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PubMed2000

Fern spore extracts can damage DNA.

The carcinogenicity of the vegetative tissues of bracken fern (Pteridium) has long been established. More recently, the carcinogenic effects of the spores of bracken have also been recognized. Both vegetative tissues and spores of bracken can induce adducts in DNA in animal tissues, but the possible genotoxic or carcinogenic effects of spores from fern species other than bracken are unknown. The single-cell gel electrophoresis ('comet') assay was used to investigate whether fern spores can cause DNA damage in vitro. Extracts of spores from six fern species were administered to cultured human premyeloid leukaemia (K562) cells. Spore extracts of five fern species: Anemia phyllitidis, Dicksonia antarctica, Pteridium aquilinum, Pteris vittata and Sadleria pallida, induced significantly more DNA strand breaks than those in the control groups. Only in one species, Osmunda regalis, was the effect no different from that in the control groups. Using extracts from A. phyllitidis and P. vittata, the extent of DNA damage was increased by increasing the original dose 10 times, whereas an experiment in which exposure times were varied suggested that the highest levels of strand breaks appear after 2 h exposure. Simultaneous incubation with human S9 liver enzyme mix ablated the damaging effect of the extracts. Our data show that fern spore extracts can cause DNA damage in human cells in vitro. Considering the strong correlation between DNA damage and carcinogenic events, the observations made in this report may well have some implications for human health.

Comet Assay↗

PubMed1986

Genetic evidence suggests that homosporous ferns with high chromosome numbers are diploid.

Homosporous ferns have usually been considered highly polyploid because they have high chromosome numbers (average n = 57.05). In angiosperms, species with chromosome numbers higher than n = 14 generally have more isozymes than those with lower numbers, consistent with their polyploidy. By extrapolation, homosporous ferns would be expected to have many isozymes. However, ongoing surveys indicate that within fern genera, species having the lowest chromosome numbers have the number of isozymes considered typical of diploid seed plants. Only species above these lowest numbers have additional isozymes. Therefore, homosporous ferns either have gone through repeated cycles of polyploidy and gene silencing or were initiated with relatively high chromosome numbers. The latter possibility represents a radical departure from currently advocated hypotheses of fern evolution and suggests that there may be fundamental differences between the genomes of homosporous ferns and those of higher plants. These hypotheses can be tested by genetic, karyological, and molecular techniques.

Journal Article↗

PubMed1998

Characterization of MADS homeotic genes in the fern Ceratopteris richardii.

The MADS genes encode a family of transcription factors, some of which control the identities of floral organs in flowering plants. To understand the role of MADS genes in the evolution of floral organs, five MADS genes (CMADS1, 2, 3, 4, and 6) were cloned from the fern Ceratopteris richardii, a nonflowering plant. A gene tree of partial amino acid sequences of seed plant and fern MADS genes showed that the fern genes form three subfamilies. All members of one of the fern MADS subfamilies have additional amino-terminal amino acids, which is a synapomorphic character of the AGAMOUS subfamily of the flowering plant MADS genes. Their structural similarity indicates a sister relationship between the two subfamilies. The temporal and spatial patterns of expression of the five fern MADS genes were assessed by Northern blot analyses and in situ hybridizations. CMADS1, 2, 3, and 4 are expressed similarly in the meristematic regions and primordia of sporophyte shoots and roots, as well as in reproductive structures, including sporophylls and sporangial initials, although the amount of expression in each tissue is different in each gene. CMADS6 is expressed in gametophytic tissues but not in sporophytic tissues. The lack of organ-specific expression of MADS genes in the reproductive structures of the fern sporophyte may indicate that the restriction of MADS gene expression to specific reproductive organs and the specialization of MADS gene functions as homeotic selector genes in the flowering plant lineage were important in floral organ evolution.

Biological Evolution↗

PubMed1999

Phylogeny of Marsileaceous Ferns and Relationships of the Fossil Hydropteris pinnata Reconsidered.

Recent phylogenetic studies have provided compelling evidence that confirms the once disputed hypothesis of monophyly for heterosporous leptosporangiate ferns (Marsileaceae and Salviniaceae). Hypotheses for relationships among the three genera of Marsileaceae (Marsilea, Regnellidium, and Pilularia), however, have continued to be in conflict. The phylogeny of Marsileaceae is investigated here using information from morphology and rbcL sequence data. In addition, relationships among all heterosporous ferns, including the whole-plant fossil Hydropteris pinnata are reconsidered. Data sets of 71 morphological and 1239 rbcL characters for 23 leptosporangiate ferns, including eight heterosporous ingroup taxa and 15 homosporous outgroup taxa, were subjected to maximum parsimony analysis. Morphological analyses were carried out both with and without the fossil Hydropteris, and it was excluded from all analyses with rbcL data. An annotated list of the 71 morphological characters is provided in the appendix. For comparative purposes, the Rothwell and Stockey (1994) data set was also reanalyzed here. The best estimate of phylogenetic relationships for Marsileaceae in all analyses is that Pilularia and Regnellidium are sister taxa and Marsilea is sister to that clade. Morphological synapomorphies for various nodes are discussed. Analyses that included Hydropteris resulted in two most-parsimonious trees that differ only in the placement of the fossil. One topology is identical to the relationship found by Rothwell and Stockey (1994), placing the fossil sister to the Azolla plus Salvinia clade. The alternative topology places Hydropteris as the most basal member of the heterosporous fern clade. Equivocal interpretations for character evolution in heterosporous ferns are discussed in the context of these two most-parsimonious trees. Because of the observed degree of character ambiguity, the phylogenetic placement of Hydropteris is best viewed as unresolved, and recognition of the suborder Hydropteridineae, as circumscribed by Rothwell and Stockey (1994), is regarded as premature. The two competing hypotheses of relationships for heterosporous ferns are also compared with the known temporal distribution of relevant taxa. Stratigraphic fit of the phylogenetic estimates is measured by using the Stratigraphic Consistency Index and by comparison with minimum divergence times.

Journal Article↗

PubMed1976

Identification of carcinogenic tannin isolated from Bracken fern (Pteridium aquilinum).

We attempted to isolate a carcinogenic substance from bracken fern (Pteridium aquilinum), a naturally occurring toxicant responsible for the production of chronic enzootic hematuria and urinary bladder cancer of cattle and carcinogenic for various target organs of several species. Hot methanol extracts of bracken fern were solubilized in water and extracted with chloroform followed by a mixture of n-butanol-butanone (1:1). That fraction was dried and triturated with ether-methanol (4:1), n-butanol, and finally absolute ethanol. The insoluble residue was dissolved in 10% aqueous methanol and passed through Dowex 1 OH-, Dowex 50 H+, or Dowex 1 OH- and then Dowex 50 H+ ion exchange resins. A condensed tannin, isolated from one ot the fractions, was identical to that isolated from bracken fern by the caffeine procedure used for the separation of tannins from other plant constituents. Three systems were used for bioassay; induction of bladder carcinoma by implantation of cholesterol pellets containing bracken fern fractions into the bladder lumens of mice; acute toxicity by ip injection of brachen fern fraction into mice; and growth inhibition of Escherichia coli. The following fractions induced significantly greater incidences of bladder carcinoma than did cholesterol pellets only: tannin, Dowex 50 H+, residue, n-butanol, and methanol. Tiliroside, a component of bracken fern fractions into the bladder lumens of mice; acute genic acid, and quercetin were not carcinogenic. Tannin was the most toxic (mean lethal dose: 0.16 mg/g) and carcinogenic. None of the carcinogenic fractions inhibited growth of E. coli.

Escherichia coli↗

PubMed1976

Naturally occurring and braken-fern-induced bovine urinary bladder tumors. Clinical and morphological characteristics.

Clinical and morphological characteristics of 139 naturally occurring and 20 braken-fern-induced urinary bladder tumors of cows were studied. Hematuria was prominent and occurred as early as 60 days after braken fern feeding began. Anemia and changes in leukocytes were late manifestations. Papillomas appeared as early as 1 year, whereas invasive carcinomas did not develop until 2.6 years after initiation of feeding. Twenty of 30 cows fed braken fern developed bladder tumors within 5.3 years. None of eight untreated control cows that lived 4 years or six that lived 10 years developed neoplasms. Naturally occurring and fern-induced bladder tumors were epithelial (35%) or mixed epithelial and stromal (55%). Papillomas occurred in 24% and carcinomas in 61% of naturally occurring cases, whereas there were papillomas (40%) and carcinomas (50%) in fern-fed cows. Naturally occurring tumors were metastatic to regional lymph nodes and lung. No metastases were detected in fern-fed cows.

Adenoma↗

PubMedDate not supplied

Subretinal fluid ferning test in rhegmatogenous retinal detachment.

PURPOSE: The ferning test involves a process of crystallization achieved simply by removing water and is feasible for all ocular fluids. The ferning test of subretinal fluid (SRF) from patients with rhegmatogenous retinal detachment (RRD) reveals three different patterns: type 1 showing thin crystals, type 2 with larger crystals and type 3 with small, curvilinear structures with no tree-like appearance. The present study was designed to determine whether the SRF ferning test is correlated with the clinical features and the surgical outcome of RRD. METHODS: A series of 65 consecutive patients with RRD at the first onset were considered. Particular attention was paid to duration, extension, and surgical outcome of RRD. SRF samples were collected during scleral buckling surgery. The fluid was dropped onto the slide of a light microscope, left to dry, and examined under the microscope. RESULTS: There was a significant difference between SRF ferning types 1 and 2 as regards, duration and extension (both p < 0.001). There was also a significant difference between SRF ferning types 2 and 3 as regards duration (p<0.001), extension (p<0.001), and surgical outcome (p<0.05). CONCLUSIONS: The ferning test of SRF is quick and simple and can be regarded as a useful tool for obtaining information about clinical features, such as duration or extension of first, onset in uncomplicated cases of RRD especially for purposes of forensic medicine.

Body Fluids↗

PubMed1978

Screening aquatic ecosystems for mutagens with fern bioassays.

Recent researches on the royal fern, Osmunda regalis, have documented a high incidence of post-zygotic mutational damage in a population growing in a river heavily polluted with paper processing wastes, whereas genetic studies of nearby populations in nonpolluted environments failed to detect mutational damage. Intensive genetic and cytogenetic studies of mutation in O. regalis indicates that natural populations of homosporous ferns may be useful in situ bioassay systems for monitoring the presence of mutagens in aquatic ecosystems. Since these organisms are long-lived perennials with an ontogenetic system which stores mutational damage, they can be manipulated to give an integrated estimate of mutational damage for specified blocks of time (in units of years). Thus, the fern bioassay may be an inexpensive means of detecting both chronic low dose and episodic high dose inputs of mutagenic pollutants into aquatic ecosystems. The fern mutagen bioassay is based upon the detection of numerous categories of post-zygotic mutation load in natural fern populations. The frequency of sporophytic and embryonic lethals, leaf or root mutations, auxotrophic gametophytic mutations as well as numerous phenotypic alterations of gametophyte morphology can be routinely detected and quantified. In addition, various two-break chromosome aberrations (paracentric inversions, reciprocal translocations and ring chromosomes) can be readily screened for in the spore mother cells of many homosporous ferns.

Biological Assay↗

PubMed2005

Mycorrhizae increase arsenic uptake by the hyperaccumulator Chinese brake fern (Pteris vittata L.).

Chinese brake fern (Pteris vittata L.) is a hyperaccumulator of arsenic (As) that grows naturally on soils in the southern United States. It is reasonable to expect that mycorrhizal symbiosis may be involved in As uptake by this fern. This is because arbuscular mycorrhizal (AM) fungi have a well-documented role in increasing plant phosphorus (P) uptake, P and As have similar chemical properties, and ferns are known to be colonized by AM fungi. We conducted a factorial greenhouse experiment with three levels of As (0, 50, and 100 mg kg(-1)) and P (0, 25, and 50 mg kg(-1)) and with and without Chinese brake fern colonized by a community of AM fungi from an As-contaminated site. We found that the AM fungi not only tolerated As amendment, but their presence increased frond dry mass at the highest As application rate. Furthermore, the AM fungi increased As uptake across a range of P levels, while P uptake was generally increased only when there was no As amendment. These data indicate that AM fungi have an important role in arsenic accumulation by Chinese brake fern. Therefore, to effectively phytoremediate As-contaminated soils, the mycorrhizal status of ferns needs to be taken into account.

Arsenic↗

PubMed2000

Evidence for natural selection in a fern hybrid zone.

Morphological characters, chloroplast DNA, and allozymes were used to analyze the distribution of individuals within a hybrid population of the ferns Polystichum munitum and P. imbricans in northwestern California. Microsites within the population were characterized according to soil moisture and light levels reaching the plants. In sites with low soil moisture and high light levels, all of the ferns were genetically and morphologically like P. imbricans. In contrast, ferns with the genetic and morphological identity of P. munitum predominated in moist shady sites. Intermediate sites supported very few P.munitum, a wide variety of hybrid recombinants, and a majority of ferns with P. imbricans characteristics. The pattern of variation within the population is noteworthy because of the close proximity of the habitat extremes and the long-range dispersal of fern spores. We conclude that natural selection along environmental gradients must be a major factor in determining the ecological and genetic associations within the hybrid zone. The results of this study are evaluated in the context of the fern life cycle and compared to the assumptions of models explaining the establishment and maintenance of hybrid zones, which vary in the role attributed to environmentally mediated natural selection.

Journal Article↗

PubMed1990

Ferning of amniotic fluid contaminated with blood.

The diagnosis of rupture of the membranes by traditional methods of nitrazine paper determination and fern crystallization has been reported to be 93-98% accurate. Although the presence of contaminants in amniotic fluid has been reported to reduce this accuracy, the literature is conflicting concerning these effects. We examined the effect of blood contamination on the accuracy of diagnosing ruptured membranes. Amniotic fluid was obtained from 38 patients between 16-38 weeks' gestational age who underwent amniocentesis. Amniotic fluid was immediately mixed with freshly obtained, heparinized fetal cord blood in varying concentrations (blood to amniotic fluid 1:5, 1:10, 1:20). The slides were examined microscopically for the presence of ferning. All samples were fern-positive, but many had atypical ferns described as "skeletonized." As the concentration of blood to amniotic fluid increased, the number of atypical ferns increased (32 of 38 at 1:5, 22 of 38 at 1:10, and nine of 38 at 1:20). We conclude that the presence of blood may alter the morphology of the fern, but does not act as a contaminant that would affect the accuracy of the test.

Amniotic Fluid↗

PubMed2003

The structure and development of haustorial placentas in leptosporangiate ferns provide a clear-cut distinction between euphyllophytes and lycophytes.

This light and electron microscope study revealed that leptosporangiate ferns have highly distinctive gametophyte-sporophyte junctions characterized by sporophytic haustoria, the absence of intraplacental spaces and degenerating cells, and the early appearance of wall ingrowths in both generations. Other notable cytological features are highly pleomorphic plastids and mitochondrial aggregates in the gametophytic placental cells. Close similarities with the gametophyte-sporophyte junctions in Tmesipteris and major differences from those of homosporous lycophytes are in line with the placement of psilophytes and ferns in the same clade and distance both from lycophytes. A smooth interface between the two generations in Azolla suggests a clear-cut discontinuity between homosporous and heterosporous ferns, although this is the only heterosporous fern investigated to date. Similarities between the gametophyte-sporophyte junctions of leptosporangiate ferns and hornworts, when balanced against differences between them, are considered more likely the result of parallel evolution rather than homology.

Cell Differentiation↗

PubMed1998

Characterization of rbcS genes in the fern Pteris vittata and their photoregulation.

The fern Pteris vittata L. belongs to the evolutionarily highest group of vascular plants that still maintains a free-living gametophytic stage. The two-dimensional gametophytes developed under blue light exhibit higher CO2 fixation efficiency and different ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit (SSU) composition when compared to the red-induced filamentous gametophytes (H. Eilenberg et al., 1991, Plant Physiol 95: 298-304). To unravel the correlation between SSU structural differences and light regulation, two rbcS genes and two additional partial cDNAs were characterized. Fern rbcS genes resemble those of higher plants in their promoter light-regulatory elements (LREs) and intron number and positions. However, the primary structure of the fern mature SSUs displays much higher divergency within the gene family. This structural variability was correlated with differential steady-state mRNA levels under red and blue light. Genes rbcS-1 and-4 and 4-to 6-fold higher transcript levels in red light while rbcS-2 and-3 contribute relatively more to the blue rbcS mRNA levels. Five of the 12 amino acids that differ between rbcS-2 and-4 affect hydrophobicity and might play a crucial role in determining the efficiency of CO2 fixation. Dendrograms of Rubisco SSUs and LSUs indicate early divergence of the fern types from the rest of the vascular plants. However, prominent higher-plant-like Rubisco features such as high carboxylation efficiency, promoter LREs and exon-intron structure, suggest that molecular specialization of the higher-plant Rubisco prototype occurred earlier than the emergence of ferns.

Amino Acid Sequence↗

PubMed2001

A new triterpenoid from the fern Adiantum lunulatum and evaluation of antibacterial activity.

A new triterpenoid, 22,29xi-epoxy-30-norhopane-13beta-ol (1) was isolated together with six known compounds viz., fern-9(11)-en-6alpha-ol. fern-9(11)-ene, fern-9(11)-en-25-oic acid, fern-9(11)-en-28-ol, filicenol-B, adiantone and oxidation product of fern-9(11)-en-6alpha-ol obtained as 6-oxofern-9(11)-ene from the whole plant of Adiantum lunulatum, and their structures were elucidated by means of spectroscopic analysis and antibacterial evaluation of these compounds were conducted.

Anti-Bacterial Agents↗

PubMed2001

An Early Cretaceous root-climbing epiphyte (Lindsaeaceae) and its significance for calibrating the diversification of polypodiaceous ferns.

The discovery of fossilised roots of a lindsaeoid fern within the trunk of the extinct tree fern Tempskya provides new fossil evidence for Lindsaeaceae in the Mesozic, as well as the first direct evidence of an ecological association between Tempskya and root-climbing epiphytes. Data were collected from permineralised Tempskya trunks from the Aspen Shale (Early Cretaceous, Albian), Wyoming (USA). The roots of the lindsaeoid fossil are clearly distinguishable from those of Tempskya and other living ferns based on a suite of distinctive anatomical features, which are described in detail. The foliage is unknown. The new fossil is interpreted as a root climber, and comparisons are made with similar living species in Lindsaea subgenus Odontoloma (Lindsaeaceae). The documentation of Lindsaeaceae in the Early Cretaceous adds to a small but growing body of data on the diversification of polypodiaceous ferns during this important period. These recent discoveries point to a much earlier (Early Cretaceous) crown group radiation of polypodiaceous ferns than previously suspected.

Journal Article↗

PubMed1982

Ocular ferning test. A qualitative test for mucus deficiency.

A new qualitative test for the study of conjunctival mucus has been developed. Conjunctival scrapings were obtained from 196 patients. Microscopic mucus ferning (arborization) was observed in 148 (91%) patients with various forms of acute conjunctivitis. Six patients (18%) with cicatrizing conjunctivitis (diffuse conjunctival cicatrization, ocular pemphigoid, Stevens-Johnson syndrome) had mucus ferning in their conjunctival scrapings specimens. Mucus ferning was significantly absent (P less than 0.005) in patients with diffuse conjunctival cicatrization when compared to mucus ferning in other forms of conjunctivitis. Ocular mucus ferning test is a simple inexpensive office test for the evaluation of patients with mucus deficiency.

Adolescent↗

PubMed1994

Value of the fern test to confirm or reject the diagnosis of ruptured membranes is modest in nonlaboring women presenting with nonspecific vaginal fluid loss.

The strength of the fern test to differentiate between amniotic and nonamniotic fluid in vaginal discharge was determined in 51 term women in labor with ruptured membranes and compared with that in a group of 120 nonlaboring subjects, presenting with nonspecific vaginal fluid loss. Sensitivity and specificity in the laboring group were 98.0 and 88.2%, respectively, in agreement with previous reports. In contrast, in the non-laboring group sensitivity and specificity were only 51.4 and 70.8%, respectively. The result of the fern test predicted the actual state of the membranes correctly in 63% and incorrectly in 29% of these patients. In 16 or 39 subjects with ruptured membranes (approximately 40%), the outcome of the fern test was negative. The modest diagnostic strength of the fern test in the present study compared with previously reported data is at least in part due to differences in study population (laboring versus nonlaboring) and to the fact that observers were deprived of relevant clinical information. It is concluded that the fern test should be granted supportive rather than conclusive value in diagnosing ruptured membranes in nonlaboring women presenting with nonspecific vaginal fluid loss.

Amniotic Fluid↗

PubMed1990

Defective chlorophyll a/b-binding protein genes in the genome of a homosporous fern.

The majority of homosporous ferns have a chromosome number that is severalfold greater than that of diploid seed plants. These fern species have therefore been generally considered to be of polyploid origin. Enzyme electrophoretic investigations have demonstrated, however, that within fern genera, species having the lowest chromosome numbers (n = 27-52) have the number of isozymes typical of diploid seed plants; there is no isozyme evidence for polyploidy of these plants. We have constructed a genomic DNA library from Polystichum munitum (n = 41), a homosporous fern, and have screened the library for sequences homologous to the chlorophyll a/b-binding (CAB) protein genes of higher plants. The majority of the sequences isolated and characterized by nucleotide sequence determination represent defective CAB genes. This result is in contrast to the situation in the genomes of diploid angiosperms, where most, and sometimes all, copies of the CAB gene family represent functional members. Several hypotheses could explain the existence of multiple defective CAB genes in P. munitum. (i) The defective CAB genes are the result of "gene silencing" following polyploidy. (ii) P. munitum has not gone through a polyploidization event, but several, and perhaps the majority, of its CAB genes have mutated to a nonfunctional state (a phenomenon not yet observed in any of the genomes of non-fern plants so far examined). (iii) Some defective CAB genes have been specifically amplified in the genome of P. munitum.

Amino Acid Sequence↗