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Citrullination is a post-translational modification (PTM) of arginine that is crucial for several physiological processes, including gene regulation and neutrophil extracellular trap formation. Despite recent advances, studies of protein citrullination remain challenging due to the difficulty of accessing proteins homogeneously citrullinated at a specific site. Herein, we report a technology that enables the site-specific incorporation of citrulline (Cit) into proteins in mammalian cells. This approach exploits an engineered E. coli -derived leucyl tRNA synthetase-tRNA pair that incorporates a photocaged-citrulline (SM60) into proteins in response to a nonsense codon. Subsequently, SM60 is readily converted to Cit with light in vitro and in living cells. To demonstrate the utility of the method, we biochemically characterize the effect of incorporating Cit at two known autocitrullination sites in Protein Arginine Deiminase 4 (PAD4, R372 and R374) and show that the R372Cit and R374Cit mutants are 181- and 9-fold less active than the wild-type enzyme. This technology possesses the potential to decipher the biology of citrullination. Citrullination of arginine is crucial for several physiological processes. Here the authors report the site-specific incorporation of citrulline into proteins in mammalian cells using an engineered tRNA synthetase/tRNA pair and a photocaged-citrulline.

Significant progress has been made in the treatment and outcome of breast cancer. Some of the most dramatic strides have been in the surgical management of breast cancer. Breast-conserving therapy (BCT), including wide local excision of the tumor followed by irradiation, has become a standard treatment option for women with early-stage invasive breast cancer. Large cooperative group trials have contributed to the paradigm shift from mastectomy to BCT. This review reports the landmark BCT trials that provided the data for current surgical practices. The review also describes the body of literature contributing to the increasing use of oncoplastic techniques for patients undergoing BCT.

The 2023 Canadian forest fires have been extreme in scale and intensity with more than seven times the average annual area burned compared to the previous four decades 1 . Here, we quantify the carbon emissions from these fires from May to September 2023 on the basis of inverse modelling of satellite carbon monoxide observations. We find that the magnitude of the carbon emissions is 647 TgC (570–727 TgC), comparable to the annual fossil fuel emissions of large nations, with only India, China and the USA releasing more carbon per year 2 . We find that widespread hot–dry weather was a principal driver of fire spread, with 2023 being the warmest and driest year since at least 1980 3 . Although temperatures were extreme relative to the historical record, climate projections indicate that these temperatures are likely to be typical during the 2050s, even under a moderate climate mitigation scenario (shared socioeconomic pathway, SSP 2–4.5) 4 . Such conditions are likely to drive increased fire activity and suppress carbon uptake by Canadian forests, adding to concerns about the long-term durability of these forests as a carbon sink 5 – 8 . Satellite carbon monoxide observations show that carbon emissions from the 2023 Canadian forest fires are comparable to the annual fossil fuel emissions of large nations.

Tyrosine sulfation is an important post-translational modification found in higher eukaryotes. Here we report an engineered tyrosyl-tRNA synthetase/tRNA pair that co-translationally incorporates O -sulfotyrosine in response to UAG codons in Escherichia coli and mammalian cells. This platform enables recombinant expression of eukaryotic proteins homogeneously sulfated at chosen sites, which was demonstrated by expressing human heparin cofactor II in mammalian cells in different states of sulfation. The authors used an expanded genetic code to incorporate sulfated tyrosine into specific sites of proteins expressed in E. coli and mammalian cells and showed that sulfation of tyrosine at different sites had different functions.

Humans have significantly altered the energy balance of the Earth’s climate system mainly not only by extracting and burning fossil fuels but also by altering the biosphere and using halocarbons. The 3rd US National Climate Assessment pointed to a need for a system of indicators of climate and global change based on long-term data that could be used to support assessments and this led to the development of the National Climate Indicators System (NCIS). Here we identify a representative set of key atmospheric indicators of changes in atmospheric radiative forcing due to greenhouse gases (GHGs), and we evaluate atmospheric composition measurements, including non-CO2GHGs for use as climate change indicators in support of the US National Climate Assessment. GHG abundances and their changes over time can provide valuable information on the success of climate mitigation policies, as well as insights into possible carbon-climate feedback processes that may ultimately affect the success of those policies. To ensure that reliable information for assessing GHG emission changes can be provided on policy-relevant scales, expanded observational efforts are needed. Furthermore, the ability to detect trends resulting from changing emissions requires a commitment to supporting long-term observations. Long-term measurements of greenhouse gases, aerosols, and clouds and related climate indicators used with a dimming/brightening index could provide a foundation for quantifying forcing and its attribution and reducing error in existing indicators that do not account for complicated cloud processes.

Fires have a significant impact on the regional carbon budget, the ecosystem, and public health. We analyzed the fire dynamics and its impact on carbon flux across three fire prone regions in South Asia, Region-1 (southwestern Nepal, Uttarakhand), Region-2 (central India), and Region-3 (northeast India) from 2010 to 2021, with a focus on the significant fire season of February, March, and April (FMA) of 2021. We find high burned areas (5000–10 000 km2), and fire carbon emissions (0.3–4 TgC season–1) across these regions in FMA, 2021, as compared to a climatological mean from 2010–2020. Each of the three regions shows distinct drivers that preceded the fires. In Region-1, snow-induced soil moisture deficits drive fire activity, leading to a subsequent decline in gross primary production . In Region-2, human activities, likely cropland burning, contributed to the forest fire. In Region-3, the scattered distribution of burned areas hints that human activity is the likely cause of the forest fire. During FMA, 2021, fire carbon emission in Region-1 (∼4 TgC) were almost twice of the fossil fuel emissions (∼2.2 TgC), while in Region-2 (∼3.8 TgC), it remained below fossil fuel emissions (∼16 TgC). In both regions, emissions from forests and croplands contributed equally to the total fire carbon emissions. In Region-3, fire carbon emissions exceeded fossil fuel emissions in 2012 (∼4.7 TgC), 2013 (∼6.18 TgC), and 2014 (∼9.75 TgC) but remained lower in 2021 (∼3.37 TgC), with most emissions originating from forests. This analysis highlights the critical role of forest fires in the carbon budget, the ecosystem and the need for better forest carbon management.

A growing number of space‐based platforms, like the Orbiting Carbon Observatory (OCO‐2 and OCO‐3) missions, observe Earth's atmospheric carbon dioxide CO2$\\left(\\mathrm{C}{\\mathrm{O}}_{\\mathrm{2}}\\right)$concentrations with high accuracy and precision. With the original goal of constraining natural CO2$\\mathrm{C}{\\mathrm{O}}_{\\mathrm{2}}$fluxes at regional to global scales, these instruments have now become popular tools for studying anthropogenic emissions from cities around the world. As signatories of the Paris Climate Agreement are expected to produce nationally determined contributions (NDC) to global carbon emissions, continued monitoring, reporting, and verification (MRV) of these estimates will be essential. While the use of OCO‐2 and OCO‐3 missions for MRV purposes is increasing, several physical and environmental factors limit data collection. Using the continental United States as a test case, the influences of orbital mechanics and environmental factors on local‐ and national‐level emissions estimates are explored through a series of linear and multi‐linear regressions to predict each instrument's effective revisit time. Results suggest that, due to environmental factors, western regions of the U.S. are more likely to be constrained at a sub‐annual scale than eastern regions, with effective instrument revisit times <30${< } 30$days. East coast cities have effective revisit times >30${ >} 30$days; however, this varies seasonally. The characteristics of the instruments' orbits also vary the frequency of urban observations in both space and time. Implications for observation‐derived emission estimates at local and national scales and remedies for such shortcomings in future missions are discussed. Plain Language Summary Carbon dioxide CO2$\\left(\\mathrm{C}{\\mathrm{O}}_{\\mathrm{2}}\\right)$is a key driver of global climate change and the ability to monitor human‐based emissions of this gas is crucial for quantifying the effectiveness of carbon‐reduction policies. In recent years, space‐based platforms have provided atmospheric CO2$\\mathrm{C}{\\mathrm{O}}_{\\mathrm{2}}$observations with near‐global coverage and efforts to ingest these data into local, regional, and national carbon accounting methodologies have been successful. However, space‐based observations are influenced by physical and environmental factors that affect their coverage. This study investigated these factors and determined that the time needed to constrain emissions varies among cities within the United States. Key factors that affect these space‐based platforms include the type of orbit they are in, the location of clouds in Earth's atmosphere, and the distribution of atmospheric aerosols. Results show that cities on the west coast are more frequently observed than cities in the northeast. These limitations should be considered when cities are seeking to monitor their emission reduction efforts with space‐based technologies. Key Points Orbital mechanics and environmental factors limit the ability of OCO‐2 and OCO‐3 to collect data in space and time Understanding when and where these effects are most prevalent informs city‐level monitoring, reporting, and verification (MRV) goals Our findings can inform local MRV efforts around the world, providing more realistic spatiotemporal resolutions when using space‐based data