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  1. Modelling photoperiod in enhancing hydrogen production from Chlorella vulgaris sp. while bioremediating ammonium and organic pollutants in municipal wastewater
    Ardo FM, Khoo KS, Ahmad Sobri MZ, Suparmaniam U, Ethiraj B, Anwar AF, et al.
    Environ Pollut, 2024 Apr 01;346:123648.
    PMID: 38408504 DOI: 10.1016/j.envpol.2024.123648
    Municipal wastewater is ubiquitously laden with myriad pollutants discharged primarily from a combination of domestic and industrial activities. These heterogeneous pollutants are threating the natural environments when the traditional activated sludge system fails sporadically to reduce the pollutants' toxicities. Besides, the activated sludge system is very energy intensive, bringing conundrums for decarbonization. This research endeavoured to employ Chlorella vulgaris sp. In converting pollutants from municipal wastewater into hydrogen via alternate light and dark fermentative process. The microalgae in attached form onto 1 cm3 of polyurethane foam cubes were adopted in optimizing light intensity and photoperiod during the light exposure duration. The highest hydrogen production was recorded at 52 mL amidst the synergistic light intensity and photoperiod of 200 μmolm-2s-1 and 12:12 h (light:dark h), respectively. At this lighting condition, the removals of chemical oxygen demand (COD) and ammoniacal nitrogen were both achieved at about 80%. The sustainability of microalgal fermentative performances was verified in recyclability study using similar immobilization support material. There were negligible diminishments of hydrogen production as well as both COD and ammoniacal nitrogen removals after five cycles, heralding inconsequential microalgal cells' washout from the polyurethane support when replacing the municipal wastewater medium at each cycle. The collected dataset was finally modelled into enhanced Monod equation aided by Python software tool of machine learning. The derived model was capable to predict the performances of microalgae to execute the fermentative process in producing hydrogen while subsisting municipal wastewater at arbitrary photoperiod. The enhanced model had a best fitting of R2 of 0.9857 as validated using an independent dataset. Concisely, the outcomes had contributed towards the advancement of municipal wastewater treatment via microalgal fermentative process in producing green hydrogen as a clean energy source to decarbonize the wastewater treatment facilities.
    Matched MeSH terms: Photoperiod
  2. Crop photoperiodism model 2.0 for the flowering time of sorghum and rice that includes daily changes in sunrise and sunset times and temperature acclimation
    Clerget B, Sidibe M, Bueno CS, Grenier C, Kawakata T, Domingo AJ, et al.
    Ann Bot, 2021 07 28;128(1):97-113.
    PMID: 33821947 DOI: 10.1093/aob/mcab048
    BACKGROUND AND AIMS: Daylength determines flowering dates. However, questions remain regarding flowering dates in the natural environment, such as the synchronous flowering of plants sown simultaneously at highly contrasting latitudes. The daily change in sunrise and sunset times is the cue for the flowering of trees and for the synchronization of moulting in birds at the equator. Sunrise and sunset also synchronize the cell circadian clock, which is involved in the regulation of flowering. The goal of this study was to update the photoperiodism model with knowledge acquired since its conception.

    METHODS: A large dataset was gathered, including four 2-year series of monthly sowings of 28 sorghum varieties in Mali and two 1-year series of monthly sowings of eight rice varieties in the Philippines to compare with previously published monthly sowings in Japan and Malaysia, and data from sorghum breeders in France, Nicaragua and Colombia. An additive linear model of the duration in days to panicle initiation (PI) and flowering time using daylength and daily changes in sunrise and sunset times was implemented.

    KEY RESULTS: Simultaneous with the phyllochron, the duration to PI of field crops acclimated to the mean temperature at seedling emergence within the usual range of mean cropping temperatures. A unique additive linear model combining daylength and daily changes in sunrise and sunset hours was accurately fitted for any type of response in the duration to PI to the sowing date without any temperature input. Once calibrated on a complete and an incomplete monthly sowing series at two tropical latitudes, the model accurately predicted the duration to PI of the concerned varieties from the equatorial to the temperate zone.

    CONCLUSIONS: Including the daily changes in sunrise and sunset times in the updated photoperiodism model largely improved its accuracy at the latitude of each experiment. More research is needed to ascertain its multi-latitudinal accuracy, especially at latitudes close to the equator.

    Matched MeSH terms: Photoperiod
  3. Fulltext Circadian Rhythms in Legumes: What Do We Know and What Else Should We Explore?
    Kugan HM, Rejab NA, Sahruzaini NA, Harikrishna JA, Baisakh N, Cheng A
    Int J Mol Sci, 2021 Apr 27;22(9).
    PMID: 33925559 DOI: 10.3390/ijms22094588
    The natural timing devices of organisms, commonly known as biological clocks, are composed of specific complex folding molecules that interact to regulate the circadian rhythms. Circadian rhythms, the changes or processes that follow a 24-h light-dark cycle, while endogenously programmed, are also influenced by environmental factors, especially in sessile organisms such as plants, which can impact ecosystems and crop productivity. Current knowledge of plant clocks emanates primarily from research on Arabidopsis, which identified the main components of the circadian gene regulation network. Nonetheless, there remain critical knowledge gaps related to the molecular components of circadian rhythms in important crop groups, including the nitrogen-fixing legumes. Additionally, little is known about the synergies and trade-offs between environmental factors and circadian rhythm regulation, especially how these interactions fine-tune the physiological adaptations of the current and future crops in a rapidly changing world. This review highlights what is known so far about the circadian rhythms in legumes, which include major as well as potential future pulse crops that are packed with nutrients, particularly protein. Based on existing literature, this review also identifies the knowledge gaps that should be addressed to build a sustainable food future with the reputed "poor man's meat".
    Matched MeSH terms: Photoperiod
  4. Reproductive seasonality in primates: patterns, concepts and unsolved questions
    Heldstab SA, van Schaik CP, Müller DWH, Rensch E, Lackey LB, Zerbe P, et al.
    Biol Rev Camb Philos Soc, 2021 02;96(1):66-88.
    PMID: 32964610 DOI: 10.1111/brv.12646
    Primates, like other mammals, exhibit an annual reproductive pattern that ranges from strictly seasonal breeding to giving birth in all months of the year, but factors mediating this variation are not fully understood. We applied both a categorical description and quantitative measures of the birth peak breadth based on daily observations in zoos to characterise reproductive seasonality in 141 primate species with an average of 941 birth events per species. Absolute day length at the beginning of the mating season in seasonally reproducing species was not correlated between populations from natural habitats and zoos. The mid-point of latitudinal range was a major factor associated with reproductive seasonality, indicating a correlation with photoperiod. Gestation length, annual mean temperature, natural diet and Malagasy origin were other important factors associated with reproductive seasonality. Birth seasons were shorter with increasing latitude of geographical origin, corresponding to the decreasing length of the favourable season. Species with longer gestation periods were less seasonal than species with shorter ones, possibly because shorter gestation periods more easily facilitate the synchronisation of reproductive activity with annual cycles. Habitat conditions with higher mean annual temperature were also linked to less-seasonal reproduction, independently of the latitude effect. Species with a high percentage of leaves in their natural diet were generally non-seasonal, potentially because the availability of mature leaves is comparatively independent of seasons. Malagasy primates were more seasonal in their births than species from other regions. This might be due to the low resting metabolism of Malagasy primates, the comparatively high degree of temporal predictability of Malagasy ecosystems, or historical constraints peculiar to Malagasy primates. Latitudinal range showed a weaker but also significant association with reproductive seasonality. Amongst species with seasonal reproduction in their natural habitats, smaller primate species were more likely than larger species to shift to non-seasonal breeding in captivity. The percentage of species that changed their breeding pattern in zoos was higher in primates (30%) than in previous studies on Carnivora and Ruminantia (13 and 10%, respectively), reflecting a higher concentration of primate species in the tropics. When comparing only species that showed seasonal reproduction in natural habitats at absolute latitudes ≤11.75°, primates did not differ significantly from these two other taxa in the proportion of species that changed to a less-seasonal pattern in zoos. However, in this latitude range, natural populations of primates and Carnivora had a significantly higher proportion of seasonally reproducing species than Ruminantia, suggesting that in spite of their generally more flexible diets, both primates and Carnivora are more exposed to resource fluctuation than ruminants.
    Matched MeSH terms: Photoperiod
  5. Environmental effects on the oxygen consumption rate in juvenile Epinephelus fuscoguttatus (Forsskal, 1775)
    Okomoda VT, Mithun S, Chatterji A, Effendy MAW, Oladimeji AS, Abol-Munafi AB, et al.
    Fish Physiol Biochem, 2020 Aug;46(4):1497-1505.
    PMID: 32378001 DOI: 10.1007/s10695-020-00807-7
    This study was designed to optimize the culture conditions of juvenile Epinephelus fuscoguttatus (Forsskål, 1775) under laboratory conditions. To this effect, the rate of oxygen consumption was monitored as an index of stress under different temperature, salinity, pH, photoperiod, and urea concentrations. The result obtained after 12 h of exposure suggests the preference of the juvenile E. fuscoguttatus to a temperature range of 15-25 °C and salinity of 30 ppt. Based on this study, temperature was found to be the most lethal as 100% mortality was observed after 6 h in fish exposure to temperatures above the optimal (≥ 30 °C). However, the oxygen consumption rate was similar under the different pH, photoperiod, and urea concentration tested. It was concluded that water temperature was most critical in terms of respiration physiology of the juvenile E. fuscoguttatus given the range and levels of environmental factors tested in this study.
    Matched MeSH terms: Photoperiod
  6. Fulltext Effect of temperature on population growth of copepod, Euterpina acutifrons
    Sitti Raehanah Muhamad Shaleh, Marlena Amatus, Najamuddin Abdul Basri, Rossita Shapawi
    Borneo Journal of Marine Science and Aquaculture, 2020;4(1):57-61.
    MyJurnal
    This study was aimed at determining the optimum temperature for culturing the copepod, Euterpina acutifrons. The trial was conducted for 10 days in chambers at temperatures of 25⁰C, 27⁰C, 29⁰C and 31⁰C. Ten adult individuals of the copepod were randomly collected and placed into three replicate experimental flasks for each treatment. Throughout the trial, the salinity, light intensity, and photoperiod were maintained at 30 ±2psu, 100molm-2s-1 and 12:12 light-dark cycle, respectively. The copepods were fed with 80,000cell/ml Isochrysis sp. daily. At the end of the trial, the total numbers of E. acutifrons nauplii, copepodites and adults were determined and counted using Sedgwick-Rafter. The highest population was found at 27⁰C with mean total population of 800±100 individuals from an initial of 10 individuals. This was followed by those reared at 25⁰C and 29⁰C where the population counts were 700±100 individuals and 367±115 individuals, respectively. At the 31⁰C, all the copepod specimens were found dead on day 5th. Statistical analysis showed that the temperature had a significant effect (P
    Matched MeSH terms: Photoperiod
  7. A Rhythmic Gene Entrained to Midnight May Regulate Photoperiod-Controlled Flowering in Arabidopsis
    Yeang HY
    Yale J Biol Med, 2019 06;92(2):213-223.
    PMID: 31249482
    The widely held explanation for photoperiod-controlled flowering in long-day plants is largely embodied in the External Coincidence Hypothesis which posits that flowering is induced when activity of a rhythmic gene that regulates it (a putative "flowering gene") occurs in the presence of light. Nevertheless, re-examination of the Arabidopsis flowering data from non 24-hour cycles of Roden et al. suggests that External Coincidence is not tenable if the circadian rhythm of the "flowering gene" were entrained to sunrise as commonly accepted. On the other hand, the hypothesis is supported if circadian cycling of the gene conforms to a solar rhythm, and its entrainment is to midnight on the solar clock. Data available point to flowering being induced by the gene which peaks in its expression between 16 to 19 h after midnight. In the normal 24 h cycle, that would be between 4 p.m. and 7 p.m., regardless of the photoperiod. Such timing of the "flowering gene" expression allows for variable coincidence between gene activity and light, depending on the photoperiod and cycle period. A correlation is found between earliness of flowering and the degree of coincidence of "flowering gene" expression with light (r = 0.88, p<0.01).
    Matched MeSH terms: Photoperiod*
  8. Fulltext Outcomes and modifiable resuscitative characteristics amongst pan-Asian out-of-hospital cardiac arrest occurring at night
    Ho AFW, Hao Y, Pek PP, Shahidah N, Yap S, Ng YY, et al.
    Medicine (Baltimore), 2019 Mar;98(10):e14611.
    PMID: 30855446 DOI: 10.1097/MD.0000000000014611
    Studies are divided on the effect of day-night temporal differences on clinical outcomes in out-of-hospital cardiac arrest (OHCA). This study aimed to elucidate any differences in OHCA survival between day and night occurrence, and the factors associated with differences in survival.This was a prospective, observational study of OHCA cases across multinational Pan-Asian sites. Cases were divided according to time call received by dispatch centers into day (0700H-1900H) and night (1900H-0659H). Primary outcome was 30-day survival. Secondary outcomes were prehospital and hospital modifiable resuscitative characteristics.About 22,501 out of 55,881 cases occurred at night. Night cases were less likely to be witnessed (40.2% vs. 43.1%, P 
    Matched MeSH terms: Photoperiod
  9. Fulltext Circadian rhythms in insecticide susceptibility, metabolic enzyme activity, and gene expression in Cimex lectularius (Hemiptera: Cimicidae)
    Khalid MF, Lee CY, Doggett SL, Veera Singham G
    PLoS One, 2019;14(6):e0218343.
    PMID: 31206537 DOI: 10.1371/journal.pone.0218343
    Many insect species display daily variation of sensitivity to insecticides when they are exposed to the same concentration at different times during the day. To date, this has not been investigated in bed bugs. To address this, we explored circadian rhythms in insecticide susceptibility, xenobiotic metabolizing (XM) gene expressions, and metabolic detoxification in the common bed bug, Cimex lectularius. An insecticide susceptible Monheim strain of C. lectularius was most tolerant of deltamethrin during the late photophase at ZT9 (i.e. nine hours after light is present in the light-dark cycle (LD) cycle) and similarly repeated at CT9 (i.e. nine hours into the subjective day in constant darkness (DD)) suggesting endogenous circadian involvement in susceptibility to deltamethrin. No diel rhythm was observed against imidacloprid insecticide despite significant daily susceptibility in both LD and DD conditions. Rhythmic expressions of metabolic detoxification genes, GSTs1 and CYP397A1 displayed similar expression patterns with total GST and P450 enzyme activities in LD and DD conditions, respectively. The oscillation of mRNA levels of GSTs1 and CYP397A1 was found consistent with peak phases of deltamethrin susceptibility in C. lectularius. This study demonstrates that circadian patterns of metabolic detoxification gene expression occur within C. lectularius. As a consequence, insecticide efficacy can vary dramatically throughout a 24 hour period.
    Matched MeSH terms: Photoperiod
  10. An improved light dark box test by using a real-time video tracking system
    Narayanan SN, Kumar RS
    Acta. Biol. Hung., 2018 Dec;69(4):371-384.
    PMID: 30587025 DOI: 10.1556/018.69.2018.4.1
    In the behavioral science field, many of the oldest tests have still most frequently been used almost in the same way for decades. The subjective influence of human observer and the large inter-observer and interlab differences are substantial among these tests. This necessitates the possibility of using technological innovations for behavioral science to obtain new parameters, results and insights as well. The light-dark box (LDB) test is a characteristic tool used to assess anxiety in rodents. A complete behavioral analysis (including both anxiety and locomotion parameters) is not possible by performing traditional LDB test protocol, as it lacks the usage of a real-time video recording of the test. In the current report, we describe an improved approach to conduct LDB test using a real-time video tracking system.
    Matched MeSH terms: Photoperiod*
  11. Thermal tolerance and preference of exploited turbinid snails near their range limit in a global warming hotspot
    Lah RA, Benkendorff K, Bucher D
    J Therm Biol, 2017 Feb;64:100-108.
    PMID: 28166939 DOI: 10.1016/j.jtherbio.2017.01.008
    Predicted global climate change has prompted numerous studies of thermal tolerances of marine species. The upper thermal tolerance is unknown for most marine species, but will determine their vulnerability to ocean warming. Gastropods in the family Turbinidae are widely harvested for human consumption. To investigate the responses of turbinid snails to future conditions we determined critical thermal maxima (CTMax) and preferred temperatures of Turbo militaris and Lunella undulata from the tropical-temperate overlap region of northern New South Wales, on the Australian east coast. CTMax were determined at two warming rates: 1°C/30min and 1°C/12h. The number of snails that lost attachment to the tank wall was recorded at each temperature increment. At the faster rate, T. militaris had a significantly higher CTMax (34.0°C) than L. undulata (32.2°C). At the slower rate the mean of both species was lower and there was no significant difference between them (29.4°C for T. militaris and 29.6°C for L. undulata). This is consistent with differences in thermal inertia possibly allowing animals to tolerate short periods at higher temperatures than is possible during longer exposure times, but other mechanisms are not discounted. The thermoregulatory behaviour of the turban snails was determined in a horizontal thermal gradient. Both species actively sought out particular temperatures along the gradient, suggesting that behavioural responses may be important in ameliorating short-term temperature changes. The preferred temperatures of both species were higher at night (24.0°C and 26.0°C) than during the day (22.0°C and 23.9°C). As the snails approached their preferred temperature, net hourly displacement decreased. Preferred temperatures were within the average seasonal seawater temperature range in this region. However, with future predicted water temperature trends, the species could experience increased periods of thermal stress, possibly exceeding CTMax and potentially leading to range contractions.
    Matched MeSH terms: Photoperiod
  12. Occurrence of stomatal patchiness and its spatial scale in leaves from various sizes of trees distributed in a South-east Asian tropical rainforest in Peninsular Malaysia
    Kamakura M, Kosugi Y, Takanashi S, Uemura A, Utsugi H, Kassim AR
    Tree Physiol, 2015 Jan;35(1):61-70.
    PMID: 25595752 DOI: 10.1093/treephys/tpu109
    In this study, we demonstrated the occurrence of stomatal patchiness and its spatial scale in leaves from various sizes of trees grown in a lowland dipterocarp forest in Peninsular Malaysia. To evaluate the patterns of stomatal behavior, we used three techniques simultaneously to analyze heterobaric or homobaric leaves from five tree species ranging from 0.6 to 31 m in height: (i) diurnal changes in chlorophyll fluorescence imaging, (ii) observation and simulation of leaf gas-exchange rates and (iii) a pressure-infiltration method. Measurements were performed in situ with 1000 or 500 μmol m(-2) s(-1) photosynthetic photon flux density. Diurnal patterns in the spatial distribution of photosynthetic electron transport rate (J) mapped from chlorophyll fluorescence images, a comparison of observed and simulated leaf gas-exchange rates, and the spatial distribution of stomatal apertures obtained from the acid-fuchsin-infiltrated area showed that patchy stomatal closure coupled with severe midday depression of photosynthesis occurred in Neobalanocarpus heimii (King) Ashton, a higher canopy tree with heterobaric leaves due to the higher leaf temperature and vapor pressure deficit. However, subcanopy or understory trees showed uniform stomatal behavior throughout the day, although they also have heterobaric leaves. These results suggest that the occurrence of stomatal patchiness is determined by tree size and/or environmental conditions. The analysis of spatial scale by chlorophyll fluorescence imaging showed that several adjacent anatomical patches (lamina areas bounded by bundle-sheath extensions within the lamina) may co-operate for the distributed patterns of J and stomatal apertures.
    Matched MeSH terms: Photoperiod
  13. First Report of Xanthomonas oryzae pv. oryzicola Causing Bacterial Leaf Streak of Rice in Burundi
    Afolabi O, Milan B, Amoussa R, Koebnik R, Poulin L, Szurek B, et al.
    Plant Dis, 2014 Oct;98(10):1426.
    PMID: 30703943 DOI: 10.1094/PDIS-05-14-0504-PDN
    On May 9, 2013, symptoms reminiscent of bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola were observed on rice plants at the panicle emergence stage at Musenyi, Gihanga, and Rugombo fields in Burundi. Affected leaves showed water-soaked translucent lesions and yellow-brown to black streaks, sometimes with visible exudates on leaf surfaces. Symptomatic leaves were ground in sterile water and the suspensions obtained were subjected to a multiplex PCR assay diagnostic for X. oryzae pathovars (3). Three DNA fragments (331, 691, and 945 bp) corresponding to X. oryzae pv. oryzicola were observed after agarose gel electrophoresis. Single bacterial colonies were then isolated from surface-sterilized, infected leaves after grinding in sterile water and plating of 10-fold dilutions of the cell suspension on semi-selective PSA medium (4). After incubation at 28°C for 5 days, each of four independent cultures yielded single yellow, mucoid Xanthomonas-like colonies (named Bur_1, Bur_2, Bur_6, and Bur_7) that resembled the positive control strain MAI10 (1). These strains originated from Musenyi (Bur_1), Gihanga (Bur_2), and Rugumbo (Bur_6 and Bur_7). Multiplex PCR assays on the four putative X. oryzae pv. oryzicola strains yielded the three diagnostic DNA fragments mentioned above. All strains were further analyzed by sequence analysis of portions of the gyrB gene using the universal primers gyrB1-F and gyrB1-R for PCR amplification (5). The 762-bp DNA fragment was identical to gyrB sequences from the Asian X. oryzae pv. oryzicola strains BLS256 (Philippines), ICMP 12013 (China), LMG 797 and NCPPB 2921 (both Malaysia), and from the African strain MAI3 (Mali) (2). The partial nucleotide sequence of the gyrB gene of Bur_1 was submitted to GenBank (Accession No. KJ801400). Pathogenicity tests were performed on greenhouse-grown 4-week-old rice plants of the cvs. Nipponbare, Azucena, IRBB 1, IRBB 2, IRBB 3, IRBB 7, FKR 14, PNA64F4-56, TCS 10, Gigante, and Adny 11. Bacterial cultures were grown overnight in PSA medium and re-suspended in sterile water (1 × 108 CFU/ml). Plants were inoculated with bacterial suspensions either by spraying or by leaf infiltration (1). For spray inoculation, four plants per accession and strain were used while three leaves per plant and four plants per accession and strain were inoculated by tissue infiltration. After 15 days of incubation in a BSL-3 containment facility (27 ± 1°C with a 12-h photoperiod), the spray-inoculated plants showed water-soaked lesions with yellow exudates identical to those seen in the field. For syringe-infiltrated leaves, the same symptoms were observed at the infiltrated leaf area. Re-isolation of bacteria from symptomatic leaves yielded colonies with the typical Xanthomonas morphology that were confirmed by multiplex PCR to be X. oryzae pv. oryzicola, thus fulfilling Koch's postulates. Bur_1 has been deposited in the Collection Française de Bactéries Phytopathogènes as strain CFBP 8170 ( http://www.angers-nantes.inra.fr/cfbp/ ). To our knowledge, this is the first report of X. oryzae pv. oryzicola causing bacterial leaf streak on rice in Burundi. Further surveys will help to assess its importance in the country. References: (1) C. Gonzalez et al., Mol. Plant Microbe Interact. 20:534, 2007. (2) A. Hajri et al. Mol. Plant Pathol. 13:288, 2012. (3) J. M. Lang et al. Plant Dis. 94:311, 2010. (4) L. Poulin et al. Plant Dis. 98:1423, 2014. (5) J. M. Young et al. Syst. Appl. Microbiol. 31:366, 2008.
    Matched MeSH terms: Photoperiod
  14. Fulltext Optimization of culture conditions (sucrose, pH, and photoperiod) for in vitro regeneration and early detection of somaclonal variation in ginger lime (Citrus assamensis)
    Yaacob JS, Mahmad N, Mat Taha R, Mohamed N, Mad Yussof AI, Saleh A
    ScientificWorldJournal, 2014;2014:262710.
    PMID: 24977187 DOI: 10.1155/2014/262710
    Various explants (stem, leaf, and root) of Citrus assamensis were cultured on MS media supplemented with various combinations and concentrations (0.5-2.0 mg L(-1)) of NAA and BAP. Optimum shoot and root regeneration were obtained from stem cultures supplemented with 1.5 mg L(-1) NAA and 2.0 mg L(-1) BAP, respectively. Explant type affects the success of tissue culture of this species, whereby stem explants were observed to be the most responsive. Addition of 30 gL(-1) sucrose and pH of 5.8 was most optimum for in vitro regeneration of this species. Photoperiod of 16 hours of light and 8 hours of darkness was most optimum for shoot regeneration, but photoperiod of 24 hours of darkness was beneficial for production of callus. The morphology (macro and micro) and anatomy of in vivo and in vitro/ex vitro Citrus assamensis were also observed to elucidate any irregularities (or somaclonal variation) that may arise due to tissue culture protocols. Several minor micromorphological and anatomical differences were observed, possibly due to stress of tissue culture, but in vitro plantlets are expected to revert back to normal phenotype following full adaptation to the natural environment.
    Matched MeSH terms: Photoperiod*
  15. Flashing light as growth stimulant in cultivation of green microalgae, Chlorella sp. utilizing airlift photobioreactor
    Fathurrahman L, Hajar AH, Sakinah DW, Nurhazwani Z, Ahmad J
    Pak J Biol Sci, 2013 Nov 15;16(22):1517-23.
    PMID: 24511694
    One of the main limitations of productivity in photobioreactor is the inefficient conversion of the available light into biomass. Photoautotrophic cells such as microalgae only absorb a small fraction of supplied illumination due to limitation of its photosystem's (PS) absorbing rate. However, phenomenon of Flashing Light Effect (FLE) allows microalgae to utilize strong light exceptionally through intermittent exposure. Exposure of strong light at correct frequency of light and dark photoperiod would allow two pigment-protein complexes, PSI and PSII to be at the equilibrium mid-point potential to allow efficient light conversion. Narrow range of optimum frequency is crucial since overexposure to strong light would injured photosynthetic apparatus whereas longer dark period would contributed to loss of biomass due to triacylglycerol metabolism. The behaviour of microalgae towards various illumination conditions of FLE was determined at batch Photobioreactor (PBR) by varying the aeration flow rate: 16.94, 33.14 and 49.28 mL sec(-1) which yield, respectively the light exposure time of 3.99, 1.71 and 1.1 seconds per cycle. Maximum cell density in FLE-PBR was significantly higher at the exponential phase as compared to the continuously illuminated culture (p = 5.62 x 10(-5), a = 0.05) under the flow rate of 25.07 mL sec(-1). Maximum cell density yield of FLE-PBR and continuously illuminated PBR was, respectively 3.1125 x 10(7) and 2.947 x 10(7) cells mL(-1). Utilization of FLE as an innovative solution to increase the efficiency of microalgae to convert light into chemical energy would revolutionize the microalgae culture, reduce the time for cultivation and produce higher maximum biomass density.
    Matched MeSH terms: Photoperiod
  16. Intensity of blue LED light: a potential stimulus for biomass and lipid content in fresh water microalgae Chlorella vulgaris
    Atta M, Idris A, Bukhari A, Wahidin S
    Bioresour Technol, 2013 Nov;148:373-8.
    PMID: 24063820 DOI: 10.1016/j.biortech.2013.08.162
    Light quality and the intensity are key factors which render microalgae as a potential source of biodiesel. In this study the effects of various intensities of blue light and its photoperiods on the growth and lipid content of Chlorella vulgaris were investigated by using LED (Light Emitting Diode) in batch culture. C. vulgaris was grown for 13 days at three different light intensities (100, 200 and 300 μmol m(-2)s(-1)). Effect of three different light and dark regimes (12:12, 16:08 and 24:00 h Light:Dark) were investigated for each light intensity at 25°C culture temperature. Maximum lipid content (23.5%) was obtained due to high efficiency and deep penetration of 200 μmol m(-2)s(-1) of blue light (12:12 L:D) with improved specific growth (1.26 d(-1)) within reduced cultivation time of 8 days. White light could produce 20.9% lipid content in 10 days at 16:08 h L:D.
    Matched MeSH terms: Photoperiod
  17. Fulltext Solar rhythm in the regulation of photoperiodic flowering of long-day and short-day plants
    Yeang HY
    J Exp Bot, 2013 Jul;64(10):2643-52.
    PMID: 23645867 DOI: 10.1093/jxb/ert130
    In photoperiodic flowering, long-day (LD) plants are induced to flower seasonally when the daylight hours are long, whereas flowering in short-day (SD) plants is promoted under short photoperiods. According to the widely accepted external coincidence model, flowering occurs in LD Arabidopsis when the circadian rhythm of the gene CONSTANS (CO) peaks in the afternoon, when it is light during long days but dark when the days are short. Nevertheless, extending this explanation to SD flowering in rice, Oriza sativa, requires LD and SD plants to have 'opposite light requirements' as the CO orthologue in rice, HEADING-DATE1 (Hd1), promotes flowering only under short photoperiods. This report proposes a role of the plant's solar rhythm in promoting seasonal flowering. The interaction between rhythmic genes entrained to the solar clock and those entrained to the circadian clock form the basis of an internal coincidence model that explains both LD and SD flowering equally well. The model invokes no presumption of opposite light requirements between LD and SD plants, and further argues against any specific requirement of either light or darkness for SD flowering. Internal coincidence predicts the inhibition of SD flowering of the rice plant by a night break (a brief interruption of light), while it also provides a plausible explanation for how a judiciously timed night break promotes Arabidopsis flowering even on short days. It is the timing of the light transitions (sunrise and sunset) rather than the duration of light or darkness per se that regulates photoperiod-controlled flowering.
    Matched MeSH terms: Photoperiod*
  18. Leaf Spot on Lettuce (Lactuca sativa) Caused by Stemphylium solani, a New Disease in Malaysia
    Nasehi A, Kadir JB, Esfahani MN, Mahmodi F, Ghadirian H, Ashtiani FA, et al.
    Plant Dis, 2013 May;97(5):689.
    PMID: 30722190 DOI: 10.1094/PDIS-10-12-0902-PDN
    In June 2011, lettuce (Lactuca sativa) plants cultivated in major lettuce growing areas in Malaysia, including the Pahang and Johor states, had extensive leaf spots. In severe cases, disease incidence was recorded more than 80%. Symptoms on 50 observed plants initially were as water soaked spots (1 to 2 mm in diameter) on leaves, and then became circular spots spreading over much of the leaves. In this research, main lettuce growing areas infected by the pathogen in the mentioned states were investigated and the pathogen was isolated onto potato dextrose agar (PDA). Colonies observed were greyish green to light brown. Single conidia were formed at the terminal end of conidiophores that were 28.8 to 40.8 μm long and 11.0 to 19.2 μm wide, and 2 to 7 transverse and 1 to 4 longitudinal septa. To produce conidia, the fungus was grown on potato carrot agar (PCA) and V8 juice agar media under 8-h/16-h light/dark photoperiod. Fourteen isolates were identified Stemphylium solani based on morphological criteria described by Kim et al. (1). To confirm morphological characterization, DNA of the fungus was extracted from mycelium and PCR was done using universal primers ITS5 (5'-GGAAGTAAAAGTCGTAACAAGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3'), which amplified the internal transcribed spacer (ITS) region of rDNA (2). The sequencing result was subjected to BLAST analysis which was 99% identical to the other published sequences in the GenBank database (GenBank Accession Nos. AF203451 and HQ840713). The nucleotide sequence was deposited in GenBank under Accession No. JQ736022. Pathogenicity testing of representative isolate was done using 20 μl of conidial suspension with a concentration of 1 × 105/ml in droplets (three drops on each leaf) on four detached 45-day-old lettuce leaves cv. BBS012 (3). Fully expended leaves were placed on moist filter paper in petri dishes and were incubated in humid chambers at 25°C. The leaves inoculated with sterile water served as control. After 7 days, disease symptoms were observed, which were similar to those symptoms collected in infected fields and the fungus was reisolated and confirmed as S. solani based on morphological criteria (1) and molecular characterization (2). Control leaves remained healthy. Pathogenicity testing was completed twice. To our knowledge, this is the first report of S. solani on lettuce in Malaysia and it may become a serious problem because of its broad host range, variability in pathogenic isolates, and prolonged active phase of the disease cycle. Previous research has shown that S. solani is a causal agent of gray leaf spot on lettuce in China (4). References: (1) B. S. Kim et al. Plant Pathol. J. 20:85, 2004. (2) Y. R. Mehta et al. Current Microbiol. 44:323, 2002. (3) B. M. Pryor and T. J. Michailides. Phytopathology 92:406, 2002. (4) F. L. Tai. Sylloge Fungorum Sinicorum, Sci. Press, Acad. Sin., Peking, 1979.
    Matched MeSH terms: Photoperiod
  19. An Outbreak of Leaf Spot Caused by Stemphylium solani on Eggplant in Malaysia
    Nasehi A, Kadir JB, Esfahani MN, Mahmodi F, Ghadirian H, Ashtiani FA, et al.
    Plant Dis, 2013 May;97(5):689.
    PMID: 30722195 DOI: 10.1094/PDIS-10-12-0901-PDN
    In 2011, a severe gray leaf spot was observed on eggplant (Solanum melongena) in major eggplant growing areas in Malaysia, including the Pahang, Johor, and Selangor states. Disease incidence was >70% in severely infected areas of about 150 ha of eggplant greenhouses and fields examined. Symptoms initially appeared as small (1 to 5 mm diameter), brownish-black specks with concentric circles on the lower leaves. The specks then coalesced and developed into greyish-brown, necrotic lesions, which also appeared on the upper leaves. Eventually, the leaves senesced and were shed. Tissue cut from the edges of leaf spots were surface-sterilized in 1% NaOCl for 2 min, rinsed in sterilized water, dried, and incubated on potato dextrose agar (PDA). Fungal colonies were greyish green to light brown, and produced a yellow pigment. Single, muriform, brown, oblong conidia formed at the terminal end of each conidiophore, were each 21.6 to 45.6 μm long and 11.5 to 21.6 μm wide, and contained 2 to 7 transverse and 1 to 4 longitudinal septa. The conidiophores were tan to light brown and ≤220 μm long. Based on these morphological criteria, 25 isolates of the fungus were identified as Stemphylium solani (1). To produce conidia in culture, 7-day-old single-conidial cultures were established on potato carrot agar (PCA) and V8 juice agar media under an 8-h/16-h light/dark photoperiod at 25°C (4). Further confirmation of the identification was obtained by molecular characterization in which fungal DNA was extracted and the internal transcribed spacer (ITS) region of ribosomal DNA amplified using primers ITS5 and ITS4 (2), followed by direct sequencing. A BLAST search in the NCBI database revealed that the sequence was 99% identical with published ITS sequences for two isolates of S. solani (Accession Nos. AF203451 and HQ840713). The amplified ITS region was deposited in GenBank (JQ736023). Pathogenicity testing of a representative isolate was performed on detached, 45-day-old eggplant leaves of the cv. 125066-X under laboratory conditions. Four fully expanded leaves (one wounded and two non-wounded leaflets/leaf) were placed on moist filter paper in petri dishes, and each leaflet inoculated with a 20-μl drop of a conidial suspension containing 1 × 105 conidia/ml in sterilized, distilled water (3). The leaves were wounded by applying pressure to leaf blades with the serrated edge of forceps. Four control leaves were inoculated similarly with sterilized, distilled water. Inoculated leaves were incubated in humid chambers at 25°C with 95% RH and a 12-h photoperiod. After 7 days, symptoms similar to those observed in the original fields developed on both wounded and non-wounded inoculated leaves, but not on control leaves, and S. solani was reisolated consistently from the symptoms using the same method as the original isolations. Control leaves remained asymptomatic and the fungus was not isolated from these leaves. The pathogenicity testing was repeated with similar results. To our knowledge, this is the first report of S. solani on eggplant in Malaysia. References: (1) B. S. Kim et al. Plant Pathol. J. 20:85, 2004. (2) Y. R. Mehta et al. Curr. Microbiol. 44:323, 2002. (3) B. M. Pryor and T. J. Michailides. Phytopathology 92:406, 2002. (4) E. G. Simmons. CBS Biodiv. Series 6:775, 2007.
    Matched MeSH terms: Photoperiod
  20. The influence of light intensity and photoperiod on the growth and lipid content of microalgae Nannochloropsis sp
    Wahidin S, Idris A, Shaleh SR
    Bioresour Technol, 2013 Feb;129:7-11.
    PMID: 23232218 DOI: 10.1016/j.biortech.2012.11.032
    Illumination factors such as length of photoperiod and intensity can affect growth of microalgae and lipid content. In order to optimize microalgal growth in mass culture system and lipid content, the effects of light intensity and photoperiod cycle on the growth of the marine microalgae, Nannochloropsis sp. were studied in batch culture. Nannochloropsis sp. was grown aseptically for 9 days at three different light intensities (50, 100 and 200 μmol m(-2) s(-1)) and three different photoperiod cycles (24:0, 18:06 and 12:12 h light:dark) at 23 °C cultivation temperature. Under the light intensity of 100 μmol m(-2) s(-1) and photoperiod of 18 h light: 6 h dark cycle, Nannochloropsis sp. was found to grow favorably with a maximum cell concentration of 6.5×10(7) cells mL(-1), which corresponds to the growth rate of 0.339 d(-1) after 8 day cultivation and the lipid content was found to be 31.3%.
    Matched MeSH terms: Photoperiod*
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