Mallomonas robusta (Chrysophyceae,Synuraceae): Electron microscopical study of silica armour

Mallomonas robusta (Matvienko)Péterfi & Momeu (Mallomonopsis robusta) has been investigated by transmission electron microscopy and is redescribed in detail. Its silica armour, consisting of scales and bristles, exhibits a very peculiar fine structural pattern. Differences and possible relationships with other species are discussed. The Romanian material is designated as the nomenclatural type (neotype).     

Stalked bacteria in activated sludge

Summary A laboratory-scale activated sludge unit was fed continuously with a simulated industrial wastewater, consisting of a dilute solution of inorganic salts, at a rate giving a mean retention time of about 3 days. The system produced a well-settling sludge which on examination by electron microscopy was found to contain considerable numbers of stalked bacteria. These were identified as Caulobacter, which have the ability to attach to surfaces and other organisms by means of a prosthecal holdfast and to flourish in waters with a low content of organic nutrients, and whose occurrence in activated sludge has not apparently been previously recorded. Conditions advantageous to Caulobacter generally prevail in activated sludge systems when these operate in growth phases tending to produce well-settling sludge. Since their holdfast gives Caulobacter the ability to initiate and enlarge microbial clusters by attachment, it is suggested that Caulobacter contribute to microbial floc-formation in activated sludge.     

An electron microscopic study of the central lacteal in the intestinal villus of the cat

Summary Electron microscopy revealed the presence of the central lacteal in the intestinal villus of the cat. Serum injection was found to distend it. It appeared as a vessel of about 10 to 12 in diameter located in the center of the villus, with a wall consisting of a continuous endothelium and delicate connective-tissue fibrils. The most significant structural difference between lacteal and blood capillary of the villus is thought to be the absence of a basement membrane from the former. The probable biological importance of the fine structure of the central lacteal is discussed.     

Presence of plastid and absence of mitochondrial DNA in male reproductive cells as evidence for cytoplasmic inheritance in Turnera ulmifolia and Zantedeschia aethiopica

Summary. Epifluorescence microscopy of mature pollen grains of Turnera ulmifolia and Zantedeschia aethiopica stained with 4,6-diamidino-2-phenylindole demonstrated the presence of fluorescent cytoplasmic DNA aggregates in the male reproductive cells of both species. Double staining of the cells with 4,6-diamidino-2-phenylindole and 3,3-dihexyloxacarbocyanine iodide in Technovit resin sections showed that the mitochondria of these cells did not correspond to the fluorescent cytoplasmic DNA aggregates. Electron microscopy studies revealed both plastids and mitochondria in the cells of these species. In addition, immunoelectron microscopy using an anti-DNA monoclonal antibody showed clear labeling of plastids but not mitochondria. These data provide cytological evidence for biparental plastid inheritance and maternal mitochondrial inheritance in these species.Correspondence and reprints: College of Life Sciences, Peking University, Beijing 100871, Peoples Republic of China.     

Lampenbürstenchromosomen und Amphinukleolen in Oocytenkernen der Schnecke Bithynia tentaculata L.

The oocyte nuclei of Bithynia tentaculata have been investigated by light and electron microscopy. The small oocyte nuclei of the pachytene stage are characterised by a well developed bouquet arrangement of the chromosomes, a small nucleolus located at the nuclear envelope and lamellar inclusions of unknown function. During previtellogenesis, oocytes contain typical molluscan amphinucleoli consisting of the nucleolus and the so called Proteinkörper. It is suggested, that the Proteinkörper is identical with the Binnenkörper of insects. Living oocyte nuclei of Bithynia have been isolated and investigated by phase contrast microscopy. They contain lampbrush chromosomes bearing chromomeres, pairs of lateral loops and some spheres. Maximal loop formation occurs early in oogenesis whereas chromosomes of later developmental stages show contraction of the loops and formation of many spheres. Their histochemistry and ultrastructure is described.

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Mit Unterstützung durch die Stiftung Volkswagenwerk.     

Glycoconjugates in the secretory epithelium of the chicken mandibular gland

Summary In the secretory epithelium of the chicken mandibular gland, glycoconjugates have been studied by means of histochemical methods of light and electron microscopy. In light microscopy, a series of histochemical procedures have been employed which included lectin—peroxidase—diaminobenzidine methods and a digestion technique with neuraminidase or-amylase. In electron microscopy, a battery of methods were used that corresponded to those employed in light microscopy. In the secretory cells of the chicken mandibular gland, vicinal diol- and sulphate-containing glycoconjugates with sialic acid,-d-mannose,-d-glucose and-d-galactose residues were visualized and the possible histophysiological significances of such glycoconjugates were discussed with special reference to the functions of the salivary gland.     

Antimicrobial mechanism of β-glycyrrhetinic acid isolated from licorice, Glycyrrhiza glabra

-Glycyrrhetinic acid isolated from Glycyrrhiza glabra had an antibacterial activity of 7.6 and 12.5 g ml^–1 against Bacillus subtilis and Staphylococcus epidermidis without causing hemolysis of human erythrocytes, whereas it was not inhibitory against Escherichia coli, Proteus vulgaris and various fungi. Confocal microscopy showed that -glycyrrhetinic acid was located within the bacteria but had not caused membrane disruption. It then inhibited synthesis of DNA, RNA and protein.     

Estimating the age of Antarctic larval fish from otolith microstructure using light and electron microscopy

Larval fish of Antarctica have very narrow rings on their otoliths (<1 m) that may not be resolved with light microscopy. In this study, age data from the otoliths of larval Nototheniidae (Gobionotothen gibberifrons and Lepidonotothen larseni), determined using light and scanning electron microscopy, are compared. Rings 0.4 m wide were observed on otoliths viewed under electron microscopy; however, light microscopy could only resolve rings 0.5 m wide. Scanning electron microscopy is more time consuming and costly than light microscopy but has greater resolving power and is recommended to validate ring counts made using light microscopy in otolith studies with Antarctic larval fish.     

A pineal ganglion associated with the pineal tract in the domestic fowl

Summary A ganglion-like aggregate consisting of acetyl-cholinesterase-positive neurons was demonstrated in the pineal organ of the domestic fowl by means of light and electron microscopy. This ganglion is located in juxtaposition with the pineal tract at the posterior (caudal) aspect of the pineal stalk. Numerous large and small neurons formed the ganglion in 40-day-old domestic fowl. Some of these nerve cells established direct neuro-neuronal contacts, others were surrounded by satellite cells. These ganglion cells displayed axo-somatic and axo-dendritic synapses. The above-mentioned cluster of nerve cells may be considered as a pineal ganglion. Its central or peripheral nature is open to discussion. Send offprint requests to: Dr. K. Wake, Department of Anatomy, Faculty of Medicine, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, 113, Japan     

Free-swimming Cellular Complexes in the Coelom of the Sipunculid Thysanocardia nigra Ikeda, 1904 (Sipuncula)

The ultrastructural characteristics of coelomic cell complexes in the coelomic fluid were investigated with the use of transmission electron microscopy on the example of Japanese sipunculid. In the sipunculid coelom, complexes consisting of several cells were found for the first time: the central glandular cell and the outer layer of podocytes. Peculiar cell complexes (urns), comprising by ciliary and granular cells, were described in Thysanocardia for the first time. It had been proposed that both types of coelomic cell complexes dissociated from extensive chloragogenic tissue clusters on the intestine surface of Th. nigra. The variety of cell complexes in the coelom of other sipunculid is discussed.     

Isolation of a novel rod shaped methanogen growing on methanol and 2-propanol

A methanogen utilizing methanol was isolated from a reactor anaerobically degrading leaves of Leucaena leucocephala. The cells are rods of length 2.2 m with diameter 0.46 m also occurring in short chains. The cells stain gram-positive and the G+C content is 52.8 mol%. Growth occurred optimally with methanol (0.1 M) at 37°C and pH 7.4 with a doubling time of 7.5 h. The preferred sulfur source was glutathione. In addition to methanol, the isolate utilized 2-propanol as carbon and hydrogen source and also grew effectively on H₂+CO₂. Electron microscopy revealed the cell enveloped in triple layers consisting of a cell membrane and a cell wall separated by an electron transparent space with the nuclear zone at the centre of the cytoplasm. Presence of cytochromes was evident in the membrane fractions. The isolate possesses novel features.     

The fine structure of the cartilage in the annelidSabella penicillum

Summary The fine structure of the tentacular cartilage cells of the annelidSabella penicillum has been studied by scanning (SEM) and transmission electron microscopy (TEM). The cells contain a large, transparent vacuole centrally, and a thin layer (>0.1 m) of cytoplasm around. Some granular endoplasmic reticulum, mitochondria and smaller clear vesicles are present in the cytoplasm. The nuclei are dense in the TEM preparations. The surrounding matrix is most dense close to the cells, and form a chondroid matrix, 0.2 to 0.5 m thick, consisting of a flocculate material. The boundary to the surrounding matrix is condensed in the central cartilaginous cells, but not in the pinnular. The rigid structure of the close chondroid matrix is demonstrated in the SEM. The structure is compared to other invertebrate cartilages so far described, and its functions are discussed.     

Localization of α-galactomannan on the surface of Schizosaccharomyces pombe cells by scanning electron microscopy

Galactomannan was localized by scanning and transmission electron microscopy on the cells and cell walls of Schizosaccharomyces pombe. The markers were prepared from colloidal gold granules labelled with an -galactopyranosyl-binding lectin isolated from the seeds of Bandeiraea simplicifolia. Part or all of this -galactomannan was present in the outer layer of the cell wall and was uniformly distributed even on the fission scars.Non-Standard Abbreviations Au lectin-labelled colloid - SEM scanning electron microscopy - TEM transmission electron microscopy     

Molecular analysis of a Bjerkandera adusta lignin peroxidase gene

Summary A cDNA clone, LPO-1, encoding a major lignin peroxidase from the basidiomycete Bjerkandera adusta was isolated and characterized. The nucleotide sequence of LPO-1 predicts a mature protein consisting of 349 amino acids with a molecular weight of 37,225 preceded by a signal peptide of 23 amino acid residues. We have also cloned and sequenced the gene encoding lignin peroxidase from B. adusta. Comparison of these sequences reveals a lignin peroxidase gene structure consisting of 1,116 bp of protein-encoding DNA that is interrupted by four intervening sequences. The putative eukaryotic regulatory sequence, a TATA box, is present at position — 75 relative to the translational initiation codon. Amino acid sequence homology between the coding regions of LPO-1 and of the lignin peroxidase cDNA clone ML-1 from Phanerochaete chrysosporium is 61%. Offprint requests to: M. Kuwahara     

15-Cis-β-carotene found in the reaction center of spinach Photosystem I

-Carotene was extracted from spinach Photosystem I reaction centers (one consisting of the Psa A, B, C, D and E subunits and the other consisting of the Psa A and B subunits alone), and the extract was subjected to high-pressure liquid chromatography using an apparatus equipped with a two-dimensional diode-array detector; all the procedures were performed at 4 °C in complete darkness. Both 15-cis and all-trans--carotene were identified in the extract by means of electronic absorption spectroscopy. Thus, universal presence of 15-cis carotenoid in the reaction centers of purple photosynthetic bacteria and of spinach Photosystem I and Photosystem II has been shown.Abbreviations Chl- chlorophyll - DEAE- diethylaminoethyl - DMF- dimethylformamide - HPLC- high pressure liquid chromatography - LHC- light-harvesting complex - PS- Photosystem - RC- reaction center - RC_a,b- reaction center consisting of Psa A and B subunits alone - RC_a-e- reaction center consisting of Psa A, B, C, D and E subunits     

Fine-structural characteristics of the liver of the cod (Gadus morhua macrocephalus), with special regard to the concept of a hepatoskeletal system formed by Ito cells

Summary The liver of the adult cod (teleost, Gadus morhua macrocephalus) was observed with transmission and scanning electron microscopy. Hepatocytes of this animal are extremely large (about 50–70 m in diameter) and characterized by numerous large lipid droplets (5–15 m in diameter) showing fluorescence for vitamin A, though weaker than that of Ito cells. No Kupffer cells were recognized in the endothelial lining. Collagen fibrils are sparse in the perisinusoidal space, while Ito cells stretching their long cytoplasmic processes to the perisinusoidal as well as interparenchymatous spaces are frequent. There are a number of large desmosomes between the cytoplasmic processes, and all Ito cells seem to be interconnected by these junctions. The cytoplasm in the cell bodies and cell processes is occupied by bundles of intermediate filaments, while organelles are poorly developed. Small vesicles and caveolae are arranged along the plasma membrane. Scanning electron microscopy shows distinct three-dimensional networks consisting of Ito cells and their processes, which might be supporting elements of the liver tissue. We wish to emphasize the concept of this hepatoskeletal system.     

Intravital microscopy of the lung: minimizing invasiveness

In vivo microscopy has recently become a gold standard in lung immunology studies involving small animals, largely benefiting from the democratization of multiphoton microscopy allowing for deep tissue imaging. This technology represents currently our only way of exploring the lungs and inferring what happens in human respiratory medicine. The interest of lung in vivo microscopy essentially relies upon its relevance as a study model, fulfilling physiological requirements in comparison with in vitro and ex vivo experiments. However, strategies developed in order to overcome movements of the thorax caused by breathing and heartbeats remain the chief drawback of the technique and a major source of invasiveness. In this context, minimizing invasiveness is an unavoidable prerequisite for any improvement of lung in vivo microscopy. This review puts into perspective the main techniques enabling lung in vivo microscopy, providing pros and cons regarding invasiveness.

     

Development and characterisation of a line of bread wheat,Triticum aestivum,which lacks the short-arm satellite of chromosome 1B and the Gli-B1 locus

Summary About 360 offspring of a tri-parental cross were screened by gel electrophoresis and unexpectedly one of them did not contain chromosome 1B -gliadins derived from either of the primary parents. A line disomic for the -gliadin null was developed from the surviving embryo half of the unique grain. Two dimensional electrophoresis revealed that all the storage protein genes at Gli-B1, coding for -gliadins, -gliadins and low-molecular-weight subunits of glutenin as well as the -gliadin, were not expressed. The nuclei of dividing root-tip cells were shown by light microscopy to lack the normal short-arm satellites of chromosome 1B, indicating that the genes for the missing storage proteins had been lost through a terminal deletion. Using a radioactive ribosomal RNA probe, the deficient 1B chromosomes were shown to contain ribosomal RNA genes demonstrating that at least two-thirds of the short arm was still present. Examination of serial sections of chromosome 1B at metaphase by low-power electron microscopy showed that the point of scission of this chromosome was within the secondary constriction where the ribosomal RNA genes are located. The Gli-B1 locus must therefore be carried on the short-arm satellite. Transmission of the deficient chromosome from female gametes to progeny was normal (i.e., about 50%) but from pollen it was poor (8.8%). Recombination mapping indicated that the distance from the ribosomal RNA genes (Nor1) to Glu-B1 was 22 cM, equivalent to 13 cM from Nor1 to the centromere.     

The nature of inbreeding in a seed orchard of Douglas fir as shown by an efficient multilocus model

Summary The amounts of self-fertilization versus consanguineous matings (as measured by effective selfing) was estimated in a seed orchard of Douglas-fir, using progeny array data at six allozyme loci. The orchard is family structured, consisting several grafts (clones) and/or open-pollinated (o-p) progeny from each of several plus-trees. Population-wide selfing rates were found to be 7% for the o-p trees and 2% for the cloned trees. Estimates of mating system parameters for individual trees showed this difference for average outcrossing rate t (1) still largely remained when outcrossingpollen gene frequency p was not allowed to vary among trees and (2) disappeared when p was allowed to vary among trees. Under this joint t and p estimation, o-p trees showed both significant variation of t (based upon a one-way ANOVA grouped by common plus-tree) and significant regressions of p on ovule genotype (indicative of consanguineous matings); cloned trees showed neither. This higher rate of consanguineous mating for o-p trees might be explained by the larger and more variable size of o-p families in the orchard. Estimates of outcrossing rate t and outcrossingpollen gene frequency p were based upon a multilocus model which makes full use of the information in the data. The increased information it gives over observed outcross models is equivalent to adding 30–50% more loci, and it gives enough degrees of freedom to jointly estimate t and p for individual trees (individual progeny arrays) under certain conditions. In addition, inclusion of megagametophyte data nearly doubles the information about the mating system of individual trees.     

The occurrence of a premature form of egg-specific protein in vitellogenic follicles ofBombyx mori

Summary Analysis of yolk proteins of the silkworm,Bombyx mori, by SDS-polyacrylamide gel electrophoresis and immunoblotting showed that there was a developmental change in subunit composition of egg-specific protein; egg-specific protein consisting of 72 kDa subunits alone (premature form) was found in vitellogenic follicles, whereas the protein in mature eggs was composed of 72 kDa and 64 kDa subunits (mature form). The premature form of egg-specific protein was purified from young ovaries to homogeneity using a high performance liquid chromatography system. The purified protein had an apparent molecular mass of 225 kDa which could not be distinguished from that of the mature form. By circular dichroism analysis, both egg-specific proteins were estimated to have about 30% -helix and 20% -sheet, but the mature form showed a relatively rigid conformation in the aromatic region. The premature egg-specific protein purified from vitellogenic ovaries, consisted of three 72 kDa subunits, whereas mature egg-specific protein was composed of two 72 kDa subunits and one 64 kDa subunit. All of these subunits showed the same immunoreactivity towards antiserum raised against the mature form. An identical NH₂-terminal amino acid sequence was found in both 72 kDa polypeptides and 64 kDa polypeptide for the initial 10 amino acids.Abbreviations SDS sodium dodecyl sulfate - PMSF phenylmethylsulfonyl fluoride - PAGE polyacrylamide gel electrophoresis - HPLC high performance liquid chromatography - ESP egg-specific protein - Vtn vitellin