Konkuk University 3 articles published in JoVE Environment Cortisol Extraction from Sturgeon Fin and Jawbone Matrices Jalil Ghassemi Nejad1,2, Mohammad Ataallahi1, Mohammad H. Salmanzadeh3, Kyung T. Park3, Hong G. Lee2,4, Alireza Shoae5, Atieh Rahimi6, Kyung I. Sung1, Kyu H. Park1 1College of Animal Life Sciences, Kangwon National University, 2Team of An Educational Program for Specialists in Global Animal Science, Brain Korea 21 Plus Project, Konkuk University, 3Persian Gesture, 4Department of Animal Science and Technology, College of Animal Bioscience and Technology, Konkuk University, 5Department of Animal Science, Animal Physiology, AgResearch, 6Faculty of Agriculture, Animal Science Department, Ferdowsi University of Mashhad In this study, we present a protocol for cortisol extraction from the fin and jawbone of sturgeon species. Fin and jawbone cortisol levels were further examined by comparing two washing solvents followed by ELISA assays. This study piloted the feasibility of jawbone cortisol as a novel stress indicator. Biochemistry Measurement of Ion Concentration in the Unstirred Boundary Layer with Open Patch-Clamp Pipette: Implications in Control of Ion Channels by Fluid Flow Jae Gon Kim*1, Sang Woong Park*2, Kyung Chul Shin1, Bokyung Kim1, Doyoung Byun3, Young Min Bae1 1Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, 2Department of Emergency Medical Services, Eulji University, 3Department of Mechanical Engineering, Sungkyunkwan University Mechanosensitive ion channels are often studied in terms of fluid flow/shear force sensitivity with patch-clamp recording. However, depending on the experimental protocol, the outcome on fluid flow-regulations of ion channels can be erroneous. Here, we provide methods for preventing and correcting such errors with a theoretical basis. Chemistry Immobilization of Multi-biocatalysts in Alginate Beads for Cofactor Regeneration and Improved Reusability Hui Gao1, Eshita Khera2, Jung-Kul Lee1, Fei Wen2 1Department of Chemical Engineering, Konkuk University, 2Department of Chemical Engineering, University of Michigan Presented is the protocol for co-immobilizing whole-cell biocatalysts for cofactor regeneration and improved reusability, using the production of L-xylulose as an example. The cofactor regeneration is achieved by coupling two Escherichia coli strains expressing functionally complementary enzymes; the whole-cell biocatalyst immobilization is achieved by cell encapsulation in calcium alginate beads.