A new 28 amino acid peptide, we recently isolated from the venom of the bumblebee Megabombus pennsylvanicus. has been characterized. The peptide, Met-Cys-Ile-Cys-Lys-Asn-Gly-Lys-Pro-Leu-Pro-Gly-Phe-Ile-Gly-Lys-Ile-Cys- Arg-Lys-Ile-Cys-Met-Met-Gln-Gln-Thr-His(NH2), has been named bumblebee mast cell degranulating (MCD) peptide due to its ability to degranulate rat peritoneal mast cells, and its resemblance to the bee venom MCD peptide. Bumblebee MCD peptide, unlike bombolitins, the other mast cell degranulating heptadecapeptides of bumblebee venom, is not lytic and releases histamine at a dose as low as 0.05 micrograms/ml (1.6 X 10(-8) M).

Background: Natural variation in protein output from translation in bacteria and archaea may be an organism-specific property of the ribosome. This paper adopts a systems approach to model the protein output as a measure of specific ribosome reactive properties in a ribosome-mediated translation apparatus. We use the steady-state assumption to define a transition state complex for the ribosome, coupled with mRNA, tRNA, amino acids and reaction factors, as a subsystem that allows a focus on the completed translational output as a measure of specific properties of the ribosome.

A mathematical model of cluster patterns for mapped genes with known phenotypes in Escherichia coli predicted thatfunctional genes may account for a maximum of two-thirds of the total chromosomal space. The corollary prediction was that one-third of the chromosome comprised noncoding space. Open reading frame (ORF) analyses for 15 phylogenetically diverse bacterial genomes and for 30 fully sequenced prokaryotic genomes supported the gene cluster model prediction of a two-thirds tendency for coding space. Our results suggest that only 3-4% of unassigned ORFs in E. coli represent genes with potential phenotype and that ORFs marking novel genes in prokaryotes are far fewer than previously thought.

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