Ultrastructural study of microsporidian development

Summary Vegetative growth of Nosema sp. occurs within the gut submucosal cells of Callinectes sapidus. Vegetative cell morphology is dominated by profiles of endoplasmic reticulum, numerous free ribosomes and aggregates of vesicles enclosed by a membranous sac. The dikaryotic vegetative cell is the earliest stage found in the target area for sporogenesis, the sarcoplasm of the striated muscle cell. The next obvious stage is the sporoblast mother cell; it undergoes karyokinesis without breakdown of the nuclear envelope. Intranuclear mitotic microtubules extend from the chromosomes to the intact nuclear envelope. After repeated nuclear divisions, the sporoblast mother cell undergoes delayed cytokinesis and a series of sporoblast progeny develops.The polar filament is the first visually apparent system to develop during sporogenesis. It appears to be of dual origin: (1) the central core component is condensed in Golgi-like saccules, and (2) the envelopes around the core originate from the endoplasmic reticulum.The polaroplast, which forms after early polar filament development, appears to originate as an elaboration of the endoplasmic reticulum.Supported in part by a training grant from the National Institutes of Health (GM-669-05) and research grants from the National Science Foundation (GB-3036, GB-5235, and GB-7938) to Prof. F. Sogandares-Bernal. The skillful guidance of Prof. F. Sogandares-Bernal is acknowledged. Special thanks are extended to Prof. D. E. Copeland for the use of a Siemens Elmiskop IA electron microscope. I also wish to thank Mr. Julian King, professional fisherman of Irish Bayou, Louisiana, for providing hundreds of blue crabs used in the course of this study.     

Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch, 1837) (Hydrachnidia: Teutoniidae)

Shatrov, A. B. 2010. Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae). —Acta Zoologica (Stockholm) 91 : 222–232 The midgut of the adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae) was investigated by means of transmission electron microscopy and on semi‐thin sections. The midgut is represented by a blind sac composed of the narrow ventriculus, two proventricular lateral diverticula and three pairs of postventricular caeca. A single‐layered epithelium consists of one type of endodermal digestive cells of quite different shape and size, which may form protrusions into the midgut lumen. The large nuclei are frequently lobed and contain one to three nucleoli. The apical cell membrane forms short scarce microvilli, between their bases the pinocytotic vesicles of unspecific macropinocytosis as well as the narrow pinocytotic canals are formed and immersed into the cell. The intracellular digestion of the food ingested into the midgut after extraintestinal digestion is predominant. The pinocytotic vesicles fuse with small clear vesicles of proposed Golgi origin to form secondary lysosomes. The digestive cells also contain small amounts of rough endoplasmic reticulum, variously structured heterolysosomes, residual materials in the form of both the small electron‐dense bodies and the large variously granulated substances, reserve nutritive materials such as lipid and glycogen, as well as clear vacuoles. Residual materials are obviously extruded from the cells into the gut lumen.     

FTIR Spectroscopic Study of Biogenic Mn-Oxide Formation by Pseudomonas putida GB-1

Biomineralization in heterogeneous aqueous systems results from a complex association between pre-existing surfaces, bacterial cells, extracellular biomacromolecules, and neoformed precipitates. Fourier transform infrared (FTIR) spectroscopy was used in several complementary sample introduction modes (attenuated total reflectance [ATR], diffuse reflectance [DRIFT], and transmission) to investigate the processes of cell adhesion, biofilm growth, and biological Mn-oxidation by Pseudomonas putida strain GB-1. Distinct differences in the adhesive properties of GB-1 were observed upon Mn oxidation. No adhesion to the ZnSe crystal surface was observed for planktonic GB-1 cells coated with biogenic MnO _x , whereas cell adhesion was extensive and a GB-1 biofilm was readily grown on ZnSe, CdTe, and Ge crystals prior to Mn-oxidation. IR peak intensity ratios reveal changes in biomolecular (carbohydrate, phosphate, and protein) composition during biologically catalyzed Mn-oxidation. In situ monitoring via ATR-FTIR of an active GB-1 biofilm and DRIFT data revealed an increase in extracellular protein (amide I and II) during Mn(II) oxidation, whereas transmission mode measurements suggest an overall increase in carbohydrate and phosphate moieties. The FTIR spectrum of biogenic Mn oxide comprises Mn-O stretching vibrations characteristic of various known Mn oxides (e.g., “acid” birnessite, romanechite, todorokite), but it is not identical to known synthetic solids, possibly because of solid-phase incorporation of biomolecular constituents. The results suggest that, when biogenic MnO _x accumulates on the surfaces of planktonic cells, adhesion of the bacteria to other negatively charged surfaces is hindered via blocking of surficial proteins.     

The spatial arrangement of germ line cells in ovarian follicles of the mutantdicephalic inDrosophila melanogaster

Summary The pattern of intercellular connections between germ line cells has been studied in follicles of the mutantdicephalic (dic), which possess nurse cell clusters at both poles. Staining of follicles with a fluorescent rhodamine conjugate of phalloidin reveals ring canals and cell membranes and thus allows us to reconstruct the spatial organization of the follicle. Each germ line cell can be identified by the pattern of cell-cell connections which reflect the mitotic history of individual cells in the 16-cell cluster. The results indicate that in both wild-type anddicephalic cystocyte clusters one of the two cells with four ring canals normally becomes the pro-oocyte. However, in some follicles (dicephalic and wild-type) oocytes were found with fewer or more than four ring canals. Indic follicles, one or several nurse cells may become disconnected from the other cells during oocyte growth at stage 9–10. Such disconnected cells cannot later on empty their cytoplasm into the oocyte. This, in turn, might be of consequence for the determination of axial polarity of the embryo.     

Plastids in sieve elements and companion cells of Tilia americana

Summary Contrary to an earlier report, the sieve elements and companion cells of Tilia americana contain plastids. In young sieve elements and companion cells the plastids contain a moderately electronopaque matrix and internal membranes; the latter are very numerous in the plastids of the sieve elements. Plastids of mature sieve elements contain an electron-transparent matrix, apparently fewer internal membranes than the plastids of young elements, and a single starch grain each. The plastids of companion cells undergo little or no structural modification during cellular differentiation, and apparently contain no starch.This research has been supported by the National Science Foundation, grants GB-5950 and GB-8330.     

Ultrastructure of the plasmodial slime moldPerichaena vermicularis

Summary Mature plasmodia ofPerichaena vermicularis require a light period to induce sporulation. In this paper the ultrastructure and acid phosphatase localization of the mature plasmodium ofPerichaena vermicularis are investigated. Acid phosphatase is localized in vacuoles containing remnants of bacteria and cell organelles. Morphological and histochemical evidence support the interpretation that these vacuoles constitute two types of lysosomes called respectively heterophagic and autophagic vacuoles.Coated vesicles which apparently originate from smooth endoplasmic reticulum are dispersed throughout the plasmodium and frequently associated with lysosomes. Several dumbbellshaped mitochondria are observed in the plasmodium at the onset of fruiting but not during later stages of plasmodiocarp development. Cytoplasmic microtubules are identified inPerichaena vermicularis. Some of these are closely associated with microfilaments.This work was supported by National Science Foundation grants (GB-5884 and GB-8537) to Dr.Ian K.Ross, NSF grant (GB 12371) to Dr.James Cronshaw, and an NSF Traineeship (GZ 445 and 796) to I.Charvat.This constitutes a portion of a thesis presented to the Regents of the University of California by the first author in partial fulfillment of the requirements for the Ph. D. degree.     

Effect of organic acids on inhibition of Escherichia coli O157:H7 colonization in gnotobiotic mice associated with infant intestinal microbiota

Previously, we produced two groups of gnotobiotic mice, GB-3 and GB-4, which showed different responses to Escherichia coli O157:H7 challenge. E. coli O157:H7 was eliminated from GB-3, whereas GB-4 became carriers. In this study, we analysed the mechanisms of E. coli O157:H7 elimination using GB-3 and GB-4. When GB-3 and GB-4 mice were challenged with E. coli O157:H7, the E. coli O157:H7 population was reduced in the caecum of GB-3 when compared to that in the GB-4 caecum, although the numbers of E. coli O157:H7 in the small intestine were not significantly different between these two groups of gnotobiotic mice. The lag time of E. coli O157:H7 growth in a 50% GB-3 caecal suspension increased when compared to that in a GB-4 caecal suspension. Acetate and lactate were detected in the GB-3 caecal contents, and acetate and propionate in those from GB-4. Although E. coli O157:H7 growth was not suppressed when it was cultured in anaerobic broth supplemented with these organic acids, the motility of E. coli O157:H7 was suppressed when it was cultured on semi-solid agar supplemented with the combination of acetate and lactate. These results indicate that the organic acid profile in the caecum is an important factor related to the elimination of E. coli O157:H7 from the intestine.     

Sulphated polysaccharide synthesis in brown algae

Summary Histochemical and autoradiographic techniques have been used to investigate the sites of synthesis, transport and location of sulphated polysaccharides in some larger brown seaweeds.The most rapid uptake of ³⁵SO₄ occurred when material was incubated in medium with 10^-4M carrier sulphate, negligable uptake occurring from seawater.Autoradiography using ³⁵SO₄ has shown that in Pelvetia sulphated material is synthesised by all cell types, particularly epidermal cells. In Laminaria spp. this activity is confined to specialized secretory cells which discharge into mucilage canals. In both instances the process of carbohydrate sulphation appears to occur in the Golgi-rich perinuclear region.     

Intranuclear annulate lamellae in oocytes of the tunicate,Styela partita

Summary Intranuclear annulate lamellae have been observed with the electron microscope in oocytes of the tunicate, Styela partita. Morphological evidence suggests that the annulate lamellae may arise by a specialized fusion process of individual vesicles. Intranuclear vesicles appear to be formed, in time, before differentiated annulate lamellae. It is also suggested that the position and structure of an annulus is in large part determined by the fusion of the vesicles. An annulus may be present as soon as two vesicles have completed their fusion process. Finally, it is again suggested on the basis of morphological evidence that the intranuclear vesicles are derived by the blebbing activity of the inner layer of the nuclear envelope.This investigation was supported by grants (RG-9229, 9230) from the National Institutes of Health, Public Health Service. The electron microscope facilities used were also supported by a grant (GM-05479) from the National Institutes of Health to Professor H. W. Beams.     

Nature of vesicles associated with the nervous system of cephalopods

Summary The epistellar body on the stellate ganglion of octopods and the parolfactory vesicles on the optic tracts of decapods have been established as potential photoreceptors on the basis of morphology (rhabdomeric processes) and biochemistry (presence of rhodopsin and vitamin A₁). These organs are not to be viewed as neuroglandular, as originally suggested, but rather as possibly contributing to physiological regulation by recording photic information. Layers of nerve fibers are evident around the vesicles in silver-stained preparations, contributing to nerves with central connections. The stellate ganglion of the young Octopus has lens-like optical properties.Dedicated to Professor Berta Scharrer in honor of her 60th birthday.Aided by U.S. National Science Foundation grant GB-2484. We wish to express our thanks to Doctors Pietro Dohrn and Luisa Tosi for the provision of facilities, to Professor A. de Girolamo and Dr. Aldo Cecio of the Istituto di Anatomia, Istologia e Embriologia Veterinaria of the University of Naples for their generous cooperation in allowing us the use of their electronmicroscope laboratory, to Mr. Jeremy Worthington for able technical assistance, and to Miss Margaret Rufener for the drawings.National Science Foundation Senior Postdoctoral Fellow, Stazione Zoologica di Napoli, 1965–1966     

Developmental and structural features of secretory canals in root and shoot wood of Copaifera langsdorffii Desf. (Leguminosae–Caesalpinioideae)

Copaifera langsdorffii Desf., popularly known as copaíba, is an oleoresin-producing tree has been overexploited in Brazil by the pharmaceutical, cosmetic and varnish industries. Despite the long history of the use of this species, the structural knowledge on the resin-producing sites remains inadequate and is limited to the trunk. The aim of this study was to describe the origin, structure and developmental features of secretory spaces present in shoot and root wood of C. langsdorffii, based on the usual techniques of wood anatomy studies. Both root and shoot wood present secretory canals distributed along the marginal parenchyma bands which delimit growth layers. Secretory canals are constituted by a locally biseriate epithelium and lume that contains terpenes. They are arisen in the cambial zone from fusiform cambial initial cells and, eventually, ray initials. The origin of lumen is schizogenous. The epithelial cells have meristematic potential and are responsible for the locally biseriate epithelium. Mature secretory canals are wider and are separated between themselves only by a row of radial cells. The fusion of these adjacent secretory canals is frequent and results from the radial cell collapse. The finding of an interconnected system of resin canals in C. langsdorffii might be of value in terms of sustainable extraction of the resin and realistically assess its sustainable harvest potential.     

Secretory organelle biogenesis: Trichocyst formation in a ciliated protozoan

Summary— By classical electron microscopy and immunoelectron microscopy, the biogenesis of trichocyst secretory granules has been followed in the ciliated protozoan Pseudomicrothorax dubius. The very early pre-trichocysts form by fusion of bristle-coated, electron-dense vesicles (dense vesicles) with electron-translucent vesicles (clear vesicles), both of which originate in a well-developed trans-Golgi network (TGN). The pre-trichocyst grows by further fusion with dense and clear vesicles as well as with other pre-trichocysts until it reaches its maximum diameter of about 2 μm. Dense and clear vesicle formation from the TGN has been followed, and the fusion sequence of dense vesicles with the pre-trichocyst has been documented. The contents of the dense vesicles are the precursors of the trichocyst tip, which is composed of four arm-like rods, whereas the shaft precursors are supplied by the clear vesicles. The first evidence of trichocyst shaft formation is the appearance of a paracrystalline, dense core condensation center in the pre-trichocyst. Following shaft formation, the trichocyst tip forms by fusion and condensation of the dense arm precursors along each of the four sides of the shaft. Docking of the fully formed trichocyst in the cell cortex is described. Pre-trichocyst biogenesis in cells grown with and without Se is compared.     

On the occurrence of nuclei in mature sieve elements

Summary The secondary phloem of 3 species of the Taxodiaceae and 13 species of woody dicotyledons was examined for the occurrence of nuclei in mature sieve elements. Nuclei were found in all mature sieve cells of Metasequoia glyptostroboides, Sequoia sempervirens and Taxodium distichum, and in some mature sieve-tube members in 12 of the 13 species of woody dicotyledons. Except for nuclei of sieve cells undergoing cessation of function, the nuclei in mature sieve cells of M. glyptostroboides, S. sempervirens and T. distichum were normal in appearance. The occurrence and morphology of nuclei in mature sieve-tube members of the woody dicotyledons were quite variable. Only 3 species, Robinia pseudoacacia, Ulmus americana and Vitis riparia, contained some mature sieve elements with apparently normal nuclei.This research has been supported by National Science Foundation grants GB-5950 and GB-8330.     

N-1-napthylphthalamic-acid-binding activity of a plasma membrane-rich fraction from maize coleoptiles

Summary Plasma membrane-rich fractions were prepared from maize coleoptiles by low-shear homogenization and differential and sucrose-gradient centrifugation. Plasma membrane fragments were identified using a specific cytochemical stain based on phosphotungstic acid prepared in chromic acid. In a comparison of 10 different cell fractions of varying plasma membrane content, the N-1-napthylphthalamic-acid (NPA)-binding activity of the fractions was directly proportional to the content of plasma membrane. The NPA binding appears to be strong K _M between 10^-8 and 10^-7 M) but non-covalent. NPA is known to inhibit auxin transport efficiently and quickly. Thus, the results are consistent with the localization of auxin transport sites at the plasma membrane of plant cells.Purdue University Agricultural Experiment Station Journal Paper No. 4355. This work was supported in part by a grant from the National Science Foundation GB-23183.Supported by National Science Foundation Postdoctoral Fellowship.     

Wood properties and ring width responses to long-term atmospheric CO2 enrichment in field-grown loblolly pine (Pinus taeda L.)

Loblolly pine (Pinus taeda L.) were grown in the field, under non-limiting nutrient conditions, in open-top chambers for 4 years at ambient CO₂ partial pressures (pCO₂) and with a CO₂-enriched atmosphere (+ 30 Pa pCO₂ compared to ambient concentration). A third replicate of trees were grown without chambers at ambient pCO₂. Wood anatomy, wood density and tree ring width were analysed using stem wood samples. No significant differences were observed in the cell wall to cell lumen ratio within the latewood of the third growth ring formed in 1994. No significant differences were observed in the density of resin canals or in the ratio of resin canal cross-sectional area to xylem area within the same growth ring. Ring widths were significantly wider in the CO₂-enrichment treatment for 3 of 4 years compared to the ambient chamber control treatment. Latewood in the 1995 growth ring was significantly wider than that in the ambient control and represented a larger percentage of the total growth-ring width. Carbon dioxide enrichment also significantly increased the total wood specific gravity (determined by displacement). However, when determined as total sample wood density by X-ray densitometry, the density of enriched samples was not significantly higher than that of the ambient chamber controls. Only the 1993 growth ring of enriched trees had a significantly higher maximum latewood density than that of trees grown on non-chambered plots or ambient chambered controls. No significant differences were observed in the minimum earlywood density of individual growth rings between chambered treatments. These results show that the most significant effect of CO₂ enrichment on wood production in loblolly pine is its influence on radial growth, measured as annual tree ring widths. This influence is most pronounced in the first year of growth and decreases with age.     

Oleoresin glands in copaíba (<Emphasis Type="Italic">Copaifera trapezifolia</Emphasis> Hayne: Leguminosae), a Brazilian rainforest tree

Although studies have addressed the chemical analysis and the biological activity of oleoresin in species of Copaifera, the cellular mechanisms of oleoresin production, storage, and release have rarely been investigated. This study detailed the distribution, ontogeny, and ultrastructure of secretory cavities and canals distributed in leaf and stem, respectively, of Copaifera trapezifolia, a Brazilian species included in a plant group of great economic interest. Axillary vegetative buds, leaflets, and portions of stem in primary and secondary growth were collected and processed in order to study the anatomy, histolocalization of substances, and ultrastructure. Secretory cavities are observed in the foliar blade and secretory canals in the petiolule and stem. They are made up of a uniseriate epithelium delimiting an isodiametric or elongated lumen. Biseriate epithelium is rarely observed and is a novelty for Leguminosae. Cavities and canals originate from ground meristem cells and the lumen is formed by schizogenesis. The content of the cavities and canals of both stem and leaf is oily and resinous, which suggests that the oleoresin could be extracted from the leaf instead of the stem. Phenolic compounds are also detected in the epithelial cell cytoplasm. Cavities and canals in the beginning of developmental stages have polarized epithelial cells. The cytoplasm is rich in smooth and rough endoplasmic reticula connected to vesicles or plastids. Smooth and rough endoplasmic reticulum and plastids were found to be predominant in the epithelial cells of the secretory cavities and canals of C. trapezifolia. Such features testify the quantities of oleoresin found in the lumen and phenolic compounds in the epithelial cell cytoplasm of these glands. Other studies employing techniques such as correlative light electron microscopy could show the vesicle traffic and the compartmentalization of the produced substances in such glands.     

Cytology of beet yellows virus infection inTetragonia

Summary This paper is the second in the series dealing with the ultrastructure ofTetragonia expansa Murr. infected with the beet yellows virus. It considers the relation of the virus to the conducting cells in the phloem and the xylem. Virus particles occurred in mature sieve elements, their amount increasing as the infected leaf became older. In older leaves some sieve elements were completely blocked with virus. Virus particles were seen in pores of sieve plates, in plasmodesmata interconnecting sieve elements and parenchyma cells, and in those between parenchyma cells. Mature and immature tracheary elements also contained virus particles. Presence of inclusions composed of vesicles and virus in some immature tracheary elements may indicate that virus multiplies in these cells. No vesicles and no virus particles were discovered in immature sieve elements.This work was supported in part by National Science Foundation grant GB-5506.     

Electron microscopic characterization of calcium-binding physodes in the green alga Mougeotia scalaris

Summary Effect of the covalently cross-linking agents glutardialdehyde and osmium tetroxide, and of adsorption of the vital dye, neutral red, to the matrix of the calcium-binding vesicles from the green alga Mougeotia scalaris has been analysed in situ, both in terms of structural preservation and of the calcium-binding capacity of the vesicles. Upon cell fixation in glutardialdehyde without OsO₄, the vesicles appear to dissolve, but upon simultaneous fixation in glutardialdehyde with OsO₄ (1% w/v), the vesicles retain a globular form, are evenly stained by osmium and appear to be surrounded by a membrane-like structure. This structure was also observed around the vesicles in cells preincubated for 10 min in 0.1 mM neutral red and then fixed in glutardialdehyde/OsO₄ for 1 h. More detailed information of the matrix structure is obtained when simultaneous fixation of the Mougeotia cells was shortened to 15 min: a membrane-like structure was no longer observed around the vesicles. After cell treatment in the presence of neutral red, no calcium at all was found inside the vesicles. A small amount of calcium remained, when cells were fixed simultaneously and extensively in the absence of neutral red. However, calcium was found, to a considerable extent, inside the vesicles after short simultaneous fixation of the cells in the absence of neutral red. Based on the ultrastructural and elemental features presented here, the calcium-binding vesicles in Mougeotia appear to represent a member of the large family of (calcium-binding) physodes in lower plants (CaBP).     

An ultrastructural and autoradiographic study of the immune response in Hyalophora cecropia pupae

Summary Membrane-bounded spherical vesicles found in rat Sertoli cells have been examined quantitatively during the cycle of the seminiferous epithelium. Most of the vesicles were localized to the basal and columnar portions of the Sertoli cell cytoplasm. The thin lateral projections of the Sertoli cells contained very few vesicles. Morphometric analysis of the basal portion of the Sertoli cell cytoplasm revealed that the volume density (V _v ) of the vesicles changed markedly during the cycle. The V _v was at its minimum (0.036) at stage VII and maximum (0.117) at stages XI-I. The vesicles were also smaller at stage VII compared to the vesicles at stages IX-V. The stage-dependent difference in the size of the vesicles was found both in the basal and the columnar portions of the Sertoli cells. At stage VII some of the vesicles appeared to be elongated much like the tubular elements of the smooth endoplasmic reticulum (SER) from which they are probably derived. The stage-dependent differences in volume density and size of the Sertoli cell vesicles may be related to cyclic biochemical variations in the Sertoli cells, and are further indications of a variation in Sertoli cell function during the cycle of the seminiferous epithelium. Whether or not this is due to an internal cycle of the Sertoli cell or to influences from adjacent germ cells remains to be determined.     

Gibberellic acid and the fine structure of barley aleurone cells

Summary This paper describes the ultrastructural changes in barley aleurone cells following exposure to gibberollic acid (GA₃) for 10–12 hr and longer. These changes involve a further proliferation of the endoplasmic reticulum (ER), distention of the endoplasmic reticulum (ER) cisternae (12–16 hr of GA₃) and proliferation of vesicles from the ER and dictyosomes (14–22 hr). Accompanying these changes is a reduction in the size of the aleurone grains and a decrease in the number of spherosomes. Plastids and microbodies however appear to increase in number during this period of GA₃ treatment. The relevance of these ultrastructural changes to GA₃-stimulated synthesis of hydrolases is discussed.The skillful technical assistance of Mrs. Janet Price is gratefully acknowledged. Supported by National Science Foundation grant GB-8332.