Lizard monitor

Lizards that prey on snakes hut are also eaten hy larger snakes discriminate skin chemicals of snakes very well. Monitor lizards, Varanus albigularis, fall in this group. Hatchling monitors attacked harmless snakes but avoided venomous species. However, they accepted meat of all snakes if carefully skinned. The hatchlings tongue flicked to invertebrate prey covered with skin from venomous snakes and rejected these samples (Phillips and Alberts, 1992). 

Monitor lizards include 24 living species of large lizards in the genus Varanus, family Varanidae. Monitors inhabit tropical and sub-tropical regions of Africa, Asia, and Australia. Monitors are among the most advanced of the lizards, in terms of achieving an active, predaceous lifestyle. 

Monitor lizards grow replacement teeth in the gaps between their mature teeth. They have at least 29 vertebrae above their hips. Nine of these are neck vertebrae, supporting the unusually long neck of these lizards. Their powerful jaws are hinged in the middle, allowing them to swallow large prey. The head of monitors is tapered, and there are distinct ear holes. 

Monitors, like all lizards, are poikilothermic or coldblooded. They are most energetic after they have been heated by the morning sun, since their muscles work much more efficiently and easily when they are warm. Monitors can run quickly to chase down prey. When doing so they lift their body and tail clear off the ground. 

T. zimbabwensis or T. papuae human infection are available. However, one human trichinellosis outbreak due to consumption of reptile meat from a monitor lizard Varams nebulosus) has been documented in Thailand (Pozio 2007a). In addition, a 10% prevalence of serum mti-Trichinella IgG antibody was detected in the inhabitants of Morehead District of Papua New Guinea, where wild-pig meat, potentially infected with T. papuae, represents the main source of protein (Owen et al. 2005 Pozio and Zarlenga 2005). Although persons reported muscular or joint pain, the infection was apparently no severe, suggesting that seropositive people are exposed to recurring infections with very few larvae (Owen et al. 2005). 

Haslewood and Wootton isolated varanic acid, 3a,7a,12a,24-tetrahydroxy-5)S-cholestan-26-oic acid, from bile of the monitor lizard, Varanus niloticus [53]. Varanic acid was later found in bile of the frog, Bombina orientalis, where it occurs in the unconjugated form [18]. Une et al. synthesized 4 diastereoisomers at C-24 and C-25 of 3a,7a,12a,24-tetrahydroxy-5y3-cholestan-26-oic acid. Comparisons with these synthetic bile acids of known absolute configuration showed that the varanic acid in frog bile is (24i ,25S )-3a,7a,12a,24-tetrahydroxy-5jS-cholestan-26-oic acid [54]. 

The 12-deoxy derivative of varanic acid, 3a,7a,24-trihydroxy-5)8-cholestan-26-oic acid was detected in the bile of Varanus monitor, as a minor companion of varanic acid, the major bile acid of this lizard [69]. 

Luebke, J. I., Weider, J. M., McCarley, R W., and Greene, R. W. (1992) Distnbu-tion of NADPH-diaphorase positive somata in the brainstem of the monitor lizard Varanus exanthematicus. Neurosci Lett 148, 129—132... 

Varanic acid was isolated from the bile of the monitor lizard by Haslewood and Wootton (99). An apparent stereoisomer occurs also in HelodermOr From comparative chromatographic and spectroscopic data with synthetic material Collings and Haslewood (183) have determined that the acid is very likely a C-24- or C-25-isomer of the 3,7,12,24-tetrahydroxy structure shown above. 3a,7a,12a,24-Tetrahydroxycoprostanic acid was synthesized by Inai et al. (184) and in radioactive form by Masui and Staple (185). The labeled acid was converted to cholic acid by rat liver (185). 

The projector output (50 to 100 mW heat production due to illumination in the calorimetric vessel) was dimmed down to about 1 mW for visual observation and 10 mW for video monitoring. For comparison snails produced about 0.4 mW, crickets around 2 mW, honeybees 16 mW and lizards 8 mW. After electrical stabilization of the projector, illumination resulted in a constant shift of the baseline and did not disturb the calorimetric experiments. Figure 3 shows a water snail (Biomphalaria glabratd) on the bottom of the vessel. The vertical lines on the vessel wall were used for orientation to determine the exact position of the animal [55]. 

However, the same type of sensor can also be used in terrestric investigations, yet with a strongly reduced sensitivity. A Beckman-Monitor-System (type 123301 O2/T) was adapted to 100-mL vessels of a Calvet microcalorimeter. The electrode was placed high enough above the heat flux meter that no interference between the two signals could be observed. This system was - e.g. - applied during investigations of crabs [64] or snakes and lizards [38,65],... 

---