ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

Hits per page

hits 1 - 3 | 3 hits

Sorting

Electronic Resource

Microtubule-dependent transport of secretory granules during stalk secretion in a peritrich ciliate (1982)

Suchard, Suzanne J. ; Goode, Dennis

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 2 (1982), S. 47-71

add to mindlist on the mindlist

Details

ISSN: 0886-1544

Keywords: microtubules ; transport ; secretion ; peritrich ciliate ; directional turnover ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: The role of microtubules in secretory granule translocation was studied during stalk secretion in the peritrich ciliate, Zoothamnium arbuscula. In each cell, the release of stalk-forming secretory materials is restricted to a specialized region of the cytoplasm, the scopula. Many of the membrane-bound secretory granules that dominate the scopular cytoplasm appear to be aligned along cortical microtubules that converge on the scopular surface. This arrangement is consistent with the hypothesis that microtubules transport granules relative to the sites of exocytosis. To establish the role of microtubules in stalk secretion, telotrochs were exposed to agents with different disruptive effects on microtubule function. Exocytosis itself is not prevented by these drugs, and granules positioned for secretion prior to treatment are released. Maytansine and isopropyl-n-phenyl carbamate (IPC) completely inhibit stalk elongation. In maytansine-treated cells, microtubules are absent from the scopular cytoplasm, and granules are absent from the scopular surface. Microtubules are present in IPC-treated cells, but the granules are misdirected to the cytoplasm lateral to the scopula where no secretory sites exist. Even though the rate of stalk secretion is decreased by deuterium oxide (D2O), a control length stalk is eventually produced. In D2O-treated cells microtubules are present and in their normal orientation. The inhibition of secretion when microtubules are absent (maytansine) or misdirected (IPC) and the retardation of secretion when microtubule turnover is reduced (D2O) supports a mechanism of granule transport based on the directional turnover of microtubule subunits.

Additional Material: 17 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970020105

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Incorporation and turnover of labeled exogenous tubulin in the mitotic spindles of Chaetopterus oocytes and HeLa cells (1986)

Goode, Dennis ; Sarma, Vidya

New York, NY : Wiley-Blackwell

Cell Motility and the Cytoskeleton 6 (1986), S. 114-121

add to mindlist on the mindlist

Details

ISSN: 0886-1544

Keywords: mitosis ; microtubules ; tubulin incorporation ; assembly polarity ; Chaetopterus ; HeLa cells ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: The incorporation of tubulin into mitotic spindles in situ was studied by incubating permeabilized mitotic cells in solutions containing [3H]GTP-labeled or dichlorotriazinylamino fluorescein (DTAF)-labeled tubulin. Metaphase HeLa cells or spindle-containing “minicells” from Chaetopterus oocytes were lysed in a microtubule-assembly buffer plus 0.5% Nonidet P-40, 1 mg/ml 120,000g supernatant mammalian brain tubulin, and [3H]GTP. After different periods of incubation, mitotic spindles were isolated in 2 M-glycerol-containing assembly buffer and separated from unbound counts by centrifugation through a 4 M-glycerol cushion; 3H counts per mg protein increase linearly for 8-12 min and then reach a plateau or steady state in both Chaetopterus oocytes and HeLa cells. Addition of 4 mM CaCl2 blocks or reverses incorporation. Little or no [3H]GTP is incorporated if exogenous tubulin or lysed cells are omitted from the assembly mixture.To measure the loss rate of [3H]GTP-tubulin from mitotic spindles, cells were incubated in tubulin plus [3H]GTP for 30 min, and a 20-fold excess of cold GTP (2 mM) was added. Samples were removed after incubation for different periods, and spindles were isolated as described above and counted for 3H content. [3H]GTP is lost from spindles at a rate of about 16%/min until a new steady state is reached in about 8 min. These results are consistent with an incorporation and turnover of [3H]GTP-tubulin in spindle microtubules of these lysed-cell models.The location of this newly incorporated tubulin in the spindle was investigated by incorporating fluorescent DTAF-tubulin into mitotic spindles of these lysed cell types. A short pulse (2-5 min) appears to label microtubules (MTs) near metaphase chromosomes and longer exposures label the entire spindle.The rates of incorporation and turnover that we see by [3H]GTP and fluorescent tubulin incorporation in situ are faster than those observed with brain MTs at steady state in vitro but are in the range of the rates of spindle fiber formation in prophase, and spindle MT reassembly after cooling.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/cm.970060208

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Momentum transfer across fluid-fluid interfaces in porous media: A network model (1993)

Goode, P. A. ; Ramakrishnan, T. S.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 39 (1993), S. 1124-1134

add to mindlist on the mindlist

Details

ISSN: 0001-1541

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology

Notes: Two-phase flow in porous media is described based on the extended form of Darcy's law, which ignores momentum transfer at fluid-fluid interfaces. Two forms of corrections to this simple description have been proposed in the literature: one on the relative permeability dependence on viscosity ratio; the other on the velocities assumed to be proportional to both phase pressure gradients and so introducing an additional saturation-dependent cross coefficient.In this article, to identify the correct form of transport equations, a simple cubic network model of 30 × 30 × 30 bonds is used. The cross section of the bonds is that of a four-cusp duct. The fluid interface in each duct is located by capillary equilibrium. The duct hydraulic conductances are then obtained as a function of viscosity ratio and phase volume fraction using a finite element calculation. These individual duct results are used in the network calculations for which a percolation algorithm is applied to simulate nonwetting phase displacing wetting phase, a process also known as initial drainage. Flow calculations show that both the nonwetting-phase relative permeability and the cross coefficient are strong functions of saturation and viscosity ratio. Also, the off-diagonal terms may contribute to a nonnegligible fraction of the flow. The proposed generalization of the Darcy equations is applicable to all problems involving multiphase flow in porous media. The current practices for relative permeability measurements and reservoir simulation may have to be reexamined in the context of the proposed transport equations.

Additional Material: 13 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/aic.690390705

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

hits 1 - 3 | 3 hits