scholarly journals Developing a dedicated cestode life cycle database: lessons from the hymenolepidids

2009 ◽  
Vol 46 (1) ◽  
pp. 21-27 ◽  
Author(s):  
F. Lefebvre ◽  
B. Georgiev ◽  
R. Bray ◽  
D. Littlewood
Keyword(s):  
Life Cycle ◽  
Open Access ◽  
Intermediate Host ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Short Version ◽  
Electronic Database ◽  
Model Group ◽  
Future Needs

AbstractThe Cestode Life Cycle Database (CLCdb) project was initiated in 2005 with the objective to develop a comprehensive and centralised resource to store, retrieve and analyse key information concerning tapeworm life cycles; e.g. morphogenesis, intermediate host identities, transmission patterns, etc. It constitutes the first electronic database to deal with complex life cycle information for any helminth taxon. Here we critically evaluate our experience after exhaustively entering data for our model group, the cyclophyllidean family Hymenolepididae. After providing basic statistics (530 consulted references; ∼ 230 ‘known’ life cycle), we identify future needs in turning the CLCdb into an open access monograph covering all cestode groups. We review the added benefits and potential utilities of the database for cestodologists and other users, including ecologists and veterinarians, and we call for specialist contributions. Since late 2007, a short version of the CLCdb has been available online, with basic functionalities and tools (www.nhm.ac.uk/research-curation/projects/cestode-life-cycle/index.html).

scholarly journals Major host transitions are modulated through transcriptome-wide reprograming events in Schistocephalus solidus, a threespine stickleback parasite

2016 ◽  
Author(s):  
François Olivier Hébert ◽  
Stephan Grambauer ◽  
Iain Barber ◽  
Christian R Landry ◽  
Nadia Aubin-Horth
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Final Host ◽  
Life Cycles ◽  
Threespine Stickleback ◽  
Complex Life Cycle ◽  
Ecological Niches ◽  
Avian Host ◽  
Complex Life Cycles ◽  
Schistocephalus Solidus

ABSTRACTParasites with complex life cycles have developed numerous phenotypic strategies, closely associated with developmental events, to enable the exploitation of different ecological niches and facilitate transmission between hosts. How these environmental shifts are regulated from a metabolic and physiological standpoint, however, still remain to be fully elucidated. We examined the transcriptomic response of Schistocephalus solidus, a trophically-transmitted parasite with a complex life cycle, over the course of its development in an intermediate host, the threespine stickleback, and the final avian host. Results from our differential gene expression analysis show major reprogramming events among developmental stages. The final host stage is characterized by a strong activation of reproductive pathways and redox homeostasis. The attainment of infectivity in the fish intermediate host – which precedes sexual maturation in the final host and is associated with host behaviour changes – is marked by transcription of genes involved in neural pathways and sensory perception. Our results suggest that un-annotated and S. solidus-specific genes could play a determinant role in host-parasite molecular interactions required to complete the parasite’s life cycle. Our results permit future comparative analyses to help disentangle species-specific patterns of infection from conserved mechanisms, ultimately leading to a better understanding of the molecular control and evolution of complex life cycles.

The Output of First Stage Larvae by Cats Infested with Aelurostrongylus abstrusus

1968 ◽  
Vol 42 (3-4) ◽  
pp. 295-298 ◽  
Author(s):  
J. M. Hamilton ◽  
A. W. McCaw
Keyword(s):  
Life Cycle ◽  
Great Britain ◽  
Intermediate Host ◽  
World Wide ◽  
Wide Distribution ◽  
Clinical Disease ◽  
Complex Life Cycle ◽  
Patent Period ◽  
Aelurostrongylus Abstrusus

Aelurostrongylus abstrusus, the lungworm of the cat, has a world wide distribution and has been reported from countries as far apart as America, Great Britain and Palestine. It has a complex life cycle insofar as a molluscan intermediate host is essential and it is possible that auxiliary hosts also play an important part. In Britain, the incidence of active infestation of cats with the parasite has been recorded as 19·4% (Lewis, 1927) and 6·6% (Hamilton, 1966) but the latter author found that, generally, the clinical disease produced by the parasite was of a mild nature. It is known that the average patent period of the infestation in the cat is 8–13 weeks and it seems likely that, in that time, a considerable number of first stage larvae would be evacuated. Information on that point is not available and the object of the following experiment was to ascertain the number of larvae produced by cats during the course of a typical infestation.

Autonomy and integration in complex parasite life cycles

Parasitology ◽  
2016 ◽  
Vol 143 (14) ◽  
pp. 1824-1846 ◽  
Author(s):  
DANIEL P. BENESH
Keyword(s):  
Life Cycle ◽  
Holistic Approach ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Functional Specialization ◽  
Life Stages ◽  
Free Living ◽  
New Host ◽  
Complex Life Cycles ◽  
Life Cycle Stages

SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.

Encystment site affects the reproductive strategy of a progenetic trematode in its fish intermediate host: is host spawning an exit for parasite eggs?

Parasitology ◽  
2011 ◽  
Vol 138 (9) ◽  
pp. 1183-1192 ◽  
Author(s):  
KRISTIN K. HERRMANN ◽  
ROBERT POULIN
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Body Cavity ◽  
Life Cycles ◽  
Temperature Changes ◽  
Fish Spawning ◽  
Second Intermediate Host ◽  
Host Life ◽  
Major Factors ◽  
Fish Hosts

SUMMARYEach transmission event in complex, multi-host life cycles create obstacles selecting for adaptations by trematodes. One such adaptation is life cycle abbreviation through progenesis, in which the trematode precociously matures and reproduces within the second intermediate host. Progenesis eliminates the need for the definitive host and increases the chance of life cycle completion. However, progenetic individuals face egg-dispersal challenges associated with reproducing within metacercarial cysts in the tissues or body cavity of the second intermediate host. Most progenetic species await host death for their eggs to be released into the environment. The present study investigated temporal variation of progenesis in Stegodexamene anguillae in one of its second intermediate fish hosts and the effect of the fish's reproductive cycle on progenesis. The study involved monthly sampling over 13 months at one locality. A greater proportion of individuals became progenetic in the gonads of female fish hosts. Additionally, progenesis of worms in the gonads was correlated with seasonal daylight and temperature changes, major factors controlling fish reproduction. Host spawning events are likely to be an avenue of egg dispersal for this progenetic species, with the adoption of progenesis being conditional on whether or not the parasite can benefit from fish spawning.

Smelling the future: subtle life-history adjustments in response to environmental conditions and perceived transmission opportunities in a trematode

Parasitology ◽  
2016 ◽  
Vol 144 (4) ◽  
pp. 464-474 ◽  
Author(s):  
C. LAGRUE ◽  
R. RINNEVALLI ◽  
R. POULIN
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Intermediate Host ◽  
Definitive Host ◽  
Environmental Conditions ◽  
Life History Strategy ◽  
Host Density ◽  
Life Cycles ◽  
Life History Strategies ◽  
Priming Effects

SUMMARYA number of parasites with complex life cycles can abbreviate their life cycles to increase the likelihood of reproducing. For example, some trematodes can facultatively skip the definitive host and produce viable eggs while still inside their intermediate host. The resulting shorter life cycle is clearly advantageous when transmission probabilities to the definitive hosts are low. Coitocaecum parvum can mature precociously (progenesis), and produce eggs by selfing inside its amphipod second intermediate host. Environmental factors such as definitive host density and water temperature influence the life-history strategy adopted by C. parvum in their crustacean host. However, it is also possible that information about transmission opportunities gathered earlier in the life cycle (i.e. by cercariae-producing sporocysts in the first intermediate host) could have priming effects on the adoption of one or the other life strategy. Here we document the effects of environmental parameters (host chemical cues and temperature) on cercarial production within snail hosts and parasite life-history strategy in the amphipod host. We found that environmental cues perceived early in life have limited priming effects on life-history strategies later in life and probably account for only a small part of the variation among conspecific parasites. External cues gathered at the metacercarial stage seem to largely override potential effects of the environmental conditions experienced by early stages of the parasite.

Lack of seasonal variation in the life-history strategies of the trematode Coitocaecum parvum: no apparent environmental effect

Parasitology ◽  
2008 ◽  
Vol 135 (10) ◽  
pp. 1243-1251 ◽  
Author(s):  
C. LAGRUE ◽  
R. POULIN
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Life Cycle ◽  
Water Temperature ◽  
Intermediate Host ◽  
Definitive Host ◽  
Natural Environment ◽  
Life History Strategy ◽  
Life Cycles ◽  
Coitocaecum Parvum

SUMMARYParasites with complex life cycles have developed numerous and very diverse adaptations to increase the likelihood of completing this cycle. For example, some parasites can abbreviate their life cycles by skipping the definitive host and reproducing inside their intermediate host. The resulting shorter life cycle is clearly advantageous when definitive hosts are absent or rare. In species where life-cycle abbreviation is facultative, this strategy should be adopted in response to seasonally variable environmental conditions. The hermaphroditic trematode Coitocaecum parvum is able to mature precociously (progenesis), and produce eggs by selfing while still inside its amphipod second intermediate host. Several environmental factors such as fish definitive host density and water temperature are known to influence the life-history strategy adopted by laboratory raised C. parvum. Here we document the seasonal variation of environmental parameters and its association with the proportion of progenetic individuals in a parasite population in its natural environment. We found obvious seasonal patterns in both water temperature and C. parvum host densities. However, despite being temporally variable, the proportion of progenetic C. parvum individuals was not correlated with any single parameter. The results show that C. parvum life-history strategy is not as flexible as previously thought. It is possible that the parasite's natural environment contains so many layers of heterogeneity that C. parvum does not possess the ability to adjust its life-history strategy to accurately match the current conditions.

The effect of Toxoplasma gondii and other parasites on activity levels in wild and hybrid Rattus norvegicus

Parasitology ◽  
1994 ◽  
Vol 109 (5) ◽  
pp. 583-589 ◽  
Author(s):  
J. P. Webster
Keyword(s):  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Intermediate Host ◽  
Definitive Host ◽  
Rattus Norvegicus ◽  
Parasite Load ◽  
Life Cycles ◽  
Parasitic Infections ◽  
Activity Levels ◽  
In The Wild

Using both correlational and experimental evidence, the relationship between parasite load and host activity was assessed in brown rats, Rattus norvegicus. Two hypotheses were tested – (1) that parasites with indirect life-cycles, involving transmission between a prey and its predator, will alter the activity of the intermediate host so as to increase its susceptibility to predation by the definitive host and (2) that activity levels in parasitized rats would be increased rather than decreased. Four groups of rats (n = 140) were examined. One group (n = 50) were wild brown rats trapped from 3 UK farmsteads, with naturally occurring parasites. The others were purpose-bred wild/laboratory hybrid rats with experimentally induced parasitic infections of either (n = 15) adult-acquired or (n = 15) congenitally-acquired Toxoplasma gondii (an indirect life-cycle parasite), or (n = 15) Syphacia muris (a direct life-cycle parasite). Uninfected hybrid rats (n = 45), matched for sex, age and weight, served as controls. Rats were housed individually in outdoor cages, and their activities were recorded on video-tapes for 6 non-consecutive 10 h nights. Exercise wheels were also available for the hybrid rats. Out of 6 parasite species detected in the wild rats, T. gondii was the only one which required predation by a definitive host to complete its life-cycle, and was also the only parasite to be associated with higher activity levels in infected than uninfected rats. Hybrid rats infected with T. gondii were also more active than those uninfected, whereas there were no differences in activity levels between S. muris infected and uninfected rats. This study shows that the indirect life-cycle parasite T. gondii can influence the activity of its intermediate host the rat. I suggest that this may facilitate its transmission to the cat definitive host.

scholarly journals Developmental plasticity and the evolution of animal complex life cycles

2010 ◽  
Vol 365 (1540) ◽  
pp. 631-640 ◽  
Author(s):  
Alessandro Minelli ◽  
Giuseppe Fusco
Keyword(s):  
Life Cycle ◽  
Developmental Plasticity ◽  
Developmental Stages ◽  
Ecological Condition ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Complex Life Cycles ◽  
Transcription Profiles ◽  
Alternative Phenotypes ◽  
Reproductive Events

Metazoan life cycles can be complex in different ways. A number of diverse phenotypes and reproductive events can sequentially occur along the cycle, and at certain stages a variety of developmental and reproductive options can be available to the animal, the choice among which depends on a combination of organismal and environmental conditions. We hypothesize that a diversity of phenotypes arranged in developmental sequence throughout an animal's life cycle may have evolved by genetic assimilation of alternative phenotypes originally triggered by environmental cues. This is supported by similarities between the developmental mechanisms mediating phenotype change and alternative phenotype determination during ontogeny and the common ecological condition that favour both forms of phenotypic variation. The comparison of transcription profiles from different developmental stages throughout a complex life cycle with those from alternative phenotypes in closely related polyphenic animals is expected to offer critical evidence upon which to evaluate our hypothesis.

scholarly journals Comparative analysis of helminth infectivity: growth in intermediate hosts increases establishment rates in the next host

2021 ◽  
Vol 288 (1947) ◽  
Author(s):  
Spencer Froelick ◽  
Laura Gramolini ◽  
Daniel P. Benesh
Keyword(s):  
Life Cycle ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Intermediate Hosts ◽  
Cycle Progression ◽  
Recovery Rates ◽  
High Doses ◽  
Parasitic Worms ◽  
Higher Doses

Parasitic worms (i.e. helminths) commonly infect multiple hosts in succession before reproducing. At each life cycle step, worms may fail to infect the next host, and this risk accumulates as life cycles include more successive hosts. Risk accumulation can be minimized by having high establishment success in the next host, but comparisons of establishment probabilities across parasite life stages are lacking. We compiled recovery rates (i.e. the proportion of parasites recovered from an administered dose) from experimental infections with acanthocephalans, cestodes and nematodes. Our data covered 127 helminth species and 16 913 exposed hosts. Recovery rates increased with life cycle progression (11%, 29% and 46% in first, second and third hosts, respectively), because larger worm larvae had higher recovery, both within and across life stages. Recovery declined in bigger hosts but less than it increased with worm size. Higher doses were used in systems with lower recovery, suggesting that high doses are chosen when few worms are expected to establish infection. Our results indicate that growing in the small and short-lived hosts at the start of a complex life cycle, though dangerous, may substantially improve parasites' chances of completing their life cycles.

scholarly journals Parasites are Particularly Problematic

2018 ◽  
Vol 2 ◽  
pp. e25604
Author(s):  
Susan Perkins
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Information Content ◽  
Definitive Host ◽  
Complex Life Cycle ◽  
Phylogenetic Study ◽  
Biodiversity Informatics ◽  
Malaria Parasites ◽  
Parasitic Organism

Although they are hyperdiverse and intensively studied, parasites present major challenges when it comes to phylogenetics, taxonomy, and biodiversity informatics. The collection of any parasitic organism entails the linking of at least two specimens - the parasite and the host. If the parasite has a complex life cycle, then this becomes further complicated by requiring the linking of three or more hosts, such as the parasite, its intermediate host (vector) and its definitive host(s). Parasites are sometimes collected as byproduct of another collection event and are not studied immediately - which has the potential to disconnect them further in terms of information content and continuity- and the converse if also common - parasites can be collected by parasitologists, who do not necessarily take host vouchers or incorporate host taxonomy, let alone other metadata for these events. Using the specific example of the malaria parasites (Order Haemosporida) I will present examples of the specific challenges that have accompanied the study of these parasites including issues of delimiting species, phylogenetic study, including genetic oddities that are unique to these organisms, and taxonomic quandries that we now find ourselves in, along with other problems with maintaining continuity of information in a group that is both diverse biologically and important medically.

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