Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 17

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  darkness
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

A simple way to overcome the recalcitrance of the water fern Ceratopteris thalictroides (L.) Brongn. to cryopreservation

100%
Makowski D., Rybczynski J. J., Mikula A.
Acta Societatis Botanicorum Poloniae
|
2015
|
tom 84
|
nr 3
Ceratopteris thalictroides is a water fern very sensitive to both dehydration and low temperature. This study focuses on the cryopreservation of this species by encapsulation-dehydration technique, in particular on the effects of pre-culture step, alginate bead size and the physical conditions of culture on the cryopreservation efficiency. Encapsulated and non-pre-cultured gametophytes did not survive cooling with liquid nitrogen. When cryopreservation was preceded by a 2-week period of pre-culture, regrowth reached 42.1%. Reduction in the size of the alginate bead, and culture in total darkness resulted in improved gametophyte regrowth capacity (75.5% or 81.7%, respectively). The best results (91.3%) were obtained when all factors tested occurred simultaneously. The gametophytes recovered very quickly and sporophytes were formed within 4 weeks after rewarming. These simple improvements can be used, not only for the cryopreservation of gametophytes in cryptogams but also for some recalcitrant species of seed plants.
2

The relationship between mitochondria function and circadian clock in peripheral oscillators

84%
Kazmierczak A., Schmitt K., Grimm A., Strosznajder J. B., Eckert A.
Acta Neurobiologiae Experimentalis
|
2013
|
tom 73
|
nr 1
Circadian rhythms govern a wide variety of physical, behavioral and metabolic changes that follow a roughly 24-hour cycle, responding primarily to light and darkness in an organism’s environment. These are controlled by the circadian clock mechanism, where rhythm-generating mechanism is encoded by a transcription-translation feedback loop. Numerous studies have pointed to a cyclic relationship wherein the rhythm impacts metabolic activity and metabolism feeds back to impinge upon the rhythm. Mitochondria play a pivotal role in regulating cellular energy and were shown to be strategically positioned at the intersection between circadian rhythm and cell metabolism. Nevertheless little is known about their function in controlling the circadian rhythm. In our study, we investigated the involvement of circadian clock in mitochondrial function as well as mitochondria-dependent regulation of circadian clock. The study was carried out in primary human fibroblasts, an already established model to investigate molecular clock mechanisms in vitro. We have found that mitochondria activity as well as network activities showed rhythmic changes within 24 hours. Circadian pattern was detected for mitochondrial ROS including superoxide anion production. A significant 24-hour oscillation was found for cellular redox state. Furthermore, mitochondrial ATP levels were rhythmic and the maximum of ATP production paralleled the peak of mitochondrial ROS level and the mitochondrial network formation. Circadian rhythm was also detected for calcium ions concentration. Increase of ATP synthesis as well as changes in calcium and ROS level activated AMP-dependent protein kinase (AMPK). We have found that in primary human fibroblasts AMPK protein level and activity fluctuate in an antiphase relationship with rhythmic ATP production. Summarizing, our data provide the evidence for circadian regulation of mitochondrial dynamics and suggest that changes of mitochondrial activity may directly influence cellular clock. Supported by grants from Sciex 10. 258 to A.K. as well as Swiss National foundation (SNF No 310030_122572) and Synapsis Foundation to A.E
3
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Influence of lead (Pb2plus) on chloroplast distribution patterns in Lemna trisulca L. mesophyll cells in darkness

84%
Samardakiewicz S., Suski S., Gabrys H., Wozny A.
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
|
2013
|
tom 94
|
nr 3
4

The effect of soil tillage in darkness on weed infestation

84%
Podlesny J., Podlesna A.
Bibliotheca Fragmenta Agronomica
|
1997
|
tom 2B
5

Circadian rhythm in the subcommissural organ of the frog Rana kl. esculenta under constant darkness

84%
Sura P.
Acta Biologica Cracoviensia. Series Zoologia
|
2000
|
tom 42
6
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

The effect of growth regulators and culture conditions on the callus induction in tomato Lycopersicon sp.

84%
Rzepka-Plevnes D., Kulpa D., Grabiec M., Kowalczys K., Kurek J.
Acta Scientiarum Polonorum. Hortorum Cultus
|
2006
|
tom 05
|
nr 2
Effect of auxins: (NAA, IAA), cytokinin BAP and culture conditions (light, darkness) on callus induction in cotyledons of tomato cultivar ‘Maskotka’ and the wild form of Lycopersicon peruvianum was investigated. Callus was obtained in all experimental combinations, except of the culture with L. peruvianum on the medium with 1.0 mg⋅dm⁻³ of IAA. Callus weight, colour and structure depended on the tomato genotypes and experimental conditions. Best medium for the culture of tomato cultivar ‘Maskotka’ and the wild form L. peruvianum proved to be MS medium supplemented with 2.0 mg⋅dm⁻³ of IAA and 1.0mg⋅dm⁻³ of BAP.
7

Chronophysiologic analysis of the circadian locomotor activity of mice and the effect of neuropeptide Y administration

84%
Lach H., Srebro Z.
Acta Biologica Cracoviensia. Series Zoologia
|
1996
|
tom 38
8

Influence of light and darkness on the behaviour of Dermanyssus gallinae on layer farms

67%
Sokol R., Szkamelski A., Barski D.
Polish Journal of Veterinary Sciences
|
2008
|
tom 11
|
nr 1
71-73
The behaviour of Dernianyssus gallinae was investigated on two layer farms where two different light programs were introduced in the 40th week of hen life. In layer house No. 1, light was applied continuously for 16 hours during the day, while layer house No. 2 was subjected to 4 hours of light and 2 hours of darkness applied alternately during the day. To monitor the level of red mite infestation, 30 tube traps were placed in every layer house corridor at a height of 1.5 m above the floor. In the first layer house, 280 Dermanyssus gallinae females, 50 nymph larvae and 198 eggs were found in 100 mg of tube trap material during 16 hours of the light phase, while during the 8-hour darkness phase, 1240 females, 70 nymph larvae and 110 eggs were collected. In the other layer house (with an alternating light phase of 4 hours and a darkness phase of 2 hours per day), 387 Dermanyssus gallinae females, 401 nymph larvae and 1060 eggs were found in trap tubes over the 8-hour dark phase, while 343 females, 202 nymph larvae and 1106 eggs were discovered over the 16-hour light phase.
9

Effect of nitrates and sucrose on the induction of nitrate reductase in etiolated seedling leaves from selected barley genotypes in darkness

67%
Gniazdowska-Skoczek H.
Acta Physiologiae Plantarum
|
1998
|
tom 20
|
nr 4
The parental genotypes, cv. Aramir and R567 line, as well as the selected DH lines C23, C47/1, C41 and C55, growing in darkness differed significantly in the level of NR activity in crude leaf extracts independently of nitrate concentration in the medium. The highest activity of the enzyme was found in the line C23. When plants grew on the medium with 0.5 mM KNO₃, NR activity in that genotype was almost 10-fold higher than in the parents and lines C41, C55 and also 3.5-fold higher than in the line C47/1. An increase of nitrate concentration in the medium to 10 mM caused a significant increase of NR activity in all the genotypes under study. In the line C23 this enzyme activity was only 20% lower than that found previously in the green leaves of that genotype in light. NR from the leaves of C23 and C41 lines was thermally unstable under in vitro conditions. This enzyme in the leaf extracts from the line C23 was characterized by a considerably lower unstability. The lines DH C23 and C41 growing in the dark on the medium with 0.5 mM KNO₃ did not differ in nitrate accumulation in leaves, whereas a larger nitrate content was found in the leaves of the line C41 when it grew on the medium with 10 mM KNO₃. Independently of nitrate concentration in the medium, leaves of the line C23 were found to have a higher sucrose content than those of the line C41. Excised, etiolated leaves of barley treated with 0.5 and 10 mM KNO₃ in dark under conditions favorable to transpiration had a low NR activity. Leaf treatment with a solution containing 10 mM KNO₃ + 0.2 M sucrose caused, on the average, a 13-fold increase of NR activity in comparison to leaves treated only with 10 mM KNO₃ and about a 6-fold increase of this enzyme in comparison to leaves treated with 0.5 mM KNO₃ + 0.2 M sucrose.
10

Chlorophyll a fluorescence kinetics and CO2 exchange rates in light and in darkness in leaves of tall fescue as affected by UV radiation

67%
Lukaszek M., Poskuta J. W.
Acta Physiologiae Plantarum
|
1996
|
tom 18
|
nr 4
11
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

The short-term cold storage effect on vase life of cut Hosta leaves

67%
Wachowicz M., Rabiza-Swider J., Skutnik E., Lukaszewska A.
Acta Scientiarum Polonorum. Hortorum Cultus
|
2007
|
tom 06
|
nr 2
The longevity of cut leaves in flower arrangements is an important commercial consideration in horticultural practices. Here we report on the effect of short-term cold storage, in combination with a cytokinin treatment, on the post harvest longevity of cut leaves of Hosta ‘Minima Glauca’ and Hosta ‘Golden Tiara’. Cut leaves were stored dry or wet in polyethylene bags for 2 or 4 days in darkness or in light at 6°C and then transferred to 20°C where their vase life was compared with those of freshly cut leaves. Storage length and method affected the vase life of detached leaves of both Hosta cultivars; however, reduced longevity of leaves in storage could not be attributed to a single parameter of the storage conditions. Pulse conditioning with a cytokinin benzyladenine was effective in prolonging vase life both in non stored and stored leaves, in the latter increasing it 2.5-fold as compared to untreated leaves. Practical implications are that cold storage can be successfully used for cut Hosta leaves but only in combination with a BA pretreatment.
12

Two-dimensional electrophoresis of thylakoid proteins from yellow lupin subjected to thermal and light stress

67%
Oczkowski M., Kalinowski A., Bartkowiak S., Augustyniak A.
Biological Bulletin of Poznań
|
1997
|
tom 34
13

Effects of light and darkness on cell deaths in damaged retinal ganglion cells of the carp retina

67%
Dezawa M., Mo X., Oshitari T., Takano M., Meyer-Rochow V. B., Sawada H., Eguchi E.
Acta Neurobiologiae Experimentalis
|
2001
|
tom 61
|
nr 2
14

Comparison of responses of bean, pea and rape plants to UV-B radiation in darkness and in light

67%
Skorska E.
Acta Physiologiae Plantarum
|
2000
|
tom 22
|
nr 2
15

The growth of internal volume in young antheridia of some Chara species in relation to changes in antheridial mucilage concentration during 3-day continuous darkness

59%
Gosek A.
Bulletin of the Polish Academy of Sciences. Biological Sciences
|
1994
|
tom 42
|
nr 3
16

Rhythm of sporulation within the section Penicillium clavigerum. III. Induction of growth and zonation rhythms in Penicillium isariiforme Stolk and Meyer 247.56

59%
Piskorz-Binczycka B.
Acta Biologica Cracoviensia. Series Botanica
|
1994
|
tom 36
In Penicilium isariiforme there occur two endogenous rhythms: the growth-“wave” rhythm and sporulation rhythm in the form of coremia-bearing zonations. The growth rhythm of wave type occurring in P. isariiforme in light and in darkness is an endogenous spontaneous rhythm, whereas the sporulation rhythm manifested by the formation of spore-bearing coremia zonations represents an analogue induced rhythm. For this rhythm to occur a light impulse is necessary. The growth-wave rhythm has a long period 120 h, the sporulation rhythm has a 30 h period. Asparagine seems to regulate the sporulation rhythm; but it does not exert any greater influence on the wave rhythm in cultures grown in light nor in darkness. An addition of asparagine shortened the period of first zonation by a few hours, and the successive sporulation periods followed within very short time. Inhibitors such as: avidin. chloramphenicol, cycloheximide and puromycine controlled the length of the period of the sporulation rhythm.
17

Ekspresja genu akwaporyny w siewkach Pharbitis nil Choisy w warunkach ciągłej ciemności

51%
Dabrowska G., Mordaka P., Prusinska J., Stawki K., Goc A.
Zeszyty Problemowe Postępów Nauk Rolniczych
|
2008
|
tom 524
Kanały wodne odgrywają znaczącą rolę w rozwoju roślin i ich adaptacji do zmieniającego się środowiska zewnętrznego. Wpływ na ekspresję genów kodujących białka kanałów wodnych, akwaporyn, wywierają takie czynniki jak: hormony, susza, wysokie stężenia soli, temperatura czy światło. Gen PnPIPl, kodujący akwaporynę P. nil został zidentyfikowany w wyniku przeszukiwania biblioteki cDNA sondą - uzyskaną w wyniku reakcji różnicowego profilowania ekspresji genów. Wstępne doświadczenia sugerowały regulację ekspresji genu PnPIPl poprzez światło. Celem prezentowanej pracy było sprawdzenie poziomu transkrypcji genu akwaporyny P. nil w liścieniach siewek uprawianych w warunkach ciągłej ciemności. Stosując technikę hybrydyzacji typu northern z użyciem sondy molekularnej RNA znakowanej radioizotopowo uzyskano sygnał hybrydyzacyjny do transkryptu wielkości 1200 pz. Ekspresja genu spadała w pierwszych godzinach nocy, a wzrastała w połowie drugiej doby. Maksimum akumulacji transkryptu stwierdzono w 48 godzinie ciemności. Wyniki badań sugerują, że ekspresja genu akwaporyny PIP1 w liścieniach P. nil nie jest regulowana rytmem endogennym.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.