Untersuchungen über Azolla und ihre Symbiose mit Blaualgen

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Structural characterization of glycosphingolipids by direct chemical ionization mass spectrometry

This report describes the use of direct chemical ionization mass spectrometry with ammonia as the reagent gas (NH3-DCI) for structure analysis of underivatized, permethylated and permethylated and reduced glycosphingolipids. In contrast to ionization by electron impact, the NH3-DCI mass spectra exhibit intense molecular and carbohydrate sequence-related ions using microgram amounts of sample. Underivatized glycosphingolipids with up to two sugar residues yield abundant protonated and ammonia-cationized molecular ions and structurally significant fragments. Permethylation in conjunction with NH3-DCI can be used to obtain molecular weight as well as oligosaccharide sequence and branching information on neutral, acidic and complex-type glycosphingolipids with up to five sugar residues. Reduction of the permethylated derivatives gives rise to several new, structurally significant fragments in the corresponding NH3-DCI mass spectra which enable fatty acid and base compositions to be determined. Isotopically labeled reagent gases have been used to confirm the assignment of fragment structures and to demonstrate that the ions observed are unique to the NH3-DCI mass spectra.     

Metabolism of androstenedione by human ovarian tissues in vitro with particular reference to reductase and aromatase activity

The ability of granulosa and theca cells of the human ovarian follicle at different stages of development, as well as stromal and luteal tissues from human ovaries to metabolize androstenedione (delta 4) to testosterone (T), dihydrotestosterone (DHT), estrone (E1) and estradiol (E2) with or without exposure to additional amounts of folicle-stimulating hormone was investigated by in vitro experiments. The results show that all the aforementioned ovarian tissues metabolized delta 4 to DHT. Indeed, with the exception of estrogen-secreting granulosa cells from large antral follicle (greater than 10 mm diameter) and possibly also luteal tissue from mid-luteal phase ovaries, the various ovarian tissues preferentially metabolized delta 4 to DHT instead of E (E1 + E2). Although thecal tissue is a major source of delta 4 in human ovaries it is concluded that the granulosa cells do not interact with the theca for the synthesis of E as the follicle enlarges from 1 to 10 mm in diameter. Indeed, excessive thecal delta 4 during this growth phase probably inhibits normal follicular development. However, as the follicle enlarges beyond 10 mm in diameter, and as the granulosa cells begin to preferentially metabolize delta 4 to E, the two cell-types of the follicle may increasingly interact to enhance the follicular output of E.     

Evaluation of methodological and biological influences on the collection and composition of exhaled breath condensate

Abstract

The purpose of this inter-species comparison (calves and pigs) was to identify methodological and biological influences on the collection and composition of exhaled breath condensate (EBC). A total of 352 EBC samples were collected, whilst variables of ventilation were registered in parallel. Partial pressure of carbon dioxide (pCO₂) and pH were analysed in non-degassed EBC samples. The concentration of total protein in EBC was measured colorimetrically. In both species, lung function was evaluated before and after EBC collection. Statistical analyses were performed to study the effect of EBC collection on lung function and to identify the influence of ventilatory variables on the collection and composition of EBC. Collection of EBC did not affect lung function. Despite the volume of EBC collected per unit time being primarily dependent on ventilation per unit time, species-specific conditions during the EBC collection process resulted in different dependences of EBC collection from other variables of ventilation (i.e. maximal airflow during expiration or expired tidal volume kg^?1 body weight). The concentration of protein ml^?1 EBC increased with the expired volume per min and with peak expiratory flow. Although the pCO₂ in fresh EBC was significantly negatively dependent on the duration of collection, comparable pHs (5.6???6.2) were measured in EBC of both calves and pigs. The obtained data may help one standardize EBC collection in different species.     

Variable amounts of DNA related to the size of chloroplasts III. Biochemical determinations of DNA amounts per organelle

Plastid genomes (plastomes) are part of the integrated compartmentalised genetic system of photoautotrophic eukaryotes. They are highly redundant and generally dispersed in several regions (nucleoids) within organelles. DNA quantities and number of DNA-containing regions per plastid vary and are developmentally regulated in a way not yet understood. Reliable quantitative data describing these patterns are scarce. We present a protocol to isolate fractions of pure plastids with varying average sizes from leaflets (≤1 mm) and leaves of different developmental stages continuously up to maturity (25 cm) from Beta vulgaris L. (sugar beet) to determine DNA amounts per organelle. The approach is based on plastid purification from homogenates of moderately fixed tissue by differential and isopycnic gradient centrifugations and on application of two different DNA specific colorimetric reactions after removing potentially interfering compounds. The sensitive fluorochrome DAPI (4′,6-diamidino-2-phenylindole) was used to estimate numbers and emission intensity of nucleoids per plastid. The amounts determined ranged from 0.15 to 4.9 × 10⁻² pg DNA for plastids of 1→8 μm average diameter, corresponding from approximately a dozen to 330 genome equivalents per organelle and on average four to seven copies per nucleoid. The ratio of plastid/nuclear DNA changed continuously during leaf development from as little as 0.4% to about 20% in fully developed leaves. On the other hand, mesophyll cells of mature leaves differing in ploidy (di-, tri- and tetraploid) appeared to maintain a relatively constant nuclear genome/plastome ratio, equivalent to about 1,700 copies per C-value.