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We developed and tested a high-pressure optical chamber system for cultivation and microscopic observation of deep-sea organisms. The system is composed of an optical chamber, a highpressure pump, a pressure sensor and a microscope. The chamber has an observation cavity, 2 cultivation cavities and 2 sapphire windows. The pump is employed for perfusion of culture medium and for increasing the pressure. The pressure sensor monitors the pressure in the chamber. The microscope is used for observing samples through the sapphire windows. In the future, the optical chamber system could be used alone for short-term research or be connected to a large high-pressure vessel to create a flow-through system for long-term research. Using the system, the swimming activity of Bosmina longirostris (Branchiopoda: Cladocera) was observed at different pressures. Swimming activity increased with increasing compression up to 30 MPa. During decompression, this activity reappeared when pressure decreased to 45 MPa and increased with further decreasing pressure. KEY WORDS: Optical chamber system · Real-time · Microscopic observation · PlanktonResale or republication not permitted without written consent of the publisher Aquat Biol 11: 157-162, 2010 To overcome these drawbacks, we developed a high-pressure optical chamber system specifically used for cultivation and microscopic observation of organisms ranging from 100 to 1000 µm in size. The high-pressure chamber is made of titanium, which has been proven to be an excellent biocompatible material and can be used under high pressure up to 60 MPa (6000 m depth in the deep sea). The chamber can either be used alone for short-term research or as part of a flow-through system by connection with a large vessel. A flow-through system could maintain water chemistry conditions in the pressure chamber for longterm observation without decreasing the pressure. We examined the stability of the pressure chamber system and successfully made real-time observations of plankton under different pressures. MATERIALS AND METHODSOptical chamber system. The highhydrostatic-pressure optical chamber system is mainly composed of an optical pressure chamber, a microscope, a pressure pump and a pressure sensor. The temperature is controlled by a water bath.High-hydrostatic-pressure optical chamber: The optical chamber (Fig. 1) is made of titanium, an excellent material for highpressure research. The chamber is in the form of a rectangular box (180 × 44 × 38 mm), which has an observation cavity and 2 cultivation cavities. The maximum pressure in the chamber is 60 MPa.The observation cavity (Fig. 2a) is 13 mm in diameter and provides 2 opposite optical windows for real-time microscopic observation. The optical window (Fig. 2b) is made of sapphire, 16 mm in diameter and 8 mm in thickness. It provides clear images with common microscopes and excellent biocompatibility. A fluorine rubber O-ring (16 mm diameter, 1.8 mm thick) is used to seal the window. The sapphire window is tightened by a compression cove...

The effect of Cu2+, Ca2+, Mg2+and Zn2+ on the interaction between nitroglycerin and bovine serum albumin was investigated. The bimolecular quenching rate constant, the Stern-Volmer quenching constant, the binding constants and the number of binding sites were calculated in the absence and presence of Cu2+, Ca2+, Mg2+and Zn2+. The quenching constants of nitroglycerin to bovine serum albumin were increased in the presence of metal ions. Static quenching mechanism was also confirmed. The binding constants of nitroglycerin to bovine serum albumin were influenced by different metal ions. The enthalpy change, free energy chang, entropy change and the distance between the donor and the acceptor at different temperatures were calculated. The results indicated that energy transfer from bovine serum albumin to nitroglycerin occurs with high probability.