Uncategorized Archive

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Int J Mol Sci.: auth.: W.Wahli

 2018 Jul 28;19(8). pii: E2210. doi: 10.3390/ijms19082210.

Enteric Microbiota⁻Gut⁻Brain Axis from the Perspective of Nuclear Receptors.

Abstract

Nuclear receptors (NRs) play a key role in regulating virtually all body functions, thus maintaining a healthy operating body with all its complex systems. Recently, gut microbiota emerged as major factor contributing to the health of the whole organism. Enteric bacteria have multiple ways to influence their host and several of them involve communication with the brain. Mounting evidence of cooperation between gut flora and NRs is already available. However, the full potential of the microbiota interconnection with NRs remains to be uncovered. Herewith, we present the current state of knowledge on the multifaceted roles of NRs in the enteric microbiota⁻gut⁻brain axis.

KEYWORDS:

metabolism; microbiota; nuclear receptors; xenobiotics

PMID: 30060580

 

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MBio.: co-auth.: GTF

 2018 Mar 20;9(2). pii: e00024-18. doi: 10.1128/mBio.00024-18.

In Vitro Culture of the Insect Endosymbiont Spiroplasma poulsonii Highlights Bacterial Genes Involved in Host-Symbiont Interaction.

Abstract

Endosymbiotic bacteria associated with eukaryotic hosts are omnipresent in nature, particularly in insects. Studying the bacterial side of host-symbiont interactions is, however, often limited by the unculturability and genetic intractability of the symbionts. Spiroplasma poulsoniiis a maternally transmitted bacterial endosymbiont that is naturally associated with several Drosophila species. S. poulsonii strongly affects its host’s physiology, for example by causing male killing or by protecting it against various parasites. Despite intense work on this model since the 1950s, attempts to cultivate endosymbiotic Spiroplasma in vitro have failed so far. Here, we developed a method to sustain the in vitro culture of S. poulsonii by optimizing a commercially accessible medium. We also provide a complete genome assembly, including the first sequence of a natural plasmid of an endosymbiotic Spiroplasma species. Last, by comparing the transcriptome of the in vitro culture to the transcriptome of bacteria extracted from the host, we identified genes putatively involved in host-symbiont interactions. This work provides new opportunities to study the physiology of endosymbiotic Spiroplasma and paves the way to dissect insect-endosymbiont interactions with two genetically tractable partners.IMPORTANCE The discovery of insect bacterial endosymbionts (maternally transmitted bacteria) has revolutionized the study of insects, suggesting novel strategies for their control. Most endosymbionts are strongly dependent on their host to survive, making them uncultivable in artificial systems and genetically intractable. Spiroplasma poulsonii is an endosymbiont of Drosophila that affects host metabolism, reproduction, and defense against parasites. By providing the first reliable culture medium that allows a long-lasting in vitro culture of Spiroplasma and by elucidating its complete genome, this work lays the foundation for the development of genetic engineering tools to dissect endosymbiosis with two partners amenable to molecular study. Furthermore, the optimization method that we describe can be used on other yet uncultivable symbionts, opening new technical opportunities in the field of host-microbes interactions.

KEYWORDS:

Spiroplasma; endosymbiosis; host-symbiont interaction

PMID: 29559567

 

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Organization of the sinks’ cleaning in the Génopode (2018)

Organization of the sinks’ cleaning in the Génopode – 2018

Groups members should make sure all the sinks in their labs are emptied on these dates, in order for the cleaning staff to proceed with their cleaning.

Link to the complete cleaning planing: http://unil.ch/cig/home/menuguid/faq/cleaning-and-waste-disposal.html

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Seminar on November 24th, 2017 : Ana Lopez-Vazquez

Capture d’écran 2017-11-14 à 18.14.51

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Diabetes Obes Metab.: co-auth.: group Thorens

Diabetes Obes Metab. 2017 Sep 11. doi: 10.1111/dom.13113. [Epub ahead of print]

Sitagliptin and Roux-en-Y gastric bypass modulate insulin secretion via regulation of intra-islet PYY.

AIMS:

The gut hormone peptide tyrosine tyrosine (PYY) is critical for maintaining islet integrity and restoring islet function following Roux-en-Y gastric bypass (RYGB). The expression of PYY and its receptors (NPYRs) in islets has been documented but not fully characterized. Modulation of islet PYY by the proteolytic enzyme DPP-IV has not been investigated and the impact of DPP-IV inhibition on islet PYY function remains unexplored. Here we have addressed these gaps and their effects on glucose-stimulated insulin secretion (GSIS). We have also investigated changes in pancreatic PYY in diabetes and following RYGB.

METHODS:

Immunohistochemistry and gene expression analysis were used to assess PYY, NPYRs and DPP-IV expression in rodent and human islets. DPP-IV activity inhibition was achieved by sitagliptin. Secretion studies were used to test PYY and sitagliptin effects on insulin release, and the involvement of GLP-1. Radioimmunoassays were used to measure hormone content in islets.

RESULTS:

PYY and DPP-IV localized in different cell types in islets while NPYRs expression was confined to the beta-cells. Chronic PYY application enhanced GSIS in rodent and diabetic human islets. DPP-IV inhibition by sitagliptin potentiated GSIS; this was mediated by locally-produced PYY, and not GLP-1. Pancreatic PYY was markedly reduced in diabetes. RYGB strongly increased islet PYY content, but did not lead to full restoration of pancreatic GLP-1 levels.

CONCLUSION:

Local regulation of pancreatic PYY, rather than GLP-1, by DPP-IV inhibition or RYGB can directly modulate the insulin secretory response to glucose, indicating a novel role of pancreatic PYY in diabetes and weight-loss surgery.

KEYWORDS:

Glucagon-like peptide-1 (GLP-1); Peptide tyrosine tyrosine (PYY); Roux-En-Y gastric bypass (RYGB); dipeptidyl peptidase IV (DPP-IV); insulin; islets

PMID: 28892258

 

 

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Plant Cell.: auth.: group Fankhauser, co-auth.: I.Xenarios

Plant Cell. 2016 Dec 6. pii: tpc.00463.2016. [Epub ahead of print]

Neighbor Detection Induces Organ-specific Transcriptomes, Revealing Patterns Underlying Hypocotyl-specific Growth.

Abstract

In response to neighbor proximity, plants increase the growth of specific organs (e.g., hypocotyls) to enhance access to sunlight. Shade enhances the activity of Phytochrome Interacting Factors (PIFs) by releasing these bHLH transcription factors from phytochrome B-mediated inhibition. PIFs promote elongation by inducing auxin production in cotyledons. In order to elucidate spatiotemporal aspects of the neighbor proximity response, we separately analyzed gene expression patterns in the major light-sensing organ (cotyledons) and in rapidly elongating hypocotyls of Arabidopsis thaliana. PIFs initiate transcriptional reprogramming in both organs within 15 minutes, comprising regulated expression of several early auxin response genes. This suggests that hypocotyl growth is elicited by both local and distal auxin signals. We show that cotyledon-derived auxin is both necessary and sufficient to initiate hypocotyl growth, but we also provide evidence for the functional importance of the local PIF-induced response. With time, the transcriptional response diverges increasingly between organs. We identify genes whose differential expression may underlie organ-specific elongation. Finally, we uncover a growth promotion gene expression signature shared between different developmentally regulated growth processes and responses to the environment in different organs.

PMID:
27923878