Analyzing the Impacts of Dams on Riparian Ecosystems: A Review of Research Strategies and Their Relevance to the Snake River Through Hells Canyon

River damming provides a dominant human impact on river environments worldwide, and while local impacts of reservoir flooding are immediate, subsequent ecological impacts downstream can be extensive. In this article, we assess seven research strategies for analyzing the impacts of dams and river flow regulation on riparian ecosystems. These include spatial comparisons of (1) upstream versus downstream reaches, (2) progressive downstream patterns, or (3) the dammed river versus an adjacent free-flowing or differently regulated river(s). Temporal comparisons consider (4) pre- versus post-dam, or (5) sequential post-dam conditions. However, spatial comparisons are complicated by the fact that dams are not randomly located, and temporal comparisons are commonly limited by sparse historic information. As a result, comparative approaches are often correlative and vulnerable to confounding factors. To complement these analyses, (6) flow or sediment modifications can be implemented to test causal associations. Finally, (7) process-based modeling represents a predictive approach incorporating hydrogeomorphic processes and their biological consequences. In a case study of Hells Canyon, the upstream versus downstream comparison is confounded by a dramatic geomorphic transition. Comparison of the multiple reaches below the dams should be useful, and the comparison of Snake River with the adjacent free-flowing Salmon River may provide the strongest spatial comparison. A pre- versus post-dam comparison would provide the most direct study approach, but pre-dam information is limited to historic reports and archival photographs. We conclude that multiple study approaches are essential to provide confident interpretations of ecological impacts downstream from dams, and propose a comprehensive study for Hells Canyon that integrates multiple research strategies

Experimental Models of Glioma

The development and refinement of animal models of gliomagenesis has been fundamental to test hypotheses concerning the aetiology of gliomas and their molecular and cellular pathogenesis. During the last few decades, modeling has gained in complexity and is nowadays mostly relying on the cell type-specific modulation of the expression of candidate oncogenes and oncosup-pressors. Despite such technological advances, the recent appreciation of the molecular heterogeneity underlying human high-grade glioma variability re-vealed the need for a deeper characterization of the available models. It is now clear that most of the existing animal systems mimic one of the human molecular classes, known as "proneural", leaving the other groups un-derrepresented. While there is thus the need for an expansion of the range of available models, existing ones have already proven useful as translational research platforms, allowing preliminary assessment of the efficacy of classi-cal and innovative therapeutic approaches. In this contribution, we provide a general view of the field and synthesize our understanding of the biology of the most thoroughly studied model family, that of PDGF-induced gliomas

Environmental influences on the composition and structure of the freshwater mussels in shallow lakes in the Cuiabá River floodplain

The maintenance of the freshwater mussels' community in lakes is determined by abiotic factors at the local scale and at regional scale by interspecific relations between the larvae of bivalves and fish host. Whereas the distribution pattern at local scale, our goal was to understand the abundance and community composition of bivalves and relate the environmental agents structuring this community. We sampled 20 lakes in the floodplain of the Cuiabá River using a standardized method of sampling. To evaluate the effect of environment on the community we applied multivariate inferential analyses. We found 1.143 individuals alive belonging into six species distributed at the family Hyriidae, Mycetopodidae, Sphaeridae and Corbiculidae. The results showed that in the Pantanal the bivalve assemblage structure is influenced locally by organic matter and particle size, variables that reflect the intense interactions between water-sediment. However it is important to emphasize that these environmental characteristics are the result of the dynamics of this system which is dependent on the flood pulse, a regional factor