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Rakić Tamara Pešić Mila Kostić Nikola Andrejić Gordana Fira Djordje Dželetović Željko Stanković Slaviša Lozo Jelena 《Plant and Soil》2021,462(1-2):349-363
Plant and Soil - Flotation tailings represent an extremely unfriendly substrate for plant colonization due to toxic metal concentrations and marked macronutrient deficiencies. The perennial grass... 相似文献
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The aims of this study were to test whether xanthine oxidase, lactoperoxidase, and NO are components of the innate immune system of mammary secretion during active involution in dairy cows, and whether the innate immune system is activated by casein hydrolysates. Our laboratory has shown recently that infusion of CNH into mammary glands induced involution and was associated with earlier increases in the concentrations of components of the innate immune system. Intact casein is inactive and served as control. Half of the glands of 8 Holstein cows scheduled for dry off (approximately 60 days before parturition) were injected for 3 days with a single dose of casein hydrolyzates and the contralateral glands with a single dose of intact casein with the same concentration. Involution elicited marked increases in xanthine oxidase and lactoperoxidase activities, and accumulation of urate and nitrate. NO and H(2)O(2) were constantly produced in the mammary gland secretion. Nitrite formed either by autooxidation of NO or by conversion of nitrate to nitrite by xanthine oxidase was converted into the powerful nitric dioxide radical by lactoperoxidase and H(2)O(2) that is derived from the metabolism of xanthine oxidase. Nitric dioxide is most likely responsible for the formation of nitrosothiols on thiol-bearing groups, which allows an extended NO presence in mammary secretion. Nitrite is effectively converted to nitrate, which accumulated in the range of approximately 25 microM -1 mM from the start of the experiment to the complete involution of glands. The mammary secretion in all glands was bactericidal and bacteriostatic during established involution, and this appeared sooner and more acutely in glands treated with casein hydrolyzates, within 8 to 24 h. It is concluded that xanthine oxidase, lactoperoxidase, and NO are components of the mammary innate immune system that form bactericidal and bacteriostatic activities in mammary secretions. The innate immune system play a major role in preventing intramammary infection during milk stasis and its activation may increase its effectiveness. 相似文献
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Comparison of cell-wall-bound extracellular proteinases (CEPs) from Lactobacillus paracasei (LBP) ssp. paracasei natural isolates BGHN14, BGAR75 and BGAR76 with Lactococcus lactis (LCL) ssp. cremoris Wg2, in their action on αS1-, β- and κ-casein was done. The CEPs of LBP strains were able to degrade αS1- and β-caseins and their caseinolytic specificity depended on the type of buffer used. These CEPs, compared with LCL Wg2,
differ in four amino acid residues in small segments predicted to be involved in substrate binding. The most striking features
of this comparison are the presence of Ala instead of Ser329 and the presence of Thr instead of Asn256 and Ala299, in the subtilisin-like region of the CEP in LBP natural isolates. Additional conservative amino acid substitution Leu to
Ile364 was found. 相似文献
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Kojic M Strahinic I Fira D Jovcic B Topisirovic L 《Canadian journal of microbiology》2006,52(11):1110-1120
In this study, the plasmid content and bacteriocin production of natural isolates of lactococci were investigated. Five bacteriocin producing lactococcal strains (Lactococcus lactis subsp. lactis BGMN1-2, BGMN1-3, BGMN1-5, BGMN1-6, and BGMN2-7) were isolated as nonstarter microflora of semi-hard homemade cheese and characterized. All isolates contained a number of plasmids. It was shown that lcnB structural genes for bacteriocin lactococcin B were located on large plasmids in all isolates. In the strains BGMN1-3 and BGMN1-5 proteinase prtP genes collocated with lcnB. Furthermore, these strains produced two additional bacteriocins (LsbA and LsbB) with genes responsible for their production and immunity located on the small rolling circle-replicating plasmid pMN5. Using deletion experiments of pMN5, minimal replicon of the plasmid and involvement of a bacteriocin locus in plasmid maintenance were identified. In addition, plasmid curing experiments showed that genes for catabolism or transport of 10 carbohydrates in the strain BGMN1-5 were plasmid located. 相似文献
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Pastar I Fira D Strahinić I Krstić K Begović J Topisirović L Jovanović G 《Folia microbiologica》2006,51(6):535-540
The region of the prtR gene coding for the active site of PrtR proteinase was detected in natural isolates of lactobacilli, previously determined as Lactobacillus rhamnosus. This region was present in all L. rhamnosus strains with proteolytic activity. The PCR primers used were constructed on the basis of the sequence of the catalytic domain of the prtR proteinase gene. These primers generated in colony-PCR procedure specific 611 1-bp product with DNA from natural isolates of L. rhamnosus. No PCR amplifications using these primers were obtained for closely related bacteria of genus Lactobacillus, regardless of their proteolytic activity. In addition, these primers could be used singly or in multiplex PCR together with the Lactobacillus genus-specific primers. Compared with the other proteinases within the genus Lactobacillus (PrtP, PrtB and PrtH) which retained the activity in cell-free proteinase extracts, PrtR proteinase showed proteolytic activity only under in vivo conditions (whole cells of the producing strains). 相似文献
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Jelena Begovic Djordje Fira Amarela Terzic-Vidojevic Ljubisa Topisirovic 《Central European Journal of Biology》2010,5(1):103-110
Lactobacilli represent normal commensals of the human body, particularly in the gut and vagina where they protect these environments
from incoming pathogens via a variety of mechanisms. The influence of the carbohydrate source present in reconstituted MRS growth medium on the different
cell properties of two Lactobacillus rhamnosus strains were examined. Two human vaginal isolates, BGHV719 and exopolysaccharide producer strain BGHV954 were analyzed. The
results demonstrated that unlike in reconstituted MRS with glucose as a carbon source, the presence of fructose, mannose,
or rhamnose, significantly reduced cell surface hydrophobicity of both strains. In addition, differences in cell wall protein
composition of L. rhamnosus BGHV719 and alterations in colony mucoidity of L. rhamnosus BGHV954 were also demonstrated. Light and SEM microscopy revealed differences on the cellular level when BGHV719 was cultivated
in the presence of different sugars. The results of this study point out the importance of complex relationships between growth
medium composition and the different aspects of bacterial behavior, and call for more detailed analyses of versatile bacterial
responses to the changes in the environment, including vaginal ecosystem. This is especially important since lactobacilli
are amongst the most widely used of probiotics. 相似文献
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Mammary involution is triggered by local stimuli, but the precise mechanism has not been defined. Milk stasis accumulate local signals, which makes the tight junctions (TJ) leaky. The aim of the study was to check the hypothesis that casein hydrolyzates (CNH) compromise TJ integrity and dry up milk secretion. A single dose of CNH transiently (12 to 24 h) compromised TJ integrity in the treatedudder. This was associated by a transient (12 to 96 h) decline in milk secretion. No such changes were recorded in the contralateral gland that served as a control. Four repeated doses of CNH after each milking caused drastic changes in mammary secretion and composition, which were associated with irreversible cessation of milk secretion within 96 h. No such changes were recorded in goats treated with de-phosphorylated casein (control). We conclude that CNH are the milk-borne factors that cause the disruption of TJ integrity and induction of involution, and that the serine-Ps in the CNHs are essential for the excretion of biological activity. 相似文献
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Altered translational fidelity of a Salmonella typhimurium LT2 mutant resistant to the aminoglycoside antibiotic neamine 总被引:1,自引:0,他引:1
A neamine-resistant mutant of Salmonella typhimurium LT2 with altered translational fidelity was isolated. The phenomenon was expressed in severe restriction of amber suppressor activity in vivo as well as in decreased misreading of poly(U) RNA in vitro. The mutation conferring resistance to neamine was mapped at 72 min on the Salmonella genetic map, where some of the ribosomal genes have already been mapped. This location indicates that the neamine-resistant phenotype as well as an altered translational fidelity could be a consequence of an alteration of the ribosomal structure. 相似文献