Biomedical subjects
A V Gokhale
Publications and source records attributed to A V Gokhale.
Selectivity to K+ and Na+ of protoplast fractions isolated from different regions of Aspergillus nidulans hyphae.
The selectivity to K+ and Na+ of protoplast samples representing cytoplasm isolated from different regions of the hyphal filament of Aspergillus nidulans was investigated. Concentrations of both ions contained in successive protoplast fractions were measured. During lytic digestion, protoplasts were released first from apical regions and subsequently from progressively older regions of hyphae. A low K+/Na+ ratio was found in protoplasts containing primarily apical cytoplasm and a high K+/Na+ ratio was found in protoplasts originating from older regions of hyphae. The ratios were the same whether MgSO4 or mannitol was used as stabilizer. Absolute concentrations of both ions were higher in protoplasts of apical origin. Protoplasts stabilized in mannitol lost more ions than those stabilized in MgSO4 over an 8 h incubation period. Na+ losses were higher from apical protoplasts whereas K+ losses were higher from protoplasts liberated from older regions of hyphae. The addition of divalent metal cations (1.5 mM-Mn2+ or Mg2+) reduced losses of Na+ from protoplasts but did not affect loss of K+. Data obtained using protoplast samples were related to those obtained for intact mycelium. Absolute losses of both ions from mycelium were lower than for protoplasts but when compared on a protein basis the data suggested that protoplasts possess properties similar to those of intact mycelium in terms of K+ and Na+ selectivity.
Low-power 2.45-GHz microwave radiation affects neither the vacuolar potential nor the low frequency excess noise in single cells of characean algae.
Single, giant cells of the eukaryotic green algae Chara braunii and Nitella flexilis were subjected to short-, intermediate-, and long-term irradiations with 2.45-GHz microwaves. A search was carried out for radiation-correlated shifts (i) in both the dc level and the rms low-frequency excess noise of the vacuolar potential and (ii) in the membrane resistivity. No reliable shifts were observed, either in normal cells or in cells subjected to reduced temperatures or the poison ethacrynic acid.
Extremely low frequency resistance fluctuations of chara membrane.
The membrane resistivity of resting characean cells was measured and found to fluctuate unpredictably about its resting level. The amplitude of these fluctuations relative to the mean resistivity was normally somewhat larger than the same ratio for the vacuolar voltage; further the resistivity and voltage fluctuations seemed not to be strongly correlated.
Vacuolar hyperpolarizing offsets in characean cells exposed to mono- and bichromatic CW and to squarewave-modulated electromagnetic radiation in the band 200-1,000 MHz.
Single giant cells of the algae Chara braunii and Nitella flexilis were exposed to bursts of electromagnetic radiation (monochromatic CW, bichromatic CW, or squarewave-modulated) in the band 200-1,000 MHz while their vacuolar potentials were monitored using micropipettes. The slow hyperpolarizing response that was observed seemed to be linear in the power deposited in the vicinity of the cell, to be otherwise indifferent to irradiation frequency or modulation, and therefore to be thermal in origin.