Successful establishment of an orthotopic hepatoblastoma in vivo model in NOD/LtSz-scid IL2Rγnull mice

Investigation of hepatoblastoma in experimental conditions contributes relevantly to a detailed understanding of tumor biology and the investigation of new treatment approaches. Most systematical analyses currently use subcutaneous xenografts. We established a reproducible intrahepatic model with the hepatoblastoma-cell lines HuH6 and HepT1. The cells were stably transfected with a plasmid vector encoding for Gaussia luciferase. HuH6 and HepT1 were injected intrasplenically in NOD/LtSz-scid IL2Rγnull mice. Mice were splenectomized in order to avoid intrasplenical tumor growth. Multifocal intrahepatic tumor growth was observed in 85% (11/13) of HuH6 tumors and 55% (5/9) of HepT1 tumors. Serum Alpha-fetoprotein and Gaussia luciferase increased 5 weeks after tumor-cell inoculation. Tumors were detected by MRI at this time point. Immunhistochemical analysis such as vascularity (CD31), proliferation index (Ki-67), cytokeratin 7 and distribution of β-catenin in intrahepatic tumors were different to subcutaneous tumors. We established a reproducible xenograft model for intrahepatic hepatoblastoma growth with a high tumor incidence. Monitoring of tumor cell viability was optimized by measuring GLuc. This model enables further experimental investigations of HB in a more physiological milieu as emphasized by the β-catenin distribution.     

Compensatory evolution for a gene deletion is not limited to its immediate functional network

Background  

Genetic disruption of an important phenotype should favor compensatory mutations that restore the phenotype. If the genetic basis of the phenotype is modular, with a network of interacting genes whose functions are specific to that phenotype, compensatory mutations are expected among the genes of the affected network. This perspective was tested in the bacteriophage T3 using a genome deleted of its DNA ligase gene, disrupting DNA metabolism.     

Isolation and characterization of lactose-binding lectins from the venoms of the snakes Lachesis muta and Dendroaspis jamesonii

Two lectins have been isolated: one from the venom of Lachesis muta (bushmaster lectin) and one from Dendroaspis jamesonii venom (Jameson's mamba lectin). The lectin from bushmaster venom (BML) is similar to the lactose-binding lectins previously isolated from snake venoms (Gartner et al. (1980) FEBS Lett. 117, 13-16; Gartner & Ogilvie (1984) Biochem. J. 224, 301-307) in that it is calcium-dependent, lactose inhibitable, and is a dimer of molecular weight 28,000. In contrast, the lactose-blockable lectin from Jameson's mamba venom (JML) has an apparent molecular weight of 26,000 and agglutinates erythrocytes in the presence of EDTA. The absorption spectra of BML were affected by the binding of calcium, or calcium and lactose to the lectin. However, JML spectra were not affected by these conditions. While the hemagglutination activity of each of the previously described lactose-binding snake venom lectins is inhibited by reducing agent, the activities of BML and JML are not affected by reducing agent. Antiserum against bushmaster lectin cross-reacts with thrombolectin, cottonmouth lectin (CML), rattlesnake lectin (RSL), and copperhead lectin (CuHL) but not lectin from Jameson's mamba venom. This evidence plus a comparison of atomic absorption spectra, isoelectric points and amino acid analyses of the lectins demonstrate that JML and BML are different from thrombolectin, CML, RSL, and CuHL.