe hind flagellum of the second stage. Some very fine shorthairs 0?5µ long are interpreted as a possible internalframework to this fin. The axis of both flagella is fibrillar,but accurate numerical details have not yet been obtained. Theskins discarded from cysts have also been examined and shownto be covered with characteristic double-headed hooks, whichare strong enough to attach a cyst to passing objects.     

Observations on the fine structure of spermatozoids and vegetative cells of the green alga Golenkinia

Spermatozoids and vegetative cells of the green alga Golenkinia minutissima Iyengar et Balakrishnan have been examined by light and electron microscopy. The biflagellate spermatozoids are of a somewhat specialised type, elongated with the nucleus attached to the flagellar bases, and containing a reduced chloroplast without pyrenoid or eyespot. The flagellar apparatus and root system has been examined in detail and is compared with that found in other green algae. The flagella are of a previously unknown type; they contain only one central microtubule—possibly non-functional—but they move in an apparently normal way. Present knowledge about flagellar roots in green algae has been assembled in a table, showing that the cruciate root has now been found in 10 genera, belonging to almost as many families. Exceptions are Oedogonium, which contains a modification of this type, and the Charales, which are very different. During spermatogenesis in Golenkinia each spermatozoid is surrounded by a wall which disappears at maturity. This fact may prove to be of taxonomic value.

The spines on the vegetative cells are composed of regularly arranged longitudinal fibrils, possibly cellulose, attached to the inner part of the two-layered cell wall. The content of the vegetative cell is typically chlorococcalean.     

Ultrastructure of the amoeboid flagellate <Emphasis Type="Italic">Thaumatomonas zhukovi</Emphasis> Mylnikov et Mylnikov (Thaumatomonadida (Shirkina) Karpov, 1990)

The ultrastructure of the amoeboid flagellate Thaumatomonas zhukovi sp. is presented. The cell is covered by cell body scales that formed on the surface of mitochondria. Capturing bacteria, the pseudopodia emerge from the ventral groove, which is supported by two longitudinal microtubular bands. The heterodynamic flagella emerge from the small flagellar pocket. Both flagella are covered by cone-shaped scales and thin twisted mastigonemes. The transitional zone of the flagella contains a thin-walled cylinder. The transversal plate of the flagella rises above the cell surface. The kinetosomes lie parallel to each other. The flagellar root system consists of three microtubular bands and a fibrillar rhizoplast. The vesicular nucleus and the Golgi apparatus have typical structures. The cytoplasm contains microbodies and food vacuoles. Mitochondria contain tubular cristae. Extrusive organelles (kinetocysts), which contain amorphous material and a capsule, were found in the cytoplasm. The capsule consists of a theca and a cylinder. The resemblance of Thaumatomonas zhukovi to other thaumatomonads is discussed.     

High pH Causes Disintegration of the Root Surface in Lupinus angustifolius L.

The effect of high pH on the morphology and anatomy of the rootsof lupin (Lupinus angustifolius L. cv. Yandee) and pea (Pisumsativum L. cv. Dundale) was examined in buffered solution. Themorphology and anatomy of lupin roots were markedly altered,and root growth was reduced by increasing solution pH from 5·2to 7·5, whereas pea roots were unaffected. In lupin roots,pH 7·5 caused disintegration of the root surface andimpaired root hair formation. Lupin roots grown at pH 7·5also had decreased cell lengths but increased cell diameterin both the epidermis and the cortex in comparison to rootsgrown at pH 5·2. High pH reduced cell volume greatlyin the epidermis, to a lesser extent in the outer cortex andnot at all in the inner cortex. It appears that in lupins, theprimary detrimental effects of growth at pH 7·5 is reducedlongitudinal growth of cells near the root surface with a consequentreduction in elongation of the cells in inner cortex.Copyright1993, 1999 Academic Press Lupinus angustifolius L., Pisum sativum L., high pH, root morphology, root anatomy     

The flagellar apparatus of the golden algaSynura uvella: Four absolute orientations

Summary Flagellated vegetative cells of the colonial golden algaSynura uvella Ehr, were examined using serial sections. The two flagella are nearly parallel as they emerge from a flagellar pit near the apex of the cell. The photoreceptor is restricted to swellings on the flagella in the region where they pass through the apical pore in the scale case and the swellings are not associated with the cell membrane or an eyespot. A unique ring-like structure surrounds the axonemes of both flagella at a level just above the transitional helix. The basal bodies are interconnected by three striated, fibrous bands. Four short (<100 nm) microtubules lie between the basal bodies at their proximal ends. Two rhizoplasts extend down from the basal bodies and separate into numerous fine striated bands which lie over the nucleus. Three- and four-membered microtubular roots arise from the rhizoplasts and extend apically together. As the roots reach the cell anterior, the three-membered root bends and curves clockwise to form a large loop around the flagella; the four-membered root bends anticlockwise and terminates under the distal end of the three-membered root as it completes the loop. There are four absolute orientations, termed Types 1–4, in which the flagellar apparatus can occur. With each orientation type the positions of the Golgi body, nucleus, rhizoplasts, chloroplasts and microtubular roots change with respect to the flagella, basal bodies and photoreceptor. Two new basal bodies appear in pre-division cells, and three short microtubules appear in a dense substance adjacent to each new basal body. Based upon the positions of new pre-division basal bodies, a hypothesis is proposed to explain why there are four orientations and how they are maintained through successive cell divisions.     

Structure of the cell of the amoeboid flagellate <Emphasis Type="Italic">Thaumatomonas coloniensis</Emphasis> Wylezich et al., 2007 (Thaumatomonadida (Shirkina) Karpov, 1990)

The ultrathin structure of the amoeboid flagellate Thaumatomonas coloniensis Wylezich et al. has been studied. The cell is surrounded by somatic scales forming on the surface of the mitochondria. The heterodynamic flagella emerge from the small flagellar pocket. Both flagella are covered by pineal scales and thin twisted mastigonemes. The kinetosomes lie parallel to each other. The transitional zone of the flagella carries the thin-walled cylinder. The transversal plate of the flagella is above the cell surface. The flagellar root system consists of three microtubular bands and a fibrillar rhizoplast. The vesicular nucleus and Golgi apparatus are of the usual structure. The mitochondria contain tubular cristae. The extrusive organelles (kinetocysts) contain amorphous material and a capsule; they are located in cytoplasm. The capsule consists of a muff and cylinder. Osmiophilic bodies of various shapes contain crystalloid inclusions. The pseudopodia capturing the bacteria emerge from the ventral groove. The groove is armored by the two longitudinal groups of the close situated microtubules. Microbodies and symbiotic bacteria have not been discovered. The resemblance of Th. coloniensis with other thaumatomonads is discussed.     

THE CYTOSKELETON OF THE NAKED GREEN FLAGELLATE SPERMATOZOPSIS SIMILIS (CHLOROPHYTA):FLAGELLAR AND BASAL BODY DEVELOPMENTAL CYCLE1

Flagellar and basal body development during cell division was studied in the biflagellate green alga Spermatozopsis similis Preisig et Melkonian by light microscopy of immobilized living cells, statistical analysis of flagellar lengths during the cell cycle, and electron microscopy of cells and isolated cytoskeletons. Interphase cells display two flagella of unequal/subequal length. An eyespot located in an anterior lobe of the chloroplast is connected to the basal body bearing the shorter flagellum by means of a five-stranded microtubular root. Until cell division, the two parental flagella attain the same length. During cell division, each cell forms two new flagella that grow to a length of 1.5 μm before they are distributed in a semiconservative fashion together with the parental flagella to the two progeny cells at cytokinesis. During the following interphase, the flagella newly formed during the preceding cell division grow to attain the same length as the parental flagella until the subsequent cell division. The shorter of the two flagella of a cell thus represents the developmentally younger flagellum, which transforms to the mature state during two consecutive cell cycles. Interphase cells display only two flagella-bearing basal bodies; two nascent basal bodies are formed during cell division and are connected to the microtubular d-roots of respective parental basal bodies with which the newly formed basal bodies are later distributed to the progeny cells. During segregation, basal body pairs shaft into the 11/5 o'clock direction, thus conserving the 1/7 o'clock configuration of basal body pairs of interphase cells. Prior to chloroplast and cell division, an eyespot is newly formed near the cell posterior in close association with a 1s microtubular root, while the parental eyespot is retained. During basal body segregation, eyespot-root connections for both the old and newly formed eyespots are presumably lost, and new associations of the eyespots with the 2s roots of the newly formed basal bodies are established during cytokinesis. The significance of this “eyespot-flagellar root developmental cycle” for the absolute orientation of the progeny cells is discussed.     

Reconstruction of the flagellar apparatus in Ploeotia costata (Euglenozoa) and its relationship to other euglenoid flagellar apparatuses

The flagellar apparatus of Ploeotia costata Farmer and Triemer was reconstructed using serial sectioning and TEM. The flagellar apparatus is similar to other euglenoids having two flagella arising from basal bodies connected by a striated fiber, and three asymmetrically arranged roots. The flagella emerge subapically from between the two ventral pellicle strips. The dorsal flagellum is 1/2 the body length and actively pulls the cell, while the ventral flagellum is twice the body length and drags along the substrate surface. The ventral and dorsal roots are on the opposite sides of their respective basal bodies, while the intermediate root is associated with the ventral flagellum on the side closest to the dorsal basal body. The dorsal root lines the dorsal side of the reservoir and after giving rise to the dorsal band lines the right side of the reservoir/canal. The ventral and intermediate roots join at the reservoir forming the intermediate-ventral root, which lines the left and ventral sides of the reservoir/canal. There was no evidence of a microtubule-reinforced pocket in P. costata. Comparisons with Ploeotia vilrea, Lentomonas applanatum, and related flagellar apparatuses led to the conclusion that the basic euglenoid flagellar structure is symplesiomorphic but with enough variation to be taxonomically diagnostic.     

Studies on marine algae of the British Isles. 8. Cystoseira tamariscifolia (hudson) papenfuss

The fine structure of the zoospores of Urospora penicilliformis (Roth) Aresch. (Chlorophyceae) is described. Of special interest is the flagellar apparatus. The proximal part of each of the 4 flagella is ribbon-shaped and contains nine wings attached to the peripheral double tubules. The flagellar root system originates from the flagellar bases and includes striated fibrous roots, passing close to the nucleus, and cruciate nine-stranded microtubular roots along the four corners of the cell. The Golgi bodies produce numerous vesicles, concentrating apically in the cell; they are presumed to be of importance for the attachment of the zoospore.     

The Specificity of the Carrier-Mediated Uptake of ABA by Root Segments of Phaseolus coccineus L.

Earlier work has established that the saturable component ofuptake of RS-[2¹⁴C]ABA by bean (Phaseolus coccineus L. cv. Prizewinner)root segments can be attributed to the action of a carrier.We now show that the carrier-mediated uptake is unaffected byRS-2-trans-ABA and lunularic acid and the unnatural R-ABA alsoappears to be ineffective. The specificity for S-ABA requiresthe halving of the K_m value for ABA determined previously (2.6mmol m_-3 for RS-; 1.3 mmol m_-3 for S-ABA). The RS-1', 4'-cis-dioland RS-1'-deoxy ABA reduce the uptake of RS-[2-₁₄C]ABA aboutas strongly as does unlabelled ABA, the K¹ for 1'-deoxy ABAwas similar to the K_m for ABA. The K₁ for RS-1', 4'-trans-diolwas 15.7 mmol m_-3. Consideration of the stereochemistry of thesecompounds suggests that the face of the ring of ABA away fromthe 1'-hydroxyl group interacts with the carrier site. Labelled material diffused out of undamaged root surfaces whichhad absorbed RS-[³H]ABA through an apical cut, suggesting thatABA is present in the apoplast. A simplified hypothesis is presented that can account for polartransport of ABA based on a gradient of a carrier in a tissuebut where the carrier is distributed uniformly on the apicaland basal ends of each cell. Key words: Uptake carrier, Abscisic acid, 1', 4'-Diol, Lunularic acid, Phaseolus coccineus, Polar-transport, Deoxyabscisic acid     

马尾松毛虫雄蛾触角毛状感受器的细微结构

马尾松毛虫Dendrolimus punctagus(Walker)雄蛾有一对羽毛状触角。在触角鞭节的每对侧枝的内侧(迎风面)着生许多毛状感受器。每个毛状感受器由几丁质表皮毛及位于其下的三个感觉神经原和三个呈同心排列的辅助细胞-鞘原细胞、毛原细胞和膜原细胞构成。几丁质表皮毛上有许多孔。毛腔内充满感受器淋巴液。感觉神经原发出的树状突伸入毛腔,浸浴于感受器淋巴液内。这些结构特征表明它是一种司嗅觉的化学感受器。雄蛾终生不取食,推断它的嗅觉感受器主要用以感受雌蛾释放的性外激素,帮助寻找配偶。     

Rooting of Chrysanthemum Stem Cuttings as Affected by (2-chloroethyl) Phosphonic Acid and Indolebutyric Acid

Stem cuttings of Chrysanthemum morifolium Ram. were treatedwith aqueous solutions of (2-chloroethyl)phosphonic acid (Ethrel)and indolebutyric acid (IBA). Ethrel (1 mg per 1) as a dip oras two foliar sprays, promoted root length and branching inMrs. Roy and Clipper which are difficult-to-root cultivars,but had no effect on Improved Mefo, an easy-to-root cultivar.IBA increased root number in both Clipper and Improved Mefo.The results suggest that IBA and Ethrel act at different stagesof the rooting process, with IBA promoting initiation and Ethrelstimulating elongation and branching. Increases in root numberwith IBA treatment, and in root length with Ethrel treatment,were accompanied by decreases in the soluble carbohydrate concentration,particularly in stem bases.     

Image reconstruction of the flagellar basal body of Caulobacter crescentus

The bacterium Caulobacter crescentus has a single polar flagellum, which is present for only a portion of its cell cycle. The flagellum is ejected from the swarmer cell and then synthesized de novo later in the cell cycle. The flagellum is composed of a transmembrane basal body, a hook and a filament. Single-particle averaging and image reconstruction methods were applied to the electron micrographs of negatively stained basal bodies from C. crescentus. These basal bodies have five rings threaded on a rod. The L and P rings are connected by a bridge of material at their outer radii. The E ring is a thin, flat disk. The S ring has a triangular cross section, the sides of the triangle abutting the E ring, the rod and the M ring. The M ring, which is at the inner membrane of the cell, has a different structure depending on the method of preparation. With one method, the M ring makes a snug contact with the S ring and is often capped by an axial button, a new component apparently distinct from the M ring. With the other method, the M ring is similar to that of S. typhimurium; that is, it contacts the S ring only at an outer radius and lacks the button. Averages of the rod-hook-filament subassembly ejected by swarmer cells reveal that the rod consists of two parts with the E ring marking the approximate position of the break. The structures of basal bodies from two mutants defective in the hook assembly were found to be indistinguishable from wild-type basal bodies, suggesting that the assembly of the basal body is independent of the hook or filament assembly.     

The Floral Nectaries of Hibiscus rosa-sinensis: 1. Development of the Secretory Hairs

Floral nectaries of Hibiscus rosa-sinensis occur on the lowerinner side of the fused sepals and each one consists of numerous(50000–55000) secretory hairs, occupying a cylinder-likezone completely lining the inner side of the sepals. Each hairoriginates from a single protodermal mother cell and, at maturity,it is built up of a basal cell, a stalk, 35–40 intermediatecells and a tip secretory cell. Development of protodermal cellsinto secretory hairs is asynchronous, the first cells to initiatedevelopment being those situated in the lowermost part of thecylindrical zone, and development progressing upwards. Volume increase of protodermal mother cells initiating developmentis accompanied by cell polarization manifested by organelledisplacement towards the apical region. Secretory hairs areformed through a sequence of transverse and, later on, anticlinaldivisions. Divisions of apical cells are preceded by well definedpre-prophase microtubule bands, which foreshadow the plane ofthe forthcoming division and predict with accuracy the sitesof parental walls where the new cell plate fuses at cytokinesis. Stalks consist of either one or two cells. Two-celled stalksoccur in 40 per cent of secretory hairs and derive from a transversedivision of one stalk cell; the wall formed is always depositedparallel to the proximal and distal walls, but never to thelateral ones. The significance of this mode of division is discussedin relation to the fact that lateral walls are entirely impregnatedwith a cutin-like material that blocks apoplastic movement ofsolutes. Hibiscus rosa-sinensis, nectaries, development, preprophase microtuble bands, stalk cells     

Development and Histochemistry of the Pistil of the Grape, Vitis vinifera

The development of the grape pistil is followed for a periodof 9 weeks from flower initiation to anthesis. Three phasesof pericarp differentiation are revealed: ring meristem formation;cell proliferation by anticlinal cell divisions; and a maturationphase characterized by periclinal cell division and differentiation.Both the stigma papillae and the transmitting tissue of thestyle originate by periclinal cell divisions. The receptivestigma is of the wet type and comprises many filamentous papillae,each composed of about 20 cells and covered by a loose cuticle.The stigma exudate shows similar cytochemical properties tothe material in the intercellular spaces of the transmittingtissue and is physically continuous with it. After pollinationand coincident with withering of the stigma, a single layerof stylar cells becomes suberized, forming a protective layerof cicatrix. Vitis vinifera, grape, pistil, development, histochemistry     

In vivo Observations of Plastid and Cell Division in Raphid Diatoms and Their Relevance to Diatom Systematics

Premitotic rearrangements of the protoplast, cytokinesis andpostmitotic rearrangements were followed in vivo in Naviculapupula Küitz. and N. bacillum Ehrenb. The plastids andnuclcus perform translational movements before cytokinesis,taking up well-defined positions on opposite sides of the cell.Following this the plastid divides by constriction and the cellcleaves in two. Cytokinesis takes 5–8 min and is effectedby a contractile ring. This is circular, except where constrainedby the cell wall. Parts of the ring appear to be functionalbefore cleavage begins. The two volutin granules persist duringcell division and are segregated one to each daughter cell.The granules are associated with the tonoplast and contractilering until late in cleavage, when they are released into thevacuoles. After value formation, the plastid, which has beenchanging in shape since before mitosis, rotates through 90°.A new volutin granule is formed in each daughter cell. The segregationof the granules, the tilt of the dividing nucleus and the rotationof the plaslid are chiral. The positions and shapes taken bythe organelles during the cell cycle suggest the presence ofintracellular recognition and attachment sites, which existfor specific periods. The taxonomic value of cell cycle eventsis discussed. Navicula, cell cycle, cell division, diatom systematics, plastid division, plastid rotation, volutin granules