Tissue distribution of stem cell factor in adults.

Stem cell factor (SCF) is an essential cytokine during development and is necessary for gametogenesis, hematopoiesis, mast cell development, stem cell function, and melanogenesis. Here, we measure SCF concentration and distribution in adult humans and mice using gene expression analysis, tissue staining, and organ protein lysates. We demonstrate continued SCF expression in many cell types and tissues into adulthood. Tissues with high expression in adult humans included stomach, spleen, kidney, lung, and pancreas. In mice, we found high SCF expression in the esophagus, ovary, uterus, kidney, and small intestine. Future studies may correlate our findings of increased, organ-specific SCF concentrations within adult tissues with increased risk of SCF/CD117-related disease.

The influence of interstitial cells of Cajal loss and aging on slow wave conduction velocity in the human stomach.

Loss of interstitial cells of Cajal (ICC) has been associated with gastric dysfunction and is also observed during normal aging at ~13% reduction per decade. The impact of ICC loss on gastric slow wave conduction velocity is currently undefined. This study correlated human gastric slow wave velocity with ICC loss and aging. High-resolution gastric slow wave mapping data were screened from a database of 42 patients with severe gastric dysfunction (n = 20) and controls (n = 22). Correlations were performed between corpus slow wave conduction parameters (frequency, velocity, and amplitude) and corpus ICC counts in patients, and with age in controls. Physiological parameters were further integrated into computational models of gastric mixing. Patients: ICC count demonstrated a negative correlation with slow wave velocity in the corpus (i.e., higher velocities with reduced ICC; r2  = .55; p = .03). ICC count did not correlate with extracellular slow wave amplitude (p = .12) or frequency (p = .84). Aging: Age was positively correlated with slow wave velocity in the corpus (range: 25-74 years; r2  = .32; p = .02). Age did not correlate with extracellular slow wave amplitude (p = .40) or frequency (p = .34). Computational simulations demonstrated that the gastric emptying rate would increase at higher slow wave velocities. ICC loss and aging are associated with a higher slow wave velocity. The reason for these relationships is unexplained and merit further investigation. Increased slow wave velocity may modulate gastric emptying higher, although in gastroparesis other pathological factors must dominate to prevent emptying.

Developmental milestones in neonatal and juvenile C57Bl/6 mouse - Indications for the design of juvenile toxicity studies.

There is a growing demand for wild type mice and mouse models of disease that may be more representative of human conditions but there is little information on neonatal and juvenile mouse anatomy. This project produces sound and comprehensive histology background data on the developing neonatal mouse at different time points from Day 0 until Day 28. The work describes optimal methods for tissue harvesting, fixation and processing from the neonatal and juvenile mice which can be used in routine toxicology studies. A review of the available literature revealed inconsistencies in the developmental milestones reported in the mouse. Although it is true that the sequence of events during the development is virtually the same in mice and rats, important developmental milestones in the mouse often happen earlier than in the rat, and these species should not be used interchangeably.

Differential sensitivity of gastric and small intestinal muscles to inducible knockdown of anoctamin 1 and the effects on gastrointestinal motility.

KEY POINTS: Electrical pacemaking in gastrointestinal muscles is generated by specialized interstitial cells of Cajal that produce the patterns of contractions required for peristalsis and segmentation in the gut. The calcium-activated chloride conductance anoctamin-1 (Ano1) has been shown to be responsible for the generation of pacemaker activity in GI muscles, but this conclusion is established from studies of juvenile animals in which effects of reduced Ano1 on gastric emptying and motor patterns could not be evaluated. Knocking down Ano1 expression using Cre/LoxP technology caused dramatic changes in in gastric motor activity, with disrupted slow waves, abnormal phasic contractions and delayed gastric emptying; modest changes were noted in the small intestine. Comparison of the effects of Ano1 antagonists on muscles from juvenile and adult small intestinal muscles suggests that conductances in addition to Ano1 may develop with age and contribute to pacemaker activity. ABSTRACT: Interstitial cells of Cajal (ICC) generate slow waves and transduce neurotransmitter signals in the gastrointestinal (GI) tract, facilitating normal motility patterns. ICC express a Ca2+ -activated Cl- conductance (CaCC), and constitutive knockout of the channel protein anoctamin-1 leads to loss of slow waves in gastric and intestinal muscles. These knockout experiments were performed on juvenile mice. However, additional experiments demonstrated significant differences in the sensitivity of gastric and intestinal muscles to antagonists of anoctamin-1 channels. Furthermore, the significance of anoctamin-1 and the electrical and mechanical behaviours facilitated by this conductance have not been evaluated on the motor behaviours of adult animals. Cre/loxP technology was used to generate cell-specific knockdowns of anoctamin-1 in ICC (KitCreERT2/+ ;Ano1tm2jrr/+ ) in GI muscles. The recombination efficiency of KitCreERT was evaluated with an eGFP reporter, molecular techniques and immunohistochemistry. Electrical and contractile experiments were used to examine the consequences of anoctamin-1 knockdown on pacemaker activity, mechanical responses, gastric motility patterns, gastric emptying and GI transit. Reduced anoctamin-1 caused loss of gastric, but not intestinal slow waves. Irregular spike complexes developed in gastric muscles, leading to uncoordinated antral contractions, delayed gastric emptying and increased total GI transit time. Slow waves in intestinal muscles of juvenile mice were more sensitive to anoctamin-1 antagonists than slow waves in adult muscles. The low susceptibility to anoctamin-1 knockdown and weak efficacy of anoctamin-1 antagonists in inhibiting slow waves in adult small intestinal muscles suggest that a conductance in addition to anoctamin-1 may develop in small intestinal ICC with ageing and contribute to pacemaker activity.

Molecular ontogeny of the stomach in the catshark Scyliorhinus canicula.

The origin of extracellular digestion in metazoans was accompanied by structural and physiological alterations of the gut. These adaptations culminated in the differentiation of a novel digestive structure in jawed vertebrates, the stomach. Specific endoderm/mesenchyme signalling is required for stomach differentiation, involving the growth and transcription factors: 1) Shh and Bmp4, required for stomach outgrowth; 2) Barx1, Sfrps and Sox2, required for gastric epithelium development and 3) Cdx1 and Cdx2, involved in intestinal versus gastric identity. Thus, modulation of endoderm/mesenchyme signalling emerges as a plausible mechanism linked to the origin of the stomach. In order to gain insight into the ancient mechanisms capable of generating this structure in jawed vertebrates, we characterised the development of the gut in the catshark Scyliorhinus canicula. As chondrichthyans, these animals retained plesiomorphic features of jawed vertebrates, including a well-differentiated stomach. We identified a clear molecular regionalization of their embryonic gut, characterised by the expression of barx1 and sox2 in the prospective stomach region and expression of cdx1 and cdx2 in the prospective intestine. Furthermore, we show that gastric gland development occurs close to hatching, accompanied by the onset of gastric proton pump activity. Our findings favour a scenario in which the developmental mechanisms involved in the origin of the stomach were present in the common ancestor of chondrichthyans and osteichthyans.

Development and growth of digestive system organs of European and Japanese quail at 14 days post-hatch.

The objective of this study was to evaluate the development and growth of the digestive system organs, from the 11th day of incubation until the 14 d post-hatch in European and Japanese quail. On days 11, 13 and 15 of incubation at hatch and at 4, 7, 10 and 14 d post-hatch, embryos or chicks of European and Japanese quail were analyzed. After 15 d of incubation, samples from stomach and small intestine were analyzed by microscopy. European quail had significantly heavier body weight at 15 d of incubation and after 4 d post-hatch. The digestive system weight progressively increased with age and was similar between European and Japanese quail at 11, 13, and 15 d of incubation and 10 d post-hatch, while relative weight of digestive system was similar between quail type with great values at 4 d post-hatch. For relative weight of the small intestine + pancreas, the weight of the proventriculus and of the gastric ventricle increased significant by among ages analyzed in both types of quail. At hatch, proventriculus had functional secretory cells and mucosa of gastric ventricle had a thin coilin membrane. In small intestine segments, at 15 d of incubation the height of the villi was similar among duodenum, jejunum, and ileum (80 µm). Villi had elongated shape towards the intestinal lumen, covered by enterocytes and dispersed goblet cells with PAS+ and AB+ contend in all segments. The number of goblet cell/villi increased in segments until 7 to 10 d post-hatch. Duodenum increases the villi up to 14 d, while the jejunum and ileum up to 10 and 4 d, respectively. Based on our data in digestive system growth, a shorter period of post-hatch fast and specific diets to quail during first days of growth is recommended to both quail types. It is concluded that the development and growth of different organs of the digestive system up to 14 d of age was similar between European and Japanese quail.

The FTO Gene Is Associated with Growth and Omega-3/-6 Ratio in Asian Seabass.

Polymorphisms in the FTO gene are associated with obesity and body mass index in humans and livestock. Little information of whether FTO plays an important role in aquaculture fish species is available. We cloned and characterized the FTO gene in an economically important food fish species: Asian seabass (Lates calcarifer). The full-length cDNA of the gene is 3679 bp, containing an ORF of 1935 bp encoding 644 amino acids, a 216 bp 5' UTR and a 1538 bp 3' UTR. The gene consisted of nine exons and eight introns and was 117,679 bp in length. Phylogenetic analysis revealed that the gene in Asian seabass was closely related to those of Japanese flounder and Nile tilapia. Analysis of its expressions using qRT-PCR showed that it was expressed ubiquitously, but was higher in the liver, stomach and intestine. Comparative analysis of the genomic sequences of part of intron 1 of the gene among 10 unrelated individuals identified two SNPs. Analysis of associations between SNPs and traits (i.e. growth, oil content, omega-3 and -6 contents) in an F2 family demonstrated that the two SNPs were significantly associated with growth, oil content, omega-3 content and omega-3/-6 ratio. Altogether, our data suggest that the gene or/and its linked genes play an important role in growth and fatty acid synthesis, and that the SNPs associated with traits may be used as markers for selecting quicker growth and higher omega-3/-6 ratio at the fingerling stage.

Transcriptional development of phospholipid and lipoprotein metabolism in different intestinal regions of Atlantic salmon (Salmo salar) fry.

BACKGROUND: It has been suggested that the high phospholipid (PL) requirement in Atlantic salmon (Salmo salar) fry is due to insufficient intestinal de-novo synthesis causing low lipoprotein (LP) production and reduced transport capacity of dietary lipids. However, in-depth ontogenetic analysis of intestinal PL and LP synthesis with the development of salmon has yet to be performed. Therefore, in this paper we used RNA-Seq technology to investigate the expression of genes involved in PL synthesis and LP formation throughout early developmental stages and associate insufficient expression of synthesis pathways in salmon fry with its higher dietary PL requirement. There was a special focus on the understanding homologous genes, especially those from salmonid-specific fourth vertebrate whole-genome duplication (Ss4R), and their contribution to salmonid specific features of regulation of PL metabolic pathways. Salmon fry were sampled at 0.16 g (1 day before first-feeding), 2.5 and 10 g stages of development and transcriptomic analysis was applied separately on stomach, pyloric caeca and hindgut of the fish. RESULTS: In general, we found up-regulated pathways involved in synthesis of phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), and LP in pyloric caeca of salmon between 0.16 and 10 g. Thirteen differentially expressed genes (q < 0.05) in these pathways were highly up-regulated in 2.5 g salmon compared to 0.16 g, while only five more differentially expressed (q < 0.05) genes were found when the fish grew up to 10 g. Different homologous genes were found dominating in stomach, pyloric caeca and hindgut. However, the expression of dominating genes in pathways of PL and LP synthesis were much higher in pyloric caeca than stomach and hindgut. Salmon-specific homologous genes (Ss4R) had similar expression during development, while other homologs had more diverged expression. CONCLUSIONS: The up-regulation of the de-novo PtdCho and PtdEtn pathways confirm that salmon have decreasing requirement for dietary PL as the fish develops. The similar expressions between Ss4R homologous genes suggest that the functional divergence of these genes was incomplete compared to homologs derived from other genome duplication. The results of the present study have provided new information on the molecular mechanisms of phospholipid synthesis and lipoprotein formation in fish.

Sympathetic Innervation of Stomach in Postnatal Development.

Sympathetic innervation of the stomach was studied in rats by the method of retrograde axon transport of Fast Blue in postnatal ontogenesis. The number of labeled neurons increased in the first 10 days of life and then did not change until the senescence. All labeled neurons innervating the stomach contain the catecholamine synthesis enzyme, tyrosine hydroxylase. The proportion of labeled neuropeptide Y-immunopositive neurons did not change in the development, the percentage of labeled calbindin-immunoreactive neurons decreased in the first month of life.

The newborn rat gastric emptying rate is volume and not developmentally dependent.

BACKGROUND: Gastric residuals are a common finding in enterally fed preterm neonates and traditionally thought to reflect immaturity-related delayed gastric emptying. Adult human data suggest that the meal volume regulate the gastric emptying rate, but early in life, this has not been adequately evaluated. The goal of this study was to study the rat postnatal changes in gastric emptying rate and the strain-induced effect on muscle contraction. We hypothesized that the stomach content volume and not developmental factors determines the newborn gastric emptying rate, via the Rho-kinase 2 (ROCK-2) pathway. METHODS: Gastric volume and emptying rate measurements were obtained by ultrasound at different postprandial times and the wall strain-dependent changes in muscle contraction were evaluated ex vivo. KEY RESULTS: The newborn rat gastric emptying rate was unrelated to postnatal age, maximal 30 min postprandial, and directly proportional to content volume. In vitro measurements showed that the agonist-induced gastric muscle contraction was directly proportional to the stomach wall strain. These changes were mediated via upregulation of ROCK-2 activity. CONCLUSIONS & INFERENCES: The newborn rat gastric emptying rate is not developmentally regulated, but dependent on the content volume via wall strain-induced ROCK-2 activation. Further clinical studies addressing the content volume effect on the rate of gastric emptying are warranted, to enhance feeding tolerance in preterm neonates.

Corticosterone activity during early weaning reprograms molecular markers in rat gastric secretory cells.

Gastric epithelial cells differentiate throughout the third postnatal week in rats, and become completely functional by weaning time. When suckling is interrupted by early weaning (EW), cell proliferation and differentiation change in the gastric mucosa, and regulatory mechanisms might involve corticosterone activity. Here we used EW and RU486 (glucocorticoid receptor antagonist) to investigate the roles of corticosterone on differentiation of mucous neck (MNC) and zymogenic cells (ZC) in rats, and to evaluate whether effects persisted in young adults. MNC give rise to ZC, and mucin 6, Mist1, pepsinogen a5 and pepsinogen C are produced to characterize these cells. We found that in pups, EW augmented the expression of mucins, Mist1 and pepsinogen C at mRNA and protein levels, and it changed the number of MNC and ZC. Corticosterone regulated pepsinogen C expression, and MNC and ZC distributions. Further, the changes on MNC population and pepsinogen C were maintained until early- adult life. Therefore, by using EW as a model for altered corticosterone activity in rats, we demonstrated that the differentiation of secretory epithelial cells is sensitive to the type of nutrient in the lumen. Moreover, this environmental perception activates corticosterone to change maturation and reprogram cellular functions in adulthood.

Exploring gastric bacterial community in young pigs.

Microbiota plays an important role in the homeostasis of the gastrointestinal tract. Understanding the variations of the commensal microbiota composition is crucial for a more efficient control of enteric infectious diseases and for the reduction of the use of antibiotics in animal production, which are the main points of interest for improved animal healthcare and welfare and for consumer health protection. Even though the intestinal microbiota has been extensively studied, little is known about the gastric microbiota. This pilot study was aimed at a descriptive analysis of the gastric microbiota in healthy pigs and at the identification of any differences among four potentially distinct microbial niches in the stomach. Gastric mucosal samples from the oxyntic area, the pylorus and the gastric groove, and a sample of gastric contents were collected from four healthy weaned pigs. Bacterial DNA was isolated and extracted from each sample and amplicons from the V6 region of the 16S rRNA gene were sequenced using Ion Torrent PGM. The data were analysed by an "unsupervised" and a "supervised" approach in the Ribosomal Database Project (RDP) pipeline. Proteobacteria was the dominant phylum in all the samples. Differences in bacterial community composition were found between mucosal and content samples (one-way ANOSIM pairwise post hoc test, p < 0.05); instead, the different mucosal regions did not show differences between them. The mucosal samples were characterised by Herbiconiux and Brevundimonas, two genera which include cellulolytic and xylanolytic strains. Nevertheless, additional larger trials are needed to support the data presented in this pilot study and to increase the knowledge regarding the resident microbiota of the stomach.

Gastric Organoids: An Emerging Model System to Study Helicobacter pylori Pathogenesis.

Helicobacter research classically uses fixed human tissue, animal models or cancer cell lines. Each of these study objects has its advantages and has brought central insights into the infection process. Nevertheless, in model systems for basic and medical research, there is a gap between two-dimensional and most often transformed cell cultures and three-dimensional, highly organized tissues. In recent years, stem cell research has provided the means to fill this gap. The identification of the niche factors that support growth, expansion and differentiation of stem cells in vitro has allowed the development of three-dimensional culture systems called organoids. Gastric organoids are grown from gastric stem cells and are organized epithelial structures that comprise all the differentiated cell types of the stomach. They can be expanded without apparent limitation and are amenable to a wide range of standard laboratory techniques. Here, we review different stem cell-derived organoid model systems useful for Helicobacter pylori research and outline their advantages for infection studies.

Silver acetate exposure: Effects on reproduction and post natal development.

Effects of oral silver acetate exposure were assessed in P generation and F generation post-natal day 26 rats. Male and female Sprague Dawley rats (n = 20 each) were exposed to silver acetate at 0.4, 4.0 or 40.0 mg/kg bw in their drinking water for 10 weeks prior to and during mating. Females were exposed to silver acetate throughout gestation and lactation. Clinical signs, body weight, feed and fluid consumption were recorded regularly. Decreased mean daily fluid consumption was observed in male and female animals during the 10 week pre mating period and during gestation in the 40 mg/kg bw dose group. Decreased fertility was observed in the 40 mg/kg bw dose group. Decreased feed consumption was observed across all dose groups and decreased mean daily fluid consumption was observed in the 4.0 mg/kg dose group during lactation. Decreased implant numbers, mean numbers of pups born/litter and numbers of live pups born/litter was observed in the 40 mg/kg bw dose group. Pup weight was reduced on lactation days 0, 4 and 7 (males) and 4, 7 and 21 (females) in the 4.0 mg/kg bw dose group and in males at lactation day 21 (40 mg/kg bw dose group). Runting was observed in males (Lactation Day; LD 4) and female (LD 4 and 7) animals in the 4.0 mg/kg bw dose group. Reduced postnatal-day 26 pup weight was observed in male pups in the 40 mg/kg bw dose group and female pups in the 4.0 mg/kg bw dose group.

Modeling DNA methylation by analyzing the individual configurations of single molecules.

DNA methylation is often analyzed by reporting the average methylation degree of each cytosine. In this study, we used a single molecule methylation analysis in order to look at the methylation conformation of individual molecules. Using D-aspartate oxidase as a model gene, we performed an in-depth methylation analysis through the developmental stages of 3 different mouse tissues (brain, lung, and gut), where this gene undergoes opposite methylation destiny. This approach allowed us to track both methylation and demethylation processes at high resolution. The complexity of these dynamics was markedly simplified by introducing the concept of methylation classes (MCs), defined as the number of methylated cytosines per molecule, irrespective of their position. The MC concept smooths the stochasticity of the system, allowing a more deterministic description. In this framework, we also propose a mathematical model based on the Markov chain. This model aims to identify the transition probability of a molecule from one MC to another during methylation and demethylation processes. The results of our model suggest that: 1) both processes are ruled by a dominant class of phenomena, namely, the gain or loss of one methyl group at a time; and 2) the probability of a single CpG site becoming methylated or demethylated depends on the methylation status of the whole molecule at that time.

Characterization and tissue distribution of Lhx9 and Lhx9α in Chinese giant salamander Andrias davidianus.

Lhx9 is an LIM (named for the first three proteins in which the domain was found, Lin-11, Isl1 and Mec-3) homeodomain protein involved in development and differentiation of the gonad. In this study, we isolated the full-length Lhx9 and Lhx9α from Andrias davidianus, detected the tissue distribution and analysed the methylation of the promoters. We identified Lhx9 of 1411 bp and Lhx9α of 1153-bp length, differing in the 3'-flanking region, encoding 399 and 330 amino acids, respectively. The Lhx9 gene was detected primarily in liver, ovary and heart with moderate expression in brain, pituitary, intestine and spleen, and low expression in the remaining examined tissues, while Lhx9α expression was high in heart, pituitary and liver, and low in spleen and stomach. Significantly higher Lhx9 expression was observed in ovary than in testis, with no differences in Lhx9α expression between testis and ovary observed. Bisulphite sequencing revealed significantly higher methylation in testis compared to ovary. The methylation level of CpG sites -733, -673, -615 and -594 exhibited significantly higher levels in testis than in ovary, which was negatively correlated with Lhx9 expression. The methylation and expression patterns suggested that promoter methylation suppressed expression of Lhx9 in A. davidianus.

Ghrelin and GHS-R in the rat gastric mucosa: Are they involved in regulation of growth during early weaning?

OBJECTIVES: Based on previous evidence showing that early weaning disturbs the ontogenesis of rat gastric glands, which are the major site of ghrelin synthesis, we investigated the distribution of ghrelin and its receptor (GHS-R) in the rat gastric epithelium during postnatal development and evaluated the effects of early weaning on their levels. Additionally, we studied the contribution of ghrelin to gastric growth during the abrupt nutrient transition. METHODS: Wistar rats were submitted to early weaning at 15 d and suckling counterparts were taken as controls. RESULTS: By running quantitative reverse transcription polymerase chain reaction, immunoblots, and immunohistochemistry, we detected a variation of ghrelin levels and an increase of expression and number of immunolabeled cells, 3 d after treatment (P < 0.05). Through confocal microscopy, we identified GHS-R in the neck region of the gland and did not observe changes in protein levels. Growth was evaluated after ghrelin antagonist ([D-Lys-3]-GHRP-6) administration, which reduced DNA synthesis index in early-weaned rats (P < 0.05) as determined by bromodeoxyuridine incorporation. CONCLUSION: The present study demonstrated that ghrelin and GHS-R are distributed in gastric mucosa during the postnatal development, indicating that they can signal and function in epithelial cells. We concluded that early weaning increased ghrelin levels in the stomach, and it takes part of cell proliferation control that is essential for stomach growth. Therefore, among the many effects previously described for early weaning, this abrupt nutrient transition also changed ghrelin levels, which might represent an additional element in the complex mechanism that coordinates stomach development.

In vivo ultrasound assessment of gastric emptying in newborn mice.

OBJECTIVES: The aim of the present study was to develop an ultrasonographic approach to comparatively assess gastric emptying in newborn wild-type and guanosine triphosphate cyclohydrolase knockout hph-1 mice, because we previously reported gastroparesis early in life in this strain. METHODS: Stomach transverse, anteroposterior, and longitudinal ultrasonographic measurements were obtained with a 40-MHz transducer in pups immediately after maternal separation and 4 hours later. A conventional equation was used and the predicted values validated by obtaining postmortem gastric content volume measurements. Wild-type and hph-1 mice gastric emptying rates were comparatively evaluated at 1 to 3 and 5 to 8 days of age, respectively. RESULTS: The ultrasound equation closely predicted the newborn stomach content volumes with a correlation coefficient (R) of 0.93 and 0.81 (P < 0.01) for measurements obtained on full stomach and after 4 hours of fasting, respectively. In wild-type mice, gastric emptying was age dependent and associated with a greater residual volume at 1 to 3 days (65% ± 7%), as compared with 5- to 8-day-old pups (33% ± 4%; P  < 0.01), after fasting. In contrast, an equal duration of fasting resulted in a significantly greater residual gastric content volume in 5- to 8-day-old hph-1 mice (68%  ± 7%; P < 0.01), as compared with same-age wild-type mice. CONCLUSIONS: Ultrasonography offers a sensitive and accurate estimate of gastric content volume in newborn mice. In wild-type newborn mice, gastric emptying rate is age dependent and significantly reduced in the immediate postnatal period. The newborn hph-1 mice have a significantly higher gastric residual volume, as compared with wild-type same-age animals.

Physiological status of broiler chicks at pulling time and the relationship to duration of holding period.

Newly hatched chicks may be held longer than 48 h and experience long periods of fasting in commercial hatcheries. Limited information is known about the physiological status of chicks in such situations, due to the difficulty of precisely recording time of hatch. This study investigated the effect of the time from hatch to pulling (holding period) on physiological measures/parameters in 109 broiler chicks. Fertile Ross 308 eggs were incubated in a custom built small-scale incubator. The individual hatching time of each focal chick was determined using eggshell temperature monitoring. At 'pulling' (512 h of incubation time), the quality of focal chicks was assessed using the chick scoring method and physiological parameters were measured including BW, organ (heart, liver and stomach) weights, blood values and plasma corticosterone level. The time from hatch to pulling varied from 7.58 to 44.97 h. Egg weight at setting was significantly correlated with chick BW and weight of organs at pulling, but had no effect on chick quality, blood values and plasma corticosterone. Relative BW at pulling was negatively associated with the duration of holding period (P=0.002). However, there was a positive correlation between relative stomach weight and the duration of the holding period (P<0.001). As the holding period duration increased, there was a trend that blood partial pressure of oxygen, haematocrit and haemoglobin also increased, and blood partial pressure of carbon dioxide, total carbon dioxide and bicarbonate decreased (P<0.05). A wide range of plasma corticosterone was observed from chicks that had experienced different durations of holding period. We conclude that shortening the hatch window and minimising the number of chicks that experience a long holding period before pulling may improve chick quality and physiological status, which may be due to unfavourable environmental conditions that include feed and water deprivation.

Whey protein isolate decreases murine stomach weight and intestinal length and alters the expression of Wnt signalling-associated genes.

The present study examined the underlying mechanisms by which whey protein isolate (WPI) affects energy balance. C57BL/6J mice were fed a diet containing 10% energy from fat, 70% energy from carbohydrate (35% energy from sucrose) and 20% energy from casein or WPI for 15 weeks. Mice fed with WPI had reduced weight gain, cumulative energy intake and dark-phase VO2 compared with casein-fed mice (P< 0.05); however, WPI intake had no significant effects on body composition, meal size/number, water intake or RER. Plasma levels of insulin, TAG, leptin, glucose and glucagon-like peptide 1 remained unchanged. Notably, the intake of WPI reduced stomach weight and both length and weight of the small intestine (P< 0.05). WPI intake reduced the gastric expression of Wingless/int-1 5a (Wnt5a) (P< 0.01) and frizzled 4 (Fzd4) (P< 0.01), with no change in the expression of receptor tyrosine kinase-like orphan receptor 2 (Ror2) and LDL receptor-related protein 5 (Lrp5). In the ileum, WPI increased the mRNA expression of Wnt5a (P< 0.01) and caused a trend towards an increase in the expression of Fzd4 (P= 0.094), with no change in the expression of Ror2 and Lrp5. These genes were unresponsive in the duodenum. Among the nutrient-responsive genes, WPI specifically reduced ileal mRNA expression of peptide YY (P< 0.01) and fatty acid transporter protein 4 (P< 0.05), and decreased duodenal mRNA expression of the insulin receptor (P= 0.05), with a trend towards a decreased expression of Na-glucose co-transporter 1 (P= 0.07). The effects of WPI on gastrointestinal Wnt signalling may explain how this protein affects gastrointestinal structure and function and, in turn, energy intake and balance.