Genome-wide analysis of the invertase gene family from maize

Key message

The recent release of the maize genome (AGPv4) contains annotation errors of invertase genes and therefore the enzymes are bestly curated manually at the protein level in a comprehensible fashion

Abstract

The synthesis, transport and degradation of sucrose are determining factors for biomass allocation and yield of crop plants. Invertase (INV) is a key enzyme of carbon metabolism in both source and sink tissues. Current releases of the maize genome correctly annotates only two vacuolar invertases (ivr1 and ivr2) and four cell wall invertases (incw1, incw2 (mn1), incw3, and incw4). Our comprehensive survey identified 21 INV isogenes for which we propose a standard nomenclature grouped phylogenetically by amino acid similarity: three vacuolar (INVVR), eight cell wall (INVCW), and ten alkaline/neutral (INVAN) isogenes which form separate dendogram branches due to distinct molecular features. The acidic enzymes were curated for the presence of the DPN tripeptide which is coded by one of the smallest exons reported in plants. Particular attention was placed on the molecular role of INV in vascular tissues such as the nodes, internodes, leaf sheath, husk leaves and roots. We report the expression profile of most members of the maize INV family in nine tissues in two developmental stages, R1 and R3. INVCW7, INVVR2, INVAN8, INVAN9, INVAN10, and INVAN3 displayed the highest absolute expressions in most tissues. INVVR3, INVCW5, INVCW8, and INVAN1 showed low mRNA levels. Expressions of most INVs were repressed from stage R1 to R3, except for INVCW7 which increased significantly in all tissues after flowering. The mRNA levels of INVCW7 in the vegetative stem correlated with a higher transport rate of assimilates from leaves to the cob which led to starch accumulation and growth of the female reproductive organs.

     

The inhibition of sphingomyelin synthase 1 activity induces collecting duct cells to lose their epithelial phenotype

Epithelial tissue requires that cells attach to each other and to the extracellular matrix by the assembly of adherens junctions (AJ) and focal adhesions (FA) respectively. We have previously shown that, in renal papillary collecting duct (CD) cells, both AJ and FA are located in sphingomyelin (SM)-enriched plasma membrane microdomains. In the present work, we investigated the involvement of SM metabolism in the preservation of the epithelial cell phenotype and tissue organization. To this end, primary cultures of renal papillary CD cells were performed. Cultured cells preserved the fully differentiated epithelial phenotype as reflected by the presence of primary cilia. Cells were then incubated for 24 h with increasing concentrations of D609, a SM synthase (SMS) inhibitor. Knock-down experiments silencing SMS 1 and 2 were also performed. By combining biochemical and immunofluorescence studies, we found experimental evidences suggesting that, in CD cells, SMS 1 activity is essential for the preservation of cell-cell adhesion structures and therefore for the maintenance of CD tissue/tubular organization. The inhibition of SMS 1 activity induced CD cells to lose their epithelial phenotype and to undergo an epithelial-mesenchymal transition (EMT) process.     

Untersuchungen Zur Eosinophilie Hyalinen Knorpels

Zusammenfassung Während der chemischen Fixierung von Geweben und der nachfolgenden Behandlung in Alkoholreihen geht Hämoglobin in Lösung und diffundiert in das Gewebe. Die Diffusion des Hämoglobins ist besonders gut in der Grundsubstanz hyaliner Knorpel zu verfolgen. Das eingedrungene Hämoglobin wurde mit der Ultramikrospektrographie nachgewiesen. Die Hämoglobindiffusion läßt sich durch die Kryostatschnittechnik und durch eine Fixierung in 4%igem Formalin mit Zusatz von 2,5% Ferricyankalium verhindern bzw. mit Zusatz von Natriumchlorid oder Phosphat zu Formalin einschränken. Besonders säurehaltige Fixierungslösungen trennen die Häm- von der Globinkomponente. Der Globinanteil verbleibt in der Grundsubstanz des Knorpels und kann das Vorliegen eines ortsständigen Eiweiß-körpers vortäuschen. Die Einlagerung des vollständigen Hämoglobins oder des Globins allein bedingen die diffuse Eosinophilie der Grundsubstanz im fixierten Knorpel und blockiert die Darstellung der sauren Mucopolysaccharide (Alcianblaufärbung) sowie die metachromatische Reaktion der Grundsubstanz.

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Summary In the course of chemical fixation of tissues and the subsequent treatment with alcohol hemoglobin dissolves and diffuses into the tissue. The diffusion of hemoglobin can be observed particularly well in the ground substance of hyaline cartilage. There the hemoglobin is demonstrable by means of ultramicrospectrography. The diffusion of the hemoglobin can be prevented through the use of the cryostat technique and fixation in 4% formalin containing 2.5% ferricyankalium, NaCl or phosphate. Acid containing fixation media separate the hem from the globin component. The globin remains in the ground substance of the cartilage and may be mistaken for a sessil protein. The storage of either the complete hemoglobin molecule or the globin fraction causes the diffuse eosinophily in the ground substance of fixed cartilage which also blocks the determination of acid mucopolysaccharides (alcian blue staining method) as well as the metachromatic reaction of the ground substance.

     

Expression and function of synaptotagmin VII in CTLs

The Ca(2+) sensor synaptotagmin (Syt) VII regulates the exocytosis of conventional lysosomes in several cell types. In CTLs, the Ca(2+)-regulated exocytosis of lytic granules/secretory lysosomes is responsible for the perforin/granzyme-mediated lysis of target cells. To investigate the role of Syt VII in CTL effector function, the expression and function of Syt VII were examined in wild-type and Syt VII-deficient mice. In comparison with Syt VII(+/+) controls, Syt VII(-/-) animals were impaired in their ability to clear an infection with the intracellular pathogen Listeria monocytogenes. When isolated CTLs were examined, we found that Syt VII is expressed upon CTL activation and localizes to granzyme A-containing lytic granules. Syt VII-deficient CTLs have no defects in proliferation and cytokine production, and their lytic granules contain normal amounts of perforin and granzyme A and polarize normally at the immunological synapse. However, despite normal conjugate formation with target cells, CTLs from Syt VII(-/-) mice exhibit reduced effector activity, when compared with controls. Treatment of Syt VII(+/+) or Syt VII(-/-) CTLs with an inhibitor of the perforin-mediated lytic pathway resulted in comparable levels of cytotoxic activity, suggesting that Syt VII regulates perforin-mediated cytolytic CTL responses.     

Karyotypic changes detected by comparative genomic hybridization in a stillborn infant with chorioangioma and liver hemangioma

BACKGROUND: Placental hemangioma (chorioangioma) and congenital hemangioma are relatively common tumors, which on rare occasions may occur together. Very little is known about the pathogenetic mechanisms underlying these lesions. CASE: Herein we describe a rare case of a stillborn infant with chorioangioma, placental mesenchymal dysplasia, and liver cavernous hemangioma. In addition, we present the findings of the karyotype analysis of these lesions, which was done with the bacterial artificial chromosome arrays using the comparative genomic hybridization method. The chromosomal abnormalities that we found were deletions at 2q13 and 7p21.1 and were common to both placental and liver lesions. CONCLUSIONS: None of the identified chromosomal aberrations have been previously associated with chorioangiomas or hemangiomas. Important genes that lie in these DNA regions may be implicated in the pathogenesis of congenital hemangiomas and mesenchymal dysplasia.     

aCGH local copy number aberrations associated with overall copy number genomic instability in colorectal cancer: coordinate involvement of the regions including BCR and ABL

In order to identify small regions of the genome whose specific copy number alteration is associated with high genomic instability in the form of overall genome-wide copy number aberrations, we have analyzed array-based comparative genomic hybridization (aCGH) data from 33 sporadic colorectal carcinomas. Copy number changes of a small number of specific regions were significantly correlated with elevated overall amplifications and deletions scattered throughout the entire genome. One significant region at 9q34 includes the c-ABL gene. Another region spanning 22q11-q13 includes the breakpoint cluster region (BCR) of the Philadelphia chromosome. Coordinate 22q11-q13 alterations were observed in 9 of 11 tumors with the 9q34 alteration. Additional regions on 1q and 14q were associated with overall genome-wide copy number changes, while copy number aberrations on chromosome 7p, 7q, and 13q21.1-q31.3 were found associated with this instability only in tumors from patients with a smoking history. Our analysis demonstrates there are a small number of regions of the genome where gain or loss is commonly associated with a tumor's overall level of copy number aberrations. Our finding BCR and ABL located within two of the instability-associated regions, and the involvement of these two regions occurring coordinately, suggests a system akin to the BCR-ABL translocation of CML may be involved in genomic instability in about one-third of human colorectal carcinomas.     

Synthesis and structure-activity relationship of 4-(2-aryl-cyclopropylamino)-quinoline-3-carbonitriles as EGFR tyrosine kinase inhibitors

Synthesis and structure-activity relationship of a series of 4-(2-aryl-cyclopropylamino)-quinoline-3-carbonitrile derivatives as EGFR inhibitors is described. Compounds 29 and 30 showed potent in vitro inhibitory activity in the enzymatic assay as well as in the functional cellular assay. They are moderately selective against other types of tyrosine kinases.     

Cloning and functional characterization of the Anopheles albimanus DMT1/NRAMP homolog: implications in iron metabolism in mosquitoes

In addition to its wide role in metabolism, iron in insects has been implicated in vitellogenesis and the immune response. The NRAMP family comprises a well-conserved family of divalent cation transporters in metazoans. To gain insight on the role of NRAMP in Anopheles albimanus, we cloned a cDNA encoding a 571-residue protein (AnaNRAMP) with the structural features defining the NRAMP family. AnaNRAMP mRNA induced (59)Fe(2+) incorporation when injected into Xenopus oocytes. Western blot analysis revealed that AnaNRAMP is expressed in the head, midgut and at high levels in Malpighian tubules of unfed female mosquito. Upon blood feeding, AnaNRAMP levels were reduced in the midgut whereas they increased in the Malpighian tubules. Using immuno-localization by transmission electron microscopy, AnaNRAMP was localized in the membrane of the intra-cellular concretions or spherites of the Malpighian tubule principal cells. Taken together, our results suggest an important role of AnaNRAMP in iron transport and indicate a role of the mosquito Malpighian tubule as an important organ for iron homeostasis.