Looking for food in all the right places?

Examining a potential functional role for growth hormone secretagogue receptors in the hippocampus, Diano and colleagues (Diano et al., 2006), demonstrate novel actions of the orexigenic peptide ghrelin in hippocampal synaptic architecture, LTP, and learning and memory. These data suggest functional links between metabolic signaling and higher neural function.     

Something for the weekend? Examining the bias in avian phenological recording

In this paper we examine the bias towards weekend recording (the weekend effect) in volunteer phenology, using over 14,000 bird migration phenological observations from eight locations in the UK as a data source. Data from 45 bird species were used. Overall, 44% of all records were taken at weekends in contrast to the 28.6% (i.e. two out of seven days) that would be expected if records were evenly spread throughout the week. Whilst there is documented evidence of environmental differences at weekends, particularly in large urban areas, we believe the weekend effect is mostly a consequence of greater recorder effort at weekends. Some birds, likely to be obvious by their behaviour or abundance, had fewer weekend records than the remaining species. The weekend effect, to some extent, differed between locations and between seasons. There was some evidence that, particularly in autumn, the weekend bias may be lessening. If so, this will increase the accuracy of phenological records, making the detection of changes and responses to temperature easier.     

Is the PRC for Dark Pulses in LL a Mirror Image of the PRC for Light Pulses in DD in Mice?

The phase-response curves (PRC) for light pulses in continuous darkness (DD) have been described in many mammals, especially in nocturnal rodents. The PRC for dark pulses in continuous light (LL), however, has been described in a few mammals only, in nocturnal for bat and for hamster and in diurnal for Octodon degus, suggesting that this PRC is mirror imaging the PRC for light pulses. Therefore, the effect of 1-h and 3-h lasting dark pulses on the circadian wheel-running activity rhythm of mice in continuous light was investigated and then the PRC for dark pulses in LL was drawn up. For comparison, the effect of 1-h lasting light pulses on the circadian wheel-running activity rhythm of mice in DD was examined and the PRC for light pulses in DD was constructed. It appeared that the PRC for dark pulses, to a certain degree, represents a mirror image of the PRC for light pulses in mice. However, the advance region of this PRC is longer than that of delay. The mechanism of dark pulses action is discussed.     

Is the PRC for Dark Pulses in LL a Mirror Image of the PRC for Light Pulses in DD in Mice?

The phase-response curves (PRC) for light pulses in continuous darkness (DD) have been described in many mammals, especially in nocturnal rodents. The PRC for dark pulses in continuous light (LL), however, has been described in a few mammals only, in nocturnal for bat and for hamster and in diurnal for Octodon degus, suggesting that this PRC is mirror imaging the PRC for light pulses. Therefore, the effect of 1-h and 3-h lasting dark pulses on the circadian wheel-running activity rhythm of mice in continuous light was investigated and then the PRC for dark pulses in LL was drawn up. For comparison, the effect of 1-h lasting light pulses on the circadian wheel-running activity rhythm of mice in DD was examined and the PRC for light pulses in DD was constructed. It appeared that the PRC for dark pulses, to a certain degree, represents a mirror image of the PRC for light pulses in mice. However, the advance region of this PRC is longer than that of delay. The mechanism of dark pulses action is discussed.     

What are the driving forces for water lifting in the xylem conduit?

After Renner had shown convincingly in 1925 that the transpirational water loss generates tensions larger than 0.1 MPa (i.e. negative pressures) in the xylem of cut leafy twigs the Cohesion Theory proposed by Böhm, Askenasy, Dixon and Joly at the end of the 19th century was immediately accepted by plant physiologists. Introduction of the pressure chamber technique by Scholander et al. in 1965 enforced the general belief that tension is the only driving force for water lifting although substantial criticism regarding the technique and/or the Cohesion Theory was published by several authors. As typical for scientific disciplines, the advent of minimal‐ and non‐invasive techniques in the last decade as well as the development of a new, reliable method for xylem sap sampling have challenged this view. Today, xylem pressure gradients, potentials, ion concentrations and volume flows as well as cell turgor pressure gradients can be monitored online in intact transpiring higher plants, and within a given physiological context by using the pressure probe technique and high‐resolution NMR imaging techniques, respectively. Application of the pressure probe technique to transpiring plants has shown that negative absolute pressures (down to ? 0.6 MPa) and pressure gradients can exist temporarily in the xylem conduit, but that the magnitude and (occasionally) direction of gradients contrasts frequently the belief that tension is the only driving force. This seems to be particularly the case for plants faced with problems of height, drought, freezing and salinity as well as with cavitation of the tensile water. Reviewing the current data base shows that other forces come into operation when exclusively tension fails to lift water against gravity due to environmental conditions. Possible candidates are longitudinal cellular and xylem osmotic pressure gradients, axial potential gradients in the vessels as well as gel‐ and gas bubble‐supported interfacial gradients. The multiforce theory overcomes the problem of the Cohesion Theory that life on earth depends on water being in a highly metastable state.     

Is there a role for CEA in innate immunity in the colon?

Carcinoembryonic antigen (CEA) is a well known tumor marker associated with the progression of colorectal tumors. The CEA family of glycoproteins has been fully characterized and the function of some of its members is now beginning to be understood. Here, we advance the hypothesis that, rather than functioning in cell adhesion as has been suggested previously, CEA plays a role in protecting the colonic mucosa from microbial invasion. This hypothesis is based on new microscopic, molecular, phylogenetic and microbiological evidence.     

Actin in the nucleus: what form and what for?

Actin is an abundant protein in most nonmuscle cells. It has often been observed in isolated nuclei, yet cytoplasmic contamination was of course initially regarded as the most plausible origin. Numerous studies on nuclear actin appeared in the 1970s and 1980s, but the picture remained rather muddy. The viewpoint at that time was that actin-shown to move freely between cytoplasm and nucleus-was a mere "thermodynamic wanderer," transiently occupying the nucleus. More recently, evidence has been mounting that actin's presence in the nucleus is not simply governed by the laws of diffusion. The same holds true for the finding of various actin-related proteins in the nucleus, and the case for nuclear myosin, specifically myosin I, is now quite convincing. Moreover, the first intimations of functional roles of nuclear actin are now emerging. Here we examine the overall subject from cell biological and chemical perspectives. The major issue is no longer the presence of actin in the nucleus but rather its supramolecular organization, intranuclear locations, and, of course, functions. These issues interface with recent findings that reveal a surprisingly diverse repertoire of actin conformations and oligomer and polymer forms beyond monomeric G-actin and polymeric F-actin. We present ideas for advancing the nuclear actin field and call for a renewed attack on this major problem in cell biology.     

Has the Time Come for Big Science in Wildlife Health?

The consequences of wildlife emerging diseases are global and profound with increased burden on the public health system, negative impacts on the global economy, declines and extinctions of wildlife species, and subsequent loss of ecological integrity. Examples of health threats to wildlife include Batrachochytrium dendrobatidis, which causes a cutaneous fungal infection of amphibians and is linked to declines of amphibians globally; and the recently discovered Pseudogymnoascus (Geomyces) destructans, the etiologic agent of white nose syndrome which has caused precipitous declines of North American bat species. Of particular concern are the novel pathogens that have emerged as they are particularly devastating and challenging to manage. A big science approach to wildlife health research is needed if we are to make significant and enduring progress in managing these diseases. The advent of new analytical models and bench assays will provide us with the mathematical and molecular tools to identify and anticipate threats to wildlife, and understand the ecology and epidemiology of these diseases. Specifically, new molecular diagnostic techniques have opened up avenues for pathogen discovery, and the application of spatially referenced databases allows for risk assessments that can assist in targeting surveillance. Long-term, systematic collection of data for wildlife health and integration with other datasets is also essential. Multidisciplinary research programs should be expanded to increase our understanding of the drivers of emerging diseases and allow for the development of better disease prevention and management tools, such as vaccines. Finally, we need to create a National Fish and Wildlife Health Network that provides the operational framework (governance, policies, procedures, etc.) by which entities with a stake in wildlife health cooperate and collaborate to achieve optimal outcomes for human, animal, and ecosystem health.