The organization of animal cells in vivo can be categorized as being either epithelial or mesenchymal. Inter-conversions between these two states, epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET), often represent key events in animal development and pathogenesis. The molecular and cellular mechanisms by which cell-cell and cell-substrate interactions are governed during EMT/MET have been examined extensively. Recent studies have also shown that EMT/MET is implicated in the acquisition of stemness in cancer cells and is accompanied by changes in epigenetic modifications. Ongoing progresses in regenerative medicine suggest that morphological and physical changes can facilitate somatic cell reprogramming and help achieve stemness. In this review, we will describe the principles of EMT/MET, their roles in cancer and normal animal development, and their relationship to stemness. We will conclude by emphasizing that studying cell shape changes in development is important for mechanistic understanding of how EMT/MET contributes to cell lineage conversion in cancer research and therapeutic medicine.
Chicken embryo manipulation, especially germline manipulation, recently has progressed greatly by devising important experimental techniques, such as embryo culture and primordial germ cell (PGC) manipulation. Embryogenesis and embryonic development in chickens are affected by gravity at various developmental stages. Freshly collected PGC population seems to contain germline-competent PGCs in opposite-sex germline chimeric chickens, but these PGCs probably disappear from the population during in vitro culture. Long-term culture of chicken PGCs makes it possible to transfer foreign DNA into the germline and also contributes to preserving avian genetic resources. Propagation of endangered avian species could become possible via interspecies germline chimeras. Development of techniques producing somatic cell-derived offspring could also be useful to avian germline manipulation.
The present study was conducted to investigate whether dietary sanguinarine (Sangrovit®, SGV) could affect growth performance, relative organ weigths, gut microbiota, serum cholesterol levels, and malondialdehyde contents of leg meat in broiler chickens. A total of 840 day-old male broiler chicks (Ross breed) was randomly placed on 28 floor pens with rice straw as a bedding and subjected to one of four experimental diets; corn-soybean meal based control diet, the control diet added with avilamycin at 10 ppm as growth promoter (AGP) and SGV at the level of 20 (SGV20) or 50 ppm (SGV50). The final body weight (BW), daily BW gain, and feed conversion ratio (FCR) were significantly improved (P<0.05) in broiler chickens fed either AGP, SGV20 or SGV50 compared with the control diet-fed chickens. Compared with the control group, relative jejunal weight was significantly lowered (P<0.05) in SGV20-fed chickens and relative jejunal or ileal length was significantly increased (P<0.05) in all SGV-fed chickens. Dietary SGV20, but not AGP, altered gut microbiota (especially increase in cecal lactic acid bacteria) compared with the control diet-fed chickens. Total cholesterol of broiler chickens fed on a diet containing SGV20 or SGV50 vs. the control diet was significantly reduced. Finally, the content of malondialdehyde in thigh meats as an indicator of lipid peroxidation was significantly lowered (P<0.05) by dietary SGV compared with that seen in the control chickens. In conclusion, our study clearly reveals that supplementation of SGV into the broilers’ diet at 20 or 50 ppm improved growth performance and altered various biological and physiological parameters such as relative organ weights, serum cholesterol levels, gut microbiota, and meat qualities in broiler chickens.
When tryptophan is glycated with glucose, it results in forming two types of glycated tryptophan, glucose-tryptophan Amadori product and (1R, 3S)-1-(D- gluco-1,2,3,4,5-pentahydroxypentyl)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (PHP-THβC). Hyperglycemia and high body temperature in avian species are supposed to elevate the concentration of glycated tryptophan in the plasma of chickens fed tryptophan-excess diets. However, plasma concentrations of both glucose-tryptophan Amadori product and PHP-THβC have not been determined so far. Young chickens were fed tryptophan-excess diets (1, 2 or 3% excess) for 14 or 21 days, and plasma concentrations of two types of glycated tryptophan were measured using liquid chromatograph mass spectrometer (LC/MS). In the present study, we successfully detected and quantified both glucose-tryptophan Amadori product and PHP-THβC in the plasma, which revealed that plasma concentrations of glucose-tryptophan Amadori product and PHP-THβC were approximately 1 and 2-4μM, respectively. Furthermore, plasma concentrations of glycated tryptophan compounds significantly correlated to that of plasma tryptophans, and total amount of both glycated tryptophan compounds was almost 10% of plasma tryptophan.
Intracerebroventricular injection of glucose can induce a sedative effect in chicks under social isolation stress. In addition, central injection of glucose improves memory formation in chicks in the passive avoidance task. In the present study, we confirmed that intracerebroventricular injection of glucose modified aspartate, arginine, glutamate, β-alanine, glycine and serine-ortho-phosphate levels of the telencephalon which are known to induce sedative effects in chicks. In addition, not only glutamate in the telenephalon, one of whose receptors is involved in the formation of memory in chicks, but also its metabolite glutamine was affected. These results suggest that some types of amino acid metabolism may be linked to the functions of glucose in the brain, attenuate the stress response and improve memory formation in chicks.
The effect of various branched-chain amino acids (BCAA : isoleucine, leucine, valine) on embryo growth and the hatching time of fertilized eggs of chickens was examined. Before the onset of egg incubation, one of BCAA was injected into fertilized eggs. The amount of each BCAA administrated into eggs was equal to 1% of each amino acid exits in the egg. On day 14 of incubation, the weight of embryos was measured. On day 21, the hatching time was recorded, and body weight of chicks at birth was measured. The in ovo administration of BCAA increased the weight of whole embryo compared to the control. Compared to the control, the in ovo administration of leucine and valine significantly accelerated the hatching time. There were no significant differences in body weight of newly hatched chicks among all treatments. It was concluded that the in ovo administration of BCAA, especially leucine and valine, could accelerate embryo growth resulting in the acceleration of hatching time of chicks.
Activation of the right hemispheric neurotransmitter systems is related to negative emotion and stress in mammals, but this relationship is not fully known in birds. The effect of the presence of sawdust litter on behavior and brain monoamine laterality in isolation stressed chicks (6 days old) was investigated. Although there was no significant difference in peep, movement distance in litter group chicks (n＝7) was significantly longer than that in non-litter group chicks (n＝6) during 15 min isolation test (P<0.01). The laterality index (a measure of central monoamine laterality indicating the predominance of right over left hemispheric activity) of serotonin (5-HT) in intact chicks (no stress manipulation; n＝8) was higher than those in chicks with and without litter substrate (P<0.01). The value of the dopamine (DA) metabolite ratio in intact chicks was lower than that in the non-litter group chicks (P<0.05), but was not low in the litter group chicks. In contrast, there was no significant difference in the levels of the 5-HT metabolite ratio among the groups. In addition, the laterality index of the ratio correlated negatively with the number of peeps in chicks with sawdust litter (P<0.01). It has been suggested that emotional processing in the right hemisphere might be optimal with DAergic and/or serotonergic lateralization, whereas either a decrease or an increase in this lateralization might be reinstated in animals suffering stress. In addition, the present results imply that sawdust litter may attenuate isolation stress that induces anxiety in chicks, and that the laterality index of the DA metabolite ratio may be effective in estimating positive emotional change.
The PRL regulatory element binding protein (PREB) is a transcription factor that specifically binds to a Pit-1 binding element in the PRL promoter to regulate PRL gene expression in mammals. However, it is unknown whether chicken PREB involves the expression of PRL mRNA or not. This study aimed to clone and characterize the chicken PREB gene and to investigate the mRNA expression during embryogenesis and different reproductive stages. Based on the conserved sequence of the human, rats and mouse, primers pairs were designed and applied to amplify the PREB cDNA fragment. After sequencing of PCR products, 5′- and 3′- end of mRNA were amplified and determined. To identify the structure of the PREB gene, PCR amplification was conducted. The chicken PREB gene consisted of 9 exons and 8 introns and encoded for a 411 amino acid protein. The expression of PREB mRNA in the anterior pituitary gland was measured during embryogenesis and at different reproductive stages. PREB mRNA was detectable at embryonic day 12. Significant increase of levels of PREB mRNA was detected at embryonic day 18 and a maximum level was detected at day 1 of chick. In adult Silkie hens, the lowest level of PREB mRNA was detected in non-photostimulated hens whereas the highest level was observed in incubating hens. Since both the expression of PREB mRNA and PRL mRNA show a similar profile, PREB might be involved in expression of PRL mRNA. An alternative-splicing isoform, which lacks exon 7, was also detected. Because the predicted translated protein originating from this splicing isoform lacked most of the region of WD3 repeat region, this isoform may either have no function or have an alternative function. The results of this study support the possibility of involvement of PREB in PRL mRNA expression in the chicken anterior pituitary gland.
This study aimed to evaluate the efficacy of dietary prebiotic, probiotic, and synbiotic products for controlling infection in laying hens and broiler chickens challenged with Salmonella enterica serovar Enteritidis (SE). These products could replace the use of antibiotics, which would avoid the problem of hastening antimicrobial resistance for both types of birds. Salmonella-free 1-day-old (1-d-old) layers chicks and broilers chicks were inoculated with SE resistant to nalidixic acid and spectinomycin (SE Nalr Specr) and divided into four groups: 1) control (without feed additives); 2) probiotic (Bacillus subtilis, Lactobacillus acidophilus, L. casei, Enterococcus faecium, Bifidobacterium longum); 3) prebiotic (inulin, fructooligosaccharide, mannanoligosaccharide, and oligosaccharide); and 4) synbiotic (85% of the probiotic＋15% of the prebiotic additives). The presence of SE Nalr Specr in cloacal swabs was analyzed at 7, 14, and 21 days post-infection (dpi) in laying hens and broilers. The number of SE Nalr Specr per gram of cecal contents was determined at 7, 14, and 21 dpi in laying hens and at 2, 5, 7, 14, and 21 dpi in broilers. The results showed that the prebiotic additive reduced the occurrence of SE in cloacal swabs from laying hens but not from broilers. In the groups of laying hens and broilers that received prebiotics, the isolation and counts of SE Nalr Specr were lower during the first week post-infection but not throughout the experiment. The probiotic and synbiotic additives did not influence the SE infection in laying hens and broilers; in contrast prebiotics had a protective effect during the first week post-infection.
The aim of this study was to determine the effects of probiotics-feeding on the gene expression and protein localization of avian β-defensins (AvBDs) in the proventriculus of broiler chicks. Male broiler chicks were arranged in 3 groups: control group, probiotics group I and probiotics group II, which were fed with starter rations containing 0%, 0.2% or 0.4% probiotics, respectively, from day 0 (D0; at one day old) to D14. Proventriculi in all groups were collected at D0, D7 and D14 for analysis of AvBDs expression and AvBD12 protein localization. The expression of AvBDs genes was examined by reverse transcription-PCR and changes in the expression upon probiotics-feeding were examined by real-time PCR. The AvBD12 localization was examined by immunohistochemistry, and density of immunoreaction products was examined by image analysis under a microscope. Out of 14 AvBDs genes, seven AvBDs were detected in the proventriculus of chicks, namely, AvBD1, 2, 4, 6, 7, 10 and 12. The expression of the 7 detected genes did not show any significant differences between control and probiotics groups at D7 and D14. The immunoreactive (ir) -AvBD12 was localized in surface epithelium and cells in the connective tissues of proventricular glands. The ir-AvBD12 density in surface epithelium was significantly higher at D7 than at D0 or D14 in control group. At D7 and D14, the ir-AvBD12 density was significantly lower in probiotics groups than in control group. The ir-AvBD12 cells in proventricular gland increased in number with age; however, there were no significant differences between control and probiotics groups at D7 and D14. These results suggest that, although probiotics-feeding does not affect the gene expression of AvBDs, it may induce AvBD12 secretion from the surface epithelium of the proventriculus in broiler chicks.
Marek’s disease virus, including turkey herpesvirus (HVT), have been utilized as vectors to express foreign antigen genes and induce immunity against the antigens in chickens. Selection of promoters in developing such vector vaccines is one of the most important factors influencing efficacy of vector vaccines. In this study, in order to find a suitable promoter for expressing the hemagglutinin gene of avian influenza virus H5 subtype in HVT vector vaccines, three HVT vector avian influenza virus H5 subtype (HVT-AI) viruses expressing the hemagglutinin gene were constructed using three promoters; the cytomegalovirus (CMV) promoter, the chicken β-actin (Bac) promoter, and CMV/Bac chimera (Pec) promoter. Of those three vector vaccines, HVT-AI with the CMV promoter induced significantly higher avian influenza virus (AIV) hemagglutinin inhibition titers than the other HVT-AI vaccines with the Bac or the Pec promoters, after inoculation into chickens at one day old. When evaluated with two of commercially available AIV enzyme-linked immunosorbent assay kits, the HVT-AI vaccines did not induce positive titers, indicating that these HVT-AI vaccines may be utilized for easy differentiation of vaccinated chickens from ones infected with field AIV.
The objective of this study was to investigate the influence of electrical water bath stunning treatments (pulsed direct current) on stress conditions of poultry meat. This was carried out by evaluating meat quality measured through the incidence of PSE (pale, soft, exudative) in broiler breast fillet meat. We applied the randomized factorial design 22 with three replications at the central point, with independent variables, including voltage (40, 80, 120 V) and electrical frequency (100, 400, 700 Hz). The response functions under study were pH, L*, a*, b*, WHC and incidence of PSE meat. Samples presenting with pH of ≤5.80 and L* of ≥53.0 were classified as PSE whereas those with 5.80<pH<6.00 and 44.0<L*<53.0 were considered normal. The fillets taken from birds without stunning presented 54.14% of PSE meat samples, which decreased to 25.0% with stunning. The response functions L* and incidence of PSE showed regression (P≤0.05) with good adjustment of experimental data to the proposed model. The lowest incidence of PSE meat was observed when voltage and frequency were at their highest levels. In poultry slaughter, the applied electric stunning voltage of 120 V with a frequency of 700 Hz was determined to be the most effective for inhibition of PSE development.