Christer Hansson

The macrophage migration inhibitory factor MIF is a phenylpyruvate tautomerase

A macrophage migration inhibitory factor (MIF), originally described as a product of activated lymphocytes, has been defined as a 12 kDa protein, expressed in a wide variety of tissues. Here MIF is identified as a phenylpyruvate tautomerase (EC 5.3.2.1) having p‐hydroxyphenylpyruvate and phenylpyruvate as its natural substrates. The definition of MIF as an enzyme may yield insight into the mechanism of action of this proinflammatory and immunomodulating cytokine.

Identification and quantitative measurements of biogenic amines and DOPA in the central nervous system and haemolymph of the crayfish Pacif ast acus leniusculus (crustacea)

Abstract 1. The biogenic amines dopamine (DA), noradrenaline (NA), octopamine (OA), serotonin (5-HT) and the amino acid dihydroxyphenylalanine (DOPA) have been identified and quantitatively measured in the crayfish nervous system and in haemolymph employing high performance liquid chromatography (HPLC). 2. The substances occurred in the nervous system in amounts ranging between 0.1 and 0.7 μg/g w/w. 3. The haemolymph contained very small amounts of NA, OA, 5-HT and DOPA. 4. No adrenaline (A) was present. 5. Prolonged handling of the animals caused dramatic changes in DOPA levels. 6. Depletion experiments using reserpine caused a pronounced decrease in the content of DA, NA, OA and 5-HT in the nervous system. DOPA, however, remained unaffected.

Analysis of cysteinyldopas, dopa, dopamine, noradrenaline and adrenaline in serum and urine using high-performance liquid chromatography and electrochemical detection.

The catecholic amino acids, dopa, 2-S- and 5-S-cysteinyldopa, and 2,5-S,S-dicysteinyldopa were determined qualitatively in serum from patients with malignant melanoma by reversed-phase high-performance liquid chromatography, using electrochemical detection. In urine the catecholamines dopamine, noradrenaline and adrenaline were also determined qualitatively, as well as the above-mentioned compounds, in a single chromatographic run. The conditions were optimized by changing the pH of the mobile phase and by the addition of methanesulphonic acid. A comparison was made between the performance of four commercial reversed-phase packing materials containing chemically bonded octadecyl groups, using a standard mixture of catecholic amino acids. The influence of ionic strength, pH and amount of methanesulphonic acid on retention was investigated.

Stable structural color patterns displayed on transparent insect wings

Color patterns play central roles in the behavior of insects, and are important traits for taxonomic studies. Here we report striking and stable structural color patterns—wing interference patterns (WIPs)—in the transparent wings of small Hymenoptera and Diptera, patterns that have been largely overlooked by biologists. These extremely thin wings reflect vivid color patterns caused by thin film interference. The visibility of these patterns is affected by the way the insects display their wings against various backgrounds with different light properties. The specific color sequence displayed lacks pure red and matches the color vision of most insects, strongly suggesting that the biological significance of WIPs lies in visual signaling. Taxon-specific color patterns are formed by uneven membrane thickness, pigmentation, venation, and hair placement. The optically refracted pattern is also stabilized by microstructures of the wing such as membrane corrugations and spherical cell structures that reinforce the pattern and make it essentially noniridescent over a large range of light incidences. WIPs can be applied to map the micromorphology of wings through direct observation and are useful in several fields of biology. We demonstrate their usefulness as identification patterns to solve cases of cryptic species complexes in tiny parasitic wasps, and indicate their potentials for research on the genetic control of wing development through direct links between the transregulatory wing landscape and interference patterns we observe in Drosophila model species. Some species display sexually dimorphic WIPs, suggesting sexual selection as one of the driving forces for their evolution.

Boronic acid—silica: a new tool for the purification of catecholic compounds on-line with reversed-phase high-performance liquid chromatography

Abstract The properties of silica-immobilized benzeneboronic acids are discussed both in terms of coating of the silica and efficiency of these particles for use in a high-performance liquid chromatography column. The silica derivative displays an affinity for catecholic compounds, whose content in biological samples may be estimated with a column-switching system using boronic acid silica on-line followed by a reversed-phase chromatographic system. The dual system is suitable for direct injection of crude biological samples, and at least 1 ml of sample can be injected without additional band broadening.

The effect of cysteine on oxidation of tyrosine dopa, and cysteinyldopas

SummaryThe influence of cysteine on the oxidation of tyrosine, dopa, and monocysteinyldopas by mushroom tyrosinase was reexamined. During oxidation of tyrosine in the presence of cysteine the concentration of dopa increased slowly, whereas the concentration of cysteinyldopas increased more rapidly. When the concentration of cysteine decreased the cysteinyldopas were rapidly consumed and dopa concentrations increased sharply.Experiments on the oxidation of dopa by tyrosinase in the presence of cysteine showed that this thiol does not inhibit the oxidation. Dopa concentrations decreased more rapidly in the presence of cysteine because cysteine addition to dopaquinone prevented reformation of dopa from dopaquinone.Both 2-S-cysteinyldopa and 5-S-cysteinyldopa are substrates for tyrosinase. The oxidation of cysteinyldopas was inhibited at high cysteine concentrations. The greater part of 2,5-S,S-dicysteinyldopa formed during the oxidation of monocysteinyldopas in the presence of cysteine is derived from 5-S-cysteinyldopa, which is a better substrate for tyrosinase than 2-S-cysteinyldopa. The fact that cysteine binds more rapidly to 5-S-cysteinyldopaquinone than to 2-S-cysteinyldopaquinone further stresses the importance of 5-S-cysteinyldopa in the formation of 2,5-S,S-dicysteinyldopa.Oxidation of dopa in the presence of cysteine and glutathione or methionine showed that glutathione is added to dopaquinone but less rapidly than cysteine. Methionine showed insignificant addition to dopaquinone.When dopa or 5-OH-dopa is added to an incubate of cysteinyldopa and tyrosinase the oxidation of cysteinyldopa is accelerated owing to oxidation of cysteinyldopa by dopaquinone or 5-OH-dopaquinone.

The quantitative determination of 5-S-cysteinyldopa and dopa in normal serum and in serum from patients with malignant melanoma by means of high-pressure liquid chromatography.

A method is described for quantitative determination of 5-S-cysteinyldopa and Dopa in serum involving high-pressure liquid chromatographic analysis (HPLC) and electrochemical detection. The chromatographic system allows estimation of injected amounts corresponding to 25 pg of 5-S-cysteinyldopa and Dopa. In normal subjects the mean serum 5-S-cysteinyldopa concentration was 2.8 ng/ml (range 0.4--12 ng/ml) and the mean serum Dopa 6.3 ng/ml (range 4--10 ng/ml). Patients with melanoma metastases showed increased serum concentrations of 5-S-cysteinyldopa.

A taxonomic study on the Palearctic species of Chrysonotomyia Ashmead and Neochrysocharis Kurdjumov (Hymenoptera: Eulophidae).

The taxonomic status and range of Chrysonotomyia Ashmead and Neochrysocharis Kurdjumov are discussed. The seven Palearctic species of Chrysonotomyia are reviewed and a key to the species is presented. The Palearctic species of Neochrysocharis are revised, and a key to the species is given. Twenty species are recognized. Two of the species are described as new: acuminata and ambitiosa, both from Greece. Six new synonyms are suggested: Neochrysocharis badghysi Ryabtschinsky, N. rezniki Ryabtschinsky = N. albiscapus Erdos; N. aeneicrus Erdos = N. clinias (Walker); Chrysocharis obscuripes Forster, N. trifolii Erdos = N. formosa (Westwood); N. graminearum Szelenyi & Szocs = Chrysocharis chlora Graham. The species Neochrysocharis immaculata Kurdjumov previously synonymized with N. aratus (Walker), and later re-erected, is again put as synonym under aratus. Five new combinations are suggested: Achrysocharella chlorogaster Erdos, A. sericea Erdos, Chrysonotomyia longiventris Askew, Closterocerusformosus Westwood, all four to Neochrysocharis; Neochrysocharis chlora (originally in Chrysocharis) is transferred back to Chrysocharis. Lectotypes are designated for Entedon lanassa Walker, Neochrysocharis aeneicrus, N. albiscapus, N. cuprifrons Erdos, N. iris Erdos and Chrysocharis obscuripes. Some changes to update the Entedontinae from the key in Peck et al. (1964) are suggested.

5-Hydroxytryptamine in the retina of some mammals.

A set of indoleamine accumulating neurons has been described in the retina of several species. Their transmitter is unknown though 5-hydroxytryptamine has been suggested. We have studied the 5-hydroxytryptamine concentration in the retina of cows, pigs, guinea-pigs and also of rabbits in which the blood had been washed out. It was found to be 26·2 ng/g ( s.e.m. =7·17) in cow retina, 5·9 ( s.e.m. =0·83) in pig retina and 6·03 ng/g ( s.e.m. =2·61) in guinea-pig retina. Concentrations in this range could well be due to blood platelet 5-hydroxytryptamine and this was corroborated by the about six-fold fall from the normal concentration to 3·8 ng/g ( s.e.m. =0·9) which occurred when rabbit retinas were perfused to remove the blood. The possible presence of indoleamine accumulating neurons in some mammals (cow and pig) was also investigated by means of fluorescence microscopy. No indoleamine accumulating neurons could be found with this technique. Nevertheless, autoradiography has shown that there are indoleamine accumulating neurons in the cow and pig retina, and we suggest that these neurons have the ability to modify the indoleamines they accumulate into substances related to 5-hydroxytryptamine but unable to form fluorophores with formaldehyde in tissues.

The evolution of host use and unusual reproductive strategies in Achrysocharoides parasitoid wasps.

We studied host selection and exploitation, two crucial aspects of parasite ecology, in Achrysocharoides parasitoid wasps, which show remarkable host specificity and unusual offspring sex allocation. We estimated a molecular phylogeny of 15 Achrysocharoides species and compared this with host (plant and insect) phylogenies. This tri‐trophic phylogenetic comparison provides no evidence for cospeciation, but parasitoids do show phylogenetic conservation of the use of plant genera. Patterns of sequence divergence also suggest that the parasitoids radiated more recently (or evolved much faster) than their insect hosts. Three main categories of brood production occur in parasitoids: (1) solitary offspring, (2) mixed sex broods and (3) separate (split) sex broods. Split sex broods are very rare and virtually restricted to Achrysocharoides, while the other types occur very widely. Our phylogeny suggests that split sex broods have evolved twice and provides evidence for a transition from solitary to mixed sex broods, via split sex broods, as predicted by theory.