Surface-enhanced Raman scattering as a potential strategy for wearable flexible sensing and point-of-care testing non-invasive medical diagnosis.

As a powerful and effective analytical tool, surface-enhanced Raman scattering (SERS) has attracted considerable research interest in the fields of wearable flexible sensing and non-invasive point-of-care testing (POCT) medical diagnosis. In this mini-review, we briefly summarize the design strategy, the development progress of wearable SERS sensors and its applications in this field. We present SERS substrate analysis of material design requirements for wearable sensors and highlight the benefits of novel plasmonic particle-in-cavity (PIC)-based nanostructures for flexible SERS sensors, as well as the unique interfacial adhesion effect and excellent mechanical properties of natural silk fibroin (SF) derived from natural cocoons, indicating promising futures for applications in the field of flexible electronic, optical, and electrical sensors. Additionally, SERS wearable sensors have shown great potential in the fields of different disease markers as well as in the diagnosis testing for COVID-19. Finally, the current challenges in this field are pointed out, as well as the promising prospects of combining SERS wearable sensors with other portable health monitoring systems for POCT medical diagnosis in the future.

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.

A polysaccharide extract of mulberry leaf ameliorates hepatic glucose metabolism and insulin signaling in rats with type 2 diabetes induced by high fat-diet and streptozotocin.

Mulberry leaf is a traditional medicine used to treat diabetes in the clinic. The aim of this study was to determine the mechanisms by which mulberry leaf polysaccharide (MLPII), improves hepatic glucose metabolism and insulin resistance in rats with type 2 diabetes induced by high fat and streptozotocin (STZ). MLPII was administered for 6 weeks after establishment of type 2 diabetes in Wistar rats. At the end of the experiment, oral glucose tolerance, liver glycogen content, glucose synthase (GS) activity and insulin resistance were determined. Expression patterns of proteins and genes associated with insulin signaling as well as biomarkers of oxidative stress and antioxidant enzyme activities were assayed. Compared with normal control rats, MLPII treatment significantly improved oral glucose tolerance (P < 0.01) and restored the glycogen level (P < 0.01) and GS activity (P < 0.05) in diabetic rats. Insulin resistance was improved in MLPII-treated diabetic rats (P < 0.01). Furthermore, expression levels of insulin receptor substrate 2 (IRS2), phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB/AKT) involved in insulin signaling were significantly increased (P < 0.01), while protein­tyrosine phosphatase 1B (PTP1B) expression was markedly reduced (P < 0.01). The levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) in livers of the MLPII-treated group were significantly reduced (P < 0.01), while activities of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were significantly increased (P < 0.01, P < 0.01, P < 0.01, respectively). The results clearly indicate that MLPII treatment effectively normalizes hepatic glucose metabolism and insulin signaling by inhibiting the expression of PTP1B, activating the PI3K­AKT pathway and mitigating oxidative stress in the livers of rats with type 2 diabetes induced by high fat and STZ.

Purification, characterization and anti-diabetic activity of a polysaccharide from mulberry leaf.

In the present study, a high-purity polysaccharide from mulberry leaf (MLP) was purified and characterized, and its anti-diabetic effects were investigated in streptozotocin (STZ)-induced diabetic rats. Our results showed that the obtained MLP (purity 99.8%) was determined to be composed of d-arabinose, d-xylose, d-glucose, d-rhamnose and d-mannose with molar ratio of 1:2.13:6.53:1.04:8.73. Oral administration of MLP at 50-200mg/kgbodyweight daily for 5weeks significantly reduced the levels of fasting blood glucose (FBG), glycosylated serum protein (GSP), serum total cholesterol (TC), and serum triglyceride (TG), and increased the body weight, fasting insulin (FINS), C-peptide (C-P), liver glycogen, liver glucokinase, and serum high-density lipoprotein cholesterol (HDL-C). Moreover, MLP promoted marked pancreatic ß-cell regeneration and insulin secretion, and reduced liver fat accumulation in diabetic rats. The treatment effect of MLP on diabetes was similar to the effect of antidiabetic drug glibenclamide. These results clearly indicated that MLP may have a potential for the treatment of hyperglycemia and hyperlipidemia in diabetes.

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.

Anti-diabetic effect of mulberry leaf polysaccharide by inhibiting pancreatic islet cell apoptosis and ameliorating insulin secretory capacity in diabetic rats.

Diabetes mellitus is a clinically complex disease characterized by chronic hyperglycemia with metabolic disturbances. In this study, we investigated the effect of mulberry leaf polysaccharide (MLPII) on pancreatic islet cell apoptosis and insulin secretory function in diabetic rats induced by a high fat diet and streptozotocin. Our results showed that MLPII treatment inhibited pancreatic islet cell apoptosis and ameliorated insulin secretory capacity of pancreatic ß-cells in diabetic rats. And further study demonstrated that chronic treatment of diabetic rats with MLPII resulted in up-regulation of anti-apoptotic B-cell leukaemia/lymphoma 2 (Bcl-2) protein and down-regulation of pro-apoptotic Bcl2-associated X (Bax) and caspase-3 protein in pancreatic islet cells. Moreover, MLPII significantly restored pancreatic duodenal homeobox-1 (PDX-1) protein nuclear localization, and increased mRNA and protein expression of PDX-1 and its downstream targets, glucose transporter 2 (GLUT2) and glucokinase (GCK) in pancreatic islet cells of diabetic rats. These findings suggested that MLPII might play a critical role in protecting pancreatic islet cell from apoptosis via elevation of Bcl-2/Bax ratio, and ameliorating insulin secretory capacity of pancreatic ß-cells via restoration of PDX-1 nuclear localization and expression levels in diabetic rats. This is the first report to explore the potential molecular mechanism involved in the hypoglycemic activity of the polysaccharide from mulberry leaves.

[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.

Media optimization for laccase production by Trichoderma harzianum ZF-2 using response surface methodology.

Trichoderma harzianum ZF-2 producing laccase was isolated from decaying samples from Shandong, China, and showed dye decolorization activities. The objective of this study was to optimize its culture conditions using a statistical analysis of its laccase production. The interactions between different fermentation parameters for laccase production were characterized using a Plackett-Burman design and the response surface methodology. The different media components were initially optimized using the conventional one-factor-at-a-time method and an orthogonal test design, and a Plackett-Burman experiment was then performed to evaluate the effects on laccase production. Wheat straw powder, soybean meal, and CuSO4 were all found to have a significant influence on laccase production, and the optimal concentrations of these three factors were then sequentially investigated using the response surface methodology with a central composite design. The resulting optimal medium components for laccase production were determined as follows: wheat straw powder 7.63 g/l, soybean meal 23.07 g/l, (NH4)2SO4 1 g/l, CuSO4 0.51 g/l, Tween-20 1 g/l, MgSO4 1 g/l, and KH2PO4 0.6 g/l. Using this optimized fermentation method, the yield of laccase was increased 59.68 times to 67.258 U/ml compared with the laccase production with an unoptimized medium. This is the first report on the statistical optimization of laccase production by Trichoderma harzianum ZF-2.

[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.

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.

Colonization of Morus alba L. by the plant-growth-promoting and antagonistic bacterium Burkholderia cepacia strain Lu10-1.

BACKGROUND: Anthracnose, caused by Colletotrichum dematium, is a serious threat to the production and quality of mulberry leaves in susceptible varieties. Control of the disease has been a major problem in mulberry cultivation. Some strains of Burkholderia cepacia were reported to be useful antagonists of plant pests and could increase the yields of several crop plants. Although B. cepacia Lu10-1 is an endophytic bacterium obtained from mulberry leaves, it has not been deployed to control C. dematium infection in mulberry nor its colonization patterns in mulberry have been studied using GFP reporter or other reporters. The present study sought to evaluate the antifungal and plant-growth-promoting properties of strain Lu10-1, to clarify its specific localization within a mulberry plant, and to better understand its potential as a biocontrol and growth-promoting agent. RESULTS: Lu10-1 inhibited conidial germination and mycelial growth of C. dematium in vitro; when applied on leaves or to the soil, Lu10-1 also inhibited the development of anthracnose in a greenhouse, but the effectiveness varied with the length of the interval between the strain treatment and inoculation with the pathogen. Strain Lu10-1 could survive in both sterile and non-sterile soils for more than 60 days. The strain produced auxins, contributed to P solubilization and nitrogenase activity, and significantly promoted the growth of mulberry seedlings. The bacteria infected mulberry seedlings through cracks formed at junctions of lateral roots with the main root and in the zone of differentiation and elongation, and the cells were able to multiply and spread, mainly to the intercellular spaces of different tissues. The growth in all the tissues was around 1-5 × 105 CFU per gram of fresh plant tissue. CONCLUSIONS: Burkholderia cepacia strain Lu10-1 is an endophyte that can multiply and spread in mulberry seedlings rapidly and efficiently. The strain is antagonistic to C. dematium and acts as an efficient plant-growth-promoting agent on mulberry seedlings and is therefore a promising candidate as a biocontrol and growth-promoting agent.

Shotgun proteomic analysis of mulberry dwarf phytoplasma.

BACKGROUND: Mulberry dwarf (MD), which is caused by phytoplasma, is one of the most serious infectious diseases of mulberry. Phytoplasmas have been associated with diseases in several hundred plant species. The inability to culture phytoplasmas in vitro has hindered their characterization at the molecular level. Though the complete genomes of two phytoplasmas have been published, little information has been obtained about the proteome of phytoplasma. Therefore, the proteomic information of phytoplasmas would be useful to elucidate the functional mechanisms of phytoplasma in many biological processes. RESULTS: MD phytoplasmas, which belong to the 16SrI-B subgroup based on the 16S DNA analysis, were purified from infected tissues using a combination of differential centrifugation and density gradient centrifugation. The expressed proteome of phytoplasma was surveyed by one-dimensional SDS-PAGE and nanocapillary liquid chromatography-tandem mass spectrometry. A total of 209 phytoplasma proteins were unambiguously assigned, including the proteins with the functions of amino acid biosynthesis, cell envelope, cellular processes, energy metabolism, nucleosides and nucleotide metabolism, replication, transcription, translation, transport and binding as well as the proteins with other functions. In addition to these known function proteins, 63 proteins were annotated as hypothetical or conserved hypothetical proteins. CONCLUSIONS: Taken together, a total of 209 phytoplasma proteins have been experimentally verified, representing the most extensive survey of any phytoplasma proteome to date. This study provided a valuable dataset of phytoplasma proteins, and a better understanding of the energy metabolism and virulence mechanisms of MD phytoplasma.

Comparative proteomic analysis provides new insights into mulberry dwarf responses in mulberry (Morus alba L.).

Mulberry dwarf (MD) is a serious infectious disease of mulberry caused by phytoplasma. Infection with MD phytoplasma results in stress phenotypes of yellowing, phyllody, stunting, proliferation, and witches' broom. Physiological and biochemical analysis has shown that infection with MD phytoplasma causes an increase in soluble carbohydrate and starch content, and a decrease in the net photosynthesis rate, carboxylation efficiency, and pigment content of leaves. Furthermore, damage to the chloroplast ultrastructure was detected in infected leaves. To better understand the pathogen-stress response of mulberry (Morus alba L.) to MD phytoplasma, we conducted a comparative proteomic analysis using 2-DE of infected and healthy leaves. Among 500 protein spots that were reproducibly detected, 20 were down-regulated and 17 were up-regulated. MS identified 16 differentially expressed proteins. The photosynthetic proteins rubisco large subunit, rubisco activase, and sedoheptulose-1,7-bisphosphatase showed enhanced degradation in infected leaves. Based these results, a model for the occurrence mechanism of MD is proposed. In conclusion, this study provides new insights into the mulberry response to MD phytoplasma infection.

[Identification and colonization of an antagonistic endophytic Burkholderia cepacia Lu10-1 isolated from mulberry].

OBJECTIVE: To identify and colonize an antagonistic bacterium, Lu10-1, isolated from the healthy mulberry. METHODS: Strain Lu10-1 was identified based on the analysis of its 16S rRNA gene sequence homology, the physiological and biochemical characteristics, and the recA gene sequence comparison. A spontaneous Lu10-1 mutant tolerant to rifampicin and ampicillin were isolated by gradually increasing the concentration of the two antibiotics. The mutants were used to assess the ability of Lu10-1 to colonize mulberry by different inoculation approaches, including stem and leaf acupuncturing, seed soaking, root soaking and leaf daubing. RESULTS: Lu10-1 belonged to Burkholderia. In the phylogenetic tree, Lu10-1 was the closest relative to B. cepacia (X80284) with more than 98% sequences similarity. The 16S rDNA sequences of Lu10-1 have been registered at GenBank database under the accession number EF546394. Moreover, our results also indicated that the population of strain Lu10-1 living in the mulberry tissues decreased as a whole after the treatment of seed soaking. The bacterial density inside the mulberry seedling tissues decreased to a steady level 20 days after germination. The population of strain Lu10-1 in mulberry leaves and stems after the treatment of root soaking increased first and then decreased. CONCLUSION: The strain Lu10-1 fell into Burkholderia cepacia genomovar I as a single species. Furthermore, the strain Lu10-1 could colonize and transmit in mulberry, while its resistance to plant pathogen was not changed during the process of colonization compared to the original strains. Taken together, we suggest that Burkholderia. cepacia Lu10-1 will play an important role in the biological control of mulberry disease.

Biological control against bacterial wilt and colonization of mulberry by an endophytic Bacillus subtilis strain.

Forty-five bacterial isolates were collected from surface-sterilized leaves of mulberry (Morus alba L.). By screening their antagonistic activities against Ralstonia solanacearum in vitro, four isolates showed a remarkable inhibitory effect. The evaluation of the antagonistic strains against bacterial wilt of mulberry indicated that the strain Lu144 effectively reduced disease incidence. In the greenhouse, Lu144 displayed effective biological control against bacterial wilt of mulberry when it was applied to sterile or nonsterile soil before the infection by the pathogen. Based on bacteriological properties and 16S rRNA gene sequencing, Lu144 was identified as a strain of Bacillus subtilis. The endophytic population and infection process of Lu144 in mulberry seedlings was explored following recovery of the green fluorescent protein (GFP)-labeled Lu144 and examination of the labeled strain by confocal laser scanning microscopy. Interestingly, the infection of GFP-labeled Lu144 cells into the mulberry seedlings occurred through the cracks formed at the lateral root junctions and the zone of differentiation and elongation, and the cells were able to develop and transfer in mulberry and mainly in the intercellular spaces of different tissues. The population of the GFP-labeled Lu144 inoculant was larger and more stable in leaves than that in roots and stems.

[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.