Glucose catabolism by Thiobacillus A2 grown in chemostat culture under carbon or nitrogen limitation

Thiobacillus A2 was grown in glucose- or ammonium-limited chemostats and relative contributions of the Embden-Meyerhof (EM), Entner-Doudoroff (ED) and pentose phosphate (PP) pathways to glucose catabolism estimated by ¹⁴C-glucose radiorespirometry. In fast growing strain GFI, the EM pathway predominated (41–79%) under all growth conditions with the PP pathway contributing 18–30%. The ED pathway was apparently absent under some conditions of glucose limitation. In contrast, wild type Thiobacillus A2 exhibited predominance of the EM pathway (43–48%) under ammonium-limitation but apparent predominance of the PP pathway (43–55%) under glucose-limitation, although all three pathways were calculated to operate. Under some conditions of glucose limitation the EM pathway was possibly considerably depressed. No clear pattern of response of the three pathways to altered environmental conditions could be deduced, although marked change in pathway activities were obviously induced. Growth yield was apparently unaffected by variation in pathways. The problems of interpreting such complex radiorespirometric data are discussed.Abbreviations EM Embden-Meyerhof - ED Entner-Doudoroff - KDPG 2-keto-3-deoxy-6-phosphogluconate - 6-PG 6-phosphogluconate - PK phosphoketolase - PP pentose phosphate     

Double abdomen induction with low UV-doses inSmittia spec. (Chironomidae,diptera): Sensitive period and complete photoreversibility

Summary In embryos of the chironomid midgeSmittia spec., UV-irradiation of anterior pole regions results in double abdomen formation. In this abnormal body pattern, head and thorax are replaced by a mirror image of the abdomen. Irradiation at a particular stage between nuclear migration and blastoderm formation, and with the anterior pole facing the UV-beam, yields 100% double abdomens after a minimum UV-dose (140 J·m^–2 at 285 nm wavelength). By subsequent exposure to light of longer wavelength, embryos can be reprogrammed so that they develop normally again. The irradiation procedure described is suitable for programming large numbers of embryos for double abdomen formation, with a minimum of side effects and virtually complete photoreversibility.     

The optic lobe of Drosophila melanogaster

Summary We present a quantitative evaluation of Golgiimpregnated columnar neurons in the optic lobe of wildtype Drosophila melanogaster. This analysis reveals the overall connectivity pattern between the 10 neuropil layers of the medulla and demonstrates the existence of at least three major visual pathways. Pathway 1 connects medulla layer M10 to the lobula plate. Input layers of this pathway are M1 and M5. Pathway 2 connects M9 to shallow layers of the lobula, which in turn are tightly linked to the lobula plate. This pathway gets major input via M2. Pathways 1 and 2 receive input from retinula cells R1-6, either via the lamina monopolar cell L1 (terminating in M1 and M5) or via L2 and T1 (terminating in M2). Neurons of these pathways typically have small dendritic fields. We discuss evidence that pathways 1 and 2 may play a major role in motion detection. Pathway 3 connects M8 to deep layers of the lobula. In M8 information converges that is derived either from M3 (pathway 3a) or from M4 and M6 (pathway 3b), layers that get their major input from L3 and R8 or L4 and R7, respectively. Some neurons of pathway 3 have large dendritic fields. We suggest that they may be involved in the computation of form and colour. Possible analogies to the organization of pathways in the visual system of vertebrates are discussed.During the final editing of this work our friend A.P.M. Dittrich was tragically killed in an accident. Without him this and the previous work would never have been completed     

Transneuronal uptake of horseradish peroxidase in the central nervous system of dipterous insects

Summary Horseradish peroxidase (HRP) applied to lesioned neurons in the retina and thoracic ganglia of the flies Musca, Calliphora and Drosophila labeled axon terminals, dendrites and perikarya of the severed neurons after anterograde or retrograde passage. In addition, HRP reaction product secondarily labeled intact neurons that are contiguous with injured nerve cells. In many cases labeling of optic lobe neurons remote from primarily filled ones was also seen (here called tertiary labeling). HRP labeling was extensive and both primarily and transneuronally filled neurons could be resolved in almost as much detail as Golgi-impregnated or cobalt-silver-labeled cells. Electron microscopy showed that in both primarily and secondarily filled neurons, reaction product was distributed diffusely in the cytoplasm.Transneuronal uptake of HRP was specific to certain types of neurons in the brain and thus displayed certain pathways. The pathways resolved by transneuronal labeling with HRP extend from the optic lobes to the thoracic ganglia and include visual neurons previously identified electrophysiologically and anatomically.Transneuronal HRP uptake, although believed to occur in vivo, could not be shown to be dependent on synaptic activity. Three other heme peptides tested were taken up by injured neurons, but showed no transneuronal labeling: lactoperoxidase, cytochrome c, and microperoxidase.     

cAMP-dependent protein kinase inhibits the mitogenic action of vascular endothelial growth factor and fibroblast growth factor in capillary endothelial cells by blocking Raf activation

Proliferation of endothelial cells is regulated by angiogenic and antiangiogenic factors whose actions are mediated by complex interactions of multiple signaling pathways. Both vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) stimulate cell proliferation and activate the mitogen-activated protein kinase (MAPK) cascade in bovine brain capillary endothelial (BBE) cells. We have extended these findings to show that both mitogens activate MAPK via stimulation of Raf-1. Activation of Raf/MAPK is inhibited by increasing intracellular cAMP levels pharmacologically or via stimulation of endogenously expressed β-adrenergic receptors. Both VEGF- and bFGF-induced Raf-1 activity are blocked in the presence of forskolin or 8-bromo-cAMP by 80%. The actions of increased cAMP appear to be mediated by cAMP-dependent protein kinase (PKA), since treatment with H-89, a the specific inhibitor of PKA, reversed the inhibitory effect of elevated cAMP levels on mitogen-induced cell proliferation and Raf/MAPK activation. Moreover, elevations in cAMP/PKA activity inhibit mitogen-induced cell proliferation. These findings demonstrate, in cultured endothelial cells, that the cAMP/PKA signaling pathway is potentially an important physiological inhibitor of mitogen activation of the MAPK cascade and cell proliferation. J. Cell. Biochem. 67:353–366, 1997. © 1997 Wiley-Liss, Inc.     

SMAD4 contributes to chondrocyte and osteocyte development

Different cellular and molecular mechanisms contribute to chondrocyte and osteocyte development. Although vital roles of the mothers against decapentaplegic homolog 4 (also called ‘SMAD4’) have been discussed in different cancers and stem cell‐related studies, there are a few reviews summarizing the roles of this protein in the skeletal development and bone homeostasis. In order to fill this gap, we discuss the critical roles of SMAD4 in the skeletal development. To this end, we review the different signalling pathways and also how SMAD4 defines stem cell features. We also elaborate how the epigenetic factors—ie DNA methylation, histone modifications and noncoding RNAs—make a contribution to the chondrocyte and osteocyte development. To better grasp the important roles of SMAD4 in the cartilage and bone development, we also review the genotype‐phenotype correlation in animal models. This review helps us to understand the importance of the SMAD4 in the chondrocyte and bone development and the potential applications for therapeutic goals.     

IL-1β in atherosclerotic vascular calcification: From bench to bedside

Atherosclerotic vascular calcification contributes to increased risk of death in patients with cardiovascular diseases. Assessing the type and severity of inflammation is crucial in the treatment of numerous cardiovascular conditions. IL-1β, a potent proinflammatory cytokine, plays diverse roles in the pathogenesis of atherosclerotic vascular calcification. Several large-scale, population cohort trials have shown that the incidence of cardiovascular events is clinically reduced by the administration of anti-IL-1β therapy. Anti-IL-1β therapy might reduce the incidence of cardiovascular events by affecting atherosclerotic vascular calcification, but the mechanism underlying this effect remains unclear. In this review, we summarize current knowledge on the role of IL-1β in atherosclerotic vascular calcification, and describe the latest results reported in clinical trials evaluating anti-IL-1β therapies for the treatment of cardiovascular diseases. This review will aid in improving current understanding of the pathophysiological roles of IL-1β and mechanisms underlying its activity.     

MicroRNA-196a promotes renal cancer cell migration and invasion by targeting BRAM1 to regulate SMAD and MAPK signaling pathways

Rationale: MicroRNAs (miRNAs) are endogenous ~22nt RNAs that play critical regulatory roles in various biological and pathological processes, including various cancers. Their function in renal cancer has not been fully elucidated. It has been reported that miR-196a can act as oncogenes or as tumor suppressors depending on their target genes. However, the molecular target for miR-196a and the underlying mechanism in miR-196a promoted cell migration and invasion in renal cancer is still not clear.Methods: The expression, survival and correlation between miR-196a and BRAM1 were investigated using TCGA analysis and validated by RT-PCR and western blot. To visualize the effect of Bram1 on tumor metastasis in vivo, NOD-SCID gamma (NSG) mice were intravenously injected with RCC4 cells (10⁶ cells/mouse) or RCC4 overexpressing Bram1. In addition, cell proliferation assays, migration and invasion assays were performed to examine the role of miR-196a in renal cells in vitro. Furthermore, immunoprecipitation was done to explore the binding targets of Bram1.Results: TCGA gene expression data from renal clear cell carcinoma patients showed a lower level of Bram1 expression in patients'' specimens compared to adjacent normal tissues. Moreover, Kaplan‑Meier survival data clearly show that high expression of Bram1correlates to poor prognosis in renal carcinoma patients. Our mouse metastasis model confirmed that Bram1 overexpression resulted in an inhibition in tumor metastasis. Target-prediction analysis and dual-luciferase reporter assay demonstrated that Bram1 is a direct target of miR-196a in renal cells. Further, our in vitro functional assays revealed that miR-196a promotes renal cell proliferation, migration, and invasion. Rescue of Bram1 expression reversed miR-196a-induced cell migration. MiR-196a promotes renal cancer cell migration by directly targeting Bram1 and inhibits Smad1/5/8 phosphorylation and MAPK pathways through BMPR1A and EGFR.Conclusions: Our findings thus provide a new mechanism on the oncogenic role of miR-196a and the tumor-suppressive role of Bram1 in renal cancer cells. Dysregulated miR-196a and Bram1 represent potential prognostic biomarkers and may have therapeutic applications in renal cancer.     

How do introduction characteristics influence the invasion success of Mediterranean alien plants?

Invasive plant species are becoming increasingly widespread following accelerated anthropogenic activity in the Mediterranean region. Humans have played a central role in the expansion process, and it is important to incorporate such considerations into management plans. Using generalized linear models, our first aim was to describe how the invasion success of 862 prominent alien plant species on Mediterranean islands is related to characteristics of the introduction process: introduction frequency, date and region of origin, range size and purpose of import. The importance of each was measured by the numbers of species present and their average invasiveness. The main findings were: (a) accidental imports and ornamentals accounted for a high proportion of all aliens, although neither group had particularly high average invasiveness; (b) introduction frequency had a comparatively modest influence, with the most commonly-introduced species naturalized only three times more widely than those rarely-introduced; (c) rates of species introduction appear to have increased dramatically in the last century, although aliens which have been present in the region for more than 200 years were most widespread, indicating that it may be centuries before some species fill their potential range; (d) there were small tendencies for successful invaders to originate in the Neotropics or in regions with Mediterranean climate biomes and to have large range sizes. Our second aim was to determine whether the number or average invasiveness of species introduced via a given pathway had the most influence on the overall probability of invasion on a given island. An elasticity analysis suggested that the number of species was substantially the best predictor of the two. This finding arises largely because invasion events are rare and remain unpredictable, and has significant implications for assessing invasion risk. We discuss how substantial sources of error and intrinsic variability in invasiveness within species groups limit the potential for developing accurate risk models.