Chromosomal localization of a tandemly repeated DNA sequence in Trifolium repens L

INTRoDUCTIoNlYho1iumrePensL,whiteclover,isaneconomicallyimportantplantspeciesintemperatepastures.Asbrieflyreportedby[1],ithas16pairsofchromosomes(2n=32).Asyet,nodetailedcytologicalexaminationofthisspecies,suchasC-banding,hasbeenrep0rted.Inthelastdecade,thetechnique0fC-bandinghasbeenusedt0examinehighlyrepeatedsequencesinplantchrom0s0mesandhasprovidedausefultoolf0rtheanalysis0fcyt0geneticstructureincr0pplants[2-71.Inplants,thechr0m0s0mall0calizationofhighlyrepeatedDNAsequencesbyinsituhybr…     

Interspecific and intraspecific comparisons of the period locus in the Drosophila willistoni sibling species

The period (per) locus has received much attention in molecular evolution studies because it is one of the best studied "behavioral genes" and because it offers insight into the evolution of repetitive sequences. We studied most of the coding region of per in Drosophila willistoni and confirmed previously observed patterns of conservation and divergence among distantly related species. Five regions are so highly diverged that they cannot be aligned, whereas a region encompassing the PAS domain is very conserved. Structural and nucleotide polymorphism patterns in the willistoni group are not the same as those observed in previously studied species. We sequenced the region homologous to the highly polymorphic threonine-glycine repeat of D. melanogaster in multiple strains of D. willistoni, as well as in other members of willistoni group, and found an unusual amount of conservation in this region. However, the next nonconserved region downstream in the sequence is quite variable and polymorphic for the number of repeated glycines. The glycine codon usage is significantly different in this glycine repeat as compared to other parts of the gene. We were able to plot the directionality of change in the glycine repeat region onto a phylogeny and find that the addition of glycines is the general trend with the diversification of the willistoni group.      

Effects of using the unloaded configuration in predicting the in vivo diastolic properties of the heart

Computational models are increasingly being used to investigate the mechanical properties of cardiac tissue. While much insight has been gained from these studies, one important limitation associated with computational modeling arises when using in vivo images of the heart to generate the reference state of the model. An unloaded reference configuration is needed to accurately represent the deformation of the heart. However, it is rare for a beating heart to actually reach a zero-pressure state during the cardiac cycle. To overcome this, a computational technique was adapted to determine the unloaded configuration of an in vivo porcine left ventricle (LV). In the current study, in vivo measurements were acquired using magnetic resonance images (MRI) and synchronous pressure catheterization in the LV (N = 5). The overall goal was to quantify the effects of using early–diastolic filling as the reference configuration (common assumption used in modeling) versus using the unloaded reference configuration for predicting the in vivo properties of LV myocardium. This was accomplished by using optimization to minimize the difference between MRI measured and finite element predicted strains and cavity volumes. The results show that when using the unloaded reference configuration, the computational method predicts material properties for LV myocardium that are softer and less anisotropic than when using the early-diastolic filling reference configuration. This indicates that the choice of reference configuration could have a significant impact on capturing the realistic mechanical response of the heart.     

Effect of Sodium Fluorescein and Plating Medium on Recovery of Irradiated Escherichia coli and Serratia marcescens from Aerosols

Irradiation of aerosols of either Escherichia coli or Serratia marcescens with simulated solar (xenon) radiation caused a significant decrease in viability. When sodium fluorescein was employed to determine the physical loss of organisms from the aerosol, an additional adverse effect upon survival was noted. The decay curves indicated that at least two mechanisms of inactivation were operative, one due to aerosolization, the other to irradiation. After collection from aerosols, both species of microorganisms grew better on blood agar base than on Casitone agar, but this finding did not appear to be related to the effect of irradiation.