The role of indoleacetaldehyde in IAA production from tryptophan by plants and by their epiphytic bacteria

Tryptophan, tryptamine, or indolepyruvic acid were applied to 2 systems: a bacterial (pea stem sections containing the epiphytic bacteria) and a plant system (pea stem sections under sterile conditions). In the plant system, the production of indoleacetic acid and indoleethanol (tryptophol) from each applied indole derivative is clearly reduced by the aldehyde reagents bisulfite and dimedon, respectively. Indoleacetaldehyde is chromatographically detected after alkaline liberation from its bisulfite addition product. In the bacterial system, the production of indoleacetic acid and indoleethanol is likewise reduced by bisulfite and dimedon. However, after tryptophan or tryptamine application, we could not detect indoleacetaldehyde in the described way. In one case only, namely tryptamine application to the bacterial system, indoleethanol production (contrary to indoleacetic acid production) is scarcely reduced by the aldehyde reagents. This indicates a bacterial pathway tryptamine → indoleethanol which bypasses indoleacetaldehyde.     

The fine structure of the terminal segment of the bovine seminiferous tubule

Summary The intratesticular excurrent duct system of the bull is composed of rete testis, tubuli recti, and the terminal segment of the seminiferous tubules. Each terminal segment is surrounded by a vascular plexus and may be subdivided into a transitional region, middle portion, and terminal plug. The modified supporting cells of the middle portion and the terminal plug no longer display the typical Sertoli-Sertoli junctions seen in the transitional region and the seminiferous tubule proper. In the region of the terminal plug a distinct central lumen is generally not observed: spermatozoa and tubular fluid must pass through an intricate system of communicating clefts between the apices of the closely attached modified supporting cells. Vacuoles in the supranuclear region of the cells in the middle portion indicate strong transepithelial fluid transport. In analogy to the epithelium of rete testis and tubuli recti, the supporting cells of the terminal segment are capable of phagocytosing spermatozoa. The vascular plexus investing the terminal segment serves a dual purpose: it is a regulatory device for fluid and sperm transport, as well as an area of increased diapedesis for white blood cells.Supported by a grant from the Deutsche Forschungsgemeinschaft     

Darwin's ‘mystery of mysteries’: the role of sexual selection in plant speciation

Sexual selection is considered one of the key processes that contribute to the emergence of new species. While the connection between sexual selection and speciation has been supported by comparative studies, the mechanisms that mediate this connection remain unresolved, especially in plants. Similarly, it is not clear how speciation processes within plant populations translate into large-scale speciation dynamics. Here, we review the mechanisms through which sexual selection, pollination, and mate choice unfold and interact, and how they may ultimately produce reproductive isolation in plants. We also overview reproductive strategies that might influence sexual selection in plants and illustrate how functional traits might connect speciation at the population level (population differentiation, evolution of reproductive barriers; i.e. microevolution) with evolution above the species level (macroevolution). We also identify outstanding questions in the field, and suitable data and tools for their resolution. Altogether, this effort motivates further research focused on plants, which might potentially broaden our general understanding of speciation by sexual selection, a major concept in evolutionary biology.     

Naturally occurring monoterpenoids in needles of Picea abies (L.) Karst

Summary An analysis was made of the effects of different sampling and extraction techniques on the amounts and pattern of monoterpenoids isolated from needles of Norway spruce. The following isolation and analysis procedure was finally adopted: liquid nitrogen-cooled needles were pulverized by a microdismembrator, extracted with pentane overnight at 2°–3°C and concentrated to a volume not less than 3 ml/g fresh weight on a Vigreux column. The crude extract was injected splitless (with solvent split) onto a cold programmed temperature vaporized (PTV) precolumn of a gas chromatograph and the vaporizable compounds heated to a capillary column. This method was tested for production of artefacts and quantitative extraction and applied to needles of eleven 80-year-old spruce trees.     

Basement membrane deposition of nidogen 1 but not nidogen 2 requires the nidogen binding module of the laminin gamma1 chain

The nidogen-laminin interaction is proposed to play a key role in basement membrane (BM) assembly. However, though there are similarities, the phenotypes in mice lacking nidogen 1 and 2 (nidogen double null) differ to those of mice lacking the nidogen binding module (γ1III4) of the laminin γ1 chain. This indicates different cell- and tissue-specific functions for nidogens and their interaction with laminin and poses the question of whether the phenotypes in nidogen double null mice are caused by the loss of the laminin-nidogen interaction or rather by other unknown nidogen functions. To investigate this, we analyzed BMs, in particular those in the skin of mice lacking the nidogen binding module. In contrast to nidogen double null mice, all skin BMs in γ1III4-deficient mice appeared normal. Furthermore, although nidogen 1 deposition was strongly reduced, nidogen 2 appeared unchanged. Mice with additional deletion of the laminin γ3 chain, which contains a γ1-like nidogen binding module, showed a further reduction of nidogen 1 in the dermoepidermal BM; however, this again did not affect nidogen 2. This demonstrates that in vivo only nidogen 1 deposition is critically dependent on the nidogen binding modules of the laminin γ1 and γ3 chains, whereas nidogen 2 is independently recruited either by binding to an alternative site on laminin or to other BM proteins.     

Zum Einflu? einer Autobahn im Bau und w?hrend des Betriebs auf die Brutbiologie von Kohlmeisen (Parus major) und Blaumeisen (P. caeruleus)

Zusammenfassung Im Februar 1992 wurde an der in Bau befindlichen Autobahn BAB 66 zwischen Steinau und Schlüchtern (5021'N, 0931'E) ein Nistkastenkontrollgebiet mit 310 Nistkästen eingerichtet, um die Auswirkungen der Autobahn vor und nach Inbetriebnahme auf die Brutbiologie von Meisen zu untersuchen. Als Vergleichsgebiete dienen ein direkt benachbartes sowie ein ca. 5 km entferntes Untersuchungsgebiet. Zum Vergleich der Gewichtsentwicklung der Nestlinge wurde ein drittes autobahnfernes Gebiet herangezogen.In einzelnen Jahren finden sich zwischen den Gebieten Unterschiede in der Zusammensetzung der Brutpopulation, der Besetzungsrate der Nistkästen, dem Legebeginn, der Gelegegröße, der Schlüpfrate oder im Bruterfolg. Diese Unterschiede treten in verschiedenen Jahren und in unterschiedlichen Gebieten auf, so daß sich keine generelle Abweichung des Gebietes an der Autobahn von den straßenfernen Gebieten feststellen läßt. Die Eröffnung der Autobahn hatte keinen Effekt auf die untersuchten Parameter.Die Gewichte der Nestlinge im Gebiet an der Autobahn waren im Jahr 1996 nur am 12. und 13. Nestlingstag signifikant geringer als die Gewichte der Nestlinge in einem autobahnfernen gleichartig strukturierten Biotop. Die Ausflugsgewichte der Jungvögel an der A66 liegen jedoch ca. 2 g höher als in städtischen Biotopen.Störungen durch den Straßenverkehr, wie sie von anderen Autoren berichtet werden, ließen sich in unserem Untersuchungsgebiet nicht feststellen. In diesem Zusammenhang werden die geringe Störungsempfindlichkeit der Kohl- und Blaumeisen sowie der bisher geringe Verkehr auf der Autobahn diskutiert.

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The impact of a motorway in construction and after opening to traffic on the breeding biology of Great Tit (Parus major) and Blue Tit (P. caeruleus)

Summary In February 1992, a study area (A 66) with 310 nestboxes was installed along the construction line of a four laned motorway between Steinau and Schlüchtern (5021'N, 0931'E). One area in the immediate neighbourhood (VG1) and one 5 km distant (VG2) from the study area at the motorway (see Fig. 1) served as controls for comparison. In all three areas, the nestboxes were checked weekly during the breeding season from the beginning of May until July. Species composition of the birds using nestboxes, rate of occupation of nestboxes, and, for Great Tits (Parus major) and Blue Tits (P. caeruleus), date of the first egg, clutch size, hatching rate and number of birds fledged were recorded. The study included 5 breeding seasons from 1992 to 1996, 3 years during the period of construction and 2 years after the opening of the motorway to traffic in December 1994. In 1996, the nestling weight of 20 broods of Great Tits at the A66 was recorded daily and compared with that of all nestlings in another study area (VG3, see Fig. 1).The data were analyzed separately for each year. Distributions of frequencies were analyzed with the x² test, the other data with the Kruskal-Wallis-Test (H-Test). In case of significant differences between the study areas, the Mann Whitney U-test was used to determine which study area differed from the others. Nestlings bodymass was compared using the t-test.The species composition was similar in all three areas (Fig. 2), and it did not change after the opening of the motorway to traffic. The rate of occupation of the nestboxes, dates of laying of the first egg, clutch size, hatching rate and breeding success vary between years and between study areas (Table 1 to 5); data that differ significantly from those of two other areas are indicated by bold print. Such differences were observed in various years and involved all three areas. In study area A66, clutch size of Great Tits was higher in 1993; hatching success of Great Tits was lower in 1994 and that of Blue Tits was lower in 1993. However, there was no general trend that area A66 at the motorway was different from the other areas, either before or after being opened to the traffic. The weight of nestlings in study area A66 at the motorway was similar to that in comparable area nearby; only on day 12 and 13 after hatching was it slightly lower (Tab. 6). The last measurement on day 15 indicates a nestling weight of 16.2 g for the area at the motorway, which is in normal for deciduous forest habitats and approximately 2 g higher than that recorded in urban habitats.In brief, the motorway did not affect the species composition, rate of occupied nestboxes or the various breeding parameters; in particular, the moving traffic after opening did not seem to have any effect. The breeding parameters from the study area at the motorway were typical for the Schlüchtern region. Density reductions in breeding populations, as discussed by several authors, or disturbances caused by moving traffic, as previously reported, were not observed in our study. However, our key species, Great Tits and Blue Tits, are not generally very sensitive to interferences. Also, the level of traffic on the motorway was still rather low. This must be considered when our findings are generalized.

     

Determinants of Brushite Stone Formation: A Case-Control Study

Purpose

The occurrence of brushite stones has increased during recent years. However, the pathogenic factors driving the development of brushite stones remain unclear.

Methods

Twenty-eight brushite stone formers and 28 age-, sex- and BMI-matched healthy individuals were enrolled in this case-control study. Anthropometric, clinical, 24 h urinary parameters and dietary intake from 7-day weighed food records were assessed.

Results

Pure brushite stones were present in 46% of patients, while calcium oxalate was the major secondary stone component. Urinary pH and oxalate excretion were significantly higher, whereas urinary citrate was lower in patients as compared to healthy controls. Despite lower dietary intake, urinary calcium excretion was significantly higher in brushite stone patients. Binary logistic regression analysis revealed pH>6.50 (OR 7.296; p = 0.035), calcium>6.40 mmol/24 h (OR 25.213; p = 0.001) and citrate excretion <2.600 mmol/24 h (OR 15.352; p = 0.005) as urinary risk factors for brushite stone formation. A total of 56% of patients exhibited distal renal tubular acidosis (dRTA). Urinary pH, calcium and citrate excretion did not significantly differ between patients with or without dRTA.

Conclusions

Hypercalciuria, a diminished citrate excretion and an elevated pH turned out to be the major urinary determinants of brushite stone formation. Interestingly, urinary phosphate was not associated with urolithiasis. The increased urinary oxalate excretion, possibly due to decreased calcium intake, promotes the risk of mixed stone formation with calcium oxalate. Neither dietary factors nor dRTA can account as cause for hypercalciuria, higher urinary pH and diminished citrate excretion. Further research is needed to define the role of dRTA in brushite stone formation and to evaluate the hypothesis of an acquired acidification defect.     

Re-interpreting the role of endo-��-mannanases as mannan endotransglycosylase/hydrolases in the plant cell wall

Background

Mannans are hemicellulosic polysaccharides in the plant primary cell wall with two major physiological roles: as storage polysaccharides that provide energy for the growing seedling; and as structural components of the hemicellulose–cellulose network with a similar function to xyloglucans. Endo-β-mannanases are hydrolytic enzymes that cleave the mannan backbone. They are active during seed germination and during processes of growth or senescence. The recent discovery that endo-β-mannanase LeMAN4a from ripe tomato fruit also has mannan transglycosylase activity requires the role of endo-β-mannanases to be reinterpreted.

Aims

In this review, the role of endo-β-mannanases as mannan endotransglycosylase/hydrolases (MTHs) in remodelling the plant cell wall is considered by analogy to the role of xyloglucan endotransglucosylase/hydrolases (XTHs). The current understanding of the reaction mechanism of these enzymes, their three-dimensional protein structure, their substrates and their genes are reported.

Future outlook

There are likely to be more endohydrolases within the plant cell wall that can carry out hydrolysis and transglycosylation reactions. The challenge will be to demonstrate that the transglycosylation activities shown in vitro also exist in vivo and to validate a role for transglycosylation reactions during the growth and development of the plant cell wall.Key words: Cell wall, endo-β-mannanase, endohydrolase, mannan, endotransglycosylase     

99mTc-Labeled HYNIC-DAPI Causes Plasmid DNA Damage with High Efficiency

^99mTc is the standard radionuclide used for nuclear medicine imaging. In addition to gamma irradiation, ^99mTc emits low-energy Auger and conversion electrons that deposit their energy within nanometers of the decay site. To study the potential for DNA damage, direct DNA binding is required. Plasmid DNA enables the investigation of the unprotected interactions between molecules and DNA that result in single-strand breaks (SSBs) or double-strand breaks (DSBs); the resulting DNA fragments can be separated by gel electrophoresis and quantified by fluorescent staining. This study aimed to compare the plasmid DNA damage potential of a ^99mTc-labeled HYNIC-DAPI compound with that of ^99mTc pertechnetate (^99mTcO₄⁻). pUC19 plasmid DNA was irradiated for 2 or 24 hours. Direct and radical-induced DNA damage were evaluated in the presence or absence of the radical scavenger DMSO. For both compounds, an increase in applied activity enhanced plasmid DNA damage, which was evidenced by an increase in the open circular and linear DNA fractions and a reduction in the supercoiled DNA fraction. The number of SSBs elicited by ^99mTc-HYNIC-DAPI (1.03) was twice that caused by ^99mTcO₄⁻ (0.51), and the number of DSBs increased fivefold in the ^99mTc-HYNIC-DAPI-treated sample compared with the ^99mTcO₄⁻ treated sample (0.02 to 0.10). In the presence of DMSO, the numbers of SSBs and DSBs decreased to 0.03 and 0.00, respectively, in the ^99mTcO₄^– treated samples, whereas the numbers of SSBs and DSBs were slightly reduced to 0.95 and 0.06, respectively, in the ^99mTc-HYNIC-DAPI-treated samples. These results indicated that ^99mTc-HYNIC-DAPI induced SSBs and DSBs via a direct interaction of the ^99mTc-labeled compound with DNA. In contrast to these results, ^99mTcO₄⁻ induced SSBs via radical formation, and DSBs were formed by two nearby SSBs. The biological effectiveness of ^99mTc-HYNIC-DAPI increased by approximately 4-fold in terms of inducing SSBs and by approximately 10-fold in terms of inducing DSBs.     

Die Sonnenorientierung der V?gel. II. Entwicklung des Sonnenkompa? und sein Stellenwert im Orientierungssystem

Zusammenfassung Die vorliegende Arbeit versucht, die Sonnenorientierung der Vögel in ihrer Funktionsweise, ontogenetischen Entwicklung und biologischen Bedeutung nach dem heutigen Wissensstand darzustellen. Theoretisch kann die Sonne zur Bestimmung der Heimrichtung ( navigation), zum Aufsuchen einer als Kompaßrichtung bekannten Richtung und zum Einhalten der Richtung benutzt werden. Die meisten vorliegenden Befunde sprechen gegen eine Rolle der Sonne bei der Bestimmung der Heimrichtung nach Verfrachtung; die Funktion der Sonne als Sonnenkompaß und beim Richtungseinhalten ist dagegen durch zahlreiche Versuche bei verschiedenen Vogelarten gut belegt.Beim Aufsuchen einer Richtung mit dem Sonnenkompaß verrechnet der Vogel die Bewegung der Sonne auf ihrer scheinbaren Bahn, d. h. er schlägt einen tageszeitlich variablen Winkel zur Sonne ein, um in eine konstante Richtung zu fliegen. Dieser Winkel hängt allein von der inneren Uhr ab. Dabei scheint der Vogel im allgemeinen zu berücksichtigen, daß die Azimutwinkelgeschwindigkeit der Sonne gegen Mittag erheblich größer ist als in den frühen Vormittags- und späten Nachmittagsstunden.Untersuchungen bei Tauben ergaben, daß der Sonnenkompaß ein erlernter Orientierungsmechanismus ist: Sonnenazimut, Zeit und geographische Richtung werden aufgrund von Erfahrung miteinander in Beziehung gesetzt. Dabei muß die junge Taube die Sonne zu verschiedenen Tageszeiten beobachten, um den Sonnenkompaß während des ganzen Tages benutzen zu können. Der Zeitpunkt, zu dem der Sonnenkompaß gelernt wird, hängt stark von der Flugerfahrung der Tauben ab; er scheint sich zu entwickeln, sobald die Notwendigkeit, sich zu orientieren, auftritt, was normalerweise etwa gegen Ende des 3. Lebensmonats der Fall sein dürfte. Die Grundlagen und näheren Umstände des Lernprozesses sind noch weitgehend unbekannt.Versuche mit jungen Tauben sprechen dafür, daß der Sonnenkompaß bei der Entwicklung der Navigationsfähigkeit keine Rolle spielt; er scheint quasi nachträglich in das fertige Navigationssystem eingebaut zu werden. Dann aber stellt der Sonnenkompaß beim Heimfinden das bevorzugt benutzte Kompaßsystem dar, solange die Sonne zu sehen ist. Bei bedecktem Himmel kann er allerdings durch ein gleich leistungsfähiges nicht-visuelles System ersetzt werden.Bei tagziehenden jungen Zugvögeln — finnischen Staren — ließ sich eine Orientierung nach dem Sonnenkompaß noch nicht während des ersten Herbstzuges, sondern erst während des folgenden Frühjahrszuges nachweisen; allerdings ist unklar, inwieweit diese an handaufgezogenen Vögeln gewonnenen Befunde die natürlichen Verhältnisse widerspiegeln. Eine realistische Abschätzung der Bedeutung des Sonnenkompaß bei der Zugorientierung ist heute noch nicht möglich; theoretische überlegungen und die wenigen vorliegenden Befunde scheinen jedoch gegen eine Rolle des Sonnenkompaß als Referenzsystem für die angeborene Zugrichtung zu sprechen.

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The sun orientation of birds

Summary In the present paper (part I: J. Orn. 121: 121–143, 1980), the sun orientation of birds, its way of functioning, ontogenetic development, and biological significance are described in the light of current experimental evidence. Theoretically, the sun can be used to determine which compass direction is the home direction ( true navigation), to set a compass course, and to maintain a given direction during flight. Most of the available evidence speaks against the sun's being used for determining the home direction after displacement, whereas many findings in several species of birds demonstrate use of the sun as a sun compass and for maintaining directions.Using the sun compass to go in a constant direction, the birds compensate for the sun's apparent movement, i. e. they fly at angles to the sun's azimuth direction which vary according to the time of day. The magnitude of these angles seems to depend on the birds' internal clock only, and the birds apparently consider the different rates of change of the sun's azimuth during the day (greater around noon than in early morning or late afternoon).Experiments with young homing pigeons show that the sun compass is not a completely innate orientation mechanism, but that the relation between sun azimuth, time and geographic direction is learned. A young pigeon must experience the sun at different hours of the day to establish a sun compass for the entire day. The age at which the sun compass is learned strongly depends on the bird's flying experience. The sun compass seems to be developed as soon as the bird encountered the necessity of orienting, which normally will be about the end of its third month. The details of the learning process are not yet known.The sun does not seem to be necessary for the development of the ability to navigate; in fact, some findings with young pigeons seem to indicate that the navigational system is already developed before the sun compass is added to it. Afterwards, however, the sun compass is used preferentially whenever the sun is visible. Under overcast skies, it is replaced by an equally effective non-visual system.In day-migrating birds — young Finnish starlings — sun compass orientation could not be demonstrated during the first autumn migration period, but the starlings were shown to use it during the following spring period. It is not clear, though, whether these data from handraised birds reflect the natural situation correctly. The available evidence does not yet allow a realistic estimate of the significance of the sun compass for orientation during migration; theoretical considerations and the few present data, however, make it appear improbable that the sun compass acts as a reference system for the innate migratory direction.