Kako pisati elektronske strukturne formule Blagović, Branka; Bolf, Nenad
Kemija u industriji; časopis kemičara i tehnologa Jugoslavije,
6/2018, Volume:
67, Issue:
5-6
Journal Article
Peer reviewed
Open access
Lewisove strukture ili elektronske strukturne formule prikazuju na koji su način atomi u molekuli međusobno povezani te raspored valentnih elektrona svih atoma u molekuli. Ako se pored pravila za ...njihovo sastavljanje primijene još i VSEPR-teorija, te pojmovi kao što su formalni naboj, rezonancija i hibridizacija, dobije se prikaz koji vrlo dobro opisuje i građu i oblik molekule.
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Yeast
Saccharomyces cerevisiae
is an ideal model organism for studying molecular mechanisms of the stress response provoked by metals. In this work, yeast cells response to iron (Fe
3+
) or lead (Pb
...2+
) exposure was tested and compared. Survival test was used to determine testing doses of metal ions—for Fe
3+
it was 4 mM and for Pb
2+
8 mM. These (high, over-loaded) doses provoked comparable values of growth inhibition, but different values in vitality measurement. The percentage of metabolically active cells, determined by fluorescent FUN-1 dye, was lower in Pb
2+
than in Fe
3+
treated cells. Besides, endogenous antioxidant defence systems in the cells treated with Pb
2+
were less efficient compared to Fe
3+
. At the mitochondrial level, the effects of metal ions were in correlation with the results of cell metabolic activity. The mitochondrial proteome of Pb
2+
treated cells showed the domination of protein downregulation. Yeast cells treated either with Fe
3+
or Pb
2+
shared 19 common significantly changed proteins. The affected proteins were involved in different cellular process and amongst them only five proteins belong to energy and carbohydrate metabolism, and protein biosynthesis. Based on all obtained results, it is possible to conclude that the effects of Fe
3+
and Pb
2+
on yeast cells show rather specific patterns of toxicity and stress response.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The yeast Saccharomyces cerevisiae is a useful model for studying the influence of different stress factors on eukaryotic cells. In this work we used the pesticide imidacloprid, in the Confidor ...formulation, as the stress factor and analyzed its influence on the metabolic activity, proteome and lipid content and composition of Saccharomyces cerevisiae yeast. During the cultivation of yeast, the lowest recommended application dose of Confidor (0.025%, v/v) was added to the growth media and its influence on the mitochondria, cytosol with microsomes, and the whole yeast cells was monitored. The results show that under the stress provoked by the toxic effects of Confidor, yeast cells density significantly decreased and the percentage of metabolically disturbed cells significantly increased comparing with untreated control. Also, there was a downregulation of majority of glycolytic, gluconeogenesis, and TCA cycle enzymes (Fba1, Adh1, Hxk2, Tal1, Tdh1,Tdh3, Eno1) thus providing enough acetyl‐CoA for the lipid restructuring and accumulation mechanism since we have found the changes in the cell and mitochondrial lipid content and FA composition. This data suggest that lipids could be the molecules that orchestrate the answer of the cells in the stress response to the Confidor treatment.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The aim of this study was to investigate alterations in the content and composition of mitochondrial lipids of brewer’s yeast, which occur during brewing and repetitive recycling. The ...bottom-fermenting brewer’s yeast of Saccharomyces cerevisiae species obtained from industrial beer production was used throughout the study. The first three generations of recycled yeast were analysed. Differences between the generations were more pronounced in the phospholipid and neutral lipid composition than in fatty acid composition. Squalene was present in all generations in high concentrations. The results give insight into the response of yeast cells to stress factors and recycling.
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The fruits of Aronia melanocarpa (Michx.) Elliot contain large amounts of phenolic substances, mainly procyanidins, anthocyanins and other flavonoids, and phenolic acids. The ability of phenolic ...substances to act as antioxidants has been well established.
In this study, we investigated the radical scavenging activity of A. melanocarpa fruit juice (AMFJ).
The method used was electron spin resonance (ESR) spectroscopy. The galvinoxyl free radical was used as a scavenging object. AMFJ was added to the galvinoxyl free radical solution. The measure of the radical scavenging activity was the decrease of signal intensity.
AMFJ showed a potent antiradical activity causing a strong and rapid decrease of signal intensity as a function of time and juice concentration. This effect of AMFJ was probably due to the activity of its phenolic constituents.
The ESR measurements in this study showed a pronounced radical scavenging effect of AMFJ, an important mechanism of its antioxidant activity.
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During beer production and serial recycling, brewer's yeasts are exposed to various stress factors that, overpowering the cellular defence mechanisms, can impair yeast growth and fermentation ...performance. It is well known that yeast cells acclimatize to stress conditions in part by changing the lipid composition of their membranes. The main focus of this study is the effect of stressful fermentation conditions on two phospholipid species, phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn), in Saccharomyces cerevisiae bottom-fermenting brewer's yeast. For this purpose the content and fatty acid profile of these major classes of phospholipids have been compared, as well as their ratio in the whole cells of the starter culture, non-stressed yeast population, and the first three recycled yeast generations. The stressed yeast generations showed an increased mass fraction of PtdCho and a decreased mass fraction of PtdEtn, which led to an increased PtdCho/PtdEtn ratio in the recycled cells as compared to the non-stressed yeast culture. The most pronounced variation of PtdCho/PtdEtn ratio was found in the second yeast generation, yielding a 78 % increase with respect to the starter culture. Variations in the content of both, PtdCho and PtdEtn, were accompanied by a higher mass fraction of unsaturated fatty acids in both phospholipid species (palmitoleic acid in PtdCho, and palmitoleic and oleic in PtdEtn) and by the increased ratio of C.sub.16/C.sub.18 acids in PtdCho. The results suggest that both phospholipid species, including their fatty acids, are highly involved in the adaptation of brewer's yeast to stressful fermentation conditions. Key words: brewer's yeast, Saccharomyces cerevisiae, phospholipids, phosphatidylcholine, phosphatidylethanolamine, fatty acids, stress tolerance, recycling
The neutral lipid fraction of the aerobically grown starter yeast culture of a Saccharomyces cerevisiae brewing strain, and three-first recycled yeast generations exposed to multiple stress factors ...during beer fermentation was studied. No pronounced changes in the cellular neutral lipid content between the non-stressed starter and stressed recycled cells were found. However, it was found that recycled yeast generations modulate their neutral lipid composition during fermentation. The ergosterol content was increased at the expense of steryl esters (SEs) and squalene, which resulted in a higher ergosterol/SEs molar ratio and a slightly higher ergosterol/squalene molar ratio. In addition, the proportion of unsaturated fatty acids, mainly palmitoleic acid increased in the neutral lipid fraction of the stressed recycled yeast generations. These results suggest that some specific neutral lipid species and fatty acids stored in the neutral lipid fraction are involved in the adaptive response of the brewer's yeast to stressful fermentation conditions. The striking finding was a high squalene content in the neutral lipid fraction of both the starter yeast culture and recycled yeast generations (22.4 vs. 19-20%, respectively), implying a possible biotechnological exploitation of this biologically active molecule from the yeast biomass.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Lewisove strukture ili elektronske strukturne formule prikazuju na koji su način atomi u molekuli međusobno povezani te raspored valentnih elektrona svih atoma u molekuli. Ako se pored pravila za ...njihovo sastavljanje primijene još i VSEPR-teorija, te pojmovi kao što su formalni naboj, rezonancija i hibridizacija, dobije se prikaz koji vrlo dobro opisuje i građu i oblik molekule.
Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna .
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U ovom su radu opisani mogući mehanizmi uključeni u nastanak najčešćih neurodegenerativnih bolesti (Alzheimerove, Huntingtonove i Parkinsonove) s posebnim naglaskom na istraživanjima etiopatogeneze i ...suvremenih terapijskih mogućnosti provedenih na kvascu kao modelnom organizmu. Kombinacija jednostavnosti eksperimentalnog pristupa, visokog stupnja očuvanosti metaboličkih puteva s višim eukariotima te relativne jednostavnosti genoma, proteoma i lipidoma čine kvasac idealnim modelnim organizmom za izučavanje homeostaze i funkcije proteina i lipida, između ostalog i u neurodegenerativnim bolestima. Kvasac predstavlja puno jednostavniji no ipak biološki kompletan sustav na kojem se mogu provoditi temeljna istraživanja različitih utjecaja – kako genetskih tako i okolišnih – na brži, jeftiniji i etički prihvatljiviji način u usporedbi sa životinjskim modelima. S obzirom na to da novija istraživanja upućuju na poremećaj dinamike mitohondrija u navedenim bolestima, u radu je detaljnije obrađena uloga mitohondrija u mogućoj etiopatogenezi različitih neurodegenerativnih procesa. Kako je jedna od zajedničkih značajki neurodegenerativnih bolesti poremećena homeostaza membranskih proteina i lipida, uključujući one mitohondrijske, a zbog sve više dokaza o važnosti lipida ne samo za građu, već i za funkcioniranje membranskih sustava, u radu su detaljnije prikazani mehanizmi djelovanja membranskih lipida. Naposljetku, s obzirom na složenost i heterogenost metabolizma lipida, opisane su razlike u glavnim metaboličkim putovima lipida između sisavaca i kvasaca.
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