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Bacteria on steroids
Long-chain alkanes preserved in a Martian mudstone
Organic molecules preserved in ancient Martian rocks provide a critical record of the past habitability of Mars and could be chemical biosignatures. Experiments conducted by the Sample Analysis at Mars instrument onboard the Curiosity rover have previously reported several classes of indigenous chlorinated and sulfur-containing organic compounds in Gale crater sedimentary rocks, with chemical structures of up to six carbons. Here, we report the detection of decane (C 10 H 22 ), undecane (C 11 H 24 ), and dodecane (C 12 H 26 ) at the tens of pmol level, released from the Cumberland drilled mudstone sample, using a modified SAM analytical procedure optimized for the detection of larger organic molecules. Laboratory experiments support the hypothesis that the alkanes detected were originally preserved in the mudstone as long-chain carboxylic acids. The origin of these molecules remains uncertain, as they could be derived from either abiotic or biological sources.
Correction for Magesh et al., Co-zorbs: Motile, multispecies biofilms aid transport of diverse bacterial species
Correction for Quach et al., Deep learning–driven bacterial cytological profiling to determine antimicrobial mechanisms in <i>Mycobacterium tuberculosis</i>
Correction to Supporting Information for Walters et al., Identification of FSH-regulated and estrous stage–specific transcriptional networks in mouse ovaries
CERN releases detailed plans for supercollider — but no hints about funding
Large language models for identifying social determinants of health
Daily briefing: Mass layoffs across US health agencies
Correction to Supporting Information for Stransky et al., Toward a CRISPR-based mouse model of <i>Vhl</i> -deficient clear cell kidney cancer: Initial experience and lessons learned
Correction to Supporting Information for Struve et al., Systematic changes in circumpolar dust transport to the Subantarctic Pacific Ocean over the last two glacial cycles
Reply to Deter-Wolf et al.: Laser-stimulated fluorescence of Chancay tattoos
Laser imaging of ancient tattoos: New tools illuminate established knowledge
Reply to Wang: Improving large language model approaches for identifying social determinants of health from clinical notes
Xylem embolism refilling revealed in stems of a weedy grass
Plant hydraulic dysfunction by embolism formation can impair photosynthesis, growth, and reproduction and, in severe cases, lead to death. Embolism reversal, or “refilling,” is a hypothesized adaptive process in which xylem functionality is rapidly and sustainably restored. This study investigated xylem embolism refilling during recovery from severe drought stress using entirely noninvasive measurements of the same plants. These results were considered in relation to functional traits to address long-standing gaps in understanding the consequences of severe drought stress. Leaf and stem xylem embolism as well as transpiration, photosynthesis, and stem water potential were characterized nondestructively on intact barnyard grass plants during an acute drought event. Plants were rewatered and returned to growth conditions for 10 d, during which time recovery of stem xylem embolism and transpiration were monitored. Leaf xylem embolism and declines in leaf gas exchange occurred mostly between −1.0 MPa and −2.0 MPa, whereas stem xylem embolism occurred mostly between −3.0 MPa and −4.0 MPa. In all measured plants, which included embolism levels up to 88%, stem xylem embolism reversed completely within 24 h after rewatering, and this refilling supported recovery of transpiration and growth after plants were returned to growth conditions. This study provides direct evidence of complete and functional stem xylem refilling. These results present a clear need to elucidate underlying mechanisms and the adaptive significance of this phenomenon as well as its prevalence in nature.