Phenolic and mineral content of leaves influences decomposition in European forest ecosystems

Summary Factors influencing decomposition in European forests growing on different soils were studied in stands dominated by the European beechFagus sylvatica L. Phenolic contents of freshly fallen leaves ofF. sylvatica growing on nutrient-poor soils (acid sandy soil) were higher than those of similar leaves on nutrient-rich soils (calcareous mull soil). Analysis of fallen leaves of different ages showed rapid decay of phenolics during the first winter on the ground. After 1 year the phenolic content of leaves ofF. sylvatica growing on nutrient-poor soils was still twice as high as in similar leaves on nutrient-rich soils. Field and laboratory experiments showed that a major decomposer (Oniscus asellus, Isopoda) preferred leaves from trees on nutrient-rich soils. Mineral contents of leaves ofF. sylvatica growing on different soils differed: on rich soils leaves had higher contents of Ca, Mg, Na, and K. These elements are important nutrients for decomposers. The distribution of major decomposers reflects the mineral content of their diet, which in turn reflects soil type. Different rates of leaf turnover and nutrient turnover in different forest ecosystems (even when the same tree species is dominant) are due to the decomposing system, which is influenced by the phenolic and mineral contents of the leaves.     

Reactions of the fauna on the bark of trees to the frequency of fires in a North American savanna

Summary The arthropod communities living on the bark of the oak species Quercus macrocarpa and Q. ellipsoidalis were investigated in a North American oak savanna. Differences were found in the community structure of the arthropods living on the bark of these two tree species, although they have the same fissured bark type. In the North American oak savanna ecosystem the most important disturbance factor is fire, which maintains species richness. Highest numbers of species and specimens were found at moderately disturbed sites. Three main ecological groups of arthropods living on the bark of trees can be distinguished in relation to the degree of disturbance: (1) Inhabitants of bark of trees restricted to undisturbed sites: they do not occur in fire-disturbed areas; (2) Inhabitants of bark of trees adapted to a moderate degree of disturbance: many species occur in high numbers only in moderately disturbed areas; and (3) Specialist inhabitants of bark of trees in heavily disturbed areas. The number of specimens of these species increases per trunk with the frequency of disturbance.     

Solitary Song and its inhibition in some Estrildidae

Summary In the species studied song appears to have two functions; an epigamic function = Display Song, and a contact function = Solitary Song. Solitary Song appears to be common to all the species studied. Its utterance indicates that the bird is unpaired or separated from another individual with which it has formed a bond. InUraeginthus bengalus, U. angolensis, andAmandava amandava Solitary Song is also uttered by the hen in similar circumstances. InLonchura punctulata, A. amandava, andEuodice malabarica song is usually but not completely inhibited by the presence of a mate, in whose absence Solitary Song will be uttered even when other individuals of the same species are present. In the species studied of the generaEstrilda, Lagonosticta, andUraeginthus Solitary Song is inhibited by the continued close proximity of another bird even though this may be of the same sex or of a different species and may elicit aggressive or fleeing reactions; but conditions of close association with a bird other than a suitable mate would presumably only occur under captive conditions. There appears to be a distance factor controlling such inhibition. There is evidence of the inhibition of song due to the presence of a mate in other passerine species.     

Familientradition in der Gesangsentwicklung des Gimpels(Pyrrhula pyrrhula L.)

Zusammenfassung Der heranwachsende Junggimpel empfängt während seiner Nestlingszeit und den sich anschließenden Wochen bis zum Erlangen der Selbständigkeit von den Eltern Eindrücke, die sein späteres Geschlechtsverhalten und seine stimmliche Entwicklung entscheidend beeinflussen. Ein normales Geschlechtsverhalten entwickelt sich nur dann, wenn der Jungvogel von den eigenen Eltern oder Artgenossen aufgezogen wird. Erfolgt die Aufzucht durch andere Lebewesen (Kanarienvogel, Mensch), so tritt eine mehr oder weniger deutliche Prägung der sozialen und sexuellen Reaktion auf diese Arten ein. Mit dieser Prägung geht eine Fixation der Lautäußerungen (Lockruf, Gesang) an die der Eltern — vor allem des Vaters — Hand in Hand. Trägt der Vater normale Lockrufe und den arttypischen Gesang vor, so erfährt auch der Junggimpel eine ormale stimmliche Entwicklung. Sind aber Lockrufe und Gesang in Klangfarbe und Komposition abweichend, so lernt der Jungvogel selektiv alle diese Abweichungen und behält sie zeitlebens bei. Ein Jungmännchen, das von Kanarien aufgezogen wurde, erlernte unter einer Schar anderer Junggimpel den Gesang des einzigen anwesenden Kanarienmännchens und gab ihn an seine Söhne weiter. Vier Jahre später sangen die Urenkel dieses Vogels noch die Kanarienstrophen in unveränderter Form. — Von Menschen aufgezogene Gimpel konzentrieren ihren Lerneifer auf die Lautäußerungen des Pflegers; sie erlernen vorgepfiffene Melodien: bis zu drei kurze Volkslieder. Während die jungen Männchen ausschließlich dem Gesang des Vaters ihre Aufmerksamkeit zuwenden, nehmen die Weibchen nach ihrer Verpaarung neben den vom Vater erlernten Motiven auch solche aus dem Gesang des Gatten auf. Nur der erste Partner hat auf ihre Gesanganusbildung Einfluß.Die sensible Periode der stimmlichen Entwicklung fällt mit der Zeit zusammen, in der frühsexuelle Stimmungen den Junggimpel beherrschen. Sein Lerneifer ist auf dasjenige Lebewesen konzentriert, das ihn aufzog und dem er — aus dem daraus erwachsenen hohen Grade persönlicher Bindung heraus — seine ersten sexuellen Anträge machte.     

A somatic cell hybrid map of the long arm of human chromosome 17, containing the familial breast cancer locus (BRCA1).

We describe a detailed somatic cell hybrid map of human chromosome 17q11.2-q23, containing the familial breast and ovarian cancer locus (BRCA1) and highly informative closely linked markers. An X-irradiation panel of 38 hamster/human and mouse/human hybrids with fragments of chromosome 17 was generated and characterized with 22 STS markers from this chromosome. A detailed map of 61 probes onto chromosome 17q, subdividing the chromosome arm into 25 regions, was done by using a panel of hybrids with well-defined breakpoints and nine chromosome-mediated gene transfectants. Our localization of RARA, TOP2, EDH17B1 and 2, and possibly WNT3, between THRA1 and D17S181, two markers known to flank BRCA1, suggests that any of these is a potential candidate for the BRCA1 locus. The marker D17S579 (Mfd188), which is believed to be very close to BRCA1, maps closest to the EDH17B genes.     

Anaerobic dissimilatory phosphite oxidation,an extremely efficient concept of microbial electron economy

Phosphite is a stable phosphorus compound that, together with phosphate, made up a substantial part of the total phosphorus content of the prebiotic Earth's crust. Oxidation of phosphite to phosphate releases electrons at an unusually low redox potential (−690 mV at pH 7.0). Numerous aerobic and anaerobic bacteria use phosphite as a phosphorus source and oxidise it to phosphate for synthesis of nucleotides and other phosphorus-containing cell constituents. Only two pure cultures of strictly anaerobic bacteria have been isolated so far that use phosphite as an electron donor in their energy metabolism, the Gram-positive Phosphitispora fastidiosa and the Gram-negative Desulfotignum phosphitoxidans. The key enzyme of this metabolism is an NAD⁺-dependent phosphite dehydrogenase enzyme that phosphorylates AMP to ADP. These phosphorylating phosphite dehydrogenases were found to be related to nucleoside diphosphate sugar epimerases. The produced NADH is channelled into autotrophic CO₂ fixation via the Wood-Ljungdahl (CO-DH) pathway, thus allowing for nearly complete assimilation of the substrate electrons into bacterial biomass. This extremely efficient type of electron flow connects energy and carbon metabolism directly through NADH and might have been important in the early evolution of life when phosphite was easily available on Earth.     

Occurrence of α-acetolactate decarboxylases among lactic acid bacteria and their utilization for maturation of beer

Summary Acetolactate decarboxylase activity has been detected among three genera, nine species and 263 strains of lactic acid bacteria tested in the course of a screening for acetolactate decarboxylases amenable for use in brewing as maturation aid. Streptococcus diacetylactis strain FD-64-D was found to generate a decarboxylase exhibiting a satisfactory activity and an excellent stability at the pH prevailing in beer and wort. This decarboxylase could not be solubilized but enzymatically active, freeze-dried cells were effective for satisfactory flavour maturation of beer although difficulties were encountered during attempts to remove the applied cell material by filtration of the beer. Lactobacillus casei DSM 2547 was likewise found to produce a decarboxylase exhibiting a satisfactory activity and stability at the low pH of beer and which, in addition, was readily solubilized. A method has been developed for pilot scale production of preparations of this decarboxylase suitable for use in brewing.Abbreviations DSM Deutsche Sammlung von Microorganismen - EDTA Ethylene diaminetetra-acetic acid