Activity-stimulating phenomena caused by field-disturbance in the use of pitfall-traps

Summary The influence of several mechanical field disturbances, when using pitfall-traps for activity determinations, is analysed. The disturbances result in higher catches of surface-dwelling Collembola; the animals being stimulated to higher locomotory activity.The disturbance by walking in the field results in a multiple of the control catch. This effect lasts for about 1 hour.The digging-in effect lasts for about two days but more or less different for the various species. The cause is sought in the CO₂ production in the soil, which is considerable after soil disturbances. The reaction of Collembola to rather high CO₂ concentrations in the air results in an increase of the locomotory activity.Another interpretation, namely attraction to CO₂ sources, could not be demonstrated.

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Zusammenfassung Der Einfluß verschiedener mechanischer Störungen im Feld bei der Anwendung der Fallenfangmethode wurde analysiert. Die Störungen stimulieren die Tiere zu größerer lokomotorischer Aktivität, wodurch sich höhere Fangtotale von epedaphischen Collembolen ergeben.Die Störung, welche durch vielfältiges Herumlaufen im Fangterrain entsteht, ergibt Fangtotale, die um ein Vielfaches höher sind als die Kontrollfänge. Dieser Effekt hält eine Stunde an.Eine andere Störung entsteht durch das Eingraben der Fallen. Es resultiert ebenfalls in eine höhere Anzahl gefangener Tiere. Dieser Effekt aber dauert etwa zwei Tage. Die Ursache liegt vermutlich in der Zunahme der CO₂-Produktion im Boden als Folge des Eingrabens. Erhöhte CO₂-Konzentration in der Luft resultiert tatsächlich in einer Zunahme der lokomotorischen Aktivität.Attraktion durch die CO₂-Quelle konnte nicht nachgewiesen werden.

     

Successful in vitro fertilization and generation of transgenics in Black and Tan Brachyury (BTBR) mice

The Black and Tan Brachyury (BTBR) mouse strain is a valuable model for the study of long-term complications from obesity-induced type 2 diabetes mellitus and autism spectrum disorder. Due to technical difficulties with assisted reproduction, genetically modified animals on this background have previously been generated through extensive backcrossing, which is expensive and time-consuming. We successfully generated two separate transgenic mouse lines after direct zygote microinjection into this background strain. Additionally, we developed in vitro fertilization (IVF) methods for the BTBR mouse. We found low rates of fertilization and implantation in this strain, and identified the BTBR oocyte as the primary culprit of low success with BTBR IVF. We achieved an increase in live born pups from 5.9 to 35.6 % with IVF in the BTBR strain by use of BTBR females at a younger age (18–25 days), collection of oocytes 15–17 h after superovulation, and the use of supplemented fertilization media. This method eliminates the need for time consuming assisted embryo manipulations that are otherwise required for success with BTBR oocytes. This advancement provides an exciting opportunity to directly generate BTBR transgenics and gene-edited mice using both traditional and emerging genomic editing techniques, such as CRISPR/Cas9. These methods also allow effective colony preservation and rederivation with these strains. To our knowledge, this is the first report describing embryo manipulations in BTBR mice.     

Matrix metalloproteinase‐3 in the central nervous system: a look on the bright side

Matrix metalloproteinases (MMPs) are a large family of proteases involved in many cell‐matrix and cell‐cell signalling processes through activation, inactivation or release of extracellular matrix (ECM) and non‐ECM molecules, such as growth factors and receptors. Uncontrolled MMP activities underlie the pathophysiology of many disorders. Also matrix metalloproteinase‐3 (MMP‐3) or stromelysin‐1 contributes to several pathologies, such as cancer, asthma and rheumatoid arthritis, and has also been associated with neurodegenerative diseases like Alzheimer's disease, Parkinson's disease and multiple sclerosis. However, based on defined MMP spatiotemporal expression patterns, the identification of novel candidate molecular targets and in vitro and in vivo studies, a beneficial role for MMPs in CNS physiology and recovery is emerging. The main purpose of this review is to shed light on the recently identified roles of MMP‐3 in normal brain development and in plasticity and regeneration after CNS injury and disease. As such, MMP‐3 is correlated with neuronal migration and neurite outgrowth and guidance in the developing CNS and contributes to synaptic plasticity and learning in the adult CNS. Moreover, a strict spatiotemporal MMP‐3 up‐regulation in the injured or diseased CNS might support remyelination and neuroprotection, as well as genesis and migration of stem cells in the damaged brain.     

Nitrogen metabolite repression of arginase,ornithine transaminase and allantoinase in a conditional ethionine-resistant mutant of Saccharomyces cerevisiae with low activity of catabolic NAD-specific glutamate dehydrogenase

Antonie van Leeuwenhoek -