Biosensing the Presence of Metal Nanoparticles by Spectrally- and Time-Resolved Endogenous Fluorescence in Water Moss Fontinalis antipyretica

Pollution by heavy metals represents a significant environmental burden. We employed confocal microscopy with spectral detection and fluorescence lifetime imaging (FLIM) to evaluate the effect of nanoparticles (NPs) from various metals (Zinc, Nickel, Cobalt, Copper) on endogenous fluorescence of Fontinalis antipyretica moss. Short term (3–5 day) exposure to NPs, designed and fabricated by direct synthesis using femtosecond laser ablation in water, was studied. The green flavonoid and/or lignin endogenous fluorescence peaking between 500 and 560 nm was found to be increased by Zn and significantly reduced by Cu. The overall red chlorophyll fluorescence intensity with a maximum of 680 nm remained largely unchanged after exposure to Ni and Zn, but was decreased in the presence of Co and completely abolished by Cu. All NPs but Zn induced changes in the fluorescence lifetimes, demonstrating increased sensitivity of this parameter to environmental pollution. Gathered data indicate fast responsiveness of the endogenous fluorescence in the Fontinalis antipyretica moss to the presence of heavy metals that can thus potentially serve as a biosensing tool for monitoring environmental pollution in the moss natural environment.

Effect of Current Velocity on Cd Accumulation in the Aquatic Moss Fontinalis antipyretica

With the aim of further standardizing biomonitoring techniques with aquatic mosses, the relationship between the velocity of water flow and cadmium (Cd) accumulation in transplants of the moss Fontinalis antipyretica was investigated. For this purpose, moss transplants were exposed in a controlled aquatic environment to different concentrations of Cd (0, 4, 16 and 36 ng g−1) and different water velocities (10, 30, 50, 70 and 90 cm s−1). The Cd concentrations in the moss transplants mainly depended on the Cd concentration in the water, but a small fraction of the variance was explained by water velocity. The Cd concentrations in moss were standardized to remove the effect of the concentration in the water so all the data could be analyzed together. The regression model for the standardized concentrations explained 23% of the variance in Cd accumulation in F. antipyretica and water velocity proved to be a significant predictor of Cd accumulation.

Can Biomarkers Respond Upon Freshwater Pollution?—A Moss-Bag Approach

Moss-bags were applied to study the effect of contamination in three standing water bodies in Bulgaria (Kardzhali, Studen Kladenets and Zhrebchevo Reservoirs), the first two with old industrial contamination and the last polluted with short-chain chlorinated paraffins (SCCPs). Fontinalis antipyretica Hedw. collected from background (unpolluted) site was placed in cages for a period of 30 days. The present study examined whether inorganic and organic pollution detected with moss-bags resulted in corresponding differences in molecular, chemical and micromorphological markers. Suppressed large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL) expression was assessed in moss-bags from two of the reservoirs, contaminated with heavy metals. There was a decrease of the total phenolic content (TPC) in the moss-bags, which provides a basis for further studies of the chemical content of aquatic mosses. Fontinalis antipyretica also showed a response through leaf micromorphological characteristics. In the all three reservoirs, an increase of the twig leaf cell number was recorded (p ≤ 0.01 for Kardzhali and p ≤ 0.001 for Studen Kladenets and Zhrebchevo reservoirs), as well as of the stem leaf cell number in Zhrebchevo Reservoir (p ≤ 0.001). On the contrary, the width of the cells decreased in the studied anthropogenically impacted reservoirs. All three studied groups of biomarkers (molecular, chemical and micromorphological) appeared to be sensitive to freshwater pollution. The results achieved indicated that rbcL gene expression, TPC, cell number and size are promising biomonitoring tools.

Draft genome of the aquatic moss Fontinalis antipyretica (Fontinalaceae, Bryophyta)

Mosses comprise one of three lineages forming a sister group to extant vascular plants. Having emerged from an early split in the diversification of embryophytes, mosses may offer complementary insights into the evolution of traits following the transition to, and colonization of, land. Here, we report the draft nuclear genome of Fontinalis antipyretica (Fontinalaceae, Hypnales), a charismatic aquatic moss that is widespread in temperate regions of the Northern Hemisphere. We sequenced and de novo-assembled its genome using the 10X Genomics method. The genome comprises 385.2 Mbp, with a scaffold N50 of 45.8 Kbp. The assembly captured 87.2% of the 430 genes in the BUSCO Viridiplantae odb10 dataset. The newly generated F. antipyretica genome is the third moss genome, and the second seedless aquatic plant genome, to be sequenced and assembled to date.

Optimization of the Biomonitoring Technique with the Aquatic Moss Fontinalis antipyretica Hedw.: Selection of Shoot Segment Length for Determining Trace Element Concentrations

Bryophytes, including Fontinalis antipyretica Hedw., are widely used for biomonitoring aquatic environments. However, some methodological aspects, such as the fraction of shoot analysed, have not yet been standardized. The main objective of this study was to establish the length of segments of F. antipyretica shoots that should be used for trace element determination in monitoring studies. For this purpose, we determined the concentrations of 12 different trace elements (11 metals and one metalloid) in five successive 1 cm-long segments of the shoots of F. antipyretica collected from four different locations. We found that the concentrations of most elements increased steadily towards the basal part of the shoots without becoming stable. Sometimes, these increasing trends were concealed by another underlying trend of increasing dry/fresh weight ratios, caused by morphological changes (leaf density, shoot thickness) related with shoot development. The concentration trends were due to factors such as the deposition of Mn oxides on the moss surface. This element showed the largest increases in concentration towards the basal part of the shoot and its concentrations were closely correlated with those of most of the other elements. Considering the results obtained, we recommend the use of 3 cm-long apical segments for determining trace element concentrations in F. antipyretica. This recommendation is based on the following: (1) The change in dry weight beyond this length of segment is small; (2) the workload and the quantity of material to collect in the river is acceptable; (3) Most previous studies have used shoot segments of similar lengths.

Integrated Monitoring with Moss-Bag and Mussel Transplants in Reservoirs

For the first time, transplants with moss-bags and mussels together were applied to study the water quality in standing water bodies. The tested species: Fontinalis antipyretica Hedw. and Sinanodonta woodiana (Lea, 1834) were collected from unpolluted sites and analyzed to obtain background levels. Then, the moss and mussels were left in cages for a period of 30 days in three reservoirs where both are not present naturally. Two of the reservoirs suffer from old industrial contamination and one is affected by untreated wastes. Twenty-four compounds were studied, among them trace elements Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn and organic priority substances: six polybrominated diphenyl ethers (PBDEs) congeners and short-chain chlorinated paraffins (SCCPs). The trace element accumulation was significant after the exposition period in all studied stations. PBDEs and SCCPs were also accumulated up to two times more in the moss tissues. PBDEs in the mussels exceeded the environmental quality standard (EQS). The applied combined transplants, and especially the moss-bags, revealed severe contamination with heavy metals not detected by the water samples. The moss and the mussel followed a different model of trace element and PBDEs accumulation. The SCCPs levels were alarmingly high in all plant samples. The study confirmed PBDEs and SCCPs as bioaccumulative compounds and suggested that an EQS for SCCPs in biota needs to be established.