Heterochromatin protein 1 (HP1) has an essential role in heterochromatin formation and mitotic progression through its interaction with various proteins. We have identified a unique HP1alpha-binding protein, POGZ (pogo transposable element-derived protein with zinc finger domain), using an advanced proteomics approach. Proteins generally interact with HP1 through a PxVxL (where x is any amino-acid residue) motif; however, POGZ was found to bind to HP1alpha through a zinc-finger-like motif. Binding by POGZ, mediated through its zinc-finger-like motif, competed with PxVxL proteins and destabilized the HP1alpha-chromatin interaction. Depletion experiments confirmed that the POGZ HP1-binding domain is essential for normal mitotic progression and dissociation of HP1alpha from mitotic chromosome arms. Furthermore, POGZ is required for the correct activation and dissociation of Aurora B kinase from chromosome arms during M phase. These results reveal POGZ as an essential protein that links HP1alpha dissociation with Aurora B kinase activation during mitosis.

We demonstrate that a (3-aminopropyl)triethoxysilane-treated glass surface is superior to an untreated glass surface for coating with extracellular matrix (ECM) proteins when used as a cell culture substrate to observe cell physiology and behavior. We found that MDCK cells cultured on untreated glass coated with ECM removed the coated ECM protein and secreted different ECM proteins. In contrast, the cells did not remove the coated ECM protein when seeded on (3-aminopropyl)triethoxysilane-treated (i.e., silanized) glass coated with ECM. Furthermore, the morphology and motility of cells grown on silanized glass differed from those grown on non-treated glass, even when both types of glass were initially coated with laminin. We also found that cells on silanized glass coated with laminin had higher motility than those on silanized glass coated with fibronectin. Based on our results, we suggest that silanized glass is a more suitable cell culture substrate than conventional non-treated glass when coated by ECM for observations of ECM effects on cell physiology.

SUMMARYElectrical shock stimulation of the conotruncal area induced a spectrum of double outlet right ventricle (DORV) in embryonic chicks at developmental stages 24-27. The device used to apply electrical potentials to the heart was constructed using a 9 battery, a push-button switch, and a 100 ohm, ten-turn potentiometer with a calibrated dial. The potentiometer was connected as a voltage divider with the outlet connected to an electrode pair. This allowed for a short voltage pulse (variable 0 to 9) to be applied to a selected area of the heart through the electrodes. Two different methods were chosen to apply electrical shocks to the conotruncal area of the heart. One method utilized the application of an electrical shock between two points across the conotruncus of cardiac loop (horizontally oriented) and the second method between two points along the conotruncus of cardiac loop (vertically oriented).The range of voltages applied to the conotruncal area of the heart was from 2 to 4. Three distinct types of double outlet right ventricle were in the longitudinal (L) and horizontal (H) electrical shock groups: 1) DORV without a ventricular septal defect (VSD), which is associated with a prolapse of an aortic valve into the right venFrom the

Administration of electrical shock to the conotruncal area of embryonic chicks at developmental stage 24-27 induced a complex malformation, namely, double outlet right ventricle (DORV) of varying degrees of severity.The device used to apply electrical current to the heart was constructed using a 9-volt battery, a push-button switch, and a 100-ohm potentiometer with calibrated dial. This allowed a short pulse of known voltage to be applied through the electrodes to a selected area of the heart. Two different methods were chosen to administer electrical shock at the conotruncal area of the heart. One method utilized longitudinal application of electrical shock, and the other used horizontal application of electrical shock directly to the conotruncus.Three distinct types of DORV were found in the longitudinal (L) and the horizontal (H) electrical shock groups: 1) DORV without a ventricular septa1 defect (VSD), in which the dilated sinus of Valsalva of the aortic valve extends into the right ventricle. 2) DORV with a subaortic VSD, with variable degrees of pulmonary stenosis Longitudinal stimulation produced a higher incidence of cardiovascular anomalies than horizontal stimulation (p = 0.01). Histological examination showed complete disappearance of myocardial fibers, myocardial degeneration, and the aggregation of protein material or glycogen within myocardial cells.Our Doppler findings demonstrate that relative to control embryos, peak velocity initially increased 3 minutes after electrical stimulation (p < 0.01), and subsequently decreased significantly within 30 minutes (p < 0.01). One may hypothesize that the marked initial increase of peak velocity was induced by tissue damage, which led to a narrowing of the conotruncal outflow tract. Evidence for contruncal narrowing was also reflected in percent window data (% W), which indicates the level of turbulence within a vessel. However, the decrease of peak velocity 30 minutes after stimulation might be caused by myocardial damage resulting in a diminished cardiac output. The relationship between cell death processes in the conotruncal area and DORV spectrum induced by electrical shock is discussed.