Effects of Calcium-Binding Peptide from Tilapia Scale Protein Hydrolysates on Calcium Absorption in Caco-2 Cells

ABSTRACT

Fish scales are usually discarded as an industrial solid waste. In this study the fish scale protein was recovered and employed to prepare protein hydrolysates using commercial proteases. The hydrolysates were further separated into four peptide fractions (F1, F2, F3, and F4) by Sephadex G-15. Among the fractions, the F3 fraction, with the highest calcium-binding activity, was further investigated to enhance calcium uptake in Caco-2 cells. The results showed calcium uptake from F3-Ca by Caco-2 cells after 2 h of incubation was significantly higher than those of CaCl₂ and tilapia scale protein hydrolysates (TSPH), respectively, and was similar to that of casein phosphopeptide (CPP). Therefore, the F3 fraction improved Ca uptake versus the CPP samples and can be employed as an alternative to CPP in the manufacture of functional foods.     

后非时代中小型猪场和散养户复养技术指导

中小型猪场和散养户在我国生猪养殖行业占据重要地位。面对非洲猪瘟带来的猪肉市场严重失调的情况,中小型猪场和散养户生猪复养迫在眉睫。文章通过对中小型猪场和散养户目前的现状以及重要地位的简要分析,总结复养过程存在的雷区和难点,对其复养步骤做出指导性的建议。再通过分析非洲猪瘟防控案例,明确了非洲猪瘟的可防可控性。为中小型猪场和散养户提供了可行性的防控技巧,提高中小型猪场和散养户复养的成功率和积极性。     

Identification of the Major ACE-Inhibitory Peptides Produced by Enzymatic Hydrolysis of a Protein Concentrate from Cuttlefish Wastewater

The aim of this work was the purification and identification of the major angiotensin converting enzyme (ACE) inhibitory peptides produced by enzymatic hydrolysis of a protein concentrate recovered from a cuttlefish industrial manufacturing effluent. This process consisted on the ultrafiltration of cuttlefish softening wastewater, with a 10 kDa cut-off membrane, followed by the hydrolysis with alcalase of the retained fraction. Alcalase produced ACE inhibitors reaching the highest activity (IC₅₀ = 76.8 ± 15.2 μg mL⁻¹) after 8 h of proteolysis. Sequential ultrafiltration of the 8 h hydrolysate with molecular weight cut-off (MWCO) membranes of 10 and 1 kDa resulted in the increased activity of each permeate, with a final IC₅₀ value of 58.4 ± 4.6 μg mL⁻¹. Permeate containing peptides lower than 1 kDa was separated by reversed-phase high performance liquid chromatography (RP-HPLC). Four fractions (A–D) with potent ACE inhibitory activity were isolated and their main peptides identified using high performance liquid chromatography coupled to an electrospray ion trap Fourier transform ion cyclotron resonance-mass spectrometer (HPLC-ESI-IT-FTICR) followed by comparison with databases and de novo sequencing. The amino acid sequences of the identified peptides contained at least one hydrophobic and/or a proline together with positively charged residues in at least one of the three C-terminal positions. The IC₅₀ values of the fractions ranged from 1.92 to 8.83 μg mL⁻¹, however this study fails to identify which of these peptides are ultimately responsible for the potent antihypertensive activity of these fractions.     

Potent Cytotoxic Peptides from the Australian Marine Sponge Pipestela candelabra

Two consecutive prefractionated fractions of the Australian marine sponge extract, Pipestela candelabra, were identified to be selectively active on the human prostate cancer cells (PC3) compared to the human neonatal foreskin fibroblast non-cancer cells (NFF). Twelve secondary metabolites were isolated in which four compounds are new small peptides. Their structures were characterized by spectroscopic and chemical analysis. These compounds inhibited selectively the growth of prostate cancer cells with IC₅₀ values in the picomolar to sub-micromolar range. Structure-activity relationship of these compounds is discussed.     

Pardaxin, an antimicrobial peptide, triggers caspase-dependent and ROS-mediated apoptosis in HT-1080 cells

Pardaxin is an antimicrobial peptide (AMP) that was first isolated from secretions of the Red Sea Moses sole. The role of pardaxin in inducing apoptosis for preventing cancer has not yet been investigated. In the present study, we examined the antitumor activity of pardaxin against human fibrosarcoma HT-1080 cells; pardaxin inhibited cell proliferation by inducing apoptosis, as demonstrated by an increase in the externalization of plasma membrane phosphatidylserine and the presence of chromatin condensation. Additionally, pardaxin-treated cells showed elevation of caspase-3/7 activities, disruption of the mitochondrial membrane potential, and accumulation of reactive oxygen species (ROS) production. Inhibition of ROS production and caspase-3/7 activities reduced pardaxin-induced effects. Taken together, these findings suggest that pardaxin may be a potential anticancer agent for selectively inducing apoptosis in cancer cells.     

大豆肽饲料的营养特点及其在畜禽生产中的应用

大豆肽是大豆蛋白质的水解产物,主要功能性营养物质包括:多肽、寡肽、游离氨基酸和糖类,其相对分子质量低,易于消化吸收。丰富的小肽能调节矿物质、脂类代谢,降低胆固醇,提高免疫力。文章综述了大豆肽的饲料营养特点、制备工艺及在畜禽生产中的应用。     

小型化验室管理工作

分析了小型化验室管理中常见的问题,归纳了小型化验室的管理要点,探讨了小型化验室如何根据自身实际构建合适的质量体系以提升管理水平.     

藏系绵羊肠道解剖学指标测定

为探讨藏羊肠管适应高原低氧环境的解剖学特点,选取青海海晏的藏系绵羊作为研究对象,对其肠管的解剖学指标进行测定,并与小尾寒羊进行比较。结果表明,藏羊的肠管总长和大肠长度均长于小尾寒羊,差异显著（P〈0．05）;而藏羊的小肠总长短于小尾寒羊,差异显著（P〈0．05）。这种解剖学指标的差异与2种动物所处的环境与饲养方式不同有关,藏羊的肠管解剖学特点是其肠道对高原低氧环境以及粗饲放牧方式的一种解剖学适应。     

松嫩平原盐碱草地土壤种子库小尺度格局研究

用样线法、调查法、幼苗萌发法研究松嫩平原盐碱草地种子库在小尺度空间范围的水平分布格局。结果表明：①土壤种子库的密度为（1179．27±917．78）粒/m2,其中有757株植物幼苗,单子叶42．93％,双子叶57．07％,隶属15个科,23个属,37个种。②土壤种子库Shannon—Wiener指数H、Simpson指数、Margalet丰富度指数R、Pielou均匀度指数的范围分别为：1．42～2．03、0．70～0．78、1．50～3．33、0．77～0．89。选取出现频数较高的8个物种进行空间格局分析,离散系数的分析表明,只有苣荬菜在样方18显示出聚集分布,其他情况均为随机分布。Lloyd平均拥挤指数分析显示,繁缕、红足蒿、全叶马兰、寸草在该地区为聚集分布,而苣荬菜、碱蓬、稗草、羊草为随机分布。此外,在试验的取样间距（1m）前提下,8个物种在18个样方的空间相关性差别较大,8个物种在多数样方中显示空间负相关,表现正相关性的样方较少。     

日粮粗蛋白和大米活性肽添加水平对断奶仔猪生长及血液生化指标的影响

采用3×3双因子试验设计,其中粗蛋白质设17.0%、18.5%、20.0%三个水平,大米活性肽设0、1%、2%三个水平,研究了日粮中粗蛋白质水平和大米活性肽的不同添加量对断奶仔猪生长性能和血液生化指标的影响。结果表明,在断奶仔猪的日粮中添加1%~2%的大米活性肽,可明显提高仔猪的生长性能,平均日增重和平均日采食量分别增加5.37%~7.13%和4.62%~5.49%,料重比降低了0.63%~1.86%;还可将日粮中粗蛋白质含量降低1.5~3.0个百分点;同时,添加1%~2%的大米活性肽还能显著增强仔猪的抗氧化能力和免疫功能。