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     

Antigenic heterogeneity of strains of Saccharomyces cerevisiae and Candida albicans recognised by serum antibodies from patients with Crohn''s disease

Abstract Vitronectin, a serum and extracellular matrix protein involved in immunological reactions, interacts with Helicobacter pylori strains. Of the 20 H. pylori strains tested three strains bound more than 50% of the vitronectin added, five strains bound 25–40%, nine strains bound 10–20% and three strains bound 5–8% vitronectin. Two strains, one with high- and one with low-binding properties, were selected for further characterization of ¹²⁵I-vitronectin binding. Binding to the urea-activated ¹²⁵I-labelled vitronectin was fast, saturable and reversible when an excess of unlabelled vitronectin was added to the bacteria with bound ¹²⁵I-vitronectin. The binding was heat- and protease-sensitive, suggesting that the binding was mediated by bacterial cell-surface proteins. Since components such as fetuin and orosomucoid but not asialofetuin inhibited the binding, sialic-acid specific proteins, related to H. pylori sialic-acid specific haemagglutinins, were probably involved.     

Physical and chemical characterization of a horse serum carboxylesterase

The serine carboxylesterase from horse serum was characterized by amino acid composition, peptide mapping, molecular and subunit weights, and sequencing of the amino acids around the essential serine residue at the active site. A protocol was developed for using reversed-phase high-performance liquid chromatography as the final step to obtain homogeneous preparations of horse serum carboxylesterase. Amounts sufficient for determining the amino acid composition and for peptide maps were obtained from a partially purified starting material which contained approximately 55% carboxylesterase. The amino acid composition, like the subunit weight (70,800 +/- 1400), was similar to the corresponding values reported for other serine carboxylesterases. However, the amino acid sequence of the tryptic digest fragment containing the essential nucleophilic seryl residue differed significantly from the corresponding sequences of other mammalian serine carboxylesterases.     

Use of procainamide gels in the purification of human and horse serum cholinesterases

Two large-scale methods based primarily on the use of procainamide-Sepharose gels were developed for the purification of horse and human serum non-specific cholinesterases. With method I, the procainamide-Sepharose 4B gel was used in the first step to handle large volumes of serum. With method II, the procainamide-Sepharose 4B gel was used in the final step to obtain pure enzyme. Although both methods gave electrophoretically pure cholinesterase preparations in good yields, they were significantly more efficient at purifying the horse enzyme than the human enzyme. To study this problem, the relative binding of human and horse cholinesterases to procainamide-, methylacridinium (MAC)-, m-trimethylammoniophenyl (m-PTA)- and p-trimethylammoniophenyl (p-PTA)-Sepharose 4B gels were measured, by using two approaches. In one, binding was measured by a procedure involving equilibration of pure cholinesterase in a small volume of diluted gel slurry (4%, v/v). A partially purified preparation of Electrophorus acetylcholinesterase was included. Pure human cholinesterase bound consistently more tightly to each of the gels than did horse cholinesterase, and the acetylcholinesterase appeared to bind the gels 10-100 times more tightly than did the non-specific cholinesterases. The order of binding for the cholinesterases, beginning with the tightest, was: procainamide-Sepharose 4B, MAC-Sepharose 4B, p-PTA-Sepharose 4B and m-PTA-Sepharose 4B. For the acetylcholinesterase the order was: MAC-Sepharose 4B, procainamide-Sepharose 4B, p-PTA-Sepharose 4B and m-PTA-Sepharose 4B. The second approach involved passing native sera or partially purified sera fractions through 1 ml test columns of each of the four affinity gels to determine their retention capacity for the cholinesterases. With these impure samples, the MAC-Sepharose 4B gels proved superior to the procainamide-Sepharose 4B gels at retaining human cholinesterase, but the opposite was true for the horse cholinesterase.     

Randomised controlled trial of lymphoblastoid interferon alfa in Europid men with chronic hepatitis B virus infection.

OBJECTIVE--To confirm the findings of pilot studies that interferon alfa is an effective treatment of Europid men with chronic hepatitis B virus infection. DESIGN--Randomised controlled trial of three months treatment with interferon alfa followed by 12 months of observation. SETTING--Outpatient clinic of a tertiary referral centre. PATIENTS--37 Treated men (six anti-HIV positive) and 34 untreated men (nine anti-HIV positive) who met the criteria for the trial. Four controls failed to complete follow up. INTERVENTIONS--The treated group received subcutaneous injections of 5-10 MU interferon alfa/m2 daily for five days, then 10 MU/m2 thrice weekly for 11 weeks. Follow up continued at monthly intervals for 12 months. Untreated controls were monitored over the same period. MAIN OUTCOME MEASURE--Hepatitis B e antigen and hepatitis B virus DNA state after 15 months of observation. RESULTS--12 Of the 37 treated patients cleared hepatitis B e antigen and hepatitis B virus DNA, whereas only one of 30 untreated controls seroconverted over the same period--an increased response rate of 29% (95% confidence interval 13% to 45%). The life table estimate of response at 15 months was 35% in treated patients, an increase of 32% above controls (95% confidence interval 16% to 48%). The response rates in groups by predictive pretreatment variables were 12 of 31 anti-HIV negative patients (excess response 34%; 95% confidence interval 14% to 54%), 12 of 26 with chronic active hepatitis before treatment (excess response 46%; 27% to 65%), and 12 of 21 with a pretreatment serum aspartate aminotransferase activity greater than 70 IU/l (excess response 46%; 16% to 76%). The combination of these factors predicted response with a sensitivity of 100% and a specificity of 80%. Four of the 12 responders, who had all been infected for less than two years, also lost hepatitis B surface antigen. Treatment was well tolerated. CONCLUSIONS--Interferon alfa is effective in the treatment of a proportion of Europid men with chronic hepatitis B virus infection, who might be identified before treatment. Additional strategies are required to improve the rate of response.     

Attraction between social crab spiders: silk pheromones in Diaea socialis

The snare web is used as a medium for communication betweenindividuals within colonies of social spiders and has thereforebeen suggested as necessary for the evolution of sociality inthe Araneae. The social spider Diaea socialis (Thomisidae) isan exception because it does not build a snare web. Experimentsdemonstrate that silk attracts all spiders and that a chemicaldeposited onto the silk attracts adult female spiders, suggestingthat the group living of this species is mediated by a pheromone.The pheromone attracts spiders differentially: females are notattracted to juvenile silk, and it repels gravid females. Thepheromone appears to be stable but volatile, is ether-soluble,and retains its viability after dissolution. Molecular-ionicmasses for 7-8 different compounds were found in the range 220–281atomic units; the pheromone may be one or a combination of severalof these.     

Antinuclear antibodies in patients receiving non-practolol beta-blockers.

Antinuclear antibodies (ANA) were found in 54 (7.0%) out of 767 treated hypertensive patients compared with 59 (2.4%) out of 2470 healthy controls. Inclusion of a non-practolol beta-blocker in the treatment regimen did not significantly affect the incidence of ANA. ANA was found in significantly more patients being treated with methyldopa (13.0%) than patients receiving other hypotensive agents (3.8%). Non-practolol beta-blockers in combination with methyldopa did not increase the incidence of ANA further.     

A subunit-sized butyrylcholinesterase present in high concentrations in pooled rabbit serum

A butyrylcholinesterase of mol.wt. approx. 83000 was observed in pooled rabbit serum. The enzyme was named monomeric butyrylcholinesterase to distinguish it from the larger oligomeric butyrylcholinesterase of horse and human serum whose subunits are the same size as the monomeric enzyme. The active-site concentration of monomeric butyrylcholinesterase in the pooled serum was 0.18mum, which is five times the concentration of butyrylcholinesterase in pooled horse serum. This was surprising, since the horse serum is regarded as a rich source of butyrylcholinesterase, whereas rabbit serum is not generally thought to contain significant amounts of any butyrylcholinesterase. The explanation, in large part, was the relatively low k(cat.) of the monomeric enzyme, which was approx. 57s(-1) with butyrylthiocholine as substrate and is one-thirtieth of the comparable k(cat.) of horse butyrylcholinesterase. The substrate specificity of monomeric butyrylcholinesterase also differed significantly from that of horse and human butyrylcholinesterase. For example, with the monomeric enzyme, the hydrolysis of 1mm-acetylthiocholine was only 4% the rate for 1mm-butyrylthiocholine, whereas human and horse butyrylcholinesterases hydrolysed 1mm-acetylthiocholine at 50% of the rate for 1mm-butyrylthiocholine. Moreover, monomeric butyrylcholinesterase generally hydrolysed aromatic esters more rapidly than choline esters, whereas the reverse is true of the butyrylcholinesterases. To facilitate the study of monomeric butyrylcholinesterase, it was separated from the larger butyrylcholinesterase and acetylcholinesterase, also present in rabbit serum, and purified 89-fold by fractionation with (NH(4))(2)SO(4) and ion-exchange chromatography.     

Decreased severity of potato common scab after foliar sprays of 3,5 -dichlorophenoxyacetic acid, a possible antipathogenic agent

Glasshouse tests on the potato cultivars Majestic and Maris Bard measured the effects of single early foliar sprays of ring-substituted phenoxyacetic acids (0.9 × 10–³ M) on the incidence of potato common scab, caused by soil-borne Streptomyces scabies. The most effective compound was 3,5-dichlorophenoxyacetic acid (3,5-D), which decreased scab by about 90%; its action was preventative, early sprays being more effective than late However, it slightly decreased yield, and increased the number of tubers per plant and the proportion of deformed tubers. The trichloro- and tetrachloro- acids containing the 3,5-dichloro- group also decreased scab, though to lesser extents; the most active of these was the 2,3,4,5-tetrachloro- acid, which had the same side effects as 3,5-D. The herbicide 2,4-D almost halved scab incidence, but seriously decreased yield. Other acids tested had little or no effect on scab. In tests against S. scabies in culture, 3,5-D was no more toxic than other disubstituted acids which were inactive, or weakly active, against the disease in vivo. 3,5-D may be an ‘antipathogenic agent’, preventing scab development by altering tuber metabolism.