ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • Articles  (29)
Collection
Journal
  • 1
    ISSN: 1432-1432
    Keywords: Lymphocytes ; B cells ; T cells ; Antigen P1 ; Topoisomerase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During the differentiation of the clonally distributed lymphocytes of mouse and man into mature resting B and T cells, their DNA becomes tightly packed into dense heterochromatin masses and exhibits very little transcriptional activity; it also becomes extensively nicked, containing some 3000–4000 single-strand breaks per diploid genome. The nuclear matrix is sparse and poorly organized and there are but trace amounts of the matrix-linked enzyme DNA topoisomerase II; the nucleus of these small cells is surrounded by a thin rim of cytoplasm. The resting cell can thus be considered (by analogy to a sperm cell) as a vector for transporting tightly packed and relatively inert genetic information to all parts of the body. When the lymphocyte is stimulated to enter a proliferative cycle by binding of appropriately presented antigen or mitogen to relevant membrane receptors, the cell enlarges, due to increased synthesis of protein; the dense heterochromatin is pulled out into very small clumps, as a result of an enormous growth in size as well as complexity of the nuclear matrix, and a great increase in transcriptional activity occurs. We have identified four nuclear matrix antigens that are very widely conserved in the evolution of eucaryotes and that occupy distinctive domains in interphase nuclei. Of particular interest is antigen P1, detected in organisms ranging from algae to mammals. By virtue of its location at the interface between nuclear envelope and chromatin, we propose that it plays a major and evolutionarily conserved role in chromatin organization and orientation in all eucaryotic cell types. Prior to these events, the DNA strand breaks are rejoined by a mechanism dependent on poly(ADP ribose) synthetase; rejoining of the breaks is required in order for the cells to enter the S phase of the cell cycle. Under certain experimental conditions, the induction of DNA topoisomerase II is clearly seen to precede DNA replication; topoisomerase II may be involved in some of the nuclear changes of blastogenesis. The evidence suggests that induction of single-strand breaks in DNA may be a general feature in the evolution of differentiated somatic cells. The selective advantage of the endogenously produced DNA strand breaks may be to provide an additional mechanism that prevents the differentiated cell from replicating its genome in the absence of an appropriate proliferative signal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology 27 (1976), S. 71-94 
    ISSN: 0066-4294
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 34 (1998), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Forest land managers are concerned about the effects of logging on soil erosion, streamflow, and water quality and are promoting the use of Best Management Practices (BMPs) to control impacts. To compare the effects of BMP implementation on streamwater quality, two of three small watersheds in Kentucky were harvested in 1983 and 1984, one with BMPs, the other without BMPs. There was no effect of clearcutting on stream temperatures. Streamflow increased by 17.8 cm (123 percent) on the BMP watershed during the first 17 months after cutting and by 20.6 cm (138 percent) on the Non-BMP watershed. Water yields remained significantly elevated compared to the uncut watershed 8 years after harvesting. Suspended sediment flux was 14 and 30 times higher on the BMP and Non-BMP Watersheds, respectively, than on the uncut watershed during treatment, and 4 and 6.5 times higher in the 17 months after treatment was complete. Clearcutting resulted in increased concentrations of nitrate, and other nutrients compared to the uncut watershed, and concentrations were highest on the non-BMP watershed. Recovery of biotic control over nutrient losses occurred within three years of clearcutting. The streamside buffer strip was effective in reducing the impact of clearcutting on water yield and sediment flux.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: OMEGA, a 60-beam, 351 nm, Nd:glass laser with an on-target energy capability of more than 40 kJ, is a flexible facility that can be used for both direct- and indirect-drive targets and is designed to ultimately achieve irradiation uniformity of 1% on direct-drive capsules with shaped laser pulses (dynamic range (approximately-greater-than)400:1). The OMEGA program for the next five years includes plasma physics experiments to investigate laser–matter interaction physics at temperatures, densities, and scale lengths approaching those of direct-drive capsules designed for the 1.8 MJ National Ignition Facility (NIF); experiments to characterize and mitigate the deleterious effects of hydrodynamic instabilities; and implosion experiments with capsules that are hydrodynamically equivalent to high-gain, direct-drive capsules. Details are presented of the OMEGA direct-drive experimental program and initial data from direct-drive implosion experiments that have achieved the highest thermonuclear yield (1014 DT neutrons) and yield efficiency (1% of scientific breakeven) ever attained in laser-fusion experiments. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 432-449 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental data and hydrodynamic simulation results are presented for long-scale-length plasmas produced by the multibeam OMEGA fusion laser, with (approximately-less-than)1.5 kJ on target at wavelength 351 nm. The appropriately time-delayed beams from this system allow the production of millimeter-sized plasmas with (approximately-greater-than)1 keV electron temperatures maintained over extended periods of time ((approximately-greater-than)1 nsec). The two-dimensional plasma expansion and the temporal evolution of the electron temperature and density are found to be in very good agreement with simulations. The plasma thus produced forms an excellent tool for investigating laser–plasma interaction processes under conditions relevant to future laser-fusion reactor targets.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2405-2407 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the temporal and the frequency response of metal-semiconductor-metal ultraviolet photodetectors fabricated on single-crystal GaN. The best devices show a fast 10%–90% rise time of ∼23 ps implying a bandwidth of 〉15 GHz. These time domain data have been corroborated by direct measurement of the power spectral content. From this a cutoff frequency, f3 dB, of ∼16 GHz has been obtained. Analysis in terms of reverse bias and geometric scaling indicates that the photodetectors are transit-time limited. Modeling of the temporal behavior indicates that a slow component in the time and frequency response data is a consequence of the hole drift velocity. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1573-6849
    Keywords: cell cycle ; HeLa ; immunolocalization ; lymphocytes ; Topo II isotypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have monitored the organization of DNA topoisomerase II (Topo II) in relation to chromatin disaggregation during mitogen stimulation of lymphocytes and to the mitotic chromosome condensation cycle by immunofluorescence microscopy with isozyme-specific antibodies. Labelling for both Topo IIα and Topo IIβ was diffusely nucleoplasmic and non-nucleolar in resting lymphocytes and the pattern changed little during stimulation. Topo IIα labelling intensity increased in parallel with the extent of cell stimulation, but a fraction of fully stimulated cells was labelled very brightly. Topo IIβ labelling intensity was also greater in stimulated cells, but all partially and fully stimulated cells were labelled at the same, higher, intensity. In addition, anti-Topo IIβ detected a few small spots within nucleoli of stimulated cells that coincided with regions containing fibrillarin. In lymphocytes and HeLa, chromosome association of Topo IIα began in prophase and lasted throughout mitosis. In contrast, Topo IIβ stayed nucleoplasmic in prophase, was diffusely cytoplasmic during mitosis, and was first detected post-mitotically in nuclel with decondensing chromosomes and a reformed nuclear envelope. The results are consistent with a role for Topo IIα, but not for Topo IIβ, in mitotic chromosome condensation, and indicate that the isotypes may play independent roles in the reorganization of chromatin structure during lymphocyte mitogenic activation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 361-374 
    ISSN: 0886-1544
    Keywords: microtubular cytoskeleton ; Dinoflagellates ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoskeletal microtubule system has been studied in six species of unarmoured Dinoflagellates using immunofluorescence and electron microscopy. Several structures have been detected and described: (1) a subpellicular layer of microtubules, constituting the microtubular cytoskeleton, running singly or in bundles from the anterior part of the cell to the posterior; (2) a feeding apparatus, containing a ribbon of microtubules, which corresponds to a small peduncle in some species and is simply represented by a cytostome in some other species; and (3) the longitudinal flagellum that runs in a long intracytoplasmic pocket before becoming free at the extremity of the sulcus. A thorough study of the organization of the microtubular structures in a wide spectrum of Dinoflagellates is a prerequisite for understanding the evolutionary history of the group.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 325-336 
    ISSN: 0886-1544
    Keywords: fibrillar cytoskeleton ; myonemes ; nonactin filaments (NAF) ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An important cortical fibrillar cytoskeleton is described in some unarmoured dinoflagellates (Gymnodinium, Gyrodinium). The filaments which constitute this cortical layer are 2-3 nm in diameter, tightly packed, entangled, and resistant to denaturing agents. Issuing from them are other bundles of filaments which appear to be involved in the contraction of the cell, and for this reason they are termed “myonemal.”In highly contractile unarmoured dinoflagellates (Leptophyllus) the cytoskeleton is also made of 2-3-nm filaments, but they are regularly arrayed and more directly involved in contraction and thus correspond also to myonemal structures.Both structures - cytoskeletal and myonemal - are made of 2-3-nm filaments.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 50 (1976), S. 9-14 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Verbindungen der Strukturformeln [π-C5H5M(CO)nX] (M = Fe, n = 2; M = Mo, n = 3; X = CH3, CH2C6H5, CH2Si(CH3)3, CH2OCH3, Sn(C6H5)3, SnCl3, HgCl, I), [Mn(CO)5CH3], und [(π-CH3C5H4)Mn(CO)3] wurden als Katalysatoren für die Härtung von Epoxidharzen unter verschiedenen Bedingungen geprüft. Es wurde gefunden, daß die Verbindungen [π-C5H5Fe(CO)2R] (R = CH3, CH2C6H5) und [π-C5H5Mo(CO)3CH3] wirksame lichtempfindliche Beschleuniger für die Anhydridhärtung von Expoxidharzen sind. Der Aktivierungsmechanismus wird diskutiert.
    Notes: Compounds of the types [π-C5H5M(CO)nX] (M = Fe, n = 2; M = Mo, n = 3; X = CH3, CH2C6H5, CH2Si(CH3)3, CH2OCH3, Sn(C6H5)3, SnCl3, HgCl, I), [Mn(CO)5CH3], and [(π-CH3C5H4)Mn(CO)3] have been examined as catalysts for the cure of epoxy resins under various conditions. It was found that the compounds [π-C5H5Fe(CO)2R] (R = CH3, CH2C6H5) and [π-C5H5Mo(CO)3CH3] are active photosensitizing agents for the anhydride cure of certain epoxy resins. The mechanism of the process is discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...