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Biomedical subjects

F Crescitelli

Publications and source records attributed to F Crescitelli.

52 records · Page 3Linked to original sources
PubMed1969

The circular dichroism of suspensions of frog rod outer segments.

The circular dichroism (CD) of suspensions of frog rod outer segments has been measured. At wave-lengths between 600 and 400 nm1. The suspensions show a large positive CD increasing towards shorter wave-lengths and largely unaffected by bleaching. This probably arises, at least in part, from the preferential scattering of one form of circularly polarized light.2. There is a small reduction in CD on bleaching, slightly larger but similar in sign and wave-length dependence to that shown by pigment extracts. At wave-lengths between 250 and 220 nm3. The suspensions show a CD somewhat similar in sign, magnitude and wave-length dependence to that given by pigment extracts.4. On bleaching there is a reduction of the negative CD at 225 nm again similar to that which takes place when extracts are bleached. The observations suggest that configurational changes, of the kind detected by CD, occur in the bleaching of rhodopsin molecules whether they are present in solutions or in rods.

Animals↗
PubMed1966

Electroretinogram of the frog during embryonic development.

Eyes removed from frog embryos at various stages of development gave a definite pattern of change in the electroretinogram. From the 7th to 9th days the electroretinogram consisted of slow, purely cornea-negative potentials. From the 9th to 10th days the responses were negative but included a prominent fast, negative component superimposed on the slow potentials. During the 11th to 17th days positive potentials appeared and developed. From the 20th day on, the typical electroretinogram of the adult obtained.

Animals↗
PubMed1965

Color vision in the antelope ground squirrel.

Antelope ground squirrels (Citellus leucurus) were able, after conditioning, to respond correctly to a port illuminated with light at a wavelength of 460 nanometers. This color randomly presented at one of two positions, was correctly selected in reference to a second port illuminated with light at 500, 520, 569, and 600 nanometers, or with white light of varying intensity. Luminosity was not a factor in the discrimination.

Animals↗