Senescence behavior of the whole plant in four rice cultivars

Summary A non-sequential mode of senescence pattern (determined on the basis of decline of chlorophyll and protein) in the Ratna cultivar and a sequential mode of senescence in the Pusa, Masuri and Kalojira cultivars were observed in intact rice plant. When the panicles were removed from the plant, a delayed senescence compared with the intact control plants was observed. Again, when both panicle and daughter shoots were removed from the plant, leaf senescence of the mother plant was further delayed. The senescence behavior of the newly-developed daughter shoot was identical with that of the mother plant.M. A. C. thankfully acknowledges the financial help rendered by the C.S.I.R. (New Delhi) in the form of a Research Project (No. 38 (394)/(81-EMR II). W.A.M. wishes to thank Dr. S. Ray for his help and co-operation during this investigation.     

Proline synthesis from glutamate in the mitochondria isolated from a blowfly,Aldrichina grahami

Summary Proline biosynthesis from glutamate was demonstrated in a cell free system prepared from blowfly abdomen. The biosynthetic activity was found mainly in the mitochondrial fraction. The biosynthesis of proline from glutamate required ATP, NADPH and Mg⁺⁺ as cofactors.     

Accumulation of drastic mutants in selection lines for resistance to the insecticides dichlorvos and malathion inDrosophila melanogaster

Summary Viability tests were performed on second and third chromosomes from lines ofDrosophila melanogaster selected for increased resistance to the organophosphorus insecticides dichlorvos and malathion, in order to evaluate the accumulation of drastic alleles. Our results show that malathion reduces significantly the relative viability of chromosome 3 and also increases the frequency of drastic alleles in this chromosome, while dichlorvos increases significnatly the frequency of drastic alleles in chromosome 2.Work supported in part by the Spanish Ministry of Education and Science (Grant No. 0577/84 CAICYT).—We are grateful to Productos Cruz Verde S.A. and Agrocrós S.A. for generously supplying the insecticides dichlorvos and malathion, respectively.     

Cyclohexadienones-insect growth inhibitors from the foliar surface and tissue extracts ofSenecio cannabifolius

Dewaxed leaf surface extracts of 12 plants from Hokkaido, prepared by dipping fresh leaves in chloroform for 3 min, were used in a choice leaf-disk bioassay against larvae of the tobacco cutwormSpodoptera litura. Activity was found only in the extract ofSenecio cannabifolius, a very successful weed in Hokkaido. Individual fractions of the extract, however, were not active. Incorporation of the individual fractions of the surface extracts as well as fractions of the methanolic extracts of the leaf residue into an artificial diet fed to neonateS. litura led to the isolation of ethyl (1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl) acetate, the major surface compound, as the active principle. This compound was also present in the methanolic extract of the leaf residue together with methyl (1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl) acetate, which had the same growth inhibitory effect on the larvae. The presence of these compounds in the foliar surface and tissue suggests a defensive role against herbivores.     

Leaf-blade crimping in grasses: A new measure of growth

In grasses, ligules compress and permanently crimp emerging leaf-blades (primary crimping). Ligule compression may also mark the abaxial surface of older leaves in some species (secondary crimping). Secondary crimping appears directly related to leaf daily growth rate. Leaf-blade crimping can be used for determination of relative tissue age and as a natural record of growth rate in grasses.     

In vitro flowering of orange jessamine (Murraya paniculata (L.) Jack)

Branch internodes ofMurraya paniculata flowered in vitro on half-strength MT medium containing 5% sucrose supplemented with cytokinins. The cytokinins only induced vegetative shoots from the epicotyl of seedlings. The highest percentage of flowering (76.7% of the explants) was achieved from branch internodes of flowering plants close to the apex, on half-strength MT medium containing 5% sucrose and 0.001 mg l¹ benzyladenine (BA) in light. Flowering required two days' exposure to BA, but shoot formation could be initiated even without exposure to BA.     

Airborne methyl jasmonate stimulates the biosynthesis of furanocoumarins in the leaves of celery plants (Apium graveolens)

When leaves ofApium graveolens are exposed to vapours of methyl jasmonate (MeJa) or fed through the petiole with aqueous solutions of jasmonic acid (Ja), the levels of natural furanocoumarins, in particular xanthotoxin and bergapten, are greatly increased. The induction becomes manifest after application of 20 nmol of either Meja or Ja. Levels of xanthotoxin and bergapten begin to increase approximately 24 h after application of the inducer. Maximum concentration of the two furanocoumarins (40–70 fold increase) is reached after 4–6 days. This pronounced effect of volatile MeJa on the physiological status of the celery leaf may be considered as representative of a build-up of chemical defenses, in an undamaged plant, after receipt of airborne signals from damaged or undamaged, but fragrant plants.     

云南省余甘子灌丛生态系统生物量分配特征

采用样地调查的方法,在余甘子分布较典型地区按径级大小收获30株余甘子,并按照根、茎和叶等器官分别计算。研究结果表明：1）余甘子各器官的生物量分配为茎〉根〉叶;2）余甘子的基径和冠幅面积与余甘子各器官生物量分配有着密切的关系,其中基径与生物量密切相关,拟合度最好R^2=0．943,其次为冠幅,R^2=0．741;植株高度与余甘子各器官生物量分配相关性最差,R^2=0．359;3）根据R^2大小,可得知,以基径模拟余甘子生物量的最佳模型是多项式模型,以冠幅面积模拟则是幂函数模型最佳。     

A testis-specific lactate dehydrogenase in the pipid frog,Hymenochirus boettgeri

Summary Lactate dehydrogenase zymograms of mature testes ofHymenochirus boettgeri show in addition to the five isozymes composed of LDH-A and LDH-B subunits, a second 5-band system which is due to isozymes formed between LDH-A and a third subunit, LDH-C. These testis-specific LDH-C isozymes appear around 6 months after metamorphosis indicating that their expression is correlated with sexual maturity as is generally the case in mammals. This is the first report of a testis-specific LDH isozyme in a lower tetrapod; such isozymes have hitherto only been reported in mammals and in the pigeon.This study was supported by a grant from the Fond National Suisse de la Recherche Scientifique to H.R.K. We thank M. Sateur and F. Bourquin for their technical help.     

Four tails problems for dynamical collapse theories

The primary quantum mechanical equation of motion entails that measurements typically do not have determinate outcomes, but result in superpositions of all possible outcomes. Dynamical collapse theories (e.g. GRW) supplement this equation with a stochastic Gaussian collapse function, intended to collapse the superposition of outcomes into one outcome. But the Gaussian collapses are imperfect in a way that leaves the superpositions intact. This is the tails problem. There are several ways of making this problem more precise. But many authors dismiss the problem without considering the more severe formulations. Here I distinguish four distinct tails problems. The first (bare tails problem) and second (structured tails problem) exist in the literature. I argue that while the first is a pseudo-problem, the second has not been adequately addressed. The third (multiverse tails problem) reformulates the second to account for recently discovered dynamical consequences of collapse. Finally the fourth (tails problem dilemma) shows that solving the third by replacing the Gaussian with a non-Gaussian collapse function introduces new conflict with relativity theory.     

Hydrolysis of isoprenyl diphosphates with the acid phosphatase fromCinnamomum camphora

Direct observations of the enzymatic hydrolysis of C₁₀ acyclic allylic isoprenyl diphosphates by an acid phosphatase from the leaves ofCinnamomum camphora (camphor tree) were made using¹H and³¹P NMR spectrometers. The measurements indicated that the allylic primary diphosphates, geranyl diphosphate and neryl diphosphate, were hydrolyzed to their corresponding alcohols in a sequential manner via their corresponding monophosphates, whereas the allylic tertiary diphosphate, linalyl diphosphate, was hydrolyzed only to its corresponding monophosphate.     

Hepatic proline after bile duct ligation in rats

Since biliary hyperplasia of fascioliasis correlated with hepatic proline level, we examined the occurrence of a similar chemical stimulus during bile obstruction. Uptake of tritiated proline and glycine rose in both hepatocytes and a bile duct enriched cell fraction, following duct ligation in rats. The increased hepatic content of proline but not glycine suggests that proline has a role in post-obstructive biliary proliferation.     

Comparative study of oxalate oxidase in three genotypes ofSorghum vulgare

Summary The presence of an oxalate oxidase (EC 1.2.3.4) has been demonstrated in 15,000×g supernatants prepared from 10-day-old seedlings of three genotypes ofSorghum vulgare: grain sorghum hybrid (CSH-5), grain-cum-forage sorghum (PC-6) and forage sorghum (PC-1). The specific activity of the enzyme in the different tissues of seedlings was found to be present in the order leaves > stems > roots in PC-6 and PC-1, but this order was reversed in CSH-5. A comparison of the different properties of the leaf enzyme of these three genotypes of sorghum revealed that the enzyme has maximum activity in the acidic pH range from 4.0 to 5.0 and in the temperature range from 37°C to 40°C. The enzyme was stimulated by Cu²⁺ and Fe²⁺. The rate of H₂O₂ formation in the enzyme reaction was linear up to 5 min and was stoichiometrically related to oxalate consumption. The enzyme is unaffected by Na⁺ at physiological concentration (0.15 M). The superiority of this enzyme over moss and other plant enzymes for enzymic determination of urinary oxalate is discussed.     

Biochemical approaches to the study of plant-fungal interactions in arbuscular mycorrhiza

This communication compares some biochemical methods for quantifying colonization by arbuscular mycorrhizal (AM) fungi. The degree of mycorrhizal colonization can conveniently be measured by determining fungal specific sterols. AM-colonized plants show a specific synthesis of 24-methylene cholesterol and an enhanced level of campesterol (=24-methyl cholesterol). A gene probe for nitrate reductase, the key enzyme for nitrogen assimilation, has been developed, which allows the monitoring of the distribution of this enzyme in fungi. Among the phytohormones tested, only abscisic acid (ABA) is found at a considerably higher level in AM-colonized plants than in controls. The concentration of ABA is about twenty times higher in spores and hyphae of the AM fungusGlomus than in maize roots. Other phytohormones (auxins, cytokinins) do not show such alterations after mycorrhizal colonization. The roots of gramineous plants become yellow as a result of mycorrhizal colonization. The yellow pigment(s) formed is (are) deposited in larger quantities in the vacuole(s) of the root parenchyma and endodermis cells during the development of the gramineous plants. A substance isolated from such roots has now been identified as a C-14 carotenoid with two carboxylic groups, and named mycorradicin.     

Mixed life cycles in the transitional zone between voltinisms in the fall webworm,Hyphantria cunea

The fall webworm,Hyphantria cunea Drury, was introduced from North America into Japan at half a century ago. At present, the populations north of 36° N are bivoltine and those south of 36° N are trivoltine. In the present study, the life cycle in the transitional zone between voltinisms was clarified in Tsukuba (36.1° N). When fourth instar larvae of the second generation were collected in the field and maintained in the laboratory, the incidence of pupal diapause increased when the sampling date was delayed from 16 August to 5 September. The fact that some developed without diapause inidcates the occurrence of a trivoltine life cycle in this locality, where a bivoltine life cycle is predominant. The critical photoperiod for diapause induction at 20 and 25°C was 14 h 13 min and 14 h 10 min, respectively. The photoperiodic response may explain the rapid increase in diapause incidence in late summer. In laboratory-reared diapause pupae, the time and period of chilling (5°C) greatly influenced the time required for adult emergence at the final incubation temperature of 25°C. However, diapause pupae chilled for a sufficiently long period developed to adulthood rapidly, irrespective of the conditions before chilling. Therefore, the difference in timing of entering diapause between pupae of the second and third generations would not result in their temporal reproductive isolation in the following spring. It is concluded that the mixed voltinism in Tsukuba is not a result of a mixture of genetically distinct bivoltine and trivoltine populations, but a result of the phenotypic plasticity in a genetically rather homogeneous population.     

Hydroxydihydroergosine,a new ergot alkaloid analogue from directed biosynthesis bySphacelia sorghi

Summary A new ergot alkaloid, 9-hydroxydihydroergosine, has been produced by axenic cultures ofSphacelia sorghi to which 4-hydroxy-proline was added when biomass accumulation was complete. Evidence for a lack of biosynthetic specificity for the first, second and third amino acid in cyclic tripeptide alkaloids has now been found amongst ergot fungi.Supported by the Science Research Council and Roche Products Ltd.     

Selective herbivory on mosaic leaves of variegatedAcer pseudoplatanus

Summary The color mosaicism was observed to correlate with selective herbivory on different leaf areas of individual leaves of the variegated sycamoreAcer pseudoplatanus. The mosaicism affected the content of nutrients and of phenolic compounds and also the mechanical properties of the different leaf areas; this offers an explanation for the observed selective feeding by insect herbivores.Acknowledgments. We wish to thank S. Neuvonen for critical comments and C. Grapes for checking the language. The work was supported by the Academy of Finland and J. Salo Foundation.     

Distribution of chlorophyllase activity and levels of chlorophylls a and b in sandal (Santalum album L.) affected by spike disease

Summary Compared to healthy specimens, the levels of chlorophylls a and b and the activity of chlorophyllase towards the two pigments remained lower in the leaves of spiked sandal at all stages of leaf development, except in the senescing diseased leaves where the chlorophyllase activity showed a steep rise.     

Thiarubrine A,a bioactive constituent ofAspilia (Asteraceae) consumed by wild chimpanzees

Summary Two African species ofAspilia (Asteraceae), which are used medicinally by man and which are eaten by wild chimpanzees in an unusual manner, were found to contain the potent antibiotic thiarubrine A as a major leaf phytochemical. Its presence in leaf material strengthens the view that the feeding behavior of wild chimpanzees is related to special physiological or pharmacological effects on the animals.