• Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.179-185
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• 2007

Understanding dietary habits is one of the most important factors in studying food webs and other ecological processes. Here we designed universal primers to amplify portions of the 18S and 28S rDNA sequences to examine gut contents using PCR techniques. The gut contents of sailfin sandfish (Arctoscopus japonicus) and pacific squid (Todarodes pacificus) were examined. In total, 11 families of prey were identified with 18S and 28S rDNA using the universal primers. The DNA sequence data indicated that the primer sets successfully amplified a wide spectrum of species and represented gut contents in a relatively convenient way. We found that information in the NCBI database was not yet sufficient to discriminate the species we isolated. In addition, technology for the separation of heterogeneous PCR products and better resolution and quantification protocols would help increase data accuracy.

• The Korean Journal of Malacology
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• v.20 no.1
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• pp.27-34
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• 2004

Based on both field and laboratory experiments, seasonal changes in the species composition and abundance of phytoplankton in the gut contents of the jedo venus clam, Protothaca jedoensis, and its feeding selectivity were investigated. The phytoplankton in the gut contents comprised Bacillariophyceae (diatom), Chlorophyceae, Chrysophyceae, and Dinophyceae, of which the diatoms being the most predominant throughout the year. Although the number of species and the abundance of phytoplankton in the sea water were always more diverse and more abundant than in the gut contents, the relative number and abundance were generally similar in the seawater and in the gut contents. In the laboratory experiments, the relative abundances of Coscinodiscus marginatus and Thalassirosira eccentrica were much more higher in the gut contents than any other algal species, while Paralia sulcata, Skeletonema costatum, and Eucampia zodiacus were abundant in order of cell density in the ambient water. These results suggest that P. jedoensis may feed preferably on single algal cell or smaller chains of algal cells.

• Ocean and Polar Research
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• v.38 no.1
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• pp.35-46
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• 2016

To understand the diet of chaetognaths, the gut content and fatty acid trophic makers (FATMs) of Sagitta crassa and S. nagae, which are the most predominant species of chaetognath in the Yellow Sea, were analyzed. Gut contents of the two species examined by microscopic analysis revealed that copepods are the major components of the diet (> 70% of gut contents) and there was no significant changes in the gut contents of two species collected in spring and summer season. Although 16:0, 20:5(n-3) (Eicosapentaenoic acid) and 22:6(n-3) (Docosahexanoic acid), which are known as phytoplankton FA markers, were the most dominant among the fatty acids in both chaetognath species, the detection of copepod FA markers, 20:1(n-9) (Gadoleic acid) and 22:1(n-11) (Cetoleic acid), provided evidence that their food sources include copepods. These results suggest that S. crassa and S. nagae are carnivores and mainly feed on copepods in the Yellow Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.642-647
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• 2016

Postlarval and juvenile anchovies Engraulis japonicus were collected using a gape net with wings in the coastal waters of Yeosu in July and August 2015, and their gut contents were analyzed. The size range of the postlarvae was 11.0-24.2 mm (notochord length) and that of the juveniles was 25.1-37.4 mm (standard length). Guts were empty in 64.5% of postlarvae and in 51.7% of juveniles. The dominant prey organisms in the guts of both postlarvae and juveniles were copepoda. Calanoida were important prey organisms for postlarvae and were dominated by nauplii of Paracalanus sp. and Calanus sp. as well as unidentified copepod naupill. Calanoida were also important in the diets of juveniles, whose gut contents were dominated by Paracalanus sp. and Cirripedia. Gut compositions were significantly different (P<0.05) among three body size levels in postlarvae and juveniles. As the body size of the postlarvae and juveniles increased, Calanoida constituted a larger proportion of the gut contents, while the proportion of copepod nauplii decreased.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.368-375
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• 2022

Gut contents analysis is essential to predict the impact of organisms on food source changes due to variations of the habitat environment. Previous studies of gut content analysis have been conducted using traditional methods, such as visual observation. However, these studies are limited in analyzing food sources because of the digestive process in gut organ. DNA metabarcoding analysis is a useful method to analyze food sources by supplementing these limitations. We sampled marine fish of Pennahia argentata, Larimichthys polyactis, Crangon affinis, Loligo beka and Sepia officinalis from Gwangyang Bay and Yeosu fisheries market for analyzing gut contents by applying DNA metabarcoding analysis. 18S rRNA v9 primer was used for analyzing food source by DNA metabarcoding. Network and two-way clustering analyses characterized the relationship between organisms and food sources. As a result of comparing metabarcoding of gut contents for P. argentata between sampled from Gwangyang Bay and the fisheries market, fish and Copepoda were analyzed as common food sources. In addition, Decapoda and Copepoda were analyzed as common food sources for L. polyactis and C. affinis, respectively. Copepoda was analyzed as the primary food source for L. beka and S. officinalis. These study results demonstrated that gut contents analysis using DNA metabarcoding reflects diverse and detailed information of biological food sources in the aquatic environment. In addition, it will be possible to provide biological information in the gut to identify key food sources by applying it to the research on the food web in the ecosystem.

• Animal Bioscience
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• v.36 no.11
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• pp.1727-1737
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• 2023

Objective: The poultry industry is a primary source of animal protein worldwide. The gut microbiota of poultry birds, such as chickens and ducks, is critical in maintaining their health, growth, and productivity. This study aimed to identify longitudinal changes in the gut microbiota of laying hens from birth to the pre-laying stage. Methods: From a total of 80 Hy-Line Brown laying hens, birds were selected based on weight at equal intervals to collect feces (n = 20 per growth) and ileal contents (n = 10 per growth) for each growth stage (days 10, 21, 58, and 101). The V4 regions of the 16S rRNA gene were amplified after extracting DNA from feces and ileal contents. Amplicon sequencing was performed using Illumina, followed by analysis. Results: Microbial diversity increased with growth stages, regardless of sampling sites. Microbial community analysis indicated that Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phyla in the feces and ileal. The abundance of Lactobacillus was highest on day 10, and that of Escherichia-shigella was higher on day 21 than those at the other stages at the genus level (for the feces and ileal contents; p<0.05). Furthermore, Turicibacter was the most abundant genus after changing feed (for the feces and ileal contents; p<0.05). The fecal Ruminococcus torques and ileal Lysinibacillus were negatively correlated with the body weights of chickens (p<0.05). Conclusion: The gut microbiota of laying hens changes during the four growth stages, and interactions between microbiota and feed may be present. Our findings provide valuable data for understanding the gut microbiota of laying hens at various growth stages and future applied studies.

• Korean Journal of Ecology and Environment
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• v.54 no.3
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• pp.247-256
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• 2021

Understanding the selective feeding behavior of zooplankton on phytoplankton is essential for evaluating the nutrient cycle and energy flow in the food web. Although many studies have been conducted regarding the feeding behaviors of zooplankton through gut content analyses, there are limitations in the visual identification of digested contents using a microscope. DNA techniques have been applied to overcome these limitations since they can detect and amplify small amounts of prey DNA remaining in the gut contents. We designed a method to extract prey DNA from the gut contents of the whole body of the copepod specimen and tested the resolution of DNA identification for the prey phytoplankton. The common brackish species, Sinocalanus tenellus, were collected from Saemangeum Reservoir in different sites and seasons, and gut content DNA was extracted using 2.5% bleach treatment for 2 min for removal of potential contamination sources existing in preserved specimens without dissolution of the body. The sequences of the extracted gut contents were confirmed using BLASTn suite based on the NCBI database. The phytoplankton species detected in the gut showed temporal and spatial differences. Although DNA analysis of small copepod gut contents has been suggested as an effective method to examine the dynamics of primary prey sources at the genus or species level, uncertainties such as misidentification and limitations in the detailed information of the composition still exist.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.666-671
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• 2001

To investigate the food organisms and feeding selectivity of slimy (Leiognathus nuchalis) during the postlarval stage, the gut contents of the fish, captured in Kwangrang Bay in 1995, were observed. The food organisms in the gut were composed of copepod egg and nauplius, Tintinnopsis spp. and Codonellopsis sp. The indices of relative importance (IRI) indicated that Tintinnopsis spp. was the most dominant food item ($80.6\%$), and copepod nauplius was the next ($18.5\%$). Tintinnopsis spp. was the most favorite food item: it occupied $73.8\%$ of gut contents, though it did $39.2\%$ of microzooplankton in the surrounded water. The composition of copepod nauplius was higher in the larvae shorter than 2.0 mm NL. As slimy larvae grew, the size of food organisms in the gut was not changed, and their number increased, and the selectivity for food items increased.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.575-583
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• 2021

Composition of the gut microbiota changes with aging and plays an important role in age-associated disease such as metabolic syndrome, cancer, and neurodegeneration. The gut microbiota composition oscillates through the day, and the disruption of their diurnal rhythm results in gut dysbiosis leading to metabolic and immune dysfunctions. It is well documented that circadian rhythm changes with age in several biological functions such as sleep, body temperature, and hormone secretion. However, it is not defined whether the diurnal pattern of gut microbial composition is affected by aging. To evaluate aging effects on the diurnal pattern of the gut microbiome, we evaluated the taxa profiles of cecal contents obtained from young and aged mice of both sexes at daytime and nighttime points by 16S rRNA gene sequencing. At the phylum level, the ratio of Firmicutes to Bacteroidetes and the relative abundances of Verrucomicrobia and Cyanobacteria were increased in aged male mice at night compared with that of young male mice. Meanwhile, the relative abundances of Sutterellaceae, Alloprevotella, Lachnospiraceae UCG-001, and Parasutterella increased in aged female mice at night compared with that of young female mice. The Lachnospiraceae NK4A136 group relative abundance increased in aged mice of both sexes but at opposite time points. These results showed the changes in diurnal patterns of gut microbial composition with aging, which varied depending on the sex of the host. We suggest that disturbed diurnal patterns of the gut microbiome can be a factor for the underlying mechanism of age-associated gut dysbiosis.

• Journal of Nutrition and Health
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• v.36 no.2
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• pp.109-116
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• 2003

This study investigated the effects of high amylose starch (HAS) consumption on gut functions in male Sprague-Dawley rats. Experimental animals were fed an diet containing HAS for 4 weeks (0, 125, 250, 500 g/kg diet). Stool weights, transit time, the pH of cecum, Bifidobacterium growth, short chain fatty acid production, and prostaglandin E$_2$production in colon mucus were measured. HAS intake did not affect body weight gain or food efficiency ratio during experimental period. There were no significant differences in kidney weight, epididymal fat pad weights or spleen weights, but the weights of the liver and thymus were significantly lower in the HAS100 group. The length of the large intestine, the weights of the cecum wall and cecum contents, and stool weights significantly increased through HAS intake. But transit time was not affected by the experimental diet. Although Bifidobacterium growth in the cecum increased through the HAS intake dose dependently, there were significant differences in the HAS50 and HAS100 groups. HAS intake increased the production of short chain fatty acid in the cecum contents. In particular, acetate and butyrate concentrations grew significantly. And the production of prostaglandin E$_2$in the colon mucus significantly decreased through HAS intake. These results demonstrate that high amylose starch intake significantly improves gut function.