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ABSTRACT: BACKGROUND: Although inducible defences have been studied extensively, only little is known about how the presence of parasites might interfere with these anti-predator adaptations. Both parasites and predators are important factors shaping community structure and species composition of ecosystems. Here, we simultaneously exposed Daphnia magna to predator cues (released by the tadpole shrimp, Triops, or by a fish) and spores of the yeast parasite Metschnikowia sp. to determine how life history and morphological inducible defences against these two contrasting types of predators are affected by infection. RESULTS: The parasite suppressed some Triops-induced defences: Daphnia lost the ability to produce a greater number of larger offspring, a life-history adaptation to Triops predation. In contrast, the parasite did not suppress inducible defences against fish: induction (resulting in smaller body length of the mothers as well as of their offspring) and infection acted additively on the measured traits. Thus, fish-induced defences may be less costly than inducible defences against small invertebrate predators like Triops; the latter defences could no longer be expressed when the host had already invested in fighting off the parasite. CONCLUSIONS: In summary, our study suggests that as specific inducible defences differ in their costs, some might be suppressed if a target prey is additionally infected. Therefore, adding parasite pressure to predator-prey systems can help to elucidate the costs of inducible defences. 相似文献
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Saúl Zamora-Méndez Arlett Robles-Romo Erica Marin-Peralta Olivia Arjona Juan P. Apún-Molina Ana I. Beltrán-Lugo 《Journal Of Aquatic Food Product Technology》2017,26(9):1093-1106
Ante-mortem stress is recognized as one of the factors that could reduce shelf life in fish, although this topic has been scarcely addressed in crustaceans, particularly in cultivated penaeid shrimp where common harvest practices involves stressful conditions such as chasing, emersion, and confinement. This study analyzes indices of freshness in shrimp in response to such practices before storage in ice for six days. During ice storage, several indicators follow the typical postmortem pattern, although most of them (hypoxanthine, change in pH, and color) did not reach critical levels at day 6. Adenosine-5’-triphosphate (ATP) and degradation products (adenosine monophosphate, AMP, and inosine monophosphate, IMP), as well as several indicators of freshness (pH, expressible water, hardness, color, and the overall fatty acid composition) were not significantly affected by harvest. Other variables such as lower springiness, higher hypoxanthine, lipid hydroperoxides, and 20:4n-6/20:5n-3 ratio were observed in shrimp subjected to common harvest practices. However, under the current conditions of harvesting, these effects were marginal and probably do not substantially affect meat quality for human consumption, but care should be taken at higher environmental temperatures (e.g. harvest in summer) and for a duration of ice-storage over 6 days. 相似文献
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Glass transitions have been reported for purified humic acids only. In this study, a glass transition was detected in a sample of a sandy forest soil by Differential Scanning Calorimetry (DSC). The glass transition temperature was 79°C for air‐dried samples and 77°C for pre‐moistened samples. In addition to the glass transition, an exothermic process around 30°C was detected in pre‐moistened samples. This could be due to water loss of soil organic matter. However, the nature of this process is not yet understood. This study showed that the macromolecular behaviour of SOM, as indicated by DSC, reacts to the moisture state of soil organic matter. 相似文献
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Haifaa A. Mahjoub William T. Robbins Olivia Galeuzzi Kylee F. Graham Megan E.B. Jones Melanie A. Buote Spencer J. Greenwood Gary A. Conboy 《The Canadian veterinary journal. La revue veterinaire canadienne》2022,63(6):637
Objective To identify first-stage nematode larvae (L1) recovered from a red fox scat sample and adult female worms recovered from 2 red fox lungs at necropsy, using published molecular methods to confirm a morphological diagnosis of Angiostrongylus vasorum (French heartworm).Animal Red fox (Vulpes vulpes).Procedure Nematode larvae recovered from a Baermann examination survey of wild canid scats (n = 101) conducted from January 2017 to August 2020, were identified by size and morphology and subjected to PCR and DNA sequencing of the small subunit (SSU) rRNA gene, the large subunit (LSU) rRNA gene, or the second internal transcribed spacer (ITS2). In addition, these techniques were applied to adult female worms recovered from the heart/lungs of 2 red foxes (obtained from PEI trappers and stored frozen at −20°C since December of 2018 and 2020).Results Size and morphology of L1 recovered by Baermann examination from a wild canid scat sample (presumed to be red fox) collected near Montague, PEI and adult female worms recovered at necropsy from 2 red fox carcasses were identified as A. vasorum. Molecular analysis confirmed the larvae and adult worms were A. vasorum.Conclusion These findings indicated that A. vasorum has become endemic in the red fox population on PEI.Clinical relevance Angiostrongylus vasorum infection is potentially fatal in dogs. Veterinarians and regional diagnostic laboratories in the Maritime provinces should consider the possibility of A. vasorum infection in dogs with clinical signs of cardiopulmonary and/or central nervous system disease or bleeding disorders. 相似文献
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Vendrell D Balcázar JL de Blas I Ruiz-Zarzuela I Gironés O Luis Múzquiz J 《Comparative immunology, microbiology and infectious diseases》2008,31(4):337-345
We analysed the effect of probiotic supplementation on the control of lactococcosis in rainbow trout. Probiotic strains Leuconostoc mesenteroides CLFP 196 and Lactobacillus plantarum CLFP 238 were administered orally to fish for 30 days at 10(7) CFU g(-1) feed. Thirty days after the start of the probiotic feeding, fish were challenged with Lactococcus garvieae. Probiotic supplementation reduced fish mortality significantly, from 78% in the control group to 46-54% in the probiotic groups. 相似文献
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Vidya Sunil Andrew W. Harris Bob Sine Anne Marie Holt A. Lynn Noseworthy Doug Sider Frances B Jamieson Shelley White Cassandra Johnston Olivia Spohn 《Zoonoses and public health》2019,66(1):164-168
In July 2015, a cluster of five suspect cases of clinically diagnosed Mycobacterium marinum (M. marinum) skin infections were reported to the Haliburton, Kawartha, Pine Ridge District Health Unit (HKPRDHU), Ontario, Canada, with two additional cases subsequently identified through case finding. All seven cases presented with cutaneous lesions located on the finger, hand and/or elbow regions typical of M. marinum infection. Specimens were collected by skin biopsy for two of the seven cases; both cases tested positive for M. marinum by molecular detection (hsp65 gene amplification and sequencing), and one was confirmed positive for M. marinum by culture. All seven cases reported handling raw shrimp from an aquaculture facility in the Health Unit's jurisdiction. M. marinum is not a reportable disease in Ontario, and there are no known previous reports of a cluster of M. marinum reported in Ontario, Canada. A cluster investigation working group was struck that included representation from various agencies including Public Health Ontario (PHO), Public Health Ontario Laboratories (PHOL), Ontario Ministry of Agriculture and Rural Affairs (OMAFRA) and the two health units involved in case investigations. Several public health and aquaculture farming recommendations were made to mitigate further risks associated with handling of raw shrimp from the facility. Several challenges were faced during the investigation process. The paper discusses these challenges and public health recommendations made in order to mitigate occupational and public health risks related to the hazard identified. 相似文献
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Olivia Dondina Santiago Saura Luciano Bani María C. Mateo-Sánchez 《Landscape Ecology》2018,33(10):1741-1756