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Xu, Guangjian,Yang, EunJin,Jiang, Yong,Cho, Kyung-Ho,Jung, Jinyoung,Lee, Youngju,Kang, Sung-Ho Elsevier 2018 MARINE POLLUTION BULLETIN Vol.133 No.-
<P><B>Abstract</B></P> <P>The vertical pattern of pelagic ciliate communities was observed at eight layers in the Chukchi Sea and the northern Bering Sea of the western Arctic Ocean during the summer sea-ice reduction period (August 5 to August 24, 2016). A total of 44 ciliate species were identified, with seven species dominated the communities in the water column. Multivariate and univariate analyses demonstrated that: (1) community structures of ciliates vary significantly among eight water depths; (2) variations in the vertical distribution of ciliates were significantly correlated with changes in physicochemical variables, especially the ammonia; (3) the distributions of the three dominant species were significantly and positively related to the chlorophyll <I>a</I> and ammonia concentrations; and (4) species richness and abundance were significantly and positively correlated with the concentrations of ammonia and chlorophyll <I>a</I>. These results suggest that pelagic ciliates may reflect vertical variations in the water quality status of western Arctic ecosystems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The community patterns of pelagic ciliates showed a significant vertical variation. </LI> <LI> The vertical variation of the ciliates was significantly correlated with abiotic variables. </LI> <LI> Species richness and abundance of the ciliates were significantly related to nutrients. </LI> <LI> The pelagic ciliates may be used to indicate water quality on vertical scales in western Arctic Seas. </LI> </UL> </P>
Xu, Guangjian,Yang, Eun Jin,Xu, Henglong Elsevier 2017 Marine pollution bulletin Vol.121 No.1
<P><B>Abstract</B></P> <P>Trophic-functional groupings are an important biological trait to summarize community structure in functional space. The heterogeneity of the tropic-functional pattern of protozoan communities and its environmental drivers were studied in coastal waters of the Yellow Sea during a 1-year cycle. Samples were collected using the glass slide method at four stations within a water pollution gradient. A second-stage matrix-based analysis was used to summarize spatial variation in the annual pattern of the functional structure. A clustering analysis revealed significant variability in the trophic-functional pattern among the four stations during the 1-year cycle. The heterogeneity in the trophic-functional pattern of the communities was significantly related to changes in environmental variables, particularly ammonium-nitrogen and nitrates, alone or in combination with dissolved oxygen. These results suggest that the heterogeneity in annual patterns of protozoan trophic-functional structure may reflect water quality status in coastal ecosystems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The annual patterns of functional structure of protozoa showed clear spatial variations. </LI> <LI> Spatial variations in functional structure were significantly related to nutrient variables. </LI> <LI> Nutrients and dissolve oxygen may be the main drivers to shape the spatial differences. </LI> <LI> Spatial pattern of functional structure of protozoa may reflect water quality status. </LI> </UL> </P>
Zhong, Xiaoxiao,Xu, Guangjian,Min, Gi-Sik,Kim, Sanghee,Xu, Henglong Elsevier 2019 MARINE POLLUTION BULLETIN Vol.149 No.-
<P><B>Abstract</B></P> <P>To understand tidal disturbance on the colonization dynamics in community functioning of the ciliates in marine ecosystems, a 1-month survey was conducted using the conventional slide system (CS) and the polyurethane foam enveloped slide system (PFES) in Korean coastal waters. The results showed considerable differences were detected in community functioning parameters between the two systems. The vagile, flattened forms feeding on periphytic microalgae showed a higher community-weighted mean (CWM) value, and the solitary-colonial pattern represented a more stable temporal variability during the colonization in the PFES system than the CS system. The temporal shift in community functioning of the ciliates showed different ways in both systems. The functional diversity measures generally levelled off at more stable values in the communities with ages of 13–15 days in the PFES system than the CS system. These results imply that the PFES system may be a workable method for bioassessment in marine ecosystems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> There were differences in community functioning between the CS and PFES systems. </LI> <LI> The vagile, flattened forms showed higher CWM values in the PFES system. </LI> <LI> The solitary-colonial pattern showed a stable temporal variability in the PFES system. </LI> <LI> The dynamics of functional diversity were found more stable in the PFES system. </LI> <LI> The PFES system was effective for reducing the disturbance due to tidal events. </LI> </UL> </P>
Sun Xiang,Zhang Bo,Xu Guangjian,Chen Junwen,Shang Yongpeng,Lin Zhiwei,Yu Zhijian,Zheng Jinxin,Bai Bing 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.3
Background: Tigecycline, eravacycline, and omadacycline are recently developed tetracyclines. Susceptibility of microbes to these tetracyclines and their molecular mechanisms have not been well elucidated. We investigated the susceptibility of Moraxella catarrhalis to tigecycline, eravacycline, and omadacycline and its resistance mechanisms against these tetracyclines. Methods: A total of 207 non-duplicate M. catarrhalis isolates were collected from different inpatients. The minimum inhibitory concentrations (MICs) of the tetracyclines were determined by broth microdilution. Tigecycline-, eravacycline-, or omadacycline-resistant isolates were induced under in vitro pressure. The tet genes and mutations in the 16S rRNA was detected by PCR and sequencing. Results: Eravacycline had a lower MIC50 (0.06 mg/L) than tigecycline (0.125 mg/L) or omadacycline (0.125 mg/L) against M. catarrhalis isolates. We found that 136 isolates (65.7%) had the tetB gene, and 15 (7.2%) isolates were positive for tetL; however, their presence was not correlated with high tigecycline, eravacycline, or omadacycline (≥1 mg/L) MICs. Compared with the initial MIC after 160 days of induction, the MICs of tigecycline or eravacycline against three M. catarrhalis isolates increased ≥eight-fold, while those of omadacycline against two M. catarrhalis isolates increased 64-fold. Mutations in the 16S rRNA genes (C1036T and/or G460A) were observed in omadacycline-induced resistant isolates, and increased RR (the genes encoding 16SrRNA (four copies, RR1-RR4) copy number of 16S rRNA genes with mutations was associated with increased resistance to omadacycline. Conclusions: Tigecycline, eravacycline, and omadacycline exhibited robust antimicrobial effects against M. catarrhalis. Mutations in the 16S rRNA genes contributed to omadacycline resistance in M. catarrhalis.