Fluorescence and photoacoustic spectroscopy of immobilized thylakoids

Abstract

The O(2) evolution activity of immobilized chloroplast membranes in different environments (albumin-glutaraldehyde matrix, urethane polymer and alginate beads) is presented. As previously shown, the stability of photosystem II (PS II) of lettuce thylakoids appears to be increased by the immobilization process. For understanding such stability, some spectral investigations have been made about the energy distribution between the immobilized photosystems. The low-temperature (77 K) fluorescence emission and photoacoustic spectroscopy are well adapted to solid particle studies. Especially, it has been shown that the fluorescence ratio (F(735)/F(695)) and photoacoustic ratio (PA(676)/PA(440)) are good indicators of the functional level of native and immobilized thylakoids. Such ratios are also given after storage and after continuous illumination conditions. Some results about the role played by glutaraldehyde (in the case of albumin-glutar-aldehyde matrix) in the stabilization process are also reported.

Photosynthesis by Intact Isolated Chloroplasts on Solid Support

“…Here we shall describe attempts we have made to trap CSS', in order to be able to investigate their function under conditions more closely resembling those in leaves. In this way, the ratio of chloroplasts to suspending medium could be increased 100-fold.In the past, several attempts have been made to immobilize chloroplasts for the purpose of stabilization, but these attempts were restricted, with one exception (7), to the preservation and measurements of electron transport, with complete loss ofcapacity for carbon assimilation (1,(8)(9)(10)12). In the present work, intact CSS assimilated CO2 and evolved 02.…”

“…In the past, several attempts have been made to immobilize chloroplasts for the purpose of stabilization, but these attempts were restricted, with one exception (7), to the preservation and measurements of electron transport, with complete loss ofcapacity for carbon assimilation (1,(8)(9)(10)12 Chloroplast Isolation. Intact isolated spinach chloroplasts were prepared using a low ionic strength medium, as previously described for peas (3).…”

Plant tissue-and photosynthesis-based biosensors

“…The incorporation of several types of photosystem II specific artificial electron acceptors as electroactive mediators allows to maximize the photosynthetic activity. The most commonly used mediator is potassium ferricyanide (Cocquempot et al, 1981;Park et al, 1991;Mishra and Sabat, 1995) but benzoquinone derivatives, such as parabenzoquinone (Thomasset et al, 1983;Rouillon et al, 1995a) or 2,5-dichlorobenzoquinone (DCBQ) (Loranger and Carpentier, 1994), are also employed to improve the photosynthetic activity.…”

A fast bioassay for phytotoxicity measurements using immobilized photosynthetic membranes

“…31 A variety of immobilization procedures have been developed to stabilize the structure and function of the isolated thylakoid membranes. '4923324 Immobilization in an albumin-glutaraldehyde crosslinked matrix gave a better preservation of the native thylakoid activity than immobilization by several other techniques' 1, 32 and provided good protection against aging and strong illumination .7*8 Furthermore, this type of matrix constitutes a porous network allowing diffusion of artificial electron acceptors and inhibitors to the photosynthetic membranes.'' In this study, the electron transport activity of immobilized and free thylakoid membranes is studied in the presence of several toxic compounds.…”