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.

     

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.

     

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.

     

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.

     

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.

     

Genome size and metabolic rate in salamanders

• 1.1. The relationship between genome size (C-value) and metabolic rate in salamanders was examined by correlation analyses.
• 2.2. The C-values of 48 species of salamanders were determined by flow cytometry measurement of DNA quantity in erythrocyte nuclei; C-values of 88 species were taken from the literature.
• 3.3. Standard metabolic rates for salamanders at 5, 15, 20 and 25°C were taken from the literature.
• 4.4. Only at 25°C is there a robust, significant correlation between C-value and metabolic rate, and the hypothesis of a frugal metabolic strategy and genome size effect on metabolic rates in salamanders is discussed.

     

Effects of temperature and metabolic inhibitors on contraction of anterior byssus retractor muscle of Mytilus

• 1.1. Anterior byssus retractor muscle of Mytilus (ABRM) was stimulated to contract by ACh (acetylcholine) and effects of temperature (5–30°C), FDNB (1-fluoro 2,4 dinitro-benzene) and IAA (iodoacetic acid) on tension response were examined.
• 2.2. Isometric tension was highest at the temperature range of 10–20°C and decreased at higher and lower temperature than that range.
• 3.3. The rate of tension decay after washing of ACh was accelerated by the increase of temperature.
• 4.4. Tension redevelopment after release of 1 % during contraction was much smaller at 5°C than at 20°C.
• 5.5. Tension development by ACh and the rate of tension decay after washing of ACh were remarkably decreased by the treatment of FDNB or IAA.
• 6.6. The above results were discussed from the viewpoint that energy metabolism might be related to catch.

     

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.

     

Specific dynamic action and feeding metabolism in common carp,Cyprinus carpio L.

• 1.1. Oxygen uptake attributable to Specific Dynamic Action (SDA) was measured in common carp, Cyprinus carpio L. (63.6–84.0 g) fed on 20, 35 and 50% dietary protein at 0.40 to 1.00% ration levels at 28°C.
• 2.2. After feeding both SDA magnitude and mean peak oxygen consumption increased directly with dietary protein and ration levels. SDA duration was not significantly related to dietary protein but significantly increased with ration levels.
• 3.3. SDA coefficients were 8.99, 13.51 and 15.94% with 20, 35 and 50% dietary protein showing a direction relationship to the protein content. The SDA coefficient did not change with ration size.
• 4.4. SDA models resulting from this work are of great interest for the aquaculturist, as post-feeding oxygen requirements in an intensive fish culture can be predicted where dietary protein and ration levels are known.

     

Effect of feeding on the respiration rate of the rotifer Brachionus plicatilis

The effect of feeding on the respiration rate of Brachionus plicatilis was studied. Oxygen consumption was determined under two feeding regimes, duplicate feeding and constant feeding. Oxygen consumption rate increased during feeding. The oxygen consumption profile is discussed in relation to the following processes:

1. filtration, mastication, and locomotion during feeding
2. specific dynamic action (SDA)
3. egg formation and routine metabolism.

     

Effect of temperature on oxygen consumption and heart rate of the australian crayfish Cherax tenuimanus (Smith)

• 1.1. Oxygen consumption at 18°C was 60% of the rate at 22 and 26°C.
• 2.2. Critical points, where the rate of oxygen consumption changed, were defined at 22°C (2.89 mg DO) and 26°C (3.46 mg DO). Linear regressions were fitted showing that oxygen consumption declined significantly (81.5% ±4.5) below the critical point.
• 3.3. Oxygen consumption was proportional to weight. Allometric relationships resulted in variable temperature-related coefficients for respiratory dependence on weight, a reflection of the crayfish adaptation towards re-establishment of a new equilibrium state.
• 4.4. Heart beat rate was lower at 18°C, and highest at the acclimation temperature (22°C). Stress at 26°C was evident.

     

The peculiarities of nitrogen excretion in sturgeons (Acipenser ruthenus) (Pisces,Acipenseridae)—I. the influence of ration size

• 1.1. The nonfaecal nitrogenous excretion rate in starved sterlet fingerlings and fingerlings fed on different rations was investigated. The weight of the fish and temperature of the water was 43 g and 17.5°C, respectively.
• 2.2. In the nonfaecal excrements of starved sterlets the ammonia: urea ratio was substantially lower than in teleosts. This ratio was found to be 1.4:1.
• 3.3. In fed sterlets the urea excretion rate was higher than in starved ones but independent of ration size.
• 4.4. During the day the urea excretion rate in sterlets was constant.
• 5.5. The ammonia excretion rate accelerated 2 hr after feeding and reached its peak duration 6–11 hr after depending on the ration size.
• 6.6. Total ammonia output in the sterlet increased following the increase of ration size up to 8.4% of body wt. Further increases in ration size did not cause the corresponding elevation of ammonia excretion rate.

     

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.

     

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.

     

Plasma metabolites of lake trout (Salvelinus namaycush) in relation to diet and storage conditions

• 1.1. The effects of storage temperature (2, −20 and −80°C) and duration (3, 9 and 27 days) on plasma metabolites concentrations of lake trout fed three dietary protein levels (20, 40 and 60%) and a single lipid level (20%) for 28 days were investigated.
• 2.2. Significantly high plasma urea and glucose concentrations were associated with low (20%) and high (60%) dietary protein intake in fish; while, high plasma creatinine concentration seems to characterize insufficient dietary protein and energy consumption.
• 3.3. Deproteinization of plasma with 5.0% sulfosalicylic acid did not confer better storage stability for any of the plasma metabolites except ammonia which was significantly high in non-deproteinized samples when stored at 2°C over 3, 9 and 27 day periods.
• 4.4. These studies suggest that non-deproteinized fish plasma can be stored at − 20°C without affecting the baseline concentrations of ammonia, creatinine and glucose for up to 9 days and, urea and total protein for up to 27 days.

     

The effect of temperature on the temporal structure of the vibratory courtship signals of a spider (Cupiennius salei Keys.)

We studied the effect of ambient temperature (13°C–34°C) on the vibratory courtship communication of the wandering spider Cupiennius salei.

1. Male vibratory signals. The durations of most signal parameters decreased linearly with increasing temperature. The number of syllables in one series, and that of pulses in one syllable did not change with temperature, however. The ratios of the durations of a series and interseries, and of a syllable and a sequence (duty cycle) remained largely unchanged by temperature as well.
2. Female vibratory response. The duration of the female response to the male vibration decreased with increasing temperature whereas the female response rate remained roughly constant between 13°C and 25°C. Females exposed to different temperatures favored male signals recorded in the same temperature range. To compensate for temperature dependent changes of male vibrations the female may therefore rely on the adjustment of her receiving system and/or temperature invariant signal parameters. Among these the duty cycle is considered particularly important.
3. Temporal relationship. The onset of the female response often occurred at the supposed onset of a male syllable, had the male continued to signal after completing the series. This synchronization may be advantageous in a noisy environment.

     

Behavioural thermoregulation and critical thermal limits of Macrobrachium acanthurus (Wiegman)

• (1)The preferred temperatures of Macrobrachium acanthurus were determined for prawns acclimated to 20°C, 23°C, 26°C, 29°C and 32°C, and the final preferendum estimate was (29.5°C).
• (2)The critical thermal minima (CTMin) and maxima (CTMax) were 11.0°C, 12.1°C, 13.0°C and 14.8°C, and 34.2°C, 35.0°C, 36.1°C and 39.8°C, respectively.
• (3)The zone of thermal tolerance assessed using the CTMin and CTMax boundaries was 644°C².
• (4)The acclimation response ratio was between 0.33 and 0.62.
• (5)To cultivate this species in the southeastern region of México it should be done in not <15°C (CTMin) during the winter and below 38°C in summer (CTMax).

     

Rhythmicity of chromophore turnover of visual pigment in the Antarctic amphipod Orchomene plebs (Crustacea; Amphipoda)

1. Relative retinal amounts in the compound eye of the Antarctic amphipod Orchomene plebs were assessed during conditions of continuous summer daylight every 3 h over a period of 48 h. The habitat of the experimental animal is the bottom of the Ross Sea (78°S; 166°E) down to depths of at least 400 m; water temperature is a constant — 1.8° C. A periodicity of 12 h was detected with relative amounts of 11-cis retinal exhibiting peaks at midday and at midnight and troughs at 7.00 h and 19.00 h.
2. The result that 90% of retinoid were insoluble in n-hexane suggests that at least 90% of the measured retinoid were attached to membrane-bound proteins such as opsin.
3. Selective light adaptation showed that the visual pigments were thermostable and photoregenerable. The main absorbance peak of rhodopsin, compared with metarhodopsin, seems to be in the longer wavelengths.

     

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.