HbBIN2 Functions in Plant Cold Stress Resistance through Modulation of HbICE1 Transcriptional Activity and ROS Homeostasis in Hevea brasiliensis.

Cold stress poses significant limitations on the growth, latex yield, and ecological distribution of rubber trees (Hevea brasiliensis). The GSK3-like kinase plays a significant role in helping plants adapt to different biotic and abiotic stresses. However, the functions of GSK3-like kinase BR-INSENSITIVE 2 (BIN2) in Hevea brasiliensis remain elusive. Here, we identified HbBIN2s of Hevea brasiliensis and deciphered their roles in cold stress resistance. The transcript levels of HbBIN2s are upregulated by cold stress. In addition, HbBIN2s are present in both the nucleus and cytoplasm and have the ability to interact with the INDUCER OF CBF EXPRESSION1(HbICE1) transcription factor, a central component in cold signaling. HbBIN2 overexpression in Arabidopsis displays decreased tolerance to chilling stress with a lower survival rate and proline content but a higher level of electrolyte leakage (EL) and malondialdehyde (MDA) than wild type under cold stress. Meanwhile, HbBIN2 transgenic Arabidopsis treated with cold stress exhibits a significant increase in the accumulation of reactive oxygen species (ROS) and a decrease in the activity of antioxidant enzymes. Further investigation reveals that HbBIN2 inhibits the transcriptional activity of HbICE1, thereby attenuating the expression of C-REPEAT BINDING FACTOR (HbCBF1). Consistent with this, overexpression of HbBIN2 represses the expression of CBF pathway cold-regulated genes under cold stress. In conclusion, our findings indicate that HbBIN2 functions as a suppressor of cold stress resistance by modulating HbICE1 transcriptional activity and ROS homeostasis.

HbSnRK2.6 Functions in ABA-Regulated Cold Stress Response by Promoting HbICE2 Transcriptional Activity in Hevea brasiliensis.

Low temperature remarkably limits rubber tree (Hevea brasiliensis Muell. Arg.) growth, latex production, and geographical distribution, but the underlying mechanisms of Hevea brasiliensis cold stress response remain elusive. Here, we identified HbSnRK2.6 as a key component in ABA signaling functions in phytohormone abscisic acid (ABA)-regulated cold stress response in Hevea brasiliensis. Exogenous application of ABA enhances Hevea brasiliensis cold tolerance. Cold-regulated (COR) genes in the CBF pathway are upregulated by ABA. Transcript levels of all five HbSnRK2.6 members are significantly induced by cold, while HbSnRK2.6A, HbSnRK2.6B, and HbSnRK2.6C can be further activated by ABA under cold conditions. Additionally, HbSnRK2.6s are localized in the cytoplasm and nucleus, and can physically interact with HbICE2, a crucial positive regulator in the cold signaling pathway. Overexpression of HbSnRK2.6A or HbSnRK2.6B in Arabidopsis extensively enhances plant responses to ABA and expression of COR genes, leading to increased cold stress tolerance. Furthermore, HbSnRK2.6A and HbSnRK2.6B can promote transcriptional activity of HbICE2, thus, increasing the expression of HbCBF1. Taken together, we demonstrate that HbSnRK2.6s are involved in ABA-regulated cold stress response in Hevea brasiliensis by regulating transcriptional activity of HbICE2.

Sulfenylation of ENOLASE2 facilitates H2O2-conferred freezing tolerance in Arabidopsis.

H2O2 affects the expression of genes that are involved in plant responses to diverse environmental stresses; however, the underlying mechanisms remain elusive. Here, we demonstrate that H2O2 enhances plant freezing tolerance through its effect on a protein product of low expression of osmotically responsive genes2 (LOS2). LOS2 is translated into a major product, cytosolic enolase2 (ENO2), and sometimes an alternative product, the transcription repressor c-Myc-binding protein (MBP-1). ENO2, but not MBP-1, promotes cold tolerance by binding the promoter of C-repeat/DRE binding factor1 (CBF1), a central transcription factor in plant cold signaling, thus activating its expression. Overexpression of CBF1 restores freezing sensitivity of a LOS2 loss-of-function mutant. Furthermore, cold-induced H2O2 increases nuclear import and transcriptional binding activity of ENO2 by sulfenylating cysteine 408 and thereby promotes its oligomerization. Collectively, our results illustrate how H2O2 activates plant cold responses by sulfenylating ENO2 and promoting its oligomerization, leading to enhanced nuclear translocation and transcriptional activation of CBF1.

Airflow behavior changes in upper airway caused by different head and neck positions: Comparison by computational fluid dynamics.

The feasibility of computational fluid dynamics (CFD) to evaluate airflow characteristics in different head and neck positions has not been established. This study compared the changes in volume and airflow behavior of the upper airway by CFD simulation to predict the influence of anatomical and physiological airway changes due to different head-neck positions on mechanical ventilation. One awake volunteer with no risk of difficult airway underwent computed tomography in neutral position, extension position (both head and neck extended), and sniffing position (head extended and neck flexed). Three-dimensional airway models of the upper airway were reconstructed. The total volume (V) and narrowest area (Amin) of the airway models were measured. CFD simulation with an Spalart-Allmaras model was performed to characterize airflow behavior in neutral, extension, and sniffing positions of closed-mouth and open-mouth ventilation. The comparison result for V was neutral

CETP polymorphisms confer genetic contribution to centenarians of Hainan, south of China.

OBJECTIVE: In this paper, we will discuss if the CETP polymorphism contributes to the centenarians in Hainan island. METHODS: We tested the TaqIB and I405V polymorphisms of CETP gene among 276 centenarians and 301 matched healthy individuals by AS-PCR and analyzed the data with SPSS software package (Version 19.0). RESULTS: Our data indicated that allele B1 and V have the significant differences between centenarians and healthy control groups with P < 0.001. Further analysis implied that genotypes B1B1 (P < 0.001, OR = 0.148, 95% CI = 0.095-0.230) and VV (P < 0.001 and OR = 0.353, 95% CI = 0.237-0.525) were significantly different between centenarians and matched controls. The combination of B and V, such as B1B1-II (P < 0.001, OR = 0.128, 95% CI = 0.049-0.329), B1B1-IV (P < 0.001, OR = 0.115, 95% CI = 0.056-0.237), B1B2-VV (P < 0.05, OR = 0.534, 95% CI = 0.310-0.920), and B2B2-VV (P < 0.001, OR = 0.198, 95% CI = 0.086-0.453) have significant differences between centenarians and matched healthy individuals from Hainan. CONCLUSION: Our results implied that allele B1B1 and VV, as well as the combination B1B1-II, B1B1-IV, B1B2-VV and B2B2-VV may contribute to the longevity in centenarians of Hainan, south of China.