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ABSTRACT We describe the metagenome composition, community functional annotation, and prokaryote diversity in calcareous stromatolites from a dry stream bed of the San Felipe Creek in the Anza Borrego Desert. Analyses show a community capable of nitrogen fixation, assimilatory nitrate reduction, biofilm formation, quorum sensing, and potential thick-walled akinete formation for desiccation resistance. 

IntroductionThe medical and recreational use of cannabis has increased in the United States. Its chronic use can have detrimental effects on the neurobiology of the brain—effects that are age-dependent. This was an exploratory study looking at the effects of chronically inhaled vaporized cannabis on brain structure in adult female mice. MethodsAdult mice were exposed daily to vaporized cannabis (10.3% THC and 0.05% CBD) or placebo for 21 days. Following cessation of treatment mice were examined for changes in brain structure using voxel-based morphometry and diffusion weighted imaging MRI. Data from each imaging modality were registered to a 3D mouse MRI atlas with 139 brain areas. ResultsMice showed volumetric changes in the forebrain particularly the prefrontal cortex, accumbens, ventral pallidum, and limbic cortex. Many of these same brain areas showed changes in water diffusivity suggesting alterations in gray matter microarchitecture. DiscussionThese data are consistent with much of the clinical findings on cannabis use disorder. The sensitivity of the dopaminergic system to the daily exposure of vaporized cannabis raises concerns for abuse liability in drug naïve adult females that initiate chronic cannabis use. 

Abstract The genus Acacia is a large group of woody legumes containing an enormous amount of morphological diversity in leaf shape. This diversity is at least in part the result of an innovation in leaf development where many Acacia species are capable of developing leaves of both bifacial and unifacial morphologies. While not unique in the plant kingdom, unifaciality is most commonly associated with monocots, and its developmental genetic mechanisms have yet to be explored beyond this group. In this study, we identify an accession of Acacia crassicarpa with high regeneration rates and isolate a clone for genome sequencing. We generate a chromosome-level assembly of this readily transformable clone, and using comparative analyses, confirm a whole-genome duplication unique to Caesalpinoid legumes. This resource will be important for future work examining genome evolution in legumes and the unique developmental genetic mechanisms underlying unifacial morphogenesis in Acacia. 

ABSTRACT Vectors of infectious disease include several species of Aedes mosquitoes. The life cycle of Aedes aegypti, the yellow fever mosquito, consists of a terrestrial adult and an aquatic larval life stage. Developing in coastal waters can expose larvae to fluctuating salinity, causing salt and water imbalance, which is addressed by two prime osmoregulatory organs – the Malpighian tubules (MTs) and anal papillae (AP). Voltage-gated ion channels (VGICs) have recently been implicated in the regulation of ion transport in the osmoregulatory epithelia of insects. In the current study, we: (i) generated MT transcriptomes of freshwater-acclimated and brackish water-exposed larvae of Ae. aegypti, (ii) detected expression of several voltage-gated Ca2+, K+, Na+ and non-ion-selective ion channels in the MTs and AP using transcriptomics, PCR and gel electrophoresis, (iii) demonstrated that mRNA abundance of many altered significantly following brackish water exposure, and (iv) immunolocalized CaV1, NALCN, TRP/Painless and KCNH8 in the MTs and AP of larvae using custom-made antibodies. We found CaV1 to be expressed in the apical membrane of MTs of both larvae and adults, and its inhibition to alter membrane potentials of this osmoregulatory epithelium. Our data demonstrate that multiple VGICs are expressed in osmoregulatory epithelia of Ae. aegypti and may play an important role in the autonomous regulation of ion transport. 

Abstract As renewed interest in human space-exploration intensifies, a coherent and modernized strategy for mission design and planning has become increasingly crucial. Biotechnology has emerged as a promising approach to increase resilience, flexibility, and efficiency of missions, by virtue of its ability to effectively utilize in situ resources and reclaim resources from waste streams. Here we outline four primary mission-classes on Moon and Mars that drive a staged and accretive biomanufacturing strategy. Each class requires a unique approach to integrate biomanufacturing into the existing mission-architecture and so faces unique challenges in technology development. These challenges stem directly from the resources available in a given mission-class—the degree to which feedstocks are derived from cargo and in situ resources—and the degree to which loop-closure is necessary. As mission duration and distance from Earth increase, the benefits of specialized, sustainable biomanufacturing processes also increase. Consequentially, we define specific design-scenarios and quantify the usefulness of in-space biomanufacturing, to guide techno-economics of space-missions. Especially materials emerged as a potentially pivotal target for biomanufacturing with large impact on up-mass cost. Subsequently, we outline the processes needed for development, testing, and deployment of requisite technologies. As space-related technology development often does, these advancements are likely to have profound implications for the creation of a resilient circular bioeconomy on Earth. 

Abstract Myotonic dystrophy type 2 (DM2) is a genetic disease caused by expanded CCTG DNA repeats in the first intron of CNBP. The number of CCTG repeats in DM2 patients ranges from 75 to 11,000, yet little is known about the molecular mechanisms responsible for repeat expansions or contractions. We developed an experimental system in Saccharomyces cerevisiae that enables the selection of large-scale contractions of (CCTG)100 within the intron of a reporter gene and subsequent genetic analysis. Contractions exceeded 80 repeat units, causing the final repetitive tract to be well below the threshold for disease. We found that Rad51 and Rad52 are involved in these massive contractions, indicating a mechanism that uses homologous recombination. Srs2 helicase was shown previously to stabilize CTG, CAG, and CGG repeats. Loss of Srs2 did not significantly affect CCTG contraction rates in unperturbed conditions. In contrast, loss of the RecQ helicase Sgs1 resulted in a 6-fold decrease in contraction rate with specific evidence that helicase activity is required for large-scale contractions. Using a genetic assay to evaluate chromosome arm loss, we determined that CCTG and reverse complementary CAGG repeats elevate the rate of chromosomal fragility compared to a short-track control. Overall, our results demonstrate that the genetic control of CCTG repeat contractions is notably distinct among disease-causing microsatellite repeat sequences. 

Abstract Here, we report the discovery of a novel Sediminibacterium sequenced from laboratory cultures of freshwater stream cyanobacteria from sites in Southern California, grown in BG11 medium. Our genome-wide analyses reveal a highly contiguous and complete genome (97% BUSCO) that is placed within sediminibacterial clades in phylogenomic analyses. Functional annotation indicates the presence of genes that could be involved in mutualistic/commensal relationship with associated cyanobacterial hosts.