Invasion of the dwarf honeybee Apis florea into the near East

The dwarf honeybee, Apis florae, is an open nesting honeybee typical to Southern Asia. In the past decades it has been accidentally introduced by man to East Africa and the Arabian Peninsula where the species established sustainable and expanding populations. Recently it has also been introduced to Aqaba and Eilat, where it has also established expanding populations. We here study the genetic structure of this invasive population with nine microsatellite DNA markers to reconstruct the invasion history. The population shows indications of an extreme bottleneck suggesting that it established itself very recently and may have originated from a single introduced colony only. The impact of the species for both apiculture and conservation of biodiversity is discussed.     

Spatial and temporal variation in diets of the crabs <Emphasis Type="Italic">Metopograpsus frontalis</Emphasis> (Grapsidae) and <Emphasis Type="Italic">Perisesarma bidens</Emphasis> (Sesarmidae): implications for mangrove food webs

The diets of the mangrove crabs, Metopograpsus frontalis Miers and Perisesarma bidens de Haan, were investigated monthly for 13 months at two Hong Kong mangroves, to examine possible spatial and temporal influences on their feeding ecology. In both species, a higher degree of gut fullness was observed in summer (May–September) than in winter, suggesting a reduction in winter foraging activity. M. frontalis was omnivorous, with animal and plant materials and inorganic sediments being the major food items. P. bidens was detritivorous, with plant materials and inorganic sediment dominating the gut contents. M. frontalis is, therefore, an opportunistic feeder, whilst P. bidens, like many other members of the Sesarmidae, is a detritivore. Some degree of seasonal variation was shown in the diet of M. frontalis (with more algal material in winter) and P. bidens (with more sediments in summer), but diets were similar between sexes in both species. The dietary pattern of M. frontalis also varied between sites. The diets of the crabs, therefore, appear to be a result of the interplay between the seasonal, physical climate and biological factors, especially food availability and the crabs’ ecology. Results suggest that the predatory role of Metopograpsus, which has been poorly studied, is potentially important to estuarine food webs; whilst the trophic importance of sesarmid crabs, such as Perisesarma, especially in mangrove outwelling, should be critically re-evaluated.     

Absence of adipose differentiation related protein upregulates hepatic VLDL secretion,relieves hepatosteatosis,and improves whole body insulin resistance in leptin-deficient mice

We previously showed that adipose differentiation related protein (Adfp)-deficient mice display a 60% reduction in hepatic triglyceride (TG) content. In this study, we investigated the role of ADFP in lipid and glucose homeostasis in a genetic obesity model, Lep^ob/ob mice. We bred Adfp^−/− mice with Lep^ob/ob mice to create Lep^ob/ob/Adfp^−/− and Lep^ob/ob/Adfp^+/+ mice and analyzed the hepatic lipids, lipid droplet (LD) morphology, LD protein composition and distribution, lipogenic gene expression, and VLDL secretion, as well as insulin sensitivity of the two groups of mice. Compared with Lep^ob/ob/Adfp^+/+ mice, Lep^ob/ob/Adfp^−/− mice displayed an increased VLDL secretion rate, a 25% reduction in hepatic TG associated with improvement in fatty liver grossly and microscopically with a change of the size of LDs in a proportion of the hepatocytes and a redistribution of major LD-associated proteins from the cytoplasmic compartment to the LD surface. There was no detectable change in lipogenic gene expression. Lep^ob/ob/Adfp^−/− mice also had improved glucose tolerance and insulin sensitivity in both liver and muscle. The alteration of LD size in the liver of Lep^ob/ob/Adfp^−/− mice despite the relocation of other LDPs to the LD indicates a nonredundant role for ADFP in determining the size and distribution of hepatic LDs.     

Selective Enhancement of Donor Hematopoietic Cell Engraftment by the CXCR4 Antagonist AMD3100 in a Mouse Transplantation Model

The interaction between stromal cell-derived factor-1 (SDF-1) with CXCR4 chemokine receptors plays an important role in hematopoiesis following hematopoietic stem cell transplantation. We examined the efficacy of post transplant administration of a specific CXCR4 antagonist (AMD3100) in improving animal survival and in enhancing donor hematopoietic cell engraftment using a congeneic mouse transplantation model. AMD3100 was administered subcutaneously at 5 mg/kg body weight 3 times a week beginning at day +2 post-transplant. Post-transplant administration of AMD3100 significantly improves animal survival. AMD3100 reduces pro-inflammatory cytokine/chemokine production. Furthermore, post transplant administration of AMD3100 selectively enhances donor cell engraftment and promotes recovery of all donor cell lineages (myeloid cells, T and B lymphocytes, erythrocytes and platelets). This enhancement results from a combined effect of increased marrow niche availability and greater cell division induced by AMD3100. Our studies shed new lights into the biological roles of SDF-1/CXCR4 interaction in hematopoietic stem cell engraftment following transplantation and in transplant-related mortality. Our results indicate that AMD3100 provides a novel approach for enhancing hematological recovery following transplantation, and will likely benefit patients undergoing transplantation.     

Intracellular glutathione depletion and reactive oxygen species generation are important in α-hederin-induced apoptosis of P388 cells

alpha-Hederin, a pentacyclic triterpene saponin isolated from the seeds of Nigella sativa, was recently reported to have potent in vivo antitumor activity against LL/2 (Lewis Lung carcinoma) in BDF1 mice. In this study we observed that alpha-hederin caused a dose- and time-dependent increase in apoptosis of murine leukemia P388 cells. In order to evaluate the possible mechanisms for apoptosis, the effects of alpha-hederin on intracellular thiol concentration, including reduced glutathione (GSH), and protein thiols, and the effects of pretreatment with N-acetlycysteine (NAC), a precursor of intracellular GSH synthesis, or buthionine sulfoxime (BSO), a specific inhibitor of intracellular GSH synthesis, on alpha-hederin-induced apoptosis were investigated. It was found that alpha-hederin rapidly depleted intracellular GSH and protein thiols prior to the occurrence of apoptosis. NAC significantly alleviated alpha-hederin-induced apoptosis, while BSO augmented alpha-hederin-induced apoptosis significantly. The depletion of cellular thiols observed after alpha-hederin treatment caused disruption of mitochondrial membrane potential (deltapsi(m)) and subsequently increased the production of reactive oxygen species (ROS) in P388 cells at an early time point. Bongkrekic acid (BA), a ligand of the mitochondrial adenine nucleotide translocator, and cyclosporin (CsA) attenuated the alpha-hederin-induced loss of deltapsi(m), and ROS production. Thus, oxidative stress after alpha-hederin treatment is an important event in alpha-hederin-induced apoptosis. As observed in this study, permeability transition of mitochondrial membrane occurs after depletion of GSH and precedes a state of reactive oxygen species (ROS) generation. Further, we observed that alpha-hederin caused the release of cytochrome c from the mitochondria to cytosol, leading to caspase-3 activation. Our findings thus demonstrate that changes in intracellular thiols and redox status leading to perturbance of mitochondrial functions are important components in the mechanism of alpha-hederin-induced cell death.     

Soluble guanylate cyclases act in neurons exposed to the body fluid to promote C. elegans aggregation behavior

The genome of the nematode Caenorhabditis elegans encodes seven soluble guanylate cyclases (sGCs). In mammals, sGCs function as alpha/beta heterodimers activated by gaseous ligands binding to a haem prosthetic group. The principal activator is nitric oxide, which acts through sGCs to regulate diverse cellular events. In C. elegans the function of sGCs is mysterious: the worm genome does not appear to encode nitric oxide synthase, and all C. elegans sGC subunits are more closely related to mammalian beta than alpha subunits. Here, we show that two of the seven C. elegans sGCs, GCY-35 and GCY-36, promote aggregation behavior. gcy-35 and gcy-36 are expressed in a small number of neurons. These include the body cavity neurons AQR, PQR, and URX, which are directly exposed to the blood equivalent of C. elegans and regulate aggregation behavior. We show that GCY-35 and GCY-36 act as alpha-like and beta-like sGC subunits and that their function in the URX sensory neurons is sufficient for strong nematode aggregation. Neither GCY-35 nor GCY-36 is absolutely required for C. elegans to aggregate. Instead, these molecules may transduce one of several pathways that induce C. elegans to aggregate or may modulate aggregation by responding to cues in C. elegans body fluid.     

Indolizines as novel potent inhibitors of 15-lipoxygenase

15-Lipoxygenase (15-LO) has been implicated in oxidation of low-density lipoproteins (LDL) and this enzyme may be involved in the development of atherosclerosis. We have examined 1-substituted indolizines as possible inhibitors of 15-LO from soy beans and from rabbit reticulocytes. Most compounds studied were significantly more active as inhibitors of 15-LO from soy beans than quercetin. The indolizines were slightly less potent inhibitors of the mammalian enzyme, but we found good correlation between inhibitory activity against both 15-LO enzymes studied. Several of the compounds were only weak DPPH scavengers and they may therefore be regarded as so-called non antioxidant inhibitors of 15-LO.     

Thrombospondin 2 inhibits microvascular endothelial cell proliferation by a caspase-independent mechanism

The matricellular protein thrombospondin 2 (TSP2) regulates a variety of cell-matrix interactions. A prominent feature of TSP2-null mice is increased microvascular density, particularly in connective tissues synthesized after injury. We investigated the cellular basis for the regulation of angiogenesis by TSP2 in cultures of murine and human fibroblasts and endothelial cells. Fibroblasts isolated from murine and human dermis synthesize TSP2 mRNA and secrete significant amounts of immunoreactive TSP2, whereas endothelial cells from mouse lung and human dermis did not synthesize TSP2 mRNA or protein. Recombinant mouse TSP2 inhibited growth of human microvascular endothelial cells (HMVECs) mediated by basic fibroblast growth factor, insulin-like growth factor-1, epidermal growth factor, and vascular endothelial growth factor (VEGF). HMVECs exposed to TSP2 in the presence of these growth factors had a decreased proportion of cells in S and G2/M phases. HMVECs cultured with a combination of basic fibroblast growth factor, insulin-like growth factor-1, and epidermal growth factor displayed an increased proportion of nonviable cells in the presence of TSP2, but the addition of VEGF blocked this TSP2-mediated impairment of cell viability. TSP2-mediated inhibition of DNA synthesis by HMVECs in the presence of VEGF was not affected by the broad-spectrum caspase inhibitor zVAD-fmk. Similar findings were obtained with TSP1. Taken together, these observations indicate that either TSP2 or TSP1 can inhibit HMVEC proliferation by inhibition of cell cycle progression and induction of cell death, but the mechanisms responsible for TSP2-mediated inhibition of cell cycle progression are independent from those leading to cell death.     

The use of Roentgenstereofluorogrammetry to predict the 3-D spatial coordinates of points in low speed events

Imaging technologies such as cine-radiography, cine-MRI, and X-ray stereo photogrammetry have become popular diagnostic tools in biomechanical studies of musculoskeletal systems. However, their widespread use for research purposes has been restricted due to their high cost and somewhat limited availability. In an attempt to develop a reliable low cost system, a dual-fluoroscopic system capable of tracking the 3-D spatial motion of discrete landmark points in real time was developed. A simple methodology was developed to convert the analog fluoroscopic images to digital files for post-processing. A custom computer code based on the principles of X-ray stereo photogrammetry was also developed to predict 3-D coordinates from the 2-D images from the individual flouroscopes. The goal of the current study was to assess the accuracy and resolution of this system by using it to predict the motion of a test point following a known curvilinear trajectory. Our system predicted the time-varying motion and path of the test point within 0.25%. However, the current system is limited to studying low speed events only (max event frequency of 3Hz) due to the limited sampling frequency of the A/D conversion employed here.