ABSTRACT
The midgut of anopheline mosquito is the entry of Plasmodium, the causative agent of malaria.When the mosquito feeds on parasite infected host, Plasmodium parasites reach the midgut and must confront digestive enzymes, the innate immune response and go across the peritrophic matrix (PM), a thick extracellular sheath secreted by the mosquito midgut epithelial cells. Then, to continue its development, the parasite must reach the salivary glands to achieve transmission to a vertebrate host. We report here the morphological and biochemical descriptions of the midgut changes after a blood meal in Anopheles albimanus. Before blood feeding, midgut epithelial cells contained numerous electrondense vesicles distributed in the central to apical side. These vesicles were secreted to the luminal side of the midgut after a blood meal. At early times after blood ingest, the PM is formed near microvilli as a granulous amorphous material and after it consolidates forming a highly organized fibrillar structure, constituted by layers of electrondense and electronlucent regions. Proteomic comparative analysis of sugar and blood fed midguts showed several molecules that modify their abundance after blood intake; these include innate immunity, cytoskeletal, stress response, signaling, and digestive, detoxifying and metabolism enzymes. Biological significance In the midgut of mosquitoes during bloodfeeding, many simultaneous processes occur, including digestion, innate immune activities, cytoskeleton modifications, construction of a peritrophic matrix and hormone production, between others. Mechanical forces are very intense during bloodfeeding and epithelial and muscular cells must resist the stress, modifying the actin cytoskeleton and coordinating intracellular responses by signaling. Microorganisms present in midgut contents reproduce and interact with epithelial cells triggering innate immune response. When infectious agents are present in the blood meal they must traverse the peritrophic matrix, an envelope formed from secretion products of epithelial cells, and evade the immune system in order to reach the epithelium and continue their journey towards salivary glands, in preparation for the transmission to the new hosts. During all these processes, proteins of mosquitoes are modified in order to deal with mechanical and biological challenges, and the aim of this work is to study these changes.
Subject(s)
Anopheles/metabolism , Digestive System/metabolism , Proteome , Animals , Anopheles/parasitology , Cytoskeleton/metabolism , Electrophoresis, Gel, Two-Dimensional , Epithelial Cells/parasitology , Female , Host-Parasite Interactions , Humans , Immunity, Innate , Insect Vectors/metabolism , Insect Vectors/parasitology , Mice , Mice, Inbred BALB C , Oxidative Stress , Plasmodium/metabolism , Proteomics , Serpins/chemistry , Signal Transduction , Spectrometry, Mass, Electrospray Ionization , Tandem Mass Spectrometry , Time FactorsABSTRACT
Salivary glands of female mosquitoes produce proteins, not completely described yet, that participate in carbohydrate and blood feeding. Here, we report an acidic glycoprotein of 35 kDa (GP35 ANOAL) secreted in the saliva of the malaria vector mosquito Anopheles albimanus. GP35 ANOAL is produced exclusively in the distal lateral lobes of adult female salivary glands, it has a pI of 4.45 and is negatively stained by regular silver stain. An 888 bp cDNA clone encoding a predicted product of 240 amino acids has a signal peptide, potential post-translational modification sites, and a disintegrin signature RGD. The GP35 ANOAL sequence depicts high similarities with the 30 kDa saliva allergen of Aedes aegypti, 30 kDa allergen-like hypothetical proteins, and GE-rich proteins present in several Anopheles species, as well as in Ae. albopictus and Culex pipiens quinquefasciatus. The function of this protein family is still unknown.
Subject(s)
Anopheles/metabolism , Glycoproteins/metabolism , Insect Proteins/metabolism , Amino Acid Sequence , Animals , Anopheles/genetics , Anopheles/growth & development , Base Sequence , Female , Glycoproteins/genetics , Insect Proteins/genetics , Molecular Sequence Data , RNA, Messenger/metabolism , Salivary Glands/metabolismABSTRACT
Proteins and proteases present in midgut tissues of sugar-fed Anopheles albimanus (Wiedemann) males and females were studied by 2-dimensional electrophoresis and zymograms using gelatin and hemoglobin as substrates. Protein patterns differed between sexes. Some proteins were similar in both sexes, but differed in intensity. Sex specific proteins and midgut proteases also were detected. These findings indicate the possibility of sex dependent regulation of midgut proteins and protease production.
