Visual fields in woodcocks Scolopax rusticola (Scolopacidae; Charadriiformes)

Woodcocks, Scolopax rusticola, are long-billed terrestrial wading birds (Scolopacidae; Charadriiformes) which forage primarily by probing in soft substrates for invertebrates. Visual field topography in restrained alert birds was investigated using an ophthalmoscopic reflex technique.

1. Eye movements of significant amplitude are absent.
2. The retinal binocular field is long and narrow. It extends through 190° in the median sagittal plane. When the head adopts a normal posture (bill at an angle of 40° below the horizontal) the binocular field stretches from 25° above the bill to 5° above the horizontal behind the head. Thus, woodcocks have comprehensive visual coverage of the hemisphere above them but the bill falls outside the visual field. Maximum binocular field width equals 12° and occurs perpendicular to the line of the bill. To the rear of the head binocular field width is less than 5° except in an area 40° above the horizontal where it increases to 7°.
3. Monocular retinal fields in the horizontal plane are 182° wide. There is no blind sector at the margin of the optical fields.
4. The general structure of woodcock skulls facilitates panoramic vision in a horizontal plane.
5. Interspecific comparisons are consistent with the hypothesis that visual field topography among birds is closely associated with the role of vision in foraging. Comprehensive visual coverage of the celestial hemisphere probably occurs only in species, such as woodcocks, which rely primarily upon senses other than vision to guide foraging.

     

Selective phonotaxis to advertisement calls in the gray treefrog Hyla versicolor: behavioral experiments and neurophysiological correlates

1. The significance of particular acoustic properties of advertisement calls for selective phonotaxis by the gray treefrog, Hyla versicolor (= HV), was studied behaviorally and neurophysiologically. Most stimuli were played back at 85 dB SPL, a level typically measured at 1–2 m from a calling male.
2. Females preferred stimuli with conspecific pulse shapes at 20° and 24°C, but not at 16°C. Tests with normal and time-reversed pulses indicated the preferences were not influenced by the minor differences in the long-term spectra of pulses of different shape.
3. Pulse shape and rate had synergistic or antagonistic effects on female preferences depending on whether the values of one or both of these properties in alternative stimuli were typical of those in HV or heterospecific (H. chrysoscelis = HC) calls.
4. More auditory neurons in the torus semicircularis were temporally selective to synthetic calls (90%) than to sinusoidally AM tones and noise (< 70%).
5. Band-pass neurons were tuned to AM rates of 15–60 Hz. Neurons were more likely to be tuned to HV AM rates ( < 40 Hz) when stimuli had pulses with HV rather than HC shapes.
6. Sharp temporal tuning was uncommon and found only in neurons with band-pass or low-pass characteristics.
7. Many neurons differed significantly in response to HV and HC stimulus sets. Maximum spike rate was more often elicited by an HV stimulus (74%) than by an HC stimulus (24%).
8. Differences in spike rates elicited by HV and HC stimuli were attributable to combinations of differences in the rise times and shapes of the pulses.

     

A study on the rate of water transport of the clam katelysia opima in relation to environmental conditions

1. The neutral red technique was employed to study the rate of filtration in Katelysia opima.
2. The weight specific water filtration was found to be greater for younger clams compared to the older ones.
3. The rate of water filtration increased with decreasing salinity.
4. Water filtration was found to increase as temperature increased, reaching a maximum at 35°C. but then sharply decreasing at 39°C.
5. Light had no significant effect on the rate of filtration.
6. Suspended matter was found to affect the rate of water filtration.
7. The rate of filtration was low at high pH and high in low pH.
8. The rate of water filtration was found to be faster during high tide than during low tide.
9. The presence of the parasitic crab, Pennotheris sp., in the mantle cavity of clams had a marked effect on the particle filtration.
10. Accidental cut of the siphon tips had no effect on the rate of filtration.

     

Survival,osmoregulatory ability,and respiration of idotea chelipes (Crustacea,Isopoda) from lake veere in different salinities and temperatures

1. An ecological and physiological study ofI. chelipes from Lake Veere, The Netherlands, was made.
2. Both osmoregulatory capacity and survival decrease with increasing temperature as well as with decreasing salinity.
3. Respiration experiments suggest that the need of energy by osmoregulatory activity may be supplied at the cost of other physiological processes, at any rate at temperatures of 10°C and higher.
4. It may be expected that, if temperatures higher than 15°C and salinities lower than 8‰ coincide, the population ofI. chelipes will be affected negatively.

     

The effect of temperature on the consumption,absorption and conversion of food in Ophiocephalus punctatus bloch

1. The overall feeding rate is maximum at 28°C and decreases at 20°C and 33°C for all sizes.
2. The smaller fish are cold-sensitive. At 28°C and at 33°C the time course rate shows the same decline, whereas at 20°C the response was anomalous.
3. Absorption efficiency is independent of size and temperature.
4. Rate of absorption and hence rate of conversion is primarily conditioned by rate of feeding.
5. At 20°C the conversion efficiency is directly related to size whereas at 28°C and 33°C it is inversely related to size.

     

The effect of starvation on energy turnover and protein metabolism in Ophiocephalus punctatus bloch

1. At 20°C, fish starved for various durations took less food than unstarved fish. At 28°C, 20-day starved fish alone consumed more food.
2. The maximum feeding was during the second ten days at 28°C but in the first ten days at 20°C.
3. Absorption efficiency was unaffected by temperature and starvation.
4. Absorption rate reflected feeding rate.
5. At 28°C the conversion efficiency was high for the ten-day starved fish but at 20°C the 30-day starved fish showe high conversion efficiency.
6. Conversion rate is governed not only by feeding rate but also by conversion efficiency.
7. At 28°C the 20-day starved fish alone compensated for loss of energy, total and protein nitrogen. At 20°C the loss was compensated for by all fish.

     

Manipulations of polarized skylight calibrate magnetic orientation in a migratory bird

1. Young migratory birds enter the world with two representations of the migratory direction, one coded with respect to the magnetic field, the other with respect to celestial rotation. The preferred magnetic direction of migratory orientation is malleable early in life: it may be calibrated by celestial rotation, observed either in daytime or at night.
2. Previous experiments showed that early experience with skylight polarization was necessary for calilbration to occur in daytime. In this study, we performed a direct manipulation of patterns of polarized skylight at dawn and dusk.
3. Hand-raised Savannah sparrows (Passerculus sandwichensis) were allowed to observe the clear sky for 1 h prior to local sunrise and for one h following local sunset. They never saw the Sun nor stars. The birds observed the sky through bands of polarizing material (HNP'B) aligned with the e-vector axis in one of three orientations with respect of the azimuth of sunrise and sunset: group 1) 90°; group 2) 45° CW; group 3) 45° CCW.
4. Tested indoors in covered cages in both shifted and unshifted magnetic fields, the autumn migratory orientation of the three groups differed significantly. Group 1 oriented magnetic N-S, group 2 oriented magnetic NW-SE, and group 3 oriented magnetic NNE-SSW. These observed orientation directions are very close to those predicted by the manipulations of polarized skylight.
5. These results indicated that a fairly simplified, static polarized light pattern viewed a limited number of times only in dawn and dusk snapshots is sufficient to produce calibration of the preferred magnetic migratory orientation direction.

     

Inhibition of carotenoid synthesis in Myxococcus fulvus (Myxobacterales)

1. The inhibitory effects of CPTA, nicotine, DPA, and San 6706 on carotenogenesis in Myxococcus fulvus were investigated.
2. The effects of CPTA, D-nicotine, and L-nicotine were very similar. The action of the drugs wasadditive. The cyclization was inhibited at low doses, the introduction of the hydroxyl group at C-1′ at higher doses. Lycopene accumulated at high drug concentration. The mode of action of the inhibitors is discussed.
3. In a carotenoid mutant of M. fulvus a stimulation of the “7,8-dehydrogenase” by CPTA was observed.
4. The specific carotenoid content of bacteria was increased by DPA due to an enhanced formation of phytoene. At low doses of DPA small amounts of an intermediate carotenoid glucoside ester, a 7,8-dihydro derivative, were detected.
5. DPA was taken up by the plasma membrane. Quantitative removal of DPA by washing was not possible.
6. San 6706 specifically and reversibly blocked the desaturation of phytoene.

     

Rigorous and extended application of information theory to the afferent visual system of the cat

1. Intracellular recording were obtained from P-cells of the LGN of the cat. The impulse trains of a single presynaptic retinal ganglion cell and the postsynaptic P-cell were separated by band-pass-filtering and subsequent amplitude discrimination.
2. The rates of information and transinformation for the visual channel from the eye to a ganglion cell and to the connected P-cell were calculated. Input signals to the channel were trains of light flashes of different rate, luminance and spatial distribution.
3. Transinformation was calculated without restrictive assumptions for the code.
4. The transient behaviour of the system in response to a flash was fully considered for information calculations. Additionally, it was ensured that the state of the (adaptive) channel was considered correctly.
5. Information theory was applied in an extended way. The time courses of information transfer were calculated for various flash stimuli and compared with each other.

     

Intracellular proteolytic activity in developing myxospores of Myxococcus xanthus

1. Cell-free extracts from vegetative cells and developing myxospores of Myxococcus xanthus were found to contain similar amounts of proteolytic activity, approximately 80% of which was due to one or more neutral metal proteases.
2. Sixty per cent of the proteolytic activity was particulate.
3. The specific activity of the proteases was high throughout all stages of myxospore formation and displayed small increases in activity at two stages of development: (1) during cell shortening and (2) immediately following the conversion to spheres. The first peak in activity was apparent in assays conducted at pH 8 or 10 whereas the second peak was obvious only at pH 6.
4. A mutant which develops into myxospores only after a lag of approximately 7–8 h possessed levels of proteases similar to the wild type and displayed a peak in proteolytic activity after a delay of 7–8 h.
5. Low levels of serine protease activity were occasionally detected in both vegetative cells and myxospores; no sulfhydryl proteases were detectable in either cell type.
6. Extracellular proteases accumulated in the medium throughout myxospore development but differed from the intracellular proteases in pH optima and sensitivity to inhibitors.

     

Field and Experimental Studies on the Effects of a power station effluent on tubificidae (Oligochaeta,Annelida)

1. Higher numbers of sexually mature worms of L. hoffmeisteri were found in the River Trent downstream from Drakelow Power Stations than upstream.
2. The condenser effluent from the power stations not only increased the temperature of the river but also produced a considerable increase in the concentration of dissolved oxygen.
3. Experiments were therefore carried out on the effects of these two variables on the reproductive rate of the worms.
4. In these experiments it was found that: (a) L. hoffmeisteri increased its rate of egg production with increase in temperature up to about 25°C while T. tubifex maintained a fairly steady rate of egg production over a range of temperatures from 10–25°C. (b) L. hoffmeisteri maintained a fairly steady rate of egg and cocoon production over a wide range of oxygen concentrations above 2 ppm.
5. Therefore it seems likely that the difference between the numbers of sexually mature L. hoffmeisteri upstream and downstream from the power station were influenced more by the increased temperature, than the increased oxygen levels of the power station effluent, though under extreme conditions of deoxygenation, aeration of the river by the cooling towers at the power stations could increase the abundance of this species.

     

Improvements of the membrane filter method for DNA:rRNA hybridization

We describe and recommend the following improvements of DNA:rRNA membrane filter hybridization methods. One of our aims was to avoid DNA release from filter discs during hybridization.

1. Our hybridization conditions are 2 SSC in aq. dest., with 20% formamide, 50 C, overnight for 16 hr.
2. Duplexing is over in 8–10 hr.
3. Formamide has to be very pure (O.D.≤0.2/cm light path at 270 nm).
4. RNAase treatment: 250 μg/5 ml 2 SSC/filter at 37 C for 1 hr.
5. Our conditions for stepwise thermal denaturation are: 5°C steps from 50C to 90C in 1.5 SSC in 20% formamide.
6. Single-stranded DNA, fixed on membrane filters, and stored in vacuo at 4C, can be used reliably for hybridization for up to 20 months.
7. Concentrated DNA in 0.1 SSC, quick-frozen at ?50 C and stored at ?90 C for up to 2 years can be used for hybridization without much change.
8. A CsCl gradient purification step yields much purer DNA, but increases the release of DNA from filters by about 20%. Filters with 20% more DNA is a compensation.
9. rRNA can be stored for 20 months in SSC or 2 SSC at ?12C without changing the hybridization results.

     

Response characteristics of wide-field non-habituating non-directional motion detecting neurons in the optic lobe of the locust,Locusta migratoria

1. Extracellular recordings from wide-field nonhabituating non-directional (ND) motion detecting neurons in the second optic chiasma of the locust Locusta migratoria are presented. The responses to various types of stepwise moving spot and bar stimuli were monitored (Fig. 1)
2. Stepwise motion in all directions elicited bursts of spikes. The response is inhibited at stimulus velocities above 5°/s. At velocities above 10°/s the ND neurons are slightly more sensitive to motion in the horizontal direction than to motion in the vertical direction (Fig. 2). The ND cells have a preference for small moving stimuli (Fig. 3).
3. The motion response has two peaks. The latency of the second peak depends on stimulus size and stimulus velocity. Increasing the height from 0.1 to 23.5° of a 5°/s moving bar results in a lowering of this latency time from 176 to 130 ms (Fig. 4). When the velocity from a single 0.1° spot is increased from 1 to 16°/s, the latency decreases from 282 to 180 ms (Figs. 5–6).
4. A change-of-direction sensitivity is displayed. Stepwise motion in one particular direction produces a continuous burst of spike discharges. Reversal or change in direction leads to an inhibition of the response (Fig. 7).
5. It shows that non-directional motion perception of the wide-field ND cells can simply be explained by combining self-and lateral inhibition.

     

Effects of the discharge of thermal effluent from a power station on Lake Wabamun,Alberta, Canada — The epipelic and epipsamic algal communities

1. The epipelic algal standing crops were increased by the discharge of thermal effluent into Lake Wabamun, particularly in the discharge canal at station (03–04) and 05.
2. The increase in the standing crop size of the epipelon was due to Oscillatoria amoena and O. borneti in the heated area, while the discharge canal provided the inoculum of the algae for the heated area of the lake.
3. At station (03–04) the increased standing crop size was also a function of increased light penetration to the sediment due to the heated effluent keeping an area of the lake free of ice during the winter.
4. The species composition of the diatoms was similar at all stations except in the discharge canal where there was a reduction in the number of diatom species.
5. Navicula cuspidate developed best in the discharge canal in the summer where water temperatures of 31°C were recorded.
6. Amphora ovalis var. pediculus was the dominant diatom species during the winter under ice-cover.
7. The heated effluent had no effect upon the standing crop or species composition of the epipsammon.
8. Results obtained from the sediment core study showed that the shallow littoral zone of the lake is very disturbed due to wind-induced wave action.

     

The electrical responses of the retinal receptors and the lamina in the visual system of the fly musca

Slow electrical responses were recorded from receptors and from the lamina of the visual pathway of the fly Musca.

1. Receptors 1 to 6 in the retinal ommatidia are identified by their response dichroic sensitivity planes. The half-width of their angular sensitivity distributions is estimated 2.5° in dark adaptation, and found not to vary with ambient illumination. The retinula cells are only excited by light that enters the eye through their overlying corneal facets.
2. The responses of the lamina show no detectable dichroic sensitivity, though in favourable cases their angular sensitivity distributions may be as narrow as those of the receptors. It is shown that these responses are excited by light that enters the six facets of the corneal projection of the single lamina cartridge synapse. The retinula fibres of passage through the lamina, originating from ommatidial cells 7 and 8, evidently do not contribute excitation to the responses.
3. It is shown that the separate responses contributed by the individual receptors of the projection are added linearly at the lamina response compartment over a wide range of light intensities.

     

Der Regelkreis des Kniesehnenreflexes bei der Stabheuschrecke Carausius morosus: Reaktionen auf passive Bewegungen der Tibia

1. Passive flexion and extension of the femur-tibia-joint causes forces which are directed against the passive movements. Quantitative measurements of these forces are in accordance with the results obtained from step stimuli in open-loop-experiments (1965, 1972). Repetition of the experiments at the same joint often leads to different results: the animal is apparently able to change the amplification of the system.
2. If one brings the joint in a new position by hand, the tibia returns to its starting-point only very slowly. (Flexibilitas cerea). As a quantitative measure for Flexibilitas cerea the time interval is taken, during which a formerly fully extended joint returns to the 90°-position after a 30 sec flexion to 50° (t ₉₀) · t ₉₀ is not correllated with a quantitative measure of Thanatosis. Therefore it is not allowed to combine Thanatosis and Flexibilitas cerea to Katalepsis. — Legs whose receptor tendons were cut, show no Flexibilitas cerea. The behaviour of Flexibilitas cerea is explained by the attributes of the control system.
3. The reaction on very slow constant flexion and extension speeds (2,4°/sec – 0,3°/min) are described. Intact legs show a larger hysteresis at all speeds than legs with cut receptor tendons: it seems the control system reacts at those slow speeds. It responds only to the dynamic part of the movements, however not to the static one.

     

Characterization of two distinct latent proteinases associated with myofibrils of crucian carp (Carassius auratus cuvieri)

:

• 1.1. Enzymatic properties of two distinct proteinases tightly associated with crucian carp myofibrils were characterized.
• 2.2. These proteinases were latent but activated at 50 and 60°C, respectively.
• 3.3. The optimum pH of 50°C-proteinase was neutral-alkaline, while that of 60°C-proteinase was weak acid-neutral pH.
• 4.4. Both proteinases required more than 1% NaCl for the activity, but 50°C-proteinase was partially inhibited at higher concentrations of NaCl.
• 5.5. Both proteinases were regarded as trypsin-like proteinases belonging to a serine proteinase family, but only 60°C-proteinase was sensitive to urea, n-butanol and iso-propanol.

     

Flocculation phenomenon of Candida albicans by lysozyme

Young colonies of Sabouraud's glucose agar room temperature culture ofCandida species from human isolation were suspended in distilled water. The suspension was mixed with a solution of lysozyme and incubated in a 37° C water bath. Within 3–5 hours, various species ofCandida cells showed flocculation to varying degrees which occurred at varying periods of onset. Among sevenCandida species,Candida albicans andCandida stellatoidea showed the strongest flocculation, earliest onset and most solution clarity than did any other species.Candida stellatoidea was indistinguishable fromCandida albicans in its degree of flocculation, and in the clarity of solution.Candida species may be arranged in the following order according to their decreasing positivity in flocculation:

1. Candida albicans
2. Candida stellatoidea
3. Candida tropicalis
4. Candida krusei
5. Candida pseudotropicalis
6. Candida parapsilosis
7. Candida guilliermondii
8. Saccharomyces species may be placed afterCandida guilliermondii.

It seems possible to separate theCandida species into 3 groups by the rate of flocculation, and clarity of solution. Group I.Candida albicans andCandida stellatoidea. Group II.Candida tropicalis, C. krusei andCandida pseudotropicalis. Group III.Candida parapsilosis andCandida guilliermondii. Saccharomyces specimens (S. cerevisiae and others) were placed after group III.     

Growth of a floating aquatic weed,Salvinia under standard conditions

1. Growth of the floating aquatic weed, Salvinia, in sterile culture was exponential for at least 2 weeks under standardized conditions.
2. Increase in light intensity or in CO₂ resulted in increases in growth rate, but did not extend the exponential period of growth.
3. This aquatic plant, like many others, discriminates against calcium relative to strontium.
4. In culture Salvinia exhibited luxury consumption of N and P.
5. Because of high C/N ratios, Salvinia may not be a favorable source of animal food, but might be useful in nutrient removal schemes.
6. In sterile culture, S. molesta produced fewer leaves than S. minima, but maintained a significant increase in leaf area and dry weight. This may be correlated with the ability of the first species to rapidly spread over tropical waterways.