Intentionally introduced species: more easily invited than removed

Alien species are brought into countries world wide on a massive scale for agricultural production, ex situ conservation, landscape aesthetics, gardens, and ecosystem restoration. Unfortunately, some of these species have escaped and adversely impacted on regional as well as global biodiversity conservation and agricultural production. To reduce such risks, it is necessary to implement specific and effective measures. Since various government departments and institutions are involved in the management of alien species, it is difficult to prevent native and agroecosystems from being invaded by invited species. We propose the establishment of a supervision and inspection continuum over intentional species introduction, similar to that which exists in some countries over unintentional species introductions. Namely, a justification of the necessity to import, a risk assessment, assurances as to provision of an adequate containment facility assessment, and a damage-limitation protocol should that need to be invoked. These requirements should be satisfied before an alien species is knowingly imported, and the necessary follow-up supervision is important post- importation.     

RecA-mediated strand exchange traverses substitutional heterologies more easily than deletions or insertions

RecA protein in bacteria and its eukaryotic homolog Rad51 protein are responsible for initiation of strand exchange between homologous DNA molecules. This process is crucial for homologous recombination, the repair of certain types of DNA damage and for the reinitiation of DNA replication on collapsed replication forks. We show here, using two different types of in vitro assays, that in the absence of ATP hydrolysis RecA-mediated strand exchange traverses small substitutional heterologies between the interacting DNAs, whereas small deletions or insertions block the ongoing strand exchange. We discuss evolutionary implications of RecA selectivity against insertions and deletions and propose a molecular mechanism by which RecA can exert this selectivity.     

Inverse agonism: more than reverting constitutively active receptor signaling.

Seven-transmembrane receptors constitute one of the major families of proteins encoded by the genome. This type of receptor is one of the most important targets of the pharmaceutical industry, and many of the drugs with significant therapeutic action have been shown to be inverse agonists. Concepts regarding the mechanisms by which ligands activate and inactivate receptors are thought to be far more complex that a simple on-off switch. For both drug design and pharmacology principles, it is important to understand the mechanisms by which these drugs achieve their effects. Recent studies have demonstrated intriguing actions of inverse agonists. They have been shown not only to block constitutive responses of receptors but also to activate and regulate seven-transmembrane receptor signaling and trafficking. The activation of pathways by inverse agonists was shown to occur mainly via G-protein-independent mechanisms. These findings emphasize the importance of inverse agonism as a principle of receptor regulation. In this paper, we will review the evidence supporting inverse agonist promoted signaling and trafficking.     

A new vitamin E analogue more active than alpha-tocopherol in the rat curative myopathy bioassay

Vitamin E owes its biological effects to its antioxidant activity. Kinetic and mechanistic studies on phenolic antioxidants in vitro have led us to design and synthesize all-rac-2,4,6,7-tetramethyl-2-(4',8',12'-trimethyltridecyl) -5-hydroxy-3,4-dihydrobenzofuran, 3. In the rat curative myopathy bioassay the acetate of this compound has 1.5-1.9 times the bioactivity of all-rac-alpha-tocopherol acetate. This represents the first time that a rationally designed synthetic 'vitamin' has been found to have more activity in vivo than the corresponding natural vitamin.     

Leaf litter quality coupled to Salix variety drives litter decomposition more than stand diversity or climate

Plant and Soil - Decomposition of leaf litter is influenced by litter quality as determined by plant genotype and environment, as well as climate and soil properties. We studied these drivers of...     

Lipolysis: more than just a lipase

Successful adaptation to starvation in mammals depends heavily on the regulated mobilization of fatty acids from triacylglycerols stored in adipose tissue. Although it has long been recognized that cyclic AMP represents the critical second messenger and hormone-sensitive lipase (HSL)**Abbreviations used in this paper: ADRP, adipocyte differentiation-related protein; HSL, hormone-sensitive lipase; PKA, protein kinase A; TAG, triacylglycerol. the rate-determining enzyme for lipolysis, simple activation of the enzyme has failed to account for the robust augmentation of fatty release in response to physiological agonists. In this issue, Sztalryd et al. (2003) provide convincing support to the notion that the subcellular compartmentalization of lipase also regulates lipolysis, and, more importantly, that proteins other than HSL are localized to the lipid droplet and are indispensable for its optimal hydrolysis.     

A comprehensive DNA barcode database for Central European beetles with a focus on Germany: adding more than 3500 identified species to BOLD

Beetles are the most diverse group of animals and are crucial for ecosystem functioning. In many countries, they are well established for environmental impact assessment, but even in the well‐studied Central European fauna, species identification can be very difficult. A comprehensive and taxonomically well‐curated DNA barcode library could remedy this deficit and could also link hundreds of years of traditional knowledge with next generation sequencing technology. However, such a beetle library is missing to date. This study provides the globally largest DNA barcode reference library for Coleoptera for 15 948 individuals belonging to 3514 well‐identified species (53% of the German fauna) with representatives from 97 of 103 families (94%). This study is the first comprehensive regional test of the efficiency of DNA barcoding for beetles with a focus on Germany. Sequences ≥500 bp were recovered from 63% of the specimens analysed (15 948 of 25 294) with short sequences from another 997 specimens. Whereas most specimens (92.2%) could be unambiguously assigned to a single known species by sequence diversity at CO1, 1089 specimens (6.8%) were assigned to more than one Barcode Index Number (BIN), creating 395 BINs which need further study to ascertain if they represent cryptic species, mitochondrial introgression, or simply regional variation in widespread species. We found 409 specimens (2.6%) that shared a BIN assignment with another species, most involving a pair of closely allied species as 43 BINs were involved. Most of these taxa were separated by barcodes although sequence divergences were low. Only 155 specimens (0.97%) show identical or overlapping clusters.     

Sarcopenia is more than a muscular deficit

Sarcopenia is a complex process that appears in aged muscle associated with a decrease in mass, strength, and velocity of contraction. This process is the result of many molecular, cellular and functional alterations. It has been suggested that sarcopenia may be triggered by reactive oxygen species (ROS) that have accumulated throughout one's lifetime. We found a significant increase in oxidation of DNA and lipids in the elderly muscle, more evident in males, and a reduction in catalase and glutathione transferase activities. Experiments on Ca2+ transport showed an abnormal functional response of aged muscle after exposure to caffeine, which increases the opening of Ca2+ channels, as well a reduced activity of the Ca2+ pump in elderly males. From these results we concluded that oxidative stress play an important role in muscle aging and that oxidative damage is much more evident in elderly males, suggesting a gender difference may be related to hormonal factors. The progression of sarcopenia is directly related to a significant reduction of the regenerative potential of muscle normally due to a type of adult stem cells, known as satellite cells, which lie outside the sarcolemma and remain quiescent until external stimuli trigger as growth factors (IGF-1 or mIGF-1) their re-entry into the cell cycle. One possibility is that the anti oxidative capacity of satellite cells could also be altered and this, in turn, determines the decrease of their regenerative capacity. Data concerning this hypothesis are discussed     

A20: more than one way to skin a cat

In this issue of Molecular Cell, Skaug et al. (2011) propose a polyubiquitin-dependent, noncatalytic mechanism by which the deubiquitinase A20 inhibits IκB kinase and NF-κB activation.     

A numerically efficient model for simulation of defibrillation in an active bidomain sheet of myocardium

Presented here is an efficient algorithm for solving the bidomain equations describing myocardial tissue with active membrane kinetics. An analysis of the accuracy shows advantages of this numerical technique over other simple and therefore popular approaches. The modular structure of the algorithm provides the critical flexibility needed in simulation studies: fiber orientation and membrane kinetics can be easily modified. The computational tool described here is designed specifically to simulate cardiac defibrillation, i. e., to allow modeling of strong electric shocks applied to the myocardium extracellularly. Accordingly, the algorithm presented also incorporates modifications of the membrane model to handle the high transmembrane voltages created in the immediate vicinity of the defibrillation electrodes.     

Mitochondria: more than just a powerhouse

Pioneering biochemical studies have long forged the concept that the mitochondria are the 'energy powerhouse of the cell'. These studies, combined with the unique evolutionary origin of the mitochondria, led the way to decades of research focusing on the organelle as an essential, yet independent, functional component of the cell. Recently, however, our conceptual view of this isolated organelle has been profoundly altered with the discovery that mitochondria function within an integrated reticulum that is continually remodeled by both fusion and fission events. The identification of a number of proteins that regulate these activities is beginning to provide mechanistic details of mitochondrial membrane remodeling. However, the broader question remains regarding the underlying purpose of mitochondrial dynamics and the translation of these morphological transitions into altered functional output. One hypothesis has been that mitochondrial respiration and metabolism may be spatially and temporally regulated by the architecture and positioning of the organelle. Recent evidence supports and expands this idea by demonstrating that mitochondria are an integral part of multiple cell signaling cascades. Interestingly, proteins such as GTPases, kinases and phosphatases are involved in bi-directional communication between the mitochondrial reticulum and the rest of the cell. These proteins link mitochondrial function and dynamics to the regulation of metabolism, cell-cycle control, development, antiviral responses and cell death. In this review we will highlight the emerging evidence that provides molecular definition to mitochondria as a central platform in the execution of diverse cellular events.     

Why are mammalian alkaline phosphatases much more active than bacterial alkaline phosphatases?

Mammalian alkaline phosphatases are 20-30-fold more active than the corresponding bacterial enzymes even though their amino acid sequences are 25–30% absolutely conserved. In the active-site region there are two noticeable differences between the sequences of the bacterial and mammalian enzymes, in the Escherichia coli enzyme positions 153 and 328 are Asp and Lys, respectively, but in the mammalian enzymes His is observed at both of these positions. Site-specific mutagenesis, genetic and X-ray crystallographic data, which will be summarized here, suggest that the His substitutions at positions 153 and 328 are primarily responsible for the differences in properties between the bacterial and mammalian alkaline phosphatases.