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ABSTRACT Using dissolved inorganic carbon (DIC) as a major carbon source, as autotrophs do, is complicated by the bedeviling nature of this substance. Autotrophs using the Calvin-Benson-Bassham cycle (CBB) are known to make use of a toolkit comprised of DIC transporters and carbonic anhydrase enzymes (CA) to facilitate DIC fixation. This minireview provides a brief overview of the current understanding of how toolkit function facilitates DIC fixation inCyanobacteriaand someProteobacteriausing the CBB and continues with a survey of the DIC toolkit gene presence in organisms using different versions of the CBB and other autotrophic pathways (reductive citric acid cycle, Wood-Ljungdahl pathway, hydroxypropionate bicycle, hydroxypropionate-hydroxybutyrate cycle, and dicarboxylate-hydroxybutyrate cycle). The potential function of toolkit gene products in these organisms is discussed in terms of CO₂and HCO₃⁻supply from the environment and demand by the autotrophic pathway. The presence of DIC toolkit genes in autotrophic organisms beyond those using the CBB suggests the relevance of DIC metabolism to these organisms and provides a basis for better engineering of these organisms for industrial and agricultural purposes. 

Abstract Cryogenic calorimetric experiments to search for neutrinoless double-beta decay ($$0\nu \beta \beta $$ $0\nu \beta \beta$) are highly competitive, scalable and versatile in isotope. The largest planned detector array, CUPID, is comprised of about 1500 individual Li$$_{2}$$ $_2^{}$$$^{100}$$ $_{}^{100}$MoO$$_4$$ $_4^{}$detector modules with a further scale up envisioned for a follow up experiment (CUPID-1T). In this article, we present a novel detector concept targeting this second stage with a low impedance TES based readout for the Li$$_2$$ $_2^{}$MoO$$_4$$ $_4^{}$absorber that is easily mass-produced and lends itself to a multiplexed readout. We present the detector design and results from a first prototype detector operated at the NEXUS shallow underground facility at Fermilab. The detector is a 2-cm-side cube with 21 g mass that is strongly thermally coupled to its readout chip to allow rise-times of$$\sim $$ $\sim$0.5 ms. This design is more than one order of magnitude faster than present NTD based detectors and is hence expected to effectively mitigate backgrounds generated through the pile-up of two independent two neutrino decay events coinciding close in time. Together with a baseline resolution of 1.95 keV (FWHM) these performance parameters extrapolate to a background index from pile-up as low as$$5\cdot 10^{-6}$$ $5·{10}^{-6}$ counts/keV/kg/yr in CUPID size crystals. The detector was calibrated up to the MeV region showing sufficient dynamic range for$$0\nu \beta \beta $$ $0\nu \beta \beta$searches. In combination with a SuperCDMS HVeV detector this setup also allowed us to perform a precision measurement of the scintillation time constants of Li$$_2$$ $_2^{}$MoO$$_4$$ $_4^{}$, which showed a primary component with a fast O(20 $$\upmu $$ $\mu$s) time scale. 

ABSTRACT Autotrophic bacteria are able to fix CO₂in a great diversity of habitats, even though this dissolved gas is relatively scarce at neutral pH and above. As many of these bacteria rely on CO₂fixation by ribulose 1,5-bisphospate carboxylase/oxygenase (RubisCO) for biomass generation, they must compensate for the catalytical constraints of this enzyme with CO₂-concentrating mechanisms (CCMs). CCMs consist of CO₂and HCO₃⁻transporters and carboxysomes. Carboxysomes encapsulate RubisCO and carbonic anhydrase (CA) within a protein shell and are essential for the operation of a CCM in autotrophicBacteriathat use the Calvin-Benson-Basham cycle. Members of the genusThiomicrospiralack genes homologous to those encoding previously described CA, and prior to this work, the mechanism of function for their carboxysomes was unclear. In this paper, we provide evidence that a member of the recently discovered iota family of carbonic anhydrase enzymes (ιCA) plays a role in CO₂fixation by carboxysomes from members ofThiomicrospiraand potentially otherBacteria. Carboxysome enrichments fromThiomicrospira pelophilaandThiomicrospira aerophilawere found to have CA activity and contain ιCA, which is encoded in their carboxysome loci. When the gene encoding ιCA was interrupted inT. pelophila, cells could no longer grow under low-CO₂conditions, and CA activity was no longer detectable in their carboxysomes. WhenT. pelophilaιCA was expressed in a strain ofEscherichia colilacking native CA activity, this strain recovered an ability to grow under low CO₂conditions, and CA activity was present in crude cell extracts prepared from this strain. IMPORTANCEHere, we provide evidence that iota carbonic anhydrase (ιCA) plays a role in CO₂fixation by some organisms with CO₂-concentrating mechanisms; this is the first time that ιCA has been detected in carboxysomes. While ιCA genes have been previously described in other members of bacteria, this is the first description of a physiological role for this type of carbonic anhydrase in this domain. Given its distribution in alkaliphilic autotrophic bacteria, ιCA may provide an advantage to organisms growing at high pH values and could be helpful for engineering autotrophic organisms to synthesize compounds of industrial interest under alkaline conditions. 

This article presents constraints on dark-matter-electron interactions obtained from the first underground data-taking campaign with multiple SuperCDMS HVeV detectors operated in the same housing. An exposure of $7.63\mathrm{g}\text{−}\mathrm{days}$is used to set upper limits on the dark-matter-electron scattering cross section for dark matter masses between 0.5 and $1000\mathrm{MeV}/c^2$, as well as upper limits on dark photon kinetic mixing and axionlike particle axioelectric coupling for masses between 1.2 and $23.3\mathrm{eV}/c^2$. Compared to an earlier HVeV search, sensitivity was improved as a result of an increased overburden of 225 meters of water equivalent, an anticoincidence event selection, and better pile-up rejection. In the case of dark-matter-electron scattering via a heavy mediator, an improvement by up to a factor of 25 in cross section sensitivity was achieved. Published by the American Physical Society2025