The formation of titan cells in Cryptococcus neoformans depends on the mouse strain and correlates with induction of Th2‐type responses

Cryptococcus neoformans is a pathogenic yeast that can form titan cells in the lungs, which are fungal cells of abnormal enlarged size. Little is known about the factors that trigger titan cells. In particular, it is not known how the host environment influences this transition. In this work, we describe the formation of titan cells in two mouse strains, CD1 and C57BL/6J. We found that the proportion of C. neoformans titan cells was significantly higher in C57BL/6J mice than in CD1. This higher proportion of titan cells was associated with a higher dissemination of the yeasts to the brain. Histology sections demonstrated eosinophilia in infected animals, although it was significantly lower in the CD1 mice which presented infiltration of lymphocytes. Both mouse strains presented infiltration of granulocytes, but the amount of eosinophils was higher in C57BL/6J. CD1 mice showed a significant accumulation of IFN‐γ, TNF‐α and IL17, while C57BL/BL mice had an increase in the anti‐inflammatory cytokine IL‐4. IgM antibodies to the polysaccharide capsule and total IgE were more abundant in the sera from C57BL/6J, confirming that these animals present a Th2‐type response. We conclude that titan cell formation in C. neoformans depends, not only on microbe factors, but also on the host environment.     

Behavioral response of manatees to variations in environmental sound levels

Florida manatees (Trichechus manatus latirostris) inhabit coastal regions because they feed on the aquatic vegetation that grows in shallow waters, which are the same areas where human activities are greatest. Noise produced from anthropogenic and natural sources has the potential to affect these animals by eliciting responses ranging from mild behavioral changes to extreme aversion. Sound levels were calculated from recordings made throughout behavioral observation periods. An information theoretic approach was used to investigate the relationship between behavior patterns and sound level. Results indicated that elevated sound levels affect manatee activity and are a function of behavioral state. The proportion of time manatees spent feeding and milling changed in response to sound level. When ambient sound levels were highest, more time was spent in the directed, goal‐oriented behavior of feeding, whereas less time was spent engaged in undirected behavior such as milling. This work illustrates how shifts in activity of individual manatees may be useful parameters for identifying impacts of noise on manatees and might inform population level effects.     

Environmental control and spatial structures in peatland vegetation

Question: What are the relative influences of environment and space in structuring the plant composition in a peatland complex? Location: Lakkasuo, southern boreal zone, Finland. Method: We used principal coordinates of neighbour matrices (PCNM) to model spatial structures in the plant composition of a peatland complex comprising ombrotrophic and minerotrophic, open and forested areas. We used redundancy analyses (RDA) and variation partitioning to assess the relative influences of chemical variables (peat and water characteristics), physical variables (hydrology, soil properties, shade), as well as broad‐scale (>350 m) and medium‐scale (100–350 m) spatial structures on vegetation assemblages. Results: We identified five different significant spatial patterns circumscribing (1) the minerotrophic–ombrotrophic gradient; (2) dry ombrotrophic and wet minerotrophic areas; (3) open and shaded areas; (4) dry open/shaded and wet patches within the ombrotrophic areas; and (5) dry open patches and dry forested patches. With spatial structures and environmental variables, we were able to model 30% of the variability in plant composition in the peatland complex, 13% of which was attributable to spatial structures alone. Conclusions: We demonstrated that in the peatland complex, the spatial dependence processes were more important at the broadest scale, and found that patterns at a medium scale might reflect finer‐scale patterns that were not investigated here. Spatial autocorrelation in vegetation composition in the peatland complex appeared to be driven by Sphagnum species. Our results emphasize that spatial modelling should be routinely implemented in studies looking at species composition, since they significantly increase the explained proportion of variance.     

Patterns of early succession on bare peat in a Swiss mire after a bog burst

Questions: How does plant diversity (species richness, species abundance and rate of change) evolve in early succession on bare peat? Does succession converge towards one equilibrium stage or end up in several stages? Is there a regular pattern in succession velocity? Location: A mire in the calcareous Jura Mountains of northwest Switzerland. Method: Twenty‐one 1‐m² permanent plots on bare peat were used to monitor temporal stages over a 21‐year period (1988 to 2008) in a Swiss mire where a slide occurred in 1987. Species diversity and life forms were analysed based on Shannon's equitability index and cover. We used classification and metric ordination techniques to investigate patterns of successional rates and trends. The high temporal resolution of the survey allowed the pattern of succession velocity to be analysed. Results: Species richness increased continuously over the 21 years of succession. The highest cover throughout the study period was the life form sedge. Time trajectories of the 21 plots revealed three alternative pathways towards intermediate equilibrium stages in the first years, still not converging in the later stages. Changes in succession velocity reached a first maximum about 6 years after the slide had occurred and a second maximum 12 years later.     

Wolbachia in field populations of Forcipomyia taiwana (Diptera: Ceratopogonidae) in Taiwan

Wolbachia pipientis is an endosymbiotic alpha-proteobacterium that is found in numerous insects and arthropods. Only a few studies have been made on Wolbachia in blood-sucking midges. In this study, we identified and determined the molecular characteristics of Wolbachia strains in Forcipomyia taiwana (Shiraki), a blood-sucking midge found in Taiwan and southern China. Our results indicate that all F. taiwana individuals captured in Nantou County, Taiwan were infected with Wolbachia strains closely related to the A-supergroup wAlbA. Moreover, 2 individuals captured at low-abundance locations were also infected with a B-supergroup Wolbachia strain. We observed that 63% F. taiwana individuals captured at the low-abundance locations harbored the wAlbA-like strain which has a particular substitution pattern (D51G, T84A, and A85V) in the Wolbachia surface protein. Taken together, our results indicate that distinct Wolbachia strains exist in F. taiwana populations in the field.     

化学杂交剂对灌浆期小麦源流库的影响

以大穗小麦品种SN05-3和多穗小麦SN02-3为试验材料,研究了化学杂交剂BAU-9403对灌浆期小麦库、源、流的影响.结果表明,BAU-9403诱导的小麦雄性不育率大于95%,异交结实率高于92.5%;BAU-9403能够显著降低旗叶叶绿素含量和提高其净光合速率;喷药处理的干物质日生产量,茎、叶、鞘的干物质转移量及其输出率和转换率均下降;喷药处理籽粒饱满度平均减少0.222,平均灌浆速率降低0.306g/1000 grains·d-1,灌浆持续期平均缩短6.03d.BAU-9403处理的SN05-3净光合速率增加幅度、叶绿素含量及茎中干物质转移量、输出率和转换率下降幅度均高于SN02-3,而叶中干物质转移量下降幅度和鞘中的干物质输出率却低于SN02-3;SN05-3的灌浆持续期缩短幅度明显大于SN02-3,而其灌浆速率下降的程度小于SN02-3.综合分析表明,BAU-9403能够影响灌浆期小麦的光合生理特性,破坏库、源之间的平衡关系,使干物质积累和转运不畅,导致粒重下降,且品种间的反应存在差异.