PubMed Health⌕ Search

Biomedical subjects

I Beveridge

Publications and source records attributed to I Beveridge.

At least 37 records · Page 2Linked to original sources
PubMed2001

Mutation scanning analysis of sequence heterogeneity in the second internal transcribed spacer (rDNA) within some members of the Hypodontus macropi (Nematoda: Strongyloidea) complex.

Single-strand conformation polymorphism analysis was employed to investigate sequence variation in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA within and among individuals representing three operational taxonomic units (OTUs) of Hypodontus macropi from different species of Australian macropodid marsupials. Of the 96 nematodes analysed, totals of 3 (OTU1 from Petrogale persephone), 10 (OTU2 from Macropus robustus) and 7 (OTU9 from Macropus rufus) representative individuals were selected for DNA sequencing to characterise and estimate the magnitude of nucleotide variation in the ITS-2. While no unequivocal nucleotide difference in the ITS-2 was detectable within OTU1, most sequence variation (3/44.7%) detected within OTU2 and OTU9 was related chiefly to dinucleotide (CA, TA, or a combination of both) differences. This microsatellite variability in some H. macropi OTUs suggests that the ITS-2 rDNA may be subjected to slippage events during DNA replication, resulting in short dinucleotide repeat tracts being dispersed throughout the ITS-2 lineages, or possibly transposition and/or crossing-over events. Nucleotide variation in the ITS-2 of individual OTUs was related to the proposed secondary structure for the precursor ribosomal RNAs. Most of the sequence heterogeneity or polymorphism within OTU2 and OTU9 occurred in loops or bulges of the predicted secondary structure, which appear not to be under functional constraint. The findings of this study have implications for investigating speciation events and population differentiation in nematodes at the molecular level.

Animals↗
PubMed2001

Single-strand conformation polymorphism analysis of genetic variation in Labiostrongylus longispicularis from kangaroos.

Single-strand conformation polymorphism (SSCP) analysis was employed to screen for sequence heterogeneity in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA of Labiostrongylus longispicularis, a parasitic strongylid nematode occuring in some species of kangaroo in different geographical regions of Australia. The results showed that most of the nematodes screened had different SSCP profiles, which were subsequently shown to correspond to polymorphisms and/or an indel in the ITS-2 sequence. These variable sites related mainly to unpaired regions of the predicted secondary structure of the precursor rRNA molecule. SSCP profiles could be used to distinguish L. longispicularis in Macropus robustus robustus (New South Wales) from L. longispicularis in Macropus robustus erubescens and Macropus rufus (South Australia). This difference corresponded to a transversional change in the ITS-2 sequence at alignment position 82. The study demonstrated clearly the effectiveness of SSCP analysis for future large-scale population genetic studies of L. longispicularis in order to test the hypothesis that L. longispicularis from different geographical regions represents multiple sibling species.

Animals↗
PubMed2001

Evolutionary relationships of trichostrongyloid nematodes (Strongylida) inferred from ribosomal DNA sequence data.

The evolutionary relationships of 21 species of trichostrongyloid nematodes were determined by use of sequence data of the second internal transcribed spacer of the ribosomal DNA aligned according to secondary structure information. Irrespective of the method of analysis used, the topologies of the phylogenetic trees derived from the molecular data differed with respect to all four hypotheses proposed previously for the evolutionary relationships of the different subfamilies within the Trichostrongylidae based on morphological data. Thus, the molecular data set did not resolve the conflict between the four previous proposals for the subfamilial relationships. Nonetheless, all trees derived from the molecular data showed strong support for the exclusion of the genera Filarinema and Amidostomum from the clade containing the species within the family Trichostrongylidae. This represents a major difference from the most recent proposal of the systematics of the Trichostrongyloidea in which these two genera were included within the Trichostrongylidae. Therefore, the molecular data support an earlier systematic framework in which Filarinema and Amidostomum were considered to be sister groups of the Trichostrongyloidea.

Animals↗
PubMed2001

Co-evolutionary relationships between the nematode subfamily Cloacininae and its macropodid marsupial hosts.

Morphologically based phylogenies of the cloacinine genera Cyclostrongylus, Macropostrongylus, Pharyngostrongylus, Popovastrongylus, Rugopharynx, Thallostonema, Wallabinema, and Zoniolaimus were constructed and compared with the phylogeny of their respective macropodid hosts. These comparisons show some evidence of co-speciation. However, there was little consistency among trees of different nematode genera, parasite species were scattered amongst hosts and basal parasite taxa were, in some instances, parasitic in hosts belonging to derived clades. A cladistic analysis, using as characters 208 cloacinine nematode species found in 23 species of host, produced a tree largely resembling that of the host tree but with significant differences explainable by host switching among macropodids occupying similar habitat. Nematodes were moderately host-specific, but some species occurred in three or more distantly related host species indicating a degree of host switching. The results are more consistent with the hypothesis of a colonisation of macropodid hosts by cloacinine nematodes rather than a prolonged period of co-speciation although alternative interpretations of the data are also considered.

Animals↗
PubMed2001

Proemotobothrium n. g. (Cestoda: Trypanorhyncha), with the redescription of P. linstowi (Southwell, 1912) n. comb. and description of P. southwelli n. sp.

A new genus, Proemotobothrium (Trypanorhyncha: Otobothriidae), is erected to contain P. linstowi (Southwell, 1912) n. comb. (syn. Otobothrium magnum Southwell, 1924) and P. southwelli n. sp. The new genus is characterised by two bothridia, paired bothridial pits, an acraspedote scolex, elongate bulbs, four hooks per principal row, hooks 4 (4') being small and uncinate, a single, filiform, intercalary hook between each principal row and by the arrangement, in tandem, of the two or three extra hooks of the armature of the external surface of the tentacle, a pattern previously known only in the family Mixodigmatidae. The two species are distinguished from one another on the basis of measurements of the scolex and bulbs, the sizes of the hooks of the principal rows and by the number and size of the additional hooks in the linear arrays on the external surface of the tentacle.

Animals↗
PubMed2001

Grillotia australis n. sp. and G. pristiophori n. sp. (Cestoda: Trypanorhyncha) from Australian elasmobranch and teleost fishes.

Two new species of Grillotia are described from elasmobranch and teleost fishes from south-eastern Australia. G. australis n. sp., from the Australian angel shark Squatina australis. Regan, most closely resembles G. smarisgora (Wagener, 1854) and G. angeli Dollfus, 1969, differing from both species in the presence of smaller bulbs, two or occasionally three hooks in each intercalary row in the basal region, reduced to one in the metabasal region compared with four or five hooks in the metabasal region of G. smarisgora and a single hook in G. angeli, and in the limited extent of the band of hooklets on the external surface in the basal region of the tentacle, a region which is covered with hooks in G. smarisgora. Plerocerci of this species were found in the mackerel Trachurus declivis (Jenys) (site not known) from Tasmania. G. pristiophori n. sp., from the saw sharks Pristiophorus cirratus (Latham) and P. nudipinnis Günther, most closely resembles G. spinosissima Dollfus, 1969 in possessing a scolex covered with spiniform microtriches, but differs in having six rather than five hooks in each principal row, no intercalary hooks and by possessing a band of hooklets on the external surface of the tentacle which diminishes distally into a single file, rather than persisting as a band eight to nine files wide. G. pristiophori is the first trypanorhynch to be recorded from saw-sharks.

Animals↗
PubMed2001

Echinobothrium chisholmae n. sp. (Cestoda, Diphyllidea) from the giant shovel-nose ray Rhinobatos typus from Australia, with observations on the ultrastructure of its scolex musculature and peduncular spines.

Echinobothrium chisholmae n. sp. is described from Rhinobatos typus Bennett (Rhinobatidae), collected from Heron Island, Great Barrier Reef, Australia. E. chisholmae differs from all congeners in possessing 11 hooks in each dorsal and ventral group on the rostellum and groups of 3-6 hooklets on either side of the hooks. A single metacestode of E. chisholmae was collected from the decapod crustacean Penaeus longistylus Kubo. Yellow pigmentation of the cephalic peduncle in immature adults is caused by the accumulation of large vesicles in the distal cytoplasm of the tegument. The vesicles probably provide materials for spine formation. Ultrastructural examination of the rostellar musculature revealed that the muscles are stratified (striated-like), consisting of a periodic repetition of sarcomeres separated by perforated Z-like lines that are oblique to the long axes of the myofilaments.

Animals↗
PubMed2001

Imidacloprid treatment of marsupials for fleas (Pygiopsylla hoplia).

Two eastern barred bandicoots (Perameles gunnii), two eastern quells (Dasyunrus viverrinus), four fat-tailed dunnarts (Sminthopsis crassicaudata), a Leadbeater's possum (Gymnobelideus leadbeateri), a yellow-bellied glider (Petaurus australis), and a ring-tailed possum (Pseudocheirus peregrinus) were treated with imidacloprid (10.7 +/- 0.6 mg/kg topically, minimum dose 0.5 mg) after observation of fleas (Pygiopsylla hoplia) on animals and in their nest boxes. No live fleas or adverse reactions to imidacloprid were observed for 27 days following treatment. The ease of application, absence of toxicity, and long residual effect makes imidacloprid a useful drug for treating flea infestations in these marsupials.

Administration, Topical↗
PubMed2000

Mitochondrial DNA polymorphism within and among species of Capillaria sensu lato from Australian marsupials and rodents.

The nucleotide variation in a mitochondrial DNA (mtDNA) fragment within and among species of Capillaria sensu lato from Australian marsupials and rodents was analyzed using a mutation scanning/sequencing approach. The fragment of the cytochrome c oxidase subunit I (COI) was amplified by PCR from parasite DNA, and analysed by single-strand conformation polymorphism (SSCP) and sequencing. There was no significant variation in SSCP profiles within a morphospecies from a particular host species, but significant variation existed among morphospecies originating from different host species. The same morphospecies was found to occur in 1-3 tissue habitats within one host individual or within different individuals of a particular species of host from the same or different geographical areas, and morphospecies appeared to be relatively host specific at the generic level. The results indicated that the species of Capillaria sensu lato examined, although highly variable in their host and tissue specificity, may exhibit the greatest degree of specificity at the level of host genus.

Animals↗
PubMed2000

Genetic variation within the ticks Ixodes holocyclus and Ixodes cornuatus from south-eastern Australia.

Ticks from mainland Australia (Victoria, New South Wales and Queensland) and Tasmania, identified morphologically as either Ixodes holocyclus or Ixodes cornuatus, were compared genetically using 24 enzyme loci. The results showed that ticks from three localities in Victoria were genetically similar to I. cornuatus in Tasmania, but both groups had fixed genetic differences at >45% of loci compared with other ticks on the mainland. In addition, there were fixed genetic differences at 0-60% of loci among I. holocyclus from different localities on the mainland. Ixodes holocyclus samples could be divided into four distinct clusters (with fixed genetic differences >15%), three of which were represented by one or two specimens. Nonetheless, these electrophoretic data suggest that I. holocyclus represents a species complex. The results also showed that the morphological criteria used to identify specimens were not always accurate because several specimens had been mis-identified morphologically. Despite limitations with the morphological identification, this study has demonstrated that I. cornuatus can be distinguished from the I. holocyclus species complex using six enzyme loci, providing the foundation for a re-examination of morphological characteristics. The present study has shown that I. cornuatus and the I. holocyclus complexes have a greater distribution than previously reported, with both occurring in sympatry at Cape Patterson, on the southern coastline of Victoria.

Alleles↗
PubMed2000

A molecular systematic framework for equine strongyles based on ribosomal DNA sequence data.

In this study, molecular data sets were used to address the controversies relating to the systematics of strongyloid nematodes of equids utilising morphological data sets. DNA sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were determined for 30 species of equine strongyles and the systematic relationships reconstructed using phenetic and phylogenetic tree-building methods. The molecular data provided support for the hypothesis that the genera with large subglobular buccal capsules are ancestral to those with small cylindrical buccal capsules, but did not provide support for the current division of the subfamilies Strongylinae and Cyathostominae or for some taxonomic groupings (i.e. generic designations of species) within the Cyathostominea based on morphological data. Although not entirely concordant, the current molecular data provide a systematic framework for future studies of equine strongyles, which could be exploited in combination with new, phylogenetically informative morphological data sets.

Animals↗
PubMed2000

Helminth communities of pademelons, Thylogale stigmatica and T. thetis from eastern Australia and Papua New Guinea.

Gastrointestinal helminths were collected from pademelons of the genus Thylogale (Marsupialia: Macropodidae) in eastern Australia and Papua New Guinea. Examined were 12 Thylogale stigmatica stigmatica and 13 T. s. wilcoxi, the latter subdivided into eight specimens from the northern limit of their distribution and five from southern areas, all from eastern Queensland, Australia, one T. s. oriomo from Papua New Guinea and ten T. thetis from southeastern Queensland and northern New South Wales, Australia. Six species of cestodes and 40 species of nematodes were found. The helminth community of T. s. stigmatica was similar to that found in northern specimens of T. s. wilcoxi, while differences from the helminth community present in southern T. s. wilcoxi could be accounted for by parasites acquired from sympatric T. thetis. Thylogale thetis harboured a community of helminths distinct from but related to that in T. stigmatica. The evidence suggests that all subspecies of T. stigmatica examined share a common helminth community, but that in areas of sympatry, T. stigmatica and T. thetis share some of their parasites.

Animals↗
PubMed2000

A redescription of Pintneriella Yamaguti, 1934 (Cestoda: Trypanorhyncha and an examination of its systematic position.

Specimens of Pintneriella musculicola Yamaguti, 1934 are redescribed based on paratype material and specimens subsequently allocated to the species by its describer. The cestode species is characterised by two bothridia, a typical heteroacanthous armature with a distinctive basal swelling and basal armature, a space between hook files 1 and 1', nine hooks per principal row, no intercalary hooks and bands of hooklets or chainettes but a distinctive space on the external surface of the tentacle between hook files 9 and 9'. The strobilia is unknown. The features described indicate that Pintneriella is a valid genus within the Heteracanthoidea. Its currently known morphological features do not allow its allocation to an existing family.

Animals↗
PubMed2000

Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha) from Australian dasyatid and rhinobatid rays.

Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha: Eutetrarhynchidae) is described from the spiral valves of the rays Rhinobatos typus (Rhinobatidae) and Himantura fai (Dasyatidae) from Heron Island, Queensland, Australia. The new species is distinguished from all congeners by the deltoid microtriches covering the anterior 80% of the scolex and the presence of a dorsoventrally elongate genital atrium. The species occurred in the anteriormost section of the spiral valve of R. typus. The orientation of the armature of this and other congeners is such that principal rows of hooks begin on the bothridial surface of the tentacle and end on the antibothridial surface.

Animals↗
PubMed1999

Molecular evidence for cryptic species within Cylicostephanus minutus (Nematoda: Strongylidae).

The nucleotide sequences of the first and second internal transcribed spacers of nuclear ribosomal DNA were determined for adults of Cylicostephanus minutus from different geographical origins. The lengths of first and second internal transcribed spacer sequences ranged from 370 to 372bp and 215 to 216bp, respectively. Pairwise sequence comparisons revealed that some individuals of C. minutus had identical first and second internal transcribed spacer sequences, whereas others differed by 3.0% and 7.4% in their first and second transcribed spacers, respectively. Some individuals with sequence differences originated from the same host. The levels of difference within C. minutus were higher than that between the morphologically distinct species, Cylicostephanus goldi and Cylicostephanus longibursatus (0.8% for the first internal transcribed spacer and 3.8% for the second internal transcribed spacer). The data provide support for the proposal that C. minutus represents a complex of at least two species. In order to study the population genetic structure of C. minutus, a PCR-linked single-strand conformation polymorphism technique was also established.

Animals↗
PubMed1999

Secondary structure model for the ITS-2 precursor rRNA of strongyloid nematodes of equids: implications for phylogenetic inference.

In order to maximise the positional homology in the primary sequence alignment of the second internal transcribed spacer for 30 species of equine strongyloid nematodes, the secondary structures of the precursor ribosomal RNA were predicted using an approach combining an energy minimisation method and comparative sequence analysis. The results indicated that a common secondary structure model of the second internal transcribed spacer of these nematodes was maintained despite significant interspecific differences (2-56%) in primary sequences. The secondary structure model was then used to refine the primary second internal transcribed spacer sequence alignment. The 'manual' and 'structure' alignments were both subjected to phylogenetic analysis to compare the effect of using different sequence alignments on phylogenetic inference. The topologies of the phylogenetic trees inferred from the manual second internal transcribed spacer alignment were usually different to those derived from the structure second internal transcribed spacer alignment. The results suggested that the positional homology in the second internal transcribed spacer primary sequence alignment was maximised when the secondary structure model was taken into consideration.

Animals↗
PubMed1999

Species-specific amplification by PCR of ribosomal DNA from some equine strongyles.

The first and second internal transcribed spacer sequences of 28 morphologically-defined species of horse strongyle were characterized, and specific oligonucleotide primers were designed for some species based on the nucleotide differences. Utilizing these primers, a PCR approach was developed for the specific amplification of ribosomal DNA of Strongylus vulgaris, Cyathostomum catinatum, Cylicocyclus nassatus, Cylicostephanus longibursatus or Cylicostephanus goldi. The method allowed the species-specific amplification of parasite DNA derived from faecal samples and/or copro-cultures, demonstrating the potential of the approach for the diagnosis of equine strongyloidosis. The establishment of this PCR assay also has implications for studying the biology and epidemiology of equine strongyles and anthelmintic resistance using faecal egg count reduction tests.

Animals↗