Biology subjects

Tubbs, E.

Publications and source records attributed to Tubbs, E..

3 recordsLinked to original sources

bioRxiv2026

Lateral-eyed tree shrews combine panoramic vision with an expanded oculomotor repertoire

Mammals differ in how they redirect gaze. Primates shift and hold gaze with rapid, precise eye movements that can be decoupled from the head. In lateral-eyed mammals studied to date, gaze is organized around the head: saccades are coupled to head rotation in freely moving animals and typically accompanied by attempted head movements even under head fixation. These observations suggest a trade-off: animals that keep a panoramic field give up the precise, eye-driven control of gaze typical of frontal-eyed animals. But because lateral eyes and head-centered gaze co-occur in every lateral-eyed species studied, it is unknown whether one follows from the other. Here we test this in the tree shrew, an arboreal mammal with laterally placed eyes. Using real-time eye tracking in head-fixed animals, we find that tree shrews saccade frequently under head fixation and that most saccades occur without detectable attempted head movement. Tree shrews make visually evoked saccades, along both the horizontal and vertical axes of the visual field, toward targets. They can also fixate on visual targets. Using widefield calcium imaging, we show that visual cortex over-represents the central visual field. Lastly, we show that extraocular muscles contain morphologically elaborate palisade endings, specialized nerve endings that are a constant feature of frontal-eyed species. Lateral eyes therefore do not preclude eye-driven gaze control. The two are separable dimensions of visual system design, a combination that may suit animals whose locomotion routinely points the head away from where they need to look.

neuroscience↗

bioRxiv2024

Fusion of blood vessel organoids with human pancreatic islets improves insulin response over time.

Pancreatic islet transplantation is a promising treatment strategy for type 1 diabetes, however there are still major challenges to overcome, including vascularization. Novel strategies for the generation of prevascularized islets with native microvessels have reported improved islet functionality, vascularization and engraftment emphasizing integral role of microvascular bed. Recently a new model of self-organizing three-dimensional human blood vessel organoids (BVOs) has been developed from human pluripotent stem cells (hPSCs), composed of both endothelial and mural cells. BVO recapitulate key features of human microvasculature such as formation of vascular network, vascular lumen and basement membrane, and have been shown to be perfusable. Here, we report a new strategy to construct prevascularized islets by fusion with hPSC-derived BVOs. We demonstrate that islets and BVOs in co-culture leads to fusion and improved insulin secretion over time, on two independent human islet donors, suggesting a new therapeutic approach for pancreatic islet transplantation and type 1 diabetes modeling.

bioengineering↗

bioRxiv2021

Microfluidic device integrating a network of hyper-elastic valves for automated glucose stimulation and insulin secretion collection from a single pancreatic islet

Advances in microphysiological systems have prompted the need for robust and reliable cell culture devices. While microfluidic technology has made significant progress, devices often lack user-friendliness and are not designed to be industrialized on a large scale. Pancreatic islets are often being studied using microfluidic platforms in which the monitoring of fluxes is generally very limited, especially because the integration of valves to direct the flow is difficult to achieve. Considering these constraints, we present a thermoplastic manufactured microfluidic chip with an automated control of fluxes for the stimulation and secretion collection of pancreatic islet. The islet was directed toward precise locations through passive hydrodynamic trapping and both dynamic glucose stimulation and insulin harvesting were done automatically via a network of large deformation valves, directing the reagents and the pancreatic islet toward different pathways. This device we developed enables monitoring of insulin secretion from a single islet and can be adapted for the study of a wide variety of biological tissues and secretomes.

bioengineering↗