The Induction and Development of Potato Microtubers In Vitroon Media Free of Growth Regulating Substances

Reliable microtuber production has been obtained by culturingnodal explants of potato on Murashige and Skoog medium withoutthe addition of growth regulating substances. The use of sucroseat 8 %, as compared with 4 or 12%, advanced the initiation oftuberization and gave more and larger microtubers. A periodof 1 month under 16 h days, followed by transfer to 8 h photoperiodsgave most rapid microtuber development. A reduction in the totalnitrogen supply or an increase in the ratio of ammonium to nitratereduced the size and number of microtubers Potato, Solanum tubersum L;, microtubers, in vitro induction and development, sucrose, photoperiod, nitrogen nutrition     

Environmental Factors Controlling Capitulum Opening and Closing of Dandelion, Taraxacum albidum

The capitula of Taraxacum albidum kept in darkness opened whenthe temperature rose. The higher the temperature before thechange and greater the temperature rise, the larger the openingresponse was. The opening was promoted by light. The capitulakept in darkness at 20?1?C opened after exposure to light withoutthe temperature rise. The capitula closed 8–10 h afterthe beginning of the opening under constant light and temperatureconditions. (Received November 8, 1986; Accepted March 13, 1987)     

Thermodormancy Release of Celery Seed by Gibberellins, 6-Benzylaminopurine, and Ethephon Applied in Organic Solvent to Dry Seeds

The emergence of celery (Apium graveolens L. cv. Utah 52–70)seeds was promoted by growth regulators when exposed to hightemperatures during the germination period. The growth regulatorswere applied to dry seeds prior to sowing, by means of the organicsolvent dichloromethane (DCM). A mixture of gibberellins A₄and A₇ (GA_4/7) strongly enhanced emergence at a high day-timetemperature of 35°C alternating with night temperaturesof 20°C and 25°C; however, emergence was very poor whenthe night temperature was raised to 30°C. Under the latterregime, only mixtures of GA_4/7 with 6-benzylaminopurine (BA)or with 2-chlorophosphonic acid (ethephon) promoted seed emergence.However, BA and ethephon applied separately or in combinationwere much less effective in enhancing seed emergence withoutthe addition of GA_4/7, under all the temperature regimes.     

Studies on chloroplast development in Chlamydomonas reinhardtii II. Effects of interposed darkness on chlorophyll synthesis

Effects of an inserted dark incubation on light-induced chlorophyllsynthesis in dark grown Chlamydomonai reinhardtii y-1 cellswere studied. Chlorophyll synthesis in cells with the interposeddark incubation proceeded faster than that in cells withoutthe dark incubation when it was inserted within 2.5 hr afterthe onset of illumination. Within this limit, the longer theinitial illumination given, the shorter was the length of darkincubation required to obtain a maximum rate of chlorophyllsynthesis. However, when the dark incubation was provided laterthan 2.5 hr, the rate of subsequent chlorophyll synthesis wasreduced. Since cells responded to the dark treatment in differentmanners before and after the 2.5 hr point, this time was designatedas the transition point. This 2.5 hr period corresponds to thelength of the regular lag phase in chlorophyll synthesis undercontinuous illumination. Based on these results, the nature of the previously postulatedpromoting factor (P-factor) in chlorophyll synthesis is discussed. (Received June 13, 1972; )     

Studies on the Growth in Culture of Plant Cells: XVIII. NUCLEAR CYTOLOGY OF ACER PSEUDOPLATANUS SUSPENSION CULTURES

Established suspension culture strains of Acer pseudoplatanuswere analysed by chromosome counting and microdensitometricDNA measurements of individual nuclei. Comparison with the root-tipcomplement (2n=4x=52) showed the cultures to be entirely aneuploidwith modal chromosome numbers of approximately 75 and 135 plussome cells with 250–350. Analysis of the frequency distributionsof nuclear DNA values through the growth cycle of a batch cultureshowed that stationary phase cells accumulated in G1 of thecell cycle. Stationary phase DNA distributions could thus beused to indicate the chromosomal status of a culture withoutthe complication of G1 and G2 DNA values for each chromosomenumber. Root-tip and cultured cells showed a close correlationbetween DNA content and chromosome number indicating that structuralchanges and loss of chromosomes had been at random.     

Ontogeny of a Simple Locomotor System: Role of the Periphery in the Development of Central Nervous Circuitry

The development of locomotor systems in the lobster Homarusamericanus is described. The tail—flip escape responseis fully developed when the larvae hatch, and occurs withoutthe participation of giant fibers. The abdominal swimmeretsare undifferentiated at hatching, but are fully developed twoto three weeks later when the animals molt to the fourth larvalstage. Forward locomotion in the pelagic larvae is achievedusing thoracic swimming appendages until the fourth larval stage,when these degenerate and the swimmerets assume the locomotorrole. The hypothesis that peripheral structures specify the centralnervous connections of motoneurons during ontogeny was testedin the swimmeret system. Presumptive swimmeret appendages, includingprospective muscle and sense organs, were extirpated prior totheir differentiation in newly hatched larvae. The correspondingswimmeret motoneurons nevertheless grew and formed normal centralconnections, as evidenced by the appearance of normal patternsof rhythmic locomotor discharge and normal reflexes at the usualtime. Moreover, swimmeret motoneurons retained normal patternsof motor output even when the regeneration of their target appendageswas prevented for as long as two months. Therefore, the formationof normal motor output patterns during ontogeny is not dependentupon feedback from differentiated target muscle nor from senseorgans which normally monitor the results of the motor activity.     

A Flower and Pod Staging System for Soybean

Flower and pod abscission limit soybean yield. A system forquantifying flower and pod development based on the morphologicalappearance of the flower prior to and following anthesis hasbeen developed to aid in studies of pod abscission. Changesin the appearance of the corolla, primarily the banner petal,are used to distinguish the different stages of the system.External pistil dimensions have been correlated with internalfeatures for each stage of development. From anthesis to podset, pistil length and weight increase almost two- and fivefold,respectively, and ovule development progresses from unfertilizedegg cells to embryos surrounded by cellular endosperm. Pod determinedare correlated with ovule length and width and embryo cell number.Flower and pod stages can be determined in situ, thus permittingnon-destructive observation and experimental manipulation offlowers or pods without necessarily impeding their development.Stages have been identified that indicate precisely when podset occurs and when young pods cease growing and ultimatelyabscise. This system of flower and pod staging is useful instudies designed to assess effects of abiotic or biotic stressand genetic factors on pod set and abortion. Abscission, anthesis, Glycine max (L.) Merr, embryo development, pod set     

Trans-Kingdom Conjugation Between Agrobacterium tumfaciens and Saccharomyces cerevisiae, a Bacterium and a Yeast

For conjugation between prokaryotic Agrobacterium tumefaciensand eukaryotic Saccharomyces cerevisiae, we constructed twonovel conjugative plasmids. A. tumefaciens transmitted the plasmidsto S. cerevisiae with the aid of tra genes on a helper plasmid.The transmitted plasmids retained their original structure andfunction in transconjugant yeasts. The presence of Ti plasmidbarely affected the trans-kingdom conjugation. ¹A preliminary report of this work was presented in Japaneseby Yoshida et al. (1993).     

Microheterogeneity of PSI-E Subunit of Photosystem I in Nicotiana sylvestris

Microheterogeneity of a photosystem I (PSI) subunit encodedby a nuclear gene psaE was examined in Nicotiana sylvestris,with the aid of cDNA cloning, peptide mapping analysis and proteinsequencing. The psaE product of this plant has four isoformswhose mobilities in PAGE are slightly different from each other.We isolated two types of psaE cDNAs from a N. sylvestris cDNAlibrary, and designated the corresponding genes as psaEa andpsaEb, respectively. The psaEa and psaEb genes are 77% homologousat DNA level, and their translation products share 80.4% homologyfor the precursor proteins and 89.1% for the mature forms. Comparativeanalysis of the four isoproteins and the putative products ofthe two psaE genes revealed that two isoproteins out of fourare derived from psaEa gene, and the difference between thesetwo isoproteins lies in the respective presence or absence ofN-terminal alanine. Likewise, the other two proteins are derivedfrom psaEb with similar N-terminal heterogeneity. These resultsindicate that multi-gene organization and heterogeneous N-terminalformation at post-translational level are two possible causesfor PSI subunit polymorphism in isogenic plant lines. (Received October 8, 1993; Accepted November 30, 1993)     

Hemolymph loss during nuptial feeding constrains male mating success in sagebrush crickets

Although costs of mating have been widely documented in females,intrinsic costs of copulation have been poorly documented inmales, and there is little evidence that such costs constrainmale mating success under natural conditions. Male sagebrushcrickets, Cyphoderris strepitans, offer females an unusual somaticfood gift at copulation that may constitute a significant costof copulation: females chew on the ends of the males' fleshyhind wings and ingest hemolymph seeping from the wounds theyinflict. Previous studies have shown that once a male has mated,his probability of obtaining an additional copulation is reducedrelative to that of a virgin male seeking to secure his firstmating. If the future mating prospects of nonvirgin males arediminished because of the costs of copulation, this could stemeither from the resources required to manufacture a new spermatophoreor through the energy needed to replenish hemolymph lost throughfemale wing-feeding. To distinguish between these two alternatives,we experimentally depleted virgin males of varying amounts hemolymphin a way that mimicked hemolymph loss of nonvirgin males, withoutthe attendant costs of spermatophore production. After theyhad been treated, males were released in the field and recapturedover the course of the breeding season to monitor their matingsuccess. Control males mated significantly sooner than did malesdepleted of hemolymph. We conclude, therefore, that the depletionof hemolymph that occurs through female wing feeding is sufficientby itself to diminish a nonvirgin male's ability to secure anothermating.     

Rhizobial lipo-oligosaccharide nodulation factors: multidimensional chromatographic analysis of symbiotic signals involved in the development of legume root nodules

Nod factors are a group of biologically active oligosaccharidesignals that are secreted by symbiotically competent bacteriaof the family Rhizobiaceae. Their biosynthesis is determinedby rhizobial nodulation (nod) genes, and is specifically inducedin response to flavonoids secreted from the roots of host leguminousplants. The biological activity of Nod factors on these hostlegumes dramatically mimics the early developmental symptomsof the Rhizobium-legame symbiosis including, amongst other effects,root hair deformations and nodule initiation. Structurally,all Nod factors are short oligomers of ß-1,4-linkedN-acetylglucos-amine residues [usually degree of polymerization(dp) 4 or 5] that are N-acylated on the distal glucosarnine.This common ‘core’ structure may be modified bya number of species-specific substituents on the distal or reducingsugars. These modifications are governed by rhizobial host specificitynod genes. The biological activity of purified Nod factors mirrorsthis host specificity, indicating that the symbiotic host rangeof individual Rhizobium species is, at least partially, determinedby the variety of Nod factors they are able to produce. Herewe describe techniques that are universally applicable to theextraction, chromatographic separation and identification ofNod factors. We have applied these techniques to Nod factorsfrom the broad-host-range species Rhizobium fredii USDA257 andRhizobium spp. NGR234, and the more narrow-host-range Bradyrhizobiumjaponicum USDA110, and have identified a group of novel, relativelyhydrophilic Nod factors from the NGR234 species that may haveimplications for Nod factor biosynthesis. lipo-oligosaccharide Nod factor rhibozobia singals TLC     

PHYSIOLOGICAL ACTIVITIES OF HELMINTHOSPOROL AND HELMINTHOSPORIC ACID: I. EFFECTS ON GROWTH OF INTACT PLANTS

Helminthosporol (H-ol) and helminthosporic acid (H-acid) wereeffective in promoting elongation of leaf sheaths of rice, Japanesebarnyard grass and dwarf maize (d-2 and d-5) and of hypocotylsof taisai (Brassica chinensis), but inactive in leaf sheathsof oat and wheat, hypocotyls of sesame and morning glory (Pharbitisnil) and epicotyls of Pharbitis and dwarf and tall peas. Onthe elongation of the leaf sheath of maize d-1, H-ol was promotivebut the activity of H-acid was doubtful. On hypocotyls of lettuceand daikon (Raphanus sativus), only H-acid was active. Multiplicationrate and size of fronds of Lemna perpusila were not affectedby either of the substances. Compared with gibberellic acid for the effect on the shoot growth,H-ol and H-acid were weak in activity and narrower in the scopeof plants that responded. H-ol and H-acid characteristicallypromoted the elongation of the primary root. Comparative effectivenessof H-ol and H-acid varied with plant species or parts examined. ¹ This study was supported in part by grant-in aid of the Ministryof Education (No. 0417). The results reported here were presentedat the Annual Meeting of the Botanical Society of Japan at Kanazawain 1964 (S).     

Effects of Metabolic Inhibitors on Anthocyanin Accumulation in Petals of Rosa hybrida Hort. cv. Ehigasa

Anthocyanin accumulation of petal disks of Rosa hybrida Hort.cv. Ehigasa was strongly inhibited by 2,4-dinitrophenol (2,4-DNP),suggesting that this process requires ATP. The inhibition couldnot be reversed by kinetin or naringenin, but could be whenboth were given together. This implies that 2,4-DNP exertedits effect on the step after flavanone formation. When kinetinwas added simultaneously with naringenin to the medium, naringeninwas considered to have been converted into anthocyanin in cytosoland transported into the vacuoles with the aid of kinetin. Whennaringenin was added to the medium, the disks contained a largeramount of naringenin 7-glucoside than when it was not added.Naringenin is thought to have been metabolized to glucosideand/or converted into anthocyanin in the cells. Anthocyaninaccumulation in the petal disks was not inhibited by N,N'-dicyclohexylcarbodiimide(DCCD), whereas l-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(EDAC) caused strong inhibition which could not be reversedby adding naringenin to the medium. As these reactions seemto be similar way to those observed for tonoplast ATPase withthe same inhibitors, anthocyanin permeation into vacuoles maybe mediated by tonoplast ATPase, which might be stimulated byUV irradiation. (Received August 5, 1982; Accepted June 1, 1983)     

Bud formation on excised Heloniopsis leaf fragments: Effects of leaf age and the midrib

Detached young leaves and their segments of Heloniopsis orientalisproduced adventitious buds more readily than did detached matureleaves or their segments. Media composition had a greater influenceon bud regeneration in segments of mature leaves than in segmentsof young ones. Detached young leaves and their fragments couldform buds when placed on filter paper moistened with deionizedwater only or on an agar medium without the aid of exogenousinorganic salts and growth regulators. The presence of the midribenhanced bud formation especially in segments of mature leaves.The number of buds in midrib-less segments treated with cytokininwas greater than in untreated segments with the midrib. Theseand other results suggest that regeneration is controlled byendogenous growth regulating substances supplied via vasculartissue. (Received September 4, 1973; )     

A Possible Mechanism for Seed Coat Rupture by the Embryo in Germinating Wheat

The process of seed-coat splitting, terminating germination,in red wheats is described. We show that sequential expansionof the coleorhiza and coleoptile is required for germinativegrowth to be normal. Normal emergence requires the seed-coatsto be split by the expanding coleorhiza. We here describe agroup of cells associated with the coleorhizal tip forming apapilla-like projection which could aid this process. Embryo, germination, development, wheat, Triticum aestivum     

Developmental Assessment of Sexual Reproduction inButomus umbellatus(Butomaceae): Female Reproductive Component

Flowering plants often produce ovules that do not develop intoseeds. Lack of pollination, insufficient resources, environmentalconstraints and incompatibility reactions are often consideredto be causal factors. Pre-pollination and post-fertilizationdevelopmental irregularities (DI) are less commonly implicatedas causal factors, usually because information on them is limited.The results of a detailed developmental assessment of sexualreproduction inB. umbellatususing self- and cross-pollinatedglasshouse and open-pollinated field-grown plants, reveal ahigh degree of pre-pollination and post-fertilization DI. Pre-pollinationDI account for a large fraction of the species' low reproductivepotential. Post-fertilization DI represent another crucial reductionin the species' reproductive output. Seed set inB. umbellatusisless than 1%. In the female reproductive component, these DIinclude embryo sacs with hypertrophied or highly vacuolate eggs,collapsed synergids, collapsed egg apparati and embryo sacsthat are empty, uninucleate or with disorganized mass of nuclei;there are also ovules with no embryo sacs. Post-fertilizationDI include zygotes that are hypertrophied, highly vacuolateand collapsed, and malformed embryos. The lack of an obviousadaptive significance to the array of DI inB. umbellatussuggeststhat these are unlikely to be due to self-incompatibility reactions,and physiological or environmental constraints. SinceB. umbellatusisa long-lived species, it is highly possible that disadvantageousmutations have accumulated in its clonal lineages causing aconsiderable load in terms of faulty meiosis resulting in defectivemeiotic products, a series of DI, and therefore, limited sexualreproduction. Butomus umbellatus; flowering rush; sexual reproduction; developmental assessment; developmental irregularities; abnormal embryo sacs; CLSM     

Cortisol and Pacific Salmon: A New Look at the Role of Stress Hormones in Olfaction and Home-stream Migration

Pacific salmon (genus Oncorhynchus) exhibit an interesting anduncommon life-history pattern that combines semelparity, anadromy,and navigation (homing). During smoltification, young salmonimprint on the chemical composition of their natal stream water(the home-stream olfactory bouquet or "HSOB"); they then migrateto the ocean where they spend a few years feeding prior to migratingback to their natal freshwater stream to spawn. Upstream migrationis guided by the amazing ability to discriminate between thechemical compositions of different stream waters and thus identifyand travel to their home-stream. Pacific salmon demonstratemarked somatic and neural degeneration changes during home-streammigration and at the spawning grounds. The appearance of thesepathologies is correlated with a marked elevation in plasmacortisol levels. While the mechanisms of salmonid homing arenot completely understood, it is known that adult salmon continuouslyutilize two of their primary sensory systems, olfaction andvision, during homing. Olfaction is the primary sensory systeminvolved in freshwater homing and "HSOB" recognition, and willbe emphasized here. Previously, we proposed that the increasein plasma cortisol during Pacific salmon home-stream migrationis adaptive because it enhances the salmon's ability to recallthe imprinted memory of the "HSOB" (Carruth, 1998; Carruth etal., 2000b). Elevated plasma concentrations of cortisol couldprime the hippocampus or other olfactory regions of the brainto recall this memory and, therefore, aid in directing the fishto their natal stream. Thus, specific responses of salmon tostressors could enhance reproductive success.     

Isozyme Variation in Wild and Cultivated Species of the Genus Trifolium L. (Leguminosae)

Isozyme patterns for PGI (phosphoglucoisomerase), MDH (malatedehydrogenase), EST (esterase) and SOD (superoxide dismutase)were evaluated in 36 accessions of eight Trifolium species,namely T. incarnatum, T. polymorphum, T. pratense, T. repens,T. resupinatum, T. riograndense, T. subterraneum and T. vesiculosum.Similarity between species and accessions was estimated by Jaccard’ssimilarity index based on presence or absence of bands. TheUPGMA method was utilized for the groupings and dendrogram constructionwith the aid of the NTSYS-PC program. Interspecific similaritywas low (J 0.351). The dendrogram presented eight groups, eachone corresponding to a taxonomic species. Most of the accessionsof the same species grouped together at J > 0.50, exceptT. riograndense, T. repens and T. pratense. These three speciesshowed the lowest similarity between their accessions, reflectinghigher intraspecific variation. Some accession-specific bandswere identified. The species groupings are consistent with traditionaltaxonomic species delimitation. Therefore isozyme patterns,especially when several systems are employed, are useful andreliable biochemical markers for the taxonomic delimitationand characterization of Trifolium germplasm. Copyright 2000Annals of Botany Company Genetic diversity, germplasm characterization, isoenzymatic variability, biochemical markers, isozymes,Trifolium     

Estimating the capacity for improvement in risk prediction with a marker

Consider a set of baseline predictors X to predict a binaryoutcome D and let Y be a novel marker or predictor. This paperis concerned with evaluating the performance of the augmentedrisk model P(D = 1|Y,X) compared with the baseline model P(D= 1|X). The diagnostic likelihood ratio, DLR_X(y), quantifiesthe change in risk obtained with knowledge of Y = y for a subjectwith baseline risk factors X. The notion is commonly used inclinical medicine to quantify the increment in risk predictiondue to Y. It is contrasted here with the notion of covariate-adjustedeffect of Y in the augmented risk model. We also propose methodsfor making inference about DLR_X(y). Case–control studydesigns are accommodated. The methods provide a mechanism toinvestigate if the predictive information in Y varies with baselinecovariates. In addition, we show that when combined with a baselinerisk model and information about the population distributionof Y given X, covariate-specific predictiveness curves can beestimated. These curves are useful to an individual in decidingif ascertainment of Y is likely to be informative or not forhim. We illustrate with data from 2 studies: one is a studyof the performance of hearing screening tests for infants, andthe other concerns the value of serum creatinine in diagnosingrenal artery stenosis.