Genetic interaction of BBS1 mutations with alleles at other BBS loci can result in non-Mendelian Bardet-Biedl syndrome

Bardet-Biedl syndrome is a genetically and clinically heterogeneous disorder caused by mutations in at least seven loci (BBS1-7), five of which are cloned (BBS1, BBS2, BBS4, BBS6, and BBS7). Genetic and mutational analyses have indicated that, in some families, a combination of three mutant alleles at two loci (triallelic inheritance) is necessary for pathogenesis. To date, four of the five known BBS loci have been implicated in this mode of oligogenic disease transmission. We present a comprehensive analysis of the spectrum, distribution, and involvement in non-Mendelian trait transmission of mutant alleles in BBS1, the most common BBS locus. Analyses of 259 independent families segregating a BBS phenotype indicate that BBS1 participates in complex inheritance and that, in different families, mutations in BBS1 can interact genetically with mutations at each of the other known BBS genes, as well as at unknown loci, to cause the phenotype. Consistent with this model, we identified homozygous M390R alleles, the most frequent BBS1 mutation, in asymptomatic individuals in two families. Moreover, our statistical analyses indicate that the prevalence of the M390R allele in the general population is consistent with an oligogenic rather than a recessive model of disease transmission. The distribution of BBS oligogenic alleles also indicates that all BBS loci might interact genetically with each other, but some genes, especially BBS2 and BBS6, are more likely to participate in triallelic inheritance, suggesting a variable ability of the BBS proteins to interact genetically with each other.     

Extended rat liver slice survival and stability monitored using clinical biomarkers

Precision-cut liver slices are reportedly limited as toxicity models by their short half-life in culture. We used traditional clinical chemistry biomarkers and histology to assess a newer procedure for improved liver slice maintenance. Slices from Sprague-Dawley rat livers were well maintained in a roller culture system for up to 10 days based on protein content (60-70% or higher of initial values) and biomarker retention and verified by histological examination of the tissues showing morphological integrity and viability of hepatocyte and biliary regions. Exposure of the slices to geldanamycin (GEL) resulted in loss of slice LDH and transaminase content, with associated depression in ALP and GGT levels and elevated bilirubin, indicating that GEL affects both cell types as occurs in vivo with this hepatobiliary toxicant. Thus, we conclude that liver slices merit further investigation as a general model for chronic as well as acute toxicity studies.     

Galectin-1 interacts with beta-1 subunit of integrin

Galectin-1, a beta-galactoside-binding dimeric lectin, is involved in adhesion, migration, and proliferation of vascular smooth muscle cells (SMC), the key steps in the development of atherosclerosis and restenosis. Here we investigated the molecular basis of the interactions between galectin-1 and SMCs. Galectin-1 modulated SMC attachment in a dose- and beta-galactoside-dependent manner. Direct binding of galectin-1 to beta1 integrin was detected by the immune precipitation of beta1 integrin after chemical cross-linking of 125I-labelled galectin-1 to the cell surface proteins. Galectin-1 transiently increased availability of beta1 integrins on the cell surface to antibodies against beta1 integrin. Incubation of SMCs with galectin-1 transiently increased the amount of the active form of beta1 integrin and tyrosine phosphorylation of two cytoskeleton-associated proteins; one of them coincided with focal adhesion kinase (FAK). Galectin-1 is likely to affect SMC adhesion by interacting with beta1 integrin on the cell surface of SMCs and inducing outside-in signalling.     

In-situ near infrared spectroscopy to monitor key analytes in mammalian cell cultivation

The use of in-situ near infrared spectroscopy (NIRS) as a tool for monitoring four key analytes in a CHO-K1 animal cell culture was investigated. Previous work using on-line NIRS to monitor bioprocesses has involved its application ex-situ where the analyzer is physically outside the fermentor, or to microbial bioprocesses. This novel application of NIRS to monitor analytes within an animal cell culture using a steam sterilizable in-situ fiber optic probe is very important for furthering the use of NIRS within the bioprocessing industry. The method of calibration used to develop the models involved the use of large data sets so that all likely variation in stoichiometry was incorporated within the models. Successful models for glucose, lactate, glutamine, and ammonia were built with Standard Error of Predictions (SEP's) of 0.072 (g/L), 0.0144 (g/L), 0.308 (mM), and 0.036 (mM), respectively of the total concentration range.     

Fluorescent labeling of endothelial cells allows in vivo,continuous characterization of the vascular development of Xenopus laevis

Appropriate blood supply and vascular development are necessary in development and in cancer, heart disease, and diabetes. Here, we report the use of DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL) to label endothelial cells and characterize the vasculature of live Xenopus embryos. The atlas we have created provides a detailed map of normal vascular development against which perturbations of normal patterning can be compared. By following the development of the intersomitic vessels in real-time, we show that, while rostrocaudal gradient of maturing intersomitic vessels occurs, it is not absolute. In addition, the comparative study of the ontogeny of nerve bundles from the spinal cord of transgenic Xenopus embryos expressing green fluorescent protein in the nervous system and blood vessels demonstrates a strong anatomical correlation in neurovascular development. These studies provide the basis for understanding how the vascular system forms and assumes its complicated stereotypical pattern in normal development and in disease.     

Supramolecular organization in streptococcal pericellular capsules is based on hyaluronan tertiary structures

Supramolecular organization involving a polyanionic glycan in a bacterial capsule (hyaluronan, HA, in streptococcal capsules) is revealed, for the first time, by electron-histochemical methodology previously used to elucidate ultrastructure in extracellular matrix. Capsular HA filaments thereby revealed closely resemble aligned linear structures demonstrated by similar technology in HA solution. These parallel arrays, spontaneously formed, are based on HA tertiary structures (beta sheet-like) which are stabilized by hydrophobic and hydrogen bonds. HA tertiary structures in aqueous solutions resist shear stress as shown by rheo-NMR. Thus, supramolecular HA wrapping covering many cells probably stabilizes chains of bacteria. Streptococci possibly templated the ordered structures since eukaryotic B6 cell HA did not produce similarly organized envelopes. Supramolecular organization in streptococcal and pneumococcal capsules are compared. Their glycans are very similar but the potential for HA-like tertiary structures is not present in the pneumococcal type 3 polysaccharide and chains of cells are not formed to the same extent by pneumococci. We suggest that the streptococcal capsule exemplifies a simple extracellular matrix analogous to those in animal connective tissues, which contain glycans (chondroitin, keratan, and dermochondan sulfates) of the HA family, capable of undergoing aggregation to similar tertiary structures.