Spectrophotometric determination of inorganic phosphate in the presence of thiol compounds

A spectrophotometric method for inorganic phosphate determination in the presence of thiol compounds is described. Thiol compounds, which interfere with the measurement of inorganic phosphate by a modification of the method of Gomori, are removed by carboxymethylation by iodoacetate prior to the formation and reduction of phosphomolybdate complex. A linear standard curve is obtained by this method, and the method is suitable for the assay of a phosphate-releasing enzyme when the measurement must be performed in the presence of thiol compounds.     

Apterichtus keramanus, a new snake-eel from Okinawa, southern Japan (Ophichthinae, Ophichthidae)

A new snake-eel,Apterichtus keramanus, is described on the basis of a single 276-mm TL specimen trawled from the coast of Kerama Islands, Okinawa Prefecture, Japan. The species is unique in the genus in having the posterior nostril opening entirely inside the mouth and a dark band running from the anteroventral margin of the eye to the upper lip.     

Chromatic Regulation of Photosystem Composition in the Cyanobacterial Photosynthetic System: Kinetic Relationship between Change of Photosystem Composition and Cell Proliferation

Kinetics of the change of photosystem (PS) composition in cyanobacteriainduced by chromatic light were studied in relation to cellproliferation. The study was made for two unicellular strains,Synechococcus NIBB 1059 and Synechocystis (Aphanocapsa) PCC6714. We found that (1) the change to a higher or lower PS I/IIratio was due to acceleration or suppression of apparent PSI formation, and (2) it progressed on a similar time scale tothat of the cell proliferation. The apparent rate constant ofthe change in the PS I/II ratio was proportional to that ofcell proliferation, µ, when this was low, but at highvalues of µ the increase in the rate constant of the changein the PS I/II ratio became smaller, causing a deviation fromthe linear relationship. Results indicate that under autotrophicconditions, the photoregulated composition change occurs asa result of thylakoid development, which accompanies cell proliferation. (Received June 23, 1986; Accepted December 5, 1986)     

A radioimmunoassay for human pro-luteinizing hormone-releasing factor [pro-LRF(14-69)OH]

A radioimmunoassay (RIA) for human pro-LRF(14-69)OH was developed with an antiserum, generated in a rabbit, to [Tyr67]pro-LRF(47-67)NH2 conjugated to BSA. This antiserum bound 28-32% of [125I]pro-LRF(14-69)OH at a final dilution of 1:2500 and the binding was inhibited by pro-LRF(14-69)OH in a dose-dependent manner. The sensitivity of the RIA was 31.2-62.5 pg and the dose that inhibited 50% of the binding to the tracer was 280-320 pg. Intra- and inter-assay coefficients of variation at 50% inhibition were 8 and 12%, respectively. Neither LRF nor pro-LRF(14-37)OH was recognized by the antiserum. The dilution curve generated with human hypothalamic extract was parallel to that of pro-LRF(14-69)OH. In addition the extract yielded a major immunoreactive peak emerging in elution volumes concordant with [125I]pro-LRF(14-69)OH on Sephadex G-50 chromatography.     

Effect of Supra-High Irradiation on the Photosynthetic System of the Cyanophyte Synechocystis PCC 6714

Stability of thylakoid components under supra-high irradiancewas studied with the cyanophyte Synechocystis PCC 6714. Theactivity of overall photosynthesis was quickly inactivated (T_1/2=20min) under supra-high irradiance (300 W m^–2, white light).In parallel with the inactivation of photosynthesis, QA in PSII was also inactivated. Both inactivations were acceleratedby chloramphenicol (CAP) addition. The reactivation of PS IIrequired weak irradiation and was suppressed by CAP. However,PS I measured as P700 was very stable. The level of PS I measuredas P700 was not significantly reduced by the irradiation for12 h even in the presence of CAP while the level of Cyt b₅₅₉,component of PS II, was decreased markedly. The function ofPS I before and after supra-high irradiation with CAP was examinedby comparing sizes of P700 oxidation induced by a short flash,by a continuous light, and by determination of O₂-and ferredoxin-reduction.No difference was observed in PS I actions before and afterthe irradiation treatment. These results indicate that the PSI complex is very tolerant of supra-high irradiation. However,the cells grown under supra-high irradiance contained much fewerPS I and PS II complexes than Cyt b₆–f complexes. Theformer levels were reduced to a half to one fourth of thosebefore growth while the level of Cyt b₆–f complex wasnot reduced so much. A possible mechanism for changes in thylakoidcomposition under supra-high irradiation was discussed. (Received February 16, 1991; Accepted June 12, 1991)     

Mutual interactions between optic lobe circadian pacemakers in the cricket Gryllus bimaculatus

The coupling mechanism between the bilaterally paired optic lobe circadian pacemakers in the cricket Gryllus bimaculatus was investigated by recording locomotor activity, under constant light or constant red light, after the optic nerve was unilaterally severed.

Interleukin-4 downregulates interleukin-6 production by human alveolar macrophages at protein and mRNA levels.

Effects of interleukin-4 (IL-4) on IL-6 production by human alveolar macrophages (AM) obtained by bronchoalveolar lavage from healthy donors was examined at the protein and gene levels. IL-6 production was quantitated by enzyme immunoassay (EIA) and bioassay using the IL-6 dependent murine hybridoma cell line MH60.BSF2. Results showed that when activated with LPS, AM released significantly more biologically active IL-6 than blood monocytes. Human rIL-4 significantly suppressed IL-6 production by AM and monocytes stimulated with LPS. Northern blot analysis revealed that IL-4 reduced the expression of IL-6 mRNA in LPS-stimulated AM and monocytes. The inhibitory effect was most pronounced when IL-4 was added with LPS or within the first 4 hr after LPS to AM or monocytes. The suppressive effect of IL-4 was completely neutralized by pretreatment with anti-IL-4 antibody. IL-4 also showed a suppressive effect on IL-6 production by macrophages generated in vitro by maturation of blood monocytes with granulocyte-macrophage colony stimulating factor (GM-CSF). These observations suggest that IL-4 may play a critical role in in situ regulation of immune responses through suppression of IL-6 production.     

Identification of jasmonic acid in Mimosa pudica and its inhibitory effect on auxin- and light-induced opening of the pulvinules

Jasmonic acid was identified from Mimosa pudica L. plants by mass spectrometry, high performance liquid chromatography and thin layer chromatography. Effects of authentic jasmonic acid on pulvinule movement and transpiration of the pinnae were compared with those of abscisic acid. Jasmonic acid and abscisic acid each at 10⁻⁵ M inhibited both auxin- and light-induced opening of the pulvinules. A closure-inducing activity of jasmonic acid at 10⁻⁴ M was greater than that of abscisic acid at 10⁻⁴ M. Pinnae transpiration was reduced by 10⁻⁵ M abscisic acid but not by 10⁻⁴ M jasmonic acid.     

Immunohistochemical detection of bromodeoxyuridine in formalin-fixed tissues

Bromodeoxyuridine (BrdUrd) immunohistochemistry has recently been introduced for the visualization of DNA-synthesizing nuclei. In order to detect the BrdUrd incorporated into nuclear DNA in formalin-fixed, paraffin-embedded tissues, we tested several different pretreatment procedures including digestion with proteinase and hydrolysis with HCl, prior to immunoperoxidase staining. In order to determine the optimal conditions for detecting nuclear BrdUrd, mice were given BrdUrd and 3H-thymidine simultaneously, and the autoradiographic and immunohistochemical results obtained in BrdUrd-stained sections were compared. It was found that digestion with 0.05% proteinase at 37 degrees C for 20 min and hydrolysis with 1N HCl at 37 degrees C for 20 min was sufficient to detect BrdUrd immunoreactivity in 3H-thymidine-labelled nuclei, the results being virtually unaffected by the orders in which the two pretreatments were performed. Our method extends the range of application for BrdUrd immunohistochemistry in cell-kinetic studies.