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541. Changes in the contents of the photosynthetic electron carriers, RNAse activity and membrane permeability, triggered by excess copper in rice

Creator:
Lidon, F. C. and Henriques, F. S.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Rice (Oryza sativa L.) plants were grown in nutríent solutíon containing concentrations of Cu vaiying from deficiency to toxicity [0.002-6.25 g(Cu) m"^]. Shoot contents of Cu, Mn and Fe were measured as well as the concentrations of plastocyanin (PC), plastoquinone (PQ) and cytochromes (cyt) f, 6553, 6-559up, and b- 559hp. While Cu concentration increased wilh increasing levels of metal in the solutíon, Mn and Fe concentrations progressively decreased after Cu treatments higher than 0.05 g m‘3. On a chlorophyll basis, the contents of PC and cyt/decreased after the 0.01 g(Cu) m'^ Cu treatonent, while the contents of cyt f>-559Lp and b- 559hp did not show any apparent conelatíon, and the PQ concentration sharply increased with increasing Cu toxicity. Membrane permeability and acid RNAse activity were enhanced with increasing Cu concentration.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

542. Changes in the near-UV fluorescence excitation spectrum during protochlorophyllide photoreduction in etiolated cucumber cotyledons

Creator:
Durchan, M. and Lebedev, N.
Format:
print
Type:
model:internalpart and TEXT
Subject:
Cucumis sativus L., energy transfer, protochlorophyllide reductase, and Shibata shift
Language:
Multiple languages
Description:
Fluorescence excitation spectra of different protochlorophyll(ide) (PChlide) a forms in intact etiolated cucumber cotyledons showed a pronounced increase in intensity of the 390 nm band in comparison with spectra of the pigment in Solutions. The native PChlide F657 also had an additional band at 360 nm in its excitation spectra, which disappeared after leaf homogenization and was restored by addition of dithionite. The restoration correlated with changes around 340 nm in the excitation spectrum of blue-green fluorescence. In consideration of this fact, the 360 nm band seems to correspond to energy transfer from NADPH to PChlide a. After the onset of irradiation a new band appeared at 380 nm in the excitation spectrum of the main pigment fluorescence, which was very similar to that found in the absorption spectinm of isolated Chl a. Moreover, in the Soret region the excitation spectrum had a double band splitting which disappeared only after the Shibata shift, simultaneously with the disappearance of the 360 nm band. Besides the well-known PChl(ide) F633, F642, and F657 forms, etiolated cucumber cotyledons háve emission at 673 nm. Its excitation spectrum was hardly distinguishable from the PChlide F657 fluorescence excitation spectrum in etiolated samples. In the irradiated plants this band had excitation spectrum of monomeric Chl a. The intensity of band at 673 run decreased and transiently increased after PChlide photoconversion. The dynamics of these fluorescence intensity changes under inadiation showed positive correlation both with PChlide F657 and with PChl(ide) F642, indicating the short wavelength Chl a preexistence in etiolated plants and its additional formation after the onset of irradiation.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

543. Changes in the personality profile of young women with latent toxoplasmosis

Creator:
Flegr, Jaroslav and Havlíček, Jan
Format:
print
Type:
model:internalpart and TEXT
Subject:
Toxoplasma gondii, behaviour, Cattell’s questionnaire, manipulation hypothesis, and permutation test
Language:
English
Description:
Latent toxoplasmosis is the most widespread parasite infection in developed and developing countries. I'he prevalence of Toxoplasma gondii infection varies mostly between 20 to 80% in different territories. This form of toxoplasmosis is generally considered to be asymptomatic. Recently published results, however, suggest that the personality profiles of infected subjects differ from those of uninfected controls. These results, however, were obtained on non-standard populations (biologists or former acute toxoplasmosis patients). Here we studied the personality profiles of 191 young women tested for anti-Toxoplasma immunity during gravidity. The results showed that the differences between Toxoplasma-negative and loxoplasma-posilive subjects exits also in this sample of healthy women. The subjects with latent toxoplasmosis had higher intelligence, lower guilt proneness, and possibly also higher ergic tension. The difference in several other factors (desurgency/surgency, alaxia/protension, naiveté/shrewdness, and selfsentiment integration) concerned changes in the variances, rather than the mean values of the factors.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

544. Changes in the thyiakoid membrane polypeptide patterns triggered by excess Cu in rice

Creator:
Lidon, F. C. and Henriques, F. S.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Chloroplast polypeptide composition of rice plants {Oryza sativa L. cv. Safari) exposed for 30 d to increasing Cu ion concentrations in a hydroponie growth medium was analyised. The conventional discontinuous SDS-aerylamide gel electrophoretic systém, the SDS PhastGel (Pharmacia Fine Chemicals) gradient 10-15 and tíie 5-8 pH range polyaciylamide isoelectric focusing of the PhastSystem separation and development technique were ušed. With Cu levels greater than 0.25 g m'^ die polypeptide bands with apparent molecular masses of 42/41, 33/32, 21/20 and 19/18 kDa deereased in the PhastSystem separation and development systém, whereas with the conventional discontinuous SDS buffer systém gel electrophoresis all these bands disappeared except the 33/32 kDa band. Also, under the latter systém excess Cu deereased the 56/55, 55/54, 26 and 22 kDa bands which was not shown by the PhastSystem separation and development technique. Furthermore, in the discontinuous SDS-PAGE high Cu levels induced the disappearance of the 16.5, 14.5 and 12 kDa bands, which were again not shown by the PhastSystem separation and development technique; yet the opposite oceurred with the 49 kDa band of the gel profiles. Polyacrylamide isoelectric focusing of thyiakoid membranes showed in all Cu treatments two major bands at pl 7.7 and <5 and a minor one at pl 6.48. At Cu concentrations lower than 1.25 g m'^ two additional smáli bands appeared (pl 5.5 and 5.18); and at Cu concentrations greater than 0.25 g m'^ these smáli bands were replaced by four different ones (pl 6.7, 6.05, 5.35, 5.25).
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

545. Changes in variable chlorophyll fluorescence as a result of Cu-treatment: dose-response relations in Silene and Thlaspi

Creator:
Ouzounidou, G.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Chlorophyll (Chl) fluorescence technique was ušed to monitor Cu damage in photosynthetic process in intact leaves of a Cu-tolerant {Silene conipacla) and a non- Cu-tolerant {Thlaspi ochroleucum) species. The initial fluorescence level (Fq) increased whereas the variable fluorescence (Fy) decreased in T. ochroleucum under low and high Cu-dose, suggesting injuries both in reaction centie level and in photooxidizing side of photosystem 2 (PS2). The photochemistiy activity of PS2, Fy/Fp, revealed a slight increase under 8 pM Cu in both species, while at 160 pM of Cu a strong inhibition in T. ochroleucum was observed. The Fp/F() ratio appeared to increase under low Cu dose, however the high Cu dose in nutrient solution resulted in damage to the thylakoid structure affecting the PS2 donor and acceptor side, mainly in T. ochroleucum. The slow part of the Chl fluorescence induction cuiwe was affected more by Cu stress, than the fast one. At low Cu concentration the Rfd value increased in S. compacla but decreased in T. ochroleucum. Fligh Cu dose induced an almost complete inhibition of this parameter, that was more severe in the non-tolerant plants. Yet, low Cu dose enhanced the Chl content in S. compacla but on exposure to 160 pM Cu the symptoms of chlorosis were more visible in T. ochroleucum. Thus, excess of Cu has direct negative effects on the photosynthetic electron transport that may be accounted for by the destruction of the photosynthetic pigments.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

546. Changes of S-adenosyl-L-methionine: magnesium protoporphyrin IX methyltransferase activity in wheat after treatment with S-aminolevulinic acid

Creator:
Yaronskaya, E.B., Shalygo, N.V., Rassaina, V.V., and N.G.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Following treatment with 5-aminolevulinic acid the activity of iS-adenosyl-L- methionineimagnesium protoporphyrin IX methyltransferase (EC 2.1.1.11) in wheat leaves decreased, whereas monomethyl ester magnesium protoporphyrin IX and protochlorophyllide accumulated. The inactivation of the enzyme was the result of a cessation of the enzyme-product complex dissociation because of the limited number of porphyrin-binding sites on the structural carrier.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

547. Changes of the delayed fluorescence characteristics in Spirulina, Anabaena and Chlorella in response to chromatic adaptatíon and irradiance

Creator:
Znak, N.Y. and Morgun, V.N.
Format:
print
Type:
model:internalpart and TEXT
Subject:
chlorophyll, reaction centres, phycobilins, photosystem 2/ photosystem 1, photosynthetic electron transport, fluorescence induction, fluorescence emission spectra, and diuron
Language:
Multiple languages
Description:
Effíciency of the energy transformation for CO2 fixation (E), and kinetics of the initial 02-mediated electron transport of Spimlina platemis (Gom.) Geitl. and Chlorella vulgaris Beijerinck cells were measured after adaptation to various growth irradiances (7) by means of the delayed fluorescence (DF) induction curves. Maxima of the membrane potential expenses during induction period were observed at I half saturating oxygen evolution; they were shifted according to growth 1 remaining higher in Spirulina than in Chlorella. The alterations of absorbance and fluorescence spectra at 25 oC after adaptation to / demonstrated changes in composition of pigments of algae, created to compensate for the imbalance in radiation absorption between the two photosystems. For Spirulina cells, the value of E was higher after growing under low /, or under blue radiation absorbed mainly by photosystem (PS) 1 (400-500 nm) with excitation by yellow (570 nm) radiation. For Chlorella cells, it was also higher after growing under low I. Under such conditions the half-rise time for DP-phase of DF induction curve decreased, which reflected an acceleration of kinetics of the initial electron transport between photosystems. An opposite situation was observed with Spirulina cells grown under high I or yellow radiation, and Chlorella cells from high I. Enhancement of effective PS2/PS1 ratio associated with decrease of reaction centre (RC) 2/RCl stoichiometry may be a cause of the increase of E and high membrane energization under saturating I in algae adapted to low 1.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public