The Escherichia coli gene recA is essential for homologous recombination and DNA repair, and homologs have been identified in eukaryotes. A basidiomycete, Coprinus cinereus, which has many advantages for the study of meiosis, was recently reported to have a homolog of one of these, RAD51. In the yeast Saccharomyces, mutations in the RAD51 gene cause defects in both somatic and meiotic cells. Based on this finding, we screened for a meiosis-specific homolog of recA, equivalent to Lilium LIM15 or Saccharomyces DMC1, in C. cinereus, and isolated a clone containing a 1.2-kb DNA fragment from a cDNA library constructed with Coprinus poly(A)+ RNA isolated from cells undergoing meiosis. The predicted amino acid sequence was 52% identical to the putative gene product of the lily cDNA clone LIM15 and 61% identical to Saccharomyces DMC1, and showed limited sequence similarity to the products of RAD52, 55, and 57. The synchrony of meiosis in Coprinus provides an ideal system for the investigation of differential gene expression in relation to meiosis and fruiting body development. Northern analysis indicated that Coprinus LIM15/DMC1 was expressed at meiotic prophase within 8 h after the onset of karyogamy, suggesting that the gene functions mostly at the stage at which the homologous chromosomes pair, but may not be essential at the point at which they recombine. The gene is not expressed in somatic cells.
stimulation at a series of points along the floor of the hypothalamus and telencephalon. Twelve points were selected, in 12 different animals. After implantation and a 14-day recovery period, animals were trained to press a lever for chemical stimulation with iproniazid; in this case there was no prior training with electric stimulation.Whereas all animals with ventral hypothalamic pipettes showed a betterthan-chance tendency to press the bar for injection of the chemical, there was a distinct differentiation of rate of selfinjection, depending on placement of the pipette. Pipettes in the posterior hypothalamus gave higher rates of selfinjection than pipettes in the anterior hypothalamus. And high rates of self-injection were also obtained with pipettes in the dorsal preoptic region. These differences agree well with differences with respect to brain area in rate of self-stimulation obtained in earlier experiments with electric stimulation (5).When the injector was turned off, so that bar-pressing no longer produced self-injection, animals continued to press the bar for some time (see Fig. 1), as though no change had been made. This is probably attributable to the high level of the chemical in the brain at these points and to the gradual working down of residual stores in the pipette. Extinction does eventually result from termination of the flow, after a period of about 30 to 45 minutes. Also, when the animal is shifted from an extinction period to a new self-injection period, rate of responding quickly changes from chance levels to rates of about 300 an hour. Thus, it is the chemical reward which sustains the behavior. Injection of serotonin, by itself or immediately after injections of iproniazid, caused the animals to lie down. An animal lying down after injection of serotonin could be brought back to its feet by epinephrine. This, taken together with the tendency of some animals to press the bar for epinephrine, suggests that the exciting and rewarding effects of iproniazid are connected more with epinephrine than with serotonin.From the experiments on self-injection, three main results have been gained. Substantively, we have learned that iproniazid is an excitant of reward functions in this motivational system of the hypothalamus, and that quite probably it has this excitatory function in common with epinephrine. Methodologically, we have validated a technique of self-injection which can now be used to resolve further the problem of the excitatory and inhibitory chemistry of the motivational systems. Finally, from the stimulation at a series of points along the floor of the hypothalamus and telencephalon. Twelve points were selected, in 12 different animals. After implantation and a 14-day recovery period, animals were trained to press a lever for chemical stimulation with iproniazid; in this case there was no prior training with electric stimulation.Whereas all animals with ventral hypothalamic pipettes showed a betterthan-chance tendency to press the bar for injection of the chemical, there was a distinc...
Yasu KUNO, M.J.A., Nov. 12, 1963) As the procedure involved in the paper-chromatographic and pierate method for the detection of malignolipin are not so practical for use in diagnostic tests for cancer, two attempts were made to find a simple but exact method for the detection of malignolipin : one was the immunological test, and the other the test of the affinity for porphyrin.Results of the former have been reported in the
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