Characteristics of the life history of the coral reef‐dwelling cardinalfish
Recently, we reported the discovery of a novel endoglucanase of the glycoside hydrolase family 12 (GH12), designated IfCelS12A, from the haloalkaliphilic anaerobic bacterium
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- Award ID(s):
- 1818346
- NSF-PAR ID:
- 10484906
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Applied Microbiology and Biotechnology
- Volume:
- 108
- Issue:
- 1
- ISSN:
- 0175-7598
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Background Future expansion of corn-derived ethanol raises concerns of sustainability and competition with the food industry. Therefore, cellulosic biofuels derived from agricultural waste and dedicated energy crops are necessary. To date, slow and incomplete saccharification as well as high enzyme costs have hindered the economic viability of cellulosic biofuels, and while approaches like simultaneous saccharification and fermentation (SSF) and the use of thermotolerant microorganisms can enhance production, further improvements are needed. Cellulosic emulsions have been shown to enhance saccharification by increasing enzyme contact with cellulose fibers. In this study, we use these emulsions to develop an emulsified SSF (eSSF) process for rapid and efficient cellulosic biofuel production and make a direct three-way comparison of ethanol production between
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Kluyveromyces marxianus andOgataea polymorpha , as well asSaccharomyces cerevisiae , and observed robust fermentation at up to 46, 50, and 42 °C for each yeast, respectively. We show that the eSSF process reaches high ethanol titers in short processing times, and produces close to theoretical yields at temperatures as low as 30 °C. Finally, we demonstrate the transferability of the eSSF technology to other products by producing the advanced biofuel isobutanol in a light-controlled eSSF using optogenetic regulators, resulting in up to fourfold higher titers relative to MCC SSF.Conclusions The eSSF process addresses the main challenges of cellulosic biofuel production by increasing saccharification rate at temperatures tolerable to yeast. The rapid hydrolysis of these emulsions at low temperatures permits fermentation using non-thermotolerant yeasts, short processing times, low enzyme loads, and makes it possible to extend the process to chemicals other than ethanol, such as isobutanol. This transferability establishes the eSSF process as a platform for the sustainable production of biofuels and chemicals as a whole.
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Key points Association of plasma membrane BKCachannels with BK‐β subunits shapes their biophysical properties and physiological roles; however, functional modulation of the mitochondrial BKCachannel (mitoBKCa) by BK‐β subunits is not established.
MitoBKCa‐α and the regulatory BK‐β1 subunit associate in mouse cardiac mitochondria.
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V 1/2 = −55 mV, 12 µm matrix Ca2+).In BK‐β1 knockout mice, cardiac mitoBKCadisplayed a low
P oand a depolarizedV 1/2of activation (+47 mV at 12 µm matrix Ca2+)Co‐expression of BKCawith the BK‐β1 subunit in HeLa cells doubled the density of BKCain mitochondria.
The present study supports the view that the cardiac mitoBKCachannel is functionally modulated by the BK‐β1 subunit; proper targeting and activation of mitoBKCashapes mitochondrial Ca2+handling.
Abstract Association of the plasma membrane BKCachannel with auxiliary BK‐β1–4 subunits profoundly affects the regulatory mechanisms and physiological processes in which this channel participates. However, functional association of mitochondrial BK (mitoBKCa) with regulatory subunits is unknown. We report that mitoBKCafunctionally associates with its regulatory subunit BK‐β1 in adult rodent cardiomyocytes. Cardiac mitoBKCais a calcium‐ and voltage‐activated channel that is sensitive to paxilline with a large conductance for K+of 300 pS. Additionally, mitoBKCadisplays a high open probability (
P o) and voltage half‐activation (V 1/2 = −55 mV,n = 7) resembling that of plasma membrane BKCawhen associated with its regulatory BK‐β1 subunit. Immunochemistry assays demonstrated an interaction between mitochondrial BKCa‐α and its BK‐β1 subunit. Mitochondria from the BK‐β1 knockout (KO) mice showed sparse mitoBKCacurrents (five patches with mitoBKCaactivity out of 28 total patches fromn = 5 different hearts), displaying a depolarizedV 1/2of activation (+47 mV in 12 µm matrix Ca2+). The reduced activity of mitoBKCawas accompanied by a high expression of BKCatranscript in the BK‐β1 KO, suggesting a lower abundance of mitoBKCachannels in this genotype. Accordingly, BK‐β1subunit increased the localization of BKDEC (i.e. the splice variant of BKCathat specifically targets mitochondria) into mitochondria by two‐fold. Importantly, both paxilline‐treated and BK‐β1 KO mitochondria displayed a more rapid Ca2+overload, featuring an early opening of the mitochondrial transition pore. We provide strong evidence that mitoBKCaassociates with its regulatory BK‐β1 subunit in cardiac mitochondria, ensuring proper targeting and activation of the mitoBKCachannel that helps to maintain mitochondrial Ca2+homeostasis. -
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ABSTRACT BACKGROUND AND PURPOSE Transvascular water exchange plays a key role in the functional integrity of the blood–brain barrier (BBB). In white matter (WM), a variety of imaging modalities have demonstrated age‐related changes in structure and metabolism, but the extent to which water exchange is altered remains unclear. Here, we investigated the cumulative effects of healthy aging on WM capillary water exchange.
METHODS A total of 38 healthy adults (aged 36‐80 years) were studied using 7T dynamic contrast enhanced MRI. Blood volume fraction (
vb ) and capillary water efflux rate constant (k po) were determined by fitting changes in the1H2O longitudinal relaxation rate constant (R1) during contrast agent bolus passage to a two‐compartment exchange model. WM volume was determined by morphometric analysis of structural images.RESULTS R1values and WM volume showed similar trajectories of age‐related decline. Among all subjects,
vb andk poaveraged 1.7 (±0.5) mL/100 g of tissue and 2.1 (±1.1) s−1, respectively. Whilevb showed minimal changes over the 40‐year‐age span of participants,k podeclined 0.06 s−1(ca. 3%) per year (r = −.66;P < .0005), from near 4 s−1at age 30 to ca. 2 s−1at age 70. The association remained significant after controlling for WM volume.CONCLUSIONS Previous studies have shown that
k potracks Na+, K+‐ATPase activity‐dependent water exchange at the BBB and likely reflects neurogliovascular unit (NGVU) coupled metabolic activity. The age‐related decline ink poobserved here is consistent with compromised NGVU metabolism in older individuals and the dysregulated cellular bioenergetics that accompany normal brain aging.
