Molecular and morphological evidence supports transferring Sacosperma ( Rubiaceae , Rubioideae ) from Spermacoceae to Knoxieae

The genus Sacosperma ( Rubiaceae ) comprises two species of lianas occurring in tropical African rainforests. It is currently placed in tribe Spermacoceae , but morphological evidence suggests that placement in tribe Knoxieae might be more appropriate. This study presents the first molecular analysis of Sacosperma , which supports its placement within Knoxieae , where it is sister to the East African genus Rhodopentas . A close relationship between these two genera has never been considered before, and molecular data alone cannot resolve whether they should be treated as distinct genera. To address this, we provide a comparative analysis of Sacosperma and Rhodopentas based on morphology, anatomy, biogeography, and climate preference. The recognition of Sacosperma and Rhodopentas as two separate genera is justified, given a number of morphological differences (e.g., habit, imperforate tracheary elements, domatia, stipules, inflorescences, flower size and color), their biogeography (West and Central African vs. East African), and climate preferences (broad vs. narrow climate envelope). Sacosperma and Rhodopentas share a common ancestor that has likely diverged morphologically in response to differing ecological conditions.

Sex-specific single transcript level atlas of vasopressin and its receptor (AVPR1a) in the mouse brain

Vasopressin (AVP), a nonapeptide synthesized predominantly by magnocellular hypothalamic neurons, is conveyed to the posterior pituitary via the pituitary stalk, where AVP is secreted into the circulation. Known to regulate blood pressure and water homeostasis, it also modulates diverse social behaviors, such as pair bonding, social recognition, and cognition in mammals, including humans. Importantly, AVP modulates social behaviors in a sex-specific manner, perhaps due to sex differences in the distribution in the brain of AVP and its main receptor AVPR1a. There is a corpus of integrative studies for the expression of AVP and AVPR1a in various brain regions, and their functions in modulating central and peripheral actions. In order to purposefully address sexually dimorphic and novel roles of AVP on central and peripheral functions through its AVPR1a, we utilized RNAscope to map Avp and Avpr1a single transcript expression in the mouse brain. As the most comprehensive atlas of AVP and AVPR1a in the mouse brain, this compendium highlights the importance of newly identified AVP/AVPR1a neuronal nodes that may stimulate further functional studies.

Deep neural networks to register and annotate cells in moving and deforming nervous systems

Aligning and annotating the heterogeneous cell types that make up complex cellular tissues remains a major challenge in the analysis of biomedical imaging data. Here, we present a series of deep neural networks that allow for automatic non-rigid registration and cell identification, developed in the context of freely moving and deforming invertebrate nervous systems. A semi-supervised learning approach was used to train a Caenorhabditis elegans registration network (BrainAlignNet) that aligns pairs of images of the bending C. elegans head with single-pixel-level accuracy. When incorporated into an image analysis pipeline, this network can link neurons over time with 99.6% accuracy. This network could also be readily purposed to align neurons from the jellyfish Clytia hemisphaerica , an organism with a vastly different body plan and set of movements. A separate network (AutoCellLabeler) was trained to annotate >100 neuronal cell types in the C. elegans head based on multi-spectral fluorescence of genetic markers. This network labels >100 different cell types per animal with 98% accuracy, exceeding individual human labeler performance by aggregating knowledge across manually labeled datasets. Finally, we trained a third network (CellDiscoveryNet) to perform unsupervised discovery of >100 cell types in the C. elegans nervous system: by comparing multi-spectral imaging data from many animals, it can automatically identify and annotate cell types without using any human labels. The performance of CellDiscoveryNet matched that of trained human labelers. These tools should be immediately useful for a wide range of biological applications and should be straightforward to generalize to many other contexts requiring alignment and annotation of dense heterogeneous cell types in complex tissues.

Two classes of amine/glutamate multi-transmitter neurons innervate Drosophila internal male reproductive organs

The essential outcome of a successful mating is the transfer of genetic material from males to females in sexually reproducing animals from insects to mammals. In males, this culminates in ejaculation, a precisely timed sequence of organ contractions driven by the concerted activity of interneurons, sensory neurons, and motor neurons. Although central command circuits that trigger copulation have been mapped, the motor architecture and the chemical logic that couple specific neuronal subclasses to organ-specific contractility, seminal fluid secretion, and sperm emission remain largely uncharted. This gap in knowledge limits our ability to explain how neural circuits adapt to varying contexts and how their failure contributes to infertility. Here, we present an in-depth anatomical and functional analysis of the motor neurons that innervate the internal male reproductive tract of Drosophila melanogaster . We identify two classes of multi-transmitter motor neurons based on neurotransmitter usage, namely octopamine and glutamate neurons (OGNs) and serotonin and glutamate neurons (SGNs), each with a biased pattern of innervation: SGNs predominate in the accessory glands, OGNs in the ejaculatory duct, with equal contributions of each to the seminal vesicles. Both classes co-express vesicular transporters for glutamate (vGlut) and amines (vMAT), confirming their dual chemical identity. Their target organs differentially express receptors for glutamate, octopamine, and serotonin, suggesting combinatorial neuromodulation of contractility. Functional manipulations show that SGNs are essential for male fertility but OGNs are dispensable. Glutamatergic transmission from both classes is also dispensable for fertility. These findings provide the first high-resolution map linking multi-transmitter motor neurons to specific reproductive organs, reveal an unexpected division of labor between serotonergic and octopaminergic signaling pathways, and establish a framework for dissecting conserved neural principles that govern ejaculation and male fertility.

Heterochronic transcription factor expression drives cone-dominant retina development in 13-lined ground squirrels

Evolutionary adaptation to diurnal vision in ground squirrels has led to the development of a cone-dominant retina, in stark contrast to the rod-dominant retinas of most mammals. The molecular mechanisms driving this shift remain largely unexplored. Here, we perform single-cell RNA sequencing and chromatin accessibility profiling (scATAC-Seq) across developmental retinal neurogenesis in the 13-lined ground squirrel (13LGS) to uncover the regulatory basis of this adaptation. We find that 13LGS cone photoreceptors arise not only from early-stage neurogenic progenitors, as seen in rod-dominant species like mice, but also from late-stage neurogenic progenitors. This extended period of cone generation is driven by a heterochronic shift in transcription factor expression, with cone-promoting factors such as Onecut2 , Pou2f1 , and Zic3 remaining active in late-stage progenitors, and factors that promote cone differentiation such as Thrb , Rxrg , and Mef2c expressed precociously in late-stage neurogenic progenitors. Functional analyses reveal that Zic3 and Mef2c are sufficient to promote cone and repress rod photoreceptor-specific gene expression and act through species-specific regulatory elements that drive their expression in late-stage progenitors. These results demonstrate that modifications to gene regulatory networks underlie the development of cone-dominant retinas and provide insight into mechanisms of sensory adaptation and potential strategies for cone photoreceptor regeneration in vision disorders.

Neural coding of multiple motion speeds in visual cortical area MT

Motion speed is a salient cue for visual segmentation, yet how the visual system represents and differentiates multiple speeds remains unclear. Here, we investigated the encoding and decoding of multiple speeds. We first characterized the perceptual capacity of human and macaque subjects to segment overlapping stimuli moving at different speeds. We then determined how neurons in area MT of macaque monkeys represent multiple speeds. We found that the responses of MT neurons to two speeds showed a robust bias toward the faster speed component. This faster-speed bias occurred when both speeds were slow (≤20°/s) and diminished as stimulus speed increased. Our findings can be explained by a modified divisive normalization model, in which the weights for the speed components are proportional to the responses of a population of neurons (the weighting pool) with a broad range of speed preferences, elicited by the individual speeds. Regarding decoding, a classifier could distinguish MT responses to two speeds from those to a corresponding log-mean speed. We further found that it was possible to decode two speeds from the MT population response, supporting the theoretical framework of coding multiplicity in neuronal populations. The decoded speeds can account for perceptual performance in segmenting two speeds with a large (4x) but not a small (2x) separation. Our findings help define the neural coding rule of multiple speeds. The faster-speed bias in MT could benefit important behavioral tasks, such as figure-ground segregation, as figural objects tend to move faster than the background in the natural environment.

Single transcript level atlas of oxytocin and the oxytocin receptor in the mouse brain

Oxytocin (OXT), a primitive nonapeptide known to regulate reproduction and social behaviors, is synthesized primarily in the hypothalamus and is secreted via the hypophyseal-portal system of the posterior pituitary gland. In line with the premise that pituitary hormones, traditionally thought of as regulators of single targets, display an array of central and peripheral actions, we found that OXT directly affects bone and body composition. The effect of OXT on bone remodeling is physiologically relevant, as elevated OXT levels during pregnancy and lactation cause calcium mobilization from the maternal skeleton for intergenerational calcium transfer towards fetal bone mineralization. There is an equally large body of evidence that has established the presence of OXT receptors (OXTRs) in the brain through which central functions, such as social bonding, and peripheral functions, such as the regulation of body composition, are exerted. To purposefully address effects of OXT on the brain, we used RNAscope to map OXT and OXTR expression, at the single transcript level, in the whole female and male mouse brains. Identification of brain nuclei with the highest OXT and OXTR transcript density sheds further light on functional OXT nodes that could be further interrogated experimentally to define new physiologic circuitry.

Romantic Realisms

This collection of essays builds on recent scholarship on German philosophies of nature ( Naturphilosophie ) to argue for a Romantic aesthetics grounded in nature and the real. It brings researchers from philosophy, aesthetics, and literary studies into dialogue around key writers like F. W. J. Schelling, Novalis, and the Schlegel brothers, and pushes back against some of the conventional formalist and psychologizing frameworks through which Romanticism has been viewed traditionally. Instead, these contributions develop a picture of Romanticism as not only having aimed to ‘represent’ things conceptually or linguistically, but as capable of acting on, existing within, and indeed participating in processes of worldmaking. The resulting image is of a Romanticism pushing at the boundaries of materialist and idealist conceptualizations of the real in equal measure. The contributions fall along two main axes, represented by two sections and an afterword. The first section addresses Schelling directly and explores the potential of his philosophy for literary and aesthetic theory. The second section brings Schelling into dialogue with literary practices around 1800 to address broader ramifications for our understanding of authors like Novalis, Hoffmann, Coleridge, and Droste-Hülshoff, also seeking to establish the contemporary viability of Schelling’s thought and its long-overlooked cultural ramifications, including in contemporary environmental thinking.

The Role of Buffer Gas in Shaping the D1 Line Spectrum of Potassium Vapour

In this study, we investigate the effect of buffer gas and magnetic field onthe spectral line shapes of the potassium D1 transition using sealed vapourcells filled with varying amounts of neon as a buffer gas. Employing adual-temperature control system, we independently manipulate the cell body andstem temperatures to explore Doppler and collisional effects on the spectrum.Our results show how the Voigt spectral profile changes from Gaussian- toLorentzian-dominated forms due to pressure broadening and shifts caused bycollisions between potassium atoms and neon. Our measurements are in excellentagreement with the literature values for potassium-neon collisions. For thefirst time we were able to incorporate the buffer-gas shift and broadening intothe modified Voigt profile via the ElecSus code, and found excellent agreementbetween the predicted and measured line profiles. We also analyse the potassiumD1 spectral lines in the hyperfine Paschen-Back regime using strong magneticfields, demonstrating how Zeeman splitting modifies the pressure-broadened lineshape. This work provides valuable insights into collision-induced broadeningand shifts, enhancing our understanding of potassium spectroscopy and itsapplication in the development of advanced magneto-optical filters for solarphysics and other applications.

Should Surgeons Share Experiences of Regret With Patients?