Synthesis of phenolics and flavonoids in ginger (Zingiber officinale Roscoe) and their effects on photosynthesis rate

The relationship between phenolics and flavonoids synthesis/accumulation and photosynthesis rate was investigated for two Malaysian ginger (Zingiber officinale) varieties grown under four levels of glasshouse light intensity, namely 310, 460, 630 and 790 μmol m 2s 1. High performance liquid chromatography (HPLC) was employed to identify and quantify the polyphenolic components. The results of HPLC analysis indicated that synthesis and partitioning of quercetin, rutin, catechin, epicatechin and naringenin were high in plants grown under 310 μmol m 2s 1. The average value of flavonoids synthesis in leaves for both varieties increased (Halia Bentong 26.1%; Halia Bara 19.5%) when light intensity decreased. Photosynthetic rate and plant biomass increased in both varieties with increasing light intensity. More specifically, a high photosynthesis rate (12.25 μmol CO 2 m 2s 1 in Halia Bara) and plant biomass (79.47 g in Halia Bentong) were observed at 790 μmol m 2s 1. Furthermore, plants with the lowest rate of photosynthesis had highest flavonoids content. Previous studies have shown that quercetin inhibits and salicylic acid induces the electron transport rate in photosynthesis photosystems. In the current study, quercetin was an abundant flavonoid in both ginger varieties. Moreover, higher concentration of quercetin (1.12 mg/g dry weight) was found in Halia Bara leaves grown under 310 μmol m 2s 1 with a low photosynthesis rate. Furthermore, a high content of salicylic acid (0.673 mg/g dry weight) was detected in Halia Bara leaves exposed under 790 μmol m 2s 1 with a high photosynthesis rate. No salicylic acid was detected in gingers grown under 310 μmol m 2s 1. Ginger is a semi-shade loving plant that does not require high light intensity for photosynthesis. Different photosynthesis rates at different light intensities may be related to the absence or presence of some flavonoid and phenolic compounds

Reduced Photoinhibition under Low Irradiance Enhanced Kacip Fatimah (Labisia pumila Benth) Secondary Metabolites, Phenyl Alanine Lyase and Antioxidant Activity

A randomized complete block design experiment was designed to characterize the relationship between production of total flavonoids and phenolics, anthocyanin, photosynthesis, maximum efficiency of photosystem II (Fv/Fm), electron transfer rate (Fm/Fo), phenyl alanine lyase activity (PAL) and antioxidant (DPPH) in Labisia pumila var. alata, under four levels of irradiance (225, 500, 625 and 900 μmol/m2/s) for 16 weeks. As irradiance levels increased from 225 to 900 μmol/m2/s, the production of plant secondary metabolites (total flavonoids, phenolics and antocyanin) was found to decrease steadily. Production of total flavonoids and phenolics reached their peaks under 225 followed by 500, 625 and 900 μmol/m2/s irradiances. Significant positive correlation of production of total phenolics, flavonoids and antocyanin content with Fv/Fm, Fm/Fo and photosynthesis indicated up-regulation of carbon-based secondary metabolites (CBSM) under reduced photoinhibition on the under low light levels condition. At the lowest irradiance levels, Labisia pumila extracts also exhibited a significantly higher antioxidant activity (DPPH) than under high irradiance. The improved antioxidative activity under low light levels might be due to high availability of total flavonoids, phenolics and anthocyanin content in the plant extract. It was also found that an increase in the production of CBSM was due to high PAL activity under low light, probably signifying more availability of phenylalanine (Phe) under this condition

Emission of methane, carbon monoxide, carbon dioxide and short-chain hydrocarbons from vegetation foliage under ultraviolet irradiation

The original report that plants emit methane (CH (4)) under aerobic conditions caused much debate and controversy. Critics questioned experimental techniques, possible mechanisms for CH (4) production and the nature of estimating global emissions. Several studies have now confirmed that aerobic CH (4) emissions can be detected from plant foliage but the extent of the phenomenon in plants and the precise mechanisms and precursors involved remain uncertain. In this study, we investigated the role of environmentally realistic levels of ultraviolet (UV) radiation in causing the emission of CH (4) and other gases from foliage obtained from a wide variety of plant types. We related our measured emissions to the foliar content of methyl esters and lignin and to the epidermal UV absorbance of the species investigated. Our data demonstrate that the terrestrial vegetation foliage sampled did emit CH (4), with a range in emissions of 0.6–31.8 ng CH (4) g(−1) leaf DW h(−1), which compares favourably with the original reports of experimental work. In addition to CH (4) emissions, our data show that carbon monoxide, ethene and propane are also emitted under UV stress but we detected no significant emissions of carbon dioxide or ethane

Η εμπειρία της διαδικτυακής εκπαίδευσης των μεταπτυχιακών φοιτητών του προγράμματος «Κλινική και Πειραματική Νευροχειρουργική» στην εποχή του Covid19:εργασία ερωτηματολογίου

Σκοπός της παρούσας έρευνας ήταν να μελετηθούν οι απόψεις, προτιμήσεις και προτάσεις των μεταπτυχιακών φοιτητών του ΠΜΣ “Κλινική και Πειραματική Νευροχειρουργική” σχετικά με την εξ αποστάσεως εκπαίδευση πάνω σε θεωρητικά μαθήματα νευροανατομίας που παρακολούθησαν κατά τη διάρκεια των μέτρων που επιβλήθηκαν εξ αιτίας της πανδημίας του Covid–19. Η έρευνα θεωρείται ιδιαίτερα σημαντική καθώς από αυτή αναδεικνύονται τα προβλήματα που συναντάνε οι μεταπτυχιακοί φοιτητές στην παρακολούθηση των μαθημάτων της εξ αποστάσεως εκπαίδευσης καθώς και ο βαθμός που αυτού του είδους η εκπαίδευση καλύπτει τις εκπαιδευτικές τους ανάγκες. Μέσω της έρευνας εξετάστηκαν τα βασικότερα προβλήματα που εντοπίζουν οι μεταπτυχιακοί φοιτητές στην εφαρμογή της εξ αποστάσεως εκπαίδευσης, ο βαθμός που αυτή καλύπτει τις εκπαιδευτικές τους ανάγκες, καθώς και ο τρόπος που επιδρά το δημογραφικό προφίλ των φοιτητών στις απόψεις τους για το εν λόγω ζήτημα. Η μεθοδολογία που ακολουθήθηκε για τη διενέργεια της έρευνας ήταν αυτή της ποσοτικής πρωτογενούς έρευνας, με χρήση ενός δομημένου ερωτηματολογίου. Στην έρευνα συμμετείχαν 40 φοιτητές, με την πλειοψηφία να είναι δημόσιοι υπάλληλοι, έως 40 ετών, με εκπαιδευτικό επίπεδο βασικού πτυχίου, περισσότερες από 40 ώρες εμπειρίας σε διαδικτυακή εκπαίδευση και εμπειρία από μεικτή (σύγχρονη και ασύγχρονη) εξ αποστάσεως εκπαίδευση. Τα αποτελέσματα της έρευνας έδειξαν ότι υπήρξαν σε μικρό βαθμό εμπόδια στην εφαρμογή της εξ αποστάσεως διδασκαλίας. Οι συμμετέχοντες έδειξαν τάση συμφωνίας ότι ο νέος τρόπος διδασκαλίας της εξ αποστάσεως εκπαίδευσης τους είναι αρεστός, ωστόσο δήλωσαν πως προτιμούν την δια ζώσης. Ικανοποιητική θεωρήθηκε η επικοινωνία με τον καθηγητή και μέτρια με τους φοιτητές. Οι συμμετέχοντες συμφώνησαν ότι η μεικτή μέθοδος σύγχρονης και ασύγχρονης εκπαίδευσης ήταν αναγκαία για την κάλυψη των μαθησιακών στόχων των μαθημάτων. Επιπλέον, οι προτάσεις των μεταπτυχιακών φοιτητών ως προς τη βελτίωση της εξ αποστάσεως εκπαίδευσης εστίαζαν στη βελτίωση της δομής και της λειτουργίας της ηλεκτρονικής τάξης και ότι χρειάζεται επιπλέον ώρα διαδικτυακής διδασκαλίας. Τέλος, η έρευνα έδειξε ότι η ηλικία, το μορφωτικό επίπεδο, η επαγγελματική κατάσταση, η εμπειρία στην διαδικτυακή εκπαίδευση επιδρούν στις απόψεις των φοιτητών.The purpose of this study was to examine the views, preferences and suggestions of postgraduate students on the teleducation courses in neuroanatomy they attended during the measures imposed due to the Covid-19 pandemic. The research is considered particularly important as it highlights the problems encountered by postgraduate students in attending distance education courses as well as the extent to which this type of education meets their educational needs. The research examined the main problems the postgraduate students encountered during the implementation of distance learning, the extent to which it meets their educational needs, as well as the way in which the demographic profile of students affects their views on the issue. The methodology used to conduct the research was that of quantitative primary research, using a structured questionnaire. The research involved 40 neuroanatomy students, the majority of whom are civil servants, up to 40 years old, with a basic education level, more than 40 hours of experience in online education and experience from mixed (synchronous and asynchronous) distance education. The results of the research showed that there were few obstacles in the application of distance learning. The participants showed a tendency to agree that the new way of teaching distance education is to their liking, however they stated that they prefer live education Communication with the teacher was considered satisfactory and moderate with the students. The participants agreed that the mixed method of synchronous and asynchronous education was necessary to meet the learning objectives of the courses. In addition, the postgraduate students' suggestions for improving distance education focused on improving the structure and operation of the e-classroom and the need for additional online teaching time. Finally, the present findings indicate that the age, educational level, professional status and experience in online education are parameters that affect the views of students

The ability of abaxial and adaxial epidermis of sun and shade leaves to attenuate UV-A and UV-B radiation in relation to the UV absorbing capacity of the whole leaf methanolic extracts

The UV-absorbing capacity (measured as A(310) cm(-2) and A(365) cm(-2) or AUVR cm(-2)) of the shade leaves of four representative evergreen sclerophylls of the Mediterranean region (Quercus coccifera, Q. ilex, Arbutus andrachne and A. unedo) was considerably lower than the corresponding one of sun leaves of the same species. However, fibre optic microprobe measurements showed that adaxial as well as abaxial epidermis of shade leaves of all examined plants, except abaxial epidermis of A. andrachne, were almost as effective as the corresponding ones of the sun leaves in screening out most of the incident UV-B radiation. There is probably a threshold, under which the concentration of the UV-B absorbing compounds in the protective tissues is not furthermore reduced, in spite of the low levels of the stress factor (UV-B radiation) in the environment. On the other hand, the ability of both abaxial and adaxial epidermis to attenuate UV-A radiation, except of adaxial leaf epidermis of Quercus species, depended on the UV absorbing capacity of the whole-leaf extracts, with different correlation patterns between the two Quercus species and the two Arbutus species. This could be explained by the fact that shade leaves showed not only quantitative, but also qualitative differences (higher A(310)/A(365) ratio) in the absorbance of their methanolic extracts compared to these of sun leaves. The results of the present study showed that we should not always correlate the depth of penetration of UV radiation into sun and shade leaves according to the corresponding UV absorbing capacity of the whole leaf methanolic extracts, without taking into account all the anatomical, developmental and biochemical (such as different composition and distribution of the UV-absorbing compounds among the different protective tissues) peculiarities of the leaves of each species