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Butterfly wings display a diversity of cell types, including large polyploid scale cells, yet the molecular basis of such diversity is poorly understood. To explore scale cell diversity at a transcriptomic level, we employ single-cell RNA sequencing of ∼5,200 large cells (>6 μm) from 22.5- to 25-h male pupal forewings of the butterfly Bicyclus anynana. Using unsupervised clustering, followed by in situ hybridization, immunofluorescence, and CRISPR-Cas9 editing of candidate genes, we annotate various cell types on the wing. We identify genes marking non-innervated scale cells, pheromone-producing glandular cells, and innervated sensory cell types. We show that senseless , a zinc-finger transcription factor, and HR38 , a hormone receptor, determine the identity, size, and color of different scale cell types and are important regulators of scale cell differentiation. This dataset and the identification of various wing cell-type markers provide a foundation to compare and explore scale cell-type diversification across arthropod species. [Display omitted] • senseless is important for both scale cell specification and differentiation • HR38 is necessary for the development of hair-like scales and regulates scale color and size • cut mRNA expression is punctate and protein expression is non-homogenous in scale cells • Identified marker genes for wing cell types lay a foundation for future comparative work Butterfly wing tissues are composed of various cell types including differently shaped and colored scales, sensory and glandular cells, and epidermal cells. Prakash et al. use single-cell sequencing to identify markers of different cell types and show that HR38 and senseless regulate scale cell differentiation. [ABSTRACT FROM AUTHOR]

Butterfly wing scales can develop intricate cuticular nanostructures that produce silver colors, but the underlying genetic and physical basis of such colors is mostly unexplored. Here, we characterize different types of wild-type silver scales in Bicyclus anynana butterflies and show that the varying thickness of the air layer between two cuticular laminas is most important for producing silvery broadband reflectance. We then address the function of five genes— apterous A , Ultrabithorax , doublesex , Antennapedia , and optix— in silver scale development by examining crispants with either ectopic gains or losses of silver scales. Simultaneous transformations of three parameters—loss of the upper lamina, increased lower lamina thickness, and increased pigmentation—occur when silver scales become brown and vice versa when brown scales become silver. Antennapedia and optix are high-level regulators of different silver scale types and determine cell shape in both sexes. Moreover, Antennapedia is involved in determining ridge and crossrib orientation. [Display omitted] • Bilaminate scale structure increases silver reflectivity compared with a single lamina • Varying air gap layer is the key scale parameter to produce broadband silver colors • Antennapedia and optix determine cell shape, structure, and color in silver scales • Antennapedia regulates ridge and crossrib orientation in wing scales Silvery structural colors in butterfly wing scales are predominantly produced by bilaminate nanostructures with a sandwiched air layer, but their genetic and optical basis are unclear. Prakash et al. show that a bilaminate structure increases silver reflectivity and identify Antennapedia and optix as regulators of pigmentation, ultrastructure, and scale shape. [ABSTRACT FROM AUTHOR]

The problem of wind-induced flow in inland waters is drawing significant research attention given its relevance to a plethora of applications in wetlands including treatment designs, pollution reduction, and biogeochemical cycling. The present work addresses the role of wind induced turbulence and waves within an otherwise static water body in the presence of rigid and flexible emergent vegetation through flume experimentation and time series analysis. Because no prior example of Particle Imaging Velocimetry (PIV) experiments involving air–water and flexible oscillating components have been found in the literature, a spectral analysis framework is needed and proposed here to guide the analysis involving noise, wave and turbulence separation. The experiments reveal that wave and turbulence effects are simultaneously produced at the air–water interface and the nature of their coexistence is found to vary with different flow parameters including water level, mean wind speed, vegetation density and its flexibility. For deep water levels, signature of fine-scaled inertial turbulence is found at deeper layers of the water system. The wave action appears stronger close to the air–water interface and damped by the turbulence deeper inside the water system. As expected, wave action is found to be dominated in a certain frequency range driven by the wind forcing, while it is also diffused to lower frequencies by means of (wind-induced) oscillations in vegetation. Regarding the mean water velocity, existence of a counter-current flow and its switching to fully forward flow in the direction of the wind under certain combinations of flow parameters were studied. The relative importance of wave and turbulence to the overall energy, degree of anisotropy in the turbulent energy components, and turbulent momentum transport at different depths from the air–water interface and flow combinations were then quantified. The flume experiments reported here differ from previous laboratory studies in the related literature involving vegetation in the sense that the wave forcing is only present on the water surface contrary to a full-body excitation by tidal wave simulators and thus important in advancing the knowledge regarding a wider range of water resource problems. [ABSTRACT FROM AUTHOR]

Arsenic (As) biotransformation and release by indigenous bacteria from As rich groundwater was investigated. Metabolic landscape of 173 bacterial isolates indicated broad catabolic repertoire including abundance of As 5+ reductase activity and abilities in utilizing wide ranges of organic and inorganic respiratory substrates. Abundance of As homeostasis genes and utilization of hydrocarbon as carbon/electron donor and As 5+ as electron acceptor were noted within the isolates. Sediment microcosm study (for 300 days) showed a pivotal role of metal reducing facultative anaerobic bacteria in toxic As 3+ release in aqueous phase. Inhabitant bacteria catalyze As transformation and facilitate its release through a cascade of reactions including mineral bioweathering and As 5+ and/or Fe 3+ reduction activities. Compared to anaerobic incubation with As 5+ reducing strains, oxic state and/or incubation with As 3+ oxidizing bacteria resulted in reduced As release, thus indicating a strong role of such condition or biocatalytic mechanism in controlling in situ As contamination. [ABSTRACT FROM AUTHOR]