A természetes szelekció gondolata a 18. századtól

A tudományfilozófiai TDK dolgozatomon végighúzódó főtéma a természetes szelekció, illetve a faji változatosság, ami alapjában véve maghatározó jelenség a biológiában. Dolgozatom első részében azt vizsgálom, hogy milyen elképzelések voltak a természetes szelekcióról és a faj fogalmáról a 18.-19. században. Figyelembe kell vennünk, hogy Darwin kora előtt is foglalkoztak a természetes szelekcióval, ezért ezek rövid tárgyalása is elengedhetetlen (Darwin kora alatt az 1830-1870-es időintervallumot értem; Darwin maga 1838-ban kezdett foglalkozni a transzmutabilitással). A dolgozat második felében azt tanulmányozom, hogy az új evolúcióelméletnek milyen volt a fogadtatása hazánkban egészen napjainkig

The Effect of High Concentrations of Glufosinate Ammonium on the Yield Components of Transgenic Spring Wheat (Triticum aestivum L.) Constitutively Expressing the bar Gene

We present an experiment done on a bar+ wheat line treated with 14 different concentrations of glufosinate ammonium—an effective component of nonselective herbicides—during seed germination in a closed experimental system. Yield components as number of spikes per plant, number of grains per spike, thousand kernel weight, and yield per plant were thoroughly analysed and statistically evaluated after harvesting. We found that a concentration of glufosinate ammonium 5000 times the lethal dose was not enough to inhibit the germination of transgenic plants expressing the bar gene. Extremely high concentrations of glufosinate ammonium caused a bushy phenotype, significantly lower numbers of grains per spike, and thousand kernel weights. Concerning the productivity, we observed that concentrations of glufosinate ammonium 64 times the lethal dose did not lead to yield depression. Our results draw attention to the possibilities implied in the transgenic approaches

Aflatoxigenic Aspergillus flavus and Aspergillus parasiticus strains in Hungarian maize fields

Due to the climate change, aflatoxigenic Aspergillus species and strains have appeared in several European countries, contaminating different agricultural commodities with aflatoxin. Our aim was to screen the presence of aflatoxigenic fungi in maize fields throughout the seven geographic regions of Hungary. Fungi belonging to Aspergillus section Flavi were isolated in the ratio of 26.9% and 42.3% from soil and maize samples in 2013, and these ratios decreased to 16.1% and 34.7% in 2014. Based on morphological characteristics and the sequence analysis of the partial calmodulin gene, all isolates proved to be Aspergillus flavus, except four strains, which were identified as Aspergillus parasiticus. About half of the A. flavus strains and all the A. parasiticus strains were able to synthesize aflatoxins. Aflatoxigenic Aspergillus strains were isolated from all the seven regions of Hungary. A. parasiticus strains were found in the soil of the regions Southern Great Plain and Southern Transdanubia and in a maize sample of the region Western Transdanubia. In spite of the fact that aflatoxins have rarely been detected in feeds and foods in Hungary, aflatoxigenic A. flavus and A. parasiticus strains are present in the maize culture throughout Hungary posing a potential threat to food safety

Transcriptome analysis of an ochratoxin-A biodegrading bacteria

Fighting against and decreasing the effect of mycotoxins is an emerging problem. Among post- harvest methods are physical, chemical, and biological ones. This study is focusing on the biological tools for minimalizing the harmful effect of the ochratoxin-A (OTA) occurring on crops and fodders. The bacteria Cupriavidus basilensis ÖR16 strain has very good ability to detoxify ochratoxin-A to phenylalanine and ochratoxin-alfa. In previous studies the degradation rate of the ÖR16 bacteria was over 98%. The whole genome sequencing was also performed by our group in 2012. During this research, the enzymes, and genes responsible for the OTA degradation were characterized via transcriptome analyses. 15 genes were identified, which could play role in the degradation of OTA. Testing and investigating these nominated genes and enzymes could lead for a prepared fodder additive, which can help in the elimination of the negative effects of OTA in the future

Lack of Dose- and Time-Dependent Effects of Aflatoxin B1 on Gene Expression and Enzymes Associated with Lipid Peroxidation and the Glutathione Redox System in Chicken

Effects of aflatoxin B1 (AFB1) on lipid peroxidation and glutathione system were investigated in chicken liver. In a three-week feeding trial, different doses (<1.0 μg/kg (control diet), 17.0 µg (diet A1), 92.0 µg (diet A2), and 182.0 µg (diet A3) AFB1 kg/feed) were used. Markers of lipid peroxidation, conjugated dienes and trienes showed higher values in A3, while amounts of thiobarbituric acid reactive substances were increased in the A1 group at day 21. Glutathione content was lower at day 14 in Group A2. Glutathione peroxidase 4 activity was increased at days 7 and 21 in the A3 group but reduced in the A2 and A3 groups at day 14. The GPX4 gene was downregulated at day 7 in the A2 group, but overregulated at days 14 and 21, and at day 14 in the A3 group. GSS was downregulated at day 14 in the A1 group but overregulated at day 21 in A1 and A2 groups. GSR was downregulated at days 7 and 21 in all treatment groups, but on day 14, induction was observed in the A3 group. The results indicated that AFB1 did not induce dose- or time-dependent effects on the glutathione redox system and its encoding genes at the dose range used, which means that oxidative stress is not the primary effect of AFB1 toxicity

Ochratoxin A és biodegradációs melléktermékeinek hatása zebradánió (Danio rerio) embriókra

Napjainkra gyorsuló ütemben növekednek azok a potenciális veszélyt hordozó területek nagysága, amelyek ideálisak a mikotoxinok termelődéséhez. Friss kutatások alapján már minden magyaror-szági régióban megtalálhatóak az Aspergillus fajok, így sürgetővé vált a mikotoxin szennyezettség problémájának megoldása. A mikotoxinok ártalmatlanítására számos módszer ismert, melyek kö-zül kísérleteinkben egy biodegradációs eljárás hatékonyságát vizsgáltuk. A mikotoxinok mikrobiá-lis bontása során, bizonyos esetekben a kiindulási anyagnál is toxikusabb melléktermékek képződ-hetnek. Ezeknek a metabolitoknak a biomonitoringjára az EFSA ajánlást adott ki, melyben meg-fogalmazta, hogy a biodegradáció közben keletkező̋ metabolitok biológiai hatását is vizsgálni kell. Korábbi munkáink során kidolgozott mikroinjektálási módszer alkalmazásával egy bizonyítottan Ochratoxin A (OTA) bontó mikrobatörzs minősítését kívántuk elvégezni. Az injektálás során előre meghatározott mennyiségű̋ vizsgálati anyagot juttattunk az embriók szervezetébe, majd 120 órás korban letális végpontra vizsgáltuk őket. A mikrobatörzs minősítésekor a törzstől származó normál és bontott minták teszteredményeit hasonlítottuk össze, az 5 ppm OTA tartalmú oldat eredménye-ivel. A baktériumtörzs 96%-os bontási hatékonyságot mutatott kísérleteinkben. Az eredményeink alapján elmondható, hogy az OTA bontó ŐR 16 jelzésű baktériumtörzs (Cupriavidus Basilensis) termel toxikus anyagokat, azonban ennek toxicitása alacsonyabb az OTA tartalmú oldathoz ké-pest. A baktérium OTA bontási melléktermékei szintén alacsonyabb toxicitást mutatnak a kiindu-lási OTA oldathoz képest. Következtetésként elmondható, hogy az ŐR 16 jelzésű baktériumtörzs alkalmazható lehet zárt térben OTA-szennyezett takarmány detoxifikációjára

Effect of short-term aflatoxin exposure in combination with medicinal herb mixture on lipid peroxidation and glutathione redox system in laying hens

Aflatoxins are well known hepatotoxic mycotoxins, which mainly contaminate the cereal grains. Those induce lipid peroxidation and impair the antioxidant, including glutathione redox system in long-term studies. The purpose of present study was to investigate the short-term (36-hour) effect of feeding aflatoxin B1 (AFB1) contaminated diet alone or in combination with a medicinal herb mixture on lipid peroxidation (conjugated dienes and trienes, and malondialdehyde), and on parameters of the glutathione system (reduced glutathione and glutathione peroxidase) in blood plasma, red blood cell haemolysate, liver and kidney homogenate of 49-week old Bovans Goldline laying hens. The results revealed that AFB1 (125 m /kg feed) did not have effect on feed intake, body and liver weight, but increased malondialdehyde content was observed in blood plasma and red blood cell haemolysate as effect of feeding AFB1 and medicinal herb mixture at 36th hour of the trial. However, the same diet resulted in lower malondialdehyde content in liver, but not in kidney. Reduced glutathione concentrations showed variance among treatments; thus due to inclusion of medicinal herb mixture in the diet lower values were measured in red blood cell haemolysate. Glutathione peroxidase activity was significantly lower in all treated groups as compared to the control at 36th hour of the trial in blood plasma, but not in other tissues. The results are contradictory with previous findings, probably due to the short-term exposure, and/or to medicinal herb mixture supplementation as it could moderately modify the effect of AFB1