A mesophilic relative of common glacier algae, Ancylonema palustre sp. nov., provides insights into the induction of vacuolar pigments in zygnematophytes.

The green algae of the genus Ancylonema, which belong to the zygnematophytes, are prevalent colonizers of glaciers worldwide. They display a striking reddish-brown pigmentation in their natural environment, due to vacuolar compounds related to gallic acid. This pigmentation causes glacier darkening when these algae bloom, leading to increased melting rates. The Ancylonema species known so far are true psychrophiles, which hinders experimental work and limits our understanding of these algae. For instance, the biosynthesis, triggering factors, and biological function of Ancylonema's secondary pigments remain unknown. In this study, we introduce a mesophilic Ancylonema species, A. palustre sp. nov., from temperate moorlands. This species forms the sister lineage to all known psychrophilic strains. Despite its morphological similarity to the latter, it exhibits unique autecological and photophysiological characteristics. It allows us to describe vegetative and sexual cellular processes in great detail. We also conducted experimental tests for abiotic factors that induce the secondary pigments of zygnematophytes. We found that low nutrient conditions combined with ultraviolet B radiation result in vacuolar pigmentation, suggesting a sunscreen function. Our thriving, bacteria-free cultures of Ancylonema palustre will enable comparative genomic studies of mesophilic and extremophilic zygnematophytes. These studies may provide insights into how Ancylonema species colonized the world's glaciers.

Comparative transcriptomics elucidates the cellular responses of an aeroterrestrial zygnematophyte to UV radiation.

The zygnematophytes are the closest relatives of land plants and comprise several lineages that adapted to a life on land. Species of the genus Serritaenia form colorful, mucilaginous capsules, which surround the cells and block harmful solar radiation, one of the major terrestrial stressors. In eukaryotic algae, this 'sunscreen mucilage' represents a unique photoprotective strategy, whose induction and chemical background are unknown. We generated a de novo transcriptome of Serritaenia testaceovaginata and studied its gene regulation under moderate UV radiation (UVR) that triggers sunscreen mucilage under experimental conditions. UVR induced the repair of DNA and the photosynthetic apparatus as well as the synthesis of aromatic specialized metabolites. Specifically, we observed pronounced expressional changes in the production of aromatic amino acids, phenylpropanoid biosynthesis genes, potential cross-membrane transporters of phenolics, and extracellular, oxidative enzymes. Interestingly, the most up-regulated enzyme was a secreted class III peroxidase, whose embryophyte homologs are involved in apoplastic lignin formation. Overall, our findings reveal a conserved, plant-like UVR perception system (UVR8 and downstream factors) in zygnematophyte algae and point to a polyphenolic origin of the sunscreen pigment of Serritaenia, whose synthesis might be extracellular and oxidative, resembling that of plant lignins.

A phylogenomically informed five-order system for the closest relatives of land plants.

The evolution of streptophytes had a profound impact on life on Earth. They brought forth those photosynthetic eukaryotes that today dominate the macroscopic flora: the land plants (Embryophyta).1 There is convincing evidence that the unicellular/filamentous Zygnematophyceae-and not the morphologically more elaborate Coleochaetophyceae or Charophyceae-are the closest algal relatives of land plants.2-6 Despite the species richness (>4,000), wide distribution, and key evolutionary position of the zygnematophytes, their internal phylogeny remains largely unresolved.7,8 There are also putative zygnematophytes with interesting body plan modifications (e.g., filamentous growth) whose phylogenetic affiliations remain unknown. Here, we studied a filamentous green alga (strain MZCH580) from an Austrian peat bog with central or parietal chloroplasts that lack discernible pyrenoids. It represents Mougeotiopsis calospora PALLA, an enigmatic alga that was described more than 120 years ago9 but never subjected to molecular analyses. We generated transcriptomic data of M. calospora strain MZCH580 and conducted comprehensive phylogenomic analyses (326 nuclear loci) for 46 taxonomically diverse zygnematophytes. Strain MZCH580 falls in a deep-branching zygnematophycean clade together with some unicellular species and thus represents a formerly unknown zygnematophycean lineage with filamentous growth. Our well-supported phylogenomic tree lets us propose a new five-order system for the Zygnematophyceae and provides evidence for at least five independent origins of true filamentous growth in the closest algal relatives of land plants. This phylogeny provides a robust and comprehensive framework for performing comparative analyses and inferring the evolution of cellular traits and body plans in the closest relatives of land plants.

Life History, Biology, and Distribution of Pterostichus melanarius (Coleoptera: Carabidae) in North America.

Pterostichus melanarius (Illiger, 1798) is a Palearctic generalist predator native to Europe. It was unintentionally introduced to North America at least twice in the mid 1920s and has since become widespread in Canada and the United States. Although P. melanarius is a valuable natural enemy in many different agricultural systems, we are not aware of any effort to compile in one publication details of its life history, diet, distribution, and factors that influence its populations. Some studies in North America have investigated the effects of P. melanarius on pest species and native carabid assemblages. Moreover, given that it is an exotic species whose range appears to still be expanding, it will be valuable to predict its potential distribution in North America. Therefore, the goals of this paper are to: 1) compile information on the life history and biology of P. melanarius, 2) review the effects of various agricultural practices on this species, and 3) use ecological niche modeling to determine the potential range of P. melanarius in the United States and which climate variables are most important for range expansion. Our review revealed that P. melanarius appears to provide benefits most consistently in diverse agricultural systems managed with no-till or reduced till methods, whereas our modeling revealed that P. melanarius likely occupies, or will occupy, more of the northern U.S. than is currently recognized, particularly in the Appalachian and Rocky Mountain regions.

Crop-associated virus reduces the rooting depth of non-crop perennial native grass more than non-crop-associated virus with known viral suppressor of RNA silencing (VSR).

As agricultural acreage expanded and came to dominate landscapes across the world, viruses gained opportunities to move between crop and wild native plants. In the Midwestern USA, virus exchange currently occurs between widespread annual Poaceae crops and remnant native perennial prairie grasses now under consideration as bioenergy feedstocks. In this region, the common aphid species Rhopalosiphum padi L. (the bird cherry-oat aphid) transmits several virus species in the family Luteoviridae, including Barley yellow dwarf virus (BYDV-PAV, genus Luteovirus) and Cereal yellow dwarf virus (CYDV-RPV and -RPS, genus Polerovirus). The yellow dwarf virus (YDV) species in these two genera share genetic similarities in their 3'-ends, but diverge in the 5'-regions. Most notably, CYDVs encode a P0 viral suppressor of RNA silencing (VSR) absent in BYDV-PAV. Because BYDV-PAV has been reported more frequently in annual cereals and CYDVs in perennial non-crop grasses, we examine the hypothesis that the viruses' genetic differences reflect different affinities for crop and non-crop hosts. Specifically, we ask (i) whether CYDVs might persist within and affect a native non-crop grass more strongly than BYDV-PAV, on the grounds that the polerovirus VSR could better moderate the defenses of a well-defended perennial, and (ii) whether the opposite pattern of effects might occur in a less defended annual crop. Because previous work found that the VSR of CYDV-RPS possessed greater silencing suppressor efficiency than that of CYDV-RPV, we further explored (iii) whether a novel grass-associated CYDV-RPS isolate would influence a native non-crop grass more strongly than a comparable CYDV-RPV isolate. In growth chamber studies, we found support for this hypothesis: only grass-associated CYDV-RPS stunted the shoots and crowns of Panicum virgatum L. (switchgrass), a perennial native North American prairie grass, whereas crop-associated BYDV-PAV (and coinfection with BYDV-PAV and CYDV-RPS) most stunted annual Avena sativa L. (oats). These findings suggest that some of the diversity in grass-infecting Luteoviridae reflects viral capacity to modulate defenses in different host types. Intriguingly, while all virus treatments also reduced root production in both host species, only crop-associated BYDV-PAV (or co-infection) reduced rooting depths. Such root effects may increase host susceptibility to drought, and indicate that BYDV-PAV pathogenicity is determined by something other than a P0 VSR. These findings contribute to growing evidence that pathogenic crop-associated viruses may harm native species as well as crops. Critical next questions include the extent to which crop-associated selection pressures drive viral pathogenesis.

The Cytoskeleton Architecture of Algivorous Protoplast Feeders (Viridiraptoridae, Rhizaria) Indicates Actin-Guided Perforation of Prey Cell Walls.

Several distantly related, phagotrophic microeukaryotes share the remarkable ability to perforate foreign cell walls in a well-defined pattern to acquire protoplast material as food. The underlying cellular processes, especially the local application of cell wall degrading agents, are still unexplored. We examined the distribution of F-actin and alpha-tubulin in the algivorous, viridiraptorid amoeboflagellates Orciraptor agilis and Viridiraptor invadens over their life histories using phalloidin conjugates and immunolocalization. During attack, both species form distinctive, F-actin-rich structures at the contact zone to the algal prey cell, which exactly match the species-specific cell wall perforations and resemble invadopodia and podosome rosettes of mammalian cells to a certain extent. Furthermore, F-actin is involved in the extraction of plastid material by Orciraptor and in prey cell invasion by Viridiraptor (here, F-actin localizes to a characteristic hyaline channel, which surrounds the streaming cytoplasm). The digestive-reproductive stages of viridiraptorids display a highly ordered microtubular cytoskeleton, whereas distinct phalloidin-positive actin structures could not be detected. We discuss the presumed function of F-actin during perforation and penetration of the algal cell wall by viridiraptorids, and compare the cytoskeleton architecture of these protoplast feeders to amoeboflagellates from different eukaryotic supergroups.

Thermal Decomposition of NCN: Shock-Tube Study, Quantum Chemical Calculations, and Master-Equation Modeling.

The thermal decomposition of cyanonitrene, NCN, was studied behind reflected shock waves in the temperature range 1790-2960 K at pressures near 1 and 4 bar. Highly diluted mixtures of NCN3 in argon were shock-heated to produce NCN, and concentration-time profiles of C atoms as reaction product were monitored with atomic resonance absorption spectroscopy at 156.1 nm. Calibration was performed with methane pyrolysis experiments. Rate coefficients for the reaction (3)NCN + M → (3)C + N2 + M (R1) were determined from the initial slopes of the C atom concentration-time profiles. Reaction R1 was found to be in the low-pressure regime at the conditions of the experiments. The temperature dependence of the bimolecular rate coefficient can be expressed with the following Arrhenius equation: k1(bim) = (4.2 ± 2.1) × 10(14) exp[-242.3 kJ mol(-1)/(RT)] cm(3) mol(-1) s(-1). The rate coefficients were analyzed by using a master equation with specific rate coefficients from RRKM theory. The necessary molecular data and energies were calculated with quantum chemical methods up to the CCSD(T)/CBS//CCSD/cc-pVTZ level of theory. From the topography of the potential energy surface, it follows that reaction R1 proceeds via isomerization of NCN to CNN and subsequent C-N bond fission along a collinear reaction coordinate without a tight transition state. The calculations reproduce the magnitude and temperature dependence of the rate coefficient and confirm that reaction R1 is in the low-pressure regime under our experimental conditions.

Intermittent catheterization with a hydrophilic-coated catheter delays urinary tract infections in acute spinal cord injury: a prospective, randomized, multicenter trial.

OBJECTIVE: To investigate whether intermittent catheterization (IC) with a hydrophilic-coated catheter delays the onset of the first symptomatic urinary tract infection (UTI) and reduces the number of symptomatic UTIs in patients with acute spinal cord injury (SCI) compared with IC with standard, uncoated catheters. DESIGN: A prospective, randomized, parallel-group trial. SETTING: Fifteen North American SCI centers. Participants were followed up while in the hospital or rehabilitation unit (institutional period) and up to 3 months after institutional discharge (community period). The maximal study period was 6 months. PARTICIPANTS: A total of 224 subjects with traumatic SCI of less than 3 months' duration who use IC. METHODS: The participants were randomized within 10 days of starting IC to either single-use hydrophilic-coated (SpeediCath) or polyvinyl chloride uncoated (Conveen) catheters. MAIN OUTCOME MEASUREMENTS: The time from the first catheterization to the first antibiotic-treated symptomatic UTI was measured as well as the total number of symptomatic UTIs during the study period. RESULTS: The time to the first antibiotic-treated symptomatic UTI was significantly delayed in the hydrophilic-coated catheter group compared with the uncoated catheter group. The delay corresponded to a 33% decrease in the daily risk of developing the first symptomatic UTI among participants who used the hydrophilic-coated catheter. In the institutional period, the incidence of antibiotic-treated symptomatic UTIs was reduced by 21% (P < .05) in the hydrophilic-coated catheter group. CONCLUSIONS: The use of a hydrophilic-coated catheter for IC is associated with a delay in the onset of the first antibiotic-treated symptomatic UTI and with a reduction in the incidence of symptomatic UTI in patients with acute SCI during the acute inpatient rehabilitation. Using a hydrophilic-coated catheter could minimize UTI-related complications, treatment costs, and rehabilitation delays in this group of patients, and reduce the emergence of antibiotic-resistant organisms.

A lipidomic screen of palmitate-treated MIN6 ß-cells links sphingolipid metabolites with endoplasmic reticulum (ER) stress and impaired protein trafficking.

Saturated fatty acids promote lipotoxic ER (endoplasmic reticulum) stress in pancreatic ß-cells in association with Type 2 diabetes. To address the underlying mechanisms we employed MS in a comprehensive lipidomic screen of MIN6 ß-cells treated for 48 h with palmitate. Both the overall mass and the degree of saturation of major neutral lipids and phospholipids were only modestly increased by palmitate. The mass of GlcCer (glucosylceramide) was augmented by 70% under these conditions, without any significant alteration in the amounts of either ceramide or sphingomyelin. However, flux into ceramide (measured by [3H]serine incorporation) was augmented by chronic palmitate, and inhibition of ceramide synthesis decreased both ER stress and apoptosis. ER-to-Golgi protein trafficking was also reduced by palmitate pre-treatment, but was overcome by overexpression of GlcCer synthase. This was accompanied by increased conversion of ceramide into GlcCer, and reduced ER stress and apoptosis, but no change in phospholipid desaturation. Sphingolipid alterations due to palmitate were not secondary to ER stress since they were neither reproduced by pharmacological ER stressors nor overcome using the chemical chaperone phenylbutyric acid. In conclusion, alterations in sphingolipid, rather than phospholipid, metabolism are more likely to be implicated in the defective protein trafficking and enhanced ER stress and apoptosis of lipotoxic ß-cells.

Increased fatty acid desaturation and enhanced expression of stearoyl coenzyme A desaturase protects pancreatic beta-cells from lipoapoptosis.

Increased availability of fatty acids causes cell death and dysfunction in beta-cell lines, isolated islets, and animal models of diabetes. From the MIN6 beta-cell line, we selected two subpools that are resistant to palmitate-induced apoptosis. Protection was not universal because palmitate-resistant cells remained sensitive to cytokine- and streptozotocin-induced apoptosis. Palmitate oxidation and incorporation into cholesterol ester (but not triglycerides) were significantly higher in palmitate-resistant cells than in control cells. Consistent with these findings, transcript profiling revealed increased expression in palmitate-resistant cells of several beta-oxidation genes as well as a 2.8-fold upregulation of stearoyl-CoA desaturase 1 (SCD1). Correspondingly, the oleate-to-palmitate ratio of palmitate-resistant cells was double that of palmitate-pretreated control cells. At least some of this additional oleate in palmitate-resistant cells was incorporated into cholesterol ester stored in the form of large cytosolic lipid bodies. However, blocking cholesterol ester formation did not render palmitate-resistant cells sensitive to palmitate-induced apoptosis. On the other hand, an inhibitor of SCD1, 10,12-conjugated linoleic acid, dose dependently overcame the resistance of palmitate-resistant cells to lipoapoptosis. Our results suggest that desaturation per se is more important in protecting beta-cells from the cytotoxic effects of palmitate than is the nature of neutral lipid storage pool thus generated.

Chronic effects of fatty acids on pancreatic beta-cell function: new insights from functional genomics.

Type 2 diabetes can be viewed as a failure of the pancreatic beta-cell to compensate for peripheral insulin resistance with enhanced insulin secretion. This failure is explained by both a relative loss of beta-cell mass as well as secretory defects that include enhanced basal secretion and a selective loss of sensitivity to glucose. These features are reproduced by chronic exposure of beta-cells to fatty acids (FAs), suggesting that hyperlipidemia might contribute to decompensation. Using MIN6 cells pretreated for 48 h with oleate or palmitate, we have previously defined alterations in global gene expression by transcript profiling and described additional secretory changes to those already established (Busch A-K, Cordery D, Denyer G, Biden TJ: Diabetes 51:977-987, 2002). In contrast to a modest decoupling of glucose-stimulated insulin secretion, FA pretreatment markedly enhanced the secretory response to an acute subsequent challenge with FAs. We propose that this apparent switch in sensitivity from glucose to FAs would be an appropriate response to hyperlipidemia in vivo and thus plays a positive role in beta-cell compensation for insulin resistance. Altered expression of dozens of genes could contribute to this switch, and allelic variations in any of these genes could (to varying degrees) impair beta-cell compensation and thus contribute to conditions ranging from impaired glucose tolerance to frank diabetes.

Expression profiling of palmitate- and oleate-regulated genes provides novel insights into the effects of chronic lipid exposure on pancreatic beta-cell function.

Chronic lipid exposure is implicated in beta-cell dysfunction in type 2 diabetes. We therefore used oligonucleotide arrays to define global alterations in gene expression in MIN6 cells after 48-h pretreatment with oleate or palmitate. Altogether, 126 genes were altered > or =1.9-fold by palmitate, 62 by oleate, and 46 by both lipids. Importantly, nine of the palmitate-regulated genes are known to be correspondingly changed in models of type 2 diabetes. A tendency toward beta-cell de-differentiation was also apparent with palmitate: pyruvate carboxylase and mitochondrial glycerol 3-phosphate dehydrogenase were downregulated, whereas lactate dehydrogenase and fructose 1,6-bisphosphatases were induced. Increases in the latter (also seen with oleate), along with glucosamine-phosphate N-acetyl transferase, imply upregulation of the hexosamine biosynthesis pathway in palmitate-treated cells. However, palmitate also increased expression of calcyclin and 25-kDa synaptosomal-associated protein (SNAP25), which control distal secretory processes. Consistent with these findings, secretory responses to noncarbohydrate stimuli, especially palmitate itself, were upregulated in palmitate-treated cells (much less so with oleate). Indeed, glucose-stimulated secretion was slightly sensitized by chronic palmitate exposure but inhibited by oleate treatment, whereas both lipids enhanced basal secretion. Oleate and palmitate also induced expression of chemokines (MCP-1 and GRO1 oncogene) and genes of the acute phase response (serum amyloid A3). Increases in transcriptional modulators such as ATF3, CCAAT/enhancer binding protein-beta (C/EBPbeta), C/EBPdelta, and c-fos were also seen. The results highlight links between regulated gene expression and phenotypic alterations in palmitate versus oleate-pretreated beta-cells.