Peptide (Lys-Leu) and amino acids (Lys and Leu) supplementations improve physiological activity and fermentation performance of brewer's yeast during very high-gravity (VHG) wort fermentation.

Lys and Leu were generally considered as the key amino acids for brewer's yeast during beer brewing. In the present study, peptide Lys-Leu and a free amino acid (FAA) mixture of Lys and Leu (Lys + Leu) were supplemented in 24 °P wort to examine their effects on physiological activity and fermentation performance of brewer's yeast during very high-gravity (VHG) wort fermentation. Results showed that although both peptide Lys-Leu and their FAA mixture supplementations could increase the growth and viability, intracellular trehalose and glycerol content, wort fermentability, and ethanol content for brewer's yeast during VHG wort fermentation, and peptide was better than their FAA mixture at promoting growth and fermentation for brewer's yeast when the same dose was kept. Moreover, peptide Lys-Leu supplementation significantly increased the assimilation of Asp, but decreased the assimilation of Gly, Ala, Val, (Cys)2, Ile, Leu, Tyr, Phe, Lys, Arg, and Pro. However, the FAA mixture supplementation only promoted the assimilation of Lys and Leu, while reduced the absorption of total amino acids to a greater extent. Thus, the peptide Lys-Leu was more effective than their FAA mixture on the improvement of physiological activity, fermentation performance, and nitrogen metabolism of brewer's yeast during VHG wort fermentation.

Silkworm pupae oil exerts hypercholesterolemic and antioxidant effects in high-cholesterol diet-fed rats.

BACKGROUND: Silkworm pupae is a good resource of edible oil that is especially rich in unsaturated fatty acids and is considered to be an excellent dietary supplement for hyperlipidemia. RESULTS: Groups fed a high-cholesterol diet (HCD) with silkworm pupae oil (SPO) supplementation (1, 2, or 4 mL kg-1 day-1 ) orally had significantly lower levels of serum total cholesterol (P < 0.05) and low-density lipoprotein cholesterol (P < 0.05) compared to the HCD group. With regard to antioxidant parameters, except for levels of glutathione peroxidase (GSH-Px) in the liver, 2 and 4 mL kg-1 day-1 of SPO supplementation leaded to higher total antioxidant capacity (P < 0.05), superoxide dismutase (P < 0.05) and GSH-Px levels (P < 0.05), as well as lower malondialdehyde levels (P < 0.05), both in serum and liver compared to the HCD group. CONCLUSION: The results of the present study indicate that supplementation with SPO can improve lipid profiles and alleviate oxidative stress in high-cholesterol diet-fed rats. © 2016 Society of Chemical Industry.

Effect of Silkworm Pupa Protein Hydrolysates on Proliferation of Gastric Cancer Cells In Vitro.

The proliferation inhibition effects of the hydrolysates from silkworm pupa proteins on MGC-803 gastric cancer cells were investigated in this study. The specific morphological changes (cell membrane, cell nucleus and cytoskeleton) of cells were measured. In vitro, the proliferation of MGC-803 cells was inhibited by silkworm pupa protein hydrolysates (SPPHs) in a dose-dependent manner. The flow cytometry analysis showed that the blocking effect of SPPHs on the MGC-803 cells was mainly in the G0/G1-phase. The morphological changes, disintegration of the cytoskeleton and retardant cell cycles were probably related to the activation of apoptosis. Thus, SPPHs could be promising as a chemopreventive agent due to their ability to promote apoptosis of tumor cells.

Safety and Efficacy of CT-Guided Central Venous Catheter Gastric Insufflation in Percutaneous Gastrostomy.

Gastric insufflation for computed tomography (CT)-guided percutaneous gastrostomy is currently performed via a nasogastric tube or a Chiba needle. However, nasogastric tube placement requires patient pharynx and esophagus, and Chiba needle use is associated with an increased risk of organ damage and prolonged operation time. Herein, we introduce a new method of gastric insufflation via a central venous catheter and explore its safety and efficacy by retrospective analysis of the clinical data of patients who underwent percutaneous gastrostomy using this method in our hospital from April 2021 to March 2022. The extracted data included the following: success rate, operation time, gastric insufflation time, radiation dose, postoperative pain score, and complications. We also compared the preoperative levels of several nutritional indicators (body mass index, hemoglobin, albumin, creatinine, and blood urea nitrogen) with those obtained 1 month postoperatively. A total of 12 patients underwent percutaneous gastrostomy under CT guidance using central venous catheter gastric insufflation. The surgery and gastric insufflation success rates were 100% both. The average operation time, gastric insufflation time, and effective radiation dose were 24.08 ± 5.25 min, 5.08 ± 2.50 min, and 14.16 ± 3.63 mSv, respectively. Based on the World Health Organization scale for pain assessment, five patients reported no postoperative pain and seven patients had mild pain. There were no serious complications, such as stoma infection, peritonitis, gastrointestinal perforation and bleeding, or embedding syndrome. All evaluated nutritional indicators showed improvement at 1 month postoperatively, with statistically significant differences compared to the preoperative values (p < 0.05 for all). In conclusion, CT-guided percutaneous gastrostomy with central venous catheter gastric insufflation is a safe, effective, and feasible minimally invasive treatment.

Identification of potential allergens in larva, pupa, moth, silk, slough and feces of domestic silkworm (Bombyx mori).

The silkworm (Bombyx mori) is an important economic insect that can be used as food in many countries in Asia. However, silkworms and their metabolites are an important source of allergens, which can induce severe allergic reactions. So far, there are no systematic studies on the potential allergens in silkworm and its metabolites. These studies have important guiding significance for the prevention, diagnosis, and treatment of silkworm allergy. The aim of this study was to identify the potential allergens from larva, pupa, moth, silk, slough and feces of silkworm and analyze the sequence homology of silkworm allergens with other allergens identified in the Allergenonline database. We have found 45 potential allergens in silkworm. The results of the homology comparison suggested that silkworm allergens likely cross-react with those of Dermatophagoides farinae, Aedes aegypti, Tyrophagus putrescentiae, Triticum aestivum and Malassezia furfur.

Effect of heat, enzymatic hydrolysis and acid-alkali treatment on the allergenicity of silkworm pupa protein extract.

Silkworm pupae are edible insects with high-quality nutrition in many Asian countries, but consumption of silkworm pupae can cause severe IgE-mediated allergic disease. The aim of this study was to investigate the effect of heat, enzymatic hydrolysis and acid-alkali treatment on the allergenicity of silkworm pupa protein extract (SPPE). Heating reduced the allergenicity of SPPE when the temperature was higher than 60 °C. Spectroscopy studies suggested an unfolded conformation of SPPE with heating, dependent on temperature and time. Enzymatic hydrolysis revealed that SPPE at 25 to 33 kDa contained pepsin- and trypsin-resistant allergens. The results of acid-alkali treatment suggested that low pH can promote hydrolysis of SPPE and decrease its allergenicity. Thus, heat, enzymatic hydrolysis and acid-alkali treatment can significantly decrease the allergenicity of SPPE, with heat-, enzyme- and acid-alkali-resistant allergens at 25 to 33 kDa SPPE. This study can help in the development of methods to prepare silkworm pupa protein.

Destruction of the cell membrane and inhibition of cell phosphatidic acid biosynthesis in Staphylococcus aureus: an explanation for the antibacterial mechanism of morusin.

Morusin is a prenylated flavonoid found in mulberry that shows antimicrobial activity against foodborne pathogens. The MIC values of morusin toward S. aureus ATCC 6538 and S. aureus ATCC 25923 were both 14.9 µmol L-1. This study further investigated the antimicrobial mechanism of morusin in inhibiting the growth of Staphylococcus aureus ATCC 6538. Scanning electron microscopy and transmission electron microscopy revealed that morusin disrupted the integrity of the bacterial cell membrane. Morusin may also affect the phospholipid-repair system of bacteria, which repairs membrane structures. To test this hypothesis, quantitative real-time PCR was used to examine the effect of morusin treatment of S. aureus on the regulation of genes associated with the cell phosphatidic acid biosynthesis pathway. Gas chromatography-mass spectrometry was used to investigate the fatty acid components, which are used to synthesize bacterial phosphatidic acids. In summary, the results revealed that morusin showed a potent antibacterial effect by disrupting the cell membrane architecture and inhibiting the phosphatidic acid biosynthesis pathway of S. aureus.

Wheat gluten hydrolysates separated by macroporous resins enhance the stress tolerance in brewer's yeast.

Wheat gluten hydrolysates (WGH) were used to examine their adsorption-desorption kinetics and thermodynamics characteristics on six macroporous resins, and their effects on the stress tolerance in brewer's yeast. Results showed that the pseudo second-order kinetics, Langmuir and Freundlich model could illuminate the adsorption mechanism, and the adsorption process was physical, spontaneous and exothermic. The 40% ethanol fraction separated by XAD-16 resin improved significantly the ethanol tolerance and the viability of brewer's yeast, while the 0% ethanol fraction separated by XAD-16 resin increased obviously the osmotic stress tolerance and the viability of brewer's yeast. Results from scanning electron microscopy showed that both these WGH fractions could increase budding rate and maintain normal morphology of yeast cells under various environmental stress. Thus, WGH separated by macroporous resin could be used in high gravity brewing to enhance the ethanol and osmotic stress tolerance in brewer's yeast.

Complete Mitochondrial Genome of the Citrus Spiny Whitefly Aleurocanthus spiniferus (Quaintance) (Hemiptera: Aleyrodidae): Implications for the Phylogeny of Whiteflies.

In this study, we sequenced the complete mitochondrial genome (15,220 bp) of the citrus spiny whitefly, Aleurocanthus spiniferus (Quaintance), a well-known pest from the superfamily Aleyrodidae. The A. spiniferus mitogenome contains 36 genes, including 13 protein-coding genes (PCGs), 21 transfer RNAs (tRNA), two ribosomal RNAs (rRNA) and a large non-coding region (control region, CR). Like most whiteflies, the A. spiniferus mitogenome had a large degree of rearrangement due to translocation of the nad3-trnG-cox3 gene cluster. The 13 PCGs initiated with ATN and generally terminated with TAA, although some used TAG or T as stop codons; atp6 showed the highest evolutionary rate, whereas cox2 appeared to have the lowest rate. The A. spiniferus mitogenome had 21 tRNAs with a typical cloverleaf secondary structure composed of four arms. Modeling of the two rRNA genes indicated that their secondary structure was similar to that of other insects. The CR of A. spiniferus was 920 bp and mapped between the nad3-trnG-cox3 and trnI-trnM gene clusters. One potential stem-loop structure and five tandem repeats were identified in the CR. Phylogenetic relationships of 11 species from the Aleyrodidae were analyzed based on the deduced amino acid sequences of the 13 PCGs and evolutionary characteristics were explored. Species with more genetic rearrangements were generally more evolved within the Aleyrodidae.

Effect of ultrasonic treatment on the graft reaction between soy protein isolate and gum acacia and on the physicochemical properties of conjugates.

Soy protein isolate (SPI) was grafted with gum acacia (GA) in this work. In comparison with classical heating at high water activity, ultrasound could accelerate the graft reaction between SPI and GA. A degree of graft (DG) of 34 was obtained by ultrasonic treatment for 60 min, whereas 48 h was required with classical heating. Ultrasonic treatment improved the concentration of available free amino groups of SPI. The grafted SPI showed significantly (p < 0.05) higher levels of emulsifying activity index, emulsifying stability index, and surface hydrophobicity than native SPI. The droplet size (D[3,2] and D[4,3]) of SPI emulsion decreased from 8.3 to 2.3 microm and from 25.7 to 7.1 microm through ultrasound-assisted grafting, respectively. Moreover, SPI-GA conjugates gave emulsions exhibiting more stability against creaming than those prepared with only SPI during ambient temperature storage (20 days). Decreases of lysine and arginine contents during the graft reaction indicated that these two amino acid residues attended the covalent linkage between SPI and GA. The results of secondary structure suggested that grafted SPI had decreased alpha-helix and beta-sheet levels and increased unordered coils level.