The secretory granule protein syncollin localizes to HL-60 cells and neutrophils.

The secretory granule protein syncollin was first identified in the exocrine pancreas where a population of the protein is associated with the luminal surface of the zymogen granule membrane. In this study we provide first morphological and biochemical evidence that, in addition to its pancreatic localization, syncollin is also present in neutrophilic granulocytes of rat and human origin. By immunohistological studies, syncollin was detected in neutrophilic granulocytes of the spleen. Furthermore, syncollin is expressed by the promyelocytic HL-60 cells, where it is stored in azurophilic granules and in a vesicular compartment. These findings were confirmed by fractionation experiments and immunoelectron microscopy. Treatment with a phorbol ester triggered the release of syncollin indicating that in HL-60 cells it is a secretory protein that can be mobilized upon stimulation. A putative role for syncollin in host defense is discussed.     

Julius Sachs (1832–1897) and the Unity of Life

In 1865, the German botanist Julius Sachs published a seminal monograph entitled Experimental-Physiologie der Pflanzen (Experimental Physiology of Plants) and hence became the founder of a new scientific discipline that originated 150 y ago. Here, we outline the significance of the achievements of Sachs. In addition, we document, with reference to his Vorlesungen über Pflanzen-Physiologie (Lectures on the Physiology of Plants, 1882), that Sachs was one of the first experimentalists who proposed the functional unity of all organisms alive today (humans, animals, plants and other “vegetable” organisms, such as algae, cyanophyceae, fungi, myxomycetes, and bacteria).     

The origin of chloroplasts: Constantin S. Merezhkowsky (1855–1921) and symbiogenesis

Journal of Plant Biochemistry and Biotechnology - One century ago (Jan. 9, 1921), the Russian biologist Constantin S. Merezhkowsky, who proposed the endosymbiotic origin of plastids, committed...     

Mitochondrial haplogroups, control region polymorphisms and malignant melanoma: a study in middle European Caucasians

Background

Because mitochondria play an essential role in energy metabolism, generation of reactive oxygen species (ROS), and apoptosis, sequence variation in the mitochondrial genome has been postulated to be a contributing factor to the etiology of multifactorial age-related diseases, including cancer. The aim of the present study was to compare the frequencies of mitochondrial DNA (mtDNA) haplogroups as well as control region (CR) polymorphisms of patients with malignant melanoma (n = 351) versus those of healthy controls (n = 1598) in Middle Europe.

Methodology and Principal Findings

Using primer extension analysis and DNA sequencing, we identified all nine major European mitochondrial haplogroups and known CR polymorphisms. The frequencies of the major mitochondrial haplogroups did not differ significantly between patients and control subjects, whereas the frequencies of the one another linked CR polymorphisms A16183C, T16189C, C16192T, C16270T and T195C were significantly higher in patients with melanoma compared to the controls. Regarding clinical characteristics of the patient cohort, none of the nine major European haplogroups was associated with either Breslow thickness or distant metastasis. The CR polymorphisms A302CC-insertion and T310C-insertion were significantly associated with mean Breslow thickness, whereas the CR polymorphism T16519C was associated with metastasis.

Conclusions and Significance

Our results suggest that mtDNA variations could be involved in melanoma etiology and pathogenesis, although the functional consequence of CR polymorphisms remains to be elucidated.     

Annuithrin,a new biologically active germacranolide from Helianthus annuus

Investigations on growth inhibition in Helianthus annuus led to the isolation of a new sesquiterpene lactone, a germacranolide with an α-methylene-γ-lactone moiety. The structure of this new germacranolide, annuithrin, was elucidated by spectroscopic methods. Its biological activity has been proven by growth inhibition in straight growth tests, antibacterial tests and inhibition of DNA-/RNA-synthesis in cells of the ascitic form of Ehrlich carcinoma.     

The Arabidopsis Kinome: phylogeny and evolutionary insights into functional diversification

Background

Protein kinases constitute a particularly large protein family in Arabidopsis with important functions in cellular signal transduction networks. At the same time Arabidopsis is a model plant with high frequencies of gene duplications. Here, we have conducted a systematic analysis of the Arabidopsis kinase complement, the kinome, with particular focus on gene duplication events. We matched Arabidopsis proteins to a Hidden-Markov Model of eukaryotic kinases and computed a phylogeny of 942 Arabidopsis protein kinase domains and mapped their origin by gene duplication.

Results

The phylogeny showed two major clades of receptor kinases and soluble kinases, each of which was divided into functional subclades. Based on this phylogeny, association of yet uncharacterized kinases to families was possible which extended functional annotation of unknowns. Classification of gene duplications within these protein kinases revealed that representatives of cytosolic subfamilies showed a tendency to maintain segmentally duplicated genes, while some subfamilies of the receptor kinases were enriched for tandem duplicates. Although functional diversification is observed throughout most subfamilies, some instances of functional conservation among genes transposed from the same ancestor were observed. In general, a significant enrichment of essential genes was found among genes encoding for protein kinases.

Conclusions

The inferred phylogeny allowed classification and annotation of yet uncharacterized kinases. The prediction and analysis of syntenic blocks and duplication events within gene families of interest can be used to link functional biology to insights from an evolutionary viewpoint. The approach undertaken here can be applied to any gene family in any organism with an annotated genome.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-548) contains supplementary material, which is available to authorized users.     

Molecular phylogeny of selected predaceous leeches with reference to the evolution of body size and terrestrialism

The phylogenetic relationships of erpobdellid leeches collected throughout Europe were investigated using newly obtained mitochondrial cytochrome c oxidase subunit I (CO-I) gene sequence data from 10 taxa. Monophyly of the five European Erpobdella species (sub-family Erpobdellinae) was supported, but a newly discovered leech, E. wuttkeit Kutschera, 2004 (the smallest member of its genus, discovered in an aquarium) was only distantly related to this clade. Three members of the semiaquatic Trochetinae were included in this study. The largest European leech species discovered so far, Trocheta haskonis Grosser, 2000, was found to be a terrestrial predator that feeds on earthworms. The rare species T. haskonis is the sister taxon of T. bykowskii Gedroyc, 1913, a well-known amphibious leech. Based on a comparison of body sizes and a phylogenetic tree the evolution of terrestrialism in the family Erpobdellidae is discussed.     

Microscopic contributions to the pressure-volume diagram of the cell-water relations as demonstrated with tissue cells

Summary Continuing microscopic studies on cell-water relations with single cells (Gerdenitsch 1979) based on the relationship between the osmotic potential and the cell water volume, tissue cells were investigated. The experiments were done with inner epidermis of the bulb scale of onion (Allium cepa) which seemed to be most suitable for those investigations. Using a diagram described byRichter (1978) pressure volume curves of cells at the margin of the epidermis pieces neighboured by a various amount of dead cells and of cells in the center of tissue were worked out. They were contributed to one of three groups according to their amount of free surface (group 1: >1/3 free surface, group 2: <1/3 free surface, group 3: cells surrounded only by living-cells). Curves of the mean values of each of the three groups were compared as well as the mean -values, calculated as a measure for the elasticity of the cell wall.It was found that cells surrounded only by living cells had -values less than with both other groups. Assuming from observations during the experiments that all cells had very similar properties, this difference could be attributed to the expression of the effect of tissue counterpressure.     

Cytoskeletal Components Define Protein Location to Membrane Microdomains

The plasma membrane is an important compartment that undergoes dynamic changes in composition upon external or internal stimuli. The dynamic subcompartmentation of proteins in ordered low-density (DRM) and disordered high-density (DSM) membrane phases is hypothesized to require interactions with cytoskeletal components. Here, we systematically analyzed the effects of actin or tubulin disruption on the distribution of proteins between membrane density phases. We used a proteomic screen to identify candidate proteins with altered submembrane location, followed by biochemical or cell biological characterization in Arabidopsis thaliana. We found that several proteins, such as plasma membrane ATPases, receptor kinases, or remorins resulted in a differential distribution between membrane density phases upon cytoskeletal disruption. Moreover, in most cases, contrasting effects were observed: Disruption of actin filaments largely led to a redistribution of proteins from DRM to DSM membrane fractions while disruption of tubulins resulted in general depletion of proteins from the membranes. We conclude that actin filaments are necessary for dynamic movement of proteins between different membrane phases and that microtubules are not necessarily important for formation of microdomains as such, but rather they may control the protein amount present in the membrane phases.Living cells need borders and molecular compartments for biochemical reactions and storage of metabolites. The plasma membrane therefore is a prerequisite for the evolution of different life forms. It consists of a phospholipid bilayer into which proteins and special lipid species such as sterols, sphingolipids, and glycolipids are inserted. The first complex model of plasma membrane was proposed in 1972 by Jonathan Singer and Garth Nicolson (1), replacing the concept of the plasma membrane as a strict protein–lipid–protein sandwich that was generally accepted until then. In Singer and Nicolson''s model, the cell membrane is a two-dimensionally oriented viscous solution in which the membrane constituents are orientated in the most thermodynamically favorable manner, hiding hydrophobic hydrocarbon chains inside the lipid bilayer and exposing polar and ionic groups to the aqueous phase. This fluid mosaic model also implied that membrane proteins as well as lipid components are distributed in a homogeneous lipid bilayer at long range, but they can form specific aggregates and phases at short range, which were also termed “lipid rafts” or membrane microdomains.Over the past 30 years, it has become evident that the plasma membrane is not such a homogeneous structure as it was initially proposed. We now know that the lipid bilayer is asymmetric (2) and that the free diffusion of membrane proteins is restricted by their interactions with intracellular and extracellular components (3). More recently, Simons and Ikonen suggested that large ordered phases, enriched with cholesterol and sphingolipids, emerge within the plasma membrane and that they function as platforms for enrichment of certain proteins while excluding others (4). This current membrane model suggests that the mixture of sterols and polar lipids within the plasma membrane can appear in two distinct phases: liquid disordered (L_d) and liquid ordered (L_o) phase (5). In this view, the so-called membrane microdomains are considered to be part of the L_o phase. Based on work on model membranes, it is suggested that lateral segregation of components into L_d and L_o phases occurs spontaneously (6) with the self-associating properties between sterols and highly saturated hydrocarbon chains of phopsho- and sphingolipids as the main driving force (7). Additionally, it is suggested that also specific lipid-protein and protein-protein interactions are essential for the formations of membrane domains as well as for stabilization of smaller nanodomains which subsequently may cause formation of larger platforms. In contrast to the animal cells, in plants these membrane microdomains seem to be rather immobile (8), possibly due to their attachment to the outer cell wall. More recently, it became obvious that membrane microdomains within a single cell are highly diverse and of different compositions (9). Generally, in the plant model, organisms'' plasma membrane microdomains turned out to be important in plant defense (10, 11), cell polarity (12, 13), and general signaling properties of the plasma membrane (14, 15).The cytoskeleton was identified as an essential cellular component with important roles in membrane topography, bordering, trafficking, and organelle movement (16). Single particle tracking in mammalian cells revealed that the transferrin receptor and macroglobulin receptor demonstrate normal Brownian diffusion but only within a specific membrane compartment (17). Two hypothetical models were proposed in order to explain this phenomenon (supplemental Fig. 1). Direct interactions between transmembrane proteins and cytoskeleton are suggested to creates a barrier, called “fence,” where cytosolic parts of transmembrane proteins collides with cytoskeletal components, limiting their diffusion to certain areas. These molecules can jump over the “fence” to a neighboring compartment, possibly due to the dynamic nature of the interaction of membrane proteins and cytoskeleton, where they are again temporally trapped (17). This phenomenon was recently described also in A. thaliana where the interplay between membrane microdomains and microtubules plays a role in secondary cell wall formation (reviewed in (18)). The second model assumes, additionally, that particular transmembrane proteins are anchored to and lined up along cytoskeleton and act as “pickets” to arrest free diffusion of other membrane components, including nontransmembrane proteins, within the enclosed compartment (19).For plants, the composition of these sterol-rich membranes phases was analyzed in several biochemical studies (14, 20–22). Thereby, low-density preparations of plasma membrane fractions after treatment with nonionic detergents (DRM¹ fractions) were considered as a biochemical representation enriched in cellular membrane ordered phases or microdomains. Proteomic studies in mammalian cells consistently reported that the DRM fraction is highly enriched with several cytoskeletal proteins such as actin, tubulin, myosin, dynamin, actinin, and supervillin (23–25). Additionally, the level of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a lipid connecting the plasma membrane to actin filaments, was also significantly elevated in DRM preparations (26). Treatment with microtubule and actin depolymerizing agent results in drastic loss of many signaling proteins from these DRM fractions prepared from adult rat cardiac myocytes (27) or human embryonic retinal cells (28).Based on this knowledge, we propose two hypothetical models for the relationship between cytoskeleton and membrane microdomains for plant cells: (i) Actin filaments and microtubules could be important in the membrane phase separation or formation of the membrane microdomains themselves. In this case, disruption of the cytoskeleton would cause a lack of phase segregation in the plasma membrane. (ii) The cytoskeleton is only important for the incorporation of specific protein into the sterol-enriched regions but not for the general formation of these phase separations. This view implies that phase separations or membrane microdomains would still be present after cytoskeleton disruption but their protein composition can be different. Another possible scenario is (iii) that cytoskeletal elements serve as anchors for membrane microdomains at particular position in the plasma membrane, so the absence of these anchors would cause the increased mobility of microdomains (supplemental Fig. 1).The primary aim of this study was to characterize the interplay between cytoskeletal components and different membrane phases (microdomains) in A. thaliana suspension cell cultures. To reach this goal, biochemical and proteomic approaches were combined with confocal microscopy and activity assays measuring the influence of actin or tubulin disruption on the composition, localization, and biochemical properties of the sterol-enriched membrane microdomains. Thereby, for biochemical analyses, low-density detergent-resistant membrane fractions are analyzed as containing cellular sterol-rich membrane compartments.