Tunicates are the sister group to the vertebrates, yet most species have a life cycle split between swimming larva and sedentary adult phases. During metamorphosis, larval neurons are replaced by adult-specific ones. The regulatory mechanisms underlying this replacement remain largely unknown. Using tissue-specific CRISPR/Cas9-mediated mutagenesis in the tunicate Ciona, we show that orthologs of conserved hindbrain and branchiomeric neuron regulatory factors Pax2/5/8 and Phox2 are required to specify the ‘neck’, a cellular compartment set aside in the larva to give rise to cranial motor neuron-like neurons post-metamorphosis. Using bulk and single-cell RNA-sequencing analyses, we characterize the transcriptome of the neck downstream of Pax2/5/8. We present evidence that neck-derived adult ciliomotor neurons begin to differentiate in the larva and persist through metamorphosis, contrary to the assumption that the adult nervous system is formed after settlement and the death of larval neurons during metamorphosis. Finally, we show that FGF signaling during the larval phase alters the patterning of the neck and its derivatives. Suppression of FGF converts neck cells into larval neurons that fail to survive metamorphosis, whereas prolonged FGF signaling promotes an adult neural stem cell-like fate.
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Fernandez-Valverde, Selene L (Ed.)
The papillae of tunicate larvae contribute sensory, adhesive, and metamorphosis-regulating functions that are crucial for the biphasic lifestyle of these marine, non-vertebrate chordates. We have identified additional molecular markers for at least 5 distinct cell types in the papillae of the model tunicate
Ciona , allowing us to further study the development of these organs. Using tissue-specific CRISPR/Cas9-mediated mutagenesis and other molecular perturbations, we reveal the roles of key transcription factors and signaling pathways that are important for patterning the papilla territory into a highly organized array of different cell types and shapes. We further test the contributions of different transcription factors and cell types to the production of the adhesive glue that allows for larval attachment during settlement, and to the processes of tail retraction and body rotation during metamorphosis. With this study, we continue working towards connecting gene regulation to cellular functions that control the developmental transition between the motile larva and sessile adult ofCiona .Free, publicly-accessible full text available March 13, 2025 -
Bossart, Janice L (Ed.)
Variation in tropical forest management directly affects biodiversity and provisioning of ecosystem services on a global scale, thus it is necessary to compare forests under different conservation approaches such as protected areas, payments for ecosystem services programs (PES), and ecotourism, as well as forests lacking any formal conservation plan. To examine the effectiveness of specific conservation approaches, we examined differences in forest structure and tree recruitment, including canopy cover; canopy height; seedling, sapling, and adult tree density; and average and total diameter at breast height (DBH) across 78 plots in 18 forests across Costa Rica representing protected areas, private forests utilizing PES and/or ecotourism, and private forests not utilizing these economic incentives. The effectiveness of conservation approaches in providing suitable primate habitat was assessed by conducting broad primate census surveys across a subset of eight forests to determine species richness and group encounter rate of three primate species: mantled howler monkey (
Alouatta palliata ), Central American spider monkey (Ateles geoffroyi ), and the white-faced capuchin monkey (Cebus imitator ). Only canopy height was significantly different across the three approaches, with protected areas conserving the tallest and likely oldest forests. Canopy height was also significantly associated with the group encounter rate for both mantled howler and spider monkeys, but not for capuchins. Total group encounter rate for all three monkey species combined was higher in incentivized forests than in protected areas, with capuchin and howler monkey group encounter rates driving the trend. Group encounter rate for spider monkeys was higher in protected areas than in incentivized forests. Incentivized conservation (PES and ecotourism) and protected areas are paragons of land management practices that can lead to variation in forest structure across a landscape, which not only protect primate communities, but support the dietary ecologies of sympatric primate species. -
Atmospheric aerosols exert a significant but highly uncertain effect on the global climate, and roughly half of these particles originate as small clusters formed by collisions between atmospheric trace vapors. These particles typically consist of acids, bases, and water, stabilized by salt bridge formation and a network of strong hydrogen bonds. We review spectroscopic studies of this process, focusing on the clusters likely to be involved in the first steps of particle formation and the intermolecular interactions governing their stability. These studies typically focus on determining structure and stability and have shown that acid-base chemistry in the cluster may violate chemical intuition derived from solution-phase behavior and that hydration of these clusters is likely to be complex to describe. We also suggest fruitful areas for extension of these studies and alternative spectroscopic techniques that have not yet been applied to this problem.
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We report progress on finite-volume determinations of heavy light-meson – Goldstone boson scattering phase shifts using the Luescher method on CLS 2+1 flavor gauge field ensembles. In a first iteration we will focus on D-meson – pion scattering in the elastic scattering region at various pion masses using ensembles with three lattice spacings. We employ ensembles on the CLS quark-mass trajectory with a fixed trace of the quark-mass matrix as well as ensembles with a strange-quark mass fixed close to its physical value, which will allow us to study both the light and the strange quark-mass dependence of positive parity heavy-light hadrons close to threshold.more » « less
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Kuperman, Alon (Ed.)Increasing the spatial and temporal density of data using networked sensors, known as the Internet of Things (IoT), can lead to enhanced productivity and cost savings in a host of industries. Where applications involve large outdoor expanses, such as farming, oil and gas, or defense, large regions of unelectrified land could yield significant benefits if instrumented with a high density of IoT systems. The major limitation of expanding IoT networks in such applications stems from the challenge of delivering power to each sensing device. Batteries, generators, and renewable sources have predominately been used to address the challenge, but these solutions require constant maintenance or are sensitive to environmental factors. This work presents a novel approach where conduction currents through soil are utilized for the wireless powering of sensor networks, initial investigation is within an 0.8-ha (2-acre) area. The technique is not line-of-sight, powers all devices simultaneously through near-field mechanics, and has the ability to be minimally invasive to the working environment. A theory of operation is presented and the technique is experimentally demonstrated in an agricultural setting. Scaling and transfer parameters are discussed.more » « less