The transition of the apical meristem from vegetative to reproductive growth is a critical event in the life cycle of a plant. In rice, the timing of this transition affects the timing of heading. This timing, or heading date, is one of the critical traits considered for adapting rice to different cultivation areas and cropping seasons. Rice is a short-day (SD) plant; its heading is promoted by short photoperiods. The response of the plant to length of day (referred to as photoperiod sensitivity [PS]) and its basic vegetative growth determine the heading date of rice. Many genetic studies of heading date have been performed, and several genes controlling PS in rice have been genetically identified, including Se1 (Lm), Se3 to Se7, and E1 to E3 (Yokoo et al., 1980; Yamagata et al., 1986; Poonyarit et al., 1989; Sano, 1992; Yokoo and Okuno, 1993; Tsai, 1995; Kinoshita, 1998). However, only one gene involving photoperiod response in rice has been cloned, Se5 (Izawa et al., 2000). Little is known ...
Three pea (Pisum sativum) loci controlling photoperiod sensitivity, HIGH RESPONSE (HR), DIE NEUTRALIS (DNE), and STERILE NODES (SN), have recently been shown to correspond to orthologs of Arabidopsis (Arabidopsis thaliana) circadian clock genes EARLY FLOWERING3 (ELF3), ELF4, and LUX ARRHYTHMO, respectively. A fourth pea locus, PHOTOPERIOD (PPD), also contributes to the photoperiod response in a similar manner to SN and DNE, and recessive ppd mutants on a spring-flowering hr mutant background show early, photoperiod-insensitive flowering. However, the molecular identity of PPD has so far remained elusive. Here, we show that the PPD locus also has a role in maintenance of diurnal and circadian gene expression rhythms and identify PPD as an ELF3 co-ortholog, termed ELF3b. Genetic interactions between pea ELF3 genes suggest that loss of PPD function does not affect flowering time in the presence of functional HR, whereas PPD can compensate only partially for the lack of HR. These results provide an ...
RIVERA LOZANO, María Teresa et al. Seasonal variation in ovulatory activity of nubian, alpine and nubian X criollo does under tropical photoperiod (22° N). Trop. subtrop. agroecosyt [online]. 2011, vol.14, n.3, pp.973-980. ISSN 1870-0462.. In the present study, seasonal variation in ovulatory activity of Nubian, Alpine and Criollo x Nubian goats in the semiarid region of central-northern Mexico (22° 14 N) was examined. The study was conducted under natural photoperiod and climate conditions during a whole year. Eight female goats per breed were grouped separately and exposed to visual, olfactory and audible signals of bucks. Blood samples were obtained twice per week and serum progesterone concentrations were determined. All goats presented a clear pattern of seasonal ovulatory activity based on serum progesterone profiles. Length of the ovulatory activity period did not differ between genotypes (P ,0.10), and had an average duration of 4.3 months. Nevertheless Criollo x Nubian goats ...
In Arabidopsis and other species, light and photoperiod signals are integrated at the level of FT expression. Late-flowering photoperiod pathway mutants in Arabidopsis such as gi, fkf1, and cry2 have reduced FT expression under LD conditions, whereas early-flowering mutants have increased FT expression. In pea, LATE1 is clearly necessary for induction of the FT homolog FTL (Fig. 5B), demonstrating that both the GI-FT regulatory interaction and the association between photoperiod-insensitive late flowering and low expression of FT homologs are conserved in pea. Our preliminary studies of other photoperiod response mutants, such as phyA and SD-grown wild-type plants, suggest that they also show altered FTL expression (V. Hecht and C. Knowles, unpublished data), in support of a role for FTL as a target of the photoperiod pathway.. In Arabidopsis and rice, effects of GI on FT expression are mediated at least in part through changes in the expression of CO genes (Suárez-López et al., 2001; Hayama ...
Many plants are photoperiod sensitive and can measure day length changes to forecast the change in seasons and react accordingly. As a result, photoperiod sensitive plants will synchronize flowering time as a result of changes in day length, and the degree of sensitivity may change at different points in the developmental life cycle of the plant.. Many domesticated plants have lost their photoperiod sensitivity during the domestication process with a focused breeding effort giving farmers predictable plant life cycles they can rely on to ensure multiple harvests and consistent flowering times for a population. During recent domestication, and breeding steps, mutations in the genes that encoded the light sensing mechanism were introduced or incorporated as a result of crossbreeding with natural occurring autoflowering plants within the same species that eliminate the photoperiod sensitivity resulting in photoperiod insensitive plant.. Today, cannabis and hemp are being actively bred for ...
Although there is much theoretical and empirical data about the life history responses of time constrained organisms, little is known about the latitude compensating mechanism that enables northern populations developmental rates to compensate for latitude. To investigate the importance of photoperiod on development and growth, I collected adults and raised the offspring of the obligatory univoltine damselfly Lestes sponsa from two populations at different latitudes (53º N and 63º N). The offspring were raised in a common laboratory environment at 21º C and at the two photoperiods corresponding to the sites of collection. Field data showed that adult and egg sizes decreased towards the higher latitude. This adult size difference was a genetically fixed trait since the same size difference between populations was also found when larvae where reared in the laboratory. All studied individuals expressed shorter development time and faster growth rates under northern photoperiod regimes. Northern ...
The photoperiodic response in Arabidopsis thaliana requires the precise regulation of CONSTANS (CO) expression in relation to the light period during the day. In short days (SDs) levels of CO expression are normally low during the light period, and this results in delayed flowering compared with long days (LDs) when CO expression rises to high levels before the end of the light period. We identified a novel flowering time gene called DAY NEUTRAL FLOWERING (DNF) that acts in the same flowering pathway as CO. DNF is a membrane-bound E3 ligase that represses CO expression and plays an important role in maintaining low levels of CO expression in SDs. The effect of DNF on the rhythm of CO expression is essential for the photoperiodic response of Arabidopsis, enabling it to have a different flowering response in LDs and SDs.. ...
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A long-day plant is a plant that only flowers after being exposed to sun light for more than necessary. This is a photo of lettuce. Lettuce is a type of long-day plant.
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Red firespike (Odontonema strictum) is a tropical flowering plant that was selected as a potential flowering potted plant for its attractive red floral spikes. The objective of this study was to evaluate how light intensity, photoperiod, and temperature affect the growth and flowering of firespike. In Experiment 1, plants were grown under 0%, 45%, or 65% shade and two photoperiod conditions; long-day (LD = ≥14 h) and short-day (SD = 9 h), for 16 weeks. Plants grown under 45% shade + LD were tallest at 35.9 cm, while plants grown under 65% shade + SD were shortest at 22.8 cm. During the finishing stage, the number of inflorescences increased when plants were grown under 45% shade + SD, 45% shade + LD, and no shade, with 6, 7, and 9 inflorescences, respectively. In addition, the first open flower was observed in the 0% shade group (control) 92 days after starting the experiment. The time to first open flower increased when the plants were grown under 65% shade, either under SD or LD. In Experiment 2,
In ancient times, summer solstice celebrated the longest day of the year. Get to know summer solstice and plan an event your family and friends will love.
Reduced height 8 (Rht8) is the main alternative to the GA-insensitive Rht alleles in hot and dry environments where it reduces plant height without yield penalty. The potential of Rht8 in northern-European wheat breeding remains unclear, since the close linkage with the photoperiod-insensitive allele Ppd-D1a is unfavourable in the relatively cool summers. In the present study, two near-isogenic lines (NILs) contrasting for the Rht8/tall allele from Mara in a UK-adapted and photoperiod-sensitive wheat variety were evaluated in trials with varying nitrogen fertiliser (N) treatments and water regimes across sites in the UK and Spain.. The Rht8 introgression was associated with a robust height reduction of 11% regardless of N treatment and water regime and the Rht8 NIL was more resistant to root-lodging at agronomically-relevant N levels than the tall NIL. In the UK with reduced solar radiation over the growing season than the site in Spain, the Rht8 NIL showed a 10% yield penalty at standard ...
Mate Preference of Female Blue Tits Varies with Experimental Photoperiod. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Dear Netters, Thank you for the wonderful response (I had over 10). This is a summary and conclusion of the response plus my investigation of most of the references. To start with I must clarify my objectives a little better than I did in my first message. I am a physiologist interested in characterizing growth responses to different environmental stresses. Since Arabidopsis is so small I was looking for conditions that would optimize growth conditions to produce the greatest amount of leaf biomass for analyses. (I think there might be a few people out there who might also be interested in this). I have found that growing plants hydroponically is by far the best way to get big plants (no root restriction, well-watered all the time, ample nutrient supply). We are also interested in delaying flowering to get larger plants. We are using both the Columbia and Ler ecotypes (hence my interest in photoperiod). Shorter days delay flowering in our two ecotypes and produce much larger plants before ...
In humans, changes in day length, shift-work or trans-meridian travel lead to deficits in mood and cognitive functions. Previously, these deficits were thought to arise exclusively from sleep deprivation and/or disruptions in circadian rhythms. Work from Dr. Samer Hattars laboratory has recently shown that light can directly affect mood and learning, even in the context of normal sleep and functional circadian activity. The goal of our project is to determine the retinal and brain circuits that underlie the effects of an aberrant light schedule on mood and cognitive functions, by employing a combination of anatomical, functional, and behavioral approaches. We will evaluate the effects of social and sensory stimulations as possible therapies to prevent the mood and learning deficits induced in mice exposed to aberrant light schedules. Results obtained from this work will uncover the connectivity and functions of new retinal-brain circuits that are required for regulating mood and cognitive ...
In humans, changes in day length, shift-work or trans-meridian travel lead to deficits in mood and cognitive functions. Previously, these deficits were thought to arise exclusively from sleep deprivation and/or disruptions in circadian rhythms. Work from Dr. Samer Hattars laboratory has recently shown that light can directly affect mood and learning, even in the context of normal sleep and functional circadian activity. The goal of our project is to determine the retinal and brain circuits that underlie the effects of an aberrant light schedule on mood and cognitive functions, by employing a combination of anatomical, functional, and behavioral approaches. We will evaluate the effects of social and sensory stimulations as possible therapies to prevent the mood and learning deficits induced in mice exposed to aberrant light schedules. Results obtained from this work will uncover the connectivity and functions of new retinal-brain circuits that are required for regulating mood and cognitive ...
The most dramatic phase change that flowering plants undergo is the transition from vegetative to reproductive growth. For this transition to be successful, plants must integrate a variety of environmental signals with endogenous cues, such as plant age (Bernier, 1988).. In the facultative long-day plant Arabidopsis, the transition to reproductive growth occurs rapidly in long days but much more slowly in short days. Several flowering-time mutants, in which the timing of this transition is changed, have been isolated. Analysis of the responses of different mutants to the environment together with studies of their genetic interactions have resulted in a two-pathway model showing how the transition to flowering is regulated (Martínez-Zapater et al., 1994; Weigel, 1995; Peeters and Koornneef, 1996). According to this model, long days induce flowering via a facultative and fast pathway, whereas under noninductive photoperiods, an autonomous and much slower pathway is rate limiting. The latter ...
Read "OsPhyA modulates rice flowering time mainly through OsGI under short days and Ghd7 under long days in the absence of phytochrome B, Plant Molecular Biology" on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
A happy summer solstice to everyone. Im loving the longer days, especially how it allows me to be out in the garden till seven pm or later. More time to plant, fertilize, work on planting beds. And of course photograph the bounty of plants now in bloom. Theres still a wealth of flowers, from shrubs, new perennials, the last of the spring annuals, bulbs, vines (especially vines) and succulents. When you have 500 different species/varieties in your garden, theres always going to be something in bloom. Here are some, shot today, descriptions are top to bottom ...
The Umea Plant Centre scientists also looked at the genetics that signal fall growth cessation and bud set in trees. They discovered that CO accumulates in response to long days and initiates the formation of FT, and in the short days of fall, the pattern of CO accumulation changes so that FT is not activated. They also observed that the same species of tree at different latitudes would respond to local conditions in order to become dormant before the risk of frost damage. Because the short day-lengths occurring in fall induce bud set, the scientists wondered if FT and CO also controlled this process. When they grew trees originating from different latitudes in Europe in a growth chamber, the Umea Plant Centre team observed that this response was under strong genetic control and was maintained when trees were moved. However, they did observe that levels of CO and FT genes could be made to respond to artificially imposed day-length. Most importantly, they observed that under the same day-length, ...
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Could you be more obvious about your desperation for attention and recognition please? Also, I dont see how calling Larry a math illiterate helps your case. You want scientists attention, work the science and stop trolling on useless discussions about misapplied math where it does not correspond. Your comments and your links to your scientific proposals have no relationship whatsoever. Your accusations of libel are also misplaced and useless to your apparent cause, which, in those links, seems to be a cause for some kind of new way of thinking about some problems as opposed to some other kind of thinking, where I detect a veiled straw-man you seem to be fighting against, which also deters from your point if you have any. The ad hominem is all yours. Giving you some well-deserved insults is not ad hominem, nor is it libel (you have no idea what a dictionary is, do you?). Also, I am not Larry. If you have something to tell me do so, and address me directly. Stop acting as if you had some kind ...
Welcome, John. The thing about the yellow ladybirds is their size - about the same as a match-head. I got a pair in cop yesterday, so that pic will be up later. ...
I bought a PuddleJumper from Aldi last week for $10. The last time we went swimming Jackson held onto an adult or sat on the edge the entire time, even though he had arm floaties and a tube float I was so proud of Jackson for actually swimming with the Puddle Jumper. This is the first time hes ever kicked and paddled simultaneously ...
The CONSTANS (CO) and CO-like gene family from cowpea. GSRs encoding the conserved DNA binding domains of CONSTANS (CO) and CO-like TFs were identified and asse
Lights are back on timer, so i have to keep up with turning on co2 12:00pm to 6:00pm photoperiod, i dial almost same timing for co2 on/off trinkle...
My sweetheart is in the hospital. God-willing the doctors will be able to figure out whats wrong. I was sitting here listening to my iPod when this song came on...tonight, I dedicate it to my beloved. Lady Antebellum and Jim Brickman, Never Alone
The only problem we had is, I mentioned to his MA and to the doc himself about her hip. Since it was the first visit, there was a lot of medical history to get through. By the end of the appointment, we had both forgotten it and we left without him letting us know what he thought we should do. I called back as soon as I got home, and spoke to a nurse who at first told me that he would want to see her for it. I explained we were JUST in there and he did examine her, I just left without an order for an x-ray or an ultrasound. She said she would have him call me and I am still waiting for him to do so. Please, PLEASE, P-L-E-A-S-E do not make me bring her BACK in just to get an order! Ugh ...
We all feel tired and warn out after long day at work or university, that you end up forgetting doing our daily 50-100 sit ups and instead head to dreamland straight away. ...
Neuromuscular synaptic transmission in the ectothermal crab Carcinus maenas was used to assess the extent to which photoperiod affected the attainment of temperature acclimation. A separate series of experiments were carried out to determine thermotolerance to high temperature (CTMax) and its dependence on prior heat shock and heat shock proteins. Dactylopodite closer muscle resting potentials and the characteristics of evoked excitatory junction potentials in response to stimulation of the excitatory tonic axon were recorded with intracellular microelectrodes and the extent of acclimation to temperature under different photoperiodic regimes was measured. Animals were acclimated for at least two week to either 8 C or 25 C with short day (8hr: 16hr, L/D) or long day (16hr: 8hr, L/D) photoperiods. Photoperiod differences had a marked effect on acclimation to temperature as measured by muscle resting potential and excitatory junction potential amplitude and facilitation. In short day photoperiods ...
The capacity to develop tolerance to photoinhibition of photosynthesis was assessed in jack pine seedlings (Pinus banksiana Lamb.). Photoinhibition induced at 5 degrees C in control jack pine seedlings grown at 20 degrees C was saturated above an irradiance of 1000 mu mol . m(-2). s(-1) but was detectable at an irradiance as low as 25 mu mol . m(-2). s(-1). However, 20 degrees C seedlings shifted to 5 degrees C were 2-fold more tolerant to photoinhibition than 20 degrees C unshifted control seedlings, as detected by either the light-dependent decrease in photochemical efficiency or the apparent quantum yield of O-2 evolution. The extent of this tolerance of photoinhibition was dependent upon time, photoperiod, and irradiance during exposure to the low-temperature shift. Furthermore, the tolerance of photoinhibition was correlated with anthocyanin accumulation in 20 degrees C grown seedlings shifted to 5 degrees C. In addition, seedlings shifted to 5 degrees C and an 8-h photoperiod exhibited a ...
Responsiveness of the reproductive system, metabolic rate, and other traits to changing photoperiods from summer to winter seasons is an important physiological trait in most temperate-zone mammals [1]. Seasonal changes in photoperiod, or day length, modify reproductive timing in many temperate-zone mammals including sheep, hamsters, rodents, horses, and ferrets by acting through the photoperiod pathway [2 - 4]. The photoperiod pathway transduces the photoperiod into a physiological signal beginning with the transduction of light or dark input from specialized photoreceptors and ganglion cells in the eye through the retinohypothalamic tract into two regions of the hypothalamus, the suprachiasmatic nucleus (SCN), and later the paraventricular nucleus. A sympathetic norepinephrine signal from the SCN then passes to the hindbrain, the superior cervical ganglion in the spinal cord, and eventually to the pineal gland, which releases the indoleamine hormone melatonin [5]. Pinealoctyes within the ...
Melatonin and photoperiodic time measurement in Japanese quail (Coturnix coturnix japonica).: Artificial extension of the duration of nocturnally secreted circu
The project has three phases: In the first phase, chickpea genotypes were evaluated in the growth chambers for their flowering response under both long (16 h) and short days (10 h) and 22 0C and 16 0C day and night temperatures. Variability among the genotypes in their flowering response under either long or short days was identified. In the second phase of the study eight selected chickpea genotypes with extreme responses to photoperiod will be evaluated to determine the timing and duration of the photoperiod sensitive phase and the time of floral initiation and to establish whether photoperiod sensitivity ends at floral initiation or if it extends further into the phases of flower development. These same eight genotypes will be further characterized in a factorial combination of two photoperiods: 10 h and 16 h and three temperatures regimes: 16/8 0C, 20/12 0C and 24/16 0C (day/night). This study allows us to determine flowering response of chickpea genotypes grown in a range of thermal regimes ...
The project has three phases: In the first phase, chickpea genotypes were evaluated in the growth chambers for their flowering response under both long (16 h) and short days (10 h) and 22 0C and 16 0C day and night temperatures. Variability among the genotypes in their flowering response under either long or short days was identified. In the second phase of the study eight selected chickpea genotypes with extreme responses to photoperiod will be evaluated to determine the timing and duration of the photoperiod sensitive phase and the time of floral initiation and to establish whether photoperiod sensitivity ends at floral initiation or if it extends further into the phases of flower development. These same eight genotypes will be further characterized in a factorial combination of two photoperiods: 10 h and 16 h and three temperatures regimes: 16/8 0C, 20/12 0C and 24/16 0C (day/night). This study allows us to determine flowering response of chickpea genotypes grown in a range of thermal regimes ...
Flowering in many plant species is controlled by photoperiod, which represents the most reliable seasonal change in nature. The availability of crops with different photoperiod responses made it possible to extend their distribution range. The gene network controlling flowering is well studied in the model plant Arabidopsis thaliana, where the FLOWERING LOCUS T (FT) gene is crucial for the acceleration of flowering. FT is part of a gene family that also includes the TERMINAL FLOWER 1 (TFL1) gene, which inhibits flowering. Constitutive FT expression or loss of TFL1 function causes early flowering and transition of the shoot apex from vegetative to reproductive identity. FT proteins have a conserved role as mobile flowering signals in several different species and promote flowering in long or short days depending on the species. The induction of flowering by FT family members has been investigated in legumes such as pea, soybean and Medicago but the FT family has not yet been characterized in ...
Melatonin, better known as the hormone of darkness, is secreted by the pineal gland during the night and helps us fall asleep. Because its internal regulation depends on light, melatonin is part of chronobiology, the study of biological mechanisms and their adaptations to lunar and solar related rhythms (Klein et al. 1991). Therefore, photoperiod changes greatly impact melatonin concentration, influencing changes in neuronal and hormonal mechanisms of the photo neuro-endocrine systems, namely reproduction. Research has shown that a disruption in the circadian rhythm of melatonin due to photoperiod changes detrimentally affects the rhythmic function of the female reproductive cycle. Research from journals, articles, and printed books has shown that both exogenous and endogenous features contribute to the reproductive cycle and that the internal mechanisms are entrained by environmental cues. Photoresponsiveness of the reproductive system is mediated by the internal biological clock, transcriptional
BACKGROUND: There is not enough information about theeffects of heat stress and photoperiod on different lobes structure.OBJECTIVES: The present study aims at determining thehistological changes and the rate of changes in each lobes of ratprostate, affected by photoperiod changes and heat stress.METHODS:To this end, 15 adult male wistar rats were divided tothree groups: 1. the control group in which the rats were kept in12L: 12D and 25°C temperature condition, 2. the heat stressgroup in which the rats were kept in 12L: 12D and 42+1 °Ctemperature condition for 4 to 5 hours per day, and 3. thephotoperiod group in which the rats were kept in 16L: 8D and25°C temperature condition. After 30 days, samples were takenfrom different lobes and sections with 5 to 6μ thickness weremade and stained by H&E and PAS. RESULTS: The microscopicresults showed that histomorphometrical structure andhistochemical reactions of the different lobs of normal prostateof the rats are different. The proportion of parenchyma to
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337S is a novel bi-pole-photo-thermo-sensitive genic male sterile line in wheat, and sensitive to both long day length/high temperature and short day length/low temperature condition. Although the regulatory function of MicroRNAs (miRNAs) in reproductive development has been increasingly studied, their roles in pre-meiotic and meiotic cells formation of plants have not been clearly explored. Here, we explored the roles of miRNAs in regulating male sterility of 337S at short day length/low temperature condition. Small RNA sequencing and degradome analyses were employed to identify miRNAs and their targets in the 337S whose meiotic cells collapsed rapidly during male meiotic prophase, resulting in failure of meiosis at SL condition. A total of 102 unique miRNAs were detected. Noticeably, the largest miRNA family was MiR1122. The target CCR4-associated factor 1 (CAF1) of miR2275, a subunit of the Carbon Catabolite Repressed 4-Negative on TATA-less (CCR4-NOT) complex, contributes to the process of early
Looking for online definition of Day length dependent in the Medical Dictionary? Day length dependent explanation free. What is Day length dependent? Meaning of Day length dependent medical term. What does Day length dependent mean?
To ensure reproductive success, flowering time is sophisticatedly regulated by developmental processes that integrate various external and internal factors in plant. Recent studies showed that post-transcriptional control also plays important roles in flowering time regulation (Bezerra et al., 2004; Doyle et al., 2005; Kuhn et al., 2007; Liu et al., 2007b). In our study, AtBRNs regulate the flowering time through the post-transcriptional control of SOC1 activity. The atbrn1/atbrn2-3 double mutant flowered early under LD and SD conditions, and under SD conditions after vernalization treatment (Fig. 2a), and the early-flowering phenotype was associated with increased expression of AP1, LFY, and FT. Although these integrators have overlapping functions, SOC1 definitely regulates LFY expression (Lee & Lee, 2010). Consistently, the LFY transcript showed the highest rate of increase in these integrators. SOC1 RNA, which is not regulated by AtBRNs, could activate LFY expression in atbrn1/atbrn2-3. ...
The results indicate that there has been a significant change in the complement of FT-like genes that function as the main sources of florigen in sorghum (SbCN8, SbCN12) and rice (Hd3a = SbCN15; RFT1, no sorghum ortholog), therefore regulation of flowering time could also differ, even though both grass species are short day plants. SbCO activates expression of SbCN8 and SbCN12, although SbCN12 was induced to a significantly greater extent. SbCO also increased expression of SbEHD1, an activator of Hd3a expression in rice. SbEHD1 expression is repressed by SbPRR37 and SbGhd7 and induced when photoperiod sensitive sorghum grown in LD is transferred to SD [1, 2]. Increases in SbEHD1 expression occur in parallel with increases in SbCN8 and SbCN12 expression, suggesting that SbEhd1 can induce the expression of these genes as shown in Figure 6. However, the extent and specificity of this proposed activity of SbEhd1 will require further analysis in backgrounds where SbCO has minimal influence on the ...
en] Sexually mature ring doves (Streptopelia risoria) maintained from hatch on a photoperiod of 14 h light : 10 h darkness (14L : 10D) and kept in isolation were transferred to 8L : 16D. This treatment resulted in a partial regression of the ovaries and testes and a fall in the concentration of plasma LH but not of plasma FSH. After 2--3 months exposure to 8L : 16D, the gonads regrew to their original size: this regrowth was accompanied by a parallel increase in the concentration of plasma LH. The responsiveness of the pituitary gland to LH releasing hormone in both sexes after 5 weeks of exposure to 8L : 16D (when the gonads were partially regressed) was similar to the response observed after 15 weeks exposure to this lighting schedule (when the gonads had regrown). It was concluded that the spontaneous recovery of gonadal size in ring doves exposed to 8L : 16D is controlled by the hypothalamus and does not involve changes in the functional capacity of the pituitary gland or of the gonads ...
Drosophila melanogaster, like most organisms, has an endogenous clock. This clock is mainly synchronized by light. To achieve this, D. melanogaster uses three photoreceptor organs: the compound eyes, the ocelli and the Hofbauer Buchner eyelet. Additionally, the fly has the blue light photoreceptor pigment chryptochrome and an unknown photoreceptor pigment in the dorsal neurons of the endogenous clock. To test the influence of those photoreceptors and pigments on the endogenous clock, the locomotor activity of various fly strains was recorded under long- and short-day conditions. This investigation revealed that cryptochrome is particularly important for the entrainment in short photoperiods. It mediates the after-effects of light on the endogenous clock, and it is responsible for period lengthening in long day scenarios. The compound eyes are important for the entrainment under short- and long-day conditions, yet more so in long days. Furthermore, they are responsible for the adjustment of the ...
Hazlerigg, DG, Ebling, FJP and Johnston, JD (2005) Photoperiod differentially regulates gene expression rhythms in the rostral and caudal SCN ...
STONEHENGE, England - An estimated record number of people flocked to Stonehenge on the Salisbury Plain in southern England on Sunday to greet the Summer Solstice.
Animals and reagents. Manduca sexta (Lepidoptera: Sphingidae) were reared in the departmental insect rearing facility on an artificial diet on a long-day photoperiod regimen (17 hr light/7 hr dark) at 26°C, as described previously (Sanes and Hildebrand, 1976a). Metamorphic adult development proceeds over 18 stages, each stage lasting 1-4 d, beginning at the time of pupation and ending with the emergence of the adult moth. Pupae were staged by the criteria described by Tolbert et al. (1983) and Oland and Tolbert (1987), based on morphological changes in the structures visible through the cuticle under a dissecting microscope with bright illumination. Animals were anesthetized on ice before dissection. All chemicals and antibodies were purchased from Sigma (St. Louis, MO) and Jackson ImmunoResearch (West Grove, PA), respectively, unless otherwise indicated.. Cloning and sequence analyses of cDNAs. Total RNA isolated from antennae or brains of stage 6 pupae was used as the template for ...
Provide adequate lighting. This should be at least 2W per US Gallon (3.8L) of fluorescent lighting over the length of the tank for a period of at least 10 hours a day. Cool white tubes are usually all that is required. If you can position the tank so that it can get a little sunlight for at least an hour a day, then do so (make sure water doesnt overheat). Diana recommends a mid-day siesta [1], and uses a 5 hour on, 4 hours off, 5 hours on photoperiod on her own tanks. The dark period allows CO2 levels to rise which promotes plant growth and inhibits algae growth ...