Effect of feeding on the tissue free amino acid concentrations in rainbow trout (Oncorhynchus mykiss Walbaum)

This study investigates whether tissue free amino acid (FAA) pools in rainbow trout,Oncorhynchus mykiss (Walbaum), are altered following feeding and the relationships between the amount of food consumed and the FAA pool size. Trout were starved for 7 days to provide baseline data and then refed on day 8. Individual food intake was measured by radiography and the consumption of amino acids (AA) calculated from dietary protein consumption. Total FAA concentrations in the stomach, liver and white muscle were little changed at various times after the meal and this pattern was repeated for the majority of individual FAA. Overall, the most notable change was a reduction in essential FAA concentrations (principally in valine, leucine and isoleucine) in the white muscle following feeding. However, in the caeca total FAA, total essential FAA and a number of individual FAA were significantly elevated at 4, 9 and 15h following feeding. There were few significant correlations between dietary amino acid consumption and total tissue FAA and essential FAA concentration in the stomach, caecum and white muscle; correlations were stronger in the liver. In order to explain the relative constancy of total FAA concentrations in the tissues following food intake (which represents over 100% of the total FAA pool) a model is presented that quantifies the AA flux through the free pools and considers the role of protein turnover in regulating FAA pool size.     

Presence and ontogeny of intestinal and pancreatic phospholipase A2-like proteins in the Red Sea bream,Pagrus major. An immunocytochemical study

We have studied the location and the ontogeny of the digestive enzyme, phospholipase A₂ (PLA₂) immunohistochemically in the adult and larvae/juvenile of the red sea breamPagrus major by using an antiserum against theNaja naja venom PLA₂. The antiserum reacts with at least one enzyme among the PLA₂s purified from the fish hepatopancreas or intestine. Although the reactivities were comparatively low, it labelled zymogen granules of the pancreatic acinar cells and secretory materials of certain epithelial cells in the depths of epithelial crypts in the pyloric caeca of the adult. The immunoreactivities of PLA₂s were investigated in the viscera of larvae and juveniles of the 0 to 85^th day after hatch. In the larvae of the 13^th day, accumulation of PLA₂-positive zymogen granules in the pancreatic acinar cells were first recognized by the immunostaining. The intensity of the labelling subsequently became stronger and dramatically increased between the 20^th and 30^th day. This increase appeared to be one of the physiological changes associated with the transition to a new benthic life as juveniles. Lack of PLA₂ in the pancreas before the 13^th day may suggest the possibility that larvae utilized exogenous PLA₂, inherent in their prey, to digest the phospholipids. On the other hand, no reactivity was found in the intestine until the 85^th day.     

鳜胃肠道和肝脏主要消化酶活性的研究

试验测定了鳜胃、肠道、肝脏和幽门盲囊中蛋白酶、淀粉酶和脂肪酶等3种主要消化酶的活性及温度对这些酶活性的影响。结果表明:从鳜的胃、肠、肝脏和幽门盲囊中均可检测出蛋白酶、淀粉酶和脂肪酶的活性,且在温度为(37±1)℃和pH为7.5(胃pH5.4)条件下,鳜消化道中蛋白酶活性大小顺序为:幽门盲囊>肠>胃>肝脏;淀粉酶活性大小顺序为:肝脏>幽门盲囊>胃>肠;脂肪酶活性大小顺序为:幽门盲囊>肠>肝脏>胃。鳜胃、肠、肝脏和幽门盲囊中蛋白酶的最适温度分别为50℃、50℃、40℃和55℃,淀粉酶的最适温度分别为50℃、25℃、40℃和50℃,脂肪酶的最适温度分别为20℃、40℃、40℃和25℃。     

Muscular architecture and VIP-like immunoreactive nerves in the gastroduodenal junction of the chicken

The muscular architecture and the distribution of nerves with vasoactive intestinal polypeptide-like (VIP-like) immunoreactivity were examined in the gastroduodenal junction of the chicken. Both the outer and the inner muscle layers (tunica muscularis) and the muscularis mucosae were examined. The inner muscle layer was divided into two parts, namely its inner and outer parts. The outer muscle layer was not present in the pyloric part but was found in the proventriculus and the duodenum. The muscle strands of the outer muscle layer ran longitudinally but were absent at the isthmus and the pylorus. Most of the outer part of the inner muscle layer was located in or close to the pyloric part. The muscle strands in the outer part connected the pyloric part with other regions, namely the craniodorsal muscle, the tendinous centres and the isthmus. The inner part of the inner muscle layer was widely distributed in the stomach. In the pyloric part, the muscle strands of this layer followed a circular or spiral course. The muscularis mucosae was not present in the caudodorsal and cranioventral muscles of the gizzard. In addition, VIP-like immunoreactive nerve fibres were predominantly distributed in the inner part of inner muscle layer of the pyloric part. These results suggest that the ventriculopyloric orifice and the pyloric part itself constrict with a sphincter-like action.Abbreviations VIP vasoactive intestinal polypeptide     

绍鸭幽门区生长抑素细胞的免疫组织化学研究

用ABC免疫组织化学方法,标记1,10,16,22 周龄期绍鸭幽门区生长 抑素免疫反应细胞(D 细胞),观察细胞的形态、分布,计数幽门区单位面积内D 细胞的数目。结果表明:幽门区的D 细胞形态多为角锥形和卵圆形,有许多胞质突起。类型以“开放型”为主,少数为“封闭型”。D 细胞单个散在分布,主要位于幽门腺内,个别位于粘膜上皮。单位面积内D细胞的数目随周龄增加而增多,至16 周龄达高峰,22 周龄开始下降。     

Purification and characterization of phospholipase A2 from the pyloric caeca of red sea bream, Pagrus major

A phospholipase A₂ was purified 55,000-fold in a yield of 10% from the lipid-free extract of powder of the pyloric caeca of red sea bream to near homogeneity by sequential column chromatography on S-sepharose fast flow, butyl-cellulofine, Asahipak ES-502C cation-exchange HPLC, TSK gel G3000SW gel-filtration HPLC, and Asahipak ODP-50 reversed-phase HPLC. The final preparation showed a single band with the apparent molecular mass of 14 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and an estimated specific activity was 717 µmol min^-1 mg^-1 protein. The purified enzyme had a pH optimum in the range of pH 8.0–9.0 and required the presence of both 8 mM of Ca²⁺ and from 2 to 10 mM of sodium deoxycholate for its maximal activity, using 2 mM of phosphatidylcholine as a substrate. The purified enzyme preferentially hydrolyzed the 2-acyl ester bonds of both phosphatidylglycerol and phosphatidylcholine in the presence of sodium deoxycholate, followed in order by phosphatidylethanolamine and phosphatidyl-serine. In contrast to porcine pancreatic PLA₂, pyloric caeca PLA₂ hydrolyzed mixed-micellar phosphatidylcholine substrate effectively, regardless of the kinds of bile salts used. These results indicate that Ca²⁺-dependent low molecular mass PLA₂, so called secretory PLA₂, occurs in the pyloric caeca of red sea beam.     

ULTRASONOGRAPHIC APPEARANCE OF CHRONIC HYPERTROPHIC PYLORIC GASTROPATHY IN THE DOG

Chronic hypertrophic pyloric gastropathy was diagnosed using ultrasound in six dogs that were presented for chronic vomiting. An evenly thick hypoechoic layer surrounding the pyloric lumen was visualized ultrasonographically in dogs with grades 1 or 2 chronic hypertrophic pyloric gastropathy. This was histologically found to correspond with a thickened muscular layer. Gastric wall thickness was greater than or equal to 9 mm in all six dogs. In dogs with grade 1 or 2 chronic hypertrophic pyloric gastropathy, the hypoechoic muscular layer was greater than or equal to 4 mm.     

Growth and gut morphology of diploid and triploid juvenile Atlantic cod (Gadus morhua)

The objective of this paper was to compare the growth and gut morphology of juvenile diploid and triploid Atlantic cod (Gadus morhua) reared under similar conditions. Individually tagged 36‐week‐old diploid (mean weight 49.3 ± 13.8 g) and triploid (mean weight 43.6 ± 11.2) juvenile cod were measured at intervals during a 29‐week growth trial. Data for weight, length, condition factor (K), hepato‐somatic index (HSI), gonado‐somatic index (GSI), Relative Gut Length (RGL) and pyloric caeca number were collected and results were analysed in relation to ploidy status, gender and family contribution. At the end of the experiment, only one family (M2xF3) had many representatives with a relatively even distribution of sexes and ploidies. Diploid females were significantly heavier and had higher K than triploid females in the M2xF3 family (body weight 371.2 ± 120.2 vs. 298.4 ± 100.7 g; K 1.1 ± 0.1 vs. 0.93 ± 0.1), but no differences were found between diploid and triploid males. In the other families (pooled data), no differences in body weight were found between the ploidy groups. In general, triploids had a shorter intestine (RGL) and fewer pyloric caeca than their diploid siblings regardless of gender suggesting possible impairments in nutrient utilization and growth.     

First report on the autochthonous gut microbiota of brown trout (Salmo trutta Linnaeus)

A study was conducted to characterize the autochthonous gut microbiota present in the pyloric caeca (PC), anterior mucosa (AM) and posterior mucosa (PM) of brown trout (Salmo trutta). Total viable counts (TVC) bacterial populations were enumerated using tryptone soy agar, lactic acid bacteria (LAB) levels were enumerated on de Man, Rogosa & Sharpe agar and PCR‐DGGE was employed as a culture‐independent method to assess the total communities. No significant differences were observed between the different gut regions for TVC or LAB levels. 16S rRNA sequencing identified all LAB isolates as Carnobacterium maltaromaticum. In contrast, the TVC community was more diverse; Firmicutes and Bacteroidetes were present but all gut regions were dominated by Proteobacteria, accounting for 88.4–92.6% of the communities. Citrobacter freundii was the dominant species and accounted for 51.0–57.8% of the isolates. Complex bacterial communities were observed using PCR‐DGGE and a trend towards the reduction in the number of operational taxonomic units (OTUs), microbial richness and microbial diversity was observed from the PC to the PM. The similarity between regions was low (52–68%) and cluster analysis revealed that the communities grouped into two distinct clusters; one dominated by the PM samples and the other contained the AM and PC samples. OTUs from the DGGE were identified as members of the phyla Proteobacteria and Firmicutes. Many OTUs were detected in all gastrointestinal regions, however, some OTUs showed regional specialization. Further studies are required to elucidate the activity of these genera in situ and how their actions impact the host.     

不同规格瘤背石磺胃盲囊组织学初步研究

通过组织学观察与组织化学染色,研究了野生瘤背石磺不同体重(2～25 g)与胃盲囊的组织结构和PAS阳性细胞及肥大细胞的分布关系,为进一步探讨瘤背石磺消化生理和食性提供理论依据。结果发现:瘤背石磺胃盲囊组织主要由浆膜层、粘膜下层、固有膜和粘膜上皮层构成。瘤背石磺胃盲囊绒毛主要有两种类型,分别为非纺锤型绒毛和纺锤型绒毛,其中非纺锤型绒毛比例有随瘤背石磺体重增高而降低的趋势。胃盲囊横截面积、绒毛长度和粘膜上皮高度均有随瘤背石磺体重增高而增高的趋势,其中尤以低体重组(<8 g)和高体重组(>18 g)差异明显(P<0.05)。经PAS染色和肥大细胞染色后,发现仅在高体重组(>18 g)瘤背石磺胃盲囊绒毛粘膜上皮有大量的PAS染色阳性细胞和肥大细胞分布。