Structure of the frequency‐interacting RNA helicase: a protein interaction hub for the circadian clock

In the Neurospora crassa circadian clock, a protein complex of frequency (FRQ), casein kinase 1a (CK1a), and the FRQ‐interacting RNA Helicase (FRH) rhythmically represses gene expression by the white‐collar complex (WCC). FRH crystal structures in several conformations and bound to ADP/RNA reveal differences between FRH and the yeast homolog Mtr4 that clarify the distinct role of FRH in the clock. The FRQ‐interacting region at the FRH N‐terminus has variable structure in the absence of FRQ. A known mutation that disrupts circadian rhythms (R806H) resides in a positively charged surface of the KOW domain, far removed from the helicase core. We show that changes to other similarly located residues modulate interactions with the WCC and FRQ. A V142G substitution near the N‐terminus also alters FRQ and WCC binding to FRH, but produces an unusual short clock period. These data support the assertion that FRH helicase activity does not play an essential role in the clock, but rather FRH acts to mediate contacts among FRQ, CK1a and the WCC through interactions involving its N‐terminus and KOW module.     

The wheat TaGBF1 gene is involved in the blue‐light response and salt tolerance

Light and abiotic stress both strongly modulate plant growth and development. However, the effect of light‐responsive factors on growth and abiotic stress responses in wheat (Triticum aestivum) is unknown. G–box binding factors (GBFs) are blue light‐specific components, but their function in abiotic stress responses has not been studied. Here we identified a wheat GBF1 gene that mediated both the blue light‐ and abiotic stress‐responsive signaling pathways. TaGBF1 was inducible by blue light, salt and exposure to abscisic acid (ABA). TaGBF1 interacted with a G–box light‐responsive element in vitro and promoted a blue‐light response in wheat and Aradidopsis thaliana. Both TaGBF1 over‐expression in wheat and its heterologous expression in A. thaliana heighten sensitivity to salinity and ABA, but its knockdown in wheat conferred resistance to high salinity and ABA. The expression of AtABI5, a key component of the ABA signaling pathway in A. thaliana, and its homolog Wabi5 in wheat was increased by transgenic expression of TaGBF1. The hypersensitivity to salt and ABA caused by TaGBF1 was not observed in the abi5 mutant background, showing that ABI5 is the mediator in TaGBF1‐induced abiotic stress responses. However, the hypersensitivity to salt conferred by TaGBF1 is not dependent on light. This suggests that TaGBF1 is a common component of blue light‐ and abiotic stress‐responsive signaling pathways.     

RPW8 promoter is involved in pathogen‐And stress‐inducible expression from Vitis pseudoreticulata

Based on previous cloning of VpRPW8‐e, we obtained a 1,126 bp VpRPW8‐e promoter sequence in this study. A large number of TATA‐boxes, CAAT‐boxes, and other cis‐acting elements were predicted including light‐responsive elements, hormone‐responsive elements, stress‐responsive elements, and growth‐ and development‐associated elements within the promoter sequence. To further investigate the function of this promoter, we examined its activity in response to biotic and abiotic stress. The VpRPW8‐e promoter was strongly activated by Plasmopara viticola infection, and activation also occurred when the orientation of the promoter was reversed, although to a lesser extent. Deletion analysis showed that the ?1,126 to ?475 bp region of VpRPW8‐e promoter had high activity. A promoter fragment 5′ deleted to ?475 bp (P_?475) was activated in response to heat and cold stress, and even more strongly in response to Phytophthora capsici and salicylic acid (SA). Furthermore, Transgenic Nicotiana benthamiana were generated, VpRPW8‐e driven by P_?475 enhanced resistance to Ph. capsici in N. benthamiana. Based on these results, the ?475 bp region was deduced to be an indispensable part of the VpRPW8‐e promoter. VpRPW8‐e promoter is involved in pathogen‐ and stress‐inducible expression.     

Genetic and Environmental Influences on Body‐Fat Measures among African‐American Twins

Objective: To investigate the genetic and environmental influences on body‐fat measures including waist circumference (WC), waist‐to‐hip ratio (WHR), and body mass index (BMI) among African‐American men and women. Research Methods and Procedures: Measurements were taken as part of the Carolina African American Twin Study of Aging. This sample currently comprises 146 same‐sex African‐American twins with an average age of 50 years (range, 22 to 88 years). This analysis included 26 monozygotic and 29 dizygotic men and 45 monozygotic and 46 dizygotic women. Maximum likelihood quantitative genetic analysis was used. Results: In men, additive genetic effects accounted for 77% of the variance in WC, 59% in WHR, and 89% in BMI. In women, additive genetic effects accounted for 76% of the variance in WC, 56% in WHR, and 73% in BMI. The remaining variance in both men and women was attributed to unique environmental effects (WC, 21%; WHR, 36%; BMI, 11% in men and WC, 22%; WHR, 38%; BMI, 27% in women) and age (WC, 2%; WHR, 5% in men and WC, 2%; WHR, 6% in women). When BMI was controlled in the analysis of WC and WHR, it accounted for a portion of the genetic and environmental variance in WHR and over one‐half of the genetic and environmental variance in WC. Discussion: There are both genetic and environmental influences on WC, WHR, and BMI, and independent of BMI, there are genetic and environmental effects on WC and WHR among both genders. The results from this African‐American twin sample are similar to findings among white twin samples.