Quantitative Studies on the Growth of Allogromia laticollaris (Foraminifera)

SYNOPSIS. The growth and reproduction of Allogromia laticollaris was studied. More schizozoites were generally produced in mixtures of food organisms than on single algal foods. In the presence of moderate numbers of bacteria, cultures with Phaeodactylum tricornutum, Chlorococcum sp., Nannochloris sp., and an unidentified chlorophyte (BL-1), added singly, were also highly productive. Schizogony was the dominant asexual form of reproduction. Binary fission and cytotomy also occurred in bacterized otherwise unfed controls. ³⁵S and ³²P are convenient labels for measuring growth of A. laticollaris when introduced into the system in the range of 1 × 10⁴ - 1 × 10⁵ dpm/ml (³²P specific activity ～ 2.03 MCi/g; ³⁵S specific activity ～ 95 μCi/g). Small allogromiids grew faster than did larger ones. By means of the Taylor series modification of the classical least-squares method, a continuous life-cycle representation was calculated for A. laticollaris for the conditions of the experiment. Four points of cell volume growth were maxima for reproduction: 1.0 × 10⁷μ per organism for curve I; 2.2 × 10⁷μ³ and 1.2 × 10⁷μ³ for curve II; and 6.7 × 10⁷μ³ for curve III.     

Role of Calcium and Adenosine Cyclic 3′-5′ Phosphate in Action of Adrenocorticotropin

ALTHOUGH adenosine cyclic monophosphate (cyclic AMP) has been proposed as a mediator through which many hormones exert their physiological effects¹, it is also well established that calcium plays a crucial role in hormone release². Both calcium^3,4 and cyclic AMP^1,5 have been implicated in the action of adrenocorticotropin (ACTH) on the adrenal cortex and although various hypotheses have been advanced concerning their roles in steroid production and release, elucidation of their functions in the adrenal gland is hindered because most studies have been carried out on in vitro systems where the physiological release response cannot be studied. The isolated cat adrenal gland perfused in situ ⁶ approximates the situation in vivo, yet eliminates the influence of several factors, including the anterior pituitary. In the intact adrenal preparation one can also measure both steroid synthesis and release and can better evaluate the respective effects of cyclic AMP and calcium on these processes.