Chemical and Immunological Analysis of Prey-Derived Vomeronasal Stimulants

Abstract

We have isolated seven proteins from earthworm preparations that are chemoattractive to garter snakes. Three of these proteins have been purified to homogeneity: two from aqueous earthworm wash (EWW) and one from electric shock-induced earthworm secretion (ESS). One of the two highly purified proteins from EWW has a relative molecular mass of 20 kDa and contains free sulfhydryl groups that appear to play a functional role in its chemoattractivity. The other purified protein from EWW has a molecular mass of 3 kDa (low molecular weight protein, LMW). The highly purified chemoattractive protein (ES20) from ESS is a glycoprotein having a minimum molecular mass of 15.4 kDa calculated from its amino acid and carbohydrate contents. It consists of a single polypeptide chain. The sequence of terminal 15 amino acid residues from its amino (NH₂–) terminal has been determined. It binds specifically to the membranes of vomeronasal sensory epithelium in a saturable and reversible fashion with a K_dvalue of about 0.3 µM and B_max value of 0.4 nmol/mg of protein. This protein causes an increase in firing rate of individual neurons in the accessory olfactory bulb of garter snakes, the projection site for vomeronasal neurons. All the isolated chemoattractive proteins from both earthworm preparations can be divided immunologically into three groups: (i) those closely related to the ES20 snake-attractive protein, (ii) those closely related to the LMW snake-attractive protein, and (iii) those unrelated to either ES20 or the LMW protein.

The combined role of the main olfactory and vomeronasal systems in social communication in mammals

“…The vomeronasal system can also detect a wider variety of chemical cues than just pheromones. Snakes have long been know to use their vomeronasal system to detect prey odors (Halpern and Kubie 1980;Wang et al, 1993;Alving and Kardong, 2004) and VSN from mice have been found to respond to a wide variety of odors some of which could be considered food odors (Sam et al, 2001). Hamsters appear to detect and process odors from different species such as mice, rats and cats (Meredith and Westberry, 2004) and possibly some food odors through the vomeronasal system.…”

The Vomeronasal Organ Mediates Interspecies Defensive Behaviors through Detection of Protein Pheromone Homologs

“…In addition to detecting pheromones, VNO neurons have been shown to respond to regular chemical odorants in vitro , but the biological significance of this activity has not been determined (Sam et al, 2001; Trinh and Storm, 2003). In reptiles, the VNO initiates a defensive response to predators and facilitates the tracking of prey (Halpern and Frumin, 1979; Miller and Gutzke, 1999; Wang et al, 1993). In mammals, the identity of kairomones and detecting sensory neurons remains mostly unknown.…”

Cell dynamics in the embryonic and postnatal vomeronasal epithelium of snakes

“…The VNS of snakes has been shown to be important for mediating courtship and mating (as in mammals), aggregation, trailing of conspecifics and prey, prey attack, and ingestion. In addition, a wealth of data has accumulated on the anatomical, physiological, cellular, and molecular details of the ophidian VNS (see Halpern 1992;Jiang and Terashima, 1996;Liu et al, 1997;Luo et al, 1994;Wang et al, 1993Wang et al, , 1997. Development of the VNS is of particular interest in snakes (Holtzman, 1993).…”