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PubMed2004

Absorption of foliar-applied arsenic by the arsenic hyperaccumulating fern (Pteris vittata L.).

The fact that heavy metals can enter various domains of the plant system through foliar pathways spurred us to explore if the fronds of the Chinese brake fern (Pteris vittata L.), a hyperaccumulator of arsenic, a carcinogenic metalloid, was proficient in absorbing arsenic in the form of sprays. The specific objective of this study was to investigate the impact of frond age, form of arsenic, and time of application on the absorption of foliar-applied arsenic by the brake fern; also examined were the effects of foliar sprays on surface ultrastructure and arsenic speciation in the frond following absorption. Foliar sprays of different arsenic concentrations (0, 50, 100, 200, and 400 ppm) were applied to young and fertile fronds. A positive linear relationship existed between arsenic concentration and absorption; the arsenic concentration of fronds increased from 50 to 200 ppm. Time-course analysis with excised pinnae indicated an initial linear increase followed by a plateau at 48 h. The young fronds with immature sori absorbed more arsenic (3100 ppm) than the fertile mature fronds (890 ppm). In the frond, the arsenic absorption was greatest in the lamina of the pinnae followed by the sori and the rachis. Applying arsenic during night (20:00-22:00 h) or afternoon (12:00-14:00 h) resulted in greater absorption of arsenic than the application in the morning (08:00-10:00 h). The arsenic absorption was greater through abaxial surfaces than through adaxial surfaces. The brake fern absorbed more arsenic when it was applied in the form of arsenite. Regardless of the form of arsenic and the surface it was applied to, arsenic occurred as arsenite, the reduced and the most toxic form of arsenic, after having been absorbed by the fronds. Scanning electron microscopy revealed no surface morphological alterations following all arsenic sprays. The study unequivocally illustrated that the Chinese brake fern absorbed foliar-applied arsenic with great efficiency. Consequently, the arsenic concentrations in the fronds transcended the levels of hyperaccumulation; such a characteristic could be exploited in the phytoremediation of groundwater contaminated with arsenic.

Absorption↗

PubMed1999

Structure comparison between oxidized and reduced plastocyanin from a fern, Dryopteris crassirhizoma.

The X-ray crystal structures of oxidized and reduced plastocyanin obtained from the fern Dryopteris crassirhizoma have been determined at 1.7 and 1.8 A resolution, respectively. The fern plastocyanin is unique in the longer main chain composed of 102 amino acid residues and in the unusual pH dependence due to the pi-pi stacking interaction around the copper site [Kohzuma, T., et al. (1999) J. Biol. Chem. 274, 11817-11823]. Here we report the structural comparison between the fern plastocyanin and other plastocyanins from cyanobacteria, green algae, and other higher plants, together with the structural changes of fern plastocyanin upon reduction. Glu59 hydrogen bonds to the OH of Tyr83, which is thought to be a possible conduit for electrons, in the oxidized state. However, it moves away from Tyr83 upon reduction like poplar plastocyanin.

Amino Acid Sequence↗

PubMed2001

Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants.

Most of the 470-million-year history of plants on land belongs to bryophytes, pteridophytes and gymnosperms, which eventually yielded to the ecological dominance by angiosperms 90 Myr ago. Our knowledge of angiosperm phylogeny, particularly the branching order of the earliest lineages, has recently been increased by the concurrence of multigene sequence analyses. However, reconstructing relationships for all the main lineages of vascular plants that diverged since the Devonian period has remained a challenge. Here we report phylogenetic analyses of combined data--from morphology and from four genes--for 35 representatives from all the main lineages of land plants. We show that there are three monophyletic groups of extant vascular plants: (1) lycophytes, (2) seed plants and (3) a clade including equisetophytes (horsetails), psilotophytes (whisk ferns) and all eusporangiate and leptosporangiate ferns. Our maximum-likelihood analysis shows unambiguously that horsetails and ferns together are the closest relatives to seed plants. This refutes the prevailing view that horsetails and ferns are transitional evolutionary grades between bryophytes and seed plants, and has important implications for our understanding of the development and evolution of plants.

Biological Evolution↗

PubMed2003

Responses of ferns to red light are mediated by an unconventional photoreceptor.

Efficient photosynthesis is essential for plant survival. To optimize photosynthesis, plants have developed several photoresponses. Stems bend towards a light source (phototropism), chloroplasts move to a place of appropriate light intensity (chloroplast photorelocation) and stomata open to absorb carbon dioxide. These responses are mediated by the blue-light receptors phototropin 1 (phot1) and phototropin 2 (phot2) in Arabidopsis (refs 1-5). In some ferns, phototropism and chloroplast photorelocation are controlled by red light as well as blue light. However, until now, the photoreceptor mediating these red-light responses has not been identified. The fern Adiantum capillus-veneris has an unconventional photoreceptor, phytochrome 3 (phy3), which is a chimaera of the red/far-red light receptor phytochrome and phototropin. We identify here a function of phy3 for red-light-induced phototropism and for red-light-induced chloroplast photorelocation, by using mutational analysis and complementation. Because phy3 greatly enhances the sensitivity to white light in orienting leaves and chloroplasts, and PHY3 homologues exist among various fern species, this chimaeric photoreceptor may have had a central role in the divergence and proliferation of fern species under low-light canopy conditions.

Adiantum↗

PubMed1998

A gene encoding a vicilin-like protein is specifically expressed in fern spores. Evolutionary pathway of seed storage globulins.

The isolation and characterisation of a cDNA coding for a vicilin-like protein of the fern Matteuccia struthiopteris is described. The corresponding gene is specifically expressed during late stages of spore development. Extensive sequence comparisons suggest that the fern protein can be considered as a molecular missing link between single-domain germin/spherulin-like proteins and two-domain seed storage globulins of gymnosperms and angiosperms. Further, evidence is provided for the existence of a superfamily of structurally related, functionally different proteins which includes storage globulins of the vicilin and legumin families, a membrane-associated sucrose-binding protein of soybean, a Forssman antigen-binding lectin of velvet bean, the precursor of the vacuolar membrane bound proteins MP27/MP32 of pumpkin, the embryogenesis-specific protein Gea8 of carrot, the fern-spore-specific protein described here as well as the functionally diverse family of germins/germin-like proteins and the spherulins of myxomycetes. We propose that seed storage globulins of spermatophytes evolved from desiccation-related single-domain proteins of prokaryotes via a duplicated two-domain ancestor that is best represented by the extant fern spore-specific vicilin-like protein.

Amino Acid Sequence↗

PubMed1990

Diagnosis of preterm rupture of membranes: is testing for alpha-fetoprotein better than ferning or nitrazine?

This article evaluates the role of alpha-fetoprotein (AFP) testing in the diagnosis of ruptured membranes in the preterm patient. AFP is normally found in amniotic fluid and is not present in vaginal secretions. Testing for AFP in vaginal fluid was compared with nitrazine evaluation and ferning in two groups of preterm patients, those with intact membranes and those with ruptured membranes. There was no difference in the sensitivities of AFP, nitrazine, or ferning in diagnosing ruptured membranes. The specificities of AFP and ferning were similar and both were significantly better than nitrazine. Duration of membrane rupture for greater than 24 hours negatively affected the accuracy of all three tests. Blood-tinged amniotic fluid interfered with AFP and nitrazine evaluation. AFP does not appear to offer a significant advantage over nitrazine testing and ferning in the evaluation of patients with possible ruptured membranes.

Azo Compounds↗

PubMed2004

Phytoremediation of arsenic-contaminated groundwater by the arsenic hyperaccumulating fern Pteris vittata L.

Arsenic concentrations in a much larger fraction of U.S. groundwater sources will exceed the maximum contaminant limit when the new 10 microg L(-1) EPA standard for drinking water takes effect in 2006. Thus, it is important to develop remediation technologies that can meet this new standard. Phytoremediation of arsenic-contaminated groundwater is a relatively new idea. In this research, an arsenic-hyperaccumulating fern, commonly known as Chinese Brake fern (Pteris vittata L.), was grown hydroponically to examine its effectiveness in arsenic removal from what is believed to be herbicide-contaminated groundwater. One plant grown in 600 mL of groundwater effectively reduced the arsenic concentration from 46 to less than 10 microg L(-1) in 3 days. Re-used plants continued to take up arsenic from the groundwater, albeit at a slower rate (from 46 to 20 microg L(-1) during the same time). Young fern plants were more efficient in removing arsenic than were older fern plants of similar size. The addition of a supplement of phosphate-free Hoagland nutrition to the groundwater had little effect on arsenic removal, but the addition of phosphate nutrition significantly reduced its arsenic affinity and, thus, inhibited the arsenic removal. This study suggested that Chinese Brake has some potential to remove arsenic from groundwater.

Arsenic↗

PubMed1999

SEM Studies on Vessels in Ferns. XV. Selected Rosette Epiphytes (Aspleniaceae, Elaphoglossaceae, Vittariaceae).

Tracheary elements from macerations of roots and rhizomes of Asplenium nidus, Elaphoglossum hirtum, and Vittaria lineata were studied by means of SEM. All of these have perforation plates in tracheary elements of both roots and rhizomes. The perforation plates in roots and rhizomes show greatest development of perforations (perforations a little wider than pits of tracheary elements) in E. hirtum roots and rhizomes and least in V. lineata roots and in rhizomes of A. nidus (porose pit membranes in many perforations). The secondary wall framework of perforation plates is little different from that of pitted wall areas in these three species. These rosette epiphytes have a lower degree of specialization of perforation plates that might accommodate rapid flow related to moisture availability fluctuations in comparison to perforation plates in vessels of rhizomatous epiphytic ferns. Generalizations are not warranted at this point, however. Rows of cushion-like structures occur adjacent to angles of the tracheary elements of E. hirtum. This is the first report of these in leptosporangiate ferns; they are known thus far only in a eusporangiate fern, Danaea elliptica (Marattiaceae). Raised frames of wall material around perforations are newly reported for tracheary elements of ferns in E. hirtum.

Journal Article↗

PubMed1998

The repeatability of tear mucus ferning grading.

PURPOSE: Rolando's classification system for tear mucus ferning patterns subjectively assigns grades based on the size and spacing between ferns. Grade 1 and 2 patterns are considered "normal," whereas grade 3 and 4 patterns are often associated with keratoconjunctivitis sicca. This study was designed to examine the intraobserver and interobserver repeatability of Rolando's system. METHODS: Photographic slides (N = 418) of portions of tear ferning patterns were randomly assembled, numbered, and graded by two investigators (I1 and I2). I1 graded the slides twice; the slides were remixed under masked conditions between the first and second runs. I2 graded the slides once, independent of I1. RESULTS: For the four-grade system, intraobserver agreement was 85.41% (simple kappa = 0.75; 95% confidence interval ]CI] = 0.69-0.82). Interobserver agreement was 80.62% (kappa = 0.67; CI = 0.60-0.74) and 86.12% (kappa = 0.75; CI = 0.68-0.83) for the first and second runs of I1, respectively. Analysis of the ability to simply classify normal (grade 1 and 2) from abnormal (grade 3 and 4) patterns revealed intraobserver repeatability of 94.50% (kappa = 0.76; CI = 0.67-0.86). Interobserver agreement was 92.10% (kappa = 0.65; CI = 0.56-0.75) and 94.26% (kappa = 0.71; CI = 0.62-0.81) for the first and second runs, respectively. CONCLUSION: Based on the high rate of agreement between intraobserver and interobserver trials, Rolando's grading system appears to be an easy and consistent method for the classification of tear ferning patterns.

Adolescent↗

PubMed2000

Cryptochrome nucleocytoplasmic distribution and gene expression are regulated by light quality in the fern Adiantum capillus-veneris.

Numerous cellular responses are reportedly regulated by blue light in gametophytes of lower plants; however, the molecular mechanisms of these responses are not known. Here, we report the isolation of two blue light photoreceptor genes, designated cryptochrome genes 4 and 5 (CRY4 and CRY5), from the fern Adiantum capillus-veneris. Because previously we identified three cryptochrome genes, this fern cryptochrome gene family of five members is the largest identified to date in plants. The deduced amino acid sequences of the five genes show remarkable similarities with previously identified cryptochromes as well as class I photolyases. Like the other plant cryptochromes, none of the cryptochromes of this fern possesses photolyase activity. RNA gel blot analysis and competitive polymerase chain reaction analysis indicate that the expression of the newly identified CRY4 and CRY5 genes is regulated by light and is under phytochrome control. The intracellular distribution of reporter beta-glucuronidase (GUS)-CRY fusion proteins indicates that GUS-CRY3 and GUS-CRY4 localize in fern gametophyte nuclei. The nuclear localization of GUS-CRY3 is regulated in a light-dependent manner. Together with our physiological knowledge, these results suggest that CRY3, CRY4, or both might be the photoreceptor that mediates inhibition of spore germination by blue light.

Amino Acid Sequence↗

PubMed1978

Occupational allergic contact dermatitis due to leatherleaf fern Arachniodes adiantiformis (Forst) Tindale.

Leatherleaf fern has been imported from the United States, Honduras and Puerto Rico to the Federal Republic of Germany since 1966 and cultivated in Germany since 1970/71. It is slowly displacing the floral arrangements with asparagus used until now as filler and background material. This change is due primarily to its better keeping quality. Continuous contact with the leatherleaf fern induced an allergic contact dermatitis of the palms and fingers in a female florist. Patch tests with the leaf revealed the allergic origin of the dermatitis. Five fractions of a chromatographically separated extract of the fern were tested on sensitized guinea-pigs and on the patient. Only the first fraction gave a positive patch test response. By further separation colourless crystals of the contact allergen could be obtained. Elucidation of the structure is in progress. The sensitizer could only be detected during sporogenesis of the fern, that means when sporecapsules are present on the surface of the leaves.

Adult↗

PubMed1988

Quantitative tear ferning. Methodologic and experimental investigations.

The reproducibility of different tear-ferning methods has been investigated by double tests on 122 subjects. Rough grading according to Rolando gives identical recovery in only 42 to 50%. Quantitative test (mm2 ferning per 1 microliter) of conjunctival fluid drawn with a glass rod according to Rolando gave a coefficient of variation of 99 to 128%. Aspiration with a quantitative pipette acc. to Norn 79%, and 55% for a standardized dilution (2.5 microliters of water) in the same pipette. The coefficient of variation was lower between tear samples aspirated through a thin capillary tube (1 mm = 0.5 microliter) from the lateral part of the tear meniscus (35%), and with a standardized tear volume (2.5 microliters) only 6.4%. Ferning is obstructed by ointment, fat emulsion dropped on the conjunctiva and mucous thread, but not by a glass slide rubber with stearin. A quantitative test with a capillary tube (2.5 microliters of aspirated lacrimal fluid) showed reduced ferning 30 sec after instillation of methylcellulose (2.5%) and arachis oil, and after expression of meibomian gland secretion. No significant alteration was observed after instillation of water or stimulation of the tear secretion by nasal inhalation of NH4OH.

Crystallization↗

PubMed2001

Anatomically preserved Woodwardia virginica (Blechnaceae) and a new filicalean fern from the middle Miocene Yakima Canyon flora of central Washington, USA.

Anatomically preserved Woodwardia virginica (Blechnaceae) and a newly recognized onocleoid fern are described from the middle Miocene Yakima Canyon flora of central Washington State, USA. Identification of the W. virginica fossils is based on a combination of vegetative pinnules, rhizome and stipe anatomy, and fertile pinnules with indusiate sori and sporangia like those of extant W. virginica. Fronds are isomorphic. Vegetative pinnae are elongated and pinnatifid, with a secondary vein paralleling the midvein. Secondary veins of the pinnule lobe anastomose to form primary areoles and are either simple or dichotomize toward the margin. Rhizomes have a simple dictyostele with 3-5 cauline vascular bundles and often a sclerotic hypodermis. Leaf traces contain two large adaxial vascular bundles that occur laterally and adaxially, flanking an arc of 4-6 smaller bundles. Fertile pinnules have linear sori that are somewhat embedded in the laminae and are enclosed by a thin indusium. Leptosporangia display a vertical annulus and an elongated stalk. A second fern, Wessiea yakimaensis gen. et sp. nov., is represented by anatomically preserved branching rhizomes and attached frond bases that conform to the Onoclea-type pattern of rhizome and frond-base vasculature. Rhizomes have a simple dictyostele of 4-5 cauline meristeles. Leaf divergence is helical, with paired hippocampiform rachial traces. These two ferns occur in the same matrix with specimens of Osmunda wehrii. They demonstrate that filicalean fern assemblages similar to those of extant temperate floras were well established in western North America by the middle Miocene and further emphasize the exceptional species longevity of some homosporous pteridophytes.

Journal Article↗

PubMed1987

Positive skin tests to fern spore extracts in atopic patients.

Thirty-six atopic and eight non-atopic adult volunteers who had been exposed to ferns in their homes, were skin tested with extracts obtained from seven species of house ferns. Out of the 36 atopic patients, 18 had positive skin reactions to at least one out of seven species of the most common house ferns, whereas none of the non-atopic, healthy controls had positive reactions to any of the ferns.

Humans↗

PubMed1985

Human carcinogenic risk in the use of bracken fern.

Young bracken fern is used as a human food in Japan and other countries. However, it has been demonstrated that bracken is carcinogenic to cattle and laboratory animals such as rats, mice, and guinea pigs. Rats fed a diet containing bracken fern developed tumors of the ileum and urinary bladder. Mammary cancer was also induced in Sprague-Dawley rats fed a bracken diet. Study of the human cancer risk of this plant is thus of great importance. The fern is usually used as a food-stuff in Japan after it is treated with plain boiling water or boiling water containing wood ash or sodium bicarbonate; sometimes, bracken is pickled in salt. Although the carcinogenic activity of processed bracken thus prepared was reduced markedly, weak activity was still retained. This paper deals with the carcinogenicity of unprocessed and processed bracken fern to laboratory animals and its human cancer risk.

Animals↗

PubMedDate not supplied

Is the salivary "ferning" a reliable index of the fertile period?

We found that the fern leaf crystallisation of human saliva is a non-specific phenomenon, independent on the action of estrogenic hormones. Salivary ferning can be obtained in practice during the whole menstrual cycle and occurs in the saliva of postclimateric, pregnant and prepuberal women. Even the saliva of male subjects gives invariably the ferning reaction. In conclusion, salivary ferning does not seem a reliable method to establish woman fertile period.

Crystallization↗

PubMed2006

Effects of five rice herbicides on the growth of two threatened aquatic ferns.

The effects of five rice herbicides bensulfuron methyl, mefenacet, quinoclamine, simetryn, and thiobencarb on the growth of two threatened aquatic ferns Azolla japonica and Salvinia natans were tested using 12-day exposure experiments at 0.1-100 nM which are expected to be present in drainages and rivers in Japan. As a reference species, Lenma minor was also used to examine the toxicity of bensulfuron methyl. Bensulfuron methyl had the most pronounced effect on the relative growth rate (RGR) of A. japonica, S. natans, and L. minor with an EC50 of 5.0, 0.54, and 10 nM, respectively. The other herbicides reduced the RGR of the aquatic ferns only at the highest concentration (100 nM) or not at all. S. natans showed the highest susceptibility to bensulfuron methyl among the three species, and the EC50 for this species was comparable to or below the maximum concentration (0.49-5.6 nM) that had been previously detected in 7 of 11 rivers in Japan. These results suggest that bensulfuron methyl runoff in drainages and rivers in Japan is expected to have adverse effects on the growth of threatened aquatic ferns in some cases, and that no or small effects occur for the other four herbicides tested.

Dose-Response Relationship, Drug↗

PubMed2004

Unraveling the phylogeny of polygrammoid ferns (Polypodiaceae and Grammitidaceae): exploring aspects of the diversification of epiphytic plants.

We explore the phylogeny of the polygrammoid ferns using nucleotide sequences derived from three plastid loci for each of 98 selected species. Our analyses recovered four major monophyletic lineages: the loxogrammoids, two clades consisting of taxa restricted to the Old World, and a largely neotropical clade that also includes the pantropical Grammitidaceae. The loxogrammoid lineage diverges first and is sister to a large clade comprising the three remaining species-rich lineages. One paleotropical clade includes the drynarioid and selligueoid ferns, whereas the second paleotropical clade includes the platycerioids, lepisoroids, microsoroids, and their relatives. The grammitids nest within the neotropical clade, although the sister taxon of this circum-tropic, epiphytic group remains ambiguous. Microsorum and Polypodium, as traditionally defined, were recovered as polyphyletic. The relatively short branch lengths of the deepest clades contrast with the long branch lengths leading to the terminal groups. This suggests that the polygrammoid ferns arose through an old, rapid radiation. Our analysis also reveals that the rate of substitution in the grammitids is remarkably higher relative to other polygrammoids. Disparities in substitution rate may be correlated with one or more features characterizing grammitids, including species richness, chlorophyllous spores, and an extended gametophytic phase.

Classification↗