Carbonic anhydrase activity in acetate grown Methanosarcina barkeri

Cell extracts (27000xg supernatant) of acetate grown Methanosarcina barkeri were found to have carbonic anhydrase activity (0.41 U/mg protein), which was lost upon heating or incubation with proteinase K. The activity was inhibited by Diamox (apparent K _i=0.5 mM), by azide (apparent K _i=1 mM), and by cyanide (apparent K _i=0.02 mM). These and other properties indicate that the archaebacterium contains the enzyme carbonic anhydrase (EC 4.2.1.1). Evidence is presented that the protein is probably located in the cytoplasm. Methanol or H₂/CO₂ grown cells of M. barkeri showed no or only very little carbonic anhydrase activity. After transfer of these cells to acetate medium the activity was induced suggesting a function of this enzyme in acetate fermentation to CO₂ and CH₄. Interestingly, Desulfobacter postgatei and Desulfotomaculum acetoxidans, which oxidize acetate to 2 CO₂ with sulfate as electron acceptor, were also found to exhibit carbonic anhydrase activity (0.2 U/mg protein).     

Über die Kalkausscheidungen beiMonophyllaea horsfieldii (Gesneriaceae)

The lower surface of the leaf (macrocotyledon) ofM. horsfieldii is heavily calcified. SEM investigations reveal that the cristalline depositions of CaCO₃ (mainly needles, but also clump-like structures) are excreted by the head cells of two-cellular trichomhydathodes. First, a cap-like structure is formed. As the excretion continues, the cap takes on the shape of a hat with wide brim. Thus, the dense layer of CaCO₃ depositions is composed of hat-like structures whose brims at least partially touch. There is no evidence for the excretion of CaCO₃ by cells other than trichomhydathodes.

     

Croisements expérimentaux entre «Races Chromosomiques» dans le genreErysimum

Artificial hybrids between dysploid chromosome races or microspecies ofErysimum sylvestre group are produced. From the meiotic behaviour it is inferred thatE. montosicolum (n = 14) is an autopolyploid ofE. australe (n = 7) and that the Italian race with n = 11 is probably derived from an unknown tetraploid.

     

Interconversion of F430 derivatives of methanogenic bacteria

F₄₃₀ is the prosthetic group of the methylcoenzyme M reductase of methanogenic bacteria. The compound isolated from Methanosarcina barkeri appears to be identical to the one obtained from the only distinctly related Methanobacterium thermoautotrophicum. F₄₃₀ is thermolabile and in the presence of acetonitrile or C10 _in4 ^sup- two epimerization products are obtained upon heating; in the absence of these compounds F₄₃₀ is oxidized to 12, 13-didehydro-F₄₃₀. The latter is stereoselectively reduced under H₂ atmosphere to F₄₃₀ by cell-free extracts of M. barkeri or M. thermoautotrophicum. H₂ may be replaced by the reduced methanogenic electron carrier coenzyme F₄₂₀.Abbreviations CH₃S-CoM methylcoenzyme M, 2-methylthioethanesulfonic acid - HS-CoM coenzyme M, 2-mercaptoethanesulfonic acid - F₄₃₀ Ni(II) tetrahydro-(12, 13)-corphin with a uroporphinoid (III) ligand skeleton - 13-epi-F₄₃₀ and 12,13-di-epi-F₄₃₀ the 12, 13- and 12, 13-derivatives of F₄₃₀ - 12, 13-didehydro-F₄₃₀ F₄₃₀ oxidized at C-12 and C-13 - coenzyme F₄₂₀ 7,8-didemethyl-8-hydroxy-5-deazaflavin derivative - coenzyme F₄₂₀H₂ reduced coenzyme F₄₂₀ - MV⁺ methylviologen semiquinone - HPLC high-performance liquid chromatography     

Cytochromes in Thiobacillus tepidarius and the respiratory chain involved in the oxidation of thiosulphate and tetrathionate

Thiobacillus tepidarius was shown to contain cytochrome(s) c with absorption maxima at 421, 522 and 552 nm in room temperature reduced minus oxidized difference spectra, present at 1.1–1.2 nmol per mg dry wt and present in both membrane and soluble fractions of the cell. The membrane-bound cytochrome c (1.75 nmol per mg membrane protein) had a midpoint potential (E_m, pH 7.0) of 337 mV, while the soluble fractions appeared to contain cytochrome(s) c with E_m (pH 7.0) values of about 270 and 360 mV. The organism also contained three distinct membrane-bound b-type cytochromes (totalling 0.33 nmol per mg membrane protein), each with absorption maxima in reduced minus oxidized difference spectra at about 428, 532 and 561 nm. The E_m (pH 7.0) values for the three cytochromes b were 8 mV (47.8% of total), 182 mV (13.7%) and 322 mV (38.5%). No a- or d-type cytochromes were detectable spectrophotometrically in the intact organism or its membrane and soluble fractions. Evidence is presented for both CO-binding and CO-unreactive cytochromes b or o, and CO-binding cytochrome(s) c. From redox effects observed with CO it is proposed that a cytochrome c donates electrons to a cytochrome b, and that a high potential cytochrome b or o may be acting as the terminal oxidase in substrate oxidation. This may be the 445 nm pigment, a photodissociable CO-binding membrane haemoprotein. Substrate oxidation was relatively insensitive to CO-inhibition, but strongly inhibited by cyanide and azide. Thiosulphate oxidation couples directly to cytochrome c reduction, but tetrathionate oxidation is linked (probably via ubiquinone Q-8) to reduction of a cytochrome b of lower potential than the cytochrome c. The nature of possible electron transport pathways in Thiobacillus tepidarius is discussed. One speculative sequence is: c^– b₈ b₁₈₂ c₂₇₀ c₃₃₇ b₃₂₂/c₃₆₀ O₂ Abbreviations E_m midpoint electrode potential - E _inf0 ^sup pH 7, standard electrode potential at pH 7.0 - Q-8 coenzyme Q-8 (ubiquinone-40)     

Beiträge zur Entwicklungsgeschichte und Taxonomie einigerAchnanthes-Arten,SubgenusMicroneis (Bacillariophyceae)

The submicroscopic structure of the seed surface was studied in 16 species of the genusJacaranda and some species of the generaDigomphia, Tecoma andTabebuia (Bignoniaceae). Epicuticular excrescences (star-scales) are characteristic forJacaranda and seem to be ± restricted to this genus. WithinJacaranda onlyJ. macrocarpa has no star-scales but torus-like cuticular marks as the other genera.J. macrocarpa therefore appears as a link between the bulk ofJacaranda and the otherBignoniaceae.

     

Levures des eaux saumatres de Lagrange-Fouquet

The briny waters of Lagrange-Fouquet contain a wide variety of yeasts. The more common ones are Cryptococcus laurentii, Cryptococcus albidus, Sporobolomyces pararoseus and Sporobolomyces roseus.These yeasts stem from the phyllosphere of the surrounding vegetation, and constitute a population which is characteristic of the natural zones.

     

Saccharomyces cerevisiae and Neurospora crassa contain heavy metal sequestering phytochelatin

In fungi, cellular resistance to heavy metal cytotoxicity is mediated either by binding of metal ions to proteins of the metallothionein type or by chelation to phytochelatin-peptides of the general formula (-Glu-Cys)_n-Gly. Hitherto, only one fungus, Candida glabrata has been shown to contain both metal inactivating systems. Here we show by unambiguous FAB-MS analysis that both a metallothionein-free mutant of Saccharomyces cerevisiae as well as a wildtype strain synthesize phytochelatin (PC₂) upon exposure to 250 M Cd²⁺ ions. The presence of Zn and/or Cu ions in the nutrient broth also induces PC₂ synthesis in this organism. By ¹⁰⁹Cd exchange and subsequent monobromobimane fluorescence HPLC, it could be shown that the presence of Cd²⁺ in the growth medium also induces phytochelatin synthesis in Neurospora crassa, which contains metallothioneins.     

Growth-inhibiting and larvicidal effects of Melia volkensii extracts on Aedes aegypti larvae

Extracts from dry Melia volkensii fruits contain growth-inhibiting activity against larvae of the mosquito Aedes aegypti. The active fraction may be eluted from silica gel using hexane-ethyl acetate (1:1, v:v). At a concentration of even 2 g/ml in water, this fraction prolongs larval instars. Mortality in treated larvae is high, especially during the moulting and melanisation processes. The LC₅₀ for larval mortality is 50 g/ml in 48 h. The active compound of this fraction is not identical with azadirachtin. It may be more potent as an insect growth-inhibitor and more lethal to Aedes larvae than azadirachtin.

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Zusammenfassung Samen von Melia volkensii wurden mit 80-proz. wäßrigem Methanol extrahiert und daraus das in reinem Methanol lösliche Material gewonnen. Dieses wurde dann mit Aceton erschöpfend digeriert. Der in Methanol und Aceton lösliche Anteil wurde über Kieselgel fraktioniert und mit Larven von Aedes aegypti auf wachstumshemmende bzw. toxische Wirkung getestet. Das von einem Hexan-Essig-ester (1:1, v:v)-Gemisch eluierte Material hat noch in einer Konzentration von 2 g/ml wachstumshemmende und mit einer LC₅₀ von 50 g/ml innerhalb von 48 Stunden larvicide Wirkung. Sein biologisch aktiver Bestandteil ist nicht mit einem der Azadirachtine aus Azadirachta indica identisch. Im Vergleich mit Azadirachtin ist er für die Larven von A. aegypti ein wesentlich potenterer Wachstumshemmer bei gleichfalls höherer Letalität.

     

Surface charge of protoplasts and their significance in cell-cell interaction

-potential of mesophyll protoplasts of tobacco (Nicotiana tabacum L.), petunia (Petunia hybrida Hort.), turnip (Brassica rapa L.) and cowpea (Vigna unguiculata L. Walpers) was determined by use of a cell electrophoresis apparatus. All protoplasts examined showed a constant negative value of-10 to-35 mV. The addition of CaCl₂ nullified the -potential of tobacco protoplasts. This phenomenon is explained by DLVO theory of colloid science, which has been successfully applied to animal cells. Furthermore, positively charged polymers reversed the -potential to positive values. Treatment of the protoplast surface with several enzymes was carried out to characterize the chemical nature of suface charges. The removal of surface charges was most conspicuous by the treatment of acid phosphatase (EC 3.1.3.2), but did not occur upon treatment with -neuraminidase (EC 3.2.1.18) or Streptomyces griseus pronase. Thus a major part of the surface charge originates from the phosphate groups at the cell membrane. The significance of these studies for the properties of the protoplast surface in cell adhesion is discussed.     

Wuchsform,Infloreszenz- und Blütenmorphologie vonEpithema (Gesneriaceae)

The shoot organization and inflorescence structure ofEpithema is analyzed. On the main axis micro- and macrocotyledon (the latter falling off early) are followed by a ± long epicotyl, then a large, solitary leaf (B₃) and above this a dimerous leaf whorl (B₄, B₅). The last internode of the main axis is the basic internode of the main florescence (Troll). Peculiarly enough, the latter includes only one partial florescence which is embraced by its subtending bract (B₆) and represents a capitulum-like, congenital, pair-flowered cincinnus. Paracladia arise from the axils of B₃ to B₅ (sometimes also from the macrocotyledon); they are either reduced to their co-florescence (with the same structure as the main florescence), or carry further shoots resp. co-florescences from the axils of a dimerous leaf whorl.—Epithema can be interpreted as anisophyllous.—From flower morphology and ontogenesis a number of new differential characters are revealed. Together with shoot and inflorescence characters their systematic and possible functional significance is discussed.

Frau Univ.-Prof. Dr. E.Tschermak-Woess zum 60. Geburtstag gewidmet.     

Evidence for carrier-mediated,energy-dependent uptake of urea in some bacteria

Evidence for the existence of an energy-dependent urea permease was found for Alcaligenes eutrophus H16 and Klebsiella pneumoniae M5a1 by studying uptake of ¹⁴C-urea. Since intracellular urea was metabolized immediately, uptake did not result in formation of an urea pool. Evidence is based on observations that the in vivo urea uptake and in vitro urease activity differ significantly with respect to kinetic parameters, temperature optimum, pH optimum, response towards inhibitors and regulation. The K _m for urea uptake was 15–20 times lower (38 M and 13 M urea for A. eutrophus and K. pneumoniae, respectively) than the K _m of urease for urea (650 M and 280 M urea), the activity optimum for A. eutrophus was at pH 6.0 and 35°C for the uptake and pH 9.0 and 65°C for urease. Uptake but not urease activity in both organisms strongly decreased upon addition of inhibitors of energy metabolism, while in K. pneumoniae, potent inhibitors of urease (thiourea and hydroxyurea) did not affect the uptake process. Significant differences in the uptake rates were observed during growth with different nitrogen sources (ammonia, nitrate, urea) or in the absence of a nitrogen source; this suggested that a carrier is involved which is subject to nitrogen control. Some evidence for the presence of an energy-dependent uptake of urea was also obtained in Pseudomonas aeruginosa DSM 50071 and Providencia rettgeri DSM 1131, but not in Proteus vulgaris DSM 30118 and Bacillus pasteurii DSM 33.Non-standard abbreviations CCCP Carbonylcyanide-m-chlorphenylhydrazone - DCCD dicyclohexylcarbodiimide - DNP 2,4-dinitrophenole     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen:Ranunculaceae,Hamamelidaceae, Platanaceae undFagaceae

Transfer of fresh pollen either by wind or by insects is strongly related to the degree of its stickiness. The sticky substances involved should be understood as pollenkitt. Ultrastructural investigations indicate that the sticky pollen of entomophilous angiosperms (in this publicationHamamelis vernalis andH. virginiana, Corylopsis platypetala) results from the deposition of usually electron-dense, homogeneous pollenkitt mainly on the outside layer of the exine. In contrast, the pollen of anemophilous angiosperms (in this publicationParrotia persica, Platanus orientalis, Thalictrum flavum andQuercus robur), but also of some entomophilous angiosperms with special pollination ecology (e.g.Aquilegia vulgaris) is rather dry and powdery. In these cases the pollenkitt often is electron-transparent and inhomogeneous and is mainly removed into the cavities of the exine. Ultrastructure and deposition of pollen and pollenkitt in ambophilous angiosperms (in this publicationThalictrum minus, Castanea sativa) are ± intermediate.

     

Ultrastruktur und Entwicklungsgeschichte des Pollenkitts vonEuphorbia cyparissias,E. palustris undMercurialis perennis (Euphorbiaceae)

Development, fine structure and distribution of pollenkitt is investigated inEuphorbia cyparissias, E. palustris, andMercurialis perennis. The predominantly anemophilousM. perennis produces a great amount of strictly homogeneous pollenkitt, which is deposited in the exine caves. In contrast to this and to all other angiosperms so far investigated, bothEuphorbia species produce large quantities of an extremely inhomogeneous and particular pollenkitt. Its ultrastructure is quite different, both during its development and after its deposition on the exine surface: Lipid particles with different electron density and size are wrapped in a strictly homogeneous electron transparent matrix. This can be considered as new and additional proof for the secondary entomophily ofEuphorbia.

     

Epidermale Organe am Kopf von Morulius chrysophakedion (Cyprinidae,Ostariophysi, Pisces)

Zusammenfassung Im Kopfbereich von Morulius chrysophakedion liegen epidermale Organe in Gruppen beisammen. Im Gegensatz zu den oberflächlichen Perlorganen anderer Cyprinidae handelt es sich hierbei um voluminöse Einsenkungen der Epidermis in das darunter gelegene Bindegewebe, von dem aus gefäßführende Papillen in das Organinnere hineinziehen. Elektronenmikroskopische und histochemische Befunde sprechen für eine relativ hohe Stoffwechselaktivität der das Organ aufbauenden Polsterzellen, als deren Ergebnis eine Art Verhornung an der Organspitze vorliegt. Hinweise auf eine Funktion der epidermalen Organe von Morulius als Sinnesorgane wurden nicht gefunden; sie müssen daher von den Fahrenholzschen Organen der Dipnoi und Brachiopterygii unterschieden werden.

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Epidermal organs on the head of Morulius chrysophakedion (Cyprinidae, Ostariophysi, Pisces)Histochemical and electron microscopical study of the so called flask-shaped organs of Labeo

Summary There are groups of epidermal organs in the head region of Morulius chrysophakedion. In contrast to the superficial perlorgans of some other Cyprinidae these organs are formed by an infolding of epidermis into the connective tissue beneath. From this tissue vessels reach into the interior of the organ. Electron microscopical and histochemical data give evidence of a relatively high metabolic activity in the Polsterzellen from which the organ is built up. These cells give rise to a keratinized area at the top of the organ. There is no evidence that the epidermal organ has the function of a sense organ as in the organs of Fahrenholz in Dipnoi and Brachiopterygii.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Asperula visianii,nova spec., undA. staliana (Rubiaceae), Endemiten der Inseln Mitteldalmatiens

Asperula visianii Korica is described as a new stenoendemic species from the small Central Dalmatian island of Svetac (near Vis). It differs in several morphological features (which remain constant in cultivation) and in its ecology from the closely relatedA. staliana Vis., endemic on the nearby island of Bievo.

     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Inheritance and linkage relationships of glutamate oxaloacetate transaminase isoenzymes in apple

Summary Four zones of enzymatic activity for glutamate oxaloacetate transaminase (GOT) were found in apple tissue. A dimeric gene, GOT-1, determining the fastest migrating zone, was identified. Six alleles were found, including a near null allelle which produced detectable heterodimeric bands but not homodimeric bands. A marked deficit or absence of certain geno-types in all backcrosses and in some crosses between unrelated varieties was attributed to the close linkage (r=0.02±0.005) of GOT-1 with the incompatibility S locus. GOT-1 was also closely linked with the isocitrate dehydrogenase locus IDH-1 (0.03±0.01). Proposed incompatibility genotypes for four cultivars, and the linked GOT-1 alleles are Cox: S ₁ b/S ₂ d, Idared: S ₃ a/S ₄ c, Fiesta: S ₃ a/S ₂ d and Kent: S ₃ a/S ₁ b.The results reported in this paper are part of a PhD Thesis by the first author     

Ajuga piskoi (Labiatae) — neu für Jugoslawien

Ajuga piskoi Degen & Baldacci, hitherto known only from the type locality in Albania, has been found in Southern Yugoslavia. Two figures are presented. It is a rare and threatened plant species.

     

Nitrite reduction in Rhizobium “hedysari” strain HCNT 1

Rhizobium hedysari strain HCNT 1 rapidly reduced nitrite to N₂O, only slowly reduced nitrate to nitrite and did not exhibit nitrous oxide reductase activity. Nitrite reduction in this rhizobium strain may be a detoxification mechanism for conversion of nitrite, which inhibits O₂ uptake, to non-toxic N₂O. Concentrations of nitrite as small as 3 M diminished O₂ uptake in whole cells. The bacterium did not couple energy conservation with nitrate or nitrite reduction. Cells neither grew anaerobically at the expense of these nitrogen oxides nor translocated protons during reduction of nitrite. Induction of nitrite reductase activity was not a response to the presence of nitrate or nitrite, but occurred instead when the O₂ concentration in culture atmospheres fell to <16.5% of air saturation. Sensitivity of cytochrome o, which is synthesized only in cells grown under O₂-limited conditions, may account for the toxicity of nitrite in strain HCNT 1.