Developmental fall in whole body protein turnover of chick embryos during incubation

Whole body protein turnover was measured in chick embryos during incubation to investigate whether or not there is a fall in fractional rates of protein synthesis and degradation during development. Stable isotopically labelled [15N]phenylalanine was injected intraperitoneally into embryos on days 12 and 19. From 60 to 90 min after injection the isotope enrichment in free and protein-bound phenylalanine was measured with a selected-ion gas-chromatograph mass-spectrometer. The results showed that from days 12 to 19 of incubation, there was a remarkable reduction in fractional rates of protein synthesis and degradation in the whole body of chick embryos. During embryonic growth, protein synthesis per unit of RNA that is, the minimum amino acid translation rate of RNA, did not change significantly, whereas the RNA:protein ratio was reduced to one-third from days 12 to 19 of incubation. It was concluded, therefore, that the dramatic fall in fractional synthesis rate in chick embryos would be entirely attributable to the rapid increase in protein content, thereby changing the RNA:protein ratio in parallel with the fractional synthesis rate.     

Protein digestion in pigs measured in vitro

In vitro determination of protein digestibility by treating feedstuffs with pepsin-HCl respectively with pepsin and trypsin yields results that differ considerably from the ileal protein digestibility figures. Comparable results for N and lysine are received when the largest polypeptides in the solution obtained after peptic and tryptic treatment are precipitated with copper hydroxide.     

Eye variability in chick embryos

1. In two strains of Barred Plymouth Rock and one strain of Rhode Island Red birds a highly significant effect of strain was found on the size of eye cups and pupils in 6‐d‐old chick embryos. The average values of these eye characteristics and their variations were also influenced by the composition and energy content of the diet fed to the dams.

2. A strong positive phenotypical relationship was found between the size of eye cups and pupils, especially between the size of the left and the right eye cups. No relationship was found between the eye characteristics and the weight of egg.

3. An asymmetry of the left and the right eye was recorded; the left eye cups and pupils were smaller than the right on average by 2.2 and 3.9%, respectively.     

鸡包涵体肝炎鸡胚肝细胞包涵体特性的研究

应用鸡包涵体肝炎病毒 FAV- Hb株试验感染 SPF鸡胚 ,通过透射电镜对感染鸡胚肝脏的观察 ,表明 FAV- Hb株可引起鸡胚肝细胞内形成三种类型的包涵体 ,即非病毒性中等电子密度包涵体 ,病毒性包涵体和非病毒性高电子密度包涵体 ,各型包涵体均可见于胞核或胞浆内 ,但胞核是包涵体首先形成的部位 ,核内包涵体通过核膜进入胞浆。各型包涵体在其形成过程中有较密切的关系。     

Methodic recommendations for the determination of whole body protein synthesis rates in tracer studies

Methodical recommendations are suggested--predominantly for laboratory and small animals (rats and young chickens)--for the determination of parameters of the protein metabolism of the whole body after single doses of a mixture of 15N labelled amino acids by means of the determination of the temporal course of cumulative 15N excretion in urine and the assessment of the tracer kinetic data in a compartment model. These recommendations are to make it possible to carry out purposefully such experiments under comparable conditions. The advantages of this method are: the non-invasive character of the method; the possibility of repeating the experiment with the same animal; the adaptability to other methods of investigation (e.g. measuring energy metabolism); the relatively low expenditure of labour and requirement of test animals; the relatively good reproducibility of the method. Thus this method is a good supplement to the flooding and permanent infusion methods and should be used wherever the determination of parameters of the protein metabolism of the total body is sufficient.     

An in vitro culture method for chick embryos obtained from the anterior portion of the magnum of oviduct

1. Chick embryos, obtained from the anterior portion of the magnum of the oviduct 60 to 80 min after the preceding egg had been laid, were cultured in vitro in small and large recipient eggshells until hatching.

2. Of 82 embryos cultured, 46.3% had survived to day 4 of incubation, and 19.5% survived to hatching.

3. The method for culturing embryos used in this experiment could facilitate research on the in vitro manipulation of early chick embryos.     

Kinetics of phosphorus absorption and expressions of related transporters in primary cultured duodenal epithelial cells of chick embryos

Two experiments were conducted to investigate the kinetics of phosphorus (P) absorption and expressions of type IIb sodium-dependent phosphate cotransporter (NaP-IIb), inorganic phosphate transporters 1 and 2 (PiT-1 and PiT-2) in primary cultured duodenal epithelial cells of chick embryos. In experiment 1, the P absorptions across duodenal epithelial cell monolayers at different incubation time points (0, 10, 20, 40, 60, 80, 100 and 120 min) were compared. In experiment 2, the kinetics of P absorption was performed at 40 min after incubation of duodenal epithelial cells with the media containing 0, 0.75, 1.5, 3.0, 6.0, 12.0, 24.0 and 48.0 mmol P/L as KH₂PO₄, and the mRNA and protein expression levels of NaP-IIb, PiT-1 and PiT-2 in duodenal epithelial cells with the media containing 0, 6.0 and 48.0 mmol P/L were determined at 87 min after incubation. The results from experiment 1 showed that the P absorption increased linearly (p < .0001) from 0 to 80 min and the fastest increase occurred at 40 min; the asymptotic model was shown to have the best fit degree, and the optimal incubation time for saturable P absorption was determined to be 87 min. The kinetic curves of P absorption from experiment 2 demonstrated that P absorption was a mixed process of a non-saturable diffusion plus a saturable carrier-mediated transport across the duodenal epithelial cells. The high P concentration (48.0 mmol/L) decreased (p < .05) NaP-IIb and PiT-1 mRNA and protein levels and increased (p < .0001) PiT-2 mRNA level. These results indicated that the P absorption across primary cultured duodenal epithelial cell monolayers of chick embryos was a mixed process of a non-saturable diffusion plus a saturable carrier-mediated transport and could be restricted by reducing the NaP-IIb and PiT-1 expressions while increasing the PiT-2 expression at a high P concentration.     

Effects of estrogen on estrogen receptor expression in the bursal cells of chick embryos and steroidogenic enzymes gene expression in the bursa: Relevance of estrogen receptor and estrogen synthesis in the bursa of chick embryos

Estrogen has been reported to act on B cell genesis in the bursa of Fabricius of chick embryos. In this study, we attempted to demonstrate the hypothesis that B cell genesis is controlled by estrogen receptor (ER) in the bursal cells and steroidogenic enzymes synthesized in the bursa. We previously reported the presence of estrogen receptor α (ERα) in the bursa during the late stage of embryogenesis and an increase in the expression of ERα messenger RNA (mRNA) between the 13th day and 16th day. The number of ER-positive cells was maximal on the 16th day. In the present study, ER-positive cells in the bursa during the late stage of embryogenesis increased 4 h after β-estradiol treatment on the 14th to 18th day. The concentration of β-estradiol in the embryonic bursa increased. These results suggest that this stage of embryogenesis is critical in B cell development in the bursa in connection with the effect of estrogen treatment. Our findings also showed that the mRNA expression of five steroidogenic enzymes occurred in the bursa of chick embryos. These results suggest that estrogen is synthesized in the embryonic bursa and estrogen acts on the bursal cells in a paracrine fashion.     

Uterine secretions from different endometrial classifications affect the viability of early murine embryos cultured in vitro

An interspecies (murine-equine) bioassay system was employed to investigate the effect of equine endometrial secretions on embryonic survival. Uterine fluid was obtained from 15 diestrous mares by lavage with 150 ml of sterile Whitten's medium. Samples were grouped according to their Kenney score for endometrial type. Samples were sterilized and protein concentration was standardized to 4 mg/ml protein with BSA. Controls consisted of either 4 mg/ml BSA in Whitten's medium or 50% BSA-50% heat-treated equine serum. One hundred 2-cell mouse embryos were cultured in each sample and controls. Embryonic development was evaluated for 5 days and was expressed as the percent reaching the 4-cell, 8-cell, morula, blastocyst, expanded blastocyst, and hatched blastocyst stages. Embryonic development in Type I mare uterine fluid did not differ from controls. Development to the 4 cell, 8 cell, morula, blastocyst and expanded blastocyst stages in the Type II mare media was less (p<.01) than the controls and other endometrial types. Development to all these stages was also lower than controls and Type I incubates in Type III mare media (p<.05), although development was higher in Type III compared with Type II. Leukocyte infiltration in the endometrium was assessed to determine the level of inflammation present in these mares. Basophil and neutrophil numbers were not different (p>.05) between endometrial types. Lymphocyte numbers were significantly different (p<.05) between each endometrial type. The quantity of lymphocyte infiltration was inversely proportional to the rate of in vitro embryo development in Type I, Type II and Type III endometria.     

The determination of the rate of protein synthesis of the whole body of growing broilers

The purpose of the investigations was to prove a method, developed for monogastric mammalians, based on a 3-compartment-model and assuming a proportional growth of the pools of total N, whether it is applicable to growing poultry. The tracer, 15N-L-lysine, was given quasi-continuously for four days. In this time and in the following period of five days without tracer intake, the 15N-excretion in the urine was measured. The average of the live weight of the broiler cockerels was 1724 g. The animals were obliged to be colostomized to sample the urine. Using the fluxes of lysine, the calculation of the whole body protein synthesis rate yields 64.1 g/d. The protein degradation rate yields 54.4 g/d. The adequate values of the fractional rates of protein synthesis and -degradation for the whole body (without feathers) were 23.3% respectively 19.8%. By this it is clearly shown, that the applied method gives real dates of the parameters of the N-metabolism for growing broilers, which are in the range of values for muscle proteins and proteins of the whole body of growing poultry, published by other authors.     

Uric acid in the tissues and blood of chick embryos]

In the liver, kidney and skeletal muscle of the shank, blood plasma and blood cells of 90 chick embryos of the initial breed Leghorn White, commercial hybrid Primant, uric acid was found in all the intervals within the studied ontogenetic seqeuence. Uric acid was determined colorimetrically in tissue homogenate supernatant; in the blood plasma and in the blood cells it was determined colorimetrically on the 10th, 15th and 20th day of incubation. A significant rise (p less than 0.05) of this metabolite was ascertained in all the samples tested.     

Pulmonary ventilation in a population of hatching chick embryos

Two experiments were made to study pulmonary ventilation in the hatching chick embryo with particular reference to the part played by the air cell.

The hatchability of embryos without access to the air cell was the same as for normally positioned embryos. The lungs of about 35 per cent of the normally hatching embryos were inflated in the air cell, but 65 per cent were inflated after breathing atmospheric air. The shell was cracked but not pipped before the outer membrane was penetrated. Comparisons between different groups of normally and abnormally positioned unhatched embryos revealed that the air cell had an insignificant respiratory value, but that the mechanical advantages of the large end seemed apparent.

The time relationships between lung inflation, inner membrane perforation, pipping, yolk sac retraction, outer membrane perforation, lung discoloration and hatchability were studied. Equations were derived for the regression on time of each of the seven variables studied. Statistically insignificant differences in hatchability were observed between the 2 groups of embryos which hatched from the large or small end of the egg.

It is suggested that lung inflation occurs when a certain threshold in the respiratory movements of thoracic muscles is reached. The threshold is attained by the rising anoxia, and probably other stimuli. The chick embryo's lungs, which lack elastic recoil, respond to the threshold and start utilising air. It is doubtful whether the embryo needs the very high partial pressure of carbon dioxide in the air cell. It is feasible to believe that CO₂ is an inevitable metabolic by‐product, and that it is stored in the air cell. The air cell also serves as a resting place for the chick while retracting the yolk sac. Through evolution, however, the chick embryo may have built up a high physiological tolerance to the CO₂ which it encounters upon entering the air cell.     

c-jun对体外培养仔猪睾丸间质细胞睾酮分泌的影响

本试验用c-junASODNs诱导c-jun基因发生转录后沉默,探讨原癌基因c-jun对仔猪睾酮分泌的作用及可能机制。以2~3周龄长白仔猪为研究对象,采用体外培养体系,研究c-jun对基础状态下和hCG诱导下间质细胞(Leydig cell,LC)睾酮分泌及基础状态下LC增殖及凋亡的影响。结果显示,c-junASODNs以剂量依赖性方式抑制基础状态下和hCG诱导下睾酮分泌(P0.01)及基础状态下LC增殖(P0.01),当1μmol/Lc-junASODNs时,显著抑制LC的凋亡(P0.05)。结果表明,c-jun在基础状态下还是hCG诱导下均可促进仔猪LC睾酮的分泌,这种作用与c-jun促进LC增殖和凋亡有关。