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1.
Heavy metals in Antarctic organisms 总被引:8,自引:1,他引:7
To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms
from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates
and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit
was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod
Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals
in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals
were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather
baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental
changes.
Received: 17 July 1995/Accepted: 11 April 1996 相似文献
2.
Antarctic and sub-Antarctic benthic invertebrates are subjected to intense predation by mobile macroinvertebrates. Accordingly, chemical protection as well as other defensive mechanisms are expected to be common in organisms inhabiting these ecosystems. In order to evaluate anti-predation activities and allocation of chemical defenses within the anatomy of marine benthic Antarctic and sub-Antarctic invertebrates, 55 species were tested for feeding repellence against the sea star Odontaster validus, a common eurybathic sympatric predator. The invertebrates tested were collected from the deep waters of two poorly surveyed areas in terms of chemical ecology studies: the eastern Weddell Sea (Antarctica) and the vicinities of Bouvet Island (sub-Antarctica). Experiments were conducted at the Spanish Antarctic Base in Deception Island. In the feeding deterrence experiments, shrimp pieces were treated with crude lipophilic fractions obtained from each species, and were offered to the sea stars. A total of 29 species (53 %) from 7 different phyla (Porifera, Cnidaria, Chordata, Bryozoa, Echinodermata, Mollusca, and Annelida) showed feeding repellence against O. validus, and are therefore chemically protected against this keystone predator. Furthermore, 25 species were dissected into parts to investigate the possible allocation of defensive compounds. Some of the results obtained from these analyses support the prediction that the most exposed/vulnerable tissues concentrate chemical defenses to avoid predation against the sea stars. In summary, the results obtained in our survey support the hypothesis that deep-water Antarctic and sub-Antarctic benthic invertebrates are well protected chemically against sympatric predators, similarly to what has been reported in previous studies investigating shallow-water Antarctic species. 相似文献
3.
A comparative study of high molecular weight proteins in various types of muscle across the animal kingdom 总被引:9,自引:0,他引:9
A wide range of phyla have been surveyed by SDS-PAGE for the new large proteins of the myofibril. Connectin (or titin) appears to be widely distributed. It is seen as a band of constant intensity and mobility in vertebrate striated muscle, but is absent from smooth muscle. It appears in more variable amounts, in a form of constant but greater mobility in many invertebrates: worms, molluscs (adductor but not gastropod feet), insects, a myriapod, and even in human blood platelets. Nebulin shares the same distribution in vertebrate muscles except for its notable absence in all heart muscle examined. It too is found in many invertebrates, not always with titin. It has been found in a worm, molluscs (adductor and gastropod feet), insects, crustaceans and an echinoderm. The mobility of nebulin varies within the vertebrates and more so between invertebrates (where, as with titin, it is greater). The isoforms of filamin in skeletal, cardiac, and smooth muscles of vertebrates are recorded. C-protein in rabbit muscles has four isoforms: white, alpha-red (X-protein), beta-red, and cardiac. 相似文献
4.
Scott L. Applebaum David W. Ginsburg Charles S. Capron Donal T. Manahan 《Polar Biology》2013,36(9):1257-1267
Epithelial cells in the body wall of adult and developmental stages of marine invertebrates absorb dissolved organic material directly from seawater. Despite over a century of study, little is known about the molecular biological mechanisms responsible for this transport process. Previous studies on embryonic and larval Antarctic echinoderms show that amino acid uptake could provide an important supplement of metabolic substrates. In the present study, partial cDNA sequences of 11 putative amino acid transporter genes were isolated from six species of Antarctic echinoderms including the Antarctic sea stars Acodontaster hodgsoni, Diplasterias brucei, Odontaster meridionalis, Odontaster validus, and Perknaster fuscus, and the Antarctic sea urchin Sterechinus neumayeri. Conserved domains of cDNA-deduced amino acid sequences characterized these genes as being members of a family of amino acid transporters (solute carrier family 6). Expression of these genes was detected throughout embryonic and larval development of two species that have contrasting developmental modes (A. hodgsoni: lecithotrophic; O. meridionalis: planktotrophic). In all six species studied, the expression of amino acid transporter genes was detected in tube feet and digestive organs of adult animals, demonstrating that members of a single amino acid transporter gene family are expressed during the entire life history of a marine invertebrate. The identification of these genes is an important step toward developing a mechanistic understanding of amino acid transport capacities in Antarctic marine invertebrates. 相似文献
5.
Members of the HSP70 gene family comprising the inducible (HSP70) genes and GRP78 (glucose-regulated protein 78 kDa) were
identified in an Antarctic sea star (Odontaster validus) and an Antarctic gammarid (Paraceradocus gibber). These genes were surveyed for expression levels via Q-PCR after an acute 2-hour heat shock experiment in both animals and
a time course assay in O. validus. No significant up-regulation was detected for any of the genes in either of the animals during the acute heat shock. The
time course experiment in O. validus produced slightly different results with an initial down regulation in these genes at 2°C, but no significant up-regulation
of the genes either at 2 or 6°C. Therefore, the classical heat shock response is absent in both species. The data is discussed
in the context of the organisms’ thermal tolerance and the applicability of HSP70 to monitor thermal stress in Antarctic marine
organisms. 相似文献
6.
Anna Kidawa Katarzyna Stepanowska Marta Markowska Stanisław Rakusa-Suszczewski 《Polar Biology》2008,31(4):519-525
Chemical cues released from dead or injured organisms constitute important signals informing nearby animals about a feeding
possibility. The ability to detect the signal, evaluate its meaning and locate its source can help organisms to exploit food
resources efficiently, which is especially important to animals living in environments with limited food supply. Experiments
were carried out to study the behavioral responses of several Antarctic benthic invertebrates to fish (Notothenia corriceps) blood. Necrophagous species such as sea stars Odontaster validus and Lysasterias sp., amphipod Waldeckia obesa and nemertean Parborlasia corrugatus responded to fish blood with changes in their behavior. The behavior common to all these species was locomotion directed
towards the stimulus source. Behavioral components consistent with food consumption were observed in O. validus and P. corrugatus. The reaction of herbivorous limpets Nacella concinna to fish blood depended on the animal size. Large (>10 mm) limpets showed no behavioral response, whereas small ones (<10 mm)
reacted to the stimulus by moving a short distance away. These results indicate that blood released from the tissues of injured
or dead animals may be an important chemical signal for organisms belonging to different taxa. 相似文献
7.
Behavioural and metabolic responses of the Antarctic sea star Odontaster validus to food stimuli of different concentration 总被引:1,自引:0,他引:1
Anna Kidawa 《Polar Biology》2005,28(6):449-455
Experiments were carried out to study the behavioural and metabolic responses of the Antarctic sea star, Odontaster validus, to different concentration of food signals (glutamic acid, aspartic acid, glicyne, alanine, tyrosine and a mixture of 11 amino acids). Stimulus concentration increase caused a rise in both the percentage of reacting animals and in the reaction intensity. At low stimulus concentration, O. validus reaction consisted of tube foot waving, and only high concentrations elicited a complicated sequence of several types of behaviour. The metabolic rate of small O. validus was more sensitive to chemical stimuli than of large individuals, with small sea stars reacting even to low signal concentration. It can be speculated that small body size can be a factor restricting sea star capabilities and influencing its reaction to chemical signals. 相似文献
8.
Activities and characteristics of digestive enzymes of polar and subtropical echinoderms are similar. Specific adaptations
to facilitate digestion at low temperature were not observed. Levels of chymotrypsin and β-glucosidase of digestive tissues
of the Antarctic asteroids Odontaster validus and Odontaster meridionalis, and the Antarctic echinoid Sterechinus neumayeri, are comparable to levels of the asteroids Henricia downii and Astropecten articulatus from the Gulf of Mexico. α-Glucosidase activities are similar for S. neumayeri and A. articulatus. The pH of maximal activity is 7.5 for disaccharidases and 8.5–9.5 for chymotrypsin for both polar and subtropical species.
Affinities for substrates were higher at 25°C than at 0°C for disaccharidases of all species. However, Km values for chymotrypsin increased from 0 to 25°C. Lack of sufficient adaptation by polar echinoderms to facilitate digestion
at low temperature may reduce their capacity to digest food.
Received: 24 July 1996 / Accepted: 31 January 1997 相似文献
9.
James B. McClintock Margaret O. Amsler Charles D. Amsler Bill J. Baker 《Polar Biology》2006,29(7):615-623
The sea stars Granaster nutrix and Neosmilaster georgianus are conspicuous members of benthic communities along the Antarctic Peninsula. An analysis of the proximate composition of somatic body components of nonreproductive adults indicates the nutrient storage organs (pyloric caeca) are rich in both protein (60.7 and 60.6% mean dry wt, respectively) and lipid (25.4 and 29.8% mean dry wt, respectively). Body-wall tissues, while containing small inconspicuous skeletal ossicles, are also comprised of significant levels of organic matter (33.5 and 55.7% mean dry wt, respectively), attributable primarily to protein. Both the pyloric caeca and body-wall tissues are relatively rich in energy (mean energy levels=24.8 and 26.5 kJ g−1 dry wt; 8.4 and 14.1 kJ g−1 dry wt, respectively). Despite the availability of these nutrients and energy neither sea star is preyed upon by the sympatric omnivorous sea star Odontaster validus, a common predator of other Antarctic sea stars. Laboratory feeding bioassays indicate that O. validus rejects live intact individuals and body-wall tissues of both sea star species while readily consuming dried krill. Alginate food pellets containing a krill powder and tissue level concentrations of organic methanol extracts of body-wall tissues were also rejected by O. validus. Moreover, the copious mucus released from the body wall of N. georgianus was deterrent in O. validus food pellet bioassays. Thus, both sea stars evidently possess defensive secondary metabolites that defend against predation and are likely to play a role in mediating materials and energy transfer in the Antarctic benthos. 相似文献
10.
R A Murphy 《Federation proceedings》1976,35(6):1302-1306
The contractile systems of vertebrate smooth and striated muscles are compared. Smooth muscles contain relatively large amounts of actin and tropomyosin organized into thin filaments, and smaller amounts of myosin in the form of thick filaments. The protein contents are consistent with observed thin:thick filament ratios of about 15-18:1 in smooth compared to 2:1 in striated muscle. The basic characteristics of both types of contractile proteins are similar; but there are a variety of quantitative differences in protein structures, enzymatic activities and filament stabilities. Biochemical and X-ray diffraction data generally support recent ultrastructural evidence concerning the organization of the myofilaments in smooth muscle, although a basic contractile unit comparable to the sarcomere in striated muscle has not been discerned. Myofilament interactions and contraction in smooth muscle are controlled by changes in the Ca2+ concentration. Recent evidence suggests the Ca2+-binding regulatory site is associated with the myosin in vertebrate smooth muscle (as in a variety of invertebrate muscles), rather than with troponin which is the regulatory protein associated with the thin filament in vertebrate striated muscle. 相似文献
11.
Titin (also known as connectin) is a giant filamentous protein that spans the distance between the Z- and M-lines of the vertebrate muscle sarcomere and plays a fundamental role in the generation of passive tension. Titin has been shown to bind strongly to myosin, making it tightly associated to the thick filament in the sarcomere. Recent observations have suggested the possibility that titin also interacts with actin, implying further functions of titin in muscle contraction. We show — using in vitro motility and binding assays — that native titin interacts with both filamentous actin and reconstituted thin filaments. The interaction results in the inhibition of the filaments' in vitro motility. Furthermore, the titin-thin filament interaction occurs in a calcium-dependent manner: increased calcium results in enhanced binding of thin filaments to titin and greater suppression of in vitro motility. 相似文献
12.
The fine structure of the tergo-coxal muscle of the cockroach, Leucophaea maderae, has been studied with the electron microscope. This muscle differs from some other types of insect flight muscles inasmuch as the ratio of thin to thick filaments is 4 instead of the characteristic 3. The cockroach flight muscle also differs from the cockroach femoral muscle in thin to thick filament ratios and diameters and in lengths of thick filaments. A comparison of these latter three parameters in a number of vertebrate and invertebrate muscles suggests in general that the diameters and lengths of the thick filaments and thin to thick filament ratios are related. 相似文献
13.
Andrew R. Mahon Charles D. Amsler James B. McClintock Bill J. Baker 《Polar Biology》2002,25(6):469-473
The Antarctic limpet, Nacella concinna, has the ability to escape predation by the predatory sea star, Neosmilaster georgianus. When the sea star comes into contact with the limpet, the limpet undergoes characteristic behaviors that include extension of its pallial tentacles, raising its shell in a mushroom-like fashion, rotation, and flight. These behaviors were not observed until the sea star physically contacted the limpets and were not induced by the omnivorous sea star, Odontaster validus, which occupies the same habitats as Ne. georgianus. Crude hydrophilic extracts from Ne. georgianus, but not from O. validus, induced the escape behaviors, indicating that this response is chemical as well as tactile. These putative escape behaviors displayed by Na. concinna may contribute to avoidance of predation by Ne. georgianus. 相似文献
14.
Native myosin filaments from scallop striated muscle fray into subfilaments of approximately 100-A diameter when exposed to solutions of low ionic strength. The number of subfilaments appears to be five to seven (close to the sevenfold rotational symmetry of the native filament), and the subfilaments probably coil around one another. Synthetic filaments assembled from purified scallop myosin at roughly physiological ionic strength have diameters similar to those of native filaments, but are much longer. They too can be frayed into subfilaments at low ionic strength. Synthetic filaments share what may be an important regulatory property with native filaments: an order-disorder transition in the helical arrangement of myosin cross-bridges that is induced on activation by calcium, removal of nucleotide, or modification of a myosin head sulfhydryl. Some native filaments from scallop striated muscle carry short "end filaments" protruding from their tips, comparable to the structures associated with vertebrate striated muscle myosin filaments. Gell electrophoresis of scallop muscle homogenates reveals the presence of high molecular weight proteins that may include the invertebrate counterpart of titin, a component of the vertebrate end filament. Although the myosin molecule itself may contain much of the information required to direct its assembly, other factors acting in vivo, including interactions with accessory proteins, probably contribute to the assembly of a precisely defined thick filament during myofibrillogenesis. 相似文献
15.
Egg lipid and protein content of different females of Antarctic echinoderms in McMurdo Sound, Antarctica, were measured to
assess variation among females and developmental success. Egg triacylglycerol content of the Antarctic sea urchin Sterechinus neumayeri, when less than 70 ng, correlated with embryos that failed to develop past the 4-day-old blastula stage. In contrast asteroids
(Odontaster meridionalis, O. validus, Acodontaster hodgsoni) all produced eggs that developed normally, even with variable egg lipid content. This difference might be related to dietary
sources for more herbivorous sea urchins compared to more omnivorous and predatory asteroids. Low egg lipid content, with
resulting poor embryonic survivorship, suggests that herbivorous sea urchins may be under unusual levels of nutritional stress
in McMurdo Sound during the time frame studied (2004–2005). This nutritional stress might be related to the presence of large
icebergs, known to have reduced primary production in the Ross Sea area. 相似文献
16.
Identification and localization of high molecular weight proteins in insect flight and leg muscle. 总被引:14,自引:3,他引:11
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A Lakey C Ferguson S Labeit M Reedy A Larkins G Butcher K Leonard B Bullard 《The EMBO journal》1990,9(11):3459-3467
Thick and thin filaments in asynchronous flight muscle overlap nearly completely and thick filaments are attached to the Z-disc by connecting filaments. We have raised antibodies against a fraction of Lethocerus flight muscle myofibrils containing Z-discs and associated filaments and also against a low ionic strength extract of myofibrils. Monoclonal antibodies were obtained to proteins of 800 kd (p800), 700 kd (p700), 400 kd (p400) and alpha-actinin. The positions of the proteins in Lethocerus flight and leg myofibrils were determined by immunofluorescence and electron microscopy. p800 is in connecting filaments of flight myofibrils and in A-bands of leg myofibrils. p700 is in Z-discs of flight myofibrils and an immunologically related protein, p500, is in leg muscle Z-discs. p400 is in M-lines of both flight and leg myofibrils. Preliminary DNA sequencing shows that p800 is related to vertebrate titin and nematode twitchin. Molecules of p800 could extend from the Z-disc a short way along thick filaments, forming a mechanical link between the two structures. All three high molecular weight proteins probably stabilize the structure of the myofibril. 相似文献
17.
Smitin, a novel smooth muscle titin-like protein, interacts with myosin filaments in vivo and in vitro.
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Smooth muscle cells use an actin-myosin II-based contractile apparatus to produce force for a variety of physiological functions, including blood pressure regulation and gut peristalsis. The organization of the smooth muscle contractile apparatus resembles that of striated skeletal and cardiac muscle, but remains much more poorly understood. We have found that avian vascular and visceral smooth muscles contain a novel, megadalton protein, smitin, that is similar to striated muscle titin in molecular morphology, localization in a contractile apparatus, and ability to interact with myosin filaments. Smitin, like titin, is a long fibrous molecule with a globular domain on one end. Specific reactivities of an anti-smitin polyclonal antibody and an anti-titin monoclonal antibody suggest that smitin and titin are distinct proteins rather than differentially spliced isoforms encoded by the same gene. Smitin immunofluorescently colocalizes with myosin in chicken gizzard smooth muscle, and interacts with two configurations of smooth muscle myosin filaments in vitro. In physiological ionic strength conditions, smitin and smooth muscle myosin coassemble into irregular aggregates containing large sidepolar myosin filaments. In low ionic strength conditions, smitin and smooth muscle myosin form highly ordered structures containing linear and polygonal end-to-end and side-by-side arrays of small bipolar myosin filaments. We have used immunogold localization and sucrose density gradient cosedimentation analyses to confirm association of smitin with both the sidepolar and bipolar smooth muscle myosin filaments. These findings suggest that the titin-like protein smitin may play a central role in organizing myosin filaments in the contractile apparatus and perhaps in other structures in smooth muscle cells. 相似文献
18.
Phagocytosis was studied in vitro using coelomic fluid of the Antarctic starfish Odontaster validus at 0°C. The number of coelomocytes present was determined and the phagocytic activity of the phagocytic amoebocytes (PA)
was quantified with yeast during incubations of 1 and 2 h. The percentage of PA phagocytosing increased significantly from
42.29 ± 10.50% (SD) at 1 h to 52.57 ± 13.96% at 2 h. Numbers of yeast per PA also rose significantly from 2.27 to 2.45 cells
per amoebocyte, indicating that phagocytic activity was maintained. In vitro phagocytosis of an Antarctic invertebrate at
0°C is shown for the first time, and the types of amoebocytes involved identified. Rates of phagocytosis were similar to,
or higher than, reported data for temperate starfish, although this conclusion must be treated cautiously because of scarcity
of data and differences in methods used. However, the data suggest that phagocytosis in O. validus is well adapted to low temperature.
Accepted: 27 September 1999 相似文献
19.
Alvaro T. Palma Elie Poulin Marcelo G. Silva Roberto B. San Martín Carlos A. Muñoz Angie D. Díaz 《Polar Biology》2007,30(3):343-350
One characteristic pattern found in the marine Antarctic shallow environments is the unusually high proportion of species
with protected and pelagic lecitotrophic development modes. However, species with planktotrophic development generally appear
as the most conspicuous types of organisms in these environments. The Antarctic shallow benthos is considered as one of the
most disturbed in the world, mainly due to the action of ice, thus one could hypothesize that such an environment should favor
organisms with high dispersal capability. In order to test this general hypothesis, for two consecutive summers (2004–2005)
and at two locations, we quantified the abundance and size distribution of most echinoderms present along bathymetric transects.
Our results show the predominance of broadcasters (i.e., Sterechinus neumayeri and Odontaster validus) at a location where disturbances are common, while brooders (e.g., Abatus agassizii) only occurred at shallower depths of the least disturbed location. These results not only corroborate the hypothesis that
local disturbance is an important factor generating these ecological patterns, but also suggest how ice-related disturbances
could represent a major selecting agent behind the patterns of species diversity at an evolutionary scale in Antarctica. 相似文献
20.
J. Layne Myhre Jordan A. Hills Kendal PrillSerene L. Wohlgemuth David B. Pilgrim 《Developmental biology》2014
The sarcomeres of skeletal and cardiac muscle are highly structured protein arrays, consisting of thick and thin filaments aligned precisely to one another and to their surrounding matrix. The contractile mechanisms of sarcomeres are generally well understood, but how the patterning of sarcomeres is initiated during early skeletal muscle and cardiac development remains uncertain. Two of the most widely accepted hypotheses for this process include the “molecular ruler” model, in which the massive protein titin defines the length of the sarcomere and provides a scaffold along which the myosin thick filament is assembled, and the “premyofibril” model, which proposes that thick filament formation does not require titin, but that a “premyofibril” consisting of non-muscle myosin, α-actinin and cytoskeletal actin is used as a template. Each model posits a different order of necessity of the various components, but these have been difficult to test in vivo. Zebrafish motility mutants with developmental defects in sarcomere patterning are useful for the elucidation of such mechanisms, and here we report the analysis of the herzschlag mutant, which shows deficits in both cardiac and skeletal muscle. The herzschlag mutant produces a truncated titin protein, lacking the C-terminal rod domain that is proposed to act as a thick filament scaffold, yet muscle patterning is still initiated, with grossly normal thick and thin filament assembly. Only after embryonic muscle contraction begins is breakdown of sarcomeric myosin patterning observed, consistent with the previously noted role of titin in maintaining the contractile integrity of mature sarcomeres. This conflicts with the “molecular ruler” model of early sarcomere patterning and supports a titin-independent model of thick filament organization during sarcomerogenesis. These findings are also consistent with the symptoms of human titin myopathies that exhibit a late onset, such as tibial muscular dystrophy. 相似文献