scholarly journals Ideal culture conditions for Dicyma pulvinata conidia mass production

2009 ◽  
Vol 44 (10) ◽  
pp. 1232-1238 ◽  
Author(s):  
Débora Ferreira Melo ◽  
Sueli Corrêa Marques de Mello
Keyword(s):  
Mass Production ◽  
Continuous Light ◽  
Culture Conditions ◽  
Block Designs ◽  
Complete Darkness ◽  
Continuous Darkness ◽  
Parboiled Rice ◽  
Light Regimes ◽  
Light Darkness ◽  
Set Up

The objective of this work was to set up ideal conditions for conidia mass production of Dicyma pulvinata. Four isolates were compared in terms of their growth and conidia production on various substrates (grains of parboiled rice, common rice, maize and wheat, besides chipped maize and rice husk), temperatures (19, 22, 25, 28 and 31ºC), growth containers (aluminum trays, polypropylene bags and Erlenmeyers) and light regimes (continuous darkness, 6 and 12 hours of light/darkness, and continuous light). Temperature effects on conidia germination capacity were also evaluated. The experiments were done in randomized complete block designs, in factorial arrangements (isolates x treatments - substrates, containers, temperatures and light regimes), with four replicates. In general, parboiled rice and polypropylene bags provided the best development of the fungus. Complete darkness and 6 hours of light increased mycelial growth, whereas continuous light favored sporulation. All tested temperatures favored the cultures of the fungus, except 31ºC. Temperatures between 19 and 25ºC ensure spore germination of more than 76%.

The Daily Rhythm of Activity of the Cockroach, Blatta Orientalis L

1940 ◽  
Vol 17 (3) ◽  
pp. 267-277 ◽  
Author(s):  
D. L. GUNN
Keyword(s):  
Activity Rhythm ◽  
Continuous Light ◽  
Locomotory Activity ◽  
Continuous Darkness ◽  
Daily Cycle ◽  
Blatta Orientalis ◽  
Physical Stimuli ◽  
Inactive Phase ◽  
Set Up ◽  
Main Activity

1. In an aktograph at 25.5°C., at upwards of 75% relative humidity and with food present, the average locomotory activity of the cockroach per day does not depend on whether there is continuous light for weeks, or continuous darkness, or a daily alternation of light and darkness. 2. When temperature and humidity do not vary during the day and other factors are kept as constant as possible, the cockroach's activity can be largely concentrated into any desired half of the day, simply by suitably adjusting the time of onset of the half-day's darkness. A rhythm can thus be set up, so that the main activity occurs at the same hours each day. 3. This activity rhythm persists for some days in continuous light or continuous darkness, but eventually activity becomes much more evenly spread over the whole day, leaving only a slight residual rhythm which is unrelated to the previous conspicuous one. A new conspicuous rhythm can then be started at once by alternation of light and darkness. 4. There are indications that animal responses to physical stimuli may depend to a considerable extent on whether the animal is in the active or the inactive phase of its daily cycle. A method is suggested for making it possible to study the nocturnal phase during the daytime.

scholarly journals Life after Harvest: Circadian Regulation in Photosynthetic Pigments of Rocket Leaves during Supermarket Storage Affects the Nutritional Quality

Nutrients ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1519
Author(s):  
Lorena Ruiz de Larrinaga ◽  
Victor Resco de Dios ◽  
Dmitri Fabrikov ◽  
José Luis Guil-Guerrero ◽  
José María Becerril ◽  
...  
Keyword(s):  
Nutritional Quality ◽  
Continuous Light ◽  
Continuous Darkness ◽  
Endogenous Rhythms ◽  
Research Perspective ◽  
Nutrition Science ◽  
Light Darkness ◽  
New Research ◽  
Quality Assessments ◽  
First Time

Vegetables, once harvested and stored on supermarket shelves, continue to perform biochemical adjustments due to their modular nature and their ability to retain physiological autonomy. They can live after being harvested. In particular, the content of some essential nutraceuticals, such as carotenoids, can be altered in response to environmental or internal stimuli. Therefore, in the present study, we wondered whether endogenous rhythms continue to operate in commercial vegetables and if so, whether vegetable nutritional quality could be altered by such cycles. Our experimental model consisted of rocket leaves entrained under light/darkness cycles of 12/12 h over 3 days, and then we examined free-run oscillations for 2 days under continuous light or continuous darkness, which led to chlorophyll and carotenoid oscillations in both constant conditions. Given the importance of preserving food quality, the existence of such internal rhythms during continuous conditions may open new research perspective in nutrition science. However, while chromatographic techniques employed to determine pigment composition are accurate, they are also time-consuming and expensive. Here we propose for the first time an alternative method to estimate pigment content and the nutritional quality by the use of non-destructive and in situ optical techniques. These results are promising for nutritional quality assessments.

scholarly journals Enhanced Light-Induced Biosynthesis of Fatty Acids Suitable for Biodiesel Production by the Yellow-Green Alga Eustigmatos magnus

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6098
Author(s):  
Izabela Krzemińska ◽  
Artur Nosalewicz ◽  
Emilia Reszczyńska ◽  
Barbara Pawlik-Skowrońska
Keyword(s):  
Fatty Acids ◽  
Light Intensity ◽  
High Intensity ◽  
Continuous Light ◽  
Culture Conditions ◽  
Biodiesel Production ◽  
Bioactive Molecules ◽  
Biomass Composition ◽  
Continuous Illumination ◽  
Light Regimes

Optimization of the fatty acid profile in microalgae is one of the key strategies for obtaining valuable products and sustainable biofuels. Light intensity and light regimes exert an impact on the growth and metabolic process in microalgae. The objective of the present investigations was to assess the effect of light intensity and continuous light vs. photoperiod conditions on the growth and changes in the biomass composition in Eustigmatos magnus, with a focus on bioactive molecules such as lipids and fatty acids. The highest daily productivity of Eustigmatos magnus biomass and lipid yields were detected at continuous illumination and at the highest intensity of light. The results show that the content and composition of fatty acids was influenced by the culture conditions. The biomass of Eustigmatos magnus contained the highest concentrations of polyunsaturated fatty acids in the pphotoperiod conditions with the highest light intensity. This study shows that Eustigmatos magnus has a capacity for the accumulation of palmitoleic acid. A high intensity of continuous light improves the profile of fatty acids in Eustigmatos magnus, which can be suitable for biodiesel applications. At the high intensity of continuous light, Eustigmatos magnus lipids are characterized by high content of oleic acids and low content of saturated and monounsaturated acids.

scholarly journals Effect of different constant and alternative temperatures and light situations on germination behavior of two Purslane (Protulaca oleracea L.) populations

2016 ◽  
Vol 4 (2) ◽  
pp. 13-21
Author(s):  
F Golzardi ◽  
Y Vaziritabar ◽  
K Sadat Asilan ◽  
M Ashraf ◽  
SZ Ebadi ◽  
...  
Keyword(s):  
Germination Rate ◽  
Germination Percentage ◽  
Shoot Length ◽  
Constant Darkness ◽  
Optimum Temperature ◽  
Fresh Weight ◽  
Continuous Darkness ◽  
Light Regimes ◽  
Light Darkness ◽  
Alternating Temperature

This study was carried out to investigate the germination behavior of two purslane populations (Karaj and Ahvaz), the effect of constant temperatures under two light regimes (12 hrs light/dark and continuous dark), alternative temperatures (day/night) and the lighting/darkness periods on purslane germination. The study was conducted in a randomized complete blocks design with four replications. The results showed that the highest percentage and germination rate in constant temperatures under two light regimes in Karaj mass (continuous darkness) and Ahvaz (12/12 hrs light/darkness), respectively at 25 and 30 °C (Optimum temperature) was observed. Purslane percentage and germination rate changes in alternating temperature (day/night) showed, the maximum values of both masses achieved at 30/20°C alternative temperature. According to result, by getting away from the optimum temperature, the germination percentage and its rate tends to have a descending process in both thermal experiments (alternative and constant temperature tests). Also the effect of different darkness/light periods on purslane percentage and germination rate showed, at (0/24) constant darkness treatment these traits got to the lowest point. The highest percentage and germination rates in Karaj and Ahvaz populations, respectively observed at 0/24, 12/12, 10/14 and 8/16 treatments; which had no statistical difference. Radicle length, shoot length and fresh weight of seedlings in both populations at constant temperatures under both light regimes at 20 to 30 °C and alternative temperatures (light/dark) at 30/20 °C had the highest values.International Journal of Natural Sciences (2014), 4(2) 13-21

Control of nitrogen assimilation in Stichococcus bacillaris by growth conditions

1987 ◽  
Vol 65 (3) ◽  
pp. 432-437 ◽  
Author(s):  
Iftikhar Ahmad ◽  
Johan A. Hellebust
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Assimilation ◽  
Continuous Light ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Dark Cycle ◽  
Continuous Darkness ◽  
Cell Carbon ◽  
Stichococcus Bacillaris ◽  
Mixotrophic Conditions

Stichococcus bacillaris Naeg. (Chlorophyceae) grown on a 12 h light: 12 h dark cycle divides synchronously under photoautotrophic conditions and essentially nonsynchronously under mixotrophic conditions. Photoassimilation of carbon under photoautotrophic conditions was followed by a decline in cell carbon content during the dark period, whereas under mixotrophic conditions cell carbon increased throughout the light–dark cycle. The rates of nitrogen assimilation by cultures grown on either nitrate or ammonium declined sharply during the dark, and these declines were most pronounced under photoautotrophic conditions. Photoautotrophic cells synthesized glutamine synthetase and NADPH – glutamate dehydrogenase (GDH) exclusively in the light, whereas in mixotrophic cells about 20% of the total synthesis of these enzymes during one light–dark cycle occurred in the dark. NADH–GDH was synthesized almost continuously over the entire light–dark cycle. In the dark, both under photoautotrophic and mixotrophic conditions, the alga contained more than 50% of glutamine synthetase in an inactive form, which was reactivated in vitro in the presence of mercaptoethanol and in vivo after returning the cultures to the light. The thermal stability of glutamine synthetase activity was less in light-harvested cells than in dark-harvested cells. The inactivation of glutamine synthetase did not occur in cultures growing either heterotrophically in continuous darkness or photoautotrophically in continuous light. This enzyme appears to be under thiol control only in cells grown under alternating light–dark conditions, irrespective of whether this light regime results in synchronous cell division or not.

Light-induced suppression of the rat circadian system

1995 ◽  
Vol 268 (5) ◽  
pp. R1111-R1116 ◽  
Author(s):  
P. Depres-Brummer ◽  
F. Levi ◽  
G. Metzger ◽  
Y. Touitou
Keyword(s):  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Prolonged Exposure ◽  
Light Exposure ◽  
Continuous Light ◽  
Circadian System ◽  
Short Exposure ◽  
Complete Suppression ◽  
Continuous Darkness

In a constant environment, circadian rhythms persist with slightly altered period lengths. Results of studies with continuous light exposure are less clear, because of short exposure durations and single-variable monitoring. This study sought to characterize properties of the oscillator(s) controlling the rat's circadian system by monitoring both body temperature and locomotor activity. We observed that prolonged exposure of male Sprague-Dawley rats to continuous light (LL) systematically induced complete suppression of body temperature and locomotor activity circadian rhythms and their replacement by ultradian rhythms. This was preceded by a transient loss of coupling between both functions. Continuous darkness (DD) restored circadian synchronization of temperature and activity circadian rhythms within 1 wk. The absence of circadian rhythms in LL coincided with a mean sixfold decrease in plasma melatonin and a marked dampening but no abolition of its circadian rhythmicity. Restoration of temperature and activity circadian rhythms in DD was associated with normalization of melatonin rhythm. These results demonstrated a transient internal desynchronization of two simultaneously monitored functions in the rat and suggested the existence of two or more circadian oscillators. Such a hypothesis was further strengthened by the observation of a circadian rhythm in melatonin, despite complete suppression of body temperature and locomotor activity rhythms. This rat model should be useful for investigating the physiology of the circadian timing system as well as to identify agents and schedules having specific pharmacological actions on this system.

scholarly journals Effect of culture medium light and air circulation on sporulation of Neonectria ditissima

2014 ◽  
Vol 67 ◽  
pp. 123-132 ◽  
Author(s):  
R.W.A. Scheper ◽  
B.M. Fisher ◽  
N.T. Amponsah ◽  
M. Walter
Keyword(s):  
Culture Media ◽  
Ultra Violet ◽  
Fluorescent Light ◽  
Malt Extract ◽  
Causal Organism ◽  
Light Regimes ◽  
Large Numbers ◽  
Light Darkness ◽  
Series Of Experiments ◽  
Air Circulation

In culture most isolates of Neonectria ditissima the causal organism of European canker do not produce conidia Those that do often produce singlecelled conidia rather than the typical multicelled conidia that are found in nature A series of experiments was conducted to determine the conditions needed for conidium production Four culture media (malt extract agar modified Matsushimas medium (MM) apple sap amended water agar (ASAWA) and water agar) five light regimes including darkness near ultra violet (NUV) light and white fluorescent light and three plate sealing patterns were tested Subculturing isolates producing large numbers of viable conidia of which 71 produced multicelled conidia Similarly under a white fluorescent light/darkness regime all isolates produced viable conidia on MM and ASAWA and 100 and 97 of the isolates produced multicelled conidia respectively

The role of photoperiod and temperature in the induction and termination of an arrested development in two species of freshwater cyclopia copepods

1971 ◽  
Vol 49 (6) ◽  
pp. 855-862 ◽  
Author(s):  
Nelson H. F. Watson ◽  
B. N. Smallman
Keyword(s):  
Continuous Light ◽  
Temporary Pond ◽  
Environmental Cues ◽  
Complete Darkness ◽  
Arrested Development ◽  
Short Day ◽  
Long Day ◽  
Critical Daylength ◽  
Ecological Implications

Daylength and temperature were shown to be environmental cues which interact to cause an arrest in development at the fourth copepodite instar of two cohabiting, temporary pond species of the genus Diacyclops; D. navus Herrick, and a second species of uncertain specific designation. The first species entered arrest under short-day conditions, the latter under long days. Arrest did not occur in rearings conducted in either continuous light or complete darkness. Cyclopids were sensitive to the photoperiodic stimulus only during the first copepodite instar. Temperature was shown to affect the critical daylength values associated with a transition from a long-day to a short-day response for each species.Similarities with insect diapause and the ecological implications of the response are discussed.

Optokinetic Responses of the Crab, Carcinus to a Single Moving Light

1966 ◽  
Vol 44 (2) ◽  
pp. 263-274
Author(s):  
G. A. HORRIDGE
Keyword(s):  
Eye Movements ◽  
Apparent Motion ◽  
Horizontal Plane ◽  
Continuous Light ◽  
Lower Percentage ◽  
Eye Position ◽  
Complete Darkness ◽  
Intermittent Light ◽  
Optokinetic Responses ◽  
Dark Room

1. A crab in an otherwise dark room will stabilize its eye position by reference to a single small light, so long as the illumination at the eye exceeds about 0.0003 lux. 2. The eye movements follow the movements of the light. 3. Responses to a light moving in a horizontal plane resemble those to a striped drum, but at lower percentage following. 4. Apparent motion is an effective stimulus; with intermittent light the response is reduced. If there is a period of complete darkness after the first light the subsequent movement, when the second light comes on, is slower for longer dark periods. 5. The crab learns, after some repetitions, to discriminate between a continuous light and an intermittent one, as shown by its eventually stabilizing them at different points on its retina.

Circadian rhythm and response to light of extracellular glutamate and aspartate in rat suprachiasmatic nucleus

1996 ◽  
Vol 271 (3) ◽  
pp. R579-R585 ◽  
Author(s):  
S. Honma ◽  
Y. Katsuno ◽  
K. Shinohara ◽  
H. Abe ◽  
K. Honma
Keyword(s):  
Circadian Rhythm ◽  
Suprachiasmatic Nucleus ◽  
Light Pulse ◽  
Continuous Light ◽  
In Vivo Microdialysis ◽  
Dark Phase ◽  
Dark Cycle ◽  
Complete Darkness ◽  
Endogenous Circadian Rhythm

Extracellular concentrations of glutamate and aspartate were measured in the vicinity of rat suprachiasmatic nucleus (SCN) by means of in vivo microdialysis. The concentrations of both excitatory amino acids (EAAs) were higher during the dark phase than during the light under the light-dark cycle, showing pulsatile fluctuations throughout the day. When rats were released into the complete darkness, the 24-h pattern in the aspartate continued for at least one cycle, whereas that in the glutamate disappeared. The nocturnal increases in the EAA levels were not due to the increase of locomotor activity during the nighttime, because the 24-h rhythms were also detected in animals under urethan anesthesia. The patterns of extracellular EAA levels were changed when rats were released into the continuous light. Circadian rhythm was not detected in the glutamate, whereas the 24-h pattern was maintained in the aspartate with the levels increased to various extents. A 30-min light pulse given either at zeitgber time (ZT) 1 or ZT 13 elevated the EAA levels during the latter half of the light pulse, except glutamate by a pulse at ZT 1. The extracellular EAA levels in the vicinity of the rat SCN showed the circadian rhythm with a nocturnal peak and increased in response to the continuous light and a brief light pulse. The aspartate level is considered to be regulated by the endogenous circadian rhythm, but the glutamate levels seems to be modified by the light-dark cycle.

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