Isolation and culture of protoplasts of pigeonpea (Cajanus cajan L.)

Summary High yields of protoplasts were obtained from leaves of aseptically grown plants and calli originated from different explants, in several cultivars of Cajanus cajan L. The protoplasts divided to form cell clusters in modified KM 8p medium and developed to protocolonies after dilution with liquid Caboche's medium within three to four weeks of culture. The protocolonies proliferated to form green calli on solid Caboche's medium. No shoots or plants were obtained.Abbreviations BAP 6-benzylaminopurine - NAA -napthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - Kin kinetin - Zea zeatin - Adn S adenine sulphate - GA ₃ gibberellic acid     

Globin-coding sequences in the nuclear 28S pre-mRNA and in the cytoplasmic RNA of pigeon erythroid cells

The steady-state content of globin-coding sequences in nuclear and cytoplasmic RNA of pigeon erythroid cells was estimated by hybridization in the excess of nuclear 28S RNA and cytoplasmic poly(A) + RNA with [3H]DNA, synthesized on globin mRNA. Sequences of 9S globin mRNA are found in 0.06% of molecules of non-ribosomal 28S nuclear RNA (pre-mRNA) of erythroblasts and in 0.5% of molecules of non-ribosomal 28S nuclear RNA of reticulocytes. The content of globin mRNA in erythroblast cytoplasm is, respectively lower than in that of reticulocytes.     

Mechanical cues in cellular signalling and communication

Multicellular organisms comprise an organized array of individual cells surrounded by a meshwork of biomolecules and fluids. Cells have evolved various ways to communicate with each other, so that they can exchange information and thus fulfil their specified and unique functions. At the same time, cells are also physical entities that are subjected to a variety of local and global mechanical cues arising in the microenvironment. Cells are equipped with several different mechanisms to sense the physical properties of the microenvironment and the mechanical forces arising within it. These mechanical cues can elicit a variety of responses that have been shown to play a crucial role in vivo. In this review, we discuss the current views and understanding of cell mechanics and demonstrate the emerging evidence of the interplay between physiological mechanical cues and cell-cell communication pathways.     

Maternal genomic variability of the wild boar (Sus scrofa) reveals the uniqueness of East‐Caucasian and Central Italian populations

The phylogeography of the European wild boar was mainly determined by postglacial recolonization patterns from Mediterranean refugia after the last ice age. Here we present the first analysis of SNP polymorphism within the complete mtDNA genome of West Russian (n = 8), European (n = 64), and North African (n = 5) wild boar. Our analyses provided evidence of unique lineages in the East‐Caucasian (Dagestan) region and in Central Italy. A phylogenetic analysis revealed that these lineages are basal to the other European mtDNA sequences. We also show close connection between the Western Siberian and Eastern European populations. Also, the North African samples were clustered with the Iberian population. Phylogenetic trees and migration modeling revealed a high proximity of Dagestan sequences to those of Central Italy and suggested possible gene flow between Western Asia and Southern Europe which was not directly related to Northern and Central European lineages. Our results support the presence of old maternal lineages in two Southern glacial refugia (i.e., Caucasus and the Italian peninsula), as a legacy of an ancient wave of colonization of Southern Europe from an Eastern origin.     

Tunneling nanotubes: a new route for the exchange of components between animal cells

Recently, highly sensitive nanotubular structures mediating membrane continuity between mammalian cells have been discovered. With respect to their peculiar architecture, these membrane channels were termed tunneling nanotubes (TNTs). TNTs could form de novo between animal cells leading to the generation of complex cellular networks. They have been shown to facilitate the intercellular transfer of organelles as well as, on a limited scale, of membrane components and cytoplasmic molecules. It has been proposed that TNTs represent a novel and general biological principle of cell-to-cell communication and it becomes increasingly apparent that they fulfill important functions in the physiological processes of multicellular organisms.     

The ability of protein tyrosine phosphatase SHP-1 to suppress NFkappaB can be inhibited by dominant negative mutant of SIRPalpha

In contrast with hematopoietic cells and fibroblasts, which express mainly one form of protein tyrosine phosphatase (PTP) SHP-1 or SHP-2, epithelial cells like A431, HeLa, and 293 express both forms of PTP. These two PTP regulate NFkappaB activity differently; SHP-1 inhibits and SHP-2 stimulates NFkappaB activation. In epithelial cells the process of NFkappaB activation depends on the combination of two PTP activities. The activity of PTP SHP-1 dominates in this tandem according to our data. The signal regulatory protein (SIRPalpha) is the adapter and the substrate of PTP SHP-1 and SHP-2. We investigated the role of SIRPalpha and its dominant negative mutant in PTP activities in 293 cells. The overexpression of wild-type SIRPalpha suppresses the activities of both PTP, but has a stronger effect on PTP SHP-2, especially when this protein is overexpressed in 293 cells. In contrast with wild-type SIRPalpha, its dominant negative mutant acts predominantly against PTP SHP-1, and can be detected in the complex with PTP SHP-1. The expression of dominant negative mutant of SIRPalpha has an effect similar to the expression of dominant negative PTP SHP-1 in the process of NFkappaB activation.     

Crystal structure of a truncated urease accessory protein UreF from Helicobacter pylori

Urease plays a central role in the pathogenesis of Helicobacter pylori in humans. Maturation of this nickel metalloenzyme in bacteria requires the participation of the accessory proteins UreD (termed UreH in H. pylori), UreF, and UreG, which form sequential complexes with the urease apoprotein as well as UreE, a metallochaperone. Here, we describe the crystal structure of C‐terminal truncated UreF from H. pylori (residues 1–233), the first UreF structure to be determined, at 1.55 Å resolution using SAD methods. UreF forms a dimer in vitro and adopts an all‐helical fold congruent with secondary structure prediction. On the basis of evolutionary conservation analysis, the structure reveals a probable binding surface for interaction with other urease components as well as key conserved residues of potential functional relevance. Proteins 2010. © 2010 Wiley‐Liss, Inc.