Intestinal Mucous Cells Research Articles

Microscopic Characterization of the Mucous Cells and Their Mucin Secretions in the Alimentary Canal of the Blackmouth Catshark Galeus melastomus (Chondrichthyes: Elasmobranchii)

Sharks belong to the most primitive group of jawed vertebrates and have some special structural and functional features such as a cartilaginous skeleton, a spiral intestinal valve, and a rectal gland for osmoregulation. In January 2020, ten specimens of Galeus melastomus, the Blackmouth catshark, were collected from the Gulf of Asinara (North Sardinia, Italy) and the entire alimentary canal was studied using histochemical reactions to characterize the mucous cell types. In the alimentary canal of G. melastomus, mucous cells mainly secrete a mixture of acidic and neutral mucins. Of the acidic mucins, only the carboxylated type was present in mucous cells of the stomach, while the sulfated type predominated in the esophagus and the intestines. The use of lectins revealed a distribution of sugar residues in mucins related to cellular activities of the different regions of the catshark alimentary canal. The current study is the first report to characterize the intestinal mucous cells of G. melastomus and to provide quantitative data on their different populations in the alimentary canal.

Long noncoding RNA TUG1 regulates the progression of colorectal cancer through miR-542-3p/TRIB2 axis and Wnt/\u03b2-catenin pathway

BackgroundColorectal cancer (CRC) is one of the third normal malignancy worldwide. Taurine-upregulated gene 1 (TUG1), a member of long noncoding RNAs (lncRNAs), has been reported to be involved in various cancers. However, the mechanism underlying TUG1 in the progression of CRC remains unclear.MethodsThe expression of TUG1, microRNA-542-3p (miR-542-3p), and tribbles homolog 2 (TRIB2) in CRC tissues and cells (LoVo and HCT116) were detected by quantitative real-time PCR (qRT-PCR). Methyl thiazolyl tetrazolium (MTT), transwell and flow cytometry assays were employed to evaluate the effects of TUG1 in CRC cells. The interaction between miR-542-3p and TUG1 or TRIB2 were verified by dual-luciferase reporter assay. A xenograft tumor model in nude mice was established to investigate the biological role of TUG1 in CRC in vivo.ResultsTUG1 was increased in CRC tissues and cells (LoVo and HCT116) in contrast with adjacent normal tissues and normal intestinal mucous cells (CCC-HIE-2). Downregulation of TUG1 or TRIB2 suppressed the proliferation, migration, invasion, and induced apoptosis in CRC cells. And knockdown of TUG1 repressed tumor growth in vivo. Besides, overexpression of TRIB2 reversed the effects of TUG1 depletion on the progression of CRC. Meanwhile, TUG1 interacted with miR-542-3p and TRIB2 was a target of miR-542-3p. Furthermore, miR-542-3p knockdown or TRIB2 overexpression partly reversed the suppression effect of TUG1 depletion on the Wnt/β-catenin pathway.ConclusionsTUG1 served as a tumor promoter, impeded the progression of CRC by miR-542-3p/TRIB2 axis to inactivate of Wnt/β-catenin pathway, which providing a novel target for CRC treatment.

Metabonomics study of Shouhui Tongbian Capsules in slow transit constipation based on UPLC-ESI-QE-Orbitrap-MS

The effect of Shouhui Tongbian Capsules(SHTB) on the endogenous metabolites of colon tissue in mice with slow transit constipation was analyzed by metabolomics methods to explore its mechanism in the treatment of constipation. ICR mice were randomly divided into normal group, model group and SHTB group according to the body weight. The mice were given diphenoxylate to establish the slow transit constipation model. Mouse carbon ink pushing rate, first defecation time and the number of defecation particles in 12 h were observed. The mouse colon tissue was separated and the mucous cells were detected by Periodic acid Schiff and Alcian blue(AB-PAS) staining. Ultra-high-performance liquid chromatography electrospray ionization orbitrap tandem mass spectrometry(UPLC-ESI-Orbitrap-MS/MS) technology was used to characterize the differences in tissue metabolism to screen out the potential different metabolites and possible metabolic pathways in colon tissue. The results indicated that SHTB could significantly shorten the first defecation time and the number of defecations, and increase the number of intestinal peristalsis and mucous cells in the colonic mucosa compared to the model mice. Metabolomics results showed that, compared with the normal group, a total of 17 potential biomarkers, including L-kynurenine, N6,N6,N6-trimethyl-L-lysine, L-formylkynurenine, N6-acetyl-L-lysine, L-phenylalanine, phenylacetaldehyde, xanthoxin, thymidine, glycyl-L-leucine, cystathionine,(R)-1-aminopropan-2-ol, deoxycytidine, gamma-glutamyl-gamma-aminobutyraldehyde, D-galactose, L-arginine, L-proline and pyruvate, were found and identified in colon tissue. Treated with SHTB, these metabolic differences tended to return to normal levels. Therefore, it could be made a conclusion that the therapeutic effect of SHTB on chronic transit constipation may be related to regulating phenylalanine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, arginine and proline metabolism, cysteine and methionine metabolism, tyrosine metabolism, arginine biosynthesis, pyruvate metabolism, glycolysis, pyrimidine metabolism, tricarboxylic acid cycle and galactose metabolism.

Biological effect of astaxanthin on alcohol-induced gut damage in Carassius auratus used as experimental model

Alcohol and its metabolites are responsible for damage both within the gastrointestinal tract and other organs. Alcohol abuse promote intestinal inflammation, that may be the cause of multiple organ dysfunctions and chronic disorders. In this research, the effect of astaxanthin, a powerful antioxidant with several biological effects, on alcohol damage-induced in the intestine of Carassius auratus, was investigated. In the fishes exposed to ethanol, an increase of the intestinal epithelium mucous cells and circulating macrophages, with intestinal mucosa disorganization was observed. In contrast, in the fishes treated with astaxanthin intestinal morphology was restored. By immunohistochemical analysis, using α-Smooth Muscle Actin (α-SMA) and Vasoactive intestinal polypeptide (VIP) antibodies, a reduction of inflammatory states alcohol-induced was evident, with more regular muscularis submucosa and more organized intestinal mucosa without inflammatory cells. The results suggest that astaxanthin treatments can be a good candidate for preventing damage within the gastrointestinal associated with excessive alcohol consumption.

Effect of Phaleria macrocapa on Atrophy and Apoptosis of Intestinal Mucous Cell and Phalerin Concentration at Portal Vein and Systemic Circulation in Adenocarcinoma Mice following Adriamycine and Cyclophosphamide Treatment

Introduction: Chemotherapy has been proven capable of reducing breast cancer cell progression; however the adverse effect also emerging. Thus, diminish those adverse effects with botanical product Phaleria macrocarpa (PM) as adjuvant therapy is necessary. Objective: This study aimed to evaluate the effect of PM treatment in combination with adriamycine and cyclophosphamide (AC) on intestinal apoptosis and their correlation with phalerin concentration in systemic circulation. Methods: In the experimental study, 30 female mice with adenocarcinoma were assign into 5 groups: Neg-G, only given aquadest; Portal vein group (PMV-G) and systemic circulation groups (PMC-G), were administered PM 0.146mg/day; Portal vein group (PMACV-G) and systemic circulation group (PMACC-G), were administered Phaleria macrocarpa 0,146 mg orally, Adriamycine 0,013 mg and Cyclophosphamide 0,0156 mg singgle dose intravenously. Phalerin concentration was measured by HPLC methods at minute 30, 60, 90, 120, 150, and 180 after treatment. At the end of study, intestinal mucous cell apoptosis was identified by TUNEL methods. Results: independent t test analyses showed that index of apoptosis of intestinal mucous cell were significant higher in PMAC-G compared to that of Neg-G and PM-G, p < 0.05. In contrary, phalerin concentration in PMAC-G was significant lower compared to that of PM-G, p < 0.05. The Pearson analysis indicated the inverse correlation (r= -736, p>0.05) between apoptosis index with phalerin concentration. Conclusion: Treatment of PM in combination with AC has been proven able to increase intestinal mucous cell apoptosis and decrease phalerin concentration. However, the inverse correlation didnot exist.

Histopathological study and intestinal mucous cell responses against Aeromonas hydrophila in Nile tilapia administered with Lactobacillus rhamnosus GG.

Aim:This study aimed to examine the intestinal histopathological lesions and mucous cell responses in the entire intestines of Nile tilapia administered with Lactobacillus rhamnosus GG (LGG)-mixed feed, after Aeromonas hydrophila challenge.Materials and Methods:Intestinal samples from fish fed with control normal diet or LGG-mixed feed (1010 colony-forming unit [CFU]/g feed) with or without A. hydrophila in phosphate-buffered saline challenge (7.46 × 108 CFU/mL/fish) were collected and processed for histopathological study. The mucous cell responses were evaluated using histochemistry, using Alcian blue (AB) at pH 2.5, AB at pH 1.0, and periodic acid-Schiff-AB at pH 2.5. The quantification of the intestinal mucous cell size and the staining character of each mucin type from the entire intestine were recorded and counted.Results:Histopathological study showed remarkable lesions only in the proximal intestine in fish infected with A. hydrophila, while LGG-fed fish had less intestinal damage, perhaps resulting from heterophil infiltration. Furthermore, a significant (p<0.01) increase in mixed mucous cell numbers was observed mainly in the proximal intestine of all challenged fish, compared with normal diet-fed fish without challenge, and also in LGG-fed fish with A. hydrophila challenge compared with LGG-fed fish without challenge.Conclusion:Dietary LGG-fed Nile tilapia showed improvements in host innate immunity. In addition, LGG was effective in decreasing intestinal lesions from A. hydrophila-induced intestinal damage. Moreover, increasing numbers of mixed mucous cells in the proximal intestine might be indicative of certain pathological conditions in Nile tilapia after A. hydrophila infection.

Differential mucins secretion by intestinal mucous cells of Chelon ramada in response to an enteric helminth Neoechinorhynchus agilis (Acanthocephala)

Intestinal mucous cells produce and secrete mucins which hydrate, lubricate and protect the intestinal epithelium from mechanical injuries due to the transition of digesta or action of pathogens. Intestinal mucous cells are considered elements of the innate immune system as they secrete lectins, toxins, immunoglobulins, and anti-microbial peptides. Acid mucins can surround and eliminate many pathogenic microorganisms. We performed a quantitative analysis of the density and mucus composition of different intestinal mucous cell types from mullet (Chelon ramada) that were infected solely with Neoechinorhynchus agilis. Most N. agilis were encountered in the middle region of the intestine. Mucous cell types were identified with Alcian Blue (pH2.5) and Periodic acid-Schiff (PAS) histochemistry, and by staining with a panel of seven lectins. Mucus enriched for high viscosity acid mucins was accumulated near points of worm attachment. Parasites were surrounded by an adherent mucus layer or blanket. Ultrastructural examination showed intestinal mucous cells typically possessed an elongated, basally positioned nucleus and numerous electron dense and lucent vesicles in the cytoplasm. The results show both an increase in mucus production and changes in mucin composition in infected mullet in comparison with uninfected conspecifics.

Seasonal histopathological alterations caused by Adenoscolex oreini in Schizothorax niger of Kashmir valley

Fishes infected with Adenoscolex oreini appeared anemic and the abdomen viscera appeared red on opening the abdomen and the abdominal fluid was tinged red. On opening the intestine necrotic debris was present on the surface and numerous parasites were pesent. The histopathological alterations observed in the intestine of fish were (severe degenerative and necrotic changes in the intestinal mucosa as well as edema between submucosa and mucosa). In parasitized Schizothorax niger, hyperplasia of intestinal mucous cells and enhanced mucus secretion were also noticed. Cestode bodies were covered with an adherent mucus blanket. The analysis of the seasonal variation on the histological parameters leads to the conclusion that the distribution or the severity of the lesions observed in the these organs were not related to the seasons. Such information confirms that histopathological alterations are good biomarkers for field assessment, in particular in tropical areas that are naturally subject to a multiplicity of environmental variations. It must be emphasized that histopathology is able to evaluate the early effects and the responses to acute exposure to parasitic infections and chemical stressors.

Protective responses of intestinal mucous cells in a range of fish-helminth systems.

Histopathological, immunofluorescence and ultrastructural studies were conducted on the intestines of four fish species infected with different taxa of enteric helminths. Brown trout (Salmo trutta trutta), eel (Anguilla anguilla) and tench (Tinca tinca) obtained from Lake Piediluco (central Italy) were examined. Brown trout and eel were infected with two species of acanthocephalans, and tench was parasitized with a tapeworm species. In addition to the above site, specimens of chub (Squalius cephalus) and brown trout infected with an acanthocephalan were examined from the River Brenta (north Italy). Moreover, eels were examined from a brackish water, Comacchio lagoons (north Italy), where one digenean species was the predominant enteric worm. All the helminths species induced a similar response, the hyperplasia of the intestinal mucous cells, particularly of those secreting acid mucins. Local endocrine signals seemed to affect the production and secretion of mucus in the parasitized fish, as worms often were surrounded by an adherent mucus layer or blanket. This is the first quantitative report of enteric worm effects on the density of various mucous cell types and on the mucus composition in intestine of infected/uninfected conspecifics. We provide a global comparison between the several fish-helminth systems examined.

Downregulated long non-coding RNA CLMAT3 promotes the proliferation of colorectal cancer cells by targeting regulators of the cell cycle pathway.

Over-expression of long non-coding RNA (lncRNA)-CLMAT3 is significantly associated with colorectal liver metastasis and is an independent predictor of poor survival for colorectal cancer patients. However, as little is known regarding the role of this gene in the proliferation of colorectal cancer in vitro, we investigated the involvement of lncRNA-CLMAT3 in colorectal cancer cell proliferation. In this study, we demonstrate that lncRNA-CLMAT3 expression was significantly increased in colorectal cancer cells compared with a normal intestinal mucous cell line and that inhibition of lncRNA-CLMAT3 suppressed colorectal cancer cell proliferation in vitro. We also found that this reduced colorectal cancer cell proliferation due to lncRNA-CLMAT3 knockdown is associated with G0/G1 cell-cycle arrest induction and apoptosis enhancement. Furthermore, lncRNA-CLMAT3 knockdown enhanced Cdh1 expression and resulted in p27Kip accumulation via increased Skp2 protein ubiquitination. Taken together, our findings suggest that reducing lncRNA-CLMAT3 inhibits colorectal cancer cell proliferation by affecting cell cycle components.

Effects of alternative plant-based feeds on hepatic and gastrointestinal histology and the gastrointestinal microbiome of sablefish (Anoplopoma fimbria)

Sablefish (Anoplopoma fimbria) is a highly desired seafood product, which encourages development of sustainable aquaculture methods for this marine fish. Conventional marine fish-based feeds provide essential nutrients including long chain fatty acids for piscivorous species such as sablefish. Alternative terrestrial ingredients could reduce fishing pressures on pelagic species that are the source of fish meal and fish oil, and improve source sustainability. Using juvenile sablefish, we compared the effects of a standard fish-based diet to two diets that contained primarily terrestrial plant ingredients with flaxseed or corn oil replacing the added fish oil. After an 8-week trial feeding period, there were striking differences attributable to diet. Fish receiving the alternative feeds had lower weight gain and shorter length than fish receiving the fish-based feed, suggesting sablefish obtained lower nutrients from the alternative feeds. Among the histological differences, the intestinal mucosa was significantly less vacuolated and the frequency of intestinal mucous cells was reduced in alternative feed fish. The most dramatic lesions were observed in the liver, where severe bile duct hyperplasia (53%, flaxseed oil diet; 33%, corn oil diet), and hepatocellular lesions (nuclear pleomorphism/megalocytosis, regeneration, hypertrophy, clear cell foci) occurred in only alternative feed fish. The hepatic and biliary lesions indicate the alternative diets may be deficient or possibly harmful to sablefish. The bacterial community structures from corn oil fish showed much less diversity than those for the other diets, and the microbiome structures from the three diets were distinctly different from each other. The intestinal microbiome for the fish-based diet included the largest number of families (68), and these fish also had the largest number of unique bacterial families (11) compared to those for corn oil (two) or flaxseed oil (one) fish. Regardless of diet, the stomach and intestinal microbiomes differed significantly from each other, and the feed microbiome differed from all gastrointestinal communities, suggesting that feed is not a significant source of gut bacterial diversity. Similar to other teleosts, the sablefish gastrointestinal microbiome is dominated by Bacteroidetes, Firmicutes, and Proteobacteria. These results suggest that diet-induced shifts in microbiome can occur relatively quickly in sablefish, but the shifts may not be sufficiently adaptive or cannot overcome nutrient deficiencies. This multidisciplinary study demonstrates the utility of histology and microbiology in characterizing dietary effects for novel aquaculture species. Statement of relevancePhysiological assessments such as gastrointestinal microbiomes and histopathology can provide a near-term evaluation of the nutritional adequacy of alternative feeds, such as plant-based lipid diets for marine carnivorous finfish. This is the first examination of the microbiome of sablefish, a marine species under development for sustainable aquaculture.

Enteric neuromodulators and mucus discharge in a fish infected with the intestinal helminth Pomphorhynchus laevis.

BackgroundIn vertebrates, the presence of enteric worms can induce structural changes to the alimentary canal impacting on the neuroendocrine system, altering the proper functioning of the gastrointestinal tract and affecting the occurrence and relative density of endocrine cells (ECs). This account represents the first immunohistochemistry and ultrastructure-based study which documents the intimate relationship between the intestinal mucous cells and ECs in a fish-helminth system, investigating the potential effects of enteric neuromodulators on gut mucus secretion/discharge.MethodsA modified dual immunohisto- and histochemical staining technique was applied on intestinal sections from both infected and uninfected fish. Sections were incubated in antisera to a range of neuromodulators (i.e. leu-enkephalin, met-enkephalin, galanin and serotonin) and the glycoconjugate histochemistry of the mucous cells was determined using a subsequent alcian blue – periodic acid Schiff staining step. Dual fluorescent staining on sections prepared for confocal laser scanning microscopy and transmission electron microscopy were also used to document the relationship between ECs and mucous cells.ResultsFrom a total of 26 specimens of Squalius cephalus sampled from the River Paglia, 16 (i.e. 62 %) specimens were found to harbour an infection of the acanthocephalan Pomphorhynchus laevis (average intensity of infection 9.2 ± 0.8 parasites host−1, mean ± standard error). When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish. The relationship between met-enkephalin-like or serotonin-like ECs and lectin DBA positive mucous cells was demonstrated through a dual fluorescent staining. The presence of tight connections and desmosomes between mucous and ECs in transmission electron micrographs provides further evidence of this intimate relationship.ConclusionsThe presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera. The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances.

Responses of Squalius cephalus intestinal mucous cells to Pomphorhynchus laevis

Intestinal mucous cell numbers and their glycoconjugate composition were investigated by histochemical methods in uninfected chub, Squalius cephalus, and in conspecifics naturally parasitised with the acanthocephalan Pomphorhynchus laevis. A sub-population of 42 chub from the River Tiber (Perugia, Italy) were sampled and screened for ecto and endoparasites. No parasites were found in gills and in other visceral organs of chub and P. laevis appeared to be the only enteric worm encountered. In all infected chub (twenty-eight out of 42) this acanthocephalan was encountered mainly in the mid-gut. In situ, an excessive yellowish mucus or catarrh was observed around each acanthocephalan. Hyperplasia and hypertrophy of the mucous cells were only evident near the site of P. laevis attachment where the total number of mucous cells and the number of those containing acidic, particularly non-sulphated mucins, or mixed glycoconjugates were significantly higher. In intestinal regions of infected fish far away from the point of parasite attachment, there were no statistical differences in the density of mucous cells in comparison to uninfected fish. Interestingly, in parasitised chub, the length of intestinal folds was significantly larger close to the sites at which P. laevis attach when compared to the length of the intestinal folds located further away from the acanthocephalans and/or in uninfected intestines. The effect of P. laevis on intestinal mucous cells of S. cephalus was compared to other parasite–host systems and the role of enhanced mucus production in parasitized intestines was discussed.

Down-regulation of ncRAN, a long non-coding RNA, contributes to colorectal cancer cell migration and invasion and predicts poor overall survival for colorectal cancer patients

Accumulating evidence has indicated that long non-coding RNAs (lncRNAs) play critical roles in regulating cellular processes, such as cell growth and apoptosis, as well as cancer progression and metastasis. ncRAN (non-coding RNA expressed in aggressive neuroblastoma) was previously shown to be dramatically up-regulated and associated with poor prognosis in human neuroblastoma. This lncRNA also plays an important role in bladder cancer growth and invasion. Colorectal cancer (CRC) progression typically follows a complex cascade from primary malignancy to distant metastasis, but whether the aberrant expression of ncRAN in CRC is associated with malignancy, metastasis or prognosis remains unknown. In this study, we demonstrated that ncRAN expression is significantly down-regulated in tumor tissue and CRC cell lines compared with adjacent normal tissue and a normal intestinal mucous cell line. Reduced expression of ncRAN was detected in poorly differentiated or undifferentiated tumors and in tumors with liver metastases. Kaplan-Meier analysis indicated that patients with lower ncRAN expression have a worse overall survival. Moreover, multivariate analysis revealed that decreased expression of ncRAN is an independent predictor of overall survival. Our experimental data indicated that ncRAN mediates the in vitro migration and invasion of CRC cells. Together, these results suggest that ncRAN might represent a novel prognostic indicator, a biomarker for the early detection of metastasis and a target for gene therapy in CRC.

Changes in the number of intestinal mucous cells of juvenile southern catfish &lt;I&gt;Silurus meridionalis&lt;/I&gt; following feeding, starvation, and refeeding

Changes in the number of intestinal mucous cells of juvenile southern catfish &lt;I&gt;Silurus meridionalis&lt;/I&gt; following feeding, starvation, and refeeding

Low expression of LOC285194 is associated with poor prognosis in colorectal cancer

BackgroundThe long non-coding RNAs (lncRNAs) study has gradually become one of the hot topics in the field of RNA biology. One lncRNA which has attracted attention is LOC285194, a lncRNA demonstrated the potential tumor-suppressor role in osteosarcoma. The aim of this study was to examine the expression of LOC285194 in colorectal cancer (CRC) patients and to investigate the relationship between this lncRNA levels and existing clinicopathologic parameters and patient survival.MethodsThe expression of LOC285194 was detected by quantitative real-time polymerase chain reaction in pairs of tumorous and adjacent normal tissues of 81 colorectal cancer patients with a follow-up of 5 years, as well as in three colorectal cancer cell lines and normal intestinal mucous cell line. Then, we analyzed the potential relationship between this lncRNA levels in tumor tissues and existing clinicopathological features of CRC, and clinical outcome.ResultsThe relative expression levels of LOC285194 was significantly lower in tumor tissues (p < 0.001) and colorectal cancer cell lines compared with adjacent normal tissues and normal intestinal mucous cell line. In addition, low expression of LOC285194 was correlated with larger tumor size (p = 0.015), higher tumor stage (p = 0.034), and more distant metastasis (p = 0.046). Kaplan-Meier analysis indicated that patients with low LOC285194 expression had a poor disease free survival (p = 0.010). Moreover, multivariate analysis showed that decreased expression of LOC285194 was an independent predictor of disease-specific survival.ConclusionOur data indicate that LOC285194 might be a novel prognostic indicator in colorectal cancer and may be a potential target for diagnosis and gene therapy.

The response of intestinal mucous cells to the presence of enteric helminths: their distribution, histochemistry and fine structure

Histochemical and ultrastructural investigations were conducted on the mucous cells of the intestine of brown trout, Salmo trutta L., naturally infected with the cestode Cyathocephalus truncatus (Pallas, 1781) and the acanthocephalan Echinorhynchus truttae Shrank, 1788. A subpopulation of 45 S. trutta were examined of which 15 specimens harboured E. truttae, 15 of which were infected with C. truncatus and 15 fish, the control group, were uninfected. In histological sections, hyperplasia and hypertrophy of the mucous cells were evident at the site of parasite infection. Enhanced mucus secretion was also recorded in infected fish. The number of mucous cells close to the site of parasite attachment within the intestine was significantly higher than the number detected in uninfected individuals and in infected individuals at sites 1 cm or greater from the point of parasite attachment. There were no significant differences between the number of mucous cells found at the latter two sites. Alcian blue and periodic acid-Schiff's staining of representative histological sections revealed a significant increase in the number of mucous cells staining positively for acid glycoconjugates compared to the number of cells found in the intestines of uninfected S. trutta. In transmission electron microscopy sections, each mucous cell typically possessed an elongated, basally positioned nucleus. The cytoplasm was observed to possess numerous electron dense and lucent vesicles, in addition to well-developed rough endoplasmic reticulum, Golgi apparatus and a few round mitochondria.

Intestinal inflammatory response of powan Coregonus lavaretus (Pisces) to the presence of acanthocephalan infections

Immunopathological and ultrastructural studies were carried out on the gut of 30 specimens of powan Coregonus lavaretus (L.) from Lake Piediluco, Italy. The digestive tracts of 10 (33.3%) of the powan were found to harbour an acanthocephalan Dentitruncus truttae (Sinzar 1955). The numerous trunk spines of D. truttae reduced the number of mucosal folds near the parasite site of infection. The acanthocephalan induced hyperplasia and hypertrophy of the intestinal mucous cells and many worms were surrounded with an adherent mucous gel. Near the site of acanthocephalan attachment, the number of mucous cells was significantly higher (P<0.01) in comparison to those found in uninfected intestines. Rodlet cells (RCs) were present in the epithelial layer in both infected and uninfected fish, with no significant difference in the numbers observed (P>0.05). In infected intestine, mast cells were more abundant than in uninfected gut (P<0.01). Migration of the mast cells and their intense degranulation at the site of infection were suggested. Immunohistochemical tests applied to sections of intestinal tissue of both infected and uninfected powan revealed that the parasitized C. lavaretus had a larger number of mast cells positive for met-enkephalin and serotonin antisera.

Fecal Strings Associated with Streptococcus agalactiae Infection in Nile Tilapia, Oreochromis niloticus

This study provides the first description of long fecal strings in Streptococcus agalactiae-infected fish. Nile ti- lapia (Oreochromis niloticus) were administered an intraperitoneal injection with 0.1 mL solution containing a 10-fold di- lution from 10 1 to 10 6 cfu S. agalactiae/fish. While infected fish developed clinical signs commonly associated with S. agalactiae infection, up to 40% of infected fish in each group also produced considerably longer (up to 20 cm in length) fecal waste strings than unchallenged tilapia. Fecal strings from these infected fish were observed trailing from the anus and often became increasingly opaque and white over time. Though S. agalactiae was not isolated from the fecal strings themselves, all S. agalactiae-challenged fish sampled were culture-positive. Histologic examination of the intestines of infected fish exhibited the presence of sloughed intestinal mucous cells and enterocytes in the feces and the absence of normal fecal matter. The presence of long brown and/or white, opaque fecal strings may suggest a clinical sign of bacte- rial disease and the need for further clinical examination. Streptococcus agalactiae affects numerous wild and cul- tured fish species worldwide and causes disease involving septicemia and colonization of numerous organs (1-4). Clini- cal signs of S. agalactiae infection include lethargy or excit- ability, going off feed, 'C'-shaped body posturing, erratic swimming and whirling, opercular clearing, spinal curvature, and death (2, 3, 5). Nile tilapia (Oreochromis niloticus) are susceptible to S. agalactiae infection (3-5). In a variety of previous S. agalactiae challenge studies at the Aquatic Ani- mal Health Research Laboratory, Nile tilapia (n > 500; weight ranging from 3 to 100 g) were injected intraperito- neally with doses ranging from 10 1 to 10 9 colony-forming units (cfu) S. agalactiae/fish and maintained at approxi- mately 30˚C. Though these studies were not intended to ex- clusively examine S. agalactiae-related clinical signs, it was nonetheless noted that numerous challenged fish produced long fecal strings. Since fecal strings have not been previ- ously associated with S. agalactiae infection, a study was performed to examine the presence of fecal strings after ex- perimental S. agalactiae challenge. Nile tilapia (O. niloticus) with a mean weight of 13.9 ± 0.6 g were housed at the USDA/ARS Aquatic Animal Health Laboratory in Chestertown, Maryland, USA. The fish were kept in 57 L glass aquaria supplied with flow-through dechlorinated tap water, maintained at a mean temperature of 30.5 ± 0.6oC, mean dissolved oxygen of 5.3 ± 0.9 mg/L, and mean ammonia concentration of 0.2 ± 0.8 mg/L. The fish were also fed daily to satiation with Aquamax feed (Bren- twood, Missouri, USA) and maintained on a 12 h : 12 h light :

Larval organogenesis of Pagrus pagrus L., 1758 with special attention to the digestive system development

Organogenesis of the red porgy (Pagrus pagrus L., 1758) was examined from hatching until 63 days post-hatching (dph) using histological and histochemical techniques. At hatching, the heart appeared as a tubular structure which progressively developed into four differentiated regions at 2 dph: bulbus arteriosus, atrium, ventricle and sinus venosus. First ventricle and atrium trabeculae were appreciated at 6 and 26 dph, respectively. Primordial gill arches were evident at 2 dph. Primordial filaments and first lamellae were observed at 6 and 15 dph, respectively. At mouth opening (3dph), larvae exhausted their yolk-sac reserves. The pancreatic zymogen granules appeared at 6 dph. Glycogen granules, proteins and neutral lipids (vacuoles in paraffin sections) were detected in the cytoplasm of the hepatocytes from 4-6 dph. Hepatic sinusoids could be observed from 9 dph. Pharyngeal and buccal teeth were observed at 9 and 15 dph, respectively. Oesophageal goblet cells appeared around 6 dph, containing neutral and acid mucosubstances. An incipient stomach could be distinguished at 2 dph. The first signs of gastric gland development were detected at 26 dph, increasing in number and size by 35-40 dph. Gastric glands were concentrated in the cardiac stomach region and presented a high content of protein rich in tyrosine, arginine and tryptophan. The intestinal mucous cells appeared at 15 dph and contained neutral and acid glycoconjugates, the carboxylated mucins being more abundant than the sulphated ones. Acidophilic supranuclear inclusions in the intestinal cells of the posterior intestine, related to pynocitosis of proteins, were observed at 4-6 dph.