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Plant and non-plant species possess cryptochrome (CRY) photoreceptors to mediate blue-light regulation of development or the circadian clock. The blue light-dependent homooligomerization of Arabidopsis CRY2 is a known early photoreaction necessary for its functions, but the photobiochemistry and function of light-dependent homooligomerization and heterooligomerization of cryptochromes, collectively referred to as CRY photooligomerization, have not been well-established. Here we show that photooligomerization is an evolutionarily conserved photoreaction characteristic of the CRY photoreceptors in plant and some non-plant species. Our analyses of the kinetics of the forward and reverse reactions of photooligomerization of Arabidopsis CRY1 and CRY2 provide a previously unrecognized mechanism underlying the

Cryptochromes (CRYs) are photoreceptors or components of the molecular clock in various evolutionary lineages, and they are commonly regulated by polyubiquitination and proteolysis. Multiple E3 ubiquitin ligases regulate CRYs in animal models, and previous genetics study also suggest existence of multiple E3 ubiquitin ligases for plant CRYs. However, only one E3 ligase, Cul4COP1/SPAs, has been reported for plant CRYs so far. Here we show that Cul3LRBs is the second E3 ligase of CRY2 in Arabidopsis. We demonstrate the blue light-specific and CRY-dependent activity of LRBs (Light-Response Bric-a-Brack/Tramtrack/Broad 1, 2 & 3) in blue-light regulation of hypocotyl elongation. LRBs physically interact with photoexcited and phosphorylated CRY2, at the CCE domain of CRY2, to facilitate polyubiquitination and degradation of CRY2 in response to blue light. We propose that Cul4COP1/SPAs and Cul3LRBs E3 ligases interact with CRY2 via different structure elements to regulate the abundance of CRY2 photoreceptor under different light conditions, facilitating optimal photoresponses of plants grown in nature.

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Brassinosteroid is necessary for sugar promotion of Arabidopsis hypocotyl elongation in darkness, and sugar positively regulates BRASSINAZOLE RESISTANT1 (BZR1) at both transcription and protein levels. Sugar has the ability to induce Arabidopsis hypocotyl elongation in the dark, but the detailed mechanisms remain not well understood. Here, we report that the steroidal phytohormone brassinosteroid (BR) is involved in sugar promotion of hypocotyl elongation in the dark. Sugar-induced hypocotyl elongation was significantly repressed in the BR-deficient mutant det2-1, BR-insensitive mutant bri1-5, and wild-type plants (Col-0), but not in the BR-hypersensitive mutants bzr1-1D and bes1-D treated with the BR biosynthetic inhibitor brassinazole (BRZ). Sugar also up-regulated the expression of genes that are related to cell elongation in a BR-dependent manner, and this effect was more remarkable in bzr1-1D and bes1-D than in their corresponding wild types in the presence of BRZ, suggesting an important role of BZR1 and bri1-ems-suppressor 1 (BES1) in this process. Sugar treatment seems to have little effect on BR biosynthesis, but enhances the expression of BZR1 and BES1, two transcription factors in BR signaling, in the dark. Furthermore, sugar treatment maintains higher BZR1 protein levels in plants grown in the dark. Collectively, our results indicate that BR is required for sugar promotion of hypocotyl elongation in darkness in Arabidopsis.

PURPOSE. Lenses have an intracellular hydrostatic pressure gradient to drive fluid from central fiber cells to surface epithelial cells. Pressure is regulated by a feedback control system that relies on transient receptor potential vanilloid (TRPV)1 and TRPV4 channels. The ciliary muscle transmits tension to the lens through the zonules of Zinn. Here, we have examined if ciliary muscle tension influenced the lens intracellular hydrostatic pressure gradient. METHODS. We measured the ciliary body position and intracellular hydrostatic pressures in mouse lenses while pharmacologically causing relaxation or contraction of the ciliary muscle. We also used inhibitors of TRPV1 and TRPV4, in addition to phosphoinositide 3-kinase (PI3K) p110a knockout mice and immunostaining of phosphorylated protein kinase B (Akt), to determine how changes in ciliary muscle tension resulted in altered hydrostatic pressure. RESULTS. Ciliary muscle relaxation increased the distance between the ciliary body and the lens and caused a decrease in intracellular hydrostatic pressure that was dependent on intact zonules and could be blocked by inhibition of TRPV4. Ciliary contraction moved the ciliary body toward the lens and caused an increase in intracellular hydrostatic pressure and Akt phosphorylation that required intact zonules and was blocked by either inhibition of TRPV1 or genetic deletion of the p110a catalytic subunit of PI3K. CONCLUSIONS. These results show that the hydrostatic pressure gradient within the lens was influenced by the tension exerted on the lens by the ciliary muscle through the zonules of Zinn. Modulation of the gradient of intracellular hydrostatic pressure in the lens could alter the water content, and the gradient of refractive index.

The biological functions of long noncoding RNAs (lncRNAs), which play an important role in regulating development and gene expression, may be affected by variations in lncRNA gene loci or associated genomic sequences. However, the functions of many lncRNAs remain unknown. To analyse correlations between mutations in pouMU1 with chicken growth and carcass traits, 860 chickens from a Gushi×Anka F2 resource population and 96 Lushi, Xichuan, Changshun and recessive white chickens were used to evaluate the genetic effect of the pouMU1 gene. We performed quantitative real-time polymerase chain reaction (qRT-PCR) to analyse the relative expression levels of pouMU1 in nine different tissues and stages of development. pouMU1 expression was highest in pectoralis and leg muscles, whereas no expression was observed in the heart, liver and abdominal fat. Using direct sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods, two novel sequence mutations (g.1198A>G and g.1238-1239del/insGA) were detected in the pouMU1 gene. SPSS software was used for statistical analysis in association studies. Based on the association data, the presence of both variants was significantly associated with leg muscle fibre width and leg muscle fibre roundness (P < 0.05) and highly associated with leg muscle fibre girth and body weight at 0 week of age (P < 0.01). These data suggest that pouMU1 might participate in regulating chicken muscle development and growth, and the findings offer new insight into the functions of sequence mutations in lncRNAs.