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Metorchis
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Mariya Y. Pakharukova, Viatcheslav A. Mordvinov
There are rediae of different ages in the hemocoel of mollusks. Fedorov demonstrated that the formation of cercariae does not occur until autumn.22 Development is hampered by the diapause of the host during the winter period (freezing of rivers) in Western Siberia. The first cercariae appear in May of the following year. Mature cercariae are motile and begin to emerge from mollusks in bright sunny weather up to several hundred per a day. The average size of mature cercariae is 0.22 × 0.07 mm. The body has spines and sensory hairs. The ventral sucker is hardly noticeable. The length of the tail is 0.3 mm. The cercariae, as described by Fedorov,22 are not different from the previously described cercariae of M. bilis.11
Campylobacter
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Martin Stahl, Bruce A. Vallance
These insects have long been employed for the study of a wide variety of bacterial infections. The bacterial pathogen of choice is injected into the foreleg, where it can infect the insect hemocoel. The relative pathogenicity of the inoculated bacteria is then measured by counting the numbers of resulting dead Galleria, accompanied by the development of a distinctive black melanization of the dead and dying larvae.80,81 In this scenario, the pathogenicity of the bacteria is assessed based on their ability to proliferate and infect the insect’s hemocytes, which function in a similar fashion to mammalian neutrophils by phagocytosing and killing engulfed bacteria through a superoxide burst. This makes the Galleria insect model a useful means to test a bacterium’s ability to defend against a host inflammatory response comprised of neutrophils and/or superoxide production. However, given the fundamental differences between most other aspects of insect biology and a mammalian host, other insights into pathogenesis will likely be limited.
Host Defense and Parasite Evasion
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
Another example of a collaborative, mutualistic arrangement to achieve infection of an invertebrate host is provided by entomopathogenic nema-todes such as Steinernema and Heterorhabditis (see also Box 7.2). Infective Steinernema larvae actively search for, find, and infect insect hosts. Once in the insect, they release from special areas of their intestine mutualistic bacteria (Xenorhabdus) that then proliferate rapidly in the host insect’s hemocoel, producing a number of factors that damage the host’s hemocytes. The bacteria also inhibit expression of host-produced antimicrobial peptides, such as cecropin, and inhibit prophenoloxidase and thus melanization. Furthermore, the bacteria produce antimicrobial factors that prevent the growth of opportunistic bacteria and release enzymes that degrade molecules produced by the host insect, providing a nutrient soup that favors growth of their associated nematodes. Consequently, both Xenorhabdus and Steinernema proliferate in the host, which is soon killed. Eventually thousands of larval nematodes leave the host insect, each carrying an inoculum of these specialized bacteria to facilitate infection of a hapless new host. Because of their efficiency in killing insects, entomopathogenic nematodes have been used widely as biological control agents.
Assessment of combining biosynthesized silver nanoparticles using Bacillus thuringiensis and gamma irradiation for controlling Pectinophora gossypiella (saunders) (lepidoptera: Gelechiidae)
Published in International Journal of Radiation Biology, 2021
Ahlam Gabarty, Afaf Abas, Hedaya M. Salem, Sawsan M. El-Sonbaty, Doaa S. Farghaly, Heba A. Awad
TEM micrograph showed that the midgut epithelium of the normal 4th instar larvae consists of basal lamina (Bl), regenerative cell (Rc), mature cells (Mc) and borders facing the lumen that contain abundant microvilli (Mv) and numerous folds, which increase the surface area for absorption and secretion (Figure 7(A)). The midgut epithelium of the normal larvae consists of a single layer of cells. Its boundary toward the hemocoel makes up the basal lamina which in turn is surrounded by muscles and tracheal cells. The epithelial cells are dissimilar in appearance and contain the stem cells (Sc) (Figure 7(B)). The nucleus is centered in the cell, the nuclei assume a somewhat more basal location and are slightly ovoid and the endoplasmic reticulum is more obvious, especially in the vicinity of the nucleus. Also, there is a large number of golgi apparatus and numerous mitochondria are observed in the cells’ cytoplasm. An obvious junction between the cells, known as macula adherence is observed. Moreover, symbiotic bacteria in the cytoplasm were distinguished in the electron micrograph. These bacteria are grouped and localized in the lateral side of the cells (Figure 7(B,C)). The mature cell consists of two main types present in the midgut of all insects, i.e., columnar and endocrine cells (Figure 7(D)).
Mechanisms of nanotoxicity – biomolecule coronas protect pathological fungi against nanoparticle-based eradication
Published in Nanotoxicology, 2020
Roland H. Stauber, Dana Westmeier, Madita Wandrey, Sven Becker, Dominic Docter, Guo-Bin Ding, Eckhard Thines, Shirley K. Knauer, Svenja Siemer
Instar larvae of the greater wax-moth G. mellonella (MSC UG), were stored in the dark at 15°C to prevent pupation. Larvae weighing 250–300mg were randomly selected and experiments were performed independently. Galleria mellonella larvae were scratched and injected into the hemocoel at the last left proleg with 10μL A. fumigatus spores or spore-Ag NP complexes (8×107 conidia/mL), prepared in the presence or absence of human plasma. As controls, uninfected larvae were injected with Ag NPs (5μL, 0.1mg/mL) to exclude Ag NP-mediated toxicity. Infected and control larvae were housed under air-conditioned S1-safety requirements at 20 °C/55% humidity for 96h in the dark. Survival was recorded every 24h by visual inspection (high level of skin melanization and hardening) and testing signs of vitality by brief touching. Three independently conducted experiments were performed. Survival curves were statistically analyzed by Kaplan–Meier as described (Engels et al. 2008).
Cruciferous vegetables (Brassica oleracea) confer cytoprotective effects in Drosophila intestines
Published in Gut Microbes, 2021
James T. Lyles, Liping Luo, Ken Liu, Dean P. Jones, Rheinallt M. Jones, Cassandra L. Quave
Since indole-fed Drosophila have established Nrf2 signaling, the gut permeability in adult Drosophila was undertaken based on assays described in Darby et al.5 Briefly, male w1118 flies were aged to 5-days old. The fly food was supplemented with Brassica extracts for 3 days. Then, flies were subjected to 17.5 mM paraquat solution spiked with blue dye which induces a leaky gut phenotype. Flies that have a leaky gut are identified by a visible blue color within their hemocoel. Flies were anesthetized daily with CO2 and visually scored for blue dye infiltration and the ‘Smurf’-like phenotype.