Immunochemical Studies on Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase in the Chloroplasts of the Marine Alga Bryopsis maxima

The localization of ribulose 1,5-bisphosphate carboxylase/oxygenase(RuBisCO) in chloroplasts of the green alga Bryopsis maximawas examined by immunological techniques. Three strains of hybridomaswere established between myeloma cells and the spleen cellsfrom mouse immunized against B. maxima RuBisCO. The antibodiesreacted with the large subunit of B. maxima RuBisCO but notwith spinach RuBisCO. Immunofluorescence and immunoenzymaticstudies showed that the large subunit of B. maxima RuBisCO wasconcentrated in pyrenoids and on the surface of starch grainssurrounding the pyrenoids. (Received September 22, 1987; Accepted March 2, 1988)     

Isolation of Native Pyrenoid Core Matrix Having Ribulose 1,5-bisphosphate Caxrboxylase Activity from the Green Alga Bryopsis maxima

The native pyrenoid core matrix of the green alga Bryopsis maximawas isolated by diethyl ether treatment and sucrose densitygradient centrifugation using 1.8 M phosphate buffer. The purityof the pyrenoids was examined by microscopy, polyacrylamidegel electrophoresis and marker materials. The purified pyrenoidscontained the large subunit and the small subunit of ribulose1,5-bisphosphate carboxylase (RuBPCase) and more than 10 minorpolypeptides. They also showed RuBPCase activity when solubilizedon being transferred to a low-concentration buffer. The specificactivity was 0.62 µmol CO₂ fixed (mg protein)^–1min^–1. This isolation method is suitable for obtainingintact pyrenoids not covered by starch sheaths or membraneswithout the need for chloroplast fixation. (Received July 27, 1987; Accepted October 20, 1987)     

Adenylate cyclase and phosphodiesterase activities in relation to a rapid increase in cellular cAMP concentration by hypotonic shock indunaliella viridis

An adenylate cyclase activity of 16.02±1.03 pmol cAMP produced min⁻¹ (mg protein)⁻¹ was detected in a cell homogenate ofDunaliella viridis, a unicellular halotolerant green alga. It was present in both the membrane fraction and soluble fraction separated from the homogenate. Adenylate cyclase activity in the homogenate was activated by 1μM GTPγS but not by Ca²⁺+calmodulin, suggesting this enzyme to be regulated by a G-protein. A phosphodiesterase activity of 23.12±15.03 pmol cAMP decomposed min⁻¹ (mg protein)⁻¹ was found in the homogenate. These activities suggest the presence of a cAMP mediated signal transduction system inDunaliella. Cells, transferred from 1.7 M NaCl medium to 1 M NaCl, showed rapid increase in cAMP within 2 min to about 1.5 times the original concentration (from 2.4±0.2 to 3.9±0.2 pmol per 10⁸ cells) which was recovered in 30 min.     

Characterization of Leptospira species isolated from soil collected in Japan

Leptospira were isolated from soil obtained from Hokkaido, the northernmost island, to Okinawa, the southernmost island, of Japan using sulfamethoxazole, trimethoprim, amphotericin B, fosfomycin, and 5‐ fluorouracil. Fifty of 132 soil samples (37.9%) were culture‐positive. On the basis of 16S‐rDNA sequences, 12 of the isolated Leptospira were classified into a pathogenic species clade that is closely associated with L. alstonii and L. kmetyi. Nine isolates were classified as intermediate species and were found to be similar to L. licerasiae. Twenty‐seven isolates were classified as non‐pathogenic species, of which 23 were found to be related to L. wolbachii. Non‐pathogenic Leptospira are commonly distributed in environmental soil.     

A new light-induced absorbance change at 561 nm in chloroplasts of green alga, Bryopsis maxima

A new light-induced absorbance change having a maximum at 561nm was discovered in the thalli, as well as in isolated chloroplastsof a green alga, Bryopsis maxima Okamura. Another simultaneous change also occurred at 515 nm. The magnitudeof the 561 nm change was several-fold larger than that at 515nm and much larger than could be explained by an oxidation-reductionchange in cytochromes contained in chloroplasts. There was noabsorbance change in the Soret region that may be correlatedto the 561 nm change. Both 561 and 515 nm changes showed a spike-liketime course pattern, both having a half-rise time of about 20msec. Effects of inhibitors and uncouplers such as DCMU, Cl-CCPand gramicidin J on the absorbance change were also similarat 561 and at 515 nm. We inferred that the 561 nm change is related to photophosphorylationand possibly to the membrane potential in a way similar to the515 nm change. (Received March 27, 1974; )     

Pigment Composition of Chlorophyll-Protein Complexes Isolated from the Green Alga Bryopsis maxima

SDS-solubilized thylakoid membranes of Bryopsis maxima showeda similar pattern to those of higher plants in SDS-poIyacrylamidegel electrophoresis. Absorption spectra and pigment compositionof both CP1 and CPa bands were similar to those of higher plantsand other algae. Five bands containing chlorophyll (Chl) b weredivided into three categories; a group of major light-harvestingChl a/b-protein complexes (LHCP 1, LHCP 2 and LHCP 3), a minorLHCP (LHCP 3') and a photosystem I complex (CP1a). LHCP 1, thehigh molecular form, showed the lowest Chl a/b ratio among theLHCPs, and contained only xanthophylls as carotenoids. LHCP2, LHCP 3 and LHCP 3' bands contained xanthophylls and carotene.Carotenoid composition of LHCP 3' was different from that ofthe major LHCPs. CP1a band contained a considerable amount ofsiphonaxanthin and siphonein. (Received May 24, 1985; Accepted December 13, 1985)     

The ventilatory threshold gives maximal lactate steady state

The purpose of this study was to examine whether the ventilatory threshold (Thv) would give the maximal lactate steady state ([la]ss, max), which was defined as the highest work rate (W) attained by a subject without a progressive increase in blood lactate concentration [la]b at constant intensity exercise. Firstly, 8 healthy men repeated ramp-work tests (20 W.min-1) on an electrically braked cycle ergometer on different days. During the tests, alveolar gas exchange was measured breath-by-breath, and the W at Thv (WThv) was determined. The results of two-way ANOVA showed that the coefficient of variation of a single WThv determination was 2.6%. Secondly, 13 men performed 30-min exercise at WThv (Thv trial) and at 4.9% above WThv (Thv + trial), which corresponded to the 95% confidence interval of the single determination. The [la]b was measured at 15 and 30 min from the onset of exercise. The [la]b at 15 min (3.15 mmol.l-1, SEM 0.14) and at 30 min (2.95 mmol.l-1, SEM 0.18) were not significantly different in Thv trial. However, the [la]b of Thv + trial significantly increased (P less than 0.05) from 15 min (3.62 mmol.l-1, SEM 0.36) to 30 min (3.91 mmol.l-1, SEM 0.40). These results indicate that Thv gives the [la]ss, max, at which one can perform sustained exercise without continuous [la]b accumulation.     

Recombination between short direct repeats in Streptomyces lavendulae plasmid DNA.

Streptomyces lavendulae S985 carried two plasmids, pSL1 and pSL2. pSL2 contained all of the pSL1 sequences plus a tandem duplication of 900 base pairs from a region of pSL1. Sequence analysis of the duplication junction suggested that the duplication occurred by recombination between short direct repeats of as little as 5 base pairs.     

Structural change of myofibrils during mitosis of newt embryonic myocardial cells in culture

Newt embryonic myocardial cells can undergo mitosis in culture. The successive changes in the striation pattern of sarcomeres of myofibrils during mitosis were studied by polarization microscopy without fixing or killing the cells. Birefringence of well-organized striation patterns, i.e., bright A-bands and dark I-bands, was clearly visible in interphase cells and did not show any detectable changes during incubation for 3 h or more. Electron microscopy showed the presence of well-organized myofibrils with Z-bands in these interphase cells. When myocardial cells entered the mitotic stage, the birefringence of striation pattern of their myofibrils gradually changed with the pattern in small parts of the myofibrils gradually becoming indistinct (called 'indistinct striation' in this paper). These indistinct regions increased in size during the mitotic stage. In addition, in some regions of the indistinct striation, the birefringence of sarcomeres gradually decreased and finally disappeared (called 'disappearance of sarcomeres' in this paper). No myocardial cells underwent mitosis without these disruptive changes of the myofibril striation patterns. In the post-mitotic stage, the well-organized striation of the myofibrils reappeared. Electron microscopy showed disorganized sarcomeres without Z-bands in the regions of indistinct striation, and no well-organized myofibrils in the regions where the sarcomeres had disappeared. Thus the well-organized myofibrils with Z-bands became transiently disorganized at least in some parts, during mitosis. They were then reorganized into daughter myocardial cells.     

Nucleotide sequence of the gene encoding the active-site serine β-lactamase from Streptomyces cacaoi

Abstract The gene encoding the extracellular active-site serine β-lactamase of Streptomyces cacaoi previously cloned into Streptomyces lividans , has the information for the synthesis of a 303 amino-acid precursor. The β-lactamase as excreted by the host S. lividans ML1, has a ragged amino-terminus, indicating either the presence of a leader peptidase of poor specificity or the action of an amino-peptidase. The deduced primary structure has been confirmed by amino acid sequencing of a 10-residue stretch at the amino terminus of the mature protein and an 8-residue stretch containing the active-site serine. The S. cacaoi β-lactamase is highly homologous with the class A β-lactamases of Streptomyces albus G and Staphylococcus aureus of known three-dimensional structure. Amino acid alignments show that the S. cacaoi β-lactamase essentially differs from these two latter enzymes by short insertions and deletions that do not affect the spatial disposition of the secondary structures.