In this general chemistry laboratory exercise, the absorbance of [CoCl(iPrOH)3]+, where iPrOH is isopropyl alcohol, is used to determine the equilibrium constants for its reaction with methanol to form [CoCl(iPrOH)2(MeOH)3]+ in the temperature range ∼10 to 20 °C. The absorbance versus concentration calibration plot is determined by sequential additions of a concentrated [CoCl(iPrOH)3]Cl standard to iPrOH. The equilibrium mixture is cooled in a CaCl2–ice bath, and measurements of temperature and absorbance are made at various time intervals as the solution warms to room temperature. The variation in the equilibrium constant as a function of temperature is used to determine the Gibbs energy, enthalpy, and entropy.

Transcriptional regulatory mechanisms governing plant cell wall biosynthesis are incomplete. Expression programs that activate wall biosynthesis are well understood, but mechanisms that control the attenuation of gene expression networks remain elusive. Previous work has shown that small RNAs (sRNAs) derived from the HvCESA 6 ( Hordeum vulgare , Hv ) antisense transcripts are naturally produced and are capable of regulating aspects of wall biosynthesis. Here, we further test the hypothesis that CESA ‐derived sRNAs generated from CESA antisense transcripts are involved in the regulation of cellulose and broader cell wall biosynthesis. Antisense transcripts were detected for some but not all members of the CESA gene family in both barley and Brachypodium distachyon . Phylogenetic analysis indicates that antisense transcripts are detected for most primary cell wall CESA genes, suggesting a possible role in the transition from primary to secondary cell wall biosynthesis. Focusing on one antisense transcript, HvCESA1 shows dynamic expression throughout development, is correlated with corresponding sRNAs over the same period and is anticorrelated with HvCESA1 mRNA expression. To assess the broader impacts of CESA ‐derived sRNAs on the regulation of cell wall biosynthesis, transcript profiling was performed on barley tissues overexpressing CESA ‐derived sRNAs. Together, the data support the hypothesis that CESA antisense transcripts function through an RNA‐induced silencing mechanism, to degrade cis transcripts, and may also trigger trans ‐acting silencing on related genes to alter the expression of cell wall gene networks.

15Transcriptional regulatory mechanisms governing plant cell wall biosynthesis are 16 incomplete. Expression programs that activate wall biosynthesis are well understood, 17 but mechanisms that control the attenuation of gene expression networks remain 18 elusive. Previous work has shown that small RNAs (sRNAs) derived from the 19 HvCESA6 (Hordeum vulgare, Hv) antisense transcripts are naturally produced and are 20 capable of regulating aspects of wall biosynthesis. Here, we further test the hypothesis 21 that CESA-derived sRNAs generated from CESA antisense transcripts are involved in 22 the regulation of cellulose and broader cell wall biosynthesis. Antisense transcripts 23 were detected for some, but not all members of the CESA gene family in both barley 24and Brachypodium distachyon. Phylogenetic analysis indicates that antisense transcripts 25 are detected for most primary cell wall CESA genes, suggesting a possible role in the 26 transition from primary to secondary cell wall biosynthesis. Focusing on one antisense 27 transcript, HvCESA1 shows dynamic expression throughout development, is correlated 28 with corresponding sRNAs over the same period and is anticorrelated with HvCESA1 29 mRNA expression. To assess the broader impacts of CESA-derived sRNAs on the 30 regulation of cell wall biosynthesis, transcript profiling was performed on barley tissues 31 overexpressing CESA-derived sRNAs. Together the data support the hypothesis that 32 CESA antisense transcripts function, through an RNA-induced silencing mechanism, to 33 degrade cis transcripts, and may also trigger trans-acting silencing on related genes to 34 alter the expression of cell wall gene networks. 35 36