Opossums

Although no consistently effective chemical repellent has been developed for vertebrate pests, some promising materials have been tested as repellents that are based on predator avoidance, specifically compounds from the secretions of predators. In 1995, synthetic sulfur compounds (two thietanes, a thiolane, and a substituted methyl sulfide, which were originally identified from the anal glands of the stoat, ferret, and red fox) suppressed browsing by the introduced AustraUan bmsh-tail opossum in New Zealand about as well as FEP (83). Suggestions were made that these compounds can be made more effective by the use of bitter compounds in a cocktail. 

Leptospira icterohaemorrhagiae is the cause of a type of jaundice in humans called Weil s disease. The disease is carried by rats and is encountered in sewer workers. Other species of Leptospira, with hosts ranging from domestic animals such as the pig to wild animals such as opossums and jackals, give rise to a variety of fevers encountered locally or widely across the world. 

A possible alternative is the microvillous part of the chemosensory epithelium in the Organ of Rodolfo-Masera (Septal Organ), which is VN-like (Taniguchi etal., 1993). This mixed receptor population requires much further study since it could prove to have intermediate odourant sensitivities (Giannetti et al., 1995). Its distribution and function(s) are still incompletely known however it is sufficiently widespread, from Opossums to Rodents, to warrant an intensive survey (Rodolfo-Masera, 1943 Kratzing, 1978 Giannetti et al., 1992 and 1995). 

The early VN neurones migrate by various routes and in mammals become organised into two layers, each with distinct functional attributes (Chaps. 2 and 6). Amongst marsupials, the sensory cells of an opossum appear at about one-week post-conception (Jia and Halpem, 1998). Despite their extremely altricial developmental pattern, the bandicoots dendrites produce sensory processes (Fig. 4.5) on the lumenal border of the VNO at 35 days postnatal, which in the Northern Bandicoot (Isoodon macrourus) is about 50% of pouch life (Kratzing, 1986). 

In opossums, the migration from the proliferative layer shows a two-day lag between entry of neuroblasts to the lower zone (Go), with... 

Several studies have identified responses that do not involve VN participation, from marsupials to Mouse-lemurs. Where the chosen endpoint is totally unaffected by absence of the organ and in addition is dependent upon MOS activity, then it needs to be classified as VN-independent. Where VN-x results are ambiguous, as already considered for opossums (Monodelphis domestica), further analysis is desirable. For instance, Goats do not use AOS input for mating, only urinalysis, although experiential variables have not been fully explored (Ladewig et al., 1980). Examples of VN independence then exist in both altricial and precocial species. 

Brunjes P.C., Jazaeri A. and Sutherland M.J. (1992). Olfactory bulb organization and development in Monodelphis domestica, the Grey Short-tailed Opossum. J Comp Neurol 320, 544-554. 

Cummings D., Knsab B. and Brunjes P. (1997). Effects of unilateral olfactory deprivation in the developing opossum Monodelphis domestica. J Neurobiol 33, 429-438. 

Fadem B.H. (1989). The effects of pheromonal stimuli on estrus and peripheral plasma estradiol in female gray short-tailed opossums. Biol Reprod 41, 213-217. 

Halpem M., Shapiro L.S. and Jia C.P. (1995). Differential localisation of G-proteins in opossum vomeronasal system. Brain Res 677, 157-161. 

Holmes D. (1992). Odors as cues for orientation to mothers by weanling Virginia Opossums. J Chem Ecol 18, 2251-2259. 

Jackson L.M. and Harder J.D. (1996). Vomeronasal organ removal blocks pheromonal induction of estrus in Gray Short-tailed Opossums (Monodelphis domestica). Biol Reprod 54, 506-512. 

Jia C. and Halpem M. (1998). Neurogensis and migration of receptor neurons in the vomeronasal sensory epithelium of the Opossum Monodelphis domestica. J Comp Neurol 400, 287-297. 

MacCotter R.E. (1912). The connection of the vomeronasal nerves with the accessory olfactory bulb in the Opossum and other mammals. Anat Rec 6, 299-318. 

Martinez-Marcos A. and Halpem M. (1999b). Differential projections from the anterior and posterior divisions of the accessory olfactory bulb to the medial amygdala in the opossum, Monodelphis domestica. Europ J Neurosci 11, 3789-3799. 

Martinez-Marcos A., Ubeda-Banon I. and Halpem M. (2000). Cell turnover in the vomeronasal epithelium evidence for differential migration and maturation of subclasses of vomeronasal neurons in the adult opossum. J Neurobiol 43, 50-63. 

Perret M. and Barek S. (1991). Male influence on estrus cycles in female Woolly Opossum (Caluromys philander). J Reprod Fertil 91, 557-566. 

Poran N.S., Vandoros A. and Halpem M. (1993). Nuzzling in the Gray Short-tailed Opossum, I Delivery of odors to vomeronasal organ. Physiol Behav 53, 959-967. 

Poran N. (1998). Vomeronasal organ and its associated structures in the opossum Monodelphis domestica. Micros Res Techn 43, 500-510. 

Roland R., Halpem M., et al. (1995). Effects of vomeronasal-axotomy on the anatomy of the accessory olfactory bulb and on nuzzling behavior in the Brazilian Shorttailed Opossum Monodelphis domestica. Chem Senses 19, 544-545. 

Schwanzel-Fukuda M., Fadem B., Garcia M. and Pfaff D. (1988). Immunocytochemical localization of LHRH in the brain and Nervus terminalis of the adult and early neonatal Gray Short-Tailed opossum (Monodelphis domestica). J Comp Neurol 276, 44-60. 

Shapiro L. and Halpem M. (1995). Lectin histochemical identification of carbohydrate moieties in opossum chemosensory systems during development, with special emphasis on VVA-identified subdivisions in the accessory olfactory bulb. J Morphol 224, 331-349. 

Shapiro L., Roland R.M., Li C.S. and Halpem M. (1996) Vomeronasal system involvement in response to conspecific odors in adult male opossums, Monodelphis domestica. Behav Brain Res 77, 101-113. 

Stonerook M.J. and Harder J.D. (1992). Sexual maturation in female grey short-tailed opossums M. domestica, is dependent upon male stimuli. Biol Reprod 46, 290-294. 

J Ubl, H Murer, HA Kolb. Ion channels activated by osmotic and mechanical stress in membranes of opossum kidney cells. J Membrane Biol 104 223-232, 1988. 

It is normally found in Australia and New Guinea. The natural reservoirs are mosquitoes, birds, foxes, and opossums. Mosquitoes remain infective for life. Domestic animals do not manifest clinical symptoms. This is a biosafety level 3 agent. 

Van Duyn-Henderson, J. and D.C. Lasenby. 1986. Zinc and cadmium transport by the vertically migrating opossum shrimp, Mysis relicta. Canad. Jour. Fish. Aquat. Sci. 43 1726-1732. 

---