The evolution of a highly variable sex chromosome in Gehyra purpurascens (Gekkonidae)

A karyotypic survey of the gekkonid lizard Gehyra purpurascens revealed a distinctive sex chromosome system. G-banding showed that the Z Chromosome of males is derived from a tandem fusion of two acrocentric chromosomes of a presumed ancestral Gehyra with 2n=44. Through the application of G-; N- and C-banding, a total of six morphs of the W chromosome were identified. These differ by paracentric and pericentric inversions and, in one case, by a centric shift. The possible reasons for such extensive variation in the W chromosome are considered, and it is suggested that increased mutability of the W chromosome may be a causal factor. In contrast to earlier speculations, this example demonstrates that sex chromosomes can evolve without significant changes in the amount of C-band heterochromatin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47361/1/412_2004_Article_BF00292447.pd

Diagnosis of anterior cervical spinal epidural abscess by US and MRI in a newborn.

A 10-day-old girl who initially presented with fever developed over five days a complete paresis of both upper arms and swallowing difficulty. After emergency drainage of a retropharyngeal abscess, cervical US demonstrated a cervical anterior epidural mass compressing the cord. MRI confirmed the diagnosis of spinal epidural abscess secondary to C4-C5 spondylodiscitis. Surgical removal of the abscess was followed by complete disappearance of the neurologic symptoms after six months of follow-up. This is the first case of spinal epidural abscess in a newborn to be diagnosed by US and MRI preoperatively. The advantages of these non-invasive imaging modalities are discussed, and compared to myelography