Since a sluggish conversion reaction and shuttling of polysulfides have been barriers to high-performance Li–S batteries, it is particularly critical to establish nanostructured electrocatalysts with ...high specific surface area and electron conductivity, an excellent anchoring capability, and long-term durability. Herein, a robust binary synergistic MoS2/MXene heterostructure is proposed by the homogeneous growth of MoS2 on an MXene substrate. Due to the hierarchical structure and strong interfacial coupling effect, the binary synergistic MoS2/MXene heterostructure not only suppresses the restacking of MoS2 and MXene nanosheets but also provides abundant active sites to capture polysulfides and catalyze its conversion reaction. Typically, polysulfides are immobilized by MoS2 nanosheets; then, the anchored polysulfides are rapidly transferred from MoS2 to MXene via heterointerfaces. The MXene surface is endowed with abundant oxygen terminations, which accelerates the polysulfide conversion kinetics to a great extent. Therefore, the assembled Li–S battery delivers a reversible capacity of 981 mA h g–1 at 0.5 C after 300 cycles. Even at high rate of 5 C, capacity is still maintained at an excellent level of 408 mA h g–1 after 500 cycles with a Coulombic efficiency of 96.5%. Even more fascinating, at 0.2 C, the MoS2/MXene cathode can realize a high sulfur loading of 4.0 mg cm–2 and with capacities of 608 mA h g–1 over 500 cycles, which will promote the practical applications of Li–S batteries.
According to the statistics of Gisi181, the fungicides used for controlling cucumber downy mildew nationwide in 1996 accounted for about 10% of the total sales of agents against downy mildew. The ...sensitivity of 69 P. cubensis strains to cymoxanil was determined by in vitro leaf disc floating method recommended by FAO21f The third to fifth true leaves of healthy cucumber plants were collected and made into leaf discs with the diameter of 15 mm. The leaf discs were placed in culture dishes with the diameter of 90 mm, 10 leaf discs each dish, and soaked in 15 mL of different series of drug solutions with reverse side upward for 1 h. Each concentration was repeated three times, and those soaked in distilled water were used as control. According to the sensitivity distribution of P. cubensis to cymoxanil, the sensitivity baseline of P. cubensis to cymoxanil was calculated, and the resistance level of each strain was calculated. According to the classification standards of resistance types, P. cubensis with different resistance levels were divided into four types: sensitive type (S), resistance level "2 times; low-resistance type (LR), 2<resistance level" 10 times; medium-resistance type (MR), 10 gresistance level "100 times; high-resistance type (HR), resistance level>100.
The gene encoding sericin 1 (Ser1) of silkworm (Bombyx mori) is specifically expressed in the middle silk gland cells. To identify element involved in this transcription-dependent spatial ...restriction, truncation of the 5′ terminal from the sericin 1 (Ser1) promoter is studied in vivo. A 209bp DNA sequence upstream of the transcriptional start site (−586 to −378) is found to be responsible for promoting tissue-specific transcription. Analysis of this 209bp region by overlapping deletion studies showed that a 25bp region (−500 to −476) suppresses the ectopic expression of the Ser1 promoter. An unknown factor abundant in fat body nuclear extracts is shown to bind to this 25bp fragment. These results suggest that this 25bp region and the unknown factor are necessary for determining the tissue-specificity of the Ser1 promoter.
We have reported that several silkworm strains are permissive to intrahemocoelical infection of
Autographa californica nucleopolyhedrovirus (AcNPV), contrary to the general belief that AcNPV cannot ...infect silkworm. In the present study, we address whether the intrahemocoelical infection of AcNPV to the silkworm was an exceptional phenomenon, and the possible genetic basis underlying it. Wilder range test of 31 strains of silkworm
Bombyx mori for intrahemocoelical AcNPV infection led to the identification of 14 permissive strains and 17 nonpermissive strains, indicating that the intrahemocoelical infection of AcNPV to the silkworm was not a rare and isolated phenomenon. Productive infection was shown in permissive silkworms, by EGFP fluorescence in various tissues when expression of reporter gene controlled by a very late viral promoter
polh. The viral titer in larval hemolymph of permissive silkworms increased and maintained at a higher level hundredfold more than the initial amount of virus, indicating viral replication. A series of genetic cross experiments suggested the existence of only one dominant host anti-AcNPV gene or a set of genetically linked genes, which prevent AcNPV infection in nonpermissive silkworm strain Qingsong and are absent in permissive silkworm strain Haoyue.
To investigate the functions of signal peptide in protein secretion in the middle silk gland of silkworm Bombyx mori, a series of recombinant Autographa californica multiple nucleopolyhedroviruses ...containing enhanced green fluorescent protein (egfp) gene, led by sericin‐1 promoter and mutated signal peptide coding sequences, were constructed by region‐deletions or single amino acid residue deletions. The recombinant Autographa californica multiple nucleopolyhedroviruses were injected into the hemocoele of newly ecdysed fifth‐instar silkworm larvae. The expression and secretion of EGFP in the middle silk gland were examined by fluorescence microscopy and Western blot analysis. Results showed that even with a large part (up to 14 amino acid residues) of the ser‐1 signal peptide deleted, the expressed EGFP could still be secreted into the cavity of the silk gland. Western blot analysis showed that shortening of the signal peptide from the C‐terminal suppressed the maturation of pro‐EGFP to EGFP. When 8 amino acid residues were deleted from the C‐terminal of the signal peptide (mutant 13 aa), the secretion of EGFP was incomplete, implicating the importance of proper coupling of the h‐region and c‐region. The deletion of amino acid residue(s) in the h‐region did not affect the secretion of EGFP, indicating that the recognition of signal peptide by translocation machinery was mainly by a structural domain, but not by special amino acid residue(s). Furthermore, the deletion of Arg2 or replacement with Asp in the n‐region of the signal peptide did not influence secretion of EGFP, suggesting that a positive charge is not crucial.
In order to investigate the functional signal peptide of silkworm fibroin heavy chain (FibH) and the effect of N- and C-terminal parts of FibH on the secretion of FibH in vivo, N- and C-terminal ...segments of
fibh gene were fused with enhanced green fluorescent protein (EGFP) gene. The fused gene was then introduced into silkworm larvae and expressed in silk gland using recombinant AcMNPV (
Autographa californica multiple nuclear polyhedrosis virus) as vector. The fluorescence of EGFP was observed with fluorescence microscope. FibH-EGFP fusion proteins extracted from silk gland were analyzed by Western blot. Results showed that the two alpha helices within N-terminal 163 amino acid residues and the C-terminal 61 amino acid residues were not necessary for cleavage of signal peptide and secretion of the fusion protein into silk gland. Then the C-terminal 61 amino acid residues were substituted with a His-tag in the fusion protein to facilitate the purification. N-terminal sequencing of the purified protein showed that the signal cleavage site is between position 21 and 22 amino acid residues.
4-Nitroquinoline N-oxide (4-NQO) is a potent mutagen and carcinogen. To elucidate the cellular response to 4-NQO, we studied the transcriptional regulation of human proliferating cell nuclear antigen ...(hPCNA), an essential protein in DNA replication and repair, after 4-NQO treatment. We found that hPCNA promoter was dose-dependently transactivated by 4-NQO under the concentration of 2
μM via a previously reported p53-binding element located from −236 to −217 upstream of the transcription start site. Based on our western blot analysis, the phosphorylation of serine at the 15th residue (Ser15) of p53 was activated by 4-NQO, whereas the level of p53 in the cells did not change much. It was observed that Staurosporine, a Ser/Thr kinase inhibitor, blocked the Ser15 phosphorylation of p53 and the hPCNA promoter response to 4-NQO simultaneously, suggesting that Ser15 phosphorylated p53 was the 4-NQO-responsive hPCNA regulator. The
3H-thymidine deoxyribose (TdR) incorporation assay and the comet assay showed that DNA repair was triggered when DNA replication was inhibited after the treatment of 4-NQO, and the hPCNA transactivation seemed to contribute to DNA repair. Taken together, our data indicate that after 4-NQO treatment hPCNA is transactivated by Ser15 phosphorylated p53, and participate in DNA repair.
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