On the asymptotics of penalized splines

We study the asymptotic behaviour of penalized spline estimatorsin the univariate case. We use B-splines and a penalty is placedon mth-order differences of the coefficients. The number ofknots is assumed to converge to infinity as the sample sizeincreases. We show that penalized splines behave similarly toNadaraya--Watson kernel estimators with ‘equivalent’kernels depending upon m. The equivalent kernels we obtain forpenalized splines are the same as those found by Silverman forsmoothing splines. The asymptotic distribution of the penalizedspline estimator is Gaussian and we give simple expressionsfor the asymptotic mean and variance. Provided that it is fastenough, the rate at which the number of knots converges to infinitydoes not affect the asymptotic distribution. The optimal rateof convergence of the penalty parameter is given. Penalizedsplines are not design-adaptive.     

Identification of Jasmonic Acid in Three Species of Higher Plants and Its Biological Activities

(–)-Jasmonic acid (JA) was isolated and characterizedfrom immature seeds of Phaseolus vulgaris L. as a growth inhibitoragainst rice seedlings. The presence of JA was also confirmedin both fresh leaves and insect galls of Castanea crenata Sieb.et Zucc. and immature seeds of Dolichos lablab L. by combinedgas chromatography-mass spectrometry analyses. The biologicalactivities of JA were evaluated in several bioassay systems,and it was shown that JA is a new type of plant growth regulator. (Received February 9, 1981; Accepted March 27, 1981)     

Measuring the RGR of Individual Grass Plants

Vegetative growth of grasses was analysed by dry mass increaseof growing leaves.Holcus lanatuswas grown in a controlled environmentand leaf extension rates of leaf numbers 5–10 of the maintiller were monitored daily. Leaf appearance and leaf extensionrates (LER) of leaves 5–7 enabled the prediction of thefinal length and dry mass of leaf 8 during its growth. A linearincrease of leaf mass per unit leaf length (LML) of leaf 8 wasobserved during growth. After harvest the daily increase indry mass of growing leaves was calculated from the LER and correspondingincrease in LML. The relative growth rate (RGR) of the maintiller showed day-to-day fluctuations and was gradually reducedby 50% over a 16-d period. The RGR of the shoot was maintainedby tillering. The RGR of a single (grass) plant can be calculatedfrom four parameters only: LER, LML, leaf appearance and tillering.Variation of RGR over a period can be reconstructed after harvestand the impact of these four parameters on RGR can be established.Copyright1998 Annals of Botany Company. Relative growth rate, grass, leaf growth,Holcus lanatus.     

A New Approach to Understanding the Calcifuge Habit of Plants

Growth rate of the calcifuge plants Carex pilulifera, Deschampsiaflexuosa, Holcus mollis, Luzula pilosa, Nardus stricta, andVeronica officinalis, transplanted into an Ordovician limestonesoil of pH 8, increased by two to three times on addition of5 mol m^-3 of CaHPO₄ compared to untreated conditions. For Galiumsaxatile, however, P treatment was lethal and growth was possibleonly in soil supplied with Fe(III) citrate, which had littleor no effect on growth of the other six species. Phosphate treatmentof the limestone soil greatly increased plant uptake of P, whereasP concentration of shoots from untreated soil was very low andprobably highly deficient, compared to plants of field siteorigin. From this and two other recent studies it is now possibleto conclude that the calcifuge habit of plants, at least underclimatic conditions prevailing in northern Europe, is most oftendue to an inability of such plants to render the native phosphateof limestone soils available to plant uptake. Out of ten calcifugespecies tested, only one exception to this rule was identified.Copyright1994, 1999 Academic Press Carex pilulifera, Deschampsia flexuosa, Galium saxatile, Holcus mollis, Luzula pilosa, Nardus stricta, Veronica officinalis, calcifuge plants, phosphorus, iron, limestone soil, limiting factors     

Comparison of Four Methods Calculating the Seasonal Pattern of Plant Growth Efficiency of a Kiwifruit Berry

Four methods of determining the substrate requirements for synthesisof a kiwifruit [Actinidia deliciosa (A. Chev.) C. F. Liang etA. R. Ferguson var. deliciosa cv. Hayward] berry were comparedusing data derived from common kiwifruit berry samples collectedfrom anthesis to fruit maturity. The four methods were basedon fruit proximal analysis, elemental analysis, heats of combustion,or tissue carbon content. All methods gave similar patternsof seasonal costs and values of final cost to the plant (mean1.21 g glucose g^–1 season^–1) but there was lessagreement for growth respiration (mean 0.147 g glucose g^–1season^–1). This is the first time that a continuous recordof growth cost over the course of development has been presented,and the trends in seasonal cost reflect the uptake into andsynthesis of the different biochemical constituents in the fruit.The differences between the results of each method reflect theunderlying assumptions used in their development. It appearsfrom this work that the method of McDermitt and Loomis (1981),utilizing elemental analyses, is most preferred. Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson var deliciosa cv Haywood, kiwifruit, true growth yield, plant growth efficiency, production value, glucose value, bioenergetic cost     

A carrier-mediated mechanism for pyridoxine uptake by human intestinal epithelial Caco-2 cells: regulation by a PKA-mediated pathway

Vitamin B₆ is essential for cellular functions and growth due to its involvement in important metabolic reactions. Humans and other mammals cannot synthesize vitamin B₆ and thus must obtain this micronutrient from exogenous sources via intestinal absorption. The intestine, therefore, plays a central role in maintaining and regulating normal vitamin B₆ homeostasis. Due to the water-soluble nature of vitamin B₆ and the demonstration that transport of other water-soluble vitamins in intestinal epithelial cells involves specialized carrier-mediated mechanisms, we hypothesized that transport of vitamin B₆ in these cells is also carrier mediated in nature. To test this hypothesis, we examined pyridoxine transport in a model system for human enterocytes, the human-derived intestinal epithelial Caco-2 cells. The results showed pyridoxine uptake to be 1) linear with time for up to 10 min of incubation and to occur with minimal metabolic alteration in the transported substrate, 2) temperature and energy dependent but Na⁺ independent, 3) pH dependent with higher uptake at acidic compared with alkaline pHs, 4) saturable as a function of concentration (at buffer pH 5.5 but not 7.4) with an apparent Michaelis-Menten constant (K_m) of 11.99 ± 1.41 µM and a maximal velocity (V_max) of 67.63 ± 3.87 pmol · mg protein^-1 · 3 min^-1, 5) inhibited by pyridoxine structural analogs (at buffer pH 5.5 but not 7.4) but not by unrelated compounds, and 6) inhibited in a competitive manner by amiloride with an apparent inhibitor constant (K_i) of 0.39 mM. We also examined the possible regulation of pyridoxine uptake by specific intracellular regulatory pathways. The results showed that whereas modulators of PKC, Ca⁺²/calmodulin (CaM), and nitric oxide (NO)-mediated pathways had no effect on pyridoxine uptake, modulators of PKA-mediated pathway were found to cause significant reduction in pyridoxine uptake. This reduction was mediated via a significant inhibition in the V_max, but not the apparent K_m, of the pyridoxine uptake process. These results demonstrate, for the first time, the involvement of a specialized carrier-mediated mechanism for pyridoxine uptake by intestinal epithelial cells. This system is pH dependent and amiloride sensitive and appears to be under the regulation of an intracellular PKA-mediated pathway. vitamin B₆; intestinal transport; transport regulation; Caco-2 cell     

NUTRITIONAL STUDIES OF THE EDIBLE SEAWEED PORPHYRA TENERA I. THE INFLUENCE OF DIFFERENT B12 ANALOGUES, PLANT HORMONES, PURINES AND PYRIMIDINES ON THE GROWTH OF CONCHOCELIS

The red alga Porphyra tenera has been obtained in axenic cultureby the "dip and drag" technique in an agarized medium containingantibiotics. In the axenic culture, the Conchocelis of P. teneraneeds vitamin B₁₂ for growth. The addition of other vitaminsdoes not increase growth further. The pattern of specificityis similar to that of Escherichia coli 113-3. Factor B, pseudovitaminB₁₂ and Factor Z₂ support as much growth as vitamin B₁₂, while2-methylmercaptoadenine and 5-methyl benzimidazole cobalamineincrease the growth more than B₁₂. All the analogues containingbenzimidazole can replace B₁₂. Kinetin, adenine, indoleaceticacid and especially gibberellic acid increase growth. Threepurines, (xanthine, hypoxanthine and guanine) and three pyrimidines(uracil, methylcytosine and thymine) also promote growth inthe presence of vitamine B₁₂. (Received January 18, 1965; )     

Nutrient-Limited Growth Rates: Roles of Nutrient-Use Efficiency and of Adaptations to Increase Uptake Rate

When stressed by low nutrient availability, young sunflowerplants (Helianthus annuus) showed responses seen in many otherspecies: increases in root uptake capacity (V^max, l/K_m), root:shoot ratio, and putative nutrient-use efficiency, nUE=l/(tissuenutrient content). A straightforward mechanistic model is derivedfor relative growth rate (RGR) in solution culture in termsof these factors. A linear regression based on the model indicatesa negative role for nUE, which violates a premise of the model.A revised model proposes that primary adaptations are only inuptake rate and growth or nutrient allocations, and these actthrough the photosynthetic utility of nutrient. The tissue nutrientcontent and associated nUE become dependent quantities. Thepredictions for RGR, as tested by linear regression, are improved.The model predicts that nUE can increase as external solutionconcentration decreases, but decreases with increased uptakeadaptations in one given environment. The decrease in nUE compromisespotential gains in RGR from uptake adaptations, and makes increasesin root: shoot ratio a nearly insignificant contributor to earlyRGR. The model and associated regression analyses are generalizedfor additional adaptations such as increased root fineness andfor different quantitative ways that a nutrient may limit photosynthesis.The model and analyses are also generalized to plant growthin soil and growth without functional balance between root andshoot. Key words: Relative growth rate, Helianthus annuus, nutrient stress, nutrient use efficiency, functional balance     

Suppression of the High Affinity Phosphate Uptake System: A Mechanism of Arsenate Tolerance in Holcus lanatus L.

In Holcus lanatus L. phosphate and arsenate are taken up bythe same transport system. Short-term uptake kinetics of thehigh affinity arsenate transport system were determined in excisedroots of arsenate-tolerant and non-tolerant genotypes. In tolerantplants the V_max of ion uptake in plants grown in phosphate-freemedia was decreased compared to non-tolerant plants, and theaffinity of the uptake system was lower than in the non-tolerantplants. Both the reduction in V_max and the increase in K_m ledto reduced arsenate influx into tolerant roots. When the twogenotypes were grown in nutrient solution containing high levelsof phosphate, there was little change in the uptake kineticsin tolerant plants. In non-tolerant plants, however, there wasa marked decrease in the V_max to the level of the tolerant plantsbut with little change in the K_m. This suggests that the lowrate of arsenate uptake over a wide range of differing rootphosphate status is due to loss of induction of the synthesisof the arsenate (phosphate) carrier. Key words: Arsenate, Holcus lanatus L., phosphate uptake, tolerance mechanisms, uptake mechanisms     

Ecotypes of Holcus lanatus Tolerant to Zinc Toxicity also Tolerate Zinc Deficiency

Genotypes tolerant to zinc (Zn) toxicity, if they accumulateZn in their roots, may grow better than Zn-sensitive genotypes,even in Zn-deficient soil. In the present study, Holcus lanatusL. ecotypes differing in tolerance to Zn toxicity were grownin Zn-deficient Laffer soil which was amended with Zn to createa range of conditions from Zn deficiency to Zn toxicity. IncreasingZn additions to the soil, up to the sufficiency level, improvedgrowth of all ecotypes. At toxic levels of added Zn, the Zn-sensitiveecotype suffered a greater decrease in growth than the Zn-tolerantecotypes. All ecotypes accumulated more Zn in roots than inshoots, with root concentrations exceeding 8 g Zn kg^-1dry weightin extreme cases. When grown in Zn-deficient or Zn-sufficientsoil (up to 0.5 mg Zn kg^-1soil added), ecotypes tolerant toZn toxicity took up more Zn, grew better and had greater rootand shoot Zn concentration than the control (Zn-sensitive ecotype).Zn-tolerant ecotypes transported more Zn, copper (Cu) and iron(Fe) from roots to shoots in comparison with the Zn-sensitiveecotype. The average Zn uptake rate from Zn-deficient soil (noZn added) was greater in the Zn-tolerant ecotypes than in theZn-sensitive ecotype. In conclusion, ecotypes of H. lanatusthat are tolerant to Zn toxicity also tolerate Zn deficiencybetter than the Zn-sensitive ecotype because of their greatercapacity for taking up Zn from Zn-deficient soil. This is thefirst report of the coexistence of traits for tolerance to Zntoxicity and Zn deficiency in a single plant genotype. Copyright2000 Annals of Botany Company Copper, heavy metal, Holcus lanatus, iron, zinc deficiency, zinc toxicity     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

The Effects of Mineral Nutrition and Density on Root Interactions in Three Grass Species

Studies were made of competition between Dactylis glornerataL., Holcus lanatus L. and Anthoxanthum odoratum L. The competitiveability of the species depended on the density of planting.D. glomerata was more competitive when planted at high density,whereas H. lanatus was more competitive at low density. A. odoratumwas most competitive at the intermediate density.     

Variations in the Levels of cis- and trans-Ribosylzeatins and Other Minor Cytokinins during Development and Growth of Cones of the Hop Plant

The endogenous cytokinins in cones of the hop plant (Humuluslupulus L. cv. Shinshuwase) were identified by combined gaschromatography and selected ion current monitoring (GC-SIM)and high performance liquid chromatography as ribosyl-cis-zeatin,ribosyl-trans-zeatin, cis-zeatin, trans-zeatin and ribosyl-trans-zeatin-O-glucoside.The contents of these cytokinins in both fertilized and unfertilizedcones at various growth stages were determined using GC-SIMand/or bioassay. Based on these data, the rapid growth of thefertilized cone is attributed mainly to ribosyl-trans-zeatinwhich accumulates mostly in the seed. Ribosyl-cis-zeatin wasfound in both fertilized and unfertilized cones. In the latter,ribosyl-cis-zeatin was quantitatively a major cytokinin andseemed to cooperate with ribosyl-trans-zeatin and trans-zeatinin promoting the growth. (Received January 12, 1981; Accepted February 10, 1981)     

The Vegetative Growth of Helianthus annuus and Phaseolus vulgaris as Affected by Seasonal Factors in Freetown, Sierra Leone

Sand-culture experiments were carried out in full daylight atsuccessive weekly intervals between March and December 1969,to investigate the effects of seasonal changes in climatic factorson the growth of Helianthus annuus and Phaseolus vulgaris inFreetown. Values for a number of growth parameters were calculatedfrom the dry weights of the leaves, stems, and roots, and fromthe leaf areas. Simultaneously the diurnal changes in climaticfactors were recorded. Multiple regressions linking light, temperature, and relativehumidity with some of the growth parameters were calculated.The total variance accounted for in the regressions of relativegrowth-rate, net assimilation rate, and leaf weight ratio onlight, temperature, and relative humidity ranged from 51 to60 per cent in P. vulgaris. In H. annuus relative humidity wasless important; the percentage proportion of total varianceaccounted for in the regression of leaf weight ratio (and leafarea ratio in both species) on light and temperature was notsignificant. The results showed that H. annuus grew faster than P. vulgaris,but the latter's growth was depressed less by the dull weatherof the rainy season. The relative growth-rates of both specieswere positively dependent on light and temperature while theirnet assimilation rates were negatively dependent on relativehumidity, and their leaf area ratios negatively dependent onlight. All parameters used except leaf area ratio and leaf areato leaf weight ratio showed seasonal variations correspondingto dry and rainy seasons. The initial and final values of leafarea ratio and weight ratios were always different but did notvary in the same direction in both species. The results are discussed in relation to similar work done elsewhere.     

Effect of a Growth Inhibitor on the Hydroxyproline Level in Cell Wall of Zea Primary Roots

Evidence supporting the view that there is an inverse relationshipbetween the hydroxyproline-protein level in the cell wall andthe ability of a cell to undergo rapid cell elongation was obtained.A growth inhibitor extracted from Zea primary roots acceleratedthe incorporation of radioactivity derived from ¹⁴C-prolineinto the sodium lauryl sulfate (SLS)-insoluble cell wall fraction.However, the inhibitor had no effect on the ratio of hydroxyprolineto proline that was incorporated into the SLS-insoluble fraction. We have discussed what this growth inhibitor may mean in thegeotropic curvature of Zea primary roots. ¹ Present address: Faculty of Education, University of Yamagata,Yamagata 990, Japan (Received May 9, 1981; Accepted August 8, 1981)     

Changes in Endogenous Ribosyl-trans-zeatin and IAA Levels in Relation to the Proliferation of Tobacco Crown Gall Cells

Changes in the contents of major endogenous plant hormones intobacco crown gall cells, namely IAA and ribosyl-trans-zeatin,during cell growth were examined using HPLC and ¹⁴C-labeledplant hormones. The content of IAA was high at the early logarithmicstage, while that of ribosyl-trans-zeatin was high at the middlelogarithmic stage. This suggests that cell growth is affectedfirst by IAA, then by ribosyl-trans-zeatin. ³ Present address: Department of Agricultural Chemistry, TottoriUniversity, Koyama, Tottori 680, Japan (Received July 13, 1981; Accepted September 11, 1981)     

A Plasma Membrane Mutation acrA in Escherichia coli

Protein analysis and electron microscopic observation of thefreeze-fractured plane of the plasma membrane were performedwith an acriflavine-sensitive mutant carrying mutation acrA(at min 10) and with the wild type (acrA⁺) strain of Escherichiacoli K-12. The acrA mutant membrane was deficient (or much lower)in one protein when analyzed by the polyacrylamide gel electrophoresistechnique. (Received May 7, 1981; Accepted July 28, 1981)     

A comparison between methods used to control nutrient supply

Experimental methods to supply nutrients to culture solutionsin order quantitatively to control plant nutrition are compared.In experiments with tomato and birch plants, for which the dataare available in databases (Ingestad et al., 1994a, b), thenutrients were supplied at constant relative addition rates(R_A over sufficiently long periods of time to achieve acclimatedplants and reliable measurements of plant responses. The plantswere maintained under steady-state conditions, i.e. the internalnutrient concentrations (c₁) remained constant, as a resultof a numerical equality between the relative uptake rate (R_U)and the relative growth rate (R_G). These results are comparedto experiments with pea plants (Macduff et al., 1993). In oneseries (a), R_A was applied, but without strict control of internalsteady-state, and in the other series (b), the external concentration(c_e) was maintained constant. With limiting nitrogen, in bothseries, there was a substantial deviation from equality betweenR_U and R_G. In (a), c_I changed during the experimental periodand the purpose of the R_A approach was lost. In (b), a constantc_e had little effect on nitrogen uptake and plant growth. Atthe three highest concentrations, steady-states were obtainedat non-limiting uptake rates. At the lowest concentration, theuptake rate of nitrogen was about the same, but there was adecrease of R_a, which apparently was not caused by reduced uptake.Clear-cut relationships can not therefore be established betweentreatment variables and plant responses and the conclusionsreached by Macduff et al. (1993) have little support in theirexperimental results. This indicates an urgent need to updateboth theories and experimental methods together: in particular,it is important to identify the system under investigation andto distinguish between control of the medium and control ofthe plant. Key words: Experimental control, external nutrient concentration, non-limiting and limiting nutrient supply, relative addition rate, relative uptake rate, relative growth rate, steady-state     

海拔梯度上青海云杉径向生长与气候关系稳定性研究

以祁连山北坡海拔2 700m(分布下限)、3 000m(中部)和3 300m(分布上限)的青海云杉为研究对象,采用长短两种不同步长的样条函数去趋势对1952～1980年和1981～2009年两个时段青海云杉径向生长与气候的关系进行对比分析,以揭示青海云杉年轮中包含的不同频率生长趋势与气候之间的关系及其在海拔梯度上的差异,探讨海拔梯度上气候变化对树木径向生长的影响。结果显示:(1)随着海拔升高,限制青海云杉径向生长的气候因子从降水转变为温度,不同时期的限制因子也发生变化。(2)在海拔2 700m处,上一年12月份平均温度与青海云杉生长的关系发生了分异,小步长的样条函数得到的年表中保留了较多降水信号;海拔3 000m处青海云杉径向生长与上年9月份降水量、平均温度表现出显著正相关关系;海拔3 300m处青海云杉生长与当年夏季降水量呈显著正相关关系,而在后一时段相关关系不显著,与当年春季、夏季的平均温度相关关系不稳定,大步长的样条函数得到的年表中表现出温度与生长关系的分异,且不同海拔青海云杉径向生长的降水量制约趋势变得明显。研究表明,祁连山北坡青海云杉与气候的关系在海拔梯度上存在差异,其对气候变化的响应也存在差异,水分的限制作用随着温度的逐年升高逐渐突出;采用不同步长的样条函数去趋势可以在年表中保留不同的气候信息,从而对分异现象分析结果产生影响,选择合理步长的样条函数进行去趋势才能得到合理准确的分析结果。     

Seedling Growth in Elymus farctus after Episodes of Burial with Sand

Episodes of burial by wind-blown sand are a frequent hazardfor Elymus farctus in the strandline and foredunes. We haveinvestigated the ability of seedlings to withstand and recoverfrom experimental burial. The burial treatments were appliedat the two-leaf stage, either for one or two weeks, and thegrowth in them was compared with that in unburied controls.The method of B-splines, with knots defined at the beginningand end of the burial period, proved to be appropriate for fittingrelationships between In dry mass and time for growth analysis.The relative growth rates derived from these relationships werepartitioned into component relative growth rates for individualplant organs, to reveal the responses to burial in terms ofdry matter allocation. No plants survived two weeks of burial but all those buriedfor one week recovered. There was respiratory loss of dry massduring burial, although fitted relative growth rates were notsignificantly different from zero. On re-exposure, relativegrowth rates increased to equal the maximum values in unburiedplants. Dry mass losses were from the root and stem fractions.Leaf 1 was unaffected, whereas the development of leaf 2 wascurtailed. Apart from their delayed appearance, leaves 3–5behaved similarly to their non-buried counterparts. The maintenanceof leaves at the expense of other organs during burial may becrucial to the survival of E. farctus seedlings. Sand burial, survival, recovery, growth analysis, splined cubic regression, Elymus farctus, sand couch grass