Regulation of cyclic AMP levels in canine thyroid slices by alpha-adrenergic action.

In an attempt to clarify the role of adrenergic receptors in metabolic responses, interaction of norepinephrine with TSH was studied in canine thyroid slices with regard to cyclic AMP levels. Norepinephrine caused a very rapid (within 1 min), but quite transient increase in cyclic AMP levels. The elevation of cyclic AMP levels induced by TSH was markedly inhibited by norepinephrine. Phentolamine, an α-adrenergic blocker, not only prevented the decline of cyclic AMP levels that followed the rise by norepinephrine, but also abolished the norepinephrine effect on the TSH-induced elevation of cyclic AMP levels. Propranolol, a β-adrenergic blocker, exhibited no such effects. These results indicate that the α-adrenergic receptors control cyclic AMP levels in the thyroid gland.     

Phototransformation of the Far-red Light-absorbing Form of Large Pea Phytochrome by Laser Flash Excitation

Phototransformation of the far-red light absorbing form (P_FR)of large pea phytochrome to the red-light absorbing form (P_R)was examined at 2?C after a 715 nm laser flash excitation usinga custom-built multichannel transient spectra analyzer. Themaximum amount of phototransformation intermediates was producedby a pulse of about 50 mJ, which resulted in ca. 65% of P_R obtainedat the photostationary equilibrium. Some flash-induced intermediateswere assumed to return to P_FR in the dark. A difference spectrummeasured at 10 µsec after the flash showed an absorbanceincrease at 651 nm and a decrease at 724 nm. When the samplewas left in darkness after the flash light irradiation, absorbancein the red and far-red region gradually increased, but thatin the green region rapidly decreased. The decay curve of intermediatesmeasured at 554 nm could be resolved into three reaction componentshaving rate constants of 2,500, 590 and 48 sec^–1, respectively.Difference spectra also indicated that a small but significantincrease in absorbance between 370 and 380 nm and a decreasearound 415 nm took place 10–310 µsec after a flash. (Received February 13, 1982; Accepted April 21, 1982)     

Effects of Calcium and Potassium Ions on Phototaxis in Cryptomonas

Effects on positive phototaxis and the cell motility of 7 cationsin 5mM MOPS (morpholinopropane sulfonic acid) buffer (pH 7.0)containing 0.16 mM NaCl, 0.68 mM KCl, 0.5 mM CaCl₂ and 0.16mM MgCl₂ were studied in the unicellular flagellate Cryptomonaswith a photoelectrical measuring apparatus and photomicrography.When calcium ion was removed from the medium by adding 1 mMEGTA (ethylene glycol-bis-(ß-amino-ethylether)-N,N'-tetraaceticacid), the phototactic response was totally inhibited, but theswimming rate was not much affected. The effect of EGTA waspartially reversed by the addition of 1 mM CaCl₂. When 15mMKCl or RbCl was added to the medium, phototaxis was greatlyinhibited, but there was no significant influence on the swimmingrate. Similar but less inhibitory effects were induced in thepresence of NaCl, LiCl and CsCl. KCl-induced inhibition waspartially removed by the addition of 15 mM CaCl₂ or MgCl₂. (Received June 25, 1982; Accepted September 27, 1982)     

Isoforms of C-protein in adult chicken skeletal muscle: detection with monoclonal antibodies

Monoclonal antibodies (McAbs) specific for the C-proteins of chicken pectoralis major and anterior latissimus dorsi (ALD) muscles have been produced and characterized. Antibody specificity was demonstrated by solid phase radioimmunoassay (RIA), immunoblots, and immunofluorescence cytochemistry. Both McAbs MF-1 (or MF-21) and ALD-66 bound to myofibrillar proteins of approximately 150,000 daltons; the former antibody reacted with pectoralis but not ALD myofibrils, whereas the latter recognized ALD but not pectoralis myofibrils. Chromatographic elution of the antigens from DEAE-Sephadex, and their distribution in the A-band, support the conclusion that both of these antibodies recognize variant isoforms of C-protein. Since both McAbs react with a protein of similar molecular weight in the A-band of all myofibrils of the posterior latissimus dorsi (PLD) muscle, we suggest that either another isoform of C-protein exists in the PLD muscle or both pectoralis and ALD-like isoforms coexist in the A-bands of PLD muscle.     

Effects of narrow-beam irradiations with blue and far-red light on the timing of cell division in Adiantum gametophytes

Protonemata of the fern Adiantum capillusveneris L., grown as single-cell filaments under continuous red light, were irradiated with a narrow beam of blue light. Only irradiation of the region containing the nucleus induced cell division. Beams of 30 m in width, which corresponds to the diameter of the nucleus, or wider, were equally effective; beams 10 m wide or less were less effective. The results indicate that the nuclear region is the site of the blue- and near ultraviolet-light-absorbing pigment (P_B-NUV) which mediates the timing effect of cell division. In contrast, the effect of a narrow beam of far-red (FR) light, which delays the onset of the blue-light-induced cell division, was found to be present along the entire length of the protonema cell, including the largely vacuolated basal region of the latter. Polarized FR light having the electrical vector parallel to the protonema axis was less effective than that vibrating in other directions. These observations support the hypothesis that the phytochrome controlling the timing effect is localized in the plasma membrane.     

Pock Formation of Streptomycetes endus with Production of Phage Taillike Particles

Plate (or slope) cultures of endomycin-producing Streptomyces endus (KCC S-0213) showed spontaneously developing pocks which increased in number during subculturing. Neither spore formation nor typical aerial hyphae formation was observed in the pocks, whereas formation of substrate hyphase was not inhibited. Almost all of the hyphae were broken or lysed in the pocks, and many phage tail tiplike particles were observed in the pocks. No self-replication activity was associated with the particles. The particles often formed a hexagonal crystal or a large crystal mass. The production of these particles did not occur in the liquid culture or in young or normal plate cultures having no pocks. These results were similar to those obtained from the plaque-making phenomenon, except for active phage production, in thiostrepton-producing Streptomyces azureus (ATCC 14921), which has been described previously.