[Progress in the role of oxidative stress in the pathogenesis of type 2 diabetes].

Diabetes mellitus (DM) is characterized by hyperglycemia and disturbances of carbohydrate and fat metabolism resulted from an absolute or relative deficiency of insulin and insulin resistance. Recent studies indicate that oxidative stress may have a central role in the pathogenesis of type 2 diabetes. Currently, the diagnosis of body oxidative stress level mainly depends on the detection of oxidative stress markers including reactive oxygen species (ROS), reactive nitrogen species (RNS) and lipid peroxide in clinical and experimental studies with methods combining physical and chemical means. The mechanism underlying oxidative stress-induced diabetes mainly may be through two ways. Firstly oxidative stress damages the normal function of islet ß cells, through the destruction of mitochondrial structure and inducing apoptosis, activation of nuclear transcription factor kappa B (NF-κB) signaling pathway, causing cell inflammatory response, and reducing insulin synthesis and secretion by inhibiting pancreatic and duodenal homeobox 1 (PDX-1) nuclear cytoplasm translocation as well as inhibiting energy metabolism; Secondly, oxidative stress induces insulin resistance by interfering physiological activities related to insulin signaling including phosphorylation of insulin receptor (InsR) and insulin receptor substrate (IRS), the activation of phosphatidylinositol 3-kinase (PI3K) and the translocation of glucose transporter 4 (GLUT4), as well as injuring the cytoskeleton. Studying the role of oxidative stress in the pathogenesis of diabetes not only helps to reveal the pathogenesis of diabetes, but also provides a theoretical basis for the prevention and treatment of diabetes.

Alternative splicing of the antitrypsin gene in the silkworm, Bombyx mori.

Alternative splicing plays an important role in expanding protein diversity. In the present study, different splice variants of the antitrypsin gene (sw-AT) in the silkworm were identified by bioinformatics analyses using expressed sequence tags and genomic information. Four splice variants were obtained by RT-PCR with suitably designed primers, confirmed by sequencing, and designated as sw-AT-1, sw-AT-2, sw-AT-3, and sw-AT-4. The sw-AT gene contains 10 exons and nine introns. The splice variants differ in exon 9, with sw-AT-1, sw-AT-2, and sw-AT-3 using different versions of the exon, namely exon 9a, 9b, and 9c, respectively. In sw-AT-4, exon 9 consists of the combination of exons 9b and 9c. The expression patterns of the four isoforms in different tissues, at different developmental stages, and under different stress conditions (temperature, starvation, and mycotic infection) were characterized and quantified. The sw-AT isoforms showed tissue-specific expression patterns, with sw-AT-1 present in almost all tissues and sw-AT-4 found in only a few tissues. The four isoforms were predominantly expressed in the fat body, body wall, and testes of larvae, and exhibited similar expression profiles during development of the fat body. Among the stress treatments, low temperature had the greatest effect on isoform expression, and expression was also upregulated with mycotic infection.

[Identification of white muscardin silkworms by infrared spectroscopy].

The infrared spectra of the ethanol extracts of well-living silkworms and white muscardin silkworms of different seasons and breeds were analyzed by means of the sequential analysis in which two indexes, i. e. common peak ratio and variant peak ratio, were applied. The results showed that the ethanol extracts of white muscardin silkworm have a stable and distinct infrared spectrum. The spectral differences of the ethanol extracts between white muscardin silkworms and well-living silkworms were so obvious that the common peak ratio of them was no more than 63. 0%, and the variant peak ratio amounted to 41. 2%. The spectra of different breeds and seasons conformed with each other with a few small differences. The minimum common peak ratio of the spectra of different breeds was 76. 0%, and the maximal ratio was 92. 0%. The common peak ratio of the spectra of different seasons was 73. 1%. Infrared spectrometry was proved to be good for the identification of white muscardin silkworms and the differentiation of white muscardin silkworms of different breeds and seasons.

Transcription factor SGF1 is critical for the neurodevelopment in the silkworm, Bombyx mori.

FoxA transcription factors play vital roles in regulating the expression of organ-specific genes. BmSGF1, the sole FoxA family member in Bombyx mori, is required for development of the silk gland. However, the function of BmSGF1 in development of the nervous system in the silkworm remains unknown. Here, we show that the amino acids sequence of BmSGF1 is evolutionarily conserved in its middle region from Trichoplax adhaerens to human and diverged from the homologues in most other species in its N-terminal region. BmSGF1 expresses in the nervous system at the embryonic stage. Knockdown of Bmsgf1 by RNA interference (RNAi) results in abnormal development of axons. Therefore, our results demonstrate that BmSGF1 is an indispensable regulator for neurodevelopment.

Evolutionarily conserved repulsive guidance role of slit in the silkworm Bombyx mori.

Axon guidance molecule Slit is critical for the axon repulsion in neural tissues, which is evolutionarily conserved from planarians to humans. However, the function of Slit in the silkworm Bombyx mori was unknown. Here we showed that the structure of Bombyx mori Slit (BmSlit) was different from that in most other species in its C-terminal sequence. BmSlit was localized in the midline glial cell, the neuropil, the tendon cell, the muscle and the silk gland and colocalized with BmRobo1 in the neuropil, the muscle and the silk gland. Knock-down of Bmslit by RNA interference (RNAi) resulted in abnormal development of axons and muscles. Our results suggest that BmSlit has a repulsive role in axon guidance and muscle migration. Moreover, the localization of BmSlit in the silk gland argues for its important function in the development of the silk gland.

[Control effect and bacteriostasis of mulberry endophytic bacterium Burkholderia cepacia Lu10-1 on silkworm septicemia].

A laboratory test was conducted to study the control effect and bacteriostasis of antagonistic bacterium Burkholderia cepacia Lu10-1 isolated from mulberry on silkworm septicemia, aimed to develop a new microbial pesticide to control silkworm diseases. The supernatant of Lu10-1 zymotic fluid achieved 41.2% control efficiency and 24.0% prophylactic effect on silkworm septicemia. The antibacterial crude extract of Lu10-1 had stronger antagonistic activity against Bacillus bombyseptieus. The diameter of inhibition zone reached 18.20 mm, and the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the antibacterial crude extract were 1.56 and 3.13 mg x mL(-1), respectively. After treated with the antibacterial crude extract, B. bombyseptieus never appeared logarithmic growth phase, its cell membrane permeability changed, intracellular protein leaked out, intracellular macromolecular protein degraded, and at last, the thalli cracked, inner substances out-flowed, cavity formed, and cell ablated. It was considered that the antagonistic substances of Lu10-1 strain could be used for controlling silkworm septicemia, with preferable development foreground.