Abstract: An antibiotic susceptibility testing device of gram-negative bacteria, as well as a corresponding method, are discussed. The device has a temperature control unit (including a constant temperature chamber) and a contactless conductivity-based measurement system. Disposable glassy or PVC tubes are used as test vessels for AST. In the performance of AST assay, appropriate kind of liquid medium containing identical amount of target bacterial cells and target antibiotics at different concentrations are loaded into test tubes, following by incubation in the device at a setup temperature. The bacterial growth profile is monitored by collecting the differential values (?C) of conductivity of liquid medium, which depend on the proliferation of viable cells. Outcome of ?C indicates whether the target bacterial cells are completely inhibited by the test antibiotic or not, enabling the user to judge the value of the minimal inhibitory concentration (MIC) simply.

Abstract: Provided is a method of culturing Stichopus japonicus Stichopus japonicus, Marsupenaeus japonicus, Portunus trituberculatus and Ulva lactuca, which belongs to the technical field of mariculture, including the following steps: preparing a pond and laying a substratum for Stichopus japonicus from March 1 to 5; putting the Stichopus japonicus seedlings, and then culturing Ulva lactuca seedlings on April 1; putting Marsupenaeus japonicus seedlings on April 15; putting Portunus trituberculatus juveniles on May 5; harvesting Marsupenaeus japonicus on July 15, and putting Marsupenaeus japonicus seedlings again; harvesting Stichopus japonicus, Marsupenaeus japonicus, Portunus trituberculatus and Ulva lactuca from November 5 to 10. By adopting the method of biological control of predators of Stichopus japonicus, the use of the pesticides and fishery drugs in the culture and pond-cleaning process is reduced, and green and healthy culture, energy saving and environmental protection are realized.

Abstract: The present invention provides a molecular marker C42257 for rapidly identifying genetic sex of Marsupenaeus japonicus and applications thereof. The nucleotide sequence of the molecular marker C42257 is shown in SEQ ID NO:1. The nucleotide sequences of the primer pair of molecular marker C42257 used for detection are C42257F: GGGGGACAA ACAGAGACA (SEQ ID NO: 2) and C42257R: ATCGGGGTGGATTTAGAA (SEQ ID NO: 3), respectively. The molecular marker C42257 is not affected by the tissue specificity of M. japonicus and the environment, and the steps are simple and the results are obvious. The genomic DNA of M. japonicus and the primer pair are subjected to PCR reaction and electrophoresis detection. If a target band appears at 183 bp, it is a female M. japonicus. The molecular marker can also promote the establishment of the seedling breeding technology of all-female or high-female-ratio M. japonicus. Therefore, it has a broad application prospect.

Abstract: A method for analyzing stable isotopes of particulate organic carbon (POC) and nitrogen in seawater using elemental analysis-isotope ratio mass spectrometry (EA-IRMS), including: using a glass fiber filter membrane to filter a collected water sample and then filter 100 ml of distilled water; subjecting a resulting membrane sample to acidification; and subjecting an acidified membrane sample to EA-IRMS analysis on a machine, where an oxygen addition time is set to 80 s and a combustion tube temperature is set to 700° C. for an elemental analyzer, and a trap current is set to 300 ?A to 400 ?A for an isotope ratio mass spectrometer. The method of the present disclosure can reduce a detection cost and improve the data accuracy and work efficiency.