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Gut bacteria associated with an atherogenic TMAO-dietary pattern and choline-rich foods among aging women.

BACKGROUND AND AIMS: Choline can be metabolized by gut bacteria with a choline utilization gene, CutC, as identified through genome sequencing studies. This metabolism produces trimethylamine, the precursor to the atherosclerotic metabolite trimethylamine N-oxide (TMAO). Bacterial species involved in trimethylamine production in free-living humans have been under-investigated. We previously developed the TMAO dietary pattern (TMAO-DP), which is predictive of plasma TMAO and choline. We evaluated associations between the TMAO-DP, dietary choline, and choline-rich foods (fish, red meat, eggs) with the abundance of species with CutC. We also explored associations between the TMAO-DP and microbiome diversity. METHODS AND RESULTS: This cross-sectional analysis included 287 women (mean age = 79.6 years) from the Women's Health Initiative. Diet was assessed using a food frequency questionnaire. Stool samples were collected and the V3-V4 regions of the 16S ribosomal RNA were sequenced. Adjusted linear regression models evaluated associations between the TMAO-DP with the CLR-transformed abundance of species with CutC and with alpha-diversity indices. For beta-diversity, PERMANOVA examined measures of Aitchison distance within and between quartiles of the TMAO-DP. Associations between dietary choline and choline-rich foods with the abundance of species were evaluated using linear regression. The TMAO-DP was associated with Acidaminococcus intestini [Beta (SE): 0.23 (0.09), p-value = 0.035] and Desulfovibrio desulfuricans [Beta (SE): 0.16 (0.6), p = 0.035]. The TMAO-DP was not associated with alpha- or beta-diversity. CONCLUSION: This study provides evidence that Desulfovibrio desulfuricans and Acidaminococcus intestini, two species identified as having CutC by gene sequencing, may produce trimethylamine from diet in free-living women.

Humans

Efficient and multiplexed somatic genome editing with Cas12a mice.

Somatic genome editing in mouse models has increased our understanding of the in vivo effects of genetic alterations. However, existing models have a limited ability to create multiple targeted edits, hindering our understanding of complex genetic interactions. Here we generate transgenic mice with Cre-regulated and constitutive expression of enhanced Acidaminococcus sp. Cas12a (enAsCas12a), which robustly generates compound genotypes, including diverse cancers driven by inactivation of trios of tumour suppressor genes or an oncogenic translocation. We integrate these modular CRISPR RNA (crRNA) arrays with clonal barcoding to quantify the size and number of tumours with each array, as well as the impact of varying the guide number and position within a four-guide array. Finally, we generate tumours with inactivation of all combinations of nine tumour suppressor genes and find that the fitness of triple-knockout genotypes is largely explainable by one- and two-gene effects. These Cas12a alleles will enable further rapid creation of disease models and high-throughput investigation of coincident genomic alterations in vivo.

Animals

Gut Microbiome Composition Is Associated With Response to CD38 Antibody (Daratumumab) Treatment Among Relapsed Multiple Myeloma Patients.

INTRODUCTION: Growing data support interactions between host-gut microbes and treatment responses in multiple myeloma (MM), where a higher abundance of Eubacterium hallii in stool samples has been found among MM patients with negative minimal residual disease after induction therapy. Here, we evaluated changes in the gut microbiome associated with daratumumab (dara) based therapy in 40 MM patients, before and after therapy. PATIENTS AND METHODS: Patients with relapsed MM and prior autologous transplantation who had received 1 to 4 prior lines of therapy were eligible. Two stool samples were collected, one within 1 week prior to dara (predara) and one immediately after 4 doses of dara (postdara). Metagenomics sequencing was conducted. Microbiome taxonomic analyses were performed using MetaPhlAn4, and microbial functional pathway analyses were conducted using HUMAnN3.6. QIIME2 was used for compositional and statistical analyses. RESULTS: Of 40 participants enrolled, there were 5 nonresponders; 35 patients achieved partial response (PR) or better (responders). Among responders, 10 patients achieved complete remission (CR), and 25 patients achieved either very good partial response (VGPR) or PR. There were no statistically significant differences between overall pre and postdara gut microbiomes. Differential abundance analysis (ANCOM-BC) showed statistically significant (q ≤ 0.05) overgrowth of Alistipes finegoldii and Acidaminococcus intestini species in responders and Ruminococcus torques, Sellimonas intestinalis and Clostridium symbiosum in nonresponders. Compared to non-CR, CR samples showed enrichment of Faecalibacterium prausnitzii; non-CR samples were enriched in Segatella copri and Faecalimonas umbilicata. DISCUSSION/CONCLUSION: Our results suggest differences in species between clinical responders and nonresponders, but larger prospective studies are needed to confirm these results.

Clinical response

Rapid screening of Veillonella by ultraviolet fluorescence.

Among 51 strains of anaerobic gram-negative cocci belonging to the family Veillonellaceae, all strains of Veillonella (V. parvula and V. alcalescens) displayed red fluorescence under long-wave (366 nm) ultraviolet light, whereas no Acidaminococcus or Megasphaera demonstrated fluorescence. In contrast to Bacteroides melaninogenicus, growth of Veillonella does not require hemin and menadione, and flourescence is rapidly lost upon exposure to air. The fluorescent component of a strain of V. parvula examined could not be extracted in solution with water, ether, methanol, or chloroform, but was readily extracted with 0.4 N NaOH. Spectrophotofluorometrically, the fluorescence maximum of this extract was 660 nm with an excitation maximum of 300 nm, when measured at pH 7.2 and 25 C. Coupled with the Gram stain, ultraviolet fluorescence may be a useful tool for rapid screening of Veillonella and is particularly helpful for detection and, isolation of this organism from mixed culture.

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