Induction of indole synthesis in the appendix of Sauromatum guttatum Schott

Induction of indole synthesis in young appendix sections ofSauromatum guttatum Schott was studied. The inducer, known ascalorigen, a compound synthesized in the mature staminate flowerbuds, is capable of triggering a rapid metabolic spurt in theappendix of the inflorescence. The induced indole-formationlasts for only a short period of time, and is similar to thenormal pattern of indole synthesis. Under the experimental conditions,indole was detectable after 7 to 8 hr of calorigen treatmentbut had disappeared about 35 hr later. The moment when indoleis present in maximal amount coincides with that of maximalheat production, i.e., about 27 hr after the application ofcalorigen. A simple and sensitive bioassay for detection ofcalorigen, based on the formation of indole, could be devised. Calorigen also causes, to a lesser extent, a temperature-riseof those young floral parts (male, female and sterile tissues)where indole is not detectable at any time. The time sequenceof the induced production of heat for the various floral partsmimics that of a natural metabolic flare-up. Extracts prepared from the mature staminate flowers of Arummaculatum L., Arum dioscoridis Sibth and Sm., and Dracunculusvulgaris Schott were all able to induce the formation of indolein the appendix of Sauromatum in a fashion similar to that causedby the staminate flower extract of this plant. (Received February 12, 1972; )     

Chlorophyll fluorescence characteristics of system I chlorophyll {alpha}-protein complex and system II particles at room and liquid nitrogen temperatures

Emission spectra of a system I chlorophyll (Chl) -protein complex(SI Chl-P)³ and system II particles, prepared by the methodof Dietrich and Thornber (25), and by the method of Huzisigeet al. (24), respectively, were measured at room and liquidnitrogen temperatures to characterize the emission bands originatingfrom system I and system II. Room temperature and 77°K spectra clearly show that theF695 (690–697 nm) fluorescence band originates from bothphotosystems. In SI Chl-P the F695 band was observed both atroom and at liquid nitrogen temperatures. At 77°K, the Chl fluorescence at 685 nm is nearly as intenseas that at 720 nm (long-wavelength band) in dilute samples ofSI Chl-P. Reabsorption of 685 nm fluorescence has distortedconsiderably the shape of emission spectra of system I publishedthus far. In dilute samples of system II, the F695 is as (ormore) intense as F685, and the F735 is drastically decreased. Additionally, it is reported here that in Cyanidium caldarium,studied to compare the in vivo system with isolated SI Chl-Pand system II preparations, the 695 nm band is present uponexcitation in both system I and system II; the ratio of thelong-wave length fluorescence (F735) to the short-wavelengthfluorescence (F685) is much higher than those in the purifiedpreparations. Conceivably, the high values, obtained in thedilute samples of algae, are due to the reabsorption of thefluorescence from the short-wavelength form of Chl in the chloroplastin vivo. Furthermore, in this alga the phycocyanin fluorescenceband is split with maxima at 655 (phycocyanin) and 665 nm (allophycocyanin)at 77°K. At room temperature, however, the allophycocyaninfluorescence predominates having a peak at about 670 nm. Therelative increase in phycocyanin fluorescence at 77°K maybe due to a decrease in the energy transfer from it to allophycocyaninin agreement with slow Förster type transfer. ² Department of Botanical Sciences, University of California,Los Angeles, California 90024, U. S. A. (Received September 7, 1971; )     

Photochemical Apparatus Organization in the Diatom Cylindrotheca fusiformis: Photosystem Stoichiometry and Excitation Distribution in Cells Grown under High and Low Irradiance

The photochemical apparatus organization in the thylakoid membraneof the diatom Cylindrotheca fusiformis was investigated in cellsgrown under high and low irradiance. High light (HL, 200µE.m^–2.s^–1)grown cells displayed a relatively low fucoxanthin to chlorophyll(Chl) ratio, a low photosystem (PS) stoichiometry (PSII/PS I=1.3/1.0)and a smaller photosynthetic unit size in both PS I and PS II.Low light (LL, 30µE.m^–2.s^–1) grown cells displayeda 30% elevated fucoxanthin content, elevated PS II/PS I=3.9/1.0and larger photosynthetic unit size for PS II (a change of about100%) and for PS I (by about 30%). In agreement, SDS polyacrylamidegel electrophoresis of thylakoid membrane polypeptides showedgreater abundance of PS I, RuBP carboxylase and ATP synthasepolypeptides in HL cells. In contrast, LL grown cells exhibitedgreater abundance of light-harvesting complex polypeptides.Assuming an efficiency of red (670 nm) light utilization of1.0, the measured efficiency of blue (481 nm) light utilizationwas 0.64 (HL cells) and 0.72 (LL cells). The lower efficiencyof blue versus red light utilization is attributed to the quenchingof absorbed energy by non-fucoxanthin carotenoids. Differencesin the efficiency of blue light utilization between HL and LLgrown cells are attributed to the variable content of fucoxanthin.The results support the hypothesis of a variable Chl a-Chl c-fucoxanthinlight-harvesting antenna associated with PS II and PS I in Cylindrotheca. (Received February 10, 1988; Accepted April 6, 1988)     

Salicylic Acid Levels in Thermogenic and Non-Thermogenic Plants

The natural trigger for heat production in the thermogenic inflorescencesof Sauromatum guttatum Schott (voodoo lily) was recently identifiedas salicylic acid (SA), which induced heat production at levelsas low as 13 ng g f. wt^–1. Since then the levels of SAwere determined in other thermogenic and non-thermogenic plantspecies. In thermogenic inflorescences of five aroid species,and in male cones of at least four thermogenic cycads SA levelsduring heat production exceeded 1 µg g f. wt^–1.SA was not detected in the thermogenic flowers of a water lily,Victoria regia Lindl. (Nymphaeaceae), and Bactris major Jacq.(Palmae). Levels of salicylic acid varied substantially in thefloral parts of seven non-thermogenic species and in the leavesof 27 non-thermogenic species. Amorphophallus campanulatus Blume ex Decne, Arum italicum Mill., Arum dioscoridis Sibth. & Son., Philodendron selloum Koch, Monstera deliciosa Liebm., Encephalartosferox Bertol. f., Encephalartos hildebrandtii A. Br. & Bouché, Encephalartos gratus Prain, Dioon edule Lindl. cv. edule, Dioon edule Lindl. cv angustifolium, Sauromatum guttatum Schott, voodoo lily, Victoria regia Lindl., Bactris major Jack, salicylic acid, thermogenicity, heat production     

Photosynthetic Properties of Guard Cell Protoplasts from Vicia faba L.

Guard cell protoplasts were isolated enzymatically from theepidermis of Vicia faba L. and their photosynthetic activitieswere investigated. Time courses of light-induced changes inthe chlorophyll a fluorescence intensity of these protoplastsshowed essentially the same induction kinetics as found formesophyll protoplasts of Vicia. The transient change in thefluorescence intensity was affected by DCMU, an inhibitor ofphotosystem II; by phenylmercuric acetate, an inhibitor of ferredoxinand ferredoxin NADP reductase; and by methyl viologen, an acceptorof photosystem I. Low temperature (77 K) emission spectra ofthe protoplasts had peaks at 684 and 735 nm and a shoulder near695 nm. A high O₂ uptake (175 µmol mg^–1 Chl hr^–1)was observed in guard cell protoplasts kept in darkness, whichwas inhibited by 2 mM KCN or NaN₃ by about 60%. On illumination,this O₂ uptake was partially or completely suppressed, but itssuppression was removed by DCMU, which indicates that oxygenwas evolved (150 µmol mg^–1 Chl hr^–1) photosynthetically.We concluded that both photosystems I and II function in guardcell chloroplasts and that these protoplasts have high respiratoryactivity. (Received January 30, 1982; Accepted May 15, 1982)     

Some properties of the chlorophyll fluorescence of the diatom Phaeodactylum tricornutum

Fluorescence transients were investigated with the diatom Phaeodactylumtricornutum. Supplementary experiments were done with Chaetocerossp. Under weak excitation ({small tilde}10³ erg/cm²sec), fluorescencetransients were induced simply by die oxidation-reduction reactionof Q, the primary reductant of photosystem II. The action spectraindicated that the electron transfer components between thetwo photosystems were in the most reduced state when fucoxanthinwas excited. The transients were observed with the 681 run emissionand with the 707 nm emission at room temperature. At –196°C,induction due to the reduction of Q. appeared both at the 681and 707 nm emissions. Similar results were also obtained withChaetoceros sp. Under strong excitation (10⁴–10⁵ erg/cm²-sec), the fluorescencetransients due to the interconversion between States 1 and 2of die pigment system (cf. ref. 27, 29) were observed. The transientswere induced by die alternate excitation of chlorophyll a andfucoxanthin or chlorophyll c. Conversion from State 2 to State1 was inhibited by DNP and CCCP, indicating that die processwas energy-dependent. Fluorescence spectra at –196°Cwere not altered by die state-conversion of die pigment system. These results suggest diat all die fluorescence bands whichappeared at room temperature and at –196°C were dueto die chlorophyll a of pigment system II in Phaeodactylum andChaetoceros. (Received September 7, 1972; )     

The photosynthetic production of oxalic acid in Oxalis corniculata

The biogenesis of oxalic acid in Oxalis corniculata has beeninvestigated. In O. corniculata the bulk of the oxalic acidis produced by CO₂ fixation both in light and in darkness butthe rate of its photosynthetic formation is much higher thanin darkness. Several other plants some of which are known toaccumulate oxalic acid e.g., Biophytum sensitivum, Averrhoacarambola, Impatiens balsamina, Amorphophallus campanulatusand Colocassia antiquorum also fix ¹⁴CO₂ into oxalic acid photosyntheticallywithin 1 min of exposure to the gas. In O. corniculata ¹⁴C canbe detected in oxalic acid within 5 sec and about half of thetotal ¹⁴C fixed in the 70% ethanol soluble fraction can be locatedin this compound after 5 min. This is accompanied by a declineof radioactivity in two compounds, the chromatographic behaviourand melting points of one of which and its DNP hydrazone aresimilar to those of an authentic sample of glyoxylic acid. Whenglyoxylate 1, 2-¹⁴C is incubated with Oxalis leaf homogenateit is converted to oxalate-¹⁴C. Glycolate is also metabolizedto oxalate. The conversion of both glycolate and glyoxylateare favoured by light. The C₂ compounds acetate and glycinehowever are utilized rather poorly. Sucrose-¹⁴C is also notmetabolized markedly for this purpose. (Received August 20, 1969; )     

Permeability of Lipophilic Cations

The permeability (P) of a lipophilic cation, triphenylmethylphosphonium(TPMP⁺) which is frequently used as a membrane potential probe,has been measured in Chara australis (Charophyceae). P_TPMP+across biological membranes is usually thought to be very highbut this is not the case across the plasmalemma of Chara. Thepermeability of TPMP⁺ across the plasmalemma was found to betypical of inorganic cations, about 1.0 nm s^–1. Estimateswere made of the permeability of lipophilic cations across someother cell membranes, based on previously published work. Thepermeability of TPMP⁺ across the plasma membranes of the redalga, Griffithsia monilis and the blue-green alga, Anabaenavariabilis was about 2–5 nm s^–1. The permeabilityof TPMP⁺ across the plasma membranes of eukaryotes and prokaryotesappears to be similar. The permeability of lipophilic cationsacross the cristae of isolated mitochondria are exceptionallyhigh, about 170 nm s^–1. TPMP⁺ did not behave as a thiamineanalogue in Chara, unlike in the case of yeast. The means ofentry of TPMP⁺ into the Chara cell, driven by the electrochemicalgradient across the plasmalemma, has not been identified. Thepresence of a second lipophilic cation probe, DDA⁺ (dibenzyldimethylammonium),caused a decrease in the uptake flux of TPMP⁺; this suggeststhat the two lipophilic cations compete for the same site atthe surface of the plasmalemma. Key words: Chara australis, TPMP⁺, Permeability, Lipophilic cation     

Comparative Studies on the Properties of Two Ferredoxins from Pisum sativum L.

Two ferredoxins in approximately equal amounts were isolatedfrom 3 week old Pisum sativum L. seedlings. Both ferredoxinshad identical absorption spectra with maxima at 276, 327, 424,and 468 nm in the oxidized state, and each possessed a single2Fe-2S active centre. The isoelectric points of the two ferredoxinswere both at pH 3·3, and mixtures could not be separatedby isoelectric focusing on polyacrylamide gels. The midpointredox potentials of the ferredoxins were close to –415mV, but they differed slightly in their biological activity.Ferredoxin I was slightly the more active of the two in catalysingNADP⁺ photoreduction by Pisum or Hordeum chloroplasts whereasferredoxin II was more active in catalysing the oxidative cleavageof pyruvate by extracts of Clostridium pasteurianum. Thoughthe molecular weights of the ferredoxins determined by ultracentrifugationwere the same within experimental error, the amino acid compositionsshowed marked differences. The N-terminal 40 amino acid residuesof ferredoxins I and II were determined by means of an automaticsequencer. There were 15 differences, suggesting that gene duplicationhad occurred early in evolutionary time. Ferredoxin I appearsto be more closely related to the other angiosperm ferredoxinssince it differed in only 6 positions compared with the correspondingsequence for Medicago sativa (alfalfa) ferredoxin. The ratioof the two ferredoxins in Pisum sativum was shown to be dependenton the age of the seedlings and environmental growth conditions.     

Isourea and triazinone derivatives as related to their ability to stimulate rice seedling growth

TA [4-ethoxy-1-(p-tolyl)-s-triazine-2,6 (1H, 3H)-dione] wasprepared chemically by intramolecular cyclization of IU [2-ethyl-3-methoxycarbonyl-1-(p-tolylcarbamoyl)-isourea],which has been reported to be an effective GA-synergist. TAalone slightly stimulated the shoot growth of rice seedlings,and in combination with GA showed a distinctly synergistic effecton the growth of rice shoots. The results suggest that TA andIU are nearly equal in their physiological activity. From theresults of the rice seedling test of these two compounds andtheir analogs, structure-activity relationships of isoureaswere correlated with those of triazinones. The results of applicationof IU, at 100 mg/liter to rice seedlings followed by extractionand silica gel thin-layer chromatography, suggested that IUwas biologically converted into its closed-ring form, TA, whichis a stable and potent GA-synergist. Thus, isoureas like IUseem to be easily converted into their counterparts, triazinones,in rice tissues. ¹ This paper is Part III in the series "Plant growth-regulatingactivities of isourea derivatives and related compounds." ² Permanent address: Agricultural Chemicals Research Laboratories,Sankyo Co., Ltd., Hiro-machi, Shinagawa-ku, Tokyo 140, Japan. ³ Present address: Higashi-Osaka Junior College, Nishitsutsumigakuen,Higashi-Osaka 577, Japan. (Received February 21, 1977; )     

Microheterogeneity of N-glycosylation on a stylar self-incompatibility glycoprotein of Nicotiana alata

Gametophytic self-incompatibility, a mechanism that preventsinbreeding in some families of flowering plants, is mediatedby the products of a single genetic locus, the S-locus. Theproducts of the S-gene in the female sexual tissues of Nicotianaalata are an allelic series of glycoproteins with RNase activity.In this study, we report on the microheterogeneity of N-linkedglycosylation at the four potential N-glycosylation sites ofthe S²-glycoprotein. The S-glycoproteins from N.alata containfrom one to five potential N-glycosylation sites based on theconsensus sequence Asn-Xaa-Ser/Thr. The S²-glycoprotein containsfour potential N-glycosylation sites at Asn²⁷, Asn³⁷, Asn¹³⁸and Asn¹⁵⁰, designated sites I, n, IV and V, respectively. SiteIII is absent from the S₂-glycoprotein. Analysis of glycopeptidesgenerated from the S₂-glycoprotein by trypsin and chymotrypsindigestions revealed the types of glycans and the degree of microheterogeneitypresent at each site. Sites I (Asn²⁷) and IV (Asn¹³⁸) displaymicroheterogeneity, site II (Asn³⁷) contains only a single typeof N-glycan, and site V (Asn¹⁵⁰) is not glycosylated. The microheterogeneityobserved at site I on the S₂-glycoprotein is the same as thatobserved at the only site, site I, on the Srglycoprotein (Woodwardet al., Glycobiology, 2, 241-250, 1992). Since the N-glycosylationconsensus sequence at site I is conserved in all S-glycoproteinsfrom other species of self-incompatible solanaceous plants,glycosylation at this site may be important to their function.No other post-translational modifications (e.g. O-glycosylation,phosphorylation) were detected on the S₂-glycoprotein. fertilization microheterogeneity N-glycans plants RNase     

THE ULTRASTRUCTURE OF CILIATED CELLS FROM THE SIPHON OF SOLEN CAPENSIS (MOLLUSCA, BIVALVIA)

The structure of ciliated cells from the siphon of Solen capensishas been studied by both scanning and transmission electronmicroscopy. Two types of ciliated cell, based on the numberand length of cilia have been described which resemble thosedescribed in Donax. Type I is characterized by having 26–57({macron}= 43, n = 50) cilia which are 2.5 µm in length;Type II has fewer cilia (5–10; {macron}= 7) which are5 µn long. Both are primary receptors. Estimations ofabundance show that receptors are most numerous on the tipsof the siphon tentacles (8.8 x 10³/mm²). (Received 15 January 1985;     

Salinity and in vitro Ageing Effects on Primary Photosynthetic Processes of Thylakoids Isolated from Pisum sativum and Spinacia oleracea

The effects of in vitro ageing and salinity of the reactionmedium on the primary photochemistry of photosystem II and thepattern of energy distribution within the photochemical apparatusof thylakoids isolated from Pisum sativum and Spinacia oleraceaare described. Analyses of the low temperature induction curvesof fluorescence emission at 695 and 735 nm and of low temperatureabsorption and fluorescence emission spectra were used to examinethese processes. In vitro ageing over short periods reducedthe photochemical activity and changed the energy distributionwithin thylakoids of P. sativum, but had little effect on thylakoidsof S. oleracea. A synergistic effect of in vitro ageing andsalinity of the reaction medium was observed for P. sativumthylakoids. Ageing effects could be minimized by addition of100 mM NaCl to the resuspension medium. Changes in NaCl concentrationin the reaction medium produced large and similar changes inthe primary photochemical functioning of thylakoids from P.sativum and S. oleracea, which could be attributed mainly tothe cation species, Na^$; however, experiments using mannitolto produce osmotic stress indicated some small osmotically inducedchanges in photofunction of the thylakoids. Optimal primaryphotochemical activity of photosystem II, for both species,was observed with 200 mM NaCl. Cation-induced regulation ofexciton distribution appears to be facilitated by controllingthe degree of energy coupling between the light-harvesting chlorophylla/b complex and the two photosystems, I and II, and not by regulationof coupling between photosystems I and II.     

Callus Growth and Plantlet Regeneration in Taro, Colocasia esculenta var. esculenta (L) Schott (Araceae)

Explants of taro cultivars belonging to Colocasia esculentavar. esculenta have been nearly impossible to culture untilrecently. Here, we describe a method which induces callus formationfrom bud explants of Colocasia esculenta var. esculenta cv.Akalomamale, brings about shoot and root production, and leadsto plantlet regeneration. The medium used is half-strength Murashige-Skoog(HMS) solution containing 25 ml taro tuber extract (TE), 2 mg2, 4, 5-trichlorophenoxyacetic acid and 200 mg glutamine 1^–1.TE is an important requirement for bud explants and callus tissues.Root induction on callus-derived shoots (i.e. plantlet formation)occurs on HMS containing only 25 ml TE and 100 ml coconut water1^–1. Taro, Colocasia esculenta var. esculenta (L) Schott (Araceae), coconut water, micropropagation, plantlet regeneration, root formation, taro extract, tissue culture     

Chlorophyll-Protein Complexes Associated with Photosystem I Isolated from the Green Alga, Bryopsis maxima

Six chlorophyll (Chl)-protein complexes associated with photosystemI (CPla), and the PS I reaction center complex (CPl) were isolatedfrom the thylakoid membranes of the green alga, Bryopsis maxima,by SDS-polyacrylamide gel electrophoresis. CPla had four polypeptides(22, 24, 25, 26 kDa) in addition to the 67 kDa polypeptide ofCPl. These complexes may thus possibly be a combination of CPland antenna complexes for PS I. Six CPla showed almost the sameoptical properties, with absorption maxima at 650 and 677 nmand contained carotene and a small amount of xanthophylls. TheChl a/b ratios of these CPla were about 2, while that of CPlwas 14. CPla showed a fluorescence emission maximum at 695 nm;its excitation spectrum had peaks at 438, 470 and 540 nm, correspondingto the absorption maxima of Chl a, Chl b, xanthophylls, respectively.An antenna complex free of CPl has been detected in some plantsbut was not found in the present alga. ¹Present address: Department of Botany, The University of Adelaide,Adelaide, S.A. 5001, Australia (Received April 17, 1986; Accepted June 26, 1986)     

Division of Rhizobitoxine-Producing and Hydrogen-Uptake Positive Strains of Bradyrhizobium japonicum by nifDKE Sequence Divergence

Genomic digests from 25 strains of Bradyrhizobium japonicum,for which the phenotypes have been determined with respect toproduction of rhizobitoxine, hydrogen uptake (Hup) and compositionof extracellular polysaccharide (EPS), were hybridized withprobe DNAs of the nifDK and nifE genes of B. japonicum USDA110. The degree of the estimated base substitution in and aroundnifDKE clearly divided the strains of B. japonicum into twomarkedly divergent groups, which were designated as genotypeI and II. Moreover, a strict correlation was observed betweenthese genotypes, production of rhizobitoxine and EPS composition.The genotype I strains produced no rhizobitoxine and an EPScomposed of glucose, mannose, galactose, 4-O-methyl galactoseand galacturonic acid, whereas the genotype II strains producedrhizobitoxine and an EPS composed of rhamnose and 4-O-methylglucuronic acid. Hup⁺ strains were confined exclusively to thegenotype I. Hind III digests of genomic DNAs from the 25 strainswere hybridized with probe DNA of structural genes for the uptakehydrogenase from B. japonicum. In 23 wild-type strains, Hup⁺strains generated a 5.9-kb band that hybridized to the probeunder high-stringency conditions, while Hup^– strains didnot generate the band. These results suggest that the genotypesI and II are two highly divergent evolutionary lines that definea marked division of various phenotypes, such as productionof rhizobitoxine, EPS composition and hydrogen uptake. (Received July 10, 1989; Accepted November 4, 1989)     

An Endogenous Circadian Rhythm in the Rate of Carbon Dioxide Output of Bryophyllum: VI. ACTION SPECTRUM FOR THE INDUCTION OF PHASE SHIFTS BY VISIBLE RADIATION

A comparison has been made of the effectiveness of a 4-h exposureto equal quantum-flux densities of radiation in different zonesof the visible spectrum in shifting the phase of the endogenouscircadian rhythm of carbon dioxide metabolism in leaves of Bryoyihyllumfedtschenkoi. At an incident quantum-flux density of 8.9 ? 10^–13einsteins cm^–2 8^–1, only radiation between 600 and700 nm induced a phase shift, maximum activity being found at(560 nm. At a higher incident quantum-flux density of 1.9 ?10^–11 einsteins cm^–2 8^{– 1}, the peak of activitywas broader and extended from 560 to 700 nm. At both flux densitiesa sharp cut-off occurred at 700 nm. The action spectra are somewhat similar to the absorption spectrumof phytochrome except that they show no minor peak in the bluezone. No evidence has yet been obtained that the inductive effectof red light can be reversed by exposure to far-red radiationas in the case of a typical phytochrome-mediated response. Ultra-violet radiation at 237 nm had no effect upon the phaseof the rhythm.     

Kinetic analysis and comparison of uptake, distribution, and excretion of 48V-labeled compounds in rats

Setyawati, I. A., K. H. Thompson, V. G. Yuen, Y. Sun, M. Battell, D. M. Lyster, C. Vo, T. J. Ruth, S. Zeisler, J. H. McNeill, and C. Orvig. Kinetic analysis and comparison of uptake,distribution, and excretion of⁴⁸V-labeled compounds in rats.J. Appl. Physiol. 84(2): 569-575, 1998.Vanadium has been found to be orally active in lowering plasmaglucose levels; thus it provides a potential treatment for diabetesmellitus. Bis(maltolato)oxovanadium(IV) (BMOV) is a well-characterizedorganovanadium compound that has been shown in preliminarystudies to have a potentially useful absorption profile. Tissuedistributions of BMOV compared with those of vanadyl sulfate (VS) werestudied in Wistar rats by using⁴⁸V as a tracer. In this study,the compounds were administered in carrier-added forms by either oralgavage or intraperitoneal injection. Data analyzed by a compartmentalmodel, by using simulation, analysis, and modeling (i.e., SAAM II)software, showed a pattern of increased tissue uptake with use of⁴⁸V-BMOV compared with⁴⁸VS. The highest⁴⁸V concentrations at 24 h aftergavage were in bone, followed by kidney and liver. Most ingested⁴⁸V was eliminated unabsorbed byfecal excretion. On average, ⁴⁸Vconcentrations in bone, kidney, and liver 24 h after oraladministration of ⁴⁸V-BMOV weretwo to three times higher than those of⁴⁸VS, which is consistent with theincreased glucose-lowering potency of BMOV in acute glucose loweringcompared with VS.

     

Selective Inhibition of Type II Fatty Acid Synthetase by the Antibiotic Thiolactomycin

The antibiotic thiolactomycin inhibits the fatty acid synthesisfrom both [1-¹⁴C]- acetate and [2-¹⁴C]malonyl-CoA of spinachleaves, developing castor bean endosperms and avocado mesocarp.On the other hand, fatty acid synthetases of Brevibacteriumammoniagenes and Corynebacterium glutamicum are much less sensitiveto this antibiotic. As has been indicated that thiolactomycininhibits fatty acid synthetase of Escherichia coli but has littleeffect on the synthetases of yeast and rat liver [Hayashi etal. (1983) Biochem. Biophys. Res. Commun.. 115: 1108], thiolactomycinis suggested to be a selective inhibitor of type II fatty acidsynthetases. (Received November 10, 1983; Accepted December 17, 1983)     

The ecology of the Calanus ponticus population in the deeper layer of its concentration in the Black Sea

The layer of daytime concentration of Calanus ponticus (VC andVI C) performing daily vertical migrations and the layer of‘winter stock’ aggregation are confined to the depthof maximal gradient of the main pycnocline under an unusuallysharp oxycline. The concentration layer thickness ranges from2 to 20–30 m and the Calanus concentration in it is >250ind. m^–3, sometimes being 3500 ind. m^–3 and evenmore. The population in the concentration layer is divided intotwo ecological groups: I, feeding and migrating specimens ofcopepodite stages V and VI, their body lipid contents being25–60 µg min.^–1; and II, non-feeding and non-migratingspecimens of copepodite stage V, their body lipid contents being100–150 µg ind.^–1. The relationship with oxygenconcentration was studied in both ecogroups. The experimentsshow that specimens of ecogroup II can exit at an oxygen concentrationof 0.06 ml 1^–1, but at such concentration falling intoanabiosis. They die at 0.04 ml O₂ 1^–1. Estimates of respirationof the group II specimens (‘winter stock’) showthat lipids they store are sufficient for 7 months' survival.Depth of Calanus concentration is determined by water densityrather than concentration of oxygen.