This review is to summarize and analyze the currently available knowledge concerning the action of oat (Avena sativa L.) consumption on obesity, as well as possible constituents and extra- and intracellular mediators responsible for its anti-obesity effect. The oat constituents could reduce fat storage via several mediatory mechanisms - brain centers regulating appetite, gastrointestinal functions, gut bacteria, fat synthesis and metabolism and maybe via changes in oxidative processes, steroid hormones receptors and adipose tissue vascularization. Several oat constituents (starch, fiber and beta-glucan) could have anti-obesity properties, whilst one oat constituent (starch or fiber) could affect fat storage via several mechanisms of action.
- MeSH
- lidé MeSH
- obezita metabolismus MeSH
- oves * metabolismus MeSH
- potravní vláknina * metabolismus farmakologie MeSH
- škrob metabolismus farmakologie MeSH
- tuková tkáň metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Škrob je biopolymer, obsažený v rostlinách a řasách. V zelených rostlinách se tvoří při fotosyntéze v chloroplastech jako tzv. tranzitní škrob, který je v průběhu temné fáze transportován v podobě rozpustných sacharidů do zásobních orgánů rostlin, kde je opět převe‐ den do podoby škrobových zrn. Tato opětná syntéza se liší pro jednoděložné a dvouděložné rostliny. Průmyslově izolovaný škrob má řadu využití, hlavní roli hraje enzymová hydrolýza na sirupy, které pak mohou být výchozí látkou pro celou řadu dalších biochemických transformací. Článek se věnuje rovněž nutričním aspektům škrobu, především jeho stravitelností. Je popsán základní princip enzymo‐ vých metod ke stanovení obsahu celkového škrobu, obsahu amylosy, rychle a pomalu stravitelného škrobu a škrobu rezistentního.
Starch is a biopolymer found in plants and algae. In green plants, it is formed during photosynthesis in the chloroplasts as so ‐called transitory starch, which is transported during the dark phase in the form of soluble carbohydrates to the storage organs of plants, where it is again converted into the form of starch granules. This repeated synthesis is different for monocots and dicots. Industria‐ lly isolated starch has a number of uses, the main role is played by enzyme hydrolysis into syrups, which can then be the starting material for a whole range of subsequent biochemical transformations. The article also deals with the nutritional aspects of starch, especially its digestibility. The basic principle of enzyme methods to determine the content of total starch, amylose content, rapidly and slowly digestible starch and resistant starch is described.
Green algae are fast-growing microorganisms that are considered promising for the production of starch and neutral lipids, and the chlorococcal green alga Parachlorella kessleri is a favorable model, as it can produce both starch and neutral lipids. P. kessleri commonly divides into more than two daughter cells by a specific mechanism-multiple fission. Here, we used synchronized cultures of the alga to study the effects of supra-optimal temperature. Synchronized cultures were grown at optimal (30 °C) and supra-optimal (40 °C) temperatures and incident light intensities of 110 and 500 μmol photons m-2 s-1. The time course of cell reproduction (DNA replication, cellular division), growth (total RNA, protein, cell dry matter, cell size), and synthesis of energy reserves (net starch, neutral lipid) was studied. At 40 °C, cell reproduction was arrested, but growth and accumulation of energy reserves continued; this led to the production of giant cells enriched in protein, starch, and neutral lipids. Furthermore, we examined whether the increased temperature could alleviate the effects of deuterated water on Parachlorella kessleri growth and division; results show that supra-optimal temperature can be used in algal biotechnology for the production of protein, (deuterated) starch, and neutral lipids.
An increase in temperature can have a profound effect on the cell cycle and cell division in green algae, whereas growth and the synthesis of energy storage compounds are less influenced. In Chlamydomonas reinhardtii, laboratory experiments have shown that exposure to a supraoptimal temperature (39 °C) causes a complete block of nuclear and cellular division accompanied by an increased accumulation of starch. In this work we explore the potential of supraoptimal temperature as a method to promote starch production in C. reinhardtii in a pilot-scale photobioreactor. The method was successfully applied and resulted in an almost 3-fold increase in the starch content of C. reinhardtii dry matter. Moreover, a maximum starch content at the supraoptimal temperature was reached within 1-2 days, compared with 5 days for the control culture at the optimal temperature (30 °C). Therefore, supraoptimal temperature treatment promotes rapid starch accumulation and suggests a viable alternative to other starch-inducing methods, such as nutrient depletion. Nevertheless, technical challenges, such as bioreactor design and light availability within the culture, still need to be dealt with.
- MeSH
- biomasa * MeSH
- bioreaktory MeSH
- buněčný cyklus MeSH
- Chlamydomonas reinhardtii metabolismus MeSH
- fotobioreaktory * MeSH
- kultivační média MeSH
- mikrořasy MeSH
- průmyslová mikrobiologie metody MeSH
- škrob metabolismus MeSH
- světlo MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Today, many microbial amylases are available commercially and they have almost completely replaced chemical hydrolysis in several industry processes. Amylases from microorganisms have a broad spectrum of industrial applications as they are more stable than amylases obtained from plants and animals. The objective of this work was to use potato baits in an Atlantic Forest remnant located in Ribeirão Preto, São Paulo, Brazil, in order to obtain amylase-producing fungi with potential for biotechnological application. In addition, the culture conditions for the fungal strain that presented higher production of glucoamylase were standardized using industrial wastes. For this, 6 PET bottles containing potatoes as baits were scattered at different points in an Atlantic forest remnant. After 6 days, the samples were collected, and the filamentous fungi were isolated in Petri dishes. Fungi screening was carried out in Khanna liquid medium with 1% starch Reagen®, at 30 °C, pH 6.0, under static conditions for 4 days. Proteins and glucoamylase activity were determined by Bradford and 3,5-dinitrosalicylic acid (DNS), respectively. Among all isolated fungi, A. carbonarius showed the highest glucoamylase production. Its best cultivation conditions were observed in Khanna medium, 4 days, at 30 °C, pH 6.0, under static condition with 0.1% yeast extract and 1% starch Reagen®. Wheat and brewing residues were also used as inducers for large quantities of glucoamylase production. A. carbonarius showed to be a good alternative for the wheat and brewing waste destinations in order to obtain high added value products.
- MeSH
- Aspergillus enzymologie izolace a purifikace MeSH
- bioprospekting MeSH
- glukoamylasa metabolismus MeSH
- hydrolýza MeSH
- lesy MeSH
- pšenice metabolismus MeSH
- škrob metabolismus MeSH
- tropické klima MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Brazílie MeSH
Crocosphaera is a major dinitrogen (N2)-fixing microorganism, providing bioavailable nitrogen (N) to marine ecosystems. The N2-fixing enzyme nitrogenase is deactivated by oxygen (O2), which is abundant in marine environments. Using a cellular scale model of Crocosphaera sp. and laboratory data, we quantify the role of three O2 management strategies by Crocosphaera sp.: size adjustment, reduced O2 diffusivity, and respiratory protection. Our model predicts that Crocosphaera cells increase their size under high O2 Using transmission electron microscopy, we show that starch granules and thylakoid membranes are located near the cytoplasmic membranes, forming a barrier for O2 The model indicates a critical role for respiration in protecting the rate of N2 fixation. Moreover, the rise in respiration rates and the decline in ambient O2 with temperature strengthen this mechanism in warmer water, providing a physiological rationale for the observed niche of Crocosphaera at temperatures exceeding 20°C. Our new measurements of the sensitivity to light intensity show that the rate of N2 fixation reaches saturation at a lower light intensity (∼100 μmol m-2 s-1) than photosynthesis and that both are similarly inhibited by light intensities of >500 μmol m-2 s-1 This suggests an explanation for the maximum population of Crocosphaera occurring slightly below the ocean surface.IMPORTANCECrocosphaera is one of the major N2-fixing microorganisms in the open ocean. On a global scale, the process of N2 fixation is important in balancing the N budget, but the factors governing the rate of N2 fixation remain poorly resolved. Here, we combine a mechanistic model and both previous and present laboratory studies of Crocosphaera to quantify how chemical factors such as C, N, Fe, and O2 and physical factors such as temperature and light affect N2 fixation. Our study shows that Crocosphaera combines multiple mechanisms to reduce intracellular O2 to protect the O2-sensitive N2-fixing enzyme. Our model, however, indicates that these protections are insufficient at low temperature due to reduced respiration and the rate of N2 fixation becomes severely limited. This provides a physiological explanation for why the geographic distribution of Crocosphaera is confined to the warm low-latitude ocean.
- MeSH
- fixace dusíku * MeSH
- kyslík metabolismus MeSH
- sinice cytologie metabolismus účinky záření MeSH
- škrob metabolismus MeSH
- světlo * MeSH
- teplota * MeSH
- transmisní elektronová mikroskopie MeSH
- tylakoidy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
S rozvojom civilizačných chorôb, ako je diabetes mellitus, metabolický syndróm, prípadne obezita, rastie aj úsilie nachádzať nové liečivá predovšetkým z prírodných zdrojov. Patria medzi ne aj inhibítory α-amylázy, enzýmu, ktorý v tele zdravého človeka štiepi polysacharidy na jednoduchšie cukry. Vzhľadom k tomu, že toto štiepenie ovplyvňuje glykémiu, ktorú je snaha terapeuticky meniť, vzrastá aj záujem o tieto látky. Tento prehľadový článok mapuje druhy inhibítorov amylázy vrátane ich prírodných zdrojov.
Development of civilization diseases such as diabetes mellitus, metabolic syndrome or obesity, enforces the increasing effort to find new drugs, especially from natural sources. These include α-amylase inhibitors, which break down polysacharides into simple sugars in the body of a healthy person. As this cleavage affects the level of blood sugar, which is sought to be therapeutically influenced, there is a growing interest in these substances. This review maps the types of amylase inhibitors, including their natural resources.
- Klíčová slova
- rostlinné inhibítory, štěpení škrobu,
- MeSH
- alfa-amylasy antagonisté a inhibitory terapeutické užití MeSH
- amylasy * antagonisté a inhibitory terapeutické užití MeSH
- lidé MeSH
- škrob metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
We studied the effect of reducing the levels of the mitochondrial electron carrier cytochrome c (CYTc) in Arabidopsis thaliana. Plants with CYTc deficiency have delayed growth and development, and reach flowering several days later than the wild-type but with the same number of leaves. CYTc-deficient plants accumulate starch and glucose during the day, and contain lower levels of active gibberellins (GA) and higher levels of DELLA proteins, involved in GA signaling. GA treatment abolishes the developmental delay and reduces glucose accumulation in CYTc-deficient plants, which also show a lower raise in ATP levels in response to glucose. Treatment of wild-type plants with inhibitors of mitochondrial energy production limits plant growth and increases the levels of DELLA proteins, thus mimicking the effects of CYTc deficiency. In addition, an increase in the amount of CYTc decreases DELLA protein levels and expedites growth, and this depends on active GA synthesis. We conclude that CYTc levels impinge on the activity of the GA pathway, most likely through changes in mitochondrial energy production. In this way, hormone-dependent growth would be coupled to the activity of components of the mitochondrial respiratory chain.
- MeSH
- Arabidopsis růst a vývoj metabolismus MeSH
- cytochromy c nedostatek metabolismus fyziologie MeSH
- energetický metabolismus MeSH
- gibereliny metabolismus fyziologie MeSH
- glukosa metabolismus MeSH
- homeostáza MeSH
- mitochondrie metabolismus MeSH
- proteiny huseníčku metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- škrob metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Volatile compounds (VCs) emitted by phylogenetically diverse microorganisms (including plant pathogens and microbes that do not normally interact mutualistically with plants) promote photosynthesis, growth, and the accumulation of high levels of starch in leaves through cytokinin (CK)-regulated processes. In Arabidopsis (Arabidopsis thaliana) plants not exposed to VCs, plastidic phosphoglucose isomerase (pPGI) acts as an important determinant of photosynthesis and growth, likely as a consequence of its involvement in the synthesis of plastidic CKs in roots. Moreover, this enzyme plays an important role in connecting the Calvin-Benson cycle with the starch biosynthetic pathway in leaves. To elucidate the mechanisms involved in the responses of plants to microbial VCs and to investigate the extent of pPGI involvement, we characterized pPGI-null pgi1-2 Arabidopsis plants cultured in the presence or absence of VCs emitted by Alternaria alternata We found that volatile emissions from this fungal phytopathogen promote growth, photosynthesis, and the accumulation of plastidic CKs in pgi1-2 leaves. Notably, the mesophyll cells of pgi1-2 leaves accumulated exceptionally high levels of starch following VC exposure. Proteomic analyses revealed that VCs promote global changes in the expression of proteins involved in photosynthesis, starch metabolism, and growth that can account for the observed responses in pgi1-2 plants. The overall data show that Arabidopsis plants can respond to VCs emitted by phytopathogenic microorganisms by triggering pPGI-independent mechanisms.
- MeSH
- Alternaria chemie účinky záření MeSH
- Arabidopsis enzymologie růst a vývoj mikrobiologie fyziologie MeSH
- buněčná stěna metabolismus účinky záření MeSH
- cytokininy metabolismus MeSH
- fotosyntéza účinky záření MeSH
- glukosa-6-fosfátisomerasa metabolismus MeSH
- mezofylové buňky účinky léků metabolismus účinky záření MeSH
- mutace genetika MeSH
- plastidy účinky léků enzymologie MeSH
- proteiny huseníčku metabolismus MeSH
- proteom metabolismus MeSH
- škrob metabolismus MeSH
- světlo MeSH
- těkavé organické sloučeniny farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
