A novel succinyl dipeptide stimulates directed cell migration by modulating protein kinase C activity

In determining the mechanism of the chemokinetic action of the thiol protease inhibitor, E-64, in endothelial cell monolayers subjected to wounding, we synthesized succinyl-leucyl-agmatine (SLA), an analogue of E-64 that lacked the epoxy group and protease inhibitory effect. We observed that this analogue retained its chemokinetic effect on wounded endothelial cells. Its stimulatory action on endothelial cell polarization response to wounding was rapid and associated with directed cell migration. Furthermore, its effect on cellular polarization was blocked by protein kinase C (PKC) inhibitors and mimicked by pharmacologic agents that stimulated PKC activity. To determine if SLA's chemokinetic action was mediated by protein kinase C activation, we compared the effects of SLA and the tumor promoter phorbol myristate acetate (PMA) on the translocation of PKC activity in endothelial cells. We observed that both SLA and PMA induced the translocation of PKC activity from the cytosolic to the particulate fraction of the cells. We also observed that both SLA and PMA induced the phosphorylation of two proteins (Mr 23.4 and 36.5 kDa) in intact 32P-labeled cells. Thus, SLA stimulates the endothelial cell locomotor response to wounding by stimulating PKC activity.     

The tomato early fruit specific gene <Emphasis Type="Italic">Lefsm1</Emphasis> defines a novel class of plant-specific SANT/MYB domain proteins

We describe here a novel plant-specific gene, Lefsm1 (fruit SANT/MYB-like 1) harboring a single SANT/MYB domain. The expression of Lefsm1 is specific to the very early stages of tomato (Lycopersicon esculentum) fruit development. Ectopic expression of Lefsm1 results in severe developmental alterations manifested in retarded growth, and reduced apical dominance during tomato and Arabidopsis seedling development. A promoter sequence residing 1.0 kb upstream to the translation initiation codon confers the organ-specific expression of the gene. Lefsm1 belongs to a novel small gene family consisting of five to six members in tomato, Arabidopsis and rice. The SANT/MYB domain of LeFSM1 and its orthologs in Arabidopsis and rice differs from that of all other plant or animal MYB proteins and from the SANT domains found in part of the chromatin remodeling proteins. Together, our results indicate that Lefsm1 is a founding member of a small family of proteins containing a novel MYB/SANT domain which is likely to participate in the regulation of a plant-specific developmental program.     

Hypothetical Outcome Plots Outperform Error Bars and Violin Plots for Inferences about Reliability of Variable Ordering

Many visual depictions of probability distributions, such as error bars, are difficult for users to accurately interpret. We present and study an alternative representation, Hypothetical Outcome Plots (HOPs), that animates a finite set of individual draws. In contrast to the statistical background required to interpret many static representations of distributions, HOPs require relatively little background knowledge to interpret. Instead, HOPs enables viewers to infer properties of the distribution using mental processes like counting and integration. We conducted an experiment comparing HOPs to error bars and violin plots. With HOPs, people made much more accurate judgments about plots of two and three quantities. Accuracy was similar with all three representations for most questions about distributions of a single quantity.     

PHB3 Maintains Root Stem Cell Niche Identity through ROS-Responsive AP2/ERF Transcription Factors in Arabidopsis

1. Download high-res image (166KB)
2. Download full-size image

     

A note on the role of african states in committee I of UNCLOS III

Abstract

This study assesses the role the African states played in the formulation of Part XI of the U.N. Convention on the Law of the Sea. It demonstrates that the clauses dealing with the seabed issues largely incorporated their interests. It is also argued that it was because of the African states’ efforts (among other members of the G‐77) that the industrialized countries acquiesced in the negotiation of a comprehensive LOS Treaty.     

Recursive construction of perfect DNA molecules from imperfect oligonucleotides

Making faultless complex objects from potentially faulty building blocks is a fundamental challenge in computer engineering, nanotechnology and synthetic biology. Here, we show for the first time how recursion can be used to address this challenge and demonstrate a recursive procedure that constructs error‐free DNA molecules and their libraries from error‐prone oligonucleotides. Divide and Conquer (D&C), the quintessential recursive problem‐solving technique, is applied in silico to divide the target DNA sequence into overlapping oligonucleotides short enough to be synthesized directly, albeit with errors; error‐prone oligonucleotides are recursively combined in vitro, forming error‐prone DNA molecules; error‐free fragments of these molecules are then identified, extracted and used as new, typically longer and more accurate, inputs to another iteration of the recursive construction procedure; the entire process repeats until an error‐free target molecule is formed. Our recursive construction procedure surpasses existing methods for de novo DNA synthesis in speed, precision, amenability to automation, ease of combining synthetic and natural DNA fragments, and ability to construct designer DNA libraries. It thus provides a novel and robust foundation for the design and construction of synthetic biological molecules and organisms.     

Cell lineage analysis of the mammalian female germline

Fundamental aspects of embryonic and post-natal development, including maintenance of the mammalian female germline, are largely unknown. Here we employ a retrospective, phylogenetic-based method for reconstructing cell lineage trees utilizing somatic mutations accumulated in microsatellites, to study female germline dynamics in mice. Reconstructed cell lineage trees can be used to estimate lineage relationships between different cell types, as well as cell depth (number of cell divisions since the zygote). We show that, in the reconstructed mouse cell lineage trees, oocytes form clusters that are separate from hematopoietic and mesenchymal stem cells, both in young and old mice, indicating that these populations belong to distinct lineages. Furthermore, while cumulus cells sampled from different ovarian follicles are distinctly clustered on the reconstructed trees, oocytes from the left and right ovaries are not, suggesting a mixing of their progenitor pools. We also observed an increase in oocyte depth with mouse age, which can be explained either by depth-guided selection of oocytes for ovulation or by post-natal renewal. Overall, our study sheds light on substantial novel aspects of female germline preservation and development.