scholarly journals Non-competitive resource exploitation within-mosquito shapes evolution of malaria virulence

2017 ◽  
Author(s):  
G. Costa ◽  
M. Gildenhard ◽  
M. Eldering ◽  
R.L. Lindquist ◽  
A.E. Hauser ◽  
...  
Keyword(s):  
Parasite Development ◽  
Mosquito Vector ◽  
Theoretical Studies ◽  
Resource Exploitation ◽  
Lipid Trafficking ◽  
Malaria Epidemiology ◽  
Virulence Evolution ◽  
Evolutionary Trajectories ◽  
Host Parasite

AbstractMalaria is a fatal human parasitic disease transmitted by a mosquito vector. The evolution of within-host malaria virulence has been the focus of many empirical and theoretical studies. However, the vector’s contribution to virulence evolution is not well understood. Here we explored how within-vector resource exploitation impacts evolutionary trajectories of within-host Plasmodium virulence. We developed a nested model of within-vector dynamics and malaria epidemiology, which predicted that non-competitive resource exploitation within-vector restricts within-host parasite virulence. To validate our model, we experimentally manipulated mosquito lipid trafficking and gauged within-vector parasite development, within-host infectivity and virulence. We found that mosquito-derived lipids determine within-host parasite virulence by shaping development and metabolic activity of transmissible sporozoites. Our findings uncover the role of within-vector environment in regulating within-host Plasmodium virulence and identify Plasmodium metabolic traits that may contribute to the evolution of malaria virulence.

Introduction: Ecological impact of parasitism on wildlife host populations

Parasitology ◽  
1995 ◽  
Vol 111 (S1) ◽  
pp. S3-S14 ◽  
Author(s):  
B. T. Grenfell ◽  
F. M. D. Gulland
Keyword(s):  
Population Dynamics ◽  
Potential Role ◽  
Evolutionary Ecology ◽  
Ecological Impact ◽  
Natural Populations ◽  
Parasite Population ◽  
Theoretical Studies ◽  
Host Parasite

The study of parasite population dynamics has been one of the major developments in ecology over the last 15 years (Kennedy, 1975). The seminal articles of Crofton (1971) and Anderson & May (1978, 1979; May & Anderson, 1978, 1979) began this process by illustrating the potential role of parasites in regulating or destabilizing the dynamics of wildlife host populations. Since then, a variety of empirical and theoretical studies (reviewed by Grenfell & Dobson, 1995) have explored the role of parasites in natural populations. In parallel with these population dynamical developments, a growing interest in the evolutionary ecology of parasites has also led to a large literature, examining the evolutionary impact of parasites and the importance of host-parasite coevolution (Hamilton, 1982; May & Anderson, 1990; Lively & Apanius, 1995; Read et al. 1995; Herre, this volume).

scholarly journals Chemical depletion of phagocytic immune cells inAnopheles gambiaereveals dual roles of mosquito hemocytes in anti-Plasmodiumimmunity

2019 ◽  
Vol 116 (28) ◽  
pp. 14119-14128 ◽  
Author(s):  
Hyeogsun Kwon ◽  
Ryan C. Smith
Keyword(s):  
Immune Cells ◽  
Vector Competence ◽  
Morphological Characteristics ◽  
Innate Immune ◽  
Parasite Development ◽  
Mosquito Vector ◽  
Dual Roles ◽  
Humoral Factors ◽  
Innate Immune Signaling

Mosquito immunity is composed of both cellular and humoral factors that provide protection from invading pathogens. Immune cells known as hemocytes, have been intricately associated with phagocytosis and innate immune signaling. However, the lack of genetic tools has limited hemocyte study despite their importance in mosquito anti-Plasmodiumimmunity. To address these limitations, we employ the use of a chemical-based treatment to deplete phagocytic immune cells inAnopheles gambiae,demonstrating the role of phagocytes in complement recognition and prophenoloxidase production that limit the ookinete and oocyst stages of malaria parasite development, respectively. Through these experiments, we also define specific subtypes of phagocytic immune cells inAn. gambiae, providing insights beyond the morphological characteristics that traditionally define mosquito hemocyte populations. Together, this study represents a significant advancement in our understanding of the roles of mosquito phagocytes in mosquito vector competence and demonstrates the utility of clodronate liposomes as an important tool in the study of invertebrate immunity.

scholarly journals Aedes aegypti SGS1 is critical for Plasmodium gallinaceum infection of both the mosquito midgut and salivary glands

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Bianca B. Kojin ◽  
Ines Martin-Martin ◽  
Helena R. C. Araújo ◽  
Brian Bonilla ◽  
Alvaro Molina-Cruz ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Life Cycle ◽  
Aedes Aegypti ◽  
Salivary Glands ◽  
Malaria Transmission ◽  
Parasite Development ◽  
Mosquito Vector ◽  
Plasmodium Gallinaceum ◽  
Mosquito Midgut

Abstract Background The invasion of the mosquito salivary glands by Plasmodium sporozoites is a critical step that defines the success of malaria transmission and a detailed understanding of the molecules responsible for salivary gland invasion could be leveraged towards control of vector-borne pathogens. Antibodies directed against the mosquito salivary gland protein SGS1 have been shown to reduce Plasmodium gallinaceum sporozoite invasion of Aedes aegypti salivary glands, but the specific role of this protein in sporozoite invasion and in other stages of the Plasmodium life cycle remains unknown. Methods RNA interference and CRISPR/Cas9 were used to evaluate the role of A. aegypti SGS1 in the P. gallinaceum life cycle. Results Knockdown and knockout of SGS1 disrupted sporozoite invasion of the salivary gland. Interestingly, mosquitoes lacking SGS1 also displayed fewer oocysts. Proteomic analyses confirmed the abolishment of SGS1 in the salivary gland of SGS1 knockout mosquitoes and revealed that the C-terminus of the protein is absent in the salivary gland of control mosquitoes. In silico analyses indicated that SGS1 contains two potential internal cleavage sites and thus might generate three proteins. Conclusion SGS1 facilitates, but is not essential for, invasion of A. aegypti salivary glands by P. gallinaceum and has a dual role as a facilitator of parasite development in the mosquito midgut. SGS1 could, therefore, be part of a strategy to decrease malaria transmission by the mosquito vector, for example in a transgenic mosquito that blocks its interaction with the parasite.

scholarly journals Mosquito Vector Production across Socio-Economic Divides in Baton Rouge, Louisiana

2021 ◽  
Vol 18 (4) ◽  
pp. 1420
Author(s):  
Rebeca de Jesús Crespo ◽  
Madison Harrison ◽  
Rachel Rogers ◽  
Randy Vaeth
Keyword(s):  
Low Income ◽  
Baton Rouge ◽  
Habitat Preferences ◽  
Abundant Species ◽  
Mosquito Larvae ◽  
Mosquito Vector ◽  
Mosquito Vectors ◽  
Low Income Groups ◽  
Socio Economic Factors

We investigated the role of socio-economic factors in the proliferation of mosquito vectors in two adjacent but socio-economically contrasting neighborhoods in Baton Rouge, LA, USA. We surveyed mosquito larvae habitat, mosquito larvae, and adult mosquitoes during the summer of 2020. We also evaluated the number of requests for mosquito abatement services in the years preceding the study for each area. While we did not find differences in terms of the most abundant species, Culex quinquefasicatus (F1,30 = 0.329, p = 0.57), we did find a higher abundance of mosquito habitats, particularly discarded tires, as well as larvae (z = 13.83, p < 0.001) and adults (F1,30 = 4.207, p = 0.049) of the species Aedes albopictus in the low-income neighborhood. In contrast, mosquito abatement requests were significantly higher in the high socio-economic neighborhood (z = −8.561, p < 0.001). This study shows how factors such as adjudicated properties, discarded tires and pest abatement requests can influence the abundance of mosquito vectors, disproportionately affecting low-income groups. This study also highlights how Aedes spp. may be better indicators than Culex spp. of socio-economic differences between nearby neighborhoods, due to their short flight range and habitat preferences, and this should be considered in future studies attempting to detect such disparities in the future.

scholarly journals The fibrinolytic system enables the onset of Plasmodium infection in the mosquito vector and the mammalian host

2021 ◽  
Vol 7 (6) ◽  
pp. eabe3362 ◽  
Author(s):  
Thiago Luiz Alves e Silva ◽  
Andrea Radtke ◽  
Amanda Balaban ◽  
Tales Vicari Pascini ◽  
Zarna Rajeshkumar Pala ◽  
...  
Keyword(s):  
Plasminogen Activators ◽  
Fibrinolytic System ◽  
Matrix Proteins ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Plasminogen Activation ◽  
Plasmodium Infection ◽  
Human Plasminogen ◽  
Vertebrate Hosts

Plasmodium parasites must migrate across proteinaceous matrices to infect the mosquito and vertebrate hosts. Plasmin, a mammalian serine protease, degrades extracellular matrix proteins allowing cell migration through tissues. We report that Plasmodium gametes recruit human plasminogen to their surface where it is processed into plasmin by corecruited plasminogen activators. Inhibition of plasminogen activation arrests parasite development early during sexual reproduction, before ookinete formation. We show that increased fibrinogen and fibrin in the blood bolus, which are natural substrates of plasmin, inversely correlate with parasite infectivity of the mosquito. Furthermore, we show that sporozoites, the parasite form transmitted by the mosquito to humans, also bind plasminogen and plasminogen activators on their surface, where plasminogen is activated into plasmin. Surface-bound plasmin promotes sporozoite transmission by facilitating parasite migration across the extracellular matrices of the dermis and of the liver. The fibrinolytic system is a potential target to hamper Plasmodium transmission.

scholarly journals Anomalous transport due to Weyl fermions in the chiral antiferromagnets Mn3X, X = Sn, Ge

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Taishi Chen ◽  
Takahiro Tomita ◽  
Susumu Minami ◽  
Mingxuan Fu ◽  
Takashi Koretsune ◽  
...  
Keyword(s):  
Technological Innovation ◽  
Essential Role ◽  
Condensed Matter ◽  
Zero Field ◽  
Theoretical Studies ◽  
Planar Hall Effect ◽  
Topological States ◽  
Experimental And Theoretical Studies ◽  
Weyl Fermions

AbstractThe recent discoveries of strikingly large zero-field Hall and Nernst effects in antiferromagnets Mn3X (X = Sn, Ge) have brought the study of magnetic topological states to the forefront of condensed matter research and technological innovation. These effects are considered fingerprints of Weyl nodes residing near the Fermi energy, promoting Mn3X (X = Sn, Ge) as a fascinating platform to explore the elusive magnetic Weyl fermions. In this review, we provide recent updates on the insights drawn from experimental and theoretical studies of Mn3X (X = Sn, Ge) by combining previous reports with our new, comprehensive set of transport measurements of high-quality Mn3Sn and Mn3Ge single crystals. In particular, we report magnetotransport signatures specific to chiral anomalies in Mn3Ge and planar Hall effect in Mn3Sn, which have not yet been found in earlier studies. The results summarized here indicate the essential role of magnetic Weyl fermions in producing the large transverse responses in the absence of magnetization.

scholarly journals Ecosystem dynamics: exploring the interplay within fintech entrepreneurial ecosystems

2021 ◽  
Author(s):  
Ahmad Alaassar ◽  
Anne-Laure Mention ◽  
Tor Helge Aas
Keyword(s):  
New Ventures ◽  
Ecosystem Dynamics ◽  
Resource Exploitation ◽  
Cultural Perspective ◽  
Structured Interviews ◽  
Opportunity Identification ◽  
Entrepreneurial Ecosystems ◽  
Regulatory Dynamics ◽  
Financial Technology

AbstractScholars and practitioners continue to recognize the crucial role of entrepreneurial ecosystems (EEs) in creating a conducive environment for productive entrepreneurship. Although EEs are fundamentally interaction systems of hierarchically independent yet mutually dependent actors, few studies have investigated how interactions among ecosystem actors drive the entrepreneurial process. Seeking to address this gap, this paper explores how ecosystem actor interactions influence new ventures in the financial technology (fintech) EE of Singapore. Guided by an EE framework and the use of an exploratory-abductive approach, empirical data from semi-structured interviews is collected and analyzed. The findings reveal four categories representing both the relational perspective, which features interaction and intermediation dynamics, and the cultural perspective, which encompasses ecosystem development and regulatory dynamics. These categories help explain how and why opportunity identification and resource exploitation are accelerated or inhibited for entrepreneurs in fintech EEs. The present study provides valuable contributions to scholars and practitioners interested in EEs and contributes to the academic understanding of the emerging fintech phenomenon.

The possible role of the frontal and sub-parietal gland systems of the pentastomidReighardia sternae(Diesing, 1864) in the evasion of the host immune response

Parasitology ◽  
1979 ◽  
Vol 78 (1) ◽  
pp. 53-66 ◽  
Author(s):  
J. Riley ◽  
J. L. James ◽  
A. A. Banaja
Keyword(s):  
Immune Response ◽  
Alternative Explanation ◽  
Surface Membrane ◽  
Membrane System ◽  
Host Immune Response ◽  
Entire Surface ◽  
Strong Immune Response ◽  
Concomitant Immunity ◽  
Host Parasite

SUMMARYThe frontal and sub-parietal glands of the pentastomidReighardia sternaeelaborate lamellate secretion which is poured on to the cuticle. The entire surface of the cuticle, including the mouth, hook pits and reproductive apertures, is coated with secretion. Electron microscope studies indicate that the glands are continuously active, which implies a turnover of surface membranes. The postulated function of these membranes is to protect certain vital areas of the host–parasite interface, notably the pores of ion-transporting cells, from the host immune response. The available evidence suggests that pentastomids do evoke a strong immune response but since most are long-lived they must circumvent it. We believe the surface membrane system to be instrumental in this. Studies on another pentastomid,Porocephalus crotaliin rats have shown that an immune response stimulated by a primary infection will kill subsequent infections and that the surface membranes are strongly immunogenic. Obvious parallels between this situation and that of schistosome infections in mammals are discussed. An alternative explanation of concomitant immunity is proposed.

scholarly journals B Chromosomes in Populations of Mammals Revisited

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 487 ◽  
Author(s):  
Mladen Vujošević ◽  
Marija Rajičić ◽  
Jelena Blagojević
Keyword(s):  
Mammalian Species ◽  
B Chromosome ◽  
Molecular Techniques ◽  
B Chromosomes ◽  
General View ◽  
Protein Coding ◽  
Host Parasite Interactions ◽  
Quantitative Characteristics ◽  
Host Parasite

The study of B chromosomes (Bs) started more than a century ago, while their presence in mammals dates since 1965. As the past two decades have seen huge progress in application of molecular techniques, we decided to throw a glance on new data on Bs in mammals and to review them. We listed 85 mammals with Bs that make 1.94% of karyotypically studied species. Contrary to general view, a typical B chromosome in mammals appears both as sub- or metacentric that is the same size as small chromosomes of standard complement. Both karyotypically stable and unstable species possess Bs. The presence of Bs in certain species influences the cell division, the degree of recombination, the development, a number of quantitative characteristics, the host-parasite interactions and their behaviour. There is at least some data on molecular structure of Bs recorded in nearly a quarter of species. Nevertheless, a more detailed molecular composition of Bs presently known for six mammalian species, confirms the presence of protein coding genes, and the transcriptional activity for some of them. Therefore, the idea that Bs are inert is outdated, but the role of Bs is yet to be determined. The maintenance of Bs is obviously not the same for all species, so the current models must be adapted while bearing in mind that Bs are not inactive as it was once thought.

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