Detection and Characterization of ACC Deaminase in Plant Growth Promoting Rhizobacteria

The enzyme 1-aminocyclopropane-1-carboxylate deaminase converts ACC, the precursor of the plant hormone ethylene to α-ketobutyrate and ammonium. The enzyme has been identified in few soil bacteria, and is proposed to play a key role in plant growth promotion. In this study, the isolates of plant growth promoting rhizobacteria were screened for ACC deaminase activity based on their ability to grow on ACC as a sole nitrogen source. The selected isolates showed the presence of other plant growth promoting characteristics such as IAA production, phosphate solubilization and siderophore production. The role of ACC deaminase in lowering ethylene production under cadmium stress condition was also studied by measuring in vitro ethylene evolution by wheat seedlings treated with ACC deaminase positive isolates. Nucleic acid hybridization confirmed the presence of ACC deaminase gene (acdS) in the bacterial isolates.     

Enzymatic transesterification of Jatropha oil

Background  

Transesterification of Jatropha oil was carried out in t-butanol solvent using immobilized lipase from Enterobacter aerogenes. The presence of t-butanol significantly reduced the negative effects caused by both methanol and glycerol. The effects of various reaction parameters on transesterification of Jatropha oil were studied.     

Biomethanation of poultry litter leachate in UASB reactor coupled with ammonia stripper for enhancement of overall performance

In the present study possibility of coupling stripper to remove ammonia to the UASB reactor treating poultry litter leachate was studied to enhance the overall performance of the reactor. UASB reactor with stripper as ammonia inhibition control mechanism exhibited better performance in terms of COD reduction (96%), methane yield (0.26m(3)CH(4)/kg COD reduced), organic loading rate (OLR) (18.5kg COD m(-3)day(-1)) and Hydraulic residence time (HRT) (12h) compared to the UASB reactor without stripper (COD reduction: 92%; methane yield: 0.21m(3)CH(4)/kg COD reduced; OLR: 13.6kg CODm(-3)day(-1); HRT: 16h). The improved performance was due to the reduction of total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) in the range of 75-95% and 80-95%, respectively by the use of stripper. G/L (air flow rate/poultry leachate flow rate) in the range of 60-70 and HRT in the range of 7-9min are found to be optimum parameters for the operation of the stripper.     

Microarray Noninvasive Neuronal Seizure Recordings from Intact Larval Zebrafish

Zebrafish epilepsy models are emerging tools in experimental epilepsy. Zebrafish larvae, in particular, are advantageous because they can be easily genetically altered and used for developmental and drug studies since agents applied to the bath penetrate the organism easily. Methods for electrophysiological recordings in zebrafish are new and evolving. We present a novel multi-electrode array method to non-invasively record electrical activity from up to 61 locations of an intact larval zebrafish head. This method enables transcranial noninvasive recording of extracellular field potentials (which include multi-unit activity and EEG) to identify epileptic seizures. To record from the brains of zebrafish larvae, the dorsum of the head of an intact larva was secured onto a multi-electrode array. We recorded from individual electrodes for at least three hours and quantified neuronal firing frequency, spike patterns (continuous or bursting), and synchrony of neuronal firing. Following 15 mM potassium chloride- or pentylenetetrazole-infusion into the bath, spike and burst rate increased significantly. Additionally, synchrony of neuronal firing across channels, a hallmark of epileptic seizures, also increased. Notably, the fish survived the experiment. This non-invasive method complements present invasive zebrafish neurophysiological techniques: it affords the advantages of high spatial and temporal resolution, a capacity to measure multiregional activity and neuronal synchrony in seizures, and fish survival for future experiments, such as studies of epileptogenesis and development.     

Presence of HIV-1 Gag-specific IFN-gamma+IL-2+ and CD28+IL-2+ CD4 T cell responses is associated with nonprogression in HIV-1 infection

HIV immunity is likely CD4 T cell dependent. HIV-specific CD4 T cell proliferative responses are reported to correlate inversely with virus load and directly with specific CD8 responses. However, the phenotype and cytokine profile of specific CD4 T cells that correlate with disease is unknown. We compared the number/function of Gag p24-specific CD4 T cells in 17 HIV-infected long-term nonprogressors (LTNPs) infected for a median of 14.6 years with those of 16 slow progressors (SPs), also HIV infected for a median of 14 years but whose CD4 count had declined to <500 cells/ micro l. Compared with SPs, LTNPs had higher numbers of specific CD4s that were double positive for IFN-gamma and IL-2 as well as CD28 and IL-2. However, CD4 T cells that produced IL-2 alone (IL-2(+)IFN-gamma(-)) or IFN-gamma alone (IFN-gamma(+)IL-2(-)) did not differ between LTNPs and SPs. The decrease in p24-specific CD28(+)IL-2(+) cells with a concomitant increase of p24-specific CD28(-)IL-2(+) cells occurred before those specific for a non-HIV Ag, CMV. p24-specific CD28(-)IL-2(+) cells were evident in LTNPs and SPs, whereas the CMV-specific CD28(-)IL-2(+) response was confined to SPs. The difference between LTNPs and SPs in the Gag p24 IFN-gamma(+)IL-2(+) response was maintained when responses to total Gag (p17 plus p24) were measured. The percentage and absolute number of Gag-specific IFN-gamma(+)IL-2(+) but not of IFN-gamma(+)IL-2(-) CD4s correlated inversely with virus load. The Gag-specific IFN-gamma(+)IL-2(+) CD4 response also correlated positively with the percentage of Gag-specific IFN-gamma(+) CD8 T cells in these subjects. Accumulation of specific CD28(-)IL-2(+) helpers and loss of IFN-gamma(+)IL-2(+) CD4 T cells may compromise specific CD8 responses and, in turn, immunity to HIV.     

A spatiotemporal characterization of the effect of p53 phosphorylation on its interaction with MDM2

The interaction of p53 and MDM2 is modulated by the phosphorylation of p53. This mechanism is key to activating p53, yet its molecular determinants are not fully understood. To study the spatiotemporal characteristics of this molecular process we carried out Brownian dynamics simulations of the interactions of the MDM2 protein with a p53 peptide in its wild type state and when phosphorylated at Thr18 (pThr18) and Ser20 (pSer20). We found that p53 phosphorylation results in concerted changes in the topology of the interaction landscape in the diffusively bound encounter complex domain. These changes hinder phosphorylated p53 peptides from binding to MDM2 well before reaching the binding site. The underlying mechanism appears to involve shift of the peptide away from the vicinity of the MDM2 protein, peptide reorientation, and reduction in peptide residence time relative to wild-type p53 peptide. pThr18 and pSr20 p53 peptides experience reduction in residence times by factors of 13.6 and 37.5 respectively relative to the wild-type p53 peptide, indicating a greater role for Ser20 phosphorylation in abrogating p53 MDM2 interactions. These detailed insights into the effect of phosphorylation on molecular interactions are not available from conventional experimental and theoretical approaches and open up new avenues that incorporate molecular interaction dynamics, for stabilizing p53 against MDM2, which is a major focus of anticancer drug lead development.     

Mutations in QARS,Encoding Glutaminyl-tRNA Synthetase,Cause Progressive Microcephaly,Cerebral-Cerebellar Atrophy,and Intractable Seizures

Progressive microcephaly is a heterogeneous condition with causes including mutations in genes encoding regulators of neuronal survival. Here, we report the identification of mutations in QARS (encoding glutaminyl-tRNA synthetase [QARS]) as the causative variants in two unrelated families affected by progressive microcephaly, severe seizures in infancy, atrophy of the cerebral cortex and cerebellar vermis, and mild atrophy of the cerebellar hemispheres. Whole-exome sequencing of individuals from each family independently identified compound-heterozygous mutations in QARS as the only candidate causative variants. QARS was highly expressed in the developing fetal human cerebral cortex in many cell types. The four QARS mutations altered highly conserved amino acids, and the aminoacylation activity of QARS was significantly impaired in mutant cell lines. Variants p.Gly45Val and p.Tyr57His were located in the N-terminal domain required for QARS interaction with proteins in the multisynthetase complex and potentially with glutamine tRNA, and recombinant QARS proteins bearing either substitution showed an over 10-fold reduction in aminoacylation activity. Conversely, variants p.Arg403Trp and p.Arg515Trp, each occurring in a different family, were located in the catalytic core and completely disrupted QARS aminoacylation activity in vitro. Furthermore, p.Arg403Trp and p.Arg515Trp rendered QARS less soluble, and p.Arg403Trp disrupted QARS-RARS (arginyl-tRNA synthetase 1) interaction. In zebrafish, homozygous qars loss of function caused decreased brain and eye size and extensive cell death in the brain. Our results highlight the importance of QARS during brain development and that epilepsy due to impairment of QARS activity is unusually severe in comparison to other aminoacyl-tRNA synthetase disorders.     

Micropropagation of <Emphasis Type="BoldItalic">Embelia ribes</Emphasis> Burm f. through proliferation of adult plant axillary shoots

Micropropagation of Embelia ribes was achieved through proliferation of axillary shoots obtained from mature plants. Nodal shoot segments, collected March–May, exhibited high-frequency (75%) shoot initiation when cultured on Murashige and Skoog (MS) basal medium supplemented with thidiazuron (TDZ) at 1.13 μM and indole-3-butyric acid (IBA) at 0.49 μM. Subculture of sprouted shoots from the original explants on medium containing TDZ (1.13 and 0.45 μM) during the first and second subcultures was found essential for further shoot proliferation, while inhibition of shoot elongation by TDZ could be overcome by transferring shoot cultures onto MS medium containing 6-benzylaminopurine (BAP; 11.10 μM) for the third subculture. Treating the explants with an antioxidant mixture of 568 μM ascorbic acid, 119 μM citric acid, and 307 μM glutathione prior to inoculation, coupled with subculture at 2-wk intervals onto fresh medium, both helped to reduce browning of the explants and facilitated production of five to six shoots/explant. MS medium supplemented with BAP (4.44 μM) and IBA (0.49 μM) induced shoot multiplication, producing five to six shoots/explant with a shoot length of 3 to 4 cm over a 4-wk culture period. Shoots of 3 to 4 cm in length exhibited 100% rooting within 4 wk after transfer to media containing half the nutrient salt concentration of MS medium with 3.69 μM IBA. Ex vitro rooting in the greenhouse from the in vitro shoots treated with 4.93 μM IBA for 30 min exhibited 95% rooting in soilrite™ medium in a 4-wk period. About 85% of micropropagated plants were established successfully in root trainers. Three-month-old, hardened plants could further be successfully established in the field. In 1 yr, by using the above protocol, 3,200 plants could be produced from a single shoot and 2,700 could be established in the field.     

Ground wētā in vines of the Awatere Valley,Marlborough: biology,density and distribution

The endemic New Zealand ground wētā (Hemiandrus sp. ‘promontorius’) has a Naturally Uncommon conservation status. This is because of the paucity of information on its density and distribution. Here, the biology, density and distribution of a population of this wētā found in and around vineyards in the Awatere Valley, Marlborough was studied. Wētā density was assessed in vineyards, paddocks and shrublands in this valley. Soil moisture, penetration resistance, pH and organic matter were recorded at locations with and without wētā. Wētā density in vineyards was significantly higher than in either paddocks or shrub habitats. In vineyards, the density of this insect was significantly higher under-vines than in the inter-rows. Higher numbers of this wētā were found in moist soils that required lower force to burrow. Females laid an average of 55 eggs between March and April, which hatched in September. These findings highlight the intersection between agriculture and conservation.