Fine structure of the excretory system of Amphioxus (Branchiostoma floridae) and its response to osmotic stress

Summary The excretory organs of Amphioxus occur as segmentally arranged structures throughout the pharyngeal region and may be divided into three components: the solenocytes, the renal tubule, and the renal glomerulus.The solenocytes possess foot processes that rest upon the coelomic surface of the ligamentum denticulatum. The tubular apparatus of the solenocytes consists of ten triangular rods surrounding a central flagellum. The distal end of the tubular apparatus enters branches of the renal tubule. The renal tubule eventually opens into the atrial cavity of Amphioxus. The renal glomerulus is a sinus within the connective tissue of the ligamentum dentieculatum where it connects elements of the branchial circulation with the dorsal aorta. The renal glomerulus, like other blood vessels of Amphioxus, lacks an endothelial lining.If Amphioxus is adapted to artificial sea water at different concentrations there is no change in kidney morphology suggesting that Amphioxus is either is osmotic with its environment or is osmoregulating with other organs.This work was supported by U.S. Public Health Service Grant 5-T01-GM 00582.     

Sulfhydryl and Disulfide Patterns Associated with Vernalization of Wheat

Analyses of plumules from seedlings of a winter wheat variety (Elgin) and a spring wheat variety (Red Bobs) indicated that SH and SS contents based on protein levels were similar in the whiter and spring wheat tissues grown at 20 C. Boll) varieties, when grown nt 3 C, contained greater concentrations of SH and SS groups, based on protein levels, than those present in the tissues grown at 20 C. The spring wheat tissues at 3 C maintained relatively constant levels of SH and SS during the growth period. Sulfhydryl (SH) and SS groups based on fresh weights were present in greater quantities in the tissues of the spring wheat grown at 20 C than in the winter wheat tissues grown at 20 C. The high SH and SS concentrations present in the warm-grown spring wheat tissues were due to a high concentration of protein extracted from that tissue. The SH and SS contents per unit fresh weight were quite similar in the cold-grown tissues of both varieties during the growth period. Both varieties at both temperatures showed a similar decrease in SH and SS contents, based on fresh weights, as maturation progressed. The spring wheats grown at 3 C and 20 C and the winter wheat grown at 3 C all showed similar characteristics and differed considerably from the winter wheat grown at 20 C. These data were positively correlated with the flowering potential of the wheat varieties.     

FINE STRUCTURE OF THE MYOEPITHELIUM OF THE ECCRINE SWEAT GLANDS OF MAN

The secretory coils of glutaraldehyde-osmium tetroxide-fixed and Epon-Araldite-embedded eccrine sweat glands from the palms of young men were studied with the electron microscope. The myoepithelial cells lie on the epithelial side of the basement membrane and abut other epithelial elements directly. The irregularly serrated base of the cell has dense thickenings along the plasma membrane which alternate with zones bearing pits; the smooth apical surface lacks dense thickenings, is studded with pits, and conjoined to secretory cells by occasional desmosomes. Masses of myofilaments, 50 A in diameter, fill most of the cell and are associated with irregular dense zones. In cross-section the arrangement of the myofilaments seems identical with that of the I band of striated muscle, and the dense zone has typical Z band structure. A few microtubules and cytoplasmic cores bearing profiles of the endoplasmic reticulum, filamentous mitochondria, and glycogen granules penetrate the fibrillar masses and run parallel to the oriented myofilaments. In the perinuclear zone, Golgi membranes, rough- and smooth-surfaced elements of the endoplasmic reticulum, mitochondria, glycogen, microtubules, lipid, pigment, and dense granules are variable components in the cytoplasm. The interrelationships of the myoepithelial cells with the secretory cells suggest that the former may act as regulators, controlling the flow of metabolites to the secretory epithelium.