Are Rod Outer Segment ATP-ase and ATP-Synthase Activity Expression of the Same Protein?

Vertebrate retinal rod outer segments (OS) consist of a stack of disks surrounded by the plasma membrane, where phototransduction takes place. Energetic metabolism in rod OS remains obscure. Literature described a so-called Mg²⁺-dependent ATPase activity, while our previous results demonstrated the presence of oxidative phosphorylation (OXPHOS) in OS, sustained by an ATP synthetic activity. Here we propose that the OS ATPase and ATP synthase are the expression of the same protein, i.e., of F₁F_o-ATP synthase. Imaging on bovine retinal sections showed that some OXPHOS proteins are expressed in the OS. Biochemical data on bovine purified rod OS, characterized for purity, show an ATP synthase activity, inhibited by classical F₁F_o-ATP synthase inhibitors. Moreover, OS possess a pH-dependent ATP hydrolysis, inhibited by pH values below 7, suggestive of the functioning of the inhibitor of F1 (IF1) protein. WB confirmed the presence of IF1 in OS, substantiating the expression of F₁F_o ATP synthase in OS. Data suggest that the OS F₁Fo ATP synthase is able to hydrolyze or synthesize ATP, depending on in vitro or in vivo conditions and that the role of IF1 would be pivotal in the prevention of the reversal of ATP synthase in OS, for example during hypoxia, granting photoreceptor survival.     

Growth and photosynthetic responses of field-grown sweetgum (Liquidambar styraciflua; Hamamelidaceae) seedlings to UV-B radiation

Very few studies have evaluated the effects of UV-B radiation on trees. especially deciduous species. In this study we evaluate the effects of supplemental UV-B radiation on the growth and photosynthetic capacity of sweetgum (Liquidambar styraciflua L.). Sweetgum seedlings were grown for 2 years in the field under either ambient or supplemental UV-B radiation. Artificial UV-B radiation was supplied by fluorescent lamps at a maximum daily supplementation of either 3.1 or 5.0 kJ of biologically effective UV-B radiation. Over the 2-year period, supplemental UV-B radiation had little effect on total plant biomass or photosynthetic capacity. However, subtle changes in leaf physiology, carbon allocation, and growth were observed. Supplemental UV-B radiation reduced photosynthetic capacity only during the first year, while leaf area and biomass were reduced in the second year. Alterations in carbon allocation included an increase in branch number and root to shoot ratio. While these data do not indicate that the productivity of sweetgum would likely be compromised by an increase in solar UV-B radiation, they do suggest that the UV-B portion of the solar spectrum contributes to the regulation of sweetgum growth and development. Therefore the possibility of significant consequences to sweetgum due to possible increases in UV-B radiation cannot be ruled out.     

Structural comparison of the haemoglobin components of the armoured catfish Pterygoplichthys pardalis. Evolutionary considerations.

Amino acid analyses and peptide mapping were performed for the four main haemoglobins from the armoured catfish Pterygoplichthys pardalis; component I, which is functionally distinct from the others, is structurally unique, whereas components II, III and IV, functionally indistinguishable, are closely related in structure. Compositional difference indices are calculated for the four components and for the two major haemoglobins from the trout Salmo irideus, and the results are discussed in terms of structural relationships and evolutionary history of fish haemoglobins.     

Disposable orbitally shaken TubeSpin bioreactor 600 for Sf9 cell cultivation in suspension

Disposable orbitally shaken TubeSpin bioreactor 600 tubes (TS600s) were recently developed for the bench-scale cultivation of animal cells in suspension. Here we compared batch cultures of Sf9 insect cells in TS600s, spinner flasks, and shake flasks. Superior cell growth was observed in TS600s and shake flasks as compared with spinner flasks, and more favorable oxygen-enriched cell culture conditions were observed in TS600s as compared with either spinner or shake flasks. The results demonstrated the suitability of TS600s as a disposable vessel for the cultivation of Sf9 cells in suspension.     

Genome organization of Bowman–Birk inhibitor in common bean (Phaseolus vulgaris L.)

A BAC library from common bean has been used in order to isolate the entire multigene Bowman–Birk serine protease inhibitor family and to study its genome organization. Using a previously isolated trypsin/chymotrypsin inhibitor nucleotide sequence as probe, two positive BAC clones were identified. The P2B8 BAC clone, of about 135 kbp and containing the complete BBI family, was chosen and partially sequenced. Our results confirm that a small multigene family codes for three double-headed inhibitors named: tc-BBI-1, tc-BBI-2 and et-BBI. They contain the binding loop trypsin/chymotrypsin (tc-BBI-1 and tc-BBI-2) and the elastase/trypsin one (et-BBI), respectively. Genes coding for tc-BBI-1 and et-BBI, were found to be very close to each other and arranged in a head to head fashion. Southern blot hybridisation on genomic DNA digested with PstI enzyme suggests that all three genes are present in a fragment of 19 kbp. Northern blot analyses on RNA isolated from various common bean organs showed that the expression of tc-BBI-1 and et-BBI was restricted to the developing cotyledons. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A bioactive collagen-β tricalcium phosphate scaffold for tissue engineering

Collagen-phosphate composites (COL/β-TCP) are novel materials that have the potential to be used as bone analogues. The aim of our study was to develop a porous bioactive material composed of type I collagen, the main bone protein and tricalcium phosphate, the mineral phase of natural bone, and investigate their in vitro biocompatibility in a human dermal fibroblast culture system. In order to obtain the bioactive materials, type I collagen was isolated from bovine tendon and characterized by physicochemical methods. β-TCP was obtained from calcium carbonate by thermal decomposition at 900 °C temperature. The powder was examined with X-ray diffraction. Two variants of COL/β-TCP scaffolds (P1 and P2) were prepared and examined by scanning electron microscopy. Our results revealed a microporous structure with small white aggregates of β-TCP, non-homogenous scattered in the collagen framework without any preferential orientation. The biocompatibility of the obtained scaffolds was tested by biochemical and histological methods on human fibroblast cultures. Both materials acted as good subtrates for human dermal fibroblast proliferation and migration.     

Hydrocaffeic and p-coumaric acids,natural phenolic compounds,inhibit UV-B damage in WKD human conjunctival cells in vitro and rabbit eye in vivo

This paper studied the effect on UV-B ocular damage of 10µm hydrocaffeic acid (HCAF) alone and as a mixture (MIX) (5µm HCAF+5µm p-coumaric acid). Since ocular UV-B damage is mediated by reactive oxygen species, the aim was to test if HCAF and MIX could reduce oxidation damage in human conjunctival cells (WKD) in vitro and in cornea and sclera of rabbits in vivo. After UVB irradiation (44 J/m²) of WKD cells, 8-oxodG levels in DNA were markedly increased and this effect was attenuated by HCAF and MIX. Rabbit eyes were treated by application of HCAF and MIX drops before UV-B exposure (79 J/m²). Corneal and scleral DNA oxidation damage, xanthine-oxidase (XO) activity and malondialdehyde levels (MDA) in corneal tissue and prostaglandin E₂ (PGE₂) in the aqueous humour were reduced by HCAF alone and in combination with p-coumaric acid, showing their potential as a topical treatment against UV-B damage.