StFX Scholar (St. Francis Xavier University)
Not a member yet
55051 research outputs found
Sort by
Francis Grace
No full textposted: SaltWire, Jul. 14, 2021; funeral arrangements by MacIsaac Funeral Home; "Francie"; formerly of Croft, Antigonis
Marcel Joseph Gagnon
No full textposted: SaltWire, May 3, 2021; funeral arrangements by Dennis Haverstock Funeral Home
Barbara Lorraine (MacArthur) Gammon
No full textposted: SaltWire, May 6, 2021; funeral arrangements by C. L. Curry Funeral Service
Donna Bernadette Greencorn
No full textposted: SaltWire, Nov. 23, 2021; funeral arrangements by C. L. Curry Funeral Service
William Thomas Bryson
No full textposted: SaltWire, Oct. 22, 2021; funeral arrangements by Dennis Haverstock Funeral Homes; "Bill"
Donald Alexander Barry
No full textposted: SaltWire, Jul. 22, 2021; funeral arrangements by MacIsaac Funeral Home; St.F.X., B.A., '47; M. Adult Ed., '7
A Review of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) in Non-Mammalian Vertebrates and Insights into Functional Divergence
No full textThe cystic fibrosis transmembrane conductance regulator (CFTR) monovalent anion channel is an integral component of osmoregulation in vertebrates, facilitating chloride and bicarbonate transport across the plasma membrane of ion exchange epithelia. Teleost fish present a unique opportunity to better our understanding of CFTR because of their highly labile salt-transporting systems, and because the processes by which teleost fish respond to osmotic stress through CFTR are well studied. Most of the molecular work with CFTR in teleost fishes has occurred since the previous review. CFTR localizes at the apical crypt of saltwater (SW) ion exchanging epithelial cells such as gill ionocytes to facilitate chloride secretion. Teleost gill ionocytes often exhibit plasticity between subtypes with or without CFTR depending on salinity. Several signaling pathways converge at CFTR. Chloride secretion is activated by cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA). Hypotonicity inhibits chloride secretion through focal adhesion kinase (FAK) and protein tyrosine kinase 2-beta (PYK2). Intracellular chloride inhibits chloride secretion though the With-no-lysine kinase 1 (WNK1) pathway. Hypotonicity also appears to increase nitric oxide production and decrease chloride secretion in ion exchange epithelia. In addition to this post-translational regulation converging at the Regulatory (R)domain, regulation of cftr occurs at the transcriptional level. Arginine-vasotocin (AVT) and cortisol stimulate an increase in cftr transcription through downstream targets. With what we have achieved so far, the euryhaline teleost fish remains a viable and valuable model organism for studying the processing, function, and regulation of CFTR in ion-exchanging epithelia.
Some research has been dedicated to finding the origin of CFTR and its R domain, however there are no comprehensive phylogenies of teleost CFTR. To examine teleost CFTR evolutionary history and gain insight into divergence of salinity tolerance, we conducted a phylogenetic analysis with 60 teleost CFTR amino acid sequences. Additionally, we examined the CFTR sequences for conserved protein kinase A (PKA) phosphorylation sites within the regulatory (R) domain with group-based prediction software (GPS). Six SW-freshwater (FW) transitions are robustly shown to occur in modern FW fishes within the Percomorphaceae clade, indicating at least six secondary losses of SW tolerance in teleost fishes. Eight putative, well conserved PKA consensus sites were identified at S659, S669, S685, S707, S720, S749, S780, and S825 relative to Fundulus heteroclitus CFTR. Deleterious mutations occur in many lineages, and the quantity and severity of deleterious mutations between phosphorylation sites differs between SW, primitive FW (PFW), modern FW (MFW), and (total) FW Teleostei groups. Mean FW score is significantly less than SW only at site S669. At S659, S669, and S707, the mean PFW score is lower than MFW. At S806, the mean MFW score is greater than PFW. There are more deleterious mutations at CFTR S659, S669, and S707 in PFW vs MFW fishes, particularly in the PFW Otophysi clade. We predict that loss of SW-tolerance in PFW teleost fishes may be related to deleterious mutations in the CFTR R-domain. Conversely in MFW teleost fishes, the six secondary losses of salinity tolerance may have been first facilitated by mutations in other genes pertinent to osmoregulation, other important phosphorylation sites of the R domain, or other domains of CFTR. Overall, this analysis of CFTR divergence at regions important for regulation may serve as an example of gate-like changes in essential proteins from genetic drift
Carol Anne (Googoo) Russell
No full textposted: Le Necrologue, Echovita; funeral arrangements by Dennis Haverstock Funeral Homes; adopted parents: David and Margo Russell, of New Brunswick; late stepmother: Martha; stepmom: Dita Googo
Rare-earth magnets influence movement patterns of the magnetically sensitive Nudibranch Tritonia exsulans in its natural habitat
No full textThe nudibranch Tritonia exsulans (previously Tritonia diomedea) is known to have behaviors and neurons that can be modified by perturbations of the Earth’s magnetic field. There is no definitive evidence for how this magnetic sense is used in nature. Using an exploratory approach, we tested for possible effects of magnetic perturbations based on underwater video of crawling patterns in the slugs’ natural habitat, with magnets of varying strength deployed on the substrate. For analysis, we used a paired comparison of tracks of animals between segments 25–50 cm distant from the magnets and segments of the same tracks 0–25 cm from the magnets, to determine whether any differences depended on the strength of the magnet. Most track measurements (length, displacement, velocity, and tortuosity) showed no such differences. However, effects were observed for the changes in track headings between successive points. These results showed that tracks had relatively higher heading variability when they moved closer to stronger magnets. We suggest that this supports a hypothesis that T. exsulans continuously uses a magnetic sense to help maintain straight-line navigation. Further specific testing of the hypothesis is now needed to verify this new possibility for how animals can benefit from a compass sense
Marie Elizabeth (Keeler) Jackson
No full textposted: Le Necrologue; funeral arrangements by C. L. Curry Funeral Services; formerly of Monaster