Observations on Fission, Maturation and Reproduction in Dugesia biblica (Turbellaria, Tricladida) from Israel

Laboratory studies on the normally fissiparous Dugesia biblica from Israel (3 n =27+ x supernumeraries) have been made in order to investigate fission rates and spontaneous maturation of four fissioning populations and one clone. Laboratory induced maturation in a sixth population of D. biblica resulted in the laying of fertile cocoons, the offspring of which were either 3 n =27+ x , 2 n = 18+ x or 2 n = 18+ x It is suggested that triploidy is primarily responsible for the lack of sexual reproduction in the field, and that unequal inheritance of supernumerary chromosomes during mitosis may explain the differing tendencies to undergo spontaneous maturation by individuals of a clone of D. biblica. The karyotype, habitat and reproduction of D. biblica is compared with a closely related but diploid, normally sexually reproducing Dugesia form and possible relationships between these two are discussed.     

Monitoring exposure to avian influenza viruses in wild mammals

• 1 Avian influenza (AI) viruses primarily circulate in wild waterfowl populations and are occasionally transmitted to domestic poultry flocks. However, the possible roles of other wildlife species, such as wild mammals, in AI virus ecology have not been adequately addressed.
• 2 Due to their habitat and behaviour, many wild mammals may be capable of transmitting pathogens among wild and domestic populations. Exposure to AI viruses has been reported in an array of wild and domestic animals. The presence of wild mammals on farms has been identified as a risk factor for at least one poultry AI outbreak in North America. These reports suggest the need for seroprevalence studies examining the exposure of wild mammals to AI viruses.
• 3 Serological tests are routinely used to assess domestic poultry, domestic swine and human exposure to influenza A viruses, but these tests have not been validated for use in wild mammals. As such, some of these protocols may require adjustments or may be inappropriate for use in serology testing of wild mammals. Herein, we review these serological techniques and evaluate their potential usefulness in AI surveillance of wild mammals. We call for care to be taken when applying serological tests outside their original area of validation, and for continued assay verification for multiple species and virus strains.

     

The effect of shade on leaf structure and physiology of tree seedlings from a mixed dipterocarp forest

This study builds upon past work investigating seedling leaf physiology and structure among tropical trees. We seek to explain how related and unrelated species and genera co‐occur in relation to varying amounts of shade. Seedlings of eight Sri Lankan rain forest tree species in three genera (Dipterocarpus, Mesua, Shorea section Doona) were grown for 2 years in four treatments that simulated a variety of shade environments across the understorey of a rain forest. All three genera comprise major canopy tree species of mixed dipterocarp forest, a widespread and important Asian tropical forest type. Compared with the other genera, Dipterocarpus spp. had the largest leaves, the thinnest leaf blades and relatively high rates of stomatal conductivity across all shade treatments, making them water‐loving species sensitive to droughty soils. Mesua spp. had intermediate sized leaves, with the thickest leaf blades and palisade mesophyll layers, the highest stomatal densities, the smallest aperture sizes and the lowest rates of stomatal conductance, making them the most water conservative. Shorea spp. were generally intermediate in blade and palisade mesophyll dimensions between Dipterocarpus spp. and Mesua spp., but they had the smallest leaves. Greater differences among genera than among species within genera were apparent, but species differences within genera were also apparent. Differences among genera and species conform to their known successional status and topographical affinities and provide a more comprehensive understanding of species site adaptation. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 332–343.     

PRIMER NOTE. Using the incomplete genome of the ectomycorrhizal fungus Amanita bisporigera to identify molecular polymorphisms in the related Amanita phalloides

We describe the cross‐genomic isolation of 13 single nucleotide polymorphisms (SNPs) and one variable microsatellite from five loci for the death cap mushroom Amanita phalloides. Microsatellite repeats were identified by searching the partial Amanita bisporigera genome. Flanking primers were designed for 25 of these microsatellite loci and tested for cross‐amplification in A. phalloides. One locus contained an interrupted, compound microsatellite, and four loci contained one to six SNPs. These results demonstrate the usefulness of even an incomplete genome to identify molecular markers for population studies in nonmodel organisms.     

Contrasting landscape epidemiology of two sympatric rabies virus strains

Viral strain evolution and disease emergence are influenced by anthropogenic change to the environment. We investigated viral characteristics, host ecology, and landscape features in the rabies‐striped skunk disease system of the central Great Plains to determine how these factors interact to influence disease emergence. We amplified portions of the N and G genes of rabies viral RNA from 269 samples extracted from striped skunk brains throughout the distribution of two different rabies strains for which striped skunks were the reservoir. Because the distribution of these two strains overlapped on the landscape and were present in the same host population, we could evaluate how viral properties influenced epidemiological patterns in the area of sympatry. We found that South Central Skunk rabies (SCSK) exhibited intense purifying selection and high infectivity, which are both characteristics of an epizootic virus. Conversely, North Central Skunk rabies (NCSK) exhibited relaxed purifying selection and comparatively lower infectivity, suggesting the presence of an enzootic virus. The host population in the area of sympatry was highly admixed, and skunks among allopatric and sympatric areas had similar effective population sizes. Spatial analysis indicated that landscape features had minimal influence on NCSK movement across the landscape, but those same features were partial barriers to the spread of SCSK. We conclude that NCSK and SCSK have different epidemiological properties that interact differently with both host and landscape features to influence rabies spread in the central Great Plains. We suggest a holistic approach for future studies of emerging infectious diseases that includes studies of viral properties, host characteristics, and spatial features.