Growth and oxygen consumption in embryonic and early postembryonic development of European pond turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

Experiments on developing eggs of European pond turtle (Emys orbicularis) demonstrated S-shaped changes in the rate of oxygen consumption and body weight during embryonic development. The rate of oxygen consumption and weight progressively increased within 70 days after hatching. During embryogenesis, the mass-specific rate of oxygen consumption decreased. After hatching, it increased but then decreased to a certain level, which remained constant to the end of the studied period. We observed unidirectional changes in the mass-specific rate of oxygen consumption and specific weight gain during embryonic development and this pattern was maintained after hatching. The coefficients of the allometric relationship between oxygen consumption and body weight were a = 0.33 and k = 0.52 during embryonic development and a = 0.17 and k = 0.89 during postembryonic development.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 2, 2005, pp. 214–220.Original Russian Text Copyright © 2005 by Vladimirova, Alekseeva, Nechaeva.     

Physiological studies on Biomphalaria alexandrina and Bulinus truncatus,the snail vectors of Schistosommiasis

Summary The Warburg's manometric technique was used to measure the rate of oxygen consumption of the second generation of laboratory-reared snails, Biomphalaria alexandrina and Bulinus truncatus at two temperatures of 25° and 30°C. The individual weight of the experimental snails ranged between 40 and 78 mg for B. alexandrina, between 60 and 90 mg for B. truncatus.At 25°C, the uninfected snails B. alexandrina consumed oxygen at an average rate of 0.096 ± 0.020 ml/g wet wt/hr. The rate of oxygen consumption increased to an average of 0.147 ± 0.008 ml/g wet wt/hr for uninfected snails maintained at 30°C (about 53 per cent increase). The average RW value for uninfected snails maintained at 25°C was 0.80.The snail Bulinus truncatus showed higher oxygen requirements than the snail Biomphalaria alexandrina. At 25°C, it consumed oxygen at an average rate of 0.124 ± 0.016 ml/g wet wt/hr. At 30°C, the rate of oxygen consumption reached a value of 0.220 + 0.006 ml/g wet wt/hr. The average RQ for Bulinus truncatus maintained at 25°C was 0.87.The rate of oxygen consumption of the schistosome — infected Biomphalaria alexandrina snails, maintained at 25°C decreased to an average rate of 0.059 ± 0.010 ml/g wet wt/hr, (an average of 39 per cent decrease). The respiratory quotient (RQ) also decreased to an average value of 0.58. Further research is suggested to clarify the metabolism of both schistosome-infected and uninfected snails.Read at the Ist African Symposium on Bilharziasis, Cairo Egypt, U.A.R., February, 1969.From the Laboratory of Bilharziasis Research, National Research Centre, Dokki, Egypt, U.A.R.     

Effect of sublethal doses of copper sulphate and bayluscide on survival and oxygen consumption of the snail biomphalaria alexandrina

The survival rate and oxygen consumption of Biomphalaria alexandrina snails exposed to sublethal concentrations of copper sulphate and Bayluscide were investigated. Prolonged exposure periods to the sublethal concentrations increased the percentage mortality among the exposed snails. Although the snails exposed to lower concentrations of the sublethal doses, were apparently normal, their oxygen consumption was markedly lower than the control ones. The rate of reduction of oxygen consumption by the experimental snails increased significantly at higher concentrations. The reduction of oxygen consumption was also presistent at prolonged exposure periods.     

The rate of oxygen consumption during embryogenesis of Lymnaea stagnalis (Gastropoda)

We studied the rate of oxygen consumption by the Lymnaea stagnalis embryos. The rate of oxygen consumption increased consistently during embryogenesis. The volume specific rate of oxygen consumption increased initially from the early cleavage stages until the gastrula stage and then decreased gradually to the eclosion of snails. There are three periods in embryogenesis of L. stagnalis, which differ in the coefficients of allometric dependence between the rate of oxygen consumption and volume of embryos: (1) early embryogenesis, when the increase in the rate of oxygen consumption is not accompanied by the growth of volume of the embryos; (2) larval period (trochophore and veliger stages; exponential coefficient k = 0.514), and (3) postlarval period (exponential coefficient k = 0.206).     

Impact of invasive apple snails in Hong Kong on wetland macrophytes,nutrients, phytoplankton and filamentous algae

1. Grazing by invasive species can affect many aspects of an aquatic system, but most studies have focused on the direct effects on plants. We conducted mesocosm and laboratory experiments to examine the impact of the invasive apple snail Pomacea canaliculata on macrophytes, filamentous algae, nutrients and phytoplankton. 2. In a freshwater pond, we confined 500 g of Myriophyllum aquaticum or Eichhornia crassipes with 0, 2, 4 or 8 apple snails in 1 m × 1 m × 1 m enclosures for approximately 1 month. Apple snails grazed heavily on both species of macrophytes, with higher overall weight losses at higher snail densities. The damage patterns differed between the two macrophytes. In M. aquaticum, both leaves and stems suffered from substantial herbivory, whereas in E. crassipes, only the roots suffered significant weight reduction. 3. In addition to grazing on macrophytes, apple snails appeared to have controlled the growth of filamentous algae, as these did not develop in the snail treatments. The ability of P. canaliculata to control filamentous algae was supported by a laboratory experiment where the consumption was as high as 0.25 g g⁻¹ snail DW d⁻¹. Because of a lack of native herbivorous snails in the pond, the growth of filamentous algae (mainly Spirogyra sp.) reached 80.3 g m⁻², forming a spongy pond scum in the no‐apple snail control. Together with previous reports that apple snails could eat the juveniles and eggs of other freshwater snails, our results indicated that P. canaliculata could have out‐competed native herbivorous snails from the pond by predation on their juveniles or eggs. Alternatively, P. canaliculata might have out‐competed them by monopolisation of food resources. 4. Nitrogen and phosphorous concentrations remained low throughout both experiments and were not correlated with apple snail density. The treatment effects on chlorophyll a (Chl a) and phytoplankton composition varied in the two experiments. In the M. aquaticum experiment, with increasing snail density, Chl a increased, and the phytoplankton community became dominated by Cryptophyceae. In the E. crassipes experiment, Chl a level was independent of snail density, but with increasing snail density, the phytoplankton community became co‐dominated by Cryptophyceae, Chlorophyceae and Bacillariophyceae. 5. Given the multiple effects of P. canaliculata on wetland biodiversity and function, management strategies should be developed to prevent its further spread. In invaded wetlands, strategies should be developed to eradicate the apple snail and re‐introduce native snails which can control the development of filamentous algae.     

The functional significance of ventilation frequency,and its relationship to oxygen demand in the resting brown long-eared bat,Plecotus auritus

Summary Mean oxygen consumption and simultaneous ventilation frequency of nine non-reproductive brown long-eared bats (body mass 8.53–13.33 g) were measured on 159 occasions. Ambient (chamber) temperature at which the measurements were made ranged from 10.8 to 41.1°C. Apneic ventilation occurred in 22 of the 59 measurements made when mean oxygen consumption was less than 0.5 ml·min^-1. No records of apneic ventilation were obtained when it was over 0.5 ml·min^-1. The relationship between ventilation frequency and mean oxygen consumption depended on whether ventilation was apneic or non-apneic. When ventilation was non-apneic the relationship was positive and log-linear. When ventilation was apneic the relationship was log-log. Within the thermoneutral zone ventilation frequency was not significantly different from that predicted from allometric equations for a terrestrial mammal of equivalent body mass, but was significantly greater than that predicted for a bird. A reduction in the amount of oxygen consumed per breath occurred at ambient temperatures above the upper critical temperature (39°C).Abbreviations RH relative humidity - T _a chamber temperature - vf ventilation frequency - VO₂ oxygen consumption     

Dynamics of energy metabolism in ontogenesis of striped shield bug (<Emphasis Type="Italic">Graphosoma lineatum</Emphasis> L.) and cabbage moth (<Emphasis Type="Italic">Mamestra brassicae</Emphasis> L.)

Dynamics of growth and oxygen consumption during ontogenesis of insects with direct (striped shield bug Graphosoma lineatum L.) and indirect (cabbage moth Mamestra brassicae L.) development have been compared. The correlation between a character of energy metabolism alteration and peculiarities of development of the insects has been shown. Cyclic decrease of oxygen consumption during molt and sharp dropping during metamorphosis have been observed in insects with indirect development. The decrease of oxygen consumption has been observed in insects with direct development only during molts. The coefficient a of allometric dependence of oxygen consumption on body weight of imago for cabbage moth was two times higher than that for striped shield bug.     

Oxygen and mannitol consumption ofRhizobium meliloti in relation to symbiotic nitrogen fixation efficiency

Summary The rate of oxygen and total mannitol consumption were studied with 48 strains ofRhizobium meliloti in relation to their symbiotic nitrogen fixation efficiency as expressed by the plants dry weight yields. The rate of oxygen consumption is positively correlated to the total mannitol consumption and significant inverse relationship between these two physiological properties and symbiotic efficiency are apparent. The possibility of using the rate of oxygen consumption as a preselection tool is discussed.Contribution no159.     

Follicular growth and kinetics in the Indian gerbil (Tatera indica) ovary during oestrous cycle

The growth of the follicle and oocyte in the Indian gerbil (Tatera indica) was a continuous process. The relationship between follicle and oocyte or its nucleus was log linear, represented by the equation log Y =a +b logX.A linear relationship (Y =a +bX)existed between the oocyte and its nucleus. The number of stages I and II follicles varied significantly during the oestrous cycle. Maximum percentage of stage I follicles was observed during oestrus and metoestrus, while stage II follicles were abundant during dioestrus, metoestrus and pro-oestrus. These follicles were significantly more in number than other types of the follicles. The occurrence of comparatively larger follicles during pro-oestrus and the presence of newly formed corpora lutea at oestrus, indicated ovulation in the early oestrus.     

Seasonal changes in daily metabolic patterns of Lacerta viridis

Summary Lacerta viridis maintained under natural photoperiodic conditions show daily and seasonal changes in metabolic rates and body temperature (T _b) as well as seasonal differences in sensitivity to temperature change. At all times of the year lizards have a daily fluctuation in oxygen consumption, with higher metabolic rates during the light phase of the day when tested at a constant ambient temperature (T _a) of 30°C. Rhythmicity of metabolic rate persists under constant darkness, but there is a decrease in the amplitude of the rhythm.Oxygen consumption measured at various T_as shows significant seasonal differences at T _as above 20°C. Expressed as the Arrhenius activation energy, metabolic sensitivity of Lacerta viridis shows temperature dependence in autumn, which changes to metabolic temperature independence in spring at T _as above 20°C. The results indicate a synergic relationship between changing photoperiod and body temperature selection, resulting in seasonal metabolic adjustment and seasonal adaptation.Abbreviations ANOVA analysis of variance - LD long day (16 h light) - SD short day (8 h light) - T _a ambient temperature - T _b body temperature     

Microelectrode measurement of oxygen tensions in collagen-hepatocyte gels

Summary Microelectrodes have been used for the measurement of oxygen tension in various biological systems.(Silver, 1987) Although not previously reported, microelectrodes allow the direct measurement of oxygen tension profiles within collagen gels containing entrapped hepatocytes (collagcn-hepatocyte gels). These oxygen tension profiles, along with hepatocyte oxygen consumption data, allowed the estimation of a diffusion coefficient for oxygen in collagen-hepatocyte gels, D _g = 2.99 × 10^–5 cm²/s.     

Allometric relationship between oxygen consumption and body weight of mosquitofish,Gambusia affinis

Synopsis The allometric relationship between body size and oxygen consumption of Gambusia affinis at 28° C was determined under controlled experimental conditions, using a manometric respirometer. The allometric exponent (b-value) was 0.64 ± 0.02 S.E. (n = 51). Oxygen consumption was not influenced by any time-related factors during the 17 days of measurements. Variance between replicated oxygen consumption trials on individual fish was negligible. Specific oxygen consumption rates of several G. affinis at 28° C that were determined by using a sealed vessel and O₂ electrode respirometry method were similar to the rates measured by the manometric respirometry method in similar-sized G. affinis.     

Metabolite profiles of the biocontrol yeast<Emphasis Type="Italic"> Pichia anomala</Emphasis> J121 grown under oxygen limitation

The biocontrol yeast Pichia anomala J121 prevents mould growth during the storage of moist grain under low oxygen/high carbon dioxide conditions. Growth and metabolite formation of P. anomala was analyzed under two conditions of oxygen limitation: (a) initial aerobic conditions with restricted oxygen access during the growth period and (b) initial microaerobic conditions followed by anaerobiosis. Major intra- and extracellular metabolites were analyzed by high-resolution magic-angle spinning (HR-MAS) NMR and HPLC, respectively. HR-MAS NMR allows the analysis of major soluble compounds inside intact cells, without the need for an extraction step. Biomass production was higher in treatment (a), whereas the specific ethanol production rate during growth on glucose was similar in both treatments. This implies that oxygen availability affected the respiration and not the fermentation of the yeast. Following glucose depletion, ethanol was oxidized to acetate in treatment (a), but continued to be produced in (b). Arabitol accumulated in the culture substrate of both treatments, whereas glycerol only accumulated in treatment (b). Trehalose, arabitol, and glycerol accumulated inside the cells in both treatments. The levels of these metabolites were generally significantly higher in treatment (b) than in (a), indicating their importance for P. anomala during severe oxygen limitation/anaerobic conditions.     

Does trace density reflect tracemaker density? A test using intertidal gastropods on San Salvador Island,the Bahamas

Abstract

Trace densities may be a potential proxy for tracemaker densities, especially in settings where traces but not body fossils preserve well. The relationship between the density of the gastropod Batillaria minima and its trails was examined in a modern muddy intertidal zone of a lagoon on San Salvador Island, the Bahamas. The number of snails found within a quadrat was a moderately positive predictor of the number of trails that crossed the quadrat’s boundaries. This suggests in some modern ecological systems, trace density is a reasonable proxy for tracemaker density. However, in some cases, high densities of snails are found without correspondingly high trail densities, which may be driven by the snails clumping or moving little, perhaps to access shared resources. Observations of tagging individual snails and speed measurements also suggest that B. minima disperses around this type of mudflat habitat a few tens of centimeters a day.     

The invasion of Biomphalaria pfeifferi by Schistosoma mansoni miracidia and the development of daughter sporocysts

Laboratory experiments have been carried out to determine the susceptibility of Gezira Biomphalaria pfeifferi snails to S. mansoni miracidia and the relationship between miracidia and daughter sporocyst production at the 10–17 day development stage. The relationship between snail numbers, miracidia numbers and water volume has also been studied. Two non susceptible snails, Bulinus truncatus and Cleopatra bulimoides, both of which occur naturally in Gezira canals, were tested to see if they act as decoys for S. mansoni miracidia.The results showed that the B. pfeifferi are 100% susceptible to S. mansoni invasion, at least to the daughter sporocyst development stage. The more miracidia that penetrated the more daughter sporocysts were produced, however individual variation and overlap were great. When one miracidium was released to find one snail it succeeded in low water volumes (5 m, 50 ml), but failed in 5 litres. When 100 miracidia were released mortality of snails was high suggesting superinfection particularly when only one or five snails were available. Among survivors daughter sporocyst counts were very high. Cleopatra and Bulinus snails do have a decoy effect when present in large numbers. In their presence the number of infected snails was marginally reduced and the number of daughter sporocysts greatly reduced. However, if superinfection is reduced by decoy effect, it is conceivable that Biomphalaria may be protected by decoy snails in circumstances where miracidia counts are high.     

Interaction of photoperiod and nutritive state in female reproduction of Lymnaea stagnalis

Summary

A study was made of the interaction of the photoperiod and the availability of food in influencing egg laying of the freshwater snail Lymnaea stagnalis. At a long day photoperiod (LD = 16 h light/8 h dark) egg laying of fed snails had increased compared with that of fed animals kept at a medium day photoperiod (MD = 12 h light/12 h dark). In MD snails oviposition ceased within a week of the beginning of a starvation period. This is most probably due to a reduction in the activities of the neuroendocrine caudodorsal cells which secrete an ovulation hormone. In contrast, in starved LD snails a low rate of ovipository activity continued, indicating that a lowered frequency of caudodorsal cell release cycles occurred under these conditions. The decreased mean size (number of eggs) of the egg masses in starved LD snails indicates that the activities of the endocrine dorsal bodies, which control vitellogenesis and synthetic activities in the female accessory sex organs, had decreased.

All MD snails survived, but nearly all LD snails died during the course of the experiment. Determinations of the mantle glycogen stores of LD snails suggest that the high mortality of LD snails is due to exhaustion of the animal's energy reserves.     

Standard Metabolism and Macrotaxonomy of Crustaceans

The influence of temperature and other environmental factors on the rate of oxygen consumption has been studied in adult crustaceans. The allometric relationship between respiration and body weight was calculated for 15 crustacean orders on the basis of published data on the standard metabolic rate and body weight in 225 crustacean species. The macrotaxonomy of the studied crustacean orders was proposed on the basis of the obtained values of coefficient a from the allometric relationship.     

Oxygen consumption by the bivalve Donax vittatus (da Costa)

The acute oxygen consumption of Donax vittatus (da Costa) freshly collected at different times from a beach at Barrassie, Ayrshire, Scotland, has been measured at different temperatures. The logarithmic relationship between oxygen consumption and body weight showed a significant difference on only one occasion, and a common regression coefficient (b) of 0.865 could be used for regressions of oxygen consumption on weight. Over the temperature range 2.9–20 °C oxygen consumption rose with temperature. There was a linear decline of Q₁₀ with temperature in the range 2.9 –20 °C. Differences in values of the constant (a) in the regression equation suggest that there is some acclimation to temperature, resulting in rotation of the rate/temperature curve counterclockwise for warm-acclimated animals, and a reduction of Q₁₀ in cold-acclimated animals. The differences in oxygen consumption which result are small and appear to have little practical significance. High levels of metabolically-inactive materials such as stored glycogen reserves lead to a reduction in the weight-specific oxygen consumption. Spawning animals show an increased oxygen consumption.     

Capacity for sustained terrestrial locomotion in an insect: Energetics,thermal dependence,and kinematics

Summary The capacity for sustained, terrestrial locomotion in the cockroach. Blaberus discoidalis, was determined in relation to running speed, metabolic cost, aerobic capacity, and ambient temperature (T _a=15, 23, and 34°C; acclimation temperature=24°C). Steady-state thoracic temperature (T _tss) increased linearly with speed at each T _a.The difference between T _tss and T _awas similar at each experimental temperature with a maximum increase of 7°C. Steady-state oxygen consumption (VO_2ss) increased linearly with speed at each T _aand had a low thermal dependence (Q₁₀=1.0-1.4). The minimum cost of locomotion (the slope of the VO_2ss versus speed function) was independent of T _a.Cockroaches attained a maximal oxygen consumption (VO_2max). increased with T _afrom 2.1 ml O₂·g^-1·h^-1 at 15°C to 4.9 ml O₂·g^-1·h^-1 at 23°C, but showed no further increase at 34°C, VO_2max increased 23-fold over resting VO₂ at 23°C, 10-fold at 34°C, and 15-fold at 15°C. Endurance correlated with the speed at which VO_2max was attained (MAS, maximal aerobic speed). Temperature affected the kinematics of locomotion. compared to cockroaches running at the same speed, but higher temperatures (23–34°C), low temperature (15°C) increased protraction time, reduced stride frequency, and reduced stability by increasing body pitching. The thermal independence of the minimum cost of locomotion (C_min), the low thermal dependence of VO_2ss (i.e., y-intercept of the VO_2ss versus speed function), and a typical Q₁₀ of 2.0 for VO_2max combined to increase MAS and endurance in B. discoidalis when T _awas increased from 15 to 23°C. Exerciserelated endothermy enabled running cockroaches to attain a greater VO_2max, metabolic scope, and endurance capacity at 23°C than would be possible if T _tss remained equal to T _a. The MAS of B. discoidalis was similar to that of other arthropods that use trachea, but was 2-fold greater than ectotherms, such as salamanders, frogs, and crabs of a comparable body mass.Abbreviations T _a ambient temperature - T _t thoracic temperature - T _tss steady state thoracic temperature during exercise - T _trest thoracic temperature during rest - VO₂ oxygen consumption - VO_2rest oxygen consumption during rest - VO_2ss steady-state oxygen consumption during exercise - VO_2max maximal oxygen consumption; MAS maximum aerobic speed - C _min minimum cost of locomotion - t _end endurance time     

Population structure of Placostylus hongii (Gastropoda: Paryphantidae) on the Poor Knights Islands

Abstract

Populations of the native land snail Placostylus hongii (Lesson, 1830) on the Poor Knights Islands were investigated during visits in 1976, 1977, and 1978. Marking and recapture of individual snails showed that linear growth of the shell ceased when a lip was formed around the outer margin of the aperture. Measurements of snails suggested that increase in outer lip width was a good indication of age, but that the rate of lip thickening varied between populations. Large Placostylus showed a restricted range of movement. Both tagging studies and random sampling revealed that mortality was size specific. Most small snails (<60 mm shell length) located were dead, whereas most larger snails were alive. Population densities of living snails averaged 2.2 individuals per 0.25 m² in the study area. The local distribution was patchy owing to the tendency of snails to be associated with specific features of the vegetation.