An in situ Freeze-Fracture Study of Spiroplasma citri and the Corn Stunt Spiroplasma

Spiroplasma citri and the corn stunt spiroplasma in sieve cells of Catharanthus roseus were investigated using freeze -fracture electron microscopy. Only the particle studded fracture faces of the plasmalemma could be exposed and not the surfaces of both the extraplasmatic and the plasmatic leaflet. The extraplasmatic fracture face (EF) shows a lower particle density than the plasmatic fracture face (PF). On the PF particle free areas could be observed, which are helically arranged in helical filaments. We suppose that the cytoplasmic fibrils, probably involved in motility processes and in maintaining the helical shape, underly the particle free area only.     

The foraging ecology of sympatric marine fish in the genus Embiotoca (Embiotocidae): Importance of foraging behavior in prey size selection

Summary Two locally sympatric temperate marine reef fishes, Embiotoca jacksoni and E. lateralis (Embiotocidae), have high taxonomic similarity in diets. Subdivision of gammarid amphipods, their principal prey, was found. E. jacksoni took more tubicolous gammarid amphipods whereas E. lateralis consumed mostly free-living individuals. The species differed considerably with respect to between-individual variability in taxonomic compositions of their diets. Each E. jacksoni closely resembled other conspecifics in this regard while individual E. lateralis displayed very high between-fish variation. The principal interspecific difference in fish diets concerned the sizes of prey items taken. E. jacksoni ate small but very common items and the mean prey weight in their guts did not differ from random collections of available prey. E. lateralis concentrated on large, rarer sizes such that the average prey weight in their guts was much heavier than available or in the diet of E. jacksoni of the same length. Disparate foraging behaviors was a much better indicator of the relative differences in diets of these two fishes than was external fish morphology. E. jacksoni, which can winnow prey items from unwanted debris, was a relatively indiscriminant forager. E. lateralis did not winnow but actively searched for prey. This species was a much more discriminating forager, but displayed much variability in foraging behavior.     

Activity and quantity of ribulose bisphosphate carboxylase-and phosphoenolpyruvate carboxylase-protein in two Crassulacean acid metabolism plants in relation to leaf age,nitrogen nutrition,and point in time during a day/night cycle

Activity of ribulose 1,5-bisphosphate (RuBP) carboxylase in leaf extracts of the constitutive Crassulacean acid metabolism (CAM) plant Kalanchoe pinnata (Lam.) Pers. decreased with increasing leaf age, whereas the activity of phosphoenolpyruvate (PEP) carboxylase increased. Changes in enzyme activities were associated with changes in the amount of enzyme proteins as determined by immunochemical analysis, sucrose density gradient centrifugation, and SDS gel electrophoresis of leaf extracts. Young developing leaves of plants which received high amounts of NO ₃ ^- during growth contained about 30% of the total soluble protein in the form of RuBP carboxylase; this value declined to about 17% in mature leaves. The level of PEP carboxylase in young leaves of plants at high NO ₃ ^- was an estimated 1% of the total soluble protein and increased to approximately 10% in mature leaves, which showed maximum capacity for dark CO₂ fixation. The growth of plants at low levels of NO ₃ ^- decreased the content of soluble protein per unit leaf area as well as the extractable activity and the percentage contribution of both RUBP carboxylase and PEP carboxylase to total soluble leaf protein. There was no definite change in the ratio of RuBP carboxylase to PEP carboxylase activity with a varying supply of NO ₃ ^- during growth. It has been suggested (e.g., Planta 144, 143–151, 1978) that a rhythmic pattern of synthesis and degradation of PEP carboxylase protein is involved in the regulation of -carboxylation during a day/night cycle in CAM. No such changes in the quantity of PEP carboxylase protein were observed in the leaves of Kalanchoe pinnata (Lam.) Pers. or in the leaves of the inducible CAM plant Mesembryanthemum crystallinum L.Abbreviations CAM Crassulacean acid metabolism - RuBP ribulose 1,5-bisphosphate - PEP phosphoenolpyruvate - G-6-P glucose-6-phosphate     

Biochemical studies on histones of the central nervous system. I. Characterization and partial identification of the label of histones from rat brain following intraventricular administration of 1-[14C]-acetate

Rat brain histones were acetylated in vivo by intraventricular injection of [14C]-acetate. More than 90% of the label is the result of a true acetylation. Enzymatic proteolysis of the labelled histone fraction and subsequent chromatographic investigation of the digestion products showed about 60% of the recovered radioactive material to be epsilon-acetyl lysine, whereas 22% of the radioactivity was found in an unidentified spot.     

Relationships among raffinose plasmids determined by the immunochemical cross-reaction of their alpha-galactosidases.

Plasmid-encoded alpha-galactosidase served as a marker enzyme for the recognition and comparison of raffinose (Raf) plasmids present in strains of Escherichia coli. Immunochemical relationships were established among Raf plasmids of 39 independent isolates from man and domestic animals (from three continents) by using antiserum against alpha-galactosidase. Immunodiffusion revealed three serological subclasses of alpha-galactosidase, which are correlated with the biological and geographical origin of the host strains. It is concluded that the raf determinants of all Raf plasmids tested have evolved from a common ancestor.     

The enzymatic system thiosulfate: Cytochrome c oxidoreductase from photolithoautotrophically grown Rhodopseudomonas palustris

Rhodopseudomonas palustris cells, characterized by a lamellar type intracytoplasmic chromatophore membrane system after phototrophic growth, yielded a crude supernatant cell-free fraction (S-144) after ultracentrifugation which retained the contents of both the cell compartments. After thiosulfate-dependent growth, a protein system was isolated from S-144 which catalyzed the thiosulfate-linked reduction of an endogenous c-type cytochrome. — The colorless oxidoreductase protein, after purification to homogeneity, revealed a molecular weight of 93,000 and, after SDS treatment, a particle weight of 48,000. It was focused at an average pI of 5.45. Apparent K _m values for several substrates were in the M range. The electron acceptor for thiosulfate oxidation was found to be a cytochrome c from S-144. The homogeneous acceptor protein, at liquid nitrogen temperature, exhibited absorption maxima at 549.0, 518.5 and 418.0 nm, and shoulders at 525.5, 512.0 and 508.0 nm. Its molecular weight was found to be 17,000 (gel filtration) and 16,000 (SDS gel electrophoresis). It was characterized by a pI of 10.0. Its midpoint redox potential of E _m,7.0=+228 mV was determined by redox titrations and the value of +205 mV by spectrophotometric calculations.Abbreviations BSA bovine serum albumin - HiPIP high potential nonheme iron protein - IEF isoclectric focusing - SDS dodecylsulfate, sodium salt - Temed N,N,N,N-tetramethylethylenediamine     

Über die Pleomorphie von MLO in Catharanthus roseus (Vinca rosea)

About the pleomorphism of MLO in Catharanthus roseus (Vinca rosea) MLO of the flower greening (virescence)-type of Primula in the phloem of Catharanthus roseus (Vinca rosea) were fixed in two different ways. After prefixation with OsO4 they showed a diminished pleomorphic morphology, most MLO were spherical. With the fixation of KARNOVSKY (1965) and subsequent treatments with OsO4 and uranyl acetate, however, an extremely high pleomorphism was observed. Such pleomorphic MLO in single thin sections are probably the expression of a threedimensional network-like connection. The concentration of MLO in the sieve elements seems to influence the pleomorphism only insignificantly.     

A new enkephalin analogue: trans-4-hydroxycinnamoyl-glycyl-glycyl-phenylalanyl-leucine. Synthesis and biological properties

A new analogue of the leucine-enkephalin in which the N-terminal tyrosine has been replaced by trans-4-hydroxycinnamic acid, has been synthetized by liquid-phase coupling methods. The central cardiovascular effects of this analogue were investigated and the results discussed.     

A novel non-heme iron-containing dioxygenase. Chloridazon-catechol dioxygenase from Phenylobacterium immobilis DSM 1986

Previously we purified an enzyme from Phenylobacterium immobilis DSM 1986, which cleaves the catechol derivative of the herbicide Chloridazon [5-amino-4-chloro-2-phenyl-3 (2H)-pyridazinone] in the meta position. The enzyme, which could be crystallized, proved in Ouchterlony double-diffusion tests to consist of a single protein species. No cross-reaction was observed with other meta-cleaving enzymes. Its light absorption spectrum showed a maximum at 279 nm (epsilon = 310 mM -1 cm -1), shoulders at 289 nm and 275 nm and a very weak band at around 430 nm (epsilon = 1.14 mM -1 cm -1). The amino acid analysis showed a slight excess of acidic amino acids, in agreement with the pl of 4.5. Surprisingly the enzyme per se is completely inactive, although it contains one non-dialysable iron atom per submit. It has to be activated by preincubation with ferrous ions or ascorbate. The enzyme activated this way is autoxidizable and returns to its non-activated state in the presence of oxygen. During the reaction with the substrate, this inactivation seems to be enhanced about 100 times. Since this kind of activation and inactivation is not observed in other meta-cleaving enzymes, this enzyme seems to represent a new type of a non-heme iron dioxygenase. We tentatively propose the name Chloridazon-catechol dioxygenase for this enzyme.