Integrative and Comparative Biology最新文献

Emerging diseases threaten wildlife worldwide and understanding immune function in the context of the ecology of an organism is critical in predicting disease outcomes. The immune response in reptiles is especially understudied, leaving major gaps in the ability to address disease threats. Freshwater turtles are especially imperiled due to a swath of anthropogenic impacts, including bacterial, viral, and fungal diseases. Because multiple novel pathogen types threaten turtles, understanding nuances in their immune responses may help predict how populations may respond to challenges and shape conservation decisions. We aimed to characterize immune responses following exposure to 3 commercially available antigens representing bacterial, viral, and fungal pathogens in adult red-eared slider turtles (Trachemys scripta elegans) housed in natural conditions. We collected blood samples from red-eared sliders at 0, 12, 24, 48, and 72 h following an antigen treatment (lipopolysaccharide; LPS, polyinosinic-polycytidylic acid; poly(I:C), zymosan, or saline). We created blood smears at 0 and 72 h and the collected serum and buffy layer (serum + BL) were subjected to 3 manipulations (fresh, frozen, frozen + heat) for use in microbial killing assays against Escherichia coli, Candida albicans, and Staphylococcus aureus. The combination of antigen treatments on the turtles and manipulations to the collected blood allowed us to examine different immune responses and components. We also quantified corticosterone using enzyme-linked immunosorbent assays to understand energy mobilization following antigen treatment. Microbial killing was generally stable against microbes, regardless of antigen exposure and serum manipulations reveal differences in relative leukocyte and protein-based contribution to killing microbe classes. Overall, the low killing of Gram-positive S. aureus relative to E. coli and C. albicans further suggests that red-eared sliders rely on a robust complement response. Though we did not observe substantial differences among treatments, our results suggest that LPS elicited an increased complement response. The other antigens did not consistently stimulate stronger responses, but more work is needed to understand dose-dependent responses to poly(I:C) and zymosan and in turtles and other reptiles. Overall, our research demonstrates that microbial killing assays can be enhanced through deliberate serum + BL manipulation and microbe usage as ecoimmunological tools to gain a more robust understanding of the immune response in wild organisms.

The tongues of pangolins are among the more derived of other mammalian ant-eating specialists, extending nearly a body length to capture food. Pangolins pack portions of their hyolingual apparatus in their thoracoabdominal cavity. These muscles are responsible for protruding, retracting, and bracing the tongue through a large range of motion akin to that of muscular hydrostats. Using DiceCT and 3D muscle architectural modeling of a cadaveric Phataginus tricuspis (White-bellied pangolin), we show how the arrangement of muscle fascicles in a section of the thoracoabdominal portion of the tongue converges on the structure of a hydrostat. Rostrally, the body of the tongue is occupied by m. sternoglossus, paired, parallel-fibered muscle bellies that run the longitudinal distance of the first 2/3 of the tongue. Upon entering the abdominal cavity, the body tethers to coiled, elongate xyphoid bones via m. xiphisternalis. Xiphisternal muscle fibers envelop the caudal portion of m. sternoglossus and anchor to the distal portions of the xiphoid bones and aid in retracting the tongue. The coiled nature of the xiphisternal bones and attachments of tongue muscles suggests an elastic mechanism may help propel tongue extension. The body of the tongue resides in a glossal tube, an extension of geniohyoid muscles built by layers of circular and longitudinal fibers that modestly, helically wind around the long axis of the tongue, also aiding in tongue protraction. Together, these muscles act as a hydrostat in promoting hyolingual movements in pangolins.

Seventy percent of mammals copulate using repeated pelvic thrusting, while the transfer of sperm requires just a single intromission. Why did thrusting evolve to be the dominant form of sexual intercourse? In this study, we investigate how the rate of sexual pelvic thrusting changes with body size. By analyzing films of copulating mammals, from mice Mus musculus to elephants Elephantidae, we find that bigger animals thrust slower. The rate of pelvic thrusting decreases from 6 Hz for the pocket mouse Pergonathus to 1.3-1.8 Hz for humans to an absence of thrusting for the rhino Rhinocerotidae and elephant Elephantidae families. To understand this dependence on body size, we consider the spring-like behavior of the legs, which is associated with the elasticity of the body's muscles, tendons, and ligaments. For both running and thrusting, greater displacment and energy savings can be achieved if the system is oscillated at its resonant or natural frequency. Resonant frequencies, as measured through previous studies of running in dogs Canis familiaris and horses Equus ferus caballus, show good agreement with sexual thrusting frequencies. Running and sexual thrusting have nothing in common from a behavioral perspective, but from a physical perspective, they are both constrained by the same musculoskeletal systems, and both take advantage of resonance. Our findings may provide improved treatments for human sexual dysfunction as well as improving breeding strategies for domestic mammals.

Hydrostatic skeletons enable the transmission of mechanical work through a soft body. Despite the ubiquity of these structures among animals, we have a relatively rudimentary understanding of how they operate mechanically. Here we consider a mathematical model of the mechanics of a relatively tractable hydrostatic skeleton, the tube feet of sea stars. Tube feet drive locomotion by generating a pushing force against the environment. This pushing force is created by the transmission of pressure from one chamber, the ampulla, to another, the stem, which extends from the oral surface of the body. This system operates as a compound machine with a mechanical advantage (MA, the ratio of output to input force) that varies with the geometry of its two chambers. We present an analytical approach for parameterizing the model from morphometric measurements and formulating predictions for representative morphologies. Our analysis predicts that MA initially increases as the stem extends, but collapses to zero near maximum extension. The decrease in force output occurs because the angle of cross-helical fiber winding in the stem approaches the critical point of 54.7°, an angle at which the force components exactly balance the hoop and longitudinal forces from pressure. Though producing no axial force at full extension, a bent tube foot can still generate perpendicular forces that generate torque to lift and propel the body, a proposition that is supported by kinematic observations of the tube feet. These results provide a framework for understanding tube foot mechanics across echinoderms and highlight the functional significance of helical-fiber arrangements in hydrostatic skeletons.

The pandemic-driven shift to online learning necessitated a re-evaluation of traditional exams, revealing their limitations in fostering essential scientific skills and potentially disadvantaging some students. This paper presents sketchnoting, a visual note-taking method, as an authentic alternative assessment. By integrating scientific concepts, peer review, and graphical literacy, this approach aimed to cultivate skills like critical thinking and communication while assessing content. Student feedback indicated enhanced learning, skill development, and preference for sketchnotes over exams, despite similar workload. Notably, this flexible assessment correlated with reduced performance disparities. This study advocates for reimagining assessment to prioritize skill development, promote equity, and improve learning outcomes, emphasizing the value of pedagogical collaboration in driving innovation.

Climate change threatens organismal health and ecological stability in myriad ways, the impacts of which are often difficult to characterize given their complex and interacting nature. To facilitate comparisons across taxa and ecosystems, we discuss the importance of a cross-scale approach to better characterize the ways in which climate change processes threaten wildlife immunity. Centering available examples from the vertebrate wildlife literature, we supplement with examples from the livestock literature to illustrate ways in which abiotic stress impacts immunity from molecular to community scales of biological organization. To highlight opportunities for cross-scale integration, we present a series of vignettes-drought, temperature extremes, storms and flooding, and habitat alterations and shifts-prior to discussing the complexities inherent to studying multiple interacting threats using heavy metal contamination as an example. Finally, we outline mechanisms by which collaborations across disciplines and sectors can continue strengthening capacity for studying the drivers of climate change-associated threats to wildlife immunology.

Biological armors have evolved across taxa as structural adaptations that provide protection from external forces while balancing mobility, metabolic cost, and functional trade-offs. These systems, from arthropod exoskeletons to vertebrate osteoderms, illustrate how natural selection shapes materials and morphology to optimize defense without compromising essential movement and physiological processes. The evolution of armor is constrained by biomechanical limits, as seen in the structural rigidity of heavily plated organisms and the flexible composites that integrate protective and dynamic properties. Methods used to study these systems-CT scanning, histology, finite element analysis, and mechanical testing-directly influence how the biological principles of armor are defined and understood. These approaches reveal the material properties and functional constraints of armored structures that can be translated into engineered applications through bioinspiration. Bioinspired designs informed by natural armor have led to innovations in impact-resistant materials, flexible ceramics, and modular protective systems. By integrating biomechanics, materials science, and evolutionary biology, this manuscript examines how armor evolves, functions, and informs bioinspired design.

Proprioception can be seen as a somatic sense stimulated by the action of the body itself. It is perceived through proprioceptors and is tightly linked to the animal body, as it is influenced by the biomechanical properties of the structures in which it is embedded. A specific class of these receptors, the muscle proprioceptors, project at several levels of the nervous system and provide information about limb position, whether in the presence or absence of movement, as well as muscle length, the sense of effort, and the sense of balance. In skeletal systems, proprioception is involved in postural maintenance, reflex actions, and rhythmic behaviors, but also in higher functions such as action planning and prediction. Proprioception can also be found in structures that are capable of movement without any real skeleton and are therefore called hydrostatic skeletons, both in humans and other animals. Hydrostatic bodies, including cephalopod limbs, the elephant trunk, and the human tongue, use muscle contractile forces to generate hydrostatic pressure, which acts as a skeleton to stabilize the structure and create motion. To provide online motion control of these bodies, the animal nervous system must cope with a huge amount of information coming from variables (such as length, angle, stiffness, and orientation) that continuously change throughout the entire structure. To limit this central burden, these structures may benefit from the presence of a muscle proprioceptive system used locally to control muscle contraction. Based on the current knowledge, many of the basic components of the proprioceptive system of soft-bodied and skeletal animals are essentially the same. Here, we aim to provide a forward-looking perspective on the role of muscle proprioception in motion, with a special focus on proprioception in muscular hydrostats. We wish to highlight the relevance of this topic across several fields of investigation, from human sensorimotor pathologies to soft robotics, where a high degree of autonomy in soft structures, combined with a reduced control demand, remains an unmet need. To address these gaps, we emphasize the need for improved knowledge and methodological assessment of this "sixth sense."

Representation in science, science curricular development, and scientific outcomes is driven by our motivated thinking and reasoning. This in turn influences how we reason about issues related to equity, diversity, inclusion, and social justice. This paper unpacks perspectives about the influence of motivated thinking on representation and on perceptions of representation in the science curricula, more specifically Black representation in the qualitative and quantitative works of the first author. Motivated thinking influences many aspects of science and science education, including the research questions we choose, the scientists whom we choose to highlight in our classroom examples, the outcomes we desire from our research and teaching, and even the scope of our scientific disciplines. Molden and Higgins' breakdown of motivated thinking is used to frame observations about the influence of motivated thinking on the outcomes and processes of research, and to provide thought provoking questions and considerations given our current, future, and past social, cultural, political, historical, and scientific context and underpinnings. As a perspective piece, this paper toggles between the first-person narrations of the first author and the supporting research.

Plants are fundamental to life, providing oxygen, food, and climate regulation, while also offering solutions to global challenges. Integrating plant biology into an undergraduate curriculum, while supporting and nurturing students' career interests present both opportunities and challenges. Undergraduate biology education often overlooks plants due to limited student interest and a strong focus on health professions, particularly among women and underrepresented minorities. Here, we describe how plants are incorporated in the Biology curriculum at Spelman College, a women's liberal arts college and a Historically Black College and University where Biology is a popular major. The department has successfully embedded plant biology across its skills and competency-based curriculum, from the foundational introductory sequence to upper-level electives and research experiences. Students learn core biological concepts in the introductory core curriculum, consisting of four courses progressing from ecological to molecular levels, where plant-related content is integrated through inquiry driven, hands-on activities or field trips. In upper-level electives and research-based courses, faculty offer a robust program in plant biology that enables deeper understanding and integration across disciplines as they address real world problems that intersect with students' diverse interests. Survey data indicate that students perceive a balanced exposure to plants and other organisms in introductory courses and recognize the importance of plants for understanding core biological principles. Although this exposure does not significantly shift their primary career interest in medicine, it contributes to a broad biology education, skill development, and an increased interest in research.