Reproductive Behaviour in Zonocerus elegans (Orthoptera: Pyrgomorphidae) with Special Reference to Nuptial Gift Guarding

Egglaying aggregations, mate fidelity and male and female mate choice and mating behaviour of the African pyrgomorphid grasshopper Zonocerus elegans are described from the field. Several hundred males and females were individually marked at oviposition sites. Pairs remained stable over days, during egglaying and presumably also over the weeks prior to egglaying. In addition to long-term consorting with a female, males may try to obtain inseminations by “footpad”–tactics at oviposition sites. It is suggested that prolonged consorting and repeated copulations increase the female's reproductive output as well as the male's share in it. Our data and the literature indicate that males are involved not only in rival competition but also in a “battle of the sexes” which females are likely to win. The intra– and intersexual “war on two fronts” results behaviourally in elaborate mating tactics and anatomically in highly developed internal female genitalia and male copulatory organs (well known taxonomic characters). This applies not only to grasshoppers but also to other insects and arthropods.     

Localization of beta-glycerophosphatase and Mg++-activated adenosine triphosphatase in a moss haustorium,and the relation of these enzymes to the cell wall labyrinth

Summary Acid phosphatase and ATPase were localized in the bryophyte haustorium and in the surrounding paternal tissue of the gametophyte. Only cells with wall labyrinths are the sites of intense enzyme activity.The reaction products of both enzymes were found to occur in cell organelles, the plasma membrane and particularly in wall inclusions that are supposedly proteinaceous in nature.The intensity of the reaction is proportional to the state of differentiation of the labyrinth. The highest enzyme activity was encountered in the epidermal cells which are furnished with the most elaborate wall labyrinths. Somewhat lower was the activity in the other labyrinth cells with filiform ingrowths.These findings stress the role of the epidermis as an absorptive epithelium, and also show clearly that the enzyme activity associated with the plasma surface is in no reciprocal ratio to the degree of amplification of the surface area.     

Dorsiventralität der Statocyten in plagiogeotropen Seitenwurzeln von Lepidium sativum L.

Summary The calyptra of plagiotropic lateral roots of Lepidium sativum L. is composed of three rows of cells. Movable amyloplates, possibly functioning as statoliths, are located only a few central cells of the ontogenetic youngest cell row. Beside the lateral root axis the two innermost statocytes contain a stable complex of rough endoplasmic reticulum, which is preferentially located in the central distal cell corner. In the statocytes lying above the lateral root axis the amyloplasts are sedimented on the ER-complex during growth in direction of the geotropic liminal angle. In the statocyte below the axis the ER-complex is free of amyloplasts. Thus a dorsiventrality exists in the statocytes located above and below the root axis in regard to the arrangement of their organelles.

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Herrn Professor Dr. Maximilian Steiner zum 70. Geburtstag.     

Die Struktur der Hoch Endopolyploiden Kerne Im Endosperm von Zea Mays,Das Auffallende Verhalten Ihrer Nucleolen und Ihr Endopolyploidiegrad

Zusammenfassung Die endopolyploiden Kerne des Endosperms von Zea mays enthalten bei 3 eingehend und 10 stichprobenartig untersuchten Sippen durchgehend Chromatinstränge, die sich aus den perlschnurartig gebauten Endochromosomen zusammensetzen. Sie stehen zum Teil netzartig miteinander in Verbindung, so daß sie nicht individuell als Riesenchromosomen kenntlich sind. In ihren Verlauf schalten sich die endomitotisch herangewachsenen knobs in Form kompakter Endochromozentren oder±dichter Ansammlungen von Heterochromomeren ein.Die Endopolyploidisierung führt bei den drei Sippen WF 9, M 14 und WF 9 X M 14 und offenbar auch bei den zehn anderen bis zu 192-Ploidie, ausnahmsweise zu 384-Ploidie.Die Kerne von M 14 erscheinen bei höchstwahrscheinlich gleicher Polyploidiestufe im allgemeinen ärmer an Chromatin als die von WF 9, und auch innerhalb dieser Sippe gibt es analoge Schwankungen kleineren Ausmaßes. Sie beruhen vermutlich auf Spiralisierungseffekten.Sippenspezifische Unterschiede bestehen auch im Vorkommen von Sekundärnucleolen, kleineren Nucleolen, die dicht neben den Hauptnucleolen an den drei endo-nucleolar-organizing bodies entstehen und bei WF 9 häufiger, in höherer Zahl und größeren Dimensionen als bei M 14 auftreten. Bei der Sippe M 14 werden dagegen häufiger und gehäuft Vacuolen aus den Nucleolen ausgestoßen (=freie N.); auch finden sich reichlicher als bei WF 9 zusätzliche kleine Nucleolen in den Chromatinsträngen eingeschaltet oder an ihnen angeheftet (=festsitzende N.). Der Bastard nimmt bezüglich der Sekundärnucleolen eine Mittelstellung zwischen den Elternsippen ein; bezüglich der freien und festsitzenden Nucleolen verhält er sich ähnlich wie M 14, bezüglich der Protuberanzen ähnlich wie WF 9.Die verschiedenartigen Nucleolen—einschließlich der in Ausstoßung begriffenen Nucleolusvacuolen—enthalten RNS, was sich aus der Methylgrün-Pyroninfärbung, kombiniert mit Ribonuclease-Behandlung ergibt.

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The structure of the highly endopolyploid nuclei in the endosperm of Zea mays, their conspicuous nucleolar conditions and degree of endopolyploidy

Summary The endopolypoid nuclei in the endosperm of Zea mays (8 inbred lines and 5 hybrids, 2+1 were investigated intensively) throughout contain strands of chromatin, which are composed of endochromosomes having chromomeric constitution. Some of the strands join laterally and most of them cannot be recognized individually. Inserted within them are endopolyploid knobs of compact heterochromatin or assemblages of heterochromomeres.In the lines WF 9 and M 14, the hybrid WF 9 x M 14 and obviously in the others the largest nuclei are 192 n and exceptionally 384 n.Nuclei of M 14 most likely having the same degree of polyploidy as those of WF 9 seem to contain less chromatin and even within WF 9 there are similar variations; probably they result from different spiralization.The different lines also show specific differences concerning the secondary nucleoli; these are nucleoli developing with endopolyploidization side by side with the main nucleoli at the three endo-nucleolar-organizing-bodies; WF 9 shows them in more nuclei, in higher frequency and in larger dimensions than M 14. In M 14 on the contrary more vacuoles (=free nucleoli) are ejected from the nucleoli and this happens more often; small additional nucleoli are also more abundantly inserted in the chromatin-strands. The hybrid behaves intermediately concerning the secondary nucleoli, more like M 14 concerning inserted and free nucleoli and similar to WF 9 in expulsion of vacuoles.Staining with methylgreen-pyronin and treatment with ribonuclease show the different nucleoli including the ejected vacuoles to contain RNA.

     

A Cre transgene active in developing endodermal organs, heart, limb, and extra-ocular muscle

Cre-mediated recombination, a method widely used in mice for tissue-specific inactivation of endogenous genes or activation of transgenes, is critically dependent on the availability of mouse lines in which Cre recombinase functions in the tissue of interest or its progenitors. Here we describe a transgenic mouse line, Osr1-cre, in which Cre is active from embryonic day (E)11.5 in a few specific tissues. These include the endoderm of the posterior foregut, midgut, hindgut, and developing urogenital system, the heart left atrium, extra-ocular muscle progenitors, and mesenchyme in particular regions of the limb. Furthermore, starting at E12.5, Cre functions in limb interdigital mesenchyme. Within the urogenital system, recombination appears to be virtually complete in the epithelium of the bladder and urethra just posterior to it by E14.5. In males, some of these urethral cells form the prostate. The spatiotemporal pattern of Cre activity in Osr1-cre makes it a unique resource among the lines available for Cre-mediated recombination experiments.     

Phenotypic differences in behavior, physiology and neurochemistry between rats selected for tameness and for defensive aggression towards humans

To better understand the biology of tameness, i.e. tolerance of human presence and handling, we analyzed two lines of wild-derived rats (Rattus norvegicus) artificially selected for tameness and defensive aggression towards humans. In response to a gloved human hand, tame rats tolerated handling, whereas aggressive rats attacked. Cross-fostering showed that these behavioral differences are not caused by postnatal maternal effects. Tame rats were more active and explorative and exhibited fewer anxiety-related behaviors. They also had smaller adrenal glands, larger spleens and lower levels of serum corticosterone. Blood glucose levels were lower in tame rats, whereas the concentrations of nine amino acids were higher. In the brain, tame rats had lower serotonin and higher taurine levels than aggressive rats. Our findings reinforce the notion that tameness is correlated with differences in stress response and will facilitate future efforts to uncover the genetic basis for animal tameness.     

The strength of competition among individual trees and the biomass-density trajectories of the cohort

We simulated the self-thinning of Rhizophora mangle mangrove forests with the spatially explicit simulation model KiWi. This model is an application of the field-of-neighbourhood (FON) approach, which describes an individual tree by a competition function defined on the zone of influence (ZOI) around the stem. The FON causes growth depression of the trees involved. Sustained growth depression results in tree death. We propose a subdivision of the biomass density trajectories (bdt), obtained during the thinning process, into four segments related to characteristic shapes of the stem diameter distribution of the cohort. A positive skewness of the stem diameter distribution, indicating that the majority of the individuals are small and hindered in growth, is necessary for the occurrence of a linear segment within the bdt, the so-called 'self-thinning line'. This segment is the third bdt segment according to our classification. It is reached when the positive skewness of the stem diameter distribution is maximal and ends when the skewness reaches its second zero transition. The thinning line is therefore linked to the homogenisation process, which forces the symmetry of the stem distribution. We show that the ongoing search for a universal slope for the linear segment of the biomass-density trajectory (bdt) cannot succeed, since it is species-specific and may also be site-dependent. The slope increases with increasing competition strength of the individuals. Nevertheless, the lower limit of the slope is pre-defined by geometrical constraints and modified by the actual strength of the neighbourhood competition. Although the simulations were all carried out with growth parameters of the mangrove species Rhizophora mangle, our results should be qualitatively valid and form a plausible theoretical framework to account for different biomass-density trajectories.