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PubMed2000

A survey of trace elements in pteridophytes.

Concentration of 11 trace elements (Ca, Sc, Cr, Fe, Co, Zn, Rb, Cs, Ba, La, and Ce) in 96 pteridophytes (fern and fern ally species) was determined by instrumental neutron activation analysis to evaluate a concentration range for each element and also to find species characteristic in the uptake of trace elements. Asplenium trichomanes was found to accumulate Sc, Cr, and Co to the highest concentrations among 96 pteridophytes. The highest concentration of Ca and Zn was observed for Asplenium obscurum. The other Pteridophytes exhibited only one element whose concentration was the highest. A positive correlation was found between the concentrations of Fe and Sc, and also between the concentrations of Cr and Co. The remarkable accumulation of lanthanides (La and Ce) was observed mainly in diversifying genera (Polystichum and Dryopteris in Dryopteridaceae, Diplazium in Woodsiaceae, and Asplenium in Aspleniaceae).

Metals, Rare Earth↗

PubMed1989

Calcium requirement of phytochrome-mediated fern-spore germination: no direct phytochrome-calcium interaction in the phytochrome-initiated transduction chain.

Phytochrome-mediated germination of fern spores of Dryopteris paleacea Sw. was initiated by a saturating red-light (R) irradiation after 20 h of imbibition. For its realization external Ca2+ was required, with a threshold at a submicromolar concentration, and an optimum was reached around 10(-4) M. At concentrations > or = 10(-1) M only a reduced response was obtained, based probably on an unspecific osmotic or ionic effect. The germination response was inhibited by La3+, an antagonist of Ca2+. From these results it is concluded that Ca2+ influx from the medium into the spores may be an important event in phytochrome-mediated germination. In the absence of Ca2+ the R-stimulated system remained capable of responding to Ca2+, added as late as 40 h after R. Moreover, Ca2+ was effective even if added after the active form of phytochrome, Pfr, had been abolished by far-red (FR) 24 h after R. Thus, the primary effect of Pfr, that initiates the transduction chain, does not require calcium. "Coupling" of Pfr to subsequent dark reactions has been investigated by R-FR irradiations with various dark intervals. The resulting "escape kinetics" were characterized by a lag phase (6 h) and half-maximal escape from FR reversibility (19 h). These kinetics were not significantly changed by the presence or absence of calcium. Thus, direct interaction of Pfr and calcium is not a step in the transduction chain initiated by the active form of phytochrome.

Calcium↗

PubMed2001

[Six new species and two new records of (Pteridophyta) from Costa Rica ].

Six new species of Pteridophyta from Costa Rica are described: Dryopteris flaccisquama A. Rojas, Hypolepis lellingeri A. Rojas, H. moraniana A. Rojas, Melpomene alan-smithii A. Rojas, Selaginella osaënsis A. Rojas and Terpsichore esquiveliana A. Rojas. Blechnum stoloniferum (Mett. ex E. Fourn.) C. Chr. and Trichomanes micayense Hieron. are new records for the country. Only D. flaccisquama and M. alan-smithii are present outside Costa Rica.

Costa Rica↗

PubMed2005

[Interspecific association between understory species in a southern highland plantation].

Based upon 2 x 2 contingency table, chi2 test and association coefficient were used to determine the interspecific association between understory species in a southern highland plantation, and to analyze the restoration degree and the stability of southern highland vegetations originated from plantation. The Qianyanzhou in Taihe County of Jiangxi Province, a typical sample of southern highland plantation, was chosen to make the study. The results showed that both in shrub layer and in herb layer, species pair with chi2 reaching significant level (P <0.05) was few in number. In shrub layer, 12 species pairs' association was highly significant (P < 0.01), 19 pairs' was significant (P < 0.05), and other 200 pairs' was nonsignificant, while in herb layer, 11 pairs' was highly significant, 11 pairs' was significant and other 83 pairs' was nonsignificant. According to interspecific association and correlation, shrub layer was divided into two species groups: Group I . Adinandra bockiana, Syzygiumn grijsii, Vaccinium bracteatunm, Ilex aculeolata, Smilax ferox, Eurya muricata and Group II . Lespedeza davidii, Serissa serissoides, Vitex negundo var. cannabifolia. Many species in Group I had a significantly negative association with the species in Group II, and dominant species always played a key role in the relationships among species. The three dominant species in herb layer, Wooduardia japonica, Dryopteris atrata and Adiantun flabellulaturn, had a highly significant positive correlation between each other, and moreover, had a significant or highly significant positive association with many other herbaceous species. Similarily, dominant species in shrub layer played a key role on the interspecific association in the two species groups. The ratios of positive and negative association indicating the species compositions of the two layers were fluctuating, which was 125/106 in shrub layer and 42/63 in herb layer. Several shortcomings of interspecific association method were pointed out, with some proposals put forward.

Biodiversity↗

PubMed2006

[Experimental study of estrogenic activities of five kinds of Chinese herbal medicines].

OBJECTIVE: To evaluate the estrogenic activity of several kinds of Chinese herbal medicines. METHOD: Use zoopery and reporter gene technique to study the estrogenic activity of five Chinese herbal medicines. Zoopery: weanling female Kunming mice weight 9-12 g were administrated botanical extracts of Selaginella tamariscina, Pinus Massoniana, Corallodiscus flabellate, Dryopteris sublaeta and Leonurus heterophyllus, the positive control group with Nilestriol tablets and control group with water, respectiely. On the eighth day, the animals were sacrificed and the uteri were separated solely and weighed. Reporter gene technique: Induce the expression of reporter gene controlled by ERE and measure the activity of luciferase on cell's clear supernatant. RESULT: The botanical extracts of S. tamariscina can increase weights of mice (P < 0.01); In the expression of reporter gene controlled by ERE, Either ERalpha or ERbeta's has estrogenic activity (P < 0.01). Follow in the zoopery we find the water part and the n-butanol part of S. tamariscina are the two active parts. CONCLUSION: S. tamariscina and it's water part and n-butanol part have estrogenic activities, effect on ERbeta is greater than ERalpha.

Animals↗

PubMed1953