scholarly journals Amino acid availability in poultry—in vitro and in vivo measurements

1999 ◽  
Vol 50 (5) ◽  
pp. 889 ◽  
Author(s):  
V. Ravindran ◽  
Wayne L. Bryden
Keyword(s):  
Amino Acid ◽  
Protein Quality ◽  
Poultry Feed ◽  
In Vitro Assays ◽  
Total Amino Acid ◽  
Amino Acid Availability ◽  
Amino Acid Contents ◽  
In Vivo Growth

Methodology to evaluate the protein quality or amino acid availability in feed ingredients for poultry using in vitro (enzymic, chemical, or microbiological assays), indirect in vivo (plasma amino acid assays), or direct in vivo (growth or digestibility assays) measurements has been reviewed. The specific applications and limitations of these methods are examined. In vitro assays are useful in providing information on heat damage in selected protein sources under defined conditions, and on relative ranking of different samples, but they cannot form the basis of practical feed formulations. While growth assays remain the only direct means of confirming nutritional relevance of values obtained by other procedures, in vivo digestibility assays appear to be most useful, at present, to estimate amino acid availability. Amino acid digestibility assays in poultry should be based on the analysis of digesta from the terminal ileum rather than excreta, because of the variable and modifying effects of hindgut microflora. Techniques used to estimate endogenous amino acid losses in poultry are discussed. The needs for correction of endogenous losses in amino acid digestibility calculations and the relative merits of apparent and true digestible amino acid systems are still being debated. It is, however, clear that both digestible amino systems are superior to the total amino acid system currently employed to formulate practical diets. Digestible amino acid values are likely to form the basis of poultry feed formulations in the future. In particular, there is an urgent need for more precise information on the variation in digestible amino acid contents of locally grown ingredients and on the factors causing this variation (e.g. variety, location, season, agronomic practices, processing, etc.).

scholarly journals Enzyme-Assisted Release of Antioxidant Peptides from Porphyra dioica Conchocelis

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 249
Author(s):  
Filipa B. Pimentel ◽  
Marlene Machado ◽  
Maria Cermeño ◽  
Thanyaporn Kleekayai ◽  
Susana Machado ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Amino Acid ◽  
Dry Weight ◽  
Essential Amino Acids ◽  
Life Cycle Stage ◽  
In Vitro Assays ◽  
Total Amino Acid ◽  
Amino Acid Profiles ◽  
Amino Acid Contents

The conchocelis life cycle stage of P. dioica represents an unexplored source of bioactive compounds. The aim of this study was to generate and characterise, for the first time, hydrolysates of conchocelis using a specific combination of proteases (Prolyve® and Flavourzyme®). Hydrolysate molecular mass distribution and free amino acid contents were assessed, and the antioxidant activity was determined using a range of in vitro assays. The protein content and the total amino acid profiles of conchocelis were also studied. Conchocelis contained ~25% of protein (dry weight basis) and had a complete profile of essential amino acids. Direct sequential enzymatic treatment modified the profile of the generated compounds, increasing the amount of low molecular weight peptides (<1 kDa). There was a significant improvement in the antioxidant activity of the hydrolysates compared with the control (up to 2.5-fold), indicating their potential as a novel source of antioxidant ingredients.

scholarly journals Revealing the in vivo growth and division patterns of mouse gut bacteria

2020 ◽  
Vol 6 (36) ◽  
pp. eabb2531
Author(s):  
Liyuan Lin ◽  
Qiuyue Wu ◽  
Jia Song ◽  
Yahui Du ◽  
Juan Gao ◽  
...  
Keyword(s):  
Amino Acid ◽  
Gut Microbiota ◽  
Growth Dynamics ◽  
Gut Bacteria ◽  
Metabolic Labeling ◽  
Taxonomic Identification ◽  
In Vivo Growth

Current techniques for studying gut microbiota are unable to answer some important microbiology questions, like how different bacteria grow and divide in the gut. We propose a method that integrates the use of sequential d-amino acid–based in vivo metabolic labeling with fluorescence in situ hybridization (FISH), for characterizing the growth and division patterns of gut bacteria. After sequentially administering two d-amino acid–based probes containing different fluorophores to mice by gavage, the resulting dual-labeled peptidoglycans provide temporal information on cell wall synthesis of gut bacteria. Following taxonomic identification with FISH probes, the growth and division patterns of the corresponding bacterial taxa, including species that cannot be cultured separately in vitro, are revealed. Our method offers a facile yet powerful tool for investigating the in vivo growth dynamics of the bacterial gut microbiota, which will advance our understanding of bacterial cytology and facilitate elucidation of the basic microbiology of this gut “dark matter.”

scholarly journals Mechanisms of heat damage in proteins

1975 ◽  
Vol 34 (2) ◽  
pp. 325-337 ◽  
Author(s):  
Shirley A. Varnish ◽  
K. J. Carpenter
Keyword(s):  
Heat Treatment ◽  
Amino Acid ◽  
Amino Acid Composition ◽  
Close Agreement ◽  
Total Amino Acid ◽  
Lysine Content ◽  
Chemical Analyses ◽  
Chick Growth ◽  
Amino Acid Availability ◽  
Amino Acid Contents

1. The preparation of a propionylated protein is described, and the effects of this treatment on amino acid composition and availability are compared with the effects of severe heat treatment (autoclaving) of a protein.2. Using chemical analyses, changes exceeding 5% for total tyrosine, histidine, methionine and cystine contents were found after propionylation of the protein. Autoclaving of the protein resulted in changes in total serine, lysine, methionine, cystine and tryptophan contents.3. Microbiological estimates of total amino acid contents were not in close agreement with the chemical estimates for the autoclaved protein.4. Fluorodinitrobenzene-reactive lysine content was reduced to almost zero by propionylation, and by almost 40% by autoclaving.5. Both propionylating and autoclaving protein reduced the amount of lysine available to the chick by about half. In contrast, the availabilities of methionine and tryptophan to the chick were unchanged by propionylation, but were reduced to 0.66 and 0.44 respectively, relative to the untreated protein, by autoclaving.6. Because of the difficulties of obtaining reliable absolute estimates of amino acid availability using chick growth assays, our interpretation of results is mainly based on relative values. The merits of microbiological microbiological estimates of amino acid availability are assessed.

scholarly journals Relation between in vitro and in vivo assessment of amino acid availability

1989 ◽  
Vol 29 (4) ◽  
pp. 495-507 ◽  
Author(s):  
I. Galibois ◽  
L. Savoie ◽  
C. Simoes Nunes ◽  
A. Rérat
Keyword(s):  
Amino Acid ◽  
Amino Acid Availability ◽  
In Vivo Assessment

scholarly journals Amino acid digestibility and poultry feed formulation: expression, limitations and application

2010 ◽  
Vol 39 (suppl spe) ◽  
pp. 279-287 ◽  
Author(s):  
Wayne L. Bryden ◽  
Xiuhua Li
Keyword(s):  
Amino Acid ◽  
Protein Quality ◽  
Poultry Feed ◽  
Data Set ◽  
Ileal Digestibility ◽  
Feed Formulation ◽  
Amino Acid Availability ◽  
Sources Of Variation

The nutritional value or quality of dietary proteins used for poultry feed formulation varies: amino acid availability is an important measure of protein quality. Determination of ileal digestibility values has become the preferred method for estimating amino acid availability. This review discusses the different approaches to the expression of digestibility results, including correction for endogenous loss and the derivatisation of standardised values. Sources of variation in values include, the assay protocol, anti-nutritional factors in feedstuffs and feed milling. Feed formulating with ileal digestibility values should allow higher dietary inclusion levels of protein feedstuffs of lower quality provided that values of different feedstuffs are additive, the age of the bird and the use of feed enzymes are considered. An Australian data set of "ileal digestible amino acid values in feedstuffs for poultry" that has recently be published is described. This overview is intended to stimulate interest in the generation and application of ileal digestibility as a method for estimating amino acid availability in poultry nutrition.

scholarly journals The Sko1p Repressor and Gcn4p Activator Antagonistically Modulate Stress-Regulated Transcription inSaccharomyces cerevisiae

2001 ◽  
Vol 21 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Amparo Pascual-Ahuir ◽  
Ramón Serrano ◽  
Markus Proft
Keyword(s):  
Amino Acid ◽  
Specific Binding ◽  
Ion Homeostasis ◽  
Normal Growth ◽  
Yeast Cells ◽  
Target Sequence ◽  
Acid Uptake ◽  
Amino Acid Availability

ABSTRACT In the transcriptional response of Saccharomyces cerevisiae to stress, both activators and repressors are implicated. Here we demonstrate that the ion homeostasis determinant,HAL1, is regulated by two antagonistically operating bZIP transcription factors, the Sko1p repressor and the Gcn4p activator. A single CRE-like sequence (CRE HAL1 ) at position −222 to −215 with the palindromic core sequence TTACGTAA is essential for stress-induced expression of HAL1. Down-regulation of HAL1 under normal growth conditions requires specific binding of Sko1p to CRE HAL1 and the corepressor gene SSN6. Release from this repression depends on the function of the high-osmolarity glycerol pathway. The Gcn4p transcriptional activator binds in vitro to the same CRE HAL1 and is necessary for up-regulatedHAL1 expression in vivo, indicating a dual control mechanism by a repressor-activator pair occupying the same promoter target sequence. gcn4 mutants display a strong sensitivity to elevated K+ or Na+ concentrations in the growth medium. In addition to reduced HAL1 expression, this sensitivity is explained by the fact that amino acid uptake is drastically impaired by high Na+ and K+concentrations in wild-type yeast cells. The reduced amino acid biosynthesis of gcn4 mutants would result in amino acid deprivation. Together with the induction of HAL1 by amino acid starvation, these results suggest that salt stress and amino acid availability are physiologically interconnected.

scholarly journals The CaaX Proteases, Afc1p and Rce1p, Have Overlapping but Distinct Substrate Specificities

2000 ◽  
Vol 20 (12) ◽  
pp. 4381-4392 ◽  
Author(s):  
Cynthia Evans Trueblood ◽  
Victor L. Boyartchuk ◽  
Elizabeth A. Picologlou ◽  
David Rozema ◽  
C. Dale Poulter ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Single Amino Acid ◽  
In Vitro Assays ◽  
Sequence Motif ◽  
Amino Acid Substitutions ◽  
In The Wild

ABSTRACT Many proteins that contain a carboxyl-terminal CaaX sequence motif, including Ras and yeast a-factor, undergo a series of sequential posttranslational processing steps. Following the initial prenylation of the cysteine, the three C-terminal amino acids are proteolytically removed, and the newly formed prenylcysteine is carboxymethylated. The specific amino acids that comprise the CaaX sequence influence whether the protein can be prenylated and proteolyzed. In this study, we evaluated processing of a-factor variants with all possible single amino acid substitutions at either the a1, the a2, or the X position of the a-factor Ca1a2X sequence, CVIA. The substrate specificity of the two known yeast CaaX proteases, Afc1p and Rce1p, was investigated in vivo. Both Afc1p and Rce1p were able to proteolyze a-factor with A, V, L, I, C, or M at the a1 position, V, L, I, C, or M at the a2 position, or any amino acid at the X position that was acceptable for prenylation of the cysteine. Eight additional a-factor variants with a1 substitutions were proteolyzed by Rce1p but not by Afc1p. In contrast, Afc1p was able to proteolyze additional a-factor variants that Rce1p may not be able to proteolyze. In vitro assays indicated that farnesylation was compromised or undetectable for 11 a-factor variants that produced no detectable halo in the wild-type AFC1 RCE1 strain. The isolation of mutations in RCE1 that improved proteolysis of a-factor-CAMQ, indicated that amino acid substitutions E139K, F189L, and Q201R in Rce1p affected its substrate specificity.

scholarly journals In Vivo Growth of Pseudomonas aeruginosa Strains PAO1 and PA14 and the Hypervirulent Strain LESB58 in a Rat Model of Chronic Lung Infection

2007 ◽  
Vol 190 (8) ◽  
pp. 2804-2813 ◽  
Author(s):  
Irena Kukavica-Ibrulj ◽  
Alessandra Bragonzi ◽  
Moira Paroni ◽  
Craig Winstanley ◽  
François Sanschagrin ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Rat Model ◽  
Growth Curves ◽  
Lung Infection ◽  
In Vitro Assays ◽  
Bacterial Strains ◽  
In Vivo Growth ◽  
Chronic Lung Infection

ABSTRACT Pseudomonas aeruginosa chronic lung infections are the major cause of morbidity and mortality in cystic fibrosis (CF) patients. The P. aeruginosa strains PAO1 and PA14 were compared with the Liverpool epidemic strain LESB58 to assess in vivo growth, infection kinetics, and bacterial persistence and localization within tissues in a rat model of chronic lung infection. The three P. aeruginosa strains demonstrated similar growth curves in vivo but differences in tissue distribution. The LESB58 strain persisted in the bronchial lumen, while the PAO1 and PA14 strains were found localized in the alveolar regions and grew as macrocolonies after day 7 postinfection. Bacterial strains were compared for swimming and twitching motility and for the production of biofilm. The P. aeruginosa LESB58 strain produced more biofilm than PAO1 and PA14. Competitive index (CI) analysis of PAO1, PA14, and LESB58 in vivo indicated CI values of 0.002, 0.0002, and 0.14 between PAO1-PA14, PAO1-LESB58, and LESB58-PA14, respectively. CI analysis comparing the in vivo growth of the PAO1 ΔPA5441 mutant and four PA14 surface attachment-defective (sad) mutants gave CI values 10 to 1,000 times lower in competitions with their respective wild-type strains PAO1 and PA14. P. aeruginosa strains studied in the rat model of chronic lung infection demonstrated similar in vivo growth but differences in virulence as shown with a competitive in vivo assay. These differences were further confirmed with biofilm and motility in vitro assays, where strain LESB58 produced more biofilm but had less capacity for motility than PAO1 and PA14.

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