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1.
Parasite ; 27: 73, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33332263

RESUMO

The Dactylosomatidae Jakowska and Negrelli, 1955 are one of four families belonging to adeleorinid coccidia and comprise the genera Babesiosoma Jakowska and Nigrelli, 1956 and Dactylosoma Labbé, 1894. These blood protozoa occur in peripheral blood of lower vertebrates, and are commonly reported parasitising amphibians. The present study describes Dactylosoma piperis n. sp. from the pepper frog Leptodactylus labyrinthicus (Spix, 1824) (Anura: Leptodactylidae), collected in 2018 at the municipality of Araguaiana, Mato Grosso State, Brazil, based on morphology of intra-erythrocytic trophozoite, primary and secondary merogonic stages and a molecular analysis (partial 18S rDNA). Dactylosoma piperis n. sp. forms a well-supported clade with other Dactylosomatidae. This is the first molecular characterization of a species of Dactylosoma from a Brazilian anuran.


Assuntos
Anuros , Coccídios , Animais , Anuros/parasitologia , Brasil , Coccídios/classificação , Coccídios/citologia , Coccídios/genética , Filogenia , RNA Ribossômico 18S/genética , Especificidade da Espécie
2.
Parasitol Res ; 119(11): 3659-3673, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32960371

RESUMO

Alongside exotic reptiles, amphibians, such as toads, frogs, salamanders, and newts, are nowadays considered popular pets worldwide. As reported for other exotic pet animals, amphibians are known to harbor numerous gastrointestinal parasites. Nonetheless, very little data are available on captive amphibian parasitic diseases. In this study, we applied direct saline fecal smears (DSFS) to examine in total 161 stool samples from 41 different amphibian species belonging to the orders Anura and Caudata. In addition, carbolfuchsin-smear (CFS) staining (n = 74 samples) was used to detect amphibian Cryptosporidium oocysts. Also, complete dissections of deceased amphibians (n = 107) were performed to specify parasite infections and to address parasite-associated pathogenicity. Overall, examined amphibian fecal samples contained 12 different parasite taxa. The order Rhabditida with the species Rhabdias spp. and Strongyloides spp. were the most prevalent nematode species (19.3%), followed by flagellated protozoans (8.7%), Amphibiocapillaria spp./Neocapillaria spp. (7.5%), Oswaldocruzia spp. (4.3%), Blastocystis spp. (3.1%), Cosmocerca spp. (3.1%), oxyurids (Pharyngonoidae) (3.1%), spirurids (1.2%), un-sporulated coccidian oocysts (0.6%), Tritrichomonas spp. (0.6%), Karotomorpha spp. (0.6%), and Cryptosporidium spp. (0.6%). One CFS-stained fecal sample (1.4%) was positive for Cryptosporidium oocysts. Within dissected amphibians, 31 (48.4%) of the anurans and 11 (26.2%) of the salamanders were infected with gastrointestinal parasites. One cutaneous Pseudocapillaroides xenopi infection was diagnosed in an adult African clawed frog (Xenopus laevis). Etiologically, 17 (15.9%) of them died due to severe parasitic and/or bacterial infections (e.g., Chryseobacterium indologenes, Citrobacter freudii, Sphingobacterium multivorum, Klebsiella pneumoniae). High prevalence and pathological findings of several clinical amphibian parasitoses call for more detailed investigation on gastrointestinal parasite-derived molecular mechanisms associated with detrimental lesions or even death.


Assuntos
Animais Exóticos , Animais de Zoológico/parasitologia , Anuros/parasitologia , Enteropatias Parasitárias/veterinária , Urodelos/parasitologia , Animais , Anuros/microbiologia , Blastocystis/isolamento & purificação , Chryseobacterium/isolamento & purificação , Criptosporidiose/parasitologia , Cryptosporidium/isolamento & purificação , Fezes/parasitologia , Feminino , Enteropatias Parasitárias/parasitologia , Nematoides/isolamento & purificação , Oocistos , Sphingobacterium , Strongyloides/isolamento & purificação , Urodelos/microbiologia
3.
Korean J Parasitol ; 58(4): 467-473, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32871642

RESUMO

Chinese edible frogs, Hoplobatrachus rugulosus, were examined to estimate the potential risks of human gnathostomiasis and sparganosis in Myanmar. A total of 20 frogs were purchased in a local market of Yangon and examined with naked eyes and the artificial digestion method after skin peeling in June 2018 and June 2019. Larvae of gnathostomes and Spirometra (=spargana) were detected in 15 (75.0%) and 15 (75.0%) frogs with average intensities of 10.5 and 6.3 larvae per infected frog, respectively. Gnathostome larvae were 2.75-3.80 (av. 3.30) mm long and 0.29-0.36 (0.33) mm wide. They had a characteristic head bulb with 4 rows of hooklets, a muscular long esophagus, and 2 pairs of cervical sac. The mean number of hooklets were 41, 44, 47, and 50 on the 1st, 2nd, 3rd, and 4th row, respectively. Collected spargana were actively moving, particularly with the scolex part, and have ivory-white color and variable in size. Conclusively, it has been first confirmed that Chinese edible frogs, H. rugulosus, are highly infected with larval gnathostomes and spargana in this study. Consuming these frogs is considered a potential risk of human gnathostomiasis and sparganosis in Myanmar.


Assuntos
Anuros/parasitologia , Gnathostoma/isolamento & purificação , Larva , Animais , Parasitologia de Alimentos , Gnathostoma/anatomia & histologia , Gnatostomíase/parasitologia , Larva/anatomia & histologia , Mianmar , Risco
4.
Parasitol Res ; 119(10): 3469-3479, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32827104

RESUMO

Amphibians are among the most threatened vertebrate groups in the world, and the main causes include climate change, habitat destruction, and emerging diseases. Herein, we investigated the occurrence and characterized molecularly Apicomplexa in anurans from southeastern Brazil. Forty individuals from seven anuran species were sampled in São Paulo state. In the molecular analyses, one Leptodactylus latrans and one Rhinella diptycha were positive in PCR assays for species of Hepatozoon. Two L. latrans were also positive for coccidian infections (Lankesterella sp. and an unidentified coccidian species). Phylogenetic analysis based on 18S rDNA clustered the sequences detected in anurans from the present study with Hepatozoon spp. detected in reptiles and other anurans from Brazil, albeit they were separate from Hepatozoon haplotypes detected in frogs from Africa and North America. Our study showed, for the first time, the molecular detection of Lankesterella sp. and another coccidian in L. latrans. Additionally, co-infection by different species of Hepatozoon haplotypes and an unidentified coccidian in anurans from Brazil was documented.


Assuntos
Anuros/parasitologia , Apicomplexa/genética , Apicomplexa/isolamento & purificação , Infecções Protozoárias em Animais/parasitologia , Animais , Anuros/classificação , Apicomplexa/classificação , Brasil/epidemiologia , Coccídios/classificação , Coccídios/genética , Coccídios/isolamento & purificação , Coccidiose/epidemiologia , Coccidiose/parasitologia , Coccidiose/veterinária , DNA de Protozoário/genética , DNA Ribossômico/genética , Filogenia , Infecções Protozoárias em Animais/epidemiologia
5.
Syst Parasitol ; 97(4): 369-378, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32562125

RESUMO

Rhabdias delangei n. sp. (Nematoda: Rhabdiasidae) is described from the lungs of the clicking stream frog Strongylopus grayii (Smith) in the Western Cape Province of South Africa. The new species is characterised by the nerve-ring being located just posterior to the mid-length of the oesophagus, a pre-equatorial vulva, as well as a thin-walled and apparently underdeveloped rectum. Pairwise analyses based on ITS-28S and partial cox1 gene fragments showed significant differences between R. delangei n. sp. and its congeners from the Afrotropical Realm. Rhabdias delangei n. sp. is the 12th species of Rhabdias Stiles & Hassall, 1905 recorded in Afrotropical amphibians and the second species of the genus found in pyxicephalid hosts. Our phylogenetic analysis based on the ITS-28S region showed that the new species is closely related to the European species R. rubrovenosa (Schneider, 1866). Furthermore, both species are similar with respect to the underdeveloped rectum and pre-equatorial position of vulva.


Assuntos
Anuros/parasitologia , Nematoides/classificação , Animais , DNA de Helmintos/genética , Pulmão/parasitologia , Nematoides/anatomia & histologia , Nematoides/genética , Filogenia , África do Sul , Especificidade da Espécie
6.
J Parasitol ; 106(3): 334-340, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32369595

RESUMO

We investigated the mean abundance of helminths and analyzed helminth composition and structure at the infracommunity and component community levels for 3 anuran species (Pleurodema diplolister, Rhinella jimi, and Rhinella granulosa) from the Caatingas, a semiarid Brazilian region characterized by accentuated seasonality and unpredictability of rains. Data were collected during the reproductive period and during drought, when P. diplolister estivated buried underground but R. jimi and R. granulosa remained foraging actively. We expected higher parasitological parameters during the reproductive period when compared to drought for these 3 anurans. We also expected higher parasite infection in the Rhinella species and higher similarity between their helminth parasite communities when compared to the estivating species, P. diplolister. Contrary to our hypothesis, the season was not related to parasite community structure. As predicted, the Rhinella toads shared more similar species composition of parasite communities. These similarities in the composition of the parasite community between Rhinella species could be due to similar temporal/spatial patterns of activity and phylogenetic proximity. Pleurodema diplolister hosted a more restricted helminth fauna, a result that might be associated with estivation restricting the temporal window available to acquire parasites. This study also presents new helminth fauna records for R. jimi and P. diplolister, and the first helminth fauna record of R. granulosa from the Caatingas in semiarid Brazil.


Assuntos
Anuros/parasitologia , Helmintíase Animal/parasitologia , Animais , Anuros/fisiologia , Brasil/epidemiologia , Secas , Helmintíase Animal/epidemiologia , Masculino , Chuva , Reprodução , Estações do Ano
7.
An Acad Bras Cienc ; 92(1): e20180384, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32321016

RESUMO

This is the first record of the trematode Choledocystus incurvatum and Choledocystus elegans in Argentinean amphibians collected in two localities of the Chacoan region. The first trematode species was found infecting the small intestine of Pseudis paradoxa Linnaeus, captured near the city of Corrientes, Corrientes Province; the second species was found infecting the gall-bladder of Lepidobatrachus laevis Budgget, captured in Ingeniero Juárez, Formosa Province. Morphology of these species was studied in detail using light microscopy and scanning electron microscopy (SEM), and compared with previous studies of Brazilian and Venezuelan specimens. Morphological descriptions of these parasites are provided to supplement existing data. Choledocystus incurvatum was characterized using molecular methods by sequencing and analyzing rDNA. Regarding metric characters of C. incurvatum, the Argentinean specimens show some differences in body and egg size (some larger than Venezuelan specimens). For C. elegans the specimen shows smaller body size than Brazilian specimens. SEM observations of C. incurvatum showed tegument covered with triangular spines and confirmed presence of a sucker-like structure around the genital atrium. The morphological and genetic data on C. incurvatum contribute to a more thorough diagnosis of the genus. Moreover, this report represents the first occurrence of this genus in the Argentine Chacoan region.


Assuntos
Anuros/parasitologia , Trematódeos/classificação , Animais , Argentina , Microscopia Eletrônica de Varredura , Filogenia , Trematódeos/anatomia & histologia , Trematódeos/ultraestrutura
8.
Ann Parasitol ; 66(1): 39­47, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32198994

RESUMO

The present study describes the helminth community collected from juveniles of Dermatonotus muelleri (Anura: Microhylidae) from the Chaco Seco Ecoregion. Helminths were found in 80.0% of specimens examined (n = 16). The helminth community of this microhylid presented very low species richness; a total of 1,339 specimens belonging four helminth species were found; three adult nematodes, Aplectana hylambatis, Cosmocerca podicipinus and Parapharyngodon sp., and an adult cestode, Ophiotaenia sp. Parasites were found in the large and small intestines. Maximum helminth richness was 2 species per infected frog. The nematode A. hylambatis presented the highest prevalence and was the most abundant (d = 0.97) indicating that it is the dominant species in the community (I = 63.0). Host snout-vent length did not influence the intensity of infection or the richness of helminth species at the community component level. Two species showed significant co-variation (A. hylambatis and Parapharyngodon sp.). The high prevalence of infection and number of parasites found for A. hylambatis could be related to the characteristics of their life cycles; the possession of the infective stage (L3) protected inside the egg membrane would have benefits against extreme drought in the area in which the study was conducted. The studies of helminths in the Chaco Seco Ecoregion, an area seriously threatened in terms of its biodiversity, are incipient. This is the second study that has been carried out to determine the structure of the parasite community in amphibians of this ecoregion.


Assuntos
Anuros , Biodiversidade , Helmintíase Animal , Helmintos , Nematoides , Animais , Anuros/parasitologia , Clima Desértico , Helmintíase Animal/epidemiologia , Helmintíase Animal/parasitologia , Helmintos/classificação , Nematoides/classificação , Prevalência , Estados Unidos
9.
Zoolog Sci ; 37(1): 70-78, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32068376

RESUMO

The taxonomic account of the tadpole-parasitic nematode Gyrinicola japonica Yamaguti, 1938, which is the type species of the genus, was reassessed based on syntypes and newly-collected specimens from the type locality. Our redescription of G. japonica addresses the erroneous original description of a spicule in this nematode, and emends the diagnosis of the species. Additionally, molecular phylogenetic trees based on nuclear 18S and 28S rDNA sequences revealed that G. japonica forms a distinctive lineage within the suborder Oxyurina, and this tadpole-specialist is phylogenetically close to the lizard-parasitic nematodes that belong to the family Pharyngodonidae. The results of morphological examination with the aid of molecular phylogenetic trees highlight the systematic uniqueness of this tadpole-parasitic group within Oxyurina, and Gyrinicolidae is accordingly resurrected as a distinctive oxyurinan family, with redefinition of the family and the genus Gyrinicola.


Assuntos
Oxyuroidea/anatomia & histologia , Oxyuroidea/classificação , Animais , Anuros/parasitologia , DNA Ribossômico , Feminino , Japão , Larva/parasitologia , Masculino , Oxyuroidea/genética , Filogenia , RNA Ribossômico 18S
10.
Parasitol Res ; 119(4): 1415-1422, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32006228

RESUMO

Myiasis is defined as the infestation of living or necrotic tissues of vertebrates by dipteran larvae. In amphibians, it can be caused by fly larvae belonging to families Calliphoridae, Chloropidae, Muscidae, and Sarcophagidae. In this study, we report new records and infestation intensity of myiasis in anurans from two localities of the Atlantic Forest in southern Brazil, and also present a list with myiasis caused by flesh fly Sarcophagidae species in anurans of the Neotropical region. For this, we surveyed anuran communities during two breeding seasons, examined for myiasis signs, and when positive collected the specimens. We found infested individuals of 13 anurans of seven species. Different Sarcophagidae larva morphotypes were collected, and two of them emerged as adult flies of Lepidodexia (Notochaeta) fumipennis and Peckia (Sarcodexia) lambens, which were both found in the tree frog Bokermannohyla circumdata. We compiled 21 cases of myiasis in anurans in the Neotropical region from the literature reviewed. This data indicated that hosts of different lineages and modes of life can be affected and that death is often fast. The diversity of myiasis-causing flies in anurans in nature is probably a lot greater than expected, especially if we consider that the encounters are occasional, but at relatively high intensities, can cause rapid deaths.


Assuntos
Anuros/parasitologia , Miíase/mortalidade , Miíase/veterinária , Sarcofagídeos/patogenicidade , Animais , Brasil , Florestas , Larva/crescimento & desenvolvimento
12.
Int J Parasitol ; 50(3): 177-194, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32087248

RESUMO

Anuran filarial nematodes are restricted to two comparatively small subfamilies (Icosiellinae and Waltonellinae) of the filariae that currently comprise six genera and 41 recognised species. However, the life histories of only five anuran filarial nematodes, proposed as an ancestral group based on molecular phylogenetic studies, have been elucidated. Furthermore, data on the natural vectors (in situ) and parasite transmission is limited. In the current study we elucidate the life history of Neofoleyellides boerewors n. gen. n. sp. parasitising the guttural toad, Sclerophrys gutturalis and the mosquito vectors Uranotaenia (Pseudoficalbia) mashonaensis and Uranotaenia (Pseudoficalbia) montana. Additionally, we report on the unique host-seeking behaviour of the mosquito vectors which locate their toad hosts using their calls. The complex host-vector relationship and specialised host-seeking behaviour by these mosquitoes indicate biases towards host species and male toad infections.


Assuntos
Anuros/parasitologia , Filariose , Filarioidea/classificação , Animais , Culicidae/parasitologia , Complexo IV da Cadeia de Transporte de Elétrons/genética , Filariose/parasitologia , Filariose/transmissão , Filariose/veterinária , Filarioidea/anatomia & histologia , Filarioidea/genética , Filarioidea/isolamento & purificação , Interações Hospedeiro-Parasita , Estágios do Ciclo de Vida , Microfilárias/isolamento & purificação , Mosquitos Vetores/parasitologia , Nematoides , Filogenia , RNA Ribossômico 18S/genética
14.
Proc Biol Sci ; 287(1919): 20192597, 2020 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-31964296

RESUMO

A key challenge surrounding ongoing climate shifts is to identify how they alter species interactions, including those between hosts and parasites. Because transmission often occurs during critical time windows, shifts in the phenology of either taxa can alter the likelihood of interaction or the resulting pathology. We quantified how phenological synchrony between vulnerable stages of an amphibian host (Pseudacris regilla) and infection by a pathogenic trematode (Ribeiroia ondatrae) determined infection prevalence, parasite load and host pathology. By tracking hosts and parasite infection throughout development between low- and high-elevation regions (San Francisco Bay Area and the Southern Cascades (Mt Lassen)), we found that when phenological synchrony was high (Bay Area), each established parasite incurred a 33% higher probability of causing severe limb malformations relative to areas with less synchrony (Mt Lassen). As a result, hosts in the Bay Area had up to a 50% higher risk of pathology even while controlling for the mean infection load. Our results indicate that host-parasite interactions and the resulting pathology were the joint product of infection load and phenological synchrony, highlighting the sensitivity of disease outcomes to forecasted shifts in climate.


Assuntos
Anuros/parasitologia , Interações Hospedeiro-Parasita , Trematódeos/fisiologia , Animais , Clima , Fenótipo
15.
Parasitol Res ; 118(12): 3359-3370, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31729575

RESUMO

A new species of naidid oligochaete, Dero rwandae, detected in the bladder and the Wolffian ducts of reed frogs Hyperolius kivuensis from Rwanda, is described. Until now, D. bauchiensis was the only endoparasitic Dero known to infect African frogs infesting the eyes and Harderian glands. To the best of our knowledge, the finding of D. rwandae is the first record of an African Dero species infecting the urinary tract of anurans. In general morphology, the two African Dero parasites resemble each other, but differences in the features of ventral setae morphology exist. Parts of the mitochondrial 16S rRNA locus and the nuclear 18S and 28S rRNA loci were sequenced to assess the phylogenetic relationships to other Dero spp. Among those few species, that are barcoded so far, the closest relative of the new taxon is D. superterrenus, a free-living South American species. The species groups formerly termed subgenera Allodero, Aulophorus and Dero within the genus Dero do not represent distinct evolutionary lineages and the genus is paraphyletic including Branchiodrilus.


Assuntos
Anuros/parasitologia , Oligoquetos/classificação , Doenças Parasitárias em Animais/parasitologia , Bexiga Urinária/parasitologia , Animais , Sequência de Bases , Oligoquetos/genética , Filogenia , RNA Ribossômico/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 28S/genética , Ruanda
16.
Parasite ; 26: 67, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31746733

RESUMO

The polystomes (Monogenea, Polystomatidae) radiated across semi-aquatic tetrapods including all three amphibian orders, freshwater turtles and the hippopotamus. Prior to this study, phylogenetic analyses revealed that the most diverse and widespread genus, Polystoma, was not monophyletic; a lineage comprising four undescribed species from the bladder of Zhangixalus spp. (Rhacophoridae) in Asia occupied a deep phylogenetic position. Regarding vicariance biogeography and molecular dating, the origin of this lineage is correlated with the breakup of Gondwanaland in the Mesozoic period. Based on a Bayesian analysis of four concatenated genes (18S, 28S, COI and 12S) and morphological evidence, one new genus, Indopolystoma n. gen., and three new species, sampled in Japan and China, are described here: Indopolystoma viridi n. sp. from Z. viridis of Japan, Indopolystoma elongatum n. sp. from Z. arboreus of Japan, and Indopolystoma parvum n. sp. from Z. omeimontis of China. Indopolystoma is unique amongst polystome genera infecting anurans by possessing a small haptor relative to the body size, posteriormost marginal hooklet C1 much bigger than hooklets C2-C8 with conspicuous broad blade and guard and a pair of hamuli lacking a deep notch. Eight species of Asian Polystoma, all from rhacophorids, are transferred as Indopolystoma carvirostris (Fan, Li & He, 2008) n. comb., I. hakgalense (Crusz & Ching, 1975) n. comb., I. indicum (Diengdoh & Tandon, 1991) n. comb., I. leucomystax (Zhang & Long, 1987) n. comb., I. mutus (Meng, Song & Ding, 2010) n. comb., I. pingbianensis (Fan, Wang & Li, 2004) n. comb., I. rhacophori (Yamaguti, 1936) n. comb., and I. zuoi (Shen, Wang & Fan, 2013) n. comb.


Assuntos
Anuros/parasitologia , Trematódeos/classificação , Animais , Teorema de Bayes , China , DNA de Helmintos/genética , Água Doce , Japão , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Trematódeos/anatomia & histologia , Trematódeos/isolamento & purificação , Bexiga Urinária/parasitologia
17.
J Helminthol ; 94: e54, 2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31630693

RESUMO

The genus Rhabdias Stiles & Hassal, 1905 includes about 83 species of nematodes parasitic in amphibians and reptiles worldwide. Herein, we describe Rhabdias glaurungi sp. nov. from the hylid frog Scinax gr. ruber (Laurenti, 1768) in the Gunma Ecological Park, Santa Bárbara municipality, state of Pará, Brazil. This species has six small lips, an inflated cuticle along the entire body and a cup-shaped buccal capsule with smooth internal surface of its anterior part and irregularly folded internal surface of its posterior part in apical view. From the 17 valid species recognized in the Neotropical realm, the new species can be distinguished by the number of lips, the morphology and size of its buccal capsule, as well as the extent and shape of its cuticular inflation; in addition, there are molecular differences. Sequences of the mitochondrial Cytochrome c Oxidase subunit I gene strongly support the status of this form as a separate species. Molecular phylogenetic analysis shows R. glaurungi sp. nov. nested within the R. pseudosphaerocephala Kuzmin, Tkach & Brooks, 2007 species complex. Rhabdias glaurungi sp. nov. is the second species of the genus described from hosts of the family Hylidae in the Neotropical realm. We conclude that the diversity of Rhabdias within the Neotropics is likely largely underestimated.


Assuntos
Anuros/parasitologia , Filogenia , Infecções por Rhabditida/parasitologia , Rhabditoidea/anatomia & histologia , Rhabditoidea/classificação , Animais , Brasil , Complexo IV da Cadeia de Transporte de Elétrons/genética , Genes Mitocondriais , Especificidade da Espécie
18.
J Exp Zool B Mol Dev Evol ; 332(7): 219-237, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31613418

RESUMO

William Bateson was an obsessive observer of animal oddities, and at some point in his herculean survey of museum collections leading up to his monumental 1894 monograph (Materials for the study of variation), he noticed a peculiar trend among the preserved specimens (mainly insects) that possessed extra legs: multiple legs that branched from the same socket tended to be mirror images of their adjacent neighbors. He did not know why. These symmetry relationships have come to be known as Bateson's rule, and they have defied a satisfactory explanation for 125 years. In the past few decades, tantalizing clues have emerged from various lines of investigation, and those lines have converged on a possible solution. An attempt is made here to fit all of those clues together to form a coherent picture of the etiology. Two case studies have proven to be pivotal: a fly mutant whose extra legs are caused by patches of dying cells and a frog syndrome whose extra legs are caused by a parasitic flatworm. The conclusion reached is that the extra legs of insects and vertebrates obey Bateson's rule for the same reason, but that reason has nothing to do with the specific molecules in their signaling pathways. Rather, it is an emergent property of the circuitry of the pathways and their polarized alignments along the limb axes. A parade of theoretical models have tried and failed to crack this mystery in the past, and they are reviewed here as part of the narrative.


Assuntos
Extremidades/crescimento & desenvolvimento , Modelos Teóricos , Animais , Anuros/anormalidades , Anuros/parasitologia , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Deformidades Congênitas dos Membros , Mutação
19.
Eur J Protistol ; 71: 125639, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31550629

RESUMO

Opalinids are a large group of anaerobic protists, mainly inhabiting the cloacae of amphibians (frogs and toads). The classification of this group has not been fully resolved, because of a lack of molecular information. Here, we give a redescription of Opalina triangulata Metcalf, 1923, collected from the rectum of the frog Fejervarya limnocharis, based on detailed morphological and molecular data. Our phylogenetic analyses confirmed the monophyly of Opalinata. Within it, Opalinea were monophyletic with O. triangulata and O. undulata as well as two Protoopalina species grouping together. Karotomorpha and Proteromonas did not group together confirming the paraphyly of Proteromonadea. Meanwhile, the ITS2 secondary structural similarities as well as G-C content revealed greater similitudes between Opalina species and P. lacertae than with Blastocystis hominis, which is in accordance with their position as sister clades in the SSU rDNA-based phylogenies.


Assuntos
Anuros/parasitologia , Filogenia , Estramenópilas/classificação , Animais , DNA Ribossômico/genética , Estramenópilas/citologia , Estramenópilas/genética
20.
An Acad Bras Cienc ; 91(3): e20171028, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31482992

RESUMO

Aplectana hylambatis is a nematode with a wide geographic distribution and low host specificity. In spite of numerous reports, until this moment, the morphological variations between different hosts and localities have not been studied. We studied 401 specimens collected from five host species from seven localities in Argentina, and examined the following morphological characters: mamelon-like cuticular protuberances anterior to the vulva, structure of the gubernaculum and the spicules, number and arrangement of caudal papillae, and the measurements of twelve characters in females and eleven characters in males. The results showed that mamelon-like protuberances and caudal papillae varied in number and arrangement between different hosts and localities. The metrical study revealed that five characters in males and six in females contributed to variability; nine characters showed significant differences between host species and localities. Specimens of A. hylambatis collected from R. arenarum formed a group clearly differentiated from the rest of the specimens. The results from this study highlight the importance of examining as many specimens as possible from different host samples and from several localities to cover the intraspecific variations.


Assuntos
Anuros/parasitologia , Nematoides/anatomia & histologia , Nematoides/classificação , Animais , Anuros/classificação , Argentina , Feminino , Geografia , Interações Hospedeiro-Parasita , Masculino
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