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PubMed1997

Methylation of somatic and sperm DNA in the homosporous fern Ceratopteris richardii.

Plants, in general, have a high proportion of their CpG and CpNpG nucleotide motifs modified with 5-methylcytosine (5mC). Developmental changes in the proportion of 5mC are evident in mammals, particularly during gametogenesis and embryogenesis, but little information is available from flowering plants due to the intimate association of gametes with sporophytic tissues. In ferns, sperm are uninucleate and free-swimming and thus are easily isolated. We have examined 5mC in DNA isolated from fern sperm and other tissues with methylation-sensitive and -insensitive restriction enzyme isoschizomers, Southern blots probed with chloroplast and nuclear ribosomal RNA genes and end-labeled restriction fragments. We conclude that fern sperm DNA is methylated to a similar or greater degree than DNA isolated from either sporophytes or gametophytes.

Chloroplasts↗

PubMed2000

Carcinogenic effects of ptaquiloside in bracken fern and related compounds.

Consumption of the bracken fern Pteridium aquilinum by cattle has been shown to induce bladder and intestinal carcinomas in cattle and to cause a number of diseases in other farm animals. An unstable glucoside named ptaquiloside, containing a reactive cyclopropane ring, has been isolated from the fern and its potent carcinogenicity proven. Nineteen of 31 ferns tested by chemotaxonomic methods in Japan have been found to contain potentially carcinogenic ptaquilosides as have Cheilanthes sieberi and Pteridium esculentum. Hydrolysis of ptaquilosides leads to pterosins; under milder conditions a dienone which is believed to be the primary carcinogen is obtained. Hypacrone, a sesquiterpine containing a reactive cyclopropane ring, has been isolated from Hypolepis punctata and its structure proved by synthesis. Illudins, structurally similar to ptaquiloside, have been isolated from the basidiomycete Omphalotus illudens. These give anti-tumour activity and similar reactivity with nucleophiles to ptaquiloside. Compound CC-1065, a highly toxic antibiotic also containing a cyclopropane ring, has been isolated from Streptomyces zelensis. The mechanism of its reactivity with DNA has been compared to that of ptaquiloside and the small structural differences between carcinogenic and anti-tumour activity discussed. Both CC-1065 and adozelesin, a synthetic analogue with anti-tumour activity, have been shown to alkylate the N-3 atom of adenine in a certain sequence of DNA. The reactivity of cysteine with ptaquilosides and illudins is discussed, as is the role of cysteine alkylating agents in apoptosis.

Animals↗

PubMed1997

Floral homeotic genes were recruited from homologous MADS-box genes preexisting in the common ancestor of ferns and seed plants.

Flowers sensu lato are short, specialized axes bearing closely aggregated sporophylls. They are typical for seed plants (spermatophytes) and are prominent in flowering plants sensu stricto (angiosperms), where they often comprise an attractive perianth. There is evidence that spermatophytes evolved from gymnosperm-like plants with a fern-like mode of reproduction called progymnosperms. It seems plausible, therefore, that the stamens/carpels and pollen sacs/nucelli of spermatophytes are homologous to fern sporophylls and sporangia, respectively. However, the exact mode and molecular basis of early seed and flower evolution is not yet known. Comparing flower developmental control genes to their homologs from lower plants that do not flower may help to clarify the issue. We have isolated and characterized MADS-box genes expressed in gametophytes and sporophytes of the fern Ceratopteris. The data indicate that at least two different MADS-box genes homologous to floral homeotic genes existed in the last common ancestor of contemporary vascular plants, some descendants of which underwent multiple duplications and diversifications and were recruited into novel developmental networks during the evolution of floral organs.

Amino Acid Sequence↗

PubMed1999

The structure and unusual pH dependence of plastocyanin from the fern Dryopteris crassirhizoma. The protonation of an active site histidine is hindered by pi-pi interactions.

Spectroscopic properties, amino acid sequence, electron transfer kinetics, and crystal structures of the oxidized (at 1.7 A resolution) and reduced form (at 1.8 A resolution) of a novel plastocyanin from the fern Dryopteris crassirhizoma are presented. Kinetic studies show that the reduced form of Dryopteris plastocyanin remains redox-active at low pH, under conditions where the oxidation of the reduced form of other plastocyanins is inhibited by the protonation of a solvent-exposed active site residue, His87 (equivalent to His90 in Dryopteris plastocyanin). The x-ray crystal structure analysis of Dryopteris plastocyanin reveals pi-pi stacking between Phe12 and His90, suggesting that the active site is uniquely protected against inactivation. Like higher plant plastocyanins, Dryopteris plastocyanin has an acidic patch, but this patch is located closer to the solvent-exposed active site His residue, and the total number of acidic residues is smaller. In the reactions of Dryopteris plastocyanin with inorganic redox reagents, the acidic patch (the "remote" site) and the hydrophobic patch surrounding His90 (the "adjacent" site) are equally efficient for electron transfer. These results indicate the significance of the lack of protonation at the active site of Dryopteris plastocyanin, the equivalence of the two electron transfer sites in this protein, and a possibility of obtaining a novel insight into the photosynthetic electron transfer system of the first vascular plant fern, including its molecular evolutionary aspects. This is the first report on the characterization of plastocyanin and the first three-dimensional protein structure from fern plant.

Amino Acid Sequence↗

PubMed2006

Arsenic uptake and accumulation in fern species growing at arsenic-contaminated sites of southern China: field surveys.

Aiming at searching for new arsenic (As) hyperaccumulators, field surveys were conducted at 12 As-contaminated sites located in Guangxi and Guangdong Provinces of southern China. Samples of 24 fern species belonging to 16 genera and 11 families as well as their associated soils were collected and As concentrations in plant and soil samples were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results show that among 24 fern species, Pteris multifida and P. oshimensis can (hyper)accumulate As in their fronds with high concentrations in addition to P. vittata and P. cretica var. nervosa, which have been previously identified as As hyperaccumulators. Total As concentrations in soils associated with P. multifida and P. oshimensis varied from 1262 to 47,235 mg kg(-1), but the DTPA-extractable As concentrations were relatively low, with a maximum of 65 mg kg(-1). Forty-four of 49 samples of P. multifida collected from five sites and 3 of 13 samples of P. oshimensis collected from one site accumulated over 1000 mg As kg(-1) in their fronds and As concentrations in the fronds were higher than those in the petioles and rhizoids. Although As concentrations in the fronds of P. oshimensis (789 mg kg(-1) averaged, range 301-2142 mg kg(-1)) were comparatively lower than those of P. multifida (1977 mg kg9-1), 624-4056 mg kg(-1)), its high aboveground biomass makes it more suitable for phytoremediating As-contaminated soils. Among all the species in Pteris genus studied, Pteris semipinnata accumulated only very low As concentration in its fronds (8 mg kg(-1), 1-18 mg kg(-1)). Further research is needed to study the differences in As uptake and accumulation among fern species in the same or other genera.

Arsenic↗

PubMed1996

The relationship of endophytic fungi to the gametophyte of the fern Schizaea pusilla.

Schizaea pusilla is a rare and threatened fern restricted in North America to acidic bogs of Nova Scotia, Newfoundland, and New Jersey. The gametophyte lives in close association with two endophytic fungi. To characterize the nature of this fern's relationship with these fungi, we introduced axenic gametophytes to bog soil for colonization. Following colonization, the endophytic fungi were isolated and reintroduced to axenic gametophytes. The gametophytes introduced to bog soil were colonized by an aseptate fungus that formed vesicles and arbuscules within the gametophyte. However, culture of colonized gametophytes produced two fungal isolates: an aseptate fungus (fungus B) and a septate fungus (fungus A). Upon reintroduction of fungal isolates to axenically grown gametophytes, the aseptate fungus demonstrated a positive growth response to the presence of the gametophytes and colonized the gametophytes without harm to the host. The septate fungus did not exhibit any specific recognition but contacted the gametophytes randomly, leaving a large percentage of the host nonviable. We propose that the relationship of the septate fungus to the gametophyte of S. pusilla is nonmycorrhizal while the relationship of the aseptate fungus to the gametophyte is mycorrhizal. Furthermore, based on lack of nutrient availability in local soils, formation of specialized structures in the gametophyte for harboring fungi, and dependence of the fern on fungal presence for completion of its life cycle, we propose that S. pusilla maintains an obligatory relationship with the aseptate mycorrhizal fungus.

Calcium↗

PubMed2000

Investigations into the Genetic Variation, Population Structure, and Breeding Systems of the Fern Asplenium trichomanes subsp. quadrivalens.

The genetic structure of five populations of the tetraploid fern Asplenium trichomanes subsp. quadrivalens in northern Switzerland was analyzed. Asplenium trichomanes subsp. quadrivalens is one of the most common and most widespread ferns in Europe. In this study we have combined genetic investigations, spatial autocorrelation, and breeding experiments to investigate in detail five populations from natural rock faces. Enzyme electrophoresis revealed very low genetic variability within and among the populations. The small amount of variation was partitioned mainly among the localities, indicated by high Fst values up to 0.764. Overall means of the proportion of polymorphic loci (P=0.076), the mean number of alleles per locus (A=1.086), and the mean expected heterozygosity (H=0.018) were low compared with other ferns (e.g., Kirkpatrick et al. 1990). Very few heterozygous individuals were found. Values of the fixation index (F) were high, ranging between 0.732 and 1.000 and indicating substantial inbreeding. Spatial autocorrelation showed different patterns of substructure in populations of A. trichomanes subsp. quadrivalens with a tendency for patches in short distances (up to 1.5 m). The breeding experiments with isolated prothalli and prothalli pairs showed that a mean of 56.4% of the isolated prothalli were successful in sporophyte formation. The highest rate in one population was 83.3%. We conclude that genetic load must be low in A. trichomanes subsp. quadrivalens. Sporophyte formation was statistically more successful in the experiments with gametophyte pairs than in isolates, indicating that additional cross-fertilization occurred. The latter agreed with the occurrence of few heterozygote samples and the small number of multilocus phenotypes found in natural habitats. Asplenium trichomanes subsp. quadrivalens is shown to be a highly inbreeding taxon with the capability of single spore colonization and subsequent founding of new populations. Such features can be hypothesized to have contributed to the postglacial colonization and the widespread distribution of this taxon in Europe.

Journal Article↗

PubMed1982

Purification and amino acid sequence of a fern (Gleichenia japonica) ferredoxin.

A chloroplast-type ferredoxin was purified from a fern, Gleichenia japonica, and its amino acid sequence was determined. The conventional method for soft leaves proved to be unsuitable for the extraction of ferredoxin from G. japonica, but a good yield was obtained by blending the leaves in cold acetone. The analysis of 8 tryptic peptides of Cm-ferredoxin gave the complete amino acid sequence. The molecule consisted of a single polypeptide chain of 95 amino acid sequence. The molecule consisted of a single polypeptide chain of 95 amino acid residues and lacked tryptophan. Relatively high contents of phenylalanine and arginine were noted, some of which had unique locations in comparison with other ferredoxins. G. japonica ferredoxin did not show a close sequence homology with the ferredoxins from horsetails, which, like ferns, belong to Pteridophyta, or with those from plants of different taxonomical groups. The fern ferredoxins were suggested to form a unique group in the chloroplast-type ferredoxins.

Acetone↗

PubMed1991

Factors responsible for tear ferning.

The biochemical agents involved in fern formation on drying tears were investigated by studying the different patterns of ferning of tears from normal and pathological eyes, mucus glycoprotein, saliva, serum, and various salt solutions. We conclude that the ferning phenomenon observed when a drop of tears is allowed to dry at room temperature on a clean microscope slide is to a large extent determined by the electrolyte concentration, especially the ratio of monovalent sodium and potassium ions to divalent calcium and magnesium ions. The presence of a biopolymer is essential, but this need not specifically be mucus as previously thought. The test may therefore be useful clinically in indicating the need for further tear analysis.

Electrolytes↗

PubMed2001

How early ferns became trees.

A new anatomically preserved fern, discovered from the basalmost Carboniferous of Australia, shows a unique combination of very primitive anatomical characters (solid centrarch cauline protostele) with the elaboration of an original model of the arborescent habit. This plant possessed a false trunk composed of a repetitive branching system of very small stems, which established it as the oldest tree-fern known to date. The potential of this primitive zygopterid fern to produce such an unusual growth form-without real equivalent among living plants-is related to the possession of two kinds of roots that have complementary functional roles: (i) large roots produced by stems with immediate positive geotropism, strongly adapted to mechanical support and water uptake from the soil; and (ii) small roots borne either on large roots or on petiole bases for absorbing humidity inside the false trunk.

Biological Evolution↗

PubMed1970

Interaction between Antheridogens and Fatty Acids in Fern Spore Germination.

Certain fatty acids in the C(5) to C(18) range, at concentrations as low as 10(-5) M, were found to inhibit the germinations of spores of the sensitive fern, Onoclea sensibilis L. The addition of gametophytic culture flltrates of the bracken fern, Pteridium aquilinum (L.) Kuhn, containing antheridogen A, was found to overcome this inhibition and allow the spores to germinate and the gametophytes to develop in a normal fashion. Some fatty acids were found to increase the antheridium-inducing potency of antheridogen A as much as 10-fold. An effect similar to this may promote the diecious reproduction of ferns.

Journal Article↗

PubMed1999

GAMETOPHYTE DEVELOPMENT IN FERNS.

The fern gametophyte has interested plant biologists for the past century because its structure and development is simple and amenable to investigation. Past studies have described many aspects of its development, including germination of the spore, patterns of cell division and differentiation, photomorphogenic or light-regulated responses, sex determination and differentiation of gametangia, hormone and pheromone responses, and fertilization. Several genes that are predicted to regulate some of these processes have been recently cloned, making it possible to analyze how these processes are controlled at a molecular level. The emergence of the fern Ceratopteris richardii as a model organism for readily identifying and characterizing mutations that affect key developmental processes in gametophytes makes it a powerful tool for dissecting the molecular mechanisms underlying these processes. If advances in gene cloning techniques and transformation are forthcoming in Ceratopteris, it is likely that the study of developmental processes in ferns will significantly contribute to our understanding of plant development and evolution beyond that which can be learned solely from studying angiosperms.

Journal Article↗

PubMed1987

An interesting use of the study of tear ferning patterns in contactology.

A study of tear ferning patterns in normal and keratoconjunctivitis sicca eyes led to the classification into 4 types by Rolando [1984]. We practised this in our laboratory and observed specific and distinct tear ferning patterns for electrophoretic types 1 and 2 which Liotet et al. [1983] described as abnormal tear proteins modification found in patients who repeatedly and rapidly clog their hydrophilic lenses. In a general way, a study of tear ferning patterns can result in an appreciation of tear quality in contactology.

Contact Lenses↗

PubMed1983

Ultrastructural aspects of sporogenesis in the apogamous fern Dryopteris borreri.

The events that accompany sporogenesis in the apogamous fern Dryopteris borreri parallel those seen in sexually reproducing ferns. Organelles dedifferentiate and redifferentiate, and form a discrete band across the equator of dyads; nuclear vacuoles and lipid spherosomes appear during prophase, and the major part of the ribosome population is removed and subsequently replaced during meiosis. Similar events have been found to occur during sporogenesis in mosses, gymnosperms and angiosperms, and therefore characteristic of the meiotic transition from sporophyte to gametophyte, even in the absence of a transition from diplophase to haplophase. The novel aspects of meiosis in D. borreri are largely those connected with the restitution event that precedes meiosis I and serves to maintain the sporophytic chromosome number throughout the life cycle of this fern. Pre-meiotic cells are regularly found to be cleaved by annular wall ingrowths, which traverse the cytoplasm but not the nuclei. The significance of these ingrowths in relation to theories concerning apogamy and plant cell division are discussed.

Endoplasmic Reticulum↗

PubMed1986

Carcinogenic principles isolated from bracken fern.

The carcinogenicity of bracken fern, Pteridium aquilinum, was demonstrated most clearly by the experiment of Evans and Mason in 1965. We have performed fractionation of the aqueous extract by means of the assay based on carcinogenicity and isolated an unstable norsesquiterpene glucoside of illudane type named ptaquiloside (PT). It was proved that PT is the carcinogenic principle present in bracken fern, inducing mammary cancer and multiple ileal tumors in high incidences when given orally to female Sprague-Dawley rats. The present review article deals with the explanation of carcinogenicity of bracken fern, progress in separation of carcinogenic fraction, isolation of PT, and its carcinogenic activity in rats.

Animals↗

PubMed1999

Effect of bracken (Pteridium a quilinum) and dryopteris (Dryopteris juxtaposita) fern toxicity in laboratory rabbits.

Experimental studies with Bracken and Dryopteris ferns @ 25% concentrate ration mixture were conducted in rabbits. Fern fed rabbits showed progressive anaemia, leukopaenia, lymphopaenia and relative heterophilia. Significant elevations in serum enzymes like serum glutamate oxaloactate transminase (SGOT), serum glutamate pyruvate transminase (SGPT), alkaline phosphatase (ALP), urea and creatinine levels were seen. Histopathologically, rabbits showed mild to moderate vascular changes in most of visceral organs, vacuolar degenerative changes in hepatocytes, hypersecretory activity in intestine, presence of casts in renal tubules and degenerative changes in renal tubular lining epithelial cells. Dryopteris fed rabbits showed somewhat more severe degenerative and vascular changes in different intervals. A low level of toxic principle ptaquiloside was detected in Bracken and Dryopteris ferns by thin layer chromatography (TLC) and high-pressure liquid chromatography (HPLC) methods.

Animals↗

PubMed1975

Induction of tumors of the urinary bladder in female mice following surgical implantation of glass beads and feeding of bracken fern.

The carcinogenic effect of bracken fern (Pteris aquilina) to the urinary bladder of mice was studied. Powdered bracken fern mixed with a basic commercial diet (1:4 by weight) was fed to a group of 40 ICR strain mice for 20 weeks after the implantation of a glass bead into the bladder. A total experimental period was 70 weeks. Fifteen mice survived 40 or more weeks and 4 mice (27%) developed urinary bladder tumors. No urinary bladder tumor was found in the group of mice fed a similar bracken fern diet mixture without a glass bead in their bladder and in the control group of mice fed a normal diet after the implantation of a glass bead. The result of this experiment may indicate that there is a metabolite(s) in the urine of bracken-fed mice carcinogenic to the bladder.

Animals↗

PubMed2002

[Usefulness of the saliva ferning test in diagnosis of Sjögren's syndrome].

One of the characteristics of mucous is its ability to crystallize to the form of ferns when it is dried at room temperature and observed by polarized light microscopy (ferning phenomenon-FP). Several studies have shown that dry mouth can be diagnosed on the basis the loss of FP in dried saliva samples. The aim of our study was to evaluate the value of saliva ferning test (SFT) in the diagnosis of Sjögren's syndrome (SS). Saliva was taken from 11 patients with primary SS, 32 patients with secondary SS as well as from 27 controls. Samples of freshly produced saliva were dropped on light-microscope slides and allowed to dry at room temperature. Crystallization was observed by polarizing light microscopy within 10 minutes after collection. The type of crystallization was classified acc. to Rolando et al. Abnormal SFT was observed in 11 (100%) patients with primary SS and 27 (84%) patients with secondary SS. Saliva from 5 (16%) patients with secondary SS and from 27 (100%) control patients yielded normal picture of crystallization. In our opinion SFT is a simple, reproducible, and useful non-invasive diagnostic test in SS.

Adult↗