Microspectrophotometric and scanning microphotometric studies of carp (Cyprinus carpio L.) erythrocytes

Carp (Cyprinus carpio) hemoglobin readily autoxidizes in blood smears. Quantification of Soret-band absorbance in individual erythrocytes by means of scanning cytophotometry therefore requires more elaborate methods of preparation of blood samples. Of the fixatives that have been tested, suspension of whole blood in isotonic salt solutions containing glutaraldehyde was most suitable. Glutaraldehyde-fixed red blood cells are totally resistant to hemolysis. In the course of fixation, hemoglobin is transformed to methemoglobin. Spectrophotometry indicated extensive similarities between glutaraldehyde-fixed carp methemoglobin and human methemoglobin. In aqueous solutions, the intensity of the Soret-peak was pH-dependent. The allosteric modifier organic polyphosphate caused an R----T transition, resulting in increased molar extinctions. Dried preparations showed Soret-spectra that were not influenced from either pH or organic polyphosphate concentration of the aqueous suspensions in which the erythrocytes had been stored. The same was true for slide preparations of cyanomethemoglobin, easily derived from methemoglobin on addition of potassium cyanide. In the absence of oxygen fresh blood cells from carp slowly transform their hemoglobin into deoxyhemoglobin. Spectra of the intermediate stages of deoxygenation, Hb4(O2)3, Hb4(O2)2 and Hb4(O2), as well as mixtures of these intermediates, could be monitored.     

The spectrum of CFTR mutations in south-west German cystic fibrosis patients

The cystic fibrosis transmembrane conductance regulator (CFTR) gene of 110 cystic fibrosis (CF) patients from the south-west of Germany was screened for 12 different mutations. This analysis resulted in an identification of 79% of all CF mutations and a complete genotype in 66% of the families. The most common mutation found was F508 (67%). Another 5 mutations accounted for a further 12.5% (4% G542X; 3% R553X; 3% N1303K; 2% 1717-1 GA; 0.5% G551D) whereas 6 mutations (R117H, A455E, I507, S549I, S549N, and R1162X) were not found. Fifty-four (49%) patients were AF508 homozygotes and 18 (16.5%) were compound heterozygotes for F508 and one of the rarer mutations. These frequencies differ slightly from those found in the north of Germany and considerably from those reported from the south of Europe, which seems to be consistent with a north to south decline of the relative abundance of F508. Two patients, age 6 and 25 years, were compound heterozygotes for G542X and N1303K. The clinical features of the 6 year old were characterised by severe gastrointestinal and as yet only mild pulmonary complications whereas the 25 year old manifested severe pulmonary and gastrointestinal symptoms indicating that the N1303K mutation of the C-terminal CFTR nucleotide binding fold significantly impairs protein function in both the pancreas and the lungs.     

Xylem and Phloem Import of Na+, K+, Rb+, Cs+ and Sb(SO4)2- in Tomato Fruits: Differential Contributions from Stem and Leaf

Wolterbeek, H. Th. and De Bruin, M. 1986. Xylem and phloem importof Na⁺, K⁺ , Rb⁺, Cs⁺ and in tomato fruits: differential contributions from stem and leaf.—J.exp. Bot. 37: 928–939. The transport of Na⁺, K⁺, Rb⁺, Cs⁺ and into developing fruits of tomato (an inbred lineof Lycopersicon esculentum Mill. cv. Tiny Tim) was measured.Element solutions were introduced into the transpiration streamthrough the cut stem bases of plant parts consisting of a stempart with single green fruit, both with and without attachedfully expanded leaf. Measurements were carried out of the accumulationin the fruit of the gamma-ray emitting radiotracers ²⁴Na⁺, ⁴²K⁺,⁸⁶Rb⁺, ¹³⁴Cs⁺ and The transport into the fruit was expressed by a single parameter taking intoaccount volume flows varying with time and experiments. Xylemto phloem transfer in the stem as a source of fruit elementsupply was shown to be inversely related with the velocity offlow of the stem xylem. The results also indicated that thetransfer system in the stem was more rapidly equilibrated thanit was in the leaf. Stem loading of the phloem is suggested as a possible mechanismregulating the solute influx in fruits under varying flow velocitiesof the stem xylem, while fruit influx of phloem solutes, whichwere loaded in the leaf, may play a major role in influx regulationunder conditions of varying solute concentrations. Key words: Alkali ions, tomato fruits, stem and leaf phloem loading     

Changes in Abscisic Acid Content in Axis and Cotyledons of Developing Phaseolus vulgaris Embryos and their Physiological Consequences

Prevost, I. and Le Page–Degivry, M. Th. 1985. Changesin absicisic acid content in axis and cotyledons of developingPhaseolus vulgaris embryos and their physiological consequences.—J.exp. Bot. 36: 1900–1905.Changes in abscisic acid (ABA)content with time were measured in embryonic axes and in cotyledonsof Phaseolus vulgaris embryos using a radio–immunoassay.During embryogenesis, a similar pattern was observed in bothtissues: ABA increased to a maximum 29 d after an thesis, followedby a decrease as the seed matured. The level of ABA in the cotyledonswas always much higher than that in the axes. In in vitro cultures,the duration of the lag phase before germination of isolatedembryonic axes increased with ABA content. The presence of cotyledonsalways lengthened the lag phase; longer lag phases were associatedwith greater concentrations of ABA in the cotyledons. Moreoverthe presence of cotyledons stimulated the growth of seedlings. Key words: ABA distribution, embryo maturation, axis and embryo germinability     

Isolation and structural analysis of two lipid A precursors from a KDO deficient mutant of Salmonella typhimurium differing in their hexadecanoic acid content

The extraction, purification and structural characterization of two lipid A precursors (Ia and Ib) differing only in one hexadecanoic acid are described. Both precursors were synthesized at elevated temperatures by a new mutant of Salmonella typhimurium (mutant Ts5) which is conditionally defective in synthesis of the 3-deoxy-d-manno-octulosonic acid region of lipopolysaccharides.Both precursors were purified by repeated phenol/chloroform/petroleum ether (PCP) extractions followed by thin layer chromatography. Teh precursor preparation was free of lipopolysaccharides and phospholipids and contained less than 0.1% protein. Structural analysis which included chemical degradation procedures as well as positive ion laser desorption (LDMS) mass spectroscopy of dephosphorylated lipid A precursors showed together that precursor Ia represents a diphosphorylated glucosamine disaccharide containing two ester, two amide-linked residues of 3-hydroxytetradecanoic acid and lacks the ester-linked dodecanoic, tetradecanoic and hexadecanoic acid as well as 3-deoxy-d-manno-octulosonic acid. Precursor Ib has the same basic structure as precursor Ia, but contains in addition one mol of hexadecanoic acid per mol disaccharide which is linked to the 3-hydroxy group of the amide-bound 3-hydroxy-tetradecanoic acid of the reducing, terminal glucosamine residue.The structure of precursor Ib supports the conclusion that hexadecanoic acid incorporation occurs at an early stage in lipid A biosynthesis prior to the attachment of 3-deoxy-d-manno-octulosonic acid and/or other polar substituents.Abbreviations LDMS laser desorption mass spectrometry - KDO 3-Deoxy-d-manno-octulosonic acid - Ts5 Salmonella typhimurium mutant Ts5 - PCP phenol/chloroform/petroleum ether - H₂F₂ hydrogen fluoride This work is dedicated to Prof. Dr. Drews, Freiburg, on the occasion of his 60th birthday     

Pitfalls in the assay of carboxymethylcellulase activity

A purified endocellulase from Sclerotium rolfsii and a crude cellulase preparation from Trichoderma reesei are used to illustrate several pitfalls associated with the assay of carboxymethylcellulase activity and the subsequent attainment of linear enzyme dilution curves. It is shown that the nature of both the enzymes and the substrate make the assay unsuitable for use in the calculation of enzyme recovery and purity.