Hematocrit and hemoglobin levels in some peruvian rodents from high and low altitude

Hematocrit levels in highland (3900–4500 m) AKODON (4 species) showed no change following a month at sea level, but showed a reduction of about 50 ml/1 after an additional 1–2 months. Feral MUS established at 4500 m had more cells(570 vs.470 ml/l) than those from sea level; about half this advantage was lost after a week at sea level. Highland species or races showed no consistent advantage in erythrocyte level over lowland species. The lowland PHYLLOTIS DARWINII LIMATUS actually had a higher hematocrit than any of the highland PHYLLOTIS. Mean cell hemoglobin concentrations ranged from 28 to 33 g/100 ml in rodents, and to 42 g/100 ml in the alpaca.Mean cell volumes ranged from 44 to 65 3 in rodents, and were 25–263 for the alpaca and vicna. The cell hemoglobin mass varied from 13 to 18 g in rodents and was 11.5g in the alpaca and vicuña. None of these values for rodents appear remarkable.

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Zusammenfassung Die HÄmatokrit-Werte von 4 Arten Hochland-AKODON (3900–4500 m) zeigten nach einem Monat Aufenthalt der Tiere auf Meereshöhe keine VerÄnderung; nach 2–3 Monaten waren die Werte 50 ml/l niedriger als der Vorwert. Wilde MUS in 4500 m Höhe hatten 570 ml und wilde MUS auf Meereshöhe 470 ml Erythrozyten/1 Blut. Wurden die Tiere aus der Höhe ins Tal gebracht, verschwand die HÄlfte des Unterschiedes innerhalb einer Woche. Die Erythrozyten-Werte von Hochland-Arten und -Rassen zeigten keine übereinstimmende überlegenheit über die von Tiefland-Arten. Tiefland PHYLLOTIS DARWINII LIMATUS hatten sogar einen höheren HÄmatokrit als Hochland PHYLLOTIS. In Hochland-Nagern betrug der mittlere Zell-HÄmoglobingehalt 28 bis 33 g/100 ml, in Alpaca bis 42 g/100 ml. Das mittlere Zellvolumen war bei Nagern 44–653 und beim Alpaca und Vivuna 25–263. Die Menge HÄmoglobin pro Zelle betrug 13–18g bei Nagern und 11-5g beim Alpaca und Vicuna. Die Werte bei Nagern im Hochland sind in keiner Weise bemerkenswert.

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Résumé Les valeurs hématocrites de 4 sortes d'AKODON de hautes terres (3000 – 4500 m) ne montraient pas de changement après un mois de séjour des animaux au niveau de la mer; après 2–3 mois, les valeurs étaient 50 ml/l plus basses que la valeur précédante. A 4500 m d'altitude les MUS sauvages avaient 570 ml érythrocytes/l sang et au niveau de la mer 470 ml. Les animaux transportés de l'altitude dans la vallée, la moitié de la différence disparut au bout d'une semaine.Les valeurs d'erythrocytes de sortes et rasses de hautes terres ne montraient point de supériorité concordante aux sortes de basses terres. PHYLLOTIS DARWINI LIMATUS de basses terres avaient mÊme un hématocrit plus haut que le PHYLLOTIS de hautes terres. Le contenu moyen de l'hémoglobine cellulaire des rongeurs de hautes terres était de 28 à 33/100 ml,chez Alpaca jusqu'à 429/100 ml. Aux rongeurs, la volume cellulaire moyenne,était 44–653et Alpaca et Vicuna avaient 25–263. Les rongeurs avaient une quantité d'hémoglobine par cellule de 13–18g, les Alpaca et Vicuna avaient 11,5g. Les valeurs aux rongeurs ne sont remarquable en aucun égard.

     

Ontogenesis of tonotopy in inferior colliculus of a hipposiderid bat reveals postnatal shift in frequency-place code

Summary The postnatal development of midbrain tonotopy was investigated in the inferior colliculus (IC) of the south Indian CF-FM batHipposideros speoris. The developmental progress of the three-dimensional frequency representation was determined by systematic stereotaxic recordings of multiunit clusters from the 1st up to the 7th postnatal week. Additional developmental measures included the tuning characteristics of single units (Figs. 3f; 4f; 5f), the analysis of the vocalised pulse repertoire (Figs. 3e, 4e, 5e), and morphometric reconstructions of the brains of all experimental animals (Fig. 1).The maturation of auditory processing could be divided into two distinct, possibly overlapping developmental periods: First, up to the 5th week, the orderly tonotopy in the IC developed, beginning with the low frequency representation and progressively adding the high frequency representation. With regard to the topology of isofrequency sheets within the IC, maturation progresses from dorsolateral to ventromedial (Figs. 3c, 4c). At the end of this phase the entire IC becomes specialised for narrowly tuned and sensitive frequency processing. This includes the establishment of the auditory fovea, i.e. the extensive spatial representation of a narrow band of behaviorally relevant frequencies in the ventromedial part of the IC. In the 5th postnatal week the auditory fovea is concerned with frequencies from 100–118 kHz (Fig. 4c, d). During subsequent development, the frequency tuning of the auditory fovea increases by 20–25 kHz and finally attains the adult range of ca. 125–140 kHz. During this process, neither the bandwidth of the auditory fovea (15–20 kHz) nor the absolute sensitivity of its units (ca. 50 dB SPL) were changed. Further maturation occurred at the single unit level : the sharpness of frequency tuning increased from the 5th to the 7th postnatal weeks (Q-₁₀-dB-values up to 30–60), and upper thresholds emerged (Figs. 4f, 5f).Although in the adult the frequency of the auditory fovea matches that of the vocalised pulses, none of the juvenile bats tested from the 5th to the 7th weeks showed such a frequency match between vocalisation and audition (Figs. 4e, 5e).The results show that postnatal maturation of audition in hipposiderid bats cannot be described by a model based on a single developmental parameter.Abbreviations BF best frequency - CF constant frequency - Cer cerebellum - CN cochlear nucleus - CO auditory cortex - CUF cuneiform nucleus - DAB days after birth - FAL forearm length - FM frequency modulation - IC inferior colliculus - NLL nucleus of the lateral lemniscus - PAG periaqueductal gray - SC superior colliculus     

Audiovocal interactions during development? Vocalisation in deafened young horseshoe bats vs. audition in vocalisation-impaired bats

Summary Horseshoe bats (Rhinolophus rouxi) were deafened in their 3rd–5th postnatal week. Subsequently their vocalisations were monitored to evaluate the impact of audition on the development of echolocation pulses. Hearing impairment affected the echolocation pulses as follows: the frequency of the constant frequency (CF) component was altered by between + 4 kHz and – 14 kHz, and the dominance of the second harmonic of the pulses was neutralised by a relative increase in intensity of the first and third harmonics.A second experiment focused on possible influences of acoustical self-stimulation with echolocation pulses on the establishment of auditory fovea representation in the inferior colliculus (IC). Frequency control of echolocation pulses was disrupted by larynx denervation. Thereafter, the bats produced multiharmonic echolocation signals (4–11 harmonics) varying in frequency. IC tonotopy, however, as monitored by stereotaxic electrophysiology, showed the same developmental dynamics as seen in control specimens (Fig. 10).Both experiments indicate that throughout postnatal development echolocation pulses are under auditory feedback control, whereas maturation of the auditory fovea and shifts in its frequency tuning represent an innate process. The significance of this postnatal development might be the adjustment of the vocal motor system of each bat to the frequency of its personal auditory fovea.Abbreviations CF constant frequency - CF1, CF2, CF3 harmonics of pure tone components of the echolocation pulses - FM frequency modulation - IC inferior colliculus of the midbrain     

Intracellular air bubbles and interfacial tension inNicotiana miersii

Summary Air bubbles were introduced into living hair cells ofNicotiana miersii. The air entered through wounds inflicted on slightly flaccid trichomes from the base of a fruiting stem. Protoplasmic streaming often continued normally in the threads that were near or apparently touched the air bubble. When air bubbles were included within a plasmolyzing protoplast, the protoplasm nearest the air bubble appeared and behaved like that further away.The volume of an included air bubble is affected by many factors, but as the bubble gets smaller, the overriding factor determining the rate of decrease in volume is the surface tension. The effect of the surface tension on the pressure within the bubble is such that the slope, in a graph of the radius of the bubble to the third power against time, is a constant. The value of this slope constant varies directly with the surface tension, although the surface tension is not the only factor determining its magnitude. The rate of volume decrease of bubbles both in living and in dead cells tended to be constant for small bubbles, and the value of the slope for radius cubed vs. time ranged from – 5 ³/sec. to –14 ³/sec, with most values near –10 ³/sec. A theoretical value for the slope of a nitrogen bubble in water at 25 C. is calculated to be –94 ³/sec. A minimum estimate of the surface tension of the cell content surrounding the air bubble is therefore 1/10th of the value of water.The relatively high value of the surface tension is interpreted to indicate that the organization of the cell content at the surface of the air bubble is not of the structural complexity assumed for the plasmalemma.A portion of this paper was presented at the annual meeting of the Botanical Society of America, Physiology Section, Lafayette, Indiana, 1961.This investigation was partly supported by a grant (G 8716) from the National Science Foundation.     

Eiwei\kristalloide in Parenchymzell-Plastiden vonMusa

Zusammenfassung Die Piastiden des leitbündelnahen Parenchyms sehr junger BananenblÄtter enthalten neben StÄrke, Prolamellarkörpern und Thylakoiden in ihrem Stroma bis zu l gro\e Eiwei\-kristalloide, die einen regelmÄ\igen Feinbau aus filamentartig angeordneten 50–60 å weiten Untereinheiten erkennen lassen. Die Kristalloide sind von einer Hülle umgeben, die hÄufig mit dichten Thylakoidstapeln in Verbindung steht.

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Protein crystalloids in plastids ofMusa parenchyma cells

Summary In very young banana leaves plastids of the parenchyma cells near the vascular bundles contain about 1 large crystalloids in their stroma, besides starch, prolamellar bodies and thylacoids. The crystalloids have a very regular fine structure consisting of 50–60 å filament-like subunits and are surrounded by a membranous envelope that often is in contact with stacks of thylacoids. Form and array of the crystalloid subunits are finally compared with protein-crystalloids inPhaseolus plastids, intramitochondrial crystals and crystal-containing bodies.

     

Is Ag(I) an adequate probe for Cu(I) in structural copper–metallothionein studies?

The binding abilities of silver(I) to mammalian MT 1 have been studied and compared with those of copper(I), recently reported [Bofill et al. (2001) J Biol Inorg Chem 6:408–417], with the aim of analyzing the suitability of Ag(I) as a Cu(I) probe in Cu–MT studies. The Zn/Ag replacement in recombinant mouse Zn₇–MT 1 and corresponding Zn₄-MT 1 and Zn₃-MT 1 fragments, as well as the stepwise incorporation of Ag(I) to the corresponding apo-MTs, have been followed in parallel by various spectroscopic techniques including electronic absorption (UV–vis), circular dichroism (CD) and electrospray mass spectrometry coupled to capillary zone electrophoresis (CZE-ESI-MS). A comparative analysis of the sets of data obtained in the titration of Zn₇–MT 1, Zn₄–MT 1 and Zn₃-MT 1 with AgClO₄ at pH 7.5 and 2.5 has led to the reaction pathways followed during the incorporation of silver to these proteins under these specific conditions, disclosing unprecedented stoichiometries and structural features for the species formed. Thus, the Zn/Ag replacement in Zn₇–MT 1 at pH 7.5 has revealed the subsequent formation of Ag₄Zn₅–MT, Ag₇Zn₃–MT, Ag₈Zn₃–MT, Ag₁₀Zn₂–MT, Ag₁₂Zn₁–MT, Ag_x–MT, x=14–19, whose structure consists of two additive domains only if Zn(II) remains coordinated to the protein. A second structural role for Zn(II) has been deduced from the different folding found for the Ag_x–MT species of the same stoichiometry formed at pH 7.5 or 2.5. Comparison of the binding features of Cu(I) and Ag(I) to the entire MT at pH 7.5 shows that, among all the _xZn_y–MT (0y<7) species found, only M^I₄Zn₅–MT [(Zn₄)(₄Zn₁)] and M^I₇Zn₃–MT [(₃Zn₂)(₄Zn₁)], which form during the first stages of the Zn(II)/M(I) metal replacement, show comparable 3D structures; thus, they are the only species where Ag(I) ions can be predicted to be an adequate probe for Cu(I).Electronic Supplementary Material Supplementary material is available in the online version of this article at .     

The native F0F1-inhibitor protein complex from beef heart mitochondria and its reconstitution in liposomes

A functional F₀F₁ ATP synthase that contains the endogenous inhibitor protein (F₀F₁I) was isolated by the use of two combined techniques [Adolfsen, R., McClung, J.A., and Moudrianakis, E. N. (1975).Biochemistry 14, 1727–1735; Dreyfus, G., Celis, H., and Ramirez, J. (1984).Anal. Biochem. 142, 215–220]. The preparation is composed of 18 subunits as judged by SDS-PAGE. A steady-state kinetic analysis of the latent ATP synthase complex at various concentrations of ATP showed aV _max of 1.28mol min^–1 mg^–1, whereas theV _max of the complex without the inhibitor was 8.3mol min^–1 mg^–1. In contrast, theK _m for Mg-ATP of F₀F₁ I was 148M, comparable to theK _m value of 142M of the F₀F₁ complex devoid of IF₁. The hydrolytic activity of the F₀F₁I increased severalfold by incubation at 60C at pH 6.8, reaching a maximal ATPase activity of 9.5mol min^–1 mg^–1; at pH 9.0 a rapid increase in the specific activity of hydrolysis was followed by a sharp drop in activity. The latent ATP synthase was reconstituted into liposomes by means of a column filtration method. The proteoliposomes showed ATP-Pi exchange activity which responded to phosphate concentration and was sensitive to energy transfer inhibitors like oligomycin and the uncouplerp-trifluoromethoxyphenylhydrazone.     

Fluttering target detection in Hipposiderid bats

Summary Two species of Hipposiderid bats,Hiposideros speoris andH. lankadiva, which both emit short CF-FM echolocation calls, were trained in a two-alternative forced-choice procedure to discriminate between an oscillating target and a motionless one. Two different targets were used: (1) the membrane of a low-frequency loudspeaker, producing sinusoidal frequency- and amplitude modulations and (2) a small rotating propeller, which produced short acoustical glints. In both casesH. lankadiva learned to discriminate between the oscillating and the motionless target. When the loudspeaker was used, thresholds for minimal modulation depths at different oscillation frequencies were determined. At loudspeaker membrane oscillation frequencies of 10 to 100 Hz the 75% correct thresholds lay between 90 and 300 Hz (Fig. 3).H. speoris could not be trained to react to the moving membrane, even at very high oscillation amplitudes. When the rotating propeller was the positive target, however,H. speoris learned very quickly to discriminate it from a motionless one. By decreasing the rotation speed it was possible to measure the minimal detectable glint-frequency for each bat. It lay at 67, 44, and just under 15 glints/s for the three specimens (Fig. 4). During the discrimination task both bat species increased their duty-cycle just prior to a decision by emitting long sequences of echolocation calls with short inter-pulse intervals. The duration of individual pulses remained relatively constant (Figs. 6 and 7). Possible mechanisms for discrimination of the oscillating targets are discussed and the importance of glints in the echoes for fluttering target detection is emphasized.Abbreviations A₀ amplitude of loudspeaker membrane oscillation - AM amplitude modulation - CF constant frequency - DC duty-cycle - FM frequency modulation - f _max maximal frequency modulation depth in echo - PD pulse duration - PI pulse interval - f _osc oscillation frequency     

The effect of sulfide on the blue-green algae of hot springs II. Yellowstone National Park

In the Mammoth Springs (Yellowstone National Park) waters with near neutral pH and soluble sulfide (H₂S, HS^–, S^2–) of over 1–2 mg/liter (30–60M) are characterized by substrate covers of phototrophic bacteria (Chloroflexus and aChlorobium-like unicell) above 50C and by a blue-green alga (Spirulina labyrinthiformis) below this temperature.Synechococcus. Mastigocladus, and other blue-green algae typical of most hot springs of western North America are excluded, apparently by sulfide. The sulfide-adaptedSpirulina photosynthesized at maximum rates at 45C and at approximately 300 to 700Ein/m²/sec of visible radiation. Sulfide (0.6–1.2 mM) severely poisoned photosynthesis of nonadapted populations, but those continuously exposed to over 30M tolerated at least 1 mM without inhibition. A normal¹⁴C-HCO₃ photoincorporation rate was sustained with 0.6–1 mM sulfide in the presence of DCMU (7M) or NH₂OH (0.2 mM), although both of these photosystem II inhibitors prevented photoincorporation without sulfide. Other sulfur-containing compounds (S₂O₃ ^2– SO₃ ^2–, S₂O₄ ^2– thioglycolic acid cysteine) were unable to relieve DCMU inhibition. The lowering of the photoincorporation rate by preferentially irradiating photosystem I was also relieved by sulfide. The most tenable explanation of these results is that sulfide is used as a photo-reductant of CO₂, at least when photosystem II is inhibited. It is suggested that in some blue-green algae photosystem II is poisoned by a low sulfide concentration, thus making these algae sulfidedependent if they are to continue photosynthesizing in a sulfide environment. Presumably a sulfidecytochrome reductase enzyme system must be synthesized for sulfide to be used as a photo-reductant.     

Biogenesis of protein bodies by budding from vacuoles in developing pumpkin cotyledons

Summary Vacuoles were isolated from pumpkin cotyledons at three developmental stages and judged to be pure by light microscopic inspection and marker enzyme assays. The time sequence of structural changes of vacuoles were examined by light microscopic inspection in parallel with their stainability with neutral red. Vacuoles isolated from the early stage of cotyledon development were heterogeneous in size (Ø=2–10 m) but stained uniformly with the dye. In contrast, vacuoles isolated from the middle stage were much larger (Ø=5–15 m), and there exist one to three cores, unstainable with neutral red, within a single vacuole. Electron microscopic observation confirms that vacuoles contain a few protein cores in cotyledon cells at the middle stage. Characteristically at this stage, it was observable that some large cores (Ø=4m) were budding from vacuoles. At the late stage, size of vacuoles becomes much smaller (Ø=6m), nearly equal to that of the protein bodies in dry seeds. Importantly, at this stage most of the volume of each vacuole was occupied by a single core, and only a small matrix space was stainable with neutral red. Suborganellar fractionation indicates that the vacuolar cores were identical to the crystalloids deposited in the protein bodies in dry seeds. Overall results strongly provide the evidence that one crystalloid buds from the vacuole during the later stage of seed maturation, giving rise to a protein body.     

The echolocation and hunting behavior of the bat,Pipistrellus kuhli

Summary The echolocation and hunting behavior ofPipistrellus kuhli was studied in the field using multi-exposure photography synchronized with high-speed tape recordings. During the search phase, the bats used 8–12 ms signals with sweeps (sweep width 3–6 kHz) and pulse intervals near 100 ms or less often near 200 ms (Figs. 1 and 2). The bats seemed to have individual terminal frequencies that could lie between 35 and 40 kHz. The duty cycle of searching signals was about 8%. The flight speed of hunting bats was between 4.0 and 4.5 m/s. The bats reacted to insect prey at distances of about 70 to 120 cm. Given the flight speed, the detection distance was estimated to about 110 to 160 cm. Following detection the bat went into the approach phase where the FM sweep steepened (to about 60 kHz bandwidth) and the repetition rate increased (to about 30 Hz). The terminal phase or buzz, which indicates prey capture (or attempted capture), was composed of two sections. The first section contained signals similar to those in the approach phase except that the pulse duration decreased and the repetition rate increased. The second section was characterized by a sharp drop in the terminal frequency (to about 20 kHz) and by very short pulses (0.3 ms) at rates of up to 200 Hz (Figs. 1 and 3). Near the beginning of the buzz the bat prepared for capturing the prey by extending the wings and forming a tail pouch (Fig. 4). A pause of about 100 ms in sound emission after the buzz indicated a successful capture (Fig. 4). Pulse duration is discussed in relation to glint detection and detection distance. It is argued that the minimum detection distance can be estimated from the pulse duration as the distance where pulse-echo overlap is avoided.Abbreviations CF constant frequency - FM frequency modulated     

Coiled mechanoreceptors inAplysia revealed by sensorin immunofluorescence and confocal microscopy

Identified mechanosensory neurons ofAplysia are established model neurons for studies on learning and memory, and for examining responses to axonal injury. Although many characteristics of these sensory neurons have received intensive study, the nature of the peripheral mechanoreceptive endings remains unknown. Identification of a peptide, sensorin, specific inAplysia for mechanosensory neurons, led to the development of an antibody which proved useful in studying the peripheral morphology of these neurons. Immunostaining for sensorin in tail body wall revealed that sensorin is present in peripheral arborizations. Examination of sensorin-positive fibers in the periphery revealed that they terminate as coiled structures in the muscle layer of the body wall. These coiled structures (0.5 m diameter processes, 2–3 m across the coil, 60) m long) run parallel to muscle fibers and have a pitch of about one turn per 4 um. Sensorin immunostaining was particularly intense in varicosities, both along peripheral fibers and along the coiled structure. The localization of sensorin suggests that it may be released peripherally where it could have various paracrine and/or autocrine neuromodulatory actions.     

Resonance phenomena in the cochlea of the mustache bat and their contribution to neuronal response characteristics in the cochlear nucleus

Summary The cochlea of the mustache bat, Pteronotus parnellii, is very sensitive and sharply tuned to the frequency range of the dominant second harmonic of the echolocation call around 61 kHz. About 900 Hz above this frequency the cochlear microphonic potential (CM) reaches its maximum amplitude and lowest threshold. At exactly the same frequency, pronounced evoked otoacoustic emissions (OAE) can be measured in the outer ear canal, indicating mechanical resonance. The CM amplitude maximum and the OAE are most severely masked by simultaneous exposure to tones within the range from about 61–62 kHz up to about 70 kHz. The data suggest that the mechanism of mechanical resonance involves cochlear loci basal to the 61 kHz position.The resonance contributes to auditory sensitivity and sharp tuning: At the frequency of the OAE, single unit responses in the cochlear nucleus have the lowest thresholds. Maximum tuning sharpness occurs at frequencies about 300 Hz below the OAE-frequency, where the threshold is about 10 dB less sensitive than at the OAE-frequency. In addition, in the frequency range around the OAE-frequency several specialized neuronal response features can be related to mechanical resonance: Long lasting excitation after the end of the stimulus, asymmetrical tuning curves with a shallow high frequency slope and phasic on-off neuronal response patterns. In particular the latter phenomenon indicates the occurrence of local mechanical cancellations in the cochlea.Abbreviations CF constant frequency component of echolocation calls - CM cochlear microphonic potential - FM frequency modulated component of echolocation calls - N1 compound action potential of the auditory nerve - OAE octoacoustic emission - SEOAE synchronous evoked OAE     

Competition for inorganic substrates among chemoorganotrophic and chemolithotrophic bacteria

In aerobic enrichment experiments with a chemostat, using phosphate-limited lactate medium, aSpirillum sp. predominated at the lower range of dilution rates. At the higher dilution rates an (chemoorganotrophic) unidentified rod-shaped bacterium came to the fore. The same result was obtained in competition experiments with pure cultures of the two bacteria. Growth parameters were: Rod, _max=0.48 hr^–1,k _s(PO₄ ^3–)=6.6×10^–N M;Spirillum, _max=0.24 hr^–1· k_s(PO₄ ^3–) =2.7×10^–8 M. TheSpirillum grew faster than the rod at low dilution rates, not only under phosphate-limitation but also in K⁺-,Mg²⁺-, NH₄ ⁺-, aspartate-, succinate-, and lactate-limited cultures. Both organisms showed little substrate specificity and could utilize a similar range of carbon and energy sources. The results support the view that part of the diversity among bacteria in the natural environment is based on selection toward substrate concentration. Another set of competition experiments was carried out with pure cultures of two marine obligately chemolithotrophic colorless sulfur bacteria,Thiobacillus thioparus andThiomicrospira pelophila. Tms. pelophila outgrewT. thioparus at low dilution rates under iron limitation, while the reverse was true at high dilution rates. It is concluded that the relatively fast growth ofTms. pelophila at low iron concentration may explain its higher sulfide tolerance. Organisms showing a selection advantage at very low concentrations of limiting substrates appear to have a relatively high surface to volume ratio.     

Analyzing the “Group effect”: Rheotropic responses of developingFucus eggs

Summary Zygotes of the brown alga speciesFucus furcatus were allowed to differentiate while being subjected to a steady laminar flow of sea water. The cell polarity was found, as a consequence, to be determined rheotropically. At pH 6.5, the cells tend to form their rhizoidal pole downstream, if the flow speeds range from 0.01 to 10 per second. The degree of this downstream orientation increases with flow speed in a way that indicates that it is brought about by convective redistribution of a macromolecular and locally effective growth stimulator with a diffusion constant of the order of 10^–8 cm²/second.Qualitatively, the downstream response concurs with thepositive group effect since both responses are due to a stimulator and are more or less restricted to pH<7.0. At two other pH values tested, 7.1 and 8.1, no relevant downstream orientation was detected. At flow speeds >1/second (pH 7.1 and 8.1) and 100/second (pH 6.5), a very strong upstream orientation of the rhizoid formation was found. This upstream response may be mediated by convective redistribution of a relatively mobile growth inhibitor.

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Zusammenfassung Fucus-Zygoten wurden in der Zeit zwischen 3 und 18 Stdn. nach ihrer Befruchtung konstant und laminar strömendem Seewasser ausgesetzt: Je nach pH-Wert und Strömungsgeschwindigkeit entwickelten daraufhin bis zu 60% einer Zellpopulation ihre Polaritätsachse parallel zur Strömungsrichtung.Bei pH 6,5 und Strömungsgeschwindigkeiten von 0,01 bis zu 10/sec bildeten die Zellen ihren Rhizoidpol stromabwärts. Die quantitative Analyse dieser rheotropischen Reaktion benutzte ein früher entwickeltes Modell, welches beschreibt, wie die Verteilung einer Substanz um ihre kugelförmige Quelle in Abhängigkeit von der Geschwindigkeit eines umgebenden strömenden Mediums zu Konzentrationsunterschieden zwischen Luv- und Leepol der Kugel führt. Nun wächst die gefundene rheotropische Reaktion in gleicher Weise mit der Strömungs-geschwindigkeit und strebt auch dem gleichen Maximalwerte um 25% zu, wie der Konzentrationsunterschied im Modell; vgl. die Spalten 2 und 3 in Tabelle 2. Diese übereinstimmung erlaubt den Schluß, daß die rheotropische Reaktion auf der Umverteilung eines von der Zelle emittierten Wuchsstoffes beruht, dessen Diffusionskonstante 10^–8 cm²/sec beträgt; der unbekannte Wuchsstoff muß daher hochmolekular sein (M>10⁷). Qualitativ entspricht diese rheotropische Reaktion bei pH 6,5 dempositiven Gruppeneffekt; beide Reaktionen sind nur bei pH-Werten <7,0 reproduzierbar. Andererseits spricht die sehr niedrige Diffusionskonstante des rheotropisch wirksamen Stoffes gegen dessen Rolle als Mittler despositiven Gruppeneffektes.Bei Strömungsgeschwindigkeiten > 1/sec (pH 7,1 und 8,1) sowie 100/sec (pH 6,5) treiben die Zellen das Rhizoid am stromaufwärtigen Pol aus. Dabei weicht das Ausmaß der Reaktion so stark vom theoretisch erwartbaren ab, daß der verantwortliche, hier wuchshemmende Stoff nicht näher charakterisiert werden kann; er ist wesentlich beweglicher, somit von viel geringerem Molekulargewicht als sein wuchsförderndes Gegenstück. Ein anderer Mechanismus als das Zusammenspiel von Konvektion und Diffusion kommt auch hier kaum in Frage, da eine Erhöhung der Viskosität des Seewassers (auf das Zwölffache) die rheotropische Reaktion nicht berührt.

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This work was supported by National Science Foundation Grant GD-2446.     

Inhibition by trifluoperazine of ATP synthesis and hydrolysis by particulate and soluble mitochondrial F1: Competition with H2PO 4 −

The effect of trifluoperazine (TFP) on the ATPase activity of soluble and paniculate F₁ATPase and on ATP synthesis driven by succinate oxidation in submitochondrial particles from bovine heart was studied at pH 7.4 and 8.8. At the two pH. TFP inhibited ATP hydrolysis. Inorganic phosphate protected against the inhibiting action of TFP. The results on the effect of various concentrations of phosphate in the reversal of the action of TFP on hydrolysis at pH 7.4 and 8.8 showed that H₂PO ₄ ^– is the species that competes with TFP. The effect of TFP on oxidative phosphorylation was studied at concentrations that do not produce uncoupling or affect the aerobic oxidation of succinate (<15M). TFP inhibited oxidative phosphorylation to a higher extent at pH 8.8 than at pH 7.4; this was through a diminution in theV _max, and an increase in theK _m for phosphate. Data on phosphate uptake during oxidative phosphorylation at several pH showed that H₂PO ₄ ^– is the true substrate for oxidative phosphorylation. Thus, in both synthesis and hydrolysis of ATP, TFP and H₂PO ₄ ^– interact with a common site. However, there is a difference in the sensitivity to TFP of ATP synthesis and hydrolysis; this is more noticeable at pH 8.8, i.e. ATPase activity of soluble F₁ remains at about 40% of the activity of the control in a concentration range of TFP of 40–100M, whereas in oxidative phosphorylation 14M TFP produces a 60% inhibition of phosphate uptake.     

Social Behaviour on the Wing in the False Vampire,Megaderma lyra

Social interaction occurs in bats. In a group of 10 Megaderma lyra (seven female and two male adults, as well as one female juvenile) held in captivity, two stereotyped flying behaviour patterns —the ‘grumbling flight’ and the ‘song flight’ — were observed and studied. The ‘grumbling flight’ is a social interaction in flight between at least two Megaderma lyra in which ‘grumble sequences’ are emitted. This behaviour is triggered by stress or arising aggression, and presumably attempts to avoid agonistic interactions with dangerous physical contact. The song flight was exclusively displayed by the dominant male bat and only directed at the non-lactating female members of the group, with a preference to alien females. This behaviour is composed of three behavioural stages, each accompanied by a specific ‘song strophe’. The song flight presumably aims at bonding the females to the male. During the grumbling flight and the song flight, M. lyra emits communication sounds in the ultrasonic range. The sounds consist of simple elements (FM_down, FM_up, CF), and are similar to types of sounds emitted for echolocation by various bat species.     

Ontogenesis of auditory fovea representation in the inferior colliculus of the Sri Lankan rufous horseshoe bat,Rhinolophus rouxi

Summary This report describes the ontogenesis of tonotopy in the inferior colliculus (IC) of the rufous horseshoe bat (Rhinolophus rouxi). Horseshoe bats are deaf at birth, but consistent tonotopy with a low-to-high frequency gradient from dorsolateral to ventromedial develops from the 2nd up to the 5th week. The representation of the auditory fovea is established in ventro-mediocaudal parts of the IC during the 3rd postnatal week (Fig. 3). Then, a narrow frequency band 5 kHz in width, comprising 16% of the bat's auditory range, captures 50–60 vol% of the IC (Fig. 3c). However, foveal tuning is 10–12 kHz (1/3 octave) lower than in adults; foveal tuning in females (65–68 kHz) is 2–3 kHz higher than in males (62–65 kHz). Thereafter, foveal tuning increases by 1–1.5 kHz per day up to the 5th postnatal week, when the adult hearing range is established (Figs. 4, 5). The increase of sensitivity and of tuning sharpness of single units also follows a low-to-high frequency gradient (Fig. 6).Throughout this development the foveal tuning matches the second harmonic of the echolocation pulses vocalised by these young bats. The results confirm the hypothesis of developmental shifts in the frequency-place code for the foveal high frequency representation in the IC.Abbreviations BF best frequency - CF constant frequency - FM frequency modulation - IC inferior colliculus - IHC inner hair cell; - OHC outer hair cell - RR Rhinolophus rouxi