The electrophoretic karyotypes of 32 clinical and 3 environmental Cryptococcus neoformans isolates from New York City were studied by contour clamped homogeneous electrophoresis. There was extensive variation among the electrophoretic karyotypes of isolates from different patients. Sequential C. neoformans isolates from patients with chronic or relapsing infection had very similar karyotypes. However, minor differences in electrophoretic karyotypes were detected among sequential isolates from 50% of the patients studied, suggesting the occurrence of chromosomal rearrangements or deletions in vivo. This hypothesis was tested by infecting mice, recovering isolates from mouse organs, and comparing the electrophoretic karyotypes before and after passage. Three clinical and three environmental strains were studied before and after passage in mice. Karyotype differences were detected after mouse passage for one clinical and two environmental strains. Our results indicate (i) extensive karyotype variation among isolates from a small geographic region, (ii) a high frequency of electrophoretic karyotype differences among sequential isolates from individual patients, and (iii) the occurrence of electrophoretic karyotype changes during experimental infection of mice. The implications of these observations are discussed.

Mouse models of lysosomal storage diseases, including Sandhoff disease, are frequently employed to test therapies directed at the central nervous system. We backbred such mice and conducted a behavioral test battery which included sensorimotor and cognitive assessments. This is the first report of short-term memory deficits in a murine model of Sandhoff disease. We also document early onset of motor deficits using the balance beam test. KeywordsSandhoff disease; Mouse model; Novel object recognition test; Rotarod; Motor coordination; Balance beam; Open field; Memory Lysosomal storage disorders (LSDs) are a family of inherited diseases with multi-organ involvement frequently including the nervous system. The G M2 gangliosidoses, one class of human LSDs that include Tay-Sachs and Sandhoff diseases, are marked by the lysosomal accumulation of G M2 ganglioside (GM2) in neurons throughout the nervous system. Sandhoff disease arises from defects in the gene encoding the β-subunit (hexb) of β-Nacetyl-d-hexosaminide N-acetylhexosaminohydrolase (EC 3.2.1.52) normally involved in the sequential catabolism of gangliosides and other glycoconjugates [11]. Sandhoff patients have widespread brain pathology which results in clinical symptoms including progressive mental and motor deterioration [10,11,21].Two transgenic murine models of Sandhoff disease exist [23,25] that, like the human equivalent, exhibit premature death and display widespread neuronal storage of ganglioside, in addition to gliotic and inflammatory reactions and neuronal cell death [11,16,23,25,27]. The Sandhoff models have engendered much research directed at overcoming the challenges [1,2,4,11,14,15,18,20]. The knockout model [25] presented here displays ataxia, tremor, muscle wasting, and deficits in motor reflex, coordination and balance [1,4,7,8,13,14,16,18,20,22,25,27,28]. However, systematic studies examining cognitive or affective outcomes are lacking [25]. Clearly, these latter studies would be valuable to evaluate CNS-specific improvements, and would be most meaningful if assays pertinent to human neurologic assessments were employed to facilitate transition to clinical trials. Furthermore, the Sandhoff mice rarely show overt clinical signs before 3 months old and then rapidly decline, typically becoming moribund between 4 and 5 months of age [1,[13][14][15]18,20,22,25,27,28]. Therefore, behavioral assays should ideally be able to identify cognitive deficits in subjects that have multiple behavioral outcomes. In addition, increased assay sensitivity could permit behavioral assessment at earlier ages thereby also providing better evaluation of therapeutic strategies which seek earlier intervention.We Heterozygous breeders of the B6; 129S4-Hexβ tm1R1p strain [25] (Jackson Labs, Maine) were backbred through 10 generations by mating with C57BL/6J mice. Then the backbred heterozygotes were mated together and progeny genotyped using a standardized PCR protocol (provided by Jackson Labs) on tail-tip DNA extracts. Studies were performed using homozy...

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