Ultrastructural aspects of beech bark degradation by fungi

The degradation of beech bark by three wood-decaying fungi has been analyzed at the ultra-structural level and the micromorphological changes occurring in the walls of the diverse cell types compared with the decay pattern in wood cells.     

On the formation and fine structure of septate wood fibres of Ribes sanguineum

Summary The septate wood-fibres of Ribes sanguineum result from a genuine mitosis of the still functioning nucleus in lignified cells. The development of the septa occurs first in the vicinity of protoxylem and spreads centrifugally outwards and from the basis of the shoot towards the vegetative apex. Because there is no wall-layer fusion of the septum with the fibre-wall, the terms chambers or compartments are proposed for the partitions resulting from cytokinesis. The septum is built up by a middle lamella with primary-wall structures and plasmodesmata; it possesses a cellulose-pectin character and does not evince secondary wall appositions or lignification.During septum development a definite trend in the cytoplasmic organization of the living wood fibres is indicated. The probable significance of the various cytoplasmic organelles for the development and structure of the septa is discussed.

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Zusammenfassung In den septierten Holzfasern von Ribes sanguineum Pursh entwickeln sich die Septen durch eine echte Mitose des aktiven Kernes. Die dabei entstehenden Aufteilungen werden als Kammer oder Fächer bezeichnet. Histochemische Versuche ergaben für die Septen eine Cellulose-Pektin-Struktur. In keiner Phase der Entwicklung erfolgt eine Sekundärwandauflage oder eine Lignifizierung. Die Septen zeigen zu der lignifizierten Wand der Faserzelle keine wandanaloge oder schichtengleiche Verbindung. Submikroskopisch weisen sie eine Primärwand-ähnliche Struktur mit einer deutlich ausgebildeten Mittellamelle und Plasmodesmen auf.In den septierten Holzfasern konnten jahreszeitliche Veränderungen in der cytoplasmatischen Organisation beobachtet werden. Nach der Septenbildung nimmt die Anzahl der Dictyosomen ab, verbunden mit einer zunehmenden Vakuolisierung und Entwicklung der Stärkekörner. Die mutmaßliche Bedeutung der cytoplasmatischen Organellen für die Septenbildung wird diskutiert.

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Dedicated to Prof. Dr. Dr. h.c. Bruno Huber on the occasion of his 70th birthday.     

Variation of cell length in bark and wood of tropical trees

Summary The variation in length of cell elements both in bark and wood of a few tropical trees (Mangifera altissima, Mansonia altissima, Pentacme contorta, Pterocarpus marsupium, Shorea megrosensis, Shorea squamata, Triplochtion scleroxylon) is described. The phloem fibres and sieve tube members show a tendency for increase in length from periderm to cambium, just as the wood fibres and vessel members increase from pith to cambium. The phloem fibres are generally longer than wood fibres (40–70%). In woods with storeyed cambia the sieve tube members exhibit no variation, retaining a constant length throughout the width of the bark; the phloem fibres possess the normal trend of a length increase from periderm to cambium. The length variation of sieve tube members and phloem fibres with the height of the tree generally exhibits a decreasing trend from butt to top, although a slight increase in length of phloem fibres at the top was noticed.Presented at the IUFRO Division V Meeting, September 1973, Cape Town, South AfricaThanks are due to Mrs. K. Puchstein for help with the measurements. The financial support by the Deutsche Forschungsgemeinschaft and the Gesellschaft der Freunde und Förderer der Bundesforschungsanstalt für Forst- und Holzwirtschaft, Reinbek, is also gratefully acknowledged.     

Homologies between prolamins of different minor millets

Minor millets, viz. Barnyard millet, Proso millet, Little millet, Foxtail millet and Kodo millet, one variety in each grown in Tamil Nadu Agricultural University (TNAU), Coimbatore, Tamil Nadu were selected for the study. The protein contents of the selected decorticated millets were found to be 11.0, 12.3, 12.9, 10.5 and 10.6% respectively. Fractionation of these proteins revealed that prolamin forms major storage protein in Foxtail millet whereas, glutelin forms major storage protein in all the other millets. The extractability was studied using different solvents, viz. isopropyl alcohol, t-butyl alcohol and ethyl alcohol with varying concentration of 2-mercapto ethanol. Electrophoretic pattern of the extracted prolamins from these millets were compared and found that a protein band at the molecular weight range of 20 kD was found homologous in all except Proso millet. The extractability of the 20kD protein in 90% isopropyl alcohol showed its strong hydrophobic nature.     

Isolation and characterization of a 20 kD prolamin from kodo millet (Paspalum scrobiculatum) (L.): Homology with other millets and cereals

The homologus 20 kD prolamin from kodo millet and other minor millets viz. barnyard, little and foxtail millets, were purified using preparative gel electrophoresis and reversed phase high performance liquid chromatography (RP-HPLC). The amino acid composition of the purified 20 kD prolamin protein from different minor millets revealed higher content of glutamic acid, alanine, leucine and serine and lower quantity of lysine and methionine. They contain 55 to 58 percent of non-polar amino acids which make them more hydrophobic than other protein fractions. The total number of amino acid residues per polypeptide chain ranged from 152 to 155 based on theoretical calculation. Peptide mapping of the 20 kD prolamin hydrolyzed with trypsin gave fewer cleavage products than expected. The antigenic relationships among these minor millets and cereals viz. wheat, maize, rice, sorghum, finger millet and pearl millet were studied using the antibody raised against the 20 kD prolamin. Cross reactivity was seen in all the minor millets at the 20 kD region. But in barnyard and little millets lower molecular weight polypeptides also cross reacted with the antibody. Immunoblotting studies revealed that the prolamins from other cereals and millets are related to the 20 kD prolamin of kodo millet. Rice was the only common cereal that did not cross react immunologically with the antibody raised against 20 kD prolamin of kodo millet.     

Susceptibility of betanodavirus in a newly established vertebra-derived cell line from Mosquitofish (Gambusia affinis)

In the present study, a new cell line from the vertebra of mosquitofish Gambusia affinis was successfully established and characterized. The cell line is named as bone Gambusia affinis (BGA) and subcultured for more than 55 passages in Leibovitz's/L15 medium supplemented with 15% FBS at 28°C. The cell line has a modal chromosome number of 48. Molecular characterization of the partial sequence of the coi gene confirmed the origin of the BGA cell line from mosquitofish. These cells exhibited epithelial morphology confirmed by the cytokeratin marker. The BGA cells showed mineralization of their extracellular matrix when stained with alizarin red and von Kossa stain. BGA cells were found to be susceptible to RGNNV and SJNNV strains of betanodavirus (NNV) showing cytopathic effect with multiple vacuolations in the cells. The RT-PCR confirmed the betanodavirus infections in BGA cells. The SEM micrograph showed the morphological changes observed in the cell during virus infection. The in vivo challenge experiment also showed the viral replicating efficiency in the Gambusia affinis with increasing viral titre. Thus, our present results show that the BGA cell line is a useful tool for isolating betanodavirus and could be used to investigate bone cell differentiation and extracellular matrix mineralization.     

Micromorphology of naturally degraded beech and spruce barks

The micromorphological changes occurring in the bark tissues of beech and spruce trees during natural degradation in the forest have been investigated and compared with those obtained previously using wood-decaying fungi. The relevance of the bark degradation process for the environment is also briefly discussed.     

On the origin of phenolic compounds in the wood rays of Abies alba

Summary The development and localization of phenolic compounds in sapwood and heartwood of Abies alba Mill. have been studied using cytological and UV-microspectrophotometric methods. The synthesis of phenolic substances was apparently initiated in vesicles developing from rough ER of the ray parenchyma cells in sapwood. They are different from the phenolic material in the pit membrane and cell wall of heartwood. There was no indication to suggest that the polyphenols in the cell wall of heartwood were either derived from or identical with the phenolic substances in the lumina of ray cells.Dedicated to Prof. Dr. H. von Pechmann on the occasion of his 70th birthdayWe are thankful to Professor Dr. Walter Liese for his support and to Mrs. R. Schultze and Miss R. Endeward for technical assistance.     

Über das Vorkommen von Rickettsien-ähnlichen Bakterien und Mykoplasmen-ähnlichen Organismen in Buchen aus Waldschadensgebieten

The occurrence of rickettsia-like bacteria and mycoplasma-like structures is reported from the roots and secondary phloem of beech trees from areas in Black Forests and Lower Saxony affected by forest die-back. The significance of the presence of these primitive organisms for the premature yellowing of leaves observed has still to be solved.     

On the fine structure of bamboo fibres

Summary The thick-walled bamboo fibres exhibit a polylamellate structure with alternating broad and narrow lamellae. Characteristically the cellulose fibrils in the broad lamellae are oriented almost parallel to the longitudinal axis of the fibre (2–20°), whereby there is a gradual but only slight increase in the angle from middle lamella to lumen. The narrow lamellae consist of fibrils oriented almost perpendicular to the cell axis (85–90°); this angle remains constant in all the successive narrow lamellae. The concentration of lignin is higher in the narrow lamellae than in the broad ones. Xylan seems to occur in a higher concentration in the narrow lamellae. The pits between the fibres are bordered. The results are discussed in relation to earlier data on wall structure and development. A model for the thick-walled bamboo fibre is presented with a new terminology for the various lamellae.We are thankful to Mrs. R. Schultze and Miss B. Schröder for their technical assistance. Grateful acknowledgement is also due to Dr. D. Keyser and Mrs. K. Hoffmann for the SEM facilities and to Prof. Dr. J. Bauch and Mrs. R. Endeward for the UV-microspectrophotometry. Prof. T. E. Timell (Syracuse) and Dr. O. Faix were helpful with the preparation of hydrofluoric acid concentrations.