Amplification of c-MYC and MLL Genes as a Marker of Clonal Cell Progression in Patients with Myeloid Malignancy and Trisomy of Chromosomes 8 or 11.

Gene amplification (amp) is one of the basic mechanisms connected with overexpression of oncogenes. The c-MYC (located in 8q24) and MLL (located in 11q23) are the most often over represented genes that lead to a rapid proliferation of the affected cell clone in patients with myeloid neoplasms. Assessment of the level of amp c-MYC or amp MLL in the cases with trisomy 8 (+8) or trisomy 11 (+11) and myeloid malignances is necessary for a more precise estimation of the disease progression. A total of 26 patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) were included in the study: 18 with +8, six with +11 and two with complex karyotypes suspected of the partial trisomy. Routine cytogenetic analysis and fluorescent in situ hybridization (FISH) were applied to indicate the chromosome alterations and genes amp in the bone marrow cells. Amp c-MYC was observed in 12 from 18 (66.7%) patients with +8. All the patients with +11 demonstrated a different level of amp MLL. In most of the cases with MDS (9/10), the coincidence of the +8 or +11 with amp c-MYC or amp MLL, respectively, leads to transformation to AML and/or short overall survival. Our data suggest that amp c-MYC and amp MLL develop in conformity with +8 and +11, especially in cases with progressive deviations in the karyotype as an aggressive expansion of an aberrant cell clone and appearance of additional chromosome anomalies.

Micropropagation of switchgrass by node culture.

Switchgrass (Panicum virgatum L.) is naturally outcrossing; therefore, maintenance of genotype is difficult through sexual propagation. The objective of this study was to develop a micropropagation procedure for the multiplication of desired or selected genotypes. Nodal segments were surface sterilized, split longitudinally, and placed with the cut surface on solid MS medium containing 30 g L-1 maltose and different concentrations of 6-benzylaminopurine (BAP) as the only growth regulator. Best shoot proliferation was obtained with 12.5 micromoles BAP and culture at 29 degrees C. Shoots were easily rooted on MS medium without BAP. Under optimum conditions, it is possible to produce approximately 500 plantlets from one parent plant in 12 wk.