scholarly journals Effects of temperature on the oncospheres of the cestode Microsomacanthus hopkinsi and its implication for their over-winter survival

1992 ◽  
Vol 70 (5) ◽  
pp. 935-940 ◽  
Author(s):  
John Lee ◽  
Wilfred Pilgrim ◽  
J. D. McLaughlin ◽  
M. D. B. Burt
Keyword(s):  
Intermediate Host ◽  
Survival Time ◽  
Host Population ◽  
Potential Significance ◽  
Northern Limit ◽  
Natural Conditions ◽  
Short Term ◽  
Inactive Period ◽  
Effects Of Temperature ◽  
Time Of Feeding

In an attempt to determine whether hymenolepidid oncospheres may overwinter and contribute to the pool of cysticercoids in the intermediate host population the following spring, we studied the survival of the oncospheres of the cestode Microsomacanthus hopkinsi following storage at 7 and 20 °C, following short-term freezing under laboratory conditions, and after overwintering (October–May) under natural conditions at depths of 0.5, 1, and 1.5 m in a local lake. Viability was tested by feeding the oncospheres to laboratory-reared amphipods (Hyalella azteca). The percentage of surviving amphipods that became infected following exposure to oncospheres stored at 7 °C declined steadily from 96% following 4 weeks storage to 43% after 24 weeks. Only 3% (2 of 60) were infected following exposure to oncospheres stored for 28 weeks. Oncospheres held overwinter under natural conditions failed to produce infections. These were slightly older (29 weeks) than the oldest oncospheres maintained at 7 °C in the laboratory, at the time of feeding to the amphipods. It appears that 28 weeks approaches the maximum survival time for the oncospheres of this species. Oncospheres subjected to short-term freezing also failed to produce infections when fed to amphipods. Oncospheres survived in sufficient numbers for up to 24 weeks to be of potential significance in the formation of infective pools in amphipods in the spring. However, there is a northern limit beyond which the inactive period of the amphipod host is too long for the oncospheres to bridge. Under these circumstances, they are of no consequence in the formation of the infective pool. Only 5% (3 of 60) of the amphipods exposed to oncospheres stored at 20 °C for 4 weeks became infected. Foci established in warmer conditions, as expected, are infective for much shorter periods.

scholarly journals Pathogenicity of the hymenolepidid cestode Microsomacanthus hopkinsi in its intermediate host, Hyalella azteca: implications for transmission, host fitness, and host populations

2006 ◽  
Vol 84 (1) ◽  
pp. 32-41 ◽  
Author(s):  
T Kokkotis ◽  
J D McLaughlin
Keyword(s):  
Intermediate Host ◽  
Hyalella Azteca ◽  
Experimental Period ◽  
Host Population ◽  
Intermediate Hosts ◽  
Short Term ◽  
Host Fitness ◽  
Negative Effect ◽  
Larval Parasites

Infection by larval parasites can have severe consequences on intermediate hosts that affect transmission, fecundity and fitness of the host, and host population structure. This study examines the pathogenic effects of cysticercoid larvae of the hymenolepidid cestode Microsomacanthus hopkinsi (Schiller, 1951) on its amphipod intermediate host, Hyalella azteca Saussure, 1858. There was a significant, positive relationship between oncosphere consumption, cysticercoid burden, and age in short-term experiments in which groups of H. azteca were exposed individually to single egg packets of M. hopkinsi during instars 1, 2, 3, 4, 6, 8, and 9; however, there was no correlation between oncosphere consumption and the intensity of infection in the amphipod hosts within each instar. The mean number of moults over a 14 day experimental period was significantly less in infected amphipods than in their respective controls. In short-term experiments, the greatest mortality appeared to be limited to amphipods exposed during the earliest instars; little mortality was observed in amphipods exposed during instar 4 or later. Long-term experiments revealed a significant negative effect of infection on the overall life span of both male and female H. azteca exposed individually to a single egg packet during instar 4. Of 72 females infected during instar 4 and provided with mates during instar 6, only 1 and 4 produced broods in instars 8 and 9, respectively, compared with 58 and 57 of 72 control females. Broods produced by infected females were significantly smaller than those of control females. Infected individuals were less likely to mate successfully. The results are discussed in terms of their consequences for transmission, host fitness, and potential effects on host populations.

scholarly journals Achieving Efficient and Stable Deammonification at LowTemperatures—Experimental and Modeling Studies

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3961
Author(s):  
Hussein Al-Hazmi ◽  
Xi Lu ◽  
Dominika Grubba ◽  
Joanna Majtacz ◽  
Przemysław Kowal ◽  
...  
Keyword(s):  
Sequencing Batch Reactor ◽  
Energy Savings ◽  
Batch Reactor ◽  
Phase Changes ◽  
Intermittent Aeration ◽  
Short Term ◽  
Higher Temperature ◽  
Effects Of Temperature ◽  
The Mathematical Model ◽  
Positive Effect

The short-term effects of temperature on deammonification sludge were evaluated in a laboratory-scale sequencing batch reactor (SBR). Mathematical modeling was used for further evaluations of different intermittent aeration strategies for achieving high and stable deammonification performance at decreasing temperatures. As for the biomass cultivated at high temperatures (e.g., 30 °C), a higher temperature dependency (the adjusted Arrhenius coefficient θ for 11–17 °C = 1.71 vs. θ for 17–30 °C = 1.12) on the specific anammox growth rates was found at lower temperatures (11–17 °C) in comparison with higher temperatures (17–30 °C). Further evaluations of recovering the nitrogen removal efficiency at decreasing temperatures with the mathematical model by modifying the intermittent aeration strategies (aeration frequency (F) and the ratio (R) between non-aerated (non-aer) phase and aerated (aer) phase durations) indicated that intermittent aeration with a prolonged non-aerated phase (e.g., R ≥ 4 regardless of F value) would help to maintain high and stable deammonification performance (~80%) at decreasing temperatures (14–22 °C). Extending the non-aerated phases (increasing R) and reducing the frequency (F) of off/on phase changes have a positive effect on increasing energy savings, leading to increasing interest in this method.

scholarly journals Domestication of wild animals may provide a springboard for rapid variation of coronavirus

2021 ◽  
Vol 16 (1) ◽  
pp. 252-254
Author(s):  
Lei Gao
Keyword(s):  
Intermediate Host ◽  
Wild Animals ◽  
Intermediate Hosts ◽  
Natural Conditions ◽  
Rapid Variation ◽  
Cross Breeding ◽  
Important Direction ◽  
Animal Hosts

Abstract Coronaviruses have spread widely among humans and other animals, but not all coronaviruses carried by specific animals can directly infect other kinds of animals. Viruses from most animal hosts need an intermediate host before they can spread widely among humans. Under natural conditions, coronaviruses do not rapidly change from infecting wild animals as intermediate hosts and to spreading widely among humans. The intermediate host might be the animals captured or bred for the purpose of cross-breeding with domesticated species for improvement of the breed. These animals differ from wild animals at the environmental and genetic levels. It is an important direction to study the semi-wild animals domesticated by humans in search for intermediate hosts of viruses widely spread among humans.

Effects of short-term decomposition on isotope values of fish tissues under natural conditions

2021 ◽  
Author(s):  
Kathryn S. Peiman ◽  
Hsien-Yung Lin ◽  
Michael Power ◽  
Scott G. Hinch ◽  
David A. Patterson ◽  
...  
Keyword(s):  
Natural Conditions ◽  
Short Term ◽  
Fish Tissues

scholarly journals Effects of WMA Additive on the Rheological Properties of Asphalt Binder and High Temperature Performance Grade

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jiupeng Zhang ◽  
Guoqiang Liu ◽  
Li Xu ◽  
Jianzhong Pei
Keyword(s):  
Critical Temperature ◽  
Rheological Properties ◽  
Asphalt Binder ◽  
Aging Effect ◽  
Asphalt Binders ◽  
Short Term ◽  
Performance Grade ◽  
Temperature Performance ◽  
Effects Of Temperature ◽  
Increasing Temperature

Sasobit additives with different dosages were added into 70# and 90# virgin asphalt binders to prepare WMA binders. The rheological properties, includingG∗andδ, were measured by using DSR at the temperature ranging from 46°C to 70°C, and the effects of temperature, additive dosage and aging onG∗/sin⁡δ, critical temperature, and H-T PG were investigated. The results indicate that WMA additive improvesG∗but reducesδ, and the improvement on 70# virgin binder is more significant.G∗/sin⁡δexponentially decreases with the increasing temperature but linearly increases with the increasing additive dosage. Aging effect weakens the interaction between binder and additive but significantly increases the binder’s viscosity; that is whyG∗/sin⁡δis higher after short-term aging. In addition, the critical temperature increases with the increasing additive dosage, and the additive dosage should be more than 3% and 5% to improve H-T PG by one grade for 70# and 90# virgin binder, respectively.

scholarly journals Resource fluctuations inhibit the reproduction and virulence of the human parasite Schistosoma mansoni in its snail intermediate host

2020 ◽  
Vol 287 (1919) ◽  
pp. 20192446
Author(s):  
David J. Civitello ◽  
Lucy H. Baker ◽  
Selvaganesh Maduraiveeran ◽  
Rachel B. Hartman
Keyword(s):  
Schistosoma Mansoni ◽  
Intermediate Host ◽  
Population Level ◽  
Host Population ◽  
Environmental Drivers ◽  
Bioenergetic Model ◽  
Snail Intermediate Host ◽  
Human Parasite ◽  
Infection Dynamics ◽  
Periodic Starvation

Resource availability can powerfully influence host–parasite interactions. However, we currently lack a mechanistic framework to predict how resource fluctuations alter individual infection dynamics. We address this gap with experiments manipulating resource supply and starvation for a human parasite, Schistosoma mansoni , and its snail intermediate host to test a hypothesis derived from mechanistic energy budget theory: resource fluctuations should reduce schistosome reproduction and virulence by inhibiting parasite ingestion of host biomass. Low resource supply caused hosts to remain small, reproduce less and produce fewer human-infectious cercariae. Periodic starvation also inhibited cercarial production and prevented infection-induced castration. The periodic starvation experiment also revealed substantial differences in fit between two bioenergetic model variants, which differ in their representation of host starvation. Simulations using the best-fit parameters of the winning model suggest that schistosome performance substantially declines with resource fluctuations with periods greater than 7 days. These experiments strengthen mechanistic theory, which can be readily scaled up to the population level to understand key feedbacks between resources, host population dynamics, parasitism and control interventions. Integrating resources with other environmental drivers of disease in an explicit bioenergetic framework could ultimately yield mechanistic predictions for many disease systems.

The effects of temperature on short-term mortality risk in Kuwait: A time-series analysis

2019 ◽  
Vol 171 ◽  
pp. 278-284 ◽  
Author(s):  
Barrak Alahmad ◽  
Ahmed Shakarchi ◽  
Mohammad Alseaidan ◽  
Mary Fox
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Mortality Risk ◽  
Short Term ◽  
Series Analysis ◽  
Short Term Mortality ◽  
Effects Of Temperature
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