Biology subjects

Thakur, N.

Publications and source records attributed to Thakur, N..

4 recordsLinked to original sources

bioRxiv2018

Speed Control and Force-Vectoring of Blue Bottle Flies in a Magnetically-Levitated Flight Mill

Flies fly at a broad range of speeds and produce sophisticated aerial maneuvers with precisely controlled wing movements. Remarkably, only subtle changes in wing motion are used by flies to produce aerial maneuvers, resulting in little directional tilt of aerodynamic force vector relative to the body. Therefore, it is often considered that flies fly according to a helicopter model and control speed mainly via force-vectoring enabled primarily by body-pitch change. Here we examine the speed control of blue bottle flies using a magnetically-levitated (MAGLEV) flight mill, as they fly at different body pitch and with different augmented aerodynamic damping. We identify wing kinematic contributors to the changes of estimated aerodynamic force through testing two force-vectoring models. Results show that in addition to body pitch, flies also use a collection of wing kinematic variables to control both force magnitude and direction, the roles of which are analogous to those of throttle, collective and cyclic pitch of helicopters. Our results also suggest that the MAGLEV flight mill system can be potentially used to study the roles of visual and mechanosensory feedback in insect flight control.\n\nSummary statement: This paper elucidates how files control flight speed while flying in a magnetically-levitated (MAGLEV) flight mill, which enables the manipulation of body pitch and aerodynamic load.

bioengineering↗

bioRxiv2017

Modulatory upregulation of an insulin peptide gene by different pathogens in C. elegans

When an animal is infected, its innate immune response needs to be tightly regulated across tissues and coordinated with other aspects of organismal physiology. Previous studies with Caenorhabditis elegans have demonstrated that insulin-like peptide genes are differentially expressed in response to different pathogens. They represent prime candidates for conveying signals between tissues upon infection. Here, we focused on one such gene, ins-11 and its potential role in mediating cross-tissue regulation of innate immune genes. While diverse bacterial intestinal infections can trigger the up-regulation of ins-11 in the intestine, we show that epidermal infection with the fungus Drechmeria coniospora triggers an upregulation of ins-11 in the epidermis. Using the Shigella virulence factor OpsF, a MAP kinase inhibitor, we found that in both cases, ins-11 expression is controlled cell autonomously by p38 MAPK, but via distinct transcription factors, STA-2/STAT in the epidermis and HLH-30/TFEB in the intestine. We established that ins-11, and the insulin signaling pathway more generally, are not involved in the regulation of antimicrobial peptide gene expression in the epidermis. The up-regulation of ins-11 in the epidermis does, however, affect intestinal gene expression in a complex manner, and has a deleterious effect on longevity. These results support a model in which insulin signaling, via ins-11, contributes to the coordination of the organismal response to infection, influencing the allocation of resources in an infected animal.

genetics↗

bioRxiv2017

A Genome-wide Association and Admixture Mapping Study of Bronchodilator Drug Response in African Americans with Asthma

BackgroundShort-acting B2-adrenergic receptor agonists (SABAs) are the most commonly prescribed asthma medications worldwide. Response to SABAs is measured as bronchodilator drug response (BDR), which varies among racial/ethnic groups in the U.S 1, 2. However, the genetic variation that contributes to BDR is largely undefined in African Americans with asthma3\n\nObjectiveTo identify genetic variants that may contribute to differences in BDR in African Americans with asthma.\n\nMethodsWe performed a genome-wide association study of BDR in 949 African American children with asthma, genotyped with the Axiom World Array 4 (Affymetrix, Santa Clara, CA) followed by imputation using 1000 Genomes phase 3 genotypes. We used linear regression models adjusting for age, sex, body mass index and genetic ancestry to test for an association between BDR and genotype at single nucleotide polymorphisms (SNPs). To increase power and distinguish between shared vs. population-specific associations with BDR in children with asthma, we performed a meta-analysis across 949 African Americans and 1,830 Latinos (Total=2,779). Lastly, we performed genome-wide admixture mapping to identify regions whereby local African or European ancestry is associated with BDR in African Americans. Two additional populations of 416 Latinos and 1,325 African Americans were used to replicate significant associations.\n\nResultsWe identified a population-specific association with an intergenic SNP on chromosome 9q21 that was significantly associated with BDR (rs73650726, p=7.69 x 10-9). A trans-ethnic meta-analysis across African Americans and Latinos identified three additional SNPs within the intron of PRKG1 that were significantly associated with BDR (rs7903366, rs7070958, and rs7081864, p[≤]5 x 10-8).\n\nConclusionsOur findings indicate that both population specific and shared genetic variation contributes to differences in BDR in minority children with asthma, and that the genetic underpinnings of BDR may differ between racial/ethnic groups.\n\nKey messagesO_LIA GWAS for BDR in African American children with asthma identified an intergenic population specific variant at 9q21 to be associated with increased bronchodilator drug response (BDR).\nC_LIO_LIA meta-analysis of GWAS across African Americans and Latinos identified shared genetic variants at 10q21 in the intron of PRKG1 to be associated with differences in BDR.\nC_LIO_LIFurther genetic studies need to be performed in diverse populations to identify the full set of genetic variants that contribute to BDR.\nC_LI

genomics↗

bioRxiv2017

Exposure to Wood Smoke is Associated with Increased Risk of Asthma and Respiratory Symptoms in a Honduran Population

BackgroundExposure to environmental pollutants has been shown to be associated with asthma, but few studies have evaluated the effect of wood smoke on asthma and disease severity in a developing country, where use of stoves powered by solid fuels is a common practice.\n\nObjectiveIn a population in Olancho, Honduras, we evaluated the association between cooking fuel, stove type and asthma. We also evaluated the effects of these factors on asthma symptoms, lung function, and atopy.\n\nMethodsParticipants with physician-diagnosed asthma (n = 597) and controls without asthma (n = 429) were recruited from the Olancho province in Honduras. Participants were interviewed using a questionnaire and their baseline pulmonary function was measured using spirometry.\n\nResultsThe prevalence of use of wood as a cooking fuel was 66.9% in the study population, of which 42.1% of participants used wood as their only fuel. Use of wood as a cooking fuel was more prevalent among households with lower income, lower maternal education, and less urbanization. The prevalence of use of an open wood stove as the primary cooking stove among participants with asthma was 6.2% higher (95% CI 0.8 - 11.7%, p = .02) than among healthy controls. In a multiple logistic regression model, we identified a significant association between use of an open wood stove and asthma (OR = 1.80, 95% CI = 1.17 - 2.78, p = 0.007), compared to the referent (electric) stove category. Among participants with asthma, we identified a significant association between use of wood as cooking fuel and increased daytime respiratory symptoms (OR = 1.46, CI: 1.01 - 2.58, p = 0.046) and nocturnal symptoms (OR = 2.51, CI: 1.04 - 2.62, p = 0.04), though not with pulmonary function. Among control participants without asthma, use of wood as cooking fuel was associated with atopy (OR = 1.94, CI = 1.14 - 3.33, p = 0.015) and cough (OR = 2.22, CI = 1.09 - 4.88, p = 0.04).\n\nConclusionsUse of an open wood stove for cooking in a developing country appears to be a significant risk factor for asthma and respiratory symptoms. Exposure to wood smoke may play a role in atopic sensitization and respiratory symptoms, leading to the development of obstructive lung disease in susceptible individuals.

epidemiology↗