ABSTRACT
The reaction of fac(S)-[Rh(aet)(3)] (aet = 2-aminoethanethiolate) with 1.5 molar equiv of AgBF(4) in water gave an S-bridged pentanuclear complex, [Ag(3){Rh(aet)(3)}(2)](BF(4))(3) (1(BF(4))(3)), while the reaction with 1.2 molar equiv of AgBF(4) produced an S-bridged nonanuclear complex, [Ag(5){Rh(aet)(3)}(4)](BF(4))(5) (2(BF(4))(5)). The crystal structures of 1(BF(4))(3) and 2(BF(4))(5) were determined by X-ray crystallography: 1(BF(4))(3).H(2)O crystallizes in the orthorhombic space group Pnma with a = 16.609(3) Å, b = 13.352(4) Å, c = 15.771(3) Å, V = 3497(1) Å(3), Z = 4, and R = 0.056. 2(BF(4))(5).4H(2)O crystallizes in the monoclinic space group P2(1)/c with a = 15.665(5) Å, b = 14.003(2) Å, c = 31.900(9) Å, beta = 94.19(1) degrees, V = 6979(3) Å(3), Z = 4, and R = 0.068. In 1 each of three Ag(I) atoms is linearly coordinated by two thiolato sulfur atoms from two octahedral fac(S)-[Rh(aet)(3)] units. In 2 each of four Ag(I) atoms is trigonally coordinated by three thiolato sulfur atoms from three fac(S)-[Rh(aet)(3)] units, while the remaining Ag(I) atom is linearly coordinated by two thiolato sulfur atoms from two fac(S)-[Rh(aet)(3)] units. 2 was readily converted to 1 by reaction with Ag(+), while the conversion of 1 to 2 was achieved by the reaction with fac(S)-[Rh(aet)(3)].
ABSTRACT
We reconstituted metachronal waves on ciliated cortical sheets prepared from detergent-extracted Paramecium multimicronucleatum cells. Ciliary movements of the cortical sheet, whose intracellular side adhered to a glass coverslip, were reactivated by perfusion of a basic reactivation medium containing ATP. In this condition, the ciliary field showed only unstable localised ripples. Addition of either cyclic AMP or cyclic GMP to the basic reactivation medium generated propagating metachronal waves characteristic of each nucleotide. In order to estimate the stability of the metachronal waves, autocorrelation coefficients were calculated from images of an 8 µm diameter region within the reactivated ciliary field. The decay time for the correlation coefficient to decrease to 0.5 was only 0.04 s in the basic reactivation medium, but was increased to 0.4 or 0.9 s by the addition of cyclic AMP or cyclic GMP, respectively. The decay time was dependent not only on the concentration of cyclic nucleotide but also on the wave frequency. In order to test whether cyclic-nucleotide-dependent phosphorylation affected the generation of waves, the ciliated cortical sheets were thiophosphorylated by incubation in ATP-gamma-S (adenosine-5'-o-3-thiotriphosphate) medium containing either cyclic AMP or cyclic GMP. Following this, perfusion with the basic reactivation medium generated metachronal waves only after cyclic GMP treatment. The effect of cyclic GMP is probably related to phosphorylation of ciliary proteins.
ABSTRACT
In conditions in which ciliated cortical sheets prepared from detergent-extracted Paramecium multimicronucleatum cells adhered to glass coverslips on a microscope stage, perfusion of a reactivation medium containing ATP plus cyclic AMP or cyclic GMP generated metachronal waves. An analysis of the ciliary movements that generate these metachronal waves yielded the following results. During the generation of metachronal waves, there were phase differences in the ciliary orientation of adjacent cilia in the direction of wave propagation. Addition of cyclic AMP or cyclic GMP increased the rotational angular velocities during the effective stroke of ciliary beating, but did not increase the rotational angular velocity of the recovery stroke. When the ATP concentration in the cyclic GMP reactivation medium was increased, the rotational angular velocity during the effective stroke rose steeply and saturated at 0.8 mmol l-1 ATP, whereas that during the recovery stroke rose gradually. Addition of cyclic nucleotides caused a single cilium isolated from neighbouring cilia on the cortical sheet to incline almost parallel to the cortical surface during the recovery stroke. Addition of cyclic GMP increased the amplitude of bending of cilia detached from the cortical sheet. From these results, it was concluded that increases in the asymmetrical movement of individual cilia, caused by the addition of cyclic nucleotides, create the ciliary interaction that generates the metachronal waves.
