Unraveling the nuclear and chloroplast genomes of an agar producing red macroalga, Gracilaria changii (Rhodophyta, Gracilariales)

Agar and agarose have wide applications in food and pharmaceutical industries. Knowledge on the genome of red seaweeds that produce them is still lacking. To fill the gap in genome analyses of these red algae, we have sequenced the nuclear and organellar genomes of an agarophyte, Gracilaria changii. The partial nuclear genome sequence of G. changii has a total length of 35.8 Mb with 10,912 predicted protein coding sequences. Only 39.4% predicted proteins were found to have significant matches to protein sequences in SwissProt. The chloroplast genome of G. changii is 183,855 bp with a total of 201 open reading frames (ORFs), 29 tRNAs and 3 rRNAs predicted. Five genes: ssrA, leuC and leuD CP76_p173 (orf139) and pbsA were absent in the chloroplast genome of G. changii. The genome information is valuable in accelerating functional studies of individual genes and resolving evolutionary relationship of red seaweeds

Global transcriptome analysis of Gracilaria changii (Rhodophyta) in response to agarolytic enzyme and bacterium

Many bacterial epiphytes of agar-producing seaweeds secrete agarase that degrade algal cell wall matrix into oligoagars which elicit defense-related responses in the hosts. The molecular defense responses of red seaweeds are largely unknown. In this study, we surveyed the defense-related transcripts of an agarophyte, Gracilaria changii, treated with β-agarase through next generation sequencing (NGS). We also compared the defense responses of seaweed elicited by agarase with those elicited by an agarolytic bacterium isolated from seaweed, by profiling the expression of defense-related genes using quantitative reverse transcription real-time PCR (qRT-PCR). NGS detected a total of 391 differentially expressed genes (DEGs) with a higher abundance (>2-fold change with a p value <0.001) in the agarase-treated transcriptome compared to that of the non-treated G. changii. Among these DEGs were genes related to signaling, bromoperoxidation, heme peroxidation, production of aromatic amino acids, chorismate, and jasmonic acid. On the other hand, the genes encoding a superoxide-generating NADPH oxidase and related to photosynthesis were downregulated. The expression of these DEGs was further corroborated by qRT-PCR results which showed more than 90 % accuracy. A comprehensive analysis of their gene expression profiles between 1 and 24 h post treatments (hpt) revealed that most of the genes analyzed were consistently upregulated or downregulated by both agarase and agarolytic bacterial treatments, indicating that the defense responses induced by both treatments are highly similar except for genes encoding vanadium bromoperoxidase and animal heme peroxidase. Our study has provided the first glimpse of the molecular defense responses of G. changii to agarase and agarolytic bacterial treatments

Analyses of Putative genes involved in the defense mechanism of Gracilaria changii in response to agarase and agarolytic bacteria treatments

Seaweed Gracilaria is the main source of agar worldwide. Information on the induced defense mechanisms of seaweed is scarce, particularly in the aspect of seaweed-microbe interactions. A set of differentially expressed genes from G.changii in response to agarase were generated from a previous study through next generation sequencing of the seaweed transcriptomes. In this study, G. changii was treated with both agarase (which generates the microbe-induced molecular patterns) and a marine agarolytic bacteria, ABS1 isolated from degrading seaweed. The result from the previous study (agarase treatment) was verified and temporal gene expression of candidate genes at 1, 6 and 24 hours post-treatment (hpt) in response to both agarase and bacteria treatments was profiled by quantitative reversetranscription real-time PCR (qRT-PCR). A total of 20 out of 22 candidates verified have the same gene expression patterns as the next generation sequencing result,demonstrating a 90.9% positive correlation between the two analyses. Four candidates encoding plasma membrane calcium-transporting ATPase (GcPMCA),vanadium bromoperoxidase type 1 (GcVBPO1), 3-phosphoshikimate 1-carbpxyvinyltransferase (GcEPSP), and 12-oxophytodienoate reductase (GcOPR) showed more than 2-fold up-regulation compared to that of control samples upon agarase treatment, implying their importance in defense response. The gene encoding vanadium bromoperoxidase type 2 (GcVBPO2) showed more than 2-fold up-regulation compared to that of the control sample upon bacteria treatment. GcVBPO1 and GcVBPO2 displayed different expression profiles in response to the two treatments, indicating the existence of more than one signaling pathways in the transcriptional regulation of vanadium bromoperoxidase. The gene expression of 16 and 10 candidates were further profiled in agarase and bacteria treated samples at different time points, respectively. Most candidates were up-regulated at 1 hpt compared to that of the control sample at the same time point, indicating a rapid modulation of transcription in G. changii upon agarase treatment. The gene expression of these candidates displayed different expression profiles in bacteria treated samples. GcEPSP and GcVBPO2, were found to have the highest fold change when treated by agarase and agarolytic bacteria respectively, at 1 hpt. Temporal gene expression profile of candidates upon agarase and bacteria treatments in G. changii

Reversal of Ampicillin Resistance in MRSA via Inhibition of Penicillin-Binding Protein 2a by Acalypha wilkesiana

The inhibitory activity of a semipure fraction from the plant, Acalypha wilkesiana assigned as 9EA-FC-B, alone and in combination with ampicillin, was studied against methicillin-resistant Staphylococcus aureus (MRSA). In addition, effects of the combination treatment on PBP2a expression were investigated. Microdilution assay was used to determine the minimal inhibitory concentrations (MIC). Synergistic effects of 9EA-FC-B with ampicillin were determined using the fractional inhibitory concentration (FIC) index and kinetic growth curve assay. Western blot experiments were carried out to study the PBP2a expression in treated MRSA cultures. The results showed a synergistic effect between ampicillin and 9EA-FC-B treatment with the lowest FIC index of 0.19 (synergism ≤ 0.5). The presence of 9EA-FC-B reduced the MIC of ampicillin from 50 to 1.56 μg mL−1. When ampicillin and 9EA-FC-B were combined at subinhibitory level, the kinetic growth curves were suppressed. The antibacterial effect of 9EA-FC-B and ampicillin was shown to be synergistic. The synergism is due the ability of 9EA-FC-B to suppress the activity of PBP2a, thus restoring the susceptibility of MRSA to ampicillin. Corilagin was postulated to be the constituent responsible for the synergistic activity showed by 9EA-FC-B

Qu'est-ce qui rend la recherche en éducation efficace – Études de cas de projets de recherche à Singapour

This study aims to address the gap in understanding the impact arising from education research, researcher collaborations with stakeholders, and knowledge mobilization activities in Singapore. Eight cases of local research projects are used to understand the phenomenon of research impact in different context-specific settings. The findings reveal differing perceptions of impact among research users and researchers, and cohesion on the factors that contribute to research impact. Drawing from the findings, the authors propose three emerging principles that can enhance research impact efforts: a) frontloading the intended research impact, b) building mutualistic relationships, and c) co-constructing research. The findings and emerging questions from the study contribute to the growing body of scholarship to help researchers and stakeholders strengthen the research-practice-policy nexus.Cette étude vise à améliorer la compréhension de l’impact qu’ont à Singapour la recherche en éducation, les collaborations entre chercheurs et parties prenantes, et les activités de mobilisation des connaissances. Les auteurs se fondent sur huit cas de projets de recherche locaux afin de comprendre l’impact de la recherche dans divers contextes spécifiques. Les résultats révèlent des perceptions différentes de l’impact parmiles chercheurs et les utilisateurs de la recherche, avec en même temps un accord entre ceux-ci sur quels facteurs contribuent à cet impact. Sur la base des résultats obtenus, les auteurs proposent trois principes émergents susceptibles d’améliorer les efforts en matière d’impact de la recherche : a) l’utilité de mettre au premier plan l’impact désiré pour la recherche, b) celle d’établir des relations de réciprocité, et c) celle de coconstruire la recherche. Les résultats et questions provenant de cette étude apportent une contribution au corpus croissant de recherches visant à aider les chercheurs et les parties prenantes à renforcer les liens entre recherche, pratique et politique