Workhorses of biology research : model organisms

In two centuries of modern scientific history, model organisms have contributed to our understanding of human physiology, cell biology, and diseases. But what are model organisms? What discoveries have they contributed to? What are some limitations and ethical dimensions associated with them

Genome wide expression profiling of two accession of G. herbaceum L. in response to drought

<p>Abstract</p> <p>Background</p> <p>Genome-wide gene expression profiling and detailed physiological investigation were used for understanding the molecular mechanism and physiological response of <it>Gossypium herbaceum</it>, which governs the adaptability of plants in drought conditions. Recently, microarray-based gene expression analysis is commonly used to decipher genes and genetic networks controlling the traits of interest. However, the results of such an analysis are often plagued due to a limited number of genes (probe sets) on microarrays. On the other hand, pyrosequencing of a transcriptome has the potential to detect rare as well as a large number of transcripts in the samples quantitatively. We used Affymetrix microarray as well as Roche's GS-FLX transcriptome sequencing for a comparative analysis of cotton transcriptome in leaf tissues under drought conditions.</p> <p>Results</p> <p>Fourteen accessions of <it>Gossypium herbaceum </it>were subjected to mannitol stress for preliminary screening; two accessions, namely Vagad and RAHS-14, were selected as being the most tolerant and most sensitive to osmotic stress, respectively. Affymetrix cotton arrays containing 24,045 probe sets and Roche's GS-FLX transcriptome sequencing of leaf tissue were used to analyze the gene expression profiling of Vagad and RAHS-14 under drought conditions. The analysis of physiological measurements and gene expression profiling showed that Vagad has the inherent ability to sense drought at a much earlier stage and to respond to it in a much more efficient manner than does RAHS-14. Gene Ontology (GO) studies showed that the phenyl propanoid pathway, pigment biosynthesis, polyketide biosynthesis, and other secondary metabolite pathways were enriched in Vagad under control and drought conditions as compared with RAHS-14. Similarly, GO analysis of transcriptome sequencing showed that the GO terms <it>responses to various abiotic stresses </it>were significantly higher in Vagad. Among the classes of transcription factors (TFs) uniquely expressed in both accessions, RAHS-14 showed the expression of ERF and WRKY families. The unique expression of ERFs in response to drought conditions reveals that RAHS-14 responds to drought by inducing senescence. This was further supported by transcriptome analysis which revealed that RAHS-14 responds to drought by inducing many transcripts related to senescence and cell death.</p> <p>Conclusion</p> <p>The comparative genome-wide gene expression profiling study of two accessions of <it>G.herbaceum </it>under drought stress deciphers the differential patterns of gene expression, including TFs and physiologically relevant processes. Our results indicate that drought tolerance observed in Vagad is not because of a single molecular reason but is rather due to several unique mechanisms which Vagad has developed as an adaptation strategy.</p

Workhorses of Biology research : model organisms

In two centuries of modern scientific history, model organisms have contributed to our understanding of human physiology, cell biology, and diseases. But what are model organisms? What discoveries have they contributed to? What are some limitations and ethical dimensions associated with them

CRISPR-Cas-Induced Mutants Identify a Requirement for dSTIM in Larval Dopaminergic Cells of Drosophila melanogaster

Molecular components of store-operated calcium entry have been identified in the recent past and consist of the endoplasmic reticulum (ER) membrane-resident calcium sensor STIM and the plasma membrane-localized calcium channel Orai. The physiological function of STIM and Orai is best defined in vertebrate immune cells. However, genetic studies with RNAi strains in Drosophila suggest a role in neuronal development and function. We generated a CRISPR-Cas-mediated deletion for the gene encoding STIM in Drosophila (dSTIM), which we demonstrate is larval lethal. To study STIM function in neurons, we merged the CRISPR-Cas9 method with the UAS-GAL4 system to generate either tissue- or cell type-specific inducible STIM knockouts (KOs). Our data identify an essential role for STIM in larval dopaminergic cells. The molecular basis for this cell-specific requirement needs further investigation

FMRFa receptor stimulated Ca2+ signals alter the activity of flight modulating central dopaminergic neurons in Drosophila melanogaster.

Neuropeptide signaling influences animal behavior by modulating neuronal activity and thus altering circuit dynamics. Insect flight is a key innate behavior that very likely requires robust neuromodulation. Cellular and molecular components that help modulate flight behavior are therefore of interest and require investigation. In a genetic RNAi screen for G-protein coupled receptors that regulate flight bout durations, we earlier identified several receptors, including the receptor for the neuropeptide FMRFa (FMRFaR). To further investigate modulation of insect flight by FMRFa we generated CRISPR-Cas9 mutants in the gene encoding the Drosophila FMRFaR. The mutants exhibit significant flight deficits with a focus in dopaminergic cells. Expression of a receptor specific RNAi in adult central dopaminergic neurons resulted in progressive loss of sustained flight. Further, genetic and cellular assays demonstrated that FMRFaR stimulates intracellular calcium signaling through the IP3R and helps maintain neuronal excitability in a subset of dopaminergic neurons for positive modulation of flight bout durations

Association of psychiatric co.morbidity and efficacy of treatment in chronic daily headache in Indian population

Objective: To study the prevalence of psychiatric co‑morbidity in patients of chronic daily headache (CDH) and compare the efficacy of treatment between various type of headache associated with psychiatric co‑morbidity. Materials and Methods: Prospective case control cohort study, 92 consecutive patients of CDH meeting eligibility criteria. The diagnosis of various subtypes of CDH was made according to the IHS criteria. Age, sex, educational, marital and socioeconomic status, matched controls were also selected. Patients were evaluated with the Mini International Neuropsychiatric Interview (MINI) scale at the time of enrolment and at 3 months. Results: CDH accounted for 28% of all headache patients. The mean age of presentation was 30.2 ± 10.3 years, male: Female ratio of 28:64 and mean duration of 4.56 ± 0.56 years. Chronic migraine (CM) accounted for 59 patients, chronic tension type headache (CTTH) 22 patients, new daily persistent headache (NDPH) 3 patients and miscellaneous 8 patients. Psychiatric co‑morbidity was present in 53.3% patients with CDH, and was more common in CM (62.7%) as compared to CTTH (36.4%). Single psychiatric co‑morbidity was seen in 26 patients, while 23 patients had multiple co‑morbidity. Major depressive episode, anxiety disorder, agoraphobia and dysthymia were significant psychiatric co‑morbidities. Patients with CM were treated with topiramate or divalproex sodium ER and CTTH were treated with amitriptyline. 55 patients came for follow up at 3 months, improvement in headache was seen in 29 patients. Conclusion: Psychiatric co‑morbidity was present in more than 50% patients with CDH and its presence along with a duration of ≥2 years was associated with a poor response to treatment

Enhanced biomass production of <i>Scenedesmus obliquus</i> in a flat-panel photobioreactor, grown in photoautotrophic mode

<p>A study on biomass accumulation was conducted with <i>Scenedesmus obliquus</i> CCAP 276/3A in flat-panel photobioreactor, grown in photoautotrophic mode. It is one of the prime prerequisites to increase the economic feasibility and acceptance of microalgal feedstock for biofuel production, besides high lipid concentration. Various physicochemical parameters considered for evaluation during the present study were illumination conditions between 50 and 200 µmol m⁻² s⁻¹, temperatures between 22 and 30°C, pH varying from 7 to 9, and with and without the use of buffers. Among the variables, growth temperature and buffering with TRICINE had a pronounced effect on the enhanced biomass production. With an illumination intensity of 150 µmol m⁻² s⁻¹ at 24°C in the TRICINE-buffered Bold's Basal medium (pH 8.5) the maximum biomass concentration achieved was 1.76 gL^-1. The specific growth rate of the microalga was found to be 1.28 d⁻¹. Under these optimized conditions, the maximum lipid accumulation in <i>Scenedesmus obliquus</i> was found to be 33% (w/w). The compositional analysis of the neutral lipids indicated the predominance of palmitic acid and linoleic acid, accounting for 28% and 22.5%, respectively.</p

Phosphatidylinositol 5-phosphate 4-kinase (PIP4K) regulates TOR signaling and cell growth during Drosophila development

During development, Drosophila larvae undergo a dramatic increase in body mass wherein nutritional and developmental cues are transduced into growth through the activity of complex signaling pathways. Class I phosphoinositide 3-kinases have an established role in this process. In this study we identify Drosophila phosphatidylinositol 5-phosphate 4-kinase (dPIP4K) as a phosphoinositide kinase that regulates growth during larval development. Loss-of-function mutants in dPIP4K show reduced body weight and prolonged larval development, whereas overexpression of dPIP4K results both in an increase in body weight and shortening of larval development. The growth defect associated with dPIP4K loss of function is accompanied by a reduction in the average cell size of larval endoreplicative tissues. Our findings reveal that these phenotypes are underpinned by changes in the signaling input into the target of rapamycin (TOR) signaling complex and changes in the activity of its direct downstream target p70 S6 kinase. Together, these results define dPIP4K activity as a regulator of cell growth and TOR signaling during larval development

Seed Biopriming with Microbial Inoculant Triggers Local and Systemic Defense Responses against Rhizoctonia solani Causing Banded Leaf and Sheath Blight in Maize (Zea mays L.)

Plant growth promoting rhizobacteria Pseudomonas aeruginosa strain MF-30 isolated from maize rhizosphere was characterized for several plant growth stimulating attributes. The strain MF-30 was also evaluated for antifungal properties against Rhizoctonia solani causing banded leaf and sheath blight in maize (Zea mays L.) under in vitro conditions and was found to have higher mycelial growth suppression in the culture suspension (67.41%) followed by volatile organic compounds (62.66%) and crude extract (51.20%) in a dual plate assay. The endophytic and epiphytic colonization ability was tested using Green Fluorescent Protein (GFP)-tagging. Visualization through confocal scanning laser microscope clearly indicated that strain MF-30 colonizes the root and foliar parts of the plants. Further, the effects of seed bio-priming with P. aeruginosa MF-30 was evaluated in the induction and bioaccumulation of defense-related biomolecules, enzymes, natural antioxidants, and other changes in maize under pot trial. This not only provided protection from R. solani but also ensured growth promotion under pathogenic stress conditions in maize. The maximum concentration of hydrogen peroxide (H2O2) was reported in the root and shoot of the plants treated with R. solani alone (8.47 and 17.50 mmol mg&minus;1 protein, respectively) compared to bioagent, P. aeruginosa MF-30 bio-primed plants (3.49 and 7.50 mmol mg&minus;1 protein, respectively). Effects on total soluble sugar content, total protein, and total proline were also found to enhanced significantly due to inoculation of P. aeruginosa MF-30. The activities of anti-oxidative defense enzymes phenylalanine ammonia lyase (PAL), ascorbate peroxidase, peroxidase, superoxide dismutase, and catalase increased significantly in the plants bio-primed with P. aeruginosa MF-30 and subsequent foliar spray of culture suspension of MF-30 compared to pathogen alone inoculated plants. qRT-PCR analysis revealed that seed bio-priming and foliar application of P. aeruginosa MF-30 significantly increased the expression of PR-1 and PR-10 genes with the simultaneous decrease in the disease severity and lesion length in the maize plants under pathogenic stress conditions. A significant enhancement of shoot and root biomass was recorded in MF-30 bio-primed plants as compared to untreated control (p &lt; 0.05). Significant increase in plant growth and antioxidant content, as well as decreased disease severity in the P. aeruginosa MF-30 bio-primed plants, suggested the possibility of an eco-friendly and economical means of achieving antioxidants-rich, healthier maize plants