Body movements and retinal pattern displacements while approaching a stationary object in the walking fly,Calliphora erythrocephala

When a walking fly approaches a stationary object two types of body movements are distinguishable. Type I body movements are characterized by low frequencies (0.4–1.3 Hz) and large amplitudes (28–65°). Superimposed on these movements are type II body movements which are characterized by high frequencies (7.3–10.6 Hz) and small amplitudes (5.9–8.2°) (Figs. 3–6; Table 1). Type II movements occur no matter whether the fly is fixating a pattern or orientating itself in homogeneous surroundings without any pattern. In contrast, only 72% of the flies with immobilized heads and 62% of the flies with movable heads make type I body movements. The amplitude of type I and type II body movements increases slightly after immobilization of the head. Binocular as well as monocular pattern projection occurs for the whole walking trajectory (Fig. 7–9). Monocular pattern projection seems to be more frequent in flies with immobilized heads than in those with movable heads. The degree of pattern fluctuations in the visual field of the flies increases slightly along the walking trajectory. Near the starting point in the centre of the arena it amounts to 5–7°, while at the end of the walking trajectory it amounts to 8–10° (Table 2). The following conclusions and hypothesis can be drawn from these experiments. 1. The graph BT for the direction of the fly's logitudinal axis can be approximated by the first derivative of the walking trajectory WT, that means, dWT(x)/dxBT(x) (Fig. 11). 2. The amplitudes of type II body movements are caused by the alternating movements of the legs during forward motion, while type I body movements are classified as exploring movements. During evolution of visually guided behaviour it is possible that blowflies have adapted their elementary movement detector system to type II body movements. 3. The types of pattern projection into the visual field of the fly while approaching an object can be explained by a simple neuronal network characterized by either inhibitory and/or excitatory influences of the visually activated neurones on the motor neurones generating the propulsive forces, that means the forward motion. In addition it is postulated that the large frontal and antero-lateral receptive fields of these neurones are not coupled with the motor centres on the same side of the body (Fig. 12).     

Linkage of Pgm-3 in the house mouse and homologies of three phosphoglucomutase loci in mouse and man

The discovery of a third phosphoglucomutase locus (Pgm-3) in the house mouse is reported. Three alleles are recognized on the basis of differences in electrophoretic mobility and enzymatic activity. Pgm-3 ^a (fast mobility and high activity) is present in inbred strain C57BL/10J and 24 other strains; Pgm-3 ^b (slow mobility and high activity) is present in LP/Pas and six other strains; and Pgm-3 ^c (no detectable activity in any tissue tested) is present in strain DBA/2J and 14 other strains. Seventy-four recombinant inbred strains derived from progenitors that differed at Pgm-3 were used to study genic linkage. Pgm-3 is on chromosome 9 and is linked to Sep-1, d, Mod-1, and Ltw-3. Gene order and recombination frequencies are estimated as d 3.8±1.8% Pgm-3 2.3±1.2% Mod-1. Substrate specificities and cofactor requirements show that mouse Pgm-1 is homologous with human Pgm-2, mouse Pgm-2 with human Pgm-1, and mouse Pgm-3 with human Pgm-3.This research was supported in part by NIH Research Grant GM18684 from the National Institute of General Medical Sciences to B.A.T. and by grants from NIH A105531-02 and the Volkswagon Foundation to Jan Klein. J.H.N. was a recipient of a Fellowship from the Max-Planck-Gesellschaft, Munich. G.S. and J.K. were supported by funds from the Deutsche Forschungsgemeinschaft.     

Studies on the oligomeric structure of yeast phosphofructo-kinase by means of cross-linking diimidoesters.

Intracellular cross-linking of yeast phosphofructokinase with a series of diimidoesters of different chain length resulted in the appearance of tetramers as largest cross-linked product of the enzyme subunits. The native enzyme is evidently composed of eight subunits being arranged in two tetramers α₄β₄. In the tetramers the monomers are probably assembled in tetrahedral geometry.     

Derivative chromosomal structures from a ring chromosome 4

Summary This report describes the results from cultured lymphocytes studied at metaphase, anaphase, and interphase from an individual with a ring chromosome 4. A ring was present in 90.1% of metaphases. Special attention was directed towards the occurrence of derivative chromosomal structures, such as partially duplicated and triplicated rings, tricentric rings, chains of 3 interlocked rings, rod-shaped chromosomes, pulverized rings, and others.The clinical features of the individual (small stature and impaired mental development, hypoplastic thumbs, ptosis palpebrae hypoplastic external male genitalia, abnormal dermatoglyphic pattern) did not conform to a specific phenotype.

---

Zusammenfassung Die Lymphocyten eines Patienten mit Ringchromosom 4 wurden in der Meta-, Ana-und Interphase beobachtet. 90,1% der Metaphasen wiesen einen Ring auf. Besondere Aufmerksamkeit wurde abnormen, aus dem Ring entstandenen Chromosomen zugewandt. Es fanden sich u. a.: partielle Doppel-und Dreifachringe, Ringe mit 3 Zentromeren, Ringe aus 3 miteinander verketteten Ringen, stabförmige Chromosomen und pulverisierte Ringe.Die Symptome des Patienten (Minderwuchs, Schwachsinn, Hypoplasie der Daumen, Ptosis palpebrae, Hypoplasie des äußeren genitale, abnorme Dermatoglyphen) waren zum größten Teil unspezifish.

---

---

This work was supported in part by grants from the Deutsche Forschungsgemeinschaft and is part of a thesis by R.N. for a medical doctorate.     

Fermentation characteristics of Dekkera bruxellensis strains

The influence of pH, temperature and carbon source (glucose and maltose) on growth rate and ethanol yield of Dekkera bruxellensis was investigated using a full-factorial design. Growth rate and ethanol yield were lower on maltose than on glucose. In controlled oxygen-limited batch cultivations, the ethanol yield of the different combinations varied from 0.42 to 0.45 g (g glucose)⁻¹ and growth rates varied from 0.037 to 0.050 h⁻¹. The effect of temperature on growth rate and ethanol yield was negligible. It was not possible to model neither growth rate nor ethanol yield from the full-factorial design, as only marginal differences were observed in the conditions tested. When comparing three D. bruxellensis strains and two industrial isolates of Saccharomyces cerevisiae, S. cerevisiae grew five times faster, but the ethanol yields were 0–13% lower. The glycerol yields of S. cerevisiae strains were up to six-fold higher compared to D. bruxellensis, and the biomass yields reached only 72–84% of D. bruxellensis. Our results demonstrate that D. bruxellensis is robust to large changes in pH and temperature and may have a more energy-efficient metabolism under oxygen limitation than S. cerevisiae.     

High‐density areas for harbor porpoises (Phocoena phocoena) identified by satellite tracking

The population status of harbor porpoises has been of concern for several years, and the establishment of Marine Protected Areas (MPAs) has been suggested as a method to protect the harbor porpoise (Phocoena phocoena, Linneaus 1758) and other small cetaceans. In order to designate MPAs, high‐density areas for the species must be identified. Spatial distribution of small cetaceans is usually assessed from ship or aerial surveys. As a potentially more accurate alternative, this study examined the movements and area preferences of 64 harbor porpoises, satellite tagged between 1997 and 2007, in order to determine the distribution in the North Sea, the western Baltic, and the waters in between. Results show that harbor porpoises are not evenly distributed, but congregate in nine high‐density areas within the study area. Several of these areas are subject to significant seasonal variation. The study found no differences in the home range size of males and females, but immature harbor porpoises have larger home ranges than mature porpoises. The use of satellite telemetry for identifying areas of high harbor porpoise density can be of key importance when designating MPAs.     

Calcium binding to fluorescent calcium indicators: calcium green, calcium orange and calcium crimson

The recently introduced fluorescent calcium sensitive indicators calcium green, calcium orange and calcium crimson suggest important improvements and advantages to detect small calcium transients at low indicator concentrations. Thermodynamic dissociation constants and dissociation rate constants of calcium green, calcium orange and calcium crimson were measured by use of fluorescence titration and stopped flow fluorescence, respectively. Calcium binding to the indicators conforms to a 1:1 calcium:indicator complex although at high concentrations of calcium the fluorescence properties deviate somewhat from the behaviour predicted by the simple model. Dissociation of the calcium-indicator complex was found to be monoexponential under all conditions examined. The affinity for calcium of the three indicators generally increases with raising temperatures (Kd at 11.5 degrees C and 39.7 degrees C (nM): 261, 180 for calcium green; 527, 323 for calcium orange; 261, 204 for calcium crimson) and pH (Kd at pH 6.42 and 7.40 (nM): 314, 226 for calcium green; 562, 457 for calcium orange; 571, 269 for calcium crimson). The changes of the thermodynamic dissociation constant are mainly caused by changes of the association rate constant. The temperature dependence of calcium binding to the indicators revealed that this process is entropically favoured at ambient temperature.