高血压大鼠心脏和血管MAPK磷酸酶-1表达的改变及对平滑肌细胞增殖的影响

目的和方法：比较自发性高血压大鼠（SHR）和对照（WKY）大鼠心脏和主动脉丝裂素活化蛋白激酶磷酸酶－1（MKP－1）及细胞外信号调节激酶（ERK－1）的表达,并观察用磷酸钙共沉淀方法转染MKP－1基因对血管紧张素Ⅱ（Ang Ⅱ）刺激平滑肌细胞（VSMC）^3H－胸腺叫啶（^3H-TdR)掺入的影响,以探讨MKP－1在细胞增殖中的调节作用。结果：①与WKY大鼠相比,SHR心脏和主动脉MKP－1呈低表达,分别降低53％和45％（P均＜0．01）;而SHR心脏和主动脉ERK－1呈明显高表达（P均＜0．01）,SHR心脏和主动脉ERK－1与MKP－1蛋白比值明显高于WKY。②AngⅡ 10^-7mol/L刺激VSMC增殖较对照组增加257％（P＜0．01）,转染野生型MKP－1基因细胞可使AngⅡ刺激的^3H-TdR掺入较未转染的细胞降低63％（P＜0．05）,转染突变型MKP－1基因和转染空载体的VSMC对AngⅡ的刺激与单纯AngⅡ组相比无明显抑制作用（P＞0．05）。结论：SHR心血管组织中促增殖肥大的ERK－1表达较其失活的MKP－1占优势,并且MKP－1可显著抑制AngⅡ的VSMC增殖。     

Linking seed germination and plant height: a case study of a wetland community on the eastern Tibet Plateau

• Seed germination is the earliest trait expressed in a plant's life history, and it can directly affect the expression of post‐germination traits. Plant height is central to plant ecological strategies, because it is a major determinant of the ability of a species to compete for light. Thus, linking seed germination and plant height at the community level is very important to understanding plant fitness and community structure.
• Here, we tested storage condition and temperature requirements for germination of 31 species from a wetland plant community on the eastern Tibet Plateau and analysed correlation of germination traits with plant height in relation to storage condition.
• Germination percentage was positively related to plant height, and this relationship disappeared when seeds were incubated at a low temperature (i.e. 5 °C) or after they were stored under wet‐cold conditions. The response of seeds to dry+wet–cold storage was negatively related to plant height. Based on the scores of each species on the first two principal components derived from PCA, species were classified into two categories by hierarchical clustering, and there was a significant difference between germination and plant height of species in these two categories.
• These results suggest that the requirements for seed germination together with seasonal change in environmental conditions determine the window for germination and, in turn, plant growth season and resource utilisation and ultimately plant height.

     

Chronic restraint stress disturbs meiotic resumption through APC/C-mediated cyclin B1 excessive degradation in mouse oocytes

Psychological stress, which exerts detrimental effects on human reproduction, may compromise the meiotic competence of oocytes. Meiotic resumption, germinal vesicle breakdown (GVBD), is the first milestone to confer meiotic competence to oocytes. In the practice of assisted reproductive technology (ART), the timing for GVBD is associated with the rates of cleavage and blastocyst formation. However, whether chronic stress compromises oocyte competence by influencing GVBD and the underlying mechanisms are unclear. In the present study, a chronic restraint stress (CRS) mouse model was used to investigate the effects of stress on oocyte meiotic resumption, as well as the mechanisms. Following a 4-week chronic restraint stress in female mice, the percentage of abnormal bipolar spindles increased and indicated compromised oocyte competence in the CRS group. Furthermore, we identified a decreased percentage of GVBD and prolonged time of GVBD in the CRS mouse oocytes compared with the control group. CRS simultaneously reduced the expression of cyclin B1 (CCNB1), which represents a regulatory subunit of M-phase/mature promoting factor (MPF). However, MG132, an inhibitor of anaphase-promoting complex/cyclosome (APC/C), could rescue the prolonged time of GVBD and increase the expression level of CCNB1 of oocytes from the CRS mice. Collectively, our results demonstrated that stress disturbed meiotic resumption through APC/C-mediated CCNB1 degradation, thus providing a novel understanding for stress-related oocyte quality decline; moreover, it may provide a non-invasive approach to select high-quality gametes and novel targets for molecular therapy to treat stress-related female infertility.     

The olfactory subgenome and specific odor recognition in forest musk deer

Olfactory receptors (ORs) are encoded by OR genes. The OR genes in forest musk deer (Moschus berezovskii), which rely on olfaction for reproductive and social communication, are poorly understood. In this study, we analyzed the genome sequence of the forest musk deer to obtain its olfactory subgenome and compared it to other species. A total of 1378 OR‐related sequences were detected in the forest musk deer genome including 864 functional genes, 366 pseudogenes and 148 partial genes. These OR genes were classified into Class I and Class II and were further classified into 18 families and 244 subfamilies through sequence identity. Comparative analyses of the OR genes’ protein sequences in species from different orders (forest musk deer, human, mouse and dog) showed that 12 clusters were specific to forest musk deer. However, when compared to other Artiodactyl species (i.e. cattle, yak and pig) only two clusters were specific to forest musk deer. The odor identification potential of the OR genes in the forest musk deer was focused mainly on floral, woody, lemon, sweet and fatty odors. We also found that OR genes specific to forest musk deer were involved in the identification of spearmint and caraway. Our work is the first genome‐wide analysis of OR genes in forest musk deer. These findings will assist with better understanding the relationship between behavior and olfaction in the forest musk deer and the characteristics of the olfactory subgenome in Artiodactyl mammals.     

Blockade of JAK2 signaling produces immunomodulatory effect to preserve pancreatic homeostasis in severe acute pancreatitis

JAK/STAT plays an important role in cytokine signal transduction and it is potentially involved in the proinflammatory response during the early phase of severe acute pancreatitis (SAP). However, whether JAK2 activity is upregulated and whether JAK2 inhibition plays a role in the maintenance of pancreatic homeostasis during SAP is incompletely understood. Here we show that JAK2/STAT3 activity is highly elevated in SAP and blockade of JAK2 by AG-490 protects against SAP-induced pancreatic inflammation and injury. Gene expression and ELISA studies showed that JAK2 inhibition altered the cytokine profiles in both the circulation and pancreases. Further analysis revealed that JAK2 inhibition restored the level of cytokines critical for macrophage polarization towards M2 macrophage. Our findings suggest that pharmacological targeting at JAK2/STAT signalling may be an effective choice of therapeutic interventions against SAP.     

Protonation and electronic structure of 2,6-dichlorophenolindophenolate during reduction. A theoretical study including explicit solvent

Protonation in the two-electron/two-proton reduction processes of 2,6-dichlorophenolindophenolate (DCIP) is investigated combining density functional theory (DFT) and molecular dynamics (MD) methods. DCIP (anion), DCIP^?– (radical anion), and DCIP^2? (dianion) are considered, including the electronic structure analysis from the prospective of quantum theory of atoms and molecules (QTAIM). It is shown that oxygen on the indophenolate moiety and nitrogen are the first and/or the second proton acceptor sites and their energetic order depends on the total charge of the system. MD simulations of differently charged species interacting with the solvent molecules have been performed for methanol, water, and oxonium cation (H₃O⁺). Methanol and water molecules are found to form only hydrogen bonds with the solute irrespective of its charge. The calculated pK_a values show that the imino group of DCIPH^? is a weaker acid than water. While in the case of DCIP (and DCIP^?–) plus oxonium cation, proton transfer from the solvent to the solute was evidenced for both aforementioned acceptor sites. In addition, MD simulations of bulks containing 15 and 43 molecules of water around the DCIP molecule have been performed, revealing the formation of 2–4 hydrogen bonds.

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Graphical Abstract 2,6-Dichlorophenolindophenolate interacts with solvent molecules (water, oxonium cation and methanol). Hydrogen transfer and electronic structure are studied by DFT and molecular dynamics methods

     

Slow endocytosis of the LDL receptor-related protein 1B: implications for a novel cytoplasmic tail conformation

The LDL receptor-related protein 1B (LRP1B) is a putative tumor suppressor homologous to LRP1. Both LRP1 and LRP1B contain cytoplasmic tails with several potential endocytosis motifs. Although the positions of these endocytic motifs are similar in both receptors, LRP1B is internalized at a 15-fold slower rate than LRP1. To determine whether the slow endocytosis of LRP1B is due to the utilization of an endocytosis motif other than the YATL motif used by LRP1, we tested minireceptors with mutations in each of the five potential motifs in the LRP1B tail. Only mutation of both NPXY motifs together abolished LRP1B endocytosis, suggesting that LRP1B can use either of these motifs for internalization. LRP1B contains a unique insertion of 33 amino acids not present in LRP1 that could lead to altered recognition of trafficking motifs. Surprisingly, deletion of this insertion had no effect on the endocytosis rate of LRP1B. However, replacing either half of the LRP1B tail with the corresponding LRP1 sequence markedly accelerated LRP1B endocytosis. From these data, we propose that both halves of the LRP1B cytoplasmic tail contribute to a unique global conformation, which results in less efficient recognition by endocytic adaptors and a slow endocytosis rate.