Biology subjects

Gardner, J. M.

Publications and source records attributed to Gardner, J. M..

23 records · Page 2Linked to original sources

bioRxiv2021

A mitochondrial electron transport chain with atypical subunit composition confers oxygen sensitivity to a mammalian chemoreceptor

The carotid body (CB) is the major chemoreceptor for blood oxygen in the control of ventilation in mammals, contributing to physiological adaptation to high altitude, pregnancy, and exercise, and its hyperactivity is linked to chronic conditions such as sleep-disorder breathing, hypertension, chronic heart failure, airway constriction, and metabolic syndrome (1-3). Upon acute hypoxia (PO2=100 mmHg to <80 mmHg), K+ channels on CB glomus cells are inhibited, causing membrane depolarization to trigger Ca+2 influx and neurotransmitter release that stimulates afferent nerves (1-3). A longstanding model proposes that the CB senses hypoxia through atypical mitochondrial electron transport chain (ETC) metabolism that is more sensitive to decreases in oxygen than other tissues. This model is supported by observations that ETC inhibition by pharmacology and gene knockout activates CB sensory activity and that smaller decreases in oxygen concentration inhibit ETC activity in CB cells compared to other cells (1-5). Determining the composition of atypical ETC subunits in the CB and their specific activities is essential to delineate molecular mechanisms underlying the mitochondrial hypothesis of oxygen sensing. Here, we identify HIGD1C, a novel hypoxia inducible gene domain factor isoform, as an ETC Complex IV (CIV) protein highly and selectively expressed in glomus cells that mediates acute oxygen sensing by the CB. We demonstrate that HIGD1C negatively regulates oxygen consumption by CIV and acts with the hypoxia-induced CIV subunit COX4I2 to enhance the sensitivity of CIV to hypoxia, constituting an important component of mitochondrial oxygen sensing in the CB. Determining how HIGD1C and other atypical CIV proteins expressed in the CB work together to confer exquisite oxygen sensing to the ETC will help us better understand how tissue- and condition-specific CIV subunits contribute to physiological function and disease (6) and allow us to potentially target these proteins to treat chronic diseases characterized by CB dysfunction (7).

physiology↗

bioRxiv2020

The effect of grape juice dilution on oenological fermentation

The impact of water addition to grape juice in winemaking, on both alcoholic and malolactic fermentation duration and outcome has been examined using commercial wine yeasts, Lalvin EC1118 and Lalvin R2 and malolactic bacteria Lalvin VP41. As expected, dilution with water did not impede fermentation, instead resulted in shortened duration, or in the case of malolactic fermentation enabled completion in these conditions. Addition of complex organic nutrient further shortened alcoholic fermentation by Lalvin R2 and in some conditions also reduced the duration of malolactic fermentation. In general, volatile compounds and some major yeast metabolites were present at lower concentrations at the end of fermentation where juices were diluted and the addition of organic complex nutrient also influenced the concentration of some compounds in wine. These findings are significant to commercial winemaking, highlighting that winemakers should consider potential impacts of juice dilution on processing efficiencies along with wine flavour and aroma. Highlights: Gardner et al. The effect of grape juice dilution on fermentationO_LIGrape juice dilution shortened both alcoholic and malolactic fermentation C_LIO_LIIn some conditions addition of commercial nutrient decreased fermentation duration C_LIO_LIIn general wine volatiles decrease with grape juice dilution C_LIO_LIIsoamyl acetate can be decreased in wine by grape juice dilution C_LI

microbiology↗

bioRxiv2020

High-throughput identification of nuclear envelope protein interactions in Schizosaccharomyces pombe using an arrayed membrane yeast-two hybrid library

The nuclear envelope (NE) contains a specialized set of integral membrane proteins that maintain nuclear shape and integrity and influence chromatin organization and gene expression. Advances in proteomics techniques and studies in model organisms have identified hundreds of proteins that localize to the NE. However, the function of many of these proteins at the NE remains unclear, in part due to a lack of understanding of the interactions that these proteins participate in at the NE membrane. To assist in the characterization of NE transmembrane protein interactions we developed an arrayed library of integral and peripheral membrane proteins in the fission yeast Schizosaccharomyces pombe for high-throughput screening using the split-ubiquitin based membrane yeast two hybrid sys-tem. We used this approach to characterize protein interactions for three conserved proteins that localize to the inner nu-clear membrane: Cut11/Ndc1, Lem2, and Ima1/Samp1/NET5. Additionally, we determined how the interaction network for Cut11 is altered in canonical temperature-sensitive cut11 mutants. This library and screening approach is readily applicable to characterizing the interactomes of integral membrane proteins localizing to various subcellular compartments.

cell biology↗

bioRxiv2020

SWR1-independent association of H2A.Z to the LINC complex promotes meiotic chromosome motion

ABSTRACTThe H2A.Z histone variant is deposited into chromatin by the SWR1 complex affecting multiple aspects of meiosis. Here we describe a SWR1-independent localization of H2A.Z at meiotic telomeres and the centrosome. We demonstrate that H2A.Z colocalizes and interacts with Mps3, the SUN component of the LINC complex that spans the nuclear envelope and links meiotic telomeres to the cytoskeleton promoting meiotic chromosome movement. H2A.Z also interacts with the meiosis-specific Ndj1 protein that anchors telomeres to the nuclear periphery via Mps3. Telomeric localization of H2A.Z depends on Ndj1 and the N-terminal domain of Mps3. Although telomeric attachment to the nuclear envelope is maintained in the absence of H2A.Z, the distribution of Mps3 is altered. The velocity of chromosome movement during meiotic prophase I is reduced in the htz1Δ mutant lacking H2A.Z, but it is unaffected in swr1Δ cells. We reveal that H2A.Z is an additional LINC-associated factor that contributes to promote telomere-driven chromosome motion critical for error-free gametogenesis.Competing Interest StatementThe authors have declared no competing interest.Non-standard abbreviationsBiFCBimolecular Fluorescence ComplementationDICDifferential Interference ContrastKAcPotassium AcetateNENuclear EnvelopeLINCLinker of the Nucleoskeleton and CytoskeletonrDNARibosomal DNASCSynaptonemal ComplexSIMStructured Illumination MicroscopySPBSpindle Pole BodyVCC-terminal moiety of the Venus fluorescent proteinVNN-terminal moiety of the Venus fluorescent proteinWCEWhole cell extractsView Full Text

cell biology↗

bioRxiv2018

Membrane insertion function for SUN-KASH complex revealed by high resolution analysis of yeast centrosomes

Bipolar spindle formation in yeast requires insertion of centrosomes (known as spindle pole bodies (SPBs)) into fenestrated regions of the nuclear envelope (NE). Using structured-illumination microscopy and bimolecular fluorescence complementation, we map protein distribution at SPB fenestra and interrogate protein-protein interactions with high spatial resolution. We find that the Sad1-UNC-84 (SUN) protein Mps3 forms a ring-like structure around the SPB, similar to toroids seen for components of the SPB insertion network (SPIN). Mps3 and the SPIN component Mps2 (a Klarsicht-ANC-1-Syne-1 domain (KASH)-like protein) form a novel non-canonical linker of nucleoskeleton and cytoskeleton (LINC) complex that is connected in both luminal and extraluminal domains. This hairpin-like LINC complex forms during SPB insertion, suggesting it functions in NE reorganization at the pore membrane. The LINC complex also controls the distribution of a soluble SPIN component Bbp1. Taken together our work shows that Mps3 is a fifth SPIN component and suggests both direct and indirect roles for the LINC complex in NE remodeling.

cell biology↗