Some physical and chemical properties of purified nematocysts of Hydra attenuata pall. (Hydrozoa,cnidaria)

• 1.1. A method for purifying undischarged nematocysts from Hydra and other cnidarians is described.
• 2.2. Isolated cysts (relative densities 1.22–1.24) evaginate their tubular content even after previous dehydration.
• 3.3. The cyst wall is permeable to dyes of mol. wts up to 600,000.
• 4.4. Approximately two-thirds of the cyst's dry wt are soluble proteins. Eighty per cent of them are of low mol. wt and highly anionic, presumably serving as binding sites for Ca²⁺ and Mg²⁺.
• 5.5. The other 20% includes 30 different proteins amongst them toxins and enzymes (phospholipase and little proteases but no collagenase, chitinase or hyaluronidase).

     

Sea water drinking as a homeostatic response to dehydration in hatchling loggerhead turtles Caretta caretta

• 1.1. Hatching Caretta caretta may lose up to 12% of their initial hatched weight from water loss during emergence from the nest.
• 2.2. After subsequent osmotic and excretory water loss in sea water, hatchlings will drink sea water (166 μl 100 g⁻¹ hr⁻¹) and return to their initial weight within 10–15 days, without feeding.
• 3.3. There were no significant changes in plasma osmolarity or sodium levels over this period.
• 4.4. This osmoregulatory strategy is in marked contrast to that seen in the estuarine crocodile, Crocodylus porosus.

     

Heating and cooling rates of eastern diamondback rattlesnakes,Crotalus adamanteus

• 1.Establishing if and how organisms modulate temperature changes is an important component of understanding their thermal biology.
• 2.We used temperature-sensitive radio-transmitters to monitor heating and cooling rates between 5 and 35 °C of four Crotalus adamanteus in the laboratory.
• 3.We found no difference between heating and cooling rates in C. adamanteus. Additionally, rates of temperature change mirrored those of a biophysical model, further suggesting a lack of physiological thermoregulation.
• 4.Our findings contrast previously published studies that demonstrate active temperature control of similarly sized reptiles and demonstrate a need for more investigations of physiological thermoregulation in reptiles.

     

The pattern and influential factors of aquatic pharyngeal movements of Trionyx sinensis

• 1.1. The pharyngeal movements of Trionyx sinensis during submersion where recorded with physiological instruments.
• 2.2. Anoxia or hypercapnia caused a marked increase in breathing rate of tested turtles during voluntary diving, and in anoxia there was a significant increase in the frequency of aquatic pharyngeal movements while hypercapnia had a slight or no effect on the frequency of these movements.
• 3.3. During voluntary diving when turtles could easily extend their heads out of water to breathe air, the frequency of rhythmic pharyngeal movements was lower; but during forced submersion, the frequency was higher and the movements were continuous.
• 4.4. The frequency increased more rapidly and greatly when turtles were in forced submersion than when they dived freely and could easily surface to breathe in N₂.
• 5.5. The frequency of pharyngeal movements of T. sinensis during diving in an aquarium with water depth of 30 or 45 cm was markedly higher than that at a water depth of 15 cm. Disturbing stimuli also influenced the aquatic rhythmic pharyngeal movements of T. sinensis.

     

Effects of temperature and acid stress on hatching,survival capacity,metabolism and postural reflexes in caenid mayflies (ephemeroptera)

• 1.1. Mortality was 100% at pH 3.5 over a temperature range of 10–30°C for embryos and nymphs of Caenis diminuta and C. hilaris.
• 2.2. Hatching success for both species was highest at pH values above 4.5.
• 3.3. Survival capacities were significantly higher at 20°C over a pH range of 4.0-7.2.
• 4.4. Oxygen consumption rates increase as a function of increasing temperature and reduced acidity.
• 5.5. Loss of the nymphal righting response was observed at pH 3.5. This response can be used as a behavioral assay for acid stress.

     

Facultative aestivation in a tropical freshwater turtle Chelodina rugosa

• 1.1. Chelodina rugosa dug from aestivation sites at the end of the dry season were immediately alert and well coordinated.
• 2.2. Compared with non-aestivating animals, aestivating turtles had 20% higher plasma osmotic pressure and 7% higher sodium. Coupled with a small, but significant weight gain upon return to the water, this suggested the occurrence of minor dehydration in aestivating animals.
• 3.3. Plasma lactate levels of aestivating animals were low, averaging 1.99 mmol/l, consistent with aerobic rather than anaerobic metabolism having sustained their long period under ground.
• 4.4. No evidence was seen of dramatic physiological specialization. Aestivation in this species is interpreted as a primarily behavioural adaptation, made possible by typically reptilian abilities to tolerate a wide range in plasma electrolytes and to survive long periods without feeding.

     

Volatile fatty acid excretion during anaerobiosis in the lugworm Arenicola marina

• 1.1. Accumulation and excretion of propionate and acetate during experimental anaerobiosis were investigated in the lugworm Arenicola marina.
• 2.2. The rate of accumulation and the ratio propionate/acetate were found to be tissue-specific.
• 3.3. The excretion of the volatile fatty acids showed a characteristic time course.
• 4.4. The results of experiments analyzing the role of different organs indicate that the excretion of these metabolites proceeded via the undifferentiated surface of the body.
• 5.5. The rate of excretion depended on the concentration gradient between animal and the ambient water, the chain-length of the fatty acid and the pH of the water. Propionate excretion was inhibited by butyrate.

     

The energy burden of the bopyrid parasite Argeia pauperata (Crustacea,isopoda) on the grass shrimp Crangon franciscorum (Crustacea,crangonidae)

• 1.1. The relationship between host and parasite rates of energy metabolism was used to estimate the energy burden of Argeia pauperata on its host Crangon franciscorum.
• 2.2. Respiration rates of the host were not significantly affected by the parasite even though the caloric turnover rate of the parasite was more than three times that of the host.
• 3.3. The ratios of both energy expenditure and size of the parasite to those of the host were positively correlated with host size.

     

Variations in response to environmental hypoxia of different colour forms of the shore crab,Carcinus maenas

• 1.1. The oxygen consumption of red and green Carcinus in normoxic and hypoxic sea water was determined, using an oxygen electrode in a sealed respirometer.
• 2.2. The red crabs had significantly higher “excited” oxygen uptake rates and a lower ability to compensate for hypoxia than the green crabs.
• 3.3. Red Carcinus display an emersion response to declining oxygen at lower oxygen tensions than the green crabs.
• 4.4. Mortality of red crabs exposed to prolonged anoxia was much greater.
• 5.5. The relationship of these findings to the zonation of the two colour forms on the shore is discussed.

     

Physiological diving adaptations of the australian water skink Sphenomorphus quoyii

• 1.1. Both the small riparian skink Sphenomorphus quoyii and its completely terrestrial relative Ctenotus robustus respond to forced submergence with instantaneous bradycardia.
• 2.2. The strength of the bradycardia was affected by water temperature and fear. Dives into hot (30°C) water produced weak and erratic bradycardia compared to dives into cold (19.5°C) water. For S. quoyii the strongest bradycardia occurred when submergence took place in water at a lower temperature than the pre-dive body temperature.
• 3.3. Upon emergence both species of skink exhibited elevated heart rates and breathing rates while heating from 19.5 to 30°C, compared to heating at rest. The increased heart and breathing rates probably act to replenish depleted oxygen stores and remove any lactate. Increased heart and ventilation rates are not indicators of physiological thermoregulation in this case.
• 4.4. Both lizard species exhibited higher heart rates and ventilation frequencies during heating than cooling.
• 5.5. Compared to its terrestrial relative, S. quoyii does not appear to possess any major thermoregulatory, ventilatory or cardiovascular adaptations to diving. However, very small reptiles may be generally preadapted to use the water to avoid predators.

     

Hyperosmotic properties of the fluids of the perivisceral coelom and water vascular system of starfish kept under stable conditions

• 1.1. Osmotic measurements were made on the perivisceral coelomic and water vascular fluids of 4 species of northwest Pacific starfish and their stable sea-water media.
• 2.2. Mean levels of both fluids were hyperosmotic in every species, often at statistically significant levels.
• 3.3. For all species combined, mean hyperosmolality (mosmol/kg ± SE) of perivisceral coelomic fluid was 1.49 ± 0.17, and water vascular fluid 6.07 ± 0.74.
• 4.4. The hyperosmotic nature of these fluids contributes to water balance, working in conjunction with madreporitic inflow and other factors.

     

Purification and some properties of an atypical alkaline p-nitrophenylphosphate phosphatase activity from Halobacterium halobium

• 1.1. An alkaline p-nitrophenylphosphate phosphatase has been purified 440-fold from extracts of Hatobacterium halobium.
• 2.2. The enzyme has an apparent molecular weight of 24,000.
• 3.3. A K_m value for p-nitrophenylphosphate of 1.12mM has been found under optimal conditions.
• 4.4. The enzyme is selectively activated and stabilized by Mn²⁺.
• 5.5. It requires high salt concentrations for stability and maximum activity.
• 6.6. It displays an unusual restricted substrate specificity of 25 phosphate esters tested, only phosphotyrosine and casein were hydrolysed besides p-nitrophenylphosphate.

     

Effects of membrane-perturbing drugs and noradrenalin on cAMP accumulation and red cell water content in carp (Cyprinus carpio) red cells

• 1.1. Carp red cells were treated with drugs that affect the cell membranes. The water content of the cells and the accumulation of cAMP in the cells were measured in normoxia and in hypoxia using non-stimulated and adrenergically stimulated cells.
• 2.2. WGA, DIDS + CCCP and A23187 increased the water content of nonstimulated normoxic cells.
• 3.3. In hypoxia ouabain and DIDS + CCCP increased the water content but cytochalasin B, NPM, DIDS, CCCP and A23187 + CA²⁺ abolished the hypoxia-induced swelling.
• 4.4. Any membrane perturbation induced some cAMP formation, Sophora and Anquilla lectins being most potent.
• 5.5. Also in adrenergically stimulated cells, membrane perturbation generally increased cAMP formation.
• 6.6. However, cAMP accumulation diminished in cells treated with cytochalasin B, CCCP and DIDS + CCCP.
• 7.7. The adrenergic swelling of carp red cells was reduced in normoxia by DIDS. NPM and CCCP increased the adrenergic swelling in normoxia to hypoxic level.
• 8.8. In hypoxia WGA and Anquilla lectin decreased the swelling.

     

Induction of locomotor behavior in the giant African snail,Achatina fulica

• 1.1. The locomotor-inducting factor of the giant African snail, Achatina fulica, was examined.
• 2.2. Snails showed nocturnal circadian behavior in relative humidity at least over 50%. Although the rhythmicity was independent of light and darkness, it was disturbed easily by hydration, and hydrated snails continued to locomote throughout the day. For induction of locomotor behavior, relative humidity over 50% was the fundamental factor and water is shown to be the limiting factor for the endogeneous circadian oscillator.
• 3.3. The integument of snails showed a higher water permeability. Through the integument, hemolymph osmolality changed easily according to hydration and dehydration from about 120 to 400 mOsm/kg H₂O. Circadian behavior was induced in snails in which hemolymph osmolality ranged from about 130 to 230 mOsm/kg H₂O.
• 4.4. By hydration, hemolymph osmolality in quiescent and estivated snails which have higher osmolality decreased gradually and then they began to locomote according to the degree of dilution, and vice versa. The induction of behavior in these snails was controlled by low hemolymph osmolality.
• 5.5. Together with the endogeneous rhythmicity, water environment was shown to be the key factor for the induction of locomotor behavior.
• 6.6. Based on these results, the mechanisms of the induction of locomotor behavior in terrestrial pulmonates are proposed.

     

Specific dynamic action demonstrated in the herbivorous marine periwinkles,LIttorina littorea L. and Littorina obtusata L. (Mollusca,Gastropoda)

• 1.1. Respiration rates of starved periwinkles, Liltorina littorea and Littorina obtusata, increased by 40–60% when fed their preferred algal food for 1 hr, or after having been exposed for the same period to an aqueous extract of the alga.
• 2.2. The stimulus causing the rise in metabolic rate by algal extracts is therefore thought to be chemosensory in nature, and possibly composed primarily of dissolved free amino acids.
• 3.3. The respiration rates of L. littorea responded only to the green alga Enteromorpha intestinalis while L. obtusata demonstrated an increase in respiration rates when fed the ubiquitous brown alga, Ascophyllum nodosum, and to a lesser degree to Enteromorpha.
• 4.4. These results compare very well to postprandial increases in oxygen consumption demonstrated in vertebrates and marine bivalves where the components of specific dynamic action (SDA) are thought to be chiefly biosynthetic costs of digestion and assimilation.

     

Some properties of ATPase activity in the intact cells of yeast Saccharomycopsis fibuligera

• 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
• 2.2. Optimal pH for the activity was approximately 7.
• 3.3. The activity was stimulated by Mg²⁺.
• 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN₃, NaVO₃, or PCMB but not inhibited by ouabain.

     

Changes in size,hydration and low molecular weight osmotic effectors during meiotic maturation of Fundulus oocytes in vivo

• 1.1. Gains in the water content of the Fundulus heteroclitus follicle account for over 90% of the total wet weight increase, and consequentially most of the size increase, associated with meiotic maturation.
• 2.2. Increases in intracellular Na⁺ and K⁺ actually exceed the accompanying increases in oocyte water, resulting in net gains in the concentration of these solutes. Changes in oocyte osmolality during maturation are mostly closely paralleled by variations in the concentration of K⁺.
• 3.3. Concentrations of various free amino acids, including taurine, remain constant or decline during maturation.
• 4.4. Taken together, these results suggest that an influx of K⁺, followed by osmotically-obliged water, is a primary cause of water uptake during oocyte maturation in F. heteroclitus.

     

Effects of low environmental pH and temperature on hatching and metabolic rates in embryos of Anax junius drury (Odonata: Aeshnidae) and the role of hypoxia in the hatching process

• 1.1. Studies were conducted in order to determine the combined effects of low environmental pH and temperature on embryonic survival capacity and metabolic rates in the dragonfly, Anax junius Drury. Studies were also conducted to assess the effects of hypoxia on hatching success as well as to investigate the role of hypoxia as a possible physiological triggering mechanism for hatching.
• 2.2. At water temperatures of 10–30°C, an environmental pH value of 3.0 was extremely limiting and significantly reduced hatching success.
• 3.3. Over a pH range of 3.0–5.0, a water temperature of 30°C was found to be severely limiting. Over a pH range of 6.0–7.0, hatching success was greater than 80% at test temperatures ranging from 10 to 25°C.
• 4.4. Embryos of A. junius exhibited a greater tolerance to markedly low environmental pH (3.0) than that previously reported for fish and amphibians, although survival capacity was less than 10%.
• 5.5. An environmental pH value of 3.0 has a significant detrimental effect on embryonic development. Survivorship and developmental rate increase significantly over a pH range of 4.0–5.0.
• 6.6. Oxygen consumption rates were lowest for fertilized eggs exposed to a pH of 3.0 at all test temperatures (10–30°C). Metabolic rates increased significantly at pH 4.O.
• 7.7. Embryos hatch successfully under hypoxic conditions in both aqueous and nonaqueous media. Results suggest that hypoxia acts as a triggering mechanism for hatching in this aquatic insect.

     

Effects of angiotensin II and bladder condition on hydration behavior and water uptake in the toad,Bufo woodhousei

• 1.1. Water absorption response (WR) behavior and water weight gain were examined in hydrated toads, Bufo woodhousei, treated with angiotensin II (All) or with a control Ringer's solution. The effects of urinary bladder condition (ad lib. bladder urine or empty bladder) were examined concurrently.
• 2.2. Toads treated with All (100μg/100g body weight), spent more time in WR posture and absorbed more water than Ringer's-injected toads.
• 3.3. Toads with empty bladders maintained WR posture for longer periods of time and gained more weight than toads whose bladders were not emptied.
• 4.4. The effects of All and bladder urine on water absorption by B. woodhousei appear to be separate and additive.

     

Genetic variation at the Lap locus and ammonia excretion following salinity transfer in an estuarine snail

• 1.1. Thais haemastoma were transferred from 30 to 15‰ and 15 to 30‰ S and ammonia excretion was measured for 72 hr.
• 2.2. Increased ammonia excretion following transfer from high to low salinity was significantly greater in snails with the rare Lap allele, Lap⁹⁴.
• 3.3. Increased rates of nitrogen loss induced by salinity reductions could be responsible for maintaining the Lap⁹⁴ allele at low frequency in estuarine populations of T. haemastoma.