Extensive fusion of haematopoietic cells with Purkinje neurons in response to chronic inflammation

Transplanted bone marrow-derived cells (BMDCs) have been reported to fuse with cells of diverse tissues, but the extremely low frequency of fusion has led to the view that such events are biologically insignificant. Nonetheless, in mice with a lethal recessive liver disease (tyrosinaemia), transplantation of wild-type BMDCs restored liver function by cell fusion and prevented death, indicating that cell fusion can have beneficial effects. Here we report that chronic inflammation resulting from severe dermatitis or autoimmune encephalitis leads to robust fusion of BMDCs with Purkinje neurons and formation of hundreds of binucleate heterokaryons per cerebellum, a 10-100-fold higher frequency than previously reported. Single haematopoietic stem-cell transplants showed that the fusogenic cell is from the haematopoietic lineage and parabiosis experiments revealed that fusion can occur without irradiation. Transplantation of rat bone marrow into mice led to activation of dormant rat Purkinje neuron-specific genes in BMDC nuclei after fusion with mouse Purkinje neurons, consistent with nuclear reprogramming. The precise neurological role of these heterokaryons awaits elucidation, but their frequency in brain after inflammation is clearly much higher than previously appreciated.     

Peanut gene expression profiling in developing seeds at different reproduction stages during <Emphasis Type="Italic">Aspergillus parasiticus</Emphasis>infection

Background  

Peanut (Arachis hypogaea L.) is an important crop economically and nutritionally, and is one of the most susceptible host crops to colonization of Aspergillus parasiticus and subsequent aflatoxin contamination. Knowledge from molecular genetic studies could help to devise strategies in alleviating this problem; however, few peanut DNA sequences are available in the public database. In order to understand the molecular basis of host resistance to aflatoxin contamination, a large-scale project was conducted to generate expressed sequence tags (ESTs) from developing seeds to identify resistance-related genes involved in defense response against Aspergillus infection and subsequent aflatoxin contamination.     

Species distribution and <Emphasis Type="Italic">in vitro</Emphasis> antifungal susceptibility of oral yeast isolates from Tanzanian HIV-infected patients with primary and recurrent oropharyngeal candidiasis

Background  

In Tanzania, little is known on the species distribution and antifungal susceptibility profiles of yeast isolates from HIV-infected patients with primary and recurrent oropharyngeal candidiasis.     

Mutualism can mediate competition and promote coexistence

Mutualistic interactions are not believed to promote coexistence of competitors because mutualisms produce positive feedbacks on abundances whereas coexistence requires negative feedbacks. Here we show that a mutualism between an anemonefish (Amphiprion) and its sea anemone host mediates the effect of asymmetrical competition for space between the anemonefish and another damselfish (Dascyllus) in a manner that fosters their coexistence. Amphiprion stimulates increases in host area, the shared resource, but social interactions cap the number of anemonefish to two adults per host. Space generated by the mutualism becomes differentially available to Dascyllus because the effectiveness of an anemonefish in excluding its competitor declines with increases in the area it defends. This alters Amphiprion's ratio of per capita intra‐ to interspecific effects and thus facilitates coexistence of the fishes. This mechanism may be prevalent in nature, adding another major pathway by which mutualism can enhance diversity.     

A role for the 30S subunit E site in maintenance of the translational reading frame

The exit (E) site has been implicated in several ribosomal activities, including translocation, decoding, and maintenance of the translational reading frame. Here, we target the 30S subunit E site by introducing a deletion in rpsG that truncates the β-hairpin of ribosomal protein S7. This mutation (S7ΔR77–Y84) increases both −1 and +1 frameshifting but does not increase miscoding, providing evidence that the 30S E site plays a specific role in frame maintenance. Mutation S7ΔR77–Y84 also stimulates +1 programmed frameshifting during prfB′-lacZ translation in many synthetic contexts. However, no effect is seen when the E codon of the frameshift site corresponds to those found in nature, suggesting that E-tRNA release does not normally limit the rate of prfB frameshifting. Ribosomes containing S7ΔR77–Y84 exhibit an elevated rate of spontaneous reverse translocation and an increased K_1/2 for E-tRNA. These effects are of similar magnitude, suggesting that both result from destabilization of E-tRNA. Finally, this mutation of the 30S E site does not inhibit EF-G-dependent translocation, consistent with a primary role for the 50S E site in the mechanism.     

Isolation and characterization of 13 polymorphic nuclear microsatellite primers for the widespread Indo-Pacific three-spot damselfish, Dascyllus trimaculatus, and closely related D. auripinnis

A set of 13 simple sequence repeat markers was developed from D. trimaculatus genomic DNA, tested for D. auripinnis and characterized using 40 individuals per species. All the loci were polymorphic with a number of alleles ranging from three to 30. Observed heterozygosities varied from 0.23 to 0.89 for D. trimaculatus and from 0.11 to 0.85 for D. auripinnis. Early results show that these will be powerful markers for the study of ecological and evolutionary mechanism in this coral reef fish species complex.     

VIPR: A probabilistic algorithm for analysis of microbial detection microarrays

Background  

All infectious disease oriented clinical diagnostic assays in use today focus on detecting the presence of a single, well defined target agent or a set of agents. In recent years, microarray-based diagnostics have been developed that greatly facilitate the highly parallel detection of multiple microbes that may be present in a given clinical specimen. While several algorithms have been described for interpretation of diagnostic microarrays, none of the existing approaches is capable of incorporating training data generated from positive control samples to improve performance.     

Home Range and Movement Patterns of Toucans: Implications for Seed Dispersal

Toucans (Ramphastidae) are highly frugivorous, widespread throughout the Neotropics, and travel long distances, thus likely providing dispersal for many tropical trees. Despite being large conspicuous members of the canopy and subcanopy bird community, their movement ecology has been little studied. To understand how these frugivores move through a lowland tropical forest, I tracked the movements of Ramphastos tucanus (White‐throated Toucan), Ramphastos vitellinus (Channel‐billed Toucan), and Pteroglossus pluricinctus (Many‐banded Araçari) in Yasuní National Park, Ecuador. The objectives of this study were to use radiotelemetry to estimate toucan home ranges, movement patterns, and potential seed dispersal distances. Using canopy nets, a total of 20 P. pluricinctus and three Ramphastos toucans were captured, radio‐tagged, and tracked over a 4‐yr period from 2001 to 2005. Average home range sizes were 191 and 86 ha for P. pluricinctus and Ramphastos toucans, respectively. The maximum travel distance in a single 30‐min tracking interval was 3665 m for P. pluricinctus and 3027 m for Ramphastos. Estimated dispersal distances of medium‐sized seeds ranged from 269 to 449 m. Large home range size and long‐distance movements indicate that toucans likely disperse seeds over a scale of hundreds of meters. This study is the first to estimate home range size of any toucan species in intact closed‐canopy forests. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Fish communities on staghorn coral: effects of habitat characteristics and resident farmerfishes

Branching corals, like many in the genus Acropora, provide structurally complex habitats for reef fishes and other organisms. Fluctuations in the abundance, distribution and characteristics of thicket-forming staghorn Acroporids may contribute to changes in the abundance and species composition of reef fishes due to changes in the availability of shelter habitat and food. Farming damselfishes of the genus Stegastes can occur in high abundances in staghorn corals and actively defend food and nest space against organisms that threaten these resources. Here we assess the value of staghorn as habitat for fishes in the central South Pacific, and how the presence of territorial farming damselfishes may influence the assemblage of fishes that associate with staghorn corals. Surveys of 185 Acropora pulchra patches located in the lagoons surrounding the island of Moorea, French Polynesia revealed 85 species of fish from 25 families. Total fish abundance and species richness values ranged from no fish on a patch to a high of 275 individuals and 26 species. Patch area was the most important characteristic in explaining variation in attributes of the fish assemblage, with other characteristics explaining little of the species composition or trophic structure. Behavioral observations revealed that farming damselfishes were most aggressive toward corallivores, herbivores, and egg predators, while they ignored most carnivores and omnivores. Despite this pattern, we observed positive covariance between Stegastes and the group of fishes that elicited the strongest aggressive response when the effect of patch area was removed, suggesting these fishes remain drawn to the resources produced or enhanced by Stegastes on A. pulchra.