Die Auswirkung der Übungsverteilung auf das Lernen und Vergessen bei Carassius auratus auratus Linné3

The significance of massed and distributed practice in discrimination learning to criterion by goldfish was studied. All animals were trained to discriminate between 6 horizontal black and white stripes (positive stimulus) and 2 vertical black and white stripes (negative stimulus). 5 groups of animals, 12 Ss each, got different training programs. Groups varied in number of trials per day (30, 10, 5 successive trials) and in distribution of trials over the day (30 trials given in blocks of 5 with ITI of 1 h or 5 trials, each spaced by an ITI of 1 h). In general animals with a small number of massed trials/day were superior in early acquisition period. When trials/day were spaced the method proved to be more efficient. The training method showed no effect concerning retention.     

Ein neues germacren-derivat sowie ein diterpenmalonat aus Baccharis-arten

The investigation of the aerial part of B. scandens afforded a new ketone, a germacrene derivative. The aerial parts of B. tricuneata var. lineata yielded, in addition to known ent-clerodane derivatives, a malonate of a further diterpene of this type. The structures are elucidated by spectroscopic methods.     

Neue germacranolide und andere inhaltsstoffe aus vertretern der subtribus gochnatiinae

The investigation of three further species belonging to the subtribe Gochnatiinae, tribe Mutisieae, afforded in addition to known compounds two new eudesmane derivatives and two new germacranolides, closely related to albicolide and salonitenolide. The structures are elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic aspects are discussed briefly.     

Neue C10-säureamide,furanoeremophilane und andere inhaltsstoffe aus bolivianischen Senecio-arten

The investigation of seven Bolivian Senecio species afforded in addition to known compounds five new furanoeremophilanes, two C₁₀-amides, a new isoeugenol ester and the isomer of pterophorin. The structures are elucidated mainly by spectroscopic methods. While most of the new compounds are closely related to those isolated before from Senecio species, four of them are unusual. Another is a new type of a furanoeremophilane; its biogenesis however, can be explained easily from known types.     

Testing hypotheses about the function of repeated nest abandonment as a life history strategy in a passerine bird

Nest structures are essential for successful reproduction in most bird species. Nest construction costs time and energy, and most bird species typically build one nest per breeding attempt. Some species, however, build more than one nest, and the reason for this behaviour is often unclear. In the Grey Fantail Rhipidura albiscapa, nest abandonment before egg‐laying is very common. Fantails will build up to seven nests within a breeding season, and pairs abandon up to 71% of their nests before egg‐laying. We describe multiple nest‐building behaviour in the Grey Fantail and test four hypotheses explaining nest abandonment in this species: cryptic depredation, destruction of nests during storm events, and two anti‐predatory responses (construction of decoy nests to confuse predators, and increasing concealment to ‘hide’ nests more effectively). We found support for only one hypothesis – that abandonment is related to nest concealment. Abandoned nests were significantly less concealed than nests that received eggs. Most abandoned nests were not completely built and none received eggs, thus ruling out cryptic predation. Nests were not more likely to be abandoned following storm events. The decoy nest hypothesis was refuted as abandoned nests were constructed at any point during the breeding season and some nests were dismantled and the material used to build the subsequent nest. Thus, Grey Fantails are flexible about nest‐site locations during the nest‐building phase and readily abandon nest locations if they are found to have deficient security.     

Growth and protection against oxidative stress in young clones and mature spruce trees (Picea abies L.) at high altitudes

Clones of Norway spruce (Picea abies L.) were grown for several years on an altitudinal gradient (1750 m, 1150 m and 800 m above sea level) to study the effects of environmental × genetic interactions on growth and foliar metabolites (protein, pigments, antioxidants). Clones at the tree line showed 4.3-fold lower growth rates and contained 60% less chlorophyll (per gram of dry matter) than those at valley level. The extent of growth reduction was clone-dependent. The mortality of the clones was low and not altitude-dependent. At valley level, but not at high altitude, needles of mature spruce trees showed lower pigment and protein concentrations than clones. In general, antioxidative systems in needles of the mature trees and young clones did not increase with increasing altitude. Needles of all trees at high altitude showed higher concentrations of dehydroascorbate than at lower altitudes, indicating higher oxidative stress. In one clone, previously identified as sensitive to acute ozone doses, this increase was significantly higher and the growth reduction was stronger than in the other genotypes. This clone also displayed a significant reduction in glutathione reductase activity at high altitude. These results suggest that induction of antioxidative systems is apparently not a general prerequisite to cope with altitude in clones whose mother plants originated from higher altitudes (about 650–1100 m above sea level, Hercycnic-Carpathian distribution area), but that the genetic constitution for maintenance of high antioxidative protection is important for stress compensation at the tree line. Received: 13 October 1998 / Accepted: 22 June 1999     

Das Archaeon Nitrososphaera viennensis

Unkown heroes in the global nitrogen cycle – Nitrososphaera viennensis Ammonia oxidizing archaea exist everywhere in Nature, but have only been discovered about 10 years ago. Today they are recognized as one of the most abundant microbial guilds, in particular because they constitute up to 30% of the marine picoplankton in the oceans and are found in high numbers in soils. The global nitrogen cycle is heavily impacted due to intensified agricultural practice. Important steps therein, like nitrification, are exclusively performed by microorganisms. Therefore, it has become increasingly important to investigate ammonia oxidizing archaea, who participate in this step. Since these archaea are difficult to cultivate, their wide distribution and importance has only been recently recognized with the help of molecular techniques. Now, first isolates, like the type strain Nitrososphaera viennensis, which was isolated from a garden soil in Vienna allow their closer investigation. This might eventually help to find measures for the mitigation of nitrogen and greenhouse gas emissions from soils.     

Prasugrel suppresses development of lithium-induced nephrogenic diabetes insipidus in mice

Previously, we localized ADP-activated P2Y₁₂ receptor (R) in rodent kidney and showed that its blockade by clopidogrel bisulfate (CLPD) attenuates lithium (Li)-induced nephrogenic diabetes insipidus (NDI). Here, we evaluated the effect of prasugrel (PRSG) administration on Li-induced NDI in mice. Both CLPD and PRSG belong to the thienopyridine class of ADP receptor antagonists. Groups of age-matched adult male B6D2 mice (N = 5/group) were fed either regular rodent chow (CNT), or with added LiCl (40 mmol/kg chow) or PRSG in drinking water (10 mg/kg bw/day) or a combination of LiCl and PRSG for 14 days and then euthanized. Water intake and urine output were determined and blood and kidney tissues were collected and analyzed. PRSG administration completely suppressed Li-induced polydipsia and polyuria and significantly prevented Li-induced decreases in AQP2 protein abundance in renal cortex and medulla. However, PRSG either alone or in combination with Li did not have a significant effect on the protein abundances of NKCC2 or NCC in the cortex and/or medulla. Immunofluorescence microscopy revealed that PRSG administration prevented Li-induced alterations in cellular disposition of AQP2 protein in medullary collecting ducts. Serum Li, Na, and osmolality were not affected by the administration of PRSG. Similar to CLPD, PRSG administration had no effect on Li-induced increase in urinary Na excretion. However, unlike CLPD, PRSG did not augment Li-induced increase in urinary arginine vasopressin (AVP) excretion. Taken together, these data suggest that the pharmacological inhibition of P2Y₁₂-R by the thienopyridine group of drugs may potentially offer therapeutic benefits in Li-induced NDI.