Overexpression of a novel chrysanthemum Cys2/His2-type zinc finger protein gene DgZFP3 confers drought tolerance in tobacco

A drought stress-responsive Cys2/His2-type zinc finger protein gene DgZFP3 was previously isolated (Liu et al., Afr J Biotechnol 11:7781–7788, 2012b) from chrysanthemum. To assess roles of DgZFP3 in plant drought stress responses, we performed gain-of-function experiment. The DgZFP3-overexpression tobacco plants showed significant drought tolerance over the wild type (WT). The transgenic lines exhibited less accumulation of H₂O₂ under drought stress, more accumulation of proline and greater activities of peroxidase (POD) and superoxide dismutase than the WT under both control conditions and drought stress. In addition, there was greater up-regulation of the ROS-related enzyme genes (NtSOD and NtPOD) and stress-related genes (NtLEA5 and NtDREB) in transgenic lines under normal or drought conditons. Thus DgZFP3 probably plays a positive regulatory role in drought stress response and has the potential to be utilized in transgenic breeding to improve drought stress tolerance in plants.     

Preliminary Study on Effects of Glacial Retreat on the Dominant Glacial Snow Bacteria in Laohugou Glacier No. 12

One impact of climate change is the rapid shrinking of glaciers, resulting in microorganisms deposited into glacial snow or ice being exposed to new environments such as glacier foreland. A pyrosequencing analysis based on the bacterial 16S rRNA gene showed that bacterial diversity was the highest in proglacial soil, followed by that of glacial snow in ablation zone, then by that of glacial snow in the accumulation area, finally by that of glacial snow in glacier terminus, with the combination of Chao1, ACE, Shannon and Simpson analysis. Eighteen phyla were detected from the 7 samples, but mainly composed of Proteobacteria, Actinobacteria and Bacteroidetes. Flavobacterium, Massilia, Pedobacter, Polaromonas were more abundant in glacial snow samples than in glacial soil sample. Massilia was rarely reported in other environments, implying the necessity for its conservation under scenarios of glacier and snowpack loss induced by climate change.     

The E3 Ligase AtRDUF1 Positively Regulates Salt Stress Responses in Arabidopsis thaliana

Ubiquitination is an important post-translational protein modification that is known to play critical roles in diverse biological processes in eukaryotes. The RING E3 ligases function in ubiquitination pathways, and are involved in a large diversity of physiological processes in higher plants. The RING domain-containing E3 ligase AtRDUF1 was previously identified as a positive regulator of ABA-mediated dehydration stress response in Arabidopsis. In this study, we report that AtRDUF1 is involved in plant responses to salt stress. AtRDUF1 expression is upregulated by salt treatment. Overexpression of AtRDUF1 in Arabidopsis results in an insensitivity to salt and osmotic stresses during germination and seedling growth. A double knock-out mutant of AtRDUF1 and its close homolog AtRDUF2 (atrduf1atrduf2) was hypersensitive to salt treatment. The expression levels of the stress-response genes RD29B, RD22, and KIN1 are more sensitive to salt treatment in AtRDUF1 overexpression plants. In summary, our data show that AtRDUF1 positively regulates responses to salt stress in Arabidopsis.     

Isolation and Characterization of a Novel Endoglucanase from a Bursaphelenchus xylophilus Metagenomic Library

A novel gene (designated as cen219) encoding endoglucanase was isolated from a Bursaphelenchus xylophilus metagenomic library by functional screening. Sequence analysis revealed that cen219 encoded a protein of 367 amino acids. SDS-PAGE analysis of purified endoglucanase suggested that Cen219 was a monomeric enzyme with a molecular mass of 40 kDa. The optimum temperature and pH for endoglucanase activity of Cen219 was separately 50°C and 6.0. It was stable from 30 to 50°C, and from pH 4.0 to 7.0. The activity was significantly enhanced by Mn²⁺ and dramatically reduced by detergent SDS and metals Fe³⁺, Cu²⁺ or Hg²⁺. The enzyme hydrolyzed a wide range of β-1, 3-, and β-1, 4-linked polysaccharides, with varying activities. Activities towards microcrystalline cellulose and filter paper were relatively high, while the highest activity was towards oat gum. The K_m and V_max of Cen219 towards CMC was 17.37 mg/ml and 333.33 U/mg, respectively. The findings have an insight into understanding the molecular basis of host–parasite interactions in B. xylophilus species. The properties also make Cen219 an interesting enzyme for biotechnological application.     

The role of cotyledons in the establishment of Suaeda physophora seedlings

The role of cotyledons in seedling establishment of the euhalophyte Suaeda physophora under non-saline and saline conditions (addition of 1 mM or 400 mM NaCl) was investigated. Survival and fresh and dry weights were greater for seedlings grown in the light (12-h light/12-h dark) than in the dark (24-h dark). The shading of cotyledons tended to decrease shoot height, shoot organic dry weight, number of leaves, and survival of seedlings regardless of NaCl treatment, but the effect of cotyledon shading was greater with 400 mM NaCl. Concentrations of Na⁺ were higher in cotyledons than in leaves, regardless of NaCl treatment. The K⁺/Na⁺ ratio was lower in cotyledons than in leaves for seedlings treated with 1 mM NaCl but not for seedlings treated with 400 mM NaCl. Addition of 400 mM NaCl decreased oxygen production in cotyledons but especially in leaves. These results are consistent with the hypothesis that, by generating oxygen via photosynthesis and by compartmentalizing Na⁺, cotyledons are crucial for the establishment of S. physophora seedlings in saline environments.     

(−)-Epicatechin mitigates radiation-induced intestinal injury and promotes intestinal regeneration via suppressing oxidative stress

Abstract

The high radiosensitivity of the intestinal epithelium limits the survival of victims by nuclear accidents or terrorism and limits effective radiotherapy against abdominal malignancies. Recently, we reported that (?)-epicatechin (EC) modulates oxidative stress and exerts neuroprotection. Here, we investigate the protective effects of EC against intestinal damage induced by radiation. The established model is acute moderate but reversible intestinal injury damage. We also set up the injured model of “minigut” ex vivo, which mimic the process of intestinal regeneration in vivo. We found that EC can repress oxidative stress by regulating SOD and MDA levels in serum and intestine tissue. Correspondingly, EC can decrease apoptosis of crypt cells in Lgr5-EGFP-IRES-creERT2 mice after radiation. Further studies demonstrated that EC can promote Nrf2 translocation from cytoplasm to nuclear and then activate the expression of HO1 and NQO1. Interestingly, EC can enhance the activity of intestine stem cells labelled by Lgr5 and promote intestinal epithelium regeneration determined by HE and immunofluorescence staining in vivo and in vitro. We also found that EC can activate the Wnt/β-catenin signal pathway confirmed by TCF/LEF luciferase reporter assay. Together, EC can provide the protective effect on intestine and promote intestinal regeneration after radiation through Nrf2 and Wnt/β-catenin signal pathway.     

水稻亚种间杂种F1半不育小孢子发生的细胞学观察

利用石蜡切片和染色体压片法对水稻亚种间半不育杂种F1及其亲本的小孢子母细胞减数分裂过程进行细胞学观察.结果显示:亲本及杂种F1的花药壁发育正常,但部分F1的小孢子母细胞减数分裂异常,形成不均等的二分体和异常的四分体;其染色体在中期Ⅰ分散在赤道板两旁或远离赤道板,形成单价体;在后期Ⅰ和后期Ⅱ产生大量落后染色体或染色体桥.研究表明,部分花粉母细胞减数分裂中期和后期染色体行为异常可能是造成杂种F1花粉半不育的主要原因.