The impact of tick parasites on the behaviour of the lizard Tiliqua rugosa

Populations of the Australian sleepy lizard, Tiliqua rugosa, near Mt. Mary, South Australia carry natural infestations of two tick species Aponomma hydrosauri and Amblyomma limbatum. In field experiments at two sites, 18 km apart, lizards with experimentally increased tick loads had smaller home ranges, moved shorter distances in a day, and were found basking more but moving less often than lizards from which ticks were experimentally removed. The results were consistent for adult lizards in two years, and for sub-adults in a third year. Laboratory trials showed that juvenile lizards that had tick infestations had lower sprint speeds than uninfested siblings, and that adults with tick infestations had less endurance than those that were uninfested. The results contrast with those of a previous survey that showed that lizards with high tick loads had greater body size and remained longer at a site, but indicate that there may be a balance, for lizards, between the fitness advantages in occupying habitats with high-quality resources, and the costs from parasites that also prefer those habitats. Received: 02 March 1999 / Accepted: 07 October 1999     

Structure of a porcine relaxin inactive on the mouse pubic ligament

In addition to B31 (CM-a) and B28 (CM-B) relaxins, acid-acetone extracts of ovaries of pregnant sows contain a third major relaxin species (relaxin C). The major components of relaxin C possess about half the activity of CM-a or CM-B in the guinea pig palpation assay, but are completely inactive in the mouse pubic ligament assay. Its uterotrophic and protein anabolic effects in ovariectomized, estrogen-primed mice, however, are comparable to those of CM-B. Sequence analysis indicates that the two major components of relaxin C, like the other porcine relaxins, consist of two polypeptide chains linked by disulfide bonds. The shorter (A) chains are identical to the A chains of the other porcine relaxins, except for the absence of the N-terminal arginine residue. The B chains display microheterogeneity; the B sequences of the two predominant species are the same as those of the other porcine relaxins through B25, but terminate at valine residue B25 or serine residue B26, respectively.     

Elasto-thixotropic properties of bronchial mucus and polymer analogs. I. Experimental results

The non-newtonian viscous and elasto-thixotropic properties of native and lyophilized pathological bronchial mucus and of polymer solutions (3% and 6% PIB in decalin) used as mucus analogs were analyzed using a cone-plate Carri-Med rheometer and a Couette viscoelastometer that we have specifically developed for measuring the rheological properties of bronchial mucus in clinical practice. The master curves obtained for apparent viscosity under steady conditions as a function of shear rates (gamma: 2.6 X 10(-3) to 6.9 X 10(1) sec-1) were fairly similar, whatever the apparatus used. Under transient conditions, at low shear rate (gamma less than 1.4 sec-1), PIB and mucus exhibited a typical viscoelastic behavior: the shear stress increased slightly up to a steady-state value. At higher gamma, a transitory overshoot of sigma characteristic of the elastothixotropic systems appeared. Such a behavior can be interpreted as resulting from structural changes such as formation and rupture of the three-dimensional network present in bronchial mucus as in polymer solutions.     

Sexual behavior and serum hormone levels in aging rhesus males: effects of environmental change

Old (N = 9) and middle-aged (N = 9) rhesus males (Macaca mulatta) that were housed in the same type of home cage and the same room for several years were moved to a new location in an adjacent building. Their sexual behavior and hormone levels in the weeks preceding the move were compared to those after the move. The hypothesis that the nonspecific sensory stimulation provided by the move would increase levels of sexual behavior was not supported by the data. To the contrary, the percentages of tests with contacts, mounts, and penile erections, and the rate of contacting the female, decreased significantly for both old and middle-aged males. The intromission rate of middle-aged, but not of old, males also decreased. In consonance with previous findings, middle-aged males displayed significantly higher levels of sexual activity than did old males. The differences were observed both before and after the move. Serum testosterone levels did not differ between middle-aged and old males, and the move did not produce significant changes in testosterone levels. Serum cortisol levels were significantly higher immediately after the move (1 hr) but returned to premove levels the following day.     

An improved purification method for cytosolic malate dehydrogenase from several sources

A new purification method for cytosolic malate dehydrogenases from several sources has been developed. The procedure, employing chromatographies on 5'AMP-Sepharose, DEAE-Sephacel and Blue-Sepharose, allows for a rapid isolation of the enzyme (approximately 40 hours), in large quantities, with good yields (45-54%). The specific activity of final preparations were around 1300 I.U./mg and were judged homogeneous by polyacrylamide gradient gel and sodium dodecyl sulfate polyacrylamide gel electrophoresis, high performance size exclusion chromatography and isoelectric focusing.     

Characterisation of Trypanosoma cruzi populations by dna polymorphism of the cruzipain gene detected by single-stranded dna conformation polymorphism (SSCP) and direct sequencing

Fifty fresh isolates of Trypanosoma cruzi from Triatoma dimidiata vectors and 31 from patients with Chagas disease were analysed for DNA polymorphisms within the 432-bp core region of the cruzipain gene which encodes the active site of cathepsin L-like cystein proteinase. The cruzipain gene showed signs of polymorphism consisting of four different DNA sequences in Central and South American isolates of T. cruzi. The PCR fragments of Guatemalan isolates could be divided into three groups, Groups 1, 2 and 3, based on different patterns of single-stranded DNA conformation polymorphism. All of the strains isolated from Brazil, Chile, and Paraguay, except for the CL strain, showed a Group 4 pattern. Two to four isolates from each group were analysed by cloning and sequencing. A silent mutation occurred between Groups 1 and 2, and five nucleotides and two aa substitutions were detected between Groups 1 and 3. The DNA sequence of Group 4 contained five nucleotides and one aa substitution from Group 1. All of the DNA sequences corresponded well with the single-stranded DNA conformation polymorphism. The Group 1 isolates, the majority in the Guatemalan population (70/81, 86.4%), were isolated from both triatomines and humans, but Group 3 were isolated only from humans. Moreover, the Group 2 isolates were detected only in triatomine vectors (9/50; 18%), but never in humans (0/32, P<0.05) suggesting that this group has an independent life-cycle in sylvatic animals and is maintained by reservoir hosts other than humans.