bluuebunny/crossref_metadata_2025 huggingface dataset:
Approaches to elucidate the basis of desiccation-tolerance in seeds
Authors: Kermode Allison R.
Published: September 2008

Plants undergo a series of physiological, biochemical and molecular changes in response to adverse environmental conditions or stresses such as drought, low temperature or high salt. Several genes and their corresponding proteins have been described that may play a role in withstanding water-deficit-related stresses or full desiccation. In particular, sugars and late-embryogenesis-abundant (LEA) proteins have received the most attention. Plant responses to water-deficit and desiccation have been well-characterized at the molecular level; however, pinpointing the precise roles of the gene products in protecting cells under conditions of water deficit remains a challenging task. While few plants are capable of withstanding full desiccation, most seeds undergo this event as a pre-programmed and final stage in their development. These are the so-called ‘orthodox’ seeds. In contrast to seeds of orthodox species, those of recalcitrant species do not acquire desiccation tolerance during their development and are shed from the parent plant at relatively high water contents. The essential components of desiccation tolerance of seeds are likely to involve the ability to effect repair upon subsequent rehydration as well as the ability to accumulate protective substances that limit the amount of damage which otherwise would be caused by water loss. Studies have begun to examine whether the desiccation sensitivity of recalcitrant seeds is at least partially the result of an insufficient accumulation of LEA-type proteins, or whether other factors (including a lack of protective sugars) are more important. This review assesses some of these studies as well as recent research to understand gene and protein function using transgenic host plant systems.
The most prevalent protein in a heat-treated extract of pea (Pisum sativum) embryos is an LEA group I protein; its conformation is not affected by exposure to high temperature
Authors: Russouw Pauline S. , Farrant Jill , Brandt Wolf , Lindsey George G.
Published: September 2008

The LEA-like protein previously isolated from a homogenate of pea (Pisum sativumL.) embryonic axes heated at 80°C for 10 min (Russouwet al., 1995) was purified without exposure to heat. Peptides produced by trypsin digestion were separated by HPLC and sequenced. The protein was identified as a member of the LEA group I family. The conformation of the protein was compared before and after heat treatment by antibody affinity, circular dichroism spectroscopy, fluorescence spectroscopy and 8-anilino-1-naphthalenesulfonic acid binding. No differences could be detected, demonstrating that the protein was not irreversibly denatured by exposure to high temperature.
Subcellular organization and metabolic activity during the development of seeds that attain different levels of desiccation tolerance
Authors: Farrant Jill M. , Pammenter N. W. , Berjak Patricia , Walters Christina
Published: September 2008

Water contents, desiccation tolerance, respiratory rates and subcellular characteristics of three contrasting seed types were studied during development.Avicennia marina(a tropical wetland species) andAesculus hippocastanum(a temperate species) produce recalcitrant seeds andPhaseolus vulgarisproduces orthodox seeds. During development,A. hippocastanumandP. vulgarisseeds showed a decline in water content and respiration rate with a concomitant increase in desiccation tolerance. These parameters did not change during the development ofA. marinaseeds once they had become germinable. There was a decrease in the degree of vacuolation and an increase in the deposition of insoluble reserves inA. hippocastanumandP. vulgarisseeds, whileA. marinaseeds remained highly vacuolated and did not accumulate insoluble reserves. Mitochondria and endomembranes degenerated during the development ofA. hippocastanumandP. vulgarisseeds, but remained unchanged inA. marinaseeds. The data are consistent with the hypothesis that extensive vacuolation and high metabolic rates contribute to desiccation sensitivity. However, the development of recalcitrantA. hippocastanumseeds is similar to that of orthodoxP. vulgarisseeds. These data are in accord with the concept of seed recalcitrance being a consequence of truncated development. The results suggest that there may be three categories of seeds: orthodox seeds which develop desiccation tolerance, seeds which show similar development to orthodox seeds, but are shed before desiccation tolerance is well developed, and seeds which show no developmental trends giving rise to increased tolerance.
Removal of the testa during germination or establishment increases germinant mortality, decay and water loss
Authors: Lamont B. B. , Milberg P.
Published: September 2008

By means of direct manipulation, this study showed that the testa protects the germinating seed and germinant from decay (an advantage in moist soils) and desiccation (an advantage in periodically dry soils) in four species, all of which retain their testas until the cotyledons are lifted above the soil. Furthermore, the testa prevents early spreading of the cotyledons (an advantage when elongating through soil and litter). Almost all germinants ofBanksia hookerianaandLeucadendron eucalyptifolium, with their testas removed, died and rotted away after being sown on the soil surface or at a range of depths.Hakea cyclocarpaandH. strumosashowed only minor losses compared with the intact germinants. All naked germinants were smaller than the controls at any depth, except amongH. cyclocarpa. Absence of the testa did not differentially affect the length of the hypocotyl in the dark or light, but lateral spread of the cotyledons was accelerated, especially in the dark. Removal of a small fraction of the testa was sufficient to cause general mortality ofB. hookerianagerminants but not ofH. cyclocarpaorH. strumosa. After imbibition, water content of the naked embryos ofB. hookerianareverted to the air-dry state within 24 h of sowing in air-dry sand, while intact seeds were still moist even after 7 days of drying. Compared with intact seeds, drying periods of 3–7 days decreased the amount of germination and root growth of naked embryos after rewetting, and increased microbial infection of the survivors. Removal of the testa from germinants was sufficient to cause general mortality after only 6 h in air-dry sand. In contrast, most intact germinants with short radicles recovered after drying for 2 days.
A comparative study of the seed germination biology of a narrow endemic and two geographically-widespread species ofSolidago(Asteraceae). 5. Effect of dry storage on after-ripening and survivorship
Authors: Walck Jeffrey L. , Baskin Jerry M. , Baskin Carol C.
Published: September 2008

The effect of dry storage under ambient laboratory conditions on after-ripening and survivorship was tested on seeds of the geographically-widespreadSolidago altissimaand S.nemoralisand the narrow-endemicS. shortii. Freshly-matured seeds ofS. altissimacollected in 1991 and in 1992 germinated to low or moderate percentages in light at 15/6, 20/10 and 25/15°C and to high percentages at 30/15 and 35/20°C, whereas those ofS. nemoralisandS. shortiigerminated to low percentages over the range of temperature regimes. After 0.8–1.8 years of storage, 1991 seeds ofS. altissimaincubated in light germinated to high percentages at 25/15, 30/15 and 35/20°C, those ofS. nemoralisdid so at 30/15 and 35/20°C and those ofS. shortiiat 20/10, 25/15, 30/15 and 35/20°C; 1992 seeds of all three species germinated to high percentages at 20/10, 25/15, 30/15 and 35/20°C. Freshly-matured 1991 and 1992 seeds of the three species germinated to low percentages in darkness over the range of temperature regimes, and only seeds ofS. shortiigerminated to high percentages after 0.8–1.8 years of storage. Compared with cold stratification, dry storage was only moderately effective in breaking dormancy in these three species. The primary difference in after-ripening of seeds of the three species was that seeds of the narrow endemic germinated to higher percentages in darkness than those of its two geographically-widespread congeners. Survivorship curves for 1991 and 1992 seeds ofS. altissimaandS. nemoralisand for 1992 seeds ofS. shortiiwere of Deevey Type I; the survivorship curve for 1991 seeds ofS. shortiiwas closest to Type II. Longevity of 1991 seeds ofS. altissima, 1992 seeds ofS. nemoralisand 1991 and 1992 seeds ofS. shortiiwas <4.0 years, whereas that of 1991 seeds ofS. nemoraliswas <2.3 years; 5% of 1992 seeds ofS. altissimawere viable after 4.0 years.
The effect of maturity on the moisture relations of seed longevity in foxglove (Digitalis purpureaL.)
Authors: Hay F.R. , Probert R.J. , Smith R. D.
Published: September 2008

Controlled aging experiments were carried out in order to evaluate the changes in seed longevity occurring following the attainment of maximum seed dry weight in foxglove (Digitalis purpureaL.). Seeds harvested in three successive years were stored at ~5% moisture content (fresh weight basis) and 50°C. Seed longevity was greater the later the seeds were harvested. When the data were modelled using the predictive viability model of Ellis and Roberts, these increases were attributable to increases in both the theoretical initial viability (in probits) of the seed-lot,Ki, and in the standard deviation of the normal distribution of seed deaths in time,σ. Furthermore, there was a positive relationship betweenKiandσwhich was independent of the year of harvest (r= 0.9016, for 11 d.f.,P< 0.001). These results do not support the predictive model which relies on the assumption thatσwill not differ between seed lots of the same species stored under identical conditions. When seeds were stored at a range of moisture contents (between 5 and 10%) at 50°C, increases inσduring seed development were manifest as changes in the negative logarithmic relationship betweenσand moisture content; below an upper limit, the regressions for seed lots at different stages of maturity were significantly different (P< 0.05) but could be constrained to either a common intercept or to a common slope (P< 0.05). It is proposed that it was the inherent variation in individual seed lifespans which increased during seed development. These results raise important concerns regarding the use of predetermined ‘species constants’ to predict the longevity of seed lots during long-term storage in seed banks.
Loss and induction of conditional dormancy in seeds of Sitka spruce maintained moist at different temperatures
Authors: Jones Steve K. , Ellis Richard H. , Gosling Peter G.
Published: September 2008

Pretreatment of moist seeds at certain temperatures can reduce seed dormancy, but such observations represent the net effect of pretreatment. Seeds of Sitka spruce (Picea sitchensis[Bong.] Carr.) were raised to 30% moisture content and pretreated at five different temperatures between 5 and 30°C for up to 24 weeks (168 d). Subsequent ability to germinate at 10°C and viability were then determined in order to investigate the effects of pretreatment on seed dormancy and survival. There was a curvilinear, negative semi-logarithmic relationship between seed longevity and pretreatment temperature, such that Q10for loss in viability increased from 2.6 between 10 and 20°C to 2.8 between 20 and 30°C. Simple multiplicative models combining cumulative normal frequency distributions for each of loss in viability and loss in dormancy were able to describe the changes in ability to germinate at 10°C, after pretreatment at 5, 10 and 30°C. However, in order to quantify the changes in ability to germinate observed at 10°C after pretreatment at 15°C, it was necessary also to invoke a model of dormancy reimposition, while for the results at 20°C it was necessary to postulate both dormancy reimposition and the further loss of this reimposed dormancy. It is concluded that moist seeds of Sitka spruce held at 15 and 20°C cycle between the dormant and non-dormant condition.
Developmental pattern of biotinylated proteins during embryogenesis and maturation of soybean seed
Authors: França Neto José B. , Shatters Robert G. , West S. H.
Published: September 2008

The developmental pattern of biotinylated proteins (BP) during embryogenesis and maturation of soybean seed was characterized. Detection of these BP was compared with the development of desiccation tolerance in seeds. Three groups of BP were detected in soybean seeds using a biotin-streptavidin detection method: the first group consisted of a set of three bands with a mean apparent MW of 85 kDa (called BP85), detected in crude extracts of embryonic axes (EA) from non-dehydrated seeds (NDS) and from artificially slow-dehydrated seeds (DS); the second one, BP75, was a single protein with an apparent MW of 75 kDa and was expressed in cotyledons (COT) and EA tissues of NDS and DS; the third group with a mean apparent MW of 35 kDa (BP35), was expressed at high levels only in COT of NDS. BP35 concentration was highest in the early stages of seed development (21 days after flowering — DAF) and decreased as seeds developed, being almost imperceptible after 47 DAF. Conversely, only traces of BP75 and BP85 extracted from EA and COT were detected at early stages of seed development (21–33 DAF). Maximum levels of accumulation of these proteins were expressed at 42–47 DAF and remained constant until harvest maturity. Desiccation-tolerant stage of the seeds was initiated at 47 DAF, which coincided with the stage of maximum accumulation of BP75 and BP85 in the seeds, however, appearance of these proteins could be stimulated by desiccation of immature seeds that had not achieved desiccation tolerance. Therefore changes in biotinylated proteins are coincident with, but not sufficient for, the development of desiccation tolerance.
Changes in selected plant growth regulators during germination in sorghum
Authors: Dewar J. , Taylor J. R. N. , Berjak P.
Published: September 2008

The technique of radioimmunoassay following sample resolution by HPLC was used to assay the amounts of the cytokinins zeatin (Z), zeatin riboside (ZR) and isopentenyladenine (IPA), the combined amounts of gibberellins1+3(GA1+3), and the amounts of indole acetic acid (IAA) and abscisic acid (ABA) during germination in grains of sorghum. Concentrations of GA1+3were low throughout germination and did not appear to be related to the time of germination. In the mature, non-germinated grain, the concentration of each of the other plant growth regulators was much higher in the smaller component comprised of the embryonic axis and scutellum than in the much larger endosperm tissue. During the germination period studied (64 h), these concentrations declined, with a peak in the amount of the cytokinin IPA and a small peak in Z+ZR (24 h) in the embryo following the first visible signs of root protrusion and coincident with a large enhancement in amylase activity. The high concentration of ABA in the embryo tissue prior to germination was noteworthy. It is suggested that the interaction of ABA and the cytokinins IPA and Z+ZR may play a significant role in controlling sorghum germination.
Cryopreservation of seeds of four coffee species (Coffea arabica, C. costatifructa, C. racemosa and C. sessiliflora): importance of water content and cooling rate
Authors: Dussert Stéhane , Chabrillange Nathalie , Engelmann Florent , Anthony François , Louarn Jacques , Hamon Serge
Published: September 2008

In the range of water contents studied (0.1–0.4 g H2O g dw−1),Coffea arabicaseeds were less sensitive to desiccation thanC. costatifructa, C. racemosaandC. sessilifloraseeds. At 0.20 g H2O g dw−1, 53% ofC. arabicaseeds germinated after direct immersion in LN (rapid cooling, 200°C min−1), but none of them developed into normal seedlings. By contrast, inC. costatifructa, C. racemosaandC. sessiliflora, when seeds were dehydrated to the optimal water content (0.19, 0.28 and 0.31 g H2O g dw−1, respectively), the percentages of seeds which developed into normal seedlings after LN exposure were 26, 78 and 31% of the desiccation control, respectively. Normal seedlings could be recovered from cryopreservedC. arabicaseeds only if they were desiccated to 0.20 g H2O g dw−1and precooled slowly to −50°C prior to immersion in LN. Precooling seeds at 2°C min−1allowed 25% of seeds to develop into normal seedlings. The thawing rate had no effect on the survival of cryopreservedC. arabicaseeds. In all cryopreservation experiments, the total germination did not reflect the percentage of seeds which developed into normal seedlings. Examination of excised embryos indicated a partial explanation of this difference since only the shoot apex was destroyed in abnormal embryos, whereas the hypocotyl and radicle were normal.
The seed bank dynamics ofCornus controversaand their rote in regeneration
Authors: Masaki Takashi , Tanaka Hiroshi , Shibata Mitsue , Nakashizuka Tohru
Published: September 2008

Seed-bank dynamics ofC. controversa, a common tree in Japanese temperate forests, were investigated at Ogawa Forest Reserve by direct measurement of seed input, soil seed density, and seedling output (germination of soil seeds), together with two field experiments on postdispersal seed mortality. Soil seed density varied from 4 to 233 m−2in the site near conspecific adults (<5 m horizontally from crown edge), and 0 to 18 m−2in far sites (≥5 m) during the 1988–92 period. Seed input occurred only in 1988 and 1990: 190–740 m−2at the sites near conspecific adults, and 4–20 m−2at the far sites. Seedling output was observed every year and accounted for 0–15% of the loss from the seed bank, occasionally 30–60%. Seeds buried at 5-cm depth suffered moderate mortality (c.0.2 year−1) by fungal pathogens. In contrast, seeds experimentally placed on the ground suffered higher mortality (0.5–1 year−1) through predation by ground mammals, probably wood mice. In the experiment, seeds whose mesocarp was removed survived much better. On the other hand, distance itself did not appear to affect post-dispersal mortality of seeds. Seeds in canopy gaps also tended to suffer higher mortality. Current spatial pattern and mode of seed dispersal should decrease the potential ability of the seed bank of this species to colonize safe sites. Rare and unpredictable events might increase the contribution of the seed-bank strategy to regeneration in this forest.
Germination-related proteins in wheat revealed by differences in seed vigour
Authors: Guy P. A. , Black M.
Published: September 2008

Artificial aging of wheat grains (Triticum aestivumcv. Mercia) for 3 d resulted in the gradual loss of seed vigour without loss of viability, but the latter decreased rapidly over the next 24 h. Loss of vigour was expressed as a delay in germination i.e. an increasing ‘lag’ period with aging before the onset of radicle emergence, but the subsequent rate of seedling growth was not affected. There was an overall decrease in the incorporation of35S-methionine into protein in aged embryos, and associated with the aging-induced delay in the completion of germination (i.e. start of radicle emergence) there was a delay in the production of certain polypeptides. In embryos of both non-aged and aged seeds these polypeptides appeared just prior to radicle emergence but several of these were never synthesized in embryos from non-viable seeds. The synthesis of mRNA coding forin vitrotranslated polypeptides, or groups of polypeptides, was similarly delayed in lowvigour embryos. Furthermore, some polypeptides were identified which were induced by the accelerated aging treatment. It is concluded that a reduced level of protein and mRNA synthesis in the embryos of low-vigour seeds may result in the delay in the accumulation of specific of mRNAs and polypeptides which are needed for the normal completion of germination, i.e. radicle emergence.
Reimposition of conditional dormancy during air-dry storage of prechilled Sitka spruce seeds
Authors: Jones Steve K. , Gosling Peter G. , Ellis Richard H.
Published: September 2008

Prechilling seeds of Sitka spruce (Picea sitchensis[Bong.] Carr.) at 4°C with 30% moisture content for 12–14 weeks (84–98 d) removed conditional dormancy (i.e. they were then able to germinate at 10°C). The non-dormant status was preserved after redrying to 6% moisture content. However, conditional dormancy was gradually reimposed during subsequent air-dry storage at 4°C and 6% seed moisture content in all five seed lots tested. Further investigations with one seed lot showed that reimposition was reversed by a second prechill treatment, but was reimposed again during subsequent air-dry storage. The trend of dormancy reimposition within seed lots over time was quantified by negative exponential relations between ability to germinate at 10°C and duration of air-dry storage. The progress of dormancy reimposition was influenced by seed storage moisture content and was most rapid at 4–10%. At higher moisture contents (15 and 20%) the rate of the reimposition of conditional dormancy was much reduced, while at moisture contents of 25 and 30% further loss in dormancy occurred. Thus it is clear that dormancy reimposition occurred during storage at low water potential rather than solely during desiccation from high to low water potential.
Germination and vigour loss of non-sprouted and sprouted wheat seeds during storage – testing the viability constants
Authors: Stahl M. , Steiner A. M.
Published: September 2008

The loss of percentage germination and vigour of non-sprouted and sprouted seeds of winter wheat was determined during storage for 80 days at 11 different combinations of moisture content and temperature. Before storage the initial percentage germination and vigour were reduced according to the level of sprouting. During storage the percentage germination and vigour decreased. The rate of germination loss increased with increasing seed moisture content and/or increasing temperature. The species-specific constants KE, CW, CH and CQ of the viability equation were not different for non-sprouted and sprouted seeds. Likewise, the relation between the percentage of normal and abnormal seedlings was independent of sprouting. The rate of vigour loss was also independent of the storage conditions and of sprouting.
Effects of dormancy-breaking chemicals on ABA levels in barley grain embryos
Authors: Wang Mei , van der Meulen René M. , Visser Karin , Van Schaik Henk-Peter , Van Duijn Bert , de Boer Albertus H.
Published: September 2008

The endogenous ABA contents of dormant and nondormant barley grains were determined following application of different compounds to break dormancy. The chemicals used for breaking of dormancy in intact dormant grains were weak and strong acids, alcohols, hydrogen peroxide, cyanide, nitrate, salicylic acid, gibberellic acid and fusicoccin. The dormancy-breaking compounds could be classified into two major groups: compounds that caused a decrease in endogenous ABA (class I) and compounds which did not affect endogenous ABA (class II). Class I compounds included gibberellic acid, ethanol, hydrogen peroxide, nitrate, salicylic acid; class II compounds were fusicoccin, acid (H2SO4), sodium azide, n-caproic acid. In addition, these dormancy-breaking compounds were able to stimulate the germination rate when applied to embryos isolated from dormant grains. The concentrations necessary for stimulation of germination of isolated embryos were much lower than the concentrations for breaking the dormancy of intact grains. After embryos were isolated from dormant grains and incubated in water, ABA was determined in both embryos and in the incubation media. The class I compounds stated above also reduced ABA content in the incubation medium of isolated embryos, while class II compounds had no effect on ABA content of the medium. External application of ABA could overcome the effect of dormancy-breaking compounds of class I but not of class II. The results suggest that in the presence of the agents belonging to class II, ABA responsiveness of isolated embryos from dormant grains is decreased, compared to nontreated embryos.
Seed biology and technology: At the crossroads and beyond. Introduction to the Symposium on Seed Biology and Technology: Applications and Advances and a prospectus for the future
Authors: Bradford Kent J. , Cohn Marc A.
Published: September 2008

The papers in this special section ofSeed Science Researchare products of a symposium on Seed Biology and Technology: Applications and Advances, held in Fort Collins, Colorado, on 13–16 August, 1997. The symposium was convened as a cooperative effort of Regional Research Project W-168 within the United States Department of Agriculture (USDA) Cooperative States Research, Extension and Education Service (CSREES) system. Regional Research Projects are authorized by the Hatch Act, which established the Agricultural Experiment Station (AES) system in the United States (US Code). This is a system in which land-grant institutions in each state conduct research and education programmes relevant to agriculture, the environment and society. Regional Research projects are a mechanism ‘for cooperative research in which two or more State agricultural experiment stations are cooperating to solve problems that concern the agriculture of more than one state.’ Such projects ‘can provide the solution to a problem of fundamental importance or fill an important gap in our knowledge from the standpoint of the present and future agriculture of the region’
Seed enhancements
Authors: Taylor A. G. , Allen P. S. , Bennett M. A. , Bradford K. J. , Burris J. S. , Misra M. K.
Published: September 2008

Seed enhancements may be defined as post-harvest treatments that improve germination or seedling growth, or facilitate the delivery of seeds and other materials required at the time of sowing. This definition includes three general areas of enhancements: pre-sowing hydration treatments (priming), coating technologies and seed conditioning. Pre-sowing hydration treatments include non-controlled water uptake systems (methods in which water is freely available and not restricted by the environment) and controlled systems (methods that regulate seed moisture content preventing the completion of germination). Three techniques are used for controlled water uptake: priming with solutions or with solid particulate systems or by controlled hydration with water. These priming techniques will be discussed in this paper with reference to methodology, protocol optimization, drying and storage. Coating technologies include pelleting and film coating, and coatings may serve as delivery systems. Seed conditioning equipment upgrades seed quality by physical criteria. Integration of these methods can be performed, and a system is described to upgrade seed quality inBrassicathat combines hydration, coating and conditioning. Upgrading is achieved by detecting sinapine leakage from nonviable seeds in a coating material surrounding the seeds. Seed-coat permeability directly influences leakage rate, and seeds of many species have a semipermeable layer. The semipermeable layer restricts solute diffusion through the seed coat, while water movement is not impeded. Opportunities for future seed enhancement research and development are highlighted.
Seed development in Phaseolus vulgaris L. cv. Seminole. 3. NMR imaging of embryos during ethylene-induced precocious germination
Authors: Fountain David W. , Forde Lucy C. , Smith Edwin E. , Owens Karen R. , Bailey Donald G. , Callaghan Paul T.
Published: September 2008

Embryos taken from late maturation phase seeds of Phaseolus vulgaris cv. Seminole prior to seed desiccation (35–45 DAA) can be induced to germinate in the absence of water by exogenous ethylene. NMR imaging of proton relaxation within the embryo shows changes in water status in putative (and not fully differentiated) vascular tissues of the hypocotyl within 3 h of ethylene administration. Difference imaging revealed that the change was progressive in the hypocotyl towards the radicle tip and was accompanied by changes in water status in the cotyledons. Water within plumular leaves was also affected. Increase in diameter of the hypocotyl–radicle axis (as estimated by pixel counts) was detectable from 3 h. Longitudinal radicle growth was detectable by NMR imaging at 18 h. Visible germination under the conditions used was apparent after 20 h. Changes in water status detected by this technique are an indication of changes in activity (concentration) or motion of water molecules or both. The data are consistent with a mode of action of ethylene in stimulating a redistribution of water within embryo structures from cotyledons to axis via the cotyledonary node and allowing the axis access to water sufficient to support germination. This supports the hypothesis that in vivo, quiescence at this developmental stage is induced and maintained by sequestration of water within the cotyledons.
Iron transport and storage within the seed coat and embryo of developing seeds of pea (Pisum sativumL.)
Authors: Marentes Eduardo , Grusak Michael A.
Published: September 2008

To understand the cellular processes related to iron transport and sequestration within the developing pea seed (Pisum sativum), total iron and ferritin iron were analysed in seed coat and embryo tissues of the iron-hyperaccumulating pea mutant, Sparkle [dgl, dgl], and its wild-type parent, cv. Sparkle. For plants grown hydroponically with 2 μM Fe, embryo Fe concentrations averaged 65 μg g−1dry weight in mature wild-type seeds and 163 μg g−1dry weight in maturedglseeds; iron concentrations were also higher indglseed coats. Extracted and electrophoretically separated seed proteins were probed with a polyclonal antibody raised against pea seed ferritin. In both genotypes, ferritin was detected in the embryo, but not in the seed coat. Ferritin iron accounted for 92% of the total iron in mature wild-type embryos, but only 42% of the total iron in maturedglembryos. Radiotracer studies using59Fe were used to characterize the movement of iron within the seed coat. Unequal distribution of59Fe in opposing sections taken from the two hemispheres of the seed coat demonstrated that iron was symplastically phloem unloaded. These results suggest that iron resides transiently within the nonvascular seed coat cells and that all cells at the inner surface of the seed coat may be involved in the release of iron to the embryo apoplast. However, the form of iron resident within the seed coat and/or taken up by the embryo is presently unknown.
Flavonoids in seeds and grains: physiological function, agronomic importance and the genetics of biosynthesis
Authors: Shirley Brenda Winkel
Published: September 2008

Flavonoids are secondary metabolites that are present at high levels in most plant seeds and grains. These compounds appear to play vital roles in defence against pathogens and predators and contribute to physiological functions such as seed maturation and dormancy. At the same time, particular subclasses of flavonoids, such as the proanthocyanidins (condensed tannins), negatively impact the use of seeds and grains in animal feed and can add undesirable qualities to food products for human consumption. This article presents an overview of investigations into the physiological and agronomic aspects of seed and grain flavonoids as well as a review of molecular genetic studies, particularly in maize,Arabidopsisand soybean, where mutants deficient in flavonoid biosynthesis provide useful tools for stydying the metabolic machinery underlying the accumulation of these compounds in reproductive structures.
Burial conditions affect light responses ofDatura feroxseeds
Authors: Botto Javier F. , Sánchez Rodolfo A. , Casal Jorge J.
Published: September 2008

The dormancy pattern of buried seeds ofDatura feroxwas studied by testing germination responses to red light (R), far-red light (FR) or darkness after exhumation at regular time intervals. The seeds were deeply dormant at the time of burial in winter. After three months (spring), exhumed seeds began to respond to an R pulse. Summer temperatures did not induce secondary dormancy. During winter of the second year, seed germination after an R pulse increased further; however, germination after an FR pulse or in darkness also increased and reached values close to R. Changes in seed germination after an R or an FR pulse and in darkness were studied in a factorial design experiment, combining different depths of burial (0.5, 5 and 10 cm), presence of vegetation (with or without vegetation canopies), and date of exhumation (4 or 7 months after burial). The seeds placed at 0.5 cm depth did not germinate in any light treatment. A very high sensitivity to light, indicated by the promotion of germination by an FR pulse compared to darkness, was exhibited only in seeds buried at 5 cm in a soil without vegetation. A typical R/FR reversible response was observed in seeds exhumed at 5 and 10 cm in almost all situations of burial; except in a soil without vegetation, at 10 cm depth, in late summer when even dark controls showed high germination. It is concluded that buried seeds ofD. feroxare released from dormancy in two steps, the first step during the spring of the first year and the second step during the subsequent winter. This process is not obviously controlled by summer temperatures. The acquisition of a very high sensitivity to light depends on vegetation cover and depth of burial, and thus it is predicted to be affected by agricultural practices.
Haemoglobin expression in germinating barley
Authors: Duff Stephen M.G. , Guy Phillip A. , Nie Xianzhou , Durnin Douglas C. , Hill Robert D.
Published: September 2008

Polyclonal antibodies to purified recombinant barley haemoglobin (Hb) have been raised in rabbits and used to investigate its expression in monocotyledonous plants. Very little or no Hb expression was observed in dry barley seeds but germination resulted in the expression of Hb which peaked at 2–3 days after imbibition. Hb expression was also observed in maize, wheat, wild oat andEchinochloa crus-galliseeds during germination. Dissection of tissues from the barley seedlings showed that most of the haemoglobin was expressed in the root and seed coat (aleurone layer), with very little in the coleoptile. Imbibition of half-seeds or excised embryos resulted in the expression of haemoglobin. ATP measurements of barley embryos showed that ATP levels quickly increase after imbibition. α-Amylase activity was also determined in embryos to correlate Hb expression with a well-characterized germination response. The results demonstrate that Hb expression is a normal consequence of germination.
Chlorophyll fluorescence of Brassica oleracea seeds as a non-destructive marker for seed maturity and seed performance
Authors: Jalink Henk , van der Schoor Rob , Frandas Angela , van Pijlen Jaap G. , Bino Raoul J.
Published: September 2008

A method is proposed for assessing the maturity and quality of seeds, based on measuring the amount of chlorophyll fluorescence (CF) signals of intact seeds. In general, the amount of chlorophyll is directly related to the degreening process and thus the maturity. Cabbage seeds (Brassica oleracea var. capitata) were separated into three subsamples based on the CF signals of the individual intact seeds. Seeds with the lowest amount of CF had the highest percentage of germination and normal seedlings. In a controlled deterioration test, the subsample with the lowest CF signal had slightly lower germination and normal seedling percentages than the non-treated seeds, whereas the seeds with the highest CF signals had much lower germination and normal seedling percentages. Advantages of the CF method for determining seed maturity and seed quality are its high sensitivity and fully non-destructive nature and the high speed at which the fluorescence is generated and measured.
Germination behaviour of Italian ryegrass in flooding pampa rangelands
Authors: Rodriguez Adriana M. , Jacobo Elizabeth J. , Deregibus V. Alejandro
Published: September 2008

Lolium multiflorum Lam., a winter annual grass species originating from the Mediterranean region, has become widespread in native grasslands of the flooding pampa (Argentina). The dynamics of dormancy release of L. multiflorum seeds in simulated natural conditions was studied. Dormancy was overcome by exposing imbibed seeds to mild cool temperatures (15°C or below) for brief periods (pre-chilling). After-ripening progressively released dormancy, at a higher rate in seeds that remained under the canopy (30/20°C) than those that were dry-stored (20°C). Germination was promoted by red light only when the after-ripening requirement was partially fulfilled or after pre-chilling treatment. These results provide useful knowledge for designing grazing strategies aimed at obtaining well-developed ryegrass canopy of high forage quality during winter and spring.
Outcome following, and impact of, prenatal identification of the candidates for the Norwood procedure
Authors: Fountain-Dommer Robin R , Bradley Scott M , Atz Andrew M , Stroud Martha R , Forbus Geoffrey A , Shirali Girish S
Published: September 2008

Objectives:Our study evaluates hospital survival following prenatal identification of candidates for the Norwood procedure, and the impact of prenatal diagnosis on survival, preoperative stability, and postoperative morbidity.Methods:We reviewed records of all patients who were identified prenatally as candidates for the Norwood procedure, and compared them to all postnatally diagnosed patients who underwent the Norwood procedure between August 1995 and May 2002.Results:Of the 98 patients studied, 45 (46%) were diagnosed prenatally. Of these, 35 underwent the Norwood procedure, 29 (83%) of who survived. Thus, 29 of 45 (64%) patients survived from prenatal diagnosis to discharge following the Norwood procedure. Of the 53 postnatally diagnosed patients who underwent the Norwood procedure, 42 (79%) survived. Prenatal diagnosis was not associated with improvement in survival, preoperative stability, or postoperative morbidity. By multivariate analysis, ascending aortic diameter equal to or greater than 2 mm (p = 0.01), and gestational age 36 weeks or greater (p = 0.01) independently predicted survival. Based on this, patients were stratified into groups at low risk, consisting of 69 patients, and at high risk, consisting of 19 patients. Prenatal diagnosis was unassociated with improved survival in either group. Results were unchanged when the analysis was restricted to patients with hypoplasia of the left heart.Conclusion:From the time of prenatal diagnosis, 64% of patients survived to discharge following the Norwood procedure. Prenatal diagnosis did not affect preoperative stability, survival or postoperative morbidity. This remained the case after stratifying patients by risk, or restricting analysis to patients with hypoplasia of the left heart. Ascending aortic diameter and gestational age independently predicted survival.
The clinical profile of Ebstein's malformation as seen from the fetus to the adult in 52 patients
Authors: Arizmendi Alejandro Flores , Pineda Luis Fernández , Jiménez Concepción Quero , Azcárate María Jesús Maître , Sarachaga Ignacio Herráiz , Urroz Elisa , de León Julio Pérez , Moya José Luis , Jiménez Manuel Quero
Published: September 2008

Ebstein's malformation of the tricuspid valve is a rare but complex congenital cardiac lesion characterised by a variable degree of dysplasia and displacement of the proximal attachments of its inferior and septal leaflets from the true atrioventricular junction. The aim of our retrospective study is to report the risk factors for mortality, and to determine the clinical profile as seen in 52 cases diagnosed in our service between 1978 and 2002, concentrating in particular on the outcome for the neonatal patient. There were 26 females and 26 males, and the age at presentation ranged from 30 weeks gestational age to 46 years. We found 23 associated cardiac anomalies in 20 cases. Of the patients, 11 patients (21%) died. Actuarial survival at 30 years was 65%. Predictors of death included fetal or neonatal presentation, presence of associated defects, a grade within the Celermajer index of 3 or 4, and a cardiothoracic ratio equal to or greater than 65%. The diagnosis was made in the neonatal period in 24 patients, nine of whom died. Of the 15 survivors, only 4 are free of symptoms. Surgical treatment was undertaken in 9 patients, with a mortality rate of 33% without late deaths, with all the survivors being in good condition. The mean period of follow-up for the 41 living patients was 16.5 years. An arrhythmia of variable severity appeared during the evolution of 27 patients (66%). At present, only 7 cases are in the functional class III or IV of the grading system of the New York Heart Association, but 25 patients (61%) needed some medical treatment, meanly for arrhythmic events. Thus, fetal and neonatal presentation of Ebstein's malformation is associated with a poor outcome. Moreover, the echocardiographic appearance, marked cardiomegaly, and the presence of associated lesions are all risk factors for mortality. Arrhythmia and need of medical treatment are common in older children and adults. Survival after surgical treatment is associated with a good outcome.
Myotonic dystrophy presenting as atrial flutter in childhood
Authors: Suda Kenji , Matsumura Masahiko , Hayashi Yuji
Published: September 2008

A 12-year-old boy presented with tachycardia and cardiomegaly. An electrocardiogram showed atrial flutter with a ventricular rate of 170 beats/min. The echocardiogram showed left ventricular dilation, with decreased contractility. Electromyography confirmed the diagnosis of myotonic dystrophy. The atrial flutter was converted to sinus rhythm by electroversion, leading to restoration of normal cardiac function. Our case illustrates that atrial flutter can be an early sign of the cardiac complications of myotonic dystrophy in childhood.
An obstructive bicuspid aortic valve in the setting of tetralogy of Fallot with pulmonary atresia: a rare combination
Authors: Ermis Cengiz , Gupta-Malhotra Monesha , Titus Jack L.
Published: September 2008

As far as we are aware, a bicuspid aortic valve has not previously been reported in the setting of tetralogy of Fallot and pulmonary atresia. We describe this association in a newborn who presented with a murmur and cyanosis. Echocardiography showed tetralogy of Fallot with pulmonary atresia, and also a moderately stenotic bicuspid aortic valve. The patient underwent open-heart surgery guided by transesophageal echocardiography. Postoperatively, there was only mild obstruction across both outflow tracts. We have also reviewed the pertinent data from our Jesse E. Edwards Registry of Cardiovascular Disease to establish the incidence of bicuspid aortic valve in the setting of obstruction of the right ventricular outflow tract, finding the association in no patients with pulmonary atresia and tetralogy of Fallot, in 0.7% of those with tetralogy of Fallot and pulmonary stenosis, but in 6.6% of those with pulmonary atresia and intact ventricular septum.
Price response of herd off-take under market liberalization in a developing cattle sector: panel analysis applied to Kenya's ranching
Authors: NYARIKI DICKSON M.
Published: September 2008

The influence of price, in view of macro-economic policy change and a set of other factors, on herd off-take rates from ranches in Kenya over a period of 17 years was assessed. An AR(1) equation, based on Nerlove's classical dynamic supply model, was derived and fitted to panel data using the Cochrane–Orcutt procedure. Pooling of data was done to circumvent data insufficiency, thereby improving the statistical power of the analysis. Results indicate that price change has had a significant effect on ranch herd off-take, and climatic factors also account for long-run off-take levels.
The story of the Chinese seals found in Ireland
Authors: GALAMBOS IMRE
Published: September 2008

In 1850, a paper was read before the Royal Historical Society of Ireland regarding a group of Chinese porcelain seals that had come to light during the previous eighty years in Ireland. In total there were about sixty seals which it was claimed had been discovered in various places throughout Ireland, ranging from Belfast all the way to Cork. In addition to their wide dispersion pattern, the seals were found in the strangest places – in an orchard, a cave, bogs, and so on. The discovery could not be easily explained at the time and when the inscriptions turned out to be written in the Chinese seal script, a number of fanciful hypotheses were advanced as to how these seals “of great antiquity” appeared in Ireland. According to these explanations, the seals were either brought over by the Phoenicians, or by ancient Irish tribes after their wanderings in China, or by mediaeval Irish monks travelling from the Middle East. All along, the emphasis was on the extent to which these artefacts corroborated Ireland's ancient connection with the Orient, an idea that was believed and promoted at the time by both Irish nationalists and English imperialists. Both sides, albeit from a different standpoint and driven by different motives, saw the Irish as a distinctly non-European culture, whose ancestors must have originated from distant lands far beyond the perimeters of western civilisation.
Medieval Egyptian Judaeo-Arabic Prescriptions (and the edition of three medical prescriptions)
Authors: LEV EFRAIM
Published: September 2008

The literature on medicine in medieval Muslim countries in general and in Egypt in particular is vast and detailed. Yet study and assessment of the practical aspects of medicine in the Mediterranean society of the Middle Ages requires examination of authentic, practical medical knowledge. At present this can be extracted mainly from the prescriptions found in the Cairo Genizah; these supply a different and valuable dimension. On the importance and the potential of research into the medical aspects of the Genizah documents, mainly prescriptions, Goitein wrote in 1971 that “these prescriptions have to be examined by experts in the history of medicine”.
Annual General Meeting 8th May 2008 President's Address
Authors: Stockwell A. J.
Published: September 2008

Fellows of the Society and guests. I thank the Honorary Treasurer for his report on the accounts and for his stewardship of the Society's finances during the year.
Impact of assembly, testing and launch operations on the airborne bacterial diversity within a spacecraft assembly facility clean-room
Authors: Newcombe David A. , La Duc Myron T. , Vaishampayan Parag , Venkateswaran Kasthuri
Published: September 2008

In an effort to minimize the probability of forward contamination of pristine extraterrestrial environments, the National Aeronautics and Space Administration requires that all US robotic spacecraft undergo assembly, testing and launch operations (ATLO) in controlled clean-room environments. This study examines the impact of ATLO activity on the microbial diversity and overall bioburden contained within the air of the clean-room facility in which the Mars Exploration Rovers (MERs) underwent final preparations for launch. Air samples were collected from several facility locations and traditional culture-based and molecular methodologies were used to measure microbial burden and diversity. Surprisingly, the greatest estimates of airborne bioburden, as derived from ATP content and cultivation assays, were observed prior to the commencement of MER ATLO activities. Furthermore, airborne microbial diversity gradually declined from the initiation of ATLO on through to launch. Proteobacterial sequences were common in 16S rDNA clone libraries. Conspicuously absent were members of the Firmicutes phylum, which includes the genusBacillus. In previous studies, species of this genus were repeatedly isolated from the surfaces of spacecraft and clean-room assembly facilities. Increased cleaning and maintenance initiated immediately prior to the start of ATLO activity could explain the observed declines in both airborne bioburden and microbial diversity.