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At least 19 recordsLinked to original sources
PubMed1977

Isolation and characterization of gas vesicles from Microcyclus aquaticus.

Intact gas vesicles of Microcyclus aquaticus S1 were isolated by using centrifugally accelerated flotation of vesicles and molecular sieve chromatography. Isolated gas vesicles were cylindrical organelles with biconical ends and measured 250x100nm. The gas vesicle membrane was composed almost entirely of protein; neither lipid nor carbohydrate was detected, although one mole of phosphate per mole of protein was found. Amino acid analysis indicated that the protein contained 54.6% hydrophobic amino acid residues, lacked sulfur-containing amino acids, and had a low aromatic amino acid content. The protein subunit composition of the vesicles was determined by gel electrophoresis in (i) 0.1% sodium dodecyl sulfate at pH 9.0 and (ii) 5 M urea at pH 2.0. The membrane appeared to consist of one protein subunit of MW 50000 daltons. Charge isomers of this subunit were not detected on urea gels. Antiserum prepared against purified gas vesicles of M. aquaticus S1 crossreacted with the gas vesicles of all other gas vacuolate strains of M. aquaticus, as well as those of Prosthecomicrobium pneumaticum, Nostoc muscorum, and Anabaena flos-aquae, indicating that the gas vesicles of these widely divergent organisms have some antigenic determinants in common.

Amino Acids↗
PubMed1977

Inhibition of gas vesicle production in Microcyclus aquaticus by L-lysine.

The timing and degree of gas vesicle production in Microcyclus aquaticus was affected by nutritional conditions. If 50 microng L-lysine/ml was added to a glucose-mineral salts medium (DM), the organism did not form gas vesicles. This effect was specific for L-lysine, as neither D-lysine nor meso-diaminopimelic acid prevented gas vesicle production. Cells grown in the presence of L-lysine did not contain any immunologically detectable gas vesicle protein, which indicates that L-lysine affects expression of the structural gene for the gas vesicle protein rather than assembly of the protein into gas vesicles. The addition of L-lysine to cultures in DM did not immediately decrease the rate of gas vesicle assembly, nor did the removal of cells from DM plus L-lysine to DM result in immediate gas vesicle production. Gas vesicle production was also affected by the addition of L-threonine or L-cysteine to culture media or by an increase in the medium's ionic strength. These results are discussed in relation to the aspartic acid pathway of amino acid biosynthesis and effects upon the intracellular L-lysine concentration.

Amino Acids↗
PubMed1975

Gas vesicle assembly in Microcyclus aquaticus.

When observed in the electron microscope intact gas vesicles appeared as transparent areas in whole cells of Microcylus aquaticus, whereas vesicles collapsed by centrifugation were not discernible. Within 5 min of suspending cells containing collapsed vesicles in growth medium, small transparent vesicles were detected. By 15 min the average number of vesicles per cell was 15. This number remained relatively constant while the size of the vesicles increased until they attained their maximum diamtere of 100 nm. At this time the vesicles, interpreted as biconical structures, began to elongate presumably due to the synthesis of the cylindrical midsection. Closely correlated with the time at which vesicles began to elongate was the initiation of smaller vesicles which resulted in a doubling of the number of vesicles per cell by 90 min. This evidence coupled with the isolation of a mutant which assembles only the conical portions of the vesicle suggests that assembly occurs in two distinct stages subject to genetic mutation. Protein and ribonucleic acid synthesis, and presumably adenosine triphosphate formation, were required for gas vesicle assembly. In addition, inhibition of protein or ribonucleic acid synthesis resulted in a loss of extant gas vesicles. Over the time course of our study, deoxyribonucleic acid synthesis was not required for gas vesicle assembly or stability.

Bacteria↗
PubMed2026

Ultrasound-driven mechanophore activation in living plants.

This study presents a biocompatible, ultrasound-responsive platform for remotely activating mechanochemical reactions within live plant tissue. Fluorogenic Mechanophore-embedded silica NanoParticles (FMNPs) that are thermally stable were engineered to emit blue fluorescence at 440 nm upon mechanical activation. In Solanum lycopersicum (tomato) leaves, activation was achieved through the synergistic combination of gas vesicles (GVs) and high-frequency focused ultrasound (FUS, 550 kHz), enabling spatially localized and minimally invasive stimulation. Low-frequency ultrasound (25 kHz) triggered activation but caused extensive tissue damage, while high-frequency FUS alone was biocompatible yet insufficient to activate FMNPs. Incorporation of GVs as a cavitation amplifier significantly boosted activation efficiency under mild acoustic conditions without observable tissue disruption. In planta fluorescence imaging confirmed that FMNPs retained their functionality after injection into leaf vasculature, and only the combination of GV and FUS produced a statistically significant fluorescence increase, indicating successful mechanochemical activation. This represents a demonstration of noninvasive and biocompatible ultrasound-induced mechanophore activation in live plants. This modular and noninvasive strategy opens possibilities for programmable release of regulatory and metabolic chemicals, biosensing, and synthetic molecular control in plant systems.

Plant Leaves↗
PubMed1979

The ultrastructure of Spirulina platensis in relation to temperature and light intensity.

The ultrastructure of Spirulina platensis, a cyanobacterium with a helical morphology, has been studied in relation to temperature and light intensity. An increase in temperature gives rise to a more tightly coiled trichome, an increase in sheath material formation and a decrease in cyanophycin (above 17 degrees C) and polyglucan (above 20 degrees C) granule concentration. An increase in light intensity leads to an increase in gas vesicle concentration while the phycobilisome content decreases. Furthermore, cylindrica bodies have been observed with a somewhat different ultrastructure from those found in other species of cyanobacteria. The occurrence, size and ultrastructure of polyhedral bodies, photosynthetic lamellae, mesosomes, lipid deposits and an unknown kidney-shaped inclusion in relation to temperature and light intensity are described.

Cell Wall↗
PubMed2026

Gloeotrichia echinulata genomes from the United States are nontoxigenic and likely geosmin producers.

Six Gloeotrichia echinulata genomes derived from planktonic harmful algal blooms (HABs) with similar colonial morphology have been sequenced from lakes in the west and northeast regions of USA, four of them to completion. The c. 7 Mbp genomes exhibit a high level of conservation, with 98-99% pairwise genome-wide average nucleotide identity and high levels of synteny, representing a single species cluster. We observed strong conservation of gene clusters responsible for the synthesis of the secondary metabolites and bioactive peptides that are characteristic of HAB-forming cyanobacteria. All six G. echinulata genomes lack genes for the synthesis of classic cyanotoxins, including microcystin, but possess genes responsible for the synthesis of the taste and odor compound geosmin. Interestingly, the geoA geosmin synthase gene in three genomes is homologous to other cyanobacterial geoA genes, while the other three geoA genes are related to actinomyces geoA. Phylogenomic analysis places the G. echinulata genomes within a clade of benthic Nostocales, reflecting an ecological niche featuring extensive growth on the sediment surface before colonies disperse into the epilimnion for planktonic growth. We identify genes conserved in all six genomes that could represent physiological adaptations supporting active growth on sediments and pelagic recruitment independent of wind-driven mixing: phycoerythrin light harvesting complexes for optimal photosynthesis at depth; gliding motility to access patchy nutrient distributions; and gas vesicles with relatively small GvpC proteins that predict resistance to higher hydrostatic pressure. The strong genomic similarity across geographically distant populations suggests that G. echinulata in the United States is a tightly related non-toxigenic species group with predictable properties relevant to public health and drinking water management.

Cyanobacteria↗
PubMed1979

Simultaneous mass spectrometric measurement of prostaglandins E1 (PGE1) and PGE2 with a deuterated internal standard.

The use of (3,3,4,4-2H4)PGE2 as internal standard for the quantitative measurement of PGE1 by gas chromatography-mass spectrometry is reported. A method for the simultaneous analysis of PGE1 and PGE2 is also described. The prostaglandins were analyzed by selected ion monitoring as the methyl ester-trimethylsilyl ether (ME-TMS) derivatives of PGB1 and PGB2, respectively. In all cases, a linear response over the range 1 to 70 ng (2.8 to 198 pmoles) was demonstrated. The use of this procedure is exemplified by its application to the PG analysis of sheep seminal vesicles.

Chromatography, Gas↗
PubMed1975

Demonstration and partial characterization of cytosol receptors for testosterone.

Androgen uptake was investigated in several peripheral organs after administration of (1,2,6,7 minus -3H)testosterone to castrated male rats. The animals were killed after 30 min, the organs were taken out, and the radioactivity was determined after tissue combustion. A relatively high accumulation of androgen was found in pancreas, adrenals, spleen, thigh muscle, kidneys, and liver in addition to the classical androgen target organs coagulation glands, seminal vesicles, prostate, preputial glands, and harderian glands. In a second serier of experiments, nuclear and cytosol fractions were prepared from prostate, seminal vesicles, coagulation glands, preputial glands, spleen, submaxillary glands, kidneys, and pancreas from castrated male rats give (1,2,6,7 minus -3H)testosterone, and these fractions were then characterized by thin-layer and radio-gas chromatography with respect to their patterns of labeled steroids. Only prostate and seminal vesicles were found to contain significant amounts of nuclear 5alpha-(-3H)dihydrotestosterone. The major nuclear androgen was (-3H)testosterone that was the only detectable labeled steroid in coagulation glands, preputial glands, and spleen and that constituted 70% or more of the nuclear radioactivity in seminal vesicles, submaxillary glands, kidneys, and pancreas. These results indicate that testosterone itself may be the predominant active androgen principle in vivo in most androgen target organs and that conversion to 5alpha-dihydrotestosterone is generally not a prerequisite for androgen activity. Using an ultrasensitive micromodification of isoelectric focusing (cf. M. Katsumata and A. S. Goldman (1974), Biochem. Biophys. Acta 359, 112. It was possible to show that cytosol from kidney; submaxillary gland, thigh muscle, and levator ani muscle and nuclei from kidney and submaxillary gland contained androgen-binding proteins with pI's in the region 4.6-5.1 ("4.6 minus 5.1 Complex"). This complex also formed in vitro after incubation of (1,2,6,7 minus -3H)testosterone with cytosol from kidney and submaxillary gland. (1,2,6,7 minus -3H)Testosterone was bound with high affinity to receptor proteins in cytosol from both kidney, submaxillary gland, and thigh muscle with dissociation constants of 5.0 x 10 minus -12 M (kidney), 3.3 x 10 mi;nus -11 M and 4.1 x 10 minus -10 M (two types of binding sites, submaxillary gland), 2.4 x 10 minus -12 M (thigh muscle) and 1.9 x 10 minus -12 M (levator ani muscle). The number of binding sites was in all cases between 1 and 20 fmol/mg of protein. On the basis of these results the hypothesis is presented that a common class of testosterone receptors is present in most organs and that these receptors can be detected both in vivo and in vitro provided methods sensitive enough are utilized.

Animals↗
PubMed1978

Metabolism of thromboxane B2 in the monkey.

[3H8]Thromboxane B2 was biosynthesized and infused into an unanesthetized monkey. Several urinary metabolites were isolated and their structures elucidated using gas chromatography-mass spectrometry. In addition to the major urinary metabolite, dinor-thromboxane B2, a series of metabolites resulting from dehydrogenetion of the alcohol group at C-11 were identified: 11-dehydro-thromboxane B2, 11-dehydro-15-keto-13,14-dihydro-2,3-dinor-thromboxane B2, and 11-dehydro-15-keto-13,14-dihydro-19-carboxyl-2,3,4,5-tetranor-thromboxane B2. 6-(1,3-dihydroxypropyl)-7-hydroxy-10-oxo-3-pentadecaenoic acid was also identified. Three mono-O-ethylated metabolites were formed from thromboxane B2, which in this study was infused in an ethanolic solution. A small quantity of thromboxane B2 was excreted unchanged into the urine.

Animals↗
PubMed1977

Mass spectral characterization of 6-oxo-OGF.

The mass spectra of eleven derivatives are presented to provide structural support for the recently discovered prostaglandin, 6-oxo-PGF1alpha, which we have isolated from incubations of arachidonic acid with ram seminal vesicles or released during isolated perfusions of sensitized guinea pig lungs.

Animals↗
PubMed1979

Incorporation of inositol into intact red blood cells. II. Enhancement of gas transport in inositol hexaphosphate-loaded red blood cells.

The gas-transport function of red blood cells which have incorporated inositol hexaphosphate is significantly improved by fusion with effector-loaded lipid vesicles. "Right-shifts" of the O2-binding curves of inositol hexaphosphate-loaded red blood cells with half-saturation pressures at 37 degrees C up to 98 mmHg are observed. The transformation of 56% of the intracellular haemoglobin into the low affinity state corresponds to an optimum increase of the O2-release capacity of 270%. The CO2 transport is also correspondingly enhanced. The treated red blood cells show no inositol hexaphosphate depletion during a reasonable time.

Carbon Dioxide↗
PubMed1979

Preparation and biochemical properties of PGH3.

PGH3 was biosynthesised from all-cis-5,8,11,14,17-eicosapentaenoic acid (20:5 omega 3) by an acetone-pentane powder of ram seminal vesicles and its structure was confirmed by GLC-MS after its reduction to PGF 3 alpha. PGH3 was transformed by horse platelet microsomes to TXB3, and by aortic microsomes to delta 17-6-keto-PGF 1 alpha. The structures of these compounds were confirmed by GLC-MS.

Animals↗
PubMed1979

Metabolism of prostaglandin D2 in the monkey.

[3H7]Prostaglandin D2 was biosynthesized and infused into an unanesthetized monkey. The urinary metabolites were isolated and subsequently identified by gas chromatography-mass spectrometry. Two pathways of prostaglandin D2 metabolism were identified and resulted in metabolites with prostaglandin D (3-hydroxycyclopentanone) and prostaglandin F (cyclopentane-1,3-diol) ring structures. The major prostaglandin D ring metabolite was identified as 9,20-dihydroxy-11,15-dioxo-2,3-dinorprost-5-en-1-oic acid. Nine other prostaglandin D ring metabolites were identified reflecting various combinations of metabolism by beta and omega oxidation, 15 dehydrogenation, and 13-14 reduction. In greater abundance were those prostaglandin D2 metabolites which had the prostaglandin F ring structure. The major prostaglandin D2 metabolite which had the prostaglandin F ring structure was identified as 9,11,15-trihydroxy-2,3-dinorprosta-5,13-dien-1-oic acid (dinor prostaglandin F2 alpha). Nine other metabolites with the prostaglandin F ring structure were identified, including prostaglandin F2 alpha itself. These, for the most part, were the structural counterparts of the metabolites with the prostaglandin D ring. Since many prostaglandin D2 metabolites were found to be identical with the metabolites of prostaglandin F2 alpha, quantitative determinations of prostaglandin F ring metabolites may not be a specific indicator of prostaglandin F2 alpha biosynthesis. Likewise, data involving the measurement of a biological effect of prostaglandin D2 must be re-examined to account for the possible contribution of prostaglandin F2 alpha, a metabolite of prostaglandin D2, to the biological response.

Animals↗