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Saturated water solutions of calcium chloride, calcium bromide and their 1:1 mixture are commonly used as "high density brines" for pressure control in oil wells. To compare the effect of these chemicals of technical grade with the effect of the chemicals of analytical grade the Lemna test was used. The multiplication rate, fresh weight, dry to fresh weight ratio, area covered by plants and chlorophyll content were measured as toxicity parameters. The concentrations of tested chemicals were 0.025, 0.05. 0.075 and 0.1 mol dm(-3). Generally, the chemicals of both technical and analytical grade in concentrations of 0.025 mol dm(-3) stimulated the Lemna minor growth, while tested chemicals in concentrations of 0.05 mol dm(-3) did not affect the growth significantly. The exceptions were results obtained by measuring fresh weight. Most of tested chemicals in concentrations of 0.075 mol dm(-3) and all chemicals in concentrations of 0.1 mol dm(-3) reduced the growth. No major differences between effects of tested chemicals of technical and analytical grade on plant growth were observed, except that tested chemicals of analytical grade in concentrations of 0.1 mol dm(-3) increased dry to fresh weight ratio much stronger than chemicals of technical grade. All tested chemicals in all concentrations increased chlorophyll content. After treatment with chemicals of analytical grade much higher increase of chlorophyll a concentration in comparison to increase of chlorophyll b was noticed, while chemicals of technical grade caused more prominent increase of chlorophyll b.

Duckweed Lemna minor L. is a suitable plant model for toxicity evaluation of many substances due to its small size, rapid growth and ease of culture. Saturated water solutions of calcium chloride and calcium bromide and their 1:1 mixture are commonly used as high density brines for pressure control in oil wells. These solutions were added in Hoagland's nutrient medium in amount appropriate to achieve 0.5%, 1.0%, 1.5% and 2.0 (v/v) dilutions and after two weeks of exposure the effect of tested chemicals on growth was estimaded by counting fronds, measuring fresh and dry weights and determining total surface area of plants. Chlorophyll and carotenoid content in Lemna minor was also measured. Additionally, anthocyanin content in Spirodela polyrrhiza (L.) Schleiden was determined. During 14 days of exposure tested chemicals in lower concentrations (0.5%, 1.0% and 1.5% v/v) promoted the growth of Lemna minor, but they inhibited it in the highest (2.0% v/v). With increased concentration of tested solutions the concentrations of chlorophyll a and chlorophyll b were correspondingly higher in comparison with the control. Total carotenoid content and chl a/chl b ratio were also increased. The highest anthocyanin content in lower epidermis of Spirodela polyrrhiza was noticed after the treatment with media containing 2.0% (v/v) CaCl2 and 1:1 mixture of CaCl2 and CaBr2, but lower concentrations of all three tested solutions also resulted in anthocyanin content increase.

The objective of the present study was to investigate the effects of cadmium-zinc (Cd-Zn) interactions on their uptake, oxidative damage of cell macromolecules (lipids, proteins, DNA) and activities of antioxidative enzymes in tobacco seedlings as well as roots and leaves of adult plants. Seedlings and plants were exposed to Cd (10 µM and 15 µM) and Zn (25 µM and 50 µM) as well as their combinations (10 µM or 15 µM Cd with either 25 µM or 50 µM Zn). Measurement of metal accumulation exhibited that Zn had mostly positive effect on Cd uptake in roots and seedlings, while Cd had antagonistic effect on Zn uptake in leaves and roots. According to examined oxidative stress parameters, in seedlings and roots individual Cd treatments induced oxidative damage, which was less prominent in combined treatments, indicating that the presence of Zn alleviates oxidative stress. However, DNA damage found in seedlings, and lower glutathione reductase (GR) and superoxide dismutase (SOD) activity recorded in both seedlings and roots, after individual Zn treatments, indicate that Zn accumulation could impose toxic effects. In leaves, oxidative stress was found after exposure to Cd either alone or in combination with Zn, thus implying that in this tissue Zn did not have alleviating effects. In conclusion, results obtained in different tobacco tissues suggest tissue-dependent Cd-Zn interactions, which resulted in activation of different mechanisms involved in the protection against metal stress.

Environmental pollution may modify genetic diversity of exposed populations causing their genetic erosion through the processes of selection, adaptation and genetic drift, by influencing migrations, or even enhance the mutational load of the population through the high genotoxic pressure. In order to evaluate the pollution impact on the genetic diversity of native Mediterranean mussel Mytilus galloprovincialis ten populations inhabiting differently polluted sites along the eastern Adriatic coast, from pristine bays to highly trafficated harbours, were studied. Pollution pressure was assessed using analyses of metals bioaccumulation and different biomarkers of effect and exposure, including genotoxicity endpoints and oxidative stress measurements. Eight microsatellite markers were analysed to assess genetic diversity of investigated populations. Both the principal component analysis (PCA) of biomarker data set as well as the integrated biomarker response (IBR) revealed substantial pollution pressure at some polluted sites, and confirmed very low pollution exposure at the three investigated reference sites. Interestingly, populations inhabiting polluted sites exhibited high level of genetic diversity. However, very low genetic differentiation was found between populations inhabiting polluted and clean areas, and microsatellite data did not revealed any pollution driven genetic divergence of M. galloprovincialis populations.

Accumulating evidence suggests that exposure to radiofrequency electromagnetic field (RF-EMF) can have various biological effects. In this study the oxidative and genotoxic effects were investigated in earthworms Eisenia fetida exposed in vivo to RF-EMF at the mobile phone frequency (900 MHz). Earthworms were exposed to the homogeneous RF-EMF at field levels of 10, 23, 41 and 120 V m(-1) for a period of 2h using a Gigahertz Transversal Electromagnetic (GTEM) cell. At the field level of 23 V m(-1) the effect of longer exposure (4h) and field modulation (80% AM 1 kHz sinusoidal) was investigated as well. All exposure treatments induced significant genotoxic effect in earthworms coelomocytes detected by the Comet assay, demonstrating DNA damaging capacity of 900 MHz electromagnetic radiation. Field modulation additionally increased the genotoxic effect. Moreover, our results indicated the induction of antioxidant stress response in terms of enhanced catalase and glutathione reductase activity as a result of the RF-EMF exposure, and demonstrated the generation of lipid and protein oxidative damage. Antioxidant responses and the potential of RF-EMF to induce damage to lipids, proteins and DNA differed depending on the field level applied, modulation of the field and duration of E. fetida exposure to 900 MHz electromagnetic radiation. Nature of detected DNA lesions and oxidative stress as the mechanism of action for the induction of DNA damage are discussed.

The effects of 5 μM cadmium (Cd), a non-essential toxic element and 25 and 50 μM zinc (Zn), an essential micronutrient, were investigated in aquatic plant Lemna minor L. after 4 and 7 days of exposure to each metal alone or to their combinations. Both metals showed tendency to accumulate with time, but when present in combination, they reduced uptake of each other. Cd treatment increased the lipid peroxidation and protein oxidation indicating appearance of oxidative stress. However, Zn supplementation in either concentration reduced values of both parameters, while exposure to Zn alone resulted in elevated level of lipid peroxidation and protein oxidation but only on the 7th day. Enhanced DNA damage, which was found on the 4th day in plants treated with Cd alone or in combination with Zn, was reduced on the 7th day in combined treatments. Higher catalase activity obtained in all treated plants on the 4th day of experiment was reduced in Zn-treated plants, but remained high in plants exposed to Cd alone or in combination with Zn after 7 days. Cd exposure resulted in higher peroxidase activity, while Zn addition prominently reduced peroxidase activity in the plants subjected to Cd stress. In conclusion, Cd induced more pronounced oxidative stress and DNA damage than Zn in applied concentrations. Combined treatments showed lower values of oxidative stress parameters— lipid peroxidation, protein oxidation and peroxidase activity as well as lower DNA damage, which indicates alleviating effect of Zn on oxidative stress in Cd-treated plants.

In a previous study it was reported that transformed tissue of horseradish (Armoracia lapathifolia Gilib.), obtained by infection of leaf explants with A. tumefaciens, developed two tumour lines with different morphology. One line grew as a completely unorganized tissue (TN – tumour tissue), while the other line grew as a partially organized teratogenous tumour with malformed hyperhydric shoots (TM – teratoma tissue), but did not regenerate the whole plant of normal morphology. The factor responsible for this problem could be the increased production of reactive oxygen species (ROS). Therefore, in this study a possible involvement of activated oxygen metabolism in dedifferentiation and hyperhydricity in TM and TN tissues is investigated. Elevated values of malondialdehyde and protein carbonyl contents found in TM and TN, in comparison with plantlet leaf, confirm the presence of oxidative stress. However, lower H2O2 content was measured in TM and TN. Lipoxygenase (LOX) activity was more pronounced in TM and especially in TN compared to leaf, which suggests that the LOX-dependent peroxidation of fatty acids might be one of the causes of oxidative damage. Moreover, significantly higher peroxidase (PRX) and ascorbate peroxidase (APX) activity as well as the increased number of their isoforms was found in transformed TM and TN in comparison with leaf. On the other hand, significantly lower superoxide dismutase (SOD) activity was found in TM and TN, which correlates with lower H2O2 content. High catalase (CAT) activity measured in leaf and partially organized TM is consistent with the role of CAT in growth and differentiation. In conclusion, in horseradish transformed tissues that underwent dedifferentiation and hyperhydricity, prominent oxidative damage was found. This result suggests that oxidative stress could be associated with the inability of partially organized teratogenous TM to regenerate plantlets with normal morphology., Dosadašnja istraživanja autora pokazala su da je transformirano tkivo hrena (Armoracia lapathifolia Gilib.), nakon infekcije bakterijom A. tumefaciens, razvilo dvije morfološki različite linije tumorskog tkiva. Jedna je linija rasla kao potpuno neorganizirano tumorsko tkivo, a druga kao djelomično organizirani teratogeni tumor s malformiranim hiperhidriranim izdancima (teratomska linija), ali bez mogućnosti regeneriranja biljke normalnih morfoloških karakteristika. Budući da bi povećana proizvodnja reaktivnih oblika kisika mogla uzrokovati promjenu morfoloških karakteristika, u ovom je radu istraživan mogući utjecaj kisika na dediferencijaciju i hiperhidriranost u potpuno neorganiziranom tumorskom tkivu i teratomskoj liniji. Uspoređujući povećane vrijednosti malondialdehida i proteinskih karbonila u potpuno neorganiziranom tumorskom tkivu i teratomskoj liniji s onima u listu hrena, uočena je pojava oksidacijskog stresa iako je izmjeren manji udjel H2O2. Aktivnost lipoksigenaze povećana je u teratomskoj liniji, a još više u potpuno neorganiziranom tumorskom tkivu, što pokazuje da bi peroksidacija masnih kiselina ovisna o aktivnosti lipoksigenaze mogla biti jedan od uzroka oksidacijskoga stresa. Štoviše, u transformiranim je tkivima za razliku od lista uočena bitno veća aktivnost peroksidaze i askorbat peroksidaze te veći broj njihovih izoenzima. S druge strane, izmjerena je kudikamo manja aktivnost superoksid dismutaze, s obzirom na smanjeni udjel H2O2. Veća aktivnost katalaze u listu i teratomskoj liniji povezana je s ulogom katalaze u rastu i diferencijaciji. Dobiveni rezultati potvrđuju prisutnost oksidacijskog stresa u dediferenciranim i hiperhidriranim tumorskim tkivima hrena, odnosno da je oksidacijski stres posljedica nesposobnosti teratomske linije da regenerira biljke normalne morfologije.

Effect of Copper on the Toxicity and Genotoxicity of Cadmium in Duckweed (Lemna Minor L.)We investigated interactions between copper (in the concentrations of 2.5 μmol L-1 and 5 μmol L-1) and cadmium (5 μmol L-1) in common duckweed (Lemna minor L.) by exposing it to either metal or to their combinations for four or seven days. Their uptake increased with time, but it was lower in plants treated with combinations of metals than in plants treated with either metal given alone. In separate treatments, either metal increased malondialdehyde (MDA) level and catalase and peroxidase activity. Both induced DNA damage, but copper did it only after 7 days of treatment. On day 4, the combination of cadmium and 5 μmol L-1 copper additionally increased MDA as well as catalase and peroxidase activity. In contrast, on day 7, MDA dropped in plants treated with combinations of metals, and especially with 2.5 μmol L-1 copper plus cadmium. In these plants, catalase activity was higher than in copper treated plants. Peroxidase activity increased after treatment with cadmium and 2.5 μmol L-1 copper but decreased in plants treated with cadmium and 5 μmol L-1 copper. Compared to copper alone, combinations of metals enhanced DNA damage after 4 days of treatment but it dropped on day 7. In conclusion, either metal given alone was toxic/genotoxic and caused oxidative stress. On day 4 of combined treatment, the higher copper concentration was more toxic than either metal alone. In contrast, on day 7 of combined treatment, the lower copper concentration showed lower oxidative and DNA damage. These complex interactions can not be explained by simple antagonism and/or synergism. Further studies should go in that direction.

In vitro propagated plants of Mammillaria gracilis Pfeiff. (Cactaceae) develop calli without any exogenous growth regulators. This habituated tissue spontaneously regenerates morphologically normal as well as hyperhydric shoots. In this study, a possible involvement of activated oxygen metabolism in habituation and hyperhydricity in in vitro propagated plants of Mammillaria gracilis Pfeiff. (Cactaceae) was investigated. Significantly higher malondialdehyde (MDA) and carbonyl contents as well as hydrogen peroxide (H2O2) production were observed in habituated callus (HC), hyperhydric regenerated shoots (HS), and tumors (TT) in comparison to normal regenerated shoots (NS). Lipoxygenase (LOX) activity showed a similar trend, with a clear increase in activity in HC and HS. The activities of antioxidative enzymes, namely, peroxidase (POX), ascorbate peroxidase (APX), and catalase (CAT), were also higher in HC, HS, and TT, whereas an increase in superoxide dismutase (SOD) activity was observed in HC and HS. The majority of antioxidative isoenzymes were common to all cactus tissues, although a few tissue-specific bands were noticed. Significant decreases in phenylalanine ammonia lyase (PAL) activity, total phenolic content, and lignification were found in HS, HC, and TT in comparison to NS. Our results showed the appearance of a prominent oxidative stress in HC, HS, and TT as well as a strong induction of the antioxidant system indicating that activated oxygen metabolism could be involved in habituation and hyperhydricity and linked to the loss of tissue organization in M. gracilis.

Although duckweed Lemna minor L. is a known accumulator of cadmium, detailed studies on its physiological and/or defense responses to this metal are still lacking. In this study, the effects of 10 µ ; M CdCl2 on Lemna minor were monitored after 6 and 12 days of treatment, while growth was estimated every two days. Cadmium treatment resulted in progressive accumulation of the metal in the plants and led to a decrease in the growth rate to 54% of the control value. The metal also considerably impaired chloroplast ultrastructure and caused a significant reduction in pigment content, i.e., at day 12, by 30% and 34% for chlorophylls a and b, and by 25% for carotenoids. During cadmium treatment, the contents of malondialdehyde (MDA) and endogenous H2O2 progressively increased (rising 77% and 46% above the controls by day 12), indicating that cadmium induced considerable oxidative stress. On the other hand, higher activities of pyrogallol peroxidase (PPX), ascorbate peroxidase (APX) and catalase (CAT), as well as the induction of a new APX isoform, in cadmium-treated plants, clearly showed activation of an antioxidative response. At day 6, only PPX activity was significantly above the controls (15%), while, at day 12, PPX, APX and CAT activities were increased (74%, 78% and 63%). Cadmium also led to accumulation of the heat shock protein 70 (HSP70) and induced an additional isoform of this protein. The obtained results suggest that cadmium (10 μ M) is phytotoxic to Lemna minor, inducing oxidative stress, and that antioxidative enzymes and HSP70 play important roles in the defense against cadmium toxicity.

Allium cepa seeds were exposed to 900 MHz EMF in GTEM cell at four different field strengths (10, 23, 41 and 120 Vm -1) for 2 h. The effect of longer exposure time (4 h) and modulation was also investigated. Germination rate and root length did not change significantly after EMF exposure. However, EMF at higher strengths (41 and 120 V m -1) and with modulation as well as longer exposure significantly increased mitotic index compared to corresponding controls. Percentage of mitotic abnormalities, mainly consisting of laggards, anaphase bridges, C-mitosis, vagrants and unequal distribution, increased at all given field conditions.

There is accumulating evidence that exposure to radio frequency electromagnetic fields (RF-EMF) from mobile telephones or their base station could have detrimental biological effects. Therefore, the possible cyto- and genotoxic effects after 4 hour exposure of tobacco shoots to 900 MHz EMF were studied.The levels of lipid peroxidation and oxidation of proteins as well as damage to DNA increased in response to EMF comparing to control values. These results suggest that short-term exposure to 900 MHz EMF has genotoxic effect but harshly interrupts plasma biomembrane integrity as well. Plant model system proved to be sensitive biomarkers of RF-EMF exposure.

Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m(-1). The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H(2)O(2) content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H(2)O(2) content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m(-1) while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m(-1) and increased PPX activity after exposures at 10 and 120 V m(-1). By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H(2)O(2) content but mostly decreased PPX activity and did not affect CAT activity. Exceptions were exposures to a modulated field and to the field of 120 V m(-1) which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m(-1) and longer exposure at 23 V m(-1) but it increased after a shorter exposure at 23 V m(-1). At both frequencies no differences in isoenzyme patterns of antioxidative enzymes or HSP70 level were found between control and exposed plants. Our results showed that non-thermal exposure to investigated radiofrequency fields induced oxidative stress in duckweed as well as unspecific stress responses, especially of antioxidative enzymes. However, the observed effects markedly depended on the field frequencies applied as well as on other exposure parameters (strength, modulation and exposure time). Enhanced lipid peroxidation and H(2)O(2) content accompanied by diminished antioxidative enzymes activity caused by exposure to investigated EMFs, especially at 900 MHz, indicate that oxidative stress could partly be due to changed activities of antioxidative enzymes.

The response of duckweed (Lemna minor L.) to salinity and osmotic stress was evaluated by monitoring growth and peroxidase activity every second day, for a period of 17 days. The nutrient medium was supplemented with isoosmolar concentrations of NaCl and mannitol (50 mM and 100 mM NaCl, 100 mM and 200 mM mannitol). Growth decreased markedly with increasing concentrations of NaCl and mannitol. The lower concentrations of NaCl (50 mM) and mannitol (100 mM) started to reduce growth significantly in the second week of the experiment, while the higher concentrations (100 and 200 mM) reduced growth from the beginning. Protein concentrations and peroxidase activity fluctuated during the growth period but, most of the time, they were increased in plants treated with NaCl and mannitol. These results suggest that Lemna minor is sensitive to both salinity and osmotic stress. However, the continued growth, and also the increase in peroxidase activity and protein concentration, during the NaCl and mannitol treatments, demonstrate its potential for adaptation to long-term stress. Although salinity and osmotic stress have similar overall effects on Lemna minor, consistent minor differences in growth, protein concentration and peroxidase activity between plants grown on NaCl and those grown on mannitol suggest overlapping, rather than identical, mechanisms of adaptation to salinity and osmotic stress.

Mejoza u viših biljaka, osobito cvjetnica, dugi je niz godina predmet istraživanja koja su rezultirala boljim razumijevanjem tog procesa, te su dovela do identifikacije niza mejotskih mutanata. Međutim, tek je uvođenjem biljne modelne vrste Arabidopsis thaliana bilo moguće integrirati citološki, molekularni i genetički pristup u istraživanju mejoze. Cjelovito sekvencirani genom, identifikacija gena putem naprednog i reverznog genetičkog pristupa, javno dostupne kolekcije mutanata u kombinaciji s modernim tehnikama molekularne citogenetike i sofisticiranim tehnikama genetskih manipulacija značajno su unaprijedili naše razumijevanje mejoze i njezine kontrole u biljaka. Osobito korisno obilježje mejoze u vrste A. thaliana je da mutacije u mejotskim genima uglavnom ne aktiviraju kontrolne točke staničnog ciklusa, te ne zaustavljaju mejozu, pa se mogu proučavati svi stadiji poremećene mejoze. Nasuprot tome, u kvasca i sisavaca funkcionalne analize mejotskih gena često su spriječene letalnim posljedicama njihovih mutacija. Prezentacija će biti usmjerena na nedavne znanstvene doprinose koji nam omogućavaju bolje razumijevanje ključnih mejotskih događaja uključenih u procese započinjanja, napredovanja i dovršetka mejoze u modelne vrste A. thaliana. Kratki pregled najnovijih spoznaja o biljnoj mejotskoj rekombinaciji bit će predstavljen u prvom dijelu prezentacije s posebnim naglaskom na mejotske uloge evolucijski konzerviranih gena AtSPO11-1 and AtMRE11. U drugom dijelu izlaganja bit će predstavljen novo-karakterizirani gen AtSMG7 i njegova važna ulozi u regulaciji mejotskog staničnog ciklusa, dovršetku mejoze II i stvaranju funkcionalnih spora.

U vremenskom razdoblju od lipnja do studenog 2000. godine obavljena su ispitivanja obraštajne zajednice koja se oblikuje na uronjenim mrežama koje se koriste za izradu kaveza za uzgoj ribe. Eksperimentalni modeli od polietilenskog mrežnog tega širine 1m i dubine 5 m uronjeni su u uzgajalištima na dvije lokacije (uvala Stračinska na otoku Šolti i uvala Peleš kod Rogoznice) i dvije sezone (ljeto i jesen). U obraštajnoj zajednici na obje lokacije zabilježen je veći broj biljnih svojti. U florističkoj zajednici uvale Stračinska i uvale Peleš zabilježene su adaptivne svojte iz sva tri sistematska odjeljka bentoskih alga (Chlorophyta, Pheophyta i Rhodophyta), te predstavnici Diatomeae i Cyanophycea. U pojedinim odjeljcima kod obje promatrane lokacije pokrovnošću se izdvajaju slijedeće svojte: Ulva multiramosa, Cladophora dalmatica, Ectocarpus silisuclosus, Polysiphonia sp., Polysiphonia scopulorum, Titanoderma pustulatum i Pneophyllum fragile. Kod obje lokacije uočeno je brojčano prevladavanje Rhodophyta, što je inače obilježje flore Jadranskog mora. U faunističkoj komponenti obraštaja na obje lokacije dominiraju adaptivne svojte Hydrozoa, Polychaeta i Bryozoa tipične za obraštajne zajednice Jadrana. Struktura i zastupljenost obraštajne zajednice na obje lokacije, ukazuje da unatoč znatnom unosu nutrienata intenzivnim uzgojem ribe nije došlo do biološkog odgovora ekosustava.

Europski hlap, Homarus gammarus, ima široku gegrafsku distribuciju. Na sjeveru se pojavljuje od Lofotenskih otoka na sjeveru Norveške do jugoistočne Švedske i Danske, ali njegova odsutnost u Baltičkom moru je posljedica nižeg saliniteta i niskih temperatura. Proširen je duž cijele obale Europe okolo Britanije i Irske, pa na jug do 30º sjeverne geografske širine na Atlantskoj obali Maroka. Vrsta obitava u manjoj gustoći duž obale i otoka na Mediteranskom moru, javljaju se nalazi na najzapadnijoj točki Crnog mora na Vratima Bospora. Dinamika presvlačenja i rasta larve i postlarve europskog hlapa (Homarus gammarus, L.1758) u kontroliranim uvjetima, je prikazana u ovom radu. Razumijevanjem faktora koji utječu na rast i preživljavanje planktonskog stadija su ključni za razumijevanje mehanizma novačenja.