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Microbes transform their environments using diverse enzymatic reactions. However, it remains challenging to measure microbial reaction rates in natural environments. Despite advances in global quantification of enzyme abundances, the individual relationships between enzyme abundances and their reaction rates have not been systematically examined. Using matched proteomic and reaction rate data from microbial cultures, we show that enzyme abundance is often insufficient to predict its corresponding reaction rate. However, we discovered that global proteomic measurements can be used to make accurate rate predictions of individual reaction rates (median R 2 = 0.78). Accurate rate predictions required only a small number of proteins and they did not need explicit prior mechanistic knowledge or environmental context. These results indicate that proteomes are encoders of cellular reaction rates, potentially enabling proteomic measurements in situ to estimate the rates of microbially mediated reactions in natural systems.

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The connection between growth and gene expression has often been considered in a single gene. Repurposing a drug-drug interaction model, the multidimensional effects of several simultaneous gene expression perturbations on growth have been examined in the model bacteria Escherichia coli.

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Marine phytoplankton vary widely in size across taxa, and in cell suspension densities across habitats and growth states. Cell suspension density and total biovolume determine the bulk influence of a phytoplankton community upon its environment. Cell suspension density also determines the intercellular spacings separating phytoplankton cells from each other, or from co-occurring bacterioplankton. Intercellular spacing then determines the mean diffusion paths for exchanges of solutes among co-occurring cells. Marine phytoplankton and bacterioplankton both produce and scavenge reactive oxygen species (ROS), to maintain intracellular ROS homeostasis to support their cellular processes, while limiting damaging reactions. Among ROS, hydrogen peroxide (H2O2) has relatively low reactivity, long intracellular and extracellular lifetimes, and readily crosses cell membranes. Our objective was to quantify how cells can influence other cells via diffusional interactions, using H2O2 as a case study. To visualize and constrain potentials for cell-to-cell exchanges of H2O2, we simulated the decrease of [H2O2] outwards from representative phytoplankton taxa maintaining internal [H2O2] above representative seawater [H2O2]. [H2O2] gradients outwards from static cell surfaces were dominated by volumetric dilution, with only a negligible influence from decay. The simulated [H2O2] fell to background [H2O2] within ~3.1 µm from a Prochlorococcus cell surface, but extended outwards 90 µm from a diatom cell surface. More rapid decays of other, less stable ROS, would lower these threshold distances. Bacterioplankton lowered simulated local [H2O2] below background only out to 1.2 µm from the surface of a static cell, even though bacterioplankton collectively act to influence seawater ROS. These small diffusional spheres around cells mean that direct cell-to-cell exchange of H2O2 is unlikely in oligotrophic habits with widely spaced, small cells; moderate in eutrophic habits with shorter cell-to-cell spacing; but extensive within phytoplankton colonies.

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Production and use of proteins is under strong selection in microbes, but it is unclear how proteome-level traits relate to ecological strategies. We identified and quantified proteomic traits of eukaryotic microbes and bacteria through an Antarctic phytoplankton bloom using in situ metaproteomics. Different taxa, rather than different environmental conditions, formed distinct clusters based on their ribosomal and photosynthetic proteomic proportions, and we propose that these characteristics relate to ecological differences. We defined and used a proteomic proxy for regulatory cost, which showed that SAR11 had the lowest regulatory cost of any taxa we observed at our summertime Southern Ocean study site. Haptophytes had lower regulatory cost than diatoms, which may underpin haptophyte-to-diatom bloom progression in the Ross Sea. We were able to make these proteomic trait inferences by assessing various sources of bias in metaproteomics, providing practical recommendations for researchers in the field. We have quantified several proteomic traits (ribosomal and photosynthetic proteomic proportions, regulatory cost) in eukaryotic and bacterial taxa, which can then be incorporated into trait-based models of microbial communities that reflect resource allocation strategies.

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Micronutrients control phytoplankton growth in the ocean, influencing carbon export and fisheries. It is currently unclear how micronutrient scarcity affects cellular processes and how interdependence across micronutrients arises. We show that proximate causes of micronutrient growth limitation and interdependence are governed by cumulative cellular costs of acquiring and using micronutrients. Using a mechanistic proteomic allocation model of a polar diatom focused on iron and manganese, we demonstrate how cellular processes fundamentally underpin micronutrient limitation, and how they interact and compensate for each other to shape cellular elemental stoichiometry and resource interdependence. We coupled our model with metaproteomic and environmental data, yielding an approach for estimating biogeochemical metrics, including taxon-specific growth rates. Our results show that cumulative cellular costs govern how environmental conditions modify phytoplankton growth.

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The Southern Ocean (SO) harbors some of the most intense phytoplankton blooms on Earth. Changes in temperature and iron availability are expected to alter the intensity of SO phytoplankton blooms, but little is known about how these changes will influence community composition and downstream biogeochemical processes. We performed light-saturated experimental manipulations on surface ocean microbial communities from McMurdo Sound in the Ross Sea to examine the effects of increased iron availability (+2 nM) and warming (+3 and +6 °C) on nutrient uptake, as well as the growth and transcriptional responses of two dominant diatoms, Fragilariopsis and Pseudo-nitzschia We found that community nutrient uptake and primary productivity were elevated under both warming conditions without iron addition (relative to ambient -0.5 °C). This effect was greater than additive under concurrent iron addition and warming. Pseudo-nitzschia became more abundant under warming without added iron (especially at 6 °C), while Fragilariopsis only became more abundant under warming in the iron-added treatments. We attribute the apparent advantage Pseudo-nitzschia shows under warming to up-regulation of iron-conserving photosynthetic processes, utilization of iron-economic nitrogen assimilation mechanisms, and increased iron uptake and storage. These data identify important molecular and physiological differences between dominant diatom groups and add to the growing body of evidence for Pseudo-nitzschia's increasingly important role in warming SO ecosystems. This study also suggests that temperature-driven shifts in SO phytoplankton assemblages may increase utilization of the vast pool of excess nutrients in iron-limited SO surface waters and thereby influence global nutrient distribution and carbon cycling.

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A systematic review based on the PRISMA guidelines was conducted to investigate and compare treatment with hyaluronic acid (HA), corticosteroids, and blood products in patients with temporomandibular joint osteoarthritis (TMJOA). The MEDLINE/PubMed, Embase, and Cochrane Library databases were searched for articles published until September 25, 2019. Articles met the inclusion criteria if they reported patients with TMJOA, a comparison group, and a follow-up period of at least 6 months. The mean and standard deviation for TMJ pain and maximum mouth opening (MMO) were reported. Nine studies involving 443 patients were included. Injectables and Ringer's lactate solution or normal saline were reported to significantly improve TMJ pain and MMO. Regarding TMJ pain, two studies showed a significant superiority of plasma rich in growth factors (PRGF)/platelet-rich plasma (PRP) injections with or without arthrocentesis over HA, but HA showed a significant improvement compared to corticosteroids. For MMO, no injectable was found to be superior to Ringer's lactate or a normal saline control, but arthrocentesis + PRP resulted in MMO improvement compared to arthrocentesis + HA. Overall, all injectables in conjunction with arthrocentesis were efficient in alleviating pain and improving MMO in TMJOA patients; however, a meta-analysis was not possible due to heterogeneity across studies.

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Calcium pyrophosphate deposition disease (CPPD) is a crystal arthropathy that can involve the temporomandibular joint. It is known to accelerate the osteoarthritic process, often initially presenting with advanced level of disease. The management of CPPD in the rheumatology and orthopedic literature is one of early diagnosis and medical management of acute attacks. The cases of three patients who presented with initial complaints of joint pain and limited mouth opening are presented. Preoperative imaging identified calcifications in two of these patients. Definitive diagnosis was achieved through arthroscopic-assisted biopsy. Rheumatology referrals revealed chondrocalcinosis of the knee in one patient. All patients had improved mouth opening and pain.

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Temporomandibular joint (TMJ) reconstruction is traditionally invasive. Several investigators have developed animal models, including mouse models, to study the TMJ. However, there are no detailed descriptions of a mouse model to be followed for additional research. The goal of this project was to study minimally invasive TMJ regeneration using tissue engineering in mice. As part of the project, a detailed mouse model was developed, which is described in this article. Eight carcasses were used to study the anatomy of the TMJ of the mouse and 36 mice were used to describe the surgical approach and perioperative management. The study showed similarities and differences when compared to humans. One mouse died suddenly 10 days postoperatively, while 35 mice survived the operation. Keratitis and wound dehiscence were the most common complications. Investigators reviewing this paper should be able to use this mouse model to further study TMJ regeneration in mice.

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Metaproteomics can provide critical information about biological systems, but peptides are found within a complex background of other peptides. This complex background can change across samples, in some cases drastically. Cofragmentation, the coelution of peptides with similar mass to charge ratios, is one factor that influences which peptides are identified in an LC-MS/MS experiment: it is dependent on the nature and complexity of this dynamic background. Metaproteomics applications are particularly susceptible to cofragmentation-induced bias; they have vast protein sequence diversity and the abundance of those proteins can span many orders of magnitude. We have developed a mechanistic model that determines the number of potentially cofragmenting peptides in a given sample (called cobia, https://github.com/bertrand-lab/cobia ). We then used previously published data sets to validate our model, showing that the resulting peptide-specific score reflects the cofragmentation "risk" of peptides. Using an Antarctic sea ice edge metatranscriptome case study, we found that more rare taxonomic and functional groups are associated with higher cofragmentation bias. We also demonstrate how cofragmentation scores can be used to guide the selection of protein- or peptide-based biomarkers. We illustrate potential consequences of cofragmentation for multiple metaproteomic approaches, and suggest practical paths forward to cope with cofragmentation-induced bias.

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Iron and light are recognized as limiting factors controlling Southern Ocean phytoplankton growth. Recent field-based evidence suggests, however, that manganese availability may also play a role. Here we examine the influence of iron and manganese on protein expression and physiology in Phaeocystis antarctica, a key Antarctic primary producer. We provide taxon-specific proteomic evidence to show that in-situ Southern Ocean Phaeocystis populations regularly experience stress due to combined low manganese and iron availability. In culture, combined low iron and manganese induce large-scale changes in the Phaeocystis proteome and result in reorganization of the photosynthetic apparatus. Natural Phaeocystis populations produce protein signatures indicating late-season manganese and iron stress, consistent with concurrently observed stimulation of chlorophyll production upon additions of manganese or iron. These results implicate manganese as an important driver of Southern Ocean productivity and demonstrate the utility of peptide mass spectrometry for identifying drivers of incomplete macronutrient consumption.

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Temporomandibular joint (TMJ) arthroscopy is a minimally invasive surgical approach for intra-articular TMJ diseases. Office-based arthroscopy using the smallest TMJ scope allows for good visualization, as well as the ability to lavage the joint in an office setting. This study aimed to assess the efficacy of an office-based TMJ arthroscopic technique. A retrospective evaluation of 363 patients with a TMJ disorder was performed. These patients underwent office-based arthroscopy using the OnPoint 1.2mm Scope System (Biomet Microfixation, Jacksonville, FL, USA) in Florida, USA, from July 2007. The following outcomes of the procedure were assessed: improvement in painless range of mandibular motion, pain on loading, and functional jaw pain; these were evaluated using a visual analog scale (VAS) over an average follow-up period of 263.81±142.1 days. The statistical analysis was performed using IBM SPSS Statistics version 20. Statistically significant improvements in TMJ pain and function, and other variables (P=0.001) were shown following TMJ arthroscopic lysis and lavage. Office-based arthroscopy using the OnPoint System was demonstrated to be a safe and efficient procedure for the treatment of patients with TMJ disorders as the first level of the algorithm of care.

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The aim of the present study was to assess the efficacy of using prophylactic embolisation of the internal maxillary artery to minimise the risk of bleeding during gap arthroplasty. We studied a prospective series of 14 patients with ankylosis of the temporomandibular joint (TMJ) between January 2011 and February 2016, who were under the care of one surgeon. They were all treated by embolisation of the internal maxillary artery 24hours before gap arthroplasty. The main outcome variable was estimated blood loss, and others included the need to extend the gap arthroplasty, and the risk of reankylosis. We studied nine women and five men, mean (SD) age 51 (18) years, seven with unilateral and seven with bilateral ankylosis. Their mean (SD) estimated blood loss was 136 (77) ml, which we considered to be minimal. Patients were followed-up at six-monthly intervals, during which time there was no reankylosis or limitation of mouth opening. No patient lost more than 250ml blood in total. Prophylactic embolisation of the internal maxillary artery seems to be beneficial and safe in the management of selected cases of ankylosis of the TMJ.

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