Effects of water regime on archaeal community composition in Arctic soils

Effects of water regime on archaeal communities in Arctic soils from Spitsbergen were studied using denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA genes, with subsequent sequencing of amplicons and ordination analysis of binary DGGE data. Samples with major differences in soil water regime showed significant differences in their archaeal community profiles. Methanomicrobiales, Methanobacteriaceae and Methanosaeta were detectable only in environments that were wet during most of the growth season, while a novel euryarchaeotal cluster was detected only in less reduced solifluction material. Group 1.3b of Crenarchaeota had a high relative abundance within the archaeal community in a wide range of wet soils. Along a natural soil moisture gradient, changes in archaeal community composition were observed only in upper soil layers. The results indicated that members of Methanomicrobiales were relatively tolerant to soil aeration. Differences in archaeal community composition associated with soil water regime were predominant over regional and seasonal variation, and over differences between individual wetlands. The results suggest that the observed 'on-off switch' mechanism of soil hydrology for large-scale variations in methane emissions from northern wetlands is at least partly caused by differences in the community structure of organisms involved in methane production.     

Monosaccharides and monosaccharide derivatives in human seminal plasma

Gas chromatography—mass spectrometry with an on-line data system was used to identify monosaccharides and monosaccharide derivatives in human seminal plasma. The carbohydrates were converted into the methoxime—trimethylsilyl derivatives before separation in open tubular glass capillary columns coated with SE-30. Twenty-one different compounds were detected in the seminal fluid, of which twelve have not been recognized before. Seventeen of the monosaccharides have previously been identified in urine. Similar patterns of sugars were found both in fertile and infertile individuals, including one with azoospermia. The compounds identified are, with the possible exception of -ribose, present as free monosaccharides at the time of ejaculation, and they do not seem to be preformed by spermatozoa.     

Cellular activation,phagocytosis, and bactericidal activity against group B streptococcus involve parallel myeloid differentiation factor 88-dependent and independent signaling pathways

Group B streptococci (GBS) vigorously activate inflammatory responses. We reported previously that a secreted GBS "factor" activates phagocytes via Toll-like receptor (TLR)2 and TLR6, but that GBS cell walls activate cells independently of these receptors. We hypothesized that the phagocytic immune functions in response to GBS, such as inflammation, uptake, and elimination of bacteria, occur through a coordinated engagement of TLRs, along with the coreceptors CD14 and CD11b/CD18. Using various knockout mice we show that GBS-induced activation of p38 and NF-kappaB depends upon the expression of the cytoplasmic TLR adapter protein, myeloid differentiation factor 88 (MyD88), but not TLR2 and/or TLR4. Macrophages with deletions of CD14 and complement receptor 3 had a normal cytokine response to whole bacteria, although the response to GBS factor was abrogated in CD14-null cells. The intracellular formation of bactericidal oxygen species proved to be MyD88 dependent; however, uptake of GBS, a prerequisite for intracellular killing by O(2) radicals, occurred independently of MyD88. While deletion of complement receptor 3 greatly diminished the uptake of opsonized GBS, it did not affect the formation of bactericidal O(2) radicals or inflammatory signaling intermediates. We conclude that the inflammatory, bactericidal, and phagocytic responses to GBS occur via parallel but independent processes.     

Initial single-center experience with a new intracoronary stent

We investigated the safety and efficacy of the recently introduced intracoronary beStent(TM). High flexibility, zero shortening after expansion and delineating gold markers at either end of the stent are favorable features of this device. Between July 1996 and February 1997, 117 patients received a total of 126 stents, measuring 15, 25 and 35 mm in length. The majority of lesions were located in the LAD (n = 48; 38%), followed by lesions in the RCA (n = 41; 33%) and the circumflex artery (n = 28; 22%). Nine additional stents were delivered into vein grafts (7%). Successful stent deployment was achieved in 94% (n = 118), even in cases with complex lesion morphology and angulated segments. The markers proved to be helpful in placing the stent close to side-branches and whenever serial stents were used. Complications during hospitalization were as follows: one cardiac death unrelated to stenting, one subacute stent thrombosis after 30 min of effective anticoagulation and one Q-wave myocardial infarction due to peripheral thrombus embolization after stent placement in a vein graft. One patient was sent for elective CABG after an unsatisfactory procedural result. Stent loss occurred in four patients, and all stents could be retrieved successfully; in another four patients stent placement at the target site was impossible. We conclude that the investigated stent demonstrates several favorable stent characteristics which have proved to be useful in treating complex lesions by providing favorable acute results with a low complication rate.     

Retinoylation of proteins in a macrophage tumor cell line J774, following uptake of chylomicron remnant retinyl ester

Following uptake of chylomicron remnant retinyl esters by the macrophage cell line J774, the retinyl esters are hydrolyzed to retinol before retinol is further metabolized to retinal and the various retinoic acid isoforms. One hour after the addition of chylomicron remnant [³H]retinyl esters to the cells, the percentage of cell-associated radioactivity in the retinyl ester fraction had decreased from approximately 90% to approximately 40%, whereas the radioactivity in the retinol fraction increased correspondingly. After 4 hours of incubation, more than 79% of the radioactive retinyl esters had been hydrolyzed to retinol. When we measured incorporation of radioactivity in the protein fraction, we observed that the level of [³H]retinoylated proteins increased rapidly the first 4 hours, and then continued to increase at a lower rate up to 24 hours, when approximately 0.6% of the cell-associated radioactivity was covalently bound to protein. These data suggest that approximately 0.18% of all the cellular proteins might be retinoylated under such conditions. In summary, in the present study we have demonstrated that retinoids taken up by a macrophage cell line as chylomicron remnant retinyl esters, a physiologic plasma transport molecule for vitamin A, might be covalently linked to proteins. Such retinoylation might be relevant both for normal function, as well as for the toxic and teratogenic effects of vitamin A.     

BIO-OPTICAL CHARACTERISTICS AND PHOTOADAPTIVE RESPONSES IN THE TOXIC AND BLOOM-FORMING DINOFLAGELLATES GYRODINIUM AUREOLUM,GYMNODINIUM GALATHEANUM,AND TWO STRAINS OF PROROCENTRUM MINIMUM1

Photoadaptive responses in the toxic and bloom-forming dinoflagellates Gyrodinium aureolum Hulbert, Gymnodinium galatheanum Braarud, and two strains of Prorocentrum minimum (Pavillard)Schiller were evaluated with respect to pigment composition, light-harvesting characteristics, carbon and nitrogen contents, and growth rates in shade- and light-adapted cells. The two former species were grown at scalar irradiances of 30 and 170 μmol · m ^?2 at a 12-h daylength at 20° C. The two strains of P. minimum were grown at 35 and 500 μmol. m^?2· s^?1 at a 2-h daylength at 20° C. For the first time, chlorophyll (chl) c₃, characteristic of several bloom-forming prymnesiophytes, was detected in G. aureolum and G. galatheanum. Photoadaptional status affected the pigment composition strongly, and the interpretation of the variation depended on whether the pigment composition was normalized per cell, carbon, or chl a. Species-specific and photoadaptional differences in chl a-specific absorption (°a_c, 400–700 nm) and chl a-normalized fluorescence excitation spectra of photosystem II fluorescence with or without addition of DCMU (°F and °F_DCMU 400–700 nm) were evident. Gyrodinium aureolum and G. galatheanum exhibited in vivo spectral characteristics similar to chl c₃-containing prymnesiophytes in accordance with their similar pigmentation. Prorocentrum minimum had in vivo absorption and fluorescence characteristics typical for peridinin-containing dinoflagellates. Species-specific differences in in vivo absorption were also observed as a function of package effect vs. growth irradiance. This effect could be explained by differences in intracellular pigment content, cell size/shape, and chloroplast morphology/numbers. Light- and shade-adapted cells of P. minimum contained 43 and 17% of photoprotective carotenoids (diadino + diatoxanthin) relative to chl a, respectively. The photoprotective function of these carotenoids was clearly observed as a reduction in °F and °F ^DCMU at 400–540 nm compared to °ac in light-adapted cells of P. minimum. Spectrally weighted light absorption (normalized to chl a and carbon, 400–700 nm) varied with species and growth conditions. The use of quantum-corrected and normalized fluorescence excitation spectra with or without DCMU-treated cells to estimate photosynthetically usable light is discussed. The usefulness of in vitro absorption and fluorescence excitation spectra for estimation of the degradation status of chl a and the ratio of chl a to total pigments is also discussed.     

Peptide nucleic acid (PNA): A model structure for the primordial genetic material?

It is proposed that the primordial genetic material could have been peptide nucleic aicds,i.e., DNA analogues having a peptide backbone. PNA momomers based on the amino acid, , -diaminobutyric acid or ornithine are suggested as compounds that could have been formed in the prebiotic soup. Finally, the possibility of a PNA/RNA world is presented, in which PNA constitutes the stable genetic material, while RNA which may be polymerized using the PNA as template accounts for enzymatic activities including PNA replication.     

Investigation of the metabolic pattern in maple syrup urine disease by means of glass capillary gas chromatography and mass spectrometry

Urine and serum from patients with maple syrup urine disease (MSUD) have been examined quantitatively and qualitatively using glass capillary gas chromatography in combination with mass spectrometry. During clinical episodes, patients with this disease were found to excrete increased amounts of the following metabolites in addition to the previously recognized branched-chain 2-keto and 2-hydroxy acids, lactate and 3-hydroxybutyrate; 2-hydroxybutyrate, 2-hydroxyisobutyrate, 3-hydroxyisovalerate, 3-hydroxylsobutyrate and 2-methyl-3-hydroxybutyrate. Most of the latter compounds seem to accompany ketoacidosis and lactic acidosis. The capillary column also separated the d- and l-forms of 2-keto-3-methylvalerate, and both isomers were, in contrast to earlier assumptions, present in the MSUD patients. The results clearly demonstrate that new information on the metabolic situation in well known disorders may be obtained by exploiting the high resolving power of capillary columns.     

Structural studies of the polysaccharide from Aloe plicatilis Miller

The interior part of the leaves of the succulent Aloe plicatilis Miller (Liliaceae) consists of a transparent jelly containing mainly an acetylated glucomannan. Structural studies show that glucose and mannose, which are present in the ratio 1:2.8, are (1 → 4)-linked and that there is no branching. The hexose residues are randomly and variously substituted at positions 2,3,6, 2,3, 2, and 3 with acetyl groups; a small proportion of the sugar units is unsubstituted.