Physical mapping of the minimal region of loss in 5q- chromosome.

Acquired interstitial loss of all or part of the long arm of human chromosome 5 (5q-) is an anomaly that is seen frequently in patients with preleukemic myelodysplasia and acute myelogenous leukemia. Loss of a critical region of overlap at band 5q31.1 in all of these cases, with various cytogenetic breaks, signifies the existence of a key negative regulator of leukemogenesis. Previous studies have defined the proximal and distal ends of the critical region to reside between the genes for IL9 and EGR1, respectively. In this report, we describe a yeast artificial chromosome contig spanning this myeloid tumor suppressor locus. The combined order of the polymorphic loci is centromere-IL9-(D5S525-D5S558-D5S89-D5S526 -D5S393)-D5S399-D5S396-D5S414-EGR1 and telomere. The physical distance between the IL9 and EGR1 genes is estimated to be < 2.4 Mb. Here we report the utility of these polymorphic loci by detecting a submicroscopic deletion of 5q31; an acute myelogenous leukemia patient with a three-way translocation, t(5;18;17)(q31;p11;q11), as the sole anomaly revealed allele loss of the D5S399 and D5S396 loci.

The role of London forces in defining noncentrosymmetric order of high dipole moment–high hyperpolarizability chromophores in electrically poled polymeric thin films

Graphs of second harmonic generation coefficients and electro-optic coefficients (measured by ellipsometry, attenuated total reflection, and two-slit interference modulation) as a function of chromophore number density (chromophore loading) are experimentally observed to exhibit maxima for polymers containing chromophores characterized by large dipole moments and polarizabilities. Modified London theory is used to demonstrated that this behavior can be attributed to the competition of chromophore-applied electric field and chromophore–chromophore electrostatic interactions. The comparison of theoretical and experimental data explains why the promise of exceptional macroscopic second-order optical nonlinearity predicted for organic materials has not been realized and suggests routes for circumventing current limitations to large optical nonlinearity. The results also suggest extensions of measurement and theoretical methods to achieve an improved understanding of intermolecular interactions in condensed phase materials including materials prepared by sequential synthesis and block copolymer methods.

On the origin of the order Artiodactyla.

The first known members of the order Artiodactyla appeared suddenly throughout the Holarctic region at the beginning of the Eocene. They are characterized by distinctive cursorial skeletal specializations. Owing to their abrupt appearance and the lack of transitional forms, the origin of the order is problematic. Descent from a "condylarth," specifically the arctocyonid Chriacus, has been suggested based on dental resemblances, but until now postcranial anatomy seemed to preclude close relationship between Arctocyonidae and Artiodactyla. A middle Paleocene specimen of a small arctocyonid (?Chriacus) reported here is much more similar to the oldest artiodactyl, Diacodexis, in the derived condition of the hindlimb, reviving the possibility that Artiodactyla evolved from an arctocyonid.

Ptolemaiida, a new order of Mammalia--with description of the cranium of Ptolemaia grangeri.

All records of the exotic mammalian family Ptolemaiidae are known from 182 m of section in the lower to middle parts of the upper Eocene and lower Oligocene Jebel Qatrani Formation, Fayum Depression, Egypt. Previous tentative assignments of ptolemaiid affinity have suggested that these animals are allied with the primitive suborder Pantolesta (currently placed in the order Cimolesta). Though perhaps ultimately derived from an unknown member of that group, the likelihood that ptolemaiids constitute a distinct group is considered, and analysis of all known materials of Ptolemaia, Qarunavus, and Cleopatrodon demonstrates that these genera belong in their own order, the Ptolemaiida, described here. The morphologically unique dentition and only known ptolemaiid cranium, that of Ptolemaia grangeri, is described. Although Qarunavus and Cleopatrodon show some similarities in primitive characters to European merialine Paroxyclaenidae (suborder Pantolesta), their affinities clearly lie with Ptolemaia and the Ptolemaiida.