nils-herrmann/clean_scirepeval huggingface dataset:
Bumblebees can detect floral humidity
Venue: The Journal of Experimental Biology

Floral humidity, a region of elevated humidity in the headspace of the flower, occurs in many plant species and may add to their multimodal floral displays. So far, the ability to detect and respond to floral humidity cues has been only established for hawkmoths when they locate and extract nectar while hovering in front of some moth-pollinated flowers. To test whether floral humidity can be used by other more widespread generalist pollinators, we designed artificial flowers that presented biologically relevant levels of humidity similar to those shown by flowering plants. Bumblebees showed a spontaneous preference for flowers that produced higher floral humidity. Furthermore, learning experiments showed that bumblebees are able to use differences in floral humidity to distinguish between rewarding and non-rewarding flowers. Our results indicate that bumblebees are sensitive to different levels of floral humidity. In this way floral humidity can add to the information provided by flowers and could impact pollinator behaviour more significantly than previously thought.
Skeletal muscle thermogenesis enables aquatic life in the smallest marine mammal
Venue: Science

Keeping warm when small Several mammal species live in cold-water environments, enabled by adaptations such as blubber and large size. A notable exception to this rule is the sea otter, a species that is orders of magnitude smaller and skinnier than the others. It is known that the sea otter's unusually thick fur helps, but Wright et al. show that they are also internally warmed by thermogenic leak from skeletal muscle, a process that elevates their metabolic rate three times above that expected for their size. This mechanism is present even in infants with immature muscles, providing these animals with internal warmth from birth. Science, abf4557, this issue p. 223 Thermogenesis is a primary regulator of sea otter muscle metabolism, allowing them to inhabit cold water. Basal metabolic rate generally scales with body mass in mammals, and variation from predicted levels indicates adaptive metabolic remodeling. As a thermogenic adaptation for living in cool water, sea otters have a basal metabolic rate approximately three times that of the predicted rate; however, the tissue-level source of this hypermetabolism is unknown. Because skeletal muscle is a major determinant of whole-body metabolism, we characterized respiratory capacity and thermogenic leak in sea otter muscle. Compared with that of previously sampled mammals, thermogenic muscle leak capacity was elevated and could account for sea otter hypermetabolism. Muscle respiratory capacity was modestly elevated and reached adult levels in neonates. Premature metabolic development and high leak rate indicate that sea otter muscle metabolism is regulated by thermogenic demand and is the source of basal hypermetabolism.
Temporomandibular joint and Giant Panda’s (Ailuropoda melanoleuca) adaptation to bamboo diet
Venue: Scientific Reports

Here, we present new evidence that evolutionary adaptation of the Ailuripodinae lineage to bamboo diet has taken place by morphological adaptations in the masticatory system. The giant panda in the wild and in captivity removes without an exception the outer skin of all bamboo shoots, rich in abrasive and toxic compounds, by the highly adapted premolars P3 and P4. The temporomandibular joint (TMJ) allows sidewise movement of the jaw and the premolars can, in a cusp-to-cusp position, remove the poorly digestible outer skin of the bamboo before crushing the bamboo with molars. Based on the evidence presented here, we suggest that adaptation of TMJ to lateral movement for enabling cusp-to-cusp contact of premolars is the crucial evolutionary factor as which we consider the key to understand the Ailuropodinae lineage adaptive pathway to utilize the bamboo resource.
Dragonfly wing nodus: A one-way hinge contributing to the asymmetric wing deformation.
Venue: Acta Biomaterialia

Dragonfly wings are highly specialized locomotor systems, which are formed by a combination of several structural components. The wing components, also known as structural elements, are responsible for the various aspects of the wing functionality. Considering the complex interactions between the wing components, modelling of the wings as a whole is only possible with inevitable huge oversimplifications. In order to overcome this difficulty, we have recently proposed a new approach to model individual components of complex wings comparatively. Here, we use this approach to study nodus, a structural element of dragonfly wings which has been less studied to date. Using a combination of several imaging techniques including scanning electron microscopy (SEM), wide-field fluorescence microscopy (WFM), confocal laser scanning microscopy (CLSM) and micro-computed tomography (micro-CT) scanning, we aim to characterize the spatial morphology and material composition of fore- and hindwing nodi of the dragonfly Brachythemis contaminata. The microscopy results show the presence of resilin in the nodi, which is expected to help the deformability of the wings. The computational results based on three-dimensional (3D) structural data suggest that the specific geometry of the nodus restrains its displacements when subjected to pressure on the ventral side. This effect, resulting from an interlocking mechanism, is expected to contribute to the dorso-ventral asymmetry of wing deformation and to provide a higher resistance to aerodynamic forces during the downstroke. Our results provide an important step towards better understanding of the structure-property-function relationship in dragonfly wings.



In this study, we investigate the wing nodus, a specialized wing component in dragonflies. Using a combination of modern imaging techniques, we demonstrate the presence of resilin in the nodus, which is expected to facilitate the wing deformability in flight. The specific geometry of the nodus, however, seems to restrain its displacements when subjected to pressure on the ventral side. This effect, resulting from an interlocking mechanism, is suggested to contribute to dorso-ventral asymmetry of wing deformations and to provide a higher resistance to aerodynamic forces during the downstroke. Our results provide an important step towards better understanding of the structure-property-function relationship in dragonfly wings and might help to design more efficient wings for biomimetic micro-air vehicles.
Hierarchical architecture of spider attachment setae reconstructed from scanning nanofocus X-ray diffraction data
Venue: Journal of the Royal Society Interface

When sitting and walking, the feet of wandering spiders reversibly attach to many surfaces without the use of gluey secretions. Responsible for the spiders' dry adhesion are the hairy attachment pads that are built of specially shaped cuticular hairs (setae) equipped with approximately 1 µm wide and 20 nm thick plate-like contact elements (spatulae) facing the substrate. Using synchrotron-based scanning nanofocus X-ray diffraction methods, combining wide-angle X-ray diffraction/scattering and small-angle X-ray scattering, allowed substantial quantitative information to be gained about the structure and materials of these fibrous adhesive structures with 200 nm resolution. The fibre diffraction patterns showed the crystalline chitin chains oriented along the long axis of the attachment setae and increased intensity of the chitin signal dorsally within the seta shaft. The small-angle scattering signals clearly indicated an angular shift by approximately 80° of the microtrich structures that branch off the bulk hair shaft and end as the adhesive contact elements in the tip region of the seta. The results reveal the specific structural arrangement and distribution of the chitin fibres within the attachment hair's cuticle preventing material failure by tensile reinforcement and proper distribution of stresses that arise upon attachment and detachment.
Soft and ion-conducting hydrogel artificial tongue for astringency perception
Venue: Science Advances

Artificial tongue for astringency perception is demonstrated with a saliva-like chemiresistive ionic hydrogel. Artificial tongues have been receiving increasing attention for the perception of five basic tastes. However, it is still challenging to fully mimic human tongue–like performance for tastes such as astringency. Mimicking the mechanism of astringency perception on the human tongue, we use a saliva-like chemiresistive ionic hydrogel anchored to a flexible substrate as a soft artificial tongue. When exposed to astringent compounds, hydrophobic aggregates form inside the microporous network and transform it into a micro/nanoporous structure with enhanced ionic conductivity. This unique human tongue–like performance enables tannic acid to be detected over a wide range (0.0005 to 1 wt %) with high sensitivity (0.292 wt %−1) and fast response time (~10 s). As a proof of concept, our sensor can detect the degree of astringency in beverages and fruits using a simple wipe-and-detection method, making a powerful platform for future applications involving humanoid robots and taste monitoring devices.
A Dual-Mechanism Antibiotic Kills Gram-Negative Bacteria and Avoids Drug Resistance
Venue: Cell

The rise of antibiotic resistance and declining discovery of new antibiotics has created a global health crisis. Of particular concern, no new antibiotic classes have been approved for treating Gram-negative pathogens in decades. Here, we characterize a compound, SCH-79797, that kills both Gram-negative and Gram-positive bacteria through a unique dual-targeting mechanism of action (MoA) with undetectably low resistance frequencies. To characterize its MoA, we combined quantitative imaging, proteomic, genetic, metabolomic, and cell-based assays. This pipeline demonstrates that SCH-79797 has two independent cellular targets, folate metabolism and bacterial membrane integrity, and outperforms combination treatments in killing methicillin-resistant Staphylococcus aureus (MRSA) persisters. Building on the molecular core of SCH-79797, we developed a derivative, Irresistin-16, with increased potency and showed its efficacy against Neisseria gonorrhoeae in a mouse vaginal infection model. This promising antibiotic lead suggests that combining multiple MoAs onto a single chemical scaffold may be an underappreciated approach to targeting challenging bacterial pathogens.
Bumble bees damage plant leaves and accelerate flower production when pollen is scarce
Venue: Science

Bumble bee gardeners Bumble bees rely heavily on pollen resources for essential nutrients as they build their summer colonies. Therefore, we might expect that annual differences in the availability of these resources must simply be tolerated, but Pashalidou et al. made observations suggesting that bees may have strategies to cope with irregular seasonal flowering (see the Perspective by Chittka). When faced with a shortage of pollen, bumble bees actively damaged plant leaves in a characteristic way, and this behavior resulted in earlier flowering by as much as 30 days. Experimenters were not able to fully replicate the results with their own damage, suggesting that there is a distinct method that the bees use to stimulate earlier flowering. Science, this issue p. 881; see also p. 824 Bumble bees manipulate plants to bring about earlier flowering. Maintaining phenological synchrony with flowers is a key ecological challenge for pollinators that may be exacerbated by ongoing environmental change. Here, we show that bumble bee workers facing pollen scarcity damage leaves of flowerless plants and thereby accelerate flower production. Laboratory studies revealed that leaf-damaging behavior is strongly influenced by pollen availability and that bee-damaged plants flower significantly earlier than undamaged or mechanically damaged controls. Subsequent outdoor experiments showed that the intensity of damage inflicted varies with local flower availability; furthermore, workers from wild colonies of two additional bumble bee species were also observed to damage plant leaves. These findings elucidate a feature of bumble bee worker behavior that can influence the local availability of floral resources.
Electric Fields Elicit Ballooning in Spiders
Venue: Current Biology

When one thinks of airborne organisms, spiders do not usually come to mind. However, these wingless arthropods have been found 4 km up in the sky , dispersing hundreds of kilometers . To disperse, spiders “balloon,” whereby they climb to the top of a prominence, let out silk, and float away. The prevailing view is that drag forces from light wind allow spiders to become airborne , yet ballooning mechanisms are not fully explained by current aerodynamic models [4, 5]. The global atmospheric electric circuit and the resulting atmospheric potential gradient (APG)  provide an additional force that has been proposed to explain ballooning [7]. Here, we test the hypothesis that electric fields (e-fields) commensurate with the APG can be detected by spiders and are sufficient to stimulate ballooning. We find that the presence of a vertical e-field elicits ballooning behavior and takeoff in spiders. We also investigate the mechanical response of putative sensory receivers in response to both e-field and air-flow stimuli, showing that spider mechanosensory hairs are mechanically activated by weak e-fields. Altogether, the evidence gathered reveals an electric driving force that is sufficient for ballooning. These results also suggest that the APG, as additional meteorological information, can reveal the auspicious time to engage in ballooning. We propose that atmospheric electricity adds key information to our understanding and predictive capability of the ecologically important mass migration patterns of arthropod fauna [8].
Encoding Membrane-Potential-Based Memory within a Microbial Community.
Venue: Cell systems

Cellular membrane potential plays a key role in the formation and retrieval of memories in the metazoan brain, but it remains unclear whether such memory can also be encoded in simpler organisms like bacteria. Here, we show that single-cell-level memory patterns can be imprinted in bacterial biofilms by light-induced changes in the membrane potential. We demonstrate that transient optical perturbations generate a persistent and robust potassium-channel-mediated change in the membrane potential of bacteria within the biofilm. The light-exposed cells respond in an anti-phase manner, relative to unexposed cells, to both natural and induced oscillations in extracellular ion concentrations. This anti-phase response, which persists for hours following the transient optical stimulus, enables a direct single-cell resolution visualization of spatial memory patterns within the biofilm. The ability to encode robust and persistent membrane-potential-based memory patterns could enable computations within prokaryotic communities and suggests a parallel between neurons and bacteria.
Kinship influences social bonds among male southern Australian bottlenose dolphins (Tursiops cf. australis)
Venue: Behavioral Ecology and Sociobiology

Male mammals employ a wide variety of mating strategies in order to increase their reproductive success, which in turn influence their social behavior. In some populations of bottlenose dolphins (Tursiops spp.), males cooperate in small groups or alliances to gain access to females for mating. However, the occurrence of these male cooperative groups has been predicted to occur only under certain social and ecological conditions, driven by factors such as differences in population density, operational sex ratio, and sexual size dimorphism. Here, we used generalized affiliation indices, social network techniques, and maternally and bi-parentally inherited genetic markers to investigate the affiliation patterns and genetic relatedness among male southern Australian bottlenose dolphins (Tursiops cf. australis) in a small embayment in South Australia. Photo-identification data and biopsy samples were collected in Coffin Bay from 2013 to 2015 through systematic boat-based surveys. We found that highly sighted male dolphins formed 12 social clusters composed of two to five individuals. Genetic analyses revealed that general male affiliation patterns were significantly correlated with mtDNA haplotype sharing. In addition, preferred affiliates showed significantly higher levels of genetic relatedness compared to casual and avoided male pairs. Our results corroborate theoretical expectations for the formation of social bonds in small delphinids and suggest that a high density of dolphins, with an expected skewed operational sex ratio and no apparent sexual size dimorphism, is likely to have favored the formation of strong male affiliations. In addition, the availability of genetic relatives within the population may have favored male affiliations based on kinship relationships.Significance statementMale bottlenose dolphins use different strategies to gain access to females, from single roving individuals, pairs or trios in alliances, to stable mixed-sex groups. Moreover, the role of kinship in the formation of male social bonds also varies within and among populations. This variability has been attributed to differences in ecological and intrinsic factors. Here, we studied the affiliation patterns and genetic relatedness in southern Australian bottlenose dolphins and demonstrated that kinship plays an important role in the formation of close male social ties. Furthermore, the results corroborate previous findings about the factors that contribute to the formation of male social bonds in these animals.
Versatility of Turing patterns potentiates rapid evolution in tarsal attachment microstructures of stick and leaf insects (Phasmatodea)
Venue: Journal of the Royal Society Interface

In its evolution, the diverse group of stick and leaf insects (Phasmatodea) has undergone a rapid radiation. These insects evolved specialized structures to adhere to different surfaces typical for their specific ecological environments. The cuticle of their tarsal attachment pads (euplantulae) is known to possess a high diversity of attachment microstructures (AMS) which are suggested to reflect ecological specializations of different groups within phasmids. However, the origin of these microstructures and their developmental background remain largely unknown. Here, based on the detailed scanning electron microscopy study of pad surfaces, we present a theoretical approach to mathematically model an outstanding diversity of phasmid AMS using the reaction–diffusion model by Alan Turing. In general, this model explains pattern formation in nature. For the first time, we were able to identify eight principal patterns and simulate the transitions among these. In addition, intermediate transitional patterns were predicted by the model. The ease of transformation suggests a high adaptability of the microstructures that might explain the rapid evolution of pad characters. We additionally discuss the functional morphology of the different microstructures and their assumed advantages in the context of the ecological background of species.
Attachment-based mechanisms underlying capture and release of pollen grains
Venue: Journal of the Royal Society Interface

Successful insect pollination can be achieved by a sequence of numerous attachment and detachment events at various biological surfaces. However, the quantitative measurements of pollen adhesion on biological surfaces have been poorly studied so far. We performed atomic force microscopy adhesion measurements of pollen on two most important floral parts for Asteraceae in a course of pollination: the stigma and style of Hypochaeris radicata plant. The results indicated distinct adhesive properties of them—the pollen adhesion on stigmatic surfaces drastically increased over prolonged contact time, while the pollen adhesion increase on stylar surfaces was rather restrained. Based on the observation with cryo-scanning electron microscopy, we explained the experimental results by the presence of morphological features in form of flexible stigmatic papillae that may play a crucial role in enhancing both capillary attraction and van der Waals forces. The distinct adhesive properties seemingly originate from the unique adhesive tasks that each of the floral parts requires to achieve successful pollination. The insights into the adhesive interaction between pollen and the floral parts, obtained in the present study, may lead to better understanding of pollination mechanisms, which are strongly related to our food production. Additionally, the novel pollen adhesive mechanisms learned from the stigma of the studied Asteraceae plant can inspire biomimetic designs of spontaneous gripping systems.
Pygidial glands of Harpalus pensylvanicus (Coleoptera: Carabidae) contain resilin-rich structures.
Venue: Arthropod Structure & Development

The pygidial gland system is a key innovation in adephagan beetles, producing, storing, and spraying defensive chemical compounds. As the source of defensive chemical production and storage, the pygidial gland system experiences severe chemical stress which challenges the integrity of the entire gland system. Here, we utilize autofluorescence-based confocal laser scanning microscopy to examine the morphology of pygidial gland secretory lobes and collecting ductules in a common Pennsylvanian harpaline species, Harpalus pensylvanicus. The glandular units are composed of type-III exocrine cells which empty into resilin-rich ductules, which themselves lead into a larger resilin-rich collecting duct, and ultimately the pygidial reservoir pump. We also utilize histological staining with toluidine blue and brightfield imaging to provide additional support for the presence of resilin in the collecting duct, as toluidine blue has been shown to stain resilin without metachromasia. We hypothesize that the high resilin content of the collecting ducts might be a widespread key evolutionary adaptation to prevent damage caused by physical and chemical stress generated in pump-containing insect exocrine gland systems.
A G protein–coupled receptor mediates neuropeptide-induced oocyte maturation in the jellyfish Clytia
Venue: PLoS biology

The reproductive hormones that trigger oocyte meiotic maturation and release from the ovary vary greatly between animal species. Identification of receptors for these maturation-inducing hormones (MIHs) and understanding how they initiate the largely conserved maturation process remain important challenges. In hydrozoan cnidarians including the jellyfish Clytia hemisphaerica, MIH comprises neuropeptides released from somatic cells of the gonad. We identified the receptor (MIHR) for these MIH neuropeptides in Clytia using cell culture–based “deorphanization” of candidate oocyte-expressed G protein–coupled receptors (GPCRs). MIHR mutant jellyfish generated using CRISPR-Cas9 editing had severe defects in gamete development or in spawning both in males and females. Female gonads, or oocytes isolated from MIHR mutants, failed to respond to synthetic MIH. Treatment with the cAMP analogue Br-cAMP to mimic cAMP rise at maturation onset rescued meiotic maturation and spawning. Injection of inhibitory antibodies to the alpha subunit of the Gs heterodimeric protein (GαS) into wild-type oocytes phenocopied the MIHR mutants. These results provide the molecular links between MIH stimulation and meiotic maturation initiation in hydrozoan oocytes. Molecular phylogeny grouped Clytia MIHR with a subset of bilaterian neuropeptide receptors, including neuropeptide Y, gonadotropin inhibitory hormone (GnIH), pyroglutamylated RFamide, and luqin, all upstream regulators of sexual reproduction. This identification and functional characterization of a cnidarian peptide GPCR advances our understanding of oocyte maturation initiation and sheds light on the evolution of neuropeptide-hormone systems.