Comparison of the Hepatoprotective Effects of the Three Main Stilbenes from Mulberry Twigs.

The purpose of this study was to compare the hepatoprotective effects of Oxy (oxyresveratrol), Res (resveratrol), and MulA (mulberroside A) (80 mg/kg body weight/d, i.g.) on acute liver injury (ALI) induced by lipopolysaccharide (LPS)/d-galactosamine (d-GalN) in mice. After 7 h of LPS (50 µg/kg body weight, i.p.) and d-GalN (500 mg/kg body weight, i.p.) exposure, the activities of serum transaminases and antioxidant enzymes were determined. The expressions of the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) signal pathway, the nuclear factor-kappa B (NF-κB) signal pathway, and the mitogen-activated protein kinase (MAPK) signal pathway related proteins were evaluated by Western blot assays. Histopathological analysis was performed by hematoxylin-eosin (H&E) staining on the separated livers of mice. The results showed that treatment with Oxy, Res, and MulA could significantly decreases the levels of alanine transaminase (ALT) and aspartate transaminase (AST) ( P < 0.01). MulA was the most effective ingredient among the three, and the ALT and AST levels were reduced at 90.3 ± 1.3% and 93.9 ± 1.1% compared with the LPS/D-GalN treated group ( P < 0.01). Meanwhile, the stilbenes curbed the expression of inflammatory factors, NF-κB pathway activation, and MAPKs phosphorylation and upregulated antioxidant enzymes, Nrf2, NAD (P) H:quinone oxidoreductase (NQO1), and heme oxygenase-1 (HO-1) expression levels. Stilbenes might protect the ALI caused by LPS/d-GalN through inhibiting the negative effectiveness of oxidation stress and inflammation. The protective performance of MulA was better than those of Oxy and Res, and we hypothesize that it might be due to the mediation of the specific metabolic pathway of the MulA in vivo. All of these results implied that stilbenes in mulberry twigs might be promising as natural additives.

Expression pattern and tissue localization of the class B scavenger receptor BmSCRBQ4 in Bombyx mori.

Class B scavenger receptors (SR-Bs) are cell surface glycoproteins involved in various physiological processes in vivo, including the transport and metabolism of lipids, binding and phagocytosis of xenobiotics, and signaling. But little information is available about silkworm SR-Bs; it is necessary to study these SR-Bs for revealing their function. In this study, we cloned the full-length coding sequence of BmSCRBQ4, a SR-B gene from the silkworm Bombyx mori L. We found that the BmSCRBQ4 gene consists of nine exons and eight introns, with an open reading frame of 1371 bp encoding 456 amino acids. Gene expression studies determined that BmSCRBQ4 messenger RNA (mRNA) was expressed in unfertilized eggs, during embryonic development and throughout the majority of the larval period. Expression of mRNA was detected in the mid gut, middle silk gland, posterior silk gland, head, integumentum, fat body, testes and the ovaries of the larval B. mori Dazao strain, as well as in the silkworm cell lines BmN and BmE. Protein expression studies found BmSCRBQ4 protein was expressed only in the testes, fat body and middle silk gland of larvae, as well as in the silkworm cell lines BmN and BmE. The BmSCRBQ4 protein showed variability in banding patterns in different tissues and cells when analyzed by Western blotting. Immunohistochemical staining showed that the BmSCRBQ4 protein localizes to the constitutive membranes or cellular membranes of these tissues. These results indicated that BmSCRBQ4 gene may play some physiologically relevant roles at the cell surface in each tissue.

Combined effect of Cameo2 and CBP on the cellular uptake of lutein in the silkworm, Bombyx mori.

Formation of yellow-red color cocoons in the silkworm, Bombyx mori, occurs as the result of the selective delivery of carotenoids from the midgut to the silk gland via the hemolymph. This process of pigment transport is thought to be mediated by specific cellular carotenoids carrier proteins. Previous studies indicated that two proteins, Cameo2 and CBP, are associated with the selective transport of lutein from the midgut into the silk gland in Bombyx mori. However, the exact roles of Cameo2 and CBP during the uptake and transport of carotenoids are still unknown. In this study, we investigated the respective contributions of these two proteins to lutein and ß-carotene transport in Bombyx mori as well as commercial cell-line. We found that tissues, expressed both Cameo2 and CBP, accumulate lutein. Cells, co-expressed Cameo2 and CBP, absorb 2 fold more lutein (P<0.01) than any other transfected cells, and the rate of cellular uptake of lutein was concentration-dependent and reached saturation. From immunofluorescence staining, confocal microscopy observation and western blot analysis, Cameo2 was localized at the membrane and CBP was expressed in the cytosol. What's more, bimolecular fluorescence complementation analysis showed that these two proteins directly interacted at cellular level. Therefore, Cameo2 and CBP are necessarily expressed in midguts and silk glands for lutein uptake in Bombyx mori. Cameo2 and CBP, as the membrane protein and the cytosol protein, respectively, have the combined effect to facilitate the cellular uptake of lutein.

The UDP-glucosyltransferase multigene family in Bombyx mori.

BACKGROUND: Glucosidation plays a major role in the inactivation and excretion of a great variety of both endogenous and exogenous compounds. A class of UDP-glycosyltransferases (UGTs) is involved in this process. Insect UGTs play important roles in several processes, including detoxication of substrates such as plant allelochemicals, cuticle formation, pigmentation, and olfaction. Identification and characterization of Bombyx mori UGT genes could provide valuable basic information for this important family and explain the detoxication mechanism and other processes in insects. RESULTS: Taking advantage of the newly assembled genome sequence, we performed a genome-wide analysis of the candidate UGT family in the silkworm, B. mori. Based on UGT signature and their similarity to UGT homologs from other organisms, we identified 42 putative silkworm UGT genes. Most of them are clustered on the silkworm chromosomes, with two major clusters on chromosomes 7 and 28, respectively. The phylogenetic analysis of these identified 42 UGT protein sequences revealed five major groups. A comparison of the silkworm UGTs with homologs from other sequenced insect genomes indicated that some UGTs are silkworm-specific genes. The expression patterns of these candidate genes were investigated with known expressed sequence tags (ESTs), microarray data, and RT-PCR method. In total, 36 genes were expressed in tissues examined and showed different patterns of expression profile, indicating that these UGT genes might have different functions. CONCLUSION: B. mori possesses a largest insect UGT gene family characterized to date, including 42 genes. Phylogenetic analysis, genomic organization and expression profiles provide an overview for the silkworm UGTs and facilitate their functional studies in future.

A genomewide survey of homeobox genes and identification of novel structure of the Hox cluster in the silkworm, Bombyx mori.

Homeobox genes encode transcriptional factors that play crucial roles in a variety of developmental pathways from unicellular to multicellular eukaryotes. We have identified 102 homeobox genes in the typical insect of Lepidoptera, Bombyx mori, based on the newly assembled genome sequence with 9X coverage. These identified homeobox genes were categorized into nine classes including at least 74 families. The available ESTs and microarray data at present confirmed that more than half of them were expressed during silkworm developmental processes. Orthologs of pb, zen and ftz were newly identified in the Bombyx Hox cluster on chromosome 6. Interestingly, a special group of 12 tandemly duplicated homeobox genes was found located between Bmpb and Bmzen in the Bombyx Hox cluster, suggesting that Hox cluster might have experienced a lineage-specific expansion in the silkworm. A detailed analysis on genome data reveals that a split exists between Bmlab and Bmpb. Our data provide valuable information for future research on the development and evolution of silkworm.

[Comparison of early embryogenesis between silkworm and Drosophila from both morphology and gene content level].

The diversity of insects has been the focus of many investigations. Research in the early embryonic developmental mechanism of silkworm will promote understanding in early embryonic developmental mechanism of other insects. This paper reviews the differences in early embryonic development of silkworm and Drosophila from both morphology and gene content level. The results not only provide evidences for the study of early embryonic development mechanism in silkworm, but also give clues for the study of insects diversity.