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1.
Lidija Murmanis 《Wood Science and Technology》1970,4(1):1-14
Summary The results of this investigation by electron microscopy on the vascular cambium in Pinus strobus L. confirm the results of earlier investigations by light microscopy. First, they showed that differences in the thickness of tangential walls of cambial cells exist and that these differences permit grouping of cells according to the sequence of the previous divisions of the initial. This, in turn, permits the site of the initial cell in the cambial zone to be deducted. The thicker distal tangential wall of the initial in the successive series of tissue production allows for precluding the direction in which the initial function proceeds, toward the xylem or toward the phloem. Second, it was demonstrated that immature xylem cells exist in groups of four, that immature phloem cells exist in pairs, and that at all times more cells are produced toward the xylem than toward the phloem. Third, it was shown that the extra-thick tangential wall in immature xylem serves as a landmark to signal the changeover in the initial function from phloem to xylem production. 相似文献
2.
Secondary xylem, or wood, is the tissue that conducts water and minerals in the tree; thus it performs physiologically one of the most important functions for the tree. In addition secondary xylem is the tissue that primarily determines the suitability of a tree for various economic uses.Investigation of the development of secondary xylem shows that it was gradual. Xylem mother cells, the immediate derivatives of cambial initals, were, at first, small cells with thin cell walls. Then the xylem mother cells enlarged radially, but still retained thin cell walls. When these cells reached the radial diameter of mature tracheids, the secondary wall deposition began. This continued until thick, rigid cell walls were attained. These thick, rigid walls determine the physical properties of a certain species of wood. This investigation shows that physical properties of tracheids can differ with stages of development.
This report is based on portions of work in fulfillment of the requirements for the Ph.D. degree in Botany at the University of Wisconsin.
Maintained at Madison, Wisconsin, 53705, U. S. A., in cooperation with the University of Wisconsin. 相似文献
Zusammenfassung Das Sekundärxylem, oder das Holz, ist dasjenige Gewebe, welches Wasser und Mineralstoffe im Baum führt. Damit erfüllt es eine der wichtigsten physiologischen Funktionen für den Baum. Außerdem bestimmt das Gewebe des Sekundärxylems in erster Linie die Verwendbarkeit des Baumes bzw. des Holzes zu wirtschaftlichen Zwecken. Die Untersuchung der Entwicklung des Sekundärxylems zeigte, daß diese Entwicklung abgestuft vor sich geht. Die Xylem-Mutterzellen, unmittelbare Abkömmlinge der Kambium Initialen, zeigten sich zuerst als kleine Zellen mit dünnen Zellwänden. Dann erweiterten sie sich in radialer Richtung, blieben aber immer noch dünn in ihren Zellwänden. Als diese Zellen etwa den Durchmesser von reifen Tracheiden erreicht hatten, begann die Auflagerung der Sekundärschicht. Dieser Vorgang setzte sich fort bis sich dicke, feste Zellwände gebildet hatten. Diese dicken, steifen Zellwände bestimmen weitgehend die physikalisch-mechanischen Eigenschaften der betreffenden Holzart. Die vorliegenden Untersuchungen zeigen, daß die physikalischen Eigenschaften der Tracheiden je nach der Entwicklungsstufe schwanken können.
This report is based on portions of work in fulfillment of the requirements for the Ph.D. degree in Botany at the University of Wisconsin.
Maintained at Madison, Wisconsin, 53705, U. S. A., in cooperation with the University of Wisconsin. 相似文献
3.
Lidija Murmanis 《Wood Science and Technology》1975,9(1):3-14
Summary Tyloses form in red oak (Quercus rubra L.) sapwood in a period of hours if the wood is cut during the active growth season and stored in green condition in the laboratory. If the wood is cut during dormancy and stored in green condition, tyloses form in a period of months. Electron microscopic examination reveals that the wall of a tylosis forms from a promonths. Electron microscopic examination reveals that the wall of a tylosis forms from a protective layer that develops inside the secondary wall of the ray cell in the vessel-ray pit-pair. Protective layers are also present in fiber-parenchyma pit-pairs. Protective layers may exhibit variable thicknesses, with light and dark layers alternating. A young tylosis wall consists of two layers: An electron-dense outer layer and an electron-transparent inner layer. Tyloses walls may attach to each other and form multilamellate tyloses. Sometimes the individual layers of tyloses walls appear lamellated. Because of the type of formation and structure, the tylosis wall in red oak apparently is a primary wall rather than a secondary. Tyloses walls have simple pits. The findings of this study enable felled hardwoods with potential for forming tyloses to be used without the destructive influence of tyloses. 相似文献
4.
Summary Vesicular membrane-bound bodies that participate in forming the cell wall of differentiating xylem cells in white pine appeared on electron microscopical examination to originate from the Golgi apparatus. Golgi bodies released vesicles that contained dark material, fibrillar material, or no contents. The vesicles were seen at different stages on their path to the cell wall; their contents came in contact with the wall by fusion of vesicular membranes with the plasmalemma. Individual filaments of fibrillar material within the vesicles were 60 to 80 Å in diameter; structurally they resembled the fibrillar component of the existing wall and became intertwined with the wall. The authors assume the dark material in the Golgi-derived vesicles represents the hemicellulosic and the pectic components of the wall, and the fibrillar material, the cellulosic.Maintained in cooperation with the University of Wisconsin. 相似文献
5.
Comparison of mouse and rabbit model for the assessment of strong PGM-containing oil-based adjuvants
Habjanec L Halassy B Vdović V Balija ML Tomasić J 《Veterinary immunology and immunopathology》2008,121(3-4):232-240
Peptidoglycan monomer (PGM) is an adjuvant active molecule with potential for use in human and veterinary vaccine. PGM's action is short-lived in mammals hence its effects might be limited. Novel PGM-containing oil-based formulations have been developed recently by incorporation of PGM into Montanide ISA720 and ISA206 adjuvants with the aim to prolong and improve immunostimulating activities of PGM. In the present work we studied the efficacy of such novel adjuvant formulations using two different antigens, ovalbumin and snake venom, respectively. Novel formulations were also tested in two experimental models, mice and rabbits. In rabbits the incorporation of PGM into oil-based adjuvants led to overall improvement of antigen-specific IgG response. However, in the mouse model, under experimental conditions used, it was not possible to distinguish differences in antigen-specific IgG response among several strong oil-based adjuvant formulations. 相似文献
6.
Ternjej Ivančica Stanković Igor Mihaljević Zlatko Furač Lidija Želježić Davor Kopjar Nevenka 《Water, air, and soil pollution》2009,204(1-4):299-314
Water, Air, & Soil Pollution - In this pilot study, we evaluated the usefulness of the alkaline comet assay as a biomonitoring tool at the level of plankton communities affected by varying... 相似文献
7.
Immune development in jejunal mucosa after colonization with selected commensal gut bacteria: a study in germ-free pigs 总被引：1，自引：0，他引：1
Haverson K Rehakova Z Sinkora J Sver L Bailey M 《Veterinary immunology and immunopathology》2007,119(3-4):243-253
The immunological structure of the porcine jejunal lamina propria in germ-free piglets was compared with that of their counterparts associated with two strains of commensal Escherichia coli, A0 34/86 serotype O83:K24:H31 and the O86 E. coli strain, up to 20 days post-colonization. In the antigen-presenting compartment, both dendritic cells (DC) and cells expressing CD163, probably macrophages were investigated. In addition we also assessed the number of CD2+/CD3+ (T) cells. In contrast to some previous reports, we show a total lack of both DC and T cells for germ-free animals in the diffuse lymphoid tissue of villi and crypts of the jejunum. Association with either strain of commensal E. coli had a profound effect on the immune structure and resulted in extensive recruitment of DC to the lamina propria and of T cells to epithelium and lamina propria. The data suggest that the earliest immigrant cells were monocytes, which soon acquired the phenotype of mucosal DC. T cells migrated in at a slightly slower rate. Nevertheless, the response could be extremely rapid: within 3 days of colonization with O83, the magnitude of this response was comparable to that observed 20 days post-colonization. 相似文献
8.
Natalija Topic Popovic Lidija Kozacinski Ivancica Strunjak‐Perovic Rozelindra Coz‐Rakovac Margita Jadan Zeljka Cvrtila‐Fleck Josip Barisic 《Aquaculture Research》2012,43(5):722-729
The composition of tail muscle fatty acids from wild and cultured bluefin tuna reared on a diet based on herring and sardine, along with the plasma lipid profile of the farmed individuals, was determined. The total lipid content of farmed bluefin in this study was 0.922 g/100 g or 3.49 g of saturated fatty acids (SAFA), 4.48 g of monounsaturated fatty acids (MUFA), 2.58 g polyunsaturated fatty acids (PUFA) n‐3 and 0.37 g of PUFA n‐6 fatty acids; for wild specimens, it was 0.920 g/100 g, or 2.85 g of SAFA, 4.82 g of MUFA, 2.78 g PUFA n‐3 and 0.27 g of PUFA n‐6 fatty acids. The major fatty acids in this study were 16:0; 16:1, n‐7; 18:1, n‐9 and DHA 22:6, n‐3 acids. The sum of these major components accounted for more than 57% and 80% of the total fatty acids in all the samples of farmed and wild tuna respectively. No significant differences in the proximate composition were demonstrated between farmed and wild samples, except for the energy value, in favour of the farmed tuna. Statistically, glucose tends to increase together with cholesterol (CHOL) and plasma triglyceride, as for these pairs, it showed positive correlation coefficients and P>0.05. Some measured tuna metabolites demonstrated strong mutual correlations, especially GLU, CHOL and TRIG, which are crucial factors in the lipid profile of animals. 相似文献
9.
Terzić S Jemersić L Lojkić M Sver L Valpotić I Orsolić N Humski A Cvetnić Z 《Acta veterinaria Hungarica》2004,52(2):151-161
Total white blood cell (WBC) counts and percentages of CD4a+, CD8a+, CD5a+, CD45RA+, CD45RC+, wCD21+ and SWC3a+ cells in the peripheral blood of pigs were analysed in this study. Blood samples were collected before and on days 4, 10, 21 and 28 after vaccination. Group 1 pigs were vaccinated with a subunit E2 vaccine (gp E2 32 microg/dose), and Group 2 received a subunit vaccine combined with an attenuated ORF virus strain D1701 10(6.45) TCID50/dose. Control pigs received a placebo. The total WBC count and percentage of particular cell types were within the normal range in vaccinated and control pigs. Although the mechanism of attenuated ORF virus activity is not clear, changes were observed in CD4a+, CD5a+, CD8a+, CD45RA+ and CD45RC+ cells in pigs that received the combination of a subunit vaccine and ORF virus. However, the percentage of wCD21+ and SWC3a+ did not differ significantly from that recorded in pigs given only the subunit vaccine. At days 4 and 10 the number of pigs positive to E2 antibodies was higher in the group that received the subunit vaccine and ORF virus than in pigs vaccinated with the subunit vaccine only. A higher percentage of memory cells (CD45RC+) as well as Th and Tc lymphocytes in pigs that received the ORF virus and the subunit vaccine could be ascribed to a nonspecific influence of the ORF virus on the development (through cognate interactions between T and B cells) and the duration (presumed according to the finding of the clonal expression of memory cells) of humoral immunity (assessed by a higher number of seropositive pigs in this group). This seems likely since the proportion of these cells was found to be lower in the pigs that received E2 vaccine only. 相似文献
10.
Many alpine gravel-bed rivers have been altered in the past due to human interventions. A typical transboundary alpine river in Central Europe flowing over Austria, Slovenia, Croatia and Hungary is the Mura River (length: 465 km, catchment area: 14,304 km2). The main problem of the river before leaving Austria is bed degradation (average 0.5 m from 1970 to 2000) as a combined consequence of river regulation works and the reduced sediment supply from the upstream reaches due to the construction of hydro power plants. River restoration measures for the river reach on the border between Austria and Slovenia (SLO–A Mura reach) were proposed in 2000 to support both ecological and flood protection purposes that apply the concept “of self-restoration”. In order to apply similar process-oriented restoration strategies in the Mura River downstream in Slovenia, we consider the potentials for self-forming river processes. We have analysed the sediment granulometry and morphology of the Mura River in Slovenia, and discussed morphodynamic processes to detect potential for the Mura River recovery into a more diverse morphological structure. The cross section area increased by 8% between 1979 and 2005 on average, mainly due to riverbed degradation. On average, the thalweg of the Mura riverbed in Slovenia had degraded by 0.28 m in the 1979–2007 period, with the highest degradation of 2.28 m in one cross section and some cross sections being stable. The high river degradation trend from the SLO–A Mura reach is slowly shifting to the downstream direction into the Mura River in Slovenia. Nevertheless, the clear downstream coarsening of river sediments turns into the normal trend of sediment fining in the Mura River reach in Slovenia. The “self-restoration” potential in the Mura River reach in Slovenia is larger than on the SLO–A Mura reach due to still active morphological fluvial processes. These processes can be enhanced by the inflow of fresh coarse sediments from the SLO–A Mura reach, where active measures for re-establishing sediment transport are under way. In the long term, this will not work as proposed, if no sediment inflow is re-established from the Mura headwaters in Austria. 相似文献