. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CONTROL OF NEUROSECRETION 283 Prolonged exposure of diapausing Cecropia to low temperature is without detectable effects in restoring the brain's ChE. Fourteen determinations on a total of 44 brains from pupae chilled at 6° C. showed that cholinesterase remained un- detectable, even though two of the determinations were on the brains of pupae chilled for as long as 30 weeks. Consequently, it is clear that the diapausing brain, even after prolonged chilling, is characterized by a ChE titer undetectable by the present methods.
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CONTROL OF NEUROSECRETION 283 Prolonged exposure of diapausing Cecropia to low temperature is without detectable effects in restoring the brain's ChE. Fourteen determinations on a total of 44 brains from pupae chilled at 6° C. showed that cholinesterase remained un- detectable, even though two of the determinations were on the brains of pupae chilled for as long as 30 weeks. Consequently, it is clear that the diapausing brain, even after prolonged chilling, is characterized by a ChE titer undetectable by the present methods. In the preceding section these brains were likewise found to be electrically silent. In the brains of previously chilled pupae ChE becomes detectable after a few days at 25° C. For example, Figure 3 illustrates results obtained on a series of pupae previously chilled for 13 weeks at 6° C. When the animals were placed at 25° C. and their brains analyzed at successive intervals, ChE remained undetectable for the first four days. Then, on the fifth day, brain ChE became barely detectable. Thereafter the activity increased rapidly until the onset of adult development, and then more slowly. Apparently, a slight but definite decline in ChE occurs prior to the emergence of the adult moth. Figure 3 likewise makes clear that the re- turn of detectable titers of brain ChE correlates in time with the appearance of electrical activity. Similarly, a total of six individual determinations on the brains of developing Telea and eight determinations on the brains of developing Saniia showed that the post-diapausing brains of these species contained finite titers of ChE. It will be recalled that the ventral nerve cord retains electrical activity through- out diapause. The ganglia from diapausing or chilled pupae also retained ChE, hydrolyzing an average of ± p,M of ACh per ganglion per hour. As re- corded in Figure 3, the enzymatic activity of the ganglia remains uniform through-
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
