Effects of upstream deletions on light- and oxygen-regulated bacterio-opsin gene expression in Halobacterium halobium

The bacterio-opsin gene (bop) of Halobacterium halobium is located within a cluster with three other genes. Growth conditions of high light intensity and low oxygen tension induce bop gene cluster expression. To identify putative regulatory factor binding sites upstream of the bop gene, we have compared sequences upstream of the bop gene with the corresponding sequences from two other genes in the bop gene cluster. Conserved sequence motifs were observed which may mediate the effect of high light intensity and/or low oxygen tension on bop gene expression. Based on these motifs, a set of mutants was constructed which contained deletions upstream of the bop gene. These constructs were tested in a host strain where bop gene expression is independent of oxygen regulation and in another strain where it is regulated by oxygen and light. The minimal upstream sequence required for both light- and oxygen-regulated bop gene expression was determined to be 54 bp.     

Aus der Geschichte der Orientierungsforschung

Zusammenfassung Die Arbeit schildert die Entwicklungen auf dem Gebiet der Orientierungsforschung und den Wandel der Ansichten im Laufe der Zeit. Am Anfang stand Mitte des letztenJh. v. Middendorffs Vermutung, Zugvögel würden sich nach einem Magnetkompaß orientieren.Viguier diskutierte die Möglichkeit, verfrachtete Vögel würden anhand des Magnetfelds heimfinden, währendExner undReynaud kinästhetische Orientierungsmechanismen vermuteten. Erste Versuche, diese Hypothesen experimnentell zu bestätigen, blieben erfolglos.Anfang dieses Jh. versuchte man durch Verfrachtungsversuche festzustellen, unter welchen Umständen und über welche Entfernungen sich Vögel orientieren können. Seevögel zeigten sehr gute Heimkehrleistungen auch aus unbekanntem Gelände; die Versuche mit Brieftauben führten dagegen zu dem Schluß, Vögel könnten sich nur anhand bekannter Landmarken orientieren. In den 30er Jahren machten die systematischen Verfrachtungsversuche vonRüppell undWojtusiak jedoch deutlich, daß auch Stare und Schwalben von unbekannten Orten über große Entfernungen mit beachtlicher Geschwindigkeit heimkehren konnten. Die gleichzeitig begonnenen Versuche der Vogelwarte Rossitten und Helgoland zur Analyse des Vogelzugs ergaben, daß das Zugverhalten von den Bedingungen, unter denen die Vögel lebten, und bei sozialen Arten auch von Artgenossen mitbestimmt wird. Wildvögel zeigten bemerkenswerte Orientierungsleistungen, doch deren Grundlage blieb weiterhin offen.In den 40er Jahren führten die Untersuchungen vonHeinroth &Heinroth an Brieftauben abermals zu der Vermutung, die Heimkehr nach Verfrachtung beruhe auf mehr oder weniger systematischem Suchen, bis die Vögel auf bekanntes Gelände treffen; dann würden sie sich nach vertrauten Landmarken orientieren. Diese Ansicht fand weite Verbreitung;Yeagleys Hypothese einer Orientierung nach Magnetfeldparametern und der Coriolis-Kraft konnte sich nicht durchsetzen.Methodische Neuerungen leiteten Anfang der 50er Jahre die systematische experimentelle Analyse der Vögel ein.Kramer beschrieb den Sonnenkompaß und stelle mit dem Karte-Kompaß-Prinzip eine erste umfassende Theorie der Orientierung vor, die davon ausgeht, daß bei jedem Orientierungsvorgang ein externes Referenzsystem — ein Kompaß — beteiligt ist. Die Untersuchungen der Folgezeit führten zu einem recht guten Verständnis der Zugorientierung. Das Heimfinden nach Verfrachtung ist dagegen immer noch ein offenes Problem; keine der derzeit diskutierten Hypothesen kann alle bekannten Phänomene erklären. Es mehren sich jedoch die Hinweise, daß das Navigationssystem sehr variabel und in hohem Maße redundant ist, so daß mit einer einfachen Antwort gar nicht zu rechnen ist.

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On the history of orientation research

Summary This paper describes the developments and changes of ideas in the field of bird orientation research, which began in the middle of last century when v.Middendorff first suggested magnetic compass orientation in migrating birds. Still in the 19th century, two different hypotheses were proposed to explain homing.Viguier suggested that the birds made use of the spatial distribution of magnetic parameters, whereasExner andReynaud assumed that the birds were able to trace the route of the outward journey kinaesthetically. Attempts to obtain experimental support for either theory were unsuccessful.The first three decades of this century were characterized by displacement experiments designed to learn under what conditions and over what distances birds were able to return. The results obtained with seabirds indicated much more sophisticated navigational abilities than the experiments with homing pigeons, which led authors to believe that birds oriented by following familiar landmarks and could only return from unknown sites if they by chance reached a familiar region. This view became widely accepted when it was presented in the review articles ofWarner andStresemann.In the 1930s, however, systematic displacement experiments with wild birds changed the general views on orientation completely.Rüppell andWojtusiak showed that Starlings and Swallows could return from unknown sites over large distances with considerable speed. At the same time, the Vogelwarten (bird banding stations) Rossitten and Helgoland initiated programs to obtain more information on the nature of migratory orientation. The results indicated that migratory behavior can be modified by the conditions under which the birds live and, in social species, by conspecifics.Drost's experiment with Sparrowhawks gave the first indications that young birds and adult birds use different orientation mechanisms. Remarkable navigational abilities were demonstrated in wild birds, yet the mechanisms they used, were still unknown.The ideas on orientation changed again in the 1940s, whenHeinroth &Heinroth reported the resuls of their study on the orientation of homing pigeons. They suggested that pigeons, when released in an unfamiliar area, searched until they meet familiar terrain and then oriented by landmarks known from previous flights.Grifffin, whose attempts to interfer with homing by depriving displaced birds of magnetic and kinaesthetic information had failed, held similar views. A new global hypothesis byYeagley, suggesting that homing pigeons made use of a grid map formed by isolines of Coriolis force and vertical intensity of the magnetic field, was not accepted.In 1950, methodological innovations byKramer andMatthews brought new impetus to orientation research: It became possible to measure the directional tendencies of caged migrants, which allowed a systematic analysis of migratory orientation in the laboratory. At the same time, the vanishing bearings of displaced birds were found to be closely related to the home direction, which opened up new possibilities in pigeon homing.Kramer, who had described the sun compass as the first known orientation mechanism in birds, also contributed substantially to the theoretical framework of orientation by his map and compass-concept which states that an external reference system — a compass — is always involved in determining the home direction.The following period of experimental analysis began with a controversis on the role of the sun. Experimental evidence did not support sun navigation, but rather indicated that the sun was used as a compass. The analysis of the birds' orientation system during the last 30 years led to a fairly good understanding of migratory orientation. The processes of homing, however, are still not well understood. Many of the old concepts and new ones like olfactory orientation have been discussed, without any one hypothesis being able to explain all known phenomena. Recent findings suggest that there may not be one simple answer to the question of how birds navigate, as the birds' navigational system turns out to be redundant and highly variable.

     

Herbicide resistance in a mutant of the microalga Bumilleriopsis filiformis

A DCMU* (diuron)-resistant algal mutant was selected and characterized. Chlorophyll content, growth, and photosystem-I activity are as in the wild-type. Growth in liquid medium with 3 M DCMU present is half of the control. Apparently only the herbicide-binding site is affected within the redox chain. In contrast to the wild-type, trypsin treatment of isolated chloroplast material completely abolishes photosynthetic electron transport inhibition by DCMU or atrazine.DCMU resistance of chloroplasts is accompanies by tolerance to triazinones and phenylpyridazinones, but not to symmetric triazines. Sensitivity to diphenylethers, DBMIB or o-phenanthroline is not altered.Data on this algal mutant combined with those from triazine-resistant mutants of higher plants give direct evidence of overlapping binding sites at a (hypothetical) binding protein located at the reducing side of photosytem II.     

Zur Entwicklung der Sonnenkompa?orientierung bei jungen Brieftauben

Zusammenfassung Um mit Hilfe der Sonne Kompaßrichtungen zu bestimmen, muß man die tägliche Sonnenwanderung verrechnen können. Darauf beruht der übliche Nachweis des Sonnenkompasses durch Verstellung der inneren Uhr. Die Beziehung von Sonnenazimut, Tageszeit und geographischer Richtung ist jedoch von der geographischen Breite abhängig und ändert sich mit der Jahreszeit. Die Kenntnis davon, auf der die Kompensation der Sonnenwanderung beruht, wird durch Erfahrung erworben. Die entsprechenden Lernvorgänge finden statt, sobald die jungen Vögel Flugerfahrung erwerben; dabei muß die Sonne zu verschiedenen Tageszeiten beobachtet werden, wobei das Magnetfeld als Richtungsreferenzsystem für die Sonnenbewegung dienen kann.Um die Natur der Lernvorgänge näher zu bestimmen, wurden Tauben für ein bis zwei Wochen in einem Magnetschlag angesiedelt; dort konnten sie von einer Voliere aus die Sonne nur in einer geänderten Richtungsbeziehung zum Magnetfeld sehen. Erwachsene Tauben zeigten sich von dieser Behandlung bei anschließenden Auflassungen unbeeinflußt; junge Tauben in dem Alter, in dem sich der Sonnenkompaß entwickelt, zeigten daraufhin eine Abweichung in der Richtung, in der das Magnetfeld gedreht gewesen war. Dies sprach für eine Beeinflussung des Sonnenkompasses durch die Behandlung; der Unterschied zwischen erwachsenen und jungen Tauben läßt sich im Sinne einer sensiblen Phase deuten. Eine Versuchsserie, in der erwachsene Tauben die innere Uhr um 6 h nachverstellt bekamen und längere Zeit unter dieser Bedingung gehalten wurden, machte deutlich, daß der einmal gelernte Verrechnungsmechanismus für die Sonnenwanderung nicht unveränderlich ist, sondern den geänderten Bedingungen angepaßt werden konnte.Damit zeigte sich der Sonnenkompaß als flexibler Mechanismus, der sich wohl nicht nur auf die Änderungen der Sonnenbahn im Laufe der Jahreszeiten einstellen kann, sondern auch auf die erheblich größeren Unterschiede, die Zugvögel zwischen Brutgebiet und Winterquartier erleben. Die Lernvorgänge, die zum Sonnenkompaß führen, werden im Vergleich mit dem Erlernen des Sternkompaß und der Navigationskarte diskutiert: Sie haben durch die sensible Phase teilweise prägungsähnlichen Charakter, wobei es möglich erscheint, daß die Entwicklung des jeweiligen Orientierungsmechanismus als solcher zu einem bestimmten Zeitpunkt abgeschlossen ist. Die spezifische Reaktion auf die Außenfaktoren wird aber weiterhin durch Erfahrung kontrolliert und kann sich gegebenenfalls geänderten Umweltbedingungen anpassen.

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The development of sun compass orientation in young homing pigeons

Summary To use the sun for direction finding, the birds must compensate for the sun's apparent movement in the course of the day. A method of demonstrating the use of the sun compass is based on shifting the bird's internal clock, which results in a typical deviation of their vanishing bearings (Fig. 1). The specific relation between sun azimut, time and geographic direction depends on geographic latitude (Fig. 2) and varies in the course of the seasons (Fig. 3). The knowledge of this relationship which is the basis for compensation of the sun's movements, is aquired by experience (Fig. 4). The respective learning processes take place when the young birds obtain some flying experience; they must observe the sun during the various times of the day. The magnetic field can serve as a reference system to judge the sun's position.To analyse the nature of these learning processes, young pigeons were moved for one to two weeks into a small loft (Fig. 5) surrounded by Helmholtz coils to alter the ambient magnetic field. From an aviary, the birds saw the sun in an abnormal directional relationship to the magnetic field. In the following releases, old, experienced pigeons were not affected by this treatment. Young birds of the age when the sun compass normally develops, however, showed significant deviations to the direction to which magnetic north had been turned (Fig. 6, 7). This difference between young and adult pigeons suggests a sensitive period for the development of the sun compass. A series of experiments in which adult pigeons were clockshifted and kept under these conditions for more than two months (Fig. 8) clearly demonstrated that the compensation mechanisms for the sun's movements, once learned, are not fixed, but can be adapted to altered situations (Fig. 9, 10).Thus the sun compass proved to be a flexible mechanism that can be adjusted not only to the changes in the sun's arc in the course of the year, but also to the greater changes experienced by migratory birds between breeding ground and wintering area. The processes leading to the establishment of the sun compass and possible similarities to the development of the star compass and the navigational map are discussed: All three mechanisms seem to be based on learning processes that are in part imprinting-like, involving a sensitive period where the mechanisms per se have to be established. The specific reaction to the external factors, however, is not fixed, but can be adapted to the changes in the environment.

     

Pigeon homing: Does initial orientation include a ‘preferred compass direction’?

Summary To find out whether the initial orientation of pigeons is affected by a spontaneous directional tendency, as postulated by Wallraff's (1974, 1978, 1982) hypothesis, experienced birds were released at test sites distributed symmetrically around their loft. — The length of the mean vectors of the single releases, the deviations from the home direction, the homeward components as well as the homing speed did not show a correlation with the geographic position of the home direction. Summarizing four sites each on 21 experimental circles, we frequently obtained significant compass vectors, but they varied in direction between 115° ESE and 351° N, depending on what sites had been used, and did not indicate a uniform trend.A preferred compass direction as an integrated part of pigeon navigation, being the reason for the frequently observed deviations from the home direction, could not be confirmed. — The problematic nature of simply pooling the data of several symmetrically distributed test sites and calling any resulting significant vector a preferred compass direction is discussed, together with other possible reasons for asymmetrical distributions of release site biases.Abbreviation PCD preferred compass direction     

Novel Potential Interacting Partners of Fibronectin in Spontaneous Animal Model of Interstitial Cystitis

Feline idiopathic cystitis (FIC) is the only spontaneous animal model for human interstitial cystitis (IC), as both possess a distinctive chronical and relapsing character. Underlying pathomechanisms of both diseases are not clearly established yet. We recently detected increased urine fibronectin levels in FIC cases. The purpose of this study was to gain further insight into the pathogenesis by assessing interacting partners of fibronectin in urine of FIC affected cats. Several candidate proteins were identified via immunoprecipitation and mass spectrometry. Considerable changes in FIC conditions compared to physiological expression of co-purified proteins were detected by Western blot and immunohistochemistry. Compared to controls, complement C4a and thioredoxin were present in higher levels in urine of FIC patients whereas loss of signal intensity was detected in FIC affected tissue. Galectin-7 was exclusively detected in urine of FIC cats, pointing to an important role of this molecule in FIC pathogenesis. Moderate physiological signal intensity of galectin-7 in transitional epithelium shifted to distinct expression in transitional epithelium under pathophysiological conditions. I-FABP expression was reduced in urine and urinary bladder tissue of FIC cats. Additionally, transduction molecules of thioredoxin, NF-κB p65 and p38 MAPK, were examined. In FIC affected tissue, colocalization of thioredoxin and NF-κB p65 could be demonstrated compared to absent coexpression of thioredoxin and p38 MAPK. These considerable changes in expression level and pattern point to an important role for co-purified proteins of fibronectin and thioredoxin-regulated signal transduction pathways in FIC pathogenesis. These results could provide a promising starting point for novel therapeutic approaches in the future.     

Magnetic Compass of Birds Is Based on a Molecule with Optimal Directional Sensitivity

The avian magnetic compass has been well characterized in behavioral tests: it is an “inclination compass” based on the inclination of the field lines rather than on the polarity, and its operation requires short-wavelength light. The “radical pair” model suggests that these properties reflect the use of specialized photopigments in the primary process of magnetoreception; it has recently been supported by experimental evidence indicating a role of magnetically sensitive radical-pair processes in the avian magnetic compass. In a multidisciplinary approach subjecting migratory birds to oscillating fields and using their orientation responses as a criterion for unhindered magnetoreception, we identify key features of the underlying receptor molecules. Our observation of resonance effects at specific frequencies, combined with new theoretical considerations and calculations, indicate that birds use a radical pair with special properties that is optimally designed as a receptor in a biological compass. This radical pair design might be realized by cryptochrome photoreceptors if paired with molecular oxygen as a reaction partner.     

ENVIRONMENTAL AND GENETIC CONTROL OF BRAIN AND SONG STRUCTURE IN THE ZEBRA FINCH

Birdsong is a classic example of a learned trait with cultural inheritance, with selection acting on trait expression. To understand how song responds to selection, it is vital to determine the extent to which variation in song learning and neuroanatomy is attributable to genetic variation, environmental conditions, or their interactions. Using a partial cross fostering design with an experimental stressor, we quantified the heritability of song structure and key brain nuclei in the song control system of the zebra finch and the genotype‐by‐environment (G × E) interactions. Neuroanatomy and song structure both showed low levels of heritability and are unlikely to be under selection as indicators of genetic quality. HVC, in particular, was almost entirely under environmental control. G × E interaction was important for brain development and may provide a mechanism by which additive genetic variation is maintained, which in turn may promote sexual selection through female choice. Our study suggests that selection may act on the genes determining vocal learning, rather than directly on the underlying neuroanatomy, and emphasizes the fundamental importance of environmental conditions for vocal learning and neural development in songbirds.     

The relevance of the phosphatidylinositolphosphat-binding motif FRRGT of Atg18 and Atg21 for the Cvt pathway and autophagy

Atg18 and Atg21 are homologous S. cerevisiae autophagy proteins. Atg18 is essential for biogenesis of Cvt vesicles and autophagosomes, while Atg21 is only essential for Cvt vesicle formation. We found that mutated Atg18-(FTTGT), which lost almost completely its binding to PtdIns3P and PtdIns(3,5)P(2), is non-functional during the Cvt pathway but active during autophagy and pexophagy. Since the Cvt pathway does not depend on PtdIns(3,5)P(2), we conclude that the Cvt pathway requires binding of Atg18 to PtdIns3P. Mutated Atg21-(FTTGT) is inactive during the Cvt pathway but showed only partly reduced binding to PtdIns-phosphates, suggesting further lipid binding domains in Atg21. GFP-Atg18-(FTTGT) and Atg21-(FTTGT)-GFP are released from vacuolar punctae to the cytosol.     

Specific localisation of gap junction protein connexin 32 in the gastric mucosa of horses

In the glandular stomach, gap junctional intercellular communication (GJIC) plays an important role in the gastric mucosal defense system, and loss of GJIC is associated with ulcer formation. In spite of the high incidence of gastric ulcers in horses, particularly at pars nonglandularis, the presence of gap junctions in the equine stomach has not yet been studied. The objective was to obtain basic data on the distribution of gap junction protein connexin 32 (Cx32) in the different regions of normal equine gastric mucosa. Samples of mucosa were taken from seven horses at cardiac, fundic, and pyloric region and pars nonglandularis. To detect Cx32, immunohistochemical staining and Western blot analysis were performed. Corresponding mRNA was shown by RT-PCR and localised in tissue sections by in situ hybridisation. Cx32 was found in the glandular regions, whereas it was not detectable in squamous mucosa. Within the glandular epithelium, Cx32 was abundant in surface and foveolar cells and decreased towards the proliferative zone of the glands. These results suggest that gap junctions develop during the maturation of surface cells. Whether the lack of Cx32 at pars nonglandularis contributes to its susceptibility for developing ulcers, has to be further elucidated.