No abstract

Aspartic proteases are a class of proteolytic enzymes with conserved aspartate residues, which are implicated in protein processing, maturation, and degradation. Compared with yeast and animals, plants possess a larger aspartic protease family. However, little is known about most of these enzymes. Here, we characterized two Arabidopsis (Arabidopsis thaliana) putative glycosylphosphatidylinositol (GPI)-anchored aspartic protease genes, A36 and A39, which are highly expressed in pollen and pollen tubes. a36 and a36 a39 mutants display significantly reduced pollen activity. Transmission electron microscopy and terminaldeoxynucleotidyl transferase-mediated nick end labeling assays further revealed that the unviable pollen in a36 a39 may undergo unanticipated apoptosis-like programmed cell death. The degeneration of female gametes also occurred in a36 a39. Aniline Blue staining, scanning electron microscopy, and semi in vitro guidance assays indicated that the micropylar guidance of pollen tubes is significantly compromised in a36 a39. A36 and A39 that were fused with green fluorescent protein are localized to the plasma membrane and display punctate cytosolic localization and colocalize with the GPI-anchored protein COBRA-LIKE10. Furthermore, in a36 a39, the abundance of highly methylesterified homogalacturonans and xyloglucans was increased significantly in the apical pollen tube wall. These results indicate that A36 and A39, two putative GPI-anchored aspartic proteases, play important roles in plant reproduction in Arabidopsis.

Ingo Fischer opened a general discussion of the paper by Anne Zehnacker: You also presented data on the structure of the ionic dipeptide and discuss the relative stability of the isomers in terms of the CH-p and NH-p bonds in the ion. But in the ion you also have ion-multipole interactions. Can you comment on their role for the structure and stability of the dipeptide isomers? Anne Zehnacker-Rentien responded: Actually, the CH and NH p-bonds disappear in the ionic "folded-extended" structure. Indeed, most of the charge is borne by the extended aromatic ring. Therefore, the interaction between the charged benzene ring and the NH becomes repulsive. This is why the extended ring undergoes a rotation upon ionisation, to favour an interaction between CO and the aromatic ring. However, I agree that this interaction is probably more of a dipole/charge interaction than a COp interaction. Ingo Fischer added: You point out that the NH-p bond is weaker in the c-LL isomer than in the c-LD isomer, while for the CH-p bond you observe the opposite trend. Do you have a simple picture that explains this result? Anne Zehnacker-Rentien replied: In general, steric constraints due to the cyclic nature of the dipeptide add to chirality effects and make these effects more prominent. This is the case for example for 1-amino-2-indanol in which the (R,S) and (R,R) diastereomers show much more structural differences than linear 1,2 amino alcohols. 1 In the cyclo Tyr-Tyr studied here, the cyclic nature of the peptide backbone is also responsible for the differences in interactions. Because of the different position of the extended aromatic ring in the "folded/extended" geometry of the two diastereomers (axial for L and equatorial for D), the CH-p

No abstract

SnS has potential technical applications, but many of its properties are still not well studied. In this work, the structural, thermodynamic, elastic, and electronic properties of α-SnS have been investigated by the plane wave pseudo-potential density functional theory with the framework of generalised gradient approximation. The calculated pressure-dependent lattice parameters agree well with the available experimental data. Our thermodynamic properties of α-SnS, including heat capacity C P , entropy S, and Gibbs free energy relation of -(G T - H 0 ) curves, show similar growth trends as the experimental data. At T = 298.15 K, our C P = 52.31 J/mol·K, S = 78.93 J/mol·K, and -(G T - H 0 ) = 12.03 J/mol all agree very well with experimental data C P = 48.77 J/mol·K and 49.25 J/mol·K, S = 76.78 J/mol·K, and -(G T - H 0 ) = 12.38 J/mol. The elastic constants, together with other elastic properties, are also computed. The anisotropy analyses indicate obvious elastic anisotropy for α-SnS along different symmetry planes and axes. Moreover, calculations demonstrate that α-SnS is an indirect gap semiconductor, and it transforms to semimetal with pressure increasing up to 10.2 GPa. Combined with the density of states, the characters of the band structure have been analysed in detail.

The structure and the techniques of carrousel oxidation ditch process on nitrogen and phosphor removal are introduced in this paper. The problems in running and their corresponding resolve are also pointed. At last, the author showed the up to date research improvement and the mainly future research direction.

With the rapid development of modern society and economy, environmental problems have become increasingly prominent, especially the city water environment worsening, exacerbating the shortage of water resources, affecting people's physical and mental health, which has become the serious restriction factor of sustainable development of the city. This paper mainly discuss from the introduction of city sewage treatment technology and methods.

The blockage damage to the movable target on the ground with the mode of deterring is an important aspect of research about the fragment warhead. The analytic method of damage power about the blockage warhead cluster with the three blockage districts, including districts of dense damage in close distance, sparse damage in middle distance and deterrence damage in wide distance, was raised to do the research on the designing method of blockage damage warhead and the evaluation of blockage damage effect. The lying and standing static effectiveness test of the blockage warhead were designed based on the special blockage damage character. The designing method of the blockage damage warhead and the analytic method of blockage power characteristic were proved to be scientific, and the researching is significant in project application.