File:The Biological bulletin (20191696720).jpg

Title: The Biological bulletin
Identifier: biologicalbullet1989mari (find matches)
Year: [1] (s)
Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983
Subjects: Biology; Zoology; Biology; Marine Biology
Publisher: Woods Hole, Mass. : Marine Biological Laboratory
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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76 R. I. WOODRUFF
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Figure 4. Photographs taken from the video screen. A, B, and C show an injection of Lucifer yellow into a nurse cell, followed by a 1-h incubation. The negative lluorochrome migrates via the intercellular bridge into the oocyte, becoming more concentrated there. The uneven appearance of the oocyte fluores- cence in C is an artifact of the recording. D. E, and F show that, when injected into an oocyte and incubated, in this case for 48 min, no detectable levels of dye are seen in the nurse cell. thium salt (Stewart, 1978) and thus in solution would have two negative charges. From the Nernst equation we would expect for a molecule with a ~2 charge that: Volt- age = 29mV.log (C,/C:). Thus a potential difference of 5-mV should bring about a 1.5-fold difference in the equilibrium concentrations, while an 8-mV potential difference would bring about a two-fold difference in the equilibrium concentrations. Given the unknown vari- ables such as the opacity of the different cells, the esti- than two-fold difference seems to fit the ex- peci Tat no further change was observed after against bulk flow of materials from nurs. e being a major factor in the distributio In 1 nl iicles had not yet reached equilibrium co ected for the average measured 5-n> >. Presumably this was due to the elec icused at the oocyte- nurse cell bridges. 110n to the diffu- sion gradient, and i! establishment of the equilibrium cono... t (hey were not yet achieved during the u ,n That ATP sup- pression by treatment with azide allowed a detectable spread of the fluorochrome from oocyte to nurse cells confirms that the observed asymmetry of equilibrium concentrations is dependent on metabolic energy. Varying values have appeared in the literature con- cerning the magnitude of the steady-state potentials in Drosophilu oocytes. Bohrmann el al. (1986) reported that oocytes incubated in Robb's medium (aKo 40 mA/) had a potential of-21 mV, and Woodruffs al. (1988) reported a —23.9 mV average for oocytes incubated in that same medium. In a medium with lower (8.6 mA/) aKo, O'Donnell (1988) reported a steady-state potential for Drosophila of -40 mV, while in a similar medium Miyazaki and Hagawara (1976) reported an average po- tential of-65 mV for unfertilized eggs. Sun and Wyman (1987) reported development of the medium used in the present study, and found an average potential for 27 stage-10 oocytes of-85.2 mV. The -60 mV average for the 81 stage-10 oocytes in the present study is below the average value found by Sun and Wyman, although some values as high as -85 mV were encountered. The saline solutions employed in these studies span

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