Multiangle light scattering flow photometry of cultured human fibroblasts: comparison of normal cells with a mutant line containing cytoplasmic inclusions.

Multi-angle light scattering flow photometry was used to study the light scattering properties of normal cultured fibroblasts and a mutant fibroblast line containing cytoplasmic lysosomal inclusions. The effect of glutaraldehyde fixation on the light scattering properties of the cells was also examined and correlated with their ultrastructure. Normal fibroblasts showed uniform organelle distribution with few vacuoles or dense bodies in the cytoplasm while the mutant line showed abnormal cytoplasmic inclusions of varying morphology, density and lucency. As predicted by light scattering theory, the mutant cells containing the cytoplasmic inclusions scattered more light at large angles (greater than theta = 1.85 degrees) than did the normal cells. Glutaraldehyde fixation decreased light scattering at small angles (less than theta = 1.85 degrees), increased light scattering at larger angles (greater than theta = 1.85 degrees) in both normal and mutant cells and enhanced resolution of the light scattering signatures. The mutant line scattered 2-3 times more light at a wide angle (greater than theta = 12.74 degrees) than did the normal cells. These data suggest that abnormal lysosomal storage inclusion bodies in the cytoplasm of the cells can be detected by differential light scattering methods.     

Intermediate filaments connect z-discs in adult chicken muscle.

When adult chicken skeletal myofibrils are treated with a myosin-extracting solution, the Z-discs with attached actin filaments retain their linear connections with one another in the extracted myofibril. The sarcomere length increases in the extracted myofibrils from a control lenght of 2.5 micrometer up to 6 micrometer. In a sarcomere, eight to fifty 10 nm filaments can be seen in parallel array in the H-zone. The 10 nm-wide filaments do not bind heavy meromyosin and are two to four micrometers in length. These intermediate filaments are postulated to be an integral part of the sarcomere, connecting Z-bands along the length of the myofibril.     

Somatic embryogenesis in suspension cultures of Gossypium klotzschianum anderss

Somatic embryoids differentiated in suspension cultures of G. klotzschianum after 3–4 weeks of culture in a liquid medium containing glutamine (optimally, 10–15 mM). Embryogenesis occurred after a preculture of callus on a medium containing 10 mg/l of the cytokinin, 2iP. The embryoids had meristematic regions, a well formed epidermis, and formed roots and vestigial leaves. Asparagine was much less effective than glutamine in promoting embryoid differentiation. The presence of 2,4-D in the medium resulted in increased vigor of the suspension cultures and subsequently in the formation of many embryoids, but does not seem to be necessary for somatic embryogenesis in cotton.Technical Article 14646 from the Texas Agricultural Experiment Station     

Proliferation of lamellar whorls in arcuate neurons of the hypothalamus of male rats treated with estradiol benzoate or cyproterone acetate

Summary The arcuate nucleus of the hypothalamus (AH) of male rats which had been treated either with estradiol benzoate (E²B) or cyproterone acetate (CPA) was examined ultrastructurally for the presence of whorls of endoplasmic reticulum. The incidence of whorl containing neurons (WCN) was 2–4 times higher in the AH of animals treated for 2–3 weeks with E²B or for 2 weeks with CPA than in the AH of oil treated controls. CPA is a powerful anti-androgen while E²B acts both peripherally and centrally to limit testosterone production. These findings, together with previous evidence that whorls proliferate in AH of male rats deprived of androgen by morphine treatment or castration, suggest that steroid feedback (androgen alone or both androgen and estrogen) plays an important role in AH whorl proliferation. The possibility that WCN may be LH-RH containing neurons is suggested by the close correspondence between the number and location of WCN within AH as determined in this study and the distribution of LH-RH containing cells reported by others.The authors are indebted to Schering AG for supplying cyproterone acetate for this study. This work was supported by grants DA-00259, NS-09156 and MH-14677 from U.S.P.H.S.Research Scientist Development Award MH-38894Research Scientist Development Award MH-70180     

Purification and properties of the arginine-specific carbamoyl-phosphate synthase from Saccharomyces cerevisiae.

The arginine-specific carbamoyl-phosphate synthase of yeast was stabilized sufficiently to allow partial purification of the enzyme (30- to 40-fold). The synthase (mol. wt 115000) comprised two unequal subunits: a heavy subunit (mol. wt 80000) capable of catalysing synthesis of carbamoyl phosphate with ammonia as a nitrogen donor and a light subunit conferring upon the holoenzyme the ability to utilize glutamine. The enzyme had unusually high affinity for ATP (Km = 0.2 mM) and atypical negative cooperativity for glutamine binding ([S]0.5 = 0.25 mM). Glutamine activity was not modulated by possible effectors such as arginine, ornithine or N-acetylglutamate. Thus, although the yeast arginine enzyme physically and functionally resembles the single enteric synthase, the systems differ substantially both in kinetic properties and in regulation of activity.     

Results of 12 years' treatment of chronic renal failure by dialysis and transplantation.

The survival of 305 patients with chronic renal failure treated at the Vancouver General Hospital by centre and home peritoneal dialysis, centre and home hemodialysis and cadaver renal transplantation over a 12-year period was analysed. There was decreasing survival with age except in patients undergoing home dialysis. Hypertension and analgesic nephropathy as primary causes of renal disease were associated with a poor prognosis. Hence age and diagnosis appear to be two of the main determinants of survival. Cardiovascular disease was the commonest cause of death but seven deaths were due to dialysis dementia. The results compare favourably with other published statistics.     

Associations of like and unlike polysaccharides: Mechanism and specificity in galactomannans,interacting bacterial polysaccharides,and related systems

Chiroptical, rheological, and n.m.r.-relaxation evidence is presented, to identify interactions of two types between different polysaccharides: (1) mutual exclusion of incompatible molecules, with consequent increase in the effective concentration of both; and (2) energetically favourable association of structurally and sterically regular chain-segments. β-1,4-linked plant polysaccharides interact by association of unsubstituted backbone regions, either with like chians, or with sterically compatible, unlike molecules. Extracellular polysaccharides (xanthans) of Xanthomonas plant pathogens maintain their ordered native conformation in solution, and this accounts for their industrially valuable, rheological peculiarities. These materials bind strongly to the plant glycans. Random-coil bacterial gums show no such interactions, although dextran enhances autogelation of galactomannans by exclusion. Extracellular polysaccharides from Arthrobacter species also have ordered native conformations in solution, but do not share the specific interactions of xanthan. Native xanthan shows marked specificity in its interactions with plant glycans, indicating a possible biological role in host-pathogen recognition.