Distal Intestine Research Articles

Dorothy Hodgkin lecture 2023: The enteroendocrine system-Sensors in your guts.

Glucagon-like peptide-1 (GLP-1)-based medication is now widely employed in the treatment of type 2 diabetes and obesity. Like other gut hormones, GLP-1 is released from eneteroendocrine cells after a meal and in this review, based on the Dorothy Hodgkin lecture delivered during the annual meeting of Diabetes UK in 2023, I argue that there is sufficient spare capacity of GLP-1 and other gut hormone expressing cells that could be recruited therapeutically. Years of research has revealed several receptors expressed in enteroendocrine cells that could be targeted to stimulate hormone release: although from this research it seems unlikely to find agents that selectively boost GLP-1, release of a mixture of hormones might be the more desirable outcome anyway, given the recent promising results of new peptides combining GLP1-receptor with other gut hormone receptor activation. Alternatively, the fact that GLP-1 and peptideYY (PYY) expressing cells are found in greater density in the ileum might be exploited by increasing the delivery of chyme to the distal small intestine.

Wide field-of-view fluorescence imaging for organ-level lineage tracing of rare intestinal stem cell populations.

Lineage tracing using fluorescent reporters is a common tool for monitoring the expression of genes and transcription factors in stem cell populations and their progeny. The zinc-binding protein 89 (ZBP-89/Zfp148 mouse gene) is a transcription factor that plays a role in gastrointestinal (GI) stem cell maintenance and cellular differentiation and has been linked to the progression of colon cancer. While lineage tracing is a useful tool, it is commonly performed with high-magnification microscopy on a small field of view within tissue sections, thereby limiting the ability to resolve reporter expression at the organ level. Furthermore, this technique requires extensive tissue processing, which is time consuming and requires euthanizing the animal. Further knowledge could be elucidated by measuring the expression of fluorescent reporters across entire organs with minimal tissue processing. We present the application of wide-field fluorescence imaging for whole-organ lineage tracing of an inducible Zfp148-tdTomato-expressing transgenic mouse line to assess the expression of ZBP-89/Zfp148 in the GI tract. We measured tdTomato fluorescence in ex vivo organs at time points between 24h and 6 months post-induction. Fluctuations in tdTomato expression were validated by fluorescence microscopy of tissue sections. Quantification of the wide field-of-view images showed a statistically significant increase in fluorescent signal across the GI tract between transgenic mice and littermate controls. The results also showed a gradient of decreasing reporter expression from proximal to distal intestine, suggesting a higher abundance of ZBP-89 expressing stem cells, or higher expression of ZBP-89 within the stem cells, in the proximal intestine. We demonstrate that wide-field fluorescence imaging is a valuable tool for monitoring whole-organ expression of fluorescent reporters. This technique could potentially be applied in vivo for longitudinal assessment of a single animal, further enhancing our ability to resolve rare stem cell lineages spatially and temporally.

Alpha-ketoglutaric acid mitigates the detrimental effects of soy antigenic protein on the intestinal health and growth performance of Mirror carp Cyprinus carpio.

The study investigated the alleviated effects of Alpha-ketoglutaric acid (AKG) on the intestinal health of mirror carp (Cyprinus carpio Songpu) caused by soy antigenic protein. The diets were formulated from fishmeal (CON), 50% soybean meal (SBM), the mixture of glycinin and β-conglycinin (11 + 7S) and adding 1% AKG in the 11 + 7S (AKG). Carp (~ 4g) in triplicate (30 fish per tank) was fed to apparent satiation thrice a day for six weeks. Compared with CON, SBM treatment resulted in significantly poor growth performance (P < 0.05), whereas 11 + 7S and AKG treatments were not significantly different from CON (P > 0.05). Gene expression of tumor necrosis factor (TNF-α) and interleukin-1 β (IL-1β) in proximal intestines (PI) and distal intestines (DI) were increased (P < 0.05), and transforming growth factor (TGF-β) in PI and middle intestines (MI) was decreased (P < 0.05) in both SBM and 11 + 7S. The caspase-3 in DI increased in SBM (P < 0.05) and the caspase-3 and caspase-9 in DI increased in 11 + 7S (P < 0.05); conversely, TGF-β in PI and MI was increased, TNF-α and IL-1β in the MI, caspase-3, and caspase-9 in DI was decreased in AKG (P < 0.05). The TOR (target of rapamycin) in PI and MI, ACC in PI, MI and DI was decreased in SBM (P < 0.05), the AMPK in the PI and DI, TOR in PI, MI and DI, ACC in PI and DI, 4E-BP in DI was reduced in 11 + 7S (P < 0.05). AMPK in the PI and DI, ACC in the PI and MI, TOR in PI, MI, and DI, 4E-BP in PI and DI was recovered by AKG supplementation (P < 0.05). Lipids and lipid-like metabolism, organic acids and derivatives metabolism increased in AKG dietary treatment. In conclusion, AKG reduces the expression of intestinal inflammation and apoptosis pathway and changes glycerophospholipid metabolism and sphingolipid metabolism in the intestine of fish.

Partially defatted rather than native poppy seeds beneficially alter lipid metabolism in rats fed a high-fat diet

Partially defatted poppy seeds, a by-product of poppy oil cold pressing, could be an interesting dietary supplement for obesity management. The aim of this study was to compare the effects of dietary supplementation with a small amount of native or partially defatted poppy seeds on gastrointestinal function and lipid metabolism in rats fed a high-fat diet. The defatted poppy seeds had, among others, lower fat content and higher fibre and protein content than native poppy seeds. The rats fed with a high-fat diet were characterised by severe metabolic disorders, especially in the liver, and poppy seeds were unable to prevent them. However, depending on the seed form, dietary supplementation with poppy seeds differentially affected the microbial and endogenous lipid metabolism in rats. In the distal intestine, both dietary seed forms stimulated microbial acetate production, and the supplementation with partially defatted poppy seeds additionally inhibited isobutyrate and isovalerate formation, which indicates a reduction in putrefaction. Both dietary seed forms increased cholesterol accumulation in the liver. Only dietary supplementation with partially defatted poppy seeds attenuated visceral fat and hepatic triglyceride accumulations and lowered blood triglyceride concentrations, and at the transcriptional level, the inhibition of SREBP-1c, which upregulates genes responsible for de novo lipogenesis, was additionally observed in this organ. In conclusion, a low and regular consumption of partially defatted poppy seeds may be beneficial in managing obesity-related disorders.

The effects of sodium butyrate (NaB) combination with soy saponin dietary supplementation on the growth parameters, intestinal performance and immune-related genes expression of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

Soy saponins are generally known to have negative effects on growth and the intestines of aquatic animals, and appropriate levels of sodium butyrate (NaB) may provide some mitigating effects. We investigated the effects of low and high levels of soy saponin and the protective effects of NaB (based on high level of soy saponin) on growth, serum cytokines, distal intestinal histopathology, and inflammation in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). The experiment included four groups: fishmeal group (FM, 0.00% saponin and 0.00% NaB), low saponin group (SL, 0.30% saponin and 0.00% NaB), high saponin group (SH, 1.50% saponin and 0.00% NaB) and high saponin with NaB group (SH–NaB, 1.50% saponin and 0.13% NaB). The results showed compared to FM, the final body weight (FBW) and weight gain (WG) were significantly higher and lower in SL and SH, respectively (P < 0.05). Compared to SH, the FBW and WG were significant higher in SH-NaB (P < 0.05). In the serum, compared to FM, the interferon γ (IFN-γ) and interleukin-1β (IL-1β) levels in SH were significantly increased (P < 0.05). Compared to SH, the IFN-γ level was significantly decreased in SH-NaB (P < 0.05). In the distal intestine, based on Alcian Blue-Periodic Acid-Schiff (AB-PAS) observation, the goblet cell/μm was significantly increased and decreased in the SL and SH, respectively, compared to FM. The intestinal diameter/plica height ratio in the SH was significantly higher than those in the FM, SL and SH-NaB (P < 0.05). The NO and ONOO− levels in the SH were significantly higher than that in FM and SL (P < 0.05). At the transcriptional level in the distal intestine, compared to FM, the mRNA levels of tumor necrosis factor (tnfα), il1β, interleukin-8 (il8) and ifnγ were significantly up-regulated in the SH (P < 0.05). Compared to the SH, tnfα, il8 and ifnγ were significantly down-regulated in the SH-NaB (P < 0.05). Compared to the FM, the mRNA levels of claudin3, claudin15, zo2 and zo3 were significantly up-regulated in the SL (P < 0.05). The mRNA levels of occludin, claudin3, claudin12, claudin15, zo1, zo2 and zo3 were significantly down-regulated in the SH compared to the FM (P < 0.05). Additionally, compared to the SH, the mRNA levels of occludin, claudin3, claudin12, claudin15, zo1, zo2 and zo3 were significantly up-regulated in the SH-NaB (P < 0.05). After the 7-day Vibrio parahaemolyticus challenge test, the survival was significantly higher and lower in the SL and SH, respectively, compared to FM (P < 0.05). Overall, low and high levels of soy saponins had positive and negative effects on growth, disease resistance, serum cytokines, and distal intestinal development and anti-inflammation, respectively, in hybrid grouper. NaB effectively increased disease resistance and improved distal intestinal inflammation in hybrid grouper, but the effects of NaB were mainly observed in improving distal intestinal tight junctions.

Evaluating a microalga (Schizochytrium sp.) as an alternative to fish oil in fish-free feeds for sablefish (Anoplopoma fimbria)

Alternative feeds are critical for the sustainable expansion of the marine finfish aquaculture industry. The industry uses wild-caught forage fish as a primary ingredient in farmed fish feeds. Alternative ingredients are needed to safeguard fisheries' sustainability and future aquaculture development. While there have been successes in alternative feeds, it is necessary to improve the existing options and identify alternative ingredients with higher concentrations of omega-3 polyunsaturated fatty acids (PUFAs). This study was designed to test a microalga, Schizochytrium sp., as a feed ingredient for sablefish (Anoplopoma fimbria) using six test diets. There were two fish-ingredient control diets: +FM+FO, which contained both fishmeal and fish oil, and −FM+FO, which contained fish oil, but no fishmeal. The remaining four diets contained alternative lipids and were completely fish-free. FF Flax contained flax oil as the only lipid source replacing fish oil. FF LowSc, FF ModSc, and FF HighSc contained a low, moderate, and high level of Schizochytrium sp. to replace fish oil, with flax oil content decreasing as the microalga increased. After a 20-week trial, sablefish growth differed across the feed treatments, with fish fed the high microalga-inclusion diet (FF HighSc) performing similarly to fish fed the fish-ingredient controls. Fulton's K condition factor, dry feed intake (DFI), and lipid productive value (LPV) were also influenced by treatment. For the four fish-free diets, specific growth rate increased with increasing inclusion of Schizochytrium sp. in the feed. Fillet fatty acid profiles were similarly influenced by diet treatment, generally reflecting the fatty acid profiles of the feed. Total fillet PUFAs were higher in sablefish from the fish-free treatments than the control treatments, with DHA increasing with increasing inclusion of dietary Schizochytrium. In contrast, EPA was higher in fillets from both fish-ingredient control treatments compared to fillets from the fish-free treatments, yet EPA remained higher than expected in sablefish fed the fish-free diets. Histologic evaluation of sablefish distal intestine and liver demonstrated that the microalga-inclusion diets were well tolerated and did not cause histomorphological changes in the tissues. These results suggest Schizochytrium sp. can increase PUFA concentrations in fish fillets without compromising fish health and growth, making it a viable ingredient for alternative sablefish feeds.

Gastrointestinal metabolism characteristics and mechanism of a polysaccharide from Grifola frondosa

Grifola frondosa polysaccharide (GFP) is mainly composed of α-1,4 glycosidic bonds and possesses multiple pharmacological activities. However, the absence of pharmacokinetic studies has limited its further development and utilization. Herein, GFP was labeled with 5-DTAF (FGFP) and cyanine 5.5 amine (GFP-Cy5.5) to investigate its gastrointestinal metabolism characteristics and mechanism. Significant distributions of the polysaccharide in the liver and kidneys were observed by near infrared imaging. To investigate the specific distribution form of the polysaccharide, in vitro digestion models were constructed and revealed that FGFP was degraded in saliva and rat small intestine extract. The metabolites were detected in the stomach and small intestine, followed by further degradation in the distal intestine in the in vivo experiment. Subsequent investigations showed that α-amylase was involved in the gastrointestinal degradation of GFP, and its metabolite finally entered the kidneys, where it was excreted directly with urine.

Gut microbiota of the small intestine as an antimicrobial barrier against foodborne pathogens: Impact of diet on the survival of S. Typhimurium and L. monocytogenes during in vitro digestion

The human gastrointestinal tract employs an assortment of chemical, enzymatic and immune barriers to impede pathogen colonization. An essential component of these barriers is the gut microbiota, which infers protection against ingested pathogens through its colonization resistance mechanisms. Specifically, the gut microbiota of the distal small intestine (ileum) renders a crucial line of defense, given that this location is regarded as an important interaction site. This study aimed to evaluate the impact of the ileal microbiota on the survival of the foodborne pathogens Salmonella enterica serotype Typhimurium and Listeria monocytogenes, utilizing an in vitro digestion model system. Moreover, the effect of diet on the gut microbiota colonization resistance mechanisms was assessed, by comparing a healthy (high fiber/low sugar) and a western diet (low fiber/high sugar). For S. Typhimurium, the results revealed that the digestion of a healthy diet led to a similar inactivation compared to the western diet, with the values of total log reduction being 0.83 and 0.82 log(CFU), respectively; yet the lack of readily accessible nutrients in the healthy diet combined with the acidic shock during gastric digestion caused the induction of stress tolerance to the pathogen. This resulted in increased pathogen survival in the presence of gut microbiota, with S. Typhimurium proliferating during the ileal phase with a maximum specific growth rate of 0.16 1/h. On the contrary, for L. monocytogenes, the healthy diet was associated with a greater inactivation than the western diet (total log reduction values: 3.08 and 1.30 log(CFU), respectively), which appeared strongly influenced by the encounter of the pathogen with the gut microbiota. Regarding the latter, the species Escherichia coli and Bacteroides thetaiotaomicron appeared to be the most prevalent in most cases. Finally, it was also demonstrated that the ileal microbiota colonization resistance mechanisms largely relied on competitive responses. The obtained knowledge of this research can contribute to the development and/or complementation of defensive strategies against pathogen infection, while also underlining the value of in vitro approaches.

A new obesity treatment method that does not require restriction in food intake and organ resection

Background/Aim: There are numerous treatment methods available for obesity, with bariatric surgery being the most effective. However, these techniques come with the risk of serious complications. This study presents a novel obesity treatment device that can shorten the length of the small intestine without the need for surgical intervention. Methods: Our new device comprises three main components: a 25 cm long rope, with one end attached to a 1 cm diameter plastic ring and the other end attached to a 2 mm diameter, 5 g sphere. Twenty-one male Wistar albino rats (6 months old, mean weight 400 g, outbred) were divided into three equal groups. Laparotomy and gastrotomy were performed on the subjects in Group 1, and all three parts of the device were placed into the gastrointestinal tract. In Group 2, only the plastic ring was placed in the stomach, and in Group 3, only a gastrotomy was performed. All subjects were followed for 3 months, during which their body weight, serum ghrelin, leptin, and nesfatin-1 levels were recorded, and the amount of food they consumed was measured. After sacrificing the animals, the stomach, proximal, and distal intestines were resected for histopathological evaluation. Results: The subjects in Group 1 experienced weight loss, whereas those in Groups 2 and 3 showed statistically significant weight gain (P&lt;0.001 and P=0.022, respectively). Serum ghrelin levels were significantly increased in Groups 1 and 3 (P=0.015 and 0.031, respectively), while serum leptin levels were significantly decreased in Group 1 (P=0.015). Plasma nesfatin-1 levels were significantly higher in Group 1 compared to the other groups (P=0.014). There was no statistically significant difference in feed consumption between the groups. Histopathological examination revealed significantly higher fibrosis and inflammation scores in the proximal small intestine of Group 1 compared to the other groups (P=0.008 and P=0.005, respectively). Conclusions: This new device facilitates rapid and effective weight loss without the need for restricting oral food intake or organ resection. Changes in serum ghrelin, leptin, and nesfatin-1 levels did not affect these results. We hypothesize that the effective weight loss is linked to the shortening of the small intestine length. Our future plans involve modifying the device for endoscopic application in humans.

Evaluation of rainbow trout (Oncorhynchus mykiss) organotypic intestinal platforms: cellular responses after long-term exposure to in vitro digested feed

Reliable and predictive in vitro models would support the search for new raw materials that can improve current fish diets. We recently developed some rainbow trout (RT) intestinal cell-based organotypic platforms demonstrating that the platform type modulates the degree of cell differentiation achieved in vitro and here we studied whether such differentiation correlates with their response to a prolonged exposure to a diet rich in fish meal. We compared three options, seeding the RTpiMI and RTdiMI cell lines derived respectively from the proximal or the distal intestine on (1) the polyethylene terephthalate (PET) culture inserts ThinCert™ (TC); (2) the TC coated with RT fibroblasts embedded within Matrigel® (MMfb); and (3) the highly porous polystyrene scaffold Alvetex™ also populated with fibroblasts (AV). Platforms have been exposed for 21 days to increasing concentrations of feed pellets digested in vitro by gastric and intestinal RT enzymes (IVD). Cells exposed to culture medium without IVD in each platform were used as controls. TEER values became significantly higher than their respective controls in most culture conditions. At the end of culture, epithelial cells formed multilayers irrespective of cell line or platforms if exposed to IVD, but not in the controls. This proliferative activity followed a dose-dependent pattern in the AV, did not vary in MMfb, and was highly variable in the TC. Moreover, IVD induced the formation of a few goblet-like cells characterized by rounded vacuoles. In parallel, alanine aminopeptidase activity completely disappeared in the MMfb, significantly decreased in the AV, but did not change in TC. These changes suggest a de-differentiation of the enterocytes and their partial differentiation towards the secretory lineages. Overall, the three platforms reacted differently to a pronged exposure to IVD: TC quenched most of the cell responses, MMfb generated overly sensitive reactions, while the AV react mostly in a dose-dependent manner possibly generating more physiological results.

Differences in metabolic improvement after metabolic surgery are linked to the gut microbiota in non-obese diabetic rats.

Different metabolic/bariatric surgery approaches vary in their effect on weight loss and glucose levels, although the underlying mechanism is unclear. Studies have demonstrated that the gut microbiota might be an important mechanism of improved metabolism after metabolic/bariatric surgery. To investigate the relationship between the improvement in metabolic disturbances and the changes in gut microbiota after gastric or intestinal bypass. We performed sleeve gastrectomy (SG), distal small intestine bypass (DSIB) or sham surgery in nonobese rats with diabetes induced by 60 mg/kg streptozotocin (STZ-DM). The group comparisons revealed that both SG and DSIB induced a reduction in body weight and significant improvements in glucose and lipid metabolism in the STZ-DM rats. Furthermore, DSIB exhibited a stronger glucose-lowering and lipid-reducing effect on STZ-DM rats than SG. 16S ribosomal RNA gene sequencing revealed the gut abundance of some Lactobacillus spp. increased in both the SG and DSIB groups after surgery. However, the DSIB group exhibited a more pronounced increase in the gut abundance of Lactobacillus spp. compared to the SG group, with more Lactobacillus spp. types increased in the gut. The gut abundance of Lactobacillus was significantly correlated with the improvement in glycolipid metabolism and the change in serum fibroblast growth factor 21 levels.

Dietary high β-conglycinin reduces the growth through enhancing hepatic lipid peroxidation and impairing intestinal barrier function of orange-spotted grouper (Epinephelus coioides)

β-conglycinin is one of the major soy antigen proteins in soybean meal (SBM) and exhibits growth inhibition and intestinal health damage in grouper, but the underlying mechanisms are still poorly understood. In this study, orange-spotted grouper (Epinephelus coioides) was used to investigate whether the poor growth performance induced by dietary β-conglycinin levels is associated with intestinal structural integrity disruption, the intestinal apoptosis and intestinal microbiota. The basal diet (FM diet) was formulated to contained 48% protein and 12% fat without SBM supplementation. Fish meal protein in the FM diet was replaced by SBM to prepare a high SBM diet (SBM diet). β-conglycinin at 3% and 7% were added into FM diets to prepare two diets (B-3 and B-7). Triplicate groups of fish (20 fish/tank) were fed one of the experimental diets twice daily in a feeding period of 8 weeks. Compared with FM diet, fish fed diets SBM and B-7 had decreased the growth rate, hepatosomatic index, whole-body lipid and ash contents, and increased whole-body moisture content. However, the maximum growth was observed for diet B-3 and was not different from that of FM diet. The liver total antioxidant capacity and glutathione peroxidase activity, the muscle layer thickness of middle and distal intestine, and the mucosal fold length of distal intestine were lower, while liver malondialdehyde content, intestinal diamine oxidase activity, d-lactic acid and endotoxin contents, and the number of intestinal apoptosis were higher in SBM and B-7 groups than that in FM and/or B-3 groups. SBM and B-7 diets down-regulated the intestinal expression of tight junction genes (occludin, claudin-3 and ZO-1), apoptosis genes (bcl-2 and bcl-xL) and anti-inflammatory factor genes (IκBα, TGF-β1 and IL-10), but up-regulated the intestinal expression of apoptosis genes (caspase-3, caspase-8 and caspase-9) and pro-inflammatory factor genes (NF-κB1, RelA, TAK1, IKK, MyD88, TNF-α, IL-1β, and IL-8) vs FM and/or B-3 diets. The richness and diversity indexes of OTUs, Chao1, ACE, Shannon and Simpson were not affected by dietary treatments. The relative abundances of intestinal bacteria (phylum Proteobacteria and genus Vibrio) were generally higher, and relative abundance of phylum Tenericutes was lower in SBM and/or B-7 groups than that in B-3 group. The above results indicate that high dietary β-conglycinin level, rather than intermediate level could decrease liver antioxidant capacity, reshape the intestinal microbiota, and impair the intestinal normal morphology through disrupting the intestinal tight junction structure, increasing intestinal mucosal permeability, and promoting intestinal apoptosis, which in turn triggers intestinal inflammatory responses and the occurrence of enteritis, and ultimately leads to poor growth performance in fish.

Involvement of iNOS-induced reactive enteric glia cells in gastrointestinal motility disorders of postoperative Ileus mice

Postoperative ileus (POI) is the cessation or reduction of gastrointestinal (GI) motility after surgery. Reactive enteric glial cells (EGCs) are critical for maintaining bowel function. However, the triggering mechanisms and downstream effects of reactive EGCs in POI were poorly understood. The goal of this current study was to investigate whether the inducible nitric oxide synthase (iNOS)-driven reactive EGCs participated in GI motility disorders and mechanisms underlying altered GI motility in POI. Intestinal manipulation (IM)-induced POI mice and iNOS−/− mice were used in the study. Longitudinal muscle and myenteric plexuses (LMMPs) from the distal small intestine were stained by immunofluorescence. Our results found that the GI motility disorders occurred in the IM-induced POI mice, and reactive EGCs were observed in LMMPs. Glial metabolic inhibitor gliotoxin fluorocitrate (FC) treatment or iNOS gene knockout attenuated GI motility dysfunction. In addition, we also found that FC treatment or iNOS gene knockout significantly inhibited the fluorescence intensity macrophage colony-stimulating factor (M-CSF), which reduced M2 phenotype macrophages activation in LMMPs of IM-induced POI mice. Our findings demonstrated that iNOS-driven reactive EGCs played a key role and were tightly linked to the MMs homeostasis in the POI mice. EGCs are emerging as a new frontier in neurogastroenterology and a potential therapeutic target.

Gitar balıklarında (Rhinobatos rhinobatos) Vibrio hepatarius kaynaklı subakut enteritik septisemi

Common guitarfish (Rhinobatos rhinobatos) are an endangered species and are placed on the red list of “Critically Endangered, CR” by the International Union for Conservation of Nature. Guitarfish are kept in captivity and are protected in public aquaria globally, but there is limited information about the diseases for this species. In this research, mortalities (14%) observed in common guitarfish in a public aquarium are reported. Severe hemorrhagic lesions on the ventral body side and reduced feed intake were observed in the affected animals. Two guitarfish were referred for necropsy, microbiological and histopathological examination. Macroscopic findings included severe ecchymotic hemorrhages in the ventral body, bloating of the gastrointestinal tract due to invasive mass, and hyperemia of the colon vessels and obstruction of the colon lumen. Histopathological examination revealed degenerations and necrosis in the liver, desquamation of intestinal villi, severe mononuclear cell infiltration and fibrosis in distal intestine, severe bacterial aggregates in different organs, pancreatitis, vasculitis, and filamentous bacteria-like structures. Vibrio hepatarius was isolated and identified with multilocus sequence analysis (MLSA); multilocus sequence typing (MLST) revealed that the agent belonged to a novel sequence type, 247. After the first description of V. hepatarius in wild healthy adults of Whiteleg shrimp (Litopenaeus vannamei) from Ecuador, this is the first report of deaths due to V. hepatarius observed in common guitarfish kept in captivity in a public aquarium.

Dietary glutamine enhances growth performance and gut integrity of Totoaba macdonaldi juveniles fed low fishmeal diets but has limited synergetic effects in combination with a prebiotic

Fishmeal (FM) replacement using cost-effective blends of complementary ingredients is commonly used in carnivorous marine fish diets for economic and sustainable purposes. The use of functional compounds such as prebiotics or functional ingredients is a nutritional strategy in low FM diets to maximize growth and feed utilization, as well as reducing enteropathies caused by plant proteins, in particular soybean meal (SBM) that can induce enteritis in Totoaba macdonaldi juveniles. Therefore, this study was conducted to evaluate the effects of glutamine (Gln) and agavin (AGA) as a novel prebiotic or a combination of both on growth parameters, digestive capacity, whole-body proximate composition, gut health, and sustainable and economic indexes in totoaba juvenile fed low FM (17%) diet for 56 days. Juvenile totoaba with an initial weight of 168 ± 4 g were fed one of four isoproteic and isolipidic diets formulated with poultry by-product meal and FM in a 2:1 ratio and 24% of SBM. For the control basal diet (SBM), no Gln or AGA was added. The other three experimental diets consisted of the basal diet with either 1.5% glutamine (GLN), 1% prebiotic agavin (AGA), or 1.5% glutamine and 1% agavin (Gln + AGA) supplementation. Fish fed the Gln diet significantly improved growth, feed utilization and increased trypsin, total alkaline proteases, and L-aminopeptidase activities. Additionally, an enhanced brush border height (BBH) in the distal intestine was observed in the Gln group, suggesting improved intestinal health compared to the rest of the treatments. However, no significant synergistic effect was observed in fed fish the Gln + AGA diet. Interestingly, no signs of enteritis among the fish fed the four experimental diets was observed. These results suggest that fish with an initial size of 168 g are less susceptible to the adverse effects of SBM compared to previous studies. The inclusion of 1.5% dietary glutamine is recommended in totoaba diets with low FM containing 24% of SBM. Since the fish fed the diet supplemented with glutamine + agavin resulted in intermediate values for the parameters evaluated, it is recommended to evaluate different levels of agavin in combination with glutamine or perform longer bioassays using immunological or environmental challenges to aid in elucidating potential benefits of these functional compounds and their synergistic effects.

Effect of Dietary Incorporation of Yellow Mealworm as a Partial Fishmeal Replacer on Growth, Metabolism, and Intestinal Histomorphology in Juvenile Meagre (Argyrosomus regius).

Efforts have been made to find alternatives to fish meal (FM), as the sustainability of aquaculture depends on it. Insect meal (IM) is a potential candidate to partially replace FM, being more sustainable and economically viable. In this experimental trial, three diets were tested with different yellow mealworm incorporation: a control diet with no IM, a diet with an inclusion of 10% IM (Ins10), and a diet with an incorporation of 20% IM (Ins20). The diets were tested on 10.5 g meagre for 47 days. The results showed that an IM inclusion higher than 10% affected both growth (2.6 vs. 2.2) and FCR (1.5 vs. 1.9) of meagre juveniles. However, this reduction in growth did not result from lower protein retention or changes in muscle fibre area or density. Little differences were observed in the activity of pancreatic and intestinal enzymes except for aminopeptidase total activity which was higher in the control and Ins10 compared to Ins20 (3847 vs. 3540 mU/mg protein), suggesting no limitations in protein synthesis. Also, the alkaline phosphatase intestinal maturation index was higher in the control group compared to the IM groups (437 vs. 296). On the contrary, several differences were also found in the proteolytic activity in the hepatic and muscle tissues of meagre juveniles fed the Ins10 diet. The inclusion of IM had no impact on intestine histomorphology but changes were detected in the enterocytes of fish from control and Ins10 which showed hypervacuolization and nucleus misplacement compared to the Ins20 treatment. Nevertheless, a higher percentage of Vibrionaceae was recorded for meagre fed on the Ins20 diet. Since no signs of inflammation were observed in the distal intestine, this suggests IM incorporation could have had an important impact on intestinal health due to its antimicrobial properties. This is supported by an increase in the haematocrit in the treatments where IM was added (20 to 25%). In conclusion, incorporations of IM at percentages up to 10% do not seem to have a negative impact on meagre performance at this age but can enhance the fish immune system and protection against intestinal inflammation.

Influence of fish protein hydrolysate on intestinal health and microbial communities in turbot Scophthalmus maximus

This study aimed to investigate the effect of fish protein hydrolysate (FPH) on intestinal microbiota and health of turbot Scophthalmus maximus (average initial body weight 25.5 g). Two control diets were formulated to contain 360 g kg −1 (high fish meal, HFM) and 240 g kg−1 (low fish meal, LFM) of fish meal. Two experimental diets were derived from the HFM diet by replacing fish meal with FPH at levels of 100 g kg−1 (appropriate level, FPH10) or 300 g kg−1 (excessive level, FPH30). The supplementation of FPH at an appropriate level showed a positive effect on growth performance. According to chyme amino acid concentrations, moderate FPH in diets can alleviate the rate of amino acid absorption in middle intestine than excessive one (FPH30), and more thoroughly absorbed in distal intestine than fish meal (HFM) and plant protein (LFM). Histology of distal intestine showed that an appropriate level of FPH in diets could serve to alleviate the symptoms of structural damage (villi height and wall thickness) to the intestine caused by plant protein. The expressions of tight junction proteins and mucin 2 in the FPH10 and FPH30 diets was up-regulated in middle intestine compared to the LFM diet. FPH at a moderate level reduced the levels of pro-inflammatory factors (IL-1β and TNF-α) but didn't increased anti-inflammatory factors (IL-10 and TGF-β) in middle intestine compared with the LFM diet. To turbot, mucosa and chyme-associated microbiota from middle and distal intestine mainly belonged to Proteobacteria and Firmicutes. The bacterial richness, diversity and/or evenness decreased in middle intestine chyme, distal intestine mucosa and/or chyme when fish were fed diets containing FPH. Fish fed an appropriate level of FPH showed an increase of genera Bacillus in middle intestine mucosa and a decrease of genera Vibrio in distal intestine mucosa, while there was an inverse trend in fish fed an excessive level of FPH. Overall, FPH at an appropriate level showed a positive effect on intestinal health by improving middle or distal intestinal structure integrity and barrier function, as well as regulating immune-related inflammatory factors. Meanwhile, moderate FPH in diets may modulate the abundance of potentially probiotic (Bacillus) and pathogenic (Vibrio) in the intestine.

Colorectal cancer: epidemiology, carcinogenesis, molecular subtypes and cellular mechanisms of therapy resistance (analytical review)

This article analyzes the statistical data on colorectal cancer in Russia and in the world, including incidence, mortality and survival. The main pathways of colorectal cancer carcinogenesis, molecular subtypes and their influence on the difference in lesions of the proximal and distal large intestine are presented. The paper provides an overview of the leading chemotherapy agents and targeted therapy in colorectal cancer, as well as the main reasons for the development of therapeutic resistance, including changes in the cellular microenvironment of the tumor.

833-P: Duodenal Targeting by Oral Pharmacologic Duodenal Exclusion Therapy for Treatment of Type 2 Diabetes (T2D)

GLY-200 is an oral, non-absorbed polymeric drug designed to non-invasively and reversibly enhance the mucus lining of the proximal small intestine to mimic the effects of metabolic surgery and duodenal exclusion devices. In healthy volunteers and rat models of T2D (GK, ZDF, and DIO), GLY-200 produced reductions in postprandial glucose and bodyweight compared to control. This study aimed to visualize the retained duodenal barrier in rats using appropriate imaging modalities. Methods: Imaging of GLY-200 after gavage administration to fasted Sprague-Dawley rats was performed using Computed Tomography (CT) and an In Vivo Imaging System (IVIS). For CT imaging, GLY-200 was covalently conjugated with diatrizoate; images were obtained after transient isoflurane administration 1, 2, and 4 hours after gavage. For IVIS imaging, GLY-200 was reacted with FITC to produce a fluorescein-GLY-200 conjugate. Rats were euthanized 0.5, 1, 2, 4, and 8 hours after dosing and the GI tracts were immediately removed for imaging. Results: In CT imaging, GLY-200-diatrizoate was retained in the proximal small intestine 1 and 2 hours after administration, with an intense signal only in the duodenum. In comparison, a diatrizoate control was broadly distributed over the small intestine distal to the duodenum by 1 hour. In IVIS imaging, GLY-200-FITC showed intense fluorescence in the proximal small intestine that was predominantly associated with the gut wall and persisted for &amp;gt;4 hours after administration. In comparison, a FITC-dextran70 control was distributed broadly throughout the distal intestine and cecum by 30 minutes with no retention in the duodenum. Conclusion: Imaging studies confirm that GLY-200 conjugates are retained in the duodenum after oral administration. These data support the hypothesis that GLY-200 treatment results in a pharmacologic duodenal exclusion that could potentially recapitulate the glycemic and weight effects of metabolic surgery and duodenal exclusion devices. Disclosure A.Nimgaonkar: Employee; Glyscend Inc. C.Bryant: Employee; Glyscend Inc. T.Carlson: Employee; Glyscend Inc. F.V.Guerina: Employee; Glyscend Inc. K.Colbert: Consultant; LifeSprout, Employee; Glyscend Inc. S.Polomoscanik: None. J.S.Petersen: None. T.H.Jozefiak: Employee; Glyscend Inc., Stock/Shareholder; Glycologix, LLC. M.Fineman: Employee; Glyscend Inc., Stock/Shareholder; Glyscend Inc.

Effects of supplementing a plant protein-rich diet with insect, crayfish or microalgae meals on gilthead sea bream (Sparus aurata) and European seabass (Dicentrarchus labrax) growth, physiological status and gut health

This study was aimed at evaluating growth response, gut health and physiological status of seabream (GSB) and European seabass (ES) juveniles fed diets totally deprived of fish meal and supplemented with alternative ingredients. Fish were fed four isoproteic (45%) and isolipidic (20%) diets in which meals from black soldier fly (Hermetia illucens, H) prepupae, whole red swamp crayfish (Procambarus clarkii, RC) or a microalgae blend (Tisochrysis lutea and Tetraselmis suecica, MA) were used as supplements to replace 10% protein of a fish meal-free, plant protein-based diet high in soybean meal (CV). Each diet was fed to triplicate fish groups kept in a RAS (Temperature 23.5 °C, Salinity 29 ppt) over 12 (GSB) and 18 (ES) weeks. In both fish species, MA diet resulted in the worst specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) compared to CV. Diet H significantly improved the SGR only in GSB without affecting FCR. The dry matter apparent digestibility coefficient (ADC) was highest in the H diet (approximately 76%) and lowest in MA (around 73%), while an intermediate value was recorded for the RC diet, in both fish species. Slightly inflamed intestine and altered mucosa morphology were observed in both fish species fed on CV diet, highlighting a higher susceptibility of GSB to this diet. On the contrary, diets H, RC and MA led to a modulation of inflammatory gene expression in the distal intestine from the two fish species. However, while H and RC diets lead to a more evident intestine status improvement in GSB, in ES this result was evident even in response to MA diet administration. The MA diet induced a lowering of nutritional status compared to CV in both GSB and ES. Overall the results have shown that 10% protein from H and RC in a plant protein-based diet, tends to improve fish growth and gut health in both fish species. In ES also the diet including microalgae turned in a beneficial effect on fish gut health, compared to CV one, although it needs further refinement to reduce the adverse impact on growth and physiological status. Our findings suggest the potential use of insect and crayfish meals as functional ingredients in fish meal-free diets for GSB and ES, while further studies are needed to refine the use of microalgae as functional feed supplements in diets for sub-adult gilthead seabream and European seabass.