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Biomedical subjects

B Weiss

Publications and source records attributed to B Weiss.

At least 433 records · Page 24Linked to original sources
PubMed1970

Adenosine 3'-5'-monophosphate in rat pineal gland: increase induced by light.

Rats were maintained in alternating periods of 12 hours of light and 12 hours of darkness. The concentration of adenosine 3',5'-monophosphate in pineal gland was six times higher at the end of the light period than at the end of the period of darkness. This effect of light was abolished in blinded animals.

Adenine Nucleotides↗
PubMed1970

Terminal cross-linking of DNA strands by an enzyme system from Escherichia coli infected with bacteriophage T4.

An enzyme system, purified 560-fold from Escherichia coli infected with bacteriophage T4, catalyzes the formation of a phosphodiester bond between the original 5'-phosphoryl end-group of a DNA strand and a 3'-hydroxyl group of the complementary strand. The product, a terminally cross-linked, spontaneously renaturable DNA duplex, has been characterized by chromatographic analysis, by sedimentation analysis, and by enzymatic digestion. Essential components of the enzyme system, which requires both ATP and Mg(++), include the T4-induced DNA ligase and a component found in extracts of uninfected E. coli, which is probably an exonuclease.

Centrifugation, Density Gradient↗
PubMed1969

Further observations on overt "mediating" behavior and the discrimination of time.

When the lever-pressing behavior of five rats was maintained by a DRL schedule (reinforcement was scheduled only when a specified waiting time between successive responses was exceeded), collateral behavior developed that apparently served a mediating function. In two cases this behavior did not arise until the experimental environment included pieces of wood that the rats started to nibble. When collateral behavior first appeared, it was always accompanied by an increase in responses spaced far enough apart to earn reinforcement. If collateral behavior was prevented, the number of reinforced responses always decreased. Extinction of lever pressing extinguished the collateral behavior. Adding a limited-hold contingency to the schedule did not extinguish collateral behavior. It appears that the rat can better space its responses appropriately when concurrently performing some overt collateral activity. The amount of this activity apparently comes to serve as a discriminative stimulus. To assume the existence of internal events that serve as discriminative stimuli in temporal discriminations is, at least under some circumstances, unnecessary.

Animals↗