Uptake of Radionuclides by Bryophytes in the Chornobyl Exclusion Zone

The “Chernobyl nuclear disaster” released huge amounts of radionuclides, which are still detectable in plants and sediments today. Bryophytes (mosses) are primitive land plants lacking roots and protective cuticles and therefore readily accumulate multiple contaminants, including metals and radionuclides. This study quantifies 137Cs and 241Am in moss samples from the cooling pond of the power plant, the surrounding woodland and the city of Prypiat. Activity concentrations of up to 297 Bq/g (137Cs) and 0.43 Bq/g (241Am) were found. 137Cs contents were significantly higher at the cooling pond, where 241Am was not detectable. Distance to the damaged reactor, amount of original fallout, presence of vascular tissue in the stem or taxonomy were of little importance. Mosses seem to absorb radionuclides rather indiscriminately, if available. More than 30 years after the disaster, 137Cs was washed out from the very top layer of the soil, where it is no more accessible for rootless mosses but possibly for higher plants. On the other hand, 137Cs still remains solved and accessible in the cooling pond. However, 241Am remained adsorbed to the topsoil, thus accessible to terrestrial mosses, but precipitated in the sapropel of the cooling pond

Endocytosis and Digestion in Carnivorous Pitcher Plants of the Family Sarraceniaceae

Highly evolved carnivorous plants secrete digestive enzymes for degradation of trapped animals and absorb whole macromolecules from their prey by means of endocytosis. (1) Background: In the pitcher-plant family Sarraceniaceae, the production of enzymes is dubious and no evidence for endocytosis is known so far. (2) Methods: Heliamphora nutans, Darlingtonia californica, and nine taxa of Sarracenia are tested for cuticular pores, and for protease and endocytosis of the fluorescent protein analogue FITC-BSA, after 10–48 h of stimulation. (3) Results: Cuticular pores as a prerequisite for enzyme secretion and nutrient uptake are present in all tested species. Permeable cells form clusters in the inner epidermis of the pitchers, but are only little differentiated from impermeable epidermis cells. Proteases are found in S. psittacina, S. leucophylla, S. minor, S. oreophila, S. alabamensis, H. nutans, D. californica lacking only in S. flava and in S. purpurea ssp. purpurea, S. purpurea ssp. venosa, S. rosea, where enzyme production is possibly replaced by degradation via the extraordinary diverse inquiline fauna. S. leucophylla, S. minor, S. oreophila exhibit both protease production and endocytosis; S. psittacina, S. alabamensis, H. nutans, D. californica produce proteases only; no single species shows endocytosis without protease production. (4) Conclusions: Protease secretion seems to be a prerequisite for endocytotic nutrient uptake. Transport of FITC-BSA absorbed by endocytosis towards the vascular tissue of the trap leaves suggests that endocytosis of nutrients is more than a side effect of enzyme secretion

Snatching Sundews—Analysis of Tentacle Movement in Two Species of <i>Drosera</i> in Terms of Response Rate, Response Time, and Speed of Movement

Drosera, Droseraceae, catch prey with sticky tentacles. Both Australian Drosera allantostigma and widespread D. rotundifolia show three types of anatomically different tentacles: short, peripheral, and snap-tentacles. The latter two are capable of fast movement. This motion was analysed after mechanical, chemical, and electrical stimulation with respect to response rate, response time, and angular velocity of bending. Compared to D. rotundifolia, D. allantostigma responds more frequently and faster; the tentacles bend with higher angular velocity. Snap-tentacles have a lower response rate, shorter response time, and faster angular velocity. The response rates for chemical and electrical stimuli are similar, and higher than the rates for mechanical stimulus. The response time is not dependent on stimulus type. The higher motility in D. allantostigma indicates increased dependence on mechanical prey capture, and a reduced role of adhesive mucilage. The same tentacle types are present in both species and show similar motility patterns. The lower response rate of snap-tentacles might be a safety measure against accidental triggering, since the motion of snap-tentacles is irreversible and tissue destructive. Furthermore, tentacles seem to discern stimuli and respond specifically. The established model of stereotypical tentacle movement may not fully explain these observations

The Arsenic&ndash;Antimony Creek at Sauerbrunn/Burgenland, Austria: A Toxic Habitat for Amphibians

(1) Background: All Austrian amphibians are affected by the degradation of habitats. Mining contributes to habitat destruction by the formation of spoil heaps and mine drainage waters. In Stadtschlaining/Burgenland, antimony mining led to increased arsenic (As) and antimony (Sb) concentrations in soil and water. This study investigates a contaminated creek, still inhabited by amphibians. (2) Methods: Water and soil were analyzed along the creek and correlated with the occurrence of amphibians. (3) Results: As and Sb were increased, with up to 49,000 mg/kg As and 2446 mg/kg Sb in the soil. Up to 317 mg/kg As and 156 mg/kg Sb became bioavailable under gastric, and up to 298 mg/kg As and 30 mg/kg Sb under intestinal conditions, and were absorbed upon ingestion of soil. Larvae of Salamandra salamandra were found throughout the creek; survival rates were low. Rana temporaria occurs in the most contaminated sections but does not propagate here. Bombina variegata appears occasionally. Amphibians seem not to be able to detect and avoid metal or metalloid contamination. (4) Conclusion: Survival of larvae is dubious, but adult amphibians survive without apparent damage under severe metalloid contamination

Quantification of Protein Uptake by Endocytosis in Carnivorous Nepenthales

Carnivorous plants adsorb prey-derived nutrients partly by endocytosis. This study quantifies endocytosis in Drosophyllum lusitanicum, Drosera capensis, Drosera roseana, Dionaea muscipula and Nepenthes × ventrata. Traps were exposed to 1% fluorescent-labeled albumin (FITC-BSA), and uptake was quantified repeatedly for 64 h. Formation of vesicles started after ≤1 h in adhesive traps, but only after 16 h in species with temporary stomach (D. muscipula and N. × ventrata). In general, there are similarities in the observed species, especially in the beginning stages of endocytosis. Nonetheless, further intracellular processing of endocytotic vesicles seems to be widely different between species. Endocytotic vesicle size increased significantly over time in all species except in D. capensis. Fluorescence intensity of the endocytotic vesicles increased in all species except D. muscipula. After 64 h, estimates for FITC-BSA absorption per gland ranged from 5.9 ± 6.3 ng in D. roseana to 47.8 ± 44.3 ng in N. × ventrata, demonstrating that endocytosis substantially contributes to the adsorption of prey-derived nutrients

Endocytosis and Digestion in Carnivorous Pitcher Plants of the Family Sarraceniaceae

Highly evolved carnivorous plants secrete digestive enzymes for degradation of trapped animals and absorb whole macromolecules from their prey by means of endocytosis. (1) Background: In the pitcher-plant family Sarraceniaceae, the production of enzymes is dubious and no evidence for endocytosis is known so far. (2) Methods: Heliamphora nutans, Darlingtonia californica, and nine taxa of Sarracenia are tested for cuticular pores, and for protease and endocytosis of the fluorescent protein analogue FITC-BSA, after 10–48 h of stimulation. (3) Results: Cuticular pores as a prerequisite for enzyme secretion and nutrient uptake are present in all tested species. Permeable cells form clusters in the inner epidermis of the pitchers, but are only little differentiated from impermeable epidermis cells. Proteases are found in S. psittacina, S. leucophylla, S. minor, S. oreophila, S. alabamensis, H. nutans, D. californica lacking only in S. flava and in S. purpurea ssp. purpurea, S. purpurea ssp. venosa, S. rosea, where enzyme production is possibly replaced by degradation via the extraordinary diverse inquiline fauna. S. leucophylla, S. minor, S. oreophila exhibit both protease production and endocytosis; S. psittacina, S. alabamensis, H. nutans, D. californica produce proteases only; no single species shows endocytosis without protease production. (4) Conclusions: Protease secretion seems to be a prerequisite for endocytotic nutrient uptake. Transport of FITC-BSA absorbed by endocytosis towards the vascular tissue of the trap leaves suggests that endocytosis of nutrients is more than a side effect of enzyme secretion.© 2019 by the author