Crocodiles

The Afncan dwarf crocodile secretes a volatile substance believed to be a sex pheromone It IS a mixture of two stereoisomers one of which is shown... 

Crazing. Resembles checking but the cracks are deeper and broader. Crocodiling or alligaloring. A drastic type of crazing producing a pattern resembling the hide of a crocodile. 

The second analytical method uses a combustion system (O Neil et al. 1994) in place of reaction with BrF,. This method was used for the crocodiles because they were represented by very thin caps of enamel. The enamel was powdered and sieved (20 mg), pretreated in NaOCl to oxidize organic material and then precipitated as silver phosphate. Approximately 10-20 mg of silver phosphate were mixed with powdered graphite in quartz tubes, evacuated and sealed. Combustion at 1,200°C was followed by rapid cooling in water which prevents isotopic fractionation between the CO2 produced and the residual solid in the tube. Analyses of separate aliquots from the same sample typically showed precisions of 0.1%o to 0.4%o with 2 to 4 repetitive analyses even though yields are on the order of 25%. 

Tooth enamel precipitated as silver phosphate and reacted via this method gave values similar to corrected laser data from aliquots of the same tooth enamel (Table 6.1). Thus, the data from the crocodile samples are considered directly comparable with the data from the mammal tooth enamel. 

In field trials following multiple aerial applications of endosulfan for tsetse fly control in Africa over a 3-month period, residues of the compound in fish tissues decreased to low concentrations within 3 months after spraying. The fish tissue residues were still detectable after 12 months. Residue concentrations in fish-eating birds and crocodiles were similar to fish tissue residue levels endosulfan did not biomagnify in the food chain (HSDB 1999). 

The remaining reptiles are monosmic, i.e. they are MOS-dependent with no functional accessory system. They derive from a secondarily aquatic group of Mesozoic dinosaurs, whose survivals are now represented by Crocodiles, Alligators and Caimans (Howes, 1891 Saint Girons, 1976). In these, the loss of accessory olfaction may have been part of a pre-adaptive trend. Genomic comparisons with the avian OR repertoires could provide some clues on AOS history in their living relatives. 

Fig. 4.2 Differentiation from olfactory placode of main and VN primordia (a) to (b), embryonic stages in reptiles (Squamates and Crocodylia). (a), Early invagination of placode (a ), late separation of primordia for AOS/MOS and (b), agenesis of presumptive VN(JO) cells in crocodile (NPT, nasal pit) (from Parsons, 1970).

Before we can start to use the genetic algorithm, we must answer the question What exactly is a "population of solutions " It is easy to envisage a population of crocodiles or ants or lamas, but what does a population of solutions look like ... 

The result obtained by GC-MS, with the same SPME conditions, from the black thick balm of a crocodile mummy (sample 1400, Musee Guimet, Lyon, France) is presented in Figure 10.11. The composition of the extract is close to that of sample 1998 but phenolic compounds were not detected. The GC-MS chromatogram obtained with the same substance after acid methanolysis and silylation is presented in Figure 10.12. Except for the sesquiterpenoids eluted between 10 min and 22 min, the observed compounds originate from a beeswax. The biomarkers of this substance are hexadecanoic acids hydroxylated in position 14 or 15 and long chain hydrocarbons, acids and alcohols eluted between 50 min and 90 min. Diterpenoid or triterpenoid resin components are not observed. 

Data on copper concentrations in field collections of amphibians and reptiles are scarce. Crocodile eggs contain as much as 60 mg Cu/kg DW however, some toads (Bufo spp.) may contain as much as 2100 mg Cu/kg DW in livers without apparent adverse effects (Table 3.3 Goldfischer et al. 1970). 

Chlordane residue data for amphibians and reptiles are extremely limited. Maximum concentrations of chlordane isomers did not exceed 70 pg/kg FW of oxychlordane in eggs of the American crocodile, Crocodylus acutus, or 250 pg/kg FW in carcass of the common garter snake, Thamnophis sirtalis (Table 13.2). However, California newts, Tarichia torosa, taken near a lake treated with 10 pg/L technical chlordane had greatly elevated chlordane residues in liver and comparatively low concentrations in carcass, stomach, and stomach contents. After 14 days, livers contained about 34 mg/kg total chlordanes lipid weight — about 19% chlordanes, 9% nonachlors, and 6% chlor-denes (Albright et al. 1980). After 2.8 years, 98% of the total chlordanes was lost. 7ra .v-nonachlor was the most persistent component in newt liver, accounting for up to 55% of the total chlordanes in specimens collected 2.8 years after application (Table 13.2) (Albright et al. 1980). 

American crocodile, Crocodylus acutus, infertile eggs ... 

Hall, R.J., T.E. Kaiser, W.B. Robertson, Jr., and P.C. Patty. 1979. Organochlorine residues in eggs of the endangered American crocodile (Crocodylus acutus). Bull. Environ. Contam. Toxicol. 23 87-90. 

Eggs of the American crocodile (Crocodylus acutus) from the Florida Everglades contained up to 2.9 mg/kg fresh weight of DDE and 0.86 mg/kg of polychlorinated biphenyls, but less than 0.02 mg mirex/kg (Hall et al. 1979). Livers of the deep sea fish (Antimora rostrata) collected from 1971 to 1974 from a depth of 2500 m off the U.S. east coast, contained measurable concentrations of DDT and its degradation products, and dieldrin, but no mirex (Barber and Warlen 1979). 

Rasmussen, L.E.L. and Schmidt, M.J. (1992) Are sharks chemically aware of crocodiles In R.L. Doty and D. Miiller-Schwarze (Eds.), Chemical Signals in Vertebrates. Plenum Press, New York, pp. 335-342. 

Position Human Other bony vertebrates Caiman Nile crocodile Mississippi crocodile Functions... 

NAl/3 Val Val or Gly Ser Ac-Ala Ac-Ala In human and many other vertebrate deoxy-Hbs, the a-amino groups bind either organic phosphate or carbamino CO2, which in turn forms a salt bridge with Lys 82 of the same p chain in crocodile Hb, blocking of a-NHs or Pro in position 2 inhibits these functions... 

On two occasions, as I recall, Karl let me take a turn as his surgical assistant. To exercise this coveted privilege, I first had to procure the monkeys from their cages in the animal room. Not a routine task Monkeys in cages are not friendly by nature. Even the Crocodile Hunter would probably have had a moment of doubt before intruding on their space. Definitely not something to try at home. 

---