Enhanced Sp1/YY1 Expression Directs CBS Transcription to Mediate VEGF-Stimulated Pregnancy-Dependent H 2 S Production in Human Uterine Artery Endothelial Cells

Pregnancy and VEGF (vascular endothelial growth factor) stimulate uterine artery endothelial cell (UAEC) hydrogen sulfide production via selectively upregulating CBS (cystathionine β-synthase) but not CSE (cystathionine γ-lyase) expression. This study was conducted to determine the mechanisms by which VEGF utilizes to stimulate pregnancy-dependent upregulation of CBS and hydrogen sulfide production in human UAEC. The proximal human CBS promoter contains 4 Sp1 (specificity protein 1; a/b/c/d) sites and 1 YY1 (Yin Yang 1) site; luciferase assays using reporter genes driven by human CBS promoter with a series of 5′-deletions identified a promoter sequence (−574 to −394) containing Sp1d and the YY1 sites critical for basal and VEGF-stimulated CBS promoter activation. VEGF stimulated pregnancy-dependent recruitment of Sp1 to Sp1d and YY1 to YY1 and also recruited YY1 to Sp1c and increased Sp1/YY1 association in pregnant human UAEC, suggesting formation of a Sp1/YY1 complex at the Sp1c site. Endothelial Sp1 and YY1 proteins were significantly greater in pregnant than nonpregnant human uterine artery. VEGF stimulated pregnancy-dependent Sp1 and YY1 protein expression in vitro. Treatment with Sp1 and YY1 siRNAs completely blocked Sp1/YY1-mediated pregnancy-dependent CBS protein upregulation and hydrogen sulfide production by VEGF in human UAEC. VEGF did not trans -activate CSE promoter or increase CSE expression, and Sp1/YY1 knockdown did not affect CSE expression in human UAEC. Thus, pregnancy augments EC Sp1 and YY1 expression and promotes the recruitment of Sp1/YY1 to their DNA-binding sequences in proximal human CBS promoter to upregulate CBS transcription, underlying a novel mechanism to mediate VEGF-stimulated pregnancy-dependent endothelial hydrogen sulfide production in the human uterine artery.

Mill Scale Addition to Reduce Hydrogen Sulfide Production in Anaerobic Digestion

Direct addition of sulfur-reducing agents during anaerobic digestion (AD) is very effective in controlling hydrogen sulfide (H2S) content in biogas, although one major problem is the high operational cost due to the large amount of chemicals used. The objective of this study was to remove H2S using a waste mill scale (MS) as a sulfur-reducing agent. To evaluate its feasibility, MS was added to AD fed with food waste (FW) at concentrations between 0 and 160 g MS/kg total chemical oxygen demand (TCOD) during the batch test, and the experimental results were compared to those of the batch test with the addition of iron chloride (FeCl3). Both FeCl3 and MS played an important role as electro-conductive materials in improving methane productivity by promoting direct interspecies electron transfer. An increase in H2S removal efficiency was observed with increases in both materials. In total, 30%, 60%, and 90% of H2S production based on the maximum sulfur in the form of H2S (control) was 3.7, 9.4, and 23.8 g FeCl3/kg TCOD and 13.3, 34.1, and 86.2 g MS/kg TCOD, respectively. This finding indicates that MS can be used as a sulfur-reducing agent substitute for H2S removal in AD fed with FW.

Induction of Glutathione Synthesis Provides Cardioprotection Regulating NO, AMPK and PPARa Signaling in Ischemic Rat Hearts

Glutathione (GSH) is essential for antioxidant defence, and its depletion is associated with tissue damage during cardiac ischemia-reperfusion (I/R). GSH is synthesized by the glutamate-cysteine ligase enzyme (GCL) from L-cysteine, which alternatively might be used for hydrogen sulfide production by cystathionine-gamma-lyase (CSE). Here, we have investigated whether in vivo treatment with L-cysteine and an inhibitor of CSE,D,L-propargylglycine (PAG), can modulate cardiac glutathione and whether this treatment can influence heart resistance to I/R in a Langendorff isolated rat hearts model. Pretreatment with PAG + L-cysteine manifested in pronounced cardioprotection, as there was complete recovery of contractile function; preserved constitutive NOS activity; and limited the production of reactive oxygen and nitrogen species in the ischemized myocardium. Cardiac GSH and GSSG levels were increased by 3.5- and 2.1-fold in PAG + L-cysteine hearts and were 3.3- and 3.6-fold higher in PAG + L-cysteine + I/R compared to I/R heart. The cardioprotective effect of PAG + L-cysteine was completely abolished by an inhibitor of GCL, DL-buthionine-(S,R)-sulfoximine. Further analysis indicated diminished fatty acid β-oxidation, increased glucose consumption and anaerobic glycolysis, and promoted OXPHOS proteins and SERCA2 in PAG + L-cysteine + I/R compared to the I/R group. PAG + L-cysteine inhibited PPARα and up-regulated AMPK signalling in the heart. Thus, induction of glutathione synthesis provided cardioprotection regulating NO, AMPK and PPARa signaling in ischemic rat hearts.

A novel deep-sea bacterial threonine dehydratase drives cysteine desulfuration and hydrogen sulfide production

ABSTRACTCysteine desulfuration is one of the main ways for hydrogen sulfide (H2S) generation in cells and is usually conducted by cystathionine γ-lyase. Herein, we describe a newly discovered deep-sea bacterial threonine dehydratase (psTD), which is surprisingly discovered to drive L-cysteine desulfuration. The mechanisms of psTD catalyzing cysteine desulfuration towards H2S production are first clarified in vitro and in vivo through a combination of genetic and biochemical methods. Furthermore, based on the solved structures of psTD and its various mutants, two or three pockets are found in the active site of psTD, and switch states between inward and outward orientation of a key amino acid R77 determine the open or close status of Pocket III for small molecule exchanges, which further facilitates cysteine desulfuration. Our results reveal the functional diversity and structural specificity of psTD towards L-cysteine desulfuration and H2S formation. Given the broad distribution of psTD homologs in different bacteria, we speculate that some threonine dehydratases have evolved a novel function towards cysteine desulfuration, which benefits the producer to utilize cysteine as a sulfur source for better adapting external environments.

Soil Nitrogen Fertilization Increases Yeast Assimilable Nitrogen Concentrations in ‘Golden Russet’ and ‘Medaille d’Or’ Apples Used for Cider Production

The recent growth in the U.S. hard-cider industry has increased the demand for cider apples (Malus ×domestica Borkh.), but little is known about how to manage orchard soil fertility best to optimize horticultural performance and juice characteristics for these cultivars. To assess whether nitrogen fertilizer applied to the soil can improve apple juice and cider quality, calcium nitrate (CaNO3) fertilizer was applied at different rates to the soil beneath ‘Golden Russet’ and ‘Medaille d’Or’ trees over the course of three growing seasons. The experiment started when the trees were in their second leaf. The trees were cropped in their third and fourth leaf. At the end of the first growing season of the experiment, the greatest fertilizer rate increased tree trunk cross-sectional area (TCSA) by 82% relative to the control, but this difference did not persist through to the end of the study. Yield and crop load were unaffected by the nitrogen fertilization treatments. Increasing the nitrogen fertilizer rate correlated positively with more advanced harvest maturity in ‘Golden Russet’ fruit, which resulted in greater soluble solid concentration (SSC). Fruit from the greatest fertilizer rate treatment had an average starch pattern index (SPI) that was 1 U greater than in the control, and an SSC that was 3% greater than the control. The fertilizer treatments did not affect juice pH, titratable acidity (TA), or total polyphenol concentrations. Yeast assimilable nitrogen (YAN) concentrations were increased by nitrogen fertilization for both cultivars in both harvest years. The greatest fertilizer treatment increased juice primary amino nitrogen by 103% relative to the control. Greater nitrogen fertilization rates correlated positively with less hydrogen sulfide production during the fermentation of ‘Golden Russet’ juice from the first, but not the second, harvest. During the first year, cumulative hydrogen sulfide production for the ‘Golden Russet’ control treatment was 29.6 μg·L–1 compared with the ‘Golden Russet’ high treatment, which cumulatively produced 0.1 μg·L–1. Greater maximum fermentation rates and shorter fermentation durations correlated positively with increased fertilization rate for both cultivars after the second harvest. High treatment fermentations had maximum fermentation rates 110% greater, and fermentation durations 30% shorter than the control. Other horticultural and juice-quality parameters were not affected negatively by the CaNO3 treatments. In orchards producing apples specifically for the hard-cider industry, nitrogen fertilizer could increase juice YAN, thus reducing the need for exogenous additions during cider production.