Seasonal and spatial dynamics of ectoparasite infestation of a threatened reptile, the tuatara (Sphenodon punctatus)

Abstract The conservation of threatened vertebrate species and their threatened parasites requires an understanding of the factors influencing their distribution and dynamics. This is particularly important for species maintained in conservation reserves at high densities, where increased contact among hosts could lead to increased rates of parasitism. The tuatara (Sphenodon punctatus) (Reptilia: Sphenodontia) is a threatened reptile that persists at high densities in forests (～ 2700 tuatara/ha) and lower densities in pastures and shrubland (< 200 tuatara/ha) on Stephens Island, New Zealand. We investigated the lifecycles and seasonal dynamics of infestation of two ectoparasites (the tuatara tick, Amblyomma sphenodonti, and trombiculid mites, Neotrombicula sp.) in a mark‐recapture study in three forest study plots from November 2004 to March 2007, and compared infestation levels among habitat types in March 2006. Tick loads were lowest over summer and peaked from late autumn (May) until early spring (September). Mating and engorgement of female ticks was highest over spring, and larval tick loads subsequently increased in early autumn (March). Nymphal tick loads increased in September, and adult tick loads increased in May. Our findings suggest the tuatara tick has a 2‐ or 3‐year lifecycle. Mite loads were highest over summer and autumn, and peaked in March. Prevalences (proportion of hosts infected) and densities (estimated number of parasites per hectare) of ticks were similar among habitats, but tick loads (parasites per host) were higher in pastures than in forests and shrub. The prevalence and density of mites was higher in forests than in pasture or shrub, but mite loads were similar among habitats. We suggest that a higher density of tuatara in forests may reduce the ectoparasite loads of individuals through a dilution effect. Understanding host–parasite dynamics will help in the conservation management of both the host and its parasites.     

Joint Report of the Fourth International Workshop on Lymphocyte Alloantigens of the Horse, Lexington, Kentucky, 12–22 October 1985

Summary. The workshop consisted of 12 monthly cell exchanges of full-sibling families among the 10 participating laboratories. A total of 33 parents, 52 offspring and five unrelated horses were typed by each laboratory using local antisera. The raw data were submitted for central analysis before any identification of the animals was revealed.
Confidence derived from the consistent agreement between the laboratories on the assignment and segregation of the first 10 ELA-W specificities led to the removal of the W (workshop) notation and acceptance of full status as locus A antigens. The seemingly supertypic W11 specificity, however, remained unchanged.
Ten additional specificities were seen to segregate with the ELA system, suggesting either splits of previously described specificities or products of linked loci. The workshop (W) notation was given to the 10 specificities W12-W21, befitting their status as specificities under study.
The previously described ELY-1.1 specificity, characterized by segregation independent from the ELA system, was confirmed along with a new specificity, ELY-1.2, which behaves as an allele of ELY-1.1. For informative families, the two specificities showed codominant expression and appeared to constitute a closed, autosomal system.
The ELY-2.1 specificity was confirmed to segregate independently from the ELA-A and ELY-1 loci.     

Study of permeation and blocker binding in TMEM16A calcium-activated chloride channels

We studied the effects of mutations of positively charged amino acid residues in the pore of X. tropicalis TMEM16A calcium-activated chloride channels: K613E, K628E, K630E; R646E and R761E. The activation and deactivation kinetics were not affected, and only K613E showed a lower current density. K628E and R761E affect anion selectivity without affecting Na⁺ permeation, whereas K613E, R646E and the double mutant K613E + R646E affect anion selectivity and permeability to Na⁺. Furthermore, altered blockade by the chloride channel blockers anthracene-9-carboxylic acid (A-9-C), 4, 4''-Diisothiocyano-2,2''-stilbenedisulfonic acid (DIDS) and T16inh-A01 was observed. These results suggest the existence of 2 binding sites for anions within the pore at electrical distances of 0.3 and 0.5. These sites are also relevant for anion permeation and blockade.     

Can predators maintain parapatry? Ant distribution across a tick parapatric boundary in South Australia

Abstract Ants were sampled by pitfall traps at 85 sites, 0.5 or 1.0km apart, along six transects across a parapatric boundary between the reptile ticks Aponomma hydrosauri and Amblyomma limbatum near Mt Mary in South Australia. There was no tendency for overall ant density, or for the distribution of any single species of ant, to be related to the tick distribution. Thus the survey found no support for the hypothesis that predation by ants was maintaining the boundary. Along transects there were no correlations between ant and tick densities. Thus the survey found no support for the hypothesis that ant predation was a major factor controlling tick densities. These negative results provide further evidence that single, strong ecological processes cannot explain this well-studied parapatric boundary.