Prolonged aerated hydration for improvement of seed quality in Brassica oleracea L.

Seeds of cauliflower cv. Hipop and Brussels sprouts cv. Asmer Aries were aged at 20% moisture content for 24 h; all seeds retained a germination of over 70% after ageing although the mean germination time increased. Prolonged aerated hydration for up to 32 h at 20°C followed drying resulted in improved performance of both unaged and aged cauliflower seeds and aged Brussels sprouts. Thus, all seed showed reductions in the mean germination time to the extent that after 32 h hydration the aged cauliflower seeds performed as well as high quality unaged seed. The improvement of aged seeds was also revealed an increase in germination after the controlled deterioration test following up to 24 h (cauliflower) or 32 h (Brussels sprouts) aerated hydration. This increase was indicative of a decrease in the extent of deterioration present after aerated hydration. Deleterious effects of prolonged hydration were observed in Brussels sprouts after 32 h although these may be explained desiccation injury after treatment since radicle emergence had occurred during hydration. The improvements in seed performance may be explained the activation of metabolic repair occurring during the early part of the hydration period therereducing the extent of deterioration that has been sustained during ageing, with further improvements due to the advancement of the germination process.     

The hydration of nucleic acid duplexes as assessed by a combination of volumetric and structural techniques

Using high precision densimetric and ultrasonic measurements, we have determined, at 25°C, the apparent molar volumes ΦV and the apparent molar compressibilities ΦK_S of four nucleic acid duplexes—namely, the DNA duplex, poly(dIdC)poly(dIdC); the RNA duplex, poly(rA)poly(rU); and the two DNA/RNA hybrid duplexes, poly(rA)poly(dT) and poly(dA)poly(rU). Using available fiber diffraction data on these duplexes, we have calculated the molecular volumes as well as the solvent‐accessible surface areas of the constituent charged, polar, and nonpolar atomic groups. We found that the hydration properties of these nucleic acid duplexes do not correlate with the extent and the chemical nature of the solvent‐exposed surfaces, thereby suggesting a more specific set of duplex–water interactions beyond general solvation effects. A comparative analysis of our volumetric data on the four duplexes, in conjunction with available structural information, suggests the following features of duplex hydration: (a) The four duplexes exhibit different degrees of hydration, in the order poly(dIdC)poly(dIdC) > poly(dGdC)poly(dGdC) > poly(dAdT)poly(dAdT) ≈ poly(dA)poly(dT). (b) Repetitive AT and IC sequences within a duplex are solvated beyond general effects by a spine of hydration in the minor groove, with this sequence‐specific water network involving about 8 additional water molecules from the second and, perhaps, even the third hydration layers. (c) Repetitive GC and IC sequences within a duplex are solvated beyond general effects by a “patch of hydration” in the major groove, with this water network involving about 13 additional water molecules from the second and, perhaps, even the third hydration layers. (d) Random sequence, polymeric DNA duplexes, which statistically lack extended regions of repetitive AT, GC, or IC sequences, do not experience such specific enhancements of hydration. Consequently, consistent with our previous observations (T. V. Chalikian, A. P. Sarvazyan, G. E. Plum, and K. J. Breslauer, Biochemistry, 1994, Vol. 33, pp. 2394–2401), duplexes with approximately 50% AT content exhibit the weakest hydration, while an increase or decrease from this AT content causes enhancement of hydration, either due to stronger hydration of the minor groove (an increase in AT content) or due to stronger hydration of the major groove (an increase in GC content). (e) In dilute aqueous solutions, a B‐DNA duplex is more hydrated than an A‐DNA duplex, a volumetric‐based conclusion that is in agreement with previous results obtained on crystals, fibers, and DNA solutions in organic solvent–water mixtures. (f) the A‐like, RNA duplex poly(rA)poly(rU) and the structurally similar A‐like, hybrid duplex poly(rA)poly(dT), exhibit similar hydration properties, while the structurally distinct A‐like, hybrid duplex poly(rA)poly(dT) and non‐A‐like, hybrid duplex poly(dA)poly(rU) exhibit differential hydration properties, consistent with structural features dictating hydration characteristics. We discuss how volumetric characterizations, in conjunction with structural studies, can be used to describe, define, and resolve the general and sequence/conformation‐specific hydration properties of nucleic acid duplexes. © 1999 John Wiley & Sons, Inc. Biopoly 50: 459–471, 1999     

The role of seed coats in seed viability

The seed coat is the seed’s primary defense against adverse environmental conditions. A hard seed coat protects the seed not only from mechanical stress but also from microorganism invasion and from temperature and humidity fluctuations during storage. Phenolic compounds in the seed coat contribute to seed hardness and inhibition of microorganism growth. During germination, the seed coat protects the seed from hydration stress and electrolyte leakage.     

Ageing in vivo and neuraminidase treatment of rabbit erythrocytes: influence on half-life as assessed by 51Cr labelling.

Old and young rabbit erythrocytes, separated by centrifugation, contained different respective activities of glucose-6-phosphate dehydrogenase, pyruvate kinase and acetylcholinesterase, and different quantities of stromal sialic acid. A systematic study of the survival rate of young and old erythrocytes incubated with different amounts of Vibrio cholerae neuraminidase is described. The half-life of intact old erythrocytes is significantly shorter than that of young erythrocytes with a similar sialic acid content.     

The influence of hydration on the conformation of lysozyme studied by solid-state 13C-nmr spectroscopy

¹³C proton decoupled cross-polarization magic-angle spinning nmr spectra of lysozyme are reported as a function of hydration. Increases in hydration level enhance the resolution of the spectra, particularly in the aliphatic region, but has no significant effect on either the rotating frame proton spin–lattice relaxation time or the cross-relaxation time. The enhancement in spectral resolution with hydration is attributed to a decrease in the distribution of isotropic chemical shifts, which reflects a decrease in the distribution of conformational states sampled by the protein. Changes in the distribution of isotropic chemical shifts occur after the addition of water to the charged groups as coverage of the polar side chains and peptide groups takes place. The onset of this behavior occurs at a hydration level of about, 0.1–0.2 g water/g protein and is largely complete at about 0.3 g water/g protein, the same hydration range where changes in the heat capacity are observed. That hydrogen exchange of buried protons can occur at hydration levels significantly lower than those at which changes in the distribution of conformational states are first observed suggests that some motions that mediate exchange are already present in the dry protein. The preservation of efficient dipolar coupling indicates that the conformational rearrangements that do-occur on hydration are small and do not involve any significant overall expansion of free volume or weakening of interactions that would increase the reorientational freedom of protein groups. © 1993 John Wiley & Sons, Inc.     

Counterion condensation as saturation effect under the influence of ion hydration

Polyelectrolyte solutions are often described by structural theories. These theories in some cases yield values for the counterion concentration at the charged monomer surface that exceed the saturation concentration. This means a change of the ion properties due to ion immobilization or ion condensation in close vicinity to the polymer chain. The extent of this counterion condensation (CIC) and the respective surface potential are calculated from the saturation concentrations of the electrolyte involved including the influence of ion hydration on the effective dielectric number. In this paper, we shall consider all these influences by a fundamental differential equation and a set of explicit formulae yielding quantitative expressions without linearization. All calculations are based on the abstraction of an idealized elementary cell.     

The influence of cone age on the relative longevity of Banksia seeds

Background and Aims

Serotiny is common in the genus Banksia, so any seed collection is likely to be comprised of seeds that were produced in many different years. This study aimed to determine the impact of cone age and degree of serotiny on longevity in ex situ storage.

Methods

Cones of identifiable age classes were collected from three species of Banksia. Seeds were extracted from cones and the degree of serotiny calculated. An estimate of initial viability (K_i), the time for viability to fall by one probit (σ) and the relative longevity of seeds (p₅₀) for each species and cone age class was determined using a comparative longevity test (50 °C, 63 % relative humidity).

Key Results

The degree of serotiny ranged from moderate (7·9) for Banksia attenuata to strong (40·4) for B. hookeriana. Survival curves for all seed age classes within each species could be described by regressions with a common slope (1/σ), but with different values for K_i. The time taken for viability to fall by one probit (σ) could be described by a common value (29·1 d) for all three species.

Conclusions

Differences in seed longevity between cone age classes and species was related to variation in initial viability (K_i) rather than to differences in σ. While targeting the youngest mature seed cohort on a plant will maximize the viability of seeds collected, a wide range of age classes should be collected (but stored as separate cohorts if possible) for quality conservation/restoration seed collections where genetic diversity is important.     

The influence of metabolic rate on longevity in the nematode Caenorhabditis elegans

Much of the recent interest in aging research is due to the discovery of genes in a variety of model organisms that appear to modulate aging. A large amount of research has focused on the use of such long-lived mutants to examine the fundamental causes of aging. While model organisms do offer many advantages for studying aging, it also critical to consider the limitations of these systems. In particular, ectothermic (poikilothermic) organisms can tolerate a much larger metabolic depression than humans. Thus, considering only chronological longevity when assaying for long-lived mutants provides a limited perspective on the mechanisms by which longevity is increased. In order to provide true insight into the aging process additional physiological processes, such as metabolic rate, must also be assayed. This is especially true in the nematode Caenorhabditis elegans, which can naturally enter into a metabolically reduced state in which it survives many times longer than its usual lifetime. Currently it is seen as controversial if long-lived C. elegans mutants retain normal metabolic function. Resolving this issue requires accurately measuring the metabolic rate of C. elegans under conditions that minimize environmental stress. Additionally, the relatively small size of C. elegans requires the use of sensitive methodologies when determining metabolic rates. Several studies indicating that long-lived C. elegans mutants have normal metabolic rates may be flawed due to the use of inappropriate measurement conditions and techniques. Comparisons of metabolic rate between long-lived and wild-type C. elegans under more optimized conditions indicate that the extended longevity of at least some long-lived C. elegans mutants may be due to a reduction in metabolic rate, rather than an alteration of a metabolically independent genetic mechanism specific to aging.     

The influence of metabolic syndrome and chronic kidney disease on hemorheology assessed by the microchannel method

Metabolic syndrome (MetS) and chronic kidney disease (CKD) are individual risk factors for cardiovascular disease (CVD). Abnormal hemorheology may be associated with CVD in both disorders. The present study investigated the impact of MetS and CKD on hemorheology. We studied 138 adults (women/men=63/75, mean age=52.2 years), who included 87 participants with MetS and 33 with CKD. The hemorheology was assessed by the index of 'whole blood passage time (WBPT)' using the Micro Channel array Flow ANalyzer (MC-FAN). The WBPT values of MetS participants were significantly higher than those of non-MetS participants (52.5±13.1 vs. 46.3±7.7 sec, p=0.03). The WBPT values of CKD participants were significantly higher than those of non- CKD (55.5±12.7 vs. 48.6±11.0 sec, p=0.003). The significant influence of MetS and CKD on WBPT was qualified by their effect modification to WBPT (p=0.04). There was a significantly greater influence of the combination of MetS and CKD on WBPT (59.9±13.4 sec) in comparison to the influence of non-MetS and CKD (46.6±3.5) or non-CKD and MetS (50.0±12.2). The influence of the combination of MetS and CKD was clearer in men, relative to women. Abnormal hemorheology as assessed using MC-FAN may be enhanced by the combination of MetS and CKD.     

The influence of hydration on the conformation of bovine serum albumin studied by solid-state 13C-nmr spectroscopy

¹³C proton-decoupled cross-polarization magic-angle spinning nmr spectra of bovine serum albumin are reported as a function of hydration. Increases in hydration level enhance the resolution of the peak centered at about 40 ppm but has little or no effect on the other spectral peaks. Hydration has little effect on either the rotating frame proton spin–lattice relaxation time or the cross-relaxation time for any of the peaks, suggesting that the efficiency of dipolar coupling is largely preserved on hydration of the protein. Resolution enhancement of the peak at 40 ppm is not understood, but possible sources of the behavior include a decrease in the line width of contributing resonances from lysine ε carbons due to increased motional averaging on hydration, reordering of disulfide bridges, and titration shifts induced by hydration. Hydration of bovine serum albumin appears to have little effect on the distribution of conformations sampled by the protein so that the broad distribution of conformations observed in the dry state is also observed in the fully hydrated state. This is in contrast to lysozyme where significant ordering of the conformation is seen on hydration. © 1993 John Wiley & Sons, Inc.     

The influence of the environment on seed and seedling mortality

Summary 1. Some of the differences between various techniques of cold testing corn have been examined. No significant difference was found between the results of cold testing by exposing grains to temperatures between 3° and 20°C after 0 and 2 days pre-treatment at 20°C (Erratic results are reported for the mortality induced by exposure of pre-germinated grains to 0°C).2. Mortality in the cold test increased with time of exposure up to 10 days (the longest period involved in the experiments). Varietal differences between Wisconsin 275 and Virginian White Horsetooth became more pronounced with increased period of exposure.3. There was relatively little change in mortality between the cold tests conducted at 3° and 8°C compared to the large change between 8° and 15°C. It is suggested that the temperature of the test should be standardised within the lower range, where small uncontrolled variations in temperature will have least effect on the tests. Attention is called to the fluctuation in soil temperature which may be caused by variations in atmospheric humidity in a constant temperature room.4. Comparison of cold tests made (a) in jam jars of soil with subsequent sowing of the grains in damp sand at a higher temperature with (b) tests involving grain treated in boxes of soil in which the grains remainin situ through all phases of the test, reveal no differences due to these contrasted procedures.     

Season and social environment influence the membrane integrity of ejaculated boar spermatozoa as assessed by ouabain sensitivity

Eight adult Landrace boars were housed for 12 months in one of two social environments. Socially nonrestricted boars were penned near estrual females and socially restricted boars were penned behind solid walls to eliminate visual and physical contact with other pigs. All animals were subjected to natural changes in day length. The sensitivity of ejaculated spermatozoa to ouabain (in inhibitor of Na+-K+ ATPase) was determined on 4 consecutive weeks in November, March-April, and July-August. Semen was diluted in Tyrode's solution (pH 7.4) with and without 10(-3) M ouabain. Duplicate samples of control and ouabain-treated spermatozoa were incubated at 37 degrees C for 4 h, and percent motile sperm, motility type, and motility index (combination of percent and type) were determined at hourly intervals. Ouabain-induced decreases in most motility parameters varied with season (season X treatment, P less than 0.05). At hour 4, induced decreases in percent motile sperm were more pronounced in November and July-August than in March-April for socially nonrestricted boars. Decreases in motility type were greater (P less than 0.05) in November and July-August than in March-April for socially nonrestricted boars and were greater (P less than 0.01) in November than in July-August for restricted boars. In March-April motility type decreased (P less than 0.01) to a greater extent for socially restricted vs. nonrestricted boars. Similar season and social environment differences were observed for motility index values. Given the interrelationships between ouabain sensitivity, the functional integrity of sperm cells, and fertilizing capacity, season and social environment differences in ouabain-induced motility depression probably reflect qualitative changes in boar spermatozoa.     

The influence of spatial heterogeneity on regeneration by seed in a limestone grassland

Abstract. The spatial distribution of seedlings in fertilized and non-fertilized grassland patches (1 m x 2 m) was examined in alvar vegetation on the island of Öland, Sweden. We established whether variation in seedling distribution in grassland patches reflects the distribution of conspecific adults. We also established the significance of microsite turf attributes for prediction of seedling distribution at a small scale (10 cm x 10 cm), and the significance of conspecific adults abundance, assemblage of adult species and cover of lichens, mosses, litter and bare ground. Our results indicate that fertilization reduces the importance of regeneration by seed of perennial species and enhances seedling recruitment of winter annuals and biennials. At the patch scale, enrichment does not affect species richness. Community patchiness contributes to the maintenance of diversity by providing a variety of environments with differential regeneration of the component species. Cover of lichens, mosses, litter and bare ground, accounts, in part, for the spatial variation in seedling numbers of certain species. The strong association of seedlings of some species with conspecific adults indicates that limitations in dispersal and/or the occurrence of a more suitable environment for emergence and/or establishment close to conspecific adult plants are likely to constrain the spatial distribution of new individuals in many cases. For other species, the lack of association of seedling densities with the cover of their conspecific adults, suggests that long-distance dispersal or a long-lived seed bank can play a role in counteracting the effect of short-distance dispersal.     

The influence of monoterpenoids and phenol derivatives on Drosophila melanogaster viability

The present study investigated the effect of mono/bicyclic terpenoids and phenol derivatives on the viability of Drosophila melanogaster and their influence on the multiplication of the nuclear genome. The fertility and viability of fruit flies were assessed after oral administration and inhalation exposure of compounds 1–5: guaiacol, eugenol, borneol, menthol and carvacrol. The influence of terpenoids and phenols on the degree of chromosomes polyteny in salivary gland cells of D. melanogaster larvae was determined. Among all tested compounds, carvacrol demonstrated the most significant impact on fecundity and insect survival when inhaled or adding to the culture medium. Oral administration of carvacrol had an impact on giant chromosomes increasing their average level of chromosome polyteny degree while eugenol adding to culture medium had the opposite effect. The possible mechanism of terpenoids and phenols action is discussed.