Biology subjects

Busse, B.

Publications and source records attributed to Busse, B..

5 recordsLinked to original sources

bioRxiv2021

Improved two-photon imaging of GPCR-based optogenetic neurotransmitter sensors using orthogonally polarized excitation

Fluorescent proteins such as GFP are best excited by light that is polarized parallel to the dipole axis of the fluorophore. In most cases, fluorescent proteins are randomly oriented, resulting in unbiased images even when polarized light is used for excitation, e.g. in two-photon microcopy. Here we reveal a surprisingly strong polarization sensitivity in a class of GPCR-based neurotransmitter sensors where the fluorophore is anchored on both ends. In tubular structures such as dendrites, this effect led to a complete loss of membrane signal in dendrites running parallel to the polarization direction of the excitation beam. Our data reveal a major problem for two-photon measurements of neurotransmitter concentration that has not been recognized by the neuroscience community. To remedy the sensitivity to dendritic orientation, we designed an optical device that generates interleaved pulse trains of orthogonal polarization, removing the orientation bias from images. The passive device, which we inserted in the beam path of an existing two-photon microscope, also removed the strong direction bias in second harmonic generation (SHG) images. We conclude that for optical measurements of transmitter concentration with GPCR-based sensors, orthogonally polarized excitation is essential.

neuroscience↗

bioRxiv2021

Wnt16 exerts pleiotropic effects on bone and lean mass in zebrafish

Bone and muscle interact through developmental, mechanical, paracrine, and autocrine signals. Genetic variants at the CPED1-WNT16 locus are dually associated with bone- and muscle-related traits. While Wnt16 is necessary for bone mass and strength, this fails to explain pleiotropy at this locus. Here, we show wnt16 is required for spine and muscle morphogenesis in zebrafish. In embryos, wnt16 is expressed in dermomyotome and developing notochord, and contributes to larval myotome morphology and notochord elongation. Later, wnt16 is expressed at the ventral midline of the notochord sheath, and contributes to spine mineralization and osteoblast recruitment. Morphological changes in wnt16 mutant larvae are mirrored in adults, indicating that wnt16 impacts bone and muscle morphology throughout the lifespan. Finally, we show that wnt16 is a gene of major effect on lean mass at the CPED1-WNT16 locus. Our findings indicate that Wnt16 is secreted in structures adjacent to developing bone (notochord) and muscle (dermomyotome) where it affects the morphogenesis of each tissue, thereby rendering wnt16 expression into dual effects on bone and muscle morphology. This work expands our understanding of wnt16 in musculoskeletal development and supports the potential for variants to act through WNT16 to influence bone and muscle via parallel morphogenetic processes. AUTHOR SUMMARYIn humans, genetic variants (DNA sequences that vary amongst individuals) have been identified that appear to influence bone and skeletal muscle mass. However, how single genes and genetic variants exert dual influence on both tissues is not well understood. In this study, we found a gene called wnt16 is necessary for specifying the size and shape of muscle and bone during development in zebrafish. Moreover, we disentangled how wnt16 affects both tissues: distinct cellular populations adjacent to muscle and bone secrete Wnt16, where it acts as a signal this guides the size and shape of each tissue. This is important because in humans, genetic variants near the WNT16 gene have effects on both bone- and muscle-related traits. This study expands our understanding of the role of WNT16 in bone and muscle development, and helps to explain how genetic variants near WNT16 affect traits for both tissues. Moreover, WNT16 is actively being explored as a target for osteoporosis therapies; our study could have implications with regard to the potential to target WNT16 to treat bone and muscle simultaneously.

genetics↗

bioRxiv2021

The effect of mentee and mentor gender on scientific productivity of applicants for NIH training fellowships

Several studies have suggested that women in science are less productive than men, and that this gap contributes to their under-representation in the ranks of senior researchers. However, few studies have examined the role of mentoring, and in particular mentor gender, on the productivity of female scientists early in their careers. Such efforts are limited by the difficulties of unambiguously linking mentees to their mentors and measuring the research productivity resulting from those relationships. Here we use our novel author disambiguation solution to investigate the role of self-identified gender in mentorship of 12,932 trainees who either successfully or unsuccessfully applied to the National Institutes of Health for research fellowships between fiscal years 2011 and 2017, applying a multi-dimensional framework to assess productivity. We found that, after normalizing for the funding level of mentors, the productivity of female and male mentees is indistinguishable; it is also independent of the gender of the mentor, other than in measures of clinical impact, where women mentored by women outperform other mentee-mentor dyads.

scientific communication and education↗

bioRxiv2020

FGFR3 is a positive regulator of osteoblast expansion and differentiation during zebrafish skull vault development

Gain- or loss-of-function mutations in fibroblast growth factor receptor 3 (FGFR3) result in cranial vault defects - highlighting the proteins role in membranous ossification. Zebrafish express high levels of fgfr3 during skull development; in order to study FGFR3s role in cranial vault development, we generated the first fgfr3 loss-of-function zebrafish (fgfr3lof/lof). The mutant fish exhibited major changes in the craniofacial skeleton, with a lack of sutures, abnormal frontal and parietal bones, and the presence of ectopic bones. Integrated analyses (in vivo imaging, and single-cell RNA sequencing of the osteoblast lineage) of zebrafish fgfr3lof/lof revealed a delay in osteoblast expansion and differentiation, together with changes in the extracellular matrix. These findings demonstrate that fgfr3 is a positive regulator of osteogenesis. We hypothesize that changes in the extracellular matrix within growing bone impair cell-cell communication, mineralization, and new osteoblast recruitment.

developmental biology↗

bioRxiv2018

Severely impaired bone material quality in Chihuahua zebrafish resembles classical dominant human osteogenesis imperfecta

AbstractExcessive skeletal deformations and brittle fractures in the vast majority of patients suffering from osteogenesis imperfecta (OI) are a result of substantially reduced bone quality. Since the mechanical competence of bone is dependent on the tissue characteristics at small length scales, it is of crucial importance to assess how osteogenesis imperfecta manifests at the micro- and nanoscale of bone. In this context, the Chihuahua (Chi/+) zebrafish, carrying a heterozygous glycine substitution in the 1 chain of collagen type I, has recently been proposed as suitable animal model of dominant OI. Similar to human severe OI type III, Chi/+ show skeletal deformities, altered mineralization patterns and a smaller body size. Using a multimodal approach targeting bone quality parameters, this study aims at quantifying the changes in bone morphology, structure and tissue composition of Chi/+ at multiple length scales. Morphological changes were assessed with high-resolution micro-CT imaging and showed that the vertebrae in Chi/+ had a significantly smaller size, thinner cortical shell and distorted shape. Tissue composition in vertebrae was investigated with quantitative backscattered electron microscopy and Fourier-transform infrared spectroscopy, showing higher mean calcium content, greater matrix porosity, as well as lower mineral crystallinity and collagen maturity in comparison to controls. This study provides comprehensive quantitative data on bone quality indices in Chi/+ and thus further validates this mutant as an important model reflecting osseous characteristics associated with human classical dominant osteogenesis imperfecta, both at the whole bone level and the tissue level.

pathology↗