A molecular mechanism that confines the activity pattern of miR165 in Arabidopsis leaf primordia

In Arabidopsis leaf primordia, the expression of HD‐Zip III, which promotes tissue differentiation on the adaxial side of the leaf primordia, is repressed by miRNA165/166 (miR165/166). Small RNAs, including miRNAs, can move from cell to cell. In this study, HD‐Zip III expression was strikingly repressed by miR165/166 in the epidermis and parenchyma cells on the abaxial side of the leaf primordia compared with those on the adaxial side. We also found that the MIR165A locus, which was expressed in the abaxial epidermis, was sufficient to establish the rigid repression pattern of HD‐Zip III expression in the leaf primordia. Ectopic expression analyses of MIR165A showed that the abaxial‐biased miR165 activity in the leaf primordia was formed neither by a polarized distribution of factors affecting miR165 activity nor by a physical boundary inhibiting the cell‐to‐cell movement of miRNA between the adaxial and abaxial sides. We revealed that cis‐acting factors, including the promoter, backbone, and mature miRNA sequence of MIR165A, are necessary for the abaxial‐biased activity of miR165 in the leaf primordia. We also found that the abaxial‐determining genes YABBYs are trans‐acting factors that are necessary for the miR165 activity pattern, resulting in the rigid determination of the adaxial–abaxial boundary in leaf primordia. Thus, we proposed a molecular mechanism in which the abaxial‐biased patterning of miR165 activity is confined.     

PHI-1 induced enhancement of myosin phosphorylation in chicken smooth muscle

Herein, we provide evidence that in chicken smooth muscle, G-protein stimulation by a Rho-kinase pathway leads to an increase in myosin light chain phosphorylation. Additionally, G-protein stimulation did not increase MYPT1 phosphorylation at Thr695 or Thr850, and CPI-17, was not expressed in chicken smooth muscle. However, PHI-1 was present in chicken smooth muscle tissues. Both agonist and GTP(gamma)S stimulation result in an increase in PHI-1 phosphorylation, which is inhibited by inhibitors to both Rho-kinase (Y-27632) and (PKC) GF109203x. These data suggest that PHI-1 may act as a CPI-17 analog in chicken smooth muscle and inhibit myosin phosphatase activity during G-protein stimulation to produce Ca2+ sensitization.     

An Overview of a Wide Range of Functions of ZnT and Zip Zinc Transporters in the Secretory Pathway

Zinc plays essential roles in the early secretory pathway for a number of secretory, membrane-bound, and endosome/lysosome-resident enzymes. It enables the enzymes to fold properly and become functional, by binding as a structural or catalytic component. Moreover, zinc secreted from the secretory vesicles/granules into the extracellular space has a pivotal role as a signaling molecule for various physiological functions. Zinc transporters of the Slc30a/ZnT and Slc39a/Zip families play crucial roles in these functions, mediating zinc influx to and efflux from the lumen of the secretory pathway, constitutively or in a cell-specific manner. This paper reviews current knowledge of the ways these two zinc transporters perform these tasks by manipulating zinc homeostasis in the secretory pathway. Recent questions concerning zinc released into the cytoplasm from the secretory pathway, which then functions as an intracellular signaling molecule, are also briefly reviewed, emphasizing zinc transporter functions.     

Biophysical properties and finger print of Boswellia Sp. Burseraceae

For the first time a finger print analysis via high-performance thin layer chromatography (HPTLC) of Boswellia Sp. Burseraceae was accomplished. A preliminary investigation of the Boswellia Sp. Burseraceae displayed the presence of chemical constituents that could be involved in the production of innovative pharmaceuticals for an array of antiviral, anticancer, and antibacterial uses. Moreover, the finger print analysis would deem useful for establishing HPTLC standardization for natural and herbal photochemical constituents.     

Molecular mechanisms of non‐transferrin‐bound and transferring‐bound iron uptake in primary hippocampal neurons

The molecular mechanisms of iron trafficking in neurons have not been elucidated. In this study, we characterized the expression and localization of ferrous iron transporters Zip8, Zip14 and divalent metal transporter 1 (DMT1), and ferrireductases Steap2 and stromal cell‐derived receptor 2 in primary rat hippocampal neurons. Steap2 and Zip8 partially co‐localize, indicating these two proteins may function in Fe³⁺ reduction prior to Fe²⁺ permeation. Zip8, DMT1, and Steap2 co‐localize with the transferrin receptor/transferrin complex, suggesting they may be involved in transferrin receptor/transferrin‐mediated iron assimilation. In brain interstitial fluid, transferring‐bound iron (TBI) and non‐transferrin‐bound iron (NTBI) exist as potential iron sources. Primary hippocampal neurons exhibit significant iron uptake from TBI (Transferrin‐⁵⁹Fe³⁺) and NTBI, whether presented as ⁵⁹Fe²⁺‐citrate or ⁵⁹Fe³⁺‐citrate; reductase‐independent ⁵⁹Fe²⁺ uptake was the most efficient uptake pathway of the three. Kinetic analysis of Zn²⁺ inhibition of Fe²⁺ uptake indicated that DMT1 plays only a minor role in the uptake of NTBI. In contrast, localization and knockdown data indicate that Zip8 makes a major contribution. Data suggest also that cell accumulation of ⁵⁹Fe from TBI relies at least in part on an endocytosis‐independent pathway. These data suggest that Zip8 and Steap2 play a major role in iron accumulation from NTBI and TBI by hippocampal neurons.

     

Nramp1 and Other Transporters Involved in Metal Withholding during Infection

During the course of infection, many natural defenses are set up along the boundaries of the host-pathogen interface. Key among these is the host response to withhold metals to restrict the growth of invading microbes. This simple act of nutritional warfare, starving the invader of an essential element, is an effective means of limiting infection. The physiology of metal withholding is often referred to as “nutritional immunity,” and the mechanisms of metal transport that contribute to this host response are the focus of this review.     

木薯MeHB2转录因子的克隆与表达分析

该研究以木薯(Manihot esculenta Crantz)Ku50为实验材料,采用RT-PCR方法从叶片中克隆了1个HD-Zip基因MeHB2。MeHB2基因含有882bp的开放阅读框,编码293个氨基酸。蛋白质保守结构预测显示,MeHB2编码的蛋白含有Homeodomain、Leu zipper和HD-Zip_N等结构域,属于HD-Zip II成员。进化树分析表明,MeHB2与麻疯树、杨树和杞柳中同源基因的亲缘关系较近。实时荧光定量PCR分析表明,低温胁迫、渗透胁迫、ABA和H2O2均可诱导MeHB2基因的表达,而盐胁迫抑制其表达。此外,MeHB2的表达量还受到遮荫胁迫的诱导。研究表明,MeHB2在木薯非生物逆境调控中扮演重要角色。