The nematode genus Syncuaria Gilbert, 1927 (Acuariidae) is reported for the first time from Argentina with two species parasitic in Threskiomithidae. Syncuaria plegadisi sp. n. from the white-faced ibis, Ptegadis chihi (Vieillot), is described and figured. The new species differs from known species of Syncuaria by the following characters: absence of lateral alae; cephalic cordons narrow, consisting of cuticular plates dorsally and ventrally invaginated forming a groove; presence of cephalic spines; spicules with simple, rounded distal ends; left spicule two to three times longer than right one; female tail dorsally bent and distance between vulva and anus comparable to tail length. Syncuaria diacantha Petter, 1961, a common parasite of the roseate spoonbill, Plalalea ajaja L., is reported for the first time from Argentina and briefly described. SEM micrographs for both species are provided. Both S. plegadisi sp. n. and S. diacantha were found to co-oeeur in the same locality, but not on the same host, suggesting a high degree of host specificity.
Low temperature phosphorescence, fluorescence and transient hole buming spectra of the photosystem 2 particles isolated from the cyanobacterium Synechococcus elongatus were measured. The role of photosynthetic activity was estimated by comparison of these spectroscopic methods. A model explaining chlorophyll fluorescence changes and both phosphorescence quantum efficiency increase and transient hole bimiing efficiency decrease connected with Chemical or heat photosynthetic deactivation is presented.
For an abelian lattice ordered group G let conv G be the system of all compatible convergences on G; this system is a meet semilattice but in general it fails to be a lattice. Let and be the convergence on G which is generated by the set of all nearly disjoint sequences in G, and let a be any element of conv G. In the present paper we prove that the join and V a does exist in conv G.
The responses to irradiance of photosynthetic CO2 assimilation and photosystem 2 (PS2) electron transport were simultaneously studied by gas exchange and chlorophyll (Chl) fluorescence measurement in two-year-old apple tree leaves (Malus pumila Mill. cv. Tengmu No.1/Malus hupehensis Rehd). Net photosynthetic rate (PN) was saturated at photosynthetic photon flux density (PPFD) 600-1 100 (μmol m-2 s-1, while the PS2 non-cyclic electron transport (P-rate) showed a maximum at PPFD 800 μmol m-2 s-1. With PPFD increasing, either leaf potential photosynthetic CO2 assimilation activity (Fd/Fs) and PS2 maximal photochemical activity (Fv/Fm) decreased or the ratio of the inactive PS2 reaction centres (RC) [(Fi - Fo)/(Fm - Fo)] and the slow relaxing non-photochemical Chl fluorescence quenching (qs) increased from PPFD 1 200 μmol m-2 s-1, but cyclic electron transport around photosystem 1 (RFp), irradiance induced PS2 RC closure [(Fs - Fo')/Fm' - Fo')], and the fast and medium relaxing non-photochemical Chl fluorescence quenching (qf and qm) increased remarkably from PPFD 900 (μmol m-2 s-1. Hence leaf photosynthesis of young apple leaves saturated at PPFD 800 μmol m-2 s-1 and photoinhibition occurred above PPFD 900 μmol m-2 s-1. During the photoinhibition at different irradiances, young apple tree leaves could dissipate excess photons mainly by energy quenching and state transition mechanisms at PPFD 900-1 100 μmol m-2 s-1, but photosynthetic apparatus damage was unavoidable from PPFD 1 200 μmol m-2 s-1. We propose that Chl fluorescence parameter P-rate is superior to the gas exchange parameter PN and the Chl fluorescence parameter Fv/Fm as a definition of saturation irradiance and photoinhibition of plant leaves. and Husen Jia, Dequan Li.
The semianaytical theory of the motion ol the resonant Earth satellite under the inlluence of Sun and Moon is constructed in nonsingular variables by Lie transforms. The explicit expressions tor the general terms of the combined perturbations are obtained up to the third order with resped to C20. The account ol the additional perturbations is exemplified by the calcuiaiion of the corrections due to the precession and the nutation.