Review: Production factors affecting the quality of chicken table eggs and egg products in Europe.

The hen's egg (Gallus gallus) is an animal product of great agronomic interest, with a world production of 70.9 million tonnes in 2018. China accounted for 35% of world production, followed by North America (12% of world production), the European Union (7.0 million tonnes, 10% of world production) and India (5.0 million tonnes, 7% of world production). In France, 16-17 billion eggs are produced annually (14.5 billion for table eggs) and more than 1 200 billion worldwide. In 2019, egg production increased by 3.3% compared to 2018, mainly due to the increase in Asian production, which has risen by 42% since 2000. Chicken eggs are widely used either as a low-cost, high nutritional quality food cooked by the consumer (more than 100 billion eggs consumed in Europe), or incorporated as an ingredient in many food products. The various production methods have changed considerably over the last 15 years with the consideration of animal welfare and changes in European regulations. In Europe, fewer and fewer eggs are produced in confinement and there has been a strong growth in the number of systems giving access to an outdoor run. In this review, we describe the different ways in which eggs are produced and processed into egg products to meet the growing demand for ready-to-use food products. We analyse the effect of this evolution of hen-rearing systems on the set of characteristics of eggs and egg products that determine their quality. We describe the risks and benefits associated with these new production methods and their influence or lack of influence on commercial, nutritional, microbial and chemical contamination risk characteristics, as well as the evolution of the image for the consumer. The latter covers the ethical, cultural and environmental dimensions associated with the way the egg is produced.

In vitro digestion of complex foods: How microstructure influences food disintegration and micronutrient bioaccessibility.

Digestion is a mechanical and chemical process that is only partly understood, and even less so for complex foods. In particular, the issue of the impact of food structure on the digestion process is still unresolved. In this study, the fate of four micronutrient-enriched foods with identical compositions but different microstructures (Custard, Pudding, Sponge cake, Biscuit) was investigated using the 3-phase in vitro model of human digestion developed by the INFOGEST network. Matrix disintegration and hydrolysis of macronutrients (proteins, lipids and carbohydrates) were monitored during the three phases of digestion using biochemical techniques, size-exclusion chromatography, thin-layer chromatography and gas chromatography. Micronutrient release (vitamin B9 and lutein) was monitored using reverse-phase chromatography. Food structure did not greatly influence macronutrient hydrolysis, except for lipolysis that was four-times higher for Biscuit compared to Custard. However, the bioaccessibility of both micronutrients depended on the food structure and on the micronutrient. Vitamin B9 release was faster for Biscuit and Sponge cake during the gastric phase, whereas lutein release was higher for Custard during the intestinal step. Extensive statistical analysis highlighted the impact of food structure on the digestion process, with different digestion pathways depending on the food matrix. It also made it possible to characterise the gastric step as a predominantly macronutrient solubilisation phase, and the intestinal step as a predominantly hydrolysis phase.

A role for T cell-derived interleukin 22 in psoriatic skin inflammation.

Interleukin (IL)-22 is a T cell-derived cytokine that has been reported recently to induce cutaneous inflammation in an experimental murine model of psoriasis, and to induce in vitro an inflammatory-like phenotype. In the present study, we assessed the presence of IL-22 and the IL-22 receptor 1 (IL-22R1) in skin lesions, skin-derived T cells, as well as IL-22 levels in sera from patients with psoriasis. IL-22R1 and IL-10R2 transcripts are expressed at a similar level in psoriatic and healthy skin. In contrast, IL-22 mRNA expression was up-regulated in psoriatic skin lesions compared to normal skin, whereas IL-22 mRNA levels in peripheral blood mononuclear cells from psoriatic patients and normal subjects were similar. Circulating IL-22 levels were significantly higher in psoriatic patients than in normal subjects. T cells isolated from psoriatic skin produced higher levels of IL-22 in comparison to peripheral T cells isolated from the same patients. IL-10 was expressed at similar levels in skin biopsies and peripheral blood mononuclear cells of psoriatic patients and normal subjects. Finally, we show here that supernatants of lesional psoriatic skin-infiltrating T cells induce an inflammatory response by normal human epidermal keratinocytes, resembling that observed in psoriatic lesions. Taken together, the results reported in this study indicate that IL-22 is a cytokine produced by skin-infiltrating lymphocytes that is potentially involved in initiation and/or maintenance of the pathogenesis of psoriasis.

Hen egg white fractionation by ion-exchange chromatography.

Major hen egg white proteins have been widely studied for their functional properties but these studies still are unable to explain, alone, all of the biological properties of hen egg white. Hence, it is still interesting to produce pure and non-altered proteins to improve our knowledge on the biological properties of hen egg white. Presently, identification and characterization of both bioactive peptides and minor proteins from hen egg white is essential work for progressing in the understanding of hen egg white biological properties. With this objective in mind, a new process for a complete "mucin free" hen egg white fractionation based on ion exchange chromatography is proposed. "Mucin free" egg white is fractionated into six different fractions. Four of them are high-recovery yield purified fractions of lysozyme, ovotransferrin, ovalbumin and flavoprotein. The two other fractions are enriched in recently detected minor proteins in hen egg white.

Cloning and characterization of HEP21, a new member of the uPAR/Ly6 protein superfamily predominantly expressed in hen egg white.

Using two-dimensional (2D)-PAGE, partial protein internal sequencing, and PCR with degenerate primers, we cloned a novel cDNA named HEP21 from hen egg white. The 0.5-kb cDNA encodes a 106 amino acid protein with a cysteine spacing pattern suggesting that HEP21 is a new member of the uPAR/CD59/Ly-6/ snake neurotoxin superfamily. The closest homology of HEP21 is to mouse Ly-6C. Unlike most members of this protein family, HEP21 is not glycosylphosphatidylinositol (GPI)-anchored but is a secreted protein, as indicated by its localization and the presence of a signal peptide in its sequence. Moreover, HEP21 appears as an original member of this protein superfamily because it is predominantly expressed in a tissue, i.e., the oviduct, and especially the magnum where the egg white components are secreted.

Comparison of different electrophoretic separations of hen egg white proteins.

The hen egg white protein composition has not yet been fully defined. To improve the knowledge of this biological fluid, the most usual and recently developed electrophoretic methods have been used: SDS-PAGE, native-PAGE, isoelectric focusing (IEF), and 2-dimensional electrophoresis (2DE). Seven of the major known proteins were thus identified in at least one electrophoretic system. Isoforms of ovotransferrin, ovalbumin, and ovomucoid were visualized when pI was used for the separation. Two-dimensional electrophoresis allowed separation of a very large number of spots. In each of the four systems, some components were revealed but not identified, and unknown spots were particularly numerous with 2DE. With this technique, many spots corresponding to small acidic proteins were highlighted, among which was the Ch21 protein, whose presence in hen egg white was thus confirmed. This study thus constitutes, to our knowledge, the first proteomic investigation of hen egg white.

Simple rapid procedure for preparation of large quantities of ovalbumin.

A simple rapid procedure for preparation of large quantities of highly purified homogeneous ovalbumin from egg white by using an anion exchanger is described. It is based on the principle of frontal chromatography. The volume of "mucin-free" egg white loaded onto the column was determined in order to exceed resin capacity. Thus, competition between proteins for resin sites was created. Owing to its high negative charge density, ovalbumin drives other egg white proteins from the column progressively. Two hundred and fifty milliliters of Q-Sepharose FF gel eluted isocratically with 0. 5 M NaCl extracted 9.55 g of ovalbumin with a purity rate of 83%. A 6.75 g amount of ovalbumin, with a purity rate of 94%, was recovered with an isocratic elution program using 0.14 M NaCl. Purified ovalbumins were compared by electrophoresis and analytical chromatography with other ovalbumin preparations.

High intensity pulsed electric fields applied to egg white: effect on Salmonella Enteritidis inactivation and protein denaturation.

High-intensity electric fields have been successfully applied to the destruction of Salmonella Enteritidis in diaultrafiltered egg white. The effects of electric field strength (from 20 to 35 kV x cm(-1)), pulse frequency (from 100 to 900 Hz), pulse number (from 2 to 8), temperature (from 4 to 30 degrees C), pH (from 7 to 9), and inoculum size (from 10(3) to 10(7) CFU x ml(-1)) were tested through a multifactorial experimental design. Experimental results indicate that, for Salmonella inactivation, the electric field intensity is the dominant factor with a strongly positive effect, strengthened by its positive interaction with pulse number. Pulse number, temperature, and pH have also significant positive effects but to a lesser extent. In the most efficient conditions, the pulsed electric field (PEF) treatment is capable of 3.5 log10 reduction in viable salmonellae. Simultaneously, the measure of surface hydrophobicity does not indicate any increase after PEF treatment. These results suggest that no protein denaturation occurs, unlike what is observed after comparable heat treatment in terms of Salmonella inactivation (55 degrees C for 15 min).

cDNA cloning, structural organization, and expression of the sheep NRAMP1 gene.

Mouse resistance to several intracellular pathogens including Mycobacteria, Leishmania, and Salmonella is under the control of the Chromosome (Chr) 1 Natural Resistance Associated Macrophage Protein I gene (Nramp1). This gene could have an economic and health importance for domestic animals and humans as well. Therefore, equivalents of the NRAMP1 gene have been cloned by several research groups in various animal species. To study in sheep the influence of the NRAMP1 gene on the susceptibility to intracellular pathogens induced diseases, we have cloned the sheep NRAMP1 cDNA by screening a splenic cDNA library. The genomic organization of the sheep NRAMP1 gene was then determined by sequencing the exon/intron boundaries. The transcription start points (tsp) from the NRAMP1 mRNA have been located with primer extension experiments. RT-PCR reactions have been used to determine the profile of mRNA expression of this gene.

Genomic organization of the sheep immunoglobulin JH segments and their contribution to heavy chain variable region diversity.

The sheep immunoglobulin heavy chain Igh-J locus has been characterized in order to determine the genomic organization of JH segments and their contribution to heavy chain diversity. The locus contains six segments, of which two are functional and four are apparently pseudogenes. These segments span a 1.8 kilobase (kb) region. The distance between JH-ps4 (the 3'-most segment) and the first domain of the mu-chain encoding constant gene is about 5 kb. The two functional JH segments have a standard upstream recombination signal sequence, including heptamer and nonamer sequences separated by a 22-23 nucleotide spacer, and end with a RNA donor splice site. These two segments possess all the characteristic JH invariant residues and are found in expressed mu heavy chain variable regions. The 5' functional JH1 segment is used in more than 90% of the cDNAs sequenced to date. The contribution of JH segment germline multiplicity to variable regions diversity appears therefore to be minimal. Comparison with other mammalian JH segments shows that all loci are very closely related and probably have evolved from a common ancestral locus.

The sheep Ig variable region repertoire consists of a single VH family.

Nine germ-line Ig heavy chain variable (VH) segments (including three pseudogenes) were isolated from a genomic DNA library, and the other six were obtained by PCR, using 5'and 3' primers deduced from the first three. They appear to belong to a homogeneous VH gene family, with >80% sequence identity. This sheep VH gene family is related to the human VH4 family and to the murine VH1 subgroup (clan II). Southern blot analysis shows a maximum of 10 positive restriction fragments; therefore, the nine VH genes isolated probably constitute the major part of the repertoire. Thirty-one expressed mu variable regions (and one gamma 1 variable region) were obtained from adult spleen by either cDNA cloning or anchored reverse transcriptase-PCR; they are >80% similar to each other (in their leader to framework 3 regions) and to the germ-line sequences as well. The sheep VH repertoire thus seems to derive from a small (approximately 10 members) germ-line gene family, and its diversification must rely chiefly on junctional (D and/or N regions) diversity and somatic hypermutations.

Selective separation of tryptic beta-casein peptides through ultrafiltration membranes: Influence of ionic interactions.

Peptide separation by selective membrane filtration has numerous potential applications such as production of peptides with biological activities or spectific enrichment in compounds acting as flavoring agents or as growth factors required by the fermentation industry. The retention of peptides arising from tryptic hdroysis of beta-casein using an M5 Carbosep membrane (molecular wieght cutoll = 10,000 D) has been studied. The peptides with known sequences were characterized by their molecular weight, isoelectric point, and hydrophobicity. Our experiments highlighted that their transmission involves mechanisms other than size exclusion as developed elsewhere. The effect of ionic interactions between peptides and membrance has been investgated by vrying pH, ionic strength of bulk, and electric potential of filtering material. The charge of both peptides and membrane plays an important role in the transmission, particularly with small size and high or lkow isoelectric point. Then, peptides with the same sign as the membrane have lower transmission than expected from the size xclusion model, whereas peptides with opposite sign have higher trnsmission than expected, and even higher than 1 with some of them. (c) 1995 John Wiley & Sons, Inc.

[Relevance of infectious diseases in a pediatric practice]. / Relevanz von Infektionskrankheiten in einer Kinderarztpraxis.

According to official statistics, infectious diseases only play a minor role in German children. To test this assumption, 1685/3405 charts of a private pediatrician were randomly chosen for further evaluation. 1112/1685 children had been seen in the office during the study period, 934 of them because of an infectious disease (83%). 700/934 charts were further reviewed in a standardized fashion. Pharyngo-tonsillitis was the most frequent diagnosis (18.6%), followed by (non-obstructive) bronchitis (18.5%), infectious diseases of the skin (10.2%) and Otitis media (9.9%). Typical "childhood diseases" (measles, mumps, rubella, varicella) only played a minor role. For some diseases age-specific as well as seasonal changes in incidence could be observed. These data suggest that infectious diseases largely contribute to the morbidity in German children. Prospective epidemiological trials are needed to obtain reliable data for appropriate public health decisions.

Isolation and sequence of a cDNA coding for the immunoglobulin mu chain of the sheep.

A sheep cDNA library was screened with a human C mu probe, and the complete nucleotide sequence of a 1923 nt cDNA was determined. It contains sequences corresponding to all the exons (VH, DH, JH, CH1, CH2, CH3 and CH4) characteristic of the immunoglobulin mu heavy chain regions. The deduced amino acid sequence shows a percentage of identical residues in the range 65-45% when compared with the mu chains of various species. The VH region of this clone is clearly related to a group of genes that includes mouse VH36-60 and VHQ52, human VH2, VH4 and VH6 gene families and Xenopus VHII gene families. The constant region shows an unusual repartition of cystein and proline residues at the beginning of the CH2 domain, that may result in a molecule with enhanced stability and reduced flexibility.

Separation of beta-casein peptides through UF inorganic membranes.

Ultrafiltration of peptide mixtures is studied under various operating conditions (transmembrane pressure, tangential flow-rate) using two ultrafiltration inorganic membranes M5 and M1 with molecular weight cut-offs, MWCO 10 and 70 kD, respectively. It is shown that the separation of peptides is controlled by a dual mechanism: size exclusion and electrostatic repulsion. When the ionic strength is high enough to screen out the electrostatic interactions, experimental data are in good agreement with a sieving model developed to estimate the intrinsic transmission from the molecular weight of a component and from the MWCO of the membranes. Although the transmission so found is altered by concentration polarisation and pore blocking mechanisms, the results explain the apparent low transmission of peptides by ultrafiltration membranes. If the ionic strength of the fluid is low, electrostatic interactions can influence the transport phenomena, provided that the molecules are highly charged (at pHs away from the pI). For attractive interactions, an apparent partition coefficient larger than 1 is observed. Otherwise, the transmission is lower than predicted by the sieving theoretical equation, as if the partition coefficient were smaller than 1.

Primary structure of a monoclonal kappa chain in myeloma with light chain deposition disease.

Previous data suggest that structural abnormalities of immunoglobulin light chains may be responsible for non-amyloid light chain deposition disease (LCDD). We report on the complete primary sequence deduced from complementary (c)DNA analysis of a normal-sized kappa chain in a case of myeloma-associated LCDD. The patient's urine contained a kappa type Bence-Jones protein made of monomers and dimers of an unglycosylated kappa chain. The bone marrow myeloma cells contained intracellular kappa and gamma chains by immunofluorescence. Biosynthesis experiments showed the production of normal-sized gamma chains and of kappa chains with the same apparent molecular mass (Mr) in SDS gels as the urinary kappa chain (26,000-27,000). These kappa chains were secreted as assembled IgG molecules and as a large excess of free monomers and dimers. The complete sequence of two identical cDNA clones derived from a normal-sized kappa messenger RNA indicated that this kappa chain belonged to the rare V kappa IV subgroup. The kappa mRNA had an overall normal structure made up of the V kappa IV sequence rearranged to J kappa 1 and followed by a normal constant exon of the Km(3) allotype. The variable region differed from the V kappa IV-J kappa 1 germline sequence by 17 amino acid substitutions. The peculiar sequence of the variable region of this kappa chain of a rare subgroup might relate to its tissue deposition.

Production of an abnormal mu chain with a shortened VHIV subgroup variable region in a Burkitt's lymphoma cell line.

The Burkitt's lymphoma cell line Ly66 produces a short mu chain which lacks 4 kDa in apparent molecular mass. Study of the corresponding messenger RNA showed it to be 0.3 kb shorter than normal mu transcripts. The cDNA sequence of the mu transcripts began by a short VH region consisting of the first one-third of a VHIV subgroup gene segment. It was followed by a normal mu constant region. This VH region coded for 38 amino acids, thus differing from two truncated VHIV regions previously reported in other Burkitt's lymphoma cell lines, which were interrupted at codon +26 by an alternate splicing event. In addition, the Ly66 variable sequence bore several point mutations and contained two potential N-glycosylation sites.

Immunoglobulin light chain transcripts with altered V regions in Burkitt's lymphoma cell lines producing short mu chains.

The Burkitt lymphoma cell lines Ly91, Ly47 and Ly66 produce short mu chains in the absence of associated light (L) chains. mu mRNA lack two-thirds of the variable (V) region due to an alternate splicing event that takes place within V genes. L chain genes were found to be rearranged in these lines and to lead to transcripts with altered V regions. Although these abnormal transcripts displayed specific abnormalities in each cell line, they shared some features, including large deletions involving the V-J junction. In one cell line, L chain transcripts made up of either V kappa I subgroup gene J kappa 3 or V kappa IV gene-J kappa 4 recombination products bore a similar alteration: the donor splice site of the rearranged J kappa segment was modified, leading to the alternate use of the donor site of either the leader peptide exon or the next 3' unrearranged J kappa segment.

Alternate splice sites within the human VH gene coding sequences lead to truncated Ig mu-chains.

The Burkitt's lymphoma cell lines JBL2 and Ly91 contain intracytoplasmic mu chains without L chain by immunofluorescence. These mu chains and the corresponding cDNA are abnormally short. Detailed analysis of the productive H chain alleles showed that the cell lines JBL2 and Ly91 use a VHIV and a VHIII subgroup gene, respectively. In both cell lines, the 3' part of the V exon was markedly abnormal and contained several stop codons. Point mutations affected the JH6 donor splice site in the JBL2 gene, precluding normal splicing into C mu. Although the JH2 splice site was unmodified in Ly91, it was not used. As in JBL2, splicing occurred at an alternate splice site present 5' of these alterations, thus removing all these abnormalities from the mature transcripts. This alternate splicing explains the presence in both cell lines of truncated mRNA and proteins lacking two-thirds of the V region.

Burkitt's lymphoma cell lines producing truncated mu immunoglobulin heavy chains lacking part of the variable region.

Burkitt's lymphoma cell lines Ly91, Ly47 and JBL2 contained intracytoplasmic mu chains without light chains and variably expressed membrane mu chains. All three cell lines produced similarly truncated heavy chains with an apparent molecular mass of 64 kDa instead of the normal 74 kDa. Both the intracellular and secreted forms of the mu chains were similarly truncated. The membrane and the secreted forms of mu mRNAs were shorter than normal. The cDNAs contained a leader sequence, followed by about one third of a variable region (VH), then by the constant region (C mu). Interruption of the variable region took place near the end of the framework region 1 (FR 1) in Ly 47 and JBL2, and within the complementarity determining region 1 (CDR1) in Ly91. In the three lines, the joining between VH and C mu maintained the normal open reading frame throughout the variable and constant regions.