Not dead yet: Diatom resting spores can survive in nature for several millennia

PREMISE

Understanding the adaptive capacities of species over long timescales lies in examining the revived recent and millennia-old resting spores buried in sediments. We show for the first time the revival, viability, and germination rate of resting spores of the diatom Chaetoceros deposited in sub-seafloor sediments from three ages (recent: 0 to 80 years; ancient: ~1250 (Medieval Climate Anomaly) and ~6600 (Holocene Thermal Maximum) calendar year before present.

METHODS

Recent and ancient Chaetoceros spores were revived to examine their viability and germination rate. Light and scanning electron microscopy and Sanger sequencing was done to identify the species.

RESULTS

We show that ~6600 cal. year BP old Chaetoceros resting spores are still viable and that the vegetative reproduction in recent and ancient resting spores varies. The time taken to germinate is three hours to 2 to 3 days in both recent and ancient spores, but the germination rate of the spores decreased with increasing age. The germination rate of the recent spores was ~41% while that of the ancient spores were ~31% and ~12% for the ~1250 and ~6600 cal. year BP old resting spores, respectively. Based on the morphology of the germinated vegetative cells we identified the species as Chaetoceros muelleri var. subsalsum. Sanger sequences of nuclear and chloroplast markers identified the species as Chaetoceros muelleri.

CONCLUSIONS

We identify a unique model system, Chaetoceros muelleri var. subsalsum and show that recent and ancient resting spores of the species buried in sediments in the Baltic Sea can be revived and used for long-term evolutionary studies.

Polycyclic aromatic hydrocarbons in the Baltic Sea - Pre-industrial and industrial developments as well as current status

We report on Baltic Sea polycyclic aromatic hydrocarbon (PAH) pressure based on the U.S. EPA PAHs in view of millennial and decadal developments utilizing data from sediment deposits and seawater. Pre-industrial PAH contents ranged from 500 to 4500 ng/g TOC. Maximum PAH contents were up to 100,000 ng/g TOC and date back to the 1960s to 1970s with maximum pollutant inputs. Contemporary sediment PAH contents with 10,000 to 35,000 ng/g TOC and seawater concentrations with about 1 to 16 ng/l show spatial variability due to different local inputs and sediment characteristics. Pre-industrial compositional change from low molecular weight to high molecular weight (HMW) PAH indicates changing sources from mostly petroleum to combustion. Application of diagnostic ratios reveals petroleum and combustion as contemporary PAH sources and that traffic emissions continuously contribute to the Baltic PAH profile. Medium to high toxicological risk to the marine community might arise from current HMW PAH contents.

An oceanic perspective on Greenland's recent freshwater discharge since 1850

Instrumental data evidence an accelerating freshwater release from Arctic sea ice export and the Greenland Ice Sheet over the past three decades causing cooling and freshening in the subpolar North Atlantic region. However, evaluating the observed acceleration on a historical oceanic and climatic perspective remains challenging given the short available instrumental time series. Here we provide a marine perspective on the freshwater releases to the ocean since 1850 as reflected in the northern limb of the Subpolar Gyre. Our reconstructions suggest that the recent acceleration tracks back to the 1940s/50s and is unprecedented since 1850. The melting, initiated by the 1920s natural rise in solar irradiance, accelerated in response to a combined effect of natural and anthropogenic forcing factors. We find that Greenland’s freshwater discharge has contributed to a nutrient-driven fertilization of the upper ocean and consequently increased the marine primary productivity since the 1940s/50s.

Climate induced human demographic and cultural change in northern Europe during the mid-Holocene

The transition from hunter-gatherer-fisher groups to agrarian societies is arguably the most significant change in human prehistory. In the European plain there is evidence for fully developed agrarian societies by 7,500 cal. yr BP, yet a well-established agrarian society does not appear in the north until 6,000 cal. yr BP for unknown reasons. Here we show a sudden increase in summer temperature at 6,000 cal. yr BP in northern Europe using a well-dated, high resolution record of sea surface temperature (SST) from the Baltic Sea. This temperature rise resulted in hypoxic conditions across the entire Baltic sea as revealed by multiple sedimentary records and supported by marine ecosystem modeling. Comparison with summed probability distributions of radiocarbon dates from archaeological sites indicate that this temperature rise coincided with both the introduction of farming, and a dramatic population increase. The evidence supports the hypothesis that the boundary of farming rapidly extended north at 6,000 cal. yr BP because terrestrial conditions in a previously marginal region improved.

Size differences of Arctic marine protists between two climate periods-using the paleoecological record to assess the importance of within-species trait variation

Mean body size decreases with increasing temperature in a variety of organisms. This size-temperature relationship has generally been tested through space but rarely through time. We analyzed the sedimentary archive of dinoflagellate cysts in a sediment record taken from the West Greenland shelf and show that mean cell size decreased at both intra- and interspecific scales in a period of relatively warm temperatures, compared with a period of relatively cold temperatures. We further show that intraspecific changes accounted for more than 70% of the change in community mean size, whereas shifts in species composition only accounted for about 30% of the observed change. Literature values on size ranges and midpoints for individual taxa were in several cases not representative for the measured sizes, although changes in community mean size, calculated from literature values, did capture the direction of change. While the results show that intraspecific variation is necessary to accurately estimate the magnitude of change in protist community mean size, it may be possible to investigate general patterns, that is relative size differences, using interspecific-level estimates.

Echoes from the past: a healthy Baltic Sea requires more effort

Integrated sediment multiproxy studies and modeling were used to reconstruct past changes in the Baltic Sea ecosystem. Results of natural changes over the past 6000 years in the Baltic Sea ecosystem suggest that forecasted climate warming might enhance environmental problems of the Baltic Sea. Integrated modeling and sediment proxy studies reveal increased sea surface temperatures and expanded seafloor anoxia (in deep basins) during earlier natural warm climate phases, such as the Medieval Climate Anomaly. Under future IPCC scenarios of global warming, there is likely no improvement of bottom water conditions in the Baltic Sea. Thus, the measures already designed to produce a healthier Baltic Sea are insufficient in the long term. The interactions between climate change and anthropogenic impacts on the Baltic Sea should be considered in management, implementation of policy strategies in the Baltic Sea environmental issues, and adaptation to future climate change.

Application of magnetically induced hyperthermia in the model protozoan Crithidia fasciculata as a potential therapy against parasitic infections

Background

Magnetic hyperthermia is currently a clinical therapy approved in the European Union for treatment of tumor cells, and uses magnetic nanoparticles (MNPs) under time-varying magnetic fields (TVMFs). The same basic principle seems promising against trypanosomatids causing Chagas disease and sleeping sickness, given that the therapeutic drugs available have severe side effects and that there are drug-resistant strains. However, no applications of this strategy against protozoan-induced diseases have been reported so far. In the present study, Crithidia fasciculata, a widely used model for therapeutic strategies against pathogenic trypanosomatids, was targeted with Fe₃O₄ MNPs in order to provoke cell death remotely using TVMFs.

Methods

Iron oxide MNPs with average diameters of approximately 30 nm were synthesized by precipitation of FeSO₄ in basic medium. The MNPs were added to C. fasciculata choanomastigotes in the exponential phase and incubated overnight, removing excess MNPs using a DEAE-cellulose resin column. The amount of MNPs uploaded per cell was determined by magnetic measurement. The cells bearing MNPs were submitted to TVMFs using a homemade AC field applicator (f = 249 kHz, H = 13 kA/m), and the temperature variation during the experiments was measured. Scanning electron microscopy was used to assess morphological changes after the TVMF experiments. Cell viability was analyzed using an MTT colorimetric assay and flow cytometry.

Results

MNPs were incorporated into the cells, with no noticeable cytotoxicity. When a TVMF was applied to cells bearing MNPs, massive cell death was induced via a nonapoptotic mechanism. No effects were observed by applying TVMF to control cells not loaded with MNPs. No macroscopic rise in temperature was observed in the extracellular medium during the experiments.

Conclusion

As a proof of principle, these data indicate that intracellular hyperthermia is a suitable technology to induce death of protozoan parasites bearing MNPs. These findings expand the possibilities for new therapeutic strategies combating parasitic infection.

Functionalized Fe₃O₄@Au superparamagnetic nanoparticles: in vitro bioactivity

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe₃O₄@Au nanoparticles functionalized with biocompatible and fluorescent molecules and their interaction with cell cultures by visualizing them with confocal microscopy. Gold covered iron oxide nanoparticles were synthesized by reducing metal salts in the presence of oleylamine and oleic acid. The functionalization of these particles with an amphiphilic polymer provides a water soluble corona as well as the possibility to incorporate different molecules relevant for bio-applications such as poly(ethylene glycol), glucose or a cadaverine derived dye. The particle size, and the presence of polymer layers and conjugated molecules were characterized and confirmed by transmission electron microscopy, thermogravimetric measurements and infrared spectroscopy. A complete magnetic study was performed, showing that gold provides an optimum coating, which enhances the superparamagnetic behaviour observed above 10-15 K in this kind of nanoparticle. The interaction with cells and the cytotoxicity of the Fe₃O₄@Au preparations were determined upon incubation with the HeLa cell line. These nanoparticles showed no cytotoxicity when evaluated by the MTT assay and it was demonstrated that nanoparticles clearly interacted with the cells, showing a higher level of accumulation in the cells for glucose conjugated nanoparticles.

[Nephrotic syndrome associated with symmetrical multiple lipomatosis (Madelung's disease)]

We present a case of multiple symmetric lipomatosis Type I (Madelung's disease) with severe organic affection, hepatic cirrhosis, sever sensitive polyneuropathy and neuropathic ulceration at the left lower limb. A nephrotic syndrome developed in a larval form due to proliferative glomerulonephritis as the result of a metainfectious complications of the infection at the lower limb. We discuss the etiopathogenicity of the organic affection and we highlight the pathogenic links between the disease and its complications.

Comparative in vitro and in vivo activities of six new monofluoroquinolone and difluoroquinolone 3-carboxylic acids with a 7-azetidin ring substituent

E-4502, E-4501, E-4500, E-4480, E-4474, and E-4441 are new monofluorinated or difluorinated quinolone agents that are chemically characterized by the presence of an azetidin ring, with different C'-3 substituents, at position 7 of the molecular structure. The MICs of the difluorinated compounds E-4501, E-4474, and E-4441 for 90% of isolates were 0.06 to 1, 0.06 to 1, and 0.12 to 1 microgram/ml, respectively, against gram-positive organisms (staphylococci, streptococci, and Enterococcus faecalis); 0.0015 to 0.12, 0.015 to 0.12, and 0.03 to 0.12 microgram/ml, respectively, against members of the family Enterobacteriaceae except Providencia spp.; and 1, 1, and 2 micrograms/ml, respectively, against Pseudomonas aeruginosa. E-4501, E-4474, and E-4441 inhibited all anaerobic bacteria at concentrations of 1, 2, and 4 micrograms/ml, respectively. Difluorinated compounds were significantly more active than the corresponding monofluorinated analogs E-4502, E-4500, and E-4480 against aerobic and facultatively anaerobic organisms, as well as against anaerobes. Considering monofluorinated and difluorinated compounds, activity in moderate ascending order was observed in quinolones containing an amine and a methyl group (E-4441 and E-4480), an amine group (E-4474 and E-4500), and a methylamine group (E-4501 and E-4502) in the C'-3 position of the azetidin ring. E-4501, E-4474, and E-4441 were more active than norfloxacin and DR-3355 [S-(-)-ofloxacin], had activities comparable to or slightly lower than that of ciprofloxacin against gram-negative bacteria, and were more active than all the reference quinolones against gram-positive organisms and anaerobes. E-4502 and E-4501, which were used to determine the effect of pH, were less active in acidic medium. In general, E-4502, E-4501, E-4500, E-4480, E-4474, and E-4441 activities were not affected or increased in medium containing serum but decreased in the presence of 10 mM Mg2+ or in human urine at pH 5.5. The protective effect of E-4501, E-4474, and E-4441 after oral administration against systemic infections with Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa in mice was greater than that of ciprofloxacin.

Activity of E-3846, a new fluoroquinolone, in vitro and in experimental cystitis and pyelonephritis in rats

The in vitro antibacterial activity of E-3846, a new fluoroquinolone carboxylic acid derivative with a pyrrol ring substituent at position 7, was evaluated in comparison with norfloxacin and ciprofloxacin. E-3846 was more active than the reference quinolones against Staphylococcus species, including methicillin-resistant strains. E-3846 was similar to ciprofloxacin and more active than norfloxacin against Streptococcus (Enterococcus) faecalis. In general, E-3846 was more active than norfloxacin against members of the family Enterobacteriaceae, but less active than ciprofloxacin. For Pseudomonas aeruginosa, the MICs giving 90% inhibition for E-3846, norfloxacin, and ciprofloxacin were 2, 1, and 0.25 micrograms/ml, respectively. The activity of E-3846 increased at acid pH; in contrast, acid pH caused a pronounced decrease in the activity of norfloxacin and ciprofloxacin. In vivo, E-3846 demonstrated excellent therapeutic efficacy in treating experimental S. faecalis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa cystitis and pyelonephritis in rats.

Muscular structural changes following fadenoperation

The authors describe the macroscopic, histological, and ultrastructural findings observed in an experimental animal model of the fadenoperation . Grossly, muscular fibrosis and musculo-scleral adhesions were well established after the second postoperative month. Histologic findings demonstrated the development of a granulomatous, foreign body reaction around the musculo-scleral fixation suture, collagenization of the muscle tissue from the first postoperative month and degenerative phenomena in the muscle fibers. Electron transmission microscopic study showed atrophy and angulation with distortion of the myofibrillar matrix, along with alteration of the Z bands of muscle fibers, mitochondrial alteration, and dilatation of the sarcotubular system. All these experimental findings suggest the relative irreversible effects of the fadenoperation after the early postoperative period and for the first time, demonstrated that this surgical technique alters the muscle structure.