The binding of glycolytic enzymes to the cytoskeleton--influence of pH

In a continuing study of the interactions between glycolytic enzymes and cytoskeletal structure, the influence of a variation of the pH of the eluting medium has been investigated. This treatment resulted in an increased degree of binding of most of the glycolytic enzymes with a decrease in pH, with the most marked increases in binding occurring with phosphofructokinase, glyceraldehydephosphate dehydrogenase, enolase and pyruvate kinase. The significance of this data has been discussed with reference to the relative affinities of interaction of the individual glycolytic components and the physiological correlations of these phenomena.     

The ultimobranchial body in Rana pipiens

Summary Hypercalcemia was induced in male frogs by injection of Vitamin D₂ and maintaining animals in calcium chloride water. The fine structure of the Ultimobranchial gland was examined 3, 7 and 14 days after the initial injection. The initial response observed after the third day was a depletion of secretory granules in addition to an alteration of nuclear shape and cytoplasmic hypertrophy. After seven days secretory granule depletion continued and early cell types occurred which indicated an increase in mitotic activity. There was also a demonstrable increase in the amount of ergastoplasm and hypertrophy of the Golgi apparatus. On the fourteenth day, the height of the epithelium was markedly increased while the underlying vascular network was enlarged and more intimately associated with the secretory parenchyma. The homeostatic mechanisms of the Ultimobranchial gland appear to include both a rapid secretory response upon stimulation and a cellular renewal system to replace exhausted cells. This suggests that such a glandular system provides a mechanism to supply a rapidly expanding cell population to meet the demands of an excessive depletion of secretory materials. The response of this gland to hypercalcemia supports previous studies which suggest that the Ultimobranchial gland is the probable source of the hypocalcemic hormone, calcitonin.This project was supported in part by funds provided by the Department of Anatomical Sciences and National Institutes of Health, Grant No. AM-11795.     

The ultimobranchial body in Rana pipiens

Summary Autoplastic transplants of ultimobranchial glands of male Rana pipiens were bilaterally or unilaterally placed in a homeotopic or heterotopic site. Serum calcium levels were maintained at normal values in bilateral autotransplants, while total ultimobranchialectomy resulted in hypercalcemia. Electron microscopy verified the viability and functional state of transplanted, denervated glands. During the periods of denervation, ergastoplasm and Golgi membranes exhibited hypertrophy which was reversed when unmyelinated nerves reappeared in the pericapillary space. Autotransplants under hypercalcemic conditions indicated that the process of secretion is primarily an intrinsic cellular activity and independant of innervation. The present evidence suggests that the sympathetic axons which innervate the parenchyma probably are inhibitory in nature and may allow depression of glandular functions during periods of hypercalcemia.The technical assistance of Mrs. Lilly Weeks is gratefully acknowledged. This project was supported by N. I. H. Grant No. AM-11795; The National Institutes of Arthritic and Metabolic Diseases.     

Glutamate receptor binding in juvenile and adult Rana pipiens CNS

Autoradiographic methods were used to map NMDA and quisqualate-sensitive glutamate binding sites in the brain of mature and juvenile Rana pipiens frogs. NMDA and quisqualate-sensitive sites were consistently co-localized in the CNS. The highest glutamate binding occurred in the telencephalon, hypothalamus, and cerebellum. Glutamate binding sites were also specifical neuropil of the optic tectum, consistent with glutamate being the retinal ganglion cell neurotransmitter. The distribution of glutamate binding sites in the brain of juvenile postmate morphic frogs was similar to that in adults. In general, Quis binding increased about twofold in adults compared to juveniles, whereas NMDA binding did not show a comparable developmental increase. To test whether glutamate binding sites are located on retinal axon terminals or on tectal cell dendrites in the optic tectum, juvenile postmetamorphic frogs were enucleated unilaterally, and receptor binding was performed following 1, 3, 7, and 14 days survival. The denervated tectal neuropil showed a delayed decrease in NMDA-and quiequalate-sensitive binding, consistent with the receptors being located on postsynaptic tectal cell dendrites. © 1994 John Wiley & Sons, Inc.     

The influence of molecular crowding on the binding of glycolytic enzymes to cytoskeletal structure

In a study of the interactions between glycolytic enzymes and cytoskeletal structure, the effect of increasing the degree of molecular crowding by the addition of protein was studied. This treatment resulted in an increased degree of binding of all the glycolytic enzymes, but with the most marked increases occurring with phosphofructokinase, enolase and pyruvate kinase. The significance of this data has been discussed in relation to the relative affinities of interaction of the individual components, the influence of molecular crowding and the physiological significance of this phenomenon.     

Speciation in the Rana pipiens Complex

The long held view that leopard frogs (Rana pipiens complex)are a single widely distributed species is not correct. Fivesibling species are currently recognizable. These findings haveimportant implications on the use of leopard frogs in experimentalresearch.     

Cytodifferentiation in the Rana pipiens oocyte

Summary In early diplotene frog oocytes incubated to illustrate thiamine pyrophosphatase (TPPase) activity, reaction product is uniformly distributed within the compartments of the endoplasmic reticulum and nuclear envelope as well as within the saccules and small vesicles comprising the dictyosomes. With continued oocyte development the reaction product becomes concentrated in localized regions of the dictyosome saccules. Eventually, the enzyme is no longer apparent within the endoplasmic reticulum, but is concentrated in the cisternae of the inner dictyosome saccules. The variations noted suggest that the enzyme is synthesized early in diplotene by the endoplasmic reticulum and is subsequently transported to the Golgi apparatus where it is consistently observed at later developmental stages. TPPase activity is also present in the Golgi apparatus of follicle and theca cells as well as in ovarian epithelial cells. The enzyme is also detected in micropinocytotic vesicles contained within the cells comprising the follicle envelope and in intercellular spaces of the follicle. Horseradish peroxidase injected into the coelomic cavity is transported via micropinocytotic vesicles into and through the cells comprising the follicle envelope and in intercellular spaces. The exogenous protein is not found even after a prolonged time period in early diplotene oocytes. The protein is, however, present in large spherical and tubular vesicles in the cortex of vitellogenic oocytes approximately 500 microns in diameter. The possible functional role of the enzyme TPPase during oogenesis is discussed.This investigation was supported by a research grant from the National Science Foundation (GB-8736).     

Seasonal changes in the activities of glycolytic enzymes from liver and skeletal muscle of Rana perezi

Glycogen phosphorylase (GP), Hexokinase (HK), Phosphofructokinase (PFK), Pyruvate kinase (PK) and Lactate dehydrogenase (LDH) activities from skeletal muscle and liver were measured in Rana perezi for the four seasons of the year. Skeletal muscle showed a decrease in PFK, PK and LDH activity during winter and summer. Liver displayed an increase in GP activity in spring and in PK and LDH in autumn.     

The ear and hearing in the frog, Rana pipiens

The development of electric organ spindles of Gymnarchus niloticus has been investigated with respect to the exact time and place of origin and the process of formation of the adult plan. The results are compared with those of Dahlgren ('14). A common primordium for all the electroplates of of a spindle as held by Dahlgren ('14) is not supported by the present work.