Red-Light Stimulation of Prolamellar Body Recrystallization and Thylakoid Formation in Barley Etioplasts

1971 ◽  
Vol 8 (1) ◽  
pp. 185-200
Author(s):  
D. R. BERRY ◽  
H. SMITH
Keyword(s):  
Red Light ◽  
Low Frequency ◽  
Chlorophyll Synthesis ◽  
Prolamellar Body ◽  
Lag Phase ◽  
Exact Nature ◽  
Prolamellar Bodies ◽  
Barley Leaves ◽  
Fraction I ◽  
And Function

The etioplasts of fully dark-grown barley leaves exhibit a relatively low frequency of crystalline prolamellar bodies (ca. 16-20%). Brief red-light treatment leads to rapid disruption of all prolamellar bodies followed by a slow reformation in the subsequent dark period. When several red-light treatments are given with intervening 3-h dark periods, a marked increase in the proportion of crystalline prolamellar bodies is seen. It is suggested that this phenomenon may be associated with the regeneration of protochlorophyll. Red-light pretreatment stimulates the formation of granal thylakoids upon subsequent transfer to continuous white light. This response is correlated with the phytochrome-mediated shortening of the lag phase in chlorophyll-synthesis under identical conditions. Regular arrays of hexagonal tubules 16-19 nm in diameter have been observed often in close juxtaposition to the newly forming thylakoid membranes. These may be aggregations of Fraction I protein, although their exact nature and function is at present Unknown.

scholarly journals EARLY STAGES IN THE DEVELOPMENT OF PLASTID FINE STRUCTURE IN RED AND FAR-RED LIGHT

1964 ◽  
Vol 22 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Shimon Klein ◽  
G. Bryan ◽  
Lawrence Bogorad
Keyword(s):  
Fine Structure ◽  
Stages Of Change ◽  
Structural Changes ◽  
Red Light ◽  
Prolamellar Body ◽  
Lag Phase ◽  
Prolamellar Bodies ◽  
Chlorophyll Accumulation ◽  
Time Required ◽  
Bean Leaves

Developmental changes in fine structure were studied in plastids of etiolated bean leaves during the time required for the protochlorophyllide-chlorophyllide transformation and the following lag phase prior to chlorophyll accumulation. In agreement with some other workers, two distinct stages of change in the fine structure of proplastids were found to occur upon illumination during this period. The first involves a dissociation of the previously fused units in the prolamellar bodies of the proplastids and occurs simultaneously with the protochlorophyllide-chlorophyllide conversion in light of 655 mµ, but not of 682, 700, or 730 mµ. The effect of the red light could not be reversed by a simultaneously supplied stronger far-red irradiation. The energy requirements for these structural changes parallel those for the pigment conversion. During the following step the vesicles which arose from the fused units of the prolamellar body were dispersed in rows through the stroma, and the prolamellar bodies themselves disappeared. For these changes to occur, higher light energies were required and the leaves had to be illuminated for longer periods. A red preillumination seemed to accelerate the development somewhat. The structural changes could be induced by light of 655 mµ, but also, to a lesser degree, of 730 mµ. No measurable additional chlorophyll accumulated during this period. Thus, the structural changes observed were independent of major changes in pigment content.

Macromolecular Physiology Of Plastids

1974 ◽  
Vol 15 (1) ◽  
pp. 31-55
Author(s):  
K. W. HENNINGSEN ◽  
J. E. BOYNTON
Keyword(s):  
Small Diameter ◽  
Chlorophyll Synthesis ◽  
Prolamellar Body ◽  
Lag Phase ◽  
Plastid Development ◽  
Structural Reorganization ◽  
Chlorophyll Accumulation ◽  
Young Leaves ◽  
Plastid Membranes ◽  
Structural Aspects

The development of plastid membranes was studied in relation to chlorophyll accumulation in dark-grown barley seedlings of various ages after transfer to light. Quantitative electron microscopy showed that the prolamellar body membranes are reorganized into primary lamellar layers which contain sufficient membranes to support grana formation during 24 h of greening. Structural reorganization of the plastid membranes is completed rapidly in young seedlings, but is slow in older seedlings. Chlorophyll accumulates rapidly in young leaves after a short lag. In older leaves there is a longer lag phase before the onset of chlorophyll synthesis, and the final rate of synthesis is lower. Shortly after transferring to light, the crystalline prolamellar bodies in the etioplasts are transformed and then dispersed into lamellar layers with numerous perforations and protuberances. Before the phase of rapid chlorophyll synthesis, many small-diameter 2-disk grana are formed. When chlorophyll begins to accumulate, the perforations are rapidly eliminated from the lamellar layers and a maximum number of 2-disk grana are formed. As greening proceeds additional disks are added to these original 2-disk grana. During the phase of rapid chlorophyll synthesis, pairing of the lamellae is positively correlated with the accumulation of chlorophyll. During greening less chlorophyll appears to be incorporated into the paired regions of the lamellae in young leaves as compared to old leaves. The results on the structural aspects of plastid development are discussed in relation to the formation of photosynthetic capacity.

Quantifying the Ontogeny of Optokinetic and Vestibuloocular Behaviors in Zebrafish, Medaka, and Goldfish

2004 ◽  
Vol 92 (6) ◽  
pp. 3546-3561 ◽  
Author(s):  
James C. Beck ◽  
Edwin Gilland ◽  
David W. Tank ◽  
Robert Baker
Keyword(s):  
Visual Stimulation ◽  
Larval Fish ◽  
Low Frequency ◽  
Velocity Storage ◽  
Active Movement ◽  
Stimulus Velocity ◽  
Oculomotor Behavior ◽  
Bode Plots ◽  
And Function ◽  
Eye Velocity

We quantitatively studied the ontogeny of oculomotor behavior in larval fish as a foundation for studies linking oculomotor structure and function with genetics. Horizontal optokinetic and vestibuloocular reflexes (OKR and VOR, respectively) were measured in three different species (goldfish, zebrafish, and medaka) during the first month after hatching. For all sizes of medaka, and most zebrafish, Bode plots of OKR (0.065–3.0 Hz, ±10°/s) revealed that eye velocity closely followed stimulus velocity (gain > 0.8) at low frequency but dropped sharply above 1 Hz (gain < 0.3 at 3 Hz). Goldfish showed increased gain proportional to size across frequencies. Linearity testing with steps and sinusoids showed excellent visual performance (gain > 0.8) in medaka almost from hatching; but zebrafish and goldfish exhibited progressive improvement, with only the largest equaling medaka performance. Monocular visual stimulation in zebrafish and goldfish produced gains of 0.5 versus <0.1 for the eye viewing a moving versus stationary stimulus pattern but 0.25 versus <0.1 in medaka. Angular VOR appeared much later than OKR, initially at only high accelerations (>200°/s at 0.5 Hz), first in medaka followed by larger (8.11 mm) zebrafish; but it was virtually nonexistent in goldfish. Velocity storage was not observed except for an eye velocity build-up in the largest medaka. In summary, a robust OKR was achieved shortly after hatching in all three species. In contrast, larval fish seem to be unique among vertebrates tested in their lack of significant angular VOR at stages where active movement is required for feeding and survival.

scholarly journals Presyncodon, a Web Server for Gene Design with the Evolutionary Information of the Expression Hosts

2018 ◽  
Vol 19 (12) ◽  
pp. 3872 ◽  
Author(s):  
Jian Tian ◽  
Qingbin Li ◽  
Xiaoyu Chu ◽  
Ningfeng Wu
Keyword(s):  
High Frequency ◽  
Synonymous Codon ◽  
Low Frequency ◽  
Synonymous Codon Usage ◽  
Codon Usage Pattern ◽  
Evolutionary Information ◽  
Specific Expression ◽  
Synonymous Codons ◽  
New Genes ◽  
And Function

In the natural host, most of the synonymous codons of a gene have been evolutionarily selected and related to protein expression and function. However, for the design of a new gene, most of the existing codon optimization tools select the high-frequency-usage codons and neglect the contribution of the low-frequency-usage codons (rare codons) to the expression of the target gene in the host. In this study, we developed the method Presyncodon, available in a web version, to predict the gene code from a protein sequence, using built-in evolutionary information on a specific expression host. The synonymous codon-usage pattern of a peptide was studied from three genomic datasets (Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae). Machine-learning models were constructed to predict a selection of synonymous codons (low- or high-frequency-usage codon) in a gene. This method could be easily and efficiently used to design new genes from protein sequences for optimal expression in three expression hosts (E. coli, B. subtilis, and S. cerevisiae). Presyncodon is free to academic and noncommercial users; accessible at http://www.mobioinfor.cn/presyncodon_www/index.html.

scholarly journals Quantitative studies on ferredoxin in greening bean leaves

1973 ◽  
Vol 136 (3) ◽  
pp. 697-703 ◽  
Author(s):  
B. G. Haslett ◽  
R. Cammack ◽  
F. R. Whatley
Keyword(s):  
Red Light ◽  
Chlorophyll Synthesis ◽  
Paramagnetic Resonance ◽  
Quantitative Studies ◽  
Low Concentrations ◽  
Electron Paramagnetic ◽  
Linear Manner ◽  
Cytoplasmic Ribosomes ◽  
Mechanism Operative ◽  
Bean Leaves

Two methods of measuring small amounts of the iron–sulphur protein ferredoxin are described. One involves measurements of the signal at g=1.96 produced by reduced ferredoxin in an e.p.r. (electron-paramagnetic-resonance) spectrometer; the other depends on the rate of ferredoxin-dependent electron transport in a chloroplast bioassay measured in an O2 electrode. These methods of measurement were used to examine the development of ferredoxin during the greening of etiolated bean leaves. Ferredoxin is present in low concentrations in the leaves and cotyledons of 14-day-old etiolated beans (Phaseolus vulgaris L. var. Canadian Wonder), and develops in a linear manner with time when the leaves are illuminated. This synthesis appears to be independent of chlorophyll synthesis during the early stages of greening. However, the chlorophyll/ferredoxin ratio reaches a final value of approx. 360 irrespective of the light intensity, indicating the existence of a control mechanism operative in deciding the stoicheiometry of these components in the mature chloroplast. The ferredoxin synthesis appears to be light-dependent, and red light is the most effective in its promotion. The effect of red illumination is not reversed by far-red light, indicating the absence of a phytochrome control of ferredoxin synthesis. From experiments using specific inhibitors of chloroplast protein synthesis, it is concluded that ferredoxin is synthesized on cytoplasmic ribosomes.

scholarly journals Free and sulfated steroids secretion in postpubertal boars (Sus scrofa domestica)

Reproduction ◽  
2014 ◽  
Vol 148 (3) ◽  
pp. 303-314 ◽  
Author(s):  
G Schuler ◽  
Y Dezhkam ◽  
L Bingsohn ◽  
B Hoffmann ◽  
K Failing ◽  
...  
Keyword(s):  
Venous Blood ◽  
Low Frequency ◽  
Peripheral Circulation ◽  
Target Cells ◽  
Sulfated Steroids ◽  
Liquid Chromatography Tandem Mass ◽  
Testicular Steroidogenesis ◽  
High Production ◽  
And Function

Sulfated steroids have been traditionally regarded as inactive metabolites. However, they may also serve as precursors for the production of active free steroids in target cells. In this study, we used the boar as a model to study the metabolism, transport, and function of steroid sulfates due to their high production in the porcine testicular–epididymal compartment, of which the role is unknown. To characterize the secretion of free and sulfated steroids, plasma samples were collected from six postpubertal boars over 6 h every 20 min from the jugular vein. Long-term secretion profiles were also established in seven boars stimulated with human chorionic gonadotropin. To directly characterize the testicular output, samples were collected from superficial testicular arterial and venous blood vessels. Testosterone, androstenedione and sulfated pregnenolone, DHEA, estrone (E1), and estradiol-17β (E2) were determined by liquid chromatography–tandem mass spectrometry. Free E1 and E2 were measured by RIA. Irrespective of a high variability between individuals, the results suggest that i) all steroids assessed are primarily produced in the testis, ii) they exhibit similar profiles pointing to a pulsatile secretion with low frequency (three to five pulses per day), and iii) after synthesis at least a major proportion is immediately released into peripheral circulation. The fact that all steroid sulfates assessed are original testicular products and their high correlations with one another suggest their role as being intermediates of testicular steroidogenesis rather than as being inactivated end products. Moreover, a substantial use of sulfated steroids in porcine testicular steroidogenesis would assign a crucial regulatory role to steroid sulfatase, which is highly expressed in Leydig cells.

scholarly journals Language prediction mechanisms in human auditory cortex

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
K. J. Forseth ◽  
G. Hickok ◽  
P. S. Rollo ◽  
N. Tandon
Keyword(s):  
Speech Perception ◽  
Auditory Cortex ◽  
Speech Production ◽  
Low Frequency ◽  
Spoken Language ◽  
Planum Temporale ◽  
Gamma Power ◽  
And Function ◽  
Predictive Mechanisms ◽  
Stimulation Of

Abstract Spoken language, both perception and production, is thought to be facilitated by an ensemble of predictive mechanisms. We obtain intracranial recordings in 37 patients using depth probes implanted along the anteroposterior extent of the supratemporal plane during rhythm listening, speech perception, and speech production. These reveal two predictive mechanisms in early auditory cortex with distinct anatomical and functional characteristics. The first, localized to bilateral Heschl’s gyri and indexed by low-frequency phase, predicts the timing of acoustic events. The second, localized to planum temporale only in language-dominant cortex and indexed by high-gamma power, shows a transient response to acoustic stimuli that is uniquely suppressed during speech production. Chronometric stimulation of Heschl’s gyrus selectively disrupts speech perception, while stimulation of planum temporale selectively disrupts speech production. This work illuminates the fundamental acoustic infrastructure—both architecture and function—for spoken language, grounding cognitive models of speech perception and production in human neurobiology.

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