Variation in the growth of the preweaning Syrian hamster (Cricetus auratus)

An assessment of the growth rate spectrum based on a longitudinal weight study of golden hamsters was undertaken over the preweaning period. The period covered 23 days with data probes at 24-hourly intervals and encompassed 16 litters providing a birth number of 120 young and a weaning survival number of 82. Subsequent analysis directed initially at the pooled or averaged data showed sex differences with males gaining weight faster than females. Further analysis showed the total period to have three definitive break-points and therefore four phases of growth activity. The segmented linear regression line calculations showed that the phasic duration of males in the second and third phases were two days later than the females. Following data-analysis adjustments and taken into account aberrations of the sample, final indications pointed to the preweaning hamster growth spectrum as quadrophasic, exhibiting a stable first phase, a second and third phase terminating earlier in females and a final weaning weight being heavier in males. The growth curves demonstrated a 'U' shaped outline and formed an integral part of hamster preweaning precocity.     

Cell culture and in vitro studies of fresh and cryopreserved human insulinoma

Summary Dispersed cells from both fresh and cryopreserved human insulinoma have been maintained in cell culture. Initial yield of viable cells was 50% for fresh and 25% for cryopreserved tissue. Viability of cells in culture was documented by increasing numbers of cells (doubling time approximately 5 d initially and 2 d at the sixth subculture for both fresh and cryopreserved tissue) and continued release of insulin over time (approximately 100 ng/ml per 10⁵ cells at 10 d and 175 ng/ml per 10⁵ cells at 30 d of culture for both fresh and cryopreserved tissue). Evidence that cells growing in culture were beta cells was provided by: (a) recovery of intracellular and extracellular immunoreactive insulin (IRI), (b) electron microscopic morphology, and (c) immunohistochemical staining. Cells from fresh insulinoma incubated with increasing concentrations of extracellular glucose released increasing amounts of IRI up to approximately 15 mM glucose, which paralleled changes in plasma insulin obtained during a preoperative glucose tolerance test. Under an Intergovernmental Personnel Act Exchange from the Department of Surgery, University of California, Davis, Sacramento Medical Center.     

Glycosyl conjugates of biotinylated diaminopyridine applied for study of carbohydrate-to-carbohydrate interaction

Previous studies by us and others established that cell-cell adhesion is mediated by specific carbohydrate-to-carbohydrate interaction (CCI). Those previous studies were based on various biochemical and biophysical approaches, including the use of labeled glycosyl epitopes with fluorescent tag. However, these methods ideally require that the glycosyl epitope must be fixed to a solid phase molecule, preferably with multivalency. The purpose of the present study is to establish a CCI process using specific glycosyl residues conjugated to biotinylated diaminopyridine (BAP), and to observe: (i) clear occurrence of homotypic CCI between “Os Fr.B” having 5–6 GlcNAc termini, vs. absence of such homotypic CCI between “Os Fr.1” having 2 GlcNAc termini; (ii) occurrence of heterotypic CCI between GM3 ganglioside and Os Fr.B, vs. absence of such heterotypic CCI between GM3 and Os Fr.1. Interaction between Os Fr.B-BAP conjugate and Os Fr.B-ceramide mimetic (Os Fr.B-mCer) was demonstrated based on two experiments: (i) dose-dependent binding of Os Fr.B-BAP conjugate to polystyrene plates coated with Os Fr.B-mCer was observed in the presence of bivalent cation, a prerequisite for all CCI processes, and such binding was abolished by EDTA; (ii) binding between equal nanomolar Os Fr.B-BAP and Os Fr.B-mCer was inhibited by mM concentration Os Fr.B without conjugate, in dose-dependent manner. Thus, cell adhesion processes based on homotypic CCI between N-linked glycans having multiple GlcNAc termini, and heterotypic CCI between GM3 and such glycans, were clearly observed using BAP conjugates of glycosyl epitopes.     

Secretion of Recombinant Pediocin PA-1 by Bifidobacterium longum, Using the Signal Sequence for Bifidobacterial α-Amylase

A recombinant DNA, encoding the chimeric protein of the signal sequence for bifidobacterial α-amylase mature pediocin PA-1, was introduced into Bifidobacterium longum MG1. Biologically active pediocin PA-1 was successfully secreted from the strain and showed bactericidal activity against Listeria monocytogenes and the same molecular mass as native pediocin PA-1.     

A novel array-based assay of in situ tissue transglutaminase activity in human umbilical vein endothelial cells

Transglutaminases (TGs), a family of calcium-dependent transamidating enzymes, are involved in functions such as apoptosis and inflammation and play a role in autoimmune diseases and neurodegenerative disorders. In this study, we describe a novel array-based approach to rapidly determine in situ TG activity in human umbilical vein endothelial cells and J82 human bladder carcinoma cells. Amine arrays were fabricated by immobilizing 3-aminopropyltrimethoxysilane on glass slides. The assay was specific and highly reproducible. The average coefficient of variation betweens spots was 2.6% (n = 3 arrays), and the average correlation coefficients between arrays and between arrays/reactions were 0.998 and 0.976, respectively (n = 3 arrays). The assay was successfully applied to detect changes in TG activity induced by maitotoxin and to analyze inhibition of the TG activation with cystamine and monodansyl cadaverine. In addition, the assay demonstrated that intracellular reactive oxygen species regulate the maitotoxin-induced activation of TG. Thus, the array-based in situ TG activity assay constitutes a rapid and high-throughput approach to investigating the roles of TGs in cell signaling.     

Two novel loci underlie natural differences in Caenorhabditis elegans abamectin responses

Parasitic nematodes cause a massive worldwide burden on human health along with a loss of livestock and agriculture productivity. Anthelmintics have been widely successful in treating parasitic nematodes. However, resistance is increasing, and little is known about the molecular and genetic causes of resistance for most of these drugs. The free-living roundworm Caenorhabditis elegans provides a tractable model to identify genes that underlie resistance. Unlike parasitic nematodes, C. elegans is easy to maintain in the laboratory, has a complete and well annotated genome, and has many genetic tools. Using a combination of wild isolates and a panel of recombinant inbred lines constructed from crosses of two genetically and phenotypically divergent strains, we identified three genomic regions on chromosome V that underlie natural differences in response to the macrocyclic lactone (ML) abamectin. One locus was identified previously and encodes an alpha subunit of a glutamate-gated chloride channel (glc-1). Here, we validate and narrow two novel loci using near-isogenic lines. Additionally, we generate a list of prioritized candidate genes identified in C. elegans and in the parasite Haemonchus contortus by comparison of ML resistance loci. These genes could represent previously unidentified resistance genes shared across nematode species and should be evaluated in the future. Our work highlights the advantages of using C. elegans as a model to better understand ML resistance in parasitic nematodes.