共查询到20条相似文献,搜索用时 31 毫秒
1.
Malathi Srivatsan Bertram Peretz Brent Hallahan Ramesh Talwalker 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(1):29-37
Summary Hemolymph was examined in young (ca. 86 days old), mature (ca. 163 days old), and old (ca. 294 days old) Aplysia for age-related changes in constituent proteins. In young, mature, and old animals protein concentrations were 1.6±0.27, 1.41±0.53, and 1.45±0.43 mg·ml-1, respectively. The copper-containing respiratory protein, hemocyanin, measured by determining the copper concentration, was found to increase significantly from young (0.98±0.51 g·ml-1) to mature (2.02±0.95 g·ml-1) Aplysia, with little change between mature and old (1.92±0.43 g·ml-1) animals. These findings were consistent with the results obtained when hemocyanin was directly measured by spectrophotometric absorption at 340 nm. Acetylcholinesterase (AChE) was present in the hemolymph of Aplysia. Its activity was highest in mature animals (3121±1627 units·mg-1) and least in old animals (1463±599 units·mg-1). Young animals had intermediate levels (2080±762 units·mg-1). SDS-PAGE revealed a distinct pattern of protein bands for hemolymph from each age group; hemolymph from the young group contained six prominent protein bands with molecular weights (MW) from 13 to 300 kDa. Hemolymph of mature and old animals exhibited four and three prominent protein bands, respectively, with MW between 45 and 300 kDa. A prominent band at 97 kDa was present in samples from the mature group, but was faint in samples from the old group and absent in samples from the young group. Under non-denaturing conditions the hemolymph protein band patterns for each group differed from the others, thereby demonstrating that the age-dependent differences in the protein profiles are intrinsic to hemolymph in vivo. Isoelectric focusing of the hemolymph samples revealed that the proteins were all acidic (pI ca. 3.0–6.5). The hemolymph from the young differed from the other two groups in having an additional acidic protein (pI ca. 4.0). A possible link between age-related changes in hemolymph proteins and age-related changes in the nervous system is proposed.Abbreviations 2-ME
2-mercaptoethanol
- AChE
acetylcholinesterase
- FMRFamide
amidated tetrapeptide containing phenylalanine, methionine, arginine and phenylalanine
- MW
molecular weight
- PAS
periodic acid-Schiff
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis
- TRIS
tris-(hydroxymethyl)-aminomethane 相似文献
2.
C. E. Booth B. R. McMahon A. W. Pinder 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1982,148(1):111-121
Summary At the onset of moderate swimming activity,Callinectes sapidus rapidly increased branchial ventilation, heart rate, and oxygen uptake, reaching steady state values in 2–3 min, with a half-time of 30 sec. Although O2 extraction efficiency decreased slightly (50% to 43%) upon reaching steady state, O2 uptake was increased 2.6 fold over resting (routine) levels. HemolymphP
O
2 did not change during sustained (30–60 min) exercise, but a marked decrease in pH (7.60 to 7.10), associated with a 14-fold increase in hemolymph lactate concentration, caused decreases in both pre-and postbranchial O2 content due to a large hemocyanin Bohr shift. The effect of the Bohr shift on O2 binding, however, was minimized by an increase in hemocyanin O2 affinity induced by lactate ions; the influence of lactate on hemocyaninP
50
was shown to be the same in vivo and in vitro. As a result of the interaction between the Bohr and lactate effects, only slight increases were observed in the a-v O2 difference (13%) and the quantitative role of hemocyanin in oxygen transport (11%) during exercise. The increase in O2 delivery was therefore attributed primarily to a 2.3 fold increase in cardiac output (Fick estimate), resulting from increases in both heart rate (1.61 X) and stroke volume (1.42X). During exercise hemocyanin remained 21% oxygenated upon leaving the tissues, thus maintaining a substantial venous O2 reserve which could be utilized to fuel more strenuous levels of exercise at least partly by aerobic pathways. The high hemolymph lactate levels, however, indicate that anaerobic metabolism makes a significant contribution to energy production even during moderate exercise. These results are similar to the respiratory and circulatory responses reported for other decapod crustaceans and fish during mild exercise.C. sapidus, however, appears to be highly resistant to fatigue, which correlates with its welldeveloped locomotor capabilities. 相似文献
3.
Douglas R. Yingst 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1978,125(2):165-173
Summary The in vitro freezing point of hemolymph from specimens ofMesidotea entomon adapted to seawater with a salinity of 34 is equal to that of seawater of the same salinity. On the other hand, if such specimens are cooled in freezing seawater, the in vivo freezing point of the hemolymph is 0.3 °C lower than the previous in vitro freezing point (Fig. 2). This difference between the in vivo and in vitro freezing points is probably due to an increase in the ionic concentration of the hemolymph in response to the increasing salt concentration of the freezing seawater with which the hemolymph probably remains isoosmotic. Specimens do not freeze as the hemolymph becomes more concentrated, because the cuticle ofM. entomon prevents the external ice from seeding the hemolymph. Measurements of the permeability of the cuticle to ice demonstrate that the cuticle is sufficiently impermeable to act as a barrier to seeding. Also, the structure of the cuticle is consistent with its functional impermeability (Fig. 6).This research was included in a dissertation submitted to the University of Southern California in partial fulfillment of the requirements for the degree of Doctor of Philosophy 相似文献
4.
Summary The gammarid amphipod Onisimus litoralis, which inhabits arctic and subarctic intertidal and under-ice habitats, is a euryhaline hyperosmotic regulator. It survives 10 d exposures to salinities from 5 to 55 ppt. It hyperregulates its hemolymph osmolality during 3 h exposures to dilutions of 33 ppt seawater and remains hyperosmotic for at least 2 w. The hemolymph is isosmotic to the medium after 12 h exposures to salinities higher than 33 ppt. The gammarid amphipod Anonyx nugax, which inhabits arctic and subarctic subtidal areas, tolerates salinities from 23 to 45 ppt with little mortality. Unlike Onisimus, however, it is an osmoconformer and its hemolymph becomes isosmotic to all dilute salinities within its tolerance range after 12 h and to concentrated media after 3 h. The salinity tolerances and osmoregulatory abilities of both species are reflected in their distributions in the field. 相似文献
5.
C. A. D. de Kort A. B. Koopmanschap 《Archives of insect biochemistry and physiology》1987,5(4):255-269
Lipophorin, the protein that specifically binds juvenile hormone in the hemolymph of the Colorado potato beetle, Leptinotarsa decemlineata, is a high-density lipoprotein of Mr ~ 574,000. Lipophorin contains 43% lipid and is composed of two apoproteins: apolipophorin I (Mr ~ 251,000) and apolipophorin II (Mr ~ 78,000). Both apoproteins contain mannose residues. Carotenoids make up a substantial part of the lipid fraction. Lipophorin constitutes about 25% of the total hemolymph proteins. Its concentration in the hemolymph (26 μM in 4-day-old long-day and 40 μM in 4-day-old short-day beetles) changes with different physiological conditions concomitant with changes in total protein content. Lipophorin specifically binds 10R-juvenile hormone III with high affinity. The dissociation constant for 10R-juvenile hormone III is 12 ± 2 nM. One lipophorin molecule contains one specific juvenile hormone-binding site. The concentration of binding sites therefore equals that of lipophorin in hemolymph. 相似文献
6.
By protein immunobiochemistry and cDNA sequencing, we have found only a single hemocyanin polypeptide in an opisthobranch gastropod, the sea hare Aplysia californica, which contrasts with previously studied prosobranch gastropods, which express two distinct isoforms of this extracellular respiratory protein. We have cloned and sequenced the cDNA encoding the complete polypeptide of Aplysia californica hemocyanin (AcH). The cDNA comprises 11,433 bp, encompassing a 5UTR of 77 bp, a 3UTR of 1057 bp, and an open reading frame for a signal peptide of 20 amino acids plus a polypeptide of 3412 amino acids (Mr ca. 387 kDa). This polypeptide is the subunit of the cylindrical native hemocyanin (Mr ca. 8 MDa). It comprises eight different functional units (FUs: a, b, c, d, e, f, g, h) that have been identified immunobiochemically after limited proteolysis of AcH purified from the hemolymph. Each FU shows a highly conserved copper-A and copper-B site for reversible oxygen binding. FU AcH-h carries a specific C-terminal extension of ca. 100 amino acids that include two cysteines that may be utilized for disulfide bridge formation. Potential N-glycosylation sites are present in six FUs but lacking in AcH-b and AcH-c. On the basis of multiple sequence alignments, phylogenetic trees and a statistically firm molecular clock were calculated. The latter suggests that the last common ancestor of Haliotis and Aplysia lived 373±47 million years ago, in convincing agreement with fossil records from the early Devonian. However, the gene duplication yielding the two distinct hemocyanin isoforms found today in Haliotis tuberculata occurred 343±43 million years ago.[Reviewing Editor: Dr. Axel Meyer]The sequence reported in this paper has been deposited in the GenBank database under accession number AJ556169. 相似文献
7.
Summary The effects of short- and long-term exposure to a range in concentration of sea salts on the kinetics of NH
inf4
sup+
uptake by Spartina alterniflora were examined in a laboratory culture experiment. Long-term exposure to increasing salinity up to 50 g/L resulted in a progressive increase in the apparent Km but did not significantly affect Vmax (mean Vmax=4.23±1.97 mole·g–1·h–1). The apparent Km increased in a nonlinear fashion from a mean of 2.66±1.10 mole/L at a salinity of 5 g/L to a mean of 17.56±4.10 mole/L at a salinity of 50 g/L. These results suggest that the long-term effect of exposure to total salt concentrations within the range 5–50 g/L was a competitive inhibition of NH
inf4
sup+
uptake in S. alterniflora. No significant NH
inf4
sup+
uptake was observed in S. alterniflora exposed to 65 g/L sea salts. Short-term exposure to rapid changes in salinity significantly affected both Vmax and Km. Reduction of solution salinity from 35 to 5 g/L did not change Vmax but reduced Km by 71%. However, exposing plants grown at 5 g/L salinity to 35 resulted in an decrease in Vmax of approximately 50%. Exposure of plants grown at 35 g/L to a total sea salt concentration of 50 g/L for 48h completely inhibited uptake of NH
inf4
sup+
. For both experiments, increasing salinity led to an increase in the apparent Km similar to that found in response to long-term exposure. Our data are consistent with a conceptual model of changes in the productivity of S. alterniflora in the salt marsh as a function of environmental modification of NH
inf4
sup+
uptake kinetics. 相似文献
8.
Margarethe Spindler-Barth 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1976,105(2):197-205
Juvenile and young adult specimens ofCarcinus maenas were kept in the laboratory under controlled conditions. The main organic constituents and their variations during the molt cycle were quantitatively determined.
相似文献
1. | During postmolt the chitin concentration rises rapidly (20–74 mg/g dry weight) in parallel to the dry weight (120–293 mg/g fresh weight). Both decrease again before ecdysis (Fig. 1). |
2. | The glycose level in the hemolymph (50–80 g/ml) shows no significant variation during the molt cycle (Fig. 2). |
3. | The glycogen concentrations in integument, (14–180 mg/g dry weight), gills (5.5–66 mg/g dry weight), muscle (8.8–41 mg/g dry weight), heart (135–308 mg/g dry weight) and hemolymph (160–690 g/ml) reach their maximum values during the premolt stage. The highest glycogen content in the midgut gland (83 mg/g dry weight) is observed immediately before and after ecdysis. Glycogen storage in heart and hemolymph, can, account for about half of the glycogen stored in the midgut gland (Figs. 3,4 and 5). |
4. | The lipid concentration in the hemolymph (120–440 g/ml) and in gills (33.6–70 mg/g dry weight) rises during the premolt stage (Figs. 6 and 7). |
5. | The protein concentration in the hemolymph increased during premolt (9–31 mg/ml). The copper content (13–42 g/ml) varies in parallel to the protein concentration indicating that the proportion of hemocyanin to total proteins remains constant during the molting cycle (Fig. 8). |
9.
Derek Chignell K.E. van Holde Karen I. Miller 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1997,118(4):895-902
The subunit structure of the hemocyanin from the squid Sepioteuthis lessoniana has been characterized by analytical sedimentation. The protein exists free in the hemolymph as a 60S, multisubunit structure with a molecular mass of approximately 4.0 × 106 gm/mol. At extremes of pH this can be dissociated into 10 monomers, of mass 3.8 × 105 gm/mol each.At neutral pH, if 5 mM Mg2+ or less is present, the monomers associate to form a dimer of molecular mass 7.7 × 105 gm/mol. In the pH range from 10.5 to 7.5, formation of the dimer is facilitated by the binding of one proton per monomer. If the magnesium concentration is raised to 25 mM or more, the dimers reversibly and completely associate into decamers. This process is shown to require the binding of 10 magnesium ions.In its size, subunit structure, and behavior with respect to association–dissociation processes, Sepioteuthis hemocyanin resembles the corresponding proteins of other squid much more than it does those of Octopus or Nautilus. 相似文献
10.
Osmotic jump experiments were used to measure the ionic permeability induced in lipid vesicles by Megathura crenulata hemocyanin. It was found that this protein strongly increases the conductance of K+ and Cl- through these membranes but not that of SO
4
=
. These effects were attributed to the formation of ionic channels in the vesicles. We have found that a simple first-order binding model can explain the dependence of the number of pore-containing vesicles both on the time after exposure to hemocyanin and on the protein concentration. Milder effects were attributed to a non-specific adhesion of the protein to the membrane surface. Consistent with the hypothesis of reversible association, vesicles which retained hemocyanin after step sucrose density gradient centrifugation at low ionic strength, lost most of the protein upon recentrifugation at high ionic strength. Consistent with the hypothesis of channel formation bot the above vesicle preparations transferred voltage-dependent hemocyanin channels into planar bilayers when they were made to fuse with them. It is concluded that hemocyanin can interact both specifically, by forming pores within the hydrophobic core of lipid membranes, and non-specifically, probably by means of electrostatic interaction with the surface of the same membrane.Abbreviations Hepes
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- PC
phosphatidylcholine
- PE
phosphatidylethanolamine
- PS
phosphatidylserine
- DOC
sodium deoxycholate 相似文献
11.
The effect of alkalinepH on the association, dissociation, and denaturation of carmin, the high-molecular-weight protein from safflower seed was investigated in thepH range 7–12, using various biophysical techniques. The results indicate that the multimeric protein carmin dissociates atpH 8.0 where denaturation has not set in. The association-dissociation of the protein can be represented schematically as 11S 7S 4S 2S. AbovepH 10, the protein undergoes simultaneous dissociation and denaturation. The denaturation process appears to be complete at pH 12.5. The protein undergoes conformational change and covalent modifications and cleavage during the denaturation process. A reversibility study shows that the process of dissociation is reversible to a large extent, whereas denaturation appears to be irreversible. These results are discussed in terms of association-dissociation, denaturation and alkaline-catalyzed covalent modifications and cleavage of seed proteins. 相似文献
12.
Summary A 25 nm hollow double helical filament has been detected ultrastructurally in the cell-free supernatant from hemolymph of the keyhole limpet Megathura crenulata (Gastropoda: Prosobranchia: Fissurellidae). Subsequently, much higher concentrations of this material were found in the cell pellet from hemolymph. Both negative staining and thin sectioning have been performed in an attempt to obtain a preliminary structural characterization of this new filament. It is proposed that the filaments are released or secreted from blood hemocytes in response to bleeding, but it has not been possible to define absolutely an intracellular organelle containing this material. It is shown that the hollow filaments, which have fine fibrillar surface extensions, are readily distinguishable from collagen fibrils and from tubular (multi-decameric) keyhole limpet hemocyanin (KLH). 相似文献
13.
Effects of heterogeneous salinity on growth,water uptake,and tissue ion concentrations of alfalfa 总被引:2,自引:0,他引:2
Aims
Soil salinity varies greatly in the plant rhizosphere. The effect of nonuniform salinity on the growth and physiology response of alfalfa plants was determined to improve understanding of salt stress tolerance mechanisms of alfalfa.Methods
Plant growth, predawn leaf water potential, water uptake, and tissue ionic content were studied in alfalfa plants grown hydroponically for 9 days using a split-root system, with uniform salinity or horizontally nonuniform salinity treatments (0/S, 75/S, and 150/S corresponding to 0, 75, and 150 mM NaCl on the low salt side, respectively).Results
Compared with uniform high salinity, 0/S and 75/S treatments significantly increased the alfalfa shoot dry mass and stem extension rate. Compensatory water uptake by low salt roots of 0/S and 75/S treatments was observed. However, decreased leaf Na+ concentration, increased leaf K+/Na+, and compensatory growth of roots on the low salt side were observed only following the 0/S treatment.Conclusions
Nonuniform salinity dose not enhance plant growth once a threshold NaCl concentration in low salinity growth medium has been reached. Compensation of water uptake from the low-salt root zone and regulation of K+/Na+ homeostasis in low salt root play more important role than regulation of leaf ions in enhancing alfalfa growth under nonuniform salinity.14.
T. A. Petrova A. Yu. Lianguzov N. M. Malygina 《Journal of Evolutionary Biochemistry and Physiology》2016,52(1):37-45
A set of normal biochemical indices of the hemolymph plasma in the gastropod pulmonate mollusc Achatina fulica was described in this study. A comparative analysis of the whole plasma and its subfractions enriched with and depleted of the oxygen-carrying protein hemocyanin was carried out using spectrophotometry and spectrofluorimetry. Individual features of the absorption spectra were analyzed using fourth derivatives. An optimal method to estimate the protein concentration was identified. The buffer capacity, equivalence points and pK values of the dominant buffer groups were calculated to characterize the acid-base properties of hemolymph plasma and its subfractions. A major role in maintaining the hemolymph buffer capacity was shown to belong to the bicarbonate buffering system. The results of this study are compared with the data for Helix pomatia available in literature. In the future, the tested indices will be used to devise ecotoxicological criteria for environmental assessment. 相似文献
15.
《Comparative biochemistry and physiology. A, Comparative physiology》1986,83(4):701-708
- 1.1. Osmolality and chloride concentrations in the hemolymph of Penaeus monodon became stable 1 day after molting in 32 ppt, while total protein and calcium concentrations remained stable throughout the molting cycle. When intermolt (≥ 36 hr postmolt) animals were transferred from control (32 ppt) to experimental (8–40 ppt) salinities, osmolality, chloride and total protein, but not calcium, concentrations in the hemolymph achieved steady state values 24–48 hr after transfer.
- 2.2. The hemolymph osmolality was a linear function (slope = 0.28) of medium osmolality at salinities between 8 and 40 ppt. It was isosmotic to seawater at 698 mOsm (10 g prawns) and 752 mOsm (30 g), and was hyperosmotic to the medium below isosmotic concentrations, and hypoosmotic to those above.
- 3.3. Hemolymph chloride concentration was isoionic to seawater at 334 mM, and was hyperregulated below isoionic concentrations, and hyporegulated to those above.
- 4.4. P. monodon maintained its hemolymph calcium concentration between 6.4 and 10 mM when medium salinities increased from 8 to 40 ppt.
- 5.5. Total protein concentration in the hemolymph was independent of medium salinity (8–40 ppt) and hemolymph osmolality (540–850 mOsm).
16.
Stabilizing influence of calcium and magnesium ions on the decameric structure of chiton hemocyanins
The stabilizing effects of Ca2+ and Mg2+ ions on the decameric structure of hemocyanins from two representative chitons, Stenoplax conspicua and Mopalia muscosa were investigated by light-scattering molecular weight measurements, ultracentrifugation, absorbance, and circular dichroism methods. The dissociation profiles at any given pH resulting from the decrease in divalent ion concentration, investigated at a fixed protein concentration of 0.1 g.liter-1, could be fitted by a decamer-to-dimer-to monomer scheme of subunit dissociation. The initial decline in the light-scattering molecular weight curves required one or two apparent binding sites per hemocyanin dimer formed as intermediate dissociation product, with apparent dissociation constants (kD,2) for Ca2+ ions of 0.7 to 7 X 10(-4) M, not very different from the value of 2.5 X 10(-4) M obtained by Makino by equilibrium dialysis for the hemocyanin of the opistobranch, Dolabella auricularia. The binding of Mg2+ ion to S. conspicua and M. muscosa hemocyanins appears to be both weaker than the binding of Ca2+ and more pH dependent, with kD,2 values ranging from the 3 X 10(-4) to 4 X 10(-2) M at pH 8.5 to 9.5. The dissociation the decameric hemocyanin species (sedimentation coefficient ca. 60 S) is also observed in the ultracentrifugation with the initial appearance of 18-20 S dimers, followed by a shift in equilibrium to monomeric species of lower sedimentation rates of 11-12 S as the divalent ion concentration is reduced below 1 X 10(-4) M Ca2+ and Mg2+. The dissociation of dimers to monomers in the second step of the reaction is characterized by one or two binding sites per subunit and a somewhat stronger affinity for divalent ions, indicated by apparent dissociation constants (kD,1) of 0.7 X 10(-4) to 3 X 10(-3) M. Circular dichroism and absorbance measurements at 222 and 346 nm suggest no significant changes in the conformation of the hemocyanin subunits produced by the different stages of subunit dissociation. 相似文献
17.
The effect of salinity variation (0, 7, 14, 21, 28 and 35S) on survival, moulting and respiratory metabolism of the early zoeal stages of the shrimps Palaemon pandaliformis and P. northropi from the northern coast of the State of São Paulo, Brazil is investigated. Freshly hatched larvae were maintained at 20 °C, in each salinity for a maximum of seven days. Oxygen consumption measurements were made at 20 °C for each salinity using Cartesian diver microrespirometers. In 0S, all P. northropi zoeae died after 24 h while 24% of the P. pandaliformis zoeae survived until 4 days. Zoeae of both species survived poorly in 7S, the best survival for the two species (90%) being registered in 28%.S. Palaemon northropi zoeae did not survive 35S while 45% survival was recorded for P. pandaliformis zoeae in this medium after seven days. Moulting did not occur in zoeae of either species in 0%.S, nor in P. northropi in 7S. The metabolism-salinity curve for P. pandaliformis zoea I is very stable over the range 0–21S while that for P. northropi exhibits complete salinity independence from 21–35 S. Thus, while the early zoeal stages, at least, are conspecific, both developing in the same environment as part of the coastal zooplankton community, they clearly maintain distinct physiological characteristics. The data presented possibly reflect genetic adaptations to the adult biotope already manifested in the first zoeae. 相似文献
18.
S. V. Sladkova S. V. Kholodkevich 《Journal of Evolutionary Biochemistry and Physiology》2011,47(2):160-167
Analysis of total protein in hemolymph was performed by Lowry method on sexually mature crawfish Pontastacus leptodactylus. The total protein content in the crawfish hemolymph was studied for one year. The protein concentration varied widely, amounted to from 12 to 95 mg/ml, and depended on season and the molting cycle phase. There are presented histograms for distribution of animals for the protein level during different seasons and their character is analyzed. In summer the amount of protein is maximal prior to molt and decreases by 40% at once after it. There is studied the diapason of total protein concentrations in hemolymph, in which survival of crawfish at unfavorable changes in habitat is maximal. The adaptive possibilities of crawfish with the low protein content are attenuated. The crawfish with the protein concentration in hemolymph lower than the «critical» one were submitted for different time by action of hydroquinone (1 g/l) used as a model toxicant. A brief action did not affect the protein content in hemolymph. At a long toxic action the protein level in hemolymph fell, on average, by 40%, which preceded death of the animals. Possible mechanisms of positive correlation of the protein concentration in the crawfish hemolymph and of their survival at deterioration of quality of the water medium are discussed. 相似文献
19.
Zusammenfassung 1. Das CiliatZoothamnium hiketes
Precht ändert bei abrupten Veränderungen des Salzgehalts des Außenmediums vorübergehend das Zellvolumen.2. Die Resistenzgrenzen gegenüber sehr niedrigen und hohen Salzgehalten hängen von der Konzentration ab, an welche sich die Tiere angepaßt haben.3. Der zeitliche Verlauf der Resistenzänderung mit dem Salzgehalt des Außenmediums wird verfolgt. Nachwirkungen im Sinne eines hardening bei Temperaturänderungen konnten nicht festgestellt werden.4. Unter Berücksichtigung dieser Befunde wird allgemein zu den Reaktionen, Regulationen und Adaptationen (= Akklimatisationen) der Tiere nach Veränderungen der Temperatur und des Salzgehaltes des Außenmediums Stellung genommen.
Responses, regulations and adaptations of animals following changes in temperature and salinity. Experiments withZoothamnium biketes (Ciliata, Peritricha)
Upon sudden changes in external salinity the ciliate protozoonZoothamnium hiketes Precht temporarily changes its cell volume. Resistance to very low and high salinities depends on the previous salinity history. The time course of changes in resistance to external salinity is described. Aftereffects in the sense of temperature hardening were not observed. Considering these findings, responses, regulations and adaptations (acclimatizations) of animals exposed to changes in temperature and salinity are discussed in general.相似文献
20.
Sally D. Hacker David Heimer C. Eric Hellquist Tabitha G. Reeder Blain Reeves Timothy J. Riordan Megan N. Dethier 《Biological invasions》2001,3(2):211-217
We report on the habitat dependent invasion and control pattern of the English cordgrass, Spartina anglica C. E. Hubbard, in Puget Sound, Washington. In 36 years, the plant has successfully invaded 73 sites, affecting 3311 ha of marine intertidal habitat, which if allowed to solidly fill, would equal 400ha. Invasion and control both depend on habitat type. Mudflats and low salinity marshes have significantly more solid area of S. anglica than do high salinity marshes and cobble beaches. Control efforts since 1997 have resulted in a 13% decline of the grass. We find that high salinity marshes have the greatest decline ( 70%), low salinity marshes have the lowest decline ( 10%), and mudflat ( 29%) and cobble beaches ( 21%) have intermediate losses. We hypothesize that invasion success and control are dependent on a relatively complex interplay between habitat physical conditions and species interactions. 相似文献