Association between contrasting methane emissions of two rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) cultivars from the irrigated agroecosystem of northeast India and their growth and photosynthetic characteristics

Over two consecutive years in the North Bank Plain Zone of Assam, India, during the spring growing season (February–June) of- 2006 and 2007 we examined effects of morpho-physiological characteristics of rice (Oryza sativa L.) plants in relation to methane (CH₄) emission from paddy fields. Traditional cultivar “Agni” and modern improved cultivar “Ranjit” were grown in light textured loamy soil under irrigation. A higher seasonal integrated methane flux (E _sif) was recorded from “Agni” compared to “Ranjit”. Both cultivars exhibited an emission peak during active vegetative growth and a second peak at panicle initiation. Leaf and tiller number, leaf area, length, and volume of root were greater in “Agni”, but grain yield and yield-related parameters such as increased photosynthate partitioning to panicles at the expense of roots were greater in “Ranjit”. “Ranjit” also photosynthesed faster than “Agni” during panicle development but slower than “Agni” at tillering. In both the years, a higher soil organic carbon content was recorded in plots of “Agni”. Our results suggest that in “Agni” enhanced diversion of photosynthate to roots resulted in more substrate being available to methanogenic bacteria in the rhizosphere. Additionally, the more extensive vegetative growth of this cultivar may enhance methane transport from the soil to the above-ground atmosphere.     

Analysis of a mathematical model for the growth of tumors

 In this paper we study a recently proposed model for the growth of a nonnecrotic, vascularized tumor. The model is in the form of a free-boundary problem whereby the tumor grows (or shrinks) due to cell proliferation or death according to the level of a diffusing nutrient concentration. The tumor is assumed to be spherically symmetric, and its boundary is an unknown function r=s(t). We concentrate on the case where at the boundary of the tumor the birth rate of cells exceeds their death rate, a necessary condition for the existence of a unique stationary solution with radius r=R ₀ (which depends on the various parameters of the problem). Denoting by c the quotient of the diffusion time scale to the tumor doubling time scale, so that c is small, we rigorously prove that (i) lim inf _t→∞ s(t)>0, i.e. once engendered, tumors persist in time. Indeed, we further show that (ii) If c is sufficiently small then s(t)→R ₀ exponentially fast as t→∞, i.e. the steady state solution is globally asymptotically stable. Further, (iii) If c is not “sufficiently small” but is smaller than some constant γ determined explicitly by the parameters of the problem, then lim sup _t→∞ s(t)<∞; if however c is “somewhat” larger than γ then generally s(t) does not remain bounded and, in fact, s(t)→∞ exponentially fast as t→∞. Received: 25 February 1998 / Revised version: 30 April 1998     

Production of methanethiol and volatile sulfur compounds by the archaeon “Ferroplasma acidarmanus”

Acidophiles are typically isolated from sulfate-rich ecological niches yet the role of sulfur metabolism in their growth and survival is poorly defined. Studies of heterotrophically grown “Ferroplasma acidarmanus” showed that its growth requires a minimum of 100 mM of a sulfate-containing salt. Headspace gas analyses by GC/MS determined that the volatile sulfur compound emitted by active “F. acidarmanus” cultures is methanethiol. In “F. acidarmanus” cultures grown either heterotrophically or chemolithotrophically, methanethiol was produced constitutively. Radiotracer studies with ³⁵S-labeled methionine, cysteine, and sulfate showed that all three were used in methanethiol production. Additionally, ³H-labeled methionine was incorporated into methanethiol and was probably used as a methyl-group donor. Methanethiol production in whole cell lysates supplied with SO₃²⁻ indicated that NADPH-dependant sulfite reductase and methyltransferase activities were present. Cell lysates also contained enzymatic activity for methionine-γ-lyase that cleaved the side chain of either methionine to form methanethiol or cysteine to produce H₂S. Since methanethiol was detected from the degradation of cysteine, it is likely that sulfide was methylated by a thiol methyltransferase. Collectively, these data demonstrate that “F. acidarmanus” produces methanethiol through the metabolism of methionine, cysteine, or sulfate. This is the first report of a methanethiol-producing acidophile, thus identifying a new contributor to the global sulfur cycle.     

Continuous cultures of tomato and citron roots in vitro

Summary Initial trials with tomato-root cultures disclosed the desirability of employing a gently agitated liquid medium containing iron in the chelated form. For the normal cultivars “Ace” and “Tropic”, subcultures were best achieved by utilizing sectors that possessed one or more newly emerged laterals. Continuous cultures of a nonlateral-forming tomato mutant, “Diageotropica”, and of citron were accomplished by subculturing tips of the elongating primary roots. The tomato roots were cultured in White's medium with the Fe₂(SO₄)₃ replaced by 0.03 mM NaFeEDTA. Sustained growth of citron-root tips necessitated the use of a medium containing Murashige and Skoog salts, 7.5% sucrose, 100 mg per I each of citric acid and thiamine HCl, and 5000 mg per li-inositol. The success with citron-root cultures was extendable to all cultivars ofC. medica L., but not to otherCitrus species relatives. Both citron and “Diageotropica” root cultures manifested undiminished elongation through repeated subcultures; but neither produced laterals in response to any cultural treatments. Research was supported in part by National Science Foundation Grant OIP75-10390 and Elvenia J. Slosson Fellowship in Ornamental Horticulture.     

Correlations between the psychological peculiarities of an individual and the efficacy of a single neurofeedback session (by the EEG characteristics)

Modifications of different EEG rhythms induced by a single neurofeedback session (by the EEG characteristics) directed toward an increase in the ratio of the spectral powers (SPs) of the α vs θ oscillations were compared with the psychological characteristics of the tested subjects (the group included 30 persons). A generally accepted neurofeedback technique was used; the intensity of acoustic white noise served as the feedback signal. EEG potentials were recorded from the C3 and C4 leads. Psychological testing was carried out using Eysenck’s (EPQ), Rusalov’s (OST), and (16 PF) questionnaires. The directions of changes in the SPs of EEG frequency components were found to significantly correlate with some individuality-related peculiarities of the tested subjects. The SP of the δ rhythm correlated with the EPQ scale “neuroticism,” OST scale “social plasticity,” and 16 PF factors H (“parmia”), I (“premsia”), and Q₃ (“self-control of behavior”). The SP of the θ component demonstrated correlations with the OST scales “ergisity,” “plasticity,” and “social temp” and with 16 PF factors M (“autia”), Q₄ (“frustration”), and Q1 (“exvia”). The SP of the α rhythm correlated with 16 PF factors Q₃ (“self-control of behavior”), G (“strength of superEgo”), O (“hypothymia”), L (“protension”), and N (“shrewdness”). The SP of the β rhythm correlated with the OST scale “emotionality,” while that of the γ rhythm showed correlations with the 16 PF indices L (“protension”) and M (“autia”). Changes in the ratio of the α vs θ SPs correlated with the EPQ scale “neuroticism.” Thus, our data confirm the statement that a high individual variability of the results of a single (first in the series) neurofeedback session is to a great extent related to peculiarities of the individual psychological pattern of the subject. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 239–247, May–June, 2006.     

Study of tree architecture of apple (<Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">domestica</Emphasis> Borkh.) by QTL analysis of growth traits

Apple tree architecture is naturally very diverse, but for fruit production, certain tree habits are more desirable than others. Here we describe the results of a QTL analysis performed to study the genetic control of growth traits in apple. This was carried out on the progeny of a cross between two apple cultivars of contrasting tree architectures. “Telamon” has a columnar tree form and “Braeburn” has a more standard, “normal” growth habit. The growth traits were measured on the F ₁ seedlings of the Telamon × Braeburn population for two consecutive years of growth on own roots and for the first year of growth on M9 rootstock. QTL analysis was carried out using either the Kruskal–Wallis method or the Multiple QTL Method. For all but one growth characteristic, significant QTLs were detected. A major cluster of QTLs was located in the Co gene region of “Telamon”, confirming the major influence of the Co gene on tree architecture, although this influence changed as the plant material aged and was generally more pronounced for rootstock-grown plants. Additional QTL results suggest the occurrence of genes with pleiotropic effects on tree architecture. The observed QTL instability over different years and for different root systems indicates that the genetic control of tree architecture is largely influenced by environmental factors and probably changes as the tree matures. Finally, a major influence of the root system on all the traits determining tree architecture was clearly demonstrated.     

Specific Phage-Displayed Peptides Binding to Tumor Vasculature

Tumor growth, progression and metastasis are critically dependent on blood supply, which has received increased attention as a potential target of new anticancer therapies. Antiangiogenic therapy to limit and even reverse the growth of tumors is under investigation and showing promise. Moreover, tumor vascular express specific surface proteins (“vascular zip codes”), not present in resting blood vessels of normal tissues, are suitable for targeting purposes. The specific “vascular zip codes” can be identified by screening phage-displayed peptide library in vivo. This technology is simple but powerful, providing the advantages of selectivity of action plus improved accessibility and efficacy. To date, a variety of tumor-homing peptides have been isolated in this method, and most of the peptides have been used for targeting devices to concentrate drugs and other therapeutic materials to tumors. Such a targeting strategy can decrease toxicity and increase the therapeutic efficacy of the drug.Dr.Yu Han and Dr. Liu Hong contributed equally to this study.     

Estimation of relative contribution of “mobile phycobilisome” and “energy spillover” in the light–dark induced state transition in Spirulina platensis

Previously, it was clarified that phycobilisome (PBS) mobility and energy spillover were both involved in light-to-dark induced state transitions of intact Spirulina platensis cells. In this work, by taking advantage of the characteristic fluorescence spectra of photosystem I (PSI) trimers and monomers as indicators, the relative contributions for the “mobile PBS” and “energy spillover” are quantitatively estimated by separating the fluorescence contribution of PBS mobility from that of PSI oligomeric change. Above the phase transition temperature (T _PT) of the membrane lipids, the relative proportion of the contributions is invariable with 65% of “mobile PBS” and 35% of “energy spillover”. Below T _PT, the proportion for the “mobile PBS” becomes larger under lowering temperature even reaching 95% with 5% “energy spillover” at 0°C. It is known that lower temperature leads to a further light state due to a more reduced or oxidized PQ pool. Based on the current result, it can be deduced that disequilibrium of the redox state of the PQ pool will trigger PBS movement instead of change in the PSI oligomeric state.     

pH-Induced Molten Globule State of <Emphasis Type="Italic">Rhizopus niveus</Emphasis> Lipase is More Resistant Against Thermal and Chemical Denaturation Than Its Native State

Here, we have characterized four pH-dependent states: alkaline state, “B” (pH 9.0), native state, “N” (pH 7.4), acid-induced state, “A” (pH 2.2) and molten globule state, “MG” (pH 1.8) of Rhizopus niveus lipase (RNL) by CD, tryptophanyl fluorescence, ANS binding, DLS, and enzyme activity assay. This “MG” state lacks catalytic activity and tertiary structure but it has native-like significant secondary structure. The “R _h” of all the four states of RNL obtained from DLS study suggests that the molecular compactness of the protein increases as the pH of solution decreases. Kinetic analysis of RNL shows that it has maximum catalytic efficiency at state “B” which is 15-fold higher than state “N.” The CD and tryptophanyl fluorescence studies of RNL on GuHCl and temperature-induced unfolding reveal that the “MG” state is more stable than the other states. The DSC endotherms of RNL obtained at pH 9.0, 7.4, and 2.2 were with two transitions, while at pH 1.8 it showed only a single transition.     

A quantum-theoretic approach to enzyme specificity: Proposals for a new type of biochemical control mechanism

A quantum-theoretic approach to the problem of enzymic specificity is presented. The concept of a “measuring system” analogized with the enzyme is utilized. Along these lines a quantum mechanical hypothesis for the mechanism of enzyme reactions was advanced (Enzymologia,35, 117–130, 1968). In the measuring process an ℐ-observable, linked to the proper values of the substrate'sA ₁...A _m observables will indicate the state of the measuring apparatus. On the corresponding Hilbert space of the enzymesubstrate complexH _ES , through the respective statistical operatorU _ES we get a “state” vector [s, a]. Theng:Γ _S xΓ _E →Γ _ES , that is, to an oriented pair 〈s, a〉 ∈Γ _S xΓ _E will correspond a “state” vector [s, a], and to a proper valuei _k of ℐ will correspond, throughg, the respective equivalence classes of Г-spaces. Introducing the concept of enzyme-substrate complex entropyL _ES , a theorem is demonstrated asserting thatL _S =L _ES -L _E + 1/2kn wheren is the number of the degrees of freedom which may fluctuate. The values ofL _ES are denoted “specific values,” and it is demonstrated that a microphysical systemS may be a substrate specific forE, if and only if it can realize one of theL _ES specific values. Along these lines a model of a stochastic process for the enzymic reaction is constructed, and the set of Kolmogorov equations for the respective probabilities is derived. When a “perturbation” is induced in our model, an interesting prediction concerning the fluctuations in the kinetics of the corresponding enzyme is obtained. A relevant experimental proof ensued from these theoretical considerations. When a “gentle perturbation” was induced in a substrate by mild X-ray or UV-irradiations, an interesting oscillatory behavior of enzymic activity was recorded. A biochemical control mechanism is constructed (a simple “flip-flop” type) utilizing nonoverlapping oscillations in the activity of two enzymes at a key metabolic intermediate level. Eventually, a relevant experimental proof for the respective control model is presented.     

Salt tolerance in Lycopersicon spp. VII. Pleiotropic action of genes controlling earliness on fruit yield

 The change from vegetative to reproductive development (earliness) in Lycopersicon chesmannii line L2 was delayed for 20 weeks when compared to other Lycopersicon species under greenhouse conditions. The interspecific hybrid of L. chesmannii L2 and L. esculentum E9, a cherry tomato cultivar, also showed this delay in reproductive development. The distribution of this character in the F₂-derived population showed a bimodal shape, plants could be scored easily as “early” or “late” in two nutrient conditions (optimum and high salinity). A QTL with major effects on earliness was detected in salinity, which explained 35.6% of the phenotypic variation. The effect of this QTL greatly diminished under control conditions, indicating differences in the genetic control of earliness between treatments. ACC synthase or phytochrome B2 are the products of candidate genes for such a major QTL. Other QTLs with minor effects, and epistatic interactions, are also involved in earliness under both conditions. A “late” F₂ subpopulation yielded twice as much as an “early” F₂; conversely, “early” plants were taller than “late” plants, regardless of the treatment. QTL analysis, carried out in both subpopulations, showed that yield differences may be explained by chesmannii alleles showing negative additive effects at some QTLs only in the “early” subpopulation. The effect of population subdivision on QTL analysis was investigated by computer simulations to show sample-size or random effects; thus, important pleiotropic or regulatory effects of genes controlling earliness on yield that affect QTL analysis, have been reveiled. Therefore alleles controlling earliness in L. chesmannii have to be taken into account for a more efficient utilization of the genetic resources of this species. Received: 30 June 1998 / Accepted: 31 August 1998     

Age changes of the carpal bones in macaques: Application of the fourier analysis on the radiographs

A method based on the Fourier analysis is proposed, which describes and analyzes the contour morphology of carpal bones by separating morphology into factors of shape and size. Here, “size” refers to the average diameter of the contour. The “shape” is expressed byshape factors which are derived from the Fourier series and the “shape” of a monkey is expressed by ashape index which is calculated fromshape factors. The age change in the morphology of the lunate and capitate ofMacaca fuscata fuscata was analyzed by this method. The development of “shape” approximately completes by 3 years of age, whereas increase in “size” begins its spurt at that age as do body weight and anterior trunk length. By applying this method to other macaque species, it was found thatM. mulatta, M. f. yakui andM. cyclopis exhibit similar patterns of growth and development of carpal bones to those ofM. f. fuscata. Patterns found inM. fascicularis differ in that its bones develop faster than in the other macaques with respect to the “shape,” but remain small with respect to the “size.”     

Low voltage-activated Ca2+ conductances in thalamic neurons

Low voltage-activated (LVA) Ca²⁺ conductances were characterized in the neurons of the associative laterodorsal (LD) thalamic nucleus in rat brain slices and in enzymatically isolated thalamic units using electrophysiological techniques. Voltage dependence, kinetics of inactivation, pharmacology, and selectivity of the LVA current in the thalamic neurons from animals older than 14 postnatal days were consistent with the existence of two, “fast” and “slow,” subtypes of LVA Ca²⁺ channels. “Slow” LVA current in enzymatically isolated thalamic neurons was much less prominent, compared with that in slice neurons, suggesting that respective channels are predominatly located on the distal dendrites. “Fast” Ca²⁺ channels were sensitive to nifedipine (K _d−2.6 μM) and La³⁺ (K _d−1.0 mM), whereas “slow” Ca²⁺ channels were sensitive to Ni²⁺ (25 μM). Selectivity of the “fast” Ca²⁺ channels was similar to that found for the LVA Ca²⁺ channels in other preparations (I _Ca:I _Sr:I _Ba−1.0: 1.23: 0.94), while selectivity of the “slow” Ca²⁺ channels more resembled selectivity of the HVA Ca²⁺ channels (I _Ca:I _Sr:I _Ba−1.0: 2.5: 3.4).     

<Emphasis Type="Italic">In Vitro</Emphasis>–<Emphasis Type="Italic">In Vivo</Emphasis> Correlation for Gliclazide Immediate-Release Tablets Based on Mechanistic Absorption Simulation

The aim of this study was to develop a drug-specific absorption model for gliclazide (GLK) using mechanistic gastrointestinal simulation technology (GIST) implemented in GastroPlus^TM software package. A range of experimentally determined, in silico predicted or literature data were used as input parameters. Experimentally determined pH-solubility profile was used for all simulations. The human jejunum effective permeability (P _eff) value was estimated on the basis of in vitro measured Caco-2 permeability (literature data). The required PK inputs were taken from the literature. The results of the simulations were compared with actual clinical data and revealed that the GIST-model gave accurate prediction of gliclazide oral absorption. The generated absorption model provided the target in vivo dissolution profile for in vitro–in vivo correlation and identification of biorelevant dissolution specification for GLK immediate-release (IR) tablets. A set of virtual in vitro data was used for correlation purposes. The obtained results suggest that dissolution specification of more than 85% GLK dissolved in 60 min may be considered as “biorelevant” dissolution acceptance criteria for GLK IR tablets.     

Genetic control of aluminium tolerance in rye (Secale cereale L.)

 Aluminium (Al) tolerance in roots of two cultivars (“Ailés” and “JNK”) and two inbred lines (“Riodeva” and “Pool”) of rye was studied using intact roots immersed in a nutrient solution at a controlled pH and temperature. Both the cultivars and the inbred lines analysed showed high Al tolerance, this character being under multigenic control. The inbred line “Riodeva” was sensitive (non-telerant) at a concentration of 150 μM, whereas the “Ailes” cultivar showed the highest level of Al tolerance at this concentration. The segregation of aluminium-tolerance genes and several isozyme loci in different F₁s, F₂s and backcrosses between plants of “Ailés” and “Riodeva” were also studied. The segregation ratios obtained for aluminium tolerance in the F₂s analysed were 3 : 1 and 15 : 1 (tolerant : non-tolerant) while in backcrosses they were 1 : 1 and 3 : 1. These results indicated that Al tolerance is controlled by, at least, two major dominant and independent loci in rye (Alt1 and Alt3). Linkage analyses carried out between Al-tolerance genes and several isozyme loci revealed that the Alt1 locus was linked to the aconitase-1 (Aco1), nicotinamide adenine dinucleotide dehydrogenase-2 (Ndh2), esterase-6 (Est6) and esterase-8 (Est8) loci, located on chromosome arm 6RL. The order obtained was Alt1-Aco1-Ndh2-Est6-Est8. The Alt3 locus was not linked to the Lap1, Aco1 and Ndh2 loci, located on chromosome arms, 6RS, 6RL and 6RL respectively. Therefore, the Alt3 locus is probably on a different chromosome. Received: 18 March 1997 / Accepted: 21 March 1997     

The cancer cell’s “power plants” as promising therapeutic targets: An overview

This introductory article to the review series entitled “The Cancer Cell’s Power Plants as Promising Therapeutic Targets” is written while more than 20 million people suffer from cancer. It summarizes strategies to destroy or prevent cancers by targeting their energy production factories, i.e., “power plants.” All nucleated animal/human cells have two types of power plants, i.e., systems that make the “high energy” compound ATP from ADP and P _i . One type is “glycolysis,” the other the “mitochondria.” In contrast to most normal cells where the mitochondria are the major ATP producers (>90%) in fueling growth, human cancers detected via Positron Emission Tomography (PET) rely on both types of power plants. In such cancers, glycolysis may contribute nearly half the ATP even in the presence of oxygen (“Warburg effect”). Based solely on cell energetics, this presents a challenge to identify curative agents that destroy only cancer cells as they must destroy both of their power plants causing “necrotic cell death” and leave normal cells alone. One such agent, 3-bromopyruvate (3-BrPA), a lactic acid analog, has been shown to inhibit both glycolytic and mitochondrial ATP production in rapidly growing cancers (Ko et al., Cancer Letts., 173, 83–91, 2001), leave normal cells alone, and eradicate advanced cancers (19 of 19) in a rodent model (Ko et al., Biochem. Biophys. Res. Commun., 324, 269–275, 2004). A second approach is to induce only cancer cells to undergo “apoptotic cell death.” Here, mitochondria release cell death inducing factors (e.g., cytochrome c). In a third approach, cancer cells are induced to die by both apoptotic and necrotic events. In summary, much effort is being focused on identifying agents that induce “necrotic,” “apoptotic” or apoptotic plus necrotic cell death only in cancer cells. Regardless how death is inflicted, every cancer cell must die, be it fast or slow.     

“Chelatable iron pool”: inositol 1,2,3-trisphosphate fulfils the conditions required to be a safe cellular iron ligand

Mammalian cells contain a pool of iron that is not strongly bound to proteins, which can be detected with fluorescent chelating probes. The cellular ligands of this biologically important “chelatable”, “labile” or “transit” iron are not known. Proposed ligands are problematic, because they are saturated by magnesium under cellular conditions and/or because they are not “safe”, i.e. they allow iron to catalyse hydroxyl radical formation. Among small cellular molecules, certain inositol phosphates (InsPs) excel at complexing Fe³⁺ in such a “safe” manner in vitro. However, we previously calculated that the most abundant InsP, inositol hexakisphosphate, cannot interact with Fe³⁺ in the presence of cellular concentrations of Mg²⁺. In this work, we study the metal complexation behaviour of inositol 1,2,3-trisphosphate [Ins(1,2,3)P ₃], a cellular constituent of unknown function and the simplest InsP to display high-affinity, “safe”, iron complexation. We report thermodynamic constants for the interaction of Ins(1,2,3)P ₃ with Na⁺, K⁺, Mg²⁺, Ca²⁺, Cu²⁺, Fe²⁺ and Fe³⁺. Our calculations indicate that Ins(1,2,3)P ₃ can be expected to complex all available Fe³⁺ in a quantitative, 1:1 reaction, both in cytosol/nucleus and in acidic compartments, in which an important labile iron subpool is thought to exist. In addition, we calculate that the fluorescent iron probe calcein would strip Fe³⁺ from Ins(1,2,3)P ₃ under cellular conditions, and hence labile iron detected using this probe may include iron bound to Ins(1,2,3)P ₃. Therefore Ins(1,2,3)P ₃ is the first viable proposal for a transit iron ligand. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Validation of the <Emphasis Type="Italic">VRN-H2</Emphasis>/<Emphasis Type="Italic">VRN-H1</Emphasis> epistatic model in barley reveals that intron length variation in <Emphasis Type="Italic">VRN-H1</Emphasis> may account for a continuum of vernalization sensitivity

The epistatic interaction of alleles at the VRN-H1 and VRN-H2 loci determines vernalization sensitivity in barley. To validate the current molecular model for the two-locus epistasis, we crossed homozygous vernalization-insensitive plants harboring a predicted “winter type” allele at either VRN-H1 (Dicktoo) or VRN-H2 (Oregon Wolfe Barley Dominant), or at both VRN-H (Calicuchima-sib) loci and measured the flowering time of unvernalized F₂ progeny under long-day photoperiod. We assessed whether the spring growth habit of Calicuchima-sib is an exception to the two-locus epistatic model or contains novel “spring” alleles at VRN-H1 (HvBM5A) and/or VRN-H2 (ZCCT-H) by determining allele sequence variants at these loci and their effects relative to growth habit. We found that (a) progeny with predicted “winter type” alleles at both VRN-H1 and VRN-H2 alleles exhibited an extremely delayed flowering (i.e. vernalization-sensitive) phenotype in two out of the three F₂ populations, (b) sequence flanking the vernalization critical region of HvBM5A intron 1 likely influences degree of vernalization sensitivity, (c) a winter habit is retained when ZCCT-Ha has been deleted, and (d) the ZCCT-H genes have higher levels of allelic polymorphism than other winterhardiness regulatory genes. Our results validate the model explaining the epistatic interaction of VRN-H2 and VRN-H1 under long-day conditions, demonstrate recovery of vernalization-sensitive progeny from crosses of vernalization-insensitive genotypes, show that intron length variation in VRN-H1 may account for a continuum of vernalization sensitivity, and provide molecular markers that are accurate predictors of “winter vs spring type” alleles at the VRN-H loci.     

The effects of external potassium and magnesium concentrations on the magnesium and potassium inflow rates and growth of micropropagated cherry rootstocks, “F.12/1” (Prunus avium L.) and “Colt” (Prunus avium L.) × Prunus pseudocerasus L.)

The effects (and interaction) of two solution concentrations of Mg (50, 500, μM) and two of K (250, 4250 μM) on the growth of micropropagated plants of “F. 12/1” and “Colt” were investigated using a flowing solution culture system. Magnesium inflow and growth of “Colt” and “F. 12/1” were inhibited to a similar extent by an increased concentration of K in the nutrient solution. However, the consequences of this inhibition were different. Reduced inflow of Mg in “F. 12/1” caused Mg deficiency symptoms at high and low concentrations of K, whereas this only occurred with a combination of high K concentration and low Mg concentration in “Colt”. The distribution of dry matter within the plant was significant in determining susceptibility to Mg deficiency. Since “F. 12/1” has a smaller root:shoot ratio than Colt it is unable to sustain the same concentration of Mg in leaves as “Colt” irrespective of external K concentration. The molar ratio of K:Mg in soil solutions should remain <8.5:1 in order to ensure maximum growth of “F. 12/1” and “Colt”. This revised version was published online in June 2006 with corrections to the Cover Date.