Environmental fluctuations accelerate molecular evolution of thermal tolerance in a marine diatom

This is the final version of the article. Available from Springer Nature via the DOI in this recordThe publisher correction to this article is in ORE at: http://hdl.handle.net/10871/34487Diatoms contribute roughly 20% of global primary production, but the factors determining their ability to adapt to global warming are unknown. Here we quantify the capacity for adaptation to warming in the marine diatom Thalassiosira pseudonana. We find that evolutionary rescue under severe (32 °C) warming is slow, but adaptation to more realistic scenarios where temperature increases are moderate (26 °C) or fluctuate between benign and severe conditions is rapid and linked to phenotypic changes in metabolic traits and elemental composition. Whole-genome re-sequencing identifies genetic divergence among populations selected in the different warming regimes and between the evolved and ancestral lineages. Consistent with the phenotypic changes, the most rapidly evolving genes are associated with transcriptional regulation, cellular responses to oxidative stress and redox homeostasis. These results demonstrate that the evolution of thermal tolerance in marine diatoms can be rapid, particularly in fluctuating environments, and is underpinned by major genomic and phenotypic change.This study was funded by a Leverhulme Trust research grant (RPG-2013-335). Whole genome re-sequencing was carried out at Exeter Sequencing Service and Computational core facilities at the University of Exeter, where Dr. Karen Moore, Dr. Audrey Farbos, Paul O’Neill, and Dr. Konrad Paszkiewicz lead the handling of the samples. Exeter Squencing Services are supported by Medical Research Council Clinical Infrastructure award (MR/M008924/1), Wellcome Trust Institutional Strategic Support Fund (WT097835MF), Wellcome Trust Multi User Equipment Award (WT101650MA), and BBSRC LOLA award (BB/K003240/1)

Publisher Correction: Environmental fluctuations accelerate molecular evolution of thermal tolerance in a marine diatom

The article for which this is the publisher correction is in ORE at: http://hdl.handle.net/10871/32652The PDF version of this Article was updated shortly after publication following an error which resulted in the Φ symbol being omitted from the left hand side of equation 8. The HTML version was correct from the time of publication

Self-incompatibility triggers irreversible oxidative modification of proteins in incompatible pollen

Self-incompatibility (SI) is used by many angiosperms to prevent self-fertilization and inbreeding. In common poppy (Papaver rhoeas), interaction of cognate pollen and pistil S-determinants triggers programmed cell death (PCD) of incompatible pollen. We previously identified that reactive oxygen species (ROS) signal to SI-PCD. ROS-induced oxidative posttranslational modifications (oxPTMs) can regulate protein structure and function. Here, we have identified and mapped oxPTMs triggered by SI in incompatible pollen. Notably, SI-induced pollen had numerous irreversible oxidative modifications, while untreated pollen had virtually none. Our data provide a valuable analysis of the protein targets of ROS in the context of SI-induction and comprise a benchmark because currently there are few reports of irreversible oxPTMs in plants. Strikingly, cytoskeletal proteins and enzymes involved in energy metabolism are a prominent target of ROS. Oxidative modifications to a phosphomimic form of a pyrophosphatase result in a reduction of its activity. Therefore, our results demonstrate irreversible oxidation of pollen proteins during SI and provide evidence that this modification can affect protein function. We suggest that this reduction in cellular activity could lead to PCD

An update: improvements in imaging perfluorocarbon-mounted plant leaves with implications for studies of plant pathology, physiology, development and cell biology.

Plant leaves are optically complex, which makes them difficult to image by light microscopy. Careful sample preparation is therefore required to enable researchers to maximize the information gained from advances in fluorescent protein labeling, cell dyes and innovations in microscope technologies and techniques. We have previously shown that mounting leaves in the non-toxic, non-fluorescent perfluorocarbon (PFC), perfluorodecalin (PFD) enhances the optical properties of the leaf with minimal impact on physiology. Here, we assess the use of the PFCs, PFD, and perfluoroperhydrophenanthrene (PP11) for in vivo plant leaf imaging using four advanced modes of microscopy: laser scanning confocal microscopy (LSCM), two-photon fluorescence microscopy, second harmonic generation microscopy, and stimulated Raman scattering (SRS) microscopy. For every mode of imaging tested, we observed an improved signal when leaves were mounted in PFD or in PP11, compared to mounting the samples in water. Using an image analysis technique based on autocorrelation to quantitatively assess LSCM image deterioration with depth, we show that PP11 outperformed PFD as a mounting medium by enabling the acquisition of clearer images deeper into the tissue. In addition, we show that SRS microscopy can be used to image PFCs directly in the mesophyll and thereby easily delimit the "negative space" within a leaf, which may have important implications for studies of leaf development. Direct comparison of on and off resonance SRS micrographs show that PFCs do not to form intracellular aggregates in live plants. We conclude that the application of PFCs as mounting media substantially increases advanced microscopy image quality of living mesophyll and leaf vascular bundle cells

An Extracellular Polysaccharide-Rich Organic Layer Contributes to Organization of the Coccosphere in Coccolithophores

This is the final version. Available from Frontiers Media via the DOI in this record.Coccolithophores are globally abundant marine microalgae characterized by their ability to form calcite platelets (coccoliths). The coccoliths are produced internally in a Golgi-derived vesicle. Mature coccoliths are extruded from the cell to form a protective covering on the cell surface, known as the coccosphere. Current evidence indicates that calcite precipitation in the coccolith vesicle (CV) is modulated by coccolith-associated polysaccharides (CAPs). Whilst previous research into CAPs has focussed on their roles in calcite precipitation within the CV, little is known of their extracellular roles. Using fluorescent lectins, we visualize the extracellular polysaccharide-rich organic layer associated with external coccoliths and demonstrate that it differs between species in structure and composition. Biochemical analysis of polysaccharide extracted from coccoliths indicated substantial differences between species in monosaccharide composition and uronic acid content. In Coccolithus braarudii our studies indicate that polysaccharide-rich material is extruded with the coccoliths, where it plays a role in the adhesion of the coccoliths to the cell surface and contributes to the overall organization of the coccosphere. Together, these results highlight the important extracellular roles of CAPs and their contribution to the dynamic nature of the coccosphere.The authors acknowledge funding from NERC SPITFIRE DTP studentship to CW. GW and CB acknowledge support from NERC (NE/N011708/1) and the European Research Council (ERC-ADG 670390). CW was additionally supported by the Gillings Graduate Exchange Programme (University of Southampton/University of North Carolina Wilmington). AT acknowledges NSF support (NSFGEO-NERC-1638838)

Quantitative proteomics of a B12 -dependent alga grown in coculture with bacteria reveals metabolic tradeoffs required for mutualism

The unicellular green alga Lobomonas rostrata requires an external supply of vitamin B12 (cobalamin) for growth, which it can obtain in stable laboratory cultures from the soil bacterium Mesorhizobium loti in exchange for photosynthate. We investigated changes in protein expression in the alga that allow it to engage in this mutualism. We used quantitative isobaric tagging (iTRAQ) proteomics to determine the L. rostrata proteome grown axenically with B12 supplementation or in coculture with M. loti. Data are available via ProteomeXchange (PXD005046). Using the related Chlamydomonas reinhardtii as a reference genome, 588 algal proteins could be identified. Enzymes of amino acid biosynthesis were higher in coculture than in axenic culture, and this was reflected in increased amounts of total cellular protein and several free amino acids. A number of heat shock proteins were also elevated. Conversely, photosynthetic proteins and those of chloroplast protein synthesis were significantly lower in L. rostrata cells in coculture. These observations were confirmed by measurement of electron transfer rates in cells grown under the two conditions. The results indicate that, despite the stability of the mutualism, L. rostrata experiences stress in coculture with M. loti, and must adjust its metabolism accordingly.The work in this manuscript was supported by funding from the Biotechnology and Biological Sciences Research Council (BBSRC) of the UK (grant BB/I013164/1, a CASE studentship for M.B.C. joint with PML Applications Ltd, Plymouth, UK, and a DTP studentship for F.B.); an EU FP7 Marie Curie ITN Photo.Comm, no. 317184 for U.J.K.; Engineering and Physical Science Research Council (EPSRC) grant EP/E036252/1; and the Natural Environment Research Council (NERC) grant NE/J024767/1

Involvement of Nitrogen on Flavonoids, Glutathione, Anthocyanin, Ascorbic Acid and Antioxidant Activities of Malaysian Medicinal Plant Labisia pumila Blume (Kacip Fatimah)

A split plot 3 by 4 experiment was designed to characterize the relationship between production of gluthatione (GSH), oxidized gluthatione (GSSG), total flavonoid, anthocyanin, ascorbic acid and antioxidant activities (FRAP and DPPH) in three varieties of Labisia pumila Blume, namely the varieties alata, pumila and lanceolata, under four levels of nitrogen fertilization (0, 90, 180 and 270 kg N/ha) for 15 weeks. The treatment effects were solely contributed by nitrogen application; there was neither varietal nor interaction effects observed. As the nitrogen levels decreased from 270 to 0 kg N/ha, the production of GSH and GSSG, anthocyanin, total flavonoid and ascorbic acid increased steadily. At the highest nitrogen treatment level, L. pumila exhibited significantly lower antioxidant activities (DPPH and FRAP) than those exposed to limited nitrogen growing conditions. Significant positive correlation was obtained between antioxidant activities (DPPH and FRAP), total flavonoid, GSH, GSSG, anthocyanin and ascorbic acid suggesting that an increase in the antioxidative activities in L. pumila under low nitrogen fertilization could be attributed to higher contents of these compounds. From this observation, it could be concluded that in order to avoid negative effects on the quality of L. pumila, it is advisable to avoid excessive application of nitrogen fertilizer when cultivating the herb for its medicinal use

From functional food to medicinal product: Systematic approach in analysis of polyphenolics from propolis and wine

In the last decade we have been working on standardization of propolis extract and determination of active constituents of wine those are rich in polyphenolics and have nutritional as well as therapeutic value. Here we are summarizing our results and providing overview on systematic approach how to analyse natural products rich in flavonoids and phenolic acids

Computing Power and Sample Size for Case-Control Association Studies with Copy Number Polymorphism: Application of Mixture-Based Likelihood Ratio Test

Recent studies suggest that copy number polymorphisms (CNPs) may play an important role in disease susceptibility and onset. Currently, the detection of CNPs mainly depends on microarray technology. For case-control studies, conventionally, subjects are assigned to a specific CNP category based on the continuous quantitative measure produced by microarray experiments, and cases and controls are then compared using a chi-square test of independence. The purpose of this work is to specify the likelihood ratio test statistic (LRTS) for case-control sampling design based on the underlying continuous quantitative measurement, and to assess its power and relative efficiency (as compared to the chi-square test of independence on CNP counts). The sample size and power formulas of both methods are given. For the latter, the CNPs are classified using the Bayesian classification rule. The LRTS is more powerful than this chi-square test for the alternatives considered, especially alternatives in which the at-risk CNP categories have low frequencies. An example of the application of the LRTS is given for a comparison of CNP distributions in individuals of Caucasian or Taiwanese ethnicity, where the LRTS appears to be more powerful than the chi-square test, possibly due to misclassification of the most common CNP category into a less common category