Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Microtubules and their associated proteins play a prominent role in many physiological and morphological aspects of brain function. Abnormal deposition of the microtubule-associated proteins (MAPs), MAP2 and γ, is a prominent aspect of Alzheimer's disease. MAP2 and γ are heat-stable phosphoproteins subject to high rates of phosphorylation/dephosphorylation. The phosphorylation state of these proteins modulates their affinity for tubulin and thereby affects the structure of the neuronal cytoskeleton. The dinoflagellate toxin okadaic acid is a potent and specific inhibitor of protein phosphatases 1 and 2A. In cultured rat cortical neurons and a human neuroblastoma cell line (MSN), okadaic acid induces increased phosphorylation of MAP2 and γ concomitant with early changes in the neuronal cytoskeleton and ultimately leads to cell death. These results suggest that the diminished rate of MAP2 and γ dephosphorylation affects the stability of the neuronal cytoskeleton. The effect of okadaic acid was not restricted to neurons. Astrocytes stained with antibodies to glial fibrillary acidic protein (GFAP) showed increased GFAP staining and changes in astrocyte morphology from a flat shape to a stellate appearance with long processes.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The capacities ofHalobacterium cutirubrum and a moderate halophile NRC 41227 to survive and recover from treatment with N-methyl-N′-nitro-N-nitrosoguanidine have been compared.Halobacterium cutirubrum is resistant to this chemical and its mutation frequency is only slightly affected, whereas NRC 41227 is highly sensitive and its mutation frequency is markedly increased. The chemically treated extreme halophile fully regains viability during liquid holding, in notable contrast to its known failure to recover from the effects of ultraviolet irradiation.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Previous work from this and other laboratories has shown that many unrelated, nonmutagenic physical, chemical, or nutritional stresses increase the resistance ofEscherichia coli AB1157 to short-wavelength UV while reducing their UV-induced mutation frequency. The mechanism appears similar in all these cases, suggesting that induction of the same error-free DNA repair pathway is involved. We now show that a combination of two such stresses is no more effective than one alone, in agreement with this hypothesis.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Our previous studies have shown that heat shock and nutritional stress produce an increase in UV resistance and a decrease in UV-induced mutation frequency in DNA repairproficient strains ofEscherichia coli K12. The effect depends on nucleotide excision repair and requires protein synthesis. We now show that comparable changes occur after oxidation stress, exposure to ethanol, or osmotic shock, all in conditions that do not affect the natural mutation frequency. The results support the hypothesis that many unrelated, nonmutagenic treatments elicit a common protective response in these cells that involves induction of an error-free DNA excision repair system.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The thermal induction of resistance to UV inEscherichia coli JE1011 has now been shown to depend on an error-free DNA repair process. Heat shock causes a simultaneous reduction in the UV-induced frequency of mutation to prototrophy of two nutritional markers. In contrast, induction of SOS repair by thymine starvation causes the expected increase in mutation frequency upon UV irradiation. Thiamine deprivation produces an effect similar to heat shock, leading to increased UV resistance and a large decrease in the radiation-induced mutation frequency. Thus, two very different types of stress are able to induce error-free DNA repair in these cells.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Our previous studies have shown thatEscherichia coli JE1011 possesses an errorfree DNA repair system that is inducible by heat shock or thiamine deprivation. However, it appears to be lacking inE. coli B, which islon −. We now show that a similar, thermally inducible, error-free system is present inE. coli AB1157, although it requires more severe heat shock for its induction. Thelon mutant of this strain is similar toE. coli B and does not become more UV-resistant after heat shock, so this gene appears to play an essential role in the process. All three strains become more resistant to heat inactivation at 55°C following a 30°C→48°C heat shock; this confirms that the induced UV and thermal resistances must arise by different mechanisms.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0886-1544
    Keywords: microtubule-associated protein 2 ; neurons ; microtubule-associated proteins ; cytoskeleton ; dendrites ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Microtubule-associated protein 2 (MAP-2) is an abundant component of the cytoskeleton present in dendrites and cell bodies of neurons of the CNS. To examine the biological function of MAP-2, two MAP-2 antisense (AS) oligonucleotides complementary to the 5′ region of the rat MAP-2 cDNA were added to rat primary embryonic day 17-18 (E17-18) cultured cortical neurons 24 h after plating and neurite outgrowth and morphology studied. The treatment of primary cortical cultures with either of the two MAP-2 AS oligonucleotides resulted in decreased MAP-2 and reduction in the number of neuritic processes relative to the control or MAP-2 sense-treated cultures. By immunostaining and light microscopy the AS-treated neurons appeared smaller, more rounded, and less intensely stained for MAP-2 than the untreated or the MAP-2 sense-treated cultures. By electron microscopy disorganized microtubules and a reduction in the number of microtubules within neurites of the AS-treated cultures were observed. We conclude that MAP-2 continues to be required for microtubule spacing and stability within neurites once they have formed. © 1994 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1573-4919
    Keywords: perfused rat heart ; heart mitochondria ; adenosine incorporation ; ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The acid-insoluble product isolated from well-oxygenated Langendorff rat heart after perfusion with [14C]adenosine was purified by phenol extraction and subjected to specific phosphorolysis by pure polynucleotide phosphorylase. TLC analysis of the reaction mixture showed that ADP was the only radioactive product, proving that the original substance was a polyribonucleotide. Studies of the time course of labelling and of the distribution of the acid-insoluble product between the mitochondrial and nuclear fractions showed that both are labelled even after 1 min at 25 °C, but at short times and low temperature more radioactivity is found in the mitochondria. The kinetics of adenosine incorporation resemble those expected for the labelling of hnRNA and mRNA. Isolated, respiring mitochondria incorporate adenosine and adenine nucleotides into acid insoluble form by a process dependent on oxidative phosphorylation and the adenine nucleotide translocase that is specific for adenine derivatives. The results are discussed in terms of the hypothesis that the polyribonucleotide might be a storage form of adenine nucleotides: it is concluded that the bulk of the labelled product is unlikely to play a major role in energy metabolism.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1573-4935
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Perfusion of Langendorff rat hearts with [14C]adenosine yields an acid-insoluble, radioactive product whose concentration falls during ischaemia. The properties of the substance show that it is a polyribonucleotide. It is suggested that it may be mitochondrial poly A acting as a storage form of adenine nucleotides.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1573-4935
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Further studies on the acid-precipitable radioactive substance formed during perfusion of Langendorff rat hearts with [14C]adenosine have shown that very brief (30 s) ischaemia causes a sudden rise (20–35%) in its level in the tissue which is followed by the steady fall we have previously described. Analysis of the products of alkaline hydrolysis of this compound shows that at least 96% of the radioactivity appears in the form of a mixture of 2′- and 3′-AMP as would be expected for RNA while its relatively high resistance to dilute alkali suggests that it is poly A. Subcellular localization studies indicate that radioactivity enters all compartments of the cell, with maximum label in the nucleus. However, a significant proportion is present in the mitochondria and may be poly A acting as the mitochondrial storage form of adenine nucleotides whose existence we have proposed.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...