Uloga enzima u metabolizmu ugljikohidrata pri diferencijaciji staničnih linija šećerne repe

Plant development is influenced by changes in the levels and types of sugars produced metabolically. The normal (N), habituated organogenic (HO) and habituated nonorganogenic (HNO) sugar beet cell lines originate from the same mother plant but exhibit distinct levels of morphogenesis and differentiation, and contain different levels of simple carbohydrates. We aim to elucidate whether differences in the abundance and activity of enzymes involved in carbohydrate metabolism and sugar sensing/signalling help explain the different carbohydrate profiles and differentiation states of the cell lines. Using 13C NMR spectroscopy to analyze cultures of the cell lines over 28 days, we found that N cells accumulated sucrose; HO cells sucrose, glucose and fructose; and HNO cells glucose and fructose. Of three invertase isoforms, the activity of cell wall invertase (CWI) was highest in all the cell lines, and CWI activity was greatest in HNO line. The specific accumulation of intracellular carbohydrates during subculture correlated strongly with CWI activity but less so with the vacuolar and cytoplasmic invertase isoforms, or with sucrose synthase activity. Cell lines showed differences in how sugars regulated invertase and sucrose synthase activity. The role of sugar sensing in the regulation of CWI activity was investigated in the cell lines using glucose and sucrose, as well as carbohydrate analogues such as mannitol, 2-O-deoxyglucose and 3-O-methylglucose. Differences in the regulation of CWI activity by carbohydrates across the three cell lines suggest that CWI can be fine-tuned according to the specific carbohydrate requirements of each line during growth. Differences in sugar signalling pathways across the cell lines were explored using glucose and sucrose in the presence of inhibitors of protein kinases or phosphatases. Taken together, our findings suggest that specific regulation of CWI activity plays an important role in determining the intracellular carbohydrate levels of sugar beet cell lines, and possibly their differentiation state as well.Na razvoj biljke utječu promjene razine i tipa proizvedenog šećera. Iako sve stanične linije šećerne repe, i to normalna, prilagođena organogena i prilagođena neorganogena potječu od iste biljke, na različitim su stupnjevima diferencijacije i morfogeneze te sadrže različitu količinu jednostavnih ugljikohidrata. Svrha je rada bila utvrditi može li se razlikama u količini i aktivnosti enzima, koji sudjeluju u metabolizmu šećera te onih u detekciji i prijenosu signala šećera, objasniti razlika u stupnju diferencijacije staničnih linija te u udjelu ugljikohidrata u njima. Primjenom 13C NMR spektroskopije analizirane su stanične linije tijekom 28 dana kultivacije i ustanovljeno je da normalne stanične linije akumuliraju saharozu, prilagođena organogena stanična linija saharozu, glukozu i fruktozu, a prilagođena neorganogena stanična linija šećerne repe glukozu i fruktozu. Od 3 izoformna oblika invertaze najveća je aktivnost invertaze stanične stijenke u sve 3 stanične linije, osobito u prilagođenih neorganogenih stanica. Specifičnost akumulacije ugljikohidrata u stanici tijekom kultivacije uvelike je ovisila o aktivnosti invertaze stanične stijenke, a manje o onoj vakuolarne i citoplazmatske invertaze te saharoza sintetaze. Šećeri su različito regulirali aktivnost invertaze stanične stijenke i saharoza sintetaze, ovisno o tipu stanične linije. Njihova je uloga istražena pomoću glukoze i saharoze te njihovih analoga, kao što su manitol, 2-O-deoksiglukoza i 3-O-metilglukoza. Utvrđeno je da se aktivnost invertaze stanične stijenke može fino regulirati pomoću ugljikohidrata, ovisno o potrebi staničnih linija za izvorom šećera tijekom rasta. Razlike u putovima prijenosa signala šećera u staničnih linija istražene su pomoću glukoze i saharoze u prisutnosti inhibitora protein kinaza i fosfataza. Na kraju, rezultati autora potvrđuju da specifična regulacija aktivnosti invertaze stanične stijenke ima važnu ulogu u određivanju razine ugljikohidrata u staničnim linijama šećerne repe, a možda i stupnju diferencijacije stanica

Zebularine, a DNA Methylation Inhibitor, Activates Anthocyanin Accumulation in Grapevine Cells

Through its role in the regulation of gene expression, DNA methylation can participate in the control of specialized metabolite production. We have investigated the link between DNA methylation and anthocyanin accumulation in grapevine using the hypomethylating drug, zebularine and Gamay Teinturier cell suspensions. In this model, zebularine increased anthocyanin accumulation in the light, and induced its production in the dark. To unravel the underlying mechanisms, cell transcriptome, metabolic content, and DNA methylation were analyzed. The up-regulation of stress-related genes, as well as a decrease in cell viability, revealed that zebularine affected cell integrity. Concomitantly, the global DNA methylation level was only slightly decreased in the light and not modified in the dark. However, locus-specific analyses demonstrated a decrease in DNA methylation at a few selected loci, including a CACTA DNA transposon and a small region upstream from the UFGT gene, coding for the UDP glucose:flavonoid-3-O-glucosyltransferase, known to be critical for anthocyanin biosynthesis. Moreover, this decrease was correlated with an increase in UFGT expression and in anthocyanin content. In conclusion, our data suggest that UFGT expression could be regulated through DNA methylation in Gamay Teinturier, although the functional link between changes in DNA methylation and UFGT transcription still needs to be demonstrated

Contribution à la connaissance de la biodiversité entomique africaine. III. – Oedichirus georgesi n. sp. de Sao Tomé & Principe (Coleoptera, Staphylinidae, Paederinae).

International audienceOedichirus georgesi n. sp. (Staphylinidae, Paederinae) is described from Sao Tomé & Principe. It differs from the Oedichirus known to date by the shape of its aedeagus and by a series of characteristics of the head, pronotum and Sternum VIII.Oedichirus georgesi n. sp. (Staphylinidae, Paederinae) est décrit de Sao Tomé & Principe. Il se distingue des Oedichirus connus à ce jour par la forme de son édéage et par une série de caractères au niveau de la tête, du pronotum et du sternite VIII

Analyse in vitro des interactions érythrocytes de mouton / babesia divergens

Pour analyser les intéractions en B. divergens (protozoaire parasite des bovins) et les globules rouges de mouton (étudié comme hôte expérimental) deux axes ont été suivis. D'une part le cycle intra-érythrocytaire du parasite a été suivi en temps réel. Le développement a été comparé dans des hématies de réceptivités différentes, mettant ainsi en évidence les phases inhibées chez les moutons non-réceptifs. D'autre part, des anticorps monoclonaux dirigés contre B. divergens ont été produits afin d'étudier les protéines impliquées dans ces interactions.NANTES-Ecole Nat.Vétérinaire (441092302) / SudocSudocFranceF