Kinetic bacteriochlorophyll fluorometer

A pump and probe fluorometer with a laser diode as single light source has been constructed for measurement of fast induction and relaxation of the fluorescence yield in intact cells, chromatophores and isolated reaction centers of photosynthetic bacteria. The time resolution of the fluorometer is limited by the repetition time of the probing flashes to 20 μs. The apparatus offers high sensitivity, excellent performance and can become a versatile device for a range of demanding applications. Some of them are demonstrated here including fast and easy investigation of the (1) organization and redox state of the photosynthetic apparatus of the intact cells of different bacterial strains and mutants and (2) electron transfer reactions on donor and acceptor sides of isolated reaction centers. The compact design of the mechanics, optics, electronics, and data processing makes the device easy to use as outdoor instrument or to integrate into larger measuring systems.     

Induction of release of tumor necrosis factor and IL-6 from human mononuclear cells by Bacteroides strains

The role of anaerobic Gram-negative bacteria in inducing cytokines during mixed infections involving aerobic and anaerobic bacteria is relatively poorly defined. The purpose of this study was to establish whether or not intact Bacteroides fragilis and related species, isolated from severe infections and from the faeces of healthy persons are capable of releasing tumor necrosis factor (TNF) and IL-6 from human mononuclear cells and whole blood. The purified lipopolysaccharides of Bacteroides fragilis strain (No. 7), extracted by the aqueous phenol method from BHI cultures and from BHI culture supplemented with 5% horse serum, were also tested. TNF release was detected by the WEHI 164-dependent bioassay and IL-6 production by the B-9 cell-dependent bioassay. Heat-inactivated Bacteroides strains belonging to different species were able to induce TNF (1x10(1)-5x10(2) U/mL) and IL-6 (1x10(1)-5x10(5) pg/mL) release from human mononuclear cells. When whole blood was used, the production of TNF and IL-6 was more pronounced (very probably because of the presence of certain serum factors). The culturing conditions (the presence of 5% horse serum in the BHI broth) influenced the inducing activity of almost all strains tested. The isolated lipopolysaccharide of Bacteroides fragilis strain No. 7 proved to have a rough profile on PAGE. There were no differences in TNF and IL-6 induction when the lipopolysaccharides of the strain was cultured in BHI or in BHI supplemented with 5% horse serum. Bacteroides strains often outnumber Enterobacteriaceae in the faeces and in mixed infections, and their role in inducing and/or modulating the host response in septic shock should not be overlooked.     

BioDeepTime: A database of biodiversity time series for modern and fossil assemblages

Motivation

We have little understanding of how communities respond to varying magnitudes and rates of environmental perturbations across temporal scales. BioDeepTime harmonizes assemblage time series of presence and abundance data to help facilitate investigations of community dynamics across timescales and the response of communities to natural and anthropogenic stressors. BioDeepTime includes time series of terrestrial and aquatic assemblages of varying spatial and temporal grain and extent from the present-day to millions of years ago.

Main Types of Variables Included

BioDeepTime currently contains 7,437,847 taxon records from 10,062 assemblage time series, each with a minimum of 10 time steps. Age constraints, sampling method, environment and taxonomic scope are provided for each time series.

Spatial Location and Grain

The database includes 8752 unique sampling locations from freshwater, marine and terrestrial ecosystems. Spatial grain represented by individual samples varies from quadrats on the order of several cm² to grid cells of ~100 km².

Time Period and Grain

BioDeepTime in aggregate currently spans the last 451 million years, with the 10,062 modern and fossil assemblage time series ranging in extent from years to millions of years. The median extent of modern time series is 18.7 years and for fossil series is 54,872 years. Temporal grain, the time encompassed by individual samples, ranges from days to tens of thousands of years.

Major Taxa and Level of Measurement

The database contains information on 28,777 unique taxa with 4,769,789 records at the species level and another 271,218 records known to the genus level, including time series of benthic and planktonic foraminifera, coccolithophores, diatoms, ostracods, plants (pollen), radiolarians and other invertebrates and vertebrates. There are to date 7012 modern and 3050 fossil time series in BioDeepTime.

Software Format

SQLite, Comma-separated values.     

Hormonal control of lipase activity in oilseed rape germinants

In oilseeds, storage lipids provide the respiratory fuel for seedling growth. The enzyme responsible for their initial hydrolysis is lipase (triacylglycerol acylhydrolase; EC 3.1.1.3). We investigated the possibility that lipase is regulated by gibberellins (GAs). In four oilseed rape cultivars of Brassica napus and B. rapa, seed imbibition in 10^?6 to 10^?3M GA₃ increased lipase activity 1.5- to 7-fold over control levels. Conversely, imbibition in 10^?7 to 10^?5M abscisic acid or 10^?6 to 10^?4M paclobutrazol, an inhibitor of GA biosynthesis, markedly decreased lipase activity. While lipase activity in B. napus cv. Parkland increased during the first 5 days following imbibition, concentrations of endogenous GA₁, GA₈ and GA₁₉ (as measured by GC-selected ion monitoring using [²H₂]GA internal standards) were relatively constant and GA₂₀, a precursor of GA₁, decreased. Levels of endogenous GA₃ were apparently variable. Thus, lipase activity was not correlated with GA₁ concentration, but the inverse correlation with GA₂₀ concentration suggests that GA turnover could be positively correlated with lipase activity. Lipase activity was also examined in three genotypes of rapid cycling B. rapa that vary in endogenous GA content: rosette, a GA-deficient dwarf, a normal line and elongated internode, a tall mutant with high GA content. The three genotypes showed similar patterns of lipase activity during the first 4 days following imbibition and the subcellular distribution of lipase activity was also similar in the three genotypes. Although GA may be involved in the regulation of lipase in oilseed rape germinants, it is not the sole regulatory factor.     

Different patterns of retinal cone topography in two genera of rodents,Mus and Apodemus

Recently, we have reported the peculiar topographic separation of shortwave- and middlewave-sensitive (S and M) cones in the retina of the common house mouse (Mus musculus) and in a number of inbred laboratory mouse strains derived from the same species. In an attempt to follow the phylogeny of the complementary cone fields, we have investigated the retina of other mouse-like rodents. Two monoclonal anti-visual pigment antibodies, OS-2 and COS-1, specific to the S and M cones, respectively, have been used to identify the two cone types. Immunocytochemistry on retinal sections and on whole-mount preparations have shown that, as in the house mouse, the two cone types in the mound builder mouse (Mus spicileugus) occupy opposite halves of the retina. In contrast, in the wood mouse (Apodemus sylvaticus), both cone types are scattered uniformly across the whole retinal surface. Another distinguishing feature between the two genera is the frequency of the S cones. Whereas their density in the Mus species is above 7 000/mm² in the S-field, the maximum density of the S cones in A. sylvaticus is one order of magnitude smaller. In another species of this genus (the herb field mouse, A. microps), the S cones are completely missing.     

Interaction of a synthetic polyanion with rat liver mitochondria

The effect of a polyanion (a copolymer of methacrylate, malaete and styrene in a 1:2:3 proportion with an average molecular weight of 10 000) on respiration, ATPase activity and ADP/ATP exchange activity of rat liver mitochondria and submitochondrial particles has been studied.The polyanion (at 17–150 μg/ml concentration, 100 μg polyanion corresponding to 0.83 μequiv. of carboxylic groups) inhibits the oxidation of succinate and NAD-linked substrates in state 3 in a concentration-dependent manner. The extent of this inhibition can be decreased by elevating the concentration of ADP. State 4 respiration is not affected by the polyanion. It has also a slight inhibitory effect on the oxidation of the above mentioned substrates in the uncoupled state (a maximum inhibition of 37% at 166 μg/ml polyanion concentration), which is unaffected by ADP. The strong inhibition of state 3 respiration can be relieved by 2,4-dinitrophenol to the low level observed in the uncoupled state. Ascorbate+TMPD oxidation is slightly inhibited in state 3, while it is not inhibited at all in the uncoupled state.The polyanion, depending on its concentration, strongly inhibits also the DNP-activated ATPase activity of mitochondria (50% inhibition at 40 μg/ml polyanion concentration).The ATPase activity of sonic submitochondrial particles is also inhibited. However, this inhibition is incomplete (reaching a maximum of 65%) and higher concentrations of the polyanion are required than to inhibit the ATPase activity of intact mitochondria.The polyanion inhibits the ADP/ATP translocator activity of mitochondria, measured by the “back exchange” of [2-³H]ADP. After a short preincubation of the mitochondria with the polyanion, the concentration dependence of the inhibition by the polyanion corresponds to that of the DNP-activated ATPase activity of intact mitochondria.It is concluded that, in intact mitochondria, the polyanion has at least a dual effect, i.e. it partially inhibits the respiratory chain between cytochrome b and cytochrome c, and strongly oxidative phosphorylation by blocking the ADP/ATP translocator.     

Presence of Cx37 and lack of desmin in smooth muscle cells are early markers for arteriogenesis

In search of early structural markers of arteriogenesis, we studied the expression of gap junction proteins as well as of contractile and cytoskeletal proteins in smooth muscle cells (SMCs) during coronary collateral vessel growth induced by chronic occlusion of the left circumflex artery (LCx) in the dog heart. We used confocal microscopy with antibodies against connexin37 (Cx37), alpha-smooth muscle actin (alpha-SM actin), calponin, desmin and vinculin. The quantitative confocal analysis of immunofluorescence intensity showed that (1) in normal vessels (NV), Cx37 was present in endothelium only, not in SMC. Calponin, alpha-SM actin, desmin and vinculin were evenly expressed in SMC. (2) In early growing V (EV) with minimal intima formation, alpha-SM actin, calponin and vinculin showed little change in SMC, but desmin was 3.3 times lower than in NV, and Cx37 was induced (NV 0 arbitrary units/microm2, EV 50.3). (3) In actively growing V (AV), alpha-SM actin, calponin and vinculin were 3-, 3.3- and 2.9-fold lower, respectively, in the neointima as compared to the media. However, Cx37 was 48.2 AU/microm2 in the media and 15.8 AU/microm2 in the neointima. Desmin was almost absent in the neointima and 5-fold reduced in the media. SMC, strongly positive for alpha-SM actin and calponin, expressed Cx37. Our findings indicate that induction of Cx37 and reduction of desmin precede the phenotypic changes of SMCs, which are characterized by down-regulation of alpha-SM actin, calponin and vinculin, and the formation of a neointima. An altered expression of Cx37 and desmin, therefore, are early markers for arteriogenesis in dog heart.     

Yersinia Yop-Specific IgA antibodies in Hungarian blood donors

Sera of 112 healthy Hungarian blood donors were tested for the presence of Yersinia enterocolitica and Y. pseudotuberculosis-specific agglutinins by tube agglutination, and for that of yersinia outer membrane protein (Yop)-specific IgA antibodies by ELISA. The positive results of this latter assay were confirmed by immunoblot. Only one sample gave a positive agglutination reaction with Y. enterocolitica antigen (group 03) and four exhibited an equivocal reaction with Y. pseudotuberculosis antigens (groups II and IV). Contrary to the low incidence of agglutinins, 15.1% of the samples showed a positive Yop-specific IgA reaction, while further 5.3% samples fell into the equivocal range by ELISA (17 and 6 specimens, respectively). Eleven of these samples (9.8% of all specimens tested) were also positive by immunoblot for the presence of Yop-specific IgA antibodies. These data suggest a higher incidence of yersinia infections than the 1.0-1.4 per 10(5) population predicted on the basis of stool culture results.     

Remyelination of spinal cord axons by olfactory ensheathing cells and Schwann cells derived from a transgenic rat expressing alkaline phosphatase marker gene

Transplantation of cell suspensions containing olfactory ensheathing cells (OECs) has been reported to remyelinate demyelinated axons in the spinal cord with a Schwann cell (SC)-like pattern of myelination. However, questions have been raised recently as to whether OECs can form SC-like myelin. To address this issue we prepared SCs and OECs from transgenic rats in which a marker gene, human placental alkaline phosphatase (hPAP), is linked to the ubiquitously active promoter of the R26 gene. SCs were prepared from the sciatic nerve and OECs from the outer nerve-fiber layer of the olfactory bulb. Positive S100 and p75 immunostaining indicated that >95% of cells in culture displayed either SC or OEC phenotypes. Suspensions of either SCs or OECs were transplanted into an X-irradiation/ethidium bromide demyelinating lesion in the spinal cord. We observed extensive SC-like remyelination following either SC or OEC transplantation 3 weeks after injection of the cells. Alkaline phosphatase (ALP) chromagen reaction product was associated clearly with the myelin-forming cells. Thus, cell suspensions that are enriched in either SCs or OECs result in peripheral-like myelin when transplanted in vivo.