School Environment and Locus of Control in Relation to Job Satisfaction among School Teachers – A Study from Indian Perspective

AbstractThe purpose of this study is to explore different patterns of relationship of job satisfaction with school environment and locus of control in different groups of school teachers selected from different school of Kolkata, India. Another objective is to see whether there any demographic variable which play any role on the job satisfaction of the teachers. 160 data were collected from the school teachers of Kolkata, using Revised School-Level Environment Questionnaire, Rotter Locus of control scale and Teacher job satisfaction questionnaire. Results showed that job satisfaction is significantly correlated with different domains of school environment and locus of control. Stepwise regression analysis indicated that job satisfaction can be significantly predicted by locus of control and maximum domains of school environment. This study highlighted a vital impact of school environment and locus of control on job satisfaction

Hemoglobin Endocytosis and Intracellular Trafficking: A Novel Way of Heme Acquisition by Leishmania

Leishmania species are causative agents of human leishmaniasis, affecting 12 million people annually. Drugs available for leishmaniasis are toxic, and no vaccine is available. Thus, the major thrust is to identify new therapeutic targets. Leishmania is an auxotroph for heme and must acquire heme from the host for its survival. Thus, the major focus has been to understand the heme acquisition process by the parasites in the last few decades. It is conceivable that the parasite is possibly obtaining heme from host hemoprotein, as free heme is not available in the host. Current understanding indicates that Leishmania internalizes hemoglobin (Hb) through a specific receptor by a clathrin-mediated endocytic process and targets it to the parasite lysosomes via the Rab5 and Rab7 regulated endocytic pathway, where it is degraded to generate intracellular heme that is used by the parasite. Subsequently, intra-lysosomal heme is initially transported to the cytosol and is finally delivered to the mitochondria via different heme transporters. Studies using different null mutant parasites showed that these receptors and transporters are essential for the survival of the parasite. Thus, the heme acquisition process in Leishmania may be exploited for the development of novel therapeutics

Leishmania highjack host lipid body for its proliferation in macrophages by overexpressing host Rab18 and TRAPPC9 by downregulating miR-1914-3p expression.

Lipids stored in lipid-bodies (LBs) in host cells are potential sources of fatty acids for pathogens. However, the mechanism of recruitment of LBs from the host cells by pathogens to acquire fatty acids is not known. Here, we have found that Leishmania specifically upregulates the expression of host Rab18 and its GEF, TRAPPC9 by downregulating the expression of miR-1914-3p by reducing the level of Dicer in macrophages via their metalloprotease gp63. Our results also show that miR-1914-3p negatively regulates the expression of Rab18 and its GEF in cells. Subsequently, Leishmania containing parasitophorous vacuoles (Ld-PVs) recruit and retain host Rab18 and TRAPPC9. Leishmania infection also induces LB biogenesis in host cells and recruits LBs on Ld-PVs and acquires FLC12-labeled fatty acids from LBs. Moreover, overexpression of miR-1914-3p in macrophages significantly inhibits the recruitment of LBs and thereby suppresses the multiplication of parasites in macrophages as parasites are unable to acquire fatty acids. These results demonstrate a novel mechanism how Leishmania acquire fatty acids from LBs for their growth in macrophages

Mechanism of overexpression of host Rab18 by <i>Leishmania</i> in infected macrophages.

a, Modulation of the expression of several host miRNAs in L. donovani infected macrophages was revealed by microarray analysis. Relative expression of miRNAs in infected cells was determined in comparison to uninfected control. The whole microarray data have been submitted in Gene Expression Omnibus database (accession number GSE89529). b, Sequence alignment of 3/-UTR of host Rab18 and TRAPPC9 containing 7-mer target site with the seed region of miR-1914-3p predicted by TagetScan tool. Mutation in the target site of 3/-UTR of Rab18 is highlighted in bold. c, Expression of miR-1914-3p in L. donovani infected and uninfected THP-1 macrophages was determined 12 h post infection using qPCR as described in Materials & Methods. d, miR-1914-3p mediated regulation of Rab18 expression was determined by co-transfecting pmir-GLO chimeric construct containing Rab18 3/-UTR or its mutant with miR-1914-3p (40 nM) or control mimic miR into semiconfluent HeLa cells. Luciferase activity was determined from lysed cells after 48 h of transfection as described in Materials & Methods. Results are expressed as relative luciferase activity. Untreated control cells were arbitrarily chosen as one unit. e, THP-1 differentiated macrophages were infected with L. donovani and expression level of Dicer in infected cells was determined at indicated time points using specific antibody against human Dicer. Uninfected cells were used as control. Actin was used as loading control. Right panel indicates the quantitation of host Dicer level at different time points. f, Expression of Dicer was determined in HeLa cells transfected with plasmid containing Flag tagged Ld-gp63 by Western blot analysis using specific antibody against Dicer. Level of gp63 in untransfected and vector transfected cells were also determined by Western blot analysis using anti-Flag antibody. Actin was used as loading control. g, Differentiated THP-1 macrophages were transfected with control miR or miR-1914-3p at indicated concentrations and expression of Rab18 was measured by qPCR as described in Materials & Methods. h, Levels of host Rab18 and Rab5 proteins in control miR or miR-1914-3p (10 nM or 20 nM) transfected THP-1 cells was determined by Western blot analysis using specific antibodies against human Rab18 and Rab5. Actin was used as loading control. i, Similarly, level of TRAPPC9 protein in control miR or miR-1914-3p (10 nM or 20 nM) transfected THP-1 cells was determined by Western blot analysis using human anti-TRAPPC9 antibody. Actin was used as loading control. All results represented as mean ± S.D. of three independent experiments. Results of the indicated groups were analyzed by paired t test and levels of significance are indicated by P value.</p

Evolution of force networks during stick-slip motion of an intruder in a granular material: Topological measures extracted from experimental data

In quasi-two-dimensional experiments with photoelastic particles confined to an annular region, an intruder constrained to move in a circular path halfway between the annular walls experiences stick-slip dynamics. We discuss the response of the granular medium to the driven intruder, focusing on the evolution of the force network during sticking periods. Because the available experimental data do not include precise information about individual contact forces, we use an approach developed in our previous work [Basak et al., J. Eng. Mech.147, 04021100 (2021)] based on networks constructed from measurements of the integrated strain magnitude on each particle. These networks are analyzed using topological measures based on persistence diagrams, revealing that force networks evolve smoothly but in a nontrivial manner throughout each sticking period, even though the intruder and granular particles are stationary. Characteristic features of persistence diagrams show identifiable slip precursors. In particular, the number of generators describing the structure and complexity of force networksincreases consistently before slips. Key features of the dynamics are similar for granular materials composed of disks or pentagons, but some details are consistently different. In particular, we find significantly larger fluctuations of the measures computed based on persistence diagrams and, therefore, of the underlying networks, for systems of pentagonal particles.Fil: Basak, Rituparna. New Jersey Institute of Technology; Estados UnidosFil: Kozlowski, Ryan. College of the Holly Cross; Estados UnidosFil: Pugnaloni, Luis Ariel. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kramar, M.. Oklahoma State University; Estados UnidosFil: Socolar, Joshua E. S.. University of Duke; Estados UnidosFil: Carlevaro, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física de Líquidos y Sistemas Biológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física de Líquidos y Sistemas Biológicos; ArgentinaFil: Kondic, Lou. New Jersey Institute of Technology; Estados Unido

<i>Leishmania</i>-containing PV specifically recruits LBs.

a, Differentiated THP-1 human macrophages were infected with L. donovani and recruitment of Bodipy 493/503 stained LBs (Green) by LAMP1 stained Ld-PVs (Red) were detected by confocal microscopy after 24 h of infection as described in Materials & Methods. Uninfected cells and cells incubated with latex beads or dead parasite were used as control. b, Recruitment of LipidTOX labelled LBs (Red) by LAMP1 stained Ld-PVs (Green) were determined after 24 h of infection as mentioned in Materials & Methods. Infection with dead parasites was used as control. Leishmania and macrophage nuclei were stained with DRAQ5 (Blue). c, To determine the recruitment of Perilipin by LAMP1 stained Ld-PVs (Red), Perilipin was immunostained with specific antibody (Green) in L. donovani infected and uninfected macrophages as described in Materials & Methods. Leishmania and macrophage nuclei were stained with DRAQ5 (Blue). d, Percentage of recruitment of different LBs on PVs containing live or fixed parasites were analyzed. All results are represented as mean ± S.D. of three independent experiments. Results of the indicated groups were analyzed by paired t test and levels of significance are indicated by P value. e, Determination of the number and size of LBs in L. donovani infected and uninfected macrophages were determined using appropriate software as described in Materials & Methods. Results are representative of mean±SE of 50 macrophages. f, Recruitment of ER membrane marker on LB and Ld-PV in L. donovani infected macrophages were determined by immunostaining the cells with calnexin specific antibody at indicated time points and analyzed by confocal microscopy. Uninfected cells and cells infected with dead parasite were used as control. Leishmania and macrophage nuclei were stained with DRAQ5 (Blue). All results are representative of three independent experiments.</p

Demonstrates the recruitment of host Rab7, Rab8 or Rab27 on Ld-PVs in <i>L</i>. <i>donovani</i> infected and uninfected macrophages and respective quantitation.

Demonstrates the recruitment of host Rab7, Rab8 or Rab27 on Ld-PVs in L. donovani infected and uninfected macrophages and respective quantitation.</p

Expression and recruitment of host Rab18 in <i>L</i>. <i>donovani</i> infected macrophages.

a, To determine the levels of different host Rab GTPases in L. donovani infected and uninfected macrophages, cells were lysed at indicated time points and Western blot analysis was carried out using specific human antibodies as mentioned in Materials & Methods. Actin was used as loading control. Right panel indicates the quantitation of the respective host Rab proteins. b, Levels of different host Rabs in L. donovani infected and uninfected differentiated macrophages at respective time points were determined by qPCR as described in Materials & Methods. The respective gene amplification was normalized using 18s rRNA as an internal control. All results are represented as mean ± S.D. of three independent experiments and normalized to uninfected control of respective Rabs arbitrarily chosen as one unit. Results of the indicated groups were analyzed by paired t test and levels of significance are indicated by P value. c, Levels of host mRNA of Rab18 in L. donovani infected and uninfected macrophages by limited dilution semi-quantitative RT-PCR. 18s rRNA was used as a control. d, Differentiated THP-1 macrophages were infected with L. donovani and recruitment of host Rab18 on LAMP1 labelled Ld-PVs were determined by immunostaining after 24 h of infection using specific antibody against human Rab18 (1:50) as described in Materials & Methods. THP-1 cells incubated with dead parasites and latex beads were used as control. e, Kinetics of host Rab18 recruitment on Ld-PVs was determined at indicated times as described in Materials & Methods. Right panel indicates the quantitation of host Rab18 recruitment on Ld-PVs at different time points. Leishmania and macrophage nuclei were stained with DRAQ5 (Blue). All results are representative of three independent experiments.</p

Shows the inhibition of Rab18 expression by the overexpression of specific siRNA in transfected macrophages.

Shows the inhibition of Rab18 expression by the overexpression of specific siRNA in transfected macrophages.</p