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1

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Genetic Analysis of Giardia from Hoofed Farm Animals Reveals Artiodactyl-Specific and Potentially Zoonotic Genotypes (1997)

EY, PETER L. ; MANSOURI, MANDANA ; KULDA, JAROSLAV ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

The @journal of eukaryotic microbiology 44 (1997), S. 0

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ISSN: 1550-7408

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: . Thirty one Giardia isolates, established from six species of hoofed livestock by axenic culture or growth in suckling mice, were compared genetically by analysis of DNA amplified from loci encoding variant surface proteins or the enzyme glutamate dehydrogenase and by allozyme analysis. The isolates were heterogeneous, but all showed affinity with genetic Assemblage A-one of two major assemblages defined previously by analysis of Giardia from humans. Three distinct genotypes were evident. Ten isolates (eight axenic and two established in suckling mice) from an alpaca, pig, horse, cattle and sheep were indistinguishable from human-derived G. intestinalis belonging to a previously designated genetic group (Group I). This genotype seems to have broad host specificity, including a zoonotic potential for humans. Five isolates (two axenic and three established in suckling mice) from an alpaca, a horse and sheep had close affinity with human-derived Group I and Group I1 G. inresrinalis genotypes. The other 16 isolates (comprising both axenic and suckling mouse-propagated cultures derived from cattle, sheep, alpaca, a goat and pigs in Australia and Europe) differed from all other Giardia with “duodenalis” morphology that have been examined by these methods and they segregated as a highly distinct sublineage (referred to herein as ‘Novel livestock’) within genetic Assemblage A. The predominance of ‘Novel livestock’ genotypes in the test panel and their apparent exclusive association with artiodactyl hosts indicates that they may be confined to this group of mammals. Assemblage B genotypes, which are prevalent in humans and some other animal species, were not detected.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1550-7408.1997.tb05970.x

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2

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Genetic relationship among isolates of Helicobacter pylori: evidence for the existence of a Helicobacter pylori species-complex (1997)

Hazell, Stuart L ; Andrews, Ross H ; Mitchell, Hazel M ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology letters 150 (1997), S. 0

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ISSN: 1574-6968

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: We investigated the population genetics of 23 isolates of H. pylori by allozyme electrophoresis using 16 enzyme loci. Isolates were obtained from adult patients of whom 48% were of Greek extraction. Eight patients (35%) had an active duodenal ulcer. Allelic variation per loci ranged from 2 to 11 alleles. Four major genetic clusters were apparent, having 〉75% fixed genetic differences. There was no distinct clustering (clonal structure) on the basis of the geographical origin of the persons from whom isolates were obtained, indicating that this bacterium has not recently jumped a species barrier into humans. Isolates associated with ulcer disease were not monophyletic, with isolates from ulcer patients being found in phylogenetically diverse branches of the dendogram derived from the data. Based on the genetic diversity of H. pylori isolates, we propose that isolates should be classified as belonging not to a single species but to a `Helicobacter pylori species-complex'.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb10345.x

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3

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Effect of delayed mating and prolonged engorgement on the reproductive fitness of female Amblyomma limbatum (Acari: Ixodidae) in marginal population areas (1993)

Chilton, Neil B. ; Andrews, Ross H. ; Bull, C. Michael

Springer

Oecologia 94 (1993), S. 67-71

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ISSN: 1432-1939

Keywords: Amblyomma limbatum ; Reptile tick ; Reproductive fitness ; Delayed mating ; parapatry

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Reptile ticks mate while females are attached to their host. Following mating, females engorge, detach and then lay their eggs. This study examines whether the time that females of the reptile tick Amblyomma limbatum spend on hosts prior to mating and the time they take to engorge on hosts after mating influence their reproductive fitness, as measured by the number of viable eggs they produce. When compared with females that experienced no temperature-induced delay in mating, females attached for an initial period to hosts with body temperatures too low to induce mating had no decline in their reproductive fitness, once provided with suitable temperatures for mating. However, on hosts with suitable body temperatures for mating, female ticks that took longer to mate, took longer to engorge and had reduced reproductive fitness. In addition, females that spent more than 20 days feeding on hosts after mating had reduced reproductive fitness, irrespective of the time they spent on hosts prior to mating compared with females with shorter feeding periods. Thus, the time that A. limbatum females spent on hosts prior to mating and/or after mating has a significant bearing on the number viable progeny produced. The ecological implications of these results are discussed in relation to females colonizing marginal population areas at the edge of their distributional range.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00317303

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4

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Niche segregation in reptile ticks: attachment sites and reproductive success of females (1992)

Chilton, Neil B. ; Bull, C. Michael ; Andrews, Ross H.

Springer

Oecologia 90 (1992), S. 255-259

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ISSN: 1432-1939

Keywords: Niche segregation ; Attachment sites ; Reptile ticks ; Reproductive success

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary This study examined whether the mating or feeding success of females of two tick species, Amblyomma limbatum and Aponomma hydrosauri, is influenced by their site of attachment on a host. Marked interspecific differences were detected in the preferred sites of attachment of females to their common host, the sleepy lizard Tiliqua rugosa, with Amb. limbatum found predominantly in the ears and on the lower back, while Ap. hydrosauri preferred to attach under the forelimbs and on the midback. Data from field surveys suggested that higher proportions of females were mated in the preferred sites for Ap. hydrosauri, and in one of the preferred sites for Amb. limbatum. However, laboratory and field experiments showed that for both species, the mean time before females were mated, mean engorgement time and mean feeding rate were independent of where they were attached to a host. Four hypotheses were considered as explanations of the observed niche segregation; intespecific competition, avoidance of pheromone jamming or adaptations, to maximize mating and feeding, and minimize physical disturbance. These could not totally explain the observed site specificity in either tick species. Site specificity may represent adaptations by each species to other host species encountered within their distributional range.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00317183

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5

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Mating behaviour and parapatry in two species of Australian reptile tick (1988)

Chilton, Neil B. ; Andrews, Ross H.

Springer

Oecologia 75 (1988), S. 146-152

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ISSN: 1432-1939

Keywords: Mating behaviour ; Parapatry ; Reproductive interference ; Reptile ticks ; Temperature

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Few quantitative studies have examined the ecological consequences of similarities and/or differences in mating behaviour of parapatric species. Reproductive interference occurs between several parapatric species of Australian reptile tick, due to similarities in their mating behaviour (Andrews et al. 1982a). Attempts to determine whether reproductive interference serves to maintain parapatry between Amblyomma limbatum and Aponomma hydrosauri have been hindered because of difficulties in providing conditions conducive to conspecific mating in Amb. limbatum. The present study examined whether off-host and/or onhost temperature influenced the subsequent mating behaviour (i.e. the proportion of females that mate and the time when mating occurs) of these two species. Irrespective of the temperature experienced by ticks prior to host attachment, specific on-host temperatures were needed to induce mating in Amb. limbatum (i.e. host cloacal temperatures 〉32° C prior to the time of peak mating activity). Significantly more Amb. limbatum females were mated and the time taken by females to mate decreased with increasing on-host temperatures. mating in Ap. hydrosauri occurred over a wider range of on-host temperatures and the time when mating occurred did not alter at different on-host temperatures. In addition, significantly more Ap. hydrosauri males moved and each male made more moves on hosts than did Amb. limbatum males. It is suggested that Ap. hydrosauri may in consequence have a competitive mating advantage over Amb. limbatum at a boundary. Similarities in mating behaviour, on the other hand, increase the probability of reproductive interference, hence reduce the reproductive fitness of colonizing females of both species. We propose that similarities and differences in mating behaviour could play a critical role in the maintenance of parapatric boundaries.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00378828

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6

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Genetic evidence for a complex of species within Rugopharynx australis (Mönnig, 1926) (Nematoda: Stronglyloidea) from macropodid marsupials (1996)

Chilton, Neil B. ; Andrews, Ross H. ; Beveridge, Ian

Springer

Systematic parasitology 34 (1996), S. 125-133

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ISSN: 1573-5192

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract An electrophoretic analysis using 17 enzyme loci was carried out on specimens of the gastric nematode of macropodid marsupials, Rugopharynx australis (Mönnig, 1926), collected from Macropus eugenii (Desmarest), M. fuliginosus (Desmarest), M. giganteus Shaw, M. robustus Gould, M. rufogriseus (Desmarest), M. rufus (Desmarest), Thylogale billardierii (Desmarest) and Wallabia bicolor (Desmarest) from south-eastern Australia. The extent of fixed genetic differences between nematodes from different host species ranged from 0–53%. The two distinct morphological forms of the parasite found in M. rufogriseus differed at 50% of loci. Specimens present in M. fuliginosus and M. giganteus were indistinguishable genetically, as were nematodes from M. rufus and M. robustus. Of the two morphologically distinct congeners included in the analysis as controls, Rugopharynx epsilon (Johnston & Mawson, 1939) was genetically distinct (46–69% fixed genetic differences) from all specimens of the R. australis complex while R. rufogrisea Magzoub, 1964 was closely related to one of the two species occuring in M. rufogriseus. It was concluded that R. australis is a species complex, with a genetically distinct species present in M. eugenii, M. fuliginosus/M. giganteus, M. robustus/M. rufus, W. bicolor and T. billardierii, and two species in M. rufogriseus.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00009686

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