Structural aspects of Golgi function

Since its discovery, the Golgi complex has attracted the attention of cell biologists because of its fashionable morphology and central position within the secretory system of the cell. Here, we discuss how the three-dimensional architecture of the Golgi complex relates to its multiple functions in protein sorting and processing, and how an analysis of the morphology of the Golgi complex can help to provide an understanding of the mechanisms involved in transport through this unique organelle.     

Structural and biochemical aspects of keratan sulphate in the cornea

Keratan sulphate (KS) is the predominant glycosaminoglycan (GAG) in the cornea of the eye, where it exists in proteoglycan (PG) form. KS-PGs have long been thought to play a pivotal role in the establishment and maintenance of the array of regularly-spaced and uniformly-thin collagen fibrils which make up the corneal stroma. This characteristic arrangement of fibrils allows light to pass through the cornea. Indeed, perturbations to the synthesis of KS-PG core proteins in genetically altered mice lead to structural matrix alterations and corneal opacification. Similarly, mutations in enzymes responsible for the sulphation of KS-GAG chains are causative for the inherited human disease, macular corneal dystrophy, which is manifested clinically by progressive corneal cloudiness starting in young adulthood.     

The influence of different host plants on some biological aspects ofHeliothis armigera (Hub.)

Summary The suitability of 6 different plants as natural food forHeliothis armigera was tested. The different biological aspects ofH. armigera were taken in consideration. Kidney bean pods and cotton plant leaves were the most successful host plants tested as they increased the pupal weight and the reproductive potential of the resulting moths, followed by lettuce, which decreased the larval duration remarkably.     

The carotenoid pigments of six species of adult acanthocephala

Zusammenfassung Die Carotinoide in 6 Spezies erwachsener Acanthocephalen wurden identifiziert. Lutein wurde als einziges Carotinoid inP. galaxis undN. pseudemydis gefunden und als wichtigstes Carotinoid inM. hirudinaceus festgestellt.F. anatis undP. laevis enthielten nur -Carotin, während das veresterte Astexanthin als einziges Pigment inN. ornatus auftrat.

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We thank Dr.M. Hine and Dr.A. Pike for sending us material which was used in this study. Part of the work was carried out in the Dept. of Zoology, University of Massachusetts, Amherst (Mass., USA).     

Carotenoids and carotenogenesis in cyanobacteria: unique ketocarotenoids and carotenoid glycosides

Cyanobacteria grow by photosynthesis, and necessarily contain chlorophyll and carotenoids, whose main functions are light harvesting and photoprotection. In this review, we discuss the carotenoids, carotenogenesis pathways, and characteristics of carotenogenesis enzymes and genes in some cyanobacteria, whose carotenogenesis enzymes have been functionally confirmed. In these cyanobacteria, various carotenoids have been identified, including the unique ketocarotenoids, echinenone and 4-ketomyxol; and the carotenoid glycosides, myxol glycosides and oscillol diglycosides. From these findings, certain carotenogenesis pathways can be proposed. The different compositions of carotenoids among these species might be due to the presence or absence of certain gene(s), or to different enzyme characteristics. For instance, two distinct beta-carotene ketolases, CrtO and CrtW, are properly used in two pathways depending on the species. One beta-carotene hydroxylase, CrtR, has been identified, and its substrate specificities vary across species. At present, functionally confirmed genes have been found in only a few species, and further studies are needed.     

The major carotenoid pigments of six species of barnacle

Résumé L'astaxanthine (et ses esters) est le caroténoïde principal de 6 espèces de balanes, et la zeaxanthine est le principal xanthophylle neutre. Les différences de composition du pigment des espèces sont probablement liées aux proportions relatives de la matière animale et végétale dans ses aliments.     

The carotenoid pigments of the cedar apple rust fungus

Zusammenfassung Die Untersuchung der Carotinoide aus den Äzidien des RostpilzesGymnosporangium juniperi-virginianae Schw. ergab das Vorliegen von 66,5%-Carotin und 33,5%-Carotin (Durchschnittswerte). Diese Werte stimmen mit denjenigen anderer Autoren für Teleuto-Stadium und Pyknidenform überein. Art und Mengenverhältnis der Carotinoide in drei Stadien vonGymnosporangium juniperi-virginianae Schw. (auf verschiedenen Wirtspflanzen) sind daher ungefähr identisch.     

Studies of the mechanism of action of the carotenoid crocetin

Summary The carotenoid crocetin was found to be taken up by normal rat muscle cells grown in vitro, and was found in the ribosomal-microsomal fraction, supporting the hypothesis that crocetin affects cell division enzymatic processes.     

Studies of the mechanism of action of the carotenoid crocetin.

The carotenoid crocetin was found to be taken up by normal rat muscle cells grown in vitro, and was found in the ribosomal-microsomal fraction, supporting the hypothesis that crocetin affects cell division enzymatic processes.     

Blood plasma investigations by resonance raman spectroscopy: Detection of carotenoid pigments

Summary Using Raman spectroscopy, we demonstrate that low levels of -carotene, lycopene, and xanthophyll give rise to resonance enhanced bands in blood plasma. These results explain the significance of previously unidentified spectral maxima which have been related to the state of health of the blood donor.     

Acidolytic cleavage of peptide bonds during acetylation

Zusammenfassung Eine Spaltung von Peptiden tritt auf, wenn versucht wird, gewisse Derivate in an sich üblicher Weise herzustellen. Damit wird auf die Möglichkeit einer Fehlinterpretation hingewiesen.     

Microincineration of sea urchin eggs during cleavage

Zusammenfassung Im Zytoplasma der unbefruchteten Seeigeleier sind die Aschen gleichmäßig verteilt; gegen die Kortikalschicht sind sie hingegen etwas angehäuft. Nach der Befruchtung, im Spermaster-Stadium, ordnen sich die Aschen radiär um den zentral gelegenen Kern. Eine starke Aschenansammlung findet sich an der Stelle der Spindel.     

Processing of peptide and hormone precursors at the dibasic cleavage sites

Many functionally important cellular peptides and proteins, including hormones, neuropeptides, and growth factors, are synthesized as inactive precursor polypeptides, which require post-translational proteolytic processing to become biologically active polypeptides. This is achieved by the action of a relatively small number of proteases that belong to a family of seven subtilisin-like proprotein convertases (PCs) including furin. In view of this, this review focuses on the importance of privileged secondary structures and of given amino acid residues around basic cleavage sites in substrate recognition by these endoproteases. In addition to their participation in normal cell functions, PCs are crucial for the initiation and progress of many important diseases. Hence, these proteases constitute potential drug targets in medicine. Accordingly, this review also discusses the approaches used to shed light on the cleavage preference and the substrate specificity of the PCs, a prerequisite to select which PCs are promising drug targets in each disease.     

Inhibition of sea urchin egg cleavage by ribonuclease

Résumé La ribonucléase exerce une action inhibitrice sur le clivage des ufs d'oursins. La source commerciale de l'enzyme, la concentration utilisée et l'état des ufs déterminent les effets obtenus. Ceux-ci varient entre une inhibition totale immédiate et un ralentissement des divisions cellulaires, suivi d'un développement anormal éventuellement abortif.En outre, la ribonucléase a une action complexe sur la membrane de fertilisation, la couche hyaline et la membrane cellulaire. Cette dernière action pourrait être liée aux effets antimitotiques observés.

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Contribution No.126 from the Oceanographic Institute, Florida State University, Tallahassee (Florida). Aided by a grant from the National Science Foundation.     

Cellular and molecular aspects of Lyme arthritis

Lyme disease is a multisystem illness initiated upon infection with the spirochete Borrelia burgdorferi. Whereas the majority of patients who develop Lyme arthritis may be successfully treated with antibiotic therapy, about 10% go on to develop arthritis which persists for months to years, despite antibiotic therapy. Development of what we have termed treatment-resistant Lyme arthritis has previously been associated with both the presence of particular major histocompatibility complex class II alleles and immunoreactivity to the spriochetal outer surface protein A (OspA). Recently, we showed that patients with treatment-resistant Lyme arthritis, but not patients with other forms of arthritis, generate synovial fluid T cell responses to an immunodominant epitope of OspA and a highly homologous region of the human-lymphocyte-function-associated antigen-1α _L chain. Identification of a bacterial antigen capable of propagating an autoimmune response against a self-antigen provides a model of molecular mimicry in the pathogenesis of treatment-resistant Lyme arthritis. Received 21 December 1999; received after revision 10 April 2000; accepted 11 April 2000