483 research outputs found
Vetufebrus ovatus n. gen., n. sp. (Haemospororida: Plasmodiidae) vectored by a streblid bat fly (Diptera: Streblidae) in Dominican amber
This is the publisher’s final pdf. The published article is copyrighted by BioMed Central Ltd. and can be found at: http://www.parasitesandvectors.com/.Background: Both sexes of bat flies in the families Nycteribiidae and Streblidae (Diptera: Hippoboscoidea) reside in\ud
the hair or on the wing membranes of bats and feed on blood. Members of the Nycteribiidae transmit bat malaria\ud
globally however extant streblids have never been implemented as vectors of bat malaria. The present study\ud
shows that during the Tertiary, streblids also were vectors of bat malaria.\ud
Results: A new haemospororidan, Vetufebrus ovatus, n. gen., n. sp., (Haemospororida: Plasmodiidae) is described\ud
from two oocysts attached to the midgut wall and sporozoites in salivary glands and ducts of a fossil bat fly\ud
(Diptera: Streblidae) in Dominican amber. The new genus is characterized by ovoid oocysts, short, stubby\ud
sporozoites with rounded ends and its occurrence in a fossil streblid. This is the first haemosporidian reported from\ud
a streblid bat fly and shows that representatives of the Hippoboscoidea were vectoring bat malaria in the New\ud
World by the mid-Tertiary.\ud
Conclusions: This report is the first evidence of an extant or extinct streblid bat fly transmitting malaria.\ud
Discovering a mid-tertiary malarial parasite in a fossil streblid that closely resembles members of a malarial genus\ud
found in nycteribiid bat flies today shows how little we know about the vector associations of streblids. While no\ud
malaria parasites have been found in extant streblids, they probably occur and it is possible that streblids were the\ud
earliest lineage of flies that transmitted bat malaria to Chiroptera
Species of Bursaphelenchus Fuchs, 1937 (Nematoda: Parasitaphelenchidae) and other nematode genera associated with insects from Pinus pinaster in Portugal
Insects associated with maritime pine, Pinus pinaster, in Portugal were collected
and screened for the presence of Bursaphelenchus species. Nematodes were
identified using Internal Transcribed Spacers-Restriction Fragment Length
Polymorphism (ITS-RFLP) analysis of dauer juveniles and morphological
identification of adults that developed from dauer juveniles on fungal cultures
or on cultures in pine wood segments at 26 C. Several associations are
described: Bursaphelenchus teratospicularis and Bursaphelenchus sexdentati are
associated with Orthotomicus erosus; Bursaphelenchus tusciae, B. sexdentati and/or
Bursaphelenchus pinophilus with Hylurgus ligniperda and Bursaphelenchus hellenicus
with Tomicus piniperda, Ips sexdentatus and H. ligniperda. An unidentified
Bursaphelenchus species is vectored by Hylobius sp. The previously reported
association of Bursaphelenchus xylophilus with Monochamus galloprovincialis
was confirmed. The association of Bursaphelenchus leoni with Pityogenes sp. is
not definitively established and needs further studies for clarification.
Other nematode genera besides Bursaphelenchus were found to be associated
with the insects sampled, including two different species of Ektaphelenchus, Parasitorhabditis
sp., Parasitaphelenchus sp., Contortylenchus sp. and other unidentified
nematodes. The Ektaphelenchus species found in O. erosus is morphologically
similar to B. teratospicularis found in the same insect; adults of both the species
are found in cocoon-like structures under the elytra of the insects.
Introduction
Approximately one third of the nematodes belonging to
the order Aphelenchida Siddiqi, 1980 are associated with
insects (Poinar, 1983). These nematodes establish a variety
of associations with the insects, which may be
described as commensalism, e.g. phoresy (to the benefit
of the nematode but not affecting the insect), mutualism
(both the organisms benefit) or parasitism (nematodes
benefit at the expense of the insect) (Giblin-Davis,
2004).
Most Bursaphelenchus Fuchs, 1937 species are mycetophagous,
feeding on fungi in the galleries of bark beetles
and thu
The Justinianic Plague: an inconsequential pandemic?
Existing mortality estimates assert that the Justinianic Plague (circa 541 to 750 CE) caused tens of millions of deaths throughout the Mediterranean world and Europe, helping to end antiquity and start the Middle Ages. In this article, we argue that this paradigm does not fit the evidence. We examine a series of independent quantitative and qualitative datasets that are directly or indirectly linked to demographic and economic trends during this two-century period: Written sources, legislation, coinage, papyri, inscriptions, pollen, ancient DNA, and mortuary archaeology. Individually or together, they fail to support the maximalist paradigm: None has a clear independent link to plague outbreaks and none supports maximalist reconstructions of late antique plague. Instead of large-scale, disruptive mortality, when contextualized and examined together, the datasets suggest continuity across the plague period. Although demographic, economic, and political changes continued between the 6th and 8th centuries, the evidence does not support the now commonplace claim that the Justinianic Plague was a primary causal factor of them. © 2019 National Academy of Sciences. All rights reserved
Nematode endoparasites do not codiversify with their stick insect hosts.
Host-parasite coevolution stems from reciprocal selection on host resistance and parasite infectivity, and can generate some of the strongest selective pressures known in nature. It is widely seen as a major driver of diversification, the most extreme case being parallel speciation in hosts and their associated parasites. Here, we report on endoparasitic nematodes, most likely members of the mermithid family, infecting different Timema stick insect species throughout California. The nematodes develop in the hemolymph of their insect host and kill it upon emergence, completely impeding host reproduction. Given the direct exposure of the endoparasites to the host's immune system in the hemolymph, and the consequences of infection on host fitness, we predicted that divergence among hosts may drive parallel divergence in the endoparasites. Our phylogenetic analyses suggested the presence of two differentiated endoparasite lineages. However, independently of whether the two lineages were considered separately or jointly, we found a complete lack of codivergence between the endoparasitic nematodes and their hosts in spite of extensive genetic variation among hosts and among parasites. Instead, there was strong isolation by distance among the endoparasitic nematodes, indicating that geography plays a more important role than host-related adaptations in driving parasite diversification in this system. The accumulating evidence for lack of codiversification between parasites and their hosts at macroevolutionary scales contrasts with the overwhelming evidence for coevolution within populations, and calls for studies linking micro- versus macroevolutionary dynamics in host-parasite interactions
Infection by the castrating parasitic nematode <i>Sphaerularia bombi </i>changes gene expression in <i>Bombus terrestris </i>bumblebee queens
Parasitism can result in dramatic changes in host phenotype, which are themselves
underpinned by genes and their expression. Understanding how hosts respond at the molecular
level to parasites can therefore reveal the molecular architecture of an altered host phenotype.
The entomoparasitic nematode Sphaerularia bombi is a parasite of bumblebee (Bombus) hosts
where it induces complex behavioural changes and host castration. To examine this interaction
at the molecular level, we performed genome-wide transcriptional profiling using RNA-Seq of S.
bombi-infected Bombus terrestris queens at two critical time-points: during and just after
overwintering diapause. We found that infection by S. bombi affects the transcription of genes
underlying host biological processes associated with energy usage, translation, and circadian
rhythm. We also found that the parasite affects the expression of immune genes, including
members of the Toll signaling pathway providing evidence for a novel interaction between the
parasite and the host immune response. Taken together, our results identify host biological
processes and genes affected by an entomoparasitic nematode providing the first steps towards
a molecular understanding of this ecologically important host-parasite interaction
Ancient Mitogenomes Shed Light on the Evolutionary History and Biogeography of Sloths
International audienc
Quantification of damage in DNA recovered from highly degraded samples – a case study on DNA in faeces
BACKGROUND: Poorly preserved biological tissues have become an important source of DNA for a wide range of zoological studies. Measuring the quality of DNA obtained from these samples is often desired; however, there are no widely used techniques available for quantifying damage in highly degraded DNA samples. We present a general method that can be used to determine the frequency of polymerase blocking DNA damage in specific gene-regions in such samples. The approach uses quantitative PCR to measure the amount of DNA present at several fragment sizes within a sample. According to a model of random degradation the amount of available template will decline exponentially with increasing fragment size in damaged samples, and the frequency of DNA damage (λ) can be estimated by determining the rate of decline. RESULTS: The method is illustrated through the analysis of DNA extracted from sea lion faecal samples. Faeces contain a complex mixture of DNA from several sources and different components are expected to be differentially degraded. We estimated the frequency of DNA damage in both predator and prey DNA within individual faecal samples. The distribution of fragment lengths for each target fit well with the assumption of a random degradation process and, in keeping with our expectations, the estimated frequency of damage was always less in predator DNA than in prey DNA within the same sample (mean λ(predator )= 0.0106 per nucleotide; mean λ(prey )= 0.0176 per nucleotide). This study is the first to explicitly define the amount of template damage in any DNA extracted from faeces and the first to quantify the amount of predator and prey DNA present within individual faecal samples. CONCLUSION: We present an approach for characterizing mixed, highly degraded PCR templates such as those often encountered in ecological studies using non-invasive samples as a source of DNA, wildlife forensics investigations and ancient DNA research. This method will allow researchers to measure template quality in order to evaluate alternate sources of DNA, different methods of sample preservation and different DNA extraction protocols. The technique could also be applied to study the process of DNA decay
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