Decrease In Parallel Research Articles

Repressed and derepressed synthesis of phosphatases during synchronous growth of Chorella pyrenoidosa

Synchronized cultures of the green alga Chlorella pyrenoidosa were used to study the repressed and derepressed synthesis of acid and alkaline phosphatases. These enzymes were synthesized stepwise during the cell's life cycle, the synthesis being derepressed after removal of orthophosphate from the growth medium. Derepression of enzyme synthesis at different times during the life cycle showed that the rates of derepressed enzyme synthesis varied with cell age. A decrease in rate parallel with the mitotic activity was observed.

Decomposition of phospholipids during Wallerian degeneration.

Abstract—Of the lipid metabolic changes in Wallerian degeneration, the decomposition of phosphatides was studied in the early stages, 2–14 days after the nerve had been cut. It was found that the decomposition of phosphatides begins only 6 days after section. The amounts of lipid‐P and fatty acid ester decrease in parallel. However, a greatcr decrease in the amount of fatty aldehyde was observed than of the lipid‐P and fatty acid ester; this indicates that the vinyl ether bonds of glycerophosphatides are more sensitive to the degenerative process than the fatty acid ester or phosphorus.The fatty acid ester: lipid‐P ratio, calculated from the results, does not change; however, the fatty aldehyde: lipid‐P ratio shows a marked decrease during this same period. The values of the ratios indicate that in the 2nd week following nerve section, decomposition of glycerophosphatides containing fatty aldehyde (i.e. plasmalogens), in contrast to glycerophosphatides of diacyl form, may be only partial. Thus, in the 2nd week of Wallerian degeneration the formation of lysophosphatides may be presumed to come from the plasmalogens.

Changes in thiamine in the developing chick embryo.

1. There is no change in the total thiamine contents of the egg during the course of incubation but there is a gradual transfer of thiamine to the embryo in the esterified form with development of the embryo. The quantity of thiamine in other parts gradually decreases and there is a marked decrease in the free thiamine parallel with development of the yolksac and allantois. The major part of the thiamine in the allantois including the allantoic fluid, is in the free form.2. In the embryo, thiamine is stored in the brain and muscle and there is a gradual transfer to the heart, liver and intestine. With increase in function of the latter organs, a sharp rise in the thiamine levels occurs.

Influence of Application of Cold to the Dog's Body upon the Blood Pressure and the Blood Sugar, with Special Reference to the Augmented Epinephrine Secretion

Being led by the facts first that application of severe external cold upon the animal (dog) body such as to cause the body temperature to fall below 30°C. causes clearly an acceleration in the epinephrine output rate from the suprarenal gland, and secondly it produces on the other hand some definite changes in the arterial blood pressure, the pulse rate and the blood sugar concentration, the present investigations were made for elucidating what role is played by the augmented epinephrine secretion in the alterations in the circulatory systems and in the carbohydrate metabolism. (1) Small dog was dipped into a cold bath of about 0.5°C., without fastening it on the board or narcotizing, but gently handled by two assistants, until the anal temperature fell to about 30° or often about 28-25°. The arterial blood pressure was continuously recorded by means of a mercury manometer or a Hurtle's; dipping was interrupted from time to time for taking blood samples and anal temperature measurement. After the final withdrawal from the icewater bath the body temperature continued further to fall for a while with subsequent gradual recovery. The arterial blood pressure ascended promptly to about 200mms. Hg. or higher, but it began to fall somewhat gradually, in parallel with the body temperature fall, and in a later period it fell under the initial level. The pulse rate increased promptly on dipping, usually over 200 beats per minute, but it soon turned to decrease in parallel with the body temperature fall, and when the body temperature inclined to recover, the pulse rate began to increase and in fact there was some large acceleration, of 20-40 beats per minute and of a duration of some ten minutes in the early stage of the recovery. The blood sugar content increased rather slowly, but it recovered the initial value before the body temperature was restored. The removal of the suprarenal medulla exaggerated the body temperature fall, the blood pressure fall and the bradycardia, the acceleration of the pulse rate in the recovery period being largely reduced too, and prolonged the hyperglycaemic period. Introduction of adrenaline hydrochloride-saline solution in the magnitude and time relation corresponding to the epinephrine output causable by severe cooling, abolishes these variations due to the loss of the suprarenal medulla. Otherwise expressed; the augmented secretion of epinephrine from the suprarenal glands on cooling the dog excessively, acts to moderate the fall of the body temperature, that of the arterial blood pressure, and the retardation of the heart beat. The hyperglycaemic period is cut short too; this might be accounted for by the other sequences above referred to. In connection with the above experiments, the following ones were carried out. (2) By use of avertin, excitement and struggling on dipping the dog into the cold bath was entirely avoided, but the blood pressure elevation and the tachycardia occurred although much weaker than in the dog non-narcotized. The hyperglycaemia was of similar degree to that in the dog under avertin. (3) Cold water was introduced into the stomach of the dog directly through the stomach fistula previously prepared in such an amount as to cause a heat debt of about three thousand small calories per kilo of body weight. It resulted in a remarkable tachycardia, such as 20-70 beats per minute and often a hypertension of 20-40 mms. Hg. Latencies were longer in comparison to the dipping experiment above quoted. A slight hyperglycaemia slowly developed too.