A new Myxobolus (Cnidaria: Myxosporea) infecting the ornamental catfish Corydoras schwartzi from the Purus River in Brazil

A new microscopic cnidarian is described, infecting five of thirty (16.6%) specimens of Corydoras schwartzi caught in the Purus River, State of Amazonas, Brazil. Histological analysis showed that cyst development occurred in the serosa layer of the intestine. Mature myxospores are ovoid in body shape in frontal view, 22.4 ± 0.3 μm in total length and 16.3 ± 0.1 μm in width. Internally, two aubergine-shaped, elongate symmetrical polar capsules occupy more than half the length of the spore, 14.3 ± 0.2 μm in length and 6.5 ± 0.1 μm in width. Ultrastructural analysis provided evidence of five polar filament coils inside the polar capsule and binucleated sporoplasm containing a moderate number of sporoplasmosomes. The valvogenic cells abutting each other form a sutural ridge and frequently a thin layer of homogeneous material separates the cells. The outer surface of the myxospore valves is smooth, with no evidence of formation of ridges in the valves. Immature myxospores in various stages of development were observed. This study is the first report of a myxosporean parasitizing C. schwartzi and the first report of a myxosporean infection in the intestine of an ornamental fish from South America

Fig. 4 in A new Myxobolus (Cnidaria: Myxosporea) infecting the ornamental catfish Corydoras schwartzi from the Purus River in Brazil

Fig. 4 (next page). Electron micrographs of myxospores of Myxobolus adrianoi sp. nov., parasite of the intestine of Corydoras schwartzi Rössel, 1963. A. Young sporoblast showing polar filament still out of the polar capsules, abundant valve-forming material, conspicuous sutural line (large white arrow), some sporoplasmosomes (small white arrows), mitochondria and presence of pinocytic channels (white arrowheads) in the ectoplasm. B–C. Sporoblast in advanced developmental stage with polar filament (white arrows) inside the polar capsule. In B note several sporoplasmosomes (white arrows) and two nuclei at sporoplasms. In C observe presence of valve-forming material (short white arrows), capsulogenic cell, nuclei at sporoplasm and nucleus of capsulogenic cell. D. Immature myxospore showing valvogenic cells abutting each other to form a sutural ridge and showing the two cells are separated by a thin layer of homogenous material (white arrow). E–F. Almost mature myxospores showing sutural lines (black arrows), valve-forming material (*), valves, two nuclei and sporoplasmosomes (white arrows) at sporoplasms. Abbreviations: cp = capsulogenic cell; ec = ectoplasm; mt = mitochondrion; nc = nucleus of capsulogenic cell; Nu = nucleus; pc = polar capsule; PF = polar filament; sp = sporoplasm; v = valvogenic cell/valve; vm = valve-forming material. Scale bars: 2 μm.Published as part of Mathews, Patrick D., Madrid, Rafael R.M., Mertins, Omar, Rigoni, Vera L.S. & Morandini, André C., 2020, A new Myxobolus (Cnidaria: Myxosporea) infecting the ornamental catfish Corydoras schwartzi from the Purus River in Brazil, pp. 1-14 in European Journal of Taxonomy 620 on page 8, DOI: 10.5852/ejt.2020.620, http://zenodo.org/record/375023

A new Myxobolus (Cnidaria: Myxosporea) infecting the ornamental catfish Corydoras schwartzi from the Purus River in Brazil

A new microscopic cnidarian is described, infecting five of thirty (16.6%) specimens of Corydoras schwartzi caught in the Purus River, State of Amazonas, Brazil. Histological analysis showed that cyst development occurred in the serosa layer of the intestine. Mature myxospores are ovoid in body shape in frontal view, 22.4 ± 0.3 μm in total length and 16.3 ± 0.1 μm in width. Internally, two aubergine-shaped, elongate symmetrical polar capsules occupy more than half the length of the spore, 14.3 ± 0.2 μm in length and 6.5 ± 0.1 μm in width. Ultrastructural analysis provided evidence of five polar filament coils inside the polar capsule and binucleated sporoplasm containing a moderate number of sporoplasmosomes. The valvogenic cells abutting each other form a sutural ridge and frequently a thin layer of homogeneous material separates the cells. The outer surface of the myxospore valves is smooth, with no evidence of formation of ridges in the valves. Immature myxospores in various stages of development were observed. This study is the first report of a myxosporean parasitizing C. schwartzi and the first report of a myxosporean infection in the intestine of an ornamental fish from South America

Essential oil from the leaves of <i>Xylopia langsdorfiana</i> (Annonaceae) as a possible spasmolytic agent

<div><p><i>Xylopia langsdorfiana</i> A. St.-Hil. &Tul. (Annonaceae) is popularly known in the northeast of Brazil as ‘pimenteira da terra’, and an essential oil (XL-OE) was extracted from its leaves. Since <i>Xylopia</i> species are cited in folk medicine and diterpenes from <i>X. langsdorfiana</i> have spasmolytic activity, this study aimed to investigate a possible spasmolytic action of XL-OE on smooth muscle models. XL-OE (243 and 729 μg/mL) showed low pharmacologic efficacy on guinea pig trachea and rat aorta and uterus. However, in guinea pig ileum, XL-OE (27–729 μg/mL) inhibited carbachol or histamine-induced phasic contractions (1 μM) in a significant and concentration-dependent manner. In addition, XL-OE (81 μg/mL) reduced fluorescence intensity in ileal myocytes stimulated by histamine, indicating a decrease in cytosolic calcium concentration, which could explain the spasmolytic activity. Thus, XL-OE proved to be a promising natural product to be used in gastrointestinal diseases acting by modulating the cytosolic calcium concentration.</p></div