TGF-beta mediated Msx2 expression controls occipital somites-derived caudal region of skull development

Craniofacial development involves cranial neural crest (CNC) and mesoderm-derived cells. TGF-beta signaling plays a critical role in instructing CNC cells to form the craniofacial skeleton. However, it is not known how TGF-beta signaling regulates the fate of mesoderm-derived cells during craniofacial development. In this study, we show that occipital somites contribute to the caudal region of mammalian skull development. Conditional inactivation of Tgfbr2 in mesoderm-derived cells results in defects of the supraoccipital bone with meningoencephalocele and discontinuity of the neural arch of the C1 vertebra. At the cellular level, loss of TGF-beta signaling causes decreased chondrocyte proliferation and premature differentiation of cartilage to bone. Expression of Msx2, a critical factor in the formation of the dorsoventral axis, is diminished in the Tgfbr2 mutant. Significantly, overexpression of Msx2 in Myf5-Cre;Tgfbr2flox/flox mice partially rescues supraoccipital bone development. These results suggest that the TGF-beta/Msx2 signaling cascade is critical for development of the caudal region of the skull.     

Effects of transgenic Bt cotton on insecticide use and abundance of two generalist predators

Considerable effort has been expended to determine if crops genetically engineered to produce Bacillus thuringiensis (Bt) toxins harm non‐target arthropods. However, if Bt crops kill target pests and thereby reduce insecticide use, this could benefit some non‐target arthropods. We analyzed data from 21 commercial cotton fields in Arizona to test the effects of Bt cotton on insecticide use and abundance of two non‐target arthropods, the generalist predators Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) and Orius tristicolor (White) (Heteroptera: Anthocoridae). The number of insecticide sprays was more than double for non‐Bt cotton compared with Bt cotton that produced Cry1Ac. The abundance of both predators was negatively associated with the number of insecticide sprays, although significantly so for only one of two sampling periods for each species tested. With the effects of insecticides statistically removed, field type (Bt or non‐Bt cotton) did not affect the abundance of either predator. Accordingly, without adjusting for the effects of insecticide sprays, the abundance of C. carnea was higher in Bt cotton fields than in non‐Bt cotton fields, but significantly so during only one of two sampling periods. The abundance of O. tristicolor did not differ between field types, even without adjusting for effects of insecticide sprays. The results indicate that Bt crops can affect insecticide use, which in turn can affect the relative abundance of non‐target arthropods in Bt and non‐Bt fields. Thus, environmental impact assessment should incorporate analysis of the effects of transgenic crops on management practices, as well as evaluation of the direct effects of such crops.     

Evidence that the parasitic nematode Skrjabinoclava manipulates host Corophium behavior to increase transmission to the sandpiper, Calidris pusilla

We found evidence that a nematode (Skrjabinoclava morrisoni) adaptivelymanipulates the behavior of its intermediate host (the amphipod Corophiumvolutator) to increase its likelihood of transmission to itsfinal host (the semipalmated sandpiper, Calidris pusilla). We foundthat male and female amphipods parasitized by nematodes increasedtheir surface activity in the field during daytime, but notduring nighttime hours. Increased surface activity is knownto increase susceptibility of amphipods to predation by sandpipersduring the day, but not at night, when sandpipers do not feedvisually. Also, as predicted by the manipulation hypothesis,only late-stage (infective) larvae of nematodes were associatedwith behavioral changes of amphipods. We found no evidence thatparasites were associated with other amphipod behaviors in thelaboratory, such as trail complexity, distance traveled, orburrow-probing activity of crawling males as would be expectedif parasitized hosts altered their own behavior. Survivorshipof amphipods was also unaffected by parasitism, which may favorparasite transmission. Thus, behavioral changes of parasitizedhosts were simple, and their expression was context-dependentand related to likelihood of predation. We argue that maturationtimes of nematodes in relation to migration schedules of sandpipers providea narrow window of opportunity and may explain why nematodes manipulateamphipod behavior.     

A model of erythropoiesis in adults with sufficient iron availability

In this paper we present a model for erythropoiesis under the basic assumption that sufficient iron availability is guaranteed. An extension of the model including a sub-model for the iron dynamics in the body is topic of present research efforts. The model gives excellent results for a number of important situations: recovery of the red blood cell mass after blood donation, adaptation of the number of red blood cells to changes in the altitude of residence and, most important, the reaction of the body to different administration regimens of erythropoiesis stimulating agents, as for instance in the case of pre-surgical administration of Epoetin-α. The simulation results concerning the last item show that choosing an appropriate administration regimen can reduce the total amount of the administered drug considerably. The core of the model consists of structured population equations for the different cell populations which are considered. A key feature of the model is the incorporation of neocytolysis.     

Synthesis of polymerized thin films for immobilized ligand display in proteomic analysis

We describe a new material for the display of biomolecular ligands for use in proteomic analysis. We report here on the construction of the first functionalized polymerized diacetylene thin films (PDTFs) for use in displaying immobilized ligands and their application in mass spectral proteomic analysis. Functionalized polymerized thin film surfaces were constructed with diacetylene-containing biotin lipid monomers designed for the capture of proteins (streptavidin) from a complex cellular lysate and detection with mass spectrometry (MS). These materials serve as a prototype for ligand-based spotted arrays amenable to high throughput screening. Functionalized PDTFs can be easily manufactured for customized microarrays and demonstrate high protein specificity and low nonspecific protein adsorption, and the resulting microarrays constructed from these materials are compatible with several different protein analysis platforms. Our results suggest that these materials have broad potential applications for use in mass spectral-based proteomic analysis.     

PhosphoScore: an open-source phosphorylation site assignment tool for MSn data

Correct phosphorylation site assignment is a critical aspect of phosphoproteomic analysis. Large-scale phosphopeptide data sets that are generated through liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) analysis often contain hundreds or thousands of phosphorylation sites that require validation. To this end, we have created PhosphoScore, an open-source assignment program that is compatible with phosphopeptide data from multiple MS levels (MS(n)). The algorithm takes into account both the match quality and normalized intensity of observed spectral peaks compared to a theoretical spectrum. PhosphoScore produced >95% correct MS(2) assignments from known synthetic data, > 98% agreement with an established MS(2) assignment algorithm (Ascore), and >92% agreement with visual inspection of MS(3) and MS(4) spectra.     

Numb endocytic adapter proteins regulate the transport and processing of the amyloid precursor protein in an isoform-dependent manner: implications for Alzheimer disease pathogenesis

Central to the pathogenesis of Alzheimer disease is the aberrant processing of the amyloid precursor protein (APP) to generate amyloid beta-peptide (Abeta), the principle component of amyloid plaques. The cell fate determinant Numb is a phosphotyrosine binding domain (PTB)-containing endocytic adapter protein that interacts with the carboxyl-terminal domain of APP. The physiological relevance of this interaction is unknown. Mammals produce four alternatively spliced variants of Numb that differ in the length of their PTB and proline-rich region. In the current study, we determined the influence of the four human Numb isoforms on the intracellular trafficking and processing of APP. Stable expression of Numb isoforms that differ in the PTB but not in the proline-rich region results in marked differences in the sorting of APP to the recycling and degradative pathways. Neural cells expressing Numb isoforms that lack the insert in the PTB (short PTB (SPTB)) exhibited marked accumulation of APP in Rab5A-labeled early endosomal and recycling compartments, whereas those expressing isoforms with the insertion in the PTB (long PTB (LPTB)) exhibited reduced amounts of cellular APP and its proteolytic derivatives relative to parental control cells. Neither the activities of thebeta- and gamma-secretases nor the expression of APP mRNA were significantly different in the stably transfected cells, suggesting that the differential effects of the Numb proteins on APP metabolism is likely to be secondary to altered APP trafficking. In addition, the expression of SPTB-Numb increases at the expense of LPTB-Numb in neuronal cultures subjected to stress, suggesting a role for Numb in stress-induced Abeta production. Taken together, these results suggest distinct roles for the human Numb isoforms in APP metabolism and may provide a novel potential link between altered Numb isoform expression and increased Abeta generation.     

The Discovery of orally available thrombin inhibitors : Studies towards the optimisation of CGH1668

The chemical optimisation of CGH1668 1 is described employing an in vivo model of absorption to determine the influence on bioavailability of single point modifications to five key molecular templates. The discovery of an orally bioavailable and selective thrombin inhibitor, 24, highlights the utility of this approach.