Sodium channel opening as a precursor to inactivation

The time constant of the process producing the delay in Na inactivation development as determined by the two pulse method (_delay) was extracted and compared to that of the slowest Na activation process ₃ for the I _Na during the conditioning pulse of that same determination. _delay and two pulse inactivation _c values were computer generated using a nonlinear least squares algorithm. _h and single pulse inactivation _h values were independently generated for each determination also with the aid of the computer using the same non-linear least squares algorithm. In one determination at 2 mV, _c was 4.68 and _delay 0.494 ms while _h was 4.70 and ₃ 0.491 ms for a _c/_h of 0.996 and a _delay/₃ of 1.006. Mean _delay/₃ from five determinations in four axons, both Cs and K perfused, and spanning a potential range of-27 to 2mV was 1.068. The precursor process to inactivation is channel opening. Some fraction of channels presumably inactivate via another route where prior channel opening is not required.     

Molecular motion of small nonelectrolyte molecules in lecithin bilayers

Summary We have used magnetic resonance spectroscopy, both ESR and¹³C spin relaxation, to measure translational and rotational mobilities and partition coefficients of small nitroxide solutes in dipalmitoyl lecithin liposomes. Above the bilayer transition temperature,T _c, the bilayer interior is quite fluid, as determined from the solutes' rapid rotational and moderately rapid translational motion; the rotational and translational viscosities within the bilayer are _R <1cP and =6–10cP, respectively. and _R are independent of molecular size for all solutes studied, but all were small compared to the size of the phospholipids. , and probably _R , are relatively independent of temperature aboveT _c, but both increase very sharply as temperature is lowered belowT _c; at 32°C, _R increases to 6cP and is greater than 1000 cP. Anisotropy of rotational motion increases gradually as temperature is lowered toT _c, and changes little belowT _c; anisotropy of translational motion was not investigated.¹³C nuclear spin relaxation measurements indicate that translational motion of nitroxide solutes is more rapid in the center of the bilayer than near the polar interface. It takes at least 100 nsec for a solute molecule to cross the bilayer/water interface. We estimate a lower limit of 2 sec/cm for the interfacial resistance to solute diffusion; this result indicates that interfacial resistance dominates permeation across the membrane. The relative solubility, or partition coefficient, is a strong function of solute structure, and decreases abruptly on cooling through the transition temperature. From the partition coefficient and its temperature dependence we calculate the free energy, enthalpy, and entropy of partition. Effects of cholesterol on partition and diffusion coefficients are compatible with the interpretation that bilayers containing cholesterol consist of two phases.     

Inactivation of voltage-dependent calcium current in an insulinoma cell line

We have studied the mechanism of Ca current inactivation in the -cell line HIT-T15 by conventional and perforated patch recording techniques, using two pulse voltage protocols and a combination of current and tail current measurements. In 5 mM Ca, from a holding potential of - 80 mV, the maximum current showed a complex time course of inactivation: a relatively fast, double exponential inactivation (_h1 12 ms and _h2 60 ms) and a very slowly inactivating component ( > 1 s). The faster component (_h1) was due to the voltage-dependent inactivation of a low-threshold-activated (LVA), T-type current, which deactivates more slowly ( 3–5 ms) than the other components ( 0.2–0.3 ms). The intermediate component (_h2) was due to the Ca-dependent inactivation of a portion of the high-threshold-activated (HVA) current. A saturating dose of the dihydropyridine (DHP) nifedipine (10 M) did not affect the LVA current, but inhibited by 68 ± 5% the transient, Ca-sensitive portion of the HVA current and by 33 ± 12% the long lasting component. We suggest that three components of the calcium current can be resolved in HIT cells and the main target of DHPs is a HVA current, which inactivates faster than the DHP-resistant HVA component and does so primarily through calcium influx. Correspondence to: C. Marchetti     

Modelling endplate currents: dependence on quantum secretion probability and decay of miniature current

Quantification of the time course and amplitude of endplate currents (EPC) was made with respect to dispersion of quanta secretion and to changes in the exponential decay of miniature endplate currents (_mepc). The relationship between RPC amplitude and _mepc follows a double-exponential curve with ₁= 0.3 ms and ₂ = 6 ms. If the amplitude of fully synchronised EPC is taken as 100%, then the loss of EPC amplitude is already 42% with physiological parameters of dispersion (the half-rise and decay constant of distribution of secretion probability = 0.5 ms, _mepc =1 ms). This loss is even more substantial if secretion is more dispersed or miniature endplate currents decay faster. Correspondence to: F. Vyskocil     

Activation kinetics of single high-threshold calcium channels in the membrane of sensory neurons from mouse embryos

Summary Activation kinetics of single high-threshold inactivating (HTI orN-type) calcium channels of cultured dorsal root ganglion cells from mouse embryos was studied using a patchclamp method. Calcium channels displayed bursting activity. The open-time histogram was single exponential with an almost potential-independent mean open time _op. The closed-time histogram was multicomponent; at least three of the components were associated with the activation process. The fast exponential component with the potential-independent time constant _cl ^f included all intraburst gaps, while two slower ones with potential-dependent time constants _cl ^vs described shut times between bursts and between clusters of bursts. The burst length histogram was biexponential. The fast component with a relatively potential-independent time constant _bur ^f described short, isolated channel openings while the slow component characterized real bursts with a potential-dependent mean life time. The waiting-time histogram could be fitted by a difference of two exponentials with time constants being the same as _cl ^s and _cl ^vs . The data obtained were described in the frame of a 4-state sequential model of calcium channel activation, in which the first two stages are formally attributed to potential-dependent transmembrane transfer of two charged gating particles accompanying the channel transitions between three closed states, and the third one to fast conformational changes in channel protein leading to the opening of the channel. The rate constants for all transitions were defined. The validity of the proposed model for both low-threshold inactivating (LTI orT-type) and high-threshold noninactivating (HTN orL-type) calcium channels is discussed.     

Thermodynamics of Mn2+-binding to goat α-lactalbumin

By means of reaction calorimetry we measured the apparent enthalpy change, H^app, of the binding of Mn²⁺-ions to goat -lactalbumin as a function of temperature. The observed H^app can be written as the sum of contributions resulting from a conformational and a binding process. In combination with the thermal unfolding curve of goat -lactalbumin, we succeeded in separating the complete set of thermodynamic parameters (H, G, S, C_p) into the binding and conformational contributions. By circular dichroism we showed that NH ₄ ⁺ -ions, upon binding to bovine a-lactalbumin, induce the same conformational change as do Na⁺ and K⁺: the binding constant equals 98 ± 9 M^–1.Abbreviations BLA bovine -lactalbumin - GLA goat -lactalbumin - HLA human -lactalbumin - CD circular dichroism Offprint requests to: H. Van DaelDeceased     

The viscoelasticity of entangled actin networks: the influence of defects and modulation by talin and vinculin

Rheological measurements of the frequency-dependent complex elastic module G^*() of entangled F-actin solutions in the frequency range 10^–5 – 1 Hz were carried out in three dynamic regimes: 1.) A terminal relaxation from gel-like to liquid-like behaviour measured at frequencies < _d ^–1 2.) a rubber-type plateau and 3.) a regime determined by chain conformational transitions at frequencies > _i ^–1. A major point of interest was to clarify whether rheological, high precision measurements can yield quantitative information about the influence of talin and vinculin on the structure, chain dynamics, elasticity and viscoelasticity of actin filaments with time. We show that in the regime reflecting internal chain dynamics (10^–2 to 1 s time domain), F-actin behaves as a random coil of the Rouse type. This contrasts with dynamic light scattering and correlation spectroscopic studies of actin filament flickering, which indicate that filaments behave as semiflexible rods. The internal chain dynamics, which are determined by thermically excited bending undulations, exhibit a persistence length of 0.3–1 m Evidence is provided that this discrepancy is due to a cross-over of semiflexible rod behaviour at excitation wavelengths () below approximately 1 gm to random-coil behaviour at 1 µ (expected at a frequency 1 Hz). The random coil behaviour is largely determined by defects in actin filaments leading to sharp bends of the chain which act as semiflexible hinges. Talin produces drastic effects on the time course of viscoelasticity during actin polymerization. It promotes the rapid formation of short filament fragments ( 1 gmm, within time scales of min) which anneal slowly into long filaments (within several hours), most probably by fusion. The viscoelasticity depends on the coexistence of short and very long filaments indicated by the elongation of the rubber plateau. The most dramatic effect is a reduction of the ratio of the terminal ('Ed) to the Rouse relaxation time of _i by more than one order of magnitude (_d/_i = 100 compared to ratio _d/_i = 2000 for pure actin). From this it is concluded that talin causes a remarkable decrease in the effective segment length of the macromolecule and, thus induces an increase in chain stiffness. Vinculin on the other hand shows no such effect. Correspondence to: E. Sackmann     

Conformational dynamics of the anticodon loop in yeast tRNAPhe as sensed by the fluorescence of wybutine

Conformational and dynamic properties of the anticodon loop of yeast tRNA^Phe were investigated by analyzing the time resolved fluorescence of wybutine serving as a local structural probe adjacent to the anticodon GmAA on its 3 side. The influence of Mg²⁺, important for stabilizing the tertiary structure of tRNA, and of the complementary anticodon s²UUC of E. coli tRNA ₂ ^Glu were investigated.Fluorescence lifetimes and anisotropies were measured with ps time resolution using time correlated single photon counting and a mode locked synchronously pumped and frequency doubled dye laser as excitation source. From the analysis of lifetimes () and rotational relaxation times ( _R ) we conclude that wybutine occurs in various structural states: (i) one stacked conformation where the base has no free mobility and the only rotational motion reflects the mobility of the whole tRNA molecule (=6 ns, _R =19 ns), (ii) an unstacked conformation where the base can freely rotate (=100 ps, _R = 370 ps) and (iii) an intermediary state (=2 ns, _R = 1.6 ns).Under biological conditions, i. e. in the presence of Mg²⁺ and neutral salts, wybutine is found in a stacked and immobile state which is consistent with the crystallographic picture. In the presence of the complementary codon however, as exemplified by the E. coli-tRNA ₂ ^Glu anticodon, our analysis indicates that the codon-anticodon complex exists in an equilibrium of structural states with different rotational mobility of wybutine. The conformation with wybutine freely mobile is the predominant one and suggests that this conformation of the codon-anticodon structure differs from the canonical 3–5 stack.     

Effects of zwitterionic detergents on the electronic structure of the primary donor and the charge recombination kinetics of P+Q A − in native and mutant reaction centers from Rhodobacter sphaeroides

The effects of detergents on the electronic structure of the oxidized primary donor P⁺ and the time constant _AP of the P⁺Q _A ^– charge recombination at ambient temperatures have been investigated in native and mutant reaction centers (RCs) from Rhodobacter sphaeroides. It is shown that N-lauryl-N,N-dimethyl-3-ammonio-1-propane sulfonate (SB12) induces a transition to a second distinct conformation of the RC. In the case of the wild type and the mutant FY(M197), in which a hydrogen bond is introduced to the 2-acetyl group of the dimer half of P that is associated with the M-subunit of the RC, the conformational change causes a more asymmetric spin density distribution between the two bacteriochlorophyll moieties of P⁺ in favor of the L-half. For both types of RCs the time constant _AP depends on the SB12/RC ratio as does the position of the long-wavelength band of P, _max. The increase of _AP by 30 ms and the shift of _max from 866 nm to 851 nm are indicative for the conformational change. In addition, a smaller linear increase of _AP with increasing SB12/RC ratio is superimposed on the variation of _AP due to the conformational change. Similar effects of SB12 on the optical spectra as well as on _AP are also observed for the two heterodimer mutants HL(L173) and HL(M202), in which one of the bacteriochlorophylls of P is replaced by a bacteriopheophytin. There are no clear indications for a correlation of _AP with the localization of the positive charge in P⁺. Furthermore, it is concluded from the dependence of _AP on the SB12/RC ratio that the single-site mutations do not affect the standard free energy difference of the two conformations to a measurable extent.     

Photocurrent kinetics of purple-membrane sheets bound to planar bilayer membranes

Summary The kinetics of light-driven proton transport by bacteriorhodopsin has been studied in a model system consisting of a planar lipid bilayer membrane to which purple membrane fragments have been attached. After excitation with a 10-nsec laser flash a fast negative current-transient occurs, followed by a positive transient which decays to zero. The time course of the photocurrent may be represented by a sum of four exponentials with time constants ₁= 1.2sec, ₂= 17sec, ₄= 57sec, ₁= 950sec (at 25°C). In a D₂O medium ₂ and ₃ are increased by a factor of 2.6 and 2.9, respectively, whereas ₁ remains unaffected. The observed components of the photocurrent can be correlated to photochemical reaction steps inferred from flash-photometric experiments on the basis of the observed time constants, the activation energies, and the effects of pH and D₂O. From the photocurrent signals information may be obtained on the magnitude of the charge displacement associated with the elementary transitions of the bacteriorhodopsin molecule.     

Mosquito circadian and circa-bi-dian flight rhythms: a two-oscillator model

Summary Circadian rhythmicity was found in the flight activity ofCuliseta incidens recorded in constant darkness for up to 14 weeks. The first nonhuman circa-bi-dian (about-two-day) rhythms were also found (Figs. 6–7). Circadian periods were either stable, remaining <24h (Fig. 1), or labile, with a change from <24h to >24 h (Fig. 2). Inactivity phenomena (day-skipping) were common in the latter group only (Fig. 5). The period at activity onset was much more labile than the period at offset (Fig. 4). The activity patterns of some period-lengthened animals suggested control by two oscillators which could temporarily or permanently uncouple (Figs. 8–9).A pacemaker model consisting of a labile evening (E) oscillator mutually coupled to a stable morning (M) oscillator is the most economical proposal which can account for these results. The view that E and M uncouple and run with different periods can account for many records in which the period was labile. Circa-bi-dian rhythms can be explained by the period of E lengthening to where it synchronizes with M in a 21 mode. Thus, E and M are proposed to behave similarly to the human activity and temperature oscillators. It is speculated that day-skipping might indicate that E oscillates between circadian and circa-bi-dian ranges without overt activity being expressed.Abbreviations LD1212 alternating 12h light, 12h dark - DD constant dark - LL constant light - period of rhythm - _on period at activity onset - _off period at activity offset - activity time - mean activity time     

Synthesis of Aminoethyl Glycosides of the Ganglioside GM1 and Asialo-GM1 Oligosaccharide Chains

4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)--D-glucopyranoside with a disaccharide donor, 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-1-thio-2-trichloroacetamido--D-galactopyranoside, in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in a tetrasaccharide, 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-(2,3-di-O-benzyl-6-O-benzoyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, in 69% yield. The complete removal of O-protecting groups in the tetrasaccharide, the replacement of N-trichloroacetyl by N-acetyl group, and the reduction of the aglycone azide group to amine led to the target aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of asialo-GM₁ ganglioside in 72% overall yield. Selective 3-O-glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,6-di-O-benzyl--D-galactopyranosyl)--D-glucopyranoside with thioglycoside methyl (ethyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero--D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid afforded 2-azidoethyl [methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)oate]-(2 3)-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside, the selectively protected derivative of the oligosaccharide chain of GM₃ ganglioside, in 79% yield. Its 4-O-glycosylation with a disaccharide glycosyl donor, (4-trichloroacetophenyl-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl--D-galactopyranosyl) 1-thio-2-trichloroacetamido--D-galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid gave 2-azidoethyl (2,3,4,6-tetra-O-acetyl--D-galactopyranosyl)-(1 3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido--D-galactopyranosyl)-(1 4)-{[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero--D-galacto-2-nonulopyranosyl)onate]-(2 3)}-(2,6-di-O-benzyl--D-galactopyranosyl)-(1 4)-2,3,6-tri-O-benzyl--D-glucopyranoside in 85% yield. The resulting pentasaccharide was O-deprotected, its N-trichloroacetyl group was replaced by N-acetyl group, and the aglycone azide group was reduced to afford in 85% overall yield aminoethyl glycoside of -D-Gal-(1 3)--D-GalNAc-(1 4)-[-D-Neu5Ac-(2 3)]--D-Gal-(1 4)--D-Glc-OCH₂CH₂NH₂ containing the oligosaccharide chain of GM₁ ganglioside.     

Study of neuronal gain in a conductance-based leaky integrate-and-fire neuron model with balanced excitatory and inhibitory synaptic input

Neurons receive a continual stream of excitatory and inhibitory synaptic inputs. A conductance-based neuron model is used to investigate how the balanced component of this input modulates the amplitude of neuronal responses. The output spiking rate is well described by a formula involving three parameters: the mean and variance of the membrane potential and the effective membrane time constant _Q. This expression shows that, for sufficiently small _Q, the level of balanced excitatory-inhibitory input has a nonlinear modulatory effect on the neuronal gain.     

Growth and reproduction of the Nile perch,Lates niloticus,an introduced predator,in the Nyanza Gulf,Lake Victoria,East Africa

Synopsis Length-frequency data suggest Nile perch, Lates niloticus, from the Nyanza Gulf grew to a total length of 9 cm by age 118 days and 23 cm by age 287 days. A modified von Bertalanffy growth curve _t = 1.35·L(1-e^–K(t-t _o)) with the parameters L = 93.1, K = 0.272 and t_o = 0.046, is suggested to describe growth up to 5 years of age and the relationship _t = 1.35·(31.96 + 7.681t) for fish aged 6 years and above. Length-weight relationships were = 0.0234·-gt^2.74 for fish between 7 and 15.9 cm total length, = 0.0151·^2.94 for fish between 16 and 45.9 cm total length, and = 0.0023·^3.44 for fish between 46 and 120 cm total length. Male Nile perch first matured between 50 and 55 cm total length when they were probably 2 years old; female Nile perch first matured between 80 and 85 cm total length when they were probably 4 years old. Small males were common, large males were rare, with the reverse holding for females. Sex change, from male to female, is a possible explanation for this size dimorphism.     

Interrelation between HeLa-S3 cell transfection and hemolysis in red blood cell suspension using pulsed ultrasound of various duty cycles

We have studied the in vitro transfection of a plasmid DNA with the lacZ gene to HeLa-S3 cells and hemolysis in a red blood cell (RBC) suspension under pulsed ultrasound with duty cycles of 10, 20 and 30% using a digital sonifier at a frequency of 20 kHz and an intensity of 6.2 W/cm² on the surface of a horn tip. Cultured HeLa-S3 cells in suspension were exposed to pulsed ultrasound for an apparent exposure time t from 0 to 60 s. HeLa-S3 viability decreased as a single exponential function of the total exposure time t=t with a common time constant =3.8 s for three duty cycles. Transfection was evaluated by counting the number of -galactosidase(-Gal)-positive cells relative to the total number of cells. Pulsed ultrasound provided an enhanced transfer of the -Gal plasmid to HeLa-S3 cells, 3.4-fold as compared with that in the case of the control. The optimal transfection efficiencies were 0.75, 0.80 and 0.74% near t= with =10, 20 and 30%, respectively. The number ratio of -Gal-positive cells to the surviving cells after exposure increased with t according to a modified logistic equation. The degree of hemolysis also increased exponentially with t at a time constant =₀/ for the RBC suspension in physiological saline at a hematocrit concentration of 0.5% with ₀=0.9 s. Thus the total exposure time for the optimal transfection efficiency was , that is, nearly four times of ₀. Hemolysis in the RBC suspension may be a useful model for determining optimal transfection by pulsed ultrasound of various duty cycles.     

Action of extracellular pH on Na+ and K+ membrane currents in the giant axon ofLoligo Vulgaris

Summary Voltage-clamp currents and resting membrane potential of squid giant axons have been studied at extracellular pH varying between 4 and 10. The membrane currents, analyzed according to the Hodgkin-Huxley equations, showed that sodium permeability,P _Na (E), and potassium conductance,g _K (E), curves were shifted toward positive voltages by different amounts and slightly depressed as the external pH was lowered. Under the same conditions, _m(E) and _n(E) were found to be enhanced and shifted to a larger extent in the same direction. The rate constants _m and _n were shifted substantially toward positive voltages, but _m and _n changed hardly at all. The shift of the _m(E) curve was analyzed in terms of a fixed surface charge model; it indicates that unspecific negative groups with an approximate pK_a of 4.5 are located in the vicinity of sodium active sites with an average charge separation of 8 Å. A similar figure is obtained for the potassium system from the shift of the _n(E) curve.     

Haemoglobin synthesis in 28 obligatory cases for α-thalassemia traits

Summary In the Far East two types of -thalassemia genes, namely -thalassemia₁ (-thal₁) and -thalassemia₂ (-thal₂) exist. Definite diagnosis of the -thal₁ and -thal₂ traits is very difficult because their hematological findings are minimally abnormal or normal. This study attempts to characterize the heterozygotes by hemoglobin chain synthesis in reticulocytes from obligatory cases of the -thal₁ and -thal₂ traits. Twelve parents of babies with hemoglobin Bart's hydrops fetalis (obligatory -thal₁ trait) had the mean total radioactivity / ratio of 0.76±SD 0.04, while that of 7 normal controls was 1.06±SD 0.04. The / globin chain ratios of 16 cases, who were either parents or offspring of patients with hemoglobin H disease, were found to segregate into 2 groups, i.e. 0.78±SD 0.03 (10 cases) and 0.92±SD 0.03 (6 cases), probably representing the -thal₁ and -thal₂ traits respectively. The hematological data of the first group showed definite hypochromic microcytic red cells, similar to thoseof the parents of the hydrops. The second group had significantly higher mean corpuscular hemoglobin than the first group, compatible with -thal₂ trait. Our globin chain synthesis study thus appears to be capable of discriminating normal, -thal₁ and -thal₂ traits.A preliminary report of the results was presented at the XV Congress of the International Society of Haematology, Israel, September, 1974.     

Anchorage-dependent animal cell culture by using a porous microcarrier

CHO-K1 cells were cultured by using a porous microcarrier. The effects of microcarrier concentration and agitation rate on cell growth in porous microcarrier cultures were investigated. The specific growth rate of 0.041 h^–1 in porous microcarrier cultures was independent of both microcarrier concentration and agitation rate. By estimating the total surface area occupied by cells from the maximum cell number, it was found that not all the surface area of the porous microcarrier was utilizable for cell growth.The maximum cell number decreased with increasing the microcarrier concentration and the agitation rate. From this result, it was also found that not all the cells grown on the interior surface of the porous microcarrier were protected against mechanical damage due to agitation. The protection capacity of the porous microcarrier was estimated to be 300 cells/carrier. The direct gas sparging into the culture broth in porous microcarrier cultures improved the cell density without mechanical damage to animal cells.List of Symbols d m microcarrier diameter - d _i m impeller diameter - d _p m mean pore diameter - n _i s^–1 agitation rate - p Pa pressure difference - v m/s velocity of microcarrier - v _p m/s average velocity flowing through cyclinder - Pa · s viscosity of medium - angle measured from stagnant point - Pa average shear stress - Pa shear stress distribution     

The reactions of three species of grasshopper to simple visual stimuli at different temperature-humidity conditions

The effect of the temperature-humidity factor on the reaction of two different visual stimuli has been investigated with Chorthippus brunneus (Thunb.) (= Chorthippus bicolor Charp.), Chorthippus longicornis (Latr.) (= Ch. parallelus Zett.) and Mecostethus grossus (L.). At low and high temperatures (high and low relative humidities), the three species show a greater preference for surroundings with vertical stripes than for white surroundings. At medium temperature and relative humidity, the preference for white surroundings is greater than for surroundings with vertical stripes. In a comparison between the three species at high temperature, they show regarding their intensity of preference for surroundings with vertical stripes a ranking order which is identical with that of their preference for dense grass vegetation in natural environments. In a comparison between and at high temperature, show a greater preference for surroundings with vertical stripes than .

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zusammenfassung Die Wirkung des Temperatur-Luftfeuchtigkeits-Faktors auf die Reaktion gegenüber zwei optischen Reizen wurde bei Chorthippus brunneus (Thunb.) (= Chorthippus bicolor Charp.). Chorthippus longicornis (Latr.) (= Ch. parallelus Zett.) und Mecostethus grossus (L.) untersucht. Bei niederen und hohen Temperaturen (hoher und niederer relativer Luftfeuchtigkeit) zeigen die drei Arten eine größere Bevorzugung für Umgebungen mit vertikalen Streifen als für weiße Umgebungen. Bei mittlerer Temperatur und relativer Feuchtigkeit ist die Bevorzugung weißer Umgebung größer als für Umgebungen mit vertikalen Streifen. Bei einem Vergleich der drei Arten bei hoher Temperatur ergibt sich hinsichtlich der Stärke ihrer Bevorzugung für vertikal gestreifte Umgebung eine Rangfolge, die mit der ihrer Bevorzugung dichter Grasvegetation in natürlicher Umgebung identisch ist. Bei einem Vergleich zwischen und bei hoher Temperatur zeigen die eine größere Präferenz für Umgebung mit Vertikalstreifung als die .