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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The expression of glial fibrillary acidic protein (GFAP)-mRNA during mouse brain development and in astroglial primary cultures has been investigated by using two approaches: Northern-blot evaluation using a specific cDNA probe, and cell-free translation associated with immunoprecipitation. During brain maturation (4–56 days postnatal), the GFAP-mRNA underwent a biphasic evolution. An increase was observed between birth and day 15 (i.e., during the period of astroglial proliferation), which was followed by a decrease until day 56 (i.e., during astroglial cell differentiation). At older stages (300 days), an increase was observed, which might reflect gliosis. During astroglial in vitro development (7–32 days in culture), the GFAP-mRNA showed similar variations. An increase, observed during the period of astroglial proliferation (7–18 days), was followed by a decrease which occurred in parallel to marked changes in cell shape, cell process outgrowth, and the organization and accumulation of gliofilaments. During the same culture period (7–32 days), α-tubulin mRNA, which was used as an internal standard, did not vary significantly. These results show that the increase of the GFAP protein and of gliofilaments observed both in vivo and in vitro during astroglial differentiation cannot be ascribed to an accumulation of the GFAP-mRNA. It might be that more than one mechanism regulates the levels of free and polymerized GFAP and of its encoding mRNA.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Two τ cDNA probes of 1.6 and 0.3 kilobases (kb) have been used to study the expression of the τ mRNAs during mouse brain development and in highly homogeneous primary cultures of neurons and astrocytes. (1) Whatever the stage, a 6-kb mRNA was detected with the two probes. In the astrocytes a 6-kb mRNA hybridized clearly only with the 1.6-kb probe. (2) During brain development the abundance of τ mRNA increases from a late fetal stage (— 4 days) until birth, remains high until 6 days postnatal, and then markedly decreases to reach very low values in adulthood. Such a marked decrease in the abundance of τ mRNA parallels that of α-tubulin mRNA. These data suggest that: (1) depending on the stage of development and on the cell type (neurons or astrocytes) τ mRNAs of the same size encode several τ proteins differing in molecular weight: several τ proteins are expressed either during early stages of development (juvenile τ proteins of 48 kilodaltons) or in adulthood (mature τ proteins of 50–70 kilodaltons) or are specific of the astrocyte (83 kilodaltons). (2) The expression of the two major components of axonal microtubules, tubulin and τ proteins, seems to be developmentally coordinated.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 61 (1993), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The sequence of a high molecular weight (HMW) τ cDNA cloned from a neuroblastoma N115 library contains, in addition to the C-and N-terminal and middle regions present in the low molecular weight mouse brain τ proteins, a 711-bp nonhomologous domain (exon 4a) and a region of 198 bp corresponding to exon 6 of the τ gene. Protein immunoblot analysis, performed with antibodies specific either for a sequence present in the N-terminal region of all the τ variants or for exon 4a revealed several bands suggesting that more than one τ form is expressed in this cell line. Northern blot experiments performed with a number of cDNA probes spanning domains common and uncommon to low molecular weight and HMW τ allowed the identification of four τ transcripts differing in the size of their coding and noncoding regions. All these transcripts contain the sequence encoded by exon 6, but two of them lack exon 4a. As shown by RNase protection assays, the N-terminal region of these transcripts is also variable and contains either exon 1, or exons 1 and 2, or exons 1–3. Yet all these HMW τ forms contain four homologous repeats in their C-terminal domain both in the differentiated and nondifferentiated cells, i.e., have adult characteristics. In conclusion, the data reported in this article demonstrate that several HMW τ variants are expressed in neuroblastoma N115 cells and that the transition between immature to mature τ forms occurring during brain development is not required for neurite outgrowth during morphological differentiation of this cell line.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 61 (1993), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Both high and low molecular weight (HMW and LMW) T proteins are expressed in the immature and adult mouse spinal cord. Northern blot analysis, performed with probes complementary to domains common and uncommon to the LMW and HMW entities, suggested that HMW τ proteins found in the immature mouse spinal cord are not translated from the single transcript of 6 kb expressed at these stages, but are transported within this nervous structure by axons arising in the periphery. In contrast, another minor transcript of 8 kb was detected in the adult mouse spinal cord by a HMW τ specific probe, suggesting that a small fraction of the HMW τ forms present in adulthood are translated within mouse spinal cord neurons. LMW spinal cord T forms are encoded by mRNAs of 6 kb that contain three and four homologous repeats at immature and mature stages, respectively, whereas adult HMW entities contain four repeats. PCR analysis performed with mouse genomic DMA also showed that the nonhomologous region specific for HMW τ is a single exon. Southern blot and gene mapping showed that the same gene, located on the murine chromosome 11, encodes all the LMW and HMW τ variants. All these τ forms, therefore, are produced by an alternative splicing mechanism that is neuron-specific and developmentally regulated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 58 (1992), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Two abnormal entities of 69 and 130 kDa, immunologically related to the microtubule-associated τ proteins, are present in the hippocampus and the frontal cortex of the Alzheimer brain, which contain a large number of neurofibrillary tangles (NFTs), but are absent in the cerebellum, which does not contain these structures. Epitope mapping with antibodies spanning domains present in the N-terminal, middle, and C-terminal τ sequence demonstrated that the 69- and 130-kDa entities belong to the τ family. Both the 69- and the 130-kDa proteins were found in an insoluble form and were the major τ species present in purified NFTs. A procedure was devised that allowed us to prepare from Alzheimer hippocampi two NFT fractions differing in size (20 and 3 μm), both of which contained the τ entities of 130 and 69 kDa.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract Immunoblotting analysis was used to identify the microtubule-associated proteins (MAPs) present in cultures of mouse brain neurons. Polyclonal antibodies were raised against the two main adult brain MAPs, i.e., MAP2 (300 kDa) and τ (60–70 kDa). Whatever the stage of the culture, which was performed in a defined medium (3 or 6 days), the anti-MAP2 serum detected several high-molecular-weight components (including MAP2) and an entity with 62–65 kDa. Anti-τ revealed essentially a major peak of 48 kDa (young τ) but also slightly cross-reacted with the 62–65 kDa entity. During the culture period (0–6 days) the cells developed progressively a dense neuritic network; the concentration of the different MAPs increased in parallel but at different rates depending on the different species. The in crease in concentration of the high-molecular-weight components occurred before that of 48-kDa τ. This suggests that high-molecular-weight MAPs and 48-kDa τ might be involved respectively in the initiation and elongation of neu-rites. In contrast, and since the main developmental changes in τ composition seen in vivo did not occur during the time course of the culture, this transition might be related to later events of neuronal differentiation.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 53 (1989), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The expression of τ mRNA and of the corresponding encoded protein variants was studied during postnatal development in two brain regions differing in their timing of differentiation: the cerebral neocortex and the cerebellum, (a) The expression of r mRNA was different in the two regions. Maximal contents were found at early stages in the cerebral neocortex, with a 10-fold decrease at later stages. In the cerebellum, two peaks of τ mRNA were observed soon after birth and in adulthood, with minimal values at postnatal day 6. (b) The expression of total τ proteins was similar to that of their encoding mRNAs in the cerebral neocortex, i.e., high concentrations after birth and low contents at later stages. In contrast, two peaks of τ proteins were observed in the cerebellum: the first perinatally and the second with a maximum at postnatal day 15. (c) Both in the cerebral neocortex md especially in the cerebellum, increasing concentrationsof mature τ variants were expressed at late developmental stages, i.e., when total τ protein contents were decreased. In conclusion, the fluctuations in expression of τ and of its encoding mRNA seen in the cerebellum seem to reflect differences in the timing of differentiation of the various cell types, i.e., the macroneurons and the interneurons, present in this brain region. The adult τ variants appear in both the neocortex and the cerebellum only at late developmental stages, i.e., when most of the circuitry has been established, although these two regions markedly differ in their timing of differentiation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 1124-1133 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 4681-4688 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Brillouin spectra of liquid toluene have been measured between 288 and 358 K using a dynamic light scattering technique. The polarized spectra have been modeled according to Mountain's theory. The most relevant quantity of the theory, namely the relaxation time, has been used to check the validity of several molecular models proposed to interpret vibrational–translational energy exchanges observed in nonassociated liquids. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 35 (1980), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The development of in vitro microtubule assembly and of tubulin concentration have been studied during brain maturation in the mouse and the rat, two species which have postnatal brain development, and in one species which is mature at birth, the guinea pig. (a) The rate of tubulin assembly is very slow soon after birth in both the mouse and rat; it increases progressively with age until adulthood. In contrast, in the guinea pig this rate is maximal at birth and slower rates are seen only at foetal stages. (b) Postnatal changes in the lag period of assembly and in the minimal concentration of tubulin (Cc) required to obtain in vitro assembly are seen in the mouse and the rat; in contrast these parameters are constant at all postnatal stages in the guinea pig with longer lag periods and lower Cc values being seen only at foetal stages. (c) Maximal rates of assembly, minimal lag periods, and minimal Cc values are restored after addition of microtubule-associated proteins to foetal guinea pig or young mouse and rat preparations, suggesting that the difference in the kinetic parameters of assembly between these species depends on differences in the concentration or activity of these proteins. (d) Maximal tubulin concentrations are observed before birth in the guinea pig and approximately at day 10 in the rat and mouse. Lennon A. M. et al. Rat, mouse, and guinea pig brain development and microtubule assembly. J. Neurochem.35, 804–813 (1980).
    Type of Medium: Electronic Resource
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