Advanced Materials Research Vol. 796

Abstract: Larval silk/cement proteins from a caddisfly, Stenopsyche marmorata, were isolated as a protein mixture of Smsp-1, 2, 3 and 4. Smsp-1 is a giant phosphorylated protein, which occupies ca. 45%-mass of the silk gland content, and composed of a long-range periodic amino acid sequences, involving 8 kinds of characteristic segments. The silk protein film was prepared and drawn in water up to 9-folds of the initial axis length, then the drawn film was subjected to polarized FT-IR and WAXD. The results implied that the Smsp-1 backbone adopts two different conformations, one of which was the β-turn-like conformers. The molecular mechanic studies were separately performed to evaluate the solid-state chain structures of the hydrophobic/Pro-rich segments 3 and 4, which are enriched in the primary sequence of Smsp-1, and the results were coincident with those from the vibration spectra and WAXD. The molecular dynamic (MD) studies were also carried out in order to estimate their preferred chain conformations in a solution state. The MD trajectory suggests that the segments 3 and 4 tend to adopt a turn-like conformation, which is a potential precursor of the β-turn-like conformers. In conclusion, the underwater silk proteins have a fiber-forming mechanism, which is substantially different from a silkworm, Bombyx mori.

Abstract: Three-dimensional (3D) mesoporous bioactive glass (MBG) scaffolds were obtained by using the demineralized bone matrix (DBM) and P123 as co-templates through a dip-coating method followed by evaporation induced self-assembly (EISA) process. 3D mesoporous bioactive glass-silk fibroin (MBG/SF) composite scaffolds were prepared by immersing MBG scaffolds into SF solutions with different concentration. Transmission electron microscopy (TEM), field mission scanning electron microscope (FESEM), fourier transform infrared spectroscopy (FT-IR) and wide angle X-ray diffraction (WA-XRD) were used to analyze the inner pore structures, pore sizes, morphologies and composition of the scaffolds. The in vitro bioactivity of the scaffolds was evaluated by soaking in simulated body fluid (SBF). The results showed that the MBG and MBG/SF composite scaffolds with the interconnected macroporous network and mesoporous walls could be obtained by this method. In addition, both the MBG scaffolds and the MBG/SF composite scaffolds have excellent apatite-forming bioactivity. Therefore, this method provides a simple way to prepare scaffolds for bone tissue engineering.

Abstract: Bombyx mori pheromone-Binding Protein 1 (BmPBP1) in male moth antennae is a class of Odorant-Binding Proteins (OBPs), it can bind with the specific sex pheromone from female moth, thus initiates the males behaviors like seeking and mating, etc. It has been found that sex pheromone-binding protein 1 is differentially expressed in the antenna of male and female silkworm moths, however, the molecular mechanism of different PBP1 expression and its role in the information transmission are unclear. In this study, we successfully generated the BmPBP1 polyclonal antibody and used it to detect BmPBP1 expression in the silkworm moth antenna. Thus this work is helpful for further studies on the function of BmPBP1 in the information communication between male and female moths.

Abstract: In order to study eri-silkworm Cordyceps militaris culture condition and the amino acid composition features in different parts of it, this experiment optimized eri-silkworm Cordyceps militaris artificial culture conditions, and determined the amino acid composition in different parts. The results showed that the inoculated eri-silkworm Cordyceps militaris which was kept at low temperature (18 ° C) and seventeen dark days grew well and began to use natural light in the eighteenth day with humidity 85%, temperature 21 ° C, which could induce the germination of the sporophore. The artificial cultivation period was about 40 days. Amino acid test shows that its sporophore and stroma are rich in 17 kinds of amino acids, including 7 kinds of essential amino acids. The higher levels of amino acids in its sporophore are lysine 15.28%, glutamate 15.05% and aspartate 7.55%. The higher levels of the amino acids in the stroma are glycine 16.11%, lysine 9.16% and glutamate 8.30%. The results indicate that eri-silkworm Cordyceps militaris can be artificially cultured. As there are differences of amino acid composition in different parts of eri-silkworm Cordyceps militaris, this study lays the foundation for its large-scale cultivation and the exploitation of its amino acid nutrition.

Abstract: JAK-STAT signaling pathway shared by a variety of cytokines was discovered in recent years. It plays an important role in growth and development, cell apoptosis and immune response. In general, activated STAT dimer binds to a palindromic sequence (TTCN2-4GAA) located at the upstream promoter region to activate gene transcription. Some signal pathways including Toll and Imd in silkworm Bombyx mori, a model of Lepidopteran insect, have been well studied. However, little is known regarding JAK-STAT signal pathway. In the present study, the genes regulated by JAK-STAT signal pathway were predicted by bioinformatics analysis. 1000bp of upstream promoter sequence of the all predicted genes were downloaded from the silkworm genome database, and the STAT binding sequence TTCN2-4GAA were searched by scanning the promoter sequences, the results showed that 1 to 6 the target sequences could be found in the upstream promoter sequences of 9293 genes coding7271 non-redundant proteins. Go annotation results showed that these proteins were involved to cellular component, molecular function and biological process, suggesting JAK-STAT pathway play an important role in many way. More than 50% genes related to binding, about 40% genes related to cellular process, metabolic process and catalytic activity in the targeting genes. It is considered that JAK-STAT play a role in immune response.1-4 STAT binding sequences could be detected in promoter region of some genes related to anti-viral factors, cellular immune effector, and small antimicrobial peptide including defensin, attacin, moricin and gloverin3, implying that the expression of some anti-viral factors, cellular immune effectors and antimicrobial peptides related to antiviral activity might be regulated by JAK-STAT signal pathway.

Abstract: The succinate sehydrogenase (SDH) encoded by nuclear genome is a conjugating enzyme in the inner mitochondrial membrane. It is a junction for oxidative phosphorylation and the electron transport chain.As a part of complex II on the inner mt membranes, the SDH consists of four subunit proteins (A to D). We searched the genome sequence database of Bombyx mori with the Drosophila melanogaste and Nasonia vitripennis SDH by tBlastn and determined the structure of all putative B. mori genes of sdh by DNAMAN. The main results are as follows: The SdhAgene of B. mori contains 13 exons. The lengths of its cDNA is 2 880 bp at least. The SdhB gene of B. mori contains 1 exon only. The lengths of cDNA is 2 847 bp at least. The SdhC gene contains 4 exons. The lengths of cDNA is 714 bp at least. The SdhD gene contains 4 exons, too. The lenghts of cDNA is 1 976 bp at least.

Abstract: Bombyx mori cell line (BmN) comes from Bombyx mori ovary cell subculture. In order to study the change of several genes transcription in the process of Bombyx mori ovary cells primary culture and subculture, we used Bombyx mori ovary organizations and BmN cell lines as research materials, used Real Time fluorescent quantitative RT-PCR to detect cyclin gene family (CyclinA, CyclinB, CyclinB3, CyclinE, CyclinL1), p53 and Telomerase genes transcription level in the ovary and BmN cell lines, and took Actin3 gene as reference to dispose the results. The results showed that in the Bombyx mori BmN cell lines the expression of CyclinA, CyclinB, CyclinB3, CyclinE, CyclinL1 and Telomerase genes were higher than those in the ovary. The expression of CyclinB in the BmN was more then 3.8 which was 76 times higher than that in the ovary; The expression of p53 gene in the BmN cell was lower than that in the ovary; The expression of Telomerase gene in the BmN cell was higher than that in the ovary. The results accumulated a reliable data for further study on the the role of cyclin gene family, p53 gene, and Telomerase gene in the process of Bombyx mori ovarian carcinoma.

Abstract: As a natural protein polymer, Bombyx mori silk fibroin (SF) has superior characteristics such as excellent mechanical properties, biocompatibility and biodegradation which make SF to be a potential candidate in the field of biomaterials. It has been reported that the mineralized SF can be used for bone repair and regeneration in the bone tissue engineering. In order to map out the growth process of hydroxyapatite (HAp) induced by SF in the mineralized buffer solution, the co-solution of SF and supersaturated simulated body fluid (1.5 SBF) was incubated at 37.2 °C for 7 days and observed by using TEM, DSC, DTA and TGA in this study. The TEM results indicated that nanoscale crystal nuclei were found along the surface of SF in the initial stage of mineralization and finally these crystals aggregated into three-dimensional network. DSC and DTA results showed that the thermal stability of HAp/SF was greatly improved by increasing incubation duration and that the phase transition of HAp occurred from metastable state to steady state. TGA results suggested the organic content of HAp/SF complex was about 21% which was similar to the natural bone.

Abstract: Hippo kinase cascade shared by a variety of multicellular animals is appreciated as a signaling pathway which aims to inhibit the growth of cells and it is very conservative during evolution. Recent studies have confirmed that the Hippo signal pathway functions in cancer, tissue regeneration as well as stem cell regulation. The silkworm Bombyx mori is a model of Lepidopteran insect, little is known regarding genes related to Hippo kinase cascade. In the present study, the sequences of major genes related to Hippo pathway are obtained successfully in silkworm, B. mori, by in silico cloning or RT-PCR, including BmHop, BmSav, BmMats, BmWts and BmYki. The deduced amino acid sequences of the genes were aligned with those of other species, although the sequence identities of these proteins from different species were not high, the conserved domains were prominent, suggesting that the roles of Hippo pathway in the silkworm are similar to those in other species. These results has laid an important foundation for the further understanding and clarifying the function of the Hippo signaling pathway in silkworm.