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  • Endosperm  (8)
  • Earth Resources and Remote Sensing  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Regulation of α-galactosidase activity and the hydrolysis of galactomannan in the endosperm of the fenugreek (Trigonella foenum-graecum L.) seed (1985)
    Springer
    Planta 166 (1985), S. 271-275 
    Details
    ISSN: 1432-2048
    Keywords: Endosperm ; Galactomannan ; α-Galactosidase ; Germination (seed) ; Seed germination ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When endosperms were isolated from fenugreek seeds 5 h after sowing and incubated in a small volume of water, the development of α-galactosidase activity and the breakdown of the galactomannan storage polysaccharide were both inhibited relative to control endosperms incubated in larger volumes. The inhibition could be relieved by pre-washing the endosperms, and reimposed by the wash-liquors. If the endosperms were isolated 24 h after sowing, no inhibition was observed. Removal of the embryonic axis from germinating fenugreek seeds and from germinated seedlings also inhibited the development of α-galactosidase activity and galactomannan breakdown in the endosperms; the inhibition was more pronounced the earlier the axis was removed. Axis excision 5 h after sowing caused a delay in the onset of galactomannan breakdown and of the appearance of α-galactosidase activity in the endosperms. It also led to a decrease in the rates of galactomannan breakdown and α-galactosidase production. Axis excision 24 h after sowing caused only a slowing of the rates of galactomannan breakdown and α-galactosidase increase. The inhibition caused by axis removal at 5 h could be relieved partially by gibberellin (10-4 M), benzyladenine (10-5 M), mixtures of these and by the herbicide SAN 9789 [4-chloro-5-(methylamine)-2-(α,α,α-trifluoro-m-tolyl)-3-(2H)-pyridazinone]. These substances had no effect on the inhibition caused by axis-removal at 24 h. Excision of the cotyledons at 5 h-leaving the separated axis and the endosperm-also caused inhibition of galactomannan breakdown and α-galactosidase development. The results are consistent with the presence in the fenugreek seed endosperm of diffusible inhibitors of galactomannan mobilisation which are removed or inactivated during normal germination and early seedling development. They are also consistent with a role for the seedling axis in the control of galactomannan breakdown in the endosperm. Initially the axis appears to have a regulatory function (via gibberellins and/or cytokinins?) in determining the onset of α-galactosidase production in the endosperm. Thereafter its continued presence is necessary to ensure maximal rates of α-galactosidase production and galactomannan hydrolysis. The role of the axis may be initially to counteract the endogenous inhibitors in the endosperm and then to act as a sink for the galactomannan breakdown products released in the endosperm and taken up by the cotyledons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397359
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  • 2
    Electronic Resource
    Electronic Resource
    Galactomannan formation and guanosine 5′-diphosphate-mannose: galactomannan mannosyltransferase in developing seeds of fenugreek (Trigonella foenum-graecum L., leguminosae) (1982)
    Springer
    Planta 155 (1982), S. 105-111 
    Details
    ISSN: 1432-2048
    Keywords: Galactomannan ; Endosperm ; Polysaccharide (biosynthesis, storage) ; Mannosyltransferase ; Seed (development) ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time-course of galactomannan and stachyose (digalactosyl-sucrose) deposition in the fenugreek seed endosperm has been determined, and correlated with standard parameters of seed development. During, and only during, the period of galactomannan deposition, endosperm homogenates are capable of catalysing the transfer of labelled d-mannosyl residues from guanosine 5′-diphosphate d-[U-14C]mannose to a soluble polysaccharide product indistinguishable from galactomannan. The mannosyltransferase activity peaks twice, once at the beginning of galactomannan deposition, and again in the middle of the most rapid phase of galactomannan deposition. The enzyme in the later peak sediments with grossly particulate material (1,000 g pellet), whereas the earlier peak contains a considerable proportion of a particulate enzyme sedimenting at 100,000 g. These observations are discussed in the light of existing information on the ultrastructural aspects of galactomannan deposition. The mannosyltransferase is clearly involved in galactomannan formation in vivo, but the status of an accompanying galactosyltransferase is less clear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392539
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  • 3
    Electronic Resource
    Electronic Resource
    Degradation of the endosperm cell walls of Lactuca sativa L., cv. grand rapids in relation to the mobilisation of proteins and the production of hydrolytic enzymes in the axis, cotyledons and endosperm (1979)
    Springer
    Planta 146 (1979), S. 335-341 
    Details
    ISSN: 1432-2048
    Keywords: Endosperm ; Germination (seeds) ; Lactuca ; Reserve hydrolysis ; Storage protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The timing of changes in total nitrogen and soluble amino nitrogen content, and in the activities of proteinase (pH 7.0), isocitrate lyase, catalase, phytase, phosphatase (pH 5.0), α-galactosidase and β-mannosidase were studied in extracts from the cotyledons, axis and endosperms of germinating and germinated light-promoted lettuce seeds. The largest amount of total nitrogen (2.7% seed dry weight) occurs within the cotyledons, as storage protein. As this decreases the total nitrogen content of the axis increases and the soluble amino nitrogen in the cotyledons and axis increases. Proteinase activity in the cotyledons increases coincidentally with the depletion of total nitrogen therein. Enzymes for phytate mobilisation and for gluconeogenesis of hydrolysed lipids increase in activity in the cotyledons as the appropriate stored reserves decline. Beta-mannosidase, an enzyme involved in the hydrolysis of oligo-mannans released by the action of endo-β-mannase on mannan reserves in the endosperm, arises within the cotyledons. This indicates that complete hydrolysis of mannans to the monomer does not occur within the endosperm. Mobilisation of all cotyledon reserves occurs after the endosperm has been degraded, providing further evidence that the endosperm is an early source of food reserves for the growing embryo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387806
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  • 4
    Electronic Resource
    Electronic Resource
    A dual rôle for the endosperm and its galactomannan reserves in the germinative physiology of fenugreek (Trigonella foenum-graecum L.), an endospermic leguminous seed (1979)
    Springer
    Planta 147 (1979), S. 145-150 
    Details
    ISSN: 1432-2048
    Keywords: Endosperm ; Galactomannan ; Germination (seeds) ; Storage polysaccharide ; Trigonella ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some 30% of the reserve material in the fenugreek seed is galactomannan localised in the endosperm; the remainder is mainly protein and lipid in the cotyledons of the embryo. The importance of galactomannan to the germinative physiology of fenugreek has been investigated by comparing intact and endosperm-free seeds. From a purely nutritional point of view the galactomannan's rôle is not qualitatively different from that of the food reserves in the embryo. Nevertheless, due to its spatial location and its hydrophilic properties, the galactomannan is the molecular basis of a mechanism whereby the endosperm imbibes a large quantity of water during seed hydration and is able to “buffer” the germinating embryo against desiccation during subsequent periods of drought-stress. The galactomannan is clearly a dual-purpose polysaccharide, regulating water-balance during germination and serving as a substrate reserve for the developing seedling following germination. The relative importance of these two rôles is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389515
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  • 5
    Electronic Resource
    Electronic Resource
    Biosynthesis of legume-seed galactomannans in vitro (1989)
    Springer
    Planta 178 (1989), S. 41-51 
    Details
    ISSN: 1432-2048
    Keywords: Cyamopsis ; Endosperm ; Galacto-mannan biosynthesis ; Galactosyltransferase ; Mannosyltransferase ; Polysaccharide biosynthesis ; Seed development ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Particulate enzyme preparations were isolated from developing fenugreek (Trigonella foenum-graecum L.) and guar (Cyamopsis tetragonoloba [L.] Taub.) seed endosperms during the period of galactomannan deposition in vivo. These preparations catalysed the formation of polysacharide products from guanosine 5′-diphosphate (GDP)-mannose, from uridine 5′-diphosphate (UDP)-galactose and from mixtures of the two nucleotides. The products were analysed by solubility, by complete acid hydrolysis, and by selective enzymatic cleavage using pure enzymes of known specificity. With GDP-[U-14C]-d-mannose as substrate and a divalent metal cation (Mg+2, Mn+2, or Ca+2) a highly efficient transfer of labelled d-mannosyl residues was obtained to give a product identified as linear (1→4)-β-linked d-mannan. No transfer of galactosyl residues was obtained when GDP-[U-14C]-d-galactose was the only substrate, although very low and variable amounts of an unidentified product which released labelled glucose on acid hydrolysis were formed. In the presence of UDP-galactose, GDP-mannose and Mn+2 ions, products were formed which have been characterised as galactomanans — a linear (1→4)-β-d-mannan backbone carrying d-galactopyranosyl substituents linked (1→6)-α to mannose. The degree of galactose substitution of the d-mannan backbone was manipulated in vitro by varying GDP-mannose concentrations at constant (saturating) UDP-galactose levels. The transfer of d-galactosyl residues from UDP-galactose to galactomannan was absolutely dependent upon the simultaneous transfer of D-mannosyl residues from GDP-mannose. d-Mannan sequences pre-formed in situ using the mannosyltransferase in the absence of UDP-galactose could not become galactose-substituted in a subsequent incubation either with UDP-galactose alone or with UDP-galactose plus GDP-mannose A model for the interaction of GDP-mannose mannosyltransferase and UDP-galactose galactosyltransferase in galactomannan biosynthesis is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392525
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  • 6
    Electronic Resource
    Electronic Resource
    Endo-β-mannanase, the leguminous aleurone layer and the storage galactomannan in germinating seeds ofTrigonella foenum-graecum L. (1977)
    Springer
    Planta 133 (1977), S. 219-222 
    Details
    ISSN: 1432-2048
    Keywords: Aleurone layer ; Endo-β-mannanase ; Endosperm ; Galactomannan ; Germination ; Leguminous seeds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity ofendo-β-mannanase in the endosperm of fenugreek seeds at different stages of germination varies pari passu with storage galactomannan breakdown.Endo-β-mannanase is similarly associated with the galactomannan breakdown which occurs when isolated fenugreek half-endosperms are incubated under “germination” conditions. Metabolic inhibitors,acting on the aleurone layer reduceendo-β-mannanase production in the half-endosperms in proportion to their inhibition of galactomannan breakdown. It is concluded (a) thatendo-β-mannanase activity, like galactomannan breakdown, is regulated by the fenugreek aleurone layer and (b) that theendo-β-mannanase is almost certainly instrumental in bringing about galactomannanan hydrolysis in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380680
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  • 7
    Electronic Resource
    Electronic Resource
    Morphological aspects of the galactomannan formation in the endosperm ofTrigonella foenum-graecum L. (Leguminosae) (1977)
    Springer
    Planta 133 (1977), S. 243-248 
    Details
    ISSN: 1432-2048
    Keywords: Endosperm ; Galactomannan ; Secretion ; Ultrastructure ; Trigonella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mode of deposition (secretion) of galactomannan in the cells of the seed endosperm ofTrigonella foenum-graecum has been studied by electron microscopy. In cells which are just beginning to secrete galactomannan there are stacks of rough endoplasmic reticulum (ER). The intracisternal space (containing the enchylema) of the rough ER then swells, becomes vacuolated and forms a voluminous network, with “pockets” of cytoplasm entrapped within poculiform rough ER. The enchylema contains material which reacts with periodate-thiocarbohydrazidesilver proteinate in a very similar manner to the galactomannan already deposited in the cell wall. It appears that the galactomannan is formed in the intracisternal space of the rough endoplasmic reticulum and then expelled outside the plasmalemma. This mode of deposition contrasts with that of other plant cell wall polysaccharides whose secretion is mediated by Golgi vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380684
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  • 8
    Electronic Resource
    Electronic Resource
    Structure and biochemistry of endosperm breakdown in date palm (Phoenix dactylifera L.) seeds (1985)
    Springer
    Protoplasma 126 (1985), S. 159-167 
    Details
    ISSN: 1615-6102
    Keywords: Date ; Phoenix ; Mannanase ; Mannosidase ; Endosperm ; Germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The zone of endosperm breakdown in the germinated date seed (Phoenix dactylifera L.) is a narrow area immediately adjacent to the surface of the enlarging cotyledon, or haustorium. The zone width is correlated with the amount of cell division in the adjacent region of the haustorium. The sequence of endosperm breakdown is: 1. protein bodies vacuolate, 2. storage cell walls become electron-transparent immediately adjacent to the protoplast of each endosperm cell, 3. all remaining cytoplasm and lipid bodies disappear, and 4. the remaining cell walls become electron-transparent and collapse against the haustorium surface. Two cell wall hydrolases are present—endo-Βmannanase (EC3.2.1.78) and Β-mannosidase (EC3.2.1.25). Β-mannosidase is detectable in the endosperm before germination. At germination, the major portion of activity is found in the softened endosperm. Β-mannanase is only detectable from germination and there is always hundreds of fold greater activity in the softened endosperm than elsewhere. Proteinase is detectable in trace amounts at germination in the softened endosperm but is also found in the haustorium at later stages. Isolated haustoria, incubated in extracted ivory nut (Phytelephas macrocarpa) mannan in buffer, cause no mannan breakdown. Haustoria, incubated in a solution of locust bean galactomannan, cause no decrease in galactomannan viscosity. Our observations suggest that although haustoria probably regulate mannan breakdown in the endosperm, they do not seem to secrete the hydrolytic enzymes concerned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281791
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  • 9
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    AERONET Remotely Sensed Measurements and Retrievals of Biomass Burning Aerosol Optical Properties During the 2015 Indonesian Burning Season (2019)
    In:  Other Sources
    Details
    Publication Date: 2019-06-29
    Description: An extreme biomass-burning event occurred in Indonesia from September through October 2015 due to severe drought conditions, partially caused by a major El Nino event, thereby allowing for significant burning of peatland that had been previously drained. This event had the highest sustained aerosol optical depths (AOD) ever monitored by the global Aerosol Robotic Network (AERONET). The newly developed AERONET Version 3 algorithms retain high AOD at the longer wavelengths when associated with high Angstrom Exponents (AEs), which thereby allowed for measurements of AOD at 675 nanometers as high as approximately 7, the upper limit of Sun photometry. Measured AEs at the highest monitored AOD levels were subsequently utilized to estimate instantaneous values of AOD at 550 nanometers in the range of 11 to 13, well beyond the upper measurement limit. Additionally, retrievals of complex refractive indices, size distributions, and single scattering albedos (SSA) were obtained at much higher AOD levels than possible from almucantar scans due to the ability to perform retrievals at smaller solar zenith angles with new hybrid sky radiance scans. For retrievals made at the highest AOD levels the fine mode volume median radii were approximately 0.25 to 0.30 microns, which are very large particles for biomass burning. Very high SSA values (approximately 0.975 from 440 to 1020 nanometers) are consistent with the domination by smoldering combustion of peat burning. Estimates of the percentage peat contribution to total biomass burning aerosol based on retrieved SSA and laboratory measured peat SSA were approximately 80-85 percent, in excellent agreement with independent estimates.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN68573 , Journal of Geophysical Research: Atmospheres (ISSN 2169-897X) (e-ISSN 2169-8996); 124; 8; 4722-4740
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
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    Observations of the Interaction and Transport of Fine Mode Aerosols with Cloud and/or Fog in Northeast Asia from Aerosol Robotic Network (AERONET) and Satellite Remote Sensing (2018)
    In:  CASI
    Details
    Publication Date: 2019-05-11
    Description: Analysis of sun photometer measured and satellite retrieved aerosol optical depth (AOD) data has shown that major aerosol pollution events with very high fine mode AOD (〉1.0 in mid-visible) in the China/Korea/Japan region are often observed to be associated with significant cloud cover. This makes remote sensing of these events difficult even for high temporal resolution sun photometer measurements. Possible physical mechanisms for these events that have high AOD include a combination of aerosol humidification, cloud processing, and meteorological co-variation with atmospheric stability and convergence. The new development of Aerosol Robotic network (AERONET) Version 3 Level 2 AOD with improved cloud screening algorithms now allow for unprecedented ability to monitor these extreme fine mode pollution events. Further, the Spectral Deconvolution Algorithm (SDA) applied to Level 1 data (L1; no cloud screening) provides an even more comprehensive assessment of fine mode AOD than L2 in current and previous data versions. Studying the 2012 winter-summer period, comparisons of AERONET L1 SDA daily average fine mode AOD data showed that Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing of AOD often did not retrieve and/or identify some of the highest fine mode AOD events in this region. Also, compared to models that include data assimilation of satellite retrieved AOD, the L1 SDA fine mode AOD was significantly higher in magnitude, particularly for the highest AOD events that were often associated with significant cloudiness.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN57373 , Journal of Geophysical Research: Atmospheres (ISSN 2169-897X) (e-ISSN 2169-8996); 123; 10; 5560-5587
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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