Lecture Summaries

LECTURES ONE and THREE
Baldomero M. Olivera, Ph.D.

Natural selection has produced an astounding array of venoms for prey capture. Among the most dangerous
venomous creatures, marine cone snails stand out. Cone snail venoms are potent, deadly to fish and people, and each species makes a venomous cocktail of up to 100 different toxins. The toxins attack the nervous system to cause convulsive shock, paralysis, and sedation. The toxins are highly specific as to the molecular target they recognize, from ion channels to transmitter receptors—a property that has made them useful as research tools, and also excellent candidates for drugs to treat neurological diseases. With over 500 living species of cone snail, each having up to 100 toxins, there are potentially over 50,000 novel molecules with drug potential. The basic research and medical value of a diverse group of animals like the cone snails is a powerful reminder of what we can gain and learn from biodiversity. Venomous relatives of the cone snails, the turrid snails, possess similar venoms, but there are over 10,000 known species of turrids, representing a million compounds with potential pharmacological value.

LECTURES TWO and FOUR
Bonnie L. Bassler, Ph.D.

A count of the cells, and associated genes, that comprise a human body, reveals that we are mostly bacterial. Bacteria live in and on us in complex communities that outnumber the cells of our own tissues. These bacteria possess a sophisticated communication mechanism that allows them to coordinate their activities to do certain things when they have strength in numbers. The mechanism, called quorum sensing, was first described in bioluminescent bacteria living symbiotically in a squid, to simulate moonlight for squid camouflage. The key to quorum sensing is a molecular signal released by the bacteria that is monitored by receptors which in turn modulate gene expression. With few bacteria, the signal concentration is low, and the genes of the bioluminescent pathway are not expressed. At higher population density, the high concentration of the signal turns on the bioluminescence genes. Pathogenic bacteria also use quorum sensing to launch a simultaneous attack when in sufficient numbers. Subverting quorum sensing to prevent coordinated attacks is a promising approach for developing new anti-microbial drugs.

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