Die Wirkung von Harnmarken auf Artgenossen beim Haushund

An 11 Versuchstagen wurden die Reaktionen von insgesamt 3 Rüden und 2 Hündinnen auf einem rund 2stündigen Spaziergang in nicht oder wenig bekanntem Gebiet beobachtet. Auf einem ersten Rundgang wurden die spontan abgegebenen Harnmarken eines Versuchstieres mit kleinen Objekten markiert, dann ein zweiter Hund an loser Leine den gleichen Weg (meist in umgekehrter Richtung) entlanggeführt und dessen Reaktionen auf die markierten Stellen registriert. Im ganzen wurden bei den ersten Rundgängen 261 Harnmarken abgesetzt. In 47,1 % der Fälle ging der im zweiten Rundgang vorbeigeführte Hund ohne ersichtlichen Grund an der Harnmarke vorbei. Bei Beachtung der Marken zeigten sich 6 verschiedene Reaktionen: 1. Beschnuppern, 2. Harnen über oder neben die Marke, 3. Scharren mit den Hinterpfoten nach Überharnen, 4. Belecken der Marke, 5. Knurren beim Scharren, 6. Zähneklappern nach Beschnuppern und Belecken. Die Marken von feindlichen Rüden und läufigen Hündinnen werden nach Beschnuppern signifikant häufiger als die eigenen bzw. diejenigen einer nichtläufigen Hündin mit einer weiteren Reaktion beantwortet. Die Marken nichtläufiger Hündinnen und die eigenen Marken ergaben keine unterschiedlichen Reaktionen beim Rüden. Eine Hündin reagiert auf die Marken eines (feindl.) Rüden nicht mehr als ein Rüde auf die eigenen Marken. Die Harnmarken vermitteln dem Hunderüden Informationen darüber, ob sie von einer läufigen Hündin, einem fremden Rüden oder von ihm selbst (bzw. einer nicht-läufigen Hündin) stammen.     

From Microscopic to Macroscopic Descriptions of Cell Migration on Growing Domains

Cell migration and growth are essential components of the development of multicellular organisms. The role of various cues in directing cell migration is widespread, in particular, the role of signals in the environment in the control of cell motility and directional guidance. In many cases, especially in developmental biology, growth of the domain also plays a large role in the distribution of cells and, in some cases, cell or signal distribution may actually drive domain growth. There is an almost ubiquitous use of partial differential equations (PDEs) for modelling the time evolution of cellular density and environmental cues. In the last 20 years, a lot of attention has been devoted to connecting macroscopic PDEs with more detailed microscopic models of cellular motility, including models of directional sensing and signal transduction pathways. However, domain growth is largely omitted in the literature. In this paper, individual-based models describing cell movement and domain growth are studied, and correspondence with a macroscopic-level PDE describing the evolution of cell density is demonstrated. The individual-based models are formulated in terms of random walkers on a lattice. Domain growth provides an extra mathematical challenge by making the lattice size variable over time. A reaction–diffusion master equation formalism is generalised to the case of growing lattices and used in the derivation of the macroscopic PDEs.     

Rapid Communication Chronic Ingestion of Ethanol Up-Regulates NMDAR1 Receptor Subunit Immunoreactivity in Rat Hippocampus

We examined the effects of chronic ethanol exposure on the levels of N -methyl-D-aspartate receptor subunit 1 (NMDAR1) protein, an essential component of N -methyl-D-aspar- tate glutamate receptors, in rat brain. By immunoblotting procedures using a specific antibody for the NMDAR1 subunit, we found that ethanol dramatically up-regulated (by 65%) NMDAR1 immunoreactivity in the hippocampus but not in the nucleus accumbens, cerebral cortex, or striatum. In contrast, ethanol did not alter the levels of glutamate receptor subunit (GLUR) 1 or GLUR2 protein, subunits that make up the α-amino-3-hydroxy-5-methy4-isoxazole propionic acid glutamate receptor, in the hippocampus. Because ethanol can potentially influence many different neurotransmitter systems, we examined whether chronic treatment with several psychotropic drugs with different pharmacological profiles (cocaine, haloperidol, SCH 23390, imipramine, and morphine) could mimic the effect of ethanol. None of these agents increased hippocampal NMDAR1 subunit immunoreactivity after chronic administration. Increased NMDAR1 subunit levels in the hippocampus after chronic ethanol exposure may represent an important neurochemical substrate for some of the features associated with ethanol dependence and withdrawal.     

NON-RANDOM ASSOCIATION OF MITOTIC CELLS FROM CULTURED HUMAN LYMPHOCYTE SUSPENSIONS

By using chromosome markers in two separate cell lines of a human dispermic chimera, it was shown that 4.9% of metaphases in suspensions of PHA-cultured lymphocytes were paired because of non-random factors. A similar amount of metaphase pairing occurred in cultured lymphocytes of normal donors, and evidence from the relative mitotic cycles of the paired cells indicated that some of this pairing was non-random. Such non-random pairing could be a source of bias in cell kinetic and other studies involving metaphase cells in lymphocyte cultures.     

Structure and properties of rat thymus deoxyribonucleoprotein. Solubility properties and effects of precipitation

1. Deoxyribonucleoprotein was prepared from rat thymus and was studied chiefly by the method of electric birefringence. The birefringence depends on the electrical and optical properties of the molecules and on their volume; the decay time of birefringence (after the removal of the electric field) depends on molecular length. 2. A comparison was made of the properties of deoxyribonucleoprotein redissolved after precipitation in 0.15m-sodium chloride with those of the original material, the main object being to find if structural changes have occurred in the former. As a preliminary, the dependence of the solubility of the deoxyribonucleoprotein on the concentration of added salt was investigated, and the birefringence properties were also studied after the addition of sodium chloride at low concentrations, after the alteration of pH and after dialysis. 3. It was found that precipitation of deoxyribonucleoprotein occurs in two fractions, beginning at about 0.4mm-sodium chloride. The solubility is minimal at about 0.15m-sodium chloride. 4. The electric birefringence and decay time of the deoxyribonucleoprotein decrease with increasing concentration of added sodium chloride, and the birefringence also decreases after dialysis. Prolonged dialysis leads to precipitation. 5. The properties of deoxyribonucleoprotein redissolved after precipitation with 0.15m-sodium chloride differ considerably from those of the original deoxyribonucleoprotein. This is attributed to some type of disorganization process occurring during precipitation. It is concluded that the organization of the original structure is very specific.