Gut Site and Gut Morphology Predict Microbiome Structure and Function in Ecologically Diverse Lemurs.

Most studies of wildlife gut microbiotas understandably rely on feces to approximate consortia along the gastrointestinal tract. We therefore compared microbiome structure and predicted metagenomic function in stomach, small intestinal, cecal, and colonic samples from 52 lemurs harvested during routine necropsies. The lemurs represent seven genera (Cheirogaleus, Daubentonia, Varecia, Hapalemur, Eulemur, Lemur, Propithecus) characterized by diverse feeding ecologies and gut morphologies. In particular, the hosts variably depend on fibrous foodstuffs and show correlative morphological complexity in their large intestines. Across host lineages, microbiome diversity, variability, membership, and function differed between the upper and lower gut, reflecting regional tradeoffs in available nutrients. These patterns related minimally to total gut length but were modulated by fermentation capacity (i.e., the ratio of small to large intestinal length). Irrespective of feeding strategy, host genera with limited fermentation capacity harbored more homogenized microbiome diversity along the gut, whereas those with expanded fermentation capacity harbored cecal and colonic microbiomes with greater diversity and abundant fermentative Ruminococcaceae taxa. While highlighting the value of curated sample repositories for retrospective comparisons, our results confirm that the need to survive on fibrous foods, either routinely or in hypervariable environments, can shape the morphological and microbial features of the lower gut.

Hematology and blood biochemistry in a declining population of mantled howler monkeys (Alouatta palliata palliata) at La Pacifica, Costa Rica.

BACKGROUND: Alouatta palliata palliata are an ecologically flexible howler monkey subspecies that has recently been relisted as Endangered. Populations are declining through much of the subspecies' range, including at our study site at La Pacifica, Costa Rica. Our objectives were to screen blood hematology and biochemistry samples collected from this wild population to elucidate their baseline health. METHODS: We collected blood samples from 38 adult individuals from across the study site and analyzed 13 hematology and 14 biochemistry parameters. RESULTS: Most hematology and blood biochemistry parameter values were similar between males and females. However, mean hemoglobin was significantly lower, and mean white blood cell count was significantly higher in females; and mean calcium and mean creatinine were significantly lower in females compared to males. CONCLUSIONS: Overall, the La Pacifica population appeared healthy based on the blood parameters analyzed from sampled individuals. Our results were also largely consistent with published data available from other populations of A. p. palliata, and with reference values for captive Alouatta caraya.

Calprotectin (S100A8/A9) Is an Innate Immune Effector in Experimental Periodontitis.

Upregulated in inflammation, calprotectin (complexed S100A8 and S100A9; S100A8/A9) functions as an innate immune effector molecule, promoting inflammation, and also as an antimicrobial protein. We hypothesized that antimicrobial S100A8/A9 would mitigate change to the local microbial community and promote resistance to experimental periodontitis in vivo. To test this hypothesis, S100A9-/- and wild-type (WT; S100A9+/+) C57BL/6 mice were compared using a model of ligature-induced periodontitis. On day 2, WT mice showed fewer infiltrating innate immune cells than S100A9-/- mice; by day 5, the immune cell numbers were similar. At 5 days post ligature placement, oral microbial communities sampled with swabs differed significantly in beta diversity between the mouse genotypes. Ligatures recovered from molar teeth of S100A9-/- and WT mice contained significantly dissimilar microbial genera from each other and the overall oral communities from swabs. Concomitantly, the S100A9-/- mice had significantly greater alveolar bone loss than WT mice around molar teeth in ligated sites. When the oral microflora was ablated by antibiotic pretreatment, differences disappeared between WT and S100A9-/- mice in their immune cell infiltrates and alveolar bone loss. Calprotectin, therefore, suppresses emergence of a dysbiotic, proinflammatory oral microbial community, which reduces innate immune effector activity, including early recruitment of innate immune cells, mitigating subsequent alveolar bone loss and protecting against experimental periodontitis.

Local habitat, not phylogenetic relatedness, predicts gut microbiota better within folivorous than frugivorous lemur lineages.

Both host phylogenetic placement and feeding strategy influence the structure of the gut microbiome (GMB); however, parsing their relative contributions presents a challenge. To meet this challenge, we compared GMB structure in two genera of lemurs characterized by different dietary specializations, the frugivorous brown lemurs ( Eulemur spp.) and the folivorous sifakas ( Propithecus spp.). These genera sympatrically occupy similar habitats (dry forests and rainforests) and diverged over similar evolutionary timescales. We collected fresh faeces from 12 species (six per host genus), at seven sites across Madagascar, and sequenced the 16S rRNA gene to determine GMB membership, diversity and variability. The lemurs' GMBs clustered predominantly by host genus; nevertheless, within genera, host relatedness did not predict GMB distance between species. The GMBs of brown lemurs had greater evenness and diversity, but were more homogeneous across species, whereas the GMBs of sifakas were differentiated between habitats. Thus, over relatively shallow timescales, environmental factors can override the influence of host phylogenetic placement on GMB phylogenetic composition. Moreover, feeding strategy can underlie the relative strength of host-microbiome coadaptation, with Madagascar's folivores perhaps requiring locally adapted GMBs to facilitate their highly specialized diets.

Characterization of Campylobacter jejuni, Campylobacter upsaliensis, and a novel Campylobacter sp. in a captive non-human primate zoological collection.

BACKGROUND: The aim of this study was to longitudinally investigate the prevalence and characterization of Campylobacter spp. from non-human primates primate (NHP) with a history of endemic diarrhea housed at Como Park Zoo. METHODS: Fecal samples from 33 symptom-free NHP belonging to eight different species were collected weekly for 9 weeks. Species-level characterization and phylogenetic analysis of isolates included biochemical testing and 16S rRNA sequencing. RESULTS: Campylobacter spp. were isolated from the feces of 42% (14/33) of the primates. Three Campylobacter spp. (C upsaliensis, C jejuni, and novel Campylobacter sp.) were identified from three NHP species. A possible positive host Campylobacter species-specificity was observed. However, no statistical association was observed between the isolation of Campylobacter spp. and age and sex of the animal. CONCLUSIONS: The study revealed the value of conducting repeated fecal sampling to establish the overall prevalence of Campylobacter in zoo-maintained NHP; it also importantly identifies a novel Campylobacter sp. isolated from white-faced saki monkeys.

Bacterial community structure and function distinguish gut sites in captive red-shanked doucs (Pygathrix nemaeus).

The mammalian order primates contains wide species diversity. Members of the subfamily Colobinae are unique amongst extant primates in that their gastrointestinal systems more closely resemble those of ruminants than other members of the primate order. In the growing literature surrounding nonhuman primate microbiomes, analysis of microbial communities has been limited to the hindgut, since few studies have captured data on other gut sites, including the foregut of colobine primates. In this study, we used the red-shanked douc (Pygathrix nemaeus) as a model for colobine primates to study the relationship between gastrointestinal bacterial community structure and gut site within and between subjects. We analyzed fecal and pregastric stomach content samples, representative of the hindgut and foregut respectively, using 16S recombinant DNA (rDNA) sequencing and identified microbiota using closed-reference operational taxonomic unit (OTU) picking against the GreenGenes database. Our results show divergent bacterial communities clearly distinguish the foregut and hindgut microbiomes. We found higher bacterial biodiversity and a higher Firmicutes:Bacteroides ratio in the hindgut as opposed to the foregut. These gut sites showed strong associations with bacterial function. Specifically, energy metabolism was upregulated in the hindgut, whereas detoxification was increased in the foregut. Our results suggest a red-shanked douc's foregut microbiome is no more concordant with its own hindgut than it is with any other red-shanked douc's hindgut microbiome, thus reinforcing the notion that the bacterial communities of the foregut and hindgut are distinctly unique. OPEN PRACTICES: This article has been awarded Open Materials and Open Data badges. All materials and data are publicly accessible via the IRIS Repository at https://www.iris-database.org/iris/app/home/detail?id=york:934328. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.

Captivity humanizes the primate microbiome.

The primate gastrointestinal tract is home to trillions of bacteria, whose composition is associated with numerous metabolic, autoimmune, and infectious human diseases. Although there is increasing evidence that modern and Westernized societies are associated with dramatic loss of natural human gut microbiome diversity, the causes and consequences of such loss are challenging to study. Here we use nonhuman primates (NHPs) as a model system for studying the effects of emigration and lifestyle disruption on the human gut microbiome. Using 16S rRNA gene sequencing in two model NHP species, we show that although different primate species have distinctive signature microbiota in the wild, in captivity they lose their native microbes and become colonized with Prevotella and Bacteroides, the dominant genera in the modern human gut microbiome. We confirm that captive individuals from eight other NHP species in a different zoo show the same pattern of convergence, and that semicaptive primates housed in a sanctuary represent an intermediate microbiome state between wild and captive. Using deep shotgun sequencing, chemical dietary analysis, and chloroplast relative abundance, we show that decreasing dietary fiber and plant content are associated with the captive primate microbiome. Finally, in a meta-analysis including published human data, we show that captivity has a parallel effect on the NHP gut microbiome to that of Westernization in humans. These results demonstrate that captivity and lifestyle disruption cause primates to lose native microbiota and converge along an axis toward the modern human microbiome.

The gut microbiome of nonhuman primates: Lessons in ecology and evolution.

The mammalian gastrointestinal (GI) tract is home to trillions of bacteria that play a substantial role in host metabolism and immunity. While progress has been made in understanding the role that microbial communities play in human health and disease, much less attention has been given to host-associated microbiomes in nonhuman primates (NHPs). Here we review past and current research exploring the gut microbiome of NHPs. First, we summarize methods for characterization of the NHP gut microbiome. Then we discuss variation in gut microbiome composition and function across different NHP taxa. Finally, we highlight how studying the gut microbiome offers new insights into primate nutrition, physiology, and immune system function, as well as enhances our understanding of primate ecology and evolution. Microbiome approaches are useful tools for studying relevant issues in primate ecology. Further study of the gut microbiome of NHPs will offer new insight into primate ecology and evolution as well as human health.

The structure and selectivity of the SR protein SRSF2 RRM domain with RNA.

SRSF2 is a prototypical SR protein which plays important roles in the alternative splicing of pre-mRNA. It has been shown to be involved in regulatory pathways for maintaining genomic stability and play important roles in regulating key receptors in the heart. We report here the solution structure of the RNA recognition motifs (RRM) domain of free human SRSF2 (residues 9-101). Compared with other members of the SR protein family, SRSF2 structure has a longer L3 loop region. The conserved aromatic residue in the RNP2 motif is absent in SRSF2. Calorimetric titration shows that the RNA sequence 5'AGCAGAGUA3' binds SRSF2 with a K(d) of 61 ± 1 nM and a 1:1 stoichiometry. NMR and mutagenesis experiments reveal that for SFSF2, the canonical ß1 and ß3 interactions are themselves not sufficient for effective RNA binding; the additional loop L3 is crucial for RNA complex formation. A comparison is made between the structures of SRSF2-RNA complex with other known RNA complexes of SR proteins. We conclude that interactions involving the L3 loop, N- and C-termini of the RRM domain are collectively important for determining selectivity between the protein and RNA.

Antibiotic-induced gut dysbiosis elicits gut-brain axis relevant multi-omic signatures and behavioral and neuroendocrine changes in a nonhuman primate model.

Emerging evidence indicates that antibiotic-induced dysbiosis can play an etiological role in the pathogenesis of neuropsychiatric disorders. However, most of this evidence comes from rodent models. The objective of this study was to evaluate if antibiotic-induced gut dysbiosis can elicit changes in gut metabolites and behavior indicative of gut-brain axis disruption in common marmosets (Callithrix jacchus) - a nonhuman primate model often used to study sociability and stress. We were able to successfully induce dysbiosis in marmosets using a custom antibiotic cocktail (vancomycin, enrofloxacin and neomycin) administered orally for 28 days. This gut dysbiosis altered gut metabolite profiles, behavior, and stress reactivity. Increase in gut Fusobacterium spp. post-antibiotic administration was a novel dysbiotic response and has not been observed in any rodent or human studies to date. There were significant changes in concentrations of several gut metabolites which are either neurotransmitters (e.g., GABA and serotonin) or have been found to be moderators of gut-brain axis communication in rodent models (e.g., short-chain fatty acids and bile acids). There was an increase in affiliative behavior and sociability in antibiotic-administered marmosets, which might be a coping mechanism in response to gut dysbiosis-induced stress. Increase in urinary cortisol levels after multiple stressors provides more definitive proof that this model of dysbiosis may cause disrupted communication between gut and brain in common marmosets. This study is a first attempt to establish common marmosets as a novel model to study the impact of severe gut dysbiosis on gut-brain axis cross-talk and behavior.

Informatics for your Gut: at the Interface of Nutrition, the Microbiome, and Technology.

BACKGROUND: A significant portion of individuals in the United States and worldwide experience diseases related to or driven by diet. As research surrounding user-centered design and the microbiome grows, movement of the spectrum of translational science from bench to bedside for improvement of human health through nutrition becomes more accessible. In this literature survey, we examined recent literature examining informatics research at the interface of nutrition and the microbiome. OBJECTIVES: The objective of this survey was to synthesize recent literature describing how technology is being applied to understand health at the interface of nutrition and the microbiome focusing on the perspective of the consumer. METHODS: A survey of the literature published between January 1, 2021 and October 10, 2022 was performed using the PubMed database and resulting literature was evaluated against inclusion and exclusion criteria. RESULTS: A total of 139 papers were retrieved and evaluated against inclusion and exclusion criteria. After evaluation, 45 papers were reviewed in depth revealing four major themes: (1) microbiome and diet, (2) usability,(3) reproducibility and rigor, and (4) precision medicine and precision nutrition. CONCLUSIONS: A review of the relationships between current literature on technology, nutrition and the microbiome, and self-management of dietary patterns was performed. Major themes that emerged from this survey revealed exciting new horizons for consumer management of diet and disease, as well as progress towards elucidating the relationship between diet, the microbiome, and health outcomes. The survey revealed continuing interest in the study of diet-related disease and the microbiome and acknowledgement of needs for data re-use, sharing, and unbiased and rigorous measurement of the microbiome. The literature also showed trends toward enhancing the usability of digital interventions to support consumer health and home management, and consensus building around how precision medicine and precision nutrition may be applied in the future to improve human health outcomes and prevent diet-related disease.

Antibiotic-induced gut dysbiosis and cognitive, emotional, and behavioral changes in rodents: a systematic review and meta-analysis.

There are previous epidemiological studies reporting associations between antibiotic use and psychiatric symptoms. Antibiotic-induced gut dysbiosis and alteration of microbiota-gut-brain axis communication has been proposed to play a role in this association. In this systematic review and meta-analysis, we reviewed published articles that have presented results on changes in cognition, emotion, and behavior in rodents (rats and mice) after antibiotic-induced gut dysbiosis. We searched three databases-PubMed, Web of Science, and SCOPUS to identify such articles using dedicated search strings and extracted data from 48 articles. Increase in anxiety and depression-like behavior was reported in 32.7 and 40.7 percent of the study-populations, respectively. Decrease in sociability, social novelty preference, recognition memory and spatial cognition was found in 18.1, 35.3, 26.1, and 62.5 percent of the study-populations, respectively. Only one bacterial taxon (increase in gut Proteobacteria) showed statistically significant association with behavioral changes (increase in anxiety). There were no consistent findings with statistical significance for the potential biomarkers [Brain-derived neurotrophic factor (BDNF) expression in the hippocampus, serum corticosterone and circulating IL-6 and IL-1ß levels]. Results of the meta-analysis revealed a significant association between symptoms of negative valence system (including anxiety and depression) and cognitive system (decreased spatial cognition) with antibiotic intake (p < 0.05). However, between-study heterogeneity and publication bias were statistically significant (p < 0.05). Risk of bias was evaluated to be high in the majority of the studies. We identified and discussed several reasons that could contribute to the heterogeneity between the results of the studies examined. The results of the meta-analysis provide promising evidence that there is indeed an association between antibiotic-induced gut dysbiosis and psychopathologies. However, inconsistencies in the implemented methodologies make generalizing these results difficult. Gut microbiota depletion using antibiotics may be a useful strategy to evaluate if and how gut microbes influence cognition, emotion, and behavior, but the heterogeneity in methodologies used precludes any definitive interpretations for a translational impact on clinical practice.

Serum cortisol assay performance following the 1 mg overnight dexamethasone suppression test.

BACKGROUND: The 1 mg overnight dexamethasone suppression test (ONDST) is recommended for the differential diagnosis of Cushing's syndrome and the investigation of adrenal incidentalomas. Despite documented variation in serum cortisol immunoassay performance, little has been published regarding its effect on the ONDST. AIMS: Assess the performance of three immunoassay platforms (Roche Elecsys II, Abbott Alinity & Siemens Centaur) when compared to a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. METHODS: Samples (n = 77) sent to the laboratory as part of an ONDST were retrieved prior to disposal, anonymized, and analysed on all platforms. Samples with factors impacting immunoassay analysis quality were excluded. Results were statistically compared to an LC-MS/MS method that previously demonstrated excellent comparability to a candidate reference method. RESULTS: The Roche gen II showed a mean bias of -2.4 nmol/L and a Passing-Bablok fit of y = -0.9 + 0.97x. This was not affected by sex. The Abbott showed a mean bias -18.8 nmol/L, and a fit of y = -11.3 + 0.88x. This bias was -20.7 nmol/L in females versus -17.2 nmol/L in males. The Siemens had a mean bias of 2.3 nmol/L and a fit of y = 1.4 + 1.07x. This bias was 5.7 nmol/L in males versus -1.0 nmol/L in females. CONCLUSIONS: Clinicians should be aware of the method-dependent variation that exists within serum cortisol analysis during the ONDSTs. Roche and Siemens aligned more closely with LC-MS/MS while the Abbot may cause a reduction in ONDST sensitivity. This data supports assay-specific cut-offs for the ONDST.

Design, Biological Evaluation, and Computer-Aided Analysis of Dihydrothiazepines as Selective Antichlamydial Agents.

Chlamydia trachomatis (CT) causes the most prevalent sexually transmitted bacterial disease in the United States. The lack of drug selectivity is one of the main challenges of the current antichlamydial pharmacotherapy. The metabolic needs of CT are controlled, among others, by cylindrical proteases and their chaperones (e.g., ClpX). It has been shown that dihydrothiazepines can disrupt CT-ClpXP. Based on this precedent, we synthesized a dihydrothiazepine library and characterized its antichlamydial activity using a modified semi-high-throughput screening assay. Then, we demonstrated their ability to inhibit ClpX ATPase activity in vitro, supporting ClpX as a target. Further, our lead compound displayed a promising selectivity profile against CT, acceptable cytotoxicity, no mutagenic potential, and good in vitro stability. A two-dimensional quantitative structure-activity relationship (2D QSAR) model was generated as a support tool in the identification of more potent antichlamydial molecules. This study suggests dihydrothiazepines are a promising starting point for the development of new and selective antichlamydial drugs.

biomArker-guided Duration of Antibiotic treatment in hospitalised Patients with suspecTed Sepsis (ADAPT-Sepsis): A protocol for a multicentre randomised controlled trial.

Aim: To describe the protocol for a multi-centre randomised controlled trial to determine whether treatment protocols monitoring daily CRP (C-reactive protein) or PCT (procalcitonin) safely allow a reduction in duration of antibiotic therapy in hospitalised adult patients with sepsis. Design: Multicentre three-arm randomised controlled trial. Setting: UK NHS hospitals. Target population: Hospitalised critically ill adults who have been commenced on intravenous antibiotics for sepsis. Health technology: Three protocols for guiding antibiotic discontinuation will be compared: (a) standard care; (b) standard care + daily CRP monitoring; (c) standard care + daily PCT monitoring. Standard care will be based on routine sepsis management and antibiotic stewardship. Measurement of outcomes and costs. Outcomes will be assessed to 28 days. The primary outcomes are total duration of antibiotics and safety outcome of all-cause mortality. Secondary outcomes include: escalation of care/re-admission; infection re-lapse/recurrence; antibiotic dose; length and level of critical care stay and length of hospital stay. Ninety-day all-cause mortality rates will also be collected. An assessment of cost effectiveness will be performed. Conclusion: In the setting of routine NHS care, if this trial finds that a treatment protocol based on monitoring CRP or PCT safely allows a reduction in duration of antibiotic therapy, and is cost effective, then this has the potential to change clinical practice for critically ill patients with sepsis. Moreover, if a biomarker-guided protocol is not found to be effective, then it will be important to avoid its use in sepsis and prevent ineffective technology becoming widely adopted in clinical practice.

The primate gut mycobiome-bacteriome interface is impacted by environmental and subsistence factors.

The gut microbiome of primates is known to be influenced by both host genetic background and subsistence strategy. However, these inferences have been made mainly based on adaptations in bacterial composition - the bacteriome and have commonly overlooked the fungal fraction - the mycobiome. To further understand the factors that shape the gut mycobiome of primates and mycobiome-bacteriome interactions, we sequenced 16 S rRNA and ITS2 markers in fecal samples of four different nonhuman primate species and three human groups under different subsistence patterns (n = 149). The results show that gut mycobiome composition in primates is still largely unknown but highly plastic and weakly structured by primate phylogeny, compared with the bacteriome. We find significant gut mycobiome overlap between captive apes and human populations living under industrialized subsistence contexts; this is in contrast with contemporary hunter-gatherers and agriculturalists, who share more mycobiome traits with diverse wild-ranging nonhuman primates. In addition, mycobiome-bacteriome interactions were specific to each population, revealing that individual, lifestyle and intrinsic ecological factors affect structural correspondence, number, and kind of interactions between gut bacteria and fungi in primates. Our findings indicate a dominant effect of ecological niche, environmental factors, and diet over the phylogenetic background of the host, in shaping gut mycobiome composition and mycobiome-bacteriome interactions in primates.

Dietary choices by four captive slender lorises (Loris tardigradus) when presented with various insect life stages.

The slender loris (Loris tardigradus) is a rare, nocturnal prosimian found only in the tropical rainforest of southern India and Sri Lanka. Little is known about their diet, though it is assumed that insects comprise a majority of their wild diet. Based on this assumption, captive lorises are offered a variety of insects or insect life stages; the species of insect or the life stage is often determined by what is easiest to buy or rear. Captive lorises at the Duke Lemur Center (DLC) were offered the opportunity to choose which life stage of mealworms (Tenebrio molito), superworms (Zophobus morio), or waxworms (Galleria mellonella) they preferred. The DLC captive lorises did not select the largest life stages of any insect offered. They preferred the larvae stage to the adult stage in all three insect species, and males and females had different insect species and life stage preferences.

Host Identity and Geographic Location Significantly Affect Gastrointestinal Microbial Richness and Diversity in Western Lowland Gorillas (Gorilla gorilla gorilla) under Human Care.

The last few decades have seen an outpouring of gastrointestinal (GI) microbiome studies across diverse host species. Studies have ranged from assessments of GI microbial richness and diversity to classification of novel microbial lineages. Assessments of the "normal" state of the GI microbiome composition across multiple host species has gained increasing importance for distinguishing healthy versus diseased states. This study aimed to determine baselines and trends over time to establish "typical" patterns of GI microbial richness and diversity, as well as inter-individual variation, in three populations of western lowland gorillas (Gorilla gorilla gorilla) under human care at three zoological institutions in North America. Fecal samples were collected from 19 western lowland gorillas every two weeks for seven months (n = 248). Host identity and host institution significantly affected GI microbiome community composition (p < 0.05), although host identity had the most consistent and significant effect on richness (p = 0.03) and Shannon diversity (p = 0.004) across institutions. Significant changes in microbial abundance over time were observed only at Denver Zoo (p < 0.05). Our results suggest that individuality contributes to most of the observed GI microbiome variation in the study populations. Our results also showed no significant changes in any individual's microbial richness or Shannon diversity during the 7-month study period. While some microbial taxa (Prevotella, Prevotellaceae and Ruminococcaceae) were detected in all gorillas at varying levels, determining individual baselines for microbial composition comparisons may be the most useful diagnostic tool for optimizing non-human primate health under human care.

Interspecies variation in hominid gut microbiota controls host gene regulation.

The gut microbiome exhibits extreme compositional variation between hominid hosts. However, it is unclear how this variation impacts host physiology across species and whether this effect can be mediated through microbial regulation of host gene expression in interacting epithelial cells. Here, we characterize the transcriptional response of human colonic epithelial cells in vitro to live microbial communities extracted from humans, chimpanzees, gorillas, and orangutans. We find that most host genes exhibit a conserved response, whereby they respond similarly to the four hominid microbiomes. However, hundreds of host genes exhibit a divergent response, whereby they respond only to microbiomes from specific host species. Such genes are associated with intestinal diseases in humans, including inflammatory bowel disease and Crohn's disease. Last, we find that inflammation-associated microbial species regulate the expression of host genes previously associated with inflammatory bowel disease, suggesting health-related consequences for species-specific host-microbiome interactions across hominids.

Cytoplasmic residues of phospholamban interact with membrane surfaces in the presence of SERCA: a new role for phospholipids in the regulation of cardiac calcium cycling?

The 52-amino acid transmembrane protein phospholamban (PLB) regulates calcium cycling in cardiac cells by forming a complex with the sarco(endo)plasmic reticulum calcium ATPase (SERCA) and reversibly diminishing the rate of calcium uptake by the sarcoplasmic reticulum. The N-terminal cytoplasmic domain of PLB interacts with the cytoplasmic domain of SERCA, but, in the absence of the enzyme, can also associate with the surface of anionic phospholipid membranes. This work investigates whether the cytoplasmic domain of PLB can also associate with membrane surfaces in the presence of SERCA, and whether such interactions could influence the regulation of the enzyme. It is shown using solid-state NMR and isothermal titration calorimetry (ITC) that an N-terminally acetylated peptide representing the first 23 N-terminal amino acids of PLB (PLB1-23) interacts with membranes composed of zwitterionic phosphatidylcholine (PC) and anionic phosphatidylglycerol (PG) lipids in the absence and presence of SERCA. Functional measurements of SERCA in sarcoplasmic reticulum (SR) vesicles, planar SR membranes and reconstituted into PC/PG membranes indicate that PLB1-23 lowers the maximal rate of ATP hydrolysis by acting at the cytoplasmic face of the enzyme. A small, but statistically significant, reduction in the inhibitory effect of the peptide is observed for SERCA reconstituted into PC/PG membranes compared to SERCA in membranes of PC alone. It is suggested that interactions between the cytoplasmic domain of PLB and negatively charged phospholipids might play a role in moderating the regulation of SERCA, with implications for cardiac muscle contractility.