Goldfish cones secrete a two-repeat interphotoreceptor retinoid-binding protein

Vitamin A and fatty acids are critical to photoreceptor structure, function, and development. The transport of these nutrients between the pigment epithelium and neural retina is mediated by interphotoreceptor retinoid-binding protein (IRBP). IRBP, a 133-kDa (human) glycolipoprotein, is the major protein component of the extracellular matrix separating these two cell layers. In amphibians and mammals, IRBP consists of four homologous repeats of about 300 amino acids which form two retinol and four fatty acid-binding sites. Here we show that IRBP in teleosts is a simpler protein composed of only two repeats. Western blot analysis shows that goldfish IRBP is half the size (70 kDa) of IRBP in higher vertebrates. Metabolic labeling studies employing Brefeldin A taken together with in situ hybridization studies and the presence of a signal peptide show that goldfish IRBP is secreted by the cone photoreceptors. The translated amino acid sequence has a calculated molecular weight of 66.7 kDa. The primary structure consists of only two homologous repeats with a similarity score of 52.5%. The last repeats of human and goldfish IRBPs are 69.1% similar with hydrophobic regions being the most similar. These data suggest that two repeats were lost during the evolution of the ray-finned fish (Actinopterygii), or that the IRBP gene duplicated between the emergence of bony fish (Osteichthyes) and amphibians. Acquisition of a multirepeat structure may reflect evolutionary pressure to efficiently transport higher levels of hydrophobic molecules within a finite space. Quadruplication of an ancestral IRBP gene may have been an important event in the evolution of photoreceptors in higher vertebrates. Correspondence to: F. Gonzalez-Fernandez     

Transport of carnosine by mouse intestinal brush-border membrane vesicles

The characteristics of carnosine (beta-alanyl-L-histidine) transport have been studied using purified brush-border membrane vesicles from mouse small intestine. Uptake curves did not exhibit any overshoot phenomena, and were similar under Na+, K+ or choline+ gradient conditions (extravesicular greater than intravesicular). However, uptake of histidine showed an overshoot phenomenon in the presence of a Na+-gradient. There was no detectable hydrolysis of carnosine during 15 min of incubation with membrane vesicles under conditions used for transport experiments. Analysis of intravesicular contents further showed the complete absence of the constituent free amino acids of carnosine, and indicates that intact carnosine is transported. Studies on the effect of concentration on peptide uptake revealed that transport occurred by a saturable process conforming to Michaelis-Menten kinetics with a Km of 9.6 +/- 1.4 mM and a Vmax of 2.9 +/- 0.2 nmol/mg protein per 0.4 min. Uptake of carnosine was inhibited by both di- and tripeptides with a maximum inhibition of 68% by glycyl-L-leucyltyrosine. These results clearly demonstrate that carnosine is transported intact by a carrier-mediated, Na+-independent process.     

Evaluation of Medium Components by Plackett-Burman Statistical Design for Lipase Production by Candida rugosa and Kinetic Modeling

Lipase production by Candida rugosa was carried out in submerged fermentation. Plackett-Burman statistical experimental design was applied to evaluate the fermentation medium components. The effect of twelve medium components was studied in sixteen experimental trials. Glucose, olive oil, peptone and FeCl3?6H2O were found to have more significance on lipase production by Candida rugosa. Maximum lipase activity of 3.8 u mL-1 was obtained at 50 h of fermentation period. The fermentation was carried out at optimized temperature of 30oC, initial pH of 6.8 and shaking speed of 120 r/min. Unstructured kinetic models were used to simulate the experimental data. Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were found suitable to efficiently predict the cell mass, lipase production and glucose consumption respectively with high determination coefficient(R2). From the estimated values of the Luedeking-Piret kinetic model parameters, α and β, it was found that the lipase production by Candida rugosa is growth associated.     

Impact of Histone H4 Lysine 20 Methylation on 53BP1 Responses to Chromosomal Double Strand Breaks

Recruitment of 53BP1 to chromatin flanking double strand breaks (DSBs) requires γH2AX/MDC1/RNF8-dependent ubiquitination of chromatin and interaction of 53BP1 with histone H4 methylated on lysine 20 (H4K20me). Several histone methyltransferases have been implicated in 53BP1 recruitment, but their quantitative contributions to the 53BP1 response are unclear. We have developed a multi-photon laser (MPL) system to target DSBs to subfemtoliter nuclear volumes and used this to mathematically model DSB response kinetics of MDC1 and of 53BP1. In contrast to MDC1, which revealed first order kinetics, the 53BP1 MPL-DSB response is best fitted by a Gompertz growth function. The 53BP1 MPL response shows the expected dependency on MDC1 and RNF8. We determined the impact of altered H4K20 methylation on 53BP1 MPL response kinetics in mouse embryonic fibroblasts (MEFs) lacking key H4K20 histone methyltransferases. This revealed no major requirement for the known H4K20 dimethylases Suv4-20h1 and Suv4-20h2 in 53BP1 recruitment or DSB repair function, but a key role for the H4K20 monomethylase, PR-SET7. The histone methyltransferase MMSET/WHSC1 has recently been implicated in 53BP1 DSB recruitment. We found that WHSC1 homozygous mutant MEFs reveal an alteration in balance of H4K20 methylation patterns; however, 53BP1 DSB responses in these cells appear normal.     

Characterization of Changes due to pH Variations in Beta Peptide (25–35) Leading to Alzheimer’s Disease

International Journal of Peptide Research and Therapeutics - The effect of various concentrations of amyloid beta peptide (ABP) in different pH (pH 2, 6, 7, 8, 10) in aging at different time...     

Length-weight relationship of six demersal fish species from Gulf of Mannar,Bay of Bengal,Eastern Indian Ocean

Length-weight relationship (LWR) parameters were analysed for six demersal finfish species from the Gulf of Mannar coast, Bay of Bengal. Fishes were sampled monthly from the landings of trawlers operated along the coast of Tuticorin and Rameshwaram with a cod-end mesh size of 35 mm at the depth of 60–80 m. Fish specimens were sampled by measuring the total length (TL) and total weight (TW) with precision to 0.1 cm and 0.1 g respectively. The present study also recorded a new maximum total length for Engyprosopon macrolepis, Torquigener brevipinnis and Leiognathus brevirostris.     

Molecular Dynamic Simulation Reveals Damaging Impact of RAC1 F28L Mutation in the Switch I Region

Ras-related C3 botulinum toxin substrate 1 (RAC1) is a plasma membrane-associated small GTPase which cycles between the active GTP-bound and inactive GDP-bound states. There is wide range of evidences indicating its active participation in inducing cancer-associated phenotypes. RAC1 F28L mutation (RAC^F28L) is a fast recycling mutation which has been implicated in several cancer associated cases. In this work we have performed molecular docking and molecular dynamics simulation (~0.3 μs) to investigate the conformational changes occurring in the mutant protein. The RMSD, RMSF and NHbonds results strongly suggested that the loss of native conformation in the Switch I region in RAC1 mutant protein could be the reason behind its oncogenic transformation. The overall results suggested that the mutant protein attained compact conformation as compared to the native. The major impact of mutation was observed in the Switch I region which might be the crucial reason behind the loss of interaction between the guanine ring and F28 residue.     

Analytical Expressions for the Steady-State Concentrations of Glucose, Oxygen and Gluconic Acid in a Composite Membrane for Closed-Loop Insulin Delivery

The mathematical model of Abdekhodaie and Wu (J Membr Sci 335:21–31, 2009) of glucose-responsive composite membranes for closed-loop insulin delivery is discussed. The glucose composite membrane contains nanoparticles of an anionic polymer, glucose oxidase and catalase embedded in a hydrophobic polymer. The model involves the system of nonlinear steady-state reaction–diffusion equations. Analytical expressions for the concentration of glucose, oxygen and gluconic acid are derived from these equations using the Adomian decomposition method. A comparison of the analytical approximation and numerical simulation is also presented. An agreement between analytical expressions and numerical results is observed.     

Restorative and synergistic efficacy of Kalpaamruthaa, a modified Siddha preparation, on an altered antioxidant status in adjuvant induced arthritic rat model

BACKGROUND: Rheumatoid arthritis (RA) is a prevalent and debilitating disease that affects the joints. Infiltration of blood-derived cells in the affected joints upon activation generate reactive oxygen/nitrogen species, resulting in an oxidative stress. One approach to counteract this oxidative stress is the use of antioxidants as therapeutic agents. OBJECTIVES: Kalpaamruthaa (KA), a modified indigenous Siddha preparation constituting Semecarpus anacardium nut milk extract (SA), Emblica officinalis (EO) and honey was evaluated for its synergistic antioxidant potential in adjuvant induced arthritic rats than sole SA treatment. MATERIALS AND METHODS: Levels/activities of reactive oxygen species (ROS)/reactive nitrogen species (RNS), myeloperoxidase, lipid peroxide and enzymic and non-enzymic antioxidants were determined in control, arthritis induced, SA and KA treated (150 mg/kg b.wt.) animals. RESULTS AND CONCLUSION: The levels/activities of ROS/RNS, myeloperoxidase and lipid peroxide were increased significantly (p<0.05) and the activities of enzymic and non-enzymic antioxidants were in turn decreased in arthritic rats, whereas these changes were reverted to near normal levels upon SA and KA treatment. KA showed an enhanced antioxidant potential than sole treatment of SA in adjuvant induced arthritic rats. KA via enhancing the antioxidant status in adjuvant induced arthritic rats than sole SA treatment proves to be an important therapeutic modality in the management of RA and thereby instituting the role of oxidative stress in the clinical manifestation of the disease RA. The profound antioxidant efficacy of KA than SA alone might be due to the synergistic action of the polyphenols such as flavonoids, tannins and other compounds such as vitamin C and hydroxycinnamates present in KA.