Effects of size and temperature on metabolic rate

We derive a general model, based on principles of biochemical kinetics and allometry, that characterizes the effects of temperature and body mass on metabolic rate. The model fits metabolic rates of microbes, ectotherms, endotherms (including those in hibernation), and plants in temperatures ranging from 0 degrees to 40 degrees C. Mass- and temperature-compensated resting metabolic rates of all organisms are similar: The lowest (for unicellular organisms and plants) is separated from the highest (for endothermic vertebrates) by a factor of about 20. Temperature and body size are primary determinants of biological time and ecological roles.     

Forms of memory failure

Memory may fail in a variety of ways. Patients with Korsakoff's syndrome demonstrate global memory deficits similar to those seen in patients with early progressive dementia. Korsakoff's patients, however, may recall rules and principles for organizing information and can gain access to their previously acquired knowledge (semantic memory), whereas recent memory may be grossly impaired. In contrast, dementia patients may have little access to previously acquired knowledge and therefore have great difficulty in organizing and encoding ongoing events. These contrasting forms of memory failure have implications for understanding the structure and mechanisms of memory and learning, particularly the relationship between episodic and semantic memory, as well as the development of therapeutic strategies for cognitive impairments.     

Current status of asymmetric synthesis

In the last 30 years the subject of asymmetric synthesis has grown from a little studied academic niche in organic chemistry to an intensely investigated field of commercial importance and heightened general interest. Impressive advances have been made in several areas, notably catalytic asymmetric homogeneous hydrogenation, catalytic asymmetric epoxidation of allyl alcohols and stereochemical control of carbon-carbon bond-forming reactions. Asymmetric synthesis must now be deliberately considered along with other available methods as a practical strategy for the synthesis of any chiral compound.     

Crop productivity and photoassimilate partitioning

The photosynthetic basis for increasing the yield of major field crops is examined in terms of improving the interception of seasonal solar radiation by crop foliage, the efficiency of conversion of intercepted light to photosynthetic assimilates, and the partitioning of photoassimilates to organs of economic interest. It is concluded that, in practice, genetic and chemical manipulation of light interception over the season and of partitioning offer the most potential for achieving further increases in yield. During the history of improvement of genetic yield potential of crops, increase in the partitioning of photoassimilates to harvested organs has been of primary importance.     

Marine lava cave fauna: composition, biogeography, and origins

An assemblage of endemic cavernicolous marine invertebrates, including taxa found on both sides of the Atlantic Ocean of great phylogenetic age or with affinities to deep sea organisms, inhabits the Jameos del Agua cave, a sea waterflooded Holocene lava tube cave on Lanzarote in the Canary Islands. This marine cave contains both relicts from Tethyan times, such as an apparently new crustacean family belonging to what had been the monotypic class Remipedia, and relicts of groups that are now common only in the deep sea as well as species that occur outside the cave.     

Synaptic morphology and differences in sensitivity

A relation between synaptic morphology and physiology was observed in an in vitro preparation of a sense organ (the ampulla of Lorenzini), in which activity was monitored from the primary afferent neurons before electron microscopic examination of the afferent synapses. The depth of the postsynaptic trough decreased as prefixation sensitivity of the sense organ decreased. This relation and other ultrastructural differences suggest that physiological properties of synapses are influenced by morphological features. Thus, synapses might be morphologically dynamic to modulate synaptic efficacy in relatively long-term phenomena.     

Some factors affecting the survival of root-nodule bacteria on desiccation

The average number of survivors of fast-growing medic rhizobia (3 strains), fast-growing Rhizobium leguminosarum types (6 strains) and slow-growing species (9 strains) following desiccation of sandy soil inoculated with 10⁶ bacteria·g^?1 soil was 727, 795 and 15,682 bacteria·g^?1 soil, respectively. Survival in desiccated sandy soil was not influenced by the degree of extracellular polysaccharide production in strains of R. trifolii, nor was it influenced by growth of R. meliloti and slow-growing species in media of low water activity before desiccation in sandy soil.A progressive increase in numbers of fast-growing bacteria surviving desiccation was observed in sandy soil amended with increasing concentrations of powdered montmorillonite, but not with mont-morillonite added as a suspension to the soil. The clay had either a detrimental effect or no effect on the survival of the slow-growing rhizobia. Maltose, sucrose and polyvinylpyrrolidonc provided a greater degree of protection to both fast- and slow-growing rhizobia than was obtained with montmorillonite. The effect of polyethylene glycol 6000 was similar to the effect of montmorillonite, as the polymer only protected the fast-growing rhizobia and not the slow-growing species.     

Correction to: Individual based modelling of fish migration in a 2-D river system: model description and case study

Landscape Ecology - In the original publication of the article, the third author name has been misspelt. The correct name is given in this Correction. The original version of this article was revised.     

The value of linking paleoecological and neoecological perspectives to understand spatially-explicit ecosystem resilience

Context

Predicting ecosystem resilience is a challenge, especially as climate change alters disturbance regimes and conditions for recovery. Recent research has highlighted the importance of spatially-explicit disturbance and resilience processes to long-term ecosystem dynamics. “Neoecological” approaches characterize resilience mechanisms at relatively fine spatio-temporal resolutions, but results are difficult to extrapolate across broad temporal scales or climatic ranges. Paleoecological methodologies can consider the effects of climates that differ from today. However, they are often limited to coarse-grained spatio-temporal resolutions.

Methods

In this synthesis, we describe implicit and explicit examples of studies that incorporate both neo- and paleoecological approaches. We propose ways to build on the strengths of both approaches in an explicit and proactive fashion.

Results

Linking the two approaches is a powerful way to surpass their respective limitations. Aligning spatial scales is critical: Paleoecological sampling design should incorporate knowledge of the spatial characteristics of the disturbance process, and neoecological studies benefit from a longer-term context to their conclusions. In some cases, modeling can incorporate non-spatial data from paleoecological records or emerging spatial paleo-data networks with mechanistic disturbance/recovery processes that operate at fine spatiotemporal scales.

Conclusions

Linking these two complementary approaches is a powerful way to build a complete understanding of ecosystem disturbance and resilience.