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Biomedical subjects

S G Velleman

Publications and source records attributed to S G Velleman.

6 recordsLinked to original sources
PubMed1992

The cartilage proteoglycan deficient mutation, nanomelia, contains a DNA polymorphism in the proteoglycan core protein gene that is genetically linked to the nanomelia phenotype.

The avian mutation, nanomelia (nm), is an autosomal recessive embryonic lethal. Homozygous embryos show hypoplasia of the limbs and a parrot-like beak. Biochemical studies have associated this phenotype with the absence of the major cartilage specific proteoglycan core protein (Argraves et al., 1981). Stirpe et al. (1987) demonstrated a reduction in core protein transcripts in nanomelic embryos. Southern analyses did not detect a rearrangement of the core protein gene or a restriction fragment length polymorphism (RFLP) in the core protein gene linked to the nanomelia mutation. These data suggest that the genetic lesion associated with the nanomelia mutation is either a subtle alteration in the core protein gene affecting the biosynthesis of core protein transcript or a defect in a regulatory gene that produces a trans-acting factor requisite for the proper expression of the core protein gene. To distinguish between these two alternative molecular mechanisms for the nanomelia mutation, experiments were conducted to demonstrate genetic linkage or non-linkage of the core protein gene to the nanomelia mutation. Using denaturing gradient gel electrophoresis (DGGE) technology, a DNA polymorphism has been identified at the 3' end of the core protein gene. The polymorphism defines two alleles, one allele is associated with the normal core protein gene, while the other allele always segregates with the nanomelia mutation. These results suggest that the identified DNA polymorphism in the core protein gene is genetically linked to the inheritance of the nanomelic phenotype and the nanomelia mutation contains a lesion in the core protein gene.

Aggrecans↗
PubMed1989

Identification and distribution of a proctolin-like neuropeptide in the nervous system of the gypsy moth, Lymantria dispar, and in other Lepidoptera.

Although the neuropeptide proctolin has important functions in many arthropods, it is reported to be absent in Lepidoptera. Its possible occurrence in these insects was reinvestigated by bioassays of HPLC fractions and immunocytochemistry. A proctolin-like substance was recovered from the frontal and subesophageal ganglia of Lymantria dispar. This substance has the same chromatographic retention time as proctolin; enzymatic degradation indicates that it is a peptide; it is bound by proctolin antisera; and thus it is indistinguishable from authentic proctolin. A small subpopulation of proctolin-like immunoreactive (PLI) neurons was stained in the larval CNS of L. dispar, Manduca sexta, Trichoplusia ni, Galleria mellonella, and Vanessa cardui. Most prominent of these cells are median neurosecretory neurons in the brain, paired neurons in the frontal ganglion, two clusters of neurons in the subesophageal ganglion, paired lateral neurons in the thoracic ganglia, and dorsomedial neurons in the abdominal ganglia. Also, varicose PLI axons are found in the corpora cardiaca and perivisceral organs. In L. dispar, PLI cells also were found in the corpora cardiaca. The results of this study indicate that proctolin is of general occurrence in the Lepidoptera, that it has an important role in the stomatogastric nervous system, and that it may be released as a local neurohormone from various neurohemal organs.

Animals↗
PubMed1983

The independent synthesis and secretion of cartilage proteoglycan and link protein by embryonic chicken chondrocytes.

The synthesis of cartilage link proteins was studied in organ cultures of sterna from normal and nanomelic chick embryos. Nanomelic chondrocytes synthesize cartilage-specific proteoglycans at 1 to 2% of normal levels, and therefore, nanomelic cartilage contains very little proteoglycan aggregate. The defect in proteoglycan synthesis results from a reduced availability of proteoglycan core protein. Link protein synthesis was monitored by the incorporation of [35S]cysteine into protein. Radiolabeled proteins were extracted from cartilage in 4 M guanidine hydrochloride and separated from proteoglycan monomer by centrifugation in dissociative cesium chloride density equilibrium gradients. The top one-sixth (D6) fraction of these gradients contained link protein and was used to extract one unlabeled normal sternum. These extracts were dialyzed to conditions permitting the formation of proteoglycan aggregates and chromatographed on controlled pore glass (CPG 2500). Proteoglycan aggregates chromatograph in the void volume (V0) of these columns. Radioactivity eluting in the CPG 2500 (V0 from normal and nanomelic D6 fractions was identified as link protein by polyacrylamide gel electrophoresis in sodium dodecyl sulfate and subsequent fluorography. Link proteins were also extracted from unlabeled cartilages and identified by the Western blotting technique using link-specific antiserum. Immunoprecipitation of [35S]cysteine-labeled link protein from normal and nanomelic D6 fractions indicated that nanomelic chondrocytes synthesize link protein at normal levels.

Animals↗