The Origin of Nitrogen on Jupiter and Saturn from the 15^{15}N/14^{14}N Ratio

The Texas Echelon cross Echelle Spectrograph (TEXES), mounted on NASA's Infrared Telescope Facility (IRTF), was used to map mid-infrared ammonia absorption features on both Jupiter and Saturn in February 2013. Ammonia is the principle reservoir of nitrogen on the giant planets, and the ratio of isotopologues ($^{15}$N/$^{14}$N) can reveal insights into the molecular carrier (e.g., as N$_2$ or NH$_3$) of nitrogen to the forming protoplanets, and hence the source reservoirs from which these worlds accreted. We targeted two spectral intervals (900 and 960 cm$^{-1}$) that were relatively clear of terrestrial atmospheric contamination and contained close features of $^{14}$NH$_3$ and $^{15}$NH$_3$, allowing us to derive the ratio from a single spectrum without ambiguity due to radiometric calibration (the primary source of uncertainty in this study). We present the first ground-based determination of Jupiter's $^{15}$N/$^{14}$N ratio (in the range from $1.4\times10^{-3}$ to $2.5\times10^{-3}$), which is consistent with both previous space-based studies and with the primordial value of the protosolar nebula. On Saturn, we present the first upper limit on the $^{15}$N/$^{14}$N ratio of no larger than $2.0\times10^{-3}$ for the 900-cm$^{-1}$ channel and a less stringent requirement that the ratio be no larger than $2.8\times10^{-3}$ for the 960-cm$^{-1}$ channel ($1\sigma$ confidence). Specifically, the data rule out strong $^{15}$N-enrichments such as those observed in Titan's atmosphere and in cometary nitrogen compounds. To the extent possible with ground-based radiometric uncertainties, the saturnian and jovian $^{15}$N/$^{14}$N ratios appear indistinguishable, implying that $^{15}$N-enriched ammonia ices could not have been a substantial contributor to the bulk nitrogen inventory of either planet, favouring the accretion of primordial N$_2$ from the gas phase or as low-temperature ices.Comment: 33 pages, 19 figures, manuscript accepted for publication in Icaru

Short Course in the Microbiome

Over the past decade, it has become evident that the microbiome is an important environmental factor that affects many physiological processes, such as cell proliferation and differentiation, behaviour, immune function and metabolism. More importantly, it may contribute to a wide variety of diseases, including cancer, inflammatory diseases, metabolic diseases and responses to pathogens. We expect that international, integrative and interdisciplinary translational research teams, along with the emergence of FDA-approved platforms, will set the framework for microbiome-based therapeutics and diagnostics. We recognize that the microbiome ecosystem offers new promise for personalized/precision medicine and targeted treatment for a variety of diseases. The short course was held as a four-session webinar series in April 2015, taught by pioneers and experts in the microbiome ecosystem, covering a broad range of topics from the healthy microbiome to the effects of an altered microbiome from neonates to adults and the long term effects as it is related to disease, from asthma to cancer. We have learned to appreciate how beneficial our microbes are in breaking down our food, fighting off infections and nurturing our immune system, and this information provides us with ideas as to how we can manipulate our microbiome to prevent certain diseases. However, given the variety of applications, there are scientific challenges, though there are very promising areas in reference to the clinical benefits of understanding more about our microbiome, whether in our gut or on our skin: the outlook is bright. A summary of the short course is presented as a meeting dispatch

Spatial Variations in the Altitude of the CH4 Homopause at Jupiter's Mid-to-high Latitudes, as Constrained from IRTF-TEXES Spectra

Peer reviewedPublisher PD

Meridional Variations of C2_2H2_2 in Jupiter's Stratosphere From Juno UVS Observations

peer reviewedThe Ultraviolet Spectrograph (UVS) instrument on the Juno mission records far-ultraviolet reflected sunlight from Jupiter. These spectra are sensitive to the abundances of chemical species in the upper atmosphere and to the distribution of the stratospheric haze layer. We combine observations from the first 30 perijoves of the mission in order to study the meridional distribution of acetylene (C2H2) in Jupiter's stratosphere. We find that the abundance of C2H2 decreases toward the poles by a factor of 2-4, in agreement with previous analyses of mid-infrared spectra. This result is expected from insolation rates: near the equator, the UV solar flux is higher, allowing more C2H2 to be generated from the UV photolysis of CH4. The decrease in abundance toward the poles suggests that horizontal mixing rates are not rapid enough to homogenize the latitudinal distribution

Interaction between the microbiome and TP53 in human lung cancer.

BACKGROUND: Lung cancer is the leading cancer diagnosis worldwide and the number one cause of cancer deaths. Exposure to cigarette smoke, the primary risk factor in lung cancer, reduces epithelial barrier integrity and increases susceptibility to infections. Herein, we hypothesize that somatic mutations together with cigarette smoke generate a dysbiotic microbiota that is associated with lung carcinogenesis. Using lung tissue from 33 controls and 143 cancer cases, we conduct 16S ribosomal RNA (rRNA) bacterial gene sequencing, with RNA-sequencing data from lung cancer cases in The Cancer Genome Atlas serving as the validation cohort. RESULTS: Overall, we demonstrate a lower alpha diversity in normal lung as compared to non-tumor adjacent or tumor tissue. In squamous cell carcinoma specifically, a separate group of taxa are identified, in which Acidovorax is enriched in smokers. Acidovorax temporans is identified within tumor sections by fluorescent in situ hybridization and confirmed by two separate 16S rRNA strategies. Further, these taxa, including Acidovorax, exhibit higher abundance among the subset of squamous cell carcinoma cases with TP53 mutations, an association not seen in adenocarcinomas. CONCLUSIONS: The results of this comprehensive study show both microbiome-gene and microbiome-exposure interactions in squamous cell carcinoma lung cancer tissue. Specifically, tumors harboring TP53 mutations, which can impair epithelial function, have a unique bacterial consortium that is higher in relative abundance in smoking-associated tumors of this type. Given the significant need for clinical diagnostic tools in lung cancer, this study may provide novel biomarkers for early detection

Targeting Dietary and Microbial Tryptophan-Indole Metabolism as Therapeutic Approaches to Colon Cancer

Tryptophan metabolism, via the kynurenine (Kyn) pathway, and microbial transformation of tryptophan to indolic compounds are fundamental for host health; both of which are altered in colon carcinogenesis. Alterations in tryptophan metabolism begin early in colon carcinogenesis as an adaptive mechanism for the tumor to escape immune surveillance and metastasize. The microbial community is a key part of the tumor microenvironment and influences cancer initiation, promotion and treatment response. A growing awareness of the impact of the microbiome on tryptophan (Trp) metabolism in the context of carcinogenesis has prompted this review. We first compare the different metabolic pathways of Trp under normal cellular physiology to colon carcinogenesis, in both the host cells and the microbiome. Second, we review how the microbiome, specifically indoles, influence host tryptophan pathways under normal and oncogenic metabolism. We conclude by proposing several dietary, microbial and drug therapeutic modalities that can be utilized in combination to abrogate tumorigenesis

Impaired Proteostasis in Obese Skeletal Muscle Relates to Altered Immunoproteasome Activity

Obesity-associated inflammation and/or oxidative stress can damage intramuscular proteins and jeopardize muscle integrity. The immunoproteasome (iProt) is vital to remove oxidatively modified proteins, but this function may be compromised with obesity. We sought to elucidate whether diet-induced obesity (DIO) alters intramuscular iProt content and activity in mice to identify a possible mechanism for impaired muscle proteostasis in the obese state. Total proteasome content and activity and estimates of muscle oxidative damage, inflammation, muscle mass and strength were also assessed. Twenty-three male, 5-week-old C57BL/6J mice were fed a high-fat, high-sucrose (HFS, 45% kcal fat, 17% sucrose, n = 12) or low-fat, low-sucrose (LFS, 10% kcal fat, 0% sucrose, n = 11) diet for 12 weeks. Strength was assessed via a weightlifting test. Despite no change in pro-inflammatory cytokines (P > 0.05), oxidative protein damage was elevated within the gastrocnemius (P = 0.036) and tibialis anterior (P = 0.033) muscles of HFS-fed mice. Intramuscular protein damage coincided with reduced iProt and total proteasome activity (PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author