In adult dipteran insects (flies), the crop is a diverticulum of the esophagus that serves as a food storage organ. The crop pumps stored contents into the alimentary canal for digestion and absorption. The pumping is mediated by peristaltic contractions of the crop musculature. In adult female mosquitoes, the crop (ventral diverticulum) selectively stores sugar solutions (e.g., nectar); proteinaceous blood meals by-pass the crop and are transferred directly to the midgut for digestion. The mechanisms that regulate crop contractions have never been investigated in mosquitoes. Here we provide the first physiological characterization of the contractile properties of the mosquito crop and explore the mechanisms that regulate crop contractions. Using an in vitro bioassay we found that the isolated crop spontaneously contracts in Ringer solution for at least 1 hour and its contractions are dependent on extracellular Ca2+. Adding serotonin (5- hydroxytryptamine, 5-HT) or a membrane-permeable analog of cyclic adenosine monophosphate (cAMP) to the extracellular bath increased the frequency of crop contractions. On the other hand, adding benzethonium chloride (BzCl; a chemical that mimics the effects of myosuppressins), H-89 or Rp-cAMPS (inhibitors of protein kinase A, PKA), or carbenoxolone (an inhibitor of gap junctions) reduced the frequency of the unstimulated, spontaneous and/or 5-HT-stimulated crop contractions. Adding aedeskinin III did not detectably alter crop contraction rates. In addition to pharmacological evidence of gap junctions, we demonstrated that the crop expressed several mRNAs encoding gap junctional proteins (i.e. innexins). Furthermore, we localized immunoreactivity for innexin 2 and innexin 3 to muscle and epithelial cells of the crop, respectively. Our results 1) suggest that 5-HT and myosupressins oppositely regulate contractile activity of the mosquito crop, and 2) provide the first evidence for putative roles of cAMP, PKA, and gap junctions in modulating contractile activity of the dipteran crop.

No abstract

Cinnamodial (CDIAL) is a drimane sesquiterpene dialdehyde found in the bark of Malagasy medicinal plants (Cinnamosma species; family Canellaceae). We previously demonstrated that CDIAL was insecticidal, antifeedant, and repellent against Aedes aegypti mosquitoes. The goal of the present study was to generate insights into the insecticidal mode of action for CDIAL, which is presently unknown. We evaluated the effects of CDIAL in vitro on the contractility of the ventral diverticulum (crop) in adult female Ae. aegypti. The crop is a food storage organ surrounded by visceral muscle that spontaneously contracts in vitro. We found that CDIAL completely inhibited spontaneous contractions of the crop as well as those stimulated by the agonist 5-hydroxytryptamine. Several derivatives of CDIAL with known insecticidal activity also inhibited crop contractions. Morphometric analyses of crops suggested that CDIAL induced a tetanic paralysis that was dependent on extracellular Ca 2+ and inhibited by Gd 3+ , a non-specific blocker of plasma membrane Ca 2+ channels. Screening of numerous pharmacological agents revealed that a Ca 2+ ionophore (A23187) was the only compound other than CDIAL to completely inhibit crop contractions via a tetanic paralysis. Taken together, our results suggest that CDIAL inhibits crop contractility by elevating intracellular Ca 2+ through the activation of plasma membrane Ca 2+ channels thereby leading to a tetanic paralysis, which may explain the insecticidal effects of CDIAL against mosquitoes. Our pharmacological screening efforts also revealed the presence of two regulatory pathways in mosquito crop contractility not previously described: an inhibitory glutamatergic pathway and a stimulatory octopaminergic pathway. The latter was also completely inhibited by CDIAL.

Primary membranous nephropathy remains one of the most frequent causes of nephrotic syndrome in adults. It is an autoimmune disorder in which auto-antibodies target antigens at the podocytes cell membrane–basement membrane interface. Our understanding of membranous nephropathy has expanded dramatically as of late. After the initial discovery of the phospholipase A2 receptor auto-antibody in 2009, eight more antigens have been discovered. These discoveries have led to refinement in our understanding of the pathogenesis, diagnosis, and natural history of primary membranous nephropathy. Now, many experts advocate for redefining primary membranous nephropathy based on antigen, potentially shedding the primary and secondary nomenclature. Recently, therapies for primary membranous have also expanded. Immunosuppressive therapies like cyclophosphamide and rituximab, which primarily target B-cells, remain the cornerstone of therapy. However, there is still significant room for improvement, as many as 30-40% do not respond to this therapy according to recent trials. Additionally, drugs targeting complement, and other novel therapies are also under investigation. In this review we will discuss the available therapies for primary membranous nephropathy in light of recent clinic trials like GEMRITUX, MENTOR, RI-CYCLO, and STARMEN, as well as management strategies. While the last 10 years have seen a boom in our mechanistic understanding of this ever-diversifying disease, we are likely to see a similar boom in the therapeutic options in the years to come.

Mosquito‐borne diseases such as malaria, dengue fever, and Zika, are a constantly evolving problem with newly emerging and reemerging pathogens threatening the health of millions of individuals worldwide. Prevention of these diseases relies on the effective control of mosquito populations with insecticides. Our group is developing new insecticides derived from natural products of the Madagascan medicinal plant Cinnamosma fragrans by understanding the interactions of these compounds with mosquitoes on a molecular and physiological level and how they exert their toxic effects. The goal of this study is to determine the effects of natural drimane sesquiterpene compounds isolated from the medicinal plant C. fragrans on the visceral muscle contractions of the ventral diverticulum (crop) in adult female yellow fever mosquitoes (Aedes aegypti), an important vector of Zika virus. Using an established bioassay, we evaluated the acute effects of several drimane sesquiterpenes on contraction rates of isolated crops in Ringer solution. Our results demonstrate that at least two insecticidal drimane sesquiterpenes significantly inhibit the spontaneous and serotonin‐stimulated contractions of the crop. The potency of their inhibition correlates with their potency as insecticides, suggesting that visceral muscle inhibition may be responsible for the toxic effects of the compounds on mosquitoes. Moreover, parallel experiments in the crop with a calcium ionophore (A23187) duplicate the effects of the natural compounds, suggesting that they may elicit muscle inhibition by modulating calcium permeability of the crop muscle cells. Future research will investigate the presence and roles of calcium channels within the crop, attempting to better understand their interaction with C. fragrans natural compounds.Support or Funding InformationSupported by NIH grant R21AI129951.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.