المؤلفون: Yeong-Ho Kwak, Seung-Yong Kim, Young-Shin Go, Dong-Hun Lee, Ha-Yun Song, Sang Ok Chung, Jeong Bae Kim, Bohyung Choi

المصدر: Water, Vol 15, Iss 19, p 3488 (2023)

مصطلحات موضوعية: ecological niche, ontogenetic change, SCA, SIA, δ space, generalists, Hydraulic engineering, TC1-978, Water supply for domestic and industrial purposes, TD201-500

الوصف: We integrated stomach content analysis (SCA) and stable isotope analysis (SIA) to understand ontogenetic niche shifts in the invasive freshwater fish, bluegill, Lepomis macrochirus, inhabiting the Yedang Reservoir in Korea. Based on the total length (TL), we classified L. macrochirus as small (23–57 mm), medium (61–99 mm), or large (100–163 mm). Across all study sites, the index of relative importance (IRI) of zooplankton was high for small individuals, whereas those of benthic macroinvertebrates were high for the medium and large groups. Isotopic niche width estimates based on carbon and nitrogen isotope ratios (δ space) also increased with growth, indicating an ontogenetic niche shift in L. macrochirus. In particular, the δ space and diet plasticity of large fish was higher in the littoral population, implying L. macrochirus are generalist feeders as adults. Individuals classified as small showed confined and constant δ space, regardless of habitat condition. Thus, together with the results on the significantly high IRI of zooplankton, these individuals seem to have strong specialistic feeding ecology. Our study demonstrates the applicability strength of combining SCA and SIA for ecological niche research by providing clear evidence of an ontogenetic niche shift in L. macrochirus and elucidates their feeding ecology.

وصف الملف: electronic resource

العلاقة: https://www.mdpi.com/2073-4441/15/19/3488Test; https://doaj.org/toc/2073-4441Test

الوصول الحر: https://doaj.org/article/b087f3c28d814f6a8c313da427c5ce89Test

المؤلفون: Hyuntae Choi, Bohyung Choi, Yoshito Chikaraishi, Yoshinori Takano, Haryun Kim, Kitack Lee, Dhongil Lim, Kyung-Hoon Shin

المصدر: Frontiers in Marine Science, Vol 9 (2022)

مصطلحات موضوعية: amino acid, nitrogen isotope, sediment, microbial degradation, compound-specific isotope analysis (CSIA), Science, General. Including nature conservation, geographical distribution, QH1-199.5

الوصف: The proportion of amino acids (AAs) in sediment can be used as an indicator of microbial degradation, which is primarily the product of benthic prokaryote activity. The microbial activity would be reflected with the stable isotope ratio of nitrogen (δ15N) at the time of mineralization and resynthesis of AAs. In this study, the compound-specific isotope analysis of individual AAs was used to investigate δ15N variation associated with microbial processes in marine sediment samples. Our results showed a decrease in AA concentrations in core-top sediment was accompanied by an increase in δ15N values, suggesting large 15N enrichment in buried AAs. Phenylalanine displayed an increase in δ15N from the surface to depths greater than 2 cm, whereas relatively constant δ15N values at depths below 2 cm, suggesting that microbial utilization of phenylalanine varies with depth. Glycine showed the highest relative molar contribution (from 12.1 to 36.4%), with the largest δ15N increase (from 0.8 to 8.7) in deep sediment, implying that such information can serve as a measure of AA diagenesis in sedimentary environments. Our results also indicated that the δ15N values of individual AAs in sediment reflected the microbial alteration of organic matter at water-sediment interfaces and in sub-surface environments. These findings form an important basis for interpreting the δ15N values of AAs in sediment.

وصف الملف: electronic resource

العلاقة: https://www.frontiersin.org/articles/10.3389/fmars.2022.1030669/fullTest; https://doaj.org/toc/2296-7745Test

الوصول الحر: https://doaj.org/article/abe4c923ec214bde870756516778b4ddTest

المؤلفون: Hee Young Yun, Thomas Larsen, Bohyung Choi, Eun‐Ji Won, Kyung‐Hoon Shin

المصدر: Ecology and Evolution, Vol 12, Iss 6, Pp n/a-n/a (2022)

مصطلحات موضوعية: amino acid‐specific isotope analysis, biomarkers, diet estimate, isotope differentiation, trophic enrichment, trophic interaction, Ecology, QH540-549.5

الوصف: Abstract Explaining food web dynamics, stability, and functioning depend substantially on understanding of feeding relations within a community. Bulk stable isotope ratios (SIRs) in natural abundance are well‐established tools to express direct and indirect feeding relations as continuous variables across time and space. Along with bulk SIRs, the SIRs of individual amino acids (AAs) are now emerging as a promising and complementary method to characterize the flow and transformation of resources across a diversity of organisms, from microbial domains to macroscopic consumers. This significant AA‐SIR capacity is based on empirical evidence that a consumer's SIR, specific to an individual AA, reflects its diet SIR coupled with a certain degree of isotopic differences between the consumer and its diet. However, many empirical ecologists are still unfamiliar with the scope of applicability and the interpretative power of AA‐SIR. To fill these knowledge gaps, we here describe a comprehensive approach to both carbon and nitrogen AA‐SIR assessment focusing on two key topics: pattern in AA‐isotope composition across spatial and temporal scales, and a certain variability of AA‐specific isotope differences between the diet and the consumer. On this basis we review the versatile applicability of AA‐SIR to improve our understanding of physiological processes as well as food web functioning, allowing us to reconstruct dominant basal dietary sources and trace their trophic transfers at the specimen and community levels. Given the insightful and opportunities of AA‐SIR, we suggest future applications for the dual use of carbon and nitrogen AA‐SIR to study more realistic food web structures and robust consumer niches, which are often very difficult to explain in nature.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-7758Test

الوصول الحر: https://doaj.org/article/b7b190e550bd424fbe898e7bd1f0b014Test

المؤلفون: Yuko Takizawa, Yoshinori Takano, Bohyung Choi, Prarthana S. Dharampal, Shawn A. Steffan, Nanako O. Ogawa, Naohiko Ohkouchi, Yoshito Chikaraishi

المصدر: Progress in Earth and Planetary Science, Vol 7, Iss 1, Pp 1-13 (2020)

مصطلحات موضوعية: Compound-specific isotope analysis, Amino acids, Nitrogen, Carbon, Trophic discrimination, Deamination, Geography. Anthropology. Recreation, Geology, QE1-996.5

الوصف: Abstract Stable nitrogen (15N/14N) and carbon (13C/12C) isotopic compositions of amino acids in organisms have widely been employed as a powerful tool to evaluate resource utilization and trophic connection among organisms in diverse ecosystems. However, little is known about the physiological factors or mechanisms responsible for determining the isotopic discrimination (particularly for carbon) within amino acids of organisms. In the present study, we investigated the inter-trophic discrimination of nitrogen and carbon isotopes within amino acids (Δδ 15NAA and Δδ 13CAA, respectively) using four consumer–diet pairs. Each pairing illustrates a metabolic perspective of isotopic fractionation of amino acids. The Δδ 15NAA values in these combinations reveal a trend consistent with those observed in many other combinations in previous studies. This further validates a standard scenario: the deamination preferentially removes 14N amino group from diet-derived amino acids, leaving behind the 15N-enriched amino acids in consumer biomass. The Δδ 15NAA values thus mirror the activity of amino acid deamination in consumers. In contrast, the trends in the Δδ 13CAA value suggest a different metabolic fate for the amino acid carbon isotope. Based on our results, we predict the following scenario: decarboxylation preferentially removes 12C α-carbon (i.e., carbonyl-carbon) from pyruvic acid in glycolysis, and from α-ketoglutaric acid in the tricarboxylic acid cycle, leaving behind the 13C-enriched both pyruvic and α-ketoglutaric acids. The 13C is then transferred to amino acids that are synthesized from the 13C-enriched precursor molecules within consumers. The Δδ 13CAA values therefore mirror the pathways of de novo amino acid synthesis in consumers. The proposed link between nitrogen and carbon isotopes can refine our knowledge of the potential processes affecting the isotopic fractionation within diet and consumer compartments, as well as environmental samples. Graphical abstract

وصف الملف: electronic resource

العلاقة: http://link.springer.com/article/10.1186/s40645-020-00364-wTest; https://doaj.org/toc/2197-4284Test

الوصول الحر: https://doaj.org/article/f8bb7d6e40d644ca8b3de0448f4a2b31Test

المؤلفون: Bohyung Choi, Changhwa Lee, Yuko Takizawa, Yoshito Chikaraishi, Hye‐Ji Oh, Kwang‐Hyeon Chang, Min‐Ho Jang, Hyun‐Woo Kim, Kyung‐Lak Lee, Kyung‐Hoon Shin

المصدر: Ecology and Evolution, Vol 10, Iss 14, Pp 7250-7260 (2020)

مصطلحات موضوعية: CSIA of amino acids, generalists, nitrogen stable isotope, specialists, trophic niche, trophic position, Ecology, QH540-549.5

الوصف: Abstract To adapt to ecological and environmental conditions, species can change their ecological niche (e.g., interactions among species) and function (e.g., prey‐predation, diet competition, and habitat segregation) at the species and guild levels. Stable isotope analysis of bulk carbon and nitrogen of organisms has conventionally been used to evaluate such adaptabilities in the scenopoetic and bionomic views as the isotopic niche width. Compound‐specific stable isotope analysis (CSIA) of nitrogen within amino acids provides trophic information without any disruption of scenopoetic views in the isotope ratios, unlike conventional bulk isotope analysis provides both information and therefore frequently hinders its usefulness for trophic information. We performed CSIA of amino acids to understand the trophic variability of the pike gudgeon Pseudogobio esocinus and largemouth bass Micropterus salmoides as representative specialist and generalist fish species, respectively, from 16 ecologically variable habitats in the four major rivers of Korea. There was little variation (1σ) in the trophic position (TP) among habitats for P. esocinus (± 0.2); however, there was considerably large variation for M. salmoides (± 0.6). The TP of M. salmoides was negatively correlated with the benthic invertebrate indices of the habitats, whereas the TP of P. esocinus showed no significant correlation with any indices. Thus, these two representative fish species have different trophic responses to ecological conditions, which is related to known differences in the trophic niche between specialists (i.e., small niche width) and generalists (i.e., large niche width). Over the past four decades, the conventional bulk isotope analysis has not been capable of deconvoluting “scenopoetic” and “bionomic” information. However, in the present study, we demonstrated that the CSIA of amino acids could isolate trophic niches from the traditional ecological niche composed of trophic and habitat information and evaluated how biological and ecological indices influence the trophic response of specialists and generalists.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-7758Test

الوصول الحر: https://doaj.org/article/d92fee96405248b0b380ec86333ede8fTest

المؤلفون: Eun-Ji Won, Bohyung Choi, Chang Hwa Lee, Seongjin Hong, Jong-Hyeon Lee, Kyung-Hoon Shin

المصدر: Environment International, Vol 135, Iss , Pp - (2020)

مصطلحات موضوعية: Environmental sciences, GE1-350

الوصف: The trophic magnification of persistent organic pollutants (POPs), which is the relationship between POP concentration and the trophic position (TPs) of an organism, is considered an important factor for prioritizing chemicals of concern in the environment. Organismal TPs are typically based on nitrogen isotope ratios of bulk tissue (δ15Nbulk). In this study, nitrogen isotope ratios of amino acids (δ15NAAs), a more precise approach for TP estimation (TPAAs), was applied and compared with estimations of TP based on δ15Nbulk (TPbulk) in marine organisms living in Masan Bay, South Korea. Compound-specific isotope analysis of the amino acids (CSIA-AAs) in fish samples allows us to calculate robust TPs by correcting the variation in baseline isotope values with use of the δ15Nbulk technique. In a benthic food chain, this approach reveals more significant magnification trends for POPs [polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs)] than those revealed by analysis of the relationship between TPbulk and POPs. The trophic magnification factors (TMF) associated with TPAAs were significant for some POPs, especially pp′-DDD and chlordane. The results presented in this study suggest that TP calculations based on δ15NAAs are an effective tool for characterizing trophic magnification trends related to the fates of various pollutants. Keywords: Compound-specific isotope analysis (CSIA), Food web, Trophic position, Trophic magnification factor (TMF)

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S0160412019328247Test; https://doaj.org/toc/0160-4120Test

الوصول الحر: https://doaj.org/article/9f38cccfe920422ea0cba88b40752deaTest

المؤلفون: Dokyun Kim, Seongjin Hong, Hyuntae Choi, Bohyung Choi, Jaeseong Kim, Jong Seong Khim, Hodong Park, Kyung-Hoon Shin

المصدر: Environment International, Vol 133, Iss , Pp - (2019)

مصطلحات موضوعية: Environmental sciences, GE1-350

الوصف: To determine distributions, bioaccumulation, and trophic transfer of freshwater cyanobacterial toxins such as microcystins (MCs), surface water, suspended solids, sediments, and coastal organisms were collected from seven stations in inner and outer regions of the estuary dam in the Geum River Estuary in June and July 2017. Concentrations of MC variants (MC-LR, -RR, and -YR) in the multimedia samples were analyzed using a HPLC-MS/MS. Trophic position (TP) of organisms (fish, bivalve, gastropod, decapod, and polychaete) was determined by nitrogen stable isotope analyses of both bulk tissues and amino acids. From July to August 2017, great concentrations of MCs were detected in discharged freshwater ranging from 0.4 to 75 μg L−1. Considerable amounts of MCs are delivered to the Geum River Estuary in summer season. MCs spread far away as dissolved phases (18.7–49.5 ng L−1) in July when large amount of freshwater was discharged during the rainy season. Concentrations of MCs in marine organisms varied among species, ranging from 40 to 870 ng g−1 dw. Bioaccumulated MCs tend to decrease with increasing TP of organisms, suggesting that MCs are biodiluted through the marine food web. Compound-specific isotope analysis (nitrogen of amino acids) provides more reliable TPs compared with those by bulk isotope analysis in a closed estuary (such as the Geum River Estuary) with large fluctuations in the isotope ratio of primary producers. Keywords: Cyanobacterial toxin, Estuary, Coastal organisms, Stable isotope, Trophic position, Biodilution

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S0160412019310785Test; https://doaj.org/toc/0160-4120Test

الوصول الحر: https://doaj.org/article/0399e6fb8b5d426ea44fbc82f9c40433Test

المؤلفون: Kiyun Park, Hyunbin Jo, Bohyung Choi, Ihn-Sil Kwak

المصدر: Mitochondrial DNA. Part B. Resources, Vol 5, Iss 3, Pp 2310-2311 (2020)

مصطلحات موضوعية: mitochondrial genome, chironomidae, Genetics, QH426-470

الوصف: The complete mitochondrial genome of Stictochironomus akizukii (Tokunaga) was sequenced. The circular mitochondrial genome is 15,052 bp and consists of 13 protein-coding, 3 ribosomal RNAs, and 22 transfer RNA genes (GenBank accession no. MT185679). Results of maximum likelihood analysis showed that this species clustered with other species of the family Chironomidae. This study will contribute to the phylogenetics of genus Stictochironomus and the other genera of Chironomidae.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2380-2359Test

الوصول الحر: https://doaj.org/article/cda2f08fceda445c91934713b0661ee0Test

المؤلفون: Kiyun Park, Won-Seok Kim, Bohyung Choi, Ihn-Sil Kwak

المصدر: Genes, Vol 11, Iss 9, p 958 (2020)

مصطلحات موضوعية: crustacean, p38 mitogen-activated protein kinase (p38 MAPK), perfluorooctane sulfonate (PFOS), di(2-ethylhexyl) phthalate (DEHP), bisphenol A (BPA), irgarol, Genetics, QH426-470

الوصف: Environmental pollution in the aquatic environment poses a threat to the immune system of benthic organisms. The Macrophthalmus japonicus crab, which inhabits tidal flat sediments, is a marine invertebrate that provides nutrient and organic matter cycling as a means of purification. Here, we characterized the M. japonicus p38 mitogen-activated protein kinase (MAPK) gene, which plays key roles in the regulation of cellular immune and apoptosis responses. M. japonicusp38 MAPK displayed the characteristics of the conserved MAPK family with Thr-Gly-Tyr (TGY) motif and substrate-binding site Ala-Thr-Arg-Trp (ATRW). The amino acid sequence of the M. japonicus p38 MAPK showed a close phylogenetic relationship to Eriocheir sinensis MAPK14 and Scylla paramamosainp38 MAPK. The phylogenetic tree displayed two origins of p38 MAPK: crustacean and insect. The tissue distribution patterns showed the highest expression in the gills and hepatopancreas of M. japonicus crab. In addition, p38 MAPK expression in M. japonicus gills and hepatopancreas was evaluated after exposure to environmental pollutants such as perfluorooctane sulfonate (PFOS), irgarol, di(2-ethylhexyl) phthalate (DEHP), and bisphenol A (BPA). In the gills, p38 MAPK expression significantly increased after exposure to all concentrations of the chemicals on day 7. However, on day 1, there were increased p38 MAPK responses observed after PFOS and irgarol exposure, whereas decreased p38 MAPK responses were observed after DEHP and BPA exposure. The upregulation of p38 MAPK gene also significantly led to M. japonicus hepatopancreas being undertested in all environmental pollutants. The findings in this study supported that anti-stress responses against exposure to environmental pollutants were reflected in changes in expression levels in M. japonicusp38 MAPK signaling regulation as a cellular defense mechanism.

وصف الملف: electronic resource

العلاقة: https://www.mdpi.com/2073-4425/11/9/958Test; https://doaj.org/toc/2073-4425Test

الوصول الحر: https://doaj.org/article/b997a2efb5df4ed985f27a1c7315a7dcTest

المؤلفون: Bohyung Choi, Yoshito Chikaraishi, Yuko Takizawa

المصدر: Researches in Organic Geochemistry. 2018, 34(2):29