Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Fluxes of elements in rain passing through forest canopies in south-eastern Australia (1987)
    Springer
    Biogeochemistry 4 (1987), S. 27-39 
    Details
    ISSN: 1573-515X
    Keywords: canopy interception ; elemental fluxes ; Eucalyptus ; leaching ; Pinus radiata ; precipitation chemistry ; throughfall ; stemflow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The elemental content of rainfall (bulk deposition), throughfall and stemflow was measured inPinus radiata D. Don andEucalyptus forests in Gippsland, Victoria. Accessions in rainfall (mg m−2 year−1) averaged: organic-C 551, NO3 −-N 96, NH4 +-N 62, total-N 303, K+ 382, Na+ 2250, Ca2+ 1170, and Mg2+ 678. The mean pH of rainfall was 5.9. Concentrations of all elements were greater in throughfall than in rainfall, and generally greater in stemflow than in throughfall. However, pH of pine throughfall was higher than that of rainfall, and pH of eucalypt throughfall was lower than that of rainfall. There was a net efflux of inorganic-N from pine crowns to rainfall, whilst in eucalypts there was generally net sorption of inorganic-N from rainfall. In both species organic-N was leached from the crowns and the net efflux of total-N from eucalypt crowns (50 mg m−2 year−1) averaged one-quarter of that in pines. Increases in the organic-C content of throughfall relative to rainfall in eucalypts were two to four times those in pines. Increases in the content of other elements in throughfall were comparable in pines and eucalypts and within the ranges K+ 615–1360, Na+ 480–-1840, Ca2+ 123–780 and Mg2+ 253–993 mg m−2 year−1. However, enrichment of Ca2+ may have been due to dust trapped in the canopies. Stemflow contributed significantly to the total amounts of elements reaching the forest floor in water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02187360
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    The origin of cytoplasmic inclusions from the nuclear envelope of mammalian oocytes (1968)
    Springer
    Cell & tissue research 93 (1968), S. 45-55 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oocytes in foetal and neonatal human, monkey and cow ovaries have been examined by electron microscopy. Dilatations of varying size and form are present between the two nuclear membranes in cells from the pre-leptotene stage to the early diplotene stage of meiosis. In the early part of this period the dilatations are limited in size and appear empty. At pachytene and early diplotene they are more complex and contain membrane-bound inclusions of two types: groups of small irregular profiles, or round to oval bodies which contain material at times resembling nuclear chromatin. The possible significance of these structures in relation to the early growth and differentiation of the cytoplasm of the oocyte is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325022
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    The fine structure of oogonia and oocytes in the rhesus monkey (Macaca mulatta) (1972)
    Springer
    Cell & tissue research 126 (1972), S. 53-74 
    Details
    ISSN: 1432-0878
    Keywords: Oogenesis ; Rhesus monkey ; Meiotic chromosomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovaries of foetal and neonatal rhesus monkeys have been examined with the electron microscope. The fine structure of the germ cells (oogonia; oocytes at the preleptotene, leptotene, zygotene, pachytene and diplotene stages of meiotic prophase) closely resembles that of corresponding human cells. Stages in spontaneous atresia are also described. Cytoplasmic organelles in oogonia are sparse and are grouped mainly at one pole of the nucleus, but become dispersed and more abundant as oogenesis proceeds. The nuclei of oogonia contain a random fibrillar matrix which becomes organized into threads at pre-leptotene. At leptotene these chromosomal threads each contain a dense axial “core”; during zygotene they become loosely paired in a “bouquet” arrangement and at pachytene the bivalents contain synaptinemal complexes. “Single” cores reappear at diplotene, surrounded by a complex fibrillar sheath organized into lateral projections and loops with associated granules: such chromosomes resemble those in human primordial oocytes although they are more diffuse. These findings support the view that at the diplotene stage mammalian oocytes contain chromosomes of the lampbrush type. Observations on the monkey are compared with those on other species, and the ways in which chromosomal organization may influence the radiosensitivity of oocytes is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306780
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Electron microscope studies of radiation-induced degeneration in oocytes of the sexually mature rhesus monkey (1972)
    Springer
    Cell & tissue research 133 (1972), S. 435-454 
    Details
    ISSN: 1432-0878
    Keywords: Oocytes ; Monkey ; Radiation damage ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study describes the effects of acute X-irradiation of the ovaries upon the structure of primordial follicles in mature rhesus monkeys. Doses of 1000 r to 12000 r, and post-irradiation intervals of 7 hours to 30 days were used. Oocytes in biopsies from irradiated ovaries were compared with those removed from the same ovaries prior to treatment or from contra-lateral controls. The results of the treatment were assessed using light and electron microscopy. The fine structural features of normal primordial oocytes are described, with particular reference to mitochondria and dense granular bodies. Some observations on spontaneous degenerative changes are included. Irradiated ovaries are classified into four arbitrary groups according to the severity of cellular damage visible in primordial follicles with the light microscope. Effects are more marked following higher doses and/or longer intervals; the most obvious changes are pyknosis of nuclei and accumulation of dense granules in the follicle cell cytoplasm. Early changes in oocytes are relatively difficult to detect, but lead to clumping of cytoplasmic and nuclear contents at more advanced stages of degeneration. Alterations in oocyte fine structure consist mainly in swelling and disruption of membrane-bound organelles, and condensation of nuclear and nucleolar chromatin. They thus resemble those occurring during spontaneous atresia, although the damage to follicle cells is evident much sooner after irradiation. These findings are compared with those made for species in which primordial follicles are known to be destroyed by much lower doses of X-rays than were used here. The contribution to the radiation-response made by the relative radiosensitivities of oocytes and follicle cells in different species is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307127
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...