Search results for "Darkness"

Vertical ground reaction force measurements and video measurements provide comparable estimates of distance moved by mice during artificial light and…

2011

Video-based measures of spontaneous activity of rodents are of interest in studying, e.g. physiology. However, video-based tracking methods typically require light. The purpose of the present study was to develop a video based method for tracking movements of mice during a dark period. The method was applied in comparing the dark and light period activities of mice. Ten male mice were used in the present study. The activity of the animals was monitored simultaneously with video and ground reaction force (GRF) recordings during consecutive 12h periods of artificial light and dark. Texture based background subtraction method was used to track the mouse from the video recording, while the weig…

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

2008

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…

Microtubule distribution in gravitropic protonemata of the mossCeratodon

1990

Tip cells of dark-grown protonemata of the moss Ceratodon purpureus are negatively gravitropic (grow upward). They possess a unique longitudinal zonation: (1) a tip group of amylochloroplasts in the apical dome, (2) a plastid-free zone, (3) a zone of significant plastid sedimentation, and (4) a zone of mostly non-sedimenting plastids. Immunofluorescence of vertical cells showed microtubules distributed throughout the cytoplasm in a mostly axial orientation extending through all zones. Optical sectioning revealed a close spatial association between microtubules and plastids. A majority (two thirds) of protonemata gravistimulated for > 20 min had a higher density of microtubules near the lowe…

Behavior of mixed Chlorophyceae cultures under prolonged dark exposure. Respiration rate modeling

2016

[EN] The behavior of three different microalgal cultures, when exposed for a long period (>48 h) to dark conditions, was studied with a methodology based on respirometry. The cultures were transferred to darkness and the oxygen evolution in the reactors was monitored after successive air injections. Several sequential oxygen uptake rates were thus calculated and a respiration constant, assuming a first order decay of a fraction of the biomass, was obtained by calibration. Initial specific oxygen uptake rates were in the range of 0.9 5.1 mg O2 g TSS−1 h−1 and dark respiration constants in the range of 0.005 0.018 h−1.

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.

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”.

Dark exposure affects plasticity-related molecules and interneurons throughout the visual system during adulthood

2020

Several experimental manipulations, including visual deprivation, are able to induce critical period-like plasticity in the visual cortex of adult animals. In this regard, many studies have analyzed the effects of dark exposure in adult animals, but still little is known about the role of interneurons and plasticity-related molecules on such mechanisms. In this study, we analyzed the effects of 10 days of dark exposure on the connectivity and structure of interneurons, both in the primary visual cortex and in the rest of cerebral regions implicated in the transmission of visual stimulus. We found that this environmental manipulation induces changes in the expression of synaptic molecules th…

GENETIC AND PHYSIOLOGICAL STUDIES OF THE EFFECT OF LIGHT ON THE DEVELOPMENT OF THE MOSS, PHYSCOMITRELLA PATENS

1978

Abstract The germination of Physcomitrella patens spores only occurs when wet spores are exposed to light. Depending on their ripeness, spores require from 44 to 64 h illumination to bring about maximum germination. There is a lag period of about 15 h between the reception of sufficient light to elicit germination before germination can be observed. Wavelengths in the range 640-680 nm are much more effective in inducing germination than longer or shorter wavelengths, but far-red reversal of red light induction of germination has not been demonstrated. Light also has very marked effects on protonemal and gametophore development. In darkness, only caulonemata are produced, and these grow nega…

Energy status and its control on embryogenesis of legumes: ATP distribution within Vicia faba embryos is developmentally regulated and correlated wit…

2003

To analyse the energy status of Vicia faba embryos in relation to differentiation processes, we measured ATP concentrations directly in cryosections using a quantitative bioluminescence-based imaging technique. This method provides a quantitative picture of the ATP distribution close to the in vivo situation. ATP concentrations were always highest within the axis. In pre-storage cotyledons, the level was low, but it increased strongly in the course of further development, starting from the abaxial region of cotyledons and moving towards the interior. Greening pattern, chlorophyll distribution and photosynthetic O2 production within embryos temporally and spatially corresponded to the ATP di…