scholarly journals Multi-locus characterization and phylogenetic inference of Leishmania spp. in snakes from Northwest China

2019 ◽  
Author(s):  
Han Chen ◽  
Jiao Li ◽  
Junrong Zhang ◽  
Jinlei He ◽  
Jianhui Zhang ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Natural Infection ◽  
Protozoan Parasite ◽  
Phylogenetic Inference ◽  
Northwest China ◽  
Future Research ◽  
Network Analyses ◽  
Epidemic Area ◽  
Potential Reservoir ◽  
Leishmania Spp

AbstractBackgroundLeishmaniasis caused by protozoan parasite Leishmania is a neglected disease which is endemic in the northwest of China. Reptiles were considered to be the potential reservoir hosts for mammalian Leishmaniasis, and Leishmania had been detected in lizards from the epidemic area in the northwest of China. To date, few studies are focused on the natural infection of snakes with Leishmania.MethodsIn this study, 15 snakes captured from 10 endemic foci in the northwest of China were detected Leishmania spp. on the base of mitochondrial cytochrome b, heat shock protein 70 gene and ribosomal internal transcribed spacer 1 regions, and identified with phylogenetic and network analyses.ResultIn total, Leishmania gene was found in 7 snakes. The phylogenetic inference trees and network analysis suggests that the species identification was confirmed as Leishmania donovani, Leishmania turanica and Leishmania sp.ConclusionOur work is the first time to investigate the natural Leishmania spp. infection of snakes in the northwest of China. Mammalian Leishmania was discovered in snakes and the reptilian Leishmania was closely related to the clinical strains both prompt the importance of snakes in the disease cycle. To indicate the epidemiological involvement of snakes, a wide sample size in epidemic area and the pathogenic features of reptilian Leishmania promastigotes are recommended in the future research.

scholarly journals Molecular Detection of Leishmania major in Hemiechinus auritus, A Potential Reservoir of Zoonotic Cutaneous Leishmaniasis in Damghan, Iran

2019 ◽  
Author(s):  
Behrad Pourmohammadi ◽  
Sadegh Mohammadi-Azni
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Leishmania Major ◽  
Natural Infection ◽  
Leishmania Infection ◽  
Northern Iran ◽  
Zoonotic Cutaneous Leishmaniasis ◽  
Potential Reservoir ◽  
Leishmania Spp ◽  
First Time ◽  
Leishmania Parasites

Background: Zoonotic cutaneous leishmaniasis caused by Leishmania major is endemic in 17 of 31 Iranian provinces. Various species of rodents have been introduced as the main reservoirs of the disease. This study was conducted to de­termine the natural infection of hedgehogs with Leishmania spp. in an endemic area of the disease, northern Iran. Methods: Fifteen long-eared hedgehogs were captured alive during 18 months study period, from Apr 2015 to Sep 2016, in Damghan City, Semnan Province, Iran. The animals were identified using apparent characteristics and to de­termine the Leishmania infection, impression smears were prepared from their ear lobes, hind feet, livers, and spleens. Micro­scopic examination and semi-nested PCR were applied to determine the infection and to identify the parasites species respectively. Results: All examined animals were identified as Hemiechinus auritus (Family: Erinaceidae). In microscopic examina­tion, 8 (53.3%) samples were shown to be infected with Leishmania parasites. The higher and lower rate of the infection was observed in the ears as well as the feet and in the liver specimens, 53.3%, and 33.3% respectively. Forty percent (6/ 15) of the samples were molecularly positive and all were identified as L. major parasites. All the examined animals in au­tumn and 50% of them in summer were shown to be infected with Leishmania parasites. Conclusion: This study demonstrated the natural infection of H. auritus with L. major for the first time in Damghan City and introduced these mammals as new potential reservoirs of ZCL in the study area.

scholarly journals Multi-locus characterization and phylogenetic inference of Leishmania spp. in snakes from Northwest China

PLoS ONE ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. e0210681 ◽  
Author(s):  
Han Chen ◽  
Jiao Li ◽  
Junrong Zhang ◽  
Xianguang Guo ◽  
Jinlong Liu ◽  
...  
Keyword(s):  
Phylogenetic Inference ◽  
Northwest China ◽  
Leishmania Spp

Natural and synthetic indirubins as potent and selective inhibitors of the protozoan parasite Leishmania donovani

Planta Medica ◽  
2007 ◽  
Vol 73 (09) ◽  
Author(s):  
E Xingi ◽  
D Smirlis ◽  
S Bisti ◽  
V Myrianthopoulos ◽  
P Magiatis ◽  
...  
Keyword(s):  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Selective Inhibitors ◽  
Parasite Leishmania ◽  
Natural And Synthetic

Conceptual Structure of Lodging-Context Studies: 1990-2016

2019 ◽  
Vol 43 (4) ◽  
pp. 573-594 ◽  
Author(s):  
Mehmet Ali Köseoglu ◽  
Fevzi Okumus ◽  
Eka Diraksa Putra ◽  
Mehmet Yildiz ◽  
Ismail Cagri Dogan
Keyword(s):  
Human Resource Management ◽  
Human Resource ◽  
Conceptual Structure ◽  
Early Growth ◽  
Network Density ◽  
Future Research ◽  
Economic Activities ◽  
Knowledge Domain ◽  
Resource Based View ◽  
Network Analyses

The purpose of this article is to analyze the conceptual structure of lodging-context research. In this regard, 2,632 articles published between 1990 and 2016 were analyzed utilizing network analyses. We find that the knowledge domain of lodging has been expanding, with greater focus on the business and economic activities of hotels. As the network density is low, lodging as a field is at a relatively early growth level and it is open for multidisciplinary collaborations. Articles related to strategy, marketing, and human resource management are relatively mature and well developed. However, some areas such as resource-based view, and cruise business still remain undeveloped and immature. Moreover, as one of the first studies in this field, this work provides an inclusive evaluation of the results, limitations, and suggestions for future research.

Developmental gene expression in Leishmania donovani: differential cloning and analysis of an amastigote-stage-specific gene

1994 ◽  
Vol 14 (5) ◽  
pp. 2975-2984
Author(s):  
H Charest ◽  
G Matlashewski
Keyword(s):  
Life Cycle ◽  
Leishmania Donovani ◽  
Repetitive Sequences ◽  
Protozoan Parasite ◽  
Life Cycle Stage ◽  
Immune Serum ◽  
Sand Fly ◽  
Specific Gene ◽  
Reading Frame ◽  
Developmental Gene Expression

Leishmania protozoans are the causative agents of leishmaniasis, a major parasitic disease in humans. During their life cycle, Leishmania protozoans exist as flagellated promastigotes in the sand fly vector and as nonmotile amastigotes in the mammalian hosts. The promastigote-to-amastigote transformation occurs in the phagolysosomal compartment of the macrophage cell and is a critical step for the establishment of the infection. To study this cytodifferentiation process, we differentially screened an amastigote cDNA library with life cycle stage-specific cDNA probes and isolated seven cDNAs representing amastigote-specific transcripts. Five of these were closely related (A2 series) and recognized, by Northern (RNA) blot analyses, a 3.5-kb transcript in amastigotes and in amastigote-infected macrophages. Expression of the amastigote-specific A2 gene was induced in promastigotes when they were transferred from culture medium at 26 degrees C and pH 7.4 to medium at 37 degrees C and pH 4.5, conditions which mimic the macrophage phagolysosomal environment. A2 genes are clustered in tandem arrays, and a 6-kb fragment corresponding to a unit of the cluster was cloned and partially sequenced. An open reading frame found within the A2-transcribed region potentially encoded a 22-kDa protein containing repetitive sequences. The recombinant A2 protein produced in Escherichia coli cells was specifically recognized by immune serum from a patient with visceral leishmaniasis. The A2 protein repetitive element has strong homology with an S antigen of Plasmodium falciparum, the protozoan parasite responsible for malaria. Both the A2 protein of Leishmania donovani and the S antigen of P. falciparum are stage specific and developmentally expressed in mammalian hosts.

scholarly journals Genetic Validation of Leishmania donovani Lysyl-tRNA Synthetase Shows that It Is Indispensable for Parasite Growth and Infectivity

mSphere ◽  
2017 ◽  
Vol 2 (4) ◽  
Author(s):  
Sanya Chadha ◽  
N. Arjunreddy Mallampudi ◽  
Debendra K. Mohapatra ◽  
Rentala Madhubala
Keyword(s):  
Visceral Leishmaniasis ◽  
Leishmania Donovani ◽  
Essential Gene ◽  
Protozoan Parasite ◽  
Protein Translation ◽  
Trna Synthetase ◽  
Parasite Growth ◽  
Coding Sequences ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases

ABSTRACT Leishmania donovani is a protozoan parasite that causes visceral leishmaniasis. Increasing resistance and severe side effects of existing drugs have led to the need to identify new chemotherapeutic targets. Aminoacyl-tRNA synthetases (aaRSs) are ubiquitous and are required for protein synthesis. aaRSs are known drug targets for bacterial and fungal pathogens. Here, we have characterized and evaluated the essentiality of L. donovani lysyl-tRNA synthetase (LdLysRS). Two different coding sequences for lysyl-tRNA synthetases are annotated in the Leishmania genome database. LdLysRS-1 (LdBPK_150270.1), located on chromosome 15, is closer to apicomplexans and eukaryotes, whereas LdLysRS-2 (LdBPK_300130.1), present on chromosome 30, is closer to bacteria. In the present study, we have characterized LdLysRS-1. Recombinant LdLysRS-1 displayed aminoacylation activity, and the protein localized to the cytosol. The LdLysRS-1 heterozygous mutants had a restrictive growth phenotype and attenuated infectivity. LdLysRS-1 appears to be an essential gene, as a chromosomal knockout of LdLysRS-1 could be generated when the gene was provided on a rescuing plasmid. Cladosporin, a fungal secondary metabolite and a known inhibitor of LysRS, was more potent against promastigotes (50% inhibitory concentration [IC50], 4.19 µM) and intracellular amastigotes (IC50, 1.09 µM) than were isomers of cladosporin (3-epi-isocladosporin and isocladosporin). These compounds exhibited low toxicity to mammalian cells. The specificity of inhibition of parasite growth caused by these inhibitors was further assessed using LdLysRS-1 heterozygous mutant strains and rescue mutant promastigotes. These inhibitors inhibited the aminoacylation activity of recombinant LdLysRS. Our data provide a framework for the development of a new class of drugs against this parasite. IMPORTANCE Aminoacyl-tRNA synthetases are housekeeping enzymes essential for protein translation, providing charged tRNAs for the proper construction of peptide chains. These enzymes provide raw materials for protein translation and also ensure fidelity of translation. L. donovani is a protozoan parasite that causes visceral leishmaniasis. It is a continuously proliferating parasite that depends heavily on efficient protein translation. Lysyl-tRNA synthetase is one of the aaRSs which charges lysine to its cognate tRNA. Two different coding sequences for lysyl-tRNA synthetases (LdLysRS) are present in this parasite. LdLysRS-1 is closer to apicomplexans and eukaryotes, whereas LdLysRS-2 is closer to bacteria. Here, we have characterized LdLysRS-1 of L. donovani. LdLysRS-1 appears to be an essential gene, as the chromosomal null mutants did not survive. The heterozygous mutants showed slower growth kinetics and exhibited attenuated virulence. This study also provides a platform to explore LdLysRS-1 as a potential drug target.

scholarly journals Role of cAMP Signaling in the Survival and Infectivity of the Protozoan Parasite, Leishmania donovani

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Arunima Biswas ◽  
Arijit Bhattacharya ◽  
Pijush K. Das
Keyword(s):  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Camp Level ◽  
Camp Signaling ◽  
Regulatory Subunit ◽  
Developmentally Regulated ◽  
Camp Phosphodiesterase ◽  
Environmental Trigger ◽  
Dependent Protein ◽  
Camp Metabolism

Leishmania donovani, while invading macrophages, encounters striking shift in temperature and pH (from 22°C and pH 7.2 to 37°C and pH 5.5), which act as the key environmental trigger for differentiation, and increases cAMP level and cAMP-mediated responses. For comprehensive understanding of cAMP signaling, we studied the enzymes related to cAMP metabolism. A stage-specific and developmentally regulated isoform of receptor adenylate cyclase (LdRACA) showed to regulate differentiation-coupled induction of cAMP. The soluble acidocalcisomal pyrophosphatase, Ldvsp1, was the major isoform regulating cAMP level in association with LdRACA. A differentially expressed soluble cytosolic cAMP phosphodiesterase (LdPDEA) might be related to infection establishment by shifting trypanothione pool utilization bias toward antioxidant defense. We identified and cloned a functional cAMP-binding effector molecule from L. donovani (a regulatory subunit of cAMP-dependent protein kinase, LdPKAR) that may modulate metacyclogenesis through induction of autophagy. This study reveals the significance of cAMP signaling in parasite survival and infectivity.

scholarly journals Social learning and networks in Nestor parrots

2021 ◽  
Author(s):  
◽  
Daniel Donoghue
Keyword(s):  
Social Network ◽  
Social Learning ◽  
Tool Use ◽  
Social Information ◽  
Habitat Modification ◽  
Future Research ◽  
Video Playback ◽  
Food Aversion ◽  
Network Analyses ◽  
The Social

<p>Social learning and network analyses are theorised to be of great utility in the context of behavioural conservation. For example, harnessing a species’ capacity for social learning may allow researchers to seed useful information into populations, while network analyses could provide a useful tool to monitor community stability, and predict pathways of pathogen transfer. Thus, an understanding of how individuals learn and the nature of the social networks within a population could enable the development of new behavioural based conservation interventions for species facing rapid environmental change, such as human-induced habitat modification. Parrots, the most threatened avian order worldwide, are notably underrepresented in the social learning and social network literature. This thesis addresses this knowledge gap by exploring social learning and networks using two endangered species of parrot; kākā (Nestor meridionalis) and kea (Nestor notabilis). The first study explores social learning of tool use in captive kea, using a trained kea demonstrator. The results from this experiment indicate that both social learning and play behaviour facilitated the uptake of tool use, and suggests that kea are highly sensitive to social information even when presented with complex tasks. The second study assesses whether wild kākā can socially learn novel string-pulling and food aversion behaviours from video playbacks of conspecific demonstrators. Although there was no evidence to indicate that kākā learn socially, these individuals also show no notable reaction to video playback of a familiar predator. Therefore, these results are likely due to difficulties in interpreting information on the screens, and not necessarily a reflection of their ability to perceive social information. In the final study, social network analysis (SNA) was performed to map social connectivity within wellington’s urban kākā population. SNA indicates that kākā form non-random social bonds, selectively associating with some individuals more than others, and also show high levels of dissimilarity in community composition at different feeding sites. Taken together, these results provide rare empirical evidence of social learning in a parrot species and suggest that even complicated seeded behaviours can quickly spread to other individuals. These findings may also be indicative of the difficulties in conducting video playback experiments in wild conditions, which is an area in need of future research. Overall, these findings contribute to the very limited body of research on social learning and networks in parrots, and provide information of potential value in the management of these species.</p>

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