scholarly journals When and where to hatch? Red-eyed treefrog embryos use light cues in two contexts

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6018 ◽  
Author(s):  
Brandon A. Güell ◽  
Karen M. Warkentin
Keyword(s):  
Spatial Orientation ◽  
Continuous Light ◽  
Open Water ◽  
Continuous Darkness ◽  
Agalychnis Callidryas ◽  
Sensory Modalities ◽  
Natural Photoperiod ◽  
Role Of Light ◽  
Do So

Hatching timing is under strong selection and environmentally cued in many species. Embryos use multiple sensory modalities to inform hatching timing and many have spontaneous hatching patterns adaptively synchronized to natural cycles. Embryos can also adaptively shift their hatching timing in response to environmental cues indicating immediate threats or opportunities. Such cued shifts in hatching are widespread among amphibians; however, we know little about what, if anything, regulates their spontaneous hatching. Moreover, in addition to selection on hatching timing, embryos may experience benefits or suffer costs due to the spatial orientation of hatching. Amphibian eggs generally lack internal constraints on hatching direction but embryos might, nonetheless, use external cues to inform hatching orientation. The terrestrial embryos of red-eyed treefrogs, Agalychnis callidryas, hatch rapidly and prematurely in response to vibrational cues in egg-predator attacks and hypoxia if flooded. Here we examined A. callidryas’ use of light cues in hatching timing and orientation. To assess patterns of spontaneous hatching and the role of light cues in their diel timing, we recorded hatching times for siblings distributed across three light environments: continuous light, continuous dark, and a 12L:12D photoperiod. Under a natural photoperiod, embryos showed a clear diel pattern of synchronous hatching shortly after nightfall. Hatching was desynchronized in both continuous light and continuous darkness. It was also delayed by continuous light, but not accelerated by continuous dark, suggesting the onset of dark serves as a hatching cue. We examined hatching orientation and light as a potential directional cue for flooded embryos. Embryos flooded in their clutches almost always hatched toward open water, whereas individual eggs flooded in glass cups often failed to do so, suggesting the natural context provides a directional cue. To test if flooded embryos orient hatching toward light, we placed individual eggs in tubes with one end illuminated and the other dark, then flooded them and recorded hatching direction. Most embryos hatched toward the light, suggesting they use light as a directional cue. Our results support that A. callidryas embryos use light cues to inform both when and where to hatch. Both the spatial orientation of hatching and the timing of spontaneous hatching may affect fitness and be informed by cues in a broader range of species than is currently appreciated.

scholarly journals When and where to hatch? Red-eyed treefrog embryos use light cues in two contexts

2018 ◽  
Author(s):  
Brandon André Güell ◽  
Karen M Warkentin
Keyword(s):  
Spatial Orientation ◽  
Continuous Light ◽  
Open Water ◽  
Continuous Darkness ◽  
Agalychnis Callidryas ◽  
Sensory Modalities ◽  
Natural Photoperiod ◽  
Role Of Light ◽  
Do So

Hatching timing is under strong selection and environmentally cued in many species. Embryos use multiple sensory modalities to inform hatching timing and many have spontaneous hatching patterns adaptively synchronized to natural cycles. Embryos can also adaptively shift their hatching timing in response to environmental cues indicating immediate threats or opportunities. Such cued shifts in hatching are widespread among amphibians; however, we know little about what, if anything, regulates their spontaneous hatching. Moreover, in addition to selection on hatching timing, embryos may experience benefits or suffer costs due to the spatial orientation of hatching. Amphibian eggs generally lack internal constraints on hatching direction but embryos might, nonetheless, use external cues to inform hatching orientation. The terrestrial embryos of red-eyed treefrogs, Agalychnis callidryas, hatch rapidly and prematurely in response to vibrational cues in egg-predator attacks and hypoxia if flooded. Here we examined A. callidryas’ use of light cues in hatching timing and orientation. To assess patterns of spontaneous hatching and the role of light cues in their diel timing, we recorded hatching times for siblings distributed across three light environments: continuous light, continuous dark, and a 12L:12D photoperiod. Under a natural photoperiod, embryos showed a clear diel pattern of synchronous hatching shortly after nightfall. Hatching was desynchronized in both continuous light and continuous darkness. It was also delayed by continuous light, but not accelerated by continuous dark, suggesting the onset of dark serves as a hatching cue. We examined hatching orientation and light as a potential directional cue for flooded embryos. Embryos flooded in their clutches almost always hatched toward open water, whereas individual eggs flooded in glass cups often failed to do so, suggesting the natural context provides a directional cue. To test if flooded embryos orient hatching toward light, we placed individual eggs in tubes with one end illuminated and the other dark, then flooded them and recorded hatching direction. Most embryos hatched toward the light, suggesting they use light as a directional cue. Our results support that A. callidryas embryos use light cues to inform both when and where to hatch. Both the spatial orientation of hatching and the timing of spontaneous hatching may affect fitness and be informed by cues in a broader range of species than is currently appreciated.

scholarly journals When and where to hatch? Red-eyed treefrog embryos use light cues in two contexts

2018 ◽  
Author(s):  
Brandon André Güell ◽  
Karen M Warkentin
Keyword(s):  
Spatial Orientation ◽  
Continuous Light ◽  
Open Water ◽  
Continuous Darkness ◽  
Agalychnis Callidryas ◽  
Sensory Modalities ◽  
Natural Photoperiod ◽  
Role Of Light ◽  
Do So

Hatching timing is under strong selection and environmentally cued in many species. Embryos use multiple sensory modalities to inform hatching timing and many have spontaneous hatching patterns adaptively synchronized to natural cycles. Embryos can also adaptively shift their hatching timing in response to environmental cues indicating immediate threats or opportunities. Such cued shifts in hatching are widespread among amphibians; however, we know little about what, if anything, regulates their spontaneous hatching. Moreover, in addition to selection on hatching timing, embryos may experience benefits or suffer costs due to the spatial orientation of hatching. Amphibian eggs generally lack internal constraints on hatching direction but embryos might, nonetheless, use external cues to inform hatching orientation. The terrestrial embryos of red-eyed treefrogs, Agalychnis callidryas, hatch rapidly and prematurely in response to vibrational cues in egg-predator attacks and hypoxia if flooded. Here we examined A. callidryas’ use of light cues in hatching timing and orientation. To assess patterns of spontaneous hatching and the role of light cues in their diel timing, we recorded hatching times for siblings distributed across three light environments: continuous light, continuous dark, and a 12L:12D photoperiod. Under a natural photoperiod, embryos showed a clear diel pattern of synchronous hatching shortly after nightfall. Hatching was desynchronized in both continuous light and continuous darkness. It was also delayed by continuous light, but not accelerated by continuous dark, suggesting the onset of dark serves as a hatching cue. We examined hatching orientation and light as a potential directional cue for flooded embryos. Embryos flooded in their clutches almost always hatched toward open water, whereas individual eggs flooded in glass cups often failed to do so, suggesting the natural context provides a directional cue. To test if flooded embryos orient hatching toward light, we placed individual eggs in tubes with one end illuminated and the other dark, then flooded them and recorded hatching direction. Most embryos hatched toward the light, suggesting they use light as a directional cue. Our results support that A. callidryas embryos use light cues to inform both when and where to hatch. Both the spatial orientation of hatching and the timing of spontaneous hatching may affect fitness and be informed by cues in a broader range of species than is currently appreciated.

scholarly journals Tambaqui growth and survival when exposed to different photoperiods

2006 ◽  
Vol 36 (3) ◽  
pp. 381-384 ◽  
Author(s):  
Paulo Henrique Rocha Aride ◽  
Rodrigo Roubach ◽  
Sérgio Ricardo Nozawa ◽  
Adalberto Luís Val
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Continuous Light ◽  
Control Fish ◽  
Continuous Darkness ◽  
Growth And Survival ◽  
Colossoma Macropomum ◽  
Fish Weight ◽  
Natural Photoperiod

The use of different photoperiods (light) were investigated during tambaqui (Colossoma macropomum) juvenile growth under captivity. Light intensity tested was: continuous dark (24hrs without light), natural photoperiod simulation (10hrs of light and 14hrs without light) and continuous light (24 with light). No mortality was recorded among treatments. Significant differences was observed after 50 days of experiment among mean fish weight, fish kept under a continuous darkness showed a better specific growth rate (6.02%) when compared to control fish (natural photo period, 3.67%). Fish exposed to continuous light presented the lowest mean specific growth rate (2.04%). It is possible to improve tambaqui juvenile weight gain performance when kept under continuous darkness.

Controls on bud activation and tiller initiation in C3 and C4 tallgrass prairie grasses: the role of light and nitrogen

Botany ◽  
2012 ◽  
Vol 90 (12) ◽  
pp. 1221-1228 ◽  
Author(s):  
Melinda M. Williamson ◽  
Gail W.T. Wilson ◽  
David C. Hartnett
Keyword(s):  
Tallgrass Prairie ◽  
Spectral Composition ◽  
Integrated Model ◽  
Perennial Grasses ◽  
Continuous Darkness ◽  
Nitrogen Concentrations ◽  
Grazing Intensities ◽  
Bud Banks ◽  
Role Of Light

Population dynamics of perennial grasses in tallgrass prairie ecosystems are strongly influenced by vegetative outgrowth from their belowground bud banks. We examined the role of light and nitrogen in regulating tiller initiation and tested an integrated model of controls on bud dormancy and activation in several C3 and C4 grasses. In addition, we assessed the interaction of nitrogen and light quantity and red – far red spectral composition on tiller initiation. Belowground perennating organs of three C3 and three C4 species were grown under full light or dark conditions, amended with one of four nitrogen concentrations (0 to 350 ppm N). Dormant buds were also subjected to full light under different spectral compositions or to continuous darkness. Our results among C3 grasses support the integrated model as light and nitrogen played important and interacting roles in the regulation of bud banks. However, differences in responses among C4 grasses and a lack of light × nitrogen interactions suggest that an alternative model may be necessary for this functional group. Our results provide predictions of responses to nitrogen enrichment or light imitations in prairie ecosystems due to interacting disturbances such as reduction in fire frequencies, alterations in grazing intensities, or climate change.

scholarly journals Influence of the light factor on the course of the cell cycle in the successive generations of the antheridial filaments of Chara vulgaris L.

2015 ◽  
Vol 46 (1) ◽  
pp. 31-45 ◽  
Author(s):  
J. Maszewski
Keyword(s):  
Cell Cycle ◽  
Hormonal Regulation ◽  
Continuous Light ◽  
Continuous Illumination ◽  
Chara Vulgaris ◽  
Inhibition Of Growth ◽  
Successive Generations ◽  
Role Of Light ◽  
Kinetics Of

The exposure to continuous light causes a rise of the mitotic index in the successive generations of the antheridial filaments of <i>Chara vulgaris</i>, whereas culture in darkness leads to a considerable depression of mitosis, and if prolonged, to its complete cessation. Light reverses the effect of the depression of mitosis caused by darkness: in the 16-, and 32-cell generations mitotic activity reappeares as early as after 3 h, but in the 2-, 4-, and 8-cell generations only after 18 h. The size of the cells in the antheridial filaments of plants exposed to continuous illumination is larger as compared with the control material. After being kept in darkness the cells become smaller. The analysis of the size of the latter suggests the inhibition of growth in initial and final periods of interphase. In all generations continuous light reduces the duration of the cell cycle while darkness protracts it. The duration of S phase is similar in all generations of antheridial filaments (ca. 16 h) and is not modified by the light conditions. Thus, the light factor seems to interfere mainly with G2 phase, and its role in the regulation of the cell cycle is correlated with the duration of this phase. The role of light in the kinetics of the cell cycle of the particular generations of antheridial filaments in Chara is discussed in the aspect of the nutritional requirements of cells, hormonal regulation and phytochrome.

scholarly journals Role of Light and Malate in the Decreased Sensitivity of cms-T Cytoplasm Maize Leaves to Bipolaris maydis Race T Toxin

1998 ◽  
Vol 88 (6) ◽  
pp. 556-562 ◽  
Author(s):  
M. O. Garraway ◽  
D.-S. Park ◽  
J. D. Beltran
Keyword(s):  
Malic Acid ◽  
Electrolyte Leakage ◽  
Continuous Light ◽  
Bathing Solution ◽  
Male Sterile ◽  
Bipolaris Maydis ◽  
Data Points ◽  
Leaf Segments ◽  
Role Of Light

Leaf segments from Texas male sterile (cms-T) cytoplasm maize isolines exposed to light (50 μM s-1 m-2) for 8 h or more before or after being infiltrated with the Bipolaris maydis race T toxin (T-toxin) leaked significantly less electrolytes when immersed in distilled water (DW) for 24 to 48 h than did dark-treated leaf segments. No comparable effect of light on toxin-induced electrolyte leakage was observed with normal (N) cytoplasm isolines. Toxin-treated cms-T leaf segments incubated in DW for three consecutive 12-h periods of alternating light and dark showed significantly greater electrolyte leakage than leaf segments incubated in continuous light for 36 h and significantly less leakage than segments incubated in continuous dark for 36 h.Exposure of cms-T, but not N, cytoplasm leaves to 25 or 50 μM malic acid decreased their sensitivity to T-toxin in the dark to a level similar to that observed when leaves were incubated in the light without malic acid. The potency of T-toxin appeared to be unaffected by its exposure to light. The loss of electrolytes from T-toxin-treated cms-T cytoplasm leaf segments was at approximately the level seen with light or malate when 25 μM H2O2 was added to the DW bathing solution. Evaluation of the data points to the possibility that H2O2 might be involved with the altered sensitivity of cms-T cytoplasm leaves to T-toxin caused by either light or malate.

scholarly journals Dusky Grouper Epinephelus marginatus Growth and Survival When Exposed to Different Photoperiods

Fishes ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 31
Author(s):  
Paulo Henrique R. Aride ◽  
Maria Fernanda S. Gomes ◽  
Darlan G. Azevedo ◽  
Gilson R. Sangali ◽  
Ana Cláudia F. Silva ◽  
...  
Keyword(s):  
Continuous Light ◽  
Mineral Matter ◽  
Total Biomass ◽  
Continuous Darkness ◽  
Growth And Survival ◽  
Final Weight ◽  
Natural Photoperiod ◽  
Key Factor ◽  
Current Production ◽  
Dusky Grouper

Photoperiod is considered an environmental factor that influences reproduction and the growth processes of fish throughout the year. In the present study, we subjected dusky grouper Epinephelus marginatus to different photoperiods in order to evaluate growth and survival. Juvenile dusky grouper were randomly distributed in twelve 100 L tanks containing four fish per aquarium. The fish were exposed to continuous light, normal photoperiod or continuous darkness for 50 days. Fish were fed 3% of their total biomass, twice a day, and the diet consisted of ground commercial dry pellets (42% crude protein, 12% humidity, 9% ether extract, 15% mineral matter, 4% crude fiber, 3.5% calcium and 3% vitamin C, in accordance with the manufacturer’s instructions). There was no mortality during the experiment. After 50 days, the best performance was found for exposure to continuous light (24 h artificial light). The final weight of the fish reared under continuous light was significantly higher than that of the fish exposed to continuous darkness. The specific growth rate of the fish exposed to continuous light was significantly higher than that of the fish exposed to the natural photoperiod and to continuous darkness. Modifications to the photoperiod can be a key factor in increasing the efficacy of current production and the improvement of current aquaculture protocols.

scholarly journals The Role of Light during Phlox drummondii Hook. Seed Germination

HortScience ◽  
1993 ◽  
Vol 28 (8) ◽  
pp. 786-788
Author(s):  
William J. Carpenter ◽  
Eric R. Ostmark ◽  
John A. Cornell
Keyword(s):  
Seed Germination ◽  
Light Level ◽  
Total Darkness ◽  
Regression Equations ◽  
Continuous Darkness ◽  
Light Duration ◽  
Radicle Emergence ◽  
Phlox Drummondii ◽  
Role Of Light

The role of light on phlox germination and radicle emergence was studied. Neither light level nor duration affected total germination (G) percentages, which ranged from 93%. to 98%. Increasing light level and lengthening light duration delayed achieving 50% of final germination (T50) and increased the span in days between 10% and 90% germination (T90 - T10). Increasing light duration from 0 to 24 hours during germination at 0.15 μmol·s-1·m-2 progressively increased T50 from 3.5 to 7.1 days and T90 - T10 from 2.6 to 13.1 days. Similarly, lengthening light duration from 0 to 24 hours at 1.5 μmol·s-1·m-2 light increased T50 from 3.7 to 10.8 days and T90 - T10 from 2.8 to 13.4 days, whereas 15 μmol·s -1·m-2 increased T50 from 3.9 to 21.9 days and T90 - T10 from 2.9 to 29.2 days. Increasing the number of days in darkness from 0 to 6 decreased T50 from 14.8 to 4.3 days and T90 - T10 from 20.2 to 3.5 days. Increasing the number of days in light from O to 6 increased T50 from 4.0 to 8.9 days and T90 - T10 from 3.8 to 8.2 days. Estimated rates of decline or increase in T50 and T90 - T10 with each added day in darkness or light were measured by fitting regression equations. Seeds germinated in continuous darkness or in 24 or 48 hours of light followed by total darkness had similar G, T50, and T90 - T10. The results indicate that initial phlox seed germination was not affected by light, but that light inhibited radicle extension in later germination stages.

A Re-Appraisal of the Role of Blood Coagulation and Platelets in the Generalized Shwartzman Phenomenon

1966 ◽  
Vol 15 (03/04) ◽  
pp. 519-538 ◽  
Author(s):  
J Levin ◽  
E Beck
Keyword(s):  
Blood Coagulation ◽  
The State ◽  
Coagulation System ◽  
Renal Lesions ◽  
Intravascular Coagulation ◽  
Renal Glomeruli ◽  
Coagulation Mechanism ◽  
Shwartzman Phenomenon ◽  
Do So

SummaryThe role of intravascular coagulation in the production of the generalized Shwartzman phenomenon has been evaluated. The administration of endotoxin to animals prepared with Thorotrast results in activation of the coagulation mechanism with the resultant deposition of fibrinoid material in the renal glomeruli. Anticoagulation prevents alterations in the state of the coagulation system and inhibits development of the renal lesions. Platelets are not primarily involved. Platelet antiserum produces similar lesions in animals prepared with Thorotrast, but appears to do so in a manner which does not significantly involve intravascular coagulation.The production of adrenal cortical hemorrhage, comparable to that seen in the Waterhouse-Friderichsen syndrome, following the administration of endotoxin to animals that had previously received ACTH does not require intravascular coagulation and may not be a manifestation of the generalized Shwartzman phenomenon.

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