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1.
BMC Evol Biol ; 19(1): 82, 2019 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-30898091

RESUMO

BACKGROUND: Species diversity is determined by both local environmental conditions that control differentiation and extinction and the outcome of large-scale processes that affect migration. The latter primarily comprises climatic change and dynamic landscape alteration. In the past few million years, both Southeast Asia and Eastern Africa experienced drastic climatic and geological oscillations: in Southeast Asia, especially in China, the Tibetan Plateau significantly rose up, and the flow of the Yangtze River was reversed. In East Africa, lakes and rivers experienced frequent range expansions and regressions due to the African mega-droughts. To test how such climatic and geological histories of both regions relate to their respective regional species and genetic diversity, a large scale comparative phylogeographic study is essential. Bellamya, a species rich freshwater snail genus that is widely distributed across China and East Africa, represents a suitable model system to address this question. We sequenced mitochondrial and nuclear DNA for members of the genus from China and used published sequences from Africa and some other locations in Asia to investigate their phylogeny and distribution of genetic diversity. RESULTS: Our phylogenetic analysis revealed two monophyletic groups, one in China and one in East Africa. Within the Chinese group, Bellamya species show little genetic differentiation. In contrast, we observe fairly deep divergence among the East African lakes with almost every lake possessing its unique clade. Our results show that strong divergence does not necessarily depend on intrinsic characteristics of a species, but rather is related to the landscape dynamics of a region. CONCLUSION: Our phylogenetic results suggest that the Bellamya in China and East Africa are independent phylogenetic clades with different evolutionary trajectories. The different climate and geological histories likely contributed to the diverging evolutionary patterns. Repeated range expansions and regressions of lakes likely contributed to the great divergence of Bellamya in East Africa, while reversal of the river courses and intermingling of different lineages had an opposite effect on Bellamya diversification in China.


Assuntos
Biodiversidade , Filogeografia , Caramujos/classificação , África Oriental , Animais , China , DNA Mitocondrial/genética , Haplótipos/genética , Lagos , Filogenia , Polimorfismo Genético , Rios , Caramujos/anatomia & histologia , Caramujos/genética , Caramujos/ultraestrutura , Especificidade da Espécie
2.
Mol Phylogenet Evol ; 132: 194-206, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30550961

RESUMO

To accurately delimit species the use of multiple character types is essential as all speciation processes are not equally reflected in different data (e.g. morphological, molecular or ecological characters). With the introduction of geometric morphometrics methods and advances in 3D technology, a comprehensive combination of molecular and morphological data has been enabled in groups where exhaustively quantifying and measuring morphological shape change was not possible before such as gastropod shells. In this study, we combined multilocus coalescent species delimitation methods with 3D geometric morphometrics of shell shape to delimit species within the land snail genus Pyrenaearia. A new taxonomic scheme was constructed for the genus identifying ten species. Two nominal species were synonymized and a hitherto unrecognized cryptic species was identified. Our findings support the importance of combining multiple lines of evidence as molecular and morphological data on their own do not yield the same information. Further, the integration of morphological and molecular data shows the importance of allometry in shell shape and suggests a combined effect of population history and selection in different environments on shells morphological variation. Our new taxonomy and phylogenetic reconstruction suggest that, besides the glacial cycles of the Pleistocene, passive dispersal and rock substrate complexity could also have been involved in the speciation of the genus.


Assuntos
Caramujos/classificação , Exoesqueleto/anatomia & histologia , Animais , Complexo IV da Cadeia de Transporte de Elétrons/classificação , Complexo IV da Cadeia de Transporte de Elétrons/genética , Filogenia , Análise de Componente Principal , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , RNA Ribossômico 28S/classificação , RNA Ribossômico 28S/genética , Caramujos/anatomia & histologia , Caramujos/genética
3.
Mol Phylogenet Evol ; 132: 307-320, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30550963

RESUMO

Naive use of molecular data may lead to ambiguous conclusions, especially within the context of "cryptic" species. Here, we integrated molecular and morphometric data to evaluate phylogenetic relationships in the widespread terrestrial micro-snail genus, Euconulus. We analyzed mitochondrial (16S + COII) and nuclear (ITS1 + ITS2) sequence across 94 populations from Europe, Asia and North America within the nominate species E. alderi, E. fulvus and E. polygyratus, and used the southeastern USA E. chersinus, E. dentatus, and E. trochulus as comparative outgroups. Phylogeny was reconstructed using four different reconstruction methods to identify robust, well-supported topological features. We then performed discriminant analysis on shell measurements between these genetically-identified species-level clades. These analyses provided evidence for a biologically valid North American "cryptic" species within E. alderi. However, while highly supported polyphyletic structure was also observed within E. fulvus, disagreement in placement of individuals between mtDNA and nDNA clades, lack of morphological differences, and presence of potential hybrids imply that these lineages do not rise to the threshold as biologically valid cryptic species, and rather appear to simply represent a complex of geographically structured populations within a single species. These results caution that entering into a cryptic species hypothesis should not be undertaken lightly, and should be optimally supported along multiple lines of evidence. Generally, post-hoc analyses of macro-scale features should be conducted to attempt identification of previously ignored diagnostic traits. If such traits cannot be found, i.e. in the case of potentially "fully cryptic" species, additional criteria should be met to propound a cryptic species hypothesis, including the agreement in tree topology among both mtDNA and nDNA, and little (or no) evidence of hybridization based on a critical analysis of sequence chromatograms. Even when the above conditions are satisfied, it only implies that the cryptic species hypothesis is plausible, but should optimally be subjected to further careful examination.


Assuntos
Caramujos/classificação , Animais , Sequência de Bases , Núcleo Celular/genética , Complexo IV da Cadeia de Transporte de Elétrons/classificação , Complexo IV da Cadeia de Transporte de Elétrons/genética , Funções Verossimilhança , Filogenia , Análise de Componente Principal , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Caramujos/genética
4.
Rev Soc Bras Med Trop ; 51(5): 689-694, 2018 Sep-Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30304280

RESUMO

INTRODUCTION: This paper presents the results of an extensive survey of freshwater mollusks in the Simplício Queda Única Hydroelectric Development area, Southeast Brazil. METHODS: Mollusks were collected between 2008 and 2013. All specimens were examined for the presence of larval trematodes. RESULTS: In total, 12,507 specimens classified into 16 genera were obtained. Known snail vectors of schistosomiasis and fascioliasis and exotic species were identified, and new records are reported. CONCLUSIONS: No specimens parasitized by larval trematodes of medical interest were detected. However, the results reinforce the importance of surveillance in study areas vulnerable to the occurrence of schistosomiasis transmission.


Assuntos
Vetores de Doenças/classificação , Água Doce/parasitologia , Centrais Elétricas , Esquistossomose mansoni/transmissão , Caramujos/classificação , Animais , Brasil , Densidade Demográfica , Caramujos/parasitologia
5.
Rev Inst Med Trop Sao Paulo ; 60: e41, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30133601

RESUMO

The wide eco-bio-social intervention generated by the SaoFrancisco River Integration Project (PISF) may contribute to the dispersion or introduction of schistosomiasis intermediate hosts in areas without prior recording. The objective was to characterize the limnic malacofauna and its distribution along watersheds involved in the PISF. A cross-sectional study based on the collection of mollusks from 33 water bodies, from Aurora, Brejo Santo, Jaguaretama, Jaguaribara, Jati e Mauriti municipalities in the Ceara (CE) State was developed. The conchological characteristics were used to identify snails at the genus level. The snails of the genus Biomphalaria were analyzed for the presence of Schistosoma mansoni cercariae and the molecular identification (only mollusks from Brejo Santo-CE) for differentiation between species. The following species were found: Biomphalaria sp.; Drepanotrema sp.; Melanoides sp.; Physa sp.; and Pomacea sp. Pomacea sp. (75.8%) and Biomphalaria sp. (72.7%) were the most prevalent species. All municipalities showed Biomphalaria sp. Biomphalaria straminea (Porcos Stream) and Biomphalaria kuhniana was identified in the Boi 1 and Cipo reservoirs (Brejo Santo). The evaluated municipalities under the influence of the PISF present areas with potential for schistosomiasis transmission. It is necessary to intensify control actions and health surveillance in these areas.


Assuntos
Caramujos/classificação , Animais , Biomphalaria/classificação , Brasil , Densidade Demográfica , Rios
6.
Infect Dis Poverty ; 7(1): 29, 2018 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-29615124

RESUMO

BACKGROUND: Snail intermediate hosts play active roles in the transmission of snail-borne trematode infections in Africa. A good knowledge of snail-borne diseases epidemiology particularly snail intermediate host populations would provide the necessary impetus to complementing existing control strategy. MAIN BODY: This review highlights the importance of molecular approaches in differentiating snail hosts population structure and the need to provide adequate information on snail host populations by updating snail hosts genome database for Africa, in order to equip different stakeholders with adequate information on the ecology of snail intermediate hosts and their roles in the transmission of different diseases. Also, we identify the gaps and areas where there is need for urgent intervention to facilitate effective integrated control of schistosomiasis and other snail-borne trematode infections. CONCLUSIONS: Prioritizing snail studies, especially snail differentiation using molecular tools will boost disease surveillance and also enhance efficient schistosomaisis control programme in Africa.


Assuntos
Vetores de Doenças , Genoma , Caramujos/classificação , Caramujos/genética , Infecções por Trematódeos , África , Animais , Vetores de Doenças/classificação , Humanos , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Esquistossomose/transmissão , Caramujos/parasitologia , Trematódeos/fisiologia , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/prevenção & controle , Infecções por Trematódeos/transmissão
7.
BMC Genomics ; 19(1): 179, 2018 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-29506476

RESUMO

BACKGROUND: Gastropoda, with approximately 80,000 living species, is the largest class of Mollusca. Among gastropods, apple snails (family Ampullariidae) are globally distributed in tropical and subtropical freshwater ecosystems and many species are ecologically and economically important. Ampullariids exhibit various morphological and physiological adaptations to their respective habitats, which make them ideal candidates for studying adaptation, population divergence, speciation, and larger-scale patterns of diversity, including the biogeography of native and invasive populations. The limited availability of genomic data, however, hinders in-depth ecological and evolutionary studies of these non-model organisms. RESULTS: Using Illumina Hiseq platforms, we sequenced 1220 million reads for seven species of apple snails. Together with the previously published RNA-Seq data of two apple snails, we conducted de novo transcriptome assembly of eight species that belong to five genera of Ampullariidae, two of which represent Old World lineages and the other three New World lineages. There were 20,730 to 35,828 unigenes with predicted open reading frames for the eight species, with N50 (shortest sequence length at 50% of the unigenes) ranging from 1320 to 1803 bp. 69.7% to 80.2% of these unigenes were functionally annotated by searching against NCBI's non-redundant, Gene Ontology database and the Kyoto Encyclopaedia of Genes and Genomes. With these data we developed AmpuBase, a relational database that features online BLAST functionality for DNA/protein sequences, keyword searching for unigenes/functional terms, and download functions for sequences and whole transcriptomes. CONCLUSIONS: In summary, we have generated comprehensive transcriptome data for multiple ampullariid genera and species, and created a publicly accessible database with a user-friendly interface to facilitate future basic and applied studies on ampullariids, and comparative molecular studies with other invertebrates.


Assuntos
Bases de Dados Genéticas , Caramujos/classificação , Caramujos/genética , Transcriptoma , Animais , Perfilação da Expressão Gênica , Ontologia Genética , Genômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Anotação de Sequência Molecular
8.
BMC Res Notes ; 11(1): 204, 2018 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-29587859

RESUMO

OBJECTIVE: Promenetus exacuous and Valvata tricarinata are freshwater snail species with widespread distributions throughout North America. Information regarding their genetic diversity and population connectivity are currently lacking. We utilized next generation sequencing to develop the first microsatellites for each species to investigate genetic diversity within and differentiation among populations. RESULTS: Sixteen and seventeen microsatellite loci were developed for P. exacuous and V. tricarinata, respectively, and tested in a total of 43 P. exacuous and 48 V. tricarinata from two lakes approximately 183 km apart in New York State, USA. Fifteen P. exacuous loci were polymorphic in at least one lake and possessed 1-23 alleles and observed heterozygosities of 0.00-0.96 within individual lakes. Seventeen polymorphic V. tricarinata loci possessed 2-19 alleles and observed heterozygosities of 0.04-0.96 within lakes. Bayesian clustering using 12 loci for each species identified two distinct genetic populations, reflecting the two lakes. High assignment scores for individual snails to the lakes they were collected from supported strong population structure with minimal admixture at the scale of this study. These loci will be useful for investigating the genetic diversity and population structure of these species and indicate genetic differentiation may be common among their populations.


Assuntos
Variação Genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Repetições de Microssatélites/genética , Caramujos/genética , Alelos , Animais , Água Doce , Genética Populacional , Heterozigoto , Lagos , New York , Caramujos/classificação , Especificidade da Espécie
9.
Vet Parasitol ; 251: 101-105, 2018 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-29426464

RESUMO

A molecular tool described here allows in one step for specific discrimination among three cryptic freshwater snail species (genus Galba) involved in fasciolosis transmission, a worldwide infectious disease of humans and livestock. The multiplex PCR approach taken targets for each species a distinctive, known microsatellite locus which is amplified using specific primers designed to generate an amplicon of a distinctive size that can be readily separated from the amplicons of the other two species on an agarose gel. In this way, the three Galba species (G. cubensis, G. schirazensis, and G. truncatula) can be differentiated from one another, including even if DNA from all three were present in the same reaction. The accuracy of this new molecular tool was tested and validated by comparing multiplex PCR results with species identification based on sequences at mitochondrial and nuclear markers. This new method is accurate, inexpensive, simple, rapid, and can be adapted to handle large sample sizes. It will be helpful for monitoring invasion of Galba species and for developing strategies to limit the snail species involved in the emergence or re-emergence of fasciolosis.


Assuntos
Fasciola hepatica/fisiologia , Fasciolíase/transmissão , Reação em Cadeia da Polimerase Multiplex/métodos , Caramujos/genética , Animais , Primers do DNA/genética , DNA Mitocondrial , Fasciolíase/parasitologia , Humanos , Repetições de Microssatélites/genética , Análise de Sequência de DNA , Caramujos/classificação
10.
Genetica ; 146(3): 265-275, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29480464

RESUMO

A small number of genes may interact to determine sex, but few such examples have been demonstrated in animals, especially through comprehensive mating experiments. The highly invasive apple snail Pomacea canaliculata is gonochoristic and shows a large variation in brood sex ratio, and the involvement of multiple genes has been suggested for this phenomenon. We conducted mating experiments to determine whether their sex determination involves a few or many genes (i.e., oligogenic or polygenic sex determination, respectively). Full-sib females or males that were born from the same parents were mated to an adult of the opposite sex, and the brood sex ratios of the parents and their offspring were investigated. Analysis of a total of 4288 offspring showed that the sex ratios of offspring from the full-sib females were variable but clustered into only a few values. Similar patterns were observed for the full-sib males, although the effect was less clear because fewer offspring were used (n = 747). Notably, the offspring sex ratios of all full-sib females in some families were nearly 0.5 (proportion of males) with little variation. These results indicate that the number of genotypes of the full-sibs, and hence genes involved in sex determination, is small in this snail. Such oligogenic systems may be a major sex-determining system among animals, especially those with variable sex ratios.


Assuntos
Processos de Determinação Sexual/genética , Caramujos/classificação , Caramujos/genética , Animais , Cruzamentos Genéticos , Feminino , Genótipo , Masculino , Malus , Razão de Masculinidade
11.
Sci Rep ; 8(1): 1185, 2018 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-29352210

RESUMO

Species of Pomacea, commonly known as apple snails, are native to South America, and have become widely distributed agricultural and environmental pests in southern China since their introduction in the 1980s. However, only since 2010 have researchers recognized that at least two species, P. canaliculata and P. maculata, are present in China. Although impacts of apple snails have been extensively documented, confusion still persists regarding current distributions and origin of the species in China. To resolve this confusion, we used phylogenetic and phylogeographic methods to analyze 1464 mitochondrial COI sequences, including 349 new sequences from samples collected in southern China and 1115 publicly available sequences from snails collected in the native and introduced ranges. Pomacea canaliculata was found at all sampled localities, while P. maculata was found at only five sampled localities in the Sichuan basin and Zhejiang province. Our data indicate that Chinese populations of P. canaliculata share an Argentinian origin, consistent with multiple introductions of this species elsewhere in Asia. In addition, just a single lineage of P. maculata is established in China, which shares with populations in Brazil.


Assuntos
Malus/parasitologia , Caramujos , Animais , Genes Mitocondriais , Haplótipos , Filogenia , Filogeografia , Dinâmica Populacional , Caramujos/classificação , Caramujos/genética
12.
Mol Phylogenet Evol ; 118: 357-368, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29107619

RESUMO

The genus Candidula (Geomitridae), consisting of 28 species in Western Europe as currently described, has a disjunct distribution in the Iberian Peninsula, Italy, the Balkans, the Aegean Islands, and one species on the Canary Islands. Although the genus is seemingly well defined by characters of the reproductive system, the relationships within the genus are still unclear and some authors have indicated a possible subgeneric division based on the internal morphology of the dart sac. Despite substantial phylogenetic incongruence, we present a well-resolved molecular phylogeny of Candidula based on two mitochondrial genes (COI and 16S rRNA), the nuclear rDNA region (5.8S rNRA + ITS2 + 28S rRNA) and seven additional nuclear DNA regions developed specifically for this genus (60SL13, 60SL17, 60SL7, RPL14, 40SS6, 60SL9, 60SL13a), in total 5595 bp. Six reciprocally monophyletic entities including Candidula species were recovered, grouping into two major clades. The incorporation of additional geomitrid genera allowed us to unequivocally demonstrate the polyphyly of the genus Candidula. One major clade grouped species from southern France and Italy with the widely distributed species C. unifasciata. The second major clade grouped all the species from the Iberian Peninsula, including C. intersecta and C. gigaxii. Candidula ultima from the Canary Islands was recovered as separated lineage within the latter clade and related to African taxa. The six monophyla were defined as six new genera belonging to different tribes within the Helicellinae. Thus, we could show that similar structures of the stimulatory apparatus of the genital system in different taxa do not necessarily indicate a close phylogenetic relationship in the Geomitridae. More genera of the family are needed to clarify their evolutionary relationships, and to fully understand the evolution of the stimulatory apparatus of the genital system within the Geomitridae.


Assuntos
Núcleo Celular/genética , Mitocôndrias/genética , Caramujos/classificação , Animais , Sequência de Bases , Complexo IV da Cadeia de Transporte de Elétrons/química , Complexo IV da Cadeia de Transporte de Elétrons/genética , Evolução Molecular , Filogenia , RNA Ribossômico 16S/química , RNA Ribossômico 16S/genética , RNA Ribossômico 28S/química , RNA Ribossômico 28S/genética , RNA Ribossômico 5,8S/química , RNA Ribossômico 5,8S/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Caramujos/genética
13.
Mol Phylogenet Evol ; 120: 218-232, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29247848

RESUMO

The land snail Cornu aspersum aspersum, native to the Mediterranean region, has been the subject of several anatomical and molecular studies leading to recognize two divergent lineages, named "East" and "West" according to their geographical distribution in North Africa. The first biogeographical scenario proposed the role of Oligocene paleogeographic events and Quaternary glacial refugia to explain spatial patterns of genetic variation. The aim of this study was to refine this scenario using molecular and morphometric data from 169 populations sampled across Mediterranean islands and continents. The two previously described lineages no longer correspond to distinct biogeographical entities. Phylogenetic relationships reveal the existence of seven clades, do not support the Tyrrhenian vicariance hypothesis, and suggest that C. a. aspersum most likely originates from North Africa. We found two contrasted patterns with the seven clades defining spatially well-structured populations in the southern Mediterranean whereas one clade is distributed across the basin. High genetic diversities and rates of endemism in North Africa support the role of this region for the diversification of C. a. aspersum. In referring to divergence times previously estimated, we suggest allopatric differentiation due to geological changes of the Atlas system and multiple refugial areas during Pleistocene glaciations. The new biogeographical scenario implies an initial range expansion from North Africa to the Iberian Peninsula and the peri-Tyrrhenian regions through land bridges connections during the Messinian Salinity Crisis and Pleistocene glaciations. Historical events appear to have also structured morphometric variation but recent dispersal events favored the emergence of secondary contacts between clades. Southern Mediterranean clades are limited to their initial distribution and populations of the recent clade would have rapidly recolonized the whole Mediterranean in the Holocene due to greater adaptive potential and the influence of human transportations.


Assuntos
Caramujos/classificação , África do Norte , Animais , Teorema de Bayes , Citocromos b/química , Citocromos b/classificação , Citocromos b/genética , DNA Mitocondrial/química , DNA Mitocondrial/classificação , DNA Mitocondrial/genética , Europa (Continente) , Variação Genética , Haplótipos , Humanos , Região do Mediterrâneo , Repetições de Microssatélites/genética , Filogenia , Filogeografia , Análise de Componente Principal , RNA Ribossômico 16S/química , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , Caramujos/anatomia & histologia , Caramujos/genética
14.
BMC Evol Biol ; 17(1): 231, 2017 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-29178825

RESUMO

BACKGROUND: Due to their great species and ecological diversity as well as their capacity to produce hundreds of different toxins, cone snails are of interest to evolutionary biologists, pharmacologists and amateur naturalists alike. Taxonomic identification of cone snails still relies mostly on the shape, color, and banding patterns of the shell. However, these phenotypic traits are prone to homoplasy. Therefore, the consistent use of genetic data for species delimitation and phylogenetic inference in this apparently hyperdiverse group is largely wanting. Here, we reconstruct the phylogeny of the cones endemic to Cabo Verde archipelago, a well-known radiation of the group, using mitochondrial (mt) genomes. RESULTS: The reconstructed phylogeny grouped the analyzed species into two main clades, one including Kalloconus from West Africa sister to Trovaoconus from Cabo Verde and the other with a paraphyletic Lautoconus due to the sister group relationship of Africonus from Cabo Verde and Lautoconus ventricosus from Mediterranean Sea and neighboring Atlantic Ocean to the exclusion of Lautoconus endemic to Senegal (plus Lautoconus guanche from Mauritania, Morocco, and Canary Islands). Within Trovaoconus, up to three main lineages could be distinguished. The clade of Africonus included four main lineages (named I to IV), each further subdivided into two monophyletic groups. The reconstructed phylogeny allowed inferring the evolution of the radula in the studied lineages as well as biogeographic patterns. The number of cone species endemic to Cabo Verde was revised under the light of sequence divergence data and the inferred phylogenetic relationships. CONCLUSIONS: The sequence divergence between continental members of the genus Kalloconus and island endemics ascribed to the genus Trovaoconus is low, prompting for synonymization of the latter. The genus Lautoconus is paraphyletic. Lautoconus ventricosus is the closest living sister group of genus Africonus. Diversification of Africonus was in allopatry due to the direct development nature of their larvae and mainly triggered by eustatic sea level changes during the Miocene-Pliocene. Our study confirms the diversity of cone endemic to Cabo Verde but significantly reduces the number of valid species. Applying a sequence divergence threshold, the number of valid species within the sampled Africonus is reduced to half.


Assuntos
Genoma Mitocondrial , Filogenia , Caramujos/classificação , Caramujos/genética , Animais , Sequência de Bases , Cabo Verde , DNA Mitocondrial/genética , Variação Genética , Análise de Sequência de DNA , Especificidade da Espécie
15.
Appl Environ Microbiol ; 83(23)2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-28986377

RESUMO

Cone snails are biomedically important sources of peptide drugs, but it is not known whether snail-associated bacteria affect venom chemistry. To begin to answer this question, we performed 16S rRNA gene amplicon sequencing of eight cone snail species, comparing their microbiomes with each other and with those from a variety of other marine invertebrates. We show that the cone snail microbiome is distinct from those in other marine invertebrates and conserved in specimens from around the world, including the Philippines, Guam, California, and Florida. We found that all venom ducts examined contain diverse 16S rRNA gene sequences bearing closest similarity to Stenotrophomonas bacteria. These sequences represent specific symbionts that live in the lumen of the venom duct, where bioactive venom peptides are synthesized.IMPORTANCE In animals, symbiotic bacteria contribute critically to metabolism. Cone snails are renowned for the production of venoms that are used as medicines and as probes for biological study. In principle, symbiotic bacterial metabolism could either degrade or synthesize active venom components, and previous publications show that bacteria do indeed contribute small molecules to some venoms. Therefore, understanding symbiosis in cone snails will contribute to further drug discovery efforts. Here, we describe an unexpected, specific symbiosis between bacteria and cone snails from around the world.


Assuntos
Venenos de Moluscos/química , Caramujos/microbiologia , Stenotrophomonas/isolamento & purificação , Stenotrophomonas/fisiologia , Simbiose , Animais , DNA Bacteriano/genética , Microbiota , Venenos de Moluscos/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Filogenia , RNA Ribossômico 16S/genética , Caramujos/classificação , Caramujos/fisiologia , Stenotrophomonas/genética
16.
Parasit Vectors ; 10(1): 460, 2017 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-29017583

RESUMO

BACKGROUND: This study was designed to determine the distribution and identity of potential intermediate snail hosts of Schistosoma spp. in Bengo, Luanda, Kwanza Norte and Malanje Provinces in north-western Angola. This is an area where infection with Schistosoma haematobium, causing urogenital schistosomiasis, is common but little is yet known about transmission of the disease. Angola has had a varied past with regard to disease control and is revitalising efforts to combat neglected tropical diseases. METHODS: Snails were sampled from 60 water-contact points. Specimens of the genera Bulinus, Biomphalaria or Lymnaea were screened for trematode infections by inducing cercarial shedding. Snails were initially identified using shell morphology; subsequently a cytochrome c oxidase subunit 1 (cox1) gene fragment was amplified from a subset of snails from each site, for molecular identification. Cercariae were captured onto FTA cards for molecular analysis. Specimens of Bulinus angolensis collected from the original locality of the type specimen have been characterised and comparisons made with snails collected in 1957 held at the Natural History Museum, London, UK. RESULTS: In total snails of nine genera were identified using morphological characteristics: Biomphalaria, Bulinus, Gyraulus, Lanistes, Lentorbis, Lymnaea, Melanoides, Physa and Succinea. Significant for schistosomiasis transmission, was the discovery of Bulinus globosus, B. canescens, B. angolensis, B. crystallinus and Biomphalaria salinarum in their type-localities and elsewhere. Bulinus globosus and B. angolensis occurred in two distinct geographical areas. The cox1 sequence for B. globosus differed markedly from those from specimens of this species collected from other countries. Bulinus angolensis is more closely related to B. globosus than originally documented and should be included in the B. africanus group. Schistosoma haematobium cercariae were recovered from B. globosus from two locations: Cabungo, Bengo (20 snails) and Calandula, Malanje (5 snails). Schistosoma haematobium cercariae were identified as group 1 cox1 corresponding to the type common throughout the African mainland. CONCLUSIONS: Various freshwater bodies in north-western Angola harbour potential intermediate snail hosts for urogenital schistosomiasis, highlighting the need to map the rest of the country to identify areas where transmission can occur and where control efforts should be targeted. The molecular phylogeny generated from the samples confirmed that considerable variation exists in B. globosus, which is the primary snail host for S. haematobium in many regions of Africa.


Assuntos
Distribuição Animal , Bulinus/classificação , Caramujos/classificação , Angola , Animais , Bulinus/genética , Bulinus/parasitologia , Bulinus/fisiologia , Cercárias , Vetores de Doenças , Água Doce/parasitologia , Doenças Negligenciadas/epidemiologia , Doenças Negligenciadas/parasitologia , Filogenia , Schistosoma haematobium/isolamento & purificação , Schistosoma haematobium/fisiologia , Esquistossomose Urinária/parasitologia , Esquistossomose Urinária/transmissão , Caramujos/genética , Caramujos/parasitologia
17.
Acta Parasitol ; 62(3): 493-501, 2017 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-28682781

RESUMO

Rapid losses of biodiversity due to the changing landscape have spurred increased interest in the role of species diversity and disease risk. A leading hypothesis for the importance of biodiversity in disease reduction is the dilution effect, which suggests that increasing species diversity within a system decreases the risk of disease among the organisms inhabiting it. The role of species diversity in trematode infection was investigated using field studies from sites across the U.S. to examine the impact of snail diversity in the infection dynamics of both first and second intermediate larval stages of Echinostoma spp. parasites. The prevalence of Echinostoma spp. sporocysts/rediae infection was not affected by increases in snail diversity, but significant negative correlations in metacercariae prevalence and intensity with snail diversity were observed. Additionally, varying effectiveness of the diluting hosts was found, i.e., snail species that were incompatible first intermediate hosts for Echinostoma spp. were more successful at diluting the echinostome parasites in the focal species, while H. trivolvis, a snail species that can harbor the first intermediate larval stages, amplified infection. These findings have important implications not only on the role of species diversity in reducing disease risk, but the success of the parasites in completing their life cycles and maintaining their abundance within an aquatic system.


Assuntos
Biodiversidade , Echinostoma/fisiologia , Caramujos/classificação , Caramujos/genética , Animais , Interações Hospedeiro-Parasita , Larva
18.
Mol Phylogenet Evol ; 114: 367-381, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28669812

RESUMO

Under current marine snail taxonomy, the majority of whelks from the Southern Hemisphere (Buccinulidae) are hypothesised to represent a monophyletic clade that has evolved independently from Northern Hemisphere taxa (Buccinidae). Phylogenetic analysis of mitochondrial genomic and nuclear ribosomal DNA sequence data indicates that Southern Hemisphere taxa are not monophyletic, and results suggest that dispersal across the equator has occurred in both directions. New Zealand buccinulid whelks, noted for their high endemic diversity, are also found to not be monophyletic. Using independent fossil calibrations, estimated genetic divergence dates show remarkable concordance with the fossil record of the Penion and Kelletia. The divergence dates and the geographic distribution of the genera through time implies that some benthic marine snails are capable of dispersal over long distances, despite varied developmental strategies. Phylogenetic results also indicate that one species, P. benthicolus belongs in Antarctoneptunea.


Assuntos
Fósseis , Caramujos/classificação , Animais , DNA/química , DNA/isolamento & purificação , DNA/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/classificação , Complexo IV da Cadeia de Transporte de Elétrons/genética , Evolução Molecular , Variação Genética , Nova Zelândia , Filogenia , RNA Ribossômico 16S/classificação , RNA Ribossômico 16S/genética , RNA Ribossômico 28S/classificação , RNA Ribossômico 28S/genética , Análise de Sequência de DNA , Caramujos/genética
19.
PLoS One ; 12(7): e0180728, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28704536

RESUMO

One major goal for phylogeographical studies is to elucidate respective roles of multiple evolutionary and ecological forces that shape the current distribution patterns. In marine and coastal ecosystems, it has been generated a common realization that species with enormous population size and pelagic larval stages can disperse across broad geographical scales, leading to weak or even no phylogeographical structure across large geographical scales. However, the violation of such realization has been frequently reported, and it remains largely unexplored on mechanisms responsible for various phylogeographical patterns observed in different species at varied geographical scales. Here, we used a species-rich genus Nassarius to assess and compare phylogeographical patterns in congeneric species, and discuss causes and consequences underlying varied phylogeographical patterns. Interestingly, we observed complex phylogeographical patterns both within single species and across multiple species, and multiple analyses showed varied levels of genetic heterogeneity among sites within and across species. Available evidence suggests that related species with similar biological characteristics may not be necessary to result in consistent phylogeographical patterns. Multiple factors, including larval ecology, interactions between dispersal and natural selection, and human activity-mediated dispersal, can partially explain the complex patterns observed in this study. Deep investigations should be performed on these factors, particularly their respective roles in determining evolutionary/ecological processes to form phylogeographical patterns in species with high dispersal capacities in marine and coastal ecosystems.


Assuntos
Ecossistema , Heterogeneidade Genética , Caramujos/genética , Animais , Filogenia , Filogeografia , Seleção Genética , Caramujos/classificação
20.
Mol Phylogenet Evol ; 111: 169-184, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28390908

RESUMO

The Hygromiidae is a highly diverse group of land snails with a distribution range stretching throughout the Palearctic region from the Macaronesian Islands to the Russian Far East and reaching southwards to the north-eastern Ethiopian region. So far, the classification of the family largely rested on the structure of the dart apparatus, an accessory genital organ. We used nuclear and mitochondrial DNA sequences of almost all genera to reconstruct the phylogeny of the Hygromiidae. Several of the clades found in the molecular phylogenetic analyses represent regional radiations that partly show a high variation in the structure of the dart apparatus. Thus, several of the currently accepted subdivisions of the family, which included taxa with similar dart apparatus from different regions, turned out to be polyphyletic. We newly delimit three subfamilies within the family, Hygromiinae, Leptaxinae and Trochulinae on the basis of our phylogenetic analyses. The Hygromiinae are further subdivided into Hygromiini and Perforatellini trib. nov. The Leptaxinae are classified in Leptaxini, Metafruticicolini and Cryptosaccini trib. nov. The Trochulinae are the most diverse group including Ciliellini, Archaicini, Ganulini trib. nov., Urticicolini trib. nov., Trochulini, Caucasigenini trib. nov., Ashfordini trib. nov., Halolimnohelcini and Monachaini. Moreover, two new genera, Coronarchaica gen. nov. from Central Asia and Noricella gen. nov. from the Alps, are described. The Hygromiidae originated in the western Palaearctic, from where the Central Asian mountain regions, the Macaronesian Islands, the Caucasus region and sub-Saharan East Africa were colonized. The radiation of the Hygromiidae as well as those of several other land snail families was dispersal limited. Because of the low dispersal abilities of land snails, the period until an isolated region is colonized by a group by chance dispersal is comparatively longer than the period necessary for morphological and ecological diversification of the group within the newly colonized region. Some of the regional radiations coincided with orogeny in the respective areas and were probably triggered by the development of geographical barriers and new niches.


Assuntos
Filogenia , Filogeografia , Caramujos/classificação , Animais , Teorema de Bayes , Sequência Consenso , DNA Mitocondrial/genética , Caramujos/genética
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