In a recent paper (11) we suggested that high state 4 respiration rates in corn mitochondria are linked to energy expenditure in phosphate transport. State 4 respiration was considerably augmented by polycations which served to increase phosphate transport, producing swelling. It seems to be widely accepted that energy-linked ion transport in mitochondria is a process capable of releasing coupled respiration (3,20,21), although it is sometimes pointed out that the stoichiometry is disturbing (3), and that permeant anions are required (20 MATERIALS AND METHODS Mitochondria. Corn mitochondria (Zea mays L., WF9(Tms) X M14) were isolated and assayed as previously described (11). Final suspension of the mitochondria was in the same medium as used for the basic reaction mixture: 200 mm sucrose, 10 mm TES buffer, 1 mm MgSO,, 1 mg/ml bovine serum albumin, adjusted to pH 7.6 with KOH. Mitochondria concentrations were adjusted to approximately 10 mg protein/ml, with protein determinations corrected for the BSA of the suspending medium. Reaction vessels contained 4.4 ml of the basic medium plus 0.1 ml of mitochondria suspension (about 1 mg protein), with additives as indicated in figures and tables. Temperature was 28 or 29 C. Recordings of 02 consumption and percentage of transmission were as previously described (1 1). ATP Measurements. Two-ml samples were withdrawn from the reaction vessel in the spectrophotometer before and 1 min after adding 300 nmoles ADP. In determination of adenylate kinase blanks the same procedure was followed, but initial additions were made of 20 /M rotenone, 3 tM antimycin A, and 20 ,ug oligomycin, and addition of NADH was omitted. The samples were added to 3 ml of 20 mm glycine buffer, pH 7.7, in a boiling water bath. After 15 min the tubes were cooled in an ice bath, and the denaturated mitochondria were centrifuged down at 5000g for 10 min. Aliquots of the extract were assayed for ATP by a luciferase assay (15) using an

The steady-state biosynthesis of the photosynthetic membrane (ICM) of Rhodopseudomonas sphaeroides has been reviewed. At moderate light intensities, 500 ft-c, preexisting ICM serves as the insertion matrix for newly synthesized membrane components. Whereas the bulk of the membrane protein, protein-pigment complexes, and pigments are inserted into preexisting ICM throughout the cell cycle, phospholipid is transferred from outside the ICM to the ICM only at the time of cell division. Because the site of cellular phospholipid synthesis is the cytoplasmic membrane, these results infer that despite the physical continuity of cytoplasmic membrane and ICM, there must exist between these membranous domains a "barrier" to the free diffusion of cellular phospholipid. The cyclical alternation in protein to phospholipid ratio of the ICM infers major structural and functional alternations, such as changes in the protein to lipid ratio of the membrane, specific density of the membrane, lipid structure within the membrane, and the rate of cyclic electron flow. When biochemical studies are correlated with detailed electron microscopic investigations we can further conclude that the number of photosynthetic units within the plane of the membrane can vary by nearly a factor of two over the course of the cell cycle. The average physical size of the photosynthetic units is constant for a given light intensity but inversely proportional to light intensity. The distribution of photosynthetic unit size classes within the membrane can be interpreted as suggesting that the "core" of the photosynthetic unit (reaction center plus fixed antenna complex) is inserted into the membrane coordinately as a structural entity. The variable antenna complex is, on the other hand, inserted independent of the "core" and randomly associates with both old and new core complexes. Finally, we conclude that there is substantial substructure to te distribution of photosynthetic units within the ICM, ie, they are highly ordered and exist in a defined spatial orientation to one another.

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Solubilization at 75 degrees C of Rhodopseudomonas sphaeroides chromatophores in the presence of sodium dodecyl sulfate (SDS) and 2-mercaptoethanol (beta-ME) resulted in the selective absence of reaction center B and C polypeptides from SDS-polyacrylamide gel electrophoresis profiles. A newly identified, chromatophore-specific polypeptide, with a mass of 35.2 kdaltons, was also missing under these conditions of chromatophore solubilization. Solubilization at 27 degrees C in the presence of SDS and beta-ME also resulted in the disappearance of these three polypeptides, but at much slower rates. Disappearance of either endogenous or exogenously supplied reaction center polypeptides B and C during SDS solubilization of whole chromatophores at either 27 or 75 degrees C was shown to be entirely dependent upon the presence of beta-ME. After chromatophore solubilization in the presence of beta-ME and subsequent SDS-polyacrylamide gel electrophoresis, exogenously added reaction centers B and C could be localized in a complex of no less than 100 to 200 kdaltons. However, the precise size of the complex was influenced by the stoichiometry of the reacting components. The disappearance of the 35.2-kdalton polypeptide was neither dependent upon the presence of beta-ME nor dependent upon the presence of any additional chromatophore polypeptides. The 35.2-kdalton polypeptide underwent a heat-induced oligomerization to yield several high-molecular-weight species.

This document introduces a novel access control architecture for publicly accessible wireless overlay networks. The architecture is designed to address the problems of ubiquitous Internet service provisioning within the city of Lancaster. The proposed access control mechanism is based on the concepts of secure user authentication, packet marking, and network-level packet filtering. The novelty of the architecture lies in its use of micro-cellular layer three networks to acquire fine grained access control in a link independent manner. The paper describes the concepts behind the access control architecture and demonstrates to what extent it addresses the security, performance and extensibility concerns of public access packet switched wireless networks.