Action potential (AP) generation at the plasmalemma of Chara corallina has a strong influence on photoprocesses in chloroplasts. Under physiological conditions the AP generation transiently suppresses photosynthetic electron transport and reversibly increases thermal losses of chlorophyll excitations. However, these changes provoked by membrane excitation became irreversible in the presence of ...

To study chorioretinal diffusion mechanisms in the mammalian retina, the peroxidase tracer technique, electron microscopy, and photocoagulation were used in a series of Dutch rabbits. Xenon arc photocoagulation of the retina was carried out on one eye of each animal, and three weeks later peroxidase was injected into the ear vein. At selected time intervals thereafter, the animals were killed, ...

The relevance of the neuroretinal ring (NRR) for early diagnostic of glaucoma is not a novel concept. In fact, we can all remember the ISNT mnemonic rule, which represented the distribution of sector thicknessess characteristic of a healthy NRR, for discriminating between normal papilla (rule intact) and suspect or glaucomatous papillae (rule infringed). This rule was not infallible because it ...

Organisms that use ammonium as the sole nitrogen source discriminate between [(15)N] and [(14)N] ammonium. This selectivity leaves an isotopic signature in their biomass that depends on the external concentration of ammonium. To dissect how differences in discrimination arise molecularly, we examined a wild-type (WT) strain of Escherichia coli K12 and mutant strains with lesions affecting ammon...