ORCID Profile
0000-0002-5019-4822
Current Organisation
Stockholm University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Cold Spring Harbor Laboratory
Date: 11-09-2020
DOI: 10.1101/2020.09.10.291559
Abstract: Photosynthetic bacteria from the class Chlorobia (formerly phylum Chlorobi ) sustain carbon fixation in anoxic water columns. They harvest light at extremely low intensities and use various inorganic electron donors to fix carbon dioxide into biomass. Until now, most information on their functional ecology and local adaptations came from isolates and merely 26 sequenced genomes that are poor representatives of natural populations. To address these limitations, we analyzed global metagenomes to profile planktonic Chlorobia cells from the oxyclines of 42 freshwater bodies, spanning subarctic to tropical regions and encompassing all four seasons. We assembled and compiled over 500 genomes, including metagenome-assembled genomes (MAGs), single-cell genomes (SAGs), and reference genomes from cultures, clustering them into 71 metagenomic operational taxonomic units (mOTUs) or “species”. Of the 71 mOTUs, 57 were classified as genus Chlorobium and these mOTUs varied in relative abundance up to ~60% of the microbial communities in the s led anoxic waters. Several Chlorobium -associated mOTUs were globally distributed whereas others were endemic to in idual lakes. Although most clades encoded the ability to oxidize hydrogen, many were lacking genes for the oxidation of specific sulfur and iron substrates. Surprisingly, one globally distributed Scandinavian Chlorobium clade encoded the ability to oxidize hydrogen, sulfur, and iron, suggesting that metabolic versatility facilitated such widespread colonization. Overall, these findings provide new insights into the biogeography of the Chlorobia and the metabolic traits that facilitate niche specialization within lake ecosystems. The reconstruction of genomes from metagenomes has enabled unprecedented insights into the ecology and evolution of environmental microbiomes. We applied this powerful approach to 274 metagenomes collected from erse freshwater habitats that spanned oxic and anoxic zones, s ling seasons, and latitudes. We demonstrate widespread and abundant distributions of planktonic Chlorobia -associated bacteria in hypolimnetic waters of stratified freshwater ecosystems and pinpoint nutrients that likely fuel their electron chains. Being photoautotrophs, these Chlorobia organisms also have the potential to serve as carbon sources that support metalimnetic and hypolimnetic food webs.
Publisher: American Physiological Society
Date: 08-2022
DOI: 10.1152/AJPENDO.00371.2021
Abstract: We show that nitrate supplementation increased force production during fatigue and increased submaximal SERCA activity. This was also evident regarding the high-energy phosphate transfer from SERCA to mitochondria, as nitrate increased mitochondrial respiration supported by SERCA-derived ADP. Surprisingly, these observations were only apparent in muscle primarily expressing type I (soleus) but not type II fibers (EDL). These findings suggest that alterations in SERCA properties are a possible mechanism in which nitrate increases force during fatiguing contractions.
Publisher: American Society for Microbiology
Date: 29-06-2021
DOI: 10.1128/MSYSTEMS.01196-20
Abstract: The reconstruction of genomes from metagenomes has helped explore the ecology and evolution of environmental microbiota. We applied this approach to 274 metagenomes collected from erse freshwater habitats that spanned oxic and anoxic zones, s ling seasons, and latitudes.
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
DOI: 10.1038/S41587-020-0718-6
Abstract: The reconstruction of bacterial and archaeal genomes from shotgun metagenomes has enabled insights into the ecology and evolution of environmental and host-associated microbiomes. Here we applied this approach to ,000 metagenomes collected from erse habitats covering all of Earth’s continents and oceans, including metagenomes from human and animal hosts, engineered environments, and natural and agricultural soils, to capture extant microbial, metabolic and functional potential. This comprehensive catalog includes 52,515 metagenome-assembled genomes representing 12,556 novel candidate species-level operational taxonomic units spanning 135 phyla. The catalog expands the known phylogenetic ersity of bacteria and archaea by 44% and is broadly available for streamlined comparative analyses, interactive exploration, metabolic modeling and bulk download. We demonstrate the utility of this collection for understanding secondary-metabolite biosynthetic potential and for resolving thousands of new host linkages to uncultivated viruses. This resource underscores the value of genome-centric approaches for revealing genomic properties of uncultivated microorganisms that affect ecosystem processes.
Publisher: Wiley
Date: 19-08-2020
DOI: 10.1113/JP280032
Publisher: Wiley
Date: 24-05-2017
DOI: 10.1113/JP274036
Publisher: American Diabetes Association
Date: 22-02-2023
DOI: 10.2337/DB22-0575
Abstract: Identifying therapeutic approaches that prevent cardiometabolic diseases are clearly important, and nitrate represents one such potential compound given its multifactorial metabolic effects. We aimed to determine whether nitrate could prevent high-fat diet (HFD)–induced cardiac abnormalities and whether this was dependent on the gut microbiome. Dietary nitrate attenuated HFD-induced pathological changes in cardiac remodelling, left ventricle reactive oxygen species, adipose inflammation, lipid homeostasis, glucose intolerance, and gut dysbiosis. Fecal microbial transplantation from nitrate-fed mice also prevented serum dyslipidemia, left ventricle reactive oxygen species, glucose intolerance, and cardiac dysfunction. Therefore, the cardioprotective effects of nitrate are related to mitigating gut dysbiosis, highlighting a nitrate-gut-heart axis.
Publisher: Wiley
Date: 07-07-2019
DOI: 10.1113/JP277765
Publisher: Wiley
Date: 26-12-2019
DOI: 10.1113/JP278920
Publisher: Wiley
Date: 28-06-2023
DOI: 10.1113/JP284701
Abstract: Skeletal muscle disuse reduces muscle protein synthesis rates and induces atrophy, events associated with decreased mitochondrial respiration and increased reactive oxygen species. Given that dietary nitrate can improve mitochondrial bioenergetics, we examined whether nitrate supplementation attenuates disuse‐induced impairments in mitochondrial function and muscle protein synthesis rates. Female C57Bl/6N mice were subjected to single‐limb casting (3 or 7 days) and consumed drinking water with or without 1 m M sodium nitrate. Compared with the contralateral control limb, 3 days of immobilization lowered myofibrillar fractional synthesis rates (FSR, P 0.0001), resulting in muscle atrophy. Although FSR and mitophagy‐related proteins were higher in subsarcolemmal (SS) compared with intermyofibrillar (IMF) mitochondria, immobilization for 3 days decreased FSR in both SS ( P = 0.009) and IMF ( P = 0.031) mitochondria. Additionally, 3 days of immobilization reduced maximal mitochondrial respiration, decreased mitochondrial protein content, and increased maximal mitochondrial reactive oxygen species emission, without altering mitophagy‐related proteins in muscle homogenate or isolated mitochondria (SS and IMF). Although nitrate consumption did not attenuate the decline in muscle mass or myofibrillar FSR, intriguingly, nitrate completely prevented immobilization‐induced reductions in SS and IMF mitochondrial FSR. In addition, nitrate prevented alterations in mitochondrial content and bioenergetics after both 3 and 7 days of immobilization. However, in contrast to 3 days of immobilization, nitrate did not prevent the decline in SS and IMF mitochondrial FSR after 7 days of immobilization. Therefore, although nitrate supplementation was not sufficient to prevent muscle atrophy, nitrate may represent a promising therapeutic strategy to maintain mitochondrial bioenergetics and transiently preserve mitochondrial protein synthesis rates during short‐term muscle disuse. image Alterations in mitochondrial bioenergetics (decreased respiration and increased reactive oxygen species) are thought to contribute to muscle atrophy and reduced protein synthesis rates during muscle disuse. Given that dietary nitrate can improve mitochondrial bioenergetics, we examined whether nitrate supplementation could attenuate immobilization‐induced skeletal muscle impairments in female mice. Dietary nitrate prevented short‐term (3 day) immobilization‐induced declines in mitochondrial protein synthesis rates, reductions in markers of mitochondrial content, and alterations in mitochondrial bioenergetics. Despite these benefits and the preservation of mitochondrial content and bioenergetics during more prolonged (7 day) immobilization, nitrate consumption did not preserve skeletal muscle mass or myofibrillar protein synthesis rates. Overall, although dietary nitrate did not prevent atrophy, nitrate supplementation represents a promising nutritional approach to preserve mitochondrial function during muscle disuse.
No related grants have been discovered for Graham Holloway.