The Insulin Receptor Adaptor IRS2 is an APC/C Substrate That Promotes Cell Cycle Protein Expression and a Robust Spindle Assembly Checkpoint

1. Download : Download high-res image (48KB)
2. Download : Download full-size image

Highlights

• •Chemical proteomics in G₁ cells treated with small molecule APC/C inhibitors reveals novel putative APC/C substrates.
• •The insulin receptor adaptor IRS2 is an APC/C substrate that is targeted for degradation by APC/C^Cdh1.
• •Quantitative proteomics in IRS2 knockout cells reveals a deficiency in cell cycle related protein expression.
• •IRS2 promotes a robust spindle assembly checkpoint (SAC) during M-phase.

     

Significant Hydrolysis of Wheat Gliadin by <Emphasis Type="Italic">Bacillus tequilensis</Emphasis> (10bT/HQ223107): a Pilot Study

Peptidase therapy is suggested to be effective to minimize gliadin toxicity in celiac disease (CD). Hence, present study deals with gliadin-hydrolysing peptidases. The efficient peptidase from the Bacillus tequilensis was purified using ammonium sulfate fractionation and preparative electrophoresis. Analysis of in-solution and in-gel hydrolysis of gliadin using one and two-dimensional SDS-PAGE revealed nearly complete hydrolysis of gliadin peptides after 180 min of incubation with B. tequilensis protease. Purified peptidase was found to be stable at acidic (pH 3.5) to neutral (pH 7.2) pH range. The molecular mass and isoelectric point of the peptidase were observed around 29 kDa and 5.2, respectively. The internal protein sequence obtained through mass spectrometric analysis suggested that peptidase might belong to peptidase S9 family known for prolyl-specific peptidases. This study recommends the possible applicability of this peptidase for elimination of immunotoxic gliadin peptides and may prove useful in CD treatment.     

Extraction of Protein Interaction Data: A Comparative Analysis of Methods in Use

Several natural language processing tools, both commercial and freely available, are used to extract protein interactions from publications. Methods used by these tools include pattern matching to dynamic programming with individual recall and precision rates. A methodical survey of these tools, keeping in mind the minimum interaction information a researcher would need, in comparison to manual analysis has not been carried out. We compared data generated using some of the selected NLP tools with manually curated protein interaction data (PathArt and IMaps) to comparatively determine the recall and precision rate. The rates were found to be lower than the published scores when a normalized definition for interaction is considered. Each data point captured wrongly or not picked up by the tool was analyzed. Our evaluation brings forth critical failures of NLP tools and provides pointers for the development of an ideal NLP tool.     

Engineering liposomes of leaf extract of seabuckthorn (SBT) by supercritical carbon dioxide (SCCO2)-mediated process

Seabuckthorn (SBT; Hipphophae rhamnoides) leaf extract obtained by supercritical carbon dioxide (SCCO(2)) using ethanol as an entrainer, containing mainly flavanoids as bioactive principles with antioxidant and antibacterial properties, was used for the preparation of liposomes. Liposomes are promising drug carriers with sustained release because they can enhance the membrane penetration of drugs, deliver the entrapped drugs across cell membranes, and improve extract stability and bioavailability. The aim of the present study was to compare the two different methods of liposome production: the Bangham thin-film method and SCCO(2) gas antisolvent method (SCCO(2) GAS) for the incorporation of SBT leaf extract in terms of particle size, morphology, encapsulation efficiency, antioxidant activity, and thermal stability. Liposomes obtained with the thin-film method were multilamellar vesicles with average particle size (3,740 nm), encapsulation efficiency (14.60%), and particle-size range (1.57-6.0 μm), respectively. On the other hand, liposomes by the SCCO(2) GAS method were nanosized (930 nm) with an improved encapsulation efficiency (28.42%) and narrow range of size distribution (0.48-1.07 μm), respectively. Further, the antioxidant activity of leaf extract of SBT was determined by the 2 diphenyl-1-picrylhydrazyl method and expressed as Trolox equivalents as well as of the intercalated extract in liposomes. The oxidative stability of SBT encapsulated in liposomes was again estimated using differential scanning calorimetry (DSC). Thermal-oxidative decomposition of the samples (i.e., pure liposomes and encapsulated extracts) and the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were also studied by DSC. After encapsulation in liposomes, antioxidant activity proved to be higher than those of the same extracts in pure form.     

A response surface methodological study on prediction of glucosylation yields of thiamin using immobilized β-glucosidase

Response surface methodology was used to predict the glucosylation yields of thiamin using immobilized β-glucosidase. A Central Composite Rotatable Design (CCRD) of 32 experiments with immobilized β-glucosidase, thiamin, incubation period, buffer concentration and pH, as five independent variables was employed at five levels. A second-order polynomial equation was developed, the regression coefficient values of which exhibited a R² value of 0.74. Contour plots explained the glucosylation behaviour of the enzyme through a reversal in glucosylation at a cross-over point corresponding to 60% (w/w d-glucose) immobilized β-glucosidase and 0.12 mM buffer concentration at pH 6. The highest conversion yield of 58% obtained experimentally compared well with the predicted yield of 52% under optimum conditions of 40% immobilized β-glucosidase, 0.55 mmol thiamin, 96 h incubation period and 0.16 mM buffer concentration at pH 7. Validation experiments carried out at certain random predictive conditions also showed good correspondence between experimental and predictive yields.     

Napin from Brassica juncea: thermodynamic and structural analysis of stability

The napin from Brassica juncea, oriental mustard, is highly thermostable, proteolysis resistant and allergenic in nature. It consists of two subunits - one small (29 amino acid residues) and one large (86 amino acids residues) - held together by disulfide bonds. The thermal unfolding of napin has been followed by differential scanning calorimetry (DSC) and circular dichroism (CD) measurements. The thermal unfolding is characterized by a three state transition with T(M1) and T(M2) at 323.5 K and 335.8 K, respectively; DeltaC(P1) and DeltaC(P2) are 2.05 kcal mol(-1) K(-1) and 1.40 kcal mol(-1) K(-1), respectively. In the temperature range 310-318 K, the molecule undergoes dimerisation. Isothermal equilibrium unfolding by guanidinium hydrochloride also follows a three state transition, N <_-_-> I <_-_-> U with DeltaG(1H2O) and DeltaG(2H2O) values of 5.2 kcal mol(-1) and 5.1 kcal mol(-1) at 300 K, respectively. Excess heat capacity values obtained, are similar to those obtained from DSC measurements. There is an increase in hydrodynamic radius from 20 A to 35.0 A due to unfolding by guanidinium hydrochloride. In silico alignment of sequences of napin has revealed that the internal repeats (40%) spanning residues 31 to 60 and 73 to 109 are conserved in all Brassica species. The internal repeats may contribute to the greater stability of napin. A thorough understanding of the structure and stability of these proteins is essential before they can be exploited for genetic improvements for nutrition.     

Nodulation patterns of actinorhizal plants in the family rosaceae

Patterns of nodulation, growth, andFrankia — host specificity have not been well characterized for the actinorhizal genera in the family Rosaceae because of the scarcity ofFrankia isolates from these taxa. Furthermore, the few isolates available from actinorhizal Rosaceae have consistently failed to nodulate plants from the host genus. In a series of experiments, species of rosaceousDryas, Cowania, Cercocarpus, Fallugia, andPurshia were inoculated withFrankia isolates, crushedDryas actinorhizae, and neoglacial soils to ascertain whether any of these inocula would effectively induce nodulation. Neoglacial soils from Alaska and Canada nodulated not only the localDryas drummondii, but alsoCercocarpus betuloides, Cowania mexicana andPurshia tridentata from distant and ecologically diverse locales as well as nonrosaceous, actinorhizal species ofAlnus, Elaeagnus, Myrica, andShepherdia. But of eightFrankia isolates, including two fromPurshia tridentata and one fromCowania mexicana, none were able to induce nodulation onPurshia orCowania species. Globular, actinorhizae-like nodules incapable of acetylene reduction were produced onC. betuloides inoculated withFrankia isolates. Crushed nodule suspensions fromDryas drummondii nodulated rosaceousCowania, Dryas andPurshia, as well as non-rosaceousElaeagnus, Myrica, andShepherdia species. Nodules produced by inoculation ofCowania mexicana andPurshia tridentata with crushed, dried nodule suspensions fromDryas drummondii reduced acetylene to ethylene, indicating nitrogenase activity for these nodulated plants. These data suggest that a similar microsymbiont infects the actinorhizal genera in the family Rosaceae.     

Electroantennogram responses of Apanteles obliquae (Hym., Braconidae) to various infochemicals

Abstract:   The electroantennogram recording technique (EAG) was used to study the olfactory sensitivity of Apanteles obliquae (Hym., Braconidae), a gregarious larval endoparasitoid of Spilosoma obliqua (Walker) (Lep., Arctiidae), to 25 general plant volatiles belonging to alcohol, aldehyde and terpenoid groups and also to volatiles from the host and plant–host complex. The EAG data indicated different olfactory sensitivity between the sexes, not only to individual plant volatiles but also to the volatiles from host and plant–host complex. Females were found to be more responsive than males. However the synthetic sex pheromone blend of the host insect elicited similar EAG responses in both sexes. The EAG data of the present study is correlated with the reported behaviour observed in other parasitoids.