Action pattern of polysaccharide lyases on glycosaminoglycans

The action pattern of polysaccharide lyases on glycosaminoglycansubstrates was examined using viscosimetric measurements andgradient polyacrylamide gel electrophoresis (PAGE). Heparinlyase I (heparinase, EC 4.2.2.7 [EC] ) and heparin lyase II (no ECnumber) both acted on heparin in a random endolytic fashion.Heparin lyase II showed an ideal endolytic action pattern onheparan sulphate, while heparin lyase I decreased the molecularweight of heparan sulphate more slowly. Heparin lyase III (heparitinase,EC 4.2.2.8 [EC] ) acted endolytically only on heparan sulphate anddid not cleave heparin. Chondroitin ABC lyase (chondroitinaseABC, EC 4.2.2.4 [EC] ) from Proteus vulgaris acted endolytically onchondroitin-6-sulphate (chondroitin sulphate C) and dermatansulphate at nearly identical initial rates, but acted on chondroitin-4-sulphate(chondroitin sulphate A) at a reduced rate, decreasing its molecularweight much more slowly. Two chondroitin AC lyases (chondroitinaseAC, both EC 4.2.2.5 [EC] ) were examined towards chondroitin-4- and-6-sulphates. The exolytic action of chondroitin AC lyase Afrom Arthrobacter aurescens on both chondroitin-4- and -6-sulphateswas demonstrated viscosimetrically and confirmed using bothgradient PAGE and gel permeation chromatography. ChondroitinAC lyase F from Flavobacterium heparinum (Cytophagia heparinia)acted endolytically on the same substrates. Chondroitin B lyase(chondroitinase B, no EC number) from F.heparinum acted endolyticallyon dermatan sulphate giving a nearly identical action patternas observed for chondroitin ABC lyase acting on dermatan sulphate. action pattern chondroitin lyase glycosaminoglycan heparin lyase.     

Isolation of Avian and Mammalian Pineal Indoles and Antigonadotropic Factors

With mild extraction and separation methods it was possibleto locate and isolate, starting with 100 or 200 g of pinealtissue, different indoles, with mass spectra identical to thoseof synthetic melatonin, 5-HIAA and 5-MIAA. It was also possibleto isolate fractions, which showed, in thin-layer chromatographicstudies, spots with R_f values identical to those of synthetic5-HTL and 5-MTL. A "non-melatonin" antigonadotropin, in an in vivo bioassay,was also isolated from sheep pineals and partially purified. Antigonadotropic and gonadotropic activities, which differ fromthe above described indoles, could be located with the samemethods. Some of these compounds acted on the hypothalamus,while others acted on the anterior hypophysis in vitro.     

Electron donor-specificity observed in photosystem I reactions of membrane fragments of the blue-green alga Anabaena variabilis and the higher plant Spinacea oleracea

Electron donating activities of plastocyanins and c-type cytochromesof various organisms for photosystem I reactions were studiedwith membrane fragments of the blue-green alga Anabaena variabilisand the higher plant Spinacea oleracea. In the Anabaena photosystem I reaction, basic but not acidicplastocyanin and c-type cytochromes acted as efficient electrondonors, while only acidic redox proteins were active in thespinach photosystem I reaction. The selective reactivity ofredox proteins in the two photosystem I reactions was observedwith both plastocyanin (or cytochrome) limited and saturatedconditions. These data support our previous observation that photosystemI of blue-green algae differs from those of other green plantswith respect to specificity to the proteinous electron donor(1). (Received August 17, 1971; )     

Time of Flowering of Pea (Pisum sativum L.) as a Function of Leaf Appearance Rate and Node of First Flower

In order to assess the influence of environmental conditionson time of flowering of pea (Pisum sativum L.), a serial sowingtrial was conducted over 2 years at Dijon, France, on two wintercultivars Frisson and Frilene. Time of flowering was analysedaccording to two variables: the leaf appearance rate R_L andthe node of first flower N_I. R_L was linearly related to temperature (r² = 0·94). Thebase temperature was 2°C for both varieties. Growth rateaccounted for the residual variability of R_L . Photoperiod andtemperature acted on N_I in an additive way. Frilene, the latergenotype, was more responsive than Frisson. A model for predicting time of flowering based upon these resultsis proposed. Deviations from this model were related to N nutritionin interaction with the plant water relations. Steps for improvingthe model are then discussed.Copyright 1993, 1999 Academic Press Pisum sativum L., pea, flowering, temperature, photoperiod, phyllochron, model     

A promotive action of kinetin on amylase activity in cotyledons of Phaseolus vulgaris

Kinetin and the embryo axis acted similarly in bringing abouta promotion of amylase activity in cotyledons of Phaseolus vulgaris.No promotive effect of gibberellic acid or indole-3-acetic acidon amylase activity could be detected. It is suggested thatthe regulatory action of the embryo axis on starch degradationin the cotyledons of P. vulgaris is mediated by cytokinins. (Received May 4, 1970; )     

Auxospore Structure, Initial Valves and the Development of Populations of Stephanodiscus in Farmoor Reservoir

A population of the planktonic diatom Stephanodiscus growingin Farmoor Reservoir has been investigated with regard to auxosporeformation and the subsequent change in cell size. This is thefirst account of auxospores in Stephanodiscus. The auxosporewall is believed to be organic without any siliceous components.Germination results in two large hemispherical initial valveswhich are rather crudely formed and lack the ring of spinescharacteristic of the vegetative cells which are figured forcomparison. The division of the initial cell to form hemisphericalcells is recorded. These then form a normal vegetative celland a hemispherical cell. The hemisperhical cells acted as markersin the natural population and their longevity was determined.The natural populations did not exhibit a continuous decreasein cell diameter, at times remaining almost constant and atother times decreasing. The origin and ratio of occurrence ofbiconcave, biconvex and concavo-convex cells in the populationis discussed. Stephanodiscus, diatom, auxospore, diatom cell size     

苦皮藤素Ⅴ对东方粘虫肌细胞的影响

苦皮藤素Ⅴ是从杀虫植物苦皮藤Celustrus angulatus Max.根皮中分离的一种对昆虫具毒杀活性的新化合物。采用电子显微镜技术研究了苦皮藤素Ⅴ对东方粘虫Mythimna separata（Walker）肌肉系统的作用。电镜观察发现,苦皮藤素Ⅴ对东方粘虫成虫飞行肌和幼虫体壁肌均具致毒作用,中毒试虫肌细胞特别是肌细胞的质膜及内膜系统发生明显病变：肌膜破坏,脱落;线粒体肿胀,空泡化,崩解;肌原纤维与线粒体间间隙增大;肌质网扩张,产生髓鞘样结构;细胞核肿胀,核质浓缩,核膜破坏;微气管与肌细胞之间间隙增大;肌小节弥散、排列紊乱。这些结果表明,肌细胞质膜及内膜系统可能是苦皮藤素Ⅴ的一个作用部位。     

Characterisation of Acidic and Basic Apoplastic Peroxidases from Needles of Norway Spruce (Picea abies, L., Karsten) with Respect to Lignifying Substrates

Acidic and basic peroxidases, termed as POD-A and POD-B, wereisolated from the apoplastic space of spruce (Picea abies, L.)needles and purified by acetone precipitation and anion exchangechromatography to apparent homogeneity. The molecular massesof POD-A and POD-B were 39.6 and 29.0 kDa, respectively. ThepH optimum of both isozymes ranged from 4.5 to 6. The apparentK_m values of POD-A and POD-B were 460 and 210 µM for coniferylalcohol. Both isozymes acted also as NADH oxidases with apparentK_m-values of 103 µM (POD-A) and 70 µM (POD-B). NAD⁺but not NADH was found in the apoplastic space of lignifyingneedles. Based on the lignification rate, the contents and kineticproperties of PODs, NADH oxidation by POD is not the major sourceof H₂O₂ required for lignin polymerisation. (Received December 21, 1996; Accepted March 3, 1997)     

Effect of Sodium on Phosphate Uptake in Unicellular and Filamentous Cyanobacteria

The effect of Na⁺ on phosphate uptake was studied in four strainsof cyanobacteria: Synechococcus PCC 7942, Gloeothece PCC 6501,Phormidium sp. and Chlorogloeopsis PCC 6912. Phosphate uptakewas stimulated by Na⁺ in all cases. Li⁺ and K⁺ acted as partialanalogues for Na⁺. Half-saturation [K_1/2(Na⁺)] of phosphateuptake was reached with Na⁺ concentrations ranging from 317µM in Chlorogloeopsis to 659 µM in Phormidium. Theconcentration of phosphate required to reach half-saturationof phosphate uptake [K_1/2(P_i)]was not changed by the presenceof Na⁺. (Received April 11, 1994; Accepted July 5, 1994)     

Studies on the Hill reaction of membrane fragments of blue-green algae I. Stabilizing effect of various media on the 2,6-dichlorophenol indophenol-Hill activity of membrane fragments obtained from Anabaena cylindrica and Anabaena variabilis

The stability of DPIP-Hill activity of membrane fragments fromblue-green algae was investigated in various suspension media.Two blue-green algae, Anabaena cylindrica and A. variabiliswere used. Activities for the DPIP-Hill reaction were stable in the twoalgal preparations only when preparations were suspended ina medium containing high concentrations of carbohydrates orPEG. Required concentrations of carbohydrates or PEG differedgready in die two preparations; 1.5 M sucrose or 20% PEG forA. cylindrica and 0.3 M sucrose or 6% PEG for A. variabiliswere minimal for maintaining full activity in 2 hr incubationat 0°C, respectively. Below these concentrations, activitiesdecreased rapidly. In both preparations, stabilizing effects,on a molar basis, varied in different kinds of solutes. However,a simple relation was found between the effects and water concentrationsof media. In A. cylindrica, a 50% decay in activity occurredin 2 hr incubation at 0°G in a medium with 43.8 M water,and, in A. variabilis, the water concentration was 53.4 M. In media free of carbohydrate or PEG, Mg++ ion had a moderatestabilizing ability. EDTA acted antagonistically to Mg++. Effectiveconcentrations were the same in two preparations. However, inthe medium containing carbohydrate or PEG, their actions wereinsignificant. Results suggest that the molecular organization in membranesnecessary for Hill reaction is easily destroyed under high waterconcentrations, and that added solutes stabilize the activityby reducing water concentrations. (Received February 13, 1971; )     

Connexin46 mutations linked to congenital cataract show loss of gap junction channel function

Human connexin46 (hCx46) forms gapjunctional channels interconnecting lens fiber cells and appears to becritical for normal lens function, because hCx46 mutations have beenlinked to congenital cataracts. We studied two hCx46 mutants, N63S, amissense mutation in the first extracellular domain, and fs380, aframe-shift mutation that shifts the translational reading frame atamino acid residue 380. We expressed wild-type Cx46 and the two mutantsin Xenopus oocytes. Production of the expressed proteins wasverified by SDS-PAGE after metabolic labeling with[³⁵S]methionine or by immunoblotting. Dualtwo-microelectrode voltage-clamp studies showed that hCx46 formed bothgap junctional channels in paired Xenopus oocytes andhemi-gap junctional channels in single oocytes. In contrast, neither ofthe two cataract-associated hCx46 mutants could form intercellularchannels in paired Xenopus oocytes. The hCx46 mutants werealso impaired in their ability to form hemi-gap-junctional channels.When N63S or fs380 was coexpressed with wild-type connexins, bothmutations acted like "loss of function" rather than "dominantnegative" mutations, because they did not affect the gap junctionalconductance induced by either wild-type hCx46 or wild-type hCx50.

     

Para-nitrophenyl Phosphate as a Substrate for Some Acid Phosphatases in Roots of Vicia faba

A cytochemical and biochemical study of acid phosphatases inroots of Vicia faba using p-nitrophenylphosphate(p-NPP) as substratehas shown the lack of specificity of the substrate which canbe acted upon by a K⁺-activated acyl phosphatase, nucleotidepyrophosphatase, glucox-6-phosphatase, 5' (3')-ribonucleotidephosphohydrolase, nucleotide phosph-transferase and those acidphosphatases demonstrable with ß-glycerophosphate.It is suggested that care should be taken in the interpretationof both biochemical and cytochemical studies employing sucha non-specific substrate as P-NPP. Vicia faba, broad bean, root, acid phosphatases     

The participation of phytochrome in the signal transduction pathway of salt stress responses in Mesembryanthemum crystallinum L.

Continuous irradiation of Mesembryanthemum crystallinum plantswith light of equal amounts of photosynthetically active radiation,but widely different red:far red ratios was used to intervenein phytochrome-mediated signal transduction pathways in thepresence and absence of salt stress. Light with a low ratioof red:far red (in contrast to light with a high ratio of red:farred), caused induction of PEP carboxylase activity, accumulationof the CAM isoform of PEP carboxylase, and the accumulationof malate anion. Taking these as indicators of CAM inductionit is concluded that phytochrome can participate in the signaltransduction pathway leading to CAM in M. crystallinum. A lowratio of red: far red light acted synergystically with saltstress in the induction of these CAM indicators. The simplestinterpretation of this interaction is that the phytochrome-mediatedeffects and salt stress effects acted on the same signal transductionpathway. The accumulation of pinitol was also increased by light witha low ratio of red:far red, consistent with the existence ofa stress syndrome in M. crystallinum which utilizes a commontransduction pathway. A low ratio of red:far red light induced a strong shade avoidanceresponse and, compared to light with a high red:far red ratio,modified chlorophyll content and betacyanin pigment complement. Plants grown in light with a low ratio of red:far red floweredearlier than plants grown in light with a high red:far red ratio. It is concluded that phytochrome can participate in the signaltransduction pathway leading to the induction of both CAM andthe processes which result in pinitol accumulation and pigmentationin M. crystallinum, as well as in the mediation of shade avoidanceand flowering responses. Key words: Mesembryanthemum crystallinum, CAM, phytochrome, signal transduction, drought stress     

Motor Control Across Trophic Strategies: Muscle Activity of Biting and Suction Feeding Fishes

Many fishes use a powerful bite of the oral jaws to captureor tear their prey. This behavior has received less study fromfunctional morphologists and physiologists than suction feeding,and presents an opportunity to examine motor control of fishfeeding across alternative prey-capture strategies. We usedelectromyography to compare muscle activity patterns of thefeeding bite in five teleost fishes representing at least threelineages in which biting has been independently acquired: twoparrotfish (Cetoscarus bicolor and Scarus iseri), a wrasse (Cheilinuschlorourus), and two serrasalmines, a pacu (Piaractus brachypomus)and a piranha (Pygocentrus nattereri). Multivariate analysisindicated that muscle activity patterns differed significantlyamong species, although a four-way ANOVA designed to test fordifferences within a phylogenetic hierarchy revealed that thebiting motor pattern was largely similar for both narrow andbroad phylogenetic comparisons. A comparison of the motor patternsof biting and suction feeding species revealed that biters hadsignificantly shorter durations of the epaxialis and sternohyoideusand significantly longer relative onset times of the epaxialis,adductor mandibulae, and sternohyoideus. Character mapping oftiming variables suggested that short relative onset times areprimitive for suction feeders and that this characteristic isgenerally retained in more advanced species. Despite these differences,all species overlap extensively in multivariate EMG space. Ourresults demonstrate that change in the feeding motor patternhas accompanied morphological and behavioral change in transitionsfrom suction to biting, which suggests that the neuromotor systemhas not acted as a constraint on the evolution of the feedingsystem in fishes.     

Host-Parasite Relations in Loose Smut of Wheat: III. The Utilization of 14C-Labelled Assimilates

Infection of wheat by Ustilago nuda caused an increased rateof export of radioactivity from the sixth leaf of infected plantsas compared with healthy plants. The ear acted as the most important‘sink’, in both infected and healthy plants. Erythntol,mannitol, and trehalose were present in the infected ears andnodes, but were not present in the healthy plants. Radioactivitywas incorporated into these compounds in the infected ear, andthis was reflected in a lower percentage in the insoluble fractionthan in the healthy ear.     

Enzyme system catalyzing formation of cis-3-hexenal and n-hexanal from linolenic and linoleic acids in Japanese silver (Farfugium iaponicum Kitamura) leaves

Leaf alcohol (cis-3-hexenol) and leaf aldehyde (trans-2-hexenal)are responsible for the green odor in leaves and fruits. cis-3-Hexenal,a precursor of cis-3-hexenol and trans-2-hexenal, was producedfrom linolenic acid by a homogenate of Farfugium japonicum (Japanesesilver) leaves. n-Hexanal was produced from linoleic acid bya homogenate of the leaves. The enzyme system catalyzing formationof C₆-aldehydes from linolenic and linoleic acids was localizedin chloroplast lamellae, and required oxygen for reaction. C₁₈-unsaturatedfatty acids such as linolenic acid, linoleic acid and -linolenicacid, which have carboxyl groups and cis-1, cis-4-pentadienesystems including a double bond at C-12, acted as substrates,and C₆-aldehydes (cis-3-hexenal or n-hexanal), but not C₉-aldehydes,were produced from them. The properties of the enzyme systemin chloroplasts were as follows: optimal pH 7.0; stable at pH5 to 7; thermolabile and no activity at 50?C. These propertieswere very similar to those of tea chloroplasts. The enzyme systemcould be solubilized from chloroplasts by 2% Triton X-100, butwas very unstable in solubilized form. (Received July 9, 1976; )     

Purification and Characterization of a Vegetative Lytic Enzyme Responsible for Liberation of Daughter Cells during the Proliferation ofChlamydomonas reinhardtii

A vegetative lytic enzyme (VLE) of Chlamydomonas reinhardtiimediates digestion of the cell walls of mother cells (sporangia)to allow release of daughter cells after mitotic cell divisionin the vegetative cell cycle. This enzyme is secreted into theculture medium concurrently with the appearance of daughtercells in synchronized cultures. Using an assay that monitorsdigestion of the mother cell wall, we purified VLE by ion-exchangeand gel-filtration chromatography from the medium of synchronizedcultures. The purified enzyme was a basic glycoprotein withan apparent molecular mass of 120 kDa on gel filtration and130 kDa on SDS-PAGE. Thus, VLE appeared to behave as a monomer.The enzyme acted specifically on the mother cell wall and wasunable to digest the cell walls derived from single vegetativecells. The enzymatic activity was inhibited by PMSF, p-APMSF,TLCK, HgCl₂, iodoacetate, EGTA, EDTA and 1,10-phenanthroline.VLE cleaved several synthetic model peptides on the carboxylside of a Lys or Arg residue, indicating that it is a proteasethat acts on protein in the mother cell wall in vivo to releasethe daughter cells. (Received November 30, 1994; Accepted March 22, 1995)     

COMPARATIVE STUDIES OF PHOTOCHEMICAL OXIDATION-REDUCTION REACTIONS IN LAMELLAR FRAGMENTS OF VARIOUS ALGAE AND SPINACH

The activity of various electron carriers, including DPIP, spinachplastocyanin, mammalian cytochrome c, and Anabaena cytochrome553, as donor in the reaction induced by the photochemical systemI was examined with lamellar fragments of various algae andspinach. Reduced DPIP was an effective electron donor irrespective ofthe organisms, when it was supplied at a high concentration(10^–3 M). Spinach plastocyanin was effective in the reactionswith the lamellae of green algae, Euglena, diatom Phaeodactyrumand red algae Porphyra yezoensis and Porphyra sp. Yamamoto II,whereas it was inactive in the lamellae of blue-green algae.Horse-heart cytochrome c and Anabaena cytochrome 553 were activein the reaction with the lamellae of bluegreen algae. The formercytochrome was also active in the reactions in Porphyridiumand Cyanidium. The cytochromes were less active in the reactionsin which spinach plastocyanin acted as effective electron donor. The data were interpreted as that the photochemical system Iin bluegreen algae differs from that of other photosyntheticorganisms with respect to the properties of the site of theelectron-input. ¹ Present address: Nomura Research Institute for Technologyand Economics, Kamakura, Kanagawa. ² Present address: Ocean Research Institute, University of Tokyo,Nakano, Tokyo.     

The Influence of Resaturation Method and Tissue 3Quercus alba L. Seedlings

Parker, W. C. and Pallardy, S. G. 1987. The influence of resaturationmethod and tissue type on pressure-volume analysis of Quercusalba L. seedlings.—J. exp. Bot. 38: 535–549. The effect of resaturation method and amount of woody tissueon pressure-volume analysis was investigated using materialcollected from Quercus alba L. seedlings. Leaves excised fromwell-irrigated, intact plants had lower initial xylem pressurepotentials than did leaves resaturated by two artificial methods.Differential capacity for tissue rehydration among the threemethods was linked to shifts in the relative position of pressure-volumecurves, and differences in the osmotic potential and relativewater content at which turgor loss occurred were observed. Pressure-volumecurves from leaves resaturated by all three methods contained‘plateaus’ near full turgor, where xylem pressurepotential declined only slightly with relative water content.These plateaus were apparently associated with apoplastic waterthat accumulated in intercellular spaces of the leaf near fullturgidity, and acted to buffer changes in leaf xylem pressurepotential as tissues dehydrated. The presence of this waterhas implications for derived water relations parameter estimates.Pressure-volume curves for excised shoots also exhibited plateaus,but the relationship between xylem pressure potential and relativewater content over this region was steeper than was found forleaves. Shoot osmotic potentials were somewhat lower than thosefor leaves. The slope of the linear portion of shoot pressure-volumecurves was more shallow than for single leaves, a response associatedwith comparatively lower values of the symplastic water fractionin shoots. Key words: Pressure-volume curve, tissue-water relations, elasticity     

Feeding selectivities and food niche separation of Acartia clausi, Penilia avirostris (Crustacea) and Doliolum denticulatum (Thaliacea) in Blanes Bay (Catalan Sea, NW Mediterranean)

Selectivity-size spectra, clearance and ingestion rates andassimilation efficiencies of Acartia clausi (Copepoda), Peniliaavirostris (Cladocera) and Doliolum denticulatum (Doliolida)from Blanes Bay (Catalan Sea, NW Mediterranean) were evaluatedin grazing experiments over a wide range of food concentrations(0.02–8.8 mm³ L^–1 plankton assemblages from BlanesBay, grown in mesocosms at different nutrient levels). Acartiaclausi reached the highest grazing coefficients for large algae>70 µm (longest linear extension), P. avirostris forintermediate food sizes between 15 and 70 µm, and D. denticulatumfor small sizes from 2.5 to 15 µm. Penilia avirostrisand D. denticulatum acted as passive filter-feeders. Acartiaclausi gave some evidence for a supplementary raptorial feedingmode. Effective food concentration (EFC) decreased linearlywith increasing nutrient enrichment for D. denticulatum andfollowed domed curves for A. clausi and for P. avirostris withmaximum values at intermediate and high enrichment levels, respectively.Clearance rates of crustacean species showed curvilinear responseswith narrow modal ranges to increasing food concentration. Clearancerates of D. denticulatum increased abruptly and levelled intoa plateau at low food concentrations. Mean clearance rates were13.9, 25.5 and 64.1 mL ind.^–1 day^–1, respectively.No clearance could be detected for A. clausi at food concentrations<0.1 mm³ L^–1 and for P. avirostris at food concentrations