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At least 19 recordsLinked to original sources
PubMedDate not supplied

Ocular Ferning test - effect of temperature and humidity on tear Ferning patterns.

BACKGROUND: The ocular ferning test is used as a diagnostic aid to evaluate patients with dry-eye disease. The ferning phenomenon is a dendritic growth form of dried tear fluid. The influence of temperature and relative humidity (rH) on the morphology of tear ferning patterns was investigated. METHODS: Two microliters of tear fluid of 5 volunteers with normal tear function were dropped onto a microscope slide with a pipette and were dried in a climatic chamber at four different temperatures (20, 22, 24 and 26 degrees C) and at four different grades of rH (30, 40, 50 and 60%) at each temperature. The dried droplet was divided according to distinct morphological features into a center, transition zone and margin. The center of the dried droplet was classified into four types according to the system of Rolando. RESULTS: In the temperature range between 20 and 26 degrees C, rH has a strong influence on the ferning patterns. At these temperatures, increasing rH resulted in a deterioration of type I ferning obtained at 30% rH to type II or type III at 60% rH in all subjects. Otherwise, at rH of 30, 40 and 50%, no definite influence of temperature between 20 and 26 degrees C was observed. At an rH of 60%, the ferning patterns changed with increasing temperature from 20 to 26 degrees C from type II to type III. CONCLUSION: High humidity can modify and deteriorate the ferning patterns of tear fluid from subjects with normal tear function. To obtain reproducible results using the ocular ferning test, stable conditions are necessary. An rH not higher than 50% at a temperature range between 20 and 26 degrees C produced ferning patterns without interstitial spaces which could be related to the best quality according to the system of Rolando.

Adult↗
PubMed1989

Ferns and their allergenic importance: skin and nasal provocation tests to fern spore extract in allergic and non-allergic patients.

In our recent survey, fern spores were found to be the third most common airborne air spora in the Bangkok atmosphere; therefore, the significance of fern spores as a causative allergen was assessed in patients with allergic rhinitis. By using the extract from the spores of Acrostichum aureum Linn, which is a widespread fern, an intracutaneous test was done in 226 allergic rhinitis patients and 61.5% of these patients reacted positively. Nasal provocation test by using the same kind of fern spore extract was also performed in 24 allergic rhinitis patients and the positive reaction occurred in 70.8%. When skin tests and nasal provocation tests were performed in a group of 20 nonallergic ENT patients, only 20% gave weakly positive skin test reactions and 15% gave mild reactions to the nasal provocation test. The authors concluded that fern spores are potentially allergenic and allergists should be aware that ferns could be an important aeroallergen.

Humans↗
PubMed1999

Sem studies on vessels in ferns. 12. Marattiaceae, with comments on vessel patterns in eusporangiate ferns.

Scanning electron microscopy (SEM) of tracheary elements of roots of five species from four genera of Marattiaceae and of the rhizome of one species revealed vessel elements present in all. The secondary wall framework of perforation plates is the same as that of lateral wall pitting for vessel elements in all species. Thus, no specialization is present in perforation plates of Marattiaceae compared to the simplified morphology of perforation plates of some leptosporangiate ferns (e.g., Dryopteridaceae, Polypodiaceae, and Pteridaceae). The difference between lateral wall pitting and perforation plates in tracheary elements of Marattiaceae cannot be seen by light microscopy (in which pit membranes are transparent), but is evident with SEM. Diversity in structure of perforation plates (especially the alternation of wide and narrow perforations within a plate) and presence of web-like pit membrane remnants are evident. Vessels are widespread in both leptosporangiate and eusporangiate ferns, although specialization in perforation plates (e.g., bars few and more widely spaced in lateral wall pitting of a given vessel element) is to be expected only in ferns of habitats with marked fluctuation in water availability. Vessels of Marattiaceae lack such specializations and are thus are correlated with the mesic habitats characteristic for the family.

Journal Article↗
PubMed1986

Biochemistry of fern spore germination: protease activity in ostrich fern spores.

Protease activities were detected in quiescent and germinating spores of the ostrich fern (Matteuccia struthiopteris [L.] Todaro). Peak endopeptidase, aminopeptidase, and carboxypeptidase activities were detected 12 to 24 hours after spores began imbibing under light. There was a correlation between activities of proteases, the onset of a decline in levels of soluble protein, and an increase in levels of free amino acids. The earliest visible event of spore germination, breakage of the spore coat and protrusion of a rhizoid cell, was observed after peak protease activity, 48 to 72 hours after the start of imbibition. Results of this study demonstrate similarities in the pattern of protease activities during germination of ostrich fern spores to those of some seeds.

Journal Article↗
PubMed1998

Trans-splicing group II introns in plant mitochondria: the complete set of cis-arranged homologs in ferns, fern allies, and a hornwort.

The fragmentation of group II introns without concomitant loss of splicing competence is illustrated by extraordinary gene arrangements in plant mitochondrial genomes. The mitochondrial genes nad1, nad2, and nad5, all encoding subunits of the NADH dehydrogenase, require trans-splicing for functional assembly of their mRNAs in flowering plants. Tracing the origins of trans-splicing group II introns shows that they have evolved from formerly cis-arranged homologs whose descendants can still be identified in lineages of early branching land plants. In this contribution we present the full set of ancestor introns for all five conserved mitochondrial trans-splicing positions. These introns are strikingly small in the quillwort Isoetes lacustris, the continuous nad2 gene intron in this species representing the smallest (389 nt) land plant group II intron yet identified. cDNA analysis shows correct splicing of the introns in vivo and also identifies frequent RNA editing events in the flanking nad gene exons. Other representatives of the ancestral cis-arranged introns are identified in the fern Osmunda regalis, the horsetail Equisetum telmateia, and the hornwort Anthoceros crispulus. Only the now identified intron in Osmunda carries significant traces of a former maturase reading frame. The identification of a continuous homolog in Anthoceros demonstrates that intron invasion into the affected genes in some cases predated the split of vascular and nonvascular plants more than 400 million years ago. As an alternative to disruption after size increase, the respective introns can get secondarily lost in certain lineages.

Base Sequence↗
PubMedDate not supplied

Hay-scented fern (Dennstaedtia punctilobula (Michx.) Moore) interference with growth of northern red oak (Quercus rubra L.) seedlings.

We assessed the impacts of hay-scented fern (Dennstaedtia punctilobula (Michx.) Moore) and subsoil liming (CaO amendments) on root and shoot growth of greenhouse-grown, first-year, northern red oak (Quercus rubra L.) seedlings. Red oak seedlings and ferns were grown in reconstructed soil profiles of four common Pennsylvanian forest soils. When grown in the presence of hay-scented ferns, with or without subsoil liming, red oak seedlings had significantly reduced height growth, and foliar, stem and total root biomass. Fern foliar biomass was significantly reduced when ferns were grown with red oaks, but there was no significant difference in total belowground biomass of ferns. Belowground fern biomass was concentrated in the upper soil profile, whereas red oak roots showed a variety of distributions. In the presence of ferns, fine root branching in red oak was reduced in the organic horizons of three of the four soils tested. In both the presence and absence of ferns, root branching in red oak was also significantly and negatively correlated with the concentration of 0.01 M SrCl(2)-extractable aluminum in the mineral horizons (r(2) = 0.77). Subsoil liming generally improved root branching in red oaks. The presence of ferns significantly reduced ectomycorrhizal infection frequency in red oak. We conclude that hay-scented fern inhibited root branching and suppressed above- and belowground biomass accumulation of first-year northern red oak seedlings.

Journal Article↗
PubMed2025

Harnessing fern stress adaptations: From evolution and ecophysiology to molecular biology.

Ferns are the second most diverse vascular plant lineage after angiosperms and have been a key ecological component of Earth's biodiversity for more than 380 million years. Importantly, ferns are sister to seed plants, providing a critical outgroup for understanding the evolution of seed plant features. Ferns are remarkably resilient to abiotic and biotic stresses due to a long evolutionary history with adaptations to diverse habitats, stresses, and herbivores. As a result, ferns produce a multitude of secondary metabolites with unique bioactivities; these chemicals are potentially linked to the adaptation of ferns to herbivory, various abiotic and biotic stresses, and changing environments. Assembled reference genomes and the identification of key metabolic compounds of multiple ferns have already made significant contributions to human health and well-being. Here, we review the recent scientific advances in fern research, including evolution, stress resistance, metabolites and medicinal utilization, and comparative multi-omics applications. We propose that integrated investigations involving ecological, physiological, and molecular techniques will facilitate the future research translation of fern resources in diverse areas including soil remediation, biopesticides, and medicine. Advances in our understanding of fern molecular biology will provide new insights into the evolution of land plants and promote the utilization of ferns for heightened environmental restoration, crop protection and human health.

Ferns↗
PubMed1999

Validity of the saliva ferning test for the diagnosis of dry mouth in Sjögren's syndrome.

OBJECTIVE: To study the validity of saliva ferning patterns as a diagnostic test for dry mouth in primary or secondary Sjogren's Syndrome (SS). METHODS: Salivary smears were collected from 25 patients with Sjögren's syndrome in the fasting and nonfasting state. All 25 patients had symptomatic xerostomia and xerophthalmia and a positive Shirmer's test. Smears were taken from four sites, the cheek, lower lip, tongue, and saliva. Tests were done for rheumatoid factor, antinuclear antibodies, and anti-Ro(SS-A) antibodies. The salivary smears were air-dried and examined under a light and a polarizing microscope. Smears from 25 healthy subjects were also examined as controls. RESULTS: Three patterns of salivary secretion were identified, namely normal geometric ferning, reindeer antler ferning, and thick branching ferning. All Sjögren's syndrome patients had abnormal salivary smears, usually with a combination of reindeer antler ferning, thick branching ferning, and mucosal squames. This combination was seen in six of the 25 fasting specimens (24%); most of the remaining fasting samples showed the reindeer antler ferning. Reindeer antler ferning alone was found in five fasting and four nonfasting samples: this pattern was absent from five fasting and five nonfasting samples in which mucosal squames were the only abnormal finding. All nonfasting control samples exhibited normal geometric ferning. Smears from the cheek and saliva provided the most illustrative findings. CONCLUSION: The saliva ferning test is a simple, reproducible, and useful diagnostic aid in autoimmune xerostomia, approximately equivalent to Shirmer's test in xerophthalmia.

Adult↗
PubMed2004

Ferns diversified in the shadow of angiosperms.

The rise of angiosperms during the Cretaceous period is often portrayed as coincident with a dramatic drop in the diversity and abundance of many seed-free vascular plant lineages, including ferns. This has led to the widespread belief that ferns, once a principal component of terrestrial ecosystems, succumbed to the ecological predominance of angiosperms and are mostly evolutionary holdovers from the late Palaeozoic/early Mesozoic era. The first appearance of many modern fern genera in the early Tertiary fossil record implies another evolutionary scenario; that is, that the majority of living ferns resulted from a more recent diversification. But a full understanding of trends in fern diversification and evolution using only palaeobotanical evidence is hindered by the poor taxonomic resolution of the fern fossil record in the Cretaceous. Here we report divergence time estimates for ferns and angiosperms based on molecular data, with constraints from a reassessment of the fossil record. We show that polypod ferns (> 80% of living fern species) diversified in the Cretaceous, after angiosperms, suggesting perhaps an ecological opportunistic response to the diversification of angiosperms, as angiosperms came to dominate terrestrial ecosystems.

Biodiversity↗
PubMed2001

Vessels in ferns: structural, ecological, and evolutionary significance.

We have studied macerated xylem of ferns, supplemented by sections, by means of scanning electron microscopy (SEM) in a series of 20 papers, the results of which are summarized and interpreted here. Studies were based mostly on macerations, but also on some sections; these methods should be supplemented by other methods to confirm or modify the findings presented. Guidelines are cited for our interpretations of features of pit membranes. Fern xylem offers many distinctive features: (1) presence of numerous vessels and various numbers of tracheids in most species; (2) presence of vessels in both roots and rhizomes in virtually all species; (3) presence of specialized end walls in vessels of only a few species; (4) multiple end-wall perforation plates in numerous species; (5) lateral-wall perforation plates in numerous species; (6) porose pit membranes associated with perforation plates in all species; and (7) pit dimorphism, yielding wide membrane-free perforations alternating with extremely narrow pits. Multiple end wall perforation plates and lateral wall perforation plates are associated with the packing of tracheary elements in fascicles in ferns: facets of tips of elements contact numerous facets of adjacent elements; all such contacts are potential sites for conduction by means of perforations. This packing differs from that in primary xylem of dicotyledons and monocotyledons. Porosities in pit membranes represent a way of interconnecting vessel elements within a rhizome or root. In addition, these porosities can interconnect rhizome vessel elements with those of roots, a feature of importance because roots are adventitious in ferns as opposed to those of vascular plants with taproots. Fully-formed or incipient (small-to-medium sized porosities in pit membranes) perforation plates are widespread in ferns. These are believed to represent (1) ease of lysis of pit membranes via pectinase and cellulase; (2) numerous potential sites for perforation plate formation because of fasciculate packing of tracheary elements; (3) evolution of ferns over a long period of time, so that lysis pathways have had time to form; (4) lack of disadvantage in perforation plate presence, regardless of whether habitat moisture fluctuates markedly or little, because ferns likely have maintaining integrity of water columns that override the embolism-confining advantage of tracheids. Although all ferns share some common features, the diversity in xylem anatomy discovered thus far in ferns suggests that much remains to be learned.

Journal Article↗
PubMed2004

Functional characterization of the evolutionarily divergent fern plastocyanin.

Plastocyanin (Pc) is a soluble copper protein that transfers electrons from cytochrome b(6)f to photosystem I (PSI), two protein complexes that are localized in the thylakoid membranes in chloroplasts. The surface electrostatic potential distribution of Pc plays a key role in complex formation with the membrane-bound partners. It is practically identical for Pcs from plants and green algae, but is quite different for Pc from ferns. Here we report on a laser flash kinetic analysis of PSI reduction by Pc from various eukaryotic and prokaryotic organisms. The reaction of fern Pc with fern PSI fits a two-step kinetic model, consisting of complex formation and electron transfer, whereas other plant systems exhibit a mechanism that requires an additional intracomplex rearrangement step. The fern Pc interacts inefficiently with spinach PSI, showing no detectable complex formation. This can be explained by assuming that the unusual surface charge distribution of fern Pc impairs the interaction. Fern PSI behaves in a similar way as spinach PSI in reaction with other Pcs. The reactivity of fern Pc towards several soluble c-type cytochromes, including cytochrome f, has been analysed by flavin-photosensitized laser flash photolysis, demonstrating that the specific surface motifs for the interaction with cytochrome f are conserved in fern Pc.

Amino Acid Sequence↗