The spirotheca of the foraminifer Quasifusulina

A SEM study on the test wall of Quasifusulina has demonstrated that the ultrastructures in the spirotheca Quasifusulina different from those of related fusulinid genera, such as Fusulinella and Triticites. The primary wall structure is prokerotheca rather than diaphanotheca or keriotheca, as previously described. The peculiar wall structures of Quasifusulina may represent a previously unknown type of spirotheca in fusulinid Foraminifera. □ Foraminifera, ultrastructure, spirotheca, biomineralization, Carboniferous, Permian.     

Morphological and ultrastructural studies of some acritarchs from the Lower Cambrian Lükati Formation, Estonia

Six acritarch species from the Lükati Formation were studied using a combination of techniques, including transmitted light, scanning electron (SEM) and transmission electron (TEM) microscopy. New details of wall ultrastructure, surface microsculpture and internal morphology of the vesicle and processes significantly add to the previously known morphological features and increase the understanding of the form-genera Archaeodiscina, Globosphaeridium, Comasphaeridium, Skiagia, Tasmanites and Leiosphaeridia. Examination of microfossils using TEM revealed a substantial variation in wall ultrastructure among acritarchs. The diversity includes four structural types of vesicle wall in addition to their single- and multi-layered structure and the variable thickness of the wall. These are: electron-tenuous and fibrous; electron-dense and homogeneous; electron-dense and homogeneous but perforated by radial canals; and composite laminated structure. Morphologically recognised groupings of acritarchs (acanthomorphic, disphaeromorphic, sphaeromorphic) and tasmanitid taxa appear to be characterised by particular features of the wall structure, although the wall structure in itself may not be directly indicative of systematic relationships. Structurally diverse vesicle walls are observed in Tasmanites and Leiosphaeridia, taxa that both have been interpreted, based on other lines of evidence, to be of prasinophycean (green algal) affinities. The distinct wall ultrastructure of the Leiosphaeridia studied is similar to that of extant green algal genera, which provides evidence that some Cambrian leiosphaerids were chlorophycean algae, probably related to the Order Chlorococcales. Previous research and interpretations of the wall ultrastructure are also briefly discussed.     

Ultrastructure and affinity of Lower Carboniferous megaspores from the Moscow Basin, Russia

Ten megaspore species isolated from Moscow Basin lignites of Lower Carboniferous (Viséan) age have been studied by scanning and transmission electron microscopy (SEM and TEM). These species belong to seven megaspore genera: Lagenicula, Sublagenicula, Crassilagenicula, Setosisporites, Zonalesporites, Caudatosporites, and Cystosporites. Megaspores of the genus Caudatosporites have only been described previously from the Duckmantian (Westphalian B); a new species is duly erected. The ultrastructure of megaspore walls from the genera Crassilagenicula and Zonalesporites has not been previously described. This study also places them in context with other contemporaneous megaspores. The study shows that during the Viséan, in the Moscow Basin, megaspores expressed a similar wall ultrastructure despite large differences in external appearance. The genus Crassilagenicula may represent a group of megaspores from plants that had evolved from those bearing gulate megaspores here typified by Lagenicula acuminata, Setosisporites brevispinosus, and Sublagenicula hirsutoida. Zonalesporites brasserti also appears to show affinities to this group, and may be representative of a plant species in a transitional state between the Lagenicula bearing lycopsids and those more isoetalean in nature.     

Ultrastructure and mineral composition of serpulid tubes (Polychaeta,Annelida)

We have studied the tube ultrastructure of 44 recent species from 36 serpulid genera. Twelve distinct ultrastructures are identified. Serpulids possess very diverse tube ultrastructures, in contrast with the traditional point of view. Most species show single‐layered tubes, but 34% of these species have between two and four ultrastructurally different layers. Tubes are mostly bimineralic, and are composed of aragonite and calcite; however, one of the polymorphs is always dominant. All the studied single‐layered tubes with a lamello fibrillar tube ultrastructure are exclusively calcitic; prismatic structures, both in regular or irregular orientation, are either calcitic or aragonitic in composition. There is no correlation between tube mineralogy, and ultrastructure, and marine, brackish, and freshwater environments. We find that 47% of the serpulid species studied possess a unique combination of tube structure characters. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 633–650.     

Structure and localization of sensilla on antennae of caddisflies (Insecta: Trichoptera)

Structure of antenna segments and ultrastructure of antennal sensillae in representatives of 28 caddisfly families from both modern suborders were studied by electron and light microscopy methods. On Trichoptera antennae, 16 types of sensillae were found, some of them being described for the first time. Morphological peculiarities of cuticular ultrastructures on the antennal surface demonstrate essential differences in structure both at the family level and at the lower taxonomic levels. Specialized sensory fields structurally different from the remaining antennal surface were revealed on antennal flagellae in representatives of the Phryganeina suborder. A new classification of sensillae based on the structure of their cuticular section is proposed.     

Micro‐ and nano‐scale ultrastructure of cell walls in Cryogenian microfossils: revealing their biological affinity

Moczyd?owska, M., Schopf, J.W. & Willman, S. 2009: Micro‐ and nano‐scale ultrastructure of cell walls in Cryogenian microfossils: revealing their biological affinity. Lethaia, Vol. 43, pp. 129–136. Recently established protocols and methods in advanced microscopy and spectrometry applied to studies of ancient unicellular organic‐walled microfossils of uncertain biological affinities (acritarchs) provide new evidence of the fine ultrastructure of cell walls and their biochemistry that support the interpretation of some such microfossils as photosynthesizing microalgae. The micro‐scale and nanoscale ultrastructure of the cell walls of late Cryogenian sphaeromorphic acritarchs from the Chichkan Formation (Kazakhstan) revealed by the advanced techniques and studied originally by Kempe et al. (2005) is here further analysed and compared with that of modern microalgal analogues. On the basis of such comparison, we interpret the preserved cell wall ultrastructure to reflect original layering and lamination within sub‐layers of the fossil wall, rather than being a result of taphonomic and diagenetic alteration. The outer thick layer represents the primary wall and the inner layer the secondary wall of the cell, whereas the laminated amorphous sub‐layers, 10–20 nm in thickness and revealed by transmission electron and atomic force microscopy, are recognized as trilaminar sheath structure. Because two‐layered cell walls, trilaminar sheaths and the position of the TLS within the fossil cell wall are characteristic of the mature developmental state in cyst morphogenesis in modern microalgae, we infer that the Chichkan sphaeromorphs are probably resting cells (aplanospores) of chlorophyceaen green microalgae from the order Volvocales. □Biological affinity, cell wall, Cryogenian, microfossils, ultrastructure.     

Intrinsic Innervation of a Reptilian Esophagus (Podarcis hispanica)

We study the esophagus of Podarcis hispanica through different methods to clarify the structure and affinities of its wall innervation. The acetylcholinesterase method reveals cholinesterase activity in two submucosal nervous plexuses, with an increasing degree of structural complexity in the reptilian esophagus, compared with amphibians. Noradrenergic innervation, detected through fluorescence induced by formol, widely spreads its network in both the myenteric and submucosal plexuses (around the blood vessels in the external submucosal plexus, and to the glandular lamina propria in the inner submucosal plexus). Immunohistochemistry for vasoactive intestinal peptide shows a widespread innervation, with neurons clustered in ganglia and also scattered through the VIPergic network, only at the myenteric plexus. Immunohistochemistry for substance P shows a rich innervation along the entire wall of the esophagus, more concentrated in its caudal region, around the blood vessels. Electron microscopy shows the enteric neuronal ultrastructure and its relationship with the esophagus wall.     

Instability of langmuir-blodgett layers of barium stearate,cadmium arachidate and tripalmitin,studied by means of electron microscopy and infrared spectroscopy

Results of an investigation of the stability of n-layers of barium stearate, cadmium arachidate and tripalmitin by means of electron microscopy and attenuated total reflection infrared spectroscopy are reported. Odd and even numbered barium stearate n-layers with n=1,2,3.4,5 are found to rearrange spontaneously from a regular film into ultrastructures of irregular, flat islands of varying thickness. The kinetics of the phase transformation of the first layer depends on the substrate, that of n-layers appears to be dependent on n, the temperature, and the surrounding medium. The kinetic behaviour of odd and even numbered layers is distinctly different. Similar studies on cadmium arachidate layers reveal much slower kinetics of the rearrangement process. In the case of tripalmitin n-layers it is shown that electron microscopy and infrared spectroscopy yield valuable complementary information about ultrastructure and molecular structure of the layers in correlation with the rearrangement process, which also occurs with this system. Consequences of the results of this paper for work published in various fields are briefly discussed.     

Instability of Langmuir-Blodgett layers of barium stearate, cadmium arachidate and tripalmitin, studied by means of electron microscopy and infrared spectroscopy.

Results of an investigation of the stability of n-layers of barium stearate, cadmium arachidate and tripalmitin by means of electron microscopy and attenuated total reflection infrared spectroscopy are reported. Odd and even numbered barium starate n-layers with n - 1,2,3,4,5 are found to rearrange spontaneously from a regular film into ultrastructures of irregular, flat islands of varying thickness. The kinetics of the phase transformation of the first layer depends on the substrate, that of n-layers appears to be dependent on n, the temperature, and the surrounding medium. The kinetic behaviour of odd and even numbered layers is distinctly different. Similar studies on cadmium arachidate layers reveal much slower kinetics of the rearrangement process. In the case of tripalmitin n-layers it is shown that electron microscopy and infrared spectroscopy yield valuable complementary information about ultrastructure and molecular structure of the layers in correlation with the rearrangement process, which also occurs with this system. Consequences of the results of this paper for work published in various fields are briefly discussed.     

The miracidium microanatomy of Philophthalmus rhionica (Trematoda: Philophthalmidae)

The study of ultrastructure of Philophthalmus rhionica miracidium was carried out. Update the ultrastructures of miracidium were studied in a restricted number of species belonging to the families Notocotylidae, Paramphistomatidae, Sanguinicolidae, Fasciolidae, Schistosomatidae (Galaktionov, Dobrovolsky, 1998). The ultrastructure of representatives of two latter families, Fasciola hepatica and Schistosoma mansoni respectively, have been examined most carefully. The family Philophthalmidae differs from the families Fasciolidae and Schistosomatidae by the aberrant pedogenetic miracidium.     

Ultrastructure of acidic polysaccharides from the cell walls of brown algae

We have studied the ultrastructure of acidic polysaccharides from the cell walls of brown algae using a variety of electron microscopy techniques. Polysaccharides from Padina gymnospora present self assembled structures, forming trabecular patterns. Purified fractions constituted by alginic acid and sulfated fucan also form well-organized ultrastructures, but the pattern of organization varies depending on the polysaccharide species. Alginic acid presents sponge-like structures. Sulfated fucan exhibits particles with polygonal forms with a polycrystalline structure. These particles are in fact constituted by sulfated fucan molecules since they are recognized by a lectin specific for alpha-l-fucosyl residues. X-ray microanalysis reveal that S is a constituent element, as expected for sulfated groups. Finally, an exhaustive purified sulfated fucan shows the same ultrastructure formed by polygonal forms. Furthermore, elemental analyses of acidic polysaccharides indicate that they retain Zn, when algae were collected from a contaminated area. This observation is supported by direct quantification of heavy metal in the biomass and also in the solubilized polysaccharides compared with the algae from a non-contaminated site. We conclude that these molecules have specific ultrastructure and elemental composition; and act as metal binder for the nucleation and precipitation of heavy metals when the algae are exposed to a metal contaminated environment.     

Microscopic Anatomy and Ultrastructure of a Polian Vessel in the Sipunculan Thysanocardia nigra Ikeda, 1904 from the Sea of Japan

The microscopic anatomy and ultrastructure of a Polian vessel have been studied in the sipunculan Thysanocardia nigra Ikeda, 1904 from the Sea of Japan using the methods of histology and electron microscopy. We describe ultrastructural features of the inner and outer coelothelium, which is constructed of podocytes and multiciliary cells. Between the processes of the podocyte cells, we found double diaphragms that are considered characteristic macromolecular filters. We conclude from an analysis of the ultrastructural features of the vessel wall that coelomic fluid may be filtered from the tentacular coelom to the trunk coelom via the wall of the Polian vessel.     

Ultrastructure of fibre and parenchyma cell walls during early stages of culm development in Dendrocalamus asper

BACKGROUND AND AIMS: The anatomy of bamboo culms and the multilayered structure of fibre cell walls are known to be the main determinant factors for its physical and mechanical properties. Studies on the bamboo cell wall have focussed mainly on fully elongated and mature fibres. The main aim of this study was to describe the ultrastructure of primary and secondary cell walls in culm tissues of Dendrocalamus asper at different stages of development. METHODS: The development of fibre and parenchyma tissues was classified into four stages based on light microscopy observations made in tissues from juvenile plants. The stages were used as a basis for transmission electron microscopy study on the ultrastructure of the cell wall during the process of primary and early secondary cell wall formation. Macerations and phloroglucinol-HCl staining were employed to investigate fibre cell elongation and fibre cell wall lignification, respectively. KEY RESULTS: The observations indicated that the primary wall is formed by the deposition of two distinct layers during the elongation of the internode and that secondary wall synthesis may begin before the complete cessation of internode and fibre elongation. Elongation was followed by a maturation phase characterized by the deposition of multiple secondary wall layers, which varied in number according to the cell type, location in the culm tissue and stage of shoot development. Lignification of fibre cell walls started at the period prior to the cessation of internode elongation. CONCLUSIONS: The structure of the primary cell wall was comprised of two layers. The fibre secondary cell wall began to be laid down while the cells were still undergoing some elongation, suggesting that it may act to cause the slow-down and eventual cessation of cell elongation.     

Spermatophore development and sperm ultrastructure inCraterostigmus tasmanianus (Chilopoda,Craterostigmomorpha)

 Spermatophore development and ultrastructure of the mature sperm of Craterostigmus tasmanianus were studied using light and electron microscopy. In C. tasmanianus, as in the Scolopendromorpha, the spermatophore develops within the vas deferens. The latter consists of three parts, each with a different morphology. The first may be involved in guiding the sperm to roll up into typical ring-like structures, while the other two, which show an evident secretory activity, secrete the acellular wall of the spermatophores. The ultrastructure of mature spermatozoa showed that a very close similarity exists between Craterostigmomorpha and Lithobiomorpha, especially regarding the organization of the connecting piece. Based on this similarity, we consider the Craterostigmomorpha together with the Scolopendromorpha, Geophilomorpha and Lithobiomorpha (=Pleurostigmophora) to be the sister group of the Scutigeromorpha. Accepted: 2 June 1996     

Spore wall ultrastructure of Polypodiaceae from north-western Argentina

The spore wall ultrastructure of Campyloneurum, Microgramma, Pecluma, Phlebodium, Pleopeltis and Serpocaulum (Polypodiaceae) from north-western Argentina has been studied using transmission electron microscopy (TEM). The exospore is 0.4–3 μm thick, two-layered and variously ornamented in all taxa. The exospore surface is distinctive, but in general ultrastructure the exospore is similar in all species studied. The structural elements of the exospore consist of cavities in the inner part as well as channels with a radial orientation and channels at both sides of the laesura. Variation in the exospore surface was observed in spores at different stages of maturation. The perispore is darkly contrasted and 0.04–2 μm thick. Three different structure types were recognised, including fibrillar, multilamellar and lacunose. Scattered globules and spherules were always present on the perispore surface. The structural variability of the perispore was surveyed within complete sporangia. We concluded that the observed variability may be related to the stage in spore maturation and, consequently, to the stages in perispore differentiation. As the exospore ultrastructure is similar and interpreted as related to functional activity in the studied material, it cannot be used for systematic delimitations at this generic or specific level.     

甜菜无融合生殖单体附加系M14花粉发生与发育的超微结构研究

运用透射电子显微镜技术,对甜菜无融合生殖单体附加系M14的小孢子发生、雄配子体发育以及相应的花药壁发育过程进行超微结构的观察研究,以阐明甜菜无融合生殖单体附加系M14花粉发生与发育超微结构特点以及花粉败育的时期和败育的细胞学特征.结果显示:(1)小孢子母细胞减数分裂正常,分裂期间细胞质具有明显的"细胞质改组"现象,主要表现在核糖体减少,质体、线粒体的结构发生规律性的变化,有利于孢子体向配子体的转变.M14减数分裂的胞质分裂为同时型,前期Ⅱ和中期Ⅱ形成"细胞器带";正常发育的花粉,小孢子分裂形成营养细胞和生殖细胞;生殖细胞脱离花粉壁,生殖细胞游离于营养细胞的细胞质中,最初具细胞壁,而后消失,且生殖细胞壁成分与花粉内壁成分相似.(2)三细胞型的成熟花粉含有一个营养细胞和两个具有尾突的精子;每个精子通过两层质膜与营养细胞隔开,含有一个大的精核,长尾突内含少量的细胞质以及纤丝状结构.(3)生殖细胞和精子中缺乏质体.(4)花粉的败育起始于小孢子,大部分受阻于单核-二细胞花粉期,其败育特征为花粉内液泡吞噬作用导致细胞器解体,绒毡层细胞过早解体或肥大生长致使营养供应受阻,可能是导致单核-二细胞花粉败育的主要细胞学原因.研究表明,白花甜菜第九号染色体的附加可能是导致M14大量花粉败育的遗传学因素.     

Microorganism in the hyphae of mycorrhiza-forming fungus]

A microorganism with the cell wall and cytoplasmic membrane was found when the endotrophic mycorrhiza of pea was studied by electron microscopy. The wall of the microorganism was in a close contact with the cytoplasm of the fungus. No changes were found in the ultrastructure of the fungus and microorganism caused by their interaction.     

Electron microscopic and electron radioautographic study of cells in glandular hyperplasia and cancer of the endometrium

Peculiarities of the ultrastructure and RNA synthesis in the epithelial endometrial cells of nine patients with hyperplasia and the uterine cavity cancer have been studied by the electron-radioautographic method. Quantitative differences are revealed in the ultrastructures of the cells. Amplification of the nucleoli labelling and asynchronism of the RNA synthesis in the nucleoli with glandular hyperplasia and endometrial cancer are observed.     

An intermediate-voltage electron microscopic study of freeze-substituted generative cell in pear (Pyrus communis L.): features with relevance to cell-cell communication between the two cells of a germinating pollen

The ultrastructure of the generative cell (GC) wall complex in germinating pear (Pyrus communis L.) pollen was studied with the aim of identifying features that may shed light on the mechanism of uptake of substances by the GC from its host, the vegetative cell (VC). The techniques of rapid freeze-fixation and freeze-substitution, serial sectioning, and conventional and intermediate-voltage transmission electron microscopy were employed. The wall complex consisted of two plasma membranes (PMs), one derived from the GC and the other from the VC. A nonfibrillar wall material occurred in the space between the two PMs. Plasmodesmata could not be identified in this wall complex. However, in localized areas the wall complex formed processes that protruded into the VC cytoplasm. In other areas, the wall complex showed certain cup-shaped invaginations. Certain double membrane bound multivesicular bodies occurred in the GC cytoplasm; their morphological characteristics indicated that they may have been derived from the GC wall complex. The data indicate that in pear the GC surface is amplified by wall processes, presumably to perform a role analogous to transfer cells.     

Ultrastructural effects of date extract on Candida albicans

The effect of Berhi date extract on the ultrastructure of Candida albicans was studied by scanning and transmission electron microscopy. Exposure of yeast to 5% (w/v) date extract showed evidence of weakening in the cell wall with indications of cell distortion and partial collapse in some cases as seen by scanning electron microscopy. Increasing the concentration of date extract (20%, w/v) led to more drastic damage to the yeast with cell lysis and concurrent leakage of cytoplasmic material with eventual cell death. Ultrastructural investigation showed irregular shapes of cells treated with date extract, with prominent effects on cell wall layers. Cell membranes lost their integrity, aggregation of the cytoplasmic contents and large detachment of plasmalemma from cell wall was observed in the treated cells. These results suggest that date extract may have multiple effects on Candida with an increasing potential of using it for prophylaxis purposes. This revised version was published online in June 2006 with corrections to the Cover Date.