A Method for Isolating and Preparing Silica Bodies in Grasses for Scanning Electron Microscopy

Silica bodies are discrete deposits of dehydrated silica within epidermal cells. To describe these bodies completely, surrounding organic and unsilicified material must be removed. Methods generally used for isolating and preparing silica bodies were unsuitable for most grass species. An effective method for studying grasses is described here. After ashing the plant tissue, the ash was repeatedly rinsed with HCl in a specialized multiple funnel manifold and collected on Nuclepore filters. In addition, the silica bodies were sonicated for a few minutes to remove any remaining mineral impurities. Compared to conventional procedures, this method has a number of advantages: unsilicified material and mineral impurities were removed effectively, smaller quantities of plant tissue could be used, and the loss of silica bodies was minimized.     

Morphological variations of lobate phytoliths from grasses in China and the south-eastern United States

Abstract. Phytolith analysis of grasses is a useful tool in palaeoenvironmental and archaeobotanical research. Lobate phytolith is one of the most important morphotypes of grass phytoliths. This study describes morphological variations of diagnostic lobate phytoliths and produces a tentative classification scheme based on 250 modern grass species from China and the south‐eastern U.S.A. Eighty‐five grass species were found to contain lobate phytoliths. They are derived mainly from Panicoideae, but also include the Chloridoideae, Oryzoideae and Arundinoideae subfamilies. Twenty‐five lobate morphological types were observed from different subfamilies, genera or tribes of grasses, based on two important parameters: (1) the length of the lobate shank and (2) the shape of the outer margin of the two lobes. The identification of grass tribe or even genus is possible based on the differences in lobate shape parameters or the composition of assemblages. However, not all of the lobate assemblages have a definite relationship with the genera that produce them, because grasses can only produce a limited range of lobate shapes that often overlap from one genus to another. Several C₃ grasses and Chloridoideae subfamily grasses also produce characteristic lobate phytoliths. The variations of lobate morphologies can be related to environmental factors, especially moisture. Typical hygrophytic grasses tend to yield lobate phytoliths with very short shank, whereas typical xerophytic grasses tend to produce lobate phytoliths with a very long shank. The potential link between phytolith morphology, grass taxonomy and environmental conditions opens the possibility that phytolith morphology may be used as a proxy in palaeoclimatic reconstruction.     

Variation of silica bodies in leaf epidermal long cells within and among seventeen species of Oryza (Poaceae)

Morphometric procedures were used with scanning electron microscopy backscattered images to study silica bodies in epidermal long cells of four different leaf veins of 17 of the 20 species of Oryza. The veins studied were midrib, large vein, small vein, and marginal vein. Image analysis was used to study morphological variations among the silica bodies. Statistical analyses were based on 11 variables. Even within a single leaf, silica bodies were not uniform. However, the degree of morphological variation normally showed a distribution of morpholgical types around one modal shape. The most significant differences observed were between silica bodies of the midrib and those of other veins. Bodies varied with respect to both size and shape. Computer-assisted image analysis is an effective tool for categorizing basic data and for statistical analysis of variation among silica bodies. Morphological variation among silica bodies of a single leaf may be related to water-conducting systems and their influence on silica availability and phytolith formation.     

Book Reviews

Nicotinic Acetylcholine Receptor: Structure and Function (NATO Advanced Science Institutes Series H: Cell Biology, Vol. 3) Edited by A. MAELICKE Springer-Verlag, Berlin

The Chemical Basis of Radiation Biology C. Von Sonntag Taylor & Francis

Advances in Free Radicals in Disease Corongiu, F.P., Tomasi, A. and Vannini

Modern Biological Theories of Aging Aging Series Vol. 31. WARNER, H.R., BUTLER, R.N., SPROTT, R.L. and SCHNEIDER     

Silica deposition in relation to ageing of leaf tissues in Sasa veitchii (Carriere) Rehder (Poaceae: Bambusoideae)

BACKGROUND AND AIMS: Silica deposition is one of the important characteristics of plants in the family Poaceae. There have been many investigations into the distribution, deposition and physiological functions of silica in this family. Two hypotheses on silica deposition have been proposed based on these studies. First, that silica deposition occurs passively as a result of water uptake by plants, and second, that silica deposition is controlled positively by plants. To test these two apparently contradictory hypotheses, silica deposition in relation to the ageing of leaf tissues in Sasa veitchii was investigated. METHODS: Tissues were examined using a light microscope and a scanning electron microscope equipped with an energy dispersive X-ray microanalyser. KEY RESULTS: The deposition process differed depending on cell type. In mesophyll tissue, fusoid cells deposited large amounts of silica depending on leaf age after maturation, while chlorenchyma cells deposited little. In epidermal tissue, comprised of eight cell types, only silica cells deposited large amounts of silica during the leaf's developmental process and none after maturation. Bulliform cells, micro-hairs and prickle hairs deposited silica densely and continuously after leaf maturation. Cork cells, guard cells, long cells and subsidiary cells deposited silica at low levels. CONCLUSIONS: The significance of these observations is discussed in relation to the two hypotheses proposed for silica deposition in Poaceae. The results of the present study clearly indicate that both hypotheses are compatible with each other dependent on cell types.     

Taxonomic variation in the subunit amino acid compositions of RuBP carboxylases from grasses

Subunits of purified RuBP carboxylase extracted from 44 grass species (39 genera) have been analysed and compared in terms of MWs, amino acid compositi     

The intranuclear bodies of Entamoeba

Intranuclear bodies which are spherical in shape are clearly seen by ‘Anoptral’ (negative) phase microscopy in the nucleus of Entamoeba. These bodies vary in size and numbers from cell to cell. With interference microscopy the intranuclear bodies appear as spherical granules in the nucleus of the cell. Their distribution and numbers are again very variable. With electron microscopy the bodies can be clearly seen inside the nucleus. They are always spherical in shape but vary in size from 0·1 to 1·5 μm. They may be empty or contain granular or membranous material. They display the capacity to move out of the nucleus.     

Deciphering human prehistory through the geoarcheological study of cave sediments

Throughout human history, caves and rockshelters have been favored habitation places. These unique environments preserve sediments derived from an assortment of geological and human processes that are typically absent or masked at open‐air sites. Cave sediments are parts of larger stratigraphic frameworks that can reflect environmental changes, shifting microenvironments, and the nature of human activity within these confined and sheltered spaces. Stone tools and faunal material compose the artifact assemblages from caves that are typically studied. Cave sediments, on the other hand, which encase the archeological finds and which have both geological and human origins, have been understudied relative to traditional artifacts, in spite of their ubiquity and importance. Thus, anthropogenic sediments, the most striking of which are organic‐rich deposits, and combustion features merit the same attention as any other artifacts that result from human activities and behaviors. The purpose of this paper is to highlight some of the most salient aspects of prehistoric cave sediments and the processes revealed by recent studies of these accumulations. We review methods and techniques that are used to analyze cave sediments and illustrate how their careful study can be used to reconstruct local and regional cave environments, as well as the nature of the human activities that produced them. Finally, we show how such study can place important constraints on our archeological interpretations, ultimately having a profound effect on how we decipher human prehistory.     

Occurrence of the genus Ophicrania Kaup (Insecta: Phasmatodea) in Panay island (Philippines) and description of a new species

A distinctive new species of the phasmatodean genus Ophicrania Kaup, 1871 (Phasmatidae: Platycraninae) is described and figured from the Philippines. Ophicrania conlei n. sp. (from Mount Madja-as, on Panay island) is characterized by the bicoloured anal region of the male hind wing, divided into an inner whitish patch, and an outer brownish area. The species is also distinguished from its most similar congeners on the basis of integumental coloration, features of the antennae, thoracic nota, wings, legs, and terminalia. The present study also provides an emended diagnosis of Ophicrania, and an updated checklist of the taxa of Platycraninae recorded from the Philippine archipelago.     

Taxonomic variation in total leaf protein amino acid compositions of grasses

Leaves of greenhouse grown grasses had free protein amino acid contents of generally less than 5 % total amino acids, while field collected grasses averaged 14.7 % free protein amino acid contents. Taxonomic patterns are detectable in the total leaf amino acid profiles of grasses from both sources, those of pooids being distinguishable from those of chloridoids and panicoids, and those of danthonioids showing an intermediate pattern. Leaf profiles of Oryza, Stipeae, and Ehrharteae resemble one another, and are more like those of pooids than those of panicoids. Variations in Thr and Leu are apparently associated with differences in photosynthetic pathway. Grass leaves are generally low in total amino acid contents (2.2 ? 1.0 g % fr. wt), with Ile, Val and Met + Cys identified as the limiting essential amino acids. However, the nutritional ‘chemical scores’ of grass leaf proteins are high (75 %, based on the WHO scoring pattern).     

Three-Dimensional Structure of Macronuclei from Paramecium Determined by Scanning Electron Microscopy*

SYNOPSIS. Macronuclei of Paramecium primaurelia were isolated and examined by scanning electron microscopy. These nuclei consisted of a closely packed array of chromatin bodies measuring ～ 0.2 μm in diameter. We estimated there were ～ 30,000 such bodies/macronucleus, 20 times more than the number of unit genome equivalents. This suggests that a unit genome is physically shared by several chromatin bodies.     

Difference of EGCg adhesion on cell surface between Staphylococcus aureus and Escherichia coli visualized by electron microscopy after novel indirect staining with cerium chloride

We developed a novel method using indirect staining with cerium chloride for visualization of the catechin derivative epigallocatechin gallate (EGCg) on the surface of particles, i.e., polystyrene beads and bacterial cells, by electron microscopy. The staining method is based on the fact that in an alkaline environment, EGCg produces hydrogen peroxide, and then hydrogen peroxide reacts with cerium, resulting in a cerium hydroperoxide precipitate. This precipitate subsequently reacts with EGCg to produce larger deposits. The amount of precipitate is proportional to the amount of EGCg. Highly EGCg-sensitive Staphylococcus aureus and EGCg-resistant Escherichia coli were treated with EGCg under various pH conditions. Transmission electron microscopy observation showed that the amount of deposits on S. aureus increased with an increase in EGCg concentration. After treating bacterial cells with 0.5 mg/mL EGCg (pH 6.0), attachment of EGCg was significantly lower to E. coli than to S. aureus. This is the first report that shows differences in affinity of EGCg to the cell surfaces of Gram-positive and -negative bacteria by electron microscopy.     

Systematic variation in amino acid compositions of grass caryopses

Variation in amino acid patterns of 121 species (72 genera) of grass caryopses is extensively consistent with taxonomic groupings. The patterns of pooids and chloridoids are distinguishable from one another and from those of eu-panicoids and andropogonoids; the bamboos, Oryza, Stipeae, Ehrharta and Microlaena, which share certain morphological and anatomical features, also share a characteristic amino acid profile, while profiles of danthonoioids, Triodia and Aristida are clearly non-pooid. Caryopsis amino acid patterns vary independently of photosynthetic pathway. Embryos from taxonomically diverse genera all show very similar amino acid profiles, which differ strikingly from those of the endosperms, and the amino acid patterns of whole caryopses are dominated by their endosperms, which are responsible for the taxonomic variation. ‘Chemical scores’ of the caryopsis proteins, but not total protein contents, correlate to some extent with taxonomic groupings.     

稻绿核菌无性孢子形成过程及厚垣孢子萌发率测定

对马铃薯蔗糖人工培养基(PSA)上绿核菌(稻曲病菌)不同培养时期的产孢情况进行了系统的扫描电镜观察。研究结果表明,在培养的前期(前20d),菌落表面往往形成集结状菌丝结构,其上开始产生大量分生孢子;一些分散的菌丝上也可产生少量的分生孢子。而在培养的后期,菌落表面往往形成黄色子实体,内部集生大量厚垣孢子。说明绿核菌在人工培养基上前期以形成分生孢子为主,后期则以厚垣孢子为主,且厚垣孢子的量远远大于分生孢子。萌发试验表明,成熟的厚垣孢子会随着保存时间的延长萌发率急剧下降。因此,新鲜的成熟厚垣孢子是最为理想的接种体。     

Collagen reorganization in leech wound healing

BACKGROUND INFORMATION: Leeches respond to surgical lesions with the same sequence of events as that described for wound healing in vertebrates, where collagen is important for the development of tensions in healing wounds, functioning as an extracellular scaffold for accurate regeneration of the structures disrupted by surgical or traumatic actions. RESULTS: In surgically lesioned leeches, newly synthesized collagen is arranged in hierarchical structures. Fibrils can be packed and shaped to form cords or tubular structures, thus acting as an extracellular scaffold that directs and organizes the outgrowth of new vessels and the migration of immune cells towards lesioned tissues. In these animals, the general architecture of collagen fibrils, generated during tissue regeneration, shows similarities to both the structural pattern of collagen bundles and assembly processes observed in several vertebrate systems (fish scales, amphibian skin and human cornea). CONCLUSIONS: The production of extracellular matrix during wound healing in leeches is a surprising example of conservation of an extremely close relationship between the structure and function of molecular structures. It could be hypothesized that collagen structures, characterized not only by a striking structural complexity, but also by multifunctional purposes, are anatomical systems highly conserved throughout evolution.     

A new method for non-destructive measurement of biomass, growth rates, vertical biomass distribution and dry matter content based on digital image analysis

BACKGROUND AND AIMS: Biomass is an important trait in functional ecology and growth analysis. The typical methods for measuring biomass are destructive. Thus, they do not allow the development of individual plants to be followed and they require many individuals to be cultivated for repeated measurements. Non-destructive methods do not have these limitations. Here, a non-destructive method based on digital image analysis is presented, addressing not only above-ground fresh biomass (FBM) and oven-dried biomass (DBM), but also vertical biomass distribution as well as dry matter content (DMC) and growth rates. METHODS: Scaled digital images of the plants silhouettes were taken for 582 individuals of 27 grass species (Poaceae). Above-ground biomass and DMC were measured using destructive methods. With image analysis software Zeiss KS 300, the projected area and the proportion of greenish pixels were calculated, and generalized linear models (GLMs) were developed with destructively measured parameters as dependent variables and parameters derived from image analysis as independent variables. A bootstrap analysis was performed to assess the number of individuals required for re-calibration of the models. KEY RESULTS: The results of the developed models showed no systematic errors compared with traditionally measured values and explained most of their variance (R(2) > or = 0.85 for all models). The presented models can be directly applied to herbaceous grasses without further calibration. Applying the models to other growth forms might require a re-calibration which can be based on only 10-20 individuals for FBM or DMC and on 40-50 individuals for DBM. CONCLUSIONS: The methods presented are time and cost effective compared with traditional methods, especially if development or growth rates are to be measured repeatedly. Hence, they offer an alternative way of determining biomass, especially as they are non-destructive and address not only FBM and DBM, but also vertical biomass distribution and DMC.     

Fine Structure of the Macronuclear Anlage of the Hypotrichous Ciliate Keronopsis rubra

In exconjugants of the hypotrich Keronopsis a large, highly polyploid macronuclear anlage is formed from which condensed chromatin bodies are passed into the cytoplasm where they are thought to give rise to the numerous small macronuclei of the vegetative cell. Electron microscopy shows that the chromatin bodies within the macronuclear anlage are separated from each other by sheets of low contrast lamellar material. The anlage appears therefore as a composite nucleus containing prepacked units which are extruded into the cytoplasm following condensation.     

Comparative genomics in the grass family: molecular characterization of grass genome structure and evolution

The genomes of grasses are very different in terms of size, ploidy level and chromosome number. Despite these significant differences, it was found by comparative mapping that the linear order (colinearity) of genetic markers and genes is very well conserved between different grass genomes. The potential of such conservation has been exploited in several directions, e.g. in defining rice as a model genome for grasses and in designing better strategies for positional cloning in large genomes. Recently, the development of large insert libraries in species such as maize, rice, barley and diploid wheat has allowed the study of large stretches of DNA sequence and has provided insight into gene organization in grasses. It was found that genes are not distributed randomly along the chromosomes and that there are clusters of high gene density in species with large genomes. Comparative analysis performed at the DNA sequence level has demonstrated that colinearity between the grass genomes is retained at the molecular level (microcolinearity) in most cases. However, detailed analysis has also revealed a number of exceptions to microcolinearity, which have given insight into mechanisms that are involved in grass-genome evolution. In some cases, the use of rice as a model to support gene isolation from other grass genomes will be complicated by local rearrangements. In this Botanical Briefing, we present recent progress and future prospects of comparative genomics in grasses.     

Über Hirnhautkörperchen des Kaninchens

Zusammenfassung Am Dach des III. Ventrikels in der Nähe des Splenium corporis callosi kommen umschriebene runde Körperchen vor. Diese Hirnhautkörperchen enthalten eine zentrale Gefäßzone, die von zwei Zellmänteln umgeben wird. In der Gefäßzone treten markscheidenfreie präsynaptische Nervenfasern unmittelbar an die Arterie und die Kapillaren heran. Die hellen Zellen des inneren Mantels sind durch hohen Glykogengehalt und durch zahlreiche Vakuolen charakterisiert. Die Interzellularspalten sind stellenweise verbreitert und angefüllt mit sauren Mukopolysacchariden. Der äußere Mantel, der unmittelbar das Hirnhautkörperchen umgibt, besteht aus dicht gepackten dunklen Zellen. Diese enthalten zahlreiche Mitochondrien und Filamente, die in eine dichte amorphe Matrix eingebettet sind und für kontraktil gehalten werden. Beide, der innere und der äußere Mantel, werden von Bündelchen kollagener Fasern durchzogen. Die enge Nachbarschaft zu Blutgefäßen und Plexus chorioideus läßt vermuten, daß die Hirnhautkörperchen mit der Kontrolle der Blutströmung zu tun haben.

---

On leptomeningeal bodies in the rabbit

Summary On the roof of the 3rd ventricle of brain near the splenium corporis callosi circumscribed round bodies occur. These leptomeningeal bodies contain a central vascular zone enveloped by two sheaths of cells. In the vascular zone, some unmyelinated presynaptic nerve fibers can be seen very close to the artery and to the capillaries. The clear cells of the internal sheath are characterized by a high content of glycogen and by numerous vacuoles. The intercellular spaces are sporadically enlarged and filled with acidic nucopolysaccharides. The external sheath immediately surrounding the leptomeningeal body consists of densely packed dark cells. These cells contain numerous mitochondria and filaments embedded in a dense amorphous matrix. The filaments are interpreted as a contractile material. Both, the internal and external sheath, are trasversed by bundles of collagenous fibers. The close association with blood vessels and choroid plexus suggests that the leptomeningeal bodies are involved in blood flow control.

Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft (Le 69/7).