Threatened and Endangered Subspecies with Vulnerable Ecological Traits Also Have High Susceptibility to Sea Level Rise and Habitat Fragmentation

The presence of multiple interacting threats to biodiversity and the increasing rate of species extinction make it critical to prioritize management efforts on species and communities that maximize conservation success. We implemented a multi-step approach that coupled vulnerability assessments evaluating threats to Florida taxa such as climate change, sea-level rise, and habitat fragmentation with in-depth literature surveys of taxon-specific ecological traits. The vulnerability, adaptive capacity, and ecological traits of 12 threatened and endangered subspecies were compared to non-listed subspecies of the same parent species. Overall, the threatened and endangered subspecies showed high vulnerability and low adaptive capacity, in particular to sea level rise and habitat fragmentation. They also exhibited larger home ranges and greater dispersal limitation compared to non-endangered subspecies, which may inhibit their ability to track changing climate in fragmented landscapes. There was evidence for lower reproductive capacity in some of the threatened or endangered taxa, but not for most. Taxa located in the Florida Keys or in other low coastal areas were most vulnerable to sea level rise, and also showed low levels of adaptive capacity, indicating they may have a lower probability of conservation success. Our analysis of at-risk subspecies and closely related non-endangered subspecies demonstrates that ecological traits help to explain observed differences in vulnerability and adaptive capacity. This study points to the importance of assessing the relative contributions of multiple threats and evaluating conservation value at the species (or subspecies) level when resources are limited and several factors affect conservation success.     

Three-Dimensional Analysis of the Swimming Behavior of Daphnia magna Exposed to Nanosized Titanium Dioxide

Due to their surface characteristics, nanosized titanium dioxide particles (nTiO₂) tend to adhere to biological surfaces and we thus hypothesize that they may alter the swimming performance and behavior of motile aquatic organisms. However, no suitable approaches to address these impairments in swimming behavior as a result of nanoparticle exposure are available. Water fleas Daphnia magna exposed to 5 and 20 mg/L nTiO₂ (61 nm; polydispersity index: 0.157 in 17.46 mg/L stock suspension) for 96 h showed a significantly (p<0.05) reduced growth rate compared to a 1-mg/L treatment and the control. Using three-dimensional video observations of swimming trajectories, we observed a treatment-dependent swarming of D. magna in the center of the test vessels during the initial phase of the exposure period. Ensemble mean swimming velocities increased with increasing body length of D. magna, but were significantly reduced in comparison to the control in all treatments after 96 h of exposure. Spectral analysis of swimming velocities revealed that high-frequency variance, which we consider as a measure of swimming activity, was significantly reduced in the 5- and 20-mg/L treatments. The results highlight the potential of detailed swimming analysis of D. magna for the evaluation of sub-lethal mechanical stress mechanisms resulting from biological surface coating and thus for evaluating the effects of nanoparticles in the aquatic environment.     

The many roles of small RNAs in leaf development

Leaf development involves many complex genetic interactions,signals between adjacent cells or between more distant tissues and consequent changes in cell fate.This review describes three stages in leaf development where regulation by small RNAs have been used to modulate gene expression patterns.     

A checklist for ecological management of landscapes for conservation

The management of landscapes for biological conservation and ecologically sustainable natural resource use are crucial global issues. Research for over two decades has resulted in a large literature, yet there is little consensus on the applicability or even the existence of general principles or broad considerations that could guide landscape conservation. We assess six major themes in the ecology and conservation of landscapes. We identify 13 important issues that need to be considered in developing approaches to landscape conservation. They include recognizing the importance of landscape mosaics (including the integration of terrestrial and aquatic areas), recognizing interactions between vegetation cover and vegetation configuration, using an appropriate landscape conceptual model, maintaining the capacity to recover from disturbance and managing landscapes in an adaptive framework. These considerations are influenced by landscape context, species assemblages and management goals and do not translate directly into on-the-ground management guidelines but they should be recognized by researchers and resource managers when developing guidelines for specific cases. Two crucial overarching issues are: (i) a clearly articulated vision for landscape conservation and (ii) quantifiable objectives that offer unambiguous signposts for measuring progress.     

Noradrenaline as a putative neurotransmitter mediating hypotension—induced FOs—like immunoreactivity in the supraoptic nucleus of the rat

Hemorrhage or hypotension induces extensive Fos-like immunoreactivity in the magnocellular neurosecretory cells in the supraoptic nucleus of the hypothalamus in rat,especially in the vasopressin neurons.The present study was to explore the neurotransmitter mediating this effect,Microinfusion of the alpha-adrenergic blocker into the supraoptic nucleus reduced the hypotension-induced FOs.whereas beta-antagonist did not affect it significantly.Alaha1-and alpha2-antagonist,prazosin and yohimbine,both reduced the Fos-Positive cell counts.However,the effective dosage of yohimbine was much larger,Alpha1-agonist,methoxamine,induced abundant Fos-like immunoreactivity in the vasopressin cells in this nucleus,while beta-and alpha2-agonist did not elicit such effect.Administration of the noradrenergic re-uptake inhibitor desipramine,to this nucleus to locally accumulate the spontaneously released noradrenaline from the nerve terminals also induced Fos expression,mostly in the vasopressin cells.     

Anti-HLA immunization following transfusions of leukocyte-poor blood

We have followed the evolution of leucocyte antibodies in patients receiving multiple blood transfusions of leucocyte-poor blood. The number of leucocytes present in one unit of transfused blood was always less than 1 X 10(8). We observed that such preparations were able to re-stimulate antibodies which had disappeared, but especially they were able to provoke a first immunisation in some patients never immunized in the past. The specificities of these antibodies corresponded to one or several antigens present in the donor of the transfused unit. This study shows that leucocyte immunisation cannot always be avoided in spite of the selection of blood products containing very few white cells.     

A model of dengue fever

Background  

Dengue is a disease which is now endemic in more than 100 countries of Africa, America, Asia and the Western Pacific. It is transmitted to the man by mosquitoes (Aedes) and exists in two forms: Dengue Fever and Dengue Haemorrhagic Fever. The disease can be contracted by one of the four different viruses. Moreover, immunity is acquired only to the serotype contracted and a contact with a second serotype becomes more dangerous.     

Hydromorphologic Sorting of In-Stream Nitrogen Uptake Across Spatial Scales

Ecosystems - Nitrogen (N) uptake is a key process in stream ecosystems that is mediated mainly by benthic microorganisms (biofilms on different substrata) and has implications for the...     

Disinfecting capabilities of oxychlorine compounds.

The bacterial virus f2 was inactivated by chlorine dioxide at acidic, neutral, and alkaline pH values. The rate of inactivation increased with increasing pH. Chlorine dioxide disproportionation products, chlorite and chlorate, were not active disinfectants. As chlorine dioxide solutions were degraded under alkaline conditions, they displayed reduced viricidal effectiveness, thereby confirming the chlorine dioxide free radical as the active disinfecting species.