Nucleomorph ribosomal DNA and telomere dynamics in chlorarachniophyte algae

Chlorarachniophytes are enigmatic marine unicellular algae that acquired photosynthesis by secondary endosymbiosis. Chlorarachniophytes are unusual in that the nucleus of the engulfed algal cell (a green alga) persists in a miniaturized form, termed a nucleomorph. The nucleomorph genome of the model chlorarachniophyte, Bigelowiella natans CCMP621, is 373 kilobase pairs (kbp) in size, the smallest nuclear genome characterized to date. The B. natans nucleomorph genome is composed of three chromosomes, each with canonical eukaryotic telomeres and sub-telomeric ribosomal DNA (rDNA) operons transcribed away from the chromosome end. Here we present the complete rDNA operon and telomeric region from the nucleomorph genome of Lotharella oceanica CCMP622, a newly characterized chlorarachniophyte strain with a genome ～610 kbp in size, significantly larger than all other known chlorarachniophytes. We show that the L. oceanica rDNA operon is in the opposite chromosomal orientation to that of B. natans. Furthermore, we determined the rDNA operon orientation of five additional chlorarachniophyte strains, the majority of which possess the same arrangement as L. oceanica, with the exception of Chlorarachnion reptans and those very closely related to B. natans. It is thus possible that the ancestral rDNA operon orientation of the chlorarachniophyte nucleomorph genome might have been the same as in the independently evolved, red algal-derived, nucleomorph genomes of cryptophytes. A U2 small nuclear RNA gene was found adjacent to the telomere in Gymnochlora stellata CCMP2057 and Chlorarachnion sp. CCMP2014. This feature may represent a useful evolutionary character for inferring the relationships among extant lineages.     

Host‐seeking activity and avian host preferences of mosquitoes associated with West Nile virus transmission in the northeastern U.S.A.

Mosquito host‐seeking activity was studied using a custom‐designed trap to explore: (1) at which time interval of the night adult mosquito abatement would be most effective, and (2) if there exists an avian‐specific host‐seeking preference. Overnight trials using traps baited with dry ice showed that Aedes taeniorhynchus (Wiedemann) was most active at dusk and was then captured throughout the night. In contrast, Culex spp. (Cx. pipiens (Linnaeus) and Cx. restuans (Theobald) delayed most activity until about two h after dusk and were then captured through the night. This pattern suggests that management activities directed at adult Culex spp. would be most effective if initiated well after sunset. Mosquito capture rates in traps baited with birds in net bags were significantly greater than those with empty net bags, indicating that mosquitoes were attracted to the birds and not incidentally being sucked in by the custom trap's strong fan motor (Wilcoxon matched‐pairs signed‐ranks test, n= 24, t= 30, p < 0.05). Regression analysis showed that bird weight influenced mosquito attraction (r²= 0.21, p= 0.02). Trials with paired traps that contained different native bird species showed that Gray Catbirds, Dumatella carolinensis, attracted more mosquitoes than the heavier Northern Cardinals, Cardinalis cardinalis (paired samples t‐test, t= 2.58, df= 7, p= 0.04). However, attractiveness did not differ substantially among bird species, and Gray Catbirds did not attract more mosquitoes than all other birds combined as a group. American Robins, Turdus migratorius (n = 4) were comparable in attractiveness to other bird species, but not enough American Robins were captured for a comprehensive study of mosquito avian preference.     

Metabolic footprint of diabetes: a multiplatform metabolomics study in an epidemiological setting

Background

Metabolomics is the rapidly evolving field of the comprehensive measurement of ideally all endogenous metabolites in a biological fluid. However, no single analytic technique covers the entire spectrum of the human metabolome. Here we present results from a multiplatform study, in which we investigate what kind of results can presently be obtained in the field of diabetes research when combining metabolomics data collected on a complementary set of analytical platforms in the framework of an epidemiological study.

Methodology/Principal Findings

40 individuals with self-reported diabetes and 60 controls (male, over 54 years) were randomly selected from the participants of the population-based KORA (Cooperative Health Research in the Region of Augsburg) study, representing an extensively phenotyped sample of the general German population. Concentrations of over 420 unique small molecules were determined in overnight-fasting blood using three different techniques, covering nuclear magnetic resonance and tandem mass spectrometry. Known biomarkers of diabetes could be replicated by this multiple metabolomic platform approach, including sugar metabolites (1,5-anhydroglucoitol), ketone bodies (3-hydroxybutyrate), and branched chain amino acids. In some cases, diabetes-related medication can be detected (pioglitazone, salicylic acid).

Conclusions/Significance

Our study depicts the promising potential of metabolomics in diabetes research by identification of a series of known and also novel, deregulated metabolites that associate with diabetes. Key observations include perturbations of metabolic pathways linked to kidney dysfunction (3-indoxyl sulfate), lipid metabolism (glycerophospholipids, free fatty acids), and interaction with the gut microflora (bile acids). Our study suggests that metabolic markers hold the potential to detect diabetes-related complications already under sub-clinical conditions in the general population.     

An ES-like pluripotent state in FGF-dependent murine iPS cells

Recent data demonstrates that stem cells can exist in two morphologically, molecularly and functionally distinct pluripotent states; a naïve LIF-dependent pluripotent state which is represented by murine embryonic stem cells (mESCs) and an FGF-dependent primed pluripotent state represented by murine and rat epiblast stem cells (EpiSCs). We find that derivation of induced pluripotent stem cells (iPSCs) under EpiSC culture conditions yields FGF-dependent iPSCs from hereon called FGF-iPSCs) which, unexpectedly, display naïve ES-like/ICM properties. FGF-iPSCs display X-chromosome activation, multi-lineage differentiation, teratoma competence and chimera contribution in vivo. Our findings suggest that in 129 and Bl6 mouse strains, iPSCs can dominantly adopt a naive pluripotent state regardless of culture growth factor conditions.Characterization of the key molecular signalling pathways revealed FGF-iPSCs to depend on the Activin/Nodal and FGF pathways, while signalling through the JAK-STAT pathway is not required for FGF-iPS cell maintenance. Our findings suggest that in 129 and Bl6 mouse strains, iPSCs can dominantly adopt a naive pluripotent state regardless of culture growth factor conditions.     

Photosynthesis and plasmamembrane permeability properties of Prochloron

Photosynthetic carbon fixation of freshly isolated cells of Prochloron, the symbiont of Lissoclinum patella, proceeded at high rates (80–180 mol O₂·mgChl^-1·h^-1) in buffered seawater and showed a typical light response, saturating at about 300 E·m^-2·s^-1. However, in NaCl solutions osmotically equivalent to seawater CO₂-dependent O₂ evolution ceased or was severely inhibited. Hypotonic or hypertonic conditions induce degrees of swelling or shrinkage, respectively, apparently causing similar increases in the plasmamembrane's permeability to ferricyanide. Initially high, but rapidly declining, rates of electron transport were observed when the cells were suspended in distilled water. This inhibition was not caused by rupture of the cells, indicating instead diffusive loss of some essential factor(s) which normally exchange easily and rapidly between the cells and/or the host environment. Such rapid exchange may be part of the mechanism of this symbiosis and, if not adequately understood, may frustrate attempts to culture Prochloron away from its host.Abbreviations HEPES N-2-hydroxyethyl piperazine-N-2 ethane sulphonic acid - EPPS N-2-hydroxyethyl propane sulphonic acid - FeCN potassium ferricyanide - DBMIB 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - TMPD N,N,N,N,-tetramethyl-p-phenylenediamine - DCIP 2,6-dichlorophenol-indophenol - MV methylviologen - PS photosystem - Chl chlorophyll Publication No. 219 of the Australian Institute of Marine Science     

Fine structure of the knobby spore type of Streptomyces torulosus

The type strain of Streptomyces torulosus Lyons and Pridham (1971) was studied by scanning- and transmission electron microscope. Spore chains were formed in spirals by aerial mycelium. The spores were connected by nozzles in which small channels could be observed. The knobby ornamentations of the spores arised on a thin fibrous sheath, enveloping the spore chains. These irregular blunt projections, called knobs, had varying diameters of 100 to 250 nm. The base of the knob, consisting of globose to flattened electron dense material, was sitting directly on the sheath. It was covered by several small vesicles of the same material. Each hollow vesicle beared a thin bowlshaped shell of electron transparent material. In general, the cupular bowls and their supporting vesicles became easily depressed on their base, but not detached from the surface of the spores. This type of knobby spore ornamentation was suggested to be designated as a verrucate spore type.     

The predation on Asellus aquaticus (L.) by perch,Perca fluviatilis (L.), in a small forest lake

Asellus aquaticus (L.) was the most important benthic food item for perch, Perca fluviatilis (L.), in a small, extremely humic forest lake in southern Finland. The proportion of A. aquaticus in the diet of perch varied according to the former's availability, which, in turn, depended on its life cycle. Perch 11.0–12.9 cm (total length) most frequently fed on A. aquaticus; smaller and larger perch fed more frequently on crustacean zooplankton and aquatic insect larvae, respectively. The high density of the perch population, the importance of A. aquaticus in the benthos of the study lake and the general high activity level of the prey resulted in a high predation (0.1–1.8% per day). The population of A. aquaticus was also limited by the scarcity of macrophytic vegetation and the small area of oxygenated littoral in the lake.     

Effect of spring flooding on endophyte differentiation,nitrogenase activity,root growth and shoot growth inMyrica gale

Summary Spring flooding was investigated as a possible limiting factor in the development of nitrogenase activity, root growth, and shoot growth inMyrica gale. Dormant, one year oldMyrica gale plants were placed in a greenhouse in early April and given three treatments: control (not flooded), flooded-water (flooded with water to 2.5 cm above the soil level) and flooded-peat (flooded with water-saturated peat to 4.0 cm above the soil level). Nitrogenase activity was absent at budbreak but appeared concurrently with the differentiation of vesicles by theFrankia sp. endophyte. Flooding delayed the onset of nitrogenase activity, substantially reduced the specific nitrogenase activity of the nodules, and also severely limited the production of the new nodule biomass. Consequently by 67 days past budbreak nitrogenase activity was much greater in the control plants (5.55±0.42 mol C₂H₄/plant.h; ± SE; N=9) than in the flooded-water (1.18±0.29) and flooded-peat (0.15±0.05) plants. Production of new secondary roots was substantially reduced in the flooded plants but adventitious roots were rapidly produced along the flooded portion of the stem in the better aerated zone near the surface. New nodules formed on several adventitious roots by 67 days indicating that the plants are able to replace their largely nonfunctional deeply flooded nodules with new nodules in the aerobic zone. Initially shoot growth was unaffected by flooding but by 67 days the flooded plants had substantially less leaf biomass, lower leaf and stem nitrogen concentrations, and less total shoot nitrogen content than the control plants.     

Isozymes in nutrient medium of suspension-cultured apple cells (Malus sylvestris Mill.)

The time course of the activities of esterase, -galactosidase, and -glucosidase in cell sap and nutrient medium in in vitro cultured apple cells (Malus sylvestris Mill.) was studied. The corresponding isozyme patterns and the intracellular and extracellular isozyme patterns of acid phosphatase and polyphenol oxidase were compared using isozyme visualization methods adapted to ultra-thin-layer isoelectric focusing. Neither quantitative (total activity) nor qualitative (isozyme pattern) data were congruent for cell saps and nutrient media. Malate dehydrogenase, malic enzyme, and glutamate dehydrogenase occurred in cell sap only. The extracellular activities probably originate to a great part from a programmed release by intact cells. Nutrient media of plant cell cultures constitute a rich source of active plant isozymes.