The Satlantic FIRe (Fluorescence Induction and Relaxation) System is the latest advance in bio-optical technology to measure variable chlorophyll fluorescence in photosynthetic organisms.
- Sensitive enough for dilute field samples (down to 0.05 mg/m3 Chl a)
- Comprehensive suite of fluorescence parameters (e.g. Fv/Fm, σPSII, Fv’/Fm’)
- Independently controlled Blue and Green LED excitation
- Rapid, user friendly measurement protocols
- Optional Actinic Light Source for light adapted fluorescence measurements and automated light response curves.
- Optional Fiber Optic Probe for multi channel analysis and measurements on macrophytes and corals.
- Optional Flow-Through Cuvette for software controlled continuous sampling onboard research vessels.
Excitation light source:
blue LED (maximum emission 455 nm, 60 nm bandwidth)
green LED (maximum emission 540 nm, 60 nm bandwidth)
optional wavelengths available.
680 nm and 880 nm
Auto gain ranging, high sensitivity
Programmable 1 μsec – 50 msec
14 bit, 1 MHz
85-250 VAC, 43-63 Hz
0oC to + 40oC
Dimensions (Length x Diameter):
45 x 14 x 49 cm; 17.5 x 5 x 19 inches
How does the FIRe System differ from Pulse Amplitude Modulated (PAM) fluorometer?
The FIRe System measures changes in chlorophyll fluorescence that occur during a short (100 - 400 μs) but intense (> 20,000 μmol photons m-2 s-1) flash of light whereas the PAM approach measures the fluorescence induced by a weak modulated light source while using ‘saturating’ pulses of ~3000 - 10,000 μmol photons m-2 s-1 to modify fluorescence yields.
The FIRe System also fundamentally differs from a PAM in that the FIRe fully reduces the primary electron acceptor, QA, allowing a simultaneous single closure (STF) event of all photosystem II (PSII) reaction centers whereas the PAM technique generates multiple photochemical charge separations (MTF) that fully reduces QA, the secondary acceptor, QB, and plastoquinone (PQ). By lengthening the measuring protocol the FIRe can also yield MTF data.
For a complete discussion on the mechanistic and practical differences between the two techniques see: Suggett, D.J., K. Oxborough, N.R. Baker, H.L. MacIntyre, T.M. Kana, & R.J. Geider. 2003. Fast repetition rate and pulse amplitude modulation chlorophyll a fluorescence measurements for assessment of photosynthesis electron transport in marine phytoplankton. European Journal of Phycology. 38: 371-84.
What do I do if the STF induction curve does not reach a plateau?
If the fluorescence yield does not reach its maximum value (i.e., plateau) by the end of the single turnover flash (STF), increase the STF duration. For example, if you are currently using an STF duration of 80-100 micro-seconds, try increasing it to 120 or 150 micro-seconds.
What is the difference between parameters calculated from the STF and MTF functions?
The in situ FIRe system uses both STF and MTF protocols. STF protocols measure changes in chlorophyll fluorescence that occur during a short (100 - 400 us) but intense (>40,000 umol photons m-2s-1) flash of light whereas the MTF approach measures the fluorescence induced by a weaker modulated pulsed source with an intensity of ~ 3,000 to 10,000 umol photons m-2s-1 to modify fluorescence yields.
The STF approach also fundamentally differs from the MTF approach in that the STF fully reduces the primary electron acceptor, QA, allowing a simultaneous single closure event of all photosystem II (PSII) reaction centers whereas the MTF technique generates multiple photochemical charge separations that fully reduces QA, the secondary acceptor, QB, and plastoquinone (PQ).
So, the STF and MTF Fv/Fm data are different and will show different values, because the techniques used to measure them are different. Most scientists now accept that the STF Fv/Fm values are the most appropriate for use in productivity models. Further more, given that the STF protocol is much shorter than the MTF protocol it is more appropriate for moving waters, which is important in the context of an in-situ system where the water is constantly being flushed through the sample volume.
- Sato-Takabe, Y., K. Hamasaki, and K. Suzuki (2014) Photosynthetic competence of the marine aerobic an oxygenic phototrophic bacterium Roseobacter sp. under organic substrate limitation. Microb. Environ 29 100-103 doi:doi: 10.1264/jsme2.ME13130.
- Sugie, K., H. Endo, K. Suzuki, J. Nishioka, H. Kiyosawa, and T. Yoshimura (2014) Synergistic effects of pCO2 and iron availability on nutrient consumption ratio of the Bering Sea phytoplankton community. Biogoesciences 10 6309-6321 doi:doi: 10.5194/bg-10-6309-2013.
- Sato-Takabe, Y., K. Hamasaki, and K. Suzuki (2013) Photosynthetic characteristics of aerobic anoxygenic phototrophic bacteria Roseobacter and Erythrobacter strains Archiv. Microbiol. 194 331-341
- Levy O., Bubinsky Z., Schneider K., Achituv Y., Zakai D., Gorbunov, M. (2004) Diurnal hysteresis in coral photosynthesis. Marine Ecology Progressive Series, 268 105-117
- Gorbunov, M.Y., Kolber Z.S.,Falkowski, P.G. (1999) Measuring photosynthetic parameters in individual algal cells by Fast Repetition Rate fluorometry. Photosynthesis Research 2: 141-153
- Takao, S., T. Hirawake, G. Hashida, H. Sasaki, H. Hattori, and K. Suzuki (0000) Phytoplankton community composition and photosynthetic physiology in the Australian Sector of the Southern Ocean during austral summer 2010/2011 Polar Biol. (submitted)
The fiber-optic probe is an external FIRe accessory that can be used to measure variable fluorescence for situations in which it is not practical to place individual samples into the FIRe itself. Examples of such situations would be sampling solids, such as leaf surfaces or culture racks where the user has many samples lined up. The Fiber optic probe uses a randomized fiber bundle to ensure that the excitation light field is uniform and that the maximum amount of variable fluorescence is measured.
Actinic Light Source:
It is possible to attach and use an actinic light source (ALS) in order to achieve constant levels of photo-synthetically active radiation (PAR) in the sample cuvette. The actinic light source has two modes for acquiring data, manual PAR acquisition and stepping PAR acquisition.
Flow Through Cuvette:
The FIRe flow through cuvette was designed to enable researchers to sample from a continuous flow water source. It consists of a quartz cuvette mounted in a Delrin housing with stainless steel tubes for inflow and outflow of sample water.