Effects of lead stress on the growth, physiology, and cellular structure of privet seedlings.

In this study, we investigated the effects of different lead (Pb) concentrations (0, 200, 600, 1000, 1400 mg kg-1 soil) on the growth, ion enrichment in the tissues, photosynthetic and physiological characteristics, and cellular structures of privet seedlings. We observed that with the increase in the concentrations of Pb, the growth of privet seedlings was restricted, and the level of Pb ion increased in the roots, stem, and leaves of the seedlings; however, most of the ions were concentrated in the roots. Moreover, a decreasing trend was observed for chlorophyll a, chlorophyll b, total chlorophyll, net photosynthesis (Pn), transpiration rate (Tr), stomatal conductance (Gs), sub-stomatal CO2 concentration (Ci), maximal photochemical efficiency (Fv/Fm), photochemical quenching (qP), and quantum efficiency of photosystem II (ΦPSII). In contrast, the carotene levels, minimum fluorescence (F0), and non-photochemical quenching (qN) showed an increasing trend. Under Pb stress, the chloroplasts were swollen and deformed, and the thylakoid lamellae were gradually expanded, resulting in separation from the cell wall and eventual shrinkage of the nucleus. Using multiple linear regression analysis, we found that the content of Pb in the leaves exerted the maximum effect on the seedling growth. We observed that the decrease in photosynthetic activation energy, increase in pressure because of the excess activation energy, and decrease in the transpiration rate could result in maximum effect on the photosynthetic abilities of the seedlings under Pb stress. Our results should help in better understanding of the effects of heavy metals on plants and in assessing their potential for use in bioremediation.

Reactivity and regioselectivity in Diels-Alder reactions of anion encapsulated fullerenes.

Encapsulation and surface chemical modification are methodologies to enhance the properties of fullerenes for various applications. Herein, density functional theory calculations are performed to study the Diels-Alder (DA) reactivity of anion encapsulated C60, including [X@C60]- (X = F, Cl, Br, or I), [S@C60]2-, and [N@C60]3-. Computational results reveal that encapsulated Cl-, Br-, I-, or S2- anions are located close to the center of the C60 molecule; however, encapsulated F- is displaced from the center. Encapsulated N3- bonds to the inner surface of the carbon cage, which leads to a negative charge transfer to the C60. In [N@C60]3-, C-C bonds near to the encapsulated N atom are more reactive. Our calculations reveal that encapsulated halogen or S anions decrease the DA reactivity because of the stronger closed-shell repulsion of the encapsulated anion. However, encapsulated N3- increases the DA reactivity. The higher distortion energy of the halogen- or S2--anion encapsulated C60 leads to lower reactivity of the 6-5 bond. Opposite regioselectivity of the DA reaction with [N@C60]3- is attributed to distortion energy of the cyclopentadiene (CPD) moiety. The asymmetrical transition state geometry leads to a lower distortion energy of the CPD moiety.

DNAzymes Dz13 target the c-jun possess antiviral activity against influenza A viruses.

The emergence of anti-influenza A virus drugs resistant strain highlights the need for more effective therapy. Our earlier study demonstrated that c-jun, a downstream molecule of JNK, might be important in viral infections and inflammatory responses. In the present study, we explored the function of DNAzymes Dz13 that target c-jun in influenza A virus infected mice. Dz13 displayed non-toxic side effects on A549 cells and BALB/c mice. Moreover, Dz13-treated mice had enhanced survival after influenza compared with untreated mice. Simultaneously, the pulmonary inflammatory responses and viral burden were decreased in Dz13 treated mice. Furthermore, proliferation levels of infection-induced CD4+ and CD8+ T cells were impaired. These data demonstrated that Dz13 could reduce viral replication and inflammatory response in vivo, suggesting that Dz13 may potentially be used to treat influenza A viral infection.

Theoretical Study on the Reactivity and Regioselectivity of the Diels-Alder Reaction of Fullerene: Effects of Charges and Encapsulated Lanthanum on the Bis-Functionalization of C70.

Bis-adducts of fullerenes are important for both material and biological science. The first added substituent greatly impacts the reactivity and regioselectivity of fullerene. What determines the bond reactivity and how to control the regioselectivity are two crucial questions in synthesizing bis-adduct of C70. Recently, an unexpected 12 o'clock isomer of anthracene bis-adduct of C70 was prepared with high yield by the Diels-Alder (DA) reaction although three possible isomers (12, 2, and 5 o'clock isomers) may be formed. In the current study, the beneath mechanism is systematically investigated by density functional theory methods. Moreover, effects of charges and encapsulated lanthanum atom on the regioselectivity are reported. The computational results successfully rationalize experimental observations by Venkata et al. A possible way to change the regioselectivity of DA reaction is put forward. The kinetical promotion effect of an encapsulated La atom on the 12 o'clock reaction is elucidated.

Plasma membrane-associated proline-rich extensin-like receptor kinase 4, a novel regulator of Ca signalling, is required for abscisic acid responses in Arabidopsis thaliana.

Plant roots respond to environmental stresses or the exogenous plant hormone abscisic acid (ABA) by undergoing marked physiological and morphological changes. We show here that PERK4, a gene that encodes a member of the Arabidopsis thaliana proline-rich extensin-like receptor kinase family, plays an important role in ABA responses. Mutation of PERK4 by T-DNA insertion decreased sensitivity to ABA with respect to seed germination, seedling growth and primary root tip growth. The effect on root growth was due to enhanced cell elongation rather than cell division. The cytosolic free calcium concentration and Ca(2+) channel currents were lower in perk4 root cells than in wild-type cells in the presence of ABA. Root growth was similar in wild-type and perk4 plants after the application of a Ca(2+) channel blocker. PERK4 localised to the plasma membrane, and was shown to be an ABA- and Ca(2+)-activated protein kinase. Our data suggest that the receptor-like kinase encoded by PERK4 functions at an early stage of ABA signalling to inhibit root cell elongation by perturbing Ca(2+) homeostasis.