Apoptosis of<i>Ascogregarina taiwanensis</i>(Apicomplexa: Lecudinidae) which failed to migrate within its natural host

Autophagy and apoptosis, which could be induced by common stimuli, play crucial roles in development and disease. The functional relationship between autophagy and apoptosis is complex, due to the dual effects of autophagy. In the Bombyx Bm-12 cells, 20-hydroxyecdysone (20E) treatment or starvationinduced cell death, with autophagy preceding apoptosis. In response to 20E or starvation, BmATG8 was rapidly cleaved and conjugated with PE to form BmATG8-PE; subsequently, BmATG5 and BmATG6 were cleaved into BmATG5-tN and BmATG6-C, respectively. Reduction of expression of BmAtg5 or BmAtg6 by RNAi decreased the proportion of cells undergoing both autophagy and apoptosis after 20E treatment or starvation. Overexpression of BmAtg5 or BmAtg6 induced autophagy but not apoptosis in the absence of the stimuli, but promoted both autophagy and apoptosis induced by 20E or starvation. Notably, overexpression of cleavage site-deleted BmAtg5 or BmAtg6 increased autophagy but not apoptosis induced by 20E or starvation, whereas overexpression of BmAtg5-tN and BmAtg6-C was able to directly trigger apoptosis or promote the induced apoptosis. In conclusion, being cleaved into BmATG5-tN and BmATG6-C, BmATG5 and BmATG6 mediate apoptosis following autophagy induced by 20E or starvation in Bombyx Bm-12 cells, reflecting that autophagy precedes apoptosis in the midgut during Bombyx metamorphosis.

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“…54 The ANXA5-FITC and PI staining was monitored under a FV10-ASW confocal microscope (Olympus, Japan, Tokyo …”

Section: Anxa5-fitc and Pi Stainingmentioning

confidence: 99%

BmATG5 and BmATG6 mediate apoptosis following autophagy induced by 20-hydroxyecdysone or starvation

et al. 2016

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“…barretti has not been experimentally determined. There are multiple stages in the life cycle of Ascogregarina that could be interrupted resulting in few, to no, visible parasites detected during a midgut dissection: failure of ingested oocysts to release sporozoites, failure of trophozoites to attach, enter or develop in epithelial cells, and melanization or apoptosis of ingested parasites as has been observed in other mosquito‐ Ascogregarina species pairs (Chen, ; Chen, Huang, Fan‐Chiang, Liu, & Lee, ; Comiskey, Lowrie, & Wesson, ; Munstermann & Wesson, ). It is unclear, however, whether Ae .…”

Section: Discussionmentioning

confidence: 97%

Invasive species reduces parasite prevalence and neutralizes negative environmental effects on parasitism in a native mosquito

Westby

Sweetman

Horn

et al. 2019

Journal of Animal Ecology

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Invasive species research often focuses on direct effects of invasion on native ecosystems and less so on complex effects such as those influencing host–parasite interactions. However, invaders could have important effects on native host–parasite dynamics. Where infectious stages are ubiquitous and native host–pathogen specificity is strong, invasive less‐competent hosts may reduce the pool of infectious stages, effectively reducing native host–parasite encounter rate. Alternatively, invasive species could alter transmission via changes in native species abundance. Biotic and abiotic environmental factors can also impact disease dynamics by altering host or parasite condition. However, little is known about potential interactive effects of invasion and environmental context on native species disease dynamics. Moreover, experimental examinations of the mechanisms driving dilution effects are limited, but serve to provide tests of predictions leading to diversity–disease relationships. Using field and laboratory experiments, we tested competing hypotheses that an invasive species reduces the prevalence of a native parasite in its host by removing infectious propagules from the environment or by reducing native host abundance. In addition, we evaluated the role of detritus quantity as a resource base in mediating effects of the invasive species. Native parasite prevalence was reduced when the invasive species was present. Prevalence was also higher in high detritus habitats, although this effect was lost when the invasive species was present. The invasive species significantly reduced infectious propagules from the aquatic habitats. Presence of the invasive species had no effect on the native species abundance; thus, the reduction in parasitism was not due to changes in host density but through a reduction in infectious propagule encounters. We conclude that an invasive species can facilitate a native species by reducing parasite prevalence via a dilution effect and that these effects can be modified by resource level. Reductions in parasitism may have ripple effects throughout the community, altering the strength of competitive interactions, predation rates or coinfection with other pathogens. We advocate considering potential positive effects of invasive species on recipient communities, in addition to effects of invasions on host–parasite interactions to gain a broader understanding of the complex consequences of invasion.

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“…As no difference in the trophozoite stage was detected, this indicates an increase in parasite success caused by the per capita effect of a noncompetent, competing host. Trophozoite failure in the native host is often due to unsuccessful migration to the Malpighian tubules during pupation (Chen 1999, Chen et al 2013, which may be alleviated by prolonged larval development due to interspecific competition. In this system, parasite migration is cued not by parasite development, but by the timing of host hormonal cues, with short duration of the larval stage of the host equating to decreased time for parasite development (Chen 1999).…”

Section: Discussionmentioning

confidence: 99%

How do noncompetent hosts cause dilution of parasitism? Testing hypotheses for native and invasive mosquitoes

McIntire

Chappell

Juliano

2021

Ecology

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Parasite dilution occurs in varied systems, via multiple potential mechanisms. We used laboratory manipulation and field surveys to test for invader‐induced parasite dilution via two specific mechanisms: host–host competition and encounter reduction. In the laboratory, single Aedes triseriatus larvae were exposed to one of eight combinations of: parasitic Ascogregarina barretti, +/−1 cohabiting Aedes albopictus larva during parasite exposure, and +/−1 cohabiting A. albopictus larva after infectious parasite removal. Larval infection intensity (predicted to decrease via dilution by encounter reduction) was not significantly affected by A. albopictus. Adult infection prevalence and intensity (predicted to decrease via dilution by host–host competition) were significantly greater with A. albopictus, suggesting parasite amplification by interspecific competition, an effect potentially mediated by competition increasing A. triseriatus development time. In the field, we tested for effects of potential dilution host abundances on prevalence and abundance of A. barretti in A. triseriatus larvae. Piecewise path analysis yielded no evidence of host–host competition impacting parasitism in the field, but instead indicated a significant direct negative effect of Aedes spp. abundance on parasite abundance in A. triseriatus, which is consistent with dilution via encounter reduction in the field, but only in tree holes, not in man‐made containers. Our results are consistent with the hypothesis that a noncompetent invader can alter the native host–parasite relationship, but our laboratory and field data yield differing results. This difference is likely due to laboratory experiment testing for per capita effects of dilution hosts on parasitism, but field analysis testing for effects of dilution host abundance on parasitism. Individually, host–host competition with the invader amplifies, rather than dilutes, parasite success. In contrast, our path analysis is consistent with the hypothesis that dilution of parasitism results from increased abundance of noncompetent hosts in the field.

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Apoptosis ofAscogregarina taiwanensis(Apicomplexa: Lecudinidae) which failed to migrate within its natural host

Cited by 5 publications

References 34 publications

BmATG5 and BmATG6 mediate apoptosis following autophagy induced by 20-hydroxyecdysone or starvation

BmATG5 and BmATG6 mediate apoptosis following autophagy induced by 20-hydroxyecdysone or starvation

Invasive species reduces parasite prevalence and neutralizes negative environmental effects on parasitism in a native mosquito

How do noncompetent hosts cause dilution of parasitism? Testing hypotheses for native and invasive mosquitoes

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