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Ohne Zusammenfassung     

Versuche über Photoperiodismus II

Zusammenfassung Je 3 Klone von amerikanischen und europäischen Rebensorten, 4F ₁-Klone aus Kreuzungen zwischen Amerikaner- und Europäer-Reben sowie 1F ₁-Klon zwischen zwei Amerikaner-Reben wurden auf ihr Verhalten bei Normal- und Kurztag geprüft.Alle Pflanzen zeigten bei Kurztag ein geringeres vegetatives Wachstum, stärkere Wurzelbildung, bessere Holzreife und einen früheren Vegetationsabschluß als bei Normaltag.In bezug auf die Formgestaltung des Blattes ließen sich bei Tagesverkürzung auf 12 Stunden starke Unterschiede feststellen.Die Reaktion auf Tagesverkürzung ist am stärksten ausgeprägt bei den Amerikaner-Sorten, am wenigsten bei den Europäern. DieF ₁-Klone verhalten sich in den meisten Merkmalen intermediär.Demnach sind die amerikanischen Rebensorten Riparia 72 G, Rupestris 59 G und Solonis Trier als Kurztagpflanzen zu bezeichnen, während die europäischen Sorten Riesling, Gutedel und Silvaner sich mehr dem tagneutralen Typ nähern.Das intermediäre Verhalten derF ₁-Klone zeigt, daß eine Vererbung der verschiedenen Reaktionsweisen stattfindet.Die Versuche werden in ihrer Bedeutung für die Züchtung, die Ampelographie und die Anzuchttechnik besprochen.     

Cytologie und Vererbung bei den Lupinenarten

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Preferences of group-housed female mice regarding structure of softwood bedding

Bedding influences various parameters in the housing of laboratory mice, such as health, physiology and behaviour (often considered as being integral parts of welfare). Notwithstanding existent studies about bedding preferences of individually tested mice, data about group-housed mice are still lacking. The aim of this study was to find out the structure preference for softwood bedding of group-housed mice. One hundred and eight 8-week-old female mice (C57BL6/JOlaHsd and BALB/cOlaHsd) were housed in groups of three and were given one-week free access to two different bedding structures at a time. In three test combinations, softwood shaving bedding was tested versus softwood chip bedding products of three different particle sizes (fine/medium/coarse-grained). The preference test was performed in a DoubleCage system composed of two Makrolon type IIL cages, connected by a perspex tunnel. This validated system was able to detect the crossings of each individual animal with correct crossing time and direction. On the basis of these data, dwelling times on the particular bedding structures were statistically analysed as a parameter for bedding preferences. In all three test combinations, a highly significant shaving preference was detected. On average, mice spent 70% of their dwelling time on the shavings. This preference was more explicit during the light period and in C57BL/6J mice. The relative ranking of the bedding structures was: shavings > coarse-grained chips > medium chips = fine chips. By means of these results, a shaving structure as bedding can be recommended for laboratory mice, whereas fine chip structures should be avoided.     

Impact of environmental enrichment in mice. 1: effect of housing conditions on body weight,organ weights and haematology in different strains

Currently, environmental enrichment is a very common means of improving animal well-being, especially for laboratory animals. Although environmental enrichment seems to be a possible way for improving the well-being of animals, the consideration of housing laboratory animals should not only focus solely on animal well-being, manpower and economics but also on the precision and accuracy of the experimental results. The purpose of the present study was to evaluate the effects of enriched cages (nest box, nesting material, climbing bar) on body weight, haematological data and final organ weights. BALB/c, C57BL/6 and A/J mice, originated from Harlan Winkelmann, were used for the experiments - 16 animals of each strain. Animals at 3 weeks of age were marked and separated randomly to enriched or non-enriched cages, in groups of four, half for each housing condition. Both cages were type III Makrolon cages, only the enriched cages contained a nest box, a wood bar for climbing and nesting material. Animals were kept in a clean animal room under specific pathogen free (SPF) conditions. Body weights were recorded every week. Blood samples were collected at 14 weeks of age (white blood cells (WBC), red blood cells (RBC), haemoglobin (HGB), and haematocrit (HCT) were analysed). At 15 weeks of age, the animals were euthanized by CO(2) in their home cages, and final body weight and organ weights (heart, liver, kidney, adrenal, spleen and uterus) were recorded immediately. Although nearly all the test variables were not affected by environmental enrichment in their mean values, the enriched group showed higher coefficients of variation in many variables, and strain differences of both housing conditions were not consistent. The influences of enrichment were shown to be strain- and test-dependent. Such effects may lead to an increase in the number of animals which is necessary or may change the experimental results, especially when a study, using enriched housing conditions, focuses on strain differences. Since the same enrichment design can result in different influences, a positive or a negative or no adverse effect, due to the strain and the variables studied, researchers need to collect more information before enrichment designs are introduced into experimental plans.     

The effects of different rack systems on the breeding performance of DBA/2 mice

Housing systems for laboratory animals have been developed over a long time. Micro-environmental systems such as positive, individually ventilated caging systems and forced-air-ventilated systems are increasingly used by many researchers to reduce cross contamination between cages. There have been many investigations of the impact of these systems on the health of animals, the light intensity, the relative humidity and temperature of cages, the concentration of ammonia and CO(2), and other factors in the cages. The aim of the present study was to compare the effects of different rack systems and to understand the influence of environmental enrichment on the breeding performance of mice. Sixty DBA/2 breeding pairs were used for this experiment. Animals were kept in three rack systems: a ventilated cabinet, a normal open rack and an individually ventilated cage rack (IVC rack) with enriched or non-enriched type II elongated Makrolon cages. Reproduction performance was recorded from 10 to 40 weeks of age. In all three rack systems there was a similar breeding index (pups/dam/week) in non-enriched groups during the long-term breeding period, but the coefficients of variation in the IVC rack were higher for most parameters. This type of enrichment seems to lead to a decrease in the number of pups born, especially in the IVC group. However, there was no significant difference in breeding index (young weaned/female/week).     

Blood pressure in rats: a comparison of a multifactorial experimental design to measurements in an outbred stock

Systolic blood pressure was measured in males of 8 inbred strains and 1 outbred stock of rats 5 times over a period of 20 min on 5 consecutive days. The strain means ranged between 107.9 mmHg and 149.3 mmHg. The estimated variance between strains (V = 248.7 mmHg) was about 5 times higher than the variance within strains (V = 54.3 mmHg). The intraindividual variance within strains was relatively constant (V = 24.0-37.6 mmHg), while the interindividual variance varied to a great extent (V = 4.5-44.5 mmHg) from strain to strain. The outbred stock showed values of blood pressure and components of variance similar to those of a single inbred strain. Thus, by investigation of a battery of 8 inbred strains in a multifactorial experimental design a greater phenotypic variability due to genetic strain differences is achieved than by measurements in a single outbred stock.     

Referate

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