Prevalence of Viral Frequency-Dependent Infection in Coastal Marine Prokaryotes Revealed Using Monthly Time Series Virome Analysis

海洋微生物も”密”ならウイルスに感染する --頻度依存的なウイルス感染を大阪湾で実証--. 京都大学プレスリリース. 2023-02-24.Viruses infecting marine prokaryotes have a large impact on the diversity and dynamics of their hosts. Model systems suggest that viral infection is frequency dependent and constrained by the virus-host encounter rate. However, it is unclear whether frequency-dependent infection is pervasive among the abundant prokaryotic populations with different temporal dynamics. To address this question, we performed a comparison of prokaryotic and viral communities using 16S rRNA amplicon and virome sequencing based on samples collected monthly for 2 years at a Japanese coastal site, Osaka Bay. Concurrent seasonal shifts observed in prokaryotic and viral community dynamics indicated that the abundance of viruses correlated with that of their predicted host phyla (or classes). Cooccurrence network analysis between abundant prokaryotes and viruses revealed 6, 423 cooccurring pairs, suggesting a tight coupling of host and viral abundances and their “one-to-many” correspondence. Although stable dominant species, such as SAR11, showed few cooccurring viruses, a fast succession of their viruses suggests that viruses infecting these populations changed continuously. Our results suggest that frequency-dependent viral infection prevails in coastal marine prokaryotes regardless of host taxa and temporal dynamics

Diel cycling of the cosmopolitan abundant Pelagibacter virus 37‐F6: one of the most abundant viruses on earth

The spatiotemporal dynamics for marine viral populations has only recently been explored. However, nothing is known about temporal activities of the uncultured Pelagibacter virus vSAG 37‐F6, which was discovered by single‐virus genomics as potentially the most abundant marine virus. Here, we investigate the diel cycling of 37‐F6 virus and the putative SAR11 host using coastal and oceanic transcriptomic and viromic time‐series data from Osaka Bay and North Pacific Subtropical Gyre. Virus 37‐F6 and relatives displayed diel cycling of transcriptional activities synchronized with its putative host. In both virus and host, the lowest transcription rates were observed at 14:00–15:00, coinciding roughly with maximum solar irradiance, while higher transcriptional rates were detected during the night/early morning and afternoon. Diel abundance of free viruses of 37‐F6 in seawater roughly mirrored the transcriptional activities of both virus and host. In Osaka Bay, among viral relatives (genus level), virus 37‐F6 specifically showed the highest ratio of transcriptional activity to virome abundance, a proxy for viral transcriptional activity relative to free viral particle abundance. This high ratio suggests high infection rate efficiencies in vSAG 37‐F6 virus compared to viral relatives. Thus, time‐series data revealed temporal transcript activities in one of the most abundant viruses in Earth.This work has been supported by Spanish Ministry of Economy and Competitiveness to MMG (Ref. RTI2018-094248-B-100), Generalitat Valenciana to FMH (ACIF/2015/332), and Gordon and Betty Moore Foundation to MMG (grant 5334). Gordon and Betty Moore Foundation to EFD (3777) and Simons Foundation Grant #329108 (to EFD)

Th17-Dependent Nasal Hyperresponsiveness Is Mitigated by Steroid Treatment

Th17 cells are implicated in allergic inflammatory diseases, including allergic rhinitis (AR), though the effect of steroids on Th17 cell-dependent nasal responses is unclear. Herein, we investigated a nasal inflammation model elicited by allergen provocation in mice infused with Th17 cells and its responsiveness against steroid treatment. We transferred BALB/c mice with Th17 cells, which were differentiated in vitro and showed a specific reaction to ovalbumin (OVA). We challenged the transferred mice by intranasal injection of OVA and to some of them, administered dexamethasone (Dex) subcutaneously in advance. Then, we assessed immediate nasal response (INR), nasal hyperresponsiveness (NHR), and inflammatory cell infiltration into the nasal mucosa. The significant nasal inflammatory responses with massive neutrophil accumulation, INR, and NHR were induced upon allergen challenge. Allergen-induced INR and NHR were significantly suppressed by Dex treatment. This study suggested the effectiveness of steroids on Th17 cell-mediated nasal responses in AR

Year-round dynamics of amplicon sequence variant communities differ among eukaryotes, Imitervirales , and prokaryotes in a coastal ecosystem

International audienceAbstract Coastal microbial communities are affected by seasonal environmental change, biotic interactions, and fluctuating nutrient availability. We investigated the seasonal dynamics of communities of eukaryotes, a major group of double-stranded DNA viruses that infect eukaryotes (order Imitervirales; phylum Nucleocytoviricota), and prokaryotes in the Uranouchi Inlet, Kochi, Japan. We performed metabarcoding using ribosomal RNA genes and viral polB genes as markers in 43 seawater samples collected over 20 months. Eukaryotes, prokaryotes, and Imitervirales communities characterized by the compositions of amplicon sequence variants (ASVs) showed synchronic seasonal cycles. However, the community dynamics showed intriguing differences in several aspects, such as the recovery rate after a year. We also showed that the differences in community dynamics were at least partially explained by differences in recurrence/persistence levels of individual ASVs among eukaryotes, prokaryotes, and Imitervirales. Prokaryotic ASVs were the most persistent, followed by eukaryotic ASVs and Imitervirales ASVs, which were the least persistent. We argue that the differences in the specificity of interactions (virus–eukaryote vs. prokaryote–eukaryote) as well as the niche breadth of community members were at the origin of the distinct community dynamics among eukaryotes, their viruses, and prokaryotes

An Optimized Metabarcoding Method for Mimiviridae

International audienceMimiviridae is a group of viruses with large genomes and virions. Ecological relevance of Mimiviridae in marine environments has been increasingly recognized through the discoveries of novel isolates and metagenomic studies. To facilitate ecological profiling of Mimiviridae, we previously proposed a meta-barcoding approach based on 82 degenerate primer pairs (i.e., MEGAPRIMER) targeting the DNA polymerase gene of Mimiviridae. The method detected a larger number of operational taxonomic units (OTUs) in environmental samples than previous methods. However, it required large quantities of DNA and was laborious due to the use of individual primer pairs. Here, we examined coastal seawater samples using varying PCR conditions and purification protocols to streamline the MEGAPRIMER method. Mixing primer pairs in "cocktails" reduced the required amount of environmental DNA by 90%, while reproducing the results obtained by the original protocol. We compared the results obtained by the meta-barcoding approach with quantifications using qPCR for selected OTUs. This revealed possible amplification biases among different OTUs, but the frequency profiles for individual OTUs across multiple samples were similar to those obtained by qPCR. We anticipate that the newly developed MEGAPRIMER protocols will be useful for ecological investigation of Mimiviridae in a larger set of environmental samples

Controlled Delivery of Basic Fibroblast Growth Factor Promotes Human Cardiosphere-Derived Cell Engraftment to Enhance Cardiac Repair for Chronic Myocardial Infarction

ObjectivesThis study was designed to determine whether controlled release of basic fibroblast growth factor (bFGF) might improve human cardiosphere-derived cell (hCDC) therapy in a pig model of chronic myocardial infarction.BackgroundCurrent cell therapies for cardiac repair are limited by loss of the transplanted cells and poor differentiation.MethodsWe conducted 2 randomized, placebo-controlled studies in immunosuppressed pigs with anterior myocardial infarctions. Four weeks after coronary reperfusion, 14 pigs were randomly assigned to receive an intramyocardial injection of placebo medium with or without bFGF-incorporating hydrogel implantation. As a second study, 26 pigs were randomized to receive controlled release of bFGF combined with or without hCDCs or bone marrow–derived mesenchymal stem cell transplantation 4 weeks after reperfusion.ResultsControlled release of bFGF in ischemic myocardium significantly augmented the formation of microvascular networks to enhance myocardial perfusion and contractile function. When combined with cell transplantation, the additive effects of bFGF were confined to hCDC-injected animals, but were not observed in animals receiving human bone marrow–derived mesenchymal stem cell transplantation. This was shown by increased donor-cell engraftment and enhanced cardiomyocyte differentiation in the transplanted hearts, resulting in synergistically improved ventricular function and regional wall motion and reduced infarct size.ConclusionsControlled delivery of bFGF modulates the post-ischemic microenvironment to enhance hCDC engraftment and differentiation. This novel strategy demonstrates significant functional improvements after myocardial infarction and may potentially represent a therapeutic approach to be studied in a clinical trial in human heart failure

福岡演習林の見本林（Ⅱ）

九州大学農学部附属演習林福岡演習林の第９次森林管理計画書（2015 〜 2024 年度）において設定された見本林のうち，クスノキ見本林，外国産ヒノキ科見本林，ヒノキ見本林，高田外国産樹種見本林における調査区の設置および林分調査を行った。クスノキ見本林の調査区（400m2）では，胸高断面積合計の91% をクスノキが占めた。37 本のクスノキの平均胸高直径は42.0cm で，稚樹は見られなかった。外国産ヒノキ見本林では，コウヨウザンが18 本，ランダイスギが７本生残していた。それぞれ平均胸高直径は33.4cm，32.0cm，平均樹高は19.7m，20.6m であった。ヒノキ見本林は，立木密度が425 本/ha, 胸高断面積合計が64.2m2/ha，平均胸高直径が43.7cm，平均樹高が25.6m であった。高田外国産樹種見本林には，胸高周囲長15cm 以上の樹木が75 種2955 本生育していた。これは1935 年の見本林整備当時と比較すると，樹種数で七分の一以下，個体数で約半分程度であった。The ninth Kasuya Research Forest Management Plan (2015-2024) designated the model forests with characteristic standstructure and species composition in the Research Forest. We surveyed the stands of Cinnamomum camphola model forest, foreignCupressaceae species model forest, Chamaecyparis obtusa model forest, and Takada foreign tree species model forest. In themonitoring plot (400m2) of the C. camphola model forest, 91% of the basal area was composed by C. camphola. The mean diameter atbreast height (DBH) of 37 C. camphola trees was 42.0cm. There was no C. camphola sapling in the plot. In the foreign Cupressaceaespecies model forest, 18 Cunninghamia lanceolate trees and 7 Cunninghamia konishii trees survived. The mean DBHs and meanheights of the two species were 33.4 cm and 32.0 cm, and 19.7m and 20.6m, respectively. In the Chamaecyparis obtusa model forest,the tree density, basal area, mean DBH and mean height were 425 tree / ha, 64.2m2/ha, 43.7cm and 25.6m, respectively. In the Takadaforeign tree species model forest, there were 75 species of 2955 trees larger than 15cm in girth at breast height. These values are lessthan one seventh for species number and less than one half for the tree number comparing with those in 1935 when the model forestwas established