Attention:The NSF Public Access Repository (PAR) system and access will be unavailable from 5:00 PM ET until 8:00 PM ET on Friday, September 11 due to maintenance. We apologize for the inconvenience.


Title: Temperature-Dependent Reversible Morphological Transformations in N -Oleoyl β- d -Galactopyranosylamine
Award ID(s):
1844346
PAR ID:
10206598
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
The Journal of Physical Chemistry B
Volume:
124
Issue:
26
ISSN:
1520-6106
Page Range / eLocation ID:
5426 to 5433
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract Hemoglobin III (HbIII) is one of the two oxygen reactive hemoproteins present in the bivalve,Lucina pectinata. The clam inhabits a sulfur‐rich environment and HbIII is the only hemoprotein present in the system which does not yet have a structure described elsewhere. It is known that HbIII exists as a heterodimer with hemoglobin II (HbII) to generate the stable Oxy(HbII‐HbIII) complex but it remains unknown if HbIII can form a homodimeric species. Here, a new chromatographic methodology to separate OxyHbIII from the HbII‐HbIII dimer has been developed, employing a fast performance liquid chromatography and ionic exchange chromatography column. The nature of OxyHbIII in solution at concentrations from 1.6 mg/mL to 20.4 mg/mL was studied using small angle X‐ray scattering (SAXS). The results show that at all concentrations, the Oxy(HbIII‐HbIII) dimer dominates in solution. However, as the concentration increases to nonphysiological values, 20.4 mg/mL, HbIII forms a 30% tetrameric fraction. Thus, there is a direct relationship between the Oxy(HbIII‐HbIII) oligomeric form and hemoglobin concentration. We suggest it is likely that the OxyHbIII dimer contributes to active oxygen transport in tissues ofL pectinata, where the Oxy(HbII‐HbIII) complex is not present. 
    more » « less
  2. null (Ed.)
  3. ABSTRACT Arctic deciduous shrubs have responded to warming by increasing cover and extent, but how plant interactions (i.e., facilitation and competition) among deciduous shrub species might influence their climate sensitivities and overall growth remains unclear. Here, we investigate two deciduous shrubs:Betula nanassp.exilis(dwarf birch) andAlnus viridisssp.fruticosa(Siberian alder), the Arctic's only tall N‐fixing shrub, to determine how Siberian alder affects the growth of nearby dwarf birch. We harvested dwarf birch shrubs growing ‘near’ (i.e., within 1 m) and ‘away’ (≥ 3 m) from Siberian alders growing along the Sagwon Bluffs in Arctic Alaska for dendrochronological analysis. Dwarf birch traits and other site characteristics, including height, leaf N, catkin production, frost damage, and snow depth, were measured at additional sites nearby. We discovered locations ‘near’ Siberian alder had greater snow depth, which delayed the growing season for nearby dwarf birch, but likely protected them from early‐season frost damage. We estimated that radial growth occurring within 1979–2016 was delayed by 9 days, and peak radial growth was delayed by 2 weeks, for dwarf birch growing ‘near’ as compared to ‘away’ from alder. This resulted in different climate sensitivities for dwarf birch between locations. Measures of dwarf birch height, catkin abundance, leaf N, and average growth ring area were greater for plants ‘near’ alder than those ‘away’ from alder. This suggests that Siberian alder increased N mineralization and soil N availability under the deeper snowpack. Siberian alder facilitated dwarf birch growth. Through plant–plant interactions, Siberian alder altered the strength and type of stressors dwarf birch experienced, resulting in a change to the seasonality of its radial growth. Therefore, high‐spatial resolution species composition data could be included in vegetation models to predict future tundra growth responses more accurately to a changing climate. 
    more » « less