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Development and Evaluation of a Ground CO2 Measurement System

Mon, 01 Dec 2025 00:00:00 GMT

Title: Development and Evaluation of a Ground CO2 Measurement System Authors: Park, Keunbo Abstract: 지구 평균 기온 상승은 산업화 이후 증가한 온실가스 배출과 밀접한 관련이 있으며, 특히 고위도 지역의 영구동토층 해빙은 저장된 유기탄소의 대기 방출을 통해 지구가열화를 가속할 잠재성이 크다. 이에 따라 동토？대기 경계면에서 발생하는 CO2 교환 특성을 정량적으로 규명하기 위한 정밀 현장 관측 기술의 필요성이 증대되고 있다. 본 연구에서는 이러한 과학적·정책적 요구에 대응하여 비분산적외선(NDIR) 분광 원리를 기반으로 한 정밀 CO2 측정시스템을 설계·제작하였다. 측정 시스템은 MCU 기반 제어기, 실시간 보정 알고리즘, 통신 모듈 및 GUI 기반 시각화 시스템을 통합하여 안정적으로 운용 가능하도록 구현하였다. 개발된 측정 시스템은 표준가스를 이용한 영점 및 스팬 교정 기능을 포함하며, 이동평균 및 적응형 필터 기반 신호 처리, 비정상 신호 제거 알고리즘, 실시간 데이터 로깅 기능을 적용하였다. 성능 검증은 0.600 ppm, 429.860 ppm, 953.550 ppm의 CO2 표준가스를 이용해 정확도, 정밀도, 응답시간, 선형성 및 영점 안정성을 평가하는 방식으로 수행하였다. 실험 결과, 모든 농도 구간에서 측정값은 표준가스 농도와 일치하는 수준을 유지하였으며, 정확도 ±1% 이내, 정밀도 0.560 이하, 장기 영점 드리프트를 포함하여 상용되고 있는 정밀 측정 시스템(LI-COR LI-7810)와 동등한 성능을 확보하였다. 또한 1:1 비교 분석에서 두 장비의 측정값은 높은 상관성을 보이며 우수한 선형성을 나타냈다.

Draft genome and de novo transcriptome assembly of the Antarctic marine flatworm Obrimoposthia wandeli

Mon, 01 Dec 2025 00:00:00 GMT

Title: Draft genome and de novo transcriptome assembly of the Antarctic marine flatworm Obrimoposthia wandeli Authors: Shin, Seung Chul; Kim, Sanghee Abstract: Objectives Obrimoposthia wandeli is the most abundant marine planarian in the intertidal zone of the maritime Antarctic region and is presumed to have adapted to the extreme conditions of the Southern Ocean. However, genomic studies on marine flatworms remain extremely limited, with only one marine planarian genome currently available in public databases. We present the first draft genome and de novo transcriptome assembly of O. wandeli from Antarctica, providing a valuable genomic resource for the study of flatworm biology and environmental adaptation under harsh environments. Data description We sequenced the genome and transcriptome of O. wandeli collected near King Sejong Station using Oxford Nanopore long-read, Illumina paired-end, and RNA sequencing. The draft genome assembly spans 1.35 Gb across 6,912 contigs, with an N50 of 343,088 bp and an estimated 48,310 predicted genes. The assembly showed Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness scores of 80.2% (genome) and 80.8% (proteins). The de novo transcriptome assembly identified 26,169 non-redundant transcripts, with a BUSCO completeness of 93.1%. These genomic and transcriptomic datasets represent the first Antarctic marine planarian reference and provide a valuable resource for studying marine flatworm genomics.

A CALB-like Cold-Active Lipolytic Enzyme from Pseudonocardia antarctica: Expression, Biochemical Characterization, and AlphaFold-Guided Dynamics

Mon, 01 Dec 2025 00:00:00 GMT

Title: A CALB-like Cold-Active Lipolytic Enzyme from Pseudonocardia antarctica: Expression, Biochemical Characterization, and AlphaFold-Guided Dynamics Authors: Liu Lixiao; Do, Hackwon; Kim Jong-Oh; Lee, Jun Hyuck; Kim Hak Jun Abstract: Cold-active lipolytic enzymes enable low-temperature biocatalysis, but remain underexplored in Antarctic actinomycetes. Here, we report the discovery and first-step characterization of a CALB-like cold-active lipolytic enzyme (PanLip) from Pseudonocardia antarctica. Sequence and structure analyses revealed a canonical alpha/beta-hydrolase fold with a conserved Ser-Asp-His triad and short helical elements around the pocket reminiscent of CALB's alpha 5/alpha 10 lid. Mature PanLip was expressed primarily as inclusion bodies in E. coli; an N-terminally truncation (PanLip Delta N) improved solubility and PanLip Delta N was purified by Ni-NTA. Far-UV CD confirmed a folded alpha/beta architecture. PanLip Delta N favored short-chain substrates (p-NPA, kcat/KM = 2.4 x 105 M-1s-1) but also showed measurable hydrolytic activity toward natural triglycerides, consistently with a lipase-family esterase. The enzyme showed an activity optimum near 25 degrees C and pH 8.0. The enzyme tolerated low salt (maximal at 0.1 M NaCl), mild glycerol, and selected organic solvents (notably n-hexane), but was inhibited by high salt, Triton X-100, and SDS. AlphaFold predicted high local confidence for the catalytic core; DALI placed PanLip closest to fungal lipases (AFLB/CALB). Temperature-series MD and CABS-flex indicated enhanced surface breathing and flexible segments adjacent to the active site-including a region topologically matching CALB alpha 10-supporting a flexibility-assisted access mechanism at low temperature. Structure-based MSAs did not support a cold adaptation role for the reported VDLPGRS motif. Taken together, these findings position PanLip as a promising cold-active catalyst with CALB-like access control and potential for low-temperature biocatalysis.

Early aculiferan diversification shaped by Ægir-Iapetus palaeogeography: Insights from North Greenland (Cambrian Series 2, Stage 4)

Mon, 01 Dec 2025 00:00:00 GMT

Title: Early aculiferan diversification shaped by Ægir-Iapetus palaeogeography: Insights from North Greenland (Cambrian Series 2, Stage 4) Authors: Oh, Yeongju; Park, Tae-Yoon S.; Peel John S. Abstract: Aculifera, comprising Polyplacophora (chitons) and Aplacophora, is one of two major molluscan clades, characterised by a scleritome of mineralised sclerites or plates. Their early evolutionary history is poorly understood due to sparse fossil records bridging possible Terreneuvian (early Cambrian) stem-group taxa and Furongian (late Cambrian) chiton-like articulated representatives. Here, we describe seven species in five genera from the Aftenstjernes & oslash; Formation (Cambrian Series 2, Stage 4) of North Greenland, including a second species, Qaleruaqia bronlundensis sp. nov., of the oldest paleoloricate, Qaleruaqia sp.; the sachitid Hippopharangites groenlandicus, Hippopharangites? sp.; a possible intermediate plate of a chiton-like scleritome, Avannaplax midsommersoensis gen. et sp. nov.; and possible aculiferans Ocruranus? kangerluk and Xianfengella yatesi. Morphological comparisons of the North Greenland assemblage reveal strong affinities with Terreneuvian taxa, including maikhanellids and the Ocruranus-Eohalobia group, supporting their interpretation as stem-group aculiferans. A palaeobiogeographic analysis using 650 global occurrences of Cambro-Ordovician taxa shows that the AE gir Ocean as a principal dispersal corridor for early diversification of aculifera. During the Terreneuvian, aculiferans were widespread along AE gir margins but rare in Laurentia, likely due to isolation by the Iapetus Ocean. From Cambrian Series 2 onward, increased connectivity and expanded low-latitude carbonate platforms fostered diversification in eastern Laurentia, including North Greenland. This assemblage from North Greenland bridges a critical spatio-temporal and morphological gap between the earliest Cambrian taxa and Furongian paleoloricates, offering new insight into aculiferan diversification and palaeobiogeography.