The existence of glutathione and cysteine disulfide-linked to erythrocyte carbonic anhydrase from tiger shark

In this study it is shown that the higher molecular weight previously reported for tiger shark carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1) compared to other carbonic anhydrases is decreased to a normal value around 30 000 after disulfide reduction of the enzyme. This difference in molecular weight is at least partly due to the existence of disulfide-linked glutathione and cysteine residues. Approx. 3 mol glutathione and a similar amount of cysteine are shown to be bound per mol enzyme. The presence of these factors also has effects on the enzyme activity.     

Alterations in Pigment Content in Leaves of Pisum sativum After Exposure to Supplementary UV-B

Pea plants were either illuminated with visible light supplementedwith ultraviolet-B (UV-B) radiation for five days, or transferredback to control light after short exposures (hours) to UV-B.Spectra of NaOH-extracted pigments from UV-B-exposed plantsshowed a decrease in absorption in the visible region and anincrease in the UV region: the former a consequence of the lossof chlorophyll, the latter probably due to induced synthesisof protective pigments. The decrease in chlorophyll absorptionwas an earlier event than the increase in UV absorption. Inextracts from plants which had recovered, the increase in UVabsorption was greater than in leaves subjected to three daysof UV-B. This stresses the importance of recovery from UV-Bfor extensive synthesis of protective pigments. Analysis oftetrapyrrolic pigments showed that UV-B treatment caused noallomerization of chlorophylls. Formation of chlorophyllidesa and b was greatly enhanced during the degradation of chlorophylls;however, the concentrations of chlorophyllides were three ordersof magnitude lower than those of the chlorophylls and did notincrease greatly as chlorophyll degradation progressed. No protoporphyrinIX, uro- or copro-porphyrins III were detected, which suggeststhat early steps in chlorophyll synthesis are not affected byUV-B light. (Received May 15, 1992; Accepted August 6, 1992)     

Floristic notes from the mountains of Northern Greece Materials for the Mountain Flora of Greece, 7

The authors present an annotated list of rare or otherwise interesting vascular plants collected in the mountains of northern Greece by themselves in 1979 and by Strid and Georgiadou in 1977. The following are apparently new to Greece: Thesium linophyllon L. ssp. montanum (Ehrh. ex. Hoffm.) Čelak., Moehringia pendulo (Waldst. & Kit.) Fenzl, Gypsophila glomerata Pallas ex. Bieb., Dianthus peiraeus Waldst. & Kit. ssp. noeanus (Boiss.) Tutin, Dianthus superbus L., Ranunculus fon–tanus C. Presl, Thlaspi arvense L., Potentilla apennina Ten. ssp. stoianovii Urum. & Jav., Trifolium badium Schreber, Rhamnus pumila Turra, Viola palustris L., Athamanta albanica Alston & Sandwith, Peucedanum oligophyllum ssp. aequiradium (Vandas) Tutin, Vaccinium gaultherioides Bigelow, Galeopsis speciosa Miller, G. bifida Boenn., Melampyrum sylvaticum L., Odontites lutea (L.) Clairv., Sambucus racemosa L., Symphyandra wanneri (Rochel) Heuffel, Galinsoga parviflora Cav., Achillea distans Waldst. & Kit. ex Willd., Centaurea grbavacensis (Rohlena) Stoj. & Acht., C. indurata Janka, Lactuca aurea (Schultz Bip. ex PanČić) Stebbins, Festuca gigantea (L.) Vill., F. pirinica Horvat ex Markgr.–Dannenb., Sparganium minimum (Hartm.) Fries, and Rhynchospora alba (L.) Vahl.     

The role of NADPH oxidase and MAP kinase phosphatase in UV-B-dependent gene expression in Arabidopsis

Plant responses to supplementary UV-B irradiation have been reported to include formation of reactive oxygen species (ROS), hydrogen peroxide, in particular, and regulation by mitogen-activated protein kinase (MAPK) cascades which in turn are fine-tuned by MAPK phosphatases (MKPs). Here we present direct genetic evidence for the involvement of plasma membrane NADPH oxidase, a source of superoxide and hydrogen peroxide in the apoplasts, in UV-B signalling in Arabidopsis thaliana, by analysis of gene expression of the UV-B molecular markers in NADPH oxidase (atrbohD, F and DF) and MAP kinase phosphatase 1 (MKP1) knockout mutants (mkp1). Whereas the NADPH oxidase mutants were affected in UV-B-dependent CHS, PYROA and MEB5.2 gene expression, the mkp1 mutant was affected in the general expression pattern of the pathogenesis-related (PR) and PDF1.2 genes. The results indicate involvement of MKP1 in repressive action on gene expression of more general stress response pathways, similar to those activated by pathogen attack, while NADPH oxidase is involved in quantitative (rather than absolute) regulation of more UV-B-specific genes. The expressions of the molecular markers in the knockout mutant mkp1 and in its complemented lines (lines 6 and 10) were similar, as opposed to the responses of the corresponding wild-type Wassilewskija-4 (Ws-4). Lines 6 and 10 showed much higher MKP1 mRNA than Ws-4 but did not complement the mutant. This suggests a complex dependency of the MAPK phosporylation level of the PR and PDF1.2 genes. Both NADPH oxidase mutants and the mkp1 mutant phenotypically responded to UV-B by growth retardation.     

Amino acid content of leguminous proteins as affected by genetic and nutritional factors III

Summary Pea proteins have been extracted from ground peas, and albumin, vicilin and legumin have been isolated. The electrophoretic homogenity of the proteins was tested by means of free electrophoresis and the amino acid composition was determined by column chromatography.     

A newAstragalus (Fabaceae) from southern Peloponnisos

Astragalus maniaticus (Fabaceae), a new species endemic to the Mani Peninsula in Peloponnisos, southern Greece, is described and illustrated. Its closest affinities are still uncertain but within Greece, it lacks close allies.Dedicated to emer. Univ.-Prof. DrFriedrich Ehrendorfer on the occasion of his 70th birthday