Signaling at the vertebrate synapse: new roles for embryonic morphogens?

The formation of synapses is critical for functional neuronal connectivity. The coordinated assembly at both sides of the synapse is fundamental for the proper apposition of the neurotransmitter release machinery on the presynaptic neuron and the clustering of neurotransmitter receptors and ion channels on the receptive postsynaptic cell. This process requires bidirectional communication between the presynaptic neuron and its postsynaptic target, another neuron, or muscle fiber. Extracellular signals such as WNT, TGF-beta, and FGF factors are emerging as key target-derived signals required for the initial stages of synaptic assembly. Studies in invertebrates are also providing new insights into the function of these signals in synaptic growth and homeostasis. During early embryonic patterning, WNT, TGF-beta, and FGF factors function as typical morphogens in a concentration-dependent manner to regulate cell fate decisions. This mode of action raises the provocative idea that these same morphogens might also provide a coordinate system for axons to establish the distance to their targets during axon guidance and synapse formation.     

Myrothecium: A new indoor contaminant?

In the natural environmentMyrothecium species occur as soil or leaf surface saprobes or as weak plant pathogens. In addition, some species ofMyrothecium are known to produce trichothecene mycotoxins. During a previous aerobiological investigation at two Las Vegas elementary schools,Myrothecium conidia were found to be the second most abundant spore type identified indoors from Burkard personal spore trap samples. The present study was undertaken to re-examine the schools to locate the source ofMyrothecium spores and to examine the ability ofMyrothecium to grow on indoor substrates. There were no obvious signs of contamination in the classrooms; however,Myrothecium spores occurred on about 30% of the Burkard samples. Two colonies ofMyrothecium were identified from subcultures of the Andersen samples, and three colonies were identified from carpet dust samples. Culture studies showed that a strain ofMyrothecium cinctum was able to grow on various culture media as well as on various indoor substrates including paper, cardboard, wallpaper, ceiling tiles, dry wall, carpets and cotton rug. Although there was no attempt to estimate any human health risks, these investigations are believed to be the first to document abundantMyrothecium spores from indoor air samples.     

A new histone at the centromere?

The centromere is a classic system to study epigenetic specification, and most research has focused on a specialized histone variant, CENP-A, that is required for kinetochore assembly. Now Nishino et?al. reveal a new level of complexity for centromeric chromatin, by showing that the kinetochore complex CENP-T-W-S-X shares structural and functional properties with canonical histones.     

Neobetanin: A new natural plant constituent?

Neobetanin, recently reported as a natural constituent of beetroot, is not present in fresh beet juice and hence appears to be an artifact of the isolation process.     

Accelerated nitrogen inputs — A new problem or a new perspective?

This paper considers whether new problems are arising in forest ecosystems due to increased levels of inorganic N deposition from the atmosphere, or whether there are no new problems, just a change of perception. Deposition of N has indeed increased. Wet deposition rates are reasonably quantified, but the rates of dry deposition to forests are largely unknown. Current transport and deposition models are probably under-estimating N deposition to forests. Consideration of possible effects of enhanced N deposition reveals with varying degrees of certainty that there may be effects due to high N in biomass, high uptake rates, leaching of nitrate and consequent acidification, and an overall increase in N availability. Forest ecosystems are not well-enough understood to set a critical load for N deposition, but enough is known to define some upper limits.     

2010: A new beginning for biodiversity?

Proclaimed “International Year of Biodiversity”, will 2010 hold all its promises? Reminder: initiated by the Convention on Biological Diversity ratified after the global summit in Rio de Janeiro, delegations from more than one hundred countries gathered in Johannesburg in 2002 and committed themselves to slowing the erosion of biodiversity by 2010. The European Union was more ambitious (or reckless?) and even spoke about halting this erosion (European Environment Agency, Progress towards the European 2010 biodiversity target, 2009) [1]! Well, that date has come and the overall appraisal that has been made formally in Nagoya in October this year was not so brilliant (see Leadley et al., 2010) [2]–but the same slogan has been launched for 2020! The aim here is not to repeat that appraisal, but, after considering the broad outlines, to evoke some of the issues and challenges that inevitably result from the great question of the protection and management of global biodiversity.     

Circular economy: A new research field?

Action to pursue the circular economy (CE) transition is burgeoning in the government and the private sector. Does this action signal that CE is a distinct field of research with a unique disciplinary identity? This article argues that CE has reached field status, through its own epistemic communities characterized by increasingly shared methodological perspectives and normative ideals, and through institutionalized knowledge development through research journals and authority structures. The recent growth of CE research points toward more contextualized and nuanced operationalizations of the concept, evidence that the field is approaching a threshold state of maturity. Drawing on observations from academic literature and discussions with researchers and experts, we trace the process by which CE has arrived at the status of a field. The article concludes with reflections on research directions.     

A new 'spin' on neural stem cells?

The existence of neural stem cells in the adult brain was essentially denied until the last decade. Within the past ten years, considerable progress has been made in examining the fundamental properties of neural stem cells. Most recently there has been much interest in the identification and precise location of the adult neural stem cells in vivo. Studies examining the localization of neural stem cells are controversial and suggest two distinct locations within the adult brain: the ependymal layer lining the ventricles, and the subependymal layer immediately adjacent to the ependyma.