乳铁蛋白肽的研究进展

乳铁蛋白肽(Lactoferricin,Lfcin)是动物乳汁中的乳铁蛋白(Lactoferrin,LF)在动物消化道中经酸性胃蛋白酶降解后产生的含25～28个氨基酸的小肽,它具有杀菌、抗病毒、抗真菌等多种独特的生物学活性,对动物具有保护功能.本文概述了乳铁蛋白肽的结构、生物学功能、国内外研究动态及其应用前景.     

乳铁蛋白及其活性肽的营养生理作用及应用前景

乳铁蛋白(LF)是一种多功能的糖蛋白,乳铁蛋白活性多肽(Lfcin)是从LF上被胃蛋白酶水解下来的25个氨基酸残基的小肽。文中阐述了乳铁蛋白及其活性多肽的结构,介绍了乳铁蛋白及其活性多肽的主要生理作用:抗菌、抑菌、抗病毒、抗氧化,调节机体的免疫和提高肠道对铁离子的吸收等作用。根据乳铁蛋白制备的研究进展,讨论了乳铁蛋白及其活性多肽在乳、食品和动物生产中作为添加剂的应用前景。     

乳铁蛋白肽的研究现状及进展

<正>近年来抗菌肽由于自身的优点成为抗生素的替代品,已成为学术界研究与开发的热点,其中乳铁蛋白肽(Lactoferricin,Lfcin)因其强大的生物学功能而备受关注。最初是由Bellamy等从乳铁蛋白水解物中分离到一种乳铁蛋白多肽,即牛乳铁蛋白肽(LfcinB),此     

高原牦牛乳铁蛋白素基因克隆及序列分析

利用PCR技术从高原牦牛基因组DNA中获得了乳铁蛋白素(lactoferricin,Lfcin)基因序列;将Lfcin基因连接于pGEM T easy载体,送至生物公司测序;将高原牦牛与奶牛的Lfcin基因序列进行比对;同时,对牦牛、奶牛、人、小鼠等物种的Lfcin蛋白序列进行分析。结果表明：克隆获得了含高原环湖牦牛LF(lactoferrin)第2外显子的DNA序列,共778 bp,其中Lfcin基因编码区长75 bp,编码25个氨基酸; 序列分析显示,克隆获得的牦牛DNA序列与奶牛这一序列存在9个碱基的变异;牦牛和奶牛的Lfcin蛋白质序列完全相同,各物种Lfcin蛋白具有较高的同源性。     

乳铁蛋白及乳铁蛋白肽的基因工程研究进展

近年来,随着对乳铁蛋白和乳铁蛋白肽作用机制和空间结构的研究趋于成熟,国内外研究者逐渐将研究重点倾向于乳铁蛋白和乳铁蛋白肽的开发应用.主要介绍了乳铁蛋白和乳铁蛋白肽基因工程的研究进展,尤其是对原核表达系统和真核表达系统进行了综述.     

藏绵羊乳腺乳铁蛋白的克隆及序列分析

本研究以四川若尔盖县藏系绵羊为材料,利用RT-PCR方法扩增并克隆了藏绵羊乳铁蛋白(lactoferrin,LF)序列,运用生物信息学软件对其核苷酸序列和编码蛋白质的结构进行预测和分析。结果表明,克隆的LF基因全长2127 bp,共编码708个氨基酸,N端有19个氨基酸组成的信号肽,该蛋白质等电点为8.4,预测分子质量为77.2 ku;半定量RT-PCR分析结果表明,LF在乳腺、气管、淋巴、肝脏、泪腺和脾脏中都有表达,在肺脏中不表达。本试验克隆了藏绵羊LF cDNA全序列,并对LF和乳铁蛋白肽(lfcin,Lfc)核苷酸和蛋白质进行了分析,为进一步研究其生物学活性奠定基础。     

乳铁蛋白及其生物学功能

1 乳铁蛋白的产生与分布乳铁蛋白(Lactoferrin，简称LF)是一种铁结合性糖蛋白，1960年首先由Groves从牛乳中分离获得。各种哺乳动物都能产生LF，但其浓度因物种而异。人乳中含量特别丰富，初乳中高达7 g/L，常乳中为 1 g/L。在缺铁母体中LF浓度正常，而在蛋白营养不良的母体中，LF浓度降低。牛乳中LF含量要少得多，初乳中为1 g/L，随着泌乳的进行，浓度迅速下降。山羊、马、猪、小鼠和天竺鼠乳中LF的浓度也很低，如猪的变化范围是1.2 g/L(初乳)～0.3 g/L(常乳)。LF是一种分泌性蛋白质，它不仅合成于乳腺，在浸润粘膜表面的多数主要…     

乳铁蛋白及其活性多肽的研究进展

从动植物的天然产品中寻找耐热活性因子,是饲料科学的一个新的研究方向。家畜乳中含有多种具抗菌作用的蛋白质分子,对母畜的自身免疫及维持初生仔畜的胃肠道的健康起重要作用。乳铁蛋白(1actoferrin,简写为LF)是Groves于1960首先从牛乳中分离获得,由于LF与铁结合形成红色的复合物,故始称为红蛋白。1961年Blanc和Isliker将他们从人乳中分离出来的此种蛋白正式命名为乳铁蛋白。另有学者据乳铁蛋白转运铁的功能将其称     

猪乳铁蛋白肽的分子改良及改良肽的生物学活性研究

本研究采用化学合成的方法获得了猪源乳铁蛋白肽LFP-20及其改良肽,旨在通过研究该抗菌肽一级结构与抗菌活性的关系,获得抗菌活性更高的改良肽.微量肉汤稀释法测定的最小抑菌浓度(MIC)及溶血性分析结果表明,猪乳铁蛋白肽LFP-20及其改良肽LF2A、LF-1和LF-3对大肠杆菌、猪霍乱沙门氏菌、鼠伤寒沙门氏菌、金黄色葡萄...     

乳铁蛋白生物学功能研究进展

乳铁蛋白(LF)是一种铁结合糖蛋白,广泛存在于哺乳动物组织和体液中.它具有多种生物学作用,包括调节铁代谢和免疫反应,并具有抗微生物、抗氧化、抗癌和抗炎等活性.乳铁蛋白可以直接或间接螯合铁发挥其抗菌、抗氧化作用;乳铁蛋白作为一种免疫调节剂,对先天性免疫反应和适应性免疫反应都有作用.本文综述了乳铁蛋白的生理功能,旨在为其在...     

牛乳铁蛋白肽基因LfcinB的合成及真核表达载体的构建

根据APD抗菌肽数据库报道的牛乳铁蛋白肽LfcinB氨基酸序列,合成编码LfcinB基因的2条互补的寡核苷酸链,退火后在5′端和3′端分别形成含有BamH I和Xho I位点粘性末端的双链DNA。真核表达载体pcDNA3.1（+）经BamH I 和Xho I限制性内切酶双酶切处理后与合成的LfcinB基因进行连接,连接产物转化E.coli DH5α感受态细胞,提取质粒DNA进行测序。测序结果显示,牛乳铁蛋白肽LfcinB基因成功克隆到pcDNA3.1（+）真核表达载体中,为进一步表达和抗菌活性研究奠定物质基础。     

The in vitro effect of bovine lactoferrin on the activity of organ leukocytes in rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla) and wels catfish (Silurus glanis)

Lactoferrin (LF) is a glycoprotein found in milk, neutrophil granules, secretions and selected organs of mammals. Lactoferrin exhibits antibacterial, antiviral, fungicidal, immunoregulatory and other functions. Although fish are devoid of this protein and its cell receptors, LF effect on the immune mechanisms of fish has been demonstrated. The objective of this study was to investigate the effect of bovine lactoferrin, applied in vitro, on the activity of head kidney and spleen leukocytes in three freshwater fish species: rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla) and wels catfish (Silurus glanis). The obtained results validate LF beneficial effect on the respiratory burst of phagocytes in rainbow trout and wels catfish despite the fact that the potential killing activity against Aeromonas hydrophila was not stimulated in any of the studied species. Bovine lactoferrin enhanced the proliferation of T-lymphocytes in rainbow trout and European eel, as well as of B-lymphocytes in rainbow trout.     

Bacteriostasis of Escherichia coli by bovine lactoferrin, transferrin and immunoglobulins (IgG1, IgG2, IgM) acting alone or in combination

The effect on Escherichia coli strain B117 of bovine lactoferrin (LF), transferrin (Tr) and immunoglobulins (Ig), acting alone or in combination, was investigated in vitro. IgG1 and IgM, which, in contrast to IgG2 possessed a marked antibody activity, as assessed by enzyme-linked immunosorbent assay, induced the appearance of microcolonies in suspension, a phenomenon which could lead to misleading interpretations in the absence of sonic treatment, but none of these three isotypes influenced bacterial growth. Both LF and Tr promoted a strong inhibition of bacteria without requirement for antibodies. After a short period of growth, the multiplication of bacteria was almost completely prevented by the iron-binding proteins acting alone. A significant (p less than 0.02) but moderate (0.5 less than log10) further growth reduction was obtained when Ig of either class was added to Tr, while addition of Ig to LF revealed no significant cooperative effect. All of 11 strains of E. coli isolated from bovine mastitis were sensitive to LF action in the absence of Ig. It therefore appeared that antibodies were not required for iron-binding proteins to exert a potent bacteriostatic effect on mastitis isolates of E. coli.     

Decreased resistance of Bos taurus cattle on a diet supplemented with whole cotton seed to the tick Boophilus microplus (Canestrini)

Resistance to the tick B. microplus was compared in Bos taurus steers fed hay (low fat (LF) diet) with those fed hay supplemented with whole cotton seeds (high fat (CS) diet) which made them hyperlipidaemic. The mean number of adult female ticks maturing from the same artificial doses of larvae was about 2.7 times higher on animals fed the CS diet than on animals fed the LF diet. In both dietary groups the effect of ticks: depressed packed-cell volume, plasma cholesterol and phospholipid levels, serum albumin levels, serum alkaline phosphatase (EC 3.1.3.1) and amylase (EC 3.2.1.1) activities, and monocyte count; increased the serum level of gamma-globulin and eosinophil count. Animals on the LF diet responded to tick infestation with an increase in the number of circulating lymphocytes and a decrease in the neutrophil count. In contrast, the lower tick resistance in hyperlipidaemic animals on the CS diet was associated with a decrease in the number of lymphocytes.     

Identification, isolation, and partial characterization of a novel Streptococcus uberis adhesion molecule (SUAM)

The ability to attach to the host cell surface has been considered an important virulence strategy in many bovine mammary gland pathogens, including Streptococcus uberis. Research conducted in our laboratory lead to the identification of an S. uberis adhesion molecule (SUAM) with affinity for bovine lactoferrin (LF) and delineation of its role in adherence of S. uberis to bovine mammary epithelial cells. Using a selected bacterial surface protein extraction protocol and affinity chromatography, a 112-kDa protein that had a similar molecular mass and the LF affinity as one of the identified S. uberis LBP described by Fang and Oliver in 1999 was found. To further characterize SUAM, the N-terminal amino acid sequence of this protein was elucidated. A protein query versus translated database TBLASTN search of the National Center for Biotechnology (NCBI), non-redundant database, nr, with the LBP N-terminal amino acid sequence showed no significant similarity with previous entries. Antibodies directed against SUAM and a 17 amino acid long N-terminal sequence (pep-SUAM) inhibited adherence to and internalization of S. uberis UT888 into bovine mammary epithelial cells. Data presented suggests that we have discovered a novel bacterial protein involved in the pathogenesis of this economically important mastitis pathogen.     

Effect of lactoferrin on selected immune system parameters and the gastrointestinal morphology in growing calves

Lactoferrin (LF) is a cationic iron-binding glycoprotein that is abundantly expressed and secreted from glandular epithelial cells and a prominent component of the secondary granules of polymorphonuclear neutrophils. Various in vitro and in vivo experiments demonstrate anti-microbial, -viral, -mycotic and -inflammatory effects of LF, associated with modulations of the immune system. Effects of oral administered LF on selected immune system parameters were studied in calves. Five calves were fed LF beginning on day 3 of life with colostral milk and starting on day 6 of life milk replacer enriched with 0.16% LF was fed. The average daily intake of LF per calf was 1.5-1.6 g/day. Additional five calves served as control group with identical treatment except for the LF supplementation. At the end of the study (day 61 of life), all calves were slaughtered and various tissues were sampled for histological and gene-expression studies. LF given orally was shown to act as an immunomodulatory agent by enhancing the size of Peyer's patches in the ileum and increasing blood serum immunoglobulin G levels. In addition, the number of peripheral blood leucocytes increased and mRNA levels of various interleukins (IL) such as IL-1beta, IL-8, IL-10 and interferon gamma (IFNgamma) in those cells in response to LF treatment were enhanced. In blood, the mRNA expression of the pro-inflammatory marker genes IL-1beta and IFNgamma decreased over 10-week treatment. Additionally, LF feeding decreased villus sizes in the jejunum. Together these findings emphasize the ability of LF to stimulate prominent immune system parameters and that it has the capacity to modulate the immune responses in a positive way.     

Changes in heart rate and heart rate variability in Thoroughbreds during prolonged road transportation

OBJECTIVE: To determine whether evaluation of heart rate (HR) and HR variability (HRV) during prolonged road transportation in horses provides a sensitive index of autonomic stimulation. ANIMALS: Five 2-year-old Thoroughbreds. PROCEDURE: ECGs were recorded as horses were transported for 21 hours in a 9-horse van. Heart rate, high-frequency (HF) power, low-frequency (LF) power, and LF-to-HF ratio from Fourier spectral analyses of ECGs were calculated and compared with values recorded during a 24-hour period of stall rest preceding transportation. RESULTS: HR, HF power, and LF power had diurnal rhythms during stall rest but not during road transportation. Heart rate was higher and HF power and LF power lower during road transportation than stall rest, and HR, HF power, LF power, and LF-to-HF ratio all decreased with time during road transportation. Heart rate during stall rest was weakly and inversely associated with LF power, but during road transportation was strongly associated with LF power, HF power, and LF-to-HF ratio. Neither LF power nor HF power was correlated with LF-to-HF ratio during stall rest, but LF power was strongly and HF power weakly correlated with LF-to-HF ratio during road transportation. High-frequency power and LF power were significantly correlated with each other during stall rest and road transportation. Heart rate was significantly influenced by LF power and LF-to-HF ratio during stall rest (R(2) = 0.40) and by HF power and LF-to-HF ratio during road transportation (R(2) = 0.86). CONCLUSIONS AND CLINICAL RELEVANCE: HR is influenced by different sympathovagal mechanisms during stall rest, compared with during road transportation; HRV may be a sensitive indicator of stress in transported horses.     

No effect of short‐term exposure to high‐fibre diets on the gastrointestinal morphology of layer hens (Gallus gallus domesticus): body reserves are used to manage energy deficits in favour of phenotypic plasticity

Summary Using layer hens, Gallus gallus domesticus, we compared the digestive capabilities of birds on a low‐fibre diet (LF, 8.49% neutral detergent fibre; NDF), with those fed a high‐fibre diet balanced for energy and protein to match the LF diet (high fibre balanced, HFB; NDF = 15.61%) and those fed a high fibre unbalanced (HFU) diet (NDF = 16.68%). The HFU diet had the lowest apparent dry matter (DM) metabolisability at 58.14 ± 6.46%, followed by HFB, 65.87 ± 3.50 and the LF diet, 70.49 ± 7.07%. Despite significant differences between apparent DM metabolisabilities of LF and HFU diets, no morphometric changes in the gastrointestinal tract (GIT) of layer hens were observed (including crop, gizzard, proventriculus, liver, large intestine, paired caeca and small intestine). Conversely, body mass losses were recorded for animals on HFU diet, while those on the LF and HFB diets actually gained body mass over the 14‐day trials. We suggest that the body mass losses seen in the animals fed HFU diets were attributed to losses in adipose tissue, but this was not quantified. Assuming body mass losses were mainly in adipose tissue, we propose that adipose may act to buffer environmental challenges like shortfalls in nutrient acquisition when dietary energy requirements are not met. Compared with smaller birds (e.g. quail), the larger body size of the layer hens may offer them a greater safety margin in terms of body energy reserves before changes in the GIT might be needed to redress energy deficits associated with hard‐to‐digest, high‐fibre diets.     

Serological and molecular detection of infection with Mycobacterium leprae in Brazilian six banded armadillos (Euphractus sexcinctus)

Leprosy was recognized as a zoonotic disease, associated with nine-banded armadillos (Dasypus novemcinctus) in the Southern United States of America in 2011. In addition, there is growing evidence to support a role for armadillos in zoonotic leprosy in South America. The current study evaluated twenty specimens of the six-banded armadillo (Euphractus sexcinctus), collected from rural locations in the state of Rio Grande do Norte (RN), Brazil for evidence of infection with Mycobacterium leprae. Serum was examined using two "in-house" enzyme-linked immunosorbent assays (ELISAs) and via two commercially available (ML flow and NDO-LID®) immunochromatographic lateral flow (LF) tests, for detection of the PGL-I and/or LID-1 antigens of the bacterium. The presence of M. leprae DNA in liver tissue was examined using the multi-copy, M. leprae-specific repetitive element (RLEP), as target in conventional and nested PCR assays. Molecular and anti-PGL-I-ELISA data indicated that 20/20 (100 %) of the armadillos were infected with M. leprae. The corresponding detection levels recorded with the LF tests were 17/20 (85 %) and 16/20 (85 %), for the NDO-LID® and ML flow tests, respectively. Our results indicate that, in common with D. novemcinctus, six banded armadillos (a species hunted and reared as a food-source in some regions of Brazil, including RN), represent a potential reservoir of M. leprae and as such, their role in a possible zoonotic cycle of leprosy within Brazil warrants further investigation.