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Svein D. Mathiesen - One of the best experts on this subject based on the ideXlab platform.
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Chitinolytic bacteria in the minke whale Forestomach
Canadian journal of microbiology, 2000Co-Authors: M. A. Olsen, W. Sørmo, A S Blix, Tha Utsi, Svein D. MathiesenAbstract:Minke whales consume large amounts of pelagic crustaceans. Digestion of the prey is initiated by indigenous bacteria in a rumen-like Forestomach system. A major structural component of the crustacean exoskeleton is chitin, the β-1,4-linked polymer of N-acetyl-D-glucosamine. The exoskeletons appear to dissolve completely in the non-glandular Forestomach. Bacteria in the Forestomach fluid of six krill-eating minke whales were enumerated and isolated using an anaerobic habitat-simulating culture medium. Median viable population densities ranged between 6.0 × 106 and 9.9 × 109 bacterial cells per mL Forestomach fluid. Bacterial isolates (n = 44) cultured from the Forestomach fluid of one minke whale mainly resembled strains of Eubacterium (25%),Streptococcus (18%), Clostridium (14%), and Bacteroides (11%). As much as 12% of the bacterial isolates were chitinolytic, while β-N-acetylglucosaminidase activity was demonstrated in 54% of the isolates, and utilisation of N-acetyl-D-glucosamine was observed in 73%. T...
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Chitinolytic bacteria in the minke whale Forestomach
Canadian Journal of Microbiology, 1999Co-Authors: M. A. Olsen, W. Sørmo, A S Blix, Tha Utsi, Svein D. MathiesenAbstract:Minke whales consume large amounts of pelagic crustaceans. Digestion of the prey is initiated by indigenous bacteria in a rumen-like Forestomach system. A major structural component of the crustacean exoskeleton is chitin, the β-1,4-linked polymer of N-acetyl-D-glucosamine. The exoskeletons appear to dissolve completely in the non-glandular Forestomach. Bacteria in the Forestomach fluid of six krill-eating minke whales were enumerated and isolated using an anaerobic habitat-simulating culture medium. Median viable population densities ranged between 6.0 × 106and 9.9 × 109bacterial cells per mL Forestomach fluid. Bacterial isolates (n = 44) cultured from the Forestomach fluid of one minke whale mainly resembled strains of Eubacterium (25%),Streptococcus (18%), Clostridium (14%), and Bacteroides (11%). As much as 12% of the bacterial isolates were chitinolytic, while β-N-acetylglucosaminidase activity was demonstrated in 54% of the isolates, and utilisation of N-acetyl-D-glucosamine was observed in 73%. The chitinolytic isolates resembled strains of Bacteroides, Bacteroidaceae, Clostridium, and Streptococcus. Scanning and transmission electron microscopy of partly digested krill from the minke whale Forestomach revealed bacteria close to and inside the chitinous exoskeleton. The bacterial chitinase may act on the chitinous crustacean exoskeletons, thereby allowing other bacteria access to the nutritious soft inner tissues of the prey, and thus initiating its degradation and fermentation.Key words: chitinase, β-N-acetylglucosaminidase, cetacea, symbiotic microbial digestion.
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Chitinolytic bacteria in the minke whale Forestomach
Annales de Zootechnie, 1996Co-Authors: M. A. Olsen, Tove H. Aagnes, W. Sørmo, Svein D. MathiesenAbstract:Minke whales consume large amounts of pelagic crustaceans. Digestion of the prey is initiated by indigenous bacteria in a rumen-like Forestomach system. A major structural component of the crustacean exoskeleton is chitin, the β-1,4-linked polymer of N-acetyl-D-glucosamine. The exoskeletons appear to dissolve completely in the non-glandular Forestomach. Bacteria in the Forestomach fluid of six krill-eating minke whales were enumerated and isolated using an anaerobic habitat-simulating culture medium. Median viable population densities ranged between 6.0 × 10 6 and 9.9 × 10 9 bacterial cells per mL Forestomach fluid. Bacterial isolates ( n = 44) cultured from the Forestomach fluid of one minke whale mainly resembled strains of Eubacterium (25%), Streptococcus (18%), Clostridium (14%), and Bacteroides (11%). As much as 12% of the bacterial isolates were chitinolytic, while β-N-acetylglucosaminidase activ- ity was demonstrated in 54% of the isolates, and utilisation of N-acetyl-D-glucosamine was observed in 73%. The chitinolytic isolates resembled strains of Bacteroides, Bacteroidaceae, Clostridium, and Streptococcus. Scanning and transmission electron microscopy of partly digested krill from the minke whale Forestomach revealed bacteria close to and inside the chitinous exoskeleton. The bacterial chitinase may act on the chitinous crustacean exoskeletons, thereby allowing other bacteria access to the nutritious soft inner tissues of the prey, and thus initiating its degradation and fer - mentation.
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Production rates of volatile fatty acids in the minke whale (Balaenoptera acutorostrata) Forestomach.
The British journal of nutrition, 1996Co-Authors: M. A. Olsen, Svein D. MathiesenAbstract:Minke whales ( Balaenopteva acutorostruta ) have developed a compartmentalized stomach system, which includes a non-glandular Forestomach containing high concentrations of indigenous bacteria. The Forestomach contents serve as microbial substrate, and samples were collected from fiveadult minke whales eating capelin ( Mallotus villosus ) and crustaceans ( Thysanoessa sp. ). Chemical analysis of the Forestomach contents revealed that they consisted of crude protein (650 (SD 58) g/kg DM), lipid (330 (SD77) g/kg DM) and water-soluble carbohydrates (53.3 (SD 7·3) g/kg DM). The contribution of energy from volatile fatty acids (VFA), produced by Forestomach bacterial fermentation, to the total energy budget was estimated. The Forestomach concentration ofVFA ranged from 13·2 to 68·5 mmol/l, and the pH was 5·83 (SD 0·41). VFA pool size ranged from 72·8 to 638·1 mmol and represented from 0·169 to 2·107 kJ/kg live weight (W) 0·75 Maximal recorded Forestomach VFA production rate was 1694 mmol/h in one capelin-eating minke whalewith 42·6 litres of Forestomach fluid. Energy from VFA produced by Forestomach fermentation represented 6–107 kJ/kg w 0·75 per d, which accounts for only 0·9–16·9% of the average daily energy expenditure of minke whales. This study suggests that the bacterial fermentation in the minke whale Forestomach varies, depending on the volume and the quality of substrate available, inlinencing fermentation rates and concentration of VFA. Due to the small relative size of the Forestomach, the contribution of VFA to the daily energy requirement in minke whales would be of less importance than in ruminants even when assuming the same production rate of VFA as in a ruminant.
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digestion of herring by indigenous bacteria in the minke whale Forestomach
Applied and Environmental Microbiology, 1994Co-Authors: M. A. Olsen, Tove H. Aagnes, Svein D. MathiesenAbstract:Northeastern Atlantic minke whales (Balaenoptera acutorostrata) have a multichambered stomach system which includes a nonglandular Forestomach resembling that of ruminants. Bacteria from the Forestomachs of herring-eating whales were enumerated and isolated in an anaerobic rumen-like culture medium (M8W medium). The total viable population of anaerobic bacteria ranged from 73 × 107 to 145 × 108/ml of Forestomach fluid (n = 4). Lactobacillus spp. (19.7%), Streptococcus spp. (35.9%), and Ruminococcus spp. (12.8%) were the most common of the bacterial strains (n = 117) isolated by use of M8W medium from the Forestomach fluid population of two minke whales. Most of the isolates stained gram positive (93.2%), 62.4% were cocci, and all strains were strictly anaerobic. The population of lipolytic bacteria in one animal, enumerated by use of a selective lipid medium, constituted 89.7% of the viable population. The total viable population of anaerobic bacteria in freshly caught and homogenized herring (Clupea harengus) ranged from 56.7 to 95.0 cells per gram of homogenized prey (n = 3) when M8W medium was used. Pediococcus spp. (30.6%) and Aerococcus spp. (25.0%) were most common of the bacterial strains (n = 72) isolated from the homogenized herring. Most of the bacterial strains were gram positive (80.6%), and 70.8% were cocci. Unlike the Forestomach bacterial population, as many as 61.1% of the strains from the herring were facultatively anaerobic. All bacterial strains isolated from the prey had phenotypic patterns different from those of strains isolated from the dominant bacterial population in the Forestomach, indicating that the Forestomach microbiota is indigenous. Scanning electron microscopic examinations revealed large numbers of bacteria, surrounded by a glycocalyx, attached to partly digested food particles in the Forestomach. These data support the hypothesis that symbiotic microbial digestion occurs in the Forestomach and that the bacteria are indigenous to minke whales. Images
Nobuyuki Ito - One of the best experts on this subject based on the ideXlab platform.
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Carcinogenicity of 4-methoxyphenol and 4-methylcatechol in F344 rats.
International journal of cancer, 1994Co-Authors: Emiko Asakawa, Masao Hirose, Akihiro Hagiwara, Satoru Takahashi, Nobuyuki ItoAbstract:The carcinogenic potentials of 4-methoxyphenol (4-MP) and 4-methylcatechol (4-MC), phenolic compounds which are structurally similar to the known Forestomach carcinogen BHA and the glandular stomach carcinogen catechol respectively, and cause considerably enhanced cell proliferation and cytotoxicities in rat Forestomach and/or glandular stomach epithelium, were examined in male and female F344 rats. Groups of 30 male and female animals were administered diets containing 2% 4-MP or 2% 4-MC for 104 weeks. Histopathological findings in the 4-MP case included atypical hyperplasias (male, 67%, female, 37%), papillomas (50%, 23%) and squamous-cell carcinomas (77%, 20%) in the Forestomach. 4-MC induced Forestomach papillomas (70%, 93%) and squamous-cell carcinomas (53%, 37%), also glandular stomach submucosal hyperplasias (90%, 93%), adenomas (100%, 100%) and adenocarcinomas (57%, 47%), with ulceration or erosion. The degree of differentiation of the squamous-cell carcinomas induced by 4-MP was less than with 4-MC. The present study demonstrated unequivocal Forestomach carcinogenicity for 4-MP and Forestomach and glandular stomach carcinogenicity for 4-MC, with cytotoxicity and cell proliferation both appearing as important factors for these non-genotoxic carcinogens.
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Organ-specific modification of carcinogenesis by antioxidants in rats.
Basic life sciences, 1993Co-Authors: Masao Hirose, Kumiko Ogawa, Satoru Takahashi, Tomoyuki Shirai, Nobuyuki ItoAbstract:The synthetic antioxidant butylated hydroxyanisole (BHA) has been shown to induce Forestomach carcinomas in rats and hamsters. It strongly enhances second- stage Forestomach and urinary bladder carcinogenesis in rats pretreated with carcinogens, but inhibits liver, lung, and mammary carcinogenesis (13). BHA at high doses rapidly induces cell proliferation and an increase in DNA synthesis in the Forestomach epithelium of both rats and hamsters, these presumably playing an important role in the observed carcinogenic and promoting effects. Recently, some phenolic antioxidants, i.e., caffeic acid, sesamol, and catechol, have also been shown to induce strong cell proliferation in either the Forestomach or glandular stomach epithelium of rats (9) and hamsters (6). These antioxidants similarly appear to exert carcinogenic potential in their target organs or enhance stomach carcinogenesis. Furthermore, simultaneous treatment with diethylmaleate (DEM), a known glutathione depleter, significantly reduced BHA-induced Forestomach cell proliferation (7), indicating a role for glutathione in the BHA-induced cell proliferation.
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Enhancing effect of concomitant L-ascorbic acid administration on BHA-induced Forestomach carcinogenesis in rats
Carcinogenesis, 1993Co-Authors: Masaaki Shibata, Masao Hirose, Masataka Kagawa, Pleumjit Boonyaphiphat, Nobuyuki ItoAbstract:The effects of the synthetic antioxidant butylated hydroxyanisole (BHA) and naturally occurring antioxidants such as L-ascorbic acid (AsA; vitamin C), citric acid, benzoic acid or gallic acid in combination, on the development of rat Forestomach epithelial lesions were investigated. A dietary level of 2.0% was selected for all antioxidants and the experimental period was 1 year. As compared with BHA alone, treatment with AsA in combination with BHA increased the severity of the hyperplasia in the mid-region, but not in the prefundic region of the Forestomach epithelium, as well as the multiplicity of Forestomach tumors. Furthermore, incidences of squamous cell carcinomas (SCCs) in the Forestomach were significantly elevated in this group, while papilloma development only showed a tendency to increase. In addition, SCC invasion into the muscle layer of the Forestomach was observed only in the BHA + AsA group. Treatment with the other antioxidants did not affect BHA-induced Forestomach lesion development. The present study demonstrated that AsA can clearly enhance BHA Forestomach carcinogenesis.
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Modification of BHA Forestomach carcinogenesis in rats: inhibition by diethylmaleate or indomethacin and enhancement by a retinoid.
Carcinogenesis, 1993Co-Authors: Masaaki Shibata, Masao Hirose, Toshio Kato, Atsuko Masuda, Mamoru Mutai, Nobuyuki ItoAbstract:The long-term effects of butylated hydroxyanisole (BHA), in combination with various other chemicals on the development of Forestomach lesions in rats were investigated. BHA is a synthetic antioxidant, and the other agents included the glutathione-depleting agent diethylmaleate (DEM), the anti-inflammatory drugs indomethacin (IM), dexamethazone (DEX), 6-aminocaproic acetate (6-ACA) and FOY (gabexate mesilate), and the vitamin all-trans-retinol acetate (RA). Concurrent treatment with BHA (1% in diet) and DEM, IM, DEX or FOY for 52 weeks inhibited development of Forestomach epithelial hyperplasia as compared to BHA alone, while simultaneous treatment with RA enhanced hyperplastic development. However, the inhibition by DEX or FOY was only partial and in the DEX case, in particular, might have been due to weight loss. Since the most effective inhibitory influence on BHA-induced Forestomach lesions exerted in this 1-year experiment was by DEM, a further 2-year experiment was conducted to confirm whether DEM actually can exert inhibitory effects on BHA (2% in diet)-induced Forestomach carcinogenesis. The results demonstrated that induction of Forestomach hyperplasias and papillomas by BHA was significantly reduced by combination treatment with DEM. Both multiplicity and incidence of Forestomach papillomas were significantly decreased, while squamous cell carcinoma development showed a tendency for decrease only.
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induction of adenocarcinomas in the glandular stomach of balb c mice treated with n methyl n nitrosourea
Japanese Journal of Cancer Research, 1992Co-Authors: Masae Tatematsu, Kumiko Ogawa, Yutaka Shichino, Toru Hoshiya, Toshio Kato, Katsumi Imaida, Nobuyuki ItoAbstract:Male 6-week-old BALB/c strain animals (groups 1 and 2) received 10 weekly intragastric intubations of 0.5 mg/mouse of N-methyl-N-nitrosourea. At week 11 the Forestomachs were resected in group 1 but not group 2. Although many animals in group 2 died due to development of squamous cell carcinomas in the Forestomach, development of cancers in the glandular stomach was quite similar in both groups. Well-differentiated adenocarcinomas in groups 1 and 2 were found at low incidence at week 20, rising to 100% at week 40, with two lesions metastasizing to the lymph nodes. Four poorly differentiated adenocarcinomas and 5 signet ring cell carcinomas were also found in 27 glandular stomach tumor-bearing animals.
M. A. Olsen - One of the best experts on this subject based on the ideXlab platform.
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Chitinolytic bacteria in the minke whale Forestomach
Canadian journal of microbiology, 2000Co-Authors: M. A. Olsen, W. Sørmo, A S Blix, Tha Utsi, Svein D. MathiesenAbstract:Minke whales consume large amounts of pelagic crustaceans. Digestion of the prey is initiated by indigenous bacteria in a rumen-like Forestomach system. A major structural component of the crustacean exoskeleton is chitin, the β-1,4-linked polymer of N-acetyl-D-glucosamine. The exoskeletons appear to dissolve completely in the non-glandular Forestomach. Bacteria in the Forestomach fluid of six krill-eating minke whales were enumerated and isolated using an anaerobic habitat-simulating culture medium. Median viable population densities ranged between 6.0 × 106 and 9.9 × 109 bacterial cells per mL Forestomach fluid. Bacterial isolates (n = 44) cultured from the Forestomach fluid of one minke whale mainly resembled strains of Eubacterium (25%),Streptococcus (18%), Clostridium (14%), and Bacteroides (11%). As much as 12% of the bacterial isolates were chitinolytic, while β-N-acetylglucosaminidase activity was demonstrated in 54% of the isolates, and utilisation of N-acetyl-D-glucosamine was observed in 73%. T...
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Chitinolytic bacteria in the minke whale Forestomach
Canadian Journal of Microbiology, 1999Co-Authors: M. A. Olsen, W. Sørmo, A S Blix, Tha Utsi, Svein D. MathiesenAbstract:Minke whales consume large amounts of pelagic crustaceans. Digestion of the prey is initiated by indigenous bacteria in a rumen-like Forestomach system. A major structural component of the crustacean exoskeleton is chitin, the β-1,4-linked polymer of N-acetyl-D-glucosamine. The exoskeletons appear to dissolve completely in the non-glandular Forestomach. Bacteria in the Forestomach fluid of six krill-eating minke whales were enumerated and isolated using an anaerobic habitat-simulating culture medium. Median viable population densities ranged between 6.0 × 106and 9.9 × 109bacterial cells per mL Forestomach fluid. Bacterial isolates (n = 44) cultured from the Forestomach fluid of one minke whale mainly resembled strains of Eubacterium (25%),Streptococcus (18%), Clostridium (14%), and Bacteroides (11%). As much as 12% of the bacterial isolates were chitinolytic, while β-N-acetylglucosaminidase activity was demonstrated in 54% of the isolates, and utilisation of N-acetyl-D-glucosamine was observed in 73%. The chitinolytic isolates resembled strains of Bacteroides, Bacteroidaceae, Clostridium, and Streptococcus. Scanning and transmission electron microscopy of partly digested krill from the minke whale Forestomach revealed bacteria close to and inside the chitinous exoskeleton. The bacterial chitinase may act on the chitinous crustacean exoskeletons, thereby allowing other bacteria access to the nutritious soft inner tissues of the prey, and thus initiating its degradation and fermentation.Key words: chitinase, β-N-acetylglucosaminidase, cetacea, symbiotic microbial digestion.
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Chitinolytic bacteria in the minke whale Forestomach
Annales de Zootechnie, 1996Co-Authors: M. A. Olsen, Tove H. Aagnes, W. Sørmo, Svein D. MathiesenAbstract:Minke whales consume large amounts of pelagic crustaceans. Digestion of the prey is initiated by indigenous bacteria in a rumen-like Forestomach system. A major structural component of the crustacean exoskeleton is chitin, the β-1,4-linked polymer of N-acetyl-D-glucosamine. The exoskeletons appear to dissolve completely in the non-glandular Forestomach. Bacteria in the Forestomach fluid of six krill-eating minke whales were enumerated and isolated using an anaerobic habitat-simulating culture medium. Median viable population densities ranged between 6.0 × 10 6 and 9.9 × 10 9 bacterial cells per mL Forestomach fluid. Bacterial isolates ( n = 44) cultured from the Forestomach fluid of one minke whale mainly resembled strains of Eubacterium (25%), Streptococcus (18%), Clostridium (14%), and Bacteroides (11%). As much as 12% of the bacterial isolates were chitinolytic, while β-N-acetylglucosaminidase activ- ity was demonstrated in 54% of the isolates, and utilisation of N-acetyl-D-glucosamine was observed in 73%. The chitinolytic isolates resembled strains of Bacteroides, Bacteroidaceae, Clostridium, and Streptococcus. Scanning and transmission electron microscopy of partly digested krill from the minke whale Forestomach revealed bacteria close to and inside the chitinous exoskeleton. The bacterial chitinase may act on the chitinous crustacean exoskeletons, thereby allowing other bacteria access to the nutritious soft inner tissues of the prey, and thus initiating its degradation and fer - mentation.
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Production rates of volatile fatty acids in the minke whale (Balaenoptera acutorostrata) Forestomach.
The British journal of nutrition, 1996Co-Authors: M. A. Olsen, Svein D. MathiesenAbstract:Minke whales ( Balaenopteva acutorostruta ) have developed a compartmentalized stomach system, which includes a non-glandular Forestomach containing high concentrations of indigenous bacteria. The Forestomach contents serve as microbial substrate, and samples were collected from fiveadult minke whales eating capelin ( Mallotus villosus ) and crustaceans ( Thysanoessa sp. ). Chemical analysis of the Forestomach contents revealed that they consisted of crude protein (650 (SD 58) g/kg DM), lipid (330 (SD77) g/kg DM) and water-soluble carbohydrates (53.3 (SD 7·3) g/kg DM). The contribution of energy from volatile fatty acids (VFA), produced by Forestomach bacterial fermentation, to the total energy budget was estimated. The Forestomach concentration ofVFA ranged from 13·2 to 68·5 mmol/l, and the pH was 5·83 (SD 0·41). VFA pool size ranged from 72·8 to 638·1 mmol and represented from 0·169 to 2·107 kJ/kg live weight (W) 0·75 Maximal recorded Forestomach VFA production rate was 1694 mmol/h in one capelin-eating minke whalewith 42·6 litres of Forestomach fluid. Energy from VFA produced by Forestomach fermentation represented 6–107 kJ/kg w 0·75 per d, which accounts for only 0·9–16·9% of the average daily energy expenditure of minke whales. This study suggests that the bacterial fermentation in the minke whale Forestomach varies, depending on the volume and the quality of substrate available, inlinencing fermentation rates and concentration of VFA. Due to the small relative size of the Forestomach, the contribution of VFA to the daily energy requirement in minke whales would be of less importance than in ruminants even when assuming the same production rate of VFA as in a ruminant.
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digestion of herring by indigenous bacteria in the minke whale Forestomach
Applied and Environmental Microbiology, 1994Co-Authors: M. A. Olsen, Tove H. Aagnes, Svein D. MathiesenAbstract:Northeastern Atlantic minke whales (Balaenoptera acutorostrata) have a multichambered stomach system which includes a nonglandular Forestomach resembling that of ruminants. Bacteria from the Forestomachs of herring-eating whales were enumerated and isolated in an anaerobic rumen-like culture medium (M8W medium). The total viable population of anaerobic bacteria ranged from 73 × 107 to 145 × 108/ml of Forestomach fluid (n = 4). Lactobacillus spp. (19.7%), Streptococcus spp. (35.9%), and Ruminococcus spp. (12.8%) were the most common of the bacterial strains (n = 117) isolated by use of M8W medium from the Forestomach fluid population of two minke whales. Most of the isolates stained gram positive (93.2%), 62.4% were cocci, and all strains were strictly anaerobic. The population of lipolytic bacteria in one animal, enumerated by use of a selective lipid medium, constituted 89.7% of the viable population. The total viable population of anaerobic bacteria in freshly caught and homogenized herring (Clupea harengus) ranged from 56.7 to 95.0 cells per gram of homogenized prey (n = 3) when M8W medium was used. Pediococcus spp. (30.6%) and Aerococcus spp. (25.0%) were most common of the bacterial strains (n = 72) isolated from the homogenized herring. Most of the bacterial strains were gram positive (80.6%), and 70.8% were cocci. Unlike the Forestomach bacterial population, as many as 61.1% of the strains from the herring were facultatively anaerobic. All bacterial strains isolated from the prey had phenotypic patterns different from those of strains isolated from the dominant bacterial population in the Forestomach, indicating that the Forestomach microbiota is indigenous. Scanning electron microscopic examinations revealed large numbers of bacteria, surrounded by a glycocalyx, attached to partly digested food particles in the Forestomach. These data support the hypothesis that symbiotic microbial digestion occurs in the Forestomach and that the bacteria are indigenous to minke whales. Images
Pradeep Garg - One of the best experts on this subject based on the ideXlab platform.
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Tumorigenicity of di-tert-butyl-substituted hydroquinone and hydroxyanisoles in the Forestomach of Syrian golden hamsters
Carcinogenesis, 1991Co-Authors: Luke K.t. Lam, Pradeep GargAbstract:The di-tert-butyl-substituted hydroxyanisoles 2,5-di-tert-butyl-4-hydroxyanisole (2,5-DTBHA) and 3,5-di-tert-butyl-4-hydroxyanisole (3,5-DTBHA) are contaminants of the commercial antioxidant butylated hydroxyanisole. The tumorigenicity of 2,5-DTBHA, 3,5-DTBHA, 2,5-di-tert-butyl hydroquinone (2,5-DTBHQ), a demethylated analog of 2,5-DTBHA, and 3-tert-butyl-4-hydroxyanisole (3-BHA) were investigated. Dietary 3-BHA, which has been shown previously to induce neoplastic lesions in the hamster Forestomach, was found to cause the development of Forestomach papilloma in 75% of the hamsters in 24 weeks at 1% addition to the diet. General thickening of the Forestomach lining with moderate to severe hyperkeratosis and hyperplasia were observed in 14 (88%) of the 16 hamsters in this group. Inflammation was generally found in the Forestomach of these animals. Similar observations were found in 14 (88%) of the 16 hamsters in the group that was fed 1% DTBHQ. Severe hyperplasia and papilloma found in the Forestomach of these hamsters were similar in severity to those in the 3-BHA group. Unlike the 3-BHA and 2,5-DTBHQ groups, the Forestomachs of 1% 2,5-DTBHA and 3,5-DTBHA treated animals were not different from the hamsters in the control group. Only mild hyperplasia at or near the limiting ridge was found in the Forestomach of some of these animals. Hyperkeratosis or inflammation were not observed. Steric factors may play a role in the lack of tumorigenicity of 2,5-DTBHA and 3,5-DTBHA, while the formation of a stable free radical from 2,5-DTBHQ may be the activated species responsible for its tumorigenicity.
Stella Mazeri - One of the best experts on this subject based on the ideXlab platform.
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Observations on the biology, epidemiology and economic relevance of rumen flukes (Paramphistomidae) in cattle kept in a temperate environment.
Veterinary parasitology, 2016Co-Authors: Neil Sargison, Emily Francis, Chloe Davison, Barend M. Dec. Bronsvoort, Ian Handel, Stella MazeriAbstract:Abstract There is concern about the probable recent introduction, increased prevalence and potential economic impact of rumen fluke infection of United Kingdom cattle. A study of 339 cattle slaughtered in a Scottish red meat abattoir was undertaken with the aims of describing the prevalence and geographical distribution of rumen fluke infection, estimating its effect on production, and evaluating faecal egg counts (FECs) as a tool to diagnose infection in live animals and study the epidemiology of the disease. The overall proportion of cattle consigned to the abattoir from northern United Kingdom with rumen fluke infection in the Forestomachs was 0.29. Rumen flukes were distributed predominantly in the cranial sac of the rumen and adjacent to the reticular groove. Overall, a mean of 213 and median of 44 rumen flukes was identified in the Forestomachs of rumen fluke-positive cattle. The mean and median FECs of animals were 26.01 and 5.20 eggs per gram (epg), respectively. There was a significant difference between the mean FECs per rumen fluke of 0.08 and 0.13 epg during summer/autumn and winter sampling periods, respectively. The overall correlation between rumen fluke FECs and the number of flukes in the Forestomach was high, albeit lower in the summer/autumn than in the winter period. The sensitivities of rumen fluke FECs for the identification of flukes in the Forestomach during the summer/autumn and winter sampling periods were 0.65 and 0.85, respectively. These results will aid in the interpretation of rumen fluke FECs when monitoring cattle health and production and studying the parasite's epidemiology in a temperate environment, thereby informing rational, precise and sustainable disease control.