Exploiting Phosphate-Starved cells of <Emphasis Type="Italic">Scenedesmus</Emphasis> sp. for the Treatment of Raw Sewage

Phosphate depletion is one of the favorable ways to enhance the sewage water treatment with the algae, however, detailed information is essential with respect to internal phosphate concentration and physiology of the algae. The growth rate of the phosphate-starved Scenedesmus cells was reduced drastically after 48 h. Indicating cells entered in the stationary phase of the growth cycle. Fourier Transform Infrared analysis of phosphate-starved Scenedesmus cells showed the reduction in internal phosphate concentration and an increase in carbohydrate/phosphate and carbohydrate/lipid ratio. The phosphate-starved Scenedesmus cells, with an initial cell density of, 1 × 10⁶ cells mL^?1 shows 87% phosphate and 100 % nitrogen removal in 24 h. The normal Scenedesmus cells need approximately 48 h to trim down the nutrients from wastewater up to this extent. Other microalgae, Ankistrodesmus, growth pattern was not affected due to phosphate starvation. The cells of Ankistrodesmus was able to reduce 71% phosphate and 73% nitrogen within 24 h, with an initial cell density of, 1 × 10⁶ cells mL^?1.     

AtHsp101 research sets course of action for the genetic improvement of crops against heat stress

Journal of Plant Biochemistry and Biotechnology - Caseinolytic protease (Clp)/Hsp100 proteins are members of the AAA+ (ATPase associated with a variety of cellular activities) family of proteins...     

Intermittent hypoxia activates peptidylglycine alpha-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing

Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the alpha-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O(2)-sensitive peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O(2) for 15 s followed by 21% O(2) for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of alpha-amidated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM ( approximately 1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases V(max) but has no effect on K(m). IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.     

Insights into the structure–function relationship of brown plant hopper resistance protein,Bph14 of rice plant: a computational structural biology approach

Brown plant hopper (BPH) is one of the major destructive insect pests of rice, causing severe yield loss. Thirty-two BPH resistance genes have been identified in cultivated and wild species of rice Although, molecular mechanism of rice plant resistance against BPH studied through map-based cloning, due to non-existence of NMR/crystal structures of Bph14 protein, recognition of leucine-rich repeat (LRR) domain and its interaction with different ligands are poorly understood. Thus, in the present study, in silico approach was adopted to predict three-dimensional structure of LRR domain of Bph14 using comparative modelling approach followed by interaction study with jasmonic and salicylic acids. LRR domain along with LRR-jasmonic and salicylic acid complexes were subjected to dynamic simulation using GROMACS, individually, for energy minimisation and refinement of the structure. Final binding energy of jasmonic and salicylic acid with LRR domain was calculated using MM/PBSA. Free-energy landscape analysis revealed that overall stability of LRR domain of Bph14 is not much affected after forming complex with jasmonic and salicylic acid. MM/PBSA analysis revealed that binding affinities of LRR domain towards salicylic acid is higher as compared to jasmonic acid. Interaction study of LRR domain with salicylic acid and jasmonic acid reveals that THR987 of LRR form hydrogen bond with both complexes. Thus, THR987 plays active role in the Bph14 and phytochemical interaction for inducing resistance in rice plant against BPH. In future, Bph14 gene and phytochemicals could be used in BPH management and development of novel resistant varieties for increasing rice yield.     

Clostridium perfringens alpha toxin is produced in the intestines of broiler chicks inoculated with an alpha toxin mutant

Poultry necrotic enteritis (NE) is caused by specific strains of Clostridium perfringens, most of which are type A. The role of alpha toxin (CPA) in NE has been called into question by the finding that an engineered cpa mutant retains full virulence in vivo[9]. This is in contrast to the finding that immunization with CPA toxoids protects against NE. We confirmed the earlier findings, in that 14-day-old Cornish × Rock broiler chicks challenged with a cpa mutant developed lesions compatible with NE in >90% of birds inoculated with the mutant. However, CPA was detected in amounts ranging from 10 to >100 ng per g of gut contents and mucosa in birds inoculated with the cpa mutant, the wildtype strain from which the mutant was constructed, and our positive control strain. There was a direct relationship between lesion severity and amount of CPA detected (R = 0.89-0.99). These findings suggest that the role of CPA in pathogenesis of NE requires further investigation.     

Clostridium difficile clinical isolates exhibit variable susceptibility and proteome alterations upon exposure to mammalian cationic antimicrobial peptides

Clostridium difficile is a leading cause of hospital-acquired bacterial infections in the United States, and the increased incidence of recurrent C. difficile infections is particularly problematic. The molecular mechanisms of C. difficile colonization, including its ability to evade host innate immune responses, is poorly understood. We hypothesized that epidemic-associated C. difficile clinical isolates would exhibit increased resistance to mammalian, gut-associated, cationic antimicrobial peptides such as the cathelicidin LL-37. Standardized susceptibility tests as well as comparative proteomic analyses revealed that C. difficile strains varied in their responses to LL-37, with epidemic-associated 027 ribotype isolates displaying greater resistance. Further, exposure of C. difficile strains to sub-lethal concentrations of LL-37 resulted in increased resistance to subsequent peptide challenge, suggesting the presence of inducible resistance mechanisms. Correspondingly, LL-37 exposure altered the C. difficile proteome, with marked changes in abundance of cell wall biosynthesis proteins, surface layer proteins, ABC transporters and lysine metabolism pathway components. Taken together, these results suggest that innate immune avoidance mechanisms could facilitate robust colonization by C. difficile.     

An oxidative and salinity stress induced peroxisomal ascorbate peroxidase from Avicennia marina: Molecular and functional characterization

APX (EC, 1.11.1.11) has a key role in scavenging ROS and in protecting cells against their toxic effects in algae and higher plants. A cDNA encoding a peroxisomal ascorbate peroxidase, Am-pAPX1, was isolated from salt stressed leaves of Avicennia marina (Forsk.) Vierh. by EST library screening and its expression in the context of various environmental stresses was investigated. Am-pAPX1 contains an ORF of 286 amino acids coding for a 31.4kDa protein. The C-terminal region of the Am-pAPX1 ORF has a putative transmembrane domain and a peroxisomal targeting signal (RKKMK), suggesting peroxisomal localization. The peroxisomal localization of Am-pAPX1 was confirmed by stable transformation of the GFP-(Ala)(10)-Am-pAPX1 fusion in tobacco. RNA blot analysis revealed that Am-pAPX1 is expressed in response to salinity (NaCl) and oxidative stress (high intensity light, hydrogen peroxide application and excess iron). The isolated genomic clone of Am-pAPX1 was found to contain nine exons. A fragment of 1616bp corresponding to the 5' upstream region of Am-pAPX1 was isolated by TAIL-PCR. In silico analysis of this sequence reveals the presence of putative light and abiotic stress regulatory elements.     

Inhibition of collagenase by Cr(III): its relevance to stabilization of collagen

Bacterial collagenase has now been reacted with a select series of Cr(III) complexes and modifications in the activity of chromium-modified collagenase has been deduced from the extent of hydrolysis of (2-furanacryloyl-L-leucyl-glycyl-L-prolyl-L-alanine), FALGPA. A homologous series of Cr(III) complexes with dimeric, trimeric and tetrameric structures as in 1, 2 and 3 respectively has been investigated for their ability to inhibit the action of collagenase against FALGPA. Whereas competitive and non-competitive modes of inhibition of collagenase are expressed by 1, (dimer) and 2, (trimer) respectively, the tetramer, 3, exhibits poor affinity to collagenase and the inhibition of the enzyme activity is uncompetitive. Evidence for different modes of inhibition of collagenase depending on the nature of Cr(III) species has been presented in this work. Circular dichroism and gel electrophoresis data on Cr(III) modified collagenase corroborate the hypothesis that the inhibition of collagenase by the heavy metal ion arises from secondary and quaternary structural changes in the enzyme. The implications of the observed Cr(III) species specific inhibition of collagenase in gaining new insight into the mechanism of stabilization of collagen by Cr(III) are discussed.     

Spatial distribution of root activity and nitrogen fixation in sorghum/pigeonpea intercropping on an Indian Alfisol

A medium-duration pigeonpea cultivar (ICP 1–6) and a hybrid sorghum (CSH 5) were grown on a shallow Alfisol in monocropping and intercropping systems. Using a monolith method, spatial distribution of nodulation, acetylene reduction activity (ARA) and root respiration were measured.The number, mass and ARA of nodules decreased exponentially with distance from the plant base except at the late reproductive stage. Nodulation and ARA tended to be higher in the intercrop than in the monocrop.Respiration rate of roots increased with distance from the plant base and reached a maximum value at about 20–30 cm. The rate was higher in pigeonpea than in sorghum and also higher in intercrop than in monocrop.This study suggests that pigeonpea roots are physiologically more active than sorghum roots, implying that pigeonpea may become a strong competitor for nutrients in the soil when intercropped. The nitrogen-fixing ability of pigeonpea may be enhanced by intercropping because the sorghum rapidly absorbed inorganic N which would otherwise inhibit N₂ fixation.