Absorption and transport of radioactive tracers in the midgut of the malaria mosquito, Anopheles stephensi

Schneider, Monroe; Rudin, W.; Hecker, Hermann

doi:10.1016/s0889-1605(86)80006-4

Cited by 25 publications

(7 citation statements)

References 29 publications

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“…This decrease was likely due to diuresis, dispersal of the radiolabeled peptides into the rest of the body, enzymatic degradation in the midgut and 125 I-tyrosine incorporation in newly synthesized proteins in other tissues. A similar trend was observed for 125 I-labeled BSA fed to A. stephensi where ~85% of radiolabeled material was lost in diuresis products by 48h after feeding (Schneider et al, 1986).…”

Section: Discussionsupporting

confidence: 72%

Human IGF1 extends lifespan and enhances resistance to Plasmodium falciparum infection in the malaria vector Anopheles stephensi

Drexler

Nuss

Hauck

et al. 2013

Journal of Experimental Biology

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SUMMARYThe highly conserved insulin/insulin-like growth factor (IGF) signaling (IIS) pathway regulates metabolism, development, lifespan and immunity across a wide range of organisms. Previous studies have shown that human insulin ingested in the blood meal can activate mosquito IIS, resulting in attenuated lifespan and increased malaria parasite infection. Because human IGF1 is present at higher concentrations in blood than insulin and is functionally linked with lifespan and immune processes, we predicted that human IGF1 ingested in a blood meal would affect lifespan and malaria parasite infection in the mosquito Anopheles stephensi. Here we demonstrate that physiological levels of ingested IGF1, like insulin, can persist intact in the blood-filled midgut for up to 30h and disseminate into the mosquito body, and that both peptides activate IIS in mosquito cells and midgut. At these same levels, ingested IGF1 alone extended average mosquito lifespan by 23% compared with controls and, more significantly, when ingested in infected blood meals, reduced the prevalence of Plasmodium falciparum-infected mosquitoes by >20% and parasite load by 35-50% compared with controls. Thus, the effects of ingested IGF1 on mosquito lifespan and immunity are opposite to those of ingested insulin. These results offer the first evidence that insect cells can functionally discriminate between mammalian insulin and IGF1. Further, in light of previous success in genetically targeting IIS to alter mosquito lifespan and malaria parasite transmission, this study indicates that a more complete understanding of the IIS-activating ligands in blood can be used to optimize transgenic strategies for malaria control.

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Section: Discussionsupporting

confidence: 72%

Human IGF1 extends lifespan and enhances resistance to Plasmodium falciparum infection in the malaria vector Anopheles stephensi

Drexler

Nuss

Hauck

et al. 2013

Journal of Experimental Biology

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“…Because mature ookinetes have not been formed at 12 h after a blood meal, this implies that the PM, although incomplete, is already present, when ookinetes start migration to the epithelium. On the contrary, it has been reported that PM is sometimes not found in A. stephensi (Schneider et al ., 1986). In our TEM observation, laminar structure of the PM was not observed clearly at 21 h after a blood meal.…”

Section: Discussionmentioning

confidence: 90%

A calcium‐dependent protein kinase regulates Plasmodium ookinete access to the midgut epithelial cell

Ishino¹,

Orito²,

Chinzei³

et al. 2005

Molecular Microbiology

206

187

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SummaryPlasmodium parasites are fertilized in the mosquito midgut and develop into motile zygotes, called ookinetes, which invade the midgut epithelium. Here we show that a calcium-dependent protein kinase, CDPK3, of the rodent malarial parasite ( Plasmodium berghei ) is produced in the ookinete stage and has a critical role in parasite transmission to the mosquito vector. Targeted disruption of the CDPK3 gene decreased ookinete ability to infect the mosquito midgut by nearly two orders of magnitude. Electron microscopic analyses demonstrated that the disruptant ookinetes could not access midgut epithelial cells by traversing the layer covering the cell surface. An in vitro migration assay showed that these ookinetes lack the ability to migrate through an artificial gel, suggesting that this defect caused their failure to access the epithelium. In vitro migration assays also suggested that this motility is induced in the wild type by mobilization of intracellular stored calcium. These results indicate that a signalling pathway involving calcium and CDPK3 regulates ookinete penetration of the layer covering the midgut epithelium. Because humans do not possess CDPK family proteins, CDPK3 is a good target for blocking malarial transmission to the mosquito vector.

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“…However, when mosquitoes were fed a protein meal that had been partially digested by bovine trypsin (which mimics the activity of early trypsin) transcription of late trypsin occurred at control levels (Barillas-Mury et al, 1995). Interestingly, the mosquito also uses these free amino acids as building blocks for the synthesis of late trypsin as was shown by Schneider et al in 1986 when they observed radioactive amino acids being incorporated into the protease indicating that they may serve as a rate-limiting MSc Thesis -EK Pacey; McMaster University -Department of Biology 7 step in the production of the enzyme. This unique regulatory system allows mosquitoes to control whether or not they commit the energy to digesting a blood meal and lets them remove low-quality meals quickly and efficiently so that they are able to acquire a more nutritious meal in the near future.…”

Section: Trypsinmentioning

confidence: 97%

Transport of H+, Na+ and K+ across the posterior midgut of blood-fed mosquitoes (Aedes aegypti)

Pacey

O’Donnell

2014

Journal of Insect Physiology

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Mosquitoes pose significant threats to human health because they act as vectors for disease causing viruses and protozoans. Indeed, Aedes aegypti is known as the Yellow Fever Mosquito because of its role as a vector for viral infections that kill thousands of people each year. A more thorough understanding of mosquito physiology will aid development of novel control strategies. Previous work on ion transport across the midgut has been focused primarily on larval A. aegypti, while research on the midgut of the adult stage is less complete. The posterior midgut of the adult female is of particular interest because it is used for the storage and digestion of the blood meal which is required for the production of eggs. This study used an array of electrophysiological methodologies such as the Scanning Ion Electrode Technique (SIET) in order to elucidate the patterns and mechanisms of Na + , H + and K + transport across the posterior midgut at intervals during postprandial diuresis and digestion of the blood meal. Measurements of transepithelial potential indicated that the lumen was at its most negative (-13.2 mV) three hours after the blood meal and then gradually became less negative during the time course of digestion. Na + was absorbed (from lumen to bath) at all intervals after the blood meal (6 min, 30 min, 2h, 24 h); calculations of the electrochemical potential indicated that absorption required active transport. H + absorption at all times (6 min -48 h) after the blood meal was also active (i.e. against the electrochemical gradient for H + ) and was greatly reduced by inhibition of carbonic anhydrase. K + transport across the midgut exhibited two distinct phases. During diuresis, luminal concentrations of K + were in the range 24 -28 mM and secretion into the midgut was opposed by the electrochemical iv gradient, indicating active transport. After diuresis, during blood meal digestion, concentrations of K + in the midgut contents were high (95 -134 mM) and absorption of K + was favoured by the electrochemical gradient. K + absorption was sensitive to the channel blocker Ba 2+ during this period.v Acknowledgements

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Absorption and transport of radioactive tracers in the midgut of the malaria mosquito, Anopheles stephensi

Cited by 25 publications

References 29 publications

Human IGF1 extends lifespan and enhances resistance to Plasmodium falciparum infection in the malaria vector Anopheles stephensi

Human IGF1 extends lifespan and enhances resistance to Plasmodium falciparum infection in the malaria vector Anopheles stephensi

A calcium‐dependent protein kinase regulates Plasmodium ookinete access to the midgut epithelial cell

Transport of H+, Na+ and K+ across the posterior midgut of blood-fed mosquitoes (Aedes aegypti)

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