Preference of Proteomonas sulcata anion channelrhodopsin for NO3− revealed using a pH electrode method

Ion channel proteins are physiologically important molecules in living organisms. Their molecular functions have been investigated using electrophysiological methods, which enable quantitative, precise and advanced measurements and thus require complex instruments and experienced operators. For simpler and easier measurements, we measured the anion transport activity of light-gated anion channelrhodopsins (ACRs) using a pH electrode method, which has already been established for ion pump rhodopsins. Using that method, we successfully measured the anion transport activity and its dependence on the wavelength of light, i.e. its action spectra, and on the anion species, i.e. its selectivity or preference, of several ACRs expressed in yeast cells. In addition, we identified the strong anion transport activity and the preference for NO3− of an ACR from a marine cryptophyte algae Proteomonas sulcata, named PsuACR_353. Such a preference was discovered for the first time in microbial pump- or channel-type rhodopsins. Nitrate is one of the most stable forms of nitrogen and is used as a nitrogen source by most organisms including plants. Therefore, PsuACR_353 may play a role in NO3− transport and might take part in NO3−-related cellular functions in nature. Measurements of a mutant protein revealed that a Thr residue in the 3rd transmembrane helix, which corresponds to Cys102 in GtACR1, contributed to the preference for NO3−. These findings will be helpful to understand the mechanisms of anion transport, selectivity and preference of PsuACR_353.

Preference of Proteomonas Sulcata Anion Channelrhodopsin for Nitrate Revealed Using a pH Electrode Method

Ion channel proteins are physiologically important molecules in living organisms. Their molecular functions have been investigated using electrophysiological methods, which enable quantitative, precise and advanced measurements and thus require complex instruments and experienced operators. For simpler and easier measurements, we measured the anion transport activity of light-gated anion channelrhodopsins (ACRs) using a pH electrode method, which has already been established for ion pump rhodopsins. Using that method, we successfully measured the anion transport activity and its dependence on the wavelength of light, i.e. its action spectra, and on the anion species, i.e. its selectivity or preference, of several ACRs expressed in yeast cells. In addition, we identified the strong anion transport activity and the preference for NO3- of an ACR from a marine cryptophyte algae Proteomonas sulcata, named PsuACR_353. Such a preference was discovered for the first time in microbial pump- or channel-type rhodopsins. Nitrate is one of the most stable forms of nitrogen and is used as a nitrogen source by most organisms including plants. Therefore, PsuACR_353 may play a role in NO3- transport and might take part in NO3--related cellular functions in nature. Measurements of a mutant protein revealed that a Thr residue in the 3rd transmembrane helix, which corresponds to Cys102 in GtACR1, contributed to the preference for NO3-. These findings will be helpful to understand the mechanisms of anion transport, selectivity and preference of PsuACR_353.

Special Issue “Advances in Artificial and Biological Membranes: Mechanisms of Ionic Sensitivity, Ion-Sensor Designs, and Applications for Ion Measurement”

Ion sensors, conventionally known as ion-selective membrane electrodes, were devised 100 years ago with the invention of a pH electrode with a glass membrane (in 1906 Cremer, in 1909 Haber and Klemensiewicz) [...]

Sistem Pemantauan Kualitas Air Sungai di Kawasan Industri Berbasis WSN dan IoT

Air telah menjadi salah satu kebutuhan utama manusia, khususnya pada aliran air sungai yang terhubung dengan limbah pembuangan industri. Persyaratan kualitas air yang berhubungan langsung dengan kesehatan diantaranya kadar pH, kekeruhan, dan suhu air. Penelitian ini bertujuan untuk merancang suatu sistem pemantauan kualitas air sungai berbasis teknologi Wireless Sensor Network (WSN) dan Internet of Things (IoT). Sistem pemantauan dirancang menggunakan sensor pH electrode probe untuk mengukur pH, GE turbidity SKU SEN0189 untuk mengukur kekeruhan, dan DS18B20 untuk mengukur suhu air. Perancangan sistem WSN menggunakan NRF24L01 untuk mengirimkan data sensor dari tiga node ke base sebagai pusat data, sedangkan perancangan IoT menggunakan ESP8266 sebagai pengirim data ke database melalui jaringan internet dan ditampilkan pada halaman website. Berdasarkan hasil pengujian, sistem pemantauan dapat bekerja dengan baik pada aliran sungai saat cuaca dan kondisi sungai yang normal dengan jangka waktu maksimal 3 jam.

Monitor application of multi-electrochemical sensor in extracting bromine from seawater

In this paper, a set of online measurement devices of multi-electrochemical sensor was investigated. Combined with industrial distributed control system, it was first applied in extracting bromine from seawater to realize the real-time adjustment of production process parameters. In the process of extracting bromine from seawater, the pH value of acidified raw brine, the addition amount of Cl 2 in the oxidation stage and the addition amount of SO 2 in the absorption stage are key parameters to control the whole production process. The multi-electrochemical sensor realized a rapid and high-throughput detection of the above parameters by integrating an all-solid-stage bromide ion selective electrode (Br-ISE), Eh electrode and pH electrode. The Br-ISE and the pH electrode were self-developed electrodes and the Pt electrode was Eh electrode. The pH electrode was used to control the addition amount of H 2 SO 4 during the acidification of the brine. The Eh electrode was used to control the addition amount of Cl 2 during the oxidation stage and the addition amount of SO 2 during the absorption stage. The Br-ISE was used to monitor the Br − concentration change in the raw brine. Results showed the optimum range of Eh in the oxidation stage and absorption stage of brine were 950–1000 mV and 580–610 mV, respectively. The application of multi-electrochemical sensor in industrial bromine production can realize real-time control of material addition and save the cost of production.

ONLINE MONITORING KUALITAS AIR WADUK BERBASIS THINGSPEAK

Waduk merupakan salah satu sarana penampungan sementara sumber air. Sumber air memiliki peranan yang penting bagi mahluk hidup dalam memenuhi kebutuhannya. Akan tetapi, kualitas air perlu dijaga untuk mengurangi risiko pencemaran yang berdampak pada lingkungan hidup. Penelitian ini bertujuan merancang bangun prototipe untuk monitoring kualitas air secara online pada sebuah waduk. Parameter ukur untuk menentukan kualitas air yakni deteksi tingkat keasaman (pH), kekeruhan (NTU) dan suhu (OC) pada air waduk. Prototipe terpasang sensor pH electrode, sensor turbidity dan sensor suhu (DS18B20). Hasil pembacaan data sensor disimpan pada database Thinkspeak secara real-time. Monitoring kualitas air dapat divisualisasikan pada Smartphone yang telah terpasang aplikasi ThingView. Parameter uji sistem dilakukan dengan pada pagi hari, siang hari, dan malam hari. Validasi sistem dilakukan dengan membandingkan parameter hasil ukur dengan alat ukur digital. Pengujian sistem diperoleh pada malam hari (pH 6,4) level keasaman lebih rendah, pada siang hari (17,8 NTU) level kekeruhan lebih rendah, dan pada malam hari (22OC) suhu lebih rendah. Selain itu, performa sistem telah menunjukkan prediksi kesalahan ukur yang minimum dari hasil perbandingan pengukuran.

A platinum oxide-based microvoltammetric pH electrode suitable for physiological investigations

Herein, we report the in vitro investigation of a physiologically relevant Pt oxide-based microvoltammetric pH electrode.