scholarly journals Unravelling the Importance of Diazotrophy in Corals – Combined Assessment of Nitrogen Assimilation, Diazotrophic Community and Natural Stable Isotope Signatures

2021 ◽  
Vol 12 ◽  
Author(s):  
Vanessa N. Bednarz ◽  
Jeroen A. J. M. van de Water ◽  
Renaud Grover ◽  
Jean-François Maguer ◽  
Maoz Fine ◽  
...  
Keyword(s):  
Red Sea ◽  
Nitrogen Sources ◽  
Holistic Approach ◽  
Amplicon Sequencing ◽  
Nitrogen Budget ◽  
Stylophora Pistillata ◽  
Host Nutrition ◽  
Almost All ◽  
And Function ◽  
Northern Red Sea

There is an increasing interest in understanding the structure and function of the microbiota associated with marine and terrestrial organisms, because it can play a major role in host nutrition and resistance to environmental stress. Reef-building corals live in association with diazotrophs, which are microbes able to fix dinitrogen. Corals are known to assimilate diazotrophically-derived nitrogen (DDN), but it is still not clear whether this nitrogen source is derived from coral-associated diazotrophs and whether it substantially contributes to the coral’s nitrogen budget. In this study, we aimed to provide a better understanding of the importance of DDN for corals using a holistic approach by simultaneously assessing DDN assimilation rates (using 15N2 tracer technique), the diazotrophic bacterial community (using nifH gene amplicon sequencing) and the natural δ15N signature in Stylophora pistillata corals from the Northern Red Sea along a depth gradient in winter and summer. Overall, our results show a discrepancy between the three parameters. DDN was assimilated by the coral holobiont during winter only, with an increased assimilation with depth. Assimilation rates were, however, not linked to the presence of coral-associated diazotrophs, suggesting that the presence of nifH genes does not necessarily imply functionality. It also suggests that DDN assimilation was independent from coral-associated diazotrophs and may instead result from nitrogen derived from planktonic diazotrophs. In addition, the δ15N signature presented negative values in almost all coral samples in both seasons, suggesting that nitrogen sources other than DDN contribute to the nitrogen budget of corals from this region. This study yields novel insight into the origin and importance of diazotrophy for scleractinian corals from the Northern Red Sea using multiple proxies.

scholarly journals Mechanisms underlying gut microbiota–host interactions in insects

2021 ◽  
Vol 224 (2) ◽  
pp. jeb207696 ◽  
Author(s):  
Konstantin Schmidt ◽  
Philipp Engel
Keyword(s):  
Gut Microbiota ◽  
Molecular Mechanisms ◽  
Early Stage ◽  
Molecular Processes ◽  
General Introduction ◽  
Host Interactions ◽  
Host Nutrition ◽  
Insect Gut ◽  
Almost All ◽  
And Function

ABSTRACTInsects are the most diverse group of animals and colonize almost all environments on our planet. This diversity is reflected in the structure and function of the microbial communities inhabiting the insect digestive system. As in mammals, the gut microbiota of insects can have important symbiotic functions, complementing host nutrition, facilitating dietary breakdown or providing protection against pathogens. There is an increasing number of insect models that are experimentally tractable, facilitating mechanistic studies of gut microbiota–host interactions. In this Review, we will summarize recent findings that have advanced our understanding of the molecular mechanisms underlying the symbiosis between insects and their gut microbiota. We will open the article with a general introduction to the insect gut microbiota and then turn towards the discussion of particular mechanisms and molecular processes governing the colonization of the insect gut environment as well as the diverse beneficial roles mediated by the gut microbiota. The Review highlights that, although the gut microbiota of insects is an active field of research with implications for fundamental and applied science, we are still in an early stage of understanding molecular mechanisms. However, the expanding capability to culture microbiomes and to manipulate microbe–host interactions in insects promises new molecular insights from diverse symbioses.

scholarly journals A system in balance? – Implications of deep vertical mixing for the nitrogen budget in the northern Red Sea, including the Gulf of Aqaba (Eilat)

2006 ◽  
Vol 3 (2) ◽  
pp. 383-408 ◽  
Author(s):  
C. Häse ◽  
M. Al-Qutob ◽  
Z. Dubinsky ◽  
E. A. Ibrahim ◽  
B. Lazar ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Red Sea ◽  
Vertical Mixing ◽  
Indirect Evidence ◽  
N:P Ratio ◽  
Nitrogen Budget ◽  
Gulf Of Aqaba ◽  
Oligotrophic Water ◽  
Northern Red Sea ◽  
Nitrate Deficit

Abstract. We investigated the implications of deep winter mixing for the nitrogen budget in two adjacent systems, the northern Red Sea proper, and the Gulf of Aqaba. Both are subtropical oligotrophic water bodies. The main difference is that in the gulf deep winter mixing takes place regularly, whereas the northern Red Sea proper is permanently stratified. In the Gulf of Aqaba, we observed significantly lower nitrate deficits, i.e. deviations from the Redfield ratio, than in the northern Red Sea proper. Assuming that other external inputs and losses in N or P are very similar in both systems, the higher nitrate deficit can be explained by either lower nitrogen fixation in the (stratified) northern Red Sea, which seems unlikely. An alternative explanation would be higher rates of benthic denitrification than in the gulf. By comparing the two systems we have indirect evidence that benthic denitrification was much lower in the Gulf of Aqaba due to higher oxygen concentrations. This we attributed to the occurrence of deep winter mixing, and as a consequence, the nitrate deficit was close to zero (i.e. N:P ratio close to "Redfield"). If both nitrogen fixation and benthic denitrification take place, as in the northern Red Sea proper, the result was a positive nitrate deficit (i.e. a deficit in nitrate) in the ambient water. The nitrate deficit in the northern Red Sea was observed in spite of high iron deposition from the surrounding desert. Our results strongly support the concept of nitrogen as the proximate, and phosphate as the ultimate limiting nutrient for primary production in the sea. This must not be neglected in efforts for protecting the adjacent reefs against eutrophication.

scholarly journals Seasonal Mesophotic Coral Bleaching of Stylophora pistillata in the Northern Red Sea

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e84968 ◽  
Author(s):  
Orit Nir ◽  
David F. Gruber ◽  
Eli Shemesh ◽  
Eliezra Glasser ◽  
Dan Tchernov
Keyword(s):  
Red Sea ◽  
Coral Bleaching ◽  
Stylophora Pistillata ◽  
Northern Red Sea

scholarly journals Fast and pervasive transcriptomic resilience and acclimation of extremely heat-tolerant coral holobionts from the northern Red Sea

2021 ◽  
Vol 118 (19) ◽  
pp. e2023298118
Author(s):  
Romain Savary ◽  
Daniel J. Barshis ◽  
Christian R. Voolstra ◽  
Anny Cárdenas ◽  
Nicolas R. Evensen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Red Sea ◽  
Thermal Tolerance ◽  
Gulf Of Aqaba ◽  
Coral Host ◽  
Rna Seq ◽  
Gene Expression Response ◽  
Stylophora Pistillata ◽  
Northern Red Sea

Corals from the northern Red Sea and Gulf of Aqaba exhibit extreme thermal tolerance. To examine the underlying gene expression dynamics, we exposed Stylophora pistillata from the Gulf of Aqaba to short-term (hours) and long-term (weeks) heat stress with peak seawater temperatures ranging from their maximum monthly mean of 27 °C (baseline) to 29.5 °C, 32 °C, and 34.5 °C. Corals were sampled at the end of the heat stress as well as after a recovery period at baseline temperature. Changes in coral host and symbiotic algal gene expression were determined via RNA-sequencing (RNA-Seq). Shifts in coral microbiome composition were detected by complementary DNA (cDNA)-based 16S ribosomal RNA (rRNA) gene sequencing. In all experiments up to 32 °C, RNA-Seq revealed fast and pervasive changes in gene expression, primarily in the coral host, followed by a return to baseline gene expression for the majority of coral (>94%) and algal (>71%) genes during recovery. At 34.5 °C, large differences in gene expression were observed with minimal recovery, high coral mortality, and a microbiome dominated by opportunistic bacteria (including Vibrio species), indicating that a lethal temperature threshold had been crossed. Our results show that the S. pistillata holobiont can mount a rapid and pervasive gene expression response contingent on the amplitude and duration of the thermal stress. We propose that the transcriptomic resilience and transcriptomic acclimation observed are key to the extraordinary thermal tolerance of this holobiont and, by inference, of other northern Red Sea coral holobionts, up to seawater temperatures of at least 32 °C, that is, 5 °C above their current maximum monthly mean.

scholarly journals Contrasting seasonal responses in dinitrogen fixation between shallow and deep-water colonies of the model coral Stylophora pistillata in the northern Red Sea

PLoS ONE ◽  
2018 ◽  
Vol 13 (6) ◽  
pp. e0199022 ◽  
Author(s):  
Vanessa N. Bednarz ◽  
Malik S. Naumann ◽  
Ulisse Cardini ◽  
Nanne van Hoytema ◽  
Laura Rix ◽  
...  
Keyword(s):  
Red Sea ◽  
Deep Water ◽  
Dinitrogen Fixation ◽  
Stylophora Pistillata ◽  
Northern Red Sea ◽  
Seasonal Responses

scholarly journals Roles of HIF and 2-Oxoglutarate-Dependent Dioxygenases in Controlling Gene Expression in Hypoxia

Cancers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 350
Author(s):  
Julianty Frost ◽  
Mark Frost ◽  
Michael Batie ◽  
Hao Jiang ◽  
Sonia Rocha
Keyword(s):  
Gene Expression ◽  
Hypoxia Inducible Factor ◽  
Transcriptional Regulator ◽  
Hydroxylase Activity ◽  
Control Of Gene Expression ◽  
Prolyl Hydroxylases ◽  
Chromatin Organisation ◽  
Sense And Respond ◽  
Almost All ◽  
And Function

Hypoxia—reduction in oxygen availability—plays key roles in both physiological and pathological processes. Given the importance of oxygen for cell and organism viability, mechanisms to sense and respond to hypoxia are in place. A variety of enzymes utilise molecular oxygen, but of particular importance to oxygen sensing are the 2-oxoglutarate (2-OG) dependent dioxygenases (2-OGDs). Of these, Prolyl-hydroxylases have long been recognised to control the levels and function of Hypoxia Inducible Factor (HIF), a master transcriptional regulator in hypoxia, via their hydroxylase activity. However, recent studies are revealing that dioxygenases are involved in almost all aspects of gene regulation, including chromatin organisation, transcription and translation. We highlight the relevance of HIF and 2-OGDs in the control of gene expression in response to hypoxia and their relevance to human biology and health.

scholarly journals The Diversity of Root-Associated Endophytic Fungi from Four Epiphytic Orchids in China

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 197
Author(s):  
Tao Wang ◽  
Miao Chi ◽  
Ling Guo ◽  
Donghuan Liu ◽  
Yu Yang ◽  
...  
Keyword(s):  
Endophytic Fungi ◽  
Southern China ◽  
Culture Method ◽  
Amplicon Sequencing ◽  
Community Diversity ◽  
Mycorrhizal Symbiosis ◽  
Epiphytic Orchids ◽  
Culture Independent ◽  
Almost All

Root-associated endophytic fungi (RAF) are found asymptomatically in almost all plant groups. However, little is known about the compositions and potential functions of RAF communities associated with most Orchidaceae species. In this study, the diversity of RAF was examined in four wild epiphytic orchids, Acampe rigida, Doritis pulcherrima, Renanthera coccinea, and Robiquetia succisa, that occur in southern China. A culture-independent method involving Illumina amplicon sequencing, and an in vitro culture method, were used to identify culturable fungi. The RAF community diversity differed among the orchid roots, and some fungal taxa were clearly concentrated in a certain orchid species, with more OTUs being detected. By investigating mycorrhizal associations, the results showed that 28 (about 0.8%) of the 3527 operational taxonomic units (OTUs) could be assigned as OMF, while the OTUs of non-mycorrhizal fungal were about 99.2%. Among the OMFs, Ceratobasidiaceae OTUs were the most abundant with different richness, followed by Thelephoraceae. In addition, five Ceratobasidium sp. strains were isolated from D. pulcherrima, R. succisa, and R. coccinea roots with high separation rates. These culturable Ceratobasidium strains will provide materials for host orchid conservation and for studying the mechanisms underlying mycorrhizal symbiosis.

scholarly journals The Cross-Talk between Mesenchymal Stem Cells and Immune Cells in Tissue Repair and Regeneration

2021 ◽  
Vol 22 (5) ◽  
pp. 2472
Author(s):  
Carl Randall Harrell ◽  
Valentin Djonov ◽  
Vladislav Volarevic
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Immune Cells ◽  
Tissue Repair ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Multipotent Stem Cells ◽  
Tissue Repair And Regeneration ◽  
Almost All ◽  
And Function

Mesenchymal stem cells (MSCs) are self-renewable, rapidly proliferating, multipotent stem cells which reside in almost all post-natal tissues. MSCs possess potent immunoregulatory properties and, in juxtacrine and paracrine manner, modulate phenotype and function of all immune cells that participate in tissue repair and regeneration. Additionally, MSCs produce various pro-angiogenic factors and promote neo-vascularization in healing tissues, contributing to their enhanced repair and regeneration. In this review article, we summarized current knowledge about molecular mechanisms that regulate the crosstalk between MSCs and immune cells in tissue repair and regeneration.

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