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1.
This study aimed to investigate the effects of selenium on the ion profiles in the heart, liver, spleen, and kidney through the oral administration of hexavalent chromium. Approximately 22.14 mg/kg b.w. K2Cr2O7 was added to water to establish a chronic poisoning model. Different selenium levels (0.00, 0.31, 0.63, 1.25, 2.50, and 5.00 mg Na2SeO3/kg b.w.) around the safe dose were administered to the experimental group model. Ca, Mg, Mn, Fe, Cu, and Zn were detected in the organs through flame atomic absorption spectrometry after these organs were exposed to K2Cr2O7 and Na2SeO3 for 14, 28, and 42 days. Results showed that these elements exhibited various changes. Ca contents declined in the heart, liver, and spleen. Ca contents also decreased on the 28th day and increased on the 42nd day in the kidney. Mn contents declined in the heart and spleen but increased in the kidney. Mn contents also decreased on the 28th day and increased on the 42nd day in the liver. Cu contents declined in the heart and spleen. Cu contents increased on the 28th day and decreased on the 42nd day in the liver and kidney. Zn contents declined in the heart and spleen. Zn contents increased on the 28th day and decreased on the 42nd day in the liver and kidney. Fe contents decreased in the heart and liver. Fe contents increased on the 28th day and decreased on the 42nd day in the spleen and kidney. Mg contents did not significantly change in these organs. Appropriate selenium contents enhanced Mn and Zn contents, which were declined by chromium. Conversely, appropriate selenium contents reduced Ca, Fe, and Cu contents, which were increased by chromium. In conclusion, the exposure of chickens to K2Cr2O7 induced changes in different trace elements, and Na2SeO3 supplementation could alleviate this condition.  相似文献   

2.
An association of limnic ostracodes has been discovered in the upper part of the Irbzer Formation, of Maastrichtian age, in the Moroccan Middle-Atlas. A new species is described, Gomphocythere achloujensis nov. sp. Paracandona occitanica, which is very common in terminal Cretaceous non-marine deposits of southern Europe (France, Spain), is found for the first time on the south Tethyan margin.  相似文献   

3.
Ion channels are targets of various antiepileptic drugs. In cerebral presynaptic nerve endings Na+ and Ca2+ channels are particularly abundant, as they control neurotransmitter release, including the release of glutamate (Glu), the most concentrated excitatory amino acid neurotransmitter in the brain. Several pre-synaptic channels are implicated in the mechanism of action of the pro-convulsive agent, 4-aminopyridine (4-AP). In the present study the effects of levetiracetam and other established and newer (vinpocetine) anti-epileptic drugs, as well as of the anti-depressant, sertraline on the increase in Ca2+ induced by 4-AP in hippocampal isolated nerve endings were investigated. Also the effects of some of the anti-seizure drugs on the selective increase in Ca2+ induced by high K+, or on the selective increase in Na+ induced by veratridine were tested. Sertraline and vinpocetine effectively inhibited the rise in Ca2+ induced by 4-AP, which was dependent on the out-in Na+ gradient and tetrodotoxin sensitive. Carbamazepine, phenytoin, lamotrigine and oxcarbazepine inhibited the rise in Ca2+ induced by 4-AP too, but at higher concentrations than sertraline and vinpocetine, whereas levetiracetam, valproic acid and topiramate did not. The three latter antiepileptic drugs also failed in modifying other responses mediated by the activation of brain presynaptic Na+ or Ca2+ channels, including Glu release. This indicates that levetiracetam, valproic acid and topiramate mechanisms of action are unrelated with a decrease in presynaptic Na+ or Ca2+ channels permeability. It is concluded that depolarized cerebral isolated nerve endings represent a useful tool to unmask potential antiepileptic drugs targeting presynaptic Na+ and/or Ca2+ channels in the brain; such as vinpocetine or the anti-depressant sertraline, which high effectiveness to control seizures in the animal in vivo has been demonstrated.  相似文献   

4.
5.
A short review of investigations along a new line: the antiamyloid action of fullerenes C60 and correction of disturbed cognitive processes is presented. The prospects for the development of drugs based on fullerenes acting on the key molecular mechanisms at the early stage of Alzheimer’s disease are discussed.  相似文献   

6.
The Grosse Badlhöhle (Austria, Steiermark) is the origin of one of the most perfect bone points of the early Aurignacian and one of the best perforated femurs of the same period, which can be regarded as musical instruments. Two other fragments of points raise intriguing questions on the first Homo sapiens sapiens which cannot be solved today but will contribute to future research. A review on the debate of Palaeolithic flutes will follow with experimental proofs of boring artificial holes with high quality pictures on the blow-hole and the lack of gnawing traces on the opposite face. The musical possibility of an instrument with only one hole is discussed with ethnographic analogies. Hafting, optimal conditions of strength and possible use of arrows will close the discussion on the Badlhöhle bone artefacts.  相似文献   

7.
Neolithization through karstic rocky territories from Eastern Maghreb is supported by a special form of pastoralism. Between 7000-5000 BP, a prominent sheep and goat animal husbandry represents a shepherd’ permanent objective, while domestic cattle seems to play a saving role. Aurès reaches allowed us to study a global shepherd living, initiated by small groups, labelled as Neolithic of Capsian Tradition, stricto sensu (NCT). A new approach focuses here on non local archaeological finds from the Capéletti cave, a residential key-site located on the slopes of the Khanguet Si Mohamed Tahar amphitheatre (1540m), gives the lead to explore a winter lowland transhumance behaviour, which was a yearly extension of a summer upland behaviour. Through synchronized data, selected among exotic cultural documents, such as polished stone axes and adzes; marine and ivory-ornaments; and lowland botanic remains from marshes, such as elements of a steppic and salted vegetation, trapped inside sheep fleece, new evidences emerged which were linked, then, with new data based on flocks evaluation as alive animals. This study gives precision on:
the shepherd’s long term objective;
the initial and natural animal husbandry which moved, through an empirical management, on an increasing and controlled sheep, goat and cattle breeding;
the non local cultural goods broad-spectrum, coveted by the shepherds;
the flock meat/animal goods, coveted by peddling nomadic people;
the exchange act and its conventions;
how and when vanished epipaleolithic traditions of this NCT facies, through shepherds’ deliberate and progressive exchanges;
and how and when, outside farming process, might have appeared, on lowlands and hilly areas, a typical open countryside landscape, strictly linked with this ongoing pastoralism.
This first local Status of the Shepherd which was the main objective of this neolithization may have settled and spread out through Maghreb territories, an Atlasic Pastoral Society.  相似文献   

8.
The amber of Le Mas d’Azil (Ariège, France), fashioned by the Magdalenian people of Le Mas d’Azil cave, was collected in clay levels rich in Cupressinoxylon Göppert, of the Campanian Labarre Sandstone Formation, which is a large deltaic set, infilling the sub-Pyreneean trough. The amber pieces are small and resemble modern resin exudates on coniferous trunks. We describe following micro-inclusions. Actinomycetes: Cardonia stellata, nov. gen., nov. sp., located close to the surface of amber pieces, is abundant and displays chains of conidia and isolated aleuriospore. Nocardiopsis ? sp. D is rare. Actinomycete “de type Salignac” is abundant. Its filaments often display a tendril shape, which seems to prelude to a mycelium fragmentation. Other bacteria: Leptotrichites resinatus Schmidt ( Schmidt and Schäfer, 2005), poorly represented, is more variable than the already known material; cf. Sphaerotilus sp., very abundant, also displays differences with the Cenomanian “Sphaerotilus sp.”. Eukaryotes: one fungal filament, and a group of spores, pollens or cysts. Inorganic inclusions: gas bubbles, pseudo-protists of B and C? types, and tiny, transparent, cubic crystals. It seems that most of the quoted prokaryotes were resinicolous organisms, able to settle on the surface of the exudate, and grow in the resin, after inoculation either by a contact with the substrate, or by an anemophilic dispersion of spores. This “taphonomic way” seems here to be more general than trapping.  相似文献   

9.
Thirty-four species of ostracodes are collected in the platform series of the Southern Corbières; two biostratigraphical assemblages, with 13 and 29 species, are respectively recognized in Cenomanian and Upper Turonian; palaeoecology is specified. At that time, the ostracode sub-province of South-West France, established on Southern Corbières, Aquitaine, Touraine-Poitou-Charentes region and Provence, is connected with Eastern and Northern regions and countries: Sub-alpines ranges, Paris Basin, Great Britain, Switzerland and Bohemia, and with the Iberian Peninsula, sub-province of North-Central Spain and Western Portuguese Basin. The crossing of the Tethys and the Atlantic Ocean is realized, in Turonian, by some rare species.  相似文献   

10.
Ostracode assemblages, collected in the continental “Red Beds” of the Central High Atlas, Morocco, consist of 35 species, belonging to 17 genera, four of which are new and described herein. They allow to assign the lower member of the Iouaridène formation to the Upper Jurassic (?)-Upper Hauterivian and the Jbel Sidal formation to the Upper Hauterivian-Lower Aptian. Ostracode assemblages characterize lacustrine (freshwater) and lagoonal (oligo to mesohaline) environments. On the basis of limnic and lagoonal species, faunal connections are proposed for the Barremian-Aptian between Morocco and the Iberian Peninsula.  相似文献   

11.
With the rising demand for flexible and wearable electronic devices, flexible power sources with high energy densities are required to provide a sustainable energy supply. Theoretically, rechargeable, flexible Li‐O2/air batteries can provide extremely high specific energy densities; however, the high costs, complex synthetic methods, and inferior mechanical properties of the available flexible cathodes severely limit their practical applications. Herein, inspired by the structure of human blood capillary tissue, this study demonstrates for the first time the in situ growth of interpenetrative hierarchical N‐doped carbon nanotubes on the surface of stainless‐steel mesh (N‐CNTs@SS) for the fabrication of a self‐supporting, flexible electrode with excellent physicochemical properties via a facile and scalable one‐step strategy. Benefitting from the synergistic effects of the high electronic conductivity and stable 3D interconnected conductive network structure, the Li‐O2 batteries obtained with the N‐CNTs@SS cathode exhibit superior electrochemical performance, including a high specific capacity (9299 mA h g?1 at 500 mA g?1), an excellent rate capability, and an exceptional cycle stability (up to 232 cycles). Furthermore, as‐fabricated flexible Li‐air batteries containing the as‐prepared flexible super‐hydrophobic cathode show excellent mechanical properties, stable electrochemical performance, and superior H2O resistibility, which enhance their potential to power flexible and wearable electronic devices.  相似文献   

12.
Contryphans are bioactive peptides, isolated from the venom of marine snails of the genus Conus, which are characterized by the short length of the polypeptide chain and the high degree of unusual post‐translational modifications. The cyclization of the polypeptide chain through a single disulphide bond, the presence of two conserved Pro residues, and the epimerization of a Trp/Leu residue confer to Contryphans a stable and well‐defined structure in solution, conserved in all members of the family, and tolerant to multiple substitutions. The potential of Contryphans as scaffolds for the design of redox‐active (macro)molecules was tested by engineering a copper‐binding site on two different variants of the natural peptide Contryphan‐Vn. The binding site was designed by computational modeling, and the redesigned peptides were synthesized and characterized by optical, fluorescence, electron spin resonance, and nuclear magnetic resonance spectroscopy. The novel peptides, named Cupryphan and Arg–Cupryphan, bind Cu2+ ions with a 1:1 stoichiometry and a Kd in the 100 nM range. Other divalent metals (e.g., Zn2+ and Mg2+) are bound with much lower affinity. In addition, Cupryphans catalyze the dismutation of superoxide anions with an activity comparable to other nonpeptidic superoxide dismutase mimics. We conclude that the Contryphan motif represents a natural robust scaffold which can be engineered to perform different functions, providing additional means for the design of catalytically active mini metalloproteins.  相似文献   

13.
The results of published and unpublished experiments investigating the impacts of elevated [CO2] on the chemistry of leaf litter and decomposition of plant tissues are summarized. The data do not support the hypothesis that changes in leaf litter chemistry often associated with growing plants under elevated [CO2] have an impact on decomposition processes. A meta-analysis of data from naturally senesced leaves in field experiments showed that the nitrogen (N) concentration in leaf litter was 7.1% lower in elevated [CO2] compared to that in ambient [CO2]. This statistically significant difference was: (1) usually not significant in individual experiments, (2) much less than that often observed in green leaves, and (3) less in leaves with an N concentration indicative of complete N resorption. Under ideal conditions, the efficiency with which N is resorbed during leaf senescence was found not to be altered by CO2 enrichment, but other environmental influences on resorption inevitably increase the variability in litter N concentration. Nevertheless, the small but consistent decline in leaf litter N concentration in many experiments, coupled with a 6.5% increase in lignin concentration, would be predicted to result in a slower decomposition rate in CO2-enriched litter. However, across the assembled data base, neither mass loss nor respiration rates from litter produced in elevated [CO2] showed any consistent pattern or differences from litter grown in ambient [CO2]. The effects of [CO2] on litter chemistry or decomposition were usually smallest under experimental conditions similar to natural field conditions, including open-field exposure, plants free-rooted in the ground, and complete senescence. It is concluded that any changes in decomposition rates resulting from exposure of plants to elevated [CO2] are small when compared to other potential impacts of elevated [CO2] on carbon and N cycling. Reasons for experimental differences are considered, and recommendations for the design and execution of decomposition experiments using materials from CO2-enrichment experiments are outlined.  相似文献   

14.
In this paper Coccocarpia tomentosa, from Misiones, Argentina, is described and illustrated. Comments on five related species also known from Paraguay and Brazil are included. The known distribution of C. pellita is extended and it is cited for the first time from Argentina.  相似文献   

15.
Sprouts of potato tubers were excised from the three potato cultivars Agria, Hermes, and Spunta, sterilized and subjected to shoot formation and propagation on Murashige and Skoog (MS) medium supplemented with 1 mg dm-3 6-benzylaminopurine (BAP) + 0.5 mg dm-3 gibberellic acid. Shoots were rooted on MS medium supplemented with 1 mg dm-3 indole-3-butyric acid. To increase shoot vigour prior tuber formation, shoots were subcultured on MS medium supplemented with 0.56 mg dm-3 BAP, 0.11 mg dm-3 2,4-dichlorophenoxyacetic acid, and 0.96 mg dm-3 naphthaleneacetic acid. Under dark, microtuberization on MS media supplemented with 4 mg dm-3 of both BAP and kinetin was better than 4 mg dm-3 BAP alone, where they induced higher number of microtubers per shoot and/or the percentage of shoots that formed microtubers. The highest frequency of microtuber formation was achieved when sucrose at high concentration (8 %) was used as carbon source in culture media. Glucose ranked at the second position whereas fructose reduced the microtuber formation frequency when it was used alone or in combination with glucose. Under the applied culture conditions, cvs. Agria and Hermes showed better micropropagation and microtuberization in comparison to cv. Spunta. In addition, isozyme and RAPD techniques revealed that Agria and Hermes are closer to each other when compared with the third cultivar.  相似文献   

16.
Few studies have experimentally investigated the influence of competition for light on structure and composition of wetland vascular plant communities, despite the well-documented high productivity in such systems. Influences of the dominant emergent wetland plant Juncus effusus on the surrounding macrophyte community were evaluated in a shallow freshwater wetland through two consecutive growing seasons. Permanent transects were constructed along diagonals of randomly oriented 1 m2 plots centered around isolated, colonizing J. effusus tussocks. Percent areal cover was measured for each species or identifiable taxon group in 400 cm2 sub-plots centered 10, 20, 30, and 40 cm from the tussock edge, to evaluate species richness, diversity, and dominance indices. Observational studies during the first growing season indicated that plots having larger, more heavily shading tussocks yielded significantly lower cover and species richness in the surrounding plant community than less shaded plots. Shading by J. effusus was reduced experimentally during the second growing season by holding culms in a vertical position in half of the J. effusus-occupied study plots in order to assess directly the influence of shading by J. effusus. Manipulated plots became more diverse and species-rich and developed higher total percent areal cover. Within shaded reference plots, reductions in cover, richness, and diversity were correlated with intensity of shading; each of these measures was lowest in sub-plots centered 10 cm from the tussock, where measured light reduction was highest. Neighborhood analyses of biomass, species composition, and light reduction indicated that individual species biomass varied with distance from J. effusus tussocks and shading intensity, an indication of the potential for shifts in community composition as populations of this dominant macrophyte expand to fill a wetland area. A mathematical model is presented to illustrate shading effects of J. effusus as a population grows from isolated, colonizing tussocks to an interacting system of tussocks in an established population of this dominant macrophyte.  相似文献   

17.
Synopsis The longheaded eagle ray, Aetobatus flagellum, has recently increased significantly in numbers in Ariake Sound. It is assumed that it feeds on bivalves and so, to prevent predation by eagle rays on bivalves, a ‘predator control program’ aimed at reducing the ray population has been in place since 2001. We examined their occurrence, age, growth and food in Ariake Sound to obtain data on the ecology of the eagle ray and provide basic information on their potential impact on bivalve stocks in Ariake Bay. The eagle ray is a seasonal visitor to Ariake Sound, increasing in numbers from April, and peaking during the summer. None were captured during surveys in December and February. Their movement pattern around the bay differed according to sex. Pregnant females were caught in the estuary during August and September. Females grew to a larger size than males and apparently lived longer. The maximum ages were 19 years for females and 9 years for males. Growth until two years was similar in both sexes, but after 2 years females grew larger. The eagle ray fed only on bivalves, especially Ruditapes philippinarum and Atrina pectinata, very important fishery species farmed in Ariake Bay.  相似文献   

18.
Ultrasonic telemetry was used to analyze the effects of environmental variables on movement directions and movement rates of brown smoothhounds, Mustelus henlei, in Tomales Bay, California. Ultrasonic transmitters were surgically implanted in the peritoneal cavities of one male and five female brown smoothhounds and tracked during the period of 29 June to 15 July 2004. Coarse-scale tracking consisted of locating all tagged individuals multiple times during a single session, while fine-scale tracking consisted of following a single individual continuously during a session. Coarse-scale tracking suggested movement toward the inner bay with incoming and high tides and toward the outer bay with outgoing and low tides (P = 0.01), whereas the diel cycle had no apparent effect on their movement directions. Mean shark movement rate was 0.09 m s−1 (range: 0.01–0.34 m s−1), with diel and tidal cycles both having significant effects on their rates of movement (P = 0.02 and P < 0.01), respectively. We tracked two female sharks on a fine scale over three tracking sessions in July 2004. Both individuals exhibited higher rates of movement during the night compared to the day (P < 0.01). While one shark’s rate of movement was not significantly affected by tidal stage, the other’s was (P < 0.001).  相似文献   

19.
Bythotrephes longimanus is an invertebrate predator that has invaded the North American Great Lakes and a number of inland lakes, where it preys on crustacean zooplankton. We examined the effect of Bythotrephes on two measures of ecosystem function during a four-month observational study of freshwater lakes on the boreal shield. Bythotrephes-invaded lakes had significantly lower epilimnetic zooplankton abundance and production compared to reference lakes. On average, Bythotrephes consumed 34% of zooplankton production when it was present in lakes. There was some evidence of changes in the timing of zooplankton production, as well as shifts to cooler, less productive habitats, which may lessen the overall effect of the invader on the transfer of energy to higher trophic levels. We experimentally demonstrated a weak trophic cascade where invader predation reduced zooplankton biomass, and subsequently increased phytoplankton growth. However, the response was small in magnitude and not biologically relevant at the whole lake-scale. The most conspicuous effect of Bythotrephes that we measured was a diversion of energy away from native predators at higher trophic levels. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

20.
The larvae of Curteria episcopalis (C.L. Koch, 1837) and Curteria southcotti Gabryś, 1992, are described based on specimens reared in the laboratory. Pedroerythraeus Haitlinger, 2004 is considered a junior synonym of Curteria. Data on habitat specificity and phenology of the species as well as on development of eggs into larvae are given.  相似文献   

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