The Photocycle of Bacteriorhodopsin in the Two-Dimensional Orthorombic Crystal Form of Purple Membrane

Laser flash photolysis and low-temperature absorption studies of the photocycle of orthorhombic purple membrane (o-PM) reveal the existence of the same K, L, and M intermediates as found in the native hexagonal purple membrane (h-PM). However, the 0 intermediate is missing in the o-PM. The absorption spectrum of the K intermediate of o-PM is blueshifted by ~15 nm relative to the K intermediate found in the hexagonal purple membrane. The decay relaxation time constants of M in the o-PM are higher by more than an order of magnitude than the corresponding relaxation time constants in the h-PM. Similarly to the h-PM, the decay of M depends on the pulse width of excitation. The time-independent anisotropy factor obtained in photoselection studies of the M intermediate demonstrates the complete immobility of bacteriorhodopsin (bR) within the o-PM matrix. The same anisotropy factor of 0.3 obtained for o-PM and for h-PM suggests that in both crystalline lattices the transition moment of the retinal chromophore has similar angles with the plane of the membrane. The dependence of the decay kinetics of M on its occupancy may suggest the existence of kinetic coupling between neighboring bR molecules.     

Molecular cloning of a pea mRNA encoding an early light induced,nuclear coded chloroplast protein

Summary cDNA clones were isolated for a chloroplast protein, the mRNA of which is induced to maximum levels within 2–4 h after onset of illumination in five day old, etiolated pea seedlings. The cDNA library was constructed from poly(A)⁺-mRNA which was isolated from 4 h illuminated seedlings. The extremely short induction period of the early light induced protein(ELIP)-mRNA established the basis of our screening procedure. Colony hybridization experiments were performed with³²P-labelled cDNA probes, synthesized from RNA of seedlings which had been exposed to different programs of illumination. Plasmid DNAs were isolated from colonies showing strong hybridization signals exclusively with cDNA corresponding to the 4 h-mRNA. Hybrid released translation of preselected plasmids p 17/C2 and p17/C4 revealed a peptide of M_r 24 000. After posttranslational importin vitro, the processed product of M_r 17 000 appears in the chloroplast. Using these clones, the expression of the ELIP-mRNA was investigated by DOT-hybridization. The ELIP-mRNA reaches maximum levels within 2–4 hours after onset of illumination. Our results correspond precisely to thein vivo characteristics and indicate positive identification of the sought clones.     

Oriented axon outgrowth from avian embryonic retinae in culture

The neural retina of avian embryos was spread on a membrane filter and cut in any desired orientation. Strips cut across the retina of 4- to 7-day chick or 3- to 6-day quail embryos were explanted onto collagen gels. Vigorous neurite outgrowth was seen for about 3 days, by which time many neurites were 3 mm long. Horseradish peroxidase (HRP) labeling showed that the cells producing the neurites were large and formed a layer near the inner limiting membrane, indicating that the neurites in vitro were axons of retinal ganglion cells. The size of the neurite population and the regions from which neurites emerged vaired with the donor age, while most neurites sprouted from the side of the explant formerly closest to the optic fissure. This pattern closely resembled that of axon growth in the normal retina, as revealed by SEM, silver staining, and HRP labeling. Mitotic inhibitors (Ara-C and FUdR) did not alter the neurite outgrowth. Pretreatment of retinae with trypsin or collagenase did not disorganize axons at the time of explantation, but tended to equalize neurite emergence on each side of the retinal strips. We suggest that microenvironmental factors, especially the enzyme-labile inner limiting membrane, are important for axon guidance in the retina.     

Ergebnisse ornithologischer Beobachtungen auf Sardinien im Winter 1961/62

Zusammenfassung Das Vogelleben der Mittelmeerländer ist in der Zeit der Winterregen bisher kaum untersucht worden. Verf. teilt deshalb Beobachtungsergebnisse von der Insel Sardinien mit, die er vom 15. X. 1961–15. III. 1962 während eines Studienaufenthaltes machen konnte. Der genannte Zeitraum umfaßt Beginn und Ende der sardischen Regenzeit und wird als Winter bezeichnet.Insgesamt wurden 125 Vogelarten beobachtet, von denen 65 Jahresvögel, 56 Gastvögel und 4 Sommervögel Sardiniens sind.Bei den Jahresvögeln interessierte vor allem die Vertikalverbreitung. Im Vergleich mit der Vertikalverbreitung zur Brutzeit ergeben sich teilweise beträchtliche Verschiebungen der Höhengrenzen. Für 10 Jahresvögel wird auch die horizontale Verbreitung mit Punktkarten dargestellt. Weitere Kapitel behandeln Biotope, Schwarmbildung und Vergesellschaftung sowie den Gesang im Winter.Die Gastvögel werden nach ihrer Herkunft untersucht, wobei über 260 Ringfunde ausgewertet werden. Auch über Ankunft und Abzug, Massenschlafplätze und Wasservogelleben der Gastvögel wird berichtet.In einer tabellarischen Übersicht sind wichtige Daten aller beobachteten Jahres- und Gastvögel zusammengefaßt.Abschließend werden Aufgaben der weiteren ornithologischen Erforschung Sardiniens genannt, die vor allem in der Erkundung abgelegener Gebirgsteile und weiterer Beobachtertätigkeit in den Winter- und Sommermonaten bestehen.

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Summary The bird life of the Mediterranean countries has hardly been studied during the period of the winter rains. Therefore the author records of observations results made on Sardinia from the 15^th of October, 1961 to the 15^th of March, 1962 while studying. The period mentioned above comprises the beginning and end of the Sardinian rain period, which is termed winter.Alltogether 125 bird species have been observed, 65 of which were resident, 56 visitors and 4 Sardinian summer birds.Above all the elevation distribution of residents was of interest. Comparing the vertical distribution during the breeding period with that during the winter period considerable displacements in the elevation limits were shown. For 10 residents the horizontal distribution is also described by means of dotted maps. Further chapters deal with the environment, flock formation, socialization and the winter song.The breeding regions of the visitors has been studied from the records of more than 260 ringed birds. Reports of the visitors' arrival and departure, mass sleeping places and aquatic life was also given.In a tabulated survey important facts are summarized of all residents and visitors.Finally, problems of further ornithological studies on Sardinia are mentioned which are exploration of remote mountain parts and further observation during the winter and summer periods.

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Riassunto La vita degli uccelli del bacino mediterraneo è stata fino ad oggi poco esaminata durante la stagione delle piogge.Perciò l'autore comunica i risultati delle sue osservazioni, fatte nell'isola di Sardegna durante un soggiorno di studio dal 15. X. 1961 al 15. III. 1962.Questo periodo comprende l'inizio e la fine della stagione sarda delle piogge ed è chiamato inverno.In tutto furono osservate 125 specie, delle quali 65 sono stazionarie, 56 ospiti e 4 uccelli d'estate di Sardegna.La distribuzione verticale degli uccelli stazionari risulta di particolare interesse.Si riscontrano considerevoli spostamenti dei limiti d'altezza, confrontando la distribuzione verticale d'inverno e d'estate.Cartelli di punti mostrano la distribuzione orizzontale per 10 uccelli stazionari.Altri capitoli trattano di biotopi, formazioni di stormi, socializzazioni e canto d'inverno.La provenienza degli ospiti è studiata secondo la valorizzazione di più di 260 ritrovamenti di uccelli inanellati.Vengono trattati anche l'arrivo e la partenza degli ospiti, i posti per dormire in massa e la vita degli uccelli acquatici.Dati importanti su tutti gli uccelli, sia stazionari che ospiti, sono raccolti in un quadro sinottico.Infine si fa cenno ad altri problemi degli studi ornitologici in Sardegna, che consistono soprattutto nella esplorazione delle montagne remote ed in ulteriori osservazioni, sia nella stagione invernale che in quella estiva.

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Für seine ständige, wertvolle Hilfe und Beratung bei meiner ornithologischen Tätigkeit auf Sardinien danke ich Herrn Prof. Dr.G. Niethammer, für die Ermöglichung meines Studienaufenthalts Herrn Prof. Dr. Dr.R. Lehmensick sehr herzlich. Dank abstatten möchte ich auch den Universitäten Bonn und Cagliari sowie vielen sardischen Freunden, die mir auf vielfältige Weise behilflich waren. HerrnH. E. Wolters danke ich für die Durchsicht des Manuskripts.     

Kurze Mitteilungen

Zusammenfassung Ein Paar Türkentauben brütete vom 29. 1. bis 15. 2. 1966 auf einem Straßenbaum in Berlin-Tempelhof. Es wurde nur ein Ei gelegt. Nach 17 Tagen schlüpfte das gelbbedaunte Junge. Es ist dann kurz danach, wahrscheinlich beim Umherkriechen auf dem Nestrand, erfroren. Die Umstände, unter denen die Brut erfolgte, waren äußerst ungünstig. Die Temperatur lag seit dem 7. 2. 1966 dauernd unter Null (–9 und –13 Grad). Die brütende Taube hatte von Anfang an auf dem Nestrand brüten müssen, da die Mulde schon vor der Eiablage völlig mit Schnee bedeckt war. Der brütende Vogel war mehrere Tage und Nächte von einem hohen Schneewall umgeben, der sich auf dem Nest gebildet hatte. Dieses Nest wurde von Mai 1964 an viermal von einem Türkentaubenpaar zum Brüten benutzt. Es wird vermutet, daß zum mindesten der eine Partner, der Tauber, während der ganzen Zeit derselbe geblieben ist.     

The wind-orientation of walking carrion beetles

The wind-orientation of carrion beetles (Necrophorus humator F.) was studied by use of a locomotion-compensator.

On the role of the N-terminus of the extrinsic 33 kDa protein of Photosystem II

The role of the N-terminus of the extrinsic 33 kDa protein of Photosystem II has been investigated by means of site-directed mutagenesis and cross-linking. Replacement of Asp-9 resulted in a dramatic increase in proteolytic sensitivity leading to the degradation of the protein forming a 31 kDa fragment with an undefined N-terminus. This fragment was unable to restore oxygen evolution. However, the variants of the 33 kDa protein which remained intact could reconstitute oxygen evolution as effectively as the wild-type protein. Cross-linking experiments with a water-soluble carbodiimide revealed that mutagenesis of residue D9 led to the disruption of an intramolecular salt bridge. Therefore we suggest that the N-terminus of the 33 kDa protein is necessary for maintaining the binding ability of the protein to Photosystem II but might not be involved in binding itself.     

Germ-Line Mutations in the von Hippel–Lindau Tumor-Suppressor Gene Are Similar to Somatic von Hippel–Lindau Aberrations in Sporadic Renal Cell Carcinoma

von Hippel–Lindau (VHL) disease is a hereditary tumor syndrome predisposing to multifocal bilateral renal cell carcinomas (RCCs), pheochromocytomas, and pancreatic tumors, as well as angiomas and hemangioblastomas of the CNS. A candidate gene for VHL was recently identified, which led to the isolation of a partial cDNA clone with extended open reading frame, without significant homology to known genes or obvious functional motifs, except for an acidic pentamer repeat domain. To further characterize the functional domains of the VHL gene and assess its involvement in hereditary and nonhereditary tumors, we performed mutation analyses and studied its expression in normal and tumor tissue. We identified germ-line mutations in 39% of VHL disease families. Moreover, 33% of sporadic RCCs and all (6/6) sporadic RCC cell lines analyzed showed mutations within the VHL gene. Both germ-line and somatic mutations included deletions, insertions, splice-site mutations, and missense and nonsense mutations, all of which clustered at the 3' end of the corresponding partial VHL cDNA open reading frame, including an alternatively spliced exon 123 nt in length, suggesting functionally important domains encoded by the VHL gene in this region. Over 180 sporadic tumors of other types have shown no detectable base changes within the presumed coding sequence of the VHL gene to date. We conclude that the gene causing VHL has an important and specific role in the etiology of sporadic RCCs, acts as a recessive tumor-suppressor gene, and appears to encode important functional domains within the 3' end of the known open reading frame.     

Transient expression in leaf mesophyll protoplasts of Arabidopsis thaliana

Conditions for maximising transient expression of GUS in leaf mesophyll protoplasts of Arabidopsis thaliana ecotype C24 were investigated. It was found that the factors most influencing expression levels, with optimum levels in parenthesis, were plasmid DNA quantity (100 g per 5 × 10⁵ protoplasts), inclusion of carrier DNA (50 g), PEG pH and amount (pH above 6, and total PEG concentration at least 9% w/w) and the topological form of the DNA. Linearised plasmid DNA with long flanking sequences 3 and 5 to the marker gene yielded the highest levels of GUS expression.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - GUS -glucuronidase - MU methylumbelliferone - PEG polyethylene glycol - X-gluc 5-bromo-4-chloro-3-indolyl--glucuronic acid