Scomber Scombrus Research Articles

The genome sequence of the Atlantic mackerel, Scomber scombrus Linnaeus, 1758

We present a genome assembly from an individual Scomber scombrus (the Atlantic mackerel; Chordata; Actinopteri; Scombriformes; Scombridae). The genome sequence has a total length of 764.10 megabases. Most of the assembly is scaffolded into 24 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 16.56 kilobases in length.

Estimating the fishing rate for maximum nutritional yield (FMNY) optimizes fish production for human health

Abstract Fisheries management is largely based on the principle of achieving the maximum sustainable yield (MSY) with little regard for nutritional value. Management strategies maximizing nutrients rather than yield, however, may provide a smarter contribution to global food and nutrition security. Here, we present a novel fisheries management strategy: fishing at maximum nutritional yield (FMNY), the exploitation rate at which essential nutrients are maximized. Combining top-down population modelling approaches with bottom-up nutrient compositional analysis, we compared nutrient yields across seasons for Europe’s most valuable fishery (Atlantic mackerel, Scomber scombrus). FMNY estimates differed between nutrients, but were equal to, or lower than, FMSY. An autumn fishery provided higher amounts of lipids, omega-3 fatty acids, and protein, whereas vitamin D3, and calcium were maximized in winter. Aligning national fisheries policies and nutrition objectives is paramount to realising the potential of seafood in building healthier food systems. Developing novel fisheries management strategies, such as FMNY, where fisheries are optimised for human nutrition will, therefore, contribute to nutrient sustainability and help improve human health and diets.

Exploring the Physicochemical Characteristics of Marine Protein Hydrolysates and the Impact of In Vitro Gastrointestinal Digestion on Their Bioactivity.

Fish protein hydrolysates (FPHs) were obtained from different fish sources using a combination of microbial enzymes. The industrially produced FPHs from blue whiting (Micromesistius poutassou) and sprat (Sprattus sprattus) were compared to freeze-dried FPHs generated in-house from hake (Merluccius merluccius) and mackerel (Scomber scombrus) in terms of their physicochemical composition and functionality. Significant differences (p < 0.05) were observed in the protein, moisture, and ash contents of the FPHs, with the majority having high levels of protein (73.24-89.31%). Fractions that were more extensively hydrolysed exhibited a high solubility index (74.05-98.99%) at different pHs. Blue whiting protein hydrolysate-B (BWPH-B) had the highest foaming capacity at pH 4 (146.98 ± 4.28%) and foam stability over 5 min (90-100%) at pH 4, 6, and 8. The emulsifying capacity ranged from 61.11-108.90 m2/g, while emulsion stability was 37.82-76.99% at 0.5% (w/v) concentration. In terms of peptide bioactivity, sprat protein hydrolysate (SPH) had the strongest overall reducing power. The highest Cu2+ chelating activity was exhibited by hake protein hydrolysate (HPH) and mackerel protein hydrolysate (MPH), with IC50 values of 0.66 and 0.78 mg protein/mL, respectively, while blue whiting protein hydrolysate-A (BWPH-A) had the highest activity against Fe2+ (IC50 = 1.89 mg protein/mL). SPH scavenged DPPH and ABTS radicals best with IC50 values of 0.73 and 2.76 mg protein/mL, respectively. All FPHs displayed noteworthy scavenging activity against hydroxyl radicals, with IC50 values ranging from 0.48-3.46 mg protein/mL. SPH and MPH showed the highest scavenging potential against superoxide radicals with IC50 values of 1.75 and 2.53 mg protein/mL and against hydrogen peroxide with 2.22 and 3.66 mg protein/mL, respectively. While inhibition of α-glucosidase was not observed, the IC50 values against α-amylase ranged from 8.81-18.42 mg protein/mL, with SPH displaying the highest activity. The stability of FPHs following simulated gastrointestinal digestion (SGID) showed an irregular trend. Overall, the findings suggest that marine-derived protein hydrolysates may serve as good sources of natural nutraceuticals with antioxidant and antidiabetic properties.

Occurrence of larval anisakid in imported mackerel (Scomber scombrus) in Astana fish markets

Occurrence of larval anisakid in imported mackerel (Scomber scombrus) in Astana fish markets

Preservative Effect of a Gelatin-Based Film Including a Gelidium sp. Flour Extract on Refrigerated Atlantic Mackerel

This research evaluated the preservative properties of flour from the alga Gelidium sp., which is a waste substrate resulting from commercial phycocolloid extraction. Gelatin-based biofilms, which included two different concentrations of red alga flour, were developed and used as packaging systems during refrigerated storage (up to 9 days at 4 °C) of Atlantic mackerel (Scomber scombrus) muscle. In all batches tested, a progressive decrease in quality could be observed in the muscle of the fish as the storage time increased. Compared with the control fish, the Gelidium alga flour extract had an inhibitory effect (p &lt; 0.05) on microbial activity (total aerobes, psychrotrophs, and proteolytic bacteria), lipid oxidation (peroxide, thiobarbituric acid, fluorescence and polyene indices), lipid hydrolysis (formation of free fatty acids) and pH increase in refrigerated mackerel muscle. In contrast, no significant effect (p &gt; 0.05) was observed on trimethylamine formation, Enterobacteriaceae, or lipolytic bacteria counts. A preservative effect resulting from the incorporation of Gelidium alga flour into the gelatin-based biofilm was observed, indicating both quality and safety enhancement. In accordance with current global interest in the search for natural and waste sources, a novel and beneficial use of Gelidium flour for enhancing the quality of refrigerated fish has been proposed.

Study of Fungal Organisms Associated with Smoked and Dried Fish Sold in Awka Markets, Anambra State

Fungal contamination of fish is considered as the major cause of spoilage and it constitutes a significant public health problem. This study was carried out to determine the fungal organisms associated with smoked and dried fish samples: Scomber scombrus (Mackerel), Sardinella longiceps (Sardine), Oreochromis niloticus (Tilapia), Clarias gariepinus (catfish), Gadus morhua (Stock fish), Ethmalosa fimbriata (Bonga fish), and Citharinus citharus (Mangala) sold in Awka markets, Anambra State, Nigeria. A total of fifty (50) (25 smoked and 25 dried) fishes were obtained from three markets in Awka and examined microbiologically for viable fungal infestation using Potato Dextrose Agar (PDA) media. A total of 121 fungal organisms were isolated from 25 smoked and 25 dried fish samples and identified. The isolated fungi were Mucor spp, Aspergillus niger, Aspergillus flavus, Penicillium spp, Fusarium spp and Rhizopus spp. It was observed that all the fish samples harboured multiple fungal organisms. Aspergillus niger was the fungus with the highest mean fungal count of 9.00±5.568, followed by Mucor spp (8.00±1.732), while Aspergillus flavus was the lowest (3.67±1.528). In the dried fish samples, Gardus morhua (stock fish) had the highest infestation with fungi (1.08±1.083), while in smoked fish, Clarias gariepinus (catfish) had the highest infestation. The high level of fungal contamination can be attributed to poor handling of fish and the environment. Considering the danger to public health, food and safety authorities should intensify their monitoring efforts towards controlling fish contamination, and fish sellers should also be sensitized on hygienic fish handling techniques.

Adaptive small-scale fisheries in the eastern Cantabrian coast through reliance on essential species

Abstract In recent decades, small-scale fisheries (SSF) activity along the Basque coast (eastern Cantabrian) has declined, which has led remaining vessels to undergo notable shifts in their targeted species and therefore the fishing gears used, aimed at enhancing efficiency. Within that context, this study combines logbooks and sales notes spanning from 1995 to 2022 to assess inter-annual and seasonal variations in fishing activity and the main target species across different fishing gears, namely ‘fleet segments’. Results reveal that the spring Atlantic mackerel (Scomber scombrus) and summer albacore (Thunnus alalunga) seasons, with an intensified harvesting under favourable conditions during the past decade, affected the activity of all other segments throughout the year. In the face of climate change affecting harvested species, a scenario where mackerel and/or albacore seasons are disturbed would lead the SSF to predominantly depend on European hake, mainly caught by declining longlines and set nets, as well as on complementary species. Assessing essential species targeted by each SSF segment relies on is crucial for stakeholders as it helps manage interactions between fleets targeting the same species (e.g. SSF vs. industrial and recreational fisheries), and understand gear shifts by vessels targeting specific species in certain seasons.

Assessment of microplastic pollution in eleven commercial fish species in the Gulf of İzmir (Aegean Sea, eastern Mediterranean)

With global plastic production reaching 400 million tons in 2022, concerns about plastic pollution in the seas are increasing day by day. Therefore we focused on the abundance, characteristics, and chemical composition of potential anthropogenic origin MPs within the gastrointestinal tracts (GITs) of 11 commercial fish species in the Gulf of İzmir, an area heavily impacted by human activities. Within the scope of the study, 152 fish were sampled, and microplastics were found in 64 fish. In total, 77 MPs were identified based on ATR-FTIR analysis. Significant differences were found between species regarding MP abundance. Among the species, Scomber scombrus showed the highest MP ingestion. The MP abundance in the GIT of fish decreases from surface to deeper waters. There were also significant differences (p < 0.05) in MP abundance between pelagic and demersal fish species. Results showed that 50.6 % of MPs were fragments, and 49.4 % were fibers. The most common color was black. Seven polymer types were identified, and PE was the most common. The size of the identified MPs ranged from 101 to 4901 μm, and the average value was 715.83 ± 860.66 μm. This study sheds light on the MP contamination within commercial fish species in the Gulf of İzmir and emphasizes the urgent need for enhanced marine ecosystem conservation strategies. Our findings can serve as a basis for future studies by providing essential baseline data for implementing necessary policies and regulations.

Effect of ultrasound treatment on quality parameters and health promoting activity of fish protein hydrolysates extracted from side streams of Atlantic mackerel (Scomber scombrus).

Fish protein hydrolysates (FPH) obtained by enzymatic hydrolysis allows for smart valorization of fish side streams. However, further treatments are normally needed to enhance bioactive and functional properties of the obtained FPH. At present, the commonly used methods to improve functional properties of FPH include chemical and enzymatic modification. Chemical treatments often cause environmental problems, while the enzymatic modification method requires the use of quite expensive enzymes. In recent years, emerging technologies such as ultrasound treatment (US-treatment) have shown great potential in protein modification with high efficiency and safety, low energy consumption, and low nutritional destructiveness. In this study, high-power ultrasound treatments were applied to fish protein hydrolysates (FPH) extracted from Atlantic mackerel (Scomber scombrus) side streams to improve their quality parameters. The effect of three different treatments of 300 W, 450 W and 600 W at the operating frequency of 20 kHz for 10 min on the physicochemical, structural, and functional characteristics of FPH, were examined. The results have shown that with an increase in ultrasound power, the protein solubility of FPH increased linearly, and the changes were significant for all US-treated samples compared to control (untreated) samples. US-treatment significantly increased the degree of hydrolysis of FPH samples treated with 450 W and 600 W compared to control samples. The carbonyl content of FPH increased (significantly for 450 W and 600 W), while thiol groups decreased (significantly for 300 W and 450 W). This indicated that some US-treatments induced oxidation of FPH, however the values of the protein oxidation were low. Amino acid composition of FPH revealed that US-treatment increased the proportion of essential amino acids in the sample treated with 300 W and 450 W, but the increase was not significant. After the US-treatment, all FPH samples became lighter and less yellowish and reddish, which suggest potentially higher attractiveness to consumers. In addition, the in vitro antioxidant activity was assessed using the DPPH, FRAP, and ABTS assays and the cell-free dipeptidyl peptidase IV (DPP-IV) inhibitory activity was also measured. Moreover, these biological activities were measured at cellular level utilizing human intestinal Caco-2 cells. Specifically, the FPH capacity to lower H2O2-induced reactive oxygen species (ROS) and lipid peroxidation levels was used to measure its antioxidant activity. The findings suggest that Scomber scombrus hydrolysates could find use as ingredients for promoting health.

Microbial Load and Antibiotic Resistance Pattern of Microflora Isolated from Smoked Catfish and Mackerel Sold in Ghanaian Markets: A Potential Health Threat

Introduction: Smoked fish, particularly catfish and mackerel, plays a vital role in the Ghanaian diet, serving as a rich source of protein and essential nutrients. Smoking is a traditional preservation method widely used to extend the shelf life of fish, enhance flavor, and make it more palatable. However, despite the advantages of smoking, the process does not entirely eliminate the risk of microbial contamination, which can have significant health implications. Aim of Study: This study examined the microbial flora contamination of the smoked fish sold in Ghanaian markets. Methodology: The research was conducted in three markets: Kejetia Market, Ejura Market and Ejusu. A total of 75 different smoke-dried fish including Cat fish (Clarias gariepinus) and Mackerel (Scomber scombrus) from the markets. The fish samples were collected and kept in sterile polythene bags and transported to the laboratory for microbial analysis. Result: The study revealed that out of 75 samples analyzed, approximately 23% (n=17) were found to be contaminated with microorganisms. Escherichia coli had the highest occurrence, detected in 35.2% (6/17) of the total samples. Additionally, Shigella flexneri and Salmonella arizonae were each found in 17.6% (3/17) of the total samples. Klebsiella oxytoca was 11.7% (2/17), and Enterobacter aerogenes, Streptobacillus monilliforms, and Fusobacterium necrophorus each constituted 5.8% (1/17) of the total samples. All the identified isolates were susceptible to gentamycin (100%), and all the isolates were resistant to lincomycin (100%). Overall resistance rates for each antibiotic for all the organisms identified are lincomycin (100%), penicillin (67%), ampicillin (81%), erythromycin (65%), tetracycline (63%), neomycin (61%), cloxaxillin (43%), kanamycin (24%), and sulphamethaxole (13%). All the isolates have 100% resistance to at least three antibiotics used except for Salmonella arizonae. Conclusion: To Address these findings, a collaborative effort is required among regulatory authorities, food producers, and healthcare providers to implement stringent food safety protocols and mitigate the risks associated with contaminated fish consumption.

Fourier-transform near-infrared spectroscopy first application to age determination in European fish species: the case of the Atlantic horse mackerel from the central Mediterranean Sea

Fourier-transform near-infrared spectroscopy (FT-NIRS) has recently been used to reduce the processing time for estimates of annual age in several fish species. The present study represents the first application of this technique to marine organisms from the European waters. Atlantic horse mackerel (Trachurus trachurus) from the central Mediterranean Sea was selected for its ecological role, its socioeconomic value, and because its age is regularly estimated by otolith reading under a stereomicroscope for stock assessment purposes. Absorption spectra of the whole otoliths were acquired by FT-NIRS across a multiyear dataset, obtained during acoustic surveys carried out in different regions of the central Mediterranean Sea. The acquired spectra were processed to optimize calibration models to predict age. The best linear models obtained by the optimizing procedure predicted age successfully with a coefficient of determination of 0.95–0.96, mean squared error of 0.5 years, and bias &amp;lt;0.03 years. Although regional calibration models were also obtained separately, the models with all regions combined appeared much more robust and encompassing the whole age range, suggesting its usefulness for the entire spatial distribution range considered in the preset study. The use of FT-NIRS allowed to successfully predict age for horse mackerel between the ages 1 and 14, with similar or better precision (and bias) of the traditional methods, also increasing the standardization by repeatability of age assignments. The preliminary results obtained by this study encourage further effort to fine-tune the calibration model for new species, in order to apply a precise, rapid, cost-effective method for stock assessment purposes of Mediterranean fish resources.

Evolution of Eight Biogenic Amines in Raw and Preserved Mackerel (Scomber scombrus) Fillets Monitored by UHPLC-PDA

Evolution of Eight Biogenic Amines in Raw and Preserved Mackerel (Scomber scombrus) Fillets Monitored by UHPLC-PDA

Effect on catch efficiency and bycatch by introducing an Excluder device in the trawl fishery for lesser sandeel (Ammodytes marinus).

Sampling of the North Sea trawl fishery for lesser sandeel (Ammodytes marinus) showed that 96% of the catch weight consisted of the target species, and experimental sea trials demonstrated that the observed small bycatch percentages of haddock (Melanogrammus aeglefinus), mackerel (Scomber scombrus) and grey gurnard (Eutrigla gurnardus) could be significantly lowered by inserting a netting-based sorting device, an Excluder, in front of the codend. The sandeel fishery is conducted with small meshes in the codend, due to the small size and elongated body shape of this species. It is not mandatory for sandeel trawls to have any other selection devices than the small-meshed codend, and this can potentially cause problems with bycatch of unwanted species, if these are abundant on the fishing grounds. Therefore, we sampled the catch composition in this fishery and further, we compared the capture efficiency and species composition of a standard trawl, and one fitted with an additional sorting device called the Excluder. Overall, results showed small percentages of bycatch in the trips sampled and during the trials, the excluder significantly reduced the bycatches of mackerel, grey gurnard, and haddock above certain sizes. For other bycatch species results were inconclusive due to wide confidence limits affected by low bycatch numbers during the trials. The overall capture efficiency for the target species was not affected by adding the excluder in the trawl except for a significant reduction for a few semi-centimetre groups of the largest sizes of the species. These results highlight the potential of the Excluder as a bycatch reduction tool in the sandeel fishery for situations where bycatch can constitute a problem.

Metal variability in small pelagic fish Scomber colias as influenced by volcanic events in the Canary Islands.

Offshore volcanic activity occurs when an underwater volcano erupts. These volcanoes can be located underwater or on land and can be very dangerous to marine life. The aim of this study is to examine whether the influence of two volcanoes has an effect on the concentrations of metals and trace elements in the Atlantic mackerel Scomber colias in the Canary Islands. For the study, ten specimens of S. colias were obtained from each sampling area in March 2022. Metal concentrations were determined by inductively coupled plasma optical emission spectrophotometry (ICP-OES). The specimens of Scomber colias from the area affected by the Tajogaite volcano (La Palma) showed higher concentrations of all metals and trace elements analyzed than those from the other study areas. The specimens from the area of influence of the Tagoro Volcano (El Hierro) showed the second highest concentration of the elements studied, although this volcanic process is in a state of degassing.

Methods to Screen the Adhesion of Fish Cells on Plant-, Algal- and Fungal-Derived Biomaterials.

Cellular agriculture, an alternative and innovative approach to sustainable food production, has gained momentum in recent years. However, there is limited research into the production of cultivated seafood. Here, we investigated the ability of fish mackerel cells (Scomber scombrus) to adhere to plant, algal and fungal-based biomaterial scaffolds, aiming to optimize the cultivation of fish cells for use in cellular agriculture. A mackerel cell line was utilized, and metabolic assays and confocal imaging were utilized to track cell adhesion, growth, and differentiation on the different biomaterials. The mackerel cells adhered and grew on gelatin (positive control), zein, and soy proteins, as well as on alginate, chitosan, and cellulose polysaccharides. The highest adhesion and growth were on the zein and chitosan substrates, apart from the gelatin control. These findings provide a blueprint to enhance scaffold selection and design, contributing to the broader field of cellular agriculture through the development of scalable and eco-conscious solutions for meeting the growing global demand for seafood.

Phenotypic response of a geographically expanding species, Scomber colias: Clues in the fish otolith shape

During the last decades, there has been a growing interest in the Atlantic chub mackerel, Scomber colias, owing to its northward expansion across the East Atlantic Ocean. This trend has been observed from regions of higher abundance off northwest Africa to the waters of the Atlantic Iberian and the Mediterranean Sea. Changes in abundance and spatial distribution of Atlantic chub mackerel have been previously studied and various theoretical models have been proposed to elucidate the changes in its abundance and biomass. However, within this fishing context, only a limited number of studies have attempted to understand how this species has responded at both the individual and population levels to the changing environmental conditions. The phenotypic variability of 1660 individuals of S. colias collected from the Canary Islands, Madeira, the Cantabrian Sea and the Central-Northern Mediterranean Sea was examined, with a specific focus on otolith shape. We identified six morphotypes classified into two groups and associated to the four analyzed regions. Despite of the occurrence of shared phenotypes in varying proportions among the different fishing grounds, this classification might be explained by the adaptation of certain morphotypes to specific environmental conditions and the migratory behavior of this species. The morphotypes M1-M5 were more abundant in the warmer waters of Madeira-Canary Islands region and M6 in the colder waters of Ligurian-Cantabrian. It is plausible that the former set may represent resident contingents, while morphotypes M2-M3 and M4 are likely to exhibit migratory behavior. Therefore, we suggest a complex metapopulation structure, where different contingents coexist.

Quantifying global redundant fisheries trade to streamline seafood supply chains.

Seafood plays an important role in sustainably feeding the world and is one of the most traded food products globally. However sustainability improvements are often focused on its production (e.g., aquaculture, fishing) rather than trade. Here, we quantify the magnitude and extent of global 'redundant two-way' seafood trade-the exchange of the same quantity of the same taxonomic species between two countries-to examine its prevalence and potential implications across the seafood supply chain. We focused on wild-caught seafood trade and found that redundant two-way trade has increased by 43%, between 2000 and 2015, making up 3.2% (7.7 Mt) of global seafood trade during that period. Although most countries were involved in redundant two-way seafood trade (111 of 212 analyzed), the majority occurred between five trade partners: Canada and the United States (15%), Germany and the Netherlands (11.8%); Denmark and Sweden (10.6%); Germany and Denmark (7.1%); and France and Norway (7%). Nearly 50% of redundant trade is made up of just four species including Atlantic herring, Atlantic cod, Skipjack tuna and Atlantic mackerel. While deficiencies in global seafood trade data mask seasonal and product heterogeneity, redundant trade could have implications for meeting conservation and sustainable development goals. Future research should build upon these findings to explore specific environmental, economic, and social implications associated with redundant two-way trade to benefit producers and consumers within the seafood supply chain.

Mercury exposure and trophic ecology of urban nesting black-legged kittiwakes from France

Seabirds are increasingly used as bioindicators for assessing the chemical contamination of marine ecosystems, including by mercury (Hg) worldwide. However, some geographical areas are still poorly documented, as metropolitan France that is home to 28 seabird species including the black-legged kittiwake Rissa tridactyla, in the part of the southern limit of the North Atlantic range of the species. Here, we investigated Hg contamination and trophic ecology of black-legged kittiwakes breeding in the harbour of Boulogne-sur-Mer, Northern France. Mean blood Hg concentration was 4.81 ± 1.20 μg g−1 dw (dry weight), 3.66 ± 0.75 μg g−1 dw and 0.43 ± 0.07 μg g−1 dw for adult males, adult females, and chicks, respectively. According to Hg toxicity benchmarks for avian blood, 30% of the sampled adults were considered to be at moderate risk to Hg toxicity. Stable isotope and food analyses showed that highest δ15N values (reflecting a higher trophic position) were related to highest blood Hg concentrations in adult birds, and that Atlantic herring (Clupea harengus) and Atlantic mackerel (Scomber scombrus) were the main prey. Adult kittiwakes from Boulogne-sur-Mer showed Hg levels three times higher than those found in Arctic nesting kittiwakes, where sublethal effects have been documented. This study provides a first description of Hg contamination of black-legged kittiwakes breeding in France and calls for future ecotoxicological research to assess the vulnerability of this species in the southern part of its distribution range.

The addition of ascorbic acid improves the microbiological quality and shelf life of Atlantic mackerel (&lt;i&gt;Scomber scombrus&lt;/i&gt;) fillets stored in ice

Ascorbic acid is one of the most promising additives for improving fish shelf life, but studies on its antimicrobial activity during product storage are limited. In this experiment, we assessed the effect of ascorbic acid on the preservability of Atlantic mackerel (Scomber scombrus) fillets during storage in ice. Fillets were treated to reach an ascorbic acid concentration of 0.30 mg/g (T1) and 0.15 mg/g (T2). Samples were stored in ice at 0°C and analyzed at 0, 2, 7, 9, and 14 days for total viable count, specific spoilage organisms (SSOs), Pseudomonas spp., potentially histamine-producing bacteria (HPB), and Enterobacteriaceae. Growth curves were constructed using the DMfit tool of Combase, and the shelf life was estimated in relation to microbiological limits reported in the literature. Sensory evaluation was performed using a quality index method scheme. At 7 and 9 days of storage, treated samples exhibited bacterial counts from 0.5 to 1.7 Log CFU/g lower than controls, with a logarithmic reduction proportional to the additive concentration. The antimicrobial action appeared to diminish after 14 days. A consistent effect was observed for potentially HPB, with counts of 1.7 Log CFU/g lower in T1 samples compared to controls at 9 days. The moderate effect on SSOs limited the estimated shelf life, as the critical limit was reached after 7 days and 8.4 days (T1 and T2). Ascorbic acid positively impacted the microbiological characteristics of mackerel fillets. Further investigation into the decay dynamics of the additive in fish products during storage is advisable.

Atlantic Mackerel Is Protective in DSS-Induced Colitis Rat Models

Atlantic Mackerel Is Protective in DSS-Induced Colitis Rat Models