Measurement of Ice Nucleation-Active Bacteria on Plants and in Precipitation by Quantitative PCR

Ice nucleation-active (INA) bacteria may function as high-temperature ice-nucleating particles (INP) in clouds, but their effective contribution to atmospheric processes, i.e., their potential to trigger glaciation and precipitation, remains uncertain. We know little about their abundance on natural vegetation, factors that trigger their release, or persistence of their ice nucleation activity once airborne. To facilitate these investigations, we developed two quantitative PCR (qPCR) tests of the ina gene to directly count INA bacteria in environmental samples. Each of two primer pairs amplified most alleles of the ina gene and, taken together, they should amplify all known alleles. To aid primer design, we collected many new INA isolates. Alignment of their partial ina sequences revealed new and deeply branching clades, including sequences from Pseudomonas syringae pv. atropurpurea, Ps. viridiflava, Pantoea agglomerans, Xanthomonas campestris, and possibly Ps. putida, Ps. auricularis, and Ps. poae. qPCR of leaf washings recorded ∼10⁸ina genes g⁻¹ fresh weight of foliage on cereals and 10⁵ to 10⁷ g⁻¹ on broadleaf crops. Much lower populations were found on most naturally occurring vegetation. In fresh snow, ina genes from various INA bacteria were detected in about half the samples but at abundances that could have accounted for only a minor proportion of INP at −10°C (assuming one ina gene per INA bacterium). Despite this, an apparent biological source contributed an average of ∼85% of INP active at −10°C in snow samples. In contrast, a thunderstorm hail sample contained 0.3 INA bacteria per INP active at −10°C, suggesting a significant contribution to this sample.     

Effects of plant harvesting and nutrient enrichment on phytoplankton community structure in a shallow urban lake

The utility of shallow water bodies in urban environments is frequently compromised either by dense beds of submerged plants or cyanobacterial blooms associated with nutrient enrichment. Although submerged plants are often harvested to facilitate recreational uses, this activity may alter the phytoplankton community, which in turn, also may restrict the use of the lake. We tested whether (i) plant harvesting reduced the abundance of flagellate algae and increased the abundance of cyanobacteria, and (ii) whether increasing levels of nutrient enrichment caused shifts in the dominance of heterocytous cyanobacteria, non-heterocytous cyanobacteria and Chlorophyta, in a shallow urban lake in Southern Australia as has been observed for shallow Danish lakes in previous studies. These predictions were tested with large (3000 l), replicated mesocosms in a warm, highly productive, shallow lake densely colonised by the submerged angiosperm, Vallisnaria americana Michaux. The heterokont algae, Chlorophyta, Cyanobacteria and Cryptophyta were the most numerous algal divisions in the lake. The Euglenophyta, although uncommon in early summer, became more abundant towards the end of summer. The Dinophyta and Charophyta were rare. The abundance of the heterokont algae and Euglenophyta was significantly reduced by plant harvesting even after plants had partially re-established 18 weeks after initial harvesting. The decline in the Euglenophyta in response to plant harvesting is consistent with earlier findings, that the relative abundance of flagellate algae tends to be greater in the presence of submerged plants. Contrary to our prediction, we found that the Cyanobacteria did not increase in response to plant harvesting, however the response may be altered under higher nutrient levels. Algal responses to nutrient enrichment in the presence of dense V. americana plants generally followed the patterns observed in shallow Danish lakes despite the large differences in climatic conditions. Both studies found that the abundance of heterocytous cyanobacteria declined at higher levels of nutrient enrichment, whereas non-heterocytous cyanobacteria and chlorophytes increased.     

Effects of basic fibroblast growth factor on endothelial cells under conditions of simulated microgravity

Fibroblast growth factors interact with appropriate endothelial cell (EC) surface receptors and initiate intracellular signal cascades, which participate in modulating blood vessel growth. EC, upon exposure to basic fibroblast growth factors (bFGFs) undergo profound functional alterations, which depend on their actual sensitivity and involve gene expression and de novo protein synthesis. We investigated the effects of bFGF on signaling pathways of EA.hy926 cells in different environments. EC were cultured under normal gravity (1 g) and simulated microgravity (micro g) using a three-dimensional (3D) clinostat. Microgravity induced early and late apoptosis, extracellular matrix proteins, endothelin-1 (ET-1) and TGF-beta(1) expression. Microgravity reduced eNOS mRNA within 24 h. Moreover, a six- to eightfold higher amount of IL-6 and IL-8 was secreted within 24 h micro g. In addition, microgravity induced a duplication of NF-kappaB p50, while p65 was quadrupled. At 1 g, bFGF application (4 h) reduced ET-1, TGF-beta(1) and eNOS gene expression. After 24 h, bFGF enhanced fibronectin, VEGF, Flk-1, Flt-1, the release of IL-6, IL-8, and TGF-beta(1). Furthermore, bFGF promoted apoptosis, reduced NFkB p50, but enhanced NFkB p65. After 4 h micro g, bFGF decreased TGF-beta(1), eNOS, and ET-1 gene expression. After 24 h micro g, bFGF elevated fibronectin, Flk-1 and Flt-1 protein, and reduced IL-6 and IL-8 compared with vehicle treated micro g cultures. In micro g, bFGF enhanced NF-KappaB p50 by 50%, Bax by 25% and attenuated p65, activation of caspase-3 and annexin V-positive cells. bFGF differently changes intracellular signals in ECs depending whether it is applied under microgravity or normal gravity conditions. In microgravity, bFGF contributes to protect the EC from apoptosis.     

Roles of G protein and beta-arrestin in dopamine D2 receptor-mediated ERK activation

ERK activation by dopamine D₂ receptor (D₂R) has been extensively characterized in various cell types including brain tissues. However, the involvement of β-arrestin in the D₂R-mediated ERK activation is not clear yet. Three different strategies were employed in this study to determine the roles of G protein or β-arrestin in D₂R-mediated ERK activation. The cellular level of β-arrestins was reduced by RNA interference and pertussis toxin-insensitive Gi proteins were used to identify the G protein involved. Finally point mutations of D₂R in which coupling with G protein was abolished but the interaction with β-arrestin was increased, were employed to determine whether the affinity between D₂R and β-arrestin is a critical factor for β-arrestin-mediated ERK activation. Our results show that G_i2 protein is involved in D₂R-mediated ERK activation but β-arrestins are either not involved or play minor role.     

Synthesis,characterization, redox behavior,DNA and protein binding and antibacterial activity studies of ruthenium(II) complexes of bidentate schiff bases

Two new ruthenium(II) complexes of Schiff base ligands (L) derived from cinnamaldehyde and ethylenediamine formulated as [Ru(L)(bpy)₂](ClO₄)₂, where L¹ = N,N’-bis(4-nitrocinnamald-ehyde)ethylenediamine and L² = N,N’-bis(2-nitrocinnamaldehyde)-ethylenediamine for complex 1 and 2, respectively, were isolated in pure form. The complexes were characterized by physicochemical and spectroscopic methods. The electrochemical behavior of the complexes showed the Ru(III)/Ru(II) couple at different potentials with quasi-reversible voltammograms. The interaction of the complexes with calf thymus DNA (CT-DNA) using absorption, emission spectral studies and electrochemical techniques have been used to determine the binding constant, K_b and the linear Stern–Volmer quenching constant, K_SV. The results indicate that the ruthenium(II) complexes interact with CT-DNA strongly in a groove binding mode. The interactions of bovine serum albumin (BSA) with the complexes were also investigated with the help of absorption and fluorescence spectroscopy tools. Absorption spectroscopy proved the formation of a ground state BSA-[Ru(L)(bpy)₂](ClO₄)₂ complex. The antibacterial study showed that the Ru(II) complexes (1 and 2) have better activity than the standard antibiotics but weak activity than the ligands.     

Differential activities of peroxisomes along the mouse intestinal epithelium

The presence of peroxisomes in mammalian intestine has been revealed formerly by catalase staining combined with electron microscopy. Despite the central role of intestine in lipid uptake and the established importance of peroxisomes in different lipid‐related pathways, few data are available on the physiological role of peroxisomes in intestinal metabolism, more specifically, α‐, β‐oxidation, and etherlipid synthesis. Hence, the peroxisomal compartment was analyzed in more detail in mouse intestine. On the basis of immunohistochemistry, the organelles are mainly confined to the epithelial cells. The expression of the classical peroxisome marker catalase was highest in the proximal part of jejunum and decreased along the tract. PEX14 showed a similar profile, but was still substantial expressed in large intestinal epithelium. Immunoblotting of epithelial cells, isolated from the different segments, showed also such gradient for some enzymes, ie, catalase, ACOX1, and D‐specific multifunctional protein 2, and for the ABCD1 transporter, being high in small and low or absent in large intestine. Other peroxisomal enzymes (PHYH, HACL1, and ACAA1), the ABCD2 and ABCD3 transporters, and peroxins PEX13 and PEX14, however, did not follow this pattern, displaying rather constant signals throughout the intestinal epithelium. The small intestine displayed the highest peroxisomal β‐oxidation activity and is particularly active on dicarboxylic acids. Etherlipid synthesis was high in the large intestine, and colonic cells had the highest content of plasmalogens. Overall, these data suggest that peroxisomes exert different functions according to the intestinal segment.     

Brooding sea anemones (Cnidaria: Anthozoa: Actiniaria): paragons of diversity in mode,morphology, and maternity

Brooding has been reported in at least 57 species of sea anemone. More than three quarters (44/57) of the species that are known to brood have been described since the last comprehensive treatment of brooding in this lineage. Different authors focusing on different taxonomic groups within sea anemones over the last 115 years have collectively produced an imprecise and inconsistent set of terminology with respect to brooding in general and to the variety of conditions of brooding in particular. In this review, I characterize brooding as a behavior in which offspring are retained by the adult to at least the juvenile stage, in contrast with the more common release of eggs, embryos, or larvae. Brooding occurs in two primary modes, internal and external, in which offspring may be produced via sexual or asexual means. I categorize structures associated with external brooding in three types: pits, chambers, and grooves. Early inferences that external brooding has a primarily bipolar distribution continue to be supported with current data, but it is doubtful that small size and simultaneous hermaphroditism are correlated with brooding in sea anemones. Finally, I identify open questions about brooding in sea anemones and suggest future lines of research that will broaden our understanding of this phenomenon.