Formation and development of a group of juvenileHylobates Iar

Three young gibbons, who had minimal previous social contact with each other, were released together in a semi-natural environment. The individual and social behavior of the gibbons paralleled that of gibbons in the wild: of the total daytime, 71% was spent in foraging activities, 20% in social interaction, and 9% in inactivity.The tendency toward group formation proved strong in these gibbons; they were together an average of 68% of the time following their release. Group maintenance seemed based on a sharing of the dominance role for various activities, either equally among the three or in the form of a pair (the male and one of the females) being co-dominant. The male and small female became gradually isolated from the large female. Reciprocal initiation of sexual exploration and play were related to this pairing.The results of discrete activity observations by the simple method of simultaneously recording geographical location and activity of each gibbon, plus the continuous observation of social behavior, were remarkably consistent with gibbon observational data in an artificial setting and those obtained in long-term field investigations. In addition, the methodology permitted an analysis of some of the finer aspects of social behavior.     

Genetische Untersuchungen an dem Basidiomyceten Agrocybe aegerita

Zusammenfassung Der holzzerstörende Pilz Agrocybe aegcrita (Agaricaceae) kann leicht unter Laborbedingungen angezogen und zur Fruchtkörperbildung gebracht werden. Sein Fortpflanzungsverhalten wird durch den tetrapolaren Mechanismus der homogeniscben Incompatibilität kontrolliert und sein vollständiger Entwicklungszyklus dauert etwa 6 Wochen. Dagegen können dikaryotische Myzelien schon nach 3 Wochen Fruchtkörper bilden. Da es möglich ist, die Basidiosporen (10×6 m) mit der Hand zu isolieren, eignet sich dieser Pilz sehr gut für genetische Untersuchungen, die sowohl als Zufallsanalyse als auch mit Hilfe der Tetradenanalyse durchgeführt werden können. Wir waren daher in der Lage, die Formalgenetik dieses Pilzes auszuarbeiten.Innerhalb der monokaryotischen Nachkommenschaft eines Dikaryons, das aus der Natur isoliert wurde, fanden wir eine beträchtliche Variabilität hinsichtlich der Fruchtkörperbildung nach Kreuzung dieser Stämme. Neben relativ frühen Fruchtern (<28 d) kam es in einigen Kombinationen selbst nach 42 d nicht zur Fruktifikation trotz verträglicher Incompatibilitätsfaktoren. Um dieses Phänomen zu quantifizieren, haben wir für die Monokaryen den Parameter Fruchtungspotenz entwickelt, in den als einzige Variable der Zeitpunkt der Fruchtkörperbildung nach Herstellung eines Dikaryons eingeht. Eine ähnliche Variabilität wurde für das sogenannte monokaryotische Fruchten (die Fähigkeit von Monokaryen, auch ohne compatiblen Kreuzungspartner zu fruktifizieren) entdeckt. Drei Typen dieses qualitativen Merkmals wurden identifiziert : Monokaryotische Fruchter, Nicht-Fruchter und Nicht-Fruchter mit Fruchtkörperanlagen. Die ersteren bilden zwar normal aussehende Fruchtkörper, die jedoch wesentlich kleiner sind als die an Dikaryen entstehenden und meist nur Basidien mit zwei Sporen haben.Da Agrocybe aegerita zu den Speisepilzen gehört, haben wir versucht, ihre Fruchtkörperproduktion zu verbessern, um auf diese Weise ein Material für eine praktische Nutzung zu erhalten. Als Beispiel für eine konzertierte Züchtung wurde das Kriterium der Fruchtungspotenz ausgewählt. Ausgehend von einem aus der Natur isolierten Fruchtkörper war es möglich, in nur 4 Generationen durch Selektion und Rekombination in einer Inzuchtpopulation die Fruchtungspotenz merklich zu steigern.In einer parallelen Versuchsreihe haben wir — gewissermaßen als Kontrolle — gezeigt, daß es unter Anwendung der gleichen Methodik möglich ist, auch das konträre Züchtungsziel zu erreichen, nämlich eine Abnahme der Fruchtungspotenz.Es ist damit klar geworden, daß A. aegerita als ein geeignetes Objekt für züchterische Versuche angesehen werden kann. Darüber hinaus haben wir jedoch bei der Auswertung dieser Versuche eine statistisch signifikante Korrelation zwischen Fruchtungspotenz und monokaryotischem Fruchten entdeckt. Die Bedeutung dieser Erscheinung für ein Verständnis der genetischen Kontrolle der Fruchtkörpermorphogenese und damit für die Grundlagenforschung liegt auf der Hand.Der Aufenthalt von M. Semerdieva wurde durch ein Stipendium der Heinrich-Hertz-Stiftung, Düsseldorf, ermöglicht. Die Experimente wurden durch Sachmittel der Deutschen Forschungsgemeinschaft und des Landesamtes für Forschung unterstützt. Wir danken diesen Institutionen. Unser Dank gilt auch den technischen Mitarbeitern unseres Lehrstuhls, insbesondere Frau M. Kuglmeier, für ihre Hilfe.

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Investigations on the genetics of the basidiomycete Agrncybe aegerita I. A correlation between the time of fruiting body production and monokaryotic fruiting and its importance for breeding and morphogenesis

Summary The wood-inhabiting Basidiomycete Agrocybe aegerita (Agaricaceae) can be easily grown under laboratory conditions. Its complete life cycle requires about 6 weeks, while dikaryons are able to form fruiting bodies within 3 weeks. Since the basidiospores (10×6 m) can be isolated by hand, this organism is very well suited for genetic studies either by single strand or tetrad analysis. Thus we were able to work out the formal genetics of A. aegerita, the mating relations of which are controlled by the tetrapolar mechanism of homogenic incompatibility.Within the monokaryotic offspring of a dikaryon isolated from nature we found a considerable variation in the time of fruiting in compatible matings, some failed to fruit even after 42 d. In order to quantify this criterion, we have developed for monokaryotic strains the parameter fruiting potency, in which the only variable is the time required for fruiting body production in the resulting dikaryotic stocks.Similar variability has been found for the ability of monokaryons to show monokaryotic fruiting. Three types of this qualitative criterion have been identified : non-fruiters, non-fruiters with fruiting body initials, and monokaryotic fruiters. The latter produce small fruiting bodies, the basidia of which predominantly carry only two spores.Since Agrocybe aegerita belongs to the edible mushrooms, we have attempted to improve fruiting body production in order to obtain material for use in commercial production. As a selected example for concerted breeding we have used the criterion of fruiting potency starting from a single fruiting body. We were able to show that by selection and recombination within a small inbreeding population, in only four generations the fruiting potency could be markedly enhanced. In a parallel set of experiments as a control, we also showed that the opposite effect, a decrease in fruiting potency, could be achieved in only three generations. It became evident that A. aegerita is very well suited to applied research with respect to breeding for commercial use. In evaluating these data we have found a statistically significant correlation between fruiting potency and monokaryotic fruiting. The implications of the latter for the general understanding of genetic control of morphogenesis becomes evident.

     

Monocytes in Kaposi's sarcoma lesions are productively infected by human herpesvirus 8.

PCR analysis and serological studies demonstrated a close association between Kaposi's sarcoma (KS)-associated herpesvirus, or human herpesvirus 8 (HHV-8), and the development of Kaposi's sarcoma (KS). The majority of the KS cells were shown to be latently infected by the virus. In this study we investigated which type of cell is productively infected in KS lesions. In situ hybridization was performed with strand-specific RNA probes complementary to the sequences coding for the minor capsid protein (VP23) of HHV-8. The VP23 gene is specifically expressed during the lytic or replicative period of the virus life cycle, and therefore it is a useful marker to detect productively infected cells. By in situ hybridization of KS lesions, a strong hybridization signal was detected only in a small subset of the KS cells of the lesions. Simultaneous application of immunohistochemical staining and in situ hybridization identified the virus-replicating cells to be of monocytic origin. Productively infected monocytes may be an important reservoir for transmission of the virus and for the increase and maintenance of the high load of HHV-8 generally observed in nodular KS lesions during late stages of infection.     

Discrimination of sinusoidally frequency-modulated sound signals mimicking species-specific communication calls in the FM-bat Phyllostomus discolor

In the lesser spear-nosed bat, Phyllostomus discolor, maternal directive calls are characterized by an individual type of sinusoidal frequency modulation (= SFM) pattern. Beside modulation frequency, modulation depth, carrier frequency, and number of modulation cycles per call contribute to the mother's vocal signature. Since juvenile P. discolor learn to adapt their isolation calls to the corresponding call characteristics of the own mother or even to playback of a computer-stored directive call, if hand-reared in the absence of conspecifics, the bats' auditory system ought to be able to resolve interindividual differences in communication call structure. However, quantitative psychoacoustic data on the discrimination of SFM signals in this species are not available. Thus, in the present study, lesser spear-nosed bats were trained in a two-alternative forced-choice procedure to discriminate between two alternatingly presented SFM sound signals differing in modulation frequency. Other characteristics of acoustic stimuli were identical and designed to mimick the fundamental of species-specific calls. By gradually reducing the difference in modulation frequency between both stimuli within the behavioural relevant range until the animals' performance dropped below the 75%-correct level, a considerable auditory spectro-temporal resolution has been revealed. Particularly in comparison to the overall interindividual variation of this call parameter (minimal modulation frequency = 49 Hz, maximum = 100 Hz), the determined average difference limen for modulation frequency of 2.42 ± 0.29 Hz seems substantial and sufficient for labelling individuals. Accepted: 30 November 1996     

Thermal unfolding and aggregation of human complement protein C9: a differential scanning calorimetry study

The thermotropic behavior of purified human complement protein C9 was investigated by high-sensitivity differential scanning calorimetry. When dissolved in physiological buffers (pH 7.2, 150 mM NaCl), C9 underwent three endothermic transitions with transition temperatures (Tm) centered at about 32, 48, and 53 degrees C, respectively, and one exothermic transition above 64 degrees C that correlated with protein aggregation. The associated calorimetric enthalpies of the three endothermic transitions were about 45, 60, and 161 kcal/mol with cooperative ratios (delta Hcal/delta HvH) close to unity. The total calorimetric enthalphy for the unfolding process was in the range of 260-280 kcal/mol under all conditions. The exothermic aggregation temperature was strongly pH dependent, changing from 60 degrees C at pH 6.6 to 81.4 degrees C at pH 8.0, whereas none of the three endothermic transitions was significantly affected by pH changes. They were, however, sensitive to addition of calcium ions; most affected was Tm1 which shifted from 32 to 35.8 degrees C in the presence of 3 mM calcium, i.e., the normal blood concentration. Kosmotropic ions stabilized the protein by shifting the endothermic transitions to slightly higher temperatures whereas inclusion of chaotropic ions (such as choline), removal of bound calcium by addition of EDTA, or proteolysis with thrombin lowered the transition temperatures. Previous studies had indicated the formation of at least three different forms of C9 during membrane insertion or during heat polymerization, and it is suggested that the three endothermic transitions reflect the formation of such C9 conformers. Choline, which is present at high concentrations on the surface of biological membranes, and calcium ions have the ability to shift the transition temperatures of the first two transitions to be either close to or below body temperature. Thus, it is very likely that C9 is present in vivo in a partially unfolded state when bound to a membrane surface, and we propose that this facilitates membrane insertion and refolding of the protein into an amphiphilic conformation.     

PET1402, a nuclear gene required for proteolytic processing of cytochrome oxidase subunit 2 in yeast

The nuclear mutation pet ts1402 prevents proteolytic processing of the precursor of cytochrome oxidase subunit 2 (cox2) in Saccharomyces cerevisiae. The structural gene PET1402 was isolated by genetic complementation of the temperature-sensitive mutation. DNA sequence analysis identified a 1206-bp open reading frame, which is located 215 by upstream of the PET122 gene. The DNA sequence of PET1402 predicts a hydrophobic, integral membrane protein with four transmembrane segments and a typical mitochondrial targeting sequence. Weak sequence similarity was found to two bacterial proteins of unknown function. Haploid cells containing a null allelle of PET1402 are respiratory deficient.     

Inhibitors of mitochondrial function prevent senescence in the ascomycetePodospora anserina

Summary The onset of senescence, i.e. decrease of growth rate followed by cellular death, is prevented when inhibitors of mitochondrial function (ethidiumbromide, streptomycin, tiamulin) are present in the culture medium. If mycelia are transferred to a medium not containing one of these substances, senescence occurs after the usual time interval (30 d at 26° C). Inhibitors of cytoplasmic protein synthesis such as emetine and cycloheximide have no effect in preventing senescence.