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1.
We have isolated 18 polymorphic microsatellite loci for Cophixalus ornatus from genomic libraries enriched for (AAAG)n, (AACC)n and (AAGG)n repetitive elements. The number of alleles ranges from five to 22 per locus with the observed heterozygosity ranging from 0.10 to 0.92. These markers will be useful for the analysis of population structure in C. ornatus and testing alternative models of speciation. 相似文献
2.
The recolonization of the Krakatau islands by termites (Isoptera), and their biogeographical origins 总被引:1,自引:0,他引:1
F.J. GATHORNE-HARDY D. T.JONES N. A. MAWDSLEY 《Biological journal of the Linnean Society. Linnean Society of London》2000,71(2):251-267
The termite assemblages of the Krakatau islands and five sites in Sumatra and Java were investigated, using a standardized transect sampling method. Five species were found on the Krakatau islands that have not been collected there before. The total number of termites recorded on the islands since the 1883 volcanic eruption is now twelve species, all of which are wood feeders. No termites nesting in or feeding on the soil were found on the Krakataus, suggesting that rafting in wood is the primary method by which the termites recolonized the islands. 相似文献
3.
4.
Rolf Dierichs 《Cell and tissue research》1973,137(4):553-561
Zusammenfassung Das Alveolarepithel der Froschlunge weist nur einen einzigen Zelltyp auf. Die Zellkörper sitzen in den Nischen zwischen den Kapillaren, die sie mit Zytoplasmaausläufern überdecken. Die Epithelzellen enthalten große Zytosomen mit osmiophilen Lamellen mit einer Periode von 40–42 Å. Sie sind den Typ II-Pneumozyten der Säugerlunge vergleichbar.Das Alveolarepithel der Froschlunge ist mit einer Grenzschicht bedeckt, die in Abhängigkeit von der Fixierung eine 40–42 Å-Periode aufweist oder aus einer oder mehreren Doppelmembranen zusammengesetzt ist. Gittermuster und Myelinfiguren sind vorhanden. Das bedeutet, daß Surfactant in der Froschlunge in gleicher Weise wie in der Säugerlunge dargestellt werden kann.
Electron microscopic studies on the lung of the frogI. Demonstration of the alveolar lining layer (surfactant)
Summary The alveolar epithelium of the frog exhibits only one type of cells. The cell-bodies are situated in the spaces among the capillaries, which they cover with cytoplasmic extensions. The epithelial cells contain large bodies (cytosomes) with osmiophilic lamellae having a period of 40–42 Å. The alveolar cells are considered to be similar to the type II-pneumocytes of mammalian lungs.The alveolar epithelium of the lung of the frog is covered with a lining layer, which depending on the method of fixation consists of periods of 40–42 Å or of one or more double membranes. Lattice formations and myelin figures are seen. This means that the surfactant in the lung of the frog can be demonstrated in the same way as in mammalian lungs.相似文献
5.
F Gracia-Navarro J A Gonzalez-Reyes F Guerrero-Callejas G Garcia-Herdugo 《Tissue & cell》1983,15(5):729-736
Stellate cells in the pars distalis of adult Rana ridibunda were observed electron microscopically under normal and experimental conditions (TRH injection). The stellate cells have lengthy processes extending into the intercellular spaces between the secretory cells and scanty cytoplasm surrounding the nucleus. Occasional desmosomes link stellate cells to adjacent secretory cells. In the pars distalis of animals injected with thyrotropic-releasing hormone (TRH), the stellate cells form large cavities (2-6 mum) filled with heterogeneous material. Their cytoplasm contains well-developed Golgi complexes and some lysosomes; these are the principal morphological alterations as compared to those observed in control animals. It is suggested that stellate cells could play an active role in addition to providing a structural framework for the pars distalis. 相似文献
6.
Toe pad morphology and mechanisms of sticking in frogs 总被引:4,自引:0,他引:4
SHARON B. EMERSON DIANA DIEHL 《Biological journal of the Linnean Society. Linnean Society of London》1980,13(3):199-216
Sticking ability in frogs was measured on a series of different substrates. Analysis of performance suggests that frogs use two sticking mechanisms: interlocking on rough surfaces and capillarity on smooth surfaces. There is a correlation between morphological specializations of the toe pad and sticking ability, but these morphological features are not unique to arboreal species. Terrestrial species that use leaves as resting sites during times of inactivity have many of the same morphological specializations and stick as well as the strictly arboreal species. 相似文献
7.
Biosynthesis and Genetic Engineering of Lignin 总被引:1,自引:0,他引:1
Lignin, a complex heteropolymer of cinnamyl alcohols, is, second to cellulose, the most abundant biopolymer on Earth. Lignification has played a determining role in the adaptation of plants to terrestrial life. As all extracellular polymers, lignin confers rheological properties to plant tissues and participates probably in many other functions in cell and tissue physiology orin cell-to-cell communication. Economically, lignin is very important because it determines wood quality and it affects the pulp and paper-making processes as well as the digestibility of forage crops. For all these reasons the lignin biosynthesis pathway has been the subject of many studies. At present, most genes encoding the enzymes involved in the biosynthesis of lignin have been cloned and characterized. Various recent studies report on the alteration of the expression of these genes by genetic engineering, yielding plants with modified lignin. In addition, several mutants have been analyzed with changes in lignin content or lignin composition resulting in altered properties. Thanks to these studies, progress in the knowledge of the lignin biosynthesis pathway has been obtained. It is now clear that the pathway is more complex than initially thought and there is evidence for alternative pathways. A fine manipulation of the lignin content and/or composition in plants is now achievable and could have important economical and environmental benefits. 相似文献
8.
Gerald Ozanne 《Aerobiologia》1990,6(1):8-10
Summary Under the ?Bois plus? scheme, the CTBA is currently developing a third party certification, based on the Scrivener law, with the aim of defending
the consumers' interests. At this early stage, wood preservatives and treated wood are checked for the efficacy of treatments
in order to ensure the stability and security of works in buildings and civil engineering. According to the different classes
of risks in service, ?Bois plus? provides the most adeguate level of protection. In the close future, the industry is planning to incorporate, with the help
of the CTBA and experts, health criteria within the frame of the ?Bois plus? certification scheme. The means could beSafety indexes, which are objectives of quality for professionals.Safety indexes are concentrations of substances in wood which can be taken as safe for humans and the general environment, while still toxic
for the wood pests.
This attractive experience aims to make with the brandname ?Bois plus? a synonym of efficacy and safety. This approach meets the essential requirements 1, 3, 4 of the 89/106 EEC directive: mechanical
resistance and stability/hygiene, health and environment/safety in use. 相似文献
9.
The simultaneous action of shear deformation and high pressure (SDHP) creates changes in the structure of wood and its main
components (cellulose, hemicelluloses, lignin). The formation of water and alkali soluble polysaccharides under SDHP action,
proceeds in seconds in the solid state, without the use of any reagents and solvents. Therefore, SDHP seems to be a technologically
safe method and friendly to the environment. The amorphization of cellulose crystallites and depolymerization of cellulose
chains were observed under a wide range of pressures (1–6 GPa), both for cellulose samples and the cellulose part of wood.
Similar depolymerization occurs in the hemicellulose part of wood. The decomposition of polysaccharides under SDHP causes
the formation of the water soluble part, whose content increases with pressure and the applied shear deformation. A maximum
solubility of 40% and 55% was registered at 6 GPa following treatment of cellulose and birch wood samples. A higher output
in the case of wood can be explained by a specific role of lignin under SDHP, which acts as a ‘grinding stone’ during cellulose
and hemicelluloses destruction. As shown by high-performance size exclusion chromatography, the water soluble fraction obtained
from cellulose contained glucose (2.6%), cellobiose (9.6%), cellotriose (16.6%) and other higher water soluble oligomers (71%).
Almost complete dissolution (98%) of the treated cellulose sample can be achieved by extraction with 10% NaOH solution. The
SDHP treated birch wood was subjected to submerged fermentation (with Trichoderma viride), and a 13% output of proteins was
obtained. In this case, the water soluble part played the role of the so called ‘start sugars’. Abbreviations: ASF, alkali
soluble fraction; DP, degree of polymerization; EC, energy consumption; HP, high pressure; LMWS, low molecular weight sugars;
MC, moisture content; MCC, microcrystalline cellulose; SD, shear deformation, SDHP, shear deformation under high pressure;
SS, shear strength; WSF, water soluble fraction
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
10.
Oviduct histochemistry and site of synthesis of a 29.7 kDa jelly coat glycoprotein in the anuran Lepidobatrachus laevis 总被引:2,自引:2,他引:0
The oviduct of the anuran Lepidobatrachus laevis contains three morphological regions, each of which contains a histochemically distinct luminal mucosa. In the pars recta, the most anterior portion of the oviduct, there are periodic acid-Schiff base (PAS)-positive simple glands and epithelia. In the pars convoluta, there are alcian blue-positive, combined alcian blue- and PAS-positive and PAS-positive gland types. The most posterior region, the pars uterina, contains alcian blue-positive and alcian blue-negative epithelial cells. Previous work has shown that solubilized egg jelly contains a major 29.7 kDa glycoprotein subunit that was detected in oviduct tissue extracts from the pars convoluta in the present study. Rabbit antisera to the 29.7 kDa egg jelly glycoprotein of L. laevis reacted with the major pars convoluta glycoprotein and there were no immunoreactive components in the pars uterina. The slight immunoreactivity detected at 29.0–37.0 kDa in pars recta extracts is not believed to be the jelly molecule, based on low immunoreactivity and subunit molecular weight measurements. We conclude that the synthesis of the 29.7 kDa egg jelly glycoprotein is restricted to the pars convoluta region of the oviduct. 相似文献