Czechia


In recent years, research on spider silk has surged, focusing on its mechanical, medicinal, and commercial applications. Despite this, our understanding of the behavioral utilization of distinct silk types and their functions remains limited. Moreover, there is a notable gap in methodologies to comprehend the use of spider silk glands. This study focuses on Pholcus phalangioides, commonly known as Daddy long-legs spiders, known to build three dimensional irregular webs with unique behaviours. These include using sticky prey wraps to capture airborne prey, and viscous-sticky traps to ensnare ground-dwelling prey and dragline and bridging lines for locomotion. We employed multiple methodologies on live individuals as well as silk fibres collected for in-depth understanding of silk glands uses for these behaviours. Methods included spigot morphology analysis, gland dissections for morphology, light microscopy for identifying silk fibre types, high-speed video recording for behavioral study, shock freezing to observe spider behavior under Scanning Electron Microscopy and mechanical tests for single fibres to understand their role in ecological uses. Results suggest that a multi-methodology approach offers a comprehensive understanding of silk gland behavioral use. This study provides a unique perspective beyond the prevalent focus on orb weavers, offering insights into lesser-known species. The study highlights the limitations of single techniques, emphasizing the need for a diverse methodology. Additionally, it presents a protocol applicable to studying any spider&#39;s behavioral use of silk glands.


SEB Conference 2024

A multimethod approach to study the behavioral utilization of spider silk glands.

silk glands

spider silk

behaviour

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In recent years, research on spider silk has surged, focusing on its mechanical, medicinal, and commercial applications. Despite this, our understanding of the behavioral utilization of distinct silk types and their functions remains limited. Moreover, there is a notable gap in methodologies to comprehend the use of spider silk glands. This study focuses on Pholcus phalangioides, commonly known as Daddy long-legs spiders, known to build three dimensional irregular webs with unique behaviours. These include using sticky prey wraps to capture airborne prey, and viscous-sticky traps to ensnare ground-dwelling prey and dragline and bridging lines for locomotion. We employed multiple methodologies on live individuals as well as silk fibres collected for in-depth understanding of silk glands uses for these behaviours. Methods included spigot morphology analysis, gland dissections for morphology, light microscopy for identifying silk fibre types, high-speed video recording for behavioral study, shock freezing to observe spider behavior under Scanning Electron Microscopy and mechanical tests for single fibres to understand their role in ecological uses. Results suggest that a multi-methodology approach offers a comprehensive understanding of silk gland behavioral use. This study provides a unique perspective beyond the prevalent focus on orb weavers, offering insights into lesser-known species. The study highlights the limitations of single techniques, emphasizing the need for a diverse methodology. Additionally, it presents a protocol applicable to studying any spider's behavioral use of silk glands.


technical paper

Adequate oxygen delivery to tissue is important for maintaining cellular homeostasis. Thus, an animal’s ability to detect low oxygen is crucial for survival. In fish, oxygen sensing occurs in the gills via chemoreceptive neuroepithelial cells (NECs). Despite the many similarities between NECs and mammalian chemoreceptors, the receptors and neurochemistry involved in gill hypoxia signalling have not been well defined. The goals of the present study were to delineate a mechanism by which presynaptic dopamine D2 receptors modulate the chemoreceptor response to hypoxia, and to begin exploring receptors involved in the excitatory transmission of hypoxia within the zebrafish gill. Using an isolated gill preparation from Tg(elavl3:GCaMP6s) zebrafish, we found NECs respond to hypoxia by an increase in [Ca2+]i and activation of presynaptic dopamine D2 receptors with the selective agonist, quinpirole, decreased the calcium response to hypoxia. Presynaptic modulation via D2 receptors led to a decrease in the activity of postsynaptic neurons that innervated NECs during hypoxia. Further evaluating the postsynaptic responses to hypoxia, we demonstrated activation of these neurons with acetylcholine, and the neuronal response to hypoxia was reduced by addition of hexamethonium, a nicotinic acetylcholine receptor antagonist. Our results provide the first direct evidence of neuromodulation of the hypoxic signal produced by NECs in the gill by dopamine, suggesting that a modulatory role for dopamine in oxygen sensing arose early in vertebrate evolution. Further, we suggest a role for acetylcholine in the transmission of the hypoxic response, further highlighting the similarity between NECs and mammalian chemoreceptors.

Chemoreceptor inhibition by dopamine D2 receptors and post synaptic responses to ACh in isolated zebrafish gills.

Allometry describes how the characteristics of living organisms change with body size. Although a decline in fish size is acknowledged as one of the widespread responses to global warming, relatively few studies have investigated the allometry of thermal limits, and even fewer have attempted to quantify the cardiorespiratory responses that may underlie any size-dependent thermal tolerance.

We measured the allometry of arterial and venous oxygen tension (PaO2 and PvO2) of 65 rainbow trout ranging from 200 to 3800 g across stepwise, acute temperature increases (18, 21.5, and 25°C) and under both normoxia and hyperoxia (150% O2). Additionally, we measured the aerobic metabolic rates of 130 rainbow trout ranging from 10 to 350 g under similar temperature and oxygen regimes.

While PaO2 did not scale with body mass throughout the temperature ramp, oxygen supplementation via hyperoxia lifted overall arterial oxygen tension. Aligning with previous work on salmonids, PvO2 declined with increasing fish size in normoxia, suggesting the potential for cardiac impairments in large individuals. While the mass-dependent decline in PvO2 was attenuated in hyperoxia, thermal limitations were observed without clear correlation to oxygen supply capacity. These findings have implications for the global discussion around climate warming and fish oxygen limitations and highlight the need for a better empirical understanding of size-dependent thermal tolerance.

The allometry of vascular oxygen supply during an acute thermal challenge in rainbow trout

How would you describe the shape of the isometric force-length-activity relation (FLAR) of striated muscle sarcomeres to your students? Simple textbook knowledge, right? At very long lengths, the sarcomere (and thus the whole fiber) is unable to exert any active force even when fully activated. When the sarcomere is gradually held at shorter lengths, the force increases somewhat linearly.
For a certain 'optimal' length -- or 'plateau' region -- the force output reaches its maximum, before it decreases again for even shorter lengths.

When it comes to explaining this shape, the long-length characteristic (the descending branch) is commonly associated with the relative overlap between thin and thick filaments. However, explanations for the force decrease at shorter lengths (the ascending branch) are rather vague. In the literature, there exist several attempts of explaining a piece-wise linear ascending branch by assuming
(i) repelling forces between opposing thin filaments, (ii) thick filament compression at the Z-disk, or (iii) steric hindrance of cross-bridge building. This talk addresses these hypotheses by revealing sources, misconceptions, and counterevidence.
Further, a biophysical model is presented, exploiting know mechanisms such as the volume constancy of the filament lattice, electrostatics-induced cross-bridge building, and Hill's equation of ligand-receptor complexes. A combination of these mechanisms fully explains the experimentally observed FLAR and even pertains to submaximally Calcium-activated fibers -- a realm where conventional approaches struggle.

Biophysical mechanisms underlying the force-length-activity relation of the sarcomere

The force produced by activated skeletal muscle increases considerably (i.e., about 1.5 – 2 times) upon stretching its half sarcomeres a small amount (i.e., about 10 nanometers), and plateaus upon further stretching. Similar force transients can be observed across a broad range of stretch velocities, and across a broad range of species. The initial rise in force is known as short-range-stiffness and is believed to help stabilize animal movements by reducing the need for neural control. Short-range-stiffness is difficult to assess during movements but could be predicted using computer simulations with musculoskeletal models. However, current simulations rely on phenomenological Hill-type muscle models, which cannot explain history-dependent changes in short-range-stiffness with prior shortening, that may occur during movements. In contrast, simple biophysical muscle models have history dependence, but cannot reproduce force transients during stretch. This may be because such simple models typically only have one bound and one unbound crossbridge state, while experimental data suggest that crossbridges have at least two bound states (e.g., weakly or strongly) and two unbound states (e.g., detached or forcibly detached). Complex biophysical models including such states have previously been shown to fit force transients better, but at a high computational cost. To facilitate implementing such models in musculoskeletal simulations, we therefore applied a moment approximation to their crossbridge distributions and greatly reduced their computational cost. These models reproduced both force transients and typical steady-state force-velocity relations for various muscles. Ultimately, we will implement biophysical muscle models in musculoskeletal simulations to elucidate how muscle properties shape movement biomechanics.

A simple biophysical muscle model explains force transients during lengthening

Most species experience some amount of temperature variation at daily and seasonal timescales. Variations in temperature are expected to shape key biological traits of ectotherms, but also the breadth of phenotypes expressed within a population. Here, we combine meta-analytical and experimental data to uncover how daily temperature variation impacts phenotypic means and variation of ectothermic animals. We hypothesised that variation around warm temperatures would decrease growth, locomotion and reproductive success but increase phenotypic variation in these traits. We tested this hypothesis by first assembling the most comprehensive database to date, spanning 165 ectothermic species, and performing meta-analyses. Second, using black bream (Acanthopagrus butcheri) as an experimental model, we assessed the upper thermal limits of fish following acclimation to constant or variable daily temperatures, and compared these data to the thermal limits of field-acclimated fish. Our meta-analysis revealed that daily temperature variation increases upper thermal limits across ectotherms, but reproductive traits were compromised. Surprisingly, phenotypic variation did not increase in response to daily temperature variations. Experimental data showed that upper thermal limits of field-acclimated fish does not mirror that of fish acclimated to a constant temperature under lab conditions. Taken together, these findings demonstrate the importance of considering how daily temperature variation impacts key biological traits. Experiments that expose ectotherms to constant temperatures can over-simplify physiological responses to temperature variation that could misguide conservation and management actions.

Temperature variation can be a blessing and a curse for ectothermic animals

Ectotherms can regulate their body temperature by moving between cooler and warmer environments. The choice of a thermal environment can be driven by different parameters, including an individual’s health status. For instance, disease and parasite infection can cause some species of fish to increase their body temperature by spending more time in warmer waters, presumably to maximise their immune defences and, thus, the chance to fight off the infection, a phenomenon known as behavioural fever. Most studies on fish thermoregulation do not consider how the immune response to disease and/or parasite infection can shape a fish’s thermal choice. Yet, the severity of the parasite infection (load), the presence of multiple parasite species (co-infection) and the timing of the infection (acute vs. chronic) can change temperature preference. Here, we measured the preferred temperature of wild-caught pumpkinseed sunfish using a shuttle-box system. Fish were separated into three groups: 1) chronically co-infected by parasite, 2) acutely exposed to parasite, and 3) immune-stimulated via injection of lipopolysaccharide (LPS) endotoxin. We observed that the fish’s preferred temperature did not vary with parasite infection,co-infection and immune-stimulation. This suggests that fish did not display behavioural fever. This combination of groups with different infection status allowed us to tease apart the role of the immune system in thermal choice and deepen our understanding of animal movement. Ultimately, this helps our comprehension of how ectotherms fight disease in nature.

Temperature preference in immune-stimulated and parasite-infected sunfish

In the recently introduced integrated foundation year for Nottingham Trent University’s undergraduate bioscience courses, students study a range of practical and transferrable skills which are assessed through a professional practice and skills module. The team lab research project is designed to foster the development of a range of professional and work-relevant skills such as problem-solving, use of professional communication platforms for team communication and document sharing, as well as awareness of health and safety and time management. Module assessment focusses on a team presentations of the project and evidence of laboratory and transferrable skills through a skills portfolio.
The project, designed to introduce the students to the scientific method for investigating research questions in the laboratory, was contextualised to a real-world scenario through collaboration with an external industrial partner. In this case, the project was designed for students to design and deliver a lab-based project to explore bacterial resistance to antibiotics and the claims of natural products to have anti-microbial properties. The external partner, a biomedical scientist within the UK National Health Service specialising in microbiology, set the context of the project through reference to the importance of identification of antibiotic resistance within the NHS. Not only this but they were able to give students one-to-one guidance in the laboratory to support the development of their practical skills, and feedback on their team presentation of the project.
Students will reflect on their experience of the benefits and challenges of working on the team project as part of the presentation. 


Developing professional skills and attributes in foundation biology students

At Nottingham Trent University (NU) we have established a Biosciences Employer Advisory Group who inform our curriculum and assessment practice thereby ensuring our graduates are work ready and possess the skills the industries require now and in future. 

Our employers are directly involved in delivering session to our students, interacting with our students and feed back on their skillset and competencies. Employers are involved in showcasing their work processes, industry expectations, professional expectations across a range of skillsets such as competency testing and sign off, interview techniques and job applications, Biochemistry assays and applications and the use of genetic testing to name just a view. 

This has involved adapting module delivery, teaching activities and new assessments to mimic work activities and re-create work scenarios. During the process students develop critical thinking, problem-solving, and communication skills relevant to their future careers. 

The implementation is not without challenges including sustainability resource limitations, academic team buy-in, and logistical constraints. Addressing these challenges requires ongoing evaluation and adaptation of our initiative, alongside institutional support. 

The recreated employment experiences in bioscience education offers numerous benefits for students, educators, and employers alike. By aligning assessments with real-world work activities, fostering industry partnerships, and promoting student engagement, students on full time modes of study are prepared for successful careers in the bioscience field.

Ensuring work readiness of BSc (Honours) Biochemistry graduates at NTU through employer led assessment practice

This talk will cover the emerging field of Scholarship of Teaching and Learning (SoTL). The session begins by introducing SoTL models and definitions, and the integration of practice and theory. It will then explore some practical strategies to develop a scholarly approach to teaching and outreach. 

This session is relevant to anyone who is on a teaching and scholarship career track, or is interested in developing their expertise in Scholarship of Teaching and Learning, and links to teaching in higher education.

An Introduction to Scholarship of Teaching and Learning for Bioscientists

Ensuring food security for an ever-growing global population while adapting to climate change is the main challenge for agriculture in the 21st century. The gene discovery pipeline BREEDIT, combines multiplex genome editing with crossing schemes to improve complex traits such as yield and drought tolerance. During the presentation, I will explain different use cases of the BREEDIT technology, while I will also highlight how it brings together genomics, transcriptomics, phenotyping and machine learning.

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