Monte Carlo simulation on the intrachain end-to-end charge-transfer interaction on oligosarcosines

Monte Carlo conformational calculations for oligosarcosines having terminal electron-donor (D) and -acceptor (A) chromophores [A-(Sar)_n-D, n = 2–8] were carried out. The bulkiness of the terminal chromophores, the conformational energies, and the charge-transfer (CT) interaction energy were taken into account in the calculation. The equilibrium constant for the intramolecular end-to-end CT interaction was evaluated, and the result was compared with the experimental data. The alternating chain-length dependence of the equilibrium constant observed experimentally was reproduced by the simulation and the solvent dependence of the equilibrium constant was also reasonably explained.     

Glycogen biosynthesis in Chromatium strain D: I. Characterization of glycogen

Glycogen granules were isolated from the photosynthesizing cellsof purple sulfur bacterium, Chromatium strain D, and the chemicalstructure was studied by enzymic hydrolysis using -and ß-amylasesand pullulanase. The end-group assay of the bacterial glycogenby periodate oxidation gave the following analytical data: (average chain length), 11; ICL (interiorchain length), 3; and ECL (exterior chain length), 7. We concludethat the Chromatium glycogen is a glycogen- and amylopectin-type-glucan. Intracellular accumulation of glycogen granules inthe bacterial cells harvested at different growth stages wasexamined by electron microscope observation. ¹This research was supported in part by a research grant fromthe Ministry of Education of Japan (No. 758036). (Received February 9, 1973; )     

STUDIES ON THE MICROTUBULES IN HELIOZOA : III. A Pressure Analysis of the Role of These Structures in the Formation and Maintenance of the Axopodia of Actinosphaerium nucleofilum (Barrett)

Electron microscope preparations were made of specimens of Actinosphaerium nucleofilum fixed in glutaraldehyde before, during, and after exposure to high pressures (4,000 to 8,000 psi). A study of this material showed that, although other organelles were relatively stable, the microtubular elements of the axopodia and cytosome became unstable under pressure. Their rapid disintegration under pressure was correlated with beading and retraction of the axopodia. Moreover, after the release of pressure, microtubules reappeared as soon as, or sooner than the reextension of the axopodia. The rate of disintegration increased as the pressure was raised. At 4,000 psi, few if any tubules remained after 10 min, whereas at 6,000 and 8,000 psi the disintegration was much more rapid. Some adaptational reorganization of the microtubules and axopodia occurred while relatively low pressures were maintained. This was accompanied by an actual elongation of the axopodia in specimens maintained for 20 min at 4,000 psi, but was confined to knoblike axopodial remnants in animals kept at 6,000 psi. No regeneration of tubules or axopodia occurred at 8,000 psi. The presence of fibers and a finely fibrillar material in pressurized animals suggests that these may be derivatives of microtubular disintegration. This evidence, though purely morphological, is consistent with the hypothesis that microtubules play an important role not only in maintaining the formstability of the axopodia, but also in the active process by which the axopodia reextend themselves after retraction.     

Inhibition of glucokinase in hepatocytes by alloxan

The effect of alloxan on glucokinase in isolated rat hepatocytes was studied. Exposure of hepatocytes to alloxan (3 mM) at 30 degrees C for 5 min produced a marked inhibition (77%) of glucokinase activity and altered slightly the phosphofructokinase activity (32% inhibition). Pyruvate kinase and glucose 6-phosphate dehydrogenase, however, were not inhibited at all. Alloxan induced a concentration-dependent inhibition of glucokinase activity with a detectable inhibition at an alloxan concentration of 1 mM. The inhibition of glucokinase activity by alloxan was protected by the simultaneous presence of 15 mM hexose such as D-glucose, 3-O-methylglucose, or D-mannose. D-Galactose showed no protective effect. These results suggest that alloxan may exert its cytotoxic action through the inhibition of glucokinase activity not only in the liver but also in the pancreatic islets, since liver and islet glucokinases are known to be quite similar in various properties.     

Expiratory activity in transferred intercostal nerves in brachial plexus injury patients

Involuntary activity of transferred intercostal motor units was examined in patients with brachial plexus injury. Since the internal intercostal nerves were detached from the thorax to reinnervate the musculus biceps brachii, it was possible to record pure intercostal motor activity in humans. Respiratory activity was seen in the latter part of the expiratory phase, thus dividing the phase into two substages (E1 and E2) by the onset of the activity. CO2 rebreathing prolonged the duration of the intercostal motor activity and increased the tidal activity as determined from the integration curve. There was a close linear correlation between these two variables. These observations indicate that expiratory activity and its duration are actively controlled in humans.     

A new bioassay system for screening high berberine-producing cell colonies of Thalictrum minus

A new method of estimating the amount of berberine released from minute cell colonies of Thalictrum minus has been devised to facilitate the selection of high berberine-producing cell lines. In this system, cell aggregates obtained from a cell suspension culture are grown on small pieces of an agar culture medium and the concentration of berberine which has been released from the cells into the agar piece is assayed by the antibacterial activity against Bacillus cereus MT2026. Screening of 1000 cell colonies by the agar piece method has resulted in the isolation of four, high berberine-producing cell lines, although they have been found to be more or less unstable with respect to the biosynthetic capability during successive subcultures.     

Morphological aspects of the development of swimming and feeding functions in the milkfishChanos chanos

Development of swimming and feeding abilities based on morphological development of larval and early juvenileChanos chanos was investigated. In larvae smaller than about 6.5 mm SL, mechanical supports of fins and branchial arches were in a primordial stage of development. Supports and rays of the vertical fins and branchial arches rapidly developed from 6.5 mm SL, and all components appeared by about 10.5 mm SL. Thereafter body depth proportion changed and the supports and rays of the paired fins and gill-rakers developed. These developmental events were nearly or totally completed by about 17 mm SL, and we concluded that the larvae transformed to juveniles at this size. By this time, the mode of swimming of the fish shifted from undulating locomotion to caudal propulsion and that of feeding from swallowing paniculate food to filtering and concentrating substrate food matters using gill-rakers and the epibranchial organ. One of the most characteristic, and well-known, phenomena in the life history ofChanos chanos is the mass occurrence in the surf zone of postlarvae of a limited size range. In view of the scheme of the development of mechanical supports of the body and fins, they may acquire a swimming ability strong enough to move against the current only upon reaching about 10.5 mm SL, and if active shoreward migration of the larvae occurs, it is only during the late period of their journey from the spawning grounds to the shore. The sudden disappearance from the surf zone of larvae larger than 15–16 mm SL is obviously related to a change in food habit.