scholarly journals ECDYSONE-MEDIATED STIMULATION OF DOPA DECARBOXYLASE ACTIVITY AND ITS RELATIONSHIP TO OVARIAN DEVELOPMENT IN AEDES AEGYPTI

1974 ◽  
Vol 61 (2) ◽  
pp. 454-465 ◽  
Author(s):  
Dorothy A. Schlaeger ◽  
Morton S. Fuchs ◽  
Suk-Hee Kang
Keyword(s):  
Aedes Aegypti ◽  
Blood Meal ◽  
Ovarian Development ◽  
Blood Feeding ◽  
Dopa Decarboxylase ◽  
Decarboxylase Activity ◽  
Molting Hormone ◽  
Radioimmune Assay ◽  
Juvenile Hormone Mimic ◽  
Stimulation Of

Very little dopa decarboxylase activity is detectable in adult female mosquitoes Aedes aegypti which have not been allowed to engorge blood. However, when such females are injected with the molting hormone ß-ecdysone a marked stimulation of this enzyme's activity is observable. No stimulation is observed in males similarly injected, nor in females injected with cholesterol or a juvenile hormone mimic. In addition, ecdysone injection initiates ovarian development in these anautogenous non-blood-fed mosquitoes. The extent of stimulation in both cases is dependent upon the amount of ß-ecdysone administered. These results suggested that ecdysone may play a role in ovarian development in Aedes and led us to hypothesize that a normal blood meal may trigger the synthesis, activation, or release of this hormone endogenously. Using the radioimmune assay for ecdysone developed by Borst and O'Connor (Science [Wash. D. C.] 178:4–18.), we found that the titer of an antigenic-positive material, presumably ecdysone or a closely related analogue, substantially increased 24 h after blood feeding, thereby supporting our postulation.

The influence of the brain hormone on retention of blood in the mid-gut of the mosquito Aedes aegypti (L.) III. The involvement of the ovaries and ecdysone

1979 ◽  
Vol 205 (1160) ◽  
pp. 411-421 ◽  
Keyword(s):  
Aedes Aegypti ◽  
Blood Meal ◽  
Ovarian Development ◽  
Neurosecretory Cells ◽  
Direct Result ◽  
Corpus Cardiacum ◽  
Egg Development ◽  
The Brain

Most female mosquitoes require a blood-meal in order to produce mature oöcytes. An egg development neurosecretory hormone (EDNH), which is produced in the medial neurosecretory cells (m. n. c.) of the brain and stored in the corpus cardiacum, is released into the haemolymph following the ingestion of blood and is essential for the promotion of ovarian development to maturity. It has been shown that a factor from the m. n. c., presumably EDNH, is necessary if the blood-meal is to be retained in the mid-gut until the oöcytes approach maturity. The present paper shows that retention is not a direct result of the action of EDNH, but is dependent on the ovaries and may well involve ecdysone. Removal of the ovaries before a blood-meal leads to early haem-defaecation, but delay can be restored by injection of ecdysterone. Sub-threshold feeders and mosquitoes decapitated immediately after the intake of blood, each of which would be expected to eliminate the blood-meal early, also show a delay in the onset of haem-defaecation when injected with ecdysterone. Further, both in ovariectomized insects and sub-threshold feeders the time of onset of haem-defaecation is associated with the dose of ecdysterone given.

scholarly journals microRNA-309 targets the Homeobox gene SIX4 and controls ovarian development in the mosquito Aedes aegypti

2016 ◽  
Vol 113 (33) ◽  
pp. E4828-E4836 ◽  
Author(s):  
Yang Zhang ◽  
Bo Zhao ◽  
Sourav Roy ◽  
Tusar T. Saha ◽  
Vladimir A. Kokoza ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Molecular Mechanisms ◽  
Ovarian Development ◽  
Ovarian Tissue ◽  
Critical Role ◽  
Homeobox Gene ◽  
Target Prediction ◽  
Blood Feeding ◽  
Primary Follicle ◽  
Specific Manifestation

Obligatory blood-triggered reproductive strategy is an evolutionary adaptation of mosquitoes for rapid egg development. It contributes to the vectorial capacity of these insects. Therefore, understanding the molecular mechanisms underlying reproductive processes is of particular importance. Here, we report that microRNA-309 (miR-309) plays a critical role in mosquito reproduction. A spatiotemporal expression profile of miR-309 displayed its blood feeding-dependent onset and ovary-specific manifestation in female Aedes aegypti mosquitoes. Antagomir silencing of miR-309 impaired ovarian development and resulted in nonsynchronized follicle growth. Furthermore, the genetic disruption of miR-309 by CRISPR/Cas9 system led to the developmental failure of primary follicle formation. Examination of genomic responses to miR-309 depletion revealed that several pathways associated with ovarian development are down-regulated. Comparative analysis of genes obtained from the high-throughput RNA sequencing of ovarian tissue from the miR-309 antagomir-silenced mosquitoes with those from the in silico computation target prediction identified that the gene-encoding SIX homeobox 4 protein (SIX4) is a putative target of miR-309. Reporter assay and RNA immunoprecipitation confirmed that SIX4 is a direct target of miR-309. RNA interference of SIX4 was able to rescue phenotypic manifestations caused by miR-309 depletion. Thus, miR-309 plays a critical role in mosquito reproduction by targeting SIX4 in the ovary and serves as a regulatory switch permitting a stage-specific degradation of the ovarian SIX4 mRNA. In turn, this microRNA (miRNA)-targeted degradation is required for appropriate initiation of a blood feeding-triggered phase of ovarian development, highlighting involvement of this miRNA in mosquito reproduction.

scholarly journals On the use of inhibitors of 4-hydroxyphenylpyruvate dioxygenase as a vector-selective insecticide in the control of mosquitoes

2019 ◽  
Author(s):  
Marlon A. V. Ramirez ◽  
Marcos Sterkel ◽  
Ademir de Jesus Martins ◽  
José Bento Pereira Lima ◽  
Pedro L. Oliveira
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Aedes Aegypti ◽  
Blood Meal ◽  
Mosquito Control ◽  
Blood Feeding ◽  
Degradation Pathway ◽  
Cross Resistance ◽  
Single Meal ◽  
Neurotoxic Insecticides

AbstractBlood-sucking insects incorporate many times their body weight of blood in a single meal. As proteins are the major component of vertebrate blood, its digestion in the gut of hematophagous insects generates extremely high concentrations of free amino acids. Previous reports showed that the tyrosine degradation pathway plays an essential role in adapting these animals to blood feeding. Inhibiting 4-hydroxyphenylpyruvate dioxygenase (HPPD), the rate-limiting step of tyrosine degradation, results in the death of insects after a blood meal. Therefore, it was suggested that compounds that block the catabolism of tyrosine could act selectively on blood-feeding insects. Here we have evaluated the toxicity against mosquitoes of three HPPD inhibitors currently used as herbicides and in human health. Among the compounds tested, nitisinone (NTBC) proved to be more potent than mesotrione (MES) and isoxaflutole (IFT) in Aedes aegypti. NTBC was lethal to Ae. aegypti in artificial feeding assays (LD50: 4.36 µM), as well as in topical application (LD50: 0.0033 nmol/mosquito). NTBC was also lethal to Ae. aegypti populations that were resistant to neurotoxic insecticides, and it was lethal to other mosquito species (Anopheles and Culex). Therefore, HPPD inhibitors, particularly NTBC, represent promising new drugs for mosquito control. Since they only affect blood-feeding organisms, they would represent a safer and more environmentally friendly alternative to conventional neurotoxic insecticides.Author SummaryThe control of mosquitoes has been pursued in the last decades by the use of neurotoxic insecticides to prevent the spreading of dengue, zika and malaria, among other diseases. However, the selection and propagation of different mechanisms of resistance hinder the success of these compounds. New methodologies are needed for their control. Hematophagous arthropods, including mosquitoes, ingest quantities of blood that represent many times their body weight in a single meal, releasing huge amounts of amino acids during digestion. Recent studies showed that inhibition of the tyrosine catabolism pathway could be a new selective target for vector control. Thus we tested three different inhibitors of the second enzyme in the tyrosine degradation pathway as tools for mosquito control. Results showed that Nitisinone (NTBC), an inhibitor used in medicine, was the most potent of them. NTBC was lethal to Aedes aegypti when it was administered together with the blood meal and when it was topically applied. It also caused the death of Anopheles aquasalis and Culex quinquefasciatus mosquitoes, as well as field-collected Aedes populations resistant to neurotoxic insecticides, indicating that there is no cross-resistance. We discuss the possible use of NTBC as a new insecticide.

scholarly journals Hormone-dependent activation and repression of microRNAs by the ecdysone receptor in the dengue vector mosquito Aedes aegypti

2021 ◽  
Vol 118 (26) ◽  
pp. e2102417118
Author(s):  
Ya-Zhou He ◽  
Emre Aksoy ◽  
Yike Ding ◽  
Alexander S. Raikhel
Keyword(s):  
Aedes Aegypti ◽  
Mirna Expression ◽  
Blood Meal ◽  
Fat Body ◽  
Blood Feeding ◽  
Small Rna Sequencing ◽  
Sequencing Analysis ◽  
Ecdysone Receptor ◽  
Egg Development ◽  
Semialdehyde Dehydrogenase

Female mosquitoes transmit numerous devastating human diseases because they require vertebrate blood meal for egg development. MicroRNAs (miRNAs) play critical roles across multiple reproductive processes in female Aedes aegypti mosquitoes. However, how miRNAs are controlled to coordinate their activity with the demands of mosquito reproduction remains largely unknown. We report that the ecdysone receptor (EcR)–mediated 20-hydroxyecdysone (20E) signaling regulates miRNA expression in female mosquitoes. EcR RNA-interference silencing linked to small RNA-sequencing analysis reveals that EcR not only activates but also represses miRNA expression in the female mosquito fat body, a functional analog of the vertebrate liver. EcR directly represses the expression of clustered miR-275 and miR-305 before blood feeding when the 20E titer is low, whereas it activates their expression in response to the increased 20E titer after a blood meal. Furthermore, we find that SMRTER, an insect analog of the vertebrate nuclear receptor corepressors SMRT and N-CoR, interacts with EcR in a 20E-sensitive manner and is required for EcR-mediated repression of miRNA expression in Ae. aegypti mosquitoes. In addition, we demonstrate that miR-275 and miR-305 directly target glutamate semialdehyde dehydrogenase and AAEL009899, respectively, to facilitate egg development. This study reveals a mechanism for how miRNAs are controlled by the 20E signaling pathway to coordinate their activity with the demands of mosquito reproduction.

scholarly journals Mating and blood-feeding induce transcriptome changes in the spermathecae of the yellow fever mosquito Aedes aegypti

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Carolina Camargo ◽  
Yasir H. Ahmed-Braimah ◽  
I. Alexandra Amaro ◽  
Laura C. Harrington ◽  
Mariana F. Wolfner ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Blood Meal ◽  
Transcriptional Response ◽  
Blood Feeding ◽  
Sperm Storage ◽  
Biological Processes ◽  
Gene Products ◽  
Heme Peroxidase ◽  
Males And Females

Abstract Aedes aegypti mosquitoes are the primary vectors of numerous viruses that impact human health. As manipulation of reproduction has been proposed to suppress mosquito populations, elucidation of biological processes that enable males and females to successfully reproduce is necessary. One essential process is female sperm storage in specialized structures called spermathecae. Aedes aegypti females typically mate once, requiring them to maintain sperm viably to fertilize eggs they lay over their lifetime. Spermathecal gene products are required for Drosophila sperm storage and sperm viability, and a spermathecal-derived heme peroxidase is required for long-term Anopheles gambiae fertility. Products of the Ae. aegypti spermathecae, and their response to mating, are largely unknown. Further, although female blood-feeding is essential for anautogenous mosquito reproduction, the transcriptional response to blood-ingestion remains undefined in any reproductive tissue. We conducted an RNAseq analysis of spermathecae from unfed virgins, mated only, and mated and blood-fed females at 6, 24, and 72 h post-mating and identified significant differentially expressed genes in each group at each timepoint. A blood-meal following mating induced a greater transcriptional response in the spermathecae than mating alone. This study provides the first view of elicited mRNA changes in the spermathecae by a blood-meal in mated females.

scholarly journals Novel small molecule agonists of an Aedes aegypti neuropeptide Y receptor block mosquito biting behavior

2018 ◽  
Author(s):  
Laura B. Duvall ◽  
Lavoisier Ramos-Espiritu ◽  
Kyrollos E. Barsoum ◽  
J. Fraser Glickman ◽  
Leslie B. Vosshall
Keyword(s):  
Aedes Aegypti ◽  
Neuropeptide Y ◽  
Small Molecule ◽  
Blood Meal ◽  
Disease Transmission ◽  
Blood Feeding ◽  
Behavioral Suppression ◽  
Host Seeking ◽  
Novel Approach ◽  
Seeking Behavior

AbstractFemale Aedes aegypti mosquitoes bite humans to obtain a blood-meal to develop their eggs. Remarkably, strong attraction to humans is suppressed for several days after the blood-meal by an unknown mechanism. We investigated a role for neuropeptide Y (NPY)-related signaling in this long-term behavioral suppression, and discovered that drugs targeting human NPY receptors modulate mosquito host-seeking behavior. In a screen of all 49 predicted Ae. aegypti peptide receptors, we identified NPY-like receptor 7 (NPYLR7) as the sole target of these human drugs. To obtain small molecule agonists selective for NPYLR7, we carried out a high-throughput cell-based assay of 265,211 compounds, and isolated 6 highly selective NPYLR7 agonists that inhibit mosquito attraction to humans. NPYLR7 CRISPR-Cas9 null mutants are defective in behavioral suppression, and resistant to these drugs. Finally, we show that these drugs are capable of inhibiting biting and blood-feeding on a live host, suggesting a novel approach to control infectious disease transmission by controlling mosquito behavior.

Pre-mating Blood Feeding by Anopheles pharoensis (Diptera: Culicidae) and Its Effects on Mating, Longevity and Egg Production

1990 ◽  
Vol 25 (1) ◽  
pp. 57-63
Author(s):  
Adel S. El-Akad ◽  
J. G. Humphreys
Keyword(s):  
Blood Meal ◽  
Egg Production ◽  
Ovarian Development ◽  
Reproductive Potential ◽  
Blood Feeding ◽  
Field Observations ◽  
Laboratory Studies ◽  
The Third ◽  
Anopheles Pharoensis ◽  
Blood Meals

Field observations and laboratory studies were conducted to determine the effects of a pre-mating blood meal on mating, ovarian development and oviposition in Anopheles pharoensis (Theobald). Approximately 24% of the females blood feed before mating; however, swollen abdomens of blood-fed females interfere with the mating process. In females which mated prior to first blood meal, first oviposition occurred at 6.6 days and required only a single blood meal. A second blood meal takes them to the second oviposition in an additional 2.5 days; the third oviposition required 1.4 blood meals and occurred 3 days after the second oviposition. Blood-fed unmated females reach first oviposition at 13.4 days and require an average of 4 blood meals prior to the first oviposition. At this age, the female is chronologically old and even if mating now occurs, egg production is greatly reduced and continues to decrease through subsequent ovipositions until death. The taking of a blood meal prior to mating greatly decreases the reproductive potential of this species.

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