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Simple Summary: The European barracuda (Sphyraena sphyraena) is a wild fish species that is both commercially and ecologically valuable and is found in the Adriatic Sea. To better understand its distribution and physiology, this study examined the digestive enzymes in various parts of the barracuda's gastrointestinal system using histochemical analyses. This is the first known study to evaluate the activity of aminopeptidase, alkaline phosphatase, acid phosphatase, and non-specific esterase in the pyloric caeca and the anterior, middle, and posterior segments of the European barracuda's gastrointestinal tract. In this study, we examined the gastrointestinal tract of the European barracuda (Sphyraena sphyraena) living in the Adriatic Sea near Dubrovnik, Croatia. The study aimed to identify the presence and distribution of four digestive enzymes: alkaline phosphatase, aminopeptidase, acid phosphatase, and non-specific esterase. We found that alkaline phosphatase activity was present in the brush border of the enterocytes in all the investigated intestinal segments. The activity of the alkaline phosphatase was the strongest in the pyloric caeca but strong only in the basal part of the intestinal villi in the anterior and middle intestinal segments. In the posterior intestinal segment, alkaline phosphatase had strong activity along the entire villi. The activity of acid phosphatase was weak in all the investigated parts of the intestine, except in the posterior part, where it was moderate. Aminopeptidase was detected in the brush border of the intestinal epithelium, with stronger activity in the pyloric caeca and anterior part of the intestine and weaker activity posteriorly. The activity of the non-specific esterase was moderate in the pyloric caeca and anterior part of the intestine, while it was weak in the posterior segment and the lamina propria in all parts of the digestive tract. Weak acid phosphatase activity was observed only in the lamina propria of the posterior part of the intestine. This study is the first to evaluate the activity of digestive enzymes in the European barracuda. [ABSTRACT FROM AUTHOR]

In this study, we examined the gastrointestinal tract of the European barracuda (Sphyraena sphyraena) living in the Adriatic Sea near Dubrovnik, Croatia. The study aimed to identify the presence and distribution of four digestive enzymes: alkaline phosphatase, aminopeptidase, acid phosphatase, and non-specific esterase. We found that alkaline phosphatase activity was present in the brush border of the enterocytes in all the investigated intestinal segments. The activity of the alkaline phosphatase was the strongest in the pyloric caeca but strong only in the basal part of the intestinal villi in the anterior and middle intestinal segments. In the posterior intestinal segment, alkaline phosphatase had strong activity along the entire villi. The activity of acid phosphatase was weak in all the investigated parts of the intestine, except in the posterior part, where it was moderate. Aminopeptidase was detected in the brush border of the intestinal epithelium, with stronger activity in the pyloric caeca and anterior part of the intestine and weaker activity posteriorly. The activity of the non-specific esterase was moderate in the pyloric caeca and anterior part of the intestine, while it was weak in the posterior segment and the lamina propria in all parts of the digestive tract. Weak acid phosphatase activity was observed only in the lamina propria of the posterior part of the intestine. This study is the first to evaluate the activity of digestive enzymes in the European barracuda.

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Neuropeptides are small molecules that mediate intercellular signaling and regulate physiological processes. Starfish possess various myoactive neuropeptides, including starfish myorelaxant peptide (SMP) and a calcitonin-type peptide with apical muscle relaxing properties. In this study, we report the purification of a neuropeptide from starfish (Patiria pectinifera) pyloric caeca extract using high-performance liquid chromatography (HPLC) and an in vitro bioassay to screen for fractions and peptides with relaxing effects on P. pectinifera apical muscle preparations. A series of HPLC steps using reversed-phase and cation-exchange columns yielded a purified peptide with muscle-relaxing effects. The purified peptide's structure was determined by LC-MS and Edman degradation, revealing a pentapeptide with an amidated C-terminus (NGFFYamide) and a molecular mass of 646.2930 Da. This is the first report of NGFFYamide purification from P. pectinifera through biochemical methods. The nucleotide sequence encoding the NGFFYamide precursor was determined, showing the presence of a conserved neurophysin domain in the C-terminal region. RT-qPCR results confirmed high expression in radial nerves cord, consistent with previous findings on NG peptides in echinoderms. In vitro pharmacological studies on muscle preparations from P. pectinifera and Asterias amurensis revealed differential relaxing activity of NGFFYamide on apical muscles, while its effects on tube foot preparations were similar in both species. NGFFYamide also induced potent contraction in P. pectinifera cardiac stomach. Comparison of three NG peptides (NGFFYamide, NGFFFamide, and NGIWYamide) on P. pectinifera cardiac stomach revealed varying potency, suggesting class-specific receptor interactions. Tachyphylaxis was observed in P. pectinifera apical muscle but not in A. amurensis , warranting further investigation. Based on these results, it is plausible that NGFFYamide could be involved in regulating locomotion and feeding behavior in P. pectinifera , consistent with findings in Asterias rubens. • NG peptides from echinoderms belong to a family of neuropeptides, and are responsible for inducing relaxing and contractile activities. • This study reports the first purification of a neuropeptide (NGFFYamide) from the starfish Patiria pectinifera. • NGFFYamide induces contraction of P. pectinifera cardiac stomach, suggesting its role in feeding and digestion regulation. • Consistent with the activity assay results, RT-qPCR results showed high NGFFYamide expression levels in the radial nerve cord and the pyloric and cardiac stomachs. • Unlike A. amurensis , the apical muscle of P. pectinifera exhibited tachyphylaxis to NGFFYamide, likely due to differences in size and movement patterns between the two starfish species. [ABSTRACT FROM AUTHOR]

The life history of Atlantic salmon (Salmo salar) includes an initial freshwater phase (parr) that precedes a springtime migration to marine environments as smolts. The development of osmoregulatory systems that will ultimately support the survival of juveniles upon entry into marine habitats is a key aspect of smoltification. While the acquisition of seawater tolerance in all euryhaline species demands the concerted activity of specific ion pumps, transporters, and channels, the contributions of Na+/HCO3− cotransporter 1 (Nbce1) to salinity acclimation remain unresolved. Here, we investigated the branchial and intestinal expression of three Na+/HCO3− cotransporter 1 isoforms, denoted nbce1.1, -1.2a, and -1.2b. Given the proposed role of Nbce1 in supporting the absorption of environmental Na+ by ionocytes, we first hypothesized that expression of a branchial nbce1 transcript (nbce1.2a) would be attenuated in salmon undergoing smoltification and following seawater exposure. In two separate years, we observed spring increases in branchial Na+/K+-ATPase activity, Na+/K+/2Cl− cotransporter 1, and cystic fibrosis transmembrane regulator 1 expression characteristic of smoltification, whereas there were no attendant changes in nbce1.2a expression. Nonetheless, branchial nbce1.2a levels were reduced in parr and smolts within 2 days of seawater exposure. In the intestine, gene transcript abundance for nbce1.1 increased from spring to summer in the anterior intestine, but not in the posterior intestine or pyloric caeca, and nbce1.1 and -1.2b expression in the intestine showed season-dependent transcriptional regulation by seawater exposure. Collectively, our data indicate that tissue-specific modulation of all three nbce1 isoforms underlies adaptive responses to seawater. [ABSTRACT FROM AUTHOR]

Peptides are naturally occurring biological molecules that are found in all living organisms. These biologically active peptides play a key role in various biological processes. The aim of this study is the extraction and the purification of bioactive materials that induce relaxation of an apical muscle from the pyloric caeca of Patiria pectinifera. The acidified pyloric caeca extract was partially separated by the solid phase extraction using a stepwise gradient on Sep-Pak C18 cartridge. Among the fractions, materials eluted with 60% methanol/0.1% trifluoroacetic acid was put a thorough of a series of high performance liquid chromatography (HPLC) steps to isolate a neuropeptide with relaxation activity. The purified compound was eluted at 28% acetonitrile in 0.1% trifluoroacetic acid with retention time of 25.8 min on the CAPCELL-PAK C18 reversed-phase column. To determine the molecular weight and the amino acid sequence of the purified peptide, LC-MS and Edman degradation method were used, respectively. The primary structure of the peptide was determined to be FGMGGAYDPLSAGFTD which corresponded to the amino acid sequence of a starfish myorelaxant peptide (SMP) isotype (SMPb) found in the cDNA sequence encoding SMPa and its isotypes. In this study, a muscle relaxant neuropeptide (SMPb) has been isolated from pyloric caeca of starfish P. pectinifera. This is the first report of SMPb isolation on the protein level from P. pectinifera.

Trypsin was isolated from pyloric caeca of European seabass (Dicentrarchus Labrax) by ammonium sulphate fractionation (30-60%) and size exclusion (Sephacryl S 200) gel filtration chromatography. The enzyme was purified at a rate of 52.71 fold with a yield of 8.60%. The molecular weight of the enzyme was estimated using a low molecular weight marker (Sigma Low Range M3193) and wide molecular weight marker (Sigma Wide Range S8445). The molecular weight of the purified trypsin was estimated to be 24 kDA by sodium dodecyl sulphate-polyacrylamide (SDS-Page) gel electrophoresis, which showed only one band in bromophenol blue staining. The optimum temperature and pH for the trypsin activity were 55 °C and pH 8.0, respectively. The enzyme was extremely stable in the pH range of 7.0-10.0 and highly (70%) stable up to 50 °C after 30 minutes incubation. Na-Benzoyl-L-arginine 4-nitroanilide hydrochloride (BAPNA) was used as a substrate for all activity and stability analyzes. Data of the study showed that temperature and pH factors that significantly affect trypsin enzyme activity. [ABSTRACT FROM AUTHOR]

The objective of the present study was to explain the histological variations in the pyloric caeca and anterior intestine of Chelon ramada. For this purpose, small pieces of the target organs were attained from specimens of C. ramada: for histological and histochemical procedures. The final sections were examined under a microscope, photographed and described. Histologically, serosa, muscularis, submucosa, and mucosae are the main layers of the wall of pyloric caeca and anterior intestine in C. ramada indicating there are no remarkable differences in the basic structure. The mucosal folds of pyloric caeca are thin and deeply folded in a narrow lumen; in contrast, the mucosal folds of the anterior intestine are long protruding at a wide lumen. The mucosal layer of the anterior intestine is consisted of columnar and mucus cells as in the pyloric caeca, but mucous cells are numerous in number at the anterior intestine while it observed in fewer numbers at the mucosal layer of the pyloric caeca. In submucosal and mucosal layers, wandering cells and lymphocytes are plentiful especially among the columnar cells of the anterior intestine. These cells are more abundant in the anterior intestine than that observed in pyloric caeca; in contrast with the number of blood vessels. The present study concluded that the distribution and secretions of the mucosa are very clear with histochemical stains. This study is helpful for understanding the digestive physiology and the related functional mechanisms of fish digestion. [ABSTRACT FROM AUTHOR]

In the present study, the effects of enrichment of Artemia franciscana with fish oil and soybean oil accompanied with vitamin E were investigated on thestructure of pyloric caeca in Persian sturgeon (Acipenser persicus) larvae. A total of 1500 Persian sturgeon larvae (with the average weight of 51±2 mg) were divided into 15 tanks. Larvae were fed for 17 days in 5 experimental treatments including the treatment C (non-enriched artemia), S15 (enriched artemia with soybean oil and 15% vitamin E), S30 (enriched artemia with soybean oil and 30% vitamin E), F15 (enriched artemia with fish oil and 15% vitamin E) and F30 (enriched artemia with fish oil and 30% vitamin E). From each traetment, 15 larvae were collected and were fixed in Bouin’s solution for histological studies. Histological results showed that both fish oil and soybean oil were the main and effective factors on the total area and histo area indices of the pyloric caeca and the enrichment of artemia with fish oil and soybean oil was significantly increased this factor as compared to that of the control treatment (P

The objective of this study was to investigate the effects of the enzymatic aided acid‐swelling process on gelatin obtained from fish by‐products. For this purpose, gelatin was extracted by an acidic swelling procedure in the presence of protease extracted from Rainbow trout pyloric caeca. The yield of gelatin extraction and the most important physicochemical characteristics of the fish gelatin samples were investigated and compared with those of commercial bovine gelatin (CBG). The yields of gelatin from Epinephelus coioides skin (ESG) either with or without crude protease from pyloric caeca (15 units/g alkaline treated) were 14.98% and 50.89%, respectively. The yields of gelatin from Cyprinus carpio scales (CSG) with crude protease from pyloric caeca (15 units/g) were 49.97%. The gel strength of the CSG (259.66 g) was significantly higher than that of CBG (228.30 g) and ESG (187.75 g). Similarly, the gelling and melting points, foaming capacity and stability, and the SDS‐PAGE pattern of gelatins were compared. The electrophoretic pattern confirmed the results of gel strength which was due to the narrower alpha and beta bands in fish skin and commercial bovine gelatins than that of fish scales gelatin. The results of this research showed that the production of high‐quality gelatin can be achieved by the enzymatically aided acid‐swelling procedure from fish scales and skin. [ABSTRACT FROM AUTHOR]

Relatively little is known about salinity acclimation in the primitive groups of fishes. To test whether physiological preparative changes occur and to investigate the mechanisms of salinity acclimation, anadromous green sturgeon, Acipenser medirostris (Chondrostei) of three different ages (100, 170, and 533 dph) were acclimated for 7 weeks to three different salinities (

In this study, the combined effect of different levels of dietary n-3 HUFAs with α-Tocopherol on changes in the structure of intestine and pyloric caeca and fatty acids profile of Caspian salmon, Salmotrutta caspius, fry (initial weight of 600 ± 25 mg for 10 weeks) were investigated. Six experimental diets containing three different dietary levels of n-3 HUFAs (Low: 1 + 0.5, DHA+ EPA, Medium: 2 + 1, DHA + EPA, High: 4 + 2, DHA + EPA g/100g diet) with two different levels of α-Tocopherol (Low: 300 and High: 1000 mg/kg diet) were prepared and named: LL, LH, ML, MH, HL, HH (HUFA/α-Tocopherol), respectively. The results showed that increase in dietary vitamin E increased HUFA levels in polar lipids, particularly when dietary HUFA were higher. Histological analysis showed the mean length of enterocytes had not significant difference in anterior intestine and pyloric caeca segments. However, in fish fed moderate and high HUFA diets enterocytes were slightly higher. Feeding Caspian salmon fry with moderate and high levels of omega 3 HUFA increased the villi area of mucus layer in anterior intestinal. The results of this study showed a concomitant increase in dietary omega 3 HUFA and vitamin E increased long chain fatty acids, especially in moderate and high levels of HUFA fatty acids, which these fatty acids have beneficial effects on the growth and health of fish.

There are four documented morphotypes of lake trout ( Salvelinus namaycush ) in Lake Superior, with the two dominant forms being the shallow water lean and the deep water siscowet. These morphotypes are differentiated externally by morphometrics and meristics. Pyloric caeca counts have been used to distinguish closely related fish species including the Salvelinus genus. From samples collected in 2009, 2011–2013, and 2017, we counted and measured pyloric caeca from 116 lean and 119 siscowet lake trout from southern Lake Superior. For a subset of 22 leans and 19 siscowets between 575 and 625 mm, we measured individual pyloric caecum basal diameter, length, and estimated individual caecum and total caeca surface areas. Siscowets had significantly fewer and thicker pyloric caeca than leans, but caecum length did not differ between the morphotypes. Mean pyloric caeca count for siscowets and leans was 131 and 153, respectively. Mean individual caecum surface area was 31% higher in siscowets than in leans. When adjusted for mean total number of pyloric caeca, total caecum surface area for siscowets was 12% greater than leans. We postulate that greater pyloric caecum surface area in siscowets may be an adaption for greater lipid uptake because they have substantially higher lipid content than leans. Based on our findings, pyloric caeca counts can be used in addition to other meristic and morphometric characteristics to help distinguish lean and siscowet lake trout. [ABSTRACT FROM AUTHOR]

The brooding sea star Anasterias antarctica is distributed from the coast of Patagonia to the northern Peninsula of Antarctica. In the Beagle Channel, the females of A. antarctica brood their eggs for seven months and do not feed during this period. The endoparasite Dendrogaster argentinensis (Crustacea: Ascothoracica) causes castration in several species of Anasterias. We randomly collected four samplings of adults in May, August and October (brooding period) and January (non-brooding period). The gonad (GI) and pyloric caeca index (PCI) were calculated as organ wet weight (g)×100/total wet weight (g). Each individual was sexed by microscopic examination of the gonads. Sex ratio, brooding females/non-brooding females and mature females/ non-mature females ratios was 1:1. The male GI reached maximum values in January, when most individuals were sexually mature. The GI of non-brooding females reached its maximum during October when it was significantly higher than those from brooding females. The PCI was minimum in October, being lower in brooding females (August and October). During the non-brooding period, mature females had a significantly higher GI than non-mature females. The PCI did not vary neither between males, nor between mature and non mature females. By the end of the brooding period, non-brooding females showed a higher GI than the brooding females. This is explained by proliferation and increase of the oocytes size of non-brooding females. Mature females showed an incremented GI with presence of mature oocytes, while non-mature females exhibited more abundance of previtelogenic oocytes. Males showed synchronicity in reproductive condition. The females that have not brooded presented a process of active gametogenesis, reaching the summer with a high GI, therefore becoming mature females. Females that had brooded were probably lacking energy for new gonadal maturation. The pyloric caeca would be performing the role of a reserve organ in the brooding females, decreasing its size during the brooding period. Prevalence of D. argentinensis in A. antarctica was 11.06%. As this parasite was recorded in sea stars lacking gonads, these infected hosts could have been castrated. [ABSTRACT FROM AUTHOR]

The chum salmon of the Amur River (the mainland part of the Far East) and the Poronai River (Terpeniya Bay, Sakhalin Island) are historically related to one another, as the drainage basins of these rivers are the remnants of a formerly single river system, the Paleoamur, which existed when Sakhalin Island was a part of the continent. Both river populations of chum salmon consist of the early-run and late-run ecological forms (seasonal races), which are also referred to as the summer and autumn races. They are reproductively isolated from each other due to their spawning at different times and in different types of spawning grounds. To assess the direction, pattern, and degree of divergence between these chum salmon races in the both river fragments since the Paleoamur, it is necessary to compare them using two types of traits: selectively neutral DNA markers and morphological and physiological traits, variations in which may have an adaptive value. For this, we have studied chum salmon from both rivers in terms of microsatellite DNA markers, body counts and measurements, body weight, and fecundity. Both in the Amur River and in the Poronai River, the autumn race of chum salmon prevails over the summer race in body length and weight, fecundity, number of pyloric caeca, and several other meristic traits. The intra-basin differences between the races are much more pronounced in the Amur chum salmon. The inter-race differences in microsatellites are also greater in the Amur chum salmon compared to the Poronai chum salmon. Using microsatellites, three levels of differentiation have been revealed: (1) between the basins of the Amur and Poronai rivers, (2) between the races within each of the river basins, (3) and between population samples within each race of each basin. A hypothesis is proposed that the currently existing races of chum salmon in the Amur and Poronai rivers have evolved since the breakup of the Paleoamur, and the intra-basin divergence of the races started in the Amur River earlier than in the Poronai River. An analysis of our own data and the published data suggests that the adaptation of the seasonal races of chum salmon to the conditions of their spawning grounds is determined by a complex of morphological and physiological traits, including the number of pyloric caeca, which is an adaptive and highly heritable trait associated with the incubation temperature of the water. [ABSTRACT FROM AUTHOR]

Legumes such as soybean, peas and lupin have attracted considerable interest as potential sources of protein to replace finite and limiting supplies of marine fishmeal (FM) as major ingredients for aquafeeds. In this respect, faba beans ( Vicia faba ) represent a widespread and relatively unexploited legume crop in Europe with potentially favourable characteristics. However, for carnivorous species such as Atlantic salmon ( Salmo salar ), protein levels in legumes are generally too low and require to be concentrated to be direct replacements for FM. Previously we showed that a faba bean protein concentrate, produced by air classification, containing 55% protein could partially replace FM and/or soy protein concentrate (SPC) in feeds for parr and post-smolt salmon. In the present study, a faba bean protein isolate (BPI), produced by a wet process, with almost ~ 80% crude protein was investigated in feeds for Atlantic salmon in seawater. Four dietary treatments were tested including one with high inclusion of FM (400 g kg − 1 ) and three with low FM (216 g kg − 1 ) and increasing inclusions of BPI (0, 70 and 140 g kg − 1 ) substituting for SPC (236, 125 and 45 g kg − 1 ). Growth performance in fish was unaffected with the lower level of dietary BPI, but was reduced in fish fed the higher level, mainly due to feed intake being reduced initially. Histological analysis of the distal intestine showed inflammation in fish fed both diets containing BPI, but especially at 140 g kg − 1 . The high dietary level of BPI affected the transcriptome of pyloric caeca with almost 2000 differentially expressed genes (DEG) compared to fish fed FM, whereas fish fed SPC or the lower level of BPI showed no DEG compared to fish fed FM. In contrast, the liver transcriptome was generally affected similarly by both BPI and SPC. The combined data suggested that the BPI utilised contained a factor that was detrimental above a certain threshold and, although this factor could be an artefact of the protein isolation method, an effect of a known ANF could not be excluded with saponin the most likely candidate. Overall, however, the results of the present study confirmed that protein concentrates or isolates derived from faba beans can replace FM and/or SPC up to a certain level in feeds for Atlantic salmon. Statement of relevance A study testing novel raw materials for fish feed. [ABSTRACT FROM AUTHOR]

To assess the effects of dietary nucleotide on structure of pyloric caeca in Salmo trutta caspius, 315 juvenile fish with average weight of 12.26g (average length 11.12cm) were fed with dietary nucleotide (NT) and a control diet for 8 weeks (0.25% NT, 0.5% NT and 0% as control). To investigate the changes of pyloric caeca structure, 6 fish specimens from each treatment fixed into Bouin solution for histological examinations. Then, the sample was placed in paraffin, and 4mm sections of samples were provided and after coloration were investigated for histological features. The investigation demonstrated that both NT-supplemented diets had significant effects (P0.05). However, the group receiving 0.25% NT showed more positive effects on enterocyte cell number and thickness of muscle layer compared with those treated with 0.5% NT.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Adult traíra (Hoplias malabaricus) were submitted to different periods of food deprivation (from 30 to 240 days) and refed for 30 days after 90 and 240 days of starvation. Stomach length remained constant during all the experimental period. However, the intestine length was significantly reduced after 30 days of food deprivation. Normal length was not recovered after refeeding. The number of pyloric caeca did not change significantly. Conversely, caeca thickness decreased after 150 days of starvation and their length decreased after 180 days. After refeeding, however, the pyloric caeca recovered original thickness. In fish refed after 240 days of starvation the length of these structures seemed to present compensatory growth, becoming longer than in the control group.Traíras (Hoplias malabaricus) adultas foram submetidas a diferentes períodos de privação de alimento (de 30 a 240 dias) e realimentadas por 30 dias após 90 e 240 dias de jejum. O comprimento do estômago permaneceu constante durante todo o tempo experimental. No entanto, o comprimento do intestino reduziu significativamente após 30 dias de jejum. O comprimento normal não foi recuperado após a realimentação. O número de cecos pilóricos não sofreu modificações significativas. Por outro lado, a espessura dos cecos diminuiu após 150 dias de privação de alimento e seu comprimento diminuiu após 180 dias. Após a realimentação, porém, os cecos pilóricos recuperaram a espessura original. Nos peixes realimentados após 240 dias de jejum, os comprimentos dessas estruturas aparentemente apresentaram crescimento compensatório, tornando-se mais longas que as do grupo controle.

Abstract: Lipid content and composition in aquafeeds have changed rapidly as a result of the recent drive to replace ecologically limited marine ingredients, fishmeal and fish oil (FO). Terrestrial plant products are the most economic and sustainable alternative; however, plant meals and oils are devoid of physiologically important cholesterol and long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic (EPA), docosahexaenoic (DHA) and arachidonic (ARA) acids. Although replacement of dietary FO with vegetable oil (VO) has little effect on growth in Atlantic salmon (Salmo salar), several studies have shown major effects on the activity and expression of genes involved in lipid homeostasis. In vertebrates, sterols and LC-PUFA play crucial roles in lipid metabolism by direct interaction with lipid-sensing transcription factors (TFs) and consequent regulation of target genes. The primary aim of the present study was to elucidate the role of key TFs in the transcriptional regulation of lipid metabolism in fish by transfection and overexpression of TFs. The results show that the expression of genes of LC-PUFA biosynthesis (elovl and fads2) and cholesterol metabolism (abca1) are regulated by Lxr and Srebp TFs in salmon, indicating highly conserved regulatory mechanism across vertebrates. In addition, srebp1 and srebp2 mRNA respond to replacement of dietary FO with VO. Thus, Atlantic salmon adjust lipid metabolism in response to dietary lipid composition through the transcriptional regulation of gene expression. It may be possible to further increase efficient and effective use of sustainable alternatives to marine products in aquaculture by considering these important molecular interactions when formulating diets. [Copyright &y& Elsevier]

Given the drift to improve economic and ecological sustainability of the aquaculture sector, novel ingredients fulfilling these requirements are sought. Hermetia illucens , commonly called black soldier fly, (Diptera: Stratiomydae; H) is a promising dietary protein source but its effect on fish gut microbiota is still to be clarified. The aim of the present study was to increase the knowledge of the effect of dietary full-fat H meal on rainbow trout (Oncorhynchus mykiss) microbiota and, in particular, on intestinal mucosa-adherent microbiota by applying a dual approach based on polymerase chain reaction-denaturing gradient gel electrophoresis and high-throughput sequencing of the 16S rRNA gene. Rainbow trout (initial body weight of 137.3 ± 10.5 g) was fed for 98 days with a control diet (H0) containing fishmeal and protein-rich vegetable ingredients and an experimental diet (H50) where 50% of the fishmeal had been replaced by full-fat H meal rich in saturated fatty acids. Proteobacteria, Firmicutes and Actinobacteria were generally present in all samples, although the core microbiota (relative prevalence higher than or equal to 80% in all samples) only consisted of the proteobacteria Caulobacter , Delftia , Agrobacterium and Ochrobactrum. In addition, Streptococcus infantis and a member of the Cytophagaceae family were part of the core taxa of mucosa samples. Tenericutes were abundant in pyloric caeca samples and, among them, Mycoplasmataceae seemed to increase in the group fed the high saturated fatty acid diet containing H meal; a consideration about the connection between this bacterial group and the dietary lipid content must be considered. Dietary treatment did not clearly affect alpha-diversity metrics, but mucosa samples tended to be more resilient to dietary changes than content samples. Permutational analysis of variance showed significantly different β-diversities between diets (p < 0.05) but principal coordinates analysis did not confirm this result. Diets for rainbow trout containing full-fat H meal determined interesting modifications in the gut microbiota with patterns similar to the ones found in the literature. The dietary lipids can exert an effect on microbiota. Nonetheless, research data on this topic are still scarce and further studies are highly encouraged. • Rainbow trout were fed diets containing full-fat Hermetia illucens larvae meal. • Gut content and mucosa microbiota of fish fed full-fat H. illucens analysed separately. • Mycoplasmataceae seemed to increase in the high saturated fatty acid-fed group. • Recurring patterns between literature and the study. • No clear hypothesis on the microbiota structure and diversity. [ABSTRACT FROM AUTHOR]

The article discusses a study which evaluated histological changes in the tissues of crown-of-thorns starfish Acanthaster planci (COTS) after injection of thiosulfate-citrate-bile-sucrose agar (TCBS) that was used as a disease inducer or potential outbreak control method, by conventional and scanning electron microscopy. Digestive glands were processed and stained with hematoxylin and eosion and healthy versus infected tissues and Gram stains were compared. The study found that fulminating systemic dysbiosis were consistent with vibrio infections.

The article discusses a study on a process of transmural passive displacement of a digenean parasite in the digestive tract of the roughsnout grenadier Trachyrincus scabrus. A digenean parasite Bathycreadium elongatum abound within pyloric caeca in 74.4% of T. scabrus with a mean of 44 individuals per fish. The study found that the process, which eliminate intestinal parasites, seems to have a detrimental effect on the Bathycreadium elongatum cycle since some of the parasites are trapped in the connective tissue.

A lipolytic activity was located in the sardine digestive glands (pyloric caeca), from which a sardine digestive lipase (SaDL) was purified. Pure SaDL has a molecular mass of 43 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. The enzyme was found to be more active on short-chain triacylglycerols than on long-chain ones. SaDL does not present the interfacial activation phenomenon. Control experiments were performed under the same experimental conditions, with dromedary and turkey pancreatic lipases and showed a positive interfacial activation phenomenon. Sodium deoxycholate (NaDC) has an inhibitory effect on the lipase activity. The pure enzyme lost 40% of its activity in presence of 8 mM NaDC. SaDL was found to be mostly stable at low pH values. Interestingly, no colipase was detected in the sardine pyloric caeca. Analogous results were reported for the scorpion and the crab digestive systems. This is in line with the idea that colipase might has evolved in mammal animals simultaneously with the appearance of an exocrine pancreas. No similarity was found between the NH2-terminal amino acid residues of SaDL and those of lipases from the digestive tract of other species. Altogether, these results suggest that SaDL is a member of a new group of lipases belonging to aquatic species. [ABSTRACT FROM AUTHOR]

Comparative study of representatives of the family Scophthalmidae was performed. The topography of head sensory canals was studied; some osteological specific features and data on pyloric caeca were specified; and the presence of an outgrowth of operculum pupillare in several species was described. The found differences have different level of taxonomic significance; the most informative is the structure of the seismosensory system, in whose specific features a vector of reduction trend of evolutionary transformations is traced. On the whole, its structure agrees with present concepts of the group phylogeny. The genus Scophthalmus is characterized by the greatest number of plesiomorphies. No differences were found between the Atlantic and Black Sea representatives of the species S. maximus. Lophopsetta aquosa is considerably separated by reduction of the infraorbital canal of the eyed side. The similarity of Z. regius and Z. punctatus and the difference of both species from Phrynorhombus norvegicus support assigning Z. regius to the genus Zeugopterus. P. norvegicus is characterized by several apomorphies, which provides the given taxon the most advanced position in the family. [ABSTRACT FROM AUTHOR]

Abstract: Trypsin was purified from the pyloric caeca of brownstripe red snapper (Lutjanus vitta) by ammonium sulphate (40–60% saturation) precipitation, soybean trypsin inhibitor (SBTI)-Sepharose 4B column and DEAE-Sephacel column chromatography. Purified trypsin showed a single band on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) and native-PAGE. A yield of 4.9% with the purification-fold of 20 was obtained. Trypsin had an apparent molecular weight of 23kDa. SBTI and N-ρ-tosyl-l-lysine-chloromethylketone (TLCK) showed a strong inhibitory effect on the purified trypsin, while other protease inhibitors exhibited negligible inhibition. Trypsin had maximal activity at pH 8.5 and 60°C for the hydrolysis of α-N-benzoyl-dl-arginine-ρ-nitroanilide (BAPNA). It was stable within the temperature range of 25–55°C and pH range of 7.0–10.0. Purified trypsin had a Michaelis–Menten constant (K m) and catalytic constant (k cat) of 0.507mM and 4.71s−1, respectively, when BAPNA was used as the substrate. For the hydrolysis of α-N-ρ-tosyl-l-arginine methyl ester (TAME), K m and k cat were 0.328mM and 112s−1, respectively. [Copyright &y& Elsevier]

Abstract: Proteolytic activity of pyloric caeca extract (PCE) from bigeye snapper (Priacanthus macracanthus) was studied. The highest activity was observed at 55°C and pH 8.0 when casein, N α-Benzoyl-dl-arginine-p-nitroanilide (BAPNA) and N α-p-Tosyl-l-arginine methyl ester hydrochloride (TAME) were used as the substrates. The activity was inhibited markedly by 1mg/ml soybean trypsin inhibitor, whereas E-64, pepstatin A and EDTA exhibited a negligible effect on activity. The results suggested that a trypsin-like enzyme was most likely the major proteinase in PCE. As determined by activity staining, two proteolytic activity bands with apparent molecular weights of 55 and 24kDa were found. Gelatin hydrolysate from bigeye snapper skin prepared using PCE exhibited the increases in 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities and ferric reducing antioxidative power (FRAP) as degrees of hydrolysis (DHs) increased (P <0.05). Hydrolysates derived from gelatin using Alcalase combined with PCE showed the highest ABTS radical scavenging activity (P <0.05). Gelatin hydrolysate prepared using Alcalase in combination with Neutrase or PCE at 500 and 1000ppm, respectively, retarded the oxidation in both linoleic acid oxidation and lecithin liposome oxidation systems. The antioxidative peptide of gelatin hydrolysate had a molecular weight of 1.7kDa. [Copyright &y& Elsevier]

Variations in fish condition, pyloric caeca (PC) mass and tissue metal concentrations were examined in two consecutive summers in yellow perch collected along two polymetallic gradients in Canada, Sudbury (ON) and Rouyn-Noranda (QC). The potential of PC mass variations to help interpret food web-mediated changes in condition was also evaluated. The lack of relationships between PC weight and condition, even in reference lakes, indicated that factors other than feeding rate influenced fish condition. Inter-annual variations in fish condition (12–58%), PC weight (14–20%) and tissue metal concentrations (30–550%) were often of greater magnitude than differences between reference and contaminated fish sampled in the same year. The apparent lack of correspondence between feeding rate and condition and the large inter-annual variation in examined metrics highlight the need to better understand the ecological underpinnings that influence metal toxicity in field situations. [Copyright &y& Elsevier]

Abstract: This study on yellow perch (Perca flavescens) examines a series of enzymatic markers and the relative weights of pyloric caeca and visceral lipids, their response to changes in feeding regime and their potential use to infer recent changes in growth rate and fish condition. Fish were exposed to four different feeding regimes for 12 weeks resulting in specific growth rates ranging from 0.3% to 3.5% (%/day). Growth and condition responded rapidly to changes in ration and the weight of pyloric caeca and visceral lipids reflected increased feed intake. Growth rate was correlated with muscle citrate synthase and caecal nucleoside-diphosphate kinase activities, whereas condition was correlated with muscle citrate synthase and lactate dehydrogenase activities and with caecal glucose-6-phosphate dehydrogenase activity. Results showed that enzyme activities and biometric parameters responded rapidly to increased feed intake, but the response was slower when food intake decreased. Plateaus were attained for both condition and visceral lipid index, but the relative weight of pyloric caeca continued to increase throughout the experimental period. Results from this study could, in principle, be used to infer recent growth and energy status in wild yellow perch and thus provide an indicator of food availability in their environment. [Copyright &y& Elsevier]

Abstract: Proteases from pyloric caeca extract of three fish species including brownstripe red snapper (Lutjanus vitta), bigeye snapper (Priacanthus tayenus) and threadfin bream (Nemipterus marginatus) were comparatively studied. The extracts from bigeye snapper and threadfin bream exhibited the highest hydrolytic activities toward casein, α-N-benzoyl-dl-arginine-p-nitroanilide and α-N-ρ-tosyl-l-arginine methyl ester at pH 8.0 and 60 °C and pH 8.5 and 55 °C, respectively. The extract of brownstripe red snapper showed the optimal pH and temperature of 8.0 and 60 °C with all substrates used except the optimal temperature was 65 °C when casein was used. All proteases were strongly inhibited by soybean trypsin inhibitor (SBTI) and N-ρ-tosyl-l-lysine chloromethylketone (TLCK) and partially inhibited by N-tosyl-l-phenylalanine chloromethylketone for all substrates tested, suggesting that trypsin-like proteases were the major enzymes. Substrate-gel activity staining of 40–60% ammonium sulfate (AS) fraction revealed that major activity bands were observed with molecular mass of 24, 22 and 20 kDa for brownstripe red snapper, bigeye snapper and threadfin bream, respectively. Those activity bands were partially inhibited by SBTI and TLCK. AS fraction was further used to produce gelatin hydrolysate from the skin of brownstripe red snapper with different degrees of hydrolysis (DH). Hydrolysate with DH of 15% exhibited the highest DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power (p <0.05). Therefore, the extract from pyloric caeca could be used to produce the gelatin hydrolysates possessing antioxidative activities. [Copyright &y& Elsevier]

Abstract: The humoral control of secretion of the proteolytic enzymes trypsin and chymotrypsin was studied in yellowtail (Seriola quinqueradiata). In vitro trials were performed to investigate the effects of cholecystokinin (CCK) and two commercially available gastrin peptides. Isolated preparations of pyloric caeca/pancreas release trypsin and chymotrypsin when incubated with cholecystokinin (CCK) at 10 μM and gastrin I (G1) at 50 μM after 15 min of incubation. On the other hand, G1 at 10 μM and gastrin-related peptide (G2) did not enhance trypsin and chymotrypsin secretion. The studies concerning the CCK effects at different incubation temperatures have shown that trypsin and chymotrypsin secretion at 25 °C was stimulated by CCK after 15 min, while at 10, 15 and 20 °C the stimulatory effects of CCK were observed only after 30 min of incubation. The CCK effects were increased at higher incubation temperatures and longer incubation periods. [Copyright &y& Elsevier]

Parental and individual variance components of body length, weight, condition (estimated as the second principal component of the length–weight relationship) and pyloric caeca number were investigated in 6-month-old brown trout ( Salmo trutta L.) by the mean of two sib analyses, which provided consistent results. The average heritabilities (±SE) were 0.12 (±0.08) for length, 0.16 (±0.08) for weight, 0.47 (±0.14) for condition and 0.38 (±0.12) for pyloric caeca number. Maternal effects were also observed, although short of significance, in length, weight and caeca number. Correlations between caeca number and body size averaged +0.10 among individuals within lots, but genetic correlations were negative, i.e. about −0.9 for length and −0.7 for weight. There was no significant correlation between caeca number and condition. These results lead to question the role that pyloric caeca may play in growth, as well as their usefulness in fish breeding. [ABSTRACT FROM AUTHOR]

Abstract: The pyloric caeca of fishes are a major site for nutrient digestion and absorption. Some studies have reported an association between increased caeca number, improved feed efficiency and faster overall growth in rainbow trout. However, little is known concerning the genetic basis underlying pyloric caeca development in any fish species. We have identified two clonal rainbow trout lines that differ in pyloric caeca number. Doubled haploid progeny produced from an F1 hybrid of these lines were used to evaluate the possibility of joint segregation of pyloric caeca phenotype with 330 amplified fragment length polymorphic (AFLP) markers and 39 microsatellites genotyped in 54 individuals. A genetic map has been constructed based on these genotypes and composite interval mapping revealed three major quantitative trait loci (QTL) associated with pyloric caeca number. These QTL respectively explain 19.2%, 18.6% and 13.5% of the variation in pyloric caeca number observed within the doubled haploid progeny. Because these QTL span 3 separate linkage groups, our results demonstrate the phenotype of pyloric caeca number is a polygenic trait in rainbow trout. [Copyright &y& Elsevier]

Abstract: Trypsin from pyloric caeca of Monterey sardine was purified by fractionation with ammonium sulfate, gel filtration, affinity and ionic exchange chromatography. Fraction 102, obtained from ionic exchange chromatography, generated one band in sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing. The molecular mass of the isolated trypsin was 25 kDa and showed esterase-specific activity on Nα-p-tosyl-l-arginine methyl ester (TAME) that was 4.5 times greater than amidase-specific activity on N-benzoyl-l-arginine-p-nitroanilide. The purified enzyme was partially inhibited by the serine-protease phenyl-methyl-sulfonyl fluoride (PMSF) inhibitor and fully inhibited by the soybean trypsin inhibitor (SBTI) and benzamidine, but was not inhibited by the metallo-protease inactivator EDTA or the chymotrypsin inhibitor tosyl-l-phenylalanine chloromethyl-ketone. The optimum pH for activity was 8.0 and maximum stability was observed between pH 7 and 8. A marked loss in stability was observed below pH 4 and above pH 11. Activity was optimum at 50 °C and lost activity at higher temperatures. The kinetic trypsin constants Km and kcat were 0.051 mM and 2.12 s−1, respectively, while the catalytic efficiency (kcat/Km) was 41 s−1 mM−1. General characteristics of the Monterey sardine trypsin resemble those of trypsins from other fish, especially trypsins from the anchovy Engraulis japonica and Engraulis encrasicholus and the sardine Sardinops melanostica. [Copyright &y& Elsevier]

The anatomical proximity and embryological relationship of the pyloric caeca (PC) and small intestine of rainbow trout has led to the frequent assumption, on little evidence, that they have the same enzymes and transporters. In trout, the PC is an important absorptive organ for dietary nutrients, but its role in dietary P absorption has not been reported. We found that apical inorganic phosphate (Pi) transport in PC comprises carrier-mediated and diffusive components. Carrier-mediated uptake was energy- and temperature-dependent, competitively inhibited and Na+-independent, and greater than the Na+-dependent intestinal uptake. Pi uptake in PC was pH-sensitive in the presence of Na+. Despite the active Pi transport system in PC, high postprandial luminal Pi concentrations (∼20 mmol 1-1) indicate that diffusive uptake represents ∼92% of total Pi uptake in PC of fed fish. The nucleotide sequence of a sodium-phosphate cotransporter (NaPi-II) isoform isolated from PC was ∼8% different from the intestinal NaPi cotransporter. PC-NaPi mRNA was abundant in PC but rare in the intestine, whereas intestinal NaPi mRNA was abundant in the intestine but scarce in PC. Dietary P restriction reduced serum and bone P concentrations, increased intestine-type, but not PC-type, NaPi mRNA in PC, and increased Pi uptake in intestine but not in PC. Intestine-type NaPi expression may be useful for predicting dietary P deficiency. [ABSTRACT FROM AUTHOR]

The partial sequencing of two lipases from winter flounder Pseudopleuronectes americanus , one most closely related to gastric, lingual and lysosomal acid lipase from other vertebrates and one most closely related to bile salt-activated lipase, is reported. Biochemical analyses of enzymatic activity demonstrated the greater contribution made by bile salt-activated lipase relative to neutral bile salt-independent lipase. Using molecular techniques, the tissue-specific expression of bile salt-activated lipase in pancreatic tissue and acid triacylglycerol lipase in a wide variety of organs was demonstrated. Furthermore, the developmental expression of these types of lipase in larval fish was established. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine whether digestive capacity correlates with growth rate in Atlantic cod ( Gadus morhua). Ninety fish (1035±240 g; 478±36 mm) were assigned to one of three treatments: deprived of food for 5 weeks and then re-fed for 24 days, deprived for 10 weeks and then re-fed for 24 days, or fed for 24 days without deprivation (controls). Three times a week during feeding, the fish were provided with meals of capelin ( Mallotus villosus) in excess. Within each treatment, ten fish were sacrificed before and twenty after the feeding period. The relative masses of the pyloric caeca, intestine, and white muscle were determined. Cytochrome c oxidase (CCO), citrate synthase (CS), and nucleoside diphosphate kinase (NDPK) activities were assayed in the pyloric caeca, intestine, and muscle as was trypsin activity in the pyloric caeca. During the re-feeding period, fish that had been deprived of food for 10 weeks showed compensatory growth, growing 1.9 times faster than the controls (0.94±0.26 versus 0.50±0.31% body mass ⋅ day−1). Fish that displayed compensatory growth had a lower relative white muscle mass than controls (66.5±4.1% vs. 69.6±7.4%) while the relative masses of the pyloric caeca (2.21±0.49% vs. 1.78±0.31%) and intestine (0.95±0.20% vs. 0.77±0.15%) were greater than the controls, suggesting that the sizes of these digestive tissues might correlate with compensatory growth capacity. Citrate synthase in the pyloric caeca was the only enzyme that showed higher activity during compensatory growth (8.57±0.94 U ⋅ g tissue−1 compared to 7.13±1.03 U ⋅ g tissue−1 in the control group). This suggests that aerobic catabolic capacity of pyloric caeca could be related to growth capacity during recovery, possibly via the energetic cost of digestive enzyme synthesis. [ABSTRACT FROM AUTHOR]

Artificial diets affect the growth and gut morphology of carnivorous fishes. In this study, we compared a laboratory raised rockfish, Sebastes schlegelii (a carnivore), fed an artificial diet (Lab fish), and the wild-captured rockfish (Wild fish) to confirm the effect of an artificial diet on pyloric caecal morphology and motility. We also established an in vitro method to quantify pyloric caecal sac motility and compared it between Lab and Wild fish. The pyloric caecal length per unit body length, the pyloric caecal weight per unit body weight, and the pyloric caecal weight per length were significantly greater in the Wild fish than in the Lab fish. Additionally, both of the circular and longitudinal muscularis layers were significantly thicker in the Wild fish than in the Lab fish. The pyloric caecal motor frequency of the Wild fish was higher than that in the Lab fish, but the contractile pressure of the pyloric caeca did not change under conventional conditions. These results suggest that the thickness of the tunica muscularis of the pyloric caeca may be involved in its motility, and the pyloric caeca of the Lab fish may not be able to provide functionality in this respect. In conclusion, under artificial rearing conditions, the artificial diet reduced the thickness of the tunica muscularis and reduced the motor frequency of the pyloric caeca in rockfish. • An in vitro assay method for fish pyloric caecal motility was established. • Pyloric caeca (PC) of Kurosoi rockfish were compared between lab-reared fish (Lab fish) and wild fish. • PC motor frequency was lower in Lab fish. • PC tunica muscularis in Lab fish was atrophied. • Artificial diets likely lead to muscle atrophy, affecting motor frequency. [ABSTRACT FROM AUTHOR]

The thermoanalytical behaviour of pyloric caeca during salting and ripening was investigated using a Perkin Elmer DSC 7. Not only the thermal stability of the muscle proteins was influenced by salting but also that of pyloric caeca. It was recognised that the salting itself leads to a remarkable increase of the transition temperature compared with raw herring. An influence of the salt:fish ratio could be observed. The higher the salt content the higher the increase of the denaturation temperature. During ripening the transition temperature remained on a high level or showed only a slight decrease during the investigation period. The dependency from the salt content remained evident. The increase of the transition temperature was accompanied by a decrease of the transition enthalpy. The increase of thermal stability is connected with a decrease of the general proteolytic activity in pyloric caeca. Possibly, the enzymes are diffusing from the pyloric caeca into the muscle and cause there an increase of enzymatic activity observable in North Sea herring accompanied by a decrease of activity in pyloric caeca itself. Simultaneous the thermal stability of pyloric caeca is lowered. The reason for the differences in ripening could be seen in some enzyme-inhibiting factors unknown until now. [ABSTRACT FROM AUTHOR]

Seastars (Asterias rubens L.) were collecte d at sampling locations in different areas along transects radiating into the southern North Sea, representing areas impacted by contaminants to different degrees. Strand breakage in DNA isolated from tissue of the pyloric caeca was measured by the alkaline unwinding assay, modified to allow for the isolation of highly intact DNA. The interpretation of the results is based on the incidence of DNA strand breaks (expressed as the double:total DNA ratio or F value, indicating the degree of double-strandedness). The cytochrome P-450 concentration and the benzo [a] pyrene (BaP) hydroxylase activity were measured in microsomal fractions of the pyloric caeca. The chlorinated biphenyl (CB) congeners in tissue samples from the digestive gland were determined by temperature-programmed gas-chromatography, with a CPSil8 capillary column as the stationary phase, hydrogen as the carrier gas and 63Ni-electron capture detection. Areas where seastars showed different DNA integrity could be described. The highest integrity (0.75 < F < 0.85) was found in the off-shore reference sites of the Dogger Bank and Southern Bight. The mean F value in seastars from most sampling locations varied between 55 and 75%. The lowest DNA integrity (0.35 < F < 0.55) was found in specimens obtained from sampling locations near the river Rhine delta, along the Dutch coast and at two expected uncontaminated offshore areas. The BaP hydroxylase activity was relatively high near the mouth of the rivers Rhine and Scheldt, but also at a supposedly clean site near Dogger Bank. The concentration of CB congeners in the pyloric caeca of seastars decreased along transects radiating into the southern North Sea from the coastal areas of the Netherlands; the highest concentrations were in the nearby coastal areas and the lowest were in the open sea sampling locations. The data indicate that there might be a relationship between pollution from the Rivers Rhine, Meuse and Scheldt and the incidence of DNA strand breaks and/or BaP hydroxylase activity [ABSTRACT FROM AUTHOR]

Rainbow trout were killed 4 and 18 h after being fed wax ester-rich marine Zooplankton and the absorptive epithelium of the pyloric caeca examined by electron microscopy. Numerous osmiophilic drops were seen in the lamina propria underlying the epithelium of fish killed at both times, but these drops were only abundant within columnar epithelial cells of fish killed 4 h after feeding. Pinocytotic profiles were not common at the luminal plasma membranes, nor were osmiophilic droplets seen in the terminal web area between the luminal plasma membrane and the extensive smooth endoplasmic reticulum. Numerous osmiophilic droplets, 30-100 nm in diameter, were present in the cisternae of the smooth endoplasmic reticulum with up to five separate droplets per individual cisterna. Columnar epithelial cells also contained up to 100 large osmiophilic drops ('conglomerates') which tended to be concentrated in the supranuclear (Golgi) regions. The conglomerates were 250-1200 nm in diameter and were themselves made up of smaller droplets 30-400 nm in diameter. Conglomerates were present both within intracellular membranes and free in the cytoplasm. Osmiophilic droplets in the intercellular spaces and lamina propria were similar in size to individual droplets within conglomerates. We conclude that triacylglycerols are elaborated in the smooth endoplasmic reticulum, transferred to and processed in the Golgi region and finally discharged serosally as chylomicron-like particles of not greater than 400 nm diameter. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The coexistence of immunoreactivities to cholecystokinin, glucagon, glucagon-like peptide 1, salmon pancreatic polypeptide, neuropeptide tyrosine, and peptide tyrosine tyrosine was studied immunocytochemicaly, revealing for the first time in fish intestine the existence in the same cell of immunoreactivities to cholecystokinin-glucagon/glucagon-like peptide 1, cholecystokinin-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-salmon pancreatic polypeptide, glucagon/glucagon-like peptide 1-neuropeptide tyrosine, salmon pancreatic polypeptide tyrosine tyrosine, and glucagon/glucagon-like peptide 1-peptide tyrosine tyrosine. Colocalization of cholecystokinin-salmon pancreatic polypeptide was observed only in the pyloric caeca of the rainbow trout Oncorhynchus mykiss, while the other colocalizations also occurred in proximal and middle intestinal segments. In all cases, endocrine cells immunoreactive to only one of the paired antisera were detected except for anti-glucagon and anti-glucagon-like peptide 1, which always immunostained the same cells. [ABSTRACT FROM AUTHOR]