BACKGROUND: We investigate the usefulness of expressed sequence tags, ESTs, for establishing divergences within the tree of placental mammals. This is done on the example of the established relationships among primates (human), lagomorphs (rabbit), rodents (rat and mouse), artiodactyls (cow), carnivorans (dog) and proboscideans (elephant). METHODOLOGY/PRINCIPAL FINDINGS: We have produced 2000 ESTs (1.2 mega bases) from a marsupial mouse and characterized the data for their use in phylogenetic analysis.
This early development was studied from a serial histological sections of eight elephant embryos with masses varying between 1 and 240 g. The tush and the tusk develop from one tooth germ in a deciduous to permanent tooth relation. In order to study the mineralization of the dental organ of the tush and cap and bell stage of the tusk, embryos older than 3-months' gestation (weighing more than 250 g) would be required.
The first known case of an odontoma in an African elephant (Loxodonta africana) is described. The tumour was fused with the coronal cementum of the sixth right mandibular molar tooth, thus preventing its eruption.
A captive female African elephant, known to be 27 years old, died as a result of trauma. Her growth rate was similar to that of other captive African elephants, and slightly greater than that of wild animals. The 5th molar was in full wear, and the 6th was just coming into wear. There was extensive dental caries of the labial, lingual and occlusal surfaces of the 5th molars, presumably due to the unnatural diet. The ovaries contained a large number of cystic follicles, and at least 50 regressing corpora lutea. These abnormalities are probably related to the…
Two cases of fatal enteritis caused by Clostridium difficile in captive Asian elephants are reported from an outbreak affecting five females in the same zoo. Post mortem examination including histopathology demonstrated fibrinonecrotic enterocolitis. C. difficile was isolated by selective cultivation from two dead and a third severely affected elephant. Four isolates were obtained and found positive for toxin A and B by PCR.