Microbial tropicalization driven by a strengthening western ocean boundary current

Western boundary currents (WBCs) redistribute heat and oligotrophic seawater from the tropics to temperate latitudes, with several displaying substantial climate change‐driven intensification over the last century. Strengthening WBCs have been implicated in the poleward range expansion of marine macroflora and fauna, however, the impacts on the structure and function of temperate microbial communities are largely unknown. Here we show that the major subtropical WBC of the South Pacific Ocean, the East Australian Current (EAC), transports microbial assemblages that maintain tropical and oligotrophic (k‐strategist) signatures, to seasonally displace more copiotrophic (r‐strategist) temperate microbial populations within temperate latitudes of the Tasman Sea. We identified specific characteristics of EAC microbial assemblages compared with non‐EAC assemblages, including strain transitions within the SAR11 clade, enrichment of Prochlorococcus, predicted smaller genome sizes and shifts in the importance of several functional genes, including those associated with cyanobacterial photosynthesis, secondary metabolism and fatty acid and lipid transport. At a temperate time‐series site in the Tasman Sea, we observed significant reductions in standing stocks of total carbon and chlorophyll a, and a shift towards smaller phytoplankton and carnivorous copepods, associated with the seasonal impact of the EAC microbial assemblage. In light of the substantial shifts in microbial assemblage structure and function associated with the EAC, we conclude that climate‐driven expansions of WBCs will expand the range of tropical oligotrophic microbes, and potentially profoundly impact the trophic status of temperate waters.     

The Diguanylate Cyclase SadC Is a Central Player in Gac/Rsm-Mediated Biofilm Formation in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a Gram-negative opportunistic human pathogen and a threat for immunocompromised and cystic fibrosis patients. It is responsible for acute and chronic infections and can switch between these lifestyles upon taking an informed decision involving complex regulatory networks. The RetS/LadS/Gac/Rsm network and the cyclic-di-GMP (c-di-GMP) signaling pathways are both central to this phenomenon redirecting the P. aeruginosa population toward a biofilm mode of growth, which is associated with chronic infections. While these two pathways were traditionally studied independently from each other, we recently showed that cellular levels of c-di-GMP are increased in the hyperbiofilm retS mutant. Here, we have formally established the link between the two networks by showing that the SadC diguanylate cyclase is central to the Gac/Rsm-associated phenotypes, notably, biofilm formation. Importantly, SadC is involved in the signaling that converges onto the RsmA translational repressor either via RetS/LadS or via HptB/HsbR. Although the level of expression of the sadC gene does not seem to be impacted by the regulatory cascade, the production of the SadC protein is tightly repressed by RsmA. This adds to the growing complexity of the signaling network associated with c-di-GMP in P. aeruginosa. While this organism possesses more than 40 c-di-GMP-related enzymes, it remains unclear how signaling specificity is maintained within the c-di-GMP network. The finding that SadC but no other diguanylate cyclase is related to the formation of biofilm governed by the Gac/Rsm pathway further contributes to understanding of this insulation mechanism.     

A network of assembly factors is involved in remodeling rRNA elements during preribosome maturation

Eukaryotic ribosome biogenesis involves ∼200 assembly factors, but how these contribute to ribosome maturation is poorly understood. Here, we identify a network of factors on the nascent 60S subunit that actively remodels preribosome structure. At its hub is Rsa4, a direct substrate of the force-generating ATPase Rea1. We show that Rsa4 is connected to the central protuberance by binding to Rpl5 and to ribosomal RNA (rRNA) helix 89 of the nascent peptidyl transferase center (PTC) through Nsa2. Importantly, Nsa2 binds to helix 89 before relocation of helix 89 to the PTC. Structure-based mutations of these factors reveal the functional importance of their interactions for ribosome assembly. Thus, Rsa4 is held tightly in the preribosome and can serve as a “distribution box,” transmitting remodeling energy from Rea1 into the developing ribosome. We suggest that a relay-like factor network coupled to a mechano-enzyme is strategically positioned to relocate rRNA elements during ribosome maturation.     

Noninvasive Ultrasound Molecular Imaging of the Effect of Statins on Endothelial Inflammatory Phenotype in Early Atherosclerosis

Background/Objectives

Inflammatory changes on the endothelium are responsible for leukocyte recruitment to plaques in atherosclerosis. Noninvasive assessment of treatment-effects on endothelial inflammation may be of use for managing medical therapy and developing novel therapies. We hypothesized that molecular imaging of vascular cell adhesion molecule-1 (VCAM-1) with contrast enhanced ultrasound (CEU) could assess treatment effects on endothelial phenotype in early atherosclerosis.

Methods

Mice with atherosclerosis produced by gene deletion of the LDL-receptor and Apobec-1-editing protein were studied. At 12 weeks of age, mice received 8 weeks of regular chow or atorvastatin-enriched chow (10 mg/kg/day). At 20 weeks, CEU molecular imaging for aortic endothelial VCAM-1 expression was performed with VCAM-1-targeted (MB_VCAM) and control microbubbles (MB_Ctr). Aortic wall thickness was assessed with high frequency ultrasound. Histology, immunohistology and Western blot were used to assess plaque burden and VCAM-1 expression.

Results

Plaque burden was reduced on histology, and VCAM-1 was reduced on Western blot by atorvastatin, which corresponded to less endothelial expression of VCAM-1 on immunohistology. High frequency ultrasound did not detect differences in aortic wall thickness between groups. In contrast, CEU molecular imaging demonstrated selective signal enhancement for MB_VCAM in non-treated animals (MB_VCAM 2±0.3 vs MB_Ctr 0.7±0.2, p<0.01), but not in statin-treated animals (MB_VCAM 0.8±0.2 vs MB_Ctr 1.0±0.2, p = ns; p<0.01 for the effect of statin on MB_VCAM signal).

Conclusions

Non-invasive CEU molecular imaging detects the effects of anti-inflammatory treatment on endothelial inflammation in early atherosclerosis. This easily accessible, low-cost technique may be useful in assessing treatment effects in preclinical research and in patients.     

Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

New protein isoforms identified within Arabidopsis thaliana seed oil bodies combining chymotrypsin/trypsin digestion and peptide fragmentation analysis

Plant seed oil bodies, subcellular lipoprotein inclusions providing storage reserves, are composed of a neutral lipid core surrounded by a phospholipid monolayer with several integrated proteins that play a significant role in stabilization of the particles and probably also in lipid mobilization. Oil bodies' proteins are generally very hydrophobic, due to the long uncharged sequences anchoring them into the lipid core, which makes them extremely difficult to handle and to digest successfully. Although oil bodies have been intensively studied during last decades, not all their proteins have been identified yet. To overcome the problems connected with their identification, a method based on SDS-PAGE, in-gel digestion and LC-MS/MS analysis was used. Digestion was carried out with trypsin and chymotrypsin, single or in combination, which increased significantly the number of identified peptides, namely the hydrophobic ones. Thanks to this methodology it was possible to achieve an extensive coverage of proteins studied, to analyze their N-terminal modifications and moreover, to detect four new oil bodies' protein isoforms, which demonstrates the complexity of oil bodies' protein composition.     

Sponge non-metastatic Group I Nme gene/protein - structure and function is conserved from sponges to humans

Background  

Nucleoside diphosphate kinases NDPK are evolutionarily conserved enzymes present in Bacteria, Archaea and Eukarya, with human Nme1 the most studied representative of the family and the first identified metastasis suppressor. Sponges (Porifera) are simple metazoans without tissues, closest to the common ancestor of all animals. They changed little during evolution and probably provide the best insight into the metazoan ancestor's genomic features. Recent studies show that sponges have a wide repertoire of genes many of which are involved in diseases in more complex metazoans. The original function of those genes and the way it has evolved in the animal lineage is largely unknown. Here we report new results on the metastasis suppressor gene/protein homolog from the marine sponge Suberites domuncula, NmeGp1Sd. The purpose of this study was to investigate the properties of the sponge Group I Nme gene and protein, and compare it to its human homolog in order to elucidate the evolution of the structure and function of Nme.     

Application of DNA methyltransferases in targeted DNA methylation

Taxol is a valuable plant-derived drug showing activity against various cancer types. Worldwide efforts had been made to overcome the supply problem, because the supply by isolation from the bark of the slow-growing yew trees is limited. Plant cell cultures as well as chemical and biotechnological semisynthesis are processes, which are intensively investigated for the production of taxanes paclitaxel (Taxol) and docetaxel (Taxotere) in the last few years. This article provides a comparison of the current research on taxane biosynthesis and production in yew cell cultures.     

Phosphatidylethanolamine synthesized by four different pathways is supplied to the plasma membrane of the yeast Saccharomyces cerevisiae

In this study, we examined the contribution of the four different pathways of phosphatidylethanolamine (PE) synthesis in the yeast Saccharomyces cerevisiae to the supply of this phospholipid to the plasma membrane. These pathways of PE formation are decarboxylation of phosphatidylserine (PS) by (i) phosphatidylserine decarboxylase 1 (Psd1p) in mitochondria and (ii) phosphatidylserine decarboxylase 2 (Psd2p) in a Golgi/vacuolar compartment, (iii) incorporation of exogenous ethanolamine and ethanolamine phosphate derived from sphingolipid catabolism via the CDP-ethanolamine pathway in the endoplasmic reticulum (ER), and (iv) synthesis of PE through acylation of lyso-PE catalyzed by the acyl-CoA-dependent acyltransferase Ale1p in the mitochondria associated endoplasmic reticulum membrane (MAM). Deletion of PSD1 and/or PSD2 led to depletion of total cellular and plasma membrane PE level, whereas mutation in the other pathways had practically no effect. Analysis of wild type and mutants, however, revealed that all four routes of PE synthesis contributed not only to PE formation but also to the supply of PE to the plasma membrane. Pulse-chase labeling experiments with L[³H(G)]serine and [¹⁴C]ethanolamine confirmed the latter finding. Fatty acid profiling demonstrated a rather balanced incorporation of PE species into the plasma membrane irrespective of mutations suggesting that all four pathways of PE synthesis provide at least a basic portion of “correct” PE species required for plasma membrane biogenesis. In summary, the PE level in the plasma membrane is strongly influenced by total cellular PE synthesis, but fine tuned by selective assembly mechanisms.     

Reducing the impact of pesticides on biological control in Australian vineyards: pesticide mortality and fecundity effects on an indicator species, the predatory mite Euseius victoriensis (Acari: Phytoseiidae)

Laboratory bioassays on detached soybean, Glycine max (L.) Merr., leaves were used to test 23 fungicides, five insecticides, two acaricides, one herbicide, and two adjuvants on a key Australian predatory mite species Euseius victoriensis (Womersley) in "worst-case scenario" direct overspray assays. Zero- to 48-h-old juveniles, their initial food, and water supply were sprayed to runoff with a Potter tower; spinosad and wettable sulfur residues also were tested. Tests were standardized to deliver a pesticide dose comparable with commercial application of highest label rates at 1,000 liter/ha. Cumulative mortality was assessed 48 h, 4 d, and 7 d after spraying. Fecundity was assessed for 7 d from start of oviposition. No significant mortality or fecundity effects were detected for the following compounds at single-use application at 1,000 liter/ha: azoxystrobin, Bacillus thuringiensis (Bt) subsp. kurstaki, captan, chlorothalonil, copper hydroxide, fenarimol, glyphosate, hexaconazole, indoxacarb, metalaxyl/copper hydroxide, myclobutanil, nonyl phenol ethylene oxide, phosphorous acid, potassium bicarbonate, pyraclostrobin, quinoxyfen, spiroxamine, synthetic latex, tebufenozide, triadimenol, and trifloxystrobin. Iprodione and penconazole had some detrimental effect on fecundity. Canola oil as acaricide (2 liter/100 liter) and wettable sulfur (200 g/100 liter) had some detrimental effect on survival and fecundity and cyprodinil/fludioxonil on survivor. The following compounds were highly toxic (high 48-h mortality): benomyl, carbendazim, emamectin benzoate, mancozeb, spinosad (direct overspray and residue), wettable sulfur (> or = 400 g/100 liter), and pyrimethanil; pyrimethanil had no significant effect on fecundity of surviving females. Indoxacarb safety to E. victoriensis contrasts with its toxicity to key parasitoids and chrysopid predators. Potential impact of findings is discussed.