Equatorial plate

The spindle fibres are attached to the chromosomes at the centromere and align them on the equatorial plate. The spindle arrangement contains microtubules composed of the protein tubulin. Colchicine is a specific spindle poison, which binds to tubulin, and inhibits its polymerization. Consequently, colchicine blocks mitosis, causing polyploidy, the unequal partition of chromosomes and metaphase arrest. 

A FIGURE 20-37 Model of the forces stabilizing metaphase chromosomes at the equatorial plate. 

A typical division figure found in butamiphos-treated tissues was that, unlike the untreated cells, chromosomes were not aligned along the equatorial plate, but dispersed in the cytoplasm, giving rise to a so-called arrested metaphase (5). It is well known that colchicine inhibits mitosis at the metaphase. Butamiphos-treated onion cells had the same pattern of mitotic inhibition as colchicine-treated cells used as a reference ( 5). Butamiphos-treated tissues were compared with the untreated control with respect to percentage distribution of mitotic cells in each mitotic... 

The quantitative assessment of the degree of crystallite orientation by x-ray examination is not free of ambiguity. From a comparative analysis [23] in which results obtained from the consideration of (105) and from three different variations of equatorial reflection were compared, the conclusion was that the first procedure can lead to underrated results, i.e., to the underestimation of the orientation. However, it can be assumed that this does not result from an incorrect procedure, but from ignoring the fact that the adjacent (105) reflex can overlap. The absence of the plate effect of the orientation is characteristic of the orientation of crystallites in PET fibers. The evidence of this absence is the nearly identical azimuthal intensity distributions of the diffracted radiation in the reflexes originating from different families of lattice planes. The lack of the plate effect of orientation in the case of PET fiber stretching has to do with the rod mechanism of the crystallite orientation. 

Indexing rotation photographs. Preliminary consideration. The spots on the equator of a rotation photograph are obviously reflections from atomic planes which were vertical during the exposure. In Plate VII the equatorial spots are reflections from planes parallel to the c axis, that is, hkO planes the third or l index for these reflections is 0 by inspection. The other two indices, h and k, of all the equatorial reflections may be found from the spacings of the planes, which are worked out from the reflection angles 6 by the Bragg equation. 

The Cu(II) complex [Cu(74 )2(Fl20)2] (75) has a typical tetragonaUy distorted octahedral geometry, with two trans bidentate 74 in the equatorial positions . The crystal lattice of 75 has a layered structure, where each coordinated water molecule is H-bonded to a coordinated enolate of one complex and the unbound 4-keto group of an adjacent complex in the next layer. Dideprotonated 3,3 -bilawsone, 2,2 -bis(3-hydroxy-1,4-naphthoquinone), binds Cu(II) to form an extended trans complex framework (76, Plate VI) ". With Cd(II), a one-dimensional linear coordination polymer is formed . ... 

Plate 5. Ozone anomalies (ppmv) versus altitude (km) and time (years) in the equatorial region (4°N-4°S) derived from observations made by the HALOE instrument on board the Upper Altitude Research Satellite (UARS). Superimposed on ozone values are the zonal winds measured by the HRDI instrument on the same satellite. Full lines are eastward winds and dashed lines westward winds with intervals corresponding to 10 m/s. In the 20-30 km altitude range, the positive ozone anomalies are associated with the westerly shear in the quasi-biennal oscillation (QBO), while the negative anomalies are indicative of easterly shears. Above 30 km, ozone variability is associated with temperature variability, which affects the photochemical source terms. Above 35 km, the observed variations are due to temperature effects associated with the QBO and to the semi-annual oscillation. Courtesy of Paul Newman, NASA/GSFC. 

Fig. 5. Architecture of the fungal FAS. (A) Structural overview of the barrel-shaped molecule showing the location of the equatorial wheel composed of the six alpha subunits flanked by two domes, each composed of a p subunit trimer. The barrel is 270 A long and 230 A wide at the equator. (B) Location of the structural underpinnings of the molecule with the catalytic domains removed. (C) Organization of the alpha-subunit hexamer. (D) Organization of one p-subunit trimer (adapted from Lomakin et al. [13] with permission). (See color plate section, plate no. 4.)...

The illumination is provided by a laser diode in the near infrared at 830 nm. To avoid any specific orientation of the polarization of the light, the 4.8 mm-wide beam is directed by an optical fiber to a colhmator and then to an optical device made of a Glan-Foucault prism and qnarter-wave plate. An equatorial ring (inner diameter 118 mm) with vacnnm tight optical windows is inserted in the wall of the low-pressnre chamber in which the agglomeration of the dnst particles takes place. A set of analyzers allows measnrements to be obtained at 22 phase angles on a series of different phase angles, almost uniformly distribnted from 10 to 165 [63]. 

Figures 12-13 to 12-15. Electron diffraction patterns of cellulose microfibrils isolated from the tunicate Halocynthia as a standard cellulose sample (13), microfibrils isolated from thecal plates (14), and pellicles (15) of Scrippsiella hexapraecingula. Note the typical equatorial (110, iTO, 200) and meridional (004) reflections of cellulose I.

---