Therapy for prion diseases Insights from the use of RNA interference

Insights into the molecular basis and the temporal evolution of neurotoxicity in prion disease are increasing, and recent work in mice leads to new avenues for targeting treatment of these disorders. Using lentivirally mediated RNA interference (RNAi) against native prion protein (PrP), White et al. report the first therapeutic intervention that results in neuronal rescue, prevents symptoms and increases survival in mice with established prion disease.(1) Both the target and the timing of treatment here are crucial to the effectiveness of this strategy: the formation of the neurotoxic prion agent is prevented at a point when diseased neurons can still be saved from death. But the data also give new insights into the timing of treatment in the context of the pattern of spread of prion infection throughout the brain, with implications for developing the most effective treatments

A Molecular Toolbox for Rapid Generation of Viral Vectors to Up- or Down-Regulate Neuronal Gene Expression in vivo

We introduce a molecular toolbox for manipulation of neuronal gene expression in vivo. The toolbox includes promoters, ion channels, optogenetic tools, fluorescent proteins, and intronic artificial microRNAs. The components are easily assembled into adeno-associated virus (AAV) or lentivirus vectors using recombination cloning. We demonstrate assembly of toolbox components into lentivirus and AAV vectors and use these vectors for in vivo expression of inwardly rectifying potassium channels (Kir2.1, Kir3.1, and Kir3.2) and an artificial microRNA targeted against the ion channel HCN1 (HCN1 miRNA). We show that AAV assembled to express HCN1 miRNA produces efficacious and specific in vivo knockdown of HCN1 channels. Comparison of in vivo viral transduction using HCN1 miRNA with mice containing a germ line deletion of HCN1 reveals similar physiological phenotypes in cerebellar Purkinje cells. The easy assembly and re-usability of the toolbox components, together with the ability to up- or down-regulate neuronal gene expression in vivo, may be useful for applications in many areas of neuroscience

Cortical Tension Allocates the First Inner Cells of the Mammalian Embryo

Every cell in our body originates from the pluripotent inner mass of the embryo, yet it is unknown how biomechanical forces allocate inner cells in vivo. Here we discover subcellular heterogeneities in tensile forces, generated by actomyosin cortical networks, which drive apical constriction to position the first inner cells of living mouse embryos. Myosin II accumulates specifically around constricting cells, and its disruption dysregulates constriction and cell fate. Laser ablations of actomyosin networks reveal that constricting cells have higher cortical tension, generate tension anisotropies and morphological changes in adjacent regions of neighboring cells, and require their neighbors to coordinate their own changes in shape. Thus, tensile forces determine the first spatial segregation of cells during mammalian development. We propose that, unlike more cohesive tissues, the early embryo dissipates tensile forces required by constricting cells via their neighbors, thereby allowing confined cell repositioning without jeopardizing global architecture.Fil: Samarage, Chaminda R.. Monash University; AustraliaFil: White, Melanie D.. Monash University; AustraliaFil: Alvarez, Yanina Daniela. Monash University; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fierro González, Juan Carlos. Monash University; AustraliaFil: Henon, Yann. Monash University; AustraliaFil: Jesudason, Edwin C.. National Health Service Scotland; Reino UnidoFil: Bissiere, Stephanie. Monash University; Australia. Institute of Molecular and Cell Biology; SingapurFil: Fouras, Andreas. Monash University; AustraliaFil: Plachta, Nicolas. Monash University; Australia. Institute of Molecular and Cell Biology; Singapu

Structural basis for phosphorylation and lysine acetylation cross-talk in a kinase motif associated with myocardial ischemia and cardioprotection

Myocardial ischemia and cardioprotection by ischemic pre-conditioning induce signal networks aimed at survival or cell death if the ischemic period is prolonged. These pathways are mediated by protein post-translational modifications that are hypothesized to cross-talk with and regulate each other. Phosphopeptides and lysine-acetylated peptides were quantified in isolated rat hearts subjected to ischemia or ischemic pre-conditioning, with and without splitomicin inhibition of lysine deacetylation. We show lysine acetylation (acetyl-Lys)-dependent activation of AMP-activated protein kinase, AKT, and PKA kinases during ischemia. Phosphorylation and acetyl-Lys sites mapped onto tertiary structures were proximal in >50% of proteins investigated, yet they were mutually exclusive in 50 ischemic pre-conditioning- and/or ischemia-associated peptides containing the KXXS basophilic protein kinase consensus motif. Modifications in this motif were modeled in the C terminus of muscle-type creatine kinase. Acetyl-Lys increased proximal dephosphorylation by 10-fold. Structural analysis of modified muscle-type creatine kinase peptide variants by two-dimensional NMR revealed stabilization via a lysine-phosphate salt bridge, which was disrupted by acetyl-Lys resulting in backbone flexibility and increased phosphatase accessibility

A hypothetico-deductive approach to assessing the social function of chemical signalling in a non-territorial solitary carnivore

The function of chemical signalling in non-territorial solitary carnivores is still relatively unclear. Studies on territorial solitary and social carnivores have highlighted odour capability and utility, however the social function of chemical signalling in wild carnivore populations operating dominance hierarchy social systems has received little attention. We monitored scent marking and investigatory behaviour of wild brown bears Ursus arctos, to test multiple hypotheses relating to the social function of chemical signalling. Camera traps were stationed facing bear ‘marking trees’ to document behaviour by different age sex classes in different seasons. We found evidence to support the hypothesis that adult males utilise chemical signalling to communicate dominance to other males throughout the non-denning period. Adult females did not appear to utilise marking trees to advertise oestrous state during the breeding season. The function of marking by subadult bears is somewhat unclear, but may be related to the behaviour of adult males. Subadults investigated trees more often than they scent marked during the breeding season, which could be a result of an increased risk from adult males. Females with young showed an increase in marking and investigation of trees outside of the breeding season. We propose the hypothesis that females engage their dependent young with marking trees from a young age, at a relatively ‘safe’ time of year. Memory, experience, and learning at a young age, may all contribute towards odour capabilities in adult bears

Adherence to antidepressant therapy for major depressive patients in a psychiatric hospital in Thailand

Poor adherence to antidepressant therapy is an important barrier to the effective management of major depressive disorder. This study aims to quantify the adherence rate to antidepressant treatment and to determine the pattern of prescriptions of depressed patients in a psychiatric institute in Thailand.This retrospective study used electronic pharmacy data of outpatients aged 15 or older, with a new diagnosis of major depression who received at least one prescription of antidepressants between August 2005 and September 2008. The medication possession ratio (MPR) was used to measure adherence over a 6 month period.1,058 were eligible for study inclusion. The overall adherence (MPR > 80%) in those attending this facility at least twice was 41% but if we assume that all patients who attended only once were non-adherent, adherence may be as low as 23%. Fluoxetine was the most commonly prescribed drug followed by TCAs. A large proportion of cases received more than one drug during one visit or was switched from one drug to another (39%).Adherence to antidepressant therapy for treatment of major depression in Thailand is rather low compared to results of adherence from elsewhere

Middle-late Quaternary palaeoclimate variability from lake and wetland deposits in the Nefud Desert, Northern Arabia

Records of former lake and wetland development in present day arid/hyper-arid environments provide an important source of information for palaeoclimatic and palaeoenvironmental studies. In Arabia, such records are typically confined to eccentricity-modulated insolation maxima, and are often spatially and temporally discontinuous. Here we present records from a single locality in Northern Arabia of wetter interludes during both global interglacial and glacial conditions, providing a unique opportunity to examine the nature of these events in a common setting. At Jubbah, in the southern Nefud Desert, lake and wetland deposits reveal the repeated formation of a water body within a large endorheic basin over the past ca. 360 kyr. Lake/wetland formation occurred during MIS 11/9, 7, 5, 3 and the early Holocene, assisted by local topographic controls, and spring recharge. Palaeoenvironmental and palaeoecological data reveal the existence of a large still water body formed during either MIS 11 or 9 (ca. 363 ka), and basin wide alluviation followed by lake formation during MIS 7 (ca. 212 ka). During MIS 5e (ca. 130 ka) a large freshwater lake occupied the basin, while during MIS 5a (ca. 80 ka) the basin contained a shallow wetland and freshwater lake complex. Lake/wetland formation also occurred during early MIS 3 (ca. 60 ka), at the Terminal Pleistocene-Holocene transition (ca. 12.5 ka), and the early-middle Holocene (ca. 9–6.5 ka). Phases of lake and wetland development coincided with human occupation of the basin during the Middle Palaeolithic, Epipalaeolithic and Neolithic periods, highlighting the significance of the region for early demographic change

A PSTOL-like gene, TaPSTOL, controls a number of agronomically important traits in wheat

Background Phosphorus (P) is an essential macronutrient for plant growth, and is required in large quantities by elite varieties of crops to maintain yields. Approximately 70% of global cultivated land suffers from P deficiency, and it has recently been estimated that worldwide P resources will be exhausted by the end of this century, increasing the demand for crops more efficient in their P usage. A greater understanding of how plants are able to maintain yield with lower P inputs is, therefore, highly desirable to both breeders and farmers. Here, we clone the wheat (Triticum aestivum L.) homologue of the rice PSTOL gene (OsPSTOL), and characterize its role in phosphate nutrition plus other agronomically important traits. Results TaPSTOL is a single copy gene located on the short arm of chromosome 5A, encoding a putative kinase protein, and shares a high level of sequence similarity to OsPSTOL. We re-sequenced TaPSTOL from 24 different wheat accessions and (3) three T. durum varieties. No sequence differences were detected in 26 of the accessions, whereas two indels were identified in the promoter region of one of the durum wheats. We characterised the expression of TaPSTOL under different P concentrations and demonstrated that the promoter was induced in root tips and hairs under P limiting conditions. Overexpression and RNAi silencing of TaPSTOL in transgenic wheat lines showed that there was a significant effect upon root biomass, flowering time independent of P treatment, tiller number and seed yield, correlating with the expression of TaPSTOL. However this did not increase PUE as elevated P concentration in the grain did not correspond to increased yields. Conclusions Manipulation of TaPSTOL expression in wheat shows it is responsible for many of the previously described phenotypic advantages as OsPSTOL except yield. Furthermore, we show TaPSTOL contributes to additional agronomically important traits including flowering time and grain size. Analysis of TaPSTOL sequences from a broad selection of wheat varieties, encompassing 91% of the genetic diversity in UK bread wheat, showed that there is very little genetic variation in this gene, which would suggest that this locus may have been under high selection pressure