Chondroitin sulfate synthesis by mouse embryonic, extraembryonic, and teratoma cells in vitro

Sulfated glycosaminoglycan (GAG) synthesis by primary cultures of embryo, yolk sac, and trophoblast was compared with synthesis by the same tissues in utero. In general, the in vivo and in vitro results were in good agreement. As was the case in vivo, the three tissues synthesized chondroitin-4-sulfate and chondroitin-6-sulfate (but no dematan sulfate) at characteristic ratios.Cultured embryos are already capable of synthesizing chondroitin sulfates, primarily chondroitin-4-sulfate, before, or at, the 64-cell stage. During the attachment and initiation of outgrowth stages, blastocysts synthesize more chondroitin-6-sulfate than chondroitin-4-sulfate. Thereafter, progressively more chondroitin-4-sulfate is synthesized so that the 4:6 ratio increases, resembling that of trophoblast cells.Blastocyst-derived cell lines and teratoma cell cultures were also studied. One blastocyst-derived line, MB4, synthesized GAG with a pattern similar to that of yolk sac, which it resembles biochemically in other respects as well. The GAG profile of MB2, a parietal endoderm-like cell line resembled neither that of embryo, yolk sac, nor trophoblast cells. Embryonal carcinoma (undifferentiated teratoma) cells had a chondroitin sulfate pattern different from that of most of the other cultures.     

Composition of cartilage from lysozyme-deficient rabbits

Costal and auricular cartilage obtained from mutant rabbits exhibiting lysozyme deficiency has been found to be identical to similar tissue from control animals in a variety of biochemical parameters. These data seriously question the putative role of lysozyme as a structural component of cartilage.     

Hydra: software for tailored processing of H/D exchange data from MS or tandem MS analyses

Background  

Hydrogen/deuterium exchange mass spectrometry (H/DX-MS) experiments implemented to characterize protein interaction and protein folding generate large quantities of data. Organizing, processing and visualizing data requires an automated solution, particularly when accommodating new tandem mass spectrometry modes for H/DX measurement. We sought to develop software that offers flexibility in defining workflows so as to support exploratory treatments of H/DX-MS data, with a particular focus on the analysis of very large protein systems and the mining of tandem mass spectrometry data.     

Role of the proline-rich motif of bovine leukemia virus transmembrane protein gp30 in viral load and pathogenicity in sheep

The cytoplasmic tail of bovine leukemia virus (BLV) transmembrane protein gp30 has multiple amino acid motifs that mimic those present in signaling proteins associated with B-cell and T-cell receptors. The proline-rich motif of gp30, PX(2)PX(4-5)P, is analogous to the recognition site of Src homology 3 (SH3) domains of signaling molecules. Using site-directed mutagenesis of an infectious molecular clone of BLV, point mutations were introduced which changed three of the prolines of the motif to alanines. The influence of these mutations on the pathogenicity of BLV was studied in sheep which received either (i) plasmid DNA with provirus containing proline-to-alanine mutations (pppBLV), (ii) plasmid DNA with wild-type provirus (wtBLV), or (iii) transfection reagent alone. Although all of the BLV-injected animals seroconverted at approximately the same time, viral loads at later time points were high in five of five of the wtBLV group and two of five of the pppBLV group but low in three of five of the pppBLV group, as determined by semiquantitative PCR. Viral expression was lower in the pppBLV-transfected sheep, as measured by p24 antigen enzyme-linked immunosorbent assay in cultured cells, and serologic titers were lower. Thirty-one months after transfection, four of four wtBLV-transfected sheep had died of leukemia and lymphoma, and all five of the pppBLV-transfected sheep were clinically healthy and had normal peripheral blood lymphocyte counts. These data indicate that the proline-rich motif of gp30 is not required for viral infectivity but is important for high viral load in vivo, suggesting that SH3-mediated gp30 interactions are critical for viral pathogenesis following infection. Absence of interactions with the proline-rich motif may prevent or delay tumorigenesis in sheep.     

Schizophrenia: genome, interrupted

Structural chromosomal variation is increasingly recognized as an important contributor to human diseases, particularly those of neurodevelopment, such as autism. A current paper makes a significant advance to schizophrenia genetics by establishing an association with rare copy number variants (CNV), which are over-represented in neurodevelopmental genes.