Search results for "Darkness"

Plant regeneration from cultured leaves of Lavandula latifolia Medicus: Influence of growth regulators and illumination conditions

1989

Leaves were obtained from 4-week-old seedlings of Lavandula latifolia Medicus grown in vitro. Leaf explants were then cultured on MS medium supplemented with different concentrations and combinations of the auxins IAA or NAA with the cytokinin BA and maintained under three illumination conditions, 16h photoperiod, darkness or darkness followed by a photoperiod, to assess morphogenic responses. Irrespective of illumination conditions, bud regeneration was achieved only in media containing BA or BA/auxin combinations, with the best results being obtained in the presence of BA and 0.06 or 0.6 μM IAA or NAA. A photoperiod of 16h appeared to yield the best response in terms of bud regeneration p…

Über den Ureidstoffwechsel beim Laubmoosprotonema von Funaria hydrometrica L. (Sibth.)1)1)Herrn Prof. Dr. Dr. Kurt Mothes zum 75. Geburtstag gewidmet.

1975

Summary The activity of allantoinase (EC 3.5.2.5) is influenced by light and darkness. The extracts of dark-grown moss protonema showed a very higher enzyme activity than the extracts of light-grown plants. The allantoinase activity was increased by light-dark and decreased by dark-light transitions. DMAP mimicked light effects by stabelizing the charakteristic light depending enzyme avctivities in the dark. The inhibitors DCMU, DNP and CCCP increased the enzyme activity of light-grown moss protonema, to some extend they induced a “physiological dark condition”.

From whodunnit to whydunnit : the transformation of the traditional detective story into a modern crime novel

2008

Involvement of circadian oscillation(s) in the photoperiodic time measurement and the induction of reproductive diapause in a northern Drosophila spe…

2013

An ability to predict forthcoming changes in environmental conditions and get prepared for them in advance is crucial for the survival and reproduction of organisms living in a seasonally changing environment. We have studied the possible involvement of circadian oscillator(s) in the photoperiodic timer controlling seasonal responses by tracing Drosophila montana females' diapause induction in constant darkness and in a classical Nanda-Hamner experiment. Nearly all females developed ovaries in continuous darkness, which shows the direct development to be their default developmental pathway in the absence of photoperiods. In Nanda-Hamner experiment the females' diapause incidence was close t…

Arylalkylamine N-acetyltransferase gene expression in retina and pineal gland of rats under various photoperiods

2004

Abstract The present study examines how the circadian oscillators in the retina and the suprachiasmatic nucleus (SCN) respond to changes in photoperiod. ArylalkylamineN-acetyltransferase (aa-nat) gene expression studied by quantitative RT-PCR revealed that in adult Sprague–Dawley rats kept under different light–dark (LD) cycles for two weeks the temporal pattern of AA-NAT mRNA expression was identical in retina and pineal gland. In both tissues, the time span between the onset of darkness and the nocturnal rise in AA-NAT mRNA expression was 3 h under LD 20:4, 6 h under LD 12:12, and 15 h under LD 4:20. As aa-nat expression in the pineal gland is regulated by the circadian oscillator in SCN,…

Effects of Environmental Lighting and Tryptophan Devoid Diet on the Rat Vaginal Cycle

1998

Cerebral serotonin level influences luteinizing hormone release and, consequently, ovulation. The present study evaluated the effects of precooked maize meal (polenta), a diet almost devoid of tryptophan the serotonin precursor on the alterations of the estrus cycle as measured by vaginal smears analysis in Wistar rats. Several conditions of environmental lighting were used in order to modify ovarian cycle: 1) natural alternating light/dark cycle; 2) continuous darkness; 3) continuous light by sodium steams: 4) continuous light by fluorescent neon tubes. Rats bred in continuous lighting showed estrus-proestrus rate significantly greater than rats bred in normal lighting or in continuous dar…

Przywracanie wiary w stworzenie. Wokół wierszy Katarzyny Citko z tomu "Post tenebras Lux"

2018

The turn of the modern human from the supernatural realm, and from the spiritual dimension - from transcendence - results in a vision of a world in whichthere is no place for the God-Creator and in which the story of creation is supplanted by evolution. On the antipodes of this contemporary trend of culture, which rejects the theme of creation and the vision of the God-Creator, the book of Katarzyna Citko Post tenebras Lux - awarded the Masurian Orpheus Prize in 2015, situates itself. In the poetic message of the volume, the author talks about the mystery of everyday life, which she experiences, about the experienced epiphany of the God-Creator, thus, giving expression to an authentic, deep…

Electrophysiology of the Guinea-pig Pineal Organ: Sympathetic Influence and Different Reactions to Light and Darkness

1979

Publisher Summary Recent electrophysiological studies have shown that the guinea-pig pineal organ comprises two main categories of intrinsic cells, which are (a) pinealocytes which are predominantly influenced by central commissural fibers and (b) pinealocytes which are exclusively influenced by peripheral sympathetic fibers. The first group comprises spontaneously active cells which respond to olfactory, acoustic and short-term optic stimuli respectively. After sympathectomy their spontaneous activity is diminished but not suppressed. The second group comprises spontaneously active cells, which do not respond to short-term sensory stimulation and whose activity depends on the environmental…

The effect of light quality on anther culture of Citrus clementina Hort. ex Tan.

2005

This pre lim i nary re search re ports re sults on the in flu ence of light qual ity on an ther cul ture of Cit rus clementina Hort. ex Tan., cultivar Nules. Af ter one month of cul ti va tion in dark - ness, four light quali ties were tested: White, Red, Far-Red and Blue. Con tin u ous Dark ness and White light un der photoperiod of 16 hrs were used as a con trol con di tions. Ga metic embryoids and embryogenic cal lus were ob tained only un der photoperiodic con di tions of White light, sug gest ing that the al - ter na tion of light and dark can be used for the pro cess of ga - metic embryogenesis in Cit rus.

Turystyczny przewodnik po Piekle Mikołaja Reja, czyli o międzyplanetarnych podróżach duszy ludzkiej

2020

The article deals with the complex issue of presenting the underworld in the Reja's Wizerunk. The author draws attention to the presence in the output of the old Polish poet of many visionary elements borrowed from the most varied traditions and religious systems. The popular pattern of searching for spiritual perfection, fixed in the archetype of the topographic movement of the hero (Latin: Homo viator) turns out to be particularly visible. It turns out that at the very foundations of this imaginative pattern there is an ancient doctrine or interplanetary wandering of the soul. Most of the work was focused on the description of XI songs of Reja’s WizerunV, where a description of hell appea…