A longitudinal study of age‐related changes in Haemoproteus infection in a passerine bird

Blood parasites such as malaria and related haemosporidians commonly infect vertebrate species including birds. Understanding age‐specific patterns of parasite infections is crucial for quantifying the fitness consequences of parasitism for hosts and for understanding parasite transmission dynamics. We analyzed longitudinal and cross‐sectional infection data in house martins Delichon urbica, a migratory bird suffering from intense haemosporidian infection. We separated within‐ from among‐individual effects of age on prevalence. Our results showed that the probability of blood parasite infection increased as individual house martins aged. We also showed that the prevalence of infection decreased with age at last reproduction when controlling for age, showing a selective disappearance of infected birds from the population (i.e. selection). The estimated effect of age on prevalence was underestimated two‐ to three‐fold if not accounting for such selection. This study highlights the importance of taking among‐individual heterogeneity in the capacity to fight a disease into account because such heterogeneity can mask age‐related patterns of infection. These findings emphasize the relevance of considering within‐ and among‐individual patterns of infection in order to understand parasite‐induced mortality and the potential for parasite transmission.     

Maternal plasma pyridoxal-5'-phosphate concentrations and risk of isolated oral clefts in the Philippines

BACKGROUND: We report that inadequate vitamin B-6 status of Filipino mothers, assessed by erythrocyte aspartate aminotransferase activity coefficient (EAST-AC), is associated with an increased risk for isolated cleft lip with or without cleft palate (CL/P) in their children. Its association with the status assessed by plasma pyridoxal-5'-phosphate (PLP) concentrations is unknown. METHODS: In a case-control study in the Philippines including 46 cases (mothers of a child with CL/P) and 392 controls (mothers of an unaffected child), we evaluated the association between the risk for CL/P and maternal vitamin B-6 status assessed by PLP and EAST-AC. RESULTS: The ORs of CL/P were estimated by classifying mothers by PLP (>30, 20-30, and <20 nmol/L). Using the highest PLP group as the reference, ORs (95% CIs) were 1.03 (0.45-2.37) and 2.66 (1.30-5.50) for the middle and lowest groups, respectively (p trend = .01). In multivariate models controlling for various covariates including folate, the risk for CL/P was approximately 12 times higher in mothers with inadequate vitamin B-6 status, assessed by both PLP and EAST-AC values, compared to those with adequate status by both values. CONCLUSIONS: Inadequate vitamin B-6 status assessed by maternal PLP and EAST-AC values independently and both combined was associated with an increased risk for CL/P. The association was highest when both values were considered, suggesting that the measurement of both PLP and EAST-AC provides better assessment of vitamin B-6 status than either measurement alone.     

Communication via sex pheromones within and among Arrenurus spp. mites (Acari: Hydrachnida; Arrenuridae)

We present direct experimental evidence of pheromone use in six species of Arrenurus and indirect evidence for four species, including members of the subgenera Megaluracarus, Truncaturus, and Arrenurus. Water in which females were housed elicited arrestant behaviour in males, males oriented to the source, and at least some individuals in each species assumed the male readiness posture, a precursor to coupling. Most species responded to water treated with conspecific females, but there was also interspecific sex pheromone responsiveness. Arrenurus manubriator and A. megalurus demonstrated reciprocal pheromone cross-attractancy. Males of A. major, A. marshallae, and A. birgei responded to water from females of related species from within their subgenera. Arrenurus apetiolatus males failed to respond to conspecific female-treated water, but the same water elicited arrestant behaviour and orientation in A. manubriator. Heterospecific reactions to female-conditioned water were limited to cases involving members of the same species group and were not seen between species representing different species groups or different subgenera. The species for which cross-attractancy has been demonstrated commonly co-occur in nature, so apparently these pheromones are of limited value for species recognition. Shared reaction to sex pheromones provides additional evidence for inferring close phylogenetic relationship among species, and thus far, corresponds with morphological evidence based on adult males and larvae.     

Sex of incubation neighbours influences hatchling sexual phenotypes in an oviparous lizard

In many litter-bearing mammals and in a few viviparous reptiles the sex ratio of the entire brood or the sex of the adjacent fetuses induces sex-specific differences in the hatchling’s phenotype. This study examines whether the sex of incubation neighbours affects hatchling characteristics in oviparous common lizards (Lacerta vivipara). Oviparous common lizards lay eggs with thin eggshells and, therefore, are an optimal model organism for studying the effects of hormone leakage among developing embryos since the strongest evidence for prenatal sex ratio effects on offspring development comes from viviparous populations of the same species. Groups of three eggs were incubated together and were categorised according to the sex of the resulting hatchlings as either homosex (three hatchlings of the same sex) or heterosex (one male or one female hatchling plus two siblings of the opposite sex). Hatchlings incubated adjacent to siblings of the same sex had larger body mass and body condition. Males tended to have lower ventral scale counts when incubated with other males. Conversely, females tended to have more ventral scales when incubated with other females, indicative of a more feminised phenotype. There was also a significant interaction between hatchling sex and incubation environment with respect to the length of the fourth digit of the hindlimb, likely indicative of masculinisation in heterosex females. This study suggests steroid diffusion between adjacent eggs in a minimally manipulative experiment and provides the first evidence for developmental effects of the exogenous hormonal environment in near natural conditions in an oviparous amniote. Implications of these results for the evolution of within-clutch sex ratio are discussed.     

An elderly man with cholestatic jaundice due to biliary hydatidosis

Hydatid disease is found throughout the world, with a higher prevalence in the Mediterranean area. In Spain, the most endemic regions are Rioja and Aragon, with rates above 10 cases/100,000 inhabitants, followed by Castilla-La Mancha and Castilla y Leon (5-10 cases/100,000 inhabitants). This parasitic disease is caused by the larval stage of Echinococcus granulosus (EG) and the main organs affected are the liver and the lung (85 % cases). We present a case of obstructive jaundice and secondary cholangitis due to a biliary hydatidosis. Abdominal computed tomography scan showed dilatation of the entire biliary tract. The technique used for diagnosis and treatment was endoscopic retrograde cholangiopancreatography.