scholarly journals Variable host responses mediate host preference in marine flatworm−snail symbioses

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247551
Author(s):  
Juhyung Lee ◽  
Timothy M. Davidson ◽  
Mark E. Torchin

Host preference of symbionts evolves from fitness trade-offs. However, it is often unclear how interspecific variations in host response traits influence this evolutionary process. Using the association between the polyclad flatworm Paraprostatum echinolittorinae and its intertidal snail hosts on the Pacific Coast of Panama, we assessed how a symbiont’s host preference is associated with varying host defenses and post-infestation performances. We first characterized the prevalence and intensity of worm infestation in five snail hosts (Tegula pellisserpentis, Nerita scabricosta, N. funiculata, Planaxis planicostatus, and Cerithium stercusmuscarum). We then used manipulative experiments to test flatworm’s host choice, hosts’ behavioral rejection of flatworms, and hosts’ growth and survival following the infestation. In the field, flatworms were orders of magnitude more prevalent and dense in T. pellisserpentis, N. scabricosta, N. funiculata than P. planicostatus and C. stercusmuscarum, although the three former hosts were not necessarily more abundant. The results from our laboratory host selection trials mirrored these patterns; flatworms were 3 to 14 times more likely to choose T. pellisserpentis, N. scabricosta, N. funiculata over P. planicostatus and C. stercusmuscarum. The less preferred hosts frequently rejected flatworms via mantle contractions and foot withdrawals, which reduced the infestation rate by 39%−67%. These behaviors were less frequent or absent in the preferred hosts. Flatworm infestation variably influenced host performances in the field, negligibly affecting the growth and survival of T. pellisserpentis and N. funiculata but reducing the growth of P. planicostatus. Flatworms thus preferred less defended hosts that can also support higher worm densities without being harmed. Stable isotope analysis further revealed that flatworms are unlikely to feed on snail tissues and may live as a commensal in their preferred hosts. Our study demonstrates that host response traits can modulate a symbiont’s host choice and calls for more explicit considerations of host response variability in host preference research.

1997 ◽  
Vol 75 (4) ◽  
pp. 542-548 ◽  
Author(s):  
P. H. Niewiarowski ◽  
J. D. Congdon ◽  
A. E. Dunham ◽  
L. J. Vitt ◽  
D. W. Tinkle

Potential costs and benefits of tail autotomy in lizards have been inferred almost exclusively from experimental study in semi-natural enclosures and from indirect comparative evidence from natural populations. We present complementary evidence of the costs of tail autotomy to the lizard Uta stansburiana from detailed demographic study of a natural population. On initial capture, we broke the tails of a large sample of free-ranging hatchlings (560) and left the tails of another large sample (455) intact, and then followed subsequent hatchling growth and survival over a 3-year period. Surprisingly, in 1 out of the 3 years of study, survival of female hatchlings with broken tails exceeded that of female hatchlings with intact tails. Furthermore, no effects of tail loss on survivorship were detected for male hatchlings. However, in 2 years when recaptures were very frequent (1961, 1962), growth rates of hatchlings with broken tails were significantly slower than those of their counterparts with intact tails. We discuss our results in the broader context of estimating the relative costs and benefits of tail autotomy in natural populations, and suggest that long-term demographic studies will provide the best opportunity to assess realized fitness costs and benefits with minimum bias. We also describe how experimentally induced tail autotomy can be used as a technique to complement experimental manipulation of reproductive investment in the study of life-history trade-offs.


Parasitology ◽  
2007 ◽  
Vol 134 (12) ◽  
pp. 1767-1774 ◽  
Author(s):  
V. N. MIKHEEV ◽  
A. F. PASTERNAK ◽  
E. T. VALTONEN

SUMMARYWe tested the hypothesis that host specificity in ectoparasites does not depend exclusively on the features of the host but also on surrounding habitats, using 2 fish ectoparasites, Argulus coregoni and A. foliaceus (Crustacea: Branchiura), occurring sympatrically in Finnish lakes. Although these parasites are considered to be of low specificity, we found that the larger of the 2 species, A. coregoni developed a pronounced preference for salmonid hosts at the beginning of maturation (defined by the presence of copulating specimens). Argulus foliaceus infects a much wider range of fish hosts. We showed that specialization of A. coregoni on salmonids does not necessarily result from incompatibility with other fishes, but could instead reflect higher sensitivity of oxygen depletion compared with A. foliaceus. Adult A. coregoni may meet these demands by attaching to salmonids, the typical inhabitants of well-aerated waters. Young parasites of both species showed little host specificity and attached mainly to fishes with higher body reflectivity. In host choice experiments, A. coregoni of 4–5 mm length preferred salmonids (rainbow trout) to cyprinids (roach) irrespective of the type of fish host, on which it had been previously grown in the laboratory. We suggest that such an innate ontogenetic shift in host preference maintains the major part of the parasite population on its principal host, ensuring successful reproduction within suitable habitats.


2020 ◽  
Vol 117 (45) ◽  
pp. 28336-28343 ◽  
Author(s):  
Meng Wu ◽  
Yaobing Chen ◽  
Han Xia ◽  
Changli Wang ◽  
Chin Yee Tan ◽  
...  

Coronavirus disease 2019 (COVID-19), the global pandemic caused by SARS-CoV-2, has resulted thus far in greater than 933,000 deaths worldwide; yet disease pathogenesis remains unclear. Clinical and immunological features of patients with COVID-19 have highlighted a potential role for changes in immune activity in regulating disease severity. However, little is known about the responses in human lung tissue, the primary site of infection. Here we show that pathways related to neutrophil activation and pulmonary fibrosis are among the major up-regulated transcriptional signatures in lung tissue obtained from patients who died of COVID-19 in Wuhan, China. Strikingly, the viral burden was low in all samples, which suggests that the patient deaths may be related to the host response rather than an active fulminant infection. Examination of the colonic transcriptome of these patients suggested that SARS-CoV-2 impacted host responses even at a site with no obvious pathogenesis. Further proteomics analysis validated our transcriptome findings and identified several key proteins, such as the SARS-CoV-2 entry-associated protease cathepsins B and L and the inflammatory response modulator S100A8/A9, that are highly expressed in fatal cases, revealing potential drug targets for COVID-19.


2000 ◽  
Vol 74 (2) ◽  
pp. 155-160 ◽  
Author(s):  
T. Lindenstrøm ◽  
K. Buchmann

AbstractInvestigations were conducted on the host response in rainbow trout and the associated changes in mucous cell density during infection with the skin monogenean Gyrodactylus derjavini. Parasite populations increased on all naive hosts and peaked 4–5 weeks p.i. after which infection levels decreased. Introduction of naive fish into responding host populations resulted in heavy infections of the naive fish, whereas parasite expulsion continued in the responding host groups showing an acquired, non-sterile immunity. This non-sterile immunity lasted at least a month as these hosts were refractory to reinfection despite being exposed to a high infection pressure. Mucous cell hyperplasia was seen in some groups during the intermediary phase of infection, but at the termination of the study a significant depletion was evident. Passive immunization of naive host (with sera from immune hosts) did not confer protection. This indicates differences between host responses to G. derjavini compared to responses against other pathogens where such a passive immunity has been described.


2019 ◽  
Vol 98 ◽  
pp. 12005
Author(s):  
Yongwen Gao ◽  
Joseph Gilbertson ◽  
Hongyan Zhang

The Pacific razor clam fishery in Washington State has been co-managed by the coastal Indian Tribes and the state, but little is known about the growth and population structure of the clams due to difficulties of tagging and monitoring. Here we report the results of a pilot study using stable isotope ratios (δ13C and δ18O) of razor clam shells collected in two groups (juvenile vs. adult) and from two sites (Kalaloch Beach and Roosevelt Beach) where distinct biological differences in clam growth and survival rates were observed. The δ13C values of razor clam shells ranged from -2.9 to -0.3‰, whereas δ18O values of the same samples ranged from -2.2 to +1.4‰. Between the two sites there were significant differences in δ13C values especially for juvenile clams. The δ18O profiles from two representative shells demonstrated similar patterns of rapid growth as juveniles and seasonal patterns throughout the life span. Profiles of δ13C were sinusoidal but did not show seasonality and signatures of ocean acidification. We concluded that stable isotope analysis of razor clam shells is a potential new tool in shellfish research and management.


2003 ◽  
Vol 77 (2) ◽  
pp. 125-131 ◽  
Author(s):  
Y.R. Mahida

AbstractIn rodents,Trichinella spiralisandNippostrongylus brasiliensisinfect the small intestine andTrichuris murisresides in the colon. The intestinal host response in these animals is characterized by changes in mucosal architecture and inflammation and is associated with worm expulsion. The requirement of T cell-mediated host response in worm expulsion has been demonstrated over many years. Subsequent studies have shown that Th2-type, but not Th1-type, responses mediate resistance to the nematodes. Investigations using neutralizing antibodies and genetically manipulated mice have characterized the contribution of individual Th2-type cytokines in not only worm expulsion, but also specific cellular changes that occur in the mucosa, such as alterations in epithelial phenotype and smooth muscle. There is also increasing appreciation of the contribution of non-bone marrow-derived cells in innate and adaptive host responses in these models.


2018 ◽  
Vol 373 (1745) ◽  
pp. 20170100 ◽  
Author(s):  
Maureen H. Murray ◽  
Anjelika D. Kidd ◽  
Shannon E. Curry ◽  
Jeffrey Hepinstall-Cymerman ◽  
Michael J. Yabsley ◽  
...  

Many wildlife species shift their diets to use novel resources in urban areas. The consequences of these shifts are not well known, and consumption of reliable—but low quality—anthropogenic food may present important trade-offs for wildlife health. This may be especially true for carnivorous species such as the American white ibis ( Eudocimus albus ), a nomadic wading bird which has been increasingly observed in urban parks in South Florida, USA. We tested the effects of anthropogenic provisioning on consumer nutrition (i.e. dietary protein), body condition and ectoparasite burdens along an urban gradient using stable isotope analysis, scaled mass index values and GPS transmitter data. Ibises that assimilated more provisioned food were captured at more urban sites, used more urban habitat, had lower mass–length residuals, lower ectoparasite scores, assimilated less δ 15N and had smaller dietary isotopic ellipses. Our results suggest that ibises in urban areas are heavily provisioned with anthropogenic food, which appears to offer a trade-off by providing low-quality, but easily accessible, calories that may not support high mass but may increase time available for anti-parasite behaviours such as preening. Understanding such trade-offs is important for investigating the effects of provisioning on infection risk and the conservation of wildlife in human-modified habitats. This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife’.


Critical Care ◽  
2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Jesús F. Bermejo-Martin ◽  
Milagros González-Rivera ◽  
Raquel Almansa ◽  
Dariela Micheloud ◽  
Ana P. Tedim ◽  
...  

Abstract Background COVID-19 can course with respiratory and extrapulmonary disease. SARS-CoV-2 RNA is detected in respiratory samples but also in blood, stool and urine. Severe COVID-19 is characterized by a dysregulated host response to this virus. We studied whether viral RNAemia or viral RNA load in plasma is associated with severe COVID-19 and also to this dysregulated response. Methods A total of 250 patients with COVID-19 were recruited (50 outpatients, 100 hospitalized ward patients and 100 critically ill). Viral RNA detection and quantification in plasma was performed using droplet digital PCR, targeting the N1 and N2 regions of the SARS-CoV-2 nucleoprotein gene. The association between SARS-CoV-2 RNAemia and viral RNA load in plasma with severity was evaluated by multivariate logistic regression. Correlations between viral RNA load and biomarkers evidencing dysregulation of host response were evaluated by calculating the Spearman correlation coefficients. Results The frequency of viral RNAemia was higher in the critically ill patients (78%) compared to ward patients (27%) and outpatients (2%) (p < 0.001). Critical patients had higher viral RNA loads in plasma than non-critically ill patients, with non-survivors showing the highest values. When outpatients and ward patients were compared, viral RNAemia did not show significant associations in the multivariate analysis. In contrast, when ward patients were compared with ICU patients, both viral RNAemia and viral RNA load in plasma were associated with critical illness (OR [CI 95%], p): RNAemia (3.92 [1.183–12.968], 0.025), viral RNA load (N1) (1.962 [1.244–3.096], 0.004); viral RNA load (N2) (2.229 [1.382–3.595], 0.001). Viral RNA load in plasma correlated with higher levels of chemokines (CXCL10, CCL2), biomarkers indicative of a systemic inflammatory response (IL-6, CRP, ferritin), activation of NK cells (IL-15), endothelial dysfunction (VCAM-1, angiopoietin-2, ICAM-1), coagulation activation (D-Dimer and INR), tissue damage (LDH, GPT), neutrophil response (neutrophils counts, myeloperoxidase, GM-CSF) and immunodepression (PD-L1, IL-10, lymphopenia and monocytopenia). Conclusions SARS-CoV-2 RNAemia and viral RNA load in plasma are associated with critical illness in COVID-19. Viral RNA load in plasma correlates with key signatures of dysregulated host responses, suggesting a major role of uncontrolled viral replication in the pathogenesis of this disease.


2015 ◽  
Vol 14 (10) ◽  
pp. 1043-1053 ◽  
Author(s):  
Eric R. G. Lewis ◽  
Victoria R. David ◽  
Adina L. Doyle ◽  
Khadijeh Rajabi ◽  
Jeffrey A. Kiefer ◽  
...  

ABSTRACTCoccidioides immitisandCoccidioides posadasiiare soil-dwelling fungi and the causative agents of coccidioidomycosis, a mycosis endemic to certain semiarid regions in the Americas. The most common route of infection is by inhalation of airborneCoccidioidesarthroconidia. Once a susceptible host inhales the conidia, a transition to mature endosporulated spherules can occur within the first 5 days of infection. For this study, we examined the host response in a murine model of coccidioidomycosis during a time period of infection that has not been well characterized. We collected lung tissue and bronchoalveolar lavage fluid (BALF) from BALB/c mice that were infected with aC. immitispure strain, aC. immitishybrid strain, or aC. posadasiistrain as well as uninfected mice. We compared the host responses to theCoccidioidesstrains used in this study by assessing the level of transcription of selected cytokine genes in lung tissues and characterized host and fungal proteins present in BALF. Host response varied depending on theCoccidioidesstrain that was used and did not appear to be overly robust. This study provides a foundation to begin to dissect the host immune response early in infection, to detect abundantCoccidioidesproteins, and to develop diagnostics that target these early time points of infection.


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