86 research outputs found
Yeasts in amphibians are common: isolation and the first molecular characterization from Thailand
A survey of the presence of yeasts in frogs and toads in Thailand was conducted using standard mycological examination techniques. The results, which were confirmed with molecular techniques, revealed the presence of five yeast species-Cryptococcus liquefaciens, C. heveanensis, Pseudozyma hubeiensis, Rhodotorula mucilaginosa and R. minuta-in the bile of these amphibians. Although previous works have isolated yeasts from amphibian gastrointestinal tracts and skin, it is questionable whether these yeasts were acquired by ingestion or were commensals on adult individuals. Frog farms, an urban area and protected natural areas were surveyed and all tested positive for yeasts, which shows their ubiquity in both wild and farm-reared frogs. Additionally, the finding of yeasts in five different species of frogs and toads shows that there is a wide spectrum of hosts in this vertebrate group. Our results thus suggest that yeasts are likely to be widespread among amphibians in different habitat types and in a wide range of host species
Stowaways of a Stowaway: Parasites of Invasive Rodents
Human-induced ecosystem modifications include the introduction of alien species, among which rodents are particularly widespread. The expansion and adaptations of invasive rodents, which can come from distant regions, even different continents, have a wide spectrum of ecological consequences, including the spread of parasites and pathogens. As the title of this Research Topic reflects, the parasites travel to these newly colonized areas as stowaways on a stowaway (1, 2). Studies of parasites of invasive rodents have focused mainly on those carried by the genera Rattus and Mus. The available literature describes the parasites found and their prevalence, with particular attention given to zoonotic species that pose a threat for human health, and analyses of the specific host traits that enable successful invasions. Some recent studies have also investigated the spillover effect, shedding light on how the stowaway parasites are transmitted to native rodent species, and the role played by both invasive and native animals in transmission dynamics and maintenance of the new parasites in colonized environments. Our aim here is to focus on recent work in the field, dealing with previously unexplored Research Topics, and to identify research gaps and new questions to be pursued in the future
Spermatological characteristics of the family Glypthelminthidae (Digenea, Plagiorchioidea) inferred from the ultrastructural study of Glypthelmins staffordi Tubangui, 1928
The present study describes the ultrastructural organization of the mature spermatozoon of the digenean Glypthelmins staffordi (Glypthelminthidae) by means of transmission electron microscopy. Live digeneans were collected from the Chinese edible frog (Hoplobatrachus rugulosus) in Udon Thani Province (Thailand). The ultrastructural study reveals that the mature spermatozoon of G. staffordi is a filiform cell, which is tapered at both extremities. It exhibits the Bakhoum et al.'s type IV of spermatozoon of digeneans characterized by the 9+'1' axonemes of trepaxonematan Platyhelminthes, the presence of the association 'external ornamentation-cortical microtubules', the external ornamentation located in the posterior part of the anterior region, the arrangement of parallel cortical microtubules in two bundles and with its maximum number located in the anterior part of the sperm cell, and the presence of two mitochondria. Other characteristics are the presence of spine-like bodies, a posterior extremity containing only the nucleus, and the presence of a large amount of glycogen granules. Results of the present study are particularly compared with the existing data in other families of the Plagiorchioidea, namely the Brachycoeliidae, the Haematoloechidae, the Omphalometridae and the Plagiorchiidae
The diet of the genet (Genetta genetta Linnaeus, 1758) as a source of information on local small mammal communities
Small mammals are the most diverse group of species within mammals. However, sampling the small mammal communities living in a defined area (with a degree of completeness) can be complex, due to the fact that species showed different niche use, behavior, and body size. Traditionally, sampling with traps is one of the most commonly used techniques to investigate the composition of small mammal communities (Fonturbel 2010)
Ultrastructural characters of the spermatozoon of the liver fluke Opisthorchis viverrini (Poirier, 1886) (Opisthorchiidae)
The present study records the ultrastructural organization of the mature spermatozoon of Opisthorchis viverrini by means of transmission electron microscopy. The spermatozoon of O. viverrini is a filiform cell, tapered at both extremities. It exhibits the characteristics of type IV spermatozoon of digeneans, namely with two axonemes of the 9+'1' trepaxonematan pattern, external ornamentation of the plasma membrane associated with cortical microtubules that are in the posterior part of the anterior region of the sperm cell, and with two mitochondria. The maximal number of cortical microtubules is in the anterior part of the spermatozoon and arranged into two bundles. Other characteristics are spine-like bodies and a posterior extremity with only the second axoneme. Ultrastructural characters of the spermatozoon of O. viverrini are compared with those of other known digeneans belonging to the Opisthorchioidea, with particular emphasis on representatives of the family Opisthorchiidae. The main differences between O. viverrini and its congener Opisthorchis felineus are the spine-like bodies (present and absent, respectively) and the posterior spermatozoon character (axoneme and nucleus, respectively)
Aonchotheca yannickchavali n. sp. (Nematoda: Capillariidae) in Bandicota indica (Bechstein, 1800) and Bandicota savilei (Thomas, 1916) from Thailand
During previous surveys of helminths in rodents from Southeast Asia, an unnamed species ofAoncho-thecawas recovered from the stomach of several rodent species. In the present study, the description ofthe new speciesAonchotheca yannickchavalin. sp. is provided based on both female and male specimenscollected from two bandicoot rat species (Bandicota indicaandBandicota savilei) from Thailand (Buriramand Nan provinces). This nematode can be separated from other knownAonchothecafound in rodents byits microhabitat in the host and by the size of the spicules in males and the vulvar appendage in females
Sperm characteristics in the digenean Diplodiscus amphichrus (Paramphistomoidea, Diplodiscidae), a parasite of the Chinese edible frog Hoplobatrachus rugulosus
The ultrastructural characteristics of the mature spermatozoon of Diplodiscus amphichrus (Digenea, Paramphistomoidea, Diplodiscidae) and their ultrastructural organisation were examined by means of transmission electron microscopy. Live digeneans were collected from the Chinese edible frog Hoplobatrachus rugulosus in Thailand. The male gamete of D. amphichrus is a fliform cell with two axonemes of the 9+'1' trepaxonematan pattern, nucleus, one mitochondrion, parallel cortical microtubules, a well-developed lateral expansion, external ornamentation of the plasma membrane, spine-like bodies, and granules of glycogen. These ultrastructural characteristics have already been described in other paramphistomoids studied so far except for the cladorchiids, which present some diferences. Two characteristics of the male gamete of D. amphichrus were found for the frst time in a digenean: (i) the appearance of the initial part of the lateral expansion before the axonemes in the anterior extremity and (ii) the separation between the second axoneme and the nucleus in the posterior tip. Our results are compared with the available data in the Digenea and particularly with other paramphistomoids
Effects of parasite and historic driven selection on the diversity and structure of a MHC-II gene in a small mammal species (Peromyscus leucopus) undergoing range expansion.
Abstract Genetic diversity may decrease from the centre to the margin of a species distribution range due to neutral stochastic processes. Selection may also alter genetic diversity in non-neutral markers, such as genes associated with the immune system. Both neutral processes and selection on the immune system are thus expected to affect the spatial distribution of such markers, but the relative strength of each has been scarcely studied. Here, we compared the diversity of a neutral marker (mitochondrial cytochrome b)and a selected marker (DRB gene from the MHC-II), in eastern-North American populations of white-footed mice (Peromyscus leucopus), a species known for its role of main reservoir of the Lyme disease. We observed distinct phylogeographic patterns with these two markers, which may be the result of selection pressure acting upon the DRB gene. As predicted by the central marginal hypothesis, we observed a loss of neutral genetic diversity toward the margin of the species distribution. A decrease in diversity was also observed for the DRB gene, likely due to genetic drift and positive selection operated by helminth parasites. Such a loss in genetic diversity at the range margin may slow down the ongoing expansion of P. leucopus, by counterbalancing the effect of global warming on the mouse survival at higher latitude
Helminth communities of wood mouse (Apodemus sylvaticus) on the river Avena (Calabria, southern Italy)
Helminth parasites of woodmouse Apodemus sylvaticus were studied from May 1993 through to June 1994 on the River Avena (Calabria, southern Italy), which, as other Mediterranenan rivers, is dry for most of the year. Trapping sites were located in three different habitats of the river: slopes, shores and the riverbed. A total of 106 animals was captured and screened for the presence of helminths. Five endoparasitic species were detected: Corrigia vitta, Rictularia proni, Heligmosomoides polygyrus, Syphacia stroma and S. frederici. Four helminth species were recorded from the riverbed and shore sections, whereas only H. polygyrus and S. frederici were found on the slopes. Syphacia frederici occurred at every trapping site. The total prevalence was 25.5% and total mean intensity was 27.2 parasites/mouse. No statistical significant difference was found for both the prevalence and mean intensity of infection between either habitats or sexes, suggesting that, from the point of view of the helminth community, the study area should be considered as a single habitat
Testing parasite 'intimacy': the whipworm Trichuris muris in the European house mouse hybrid zone.
Host-parasite interaction studies across hybrid zones often focus on host genetic variation, treating parasites as homogeneous. 'Intimately' associated hosts and parasites might be expected to show similar patterns of genetic structure. In the literature, factors such as no intermediate host and no free-living stage have been proposed as 'intimacy' factors likely constraining parasites to closely follow the evolutionary history of their hosts. To test whether the whipworm, Trichuris muris, is intimately associated with its house mouse host, we studied its population genetics across the European house mouse hybrid zone (HMHZ) which has a strong central barrier to gene flow between mouse taxa. T. muris has a direct life cycle and nonmobile free stage: if these traits constrain the parasite to an intimate association with its host we expect a geographic break in the parasite genetic structure across the HMHZ. We genotyped 205 worms from 56 localities across the HMHZ and additionally T. muris collected from sympatric woodmice (Apodemus spp.) and allopatric murine species, using mt-COX1, ITS1-5.8S-ITS2 rDNA and 10 microsatellites. We show four haplogroups of mt-COX1 and three clear ITS1-5.8S-ITS2 clades in the HMHZ suggesting a complex demographic/phylogeographic history. Microsatellites show strong structure between groups of localities. However, no marker type shows a break across the HMHZ. Whipworms from Apodemus in the HMHZ cluster, and share mitochondrial haplotypes, with those from house mice. We conclude Trichuris should not be regarded as an 'intimate' parasite of the house mouse: while its life history might suggest intimacy, passage through alternate hosts is sufficiently common to erase signal of genetic structure associated with any particular host taxon
- …