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1.
2.
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   

3.
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   

4.
The effects of intraguild interactions between Dicyphus hesperus Knight (Hemiptera: Miridae) and Paecilomyces fumosoroseus Apopka-97 (PFR-97TM) (Wize) Brown and Smith (Ascomycota: Hypocreales) on Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) populations were investigated in tomato greenhouse microcosms. Conditions were established in which interference or synergy would most likely occur; namely, a high number of available whiteflies were combined with large numbers of both D. hesperus and PFR-97TM. We measured live whitefly density in a factorial repeated measures experiment where plants were provided or withheld releases of D. hesperus and/or applications of PFR-97TM for 6 weeks. Releases of D. hesperus were made at a rate of 10 adults/plant during the first and third week and PFR-97TM suspensions were applied with a backpack sprayer at a rate of 18 × 107, 1.3 × 107 and 1.2 × 107 viable blastospores/ml during the first, third and fourth week, respectively. Results revealed a non-significant interaction effect between D. hesperus and PFR-97TM, indicating that their actions were independent. Individual whitefly reductions of 48% and 35% were achieved by PFR-97TM and D. hesperus, respectively. Collectively, the natural enemies reduced whitefly densities by 62% relative to the controls. The density of D. hesperus adults was unaffected by multiple applications of PFR-97TM. These results suggest that the combination of generalist entomopathogenic fungi and generalist predators has the potential to cause increased pest mortality despite evidence of minimal interference.  相似文献   

5.
Verbal play among the Hanunóo of Mindoro is surprisingly similar to that practiced by the Dubliners of Ireland. The similarity invites a comparison of the work habits of their scribes: the ethnographer Harold Conklin and the novelist James Joyce. A Joycean version of an ethnography of the Wannaknow is presented as a textual focus for the comparison.  相似文献   

6.
In the Middle Miocene (approximately 17 to 12 Ma) at least two radiations of fossil apes from East Africa into Eurasia occurred, and, while controversial, some paleoanthropological studies suggest that one of the Eurasian lineages may have returned to Africa to evolve into humans and the African apes. Here, we present a novel argument supporting this hypothesis. Specifically, the global cooling that occurred in the middle Miocene rendered hominoids living in Europe at risk for starvation as seasonal climate change resulted in less availability of fruits during the winter months. During this time, a mutation in uricase occurred in early hominids that resulted in a rise in serum uric acid. Uric acid has been found to potentiate the effect of fructose to increase fat stores, suggesting that the mutation provided a survival advantage. Such a survival advantage would have been less likely to occur in Africa, where the continued presence of tropical rainforests would have been more likely to provide food throughout the year. Furthermore, Miocene apes in Europe were in protected sites where geographic isolation could have allowed the uricase mutation to be rapidly expressed in the entire population. While speculative, we suggest that the uricase mutation supports an extra‐Africa origin of humans.  相似文献   

7.
Chromatin from a uninucleate dinoflagellate, Crypthecodinium cohnii, a binucleate dinoflagellate, Peridinium balticum, and a chromophyte, Olisthodiscus luteus, was examined by nuclease digestion and the results were compared to those from vertebrates. Gel analysis of the products of staphylococcal (micrococcal) nuclease digestion revealed a DNA repeat unit of 220(±5) base pairs for O. luteus and 215(±5) for P. balticum. Limit digestion gave a core particle of 140 base pairs, revealing that these longer repeat sizes are due to longer linker regions. No repeating subunit structure was found upon electrophoresis of digests of C. cohnii nuclei. Examination of the DNA fragments produced by DNAse I digestion of nuclei isolated from P. balticum and O. luteus showed the same ladder of ten base multiples as seen in chromatin from other eukaryotes. Examination of the kinetics of digestion by DNAse II of Peridinium chromatin revealed less susceptibility when compared to DNAse I digestions while 70% of Olisthodiscus chromatin and 35% of C. cohnii chromatin was sensitive to DNAse II. These data, taken together with previous results from Euglena, indicate that while algal chromatin is similar to that of higher eukaryotes in regard to DNAse I and II action, it differs in that the linker DNA is longer. In addition, the Hl-like histone from O. luteus and P. balticum is located in the linker DNA as in higher eukaryotes.  相似文献   

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9.
The actinobacteria are arguably the richest source of small molecule diversity on the planet. These compounds have an incredible variety of chemical structures and biological activities (in nature and in the laboratory). Their potential for the development of therapeutic applications cannot be underestimated. It is suggested that an improved understanding of the biological roles of low molecular weight compounds in nature will lead to the discovery an inexhaustible supply of novel therapeutic agents in the next decade. To support this objective, a functional marriage of biochemistry, genomics, genetics, microbiology, and modern natural product chemistry will be essential.  相似文献   

10.
DNA-damage repair; the good, the bad, and the ugly   总被引:1,自引:0,他引:1  
Hakem R 《The EMBO journal》2008,27(4):589-605
Organisms have developed several DNA-repair pathways as well as DNA-damage checkpoints to cope with the frequent challenge of endogenous and exogenous DNA insults. In the absence or impairment of such repair or checkpoint mechanisms, the genomic integrity of the organism is often compromised. This review will focus on the functional consequences of impaired DNA-repair pathways. Although each pathway is addressed individually, it is essential to note that cross talk exists between repair pathways, and that there are instances in which a DNA-repair protein is involved in more than one pathway. It is also important to integrate DNA-repair process with DNA-damage checkpoints and cell survival, to gain a better understanding of the consequences of compromised DNA repair at both cellular and organismic levels. Functional consequences associated with impaired DNA repair include embryonic lethality, shortened life span, rapid ageing, impaired growth, and a variety of syndromes, including a pronounced manifestation of cancer.  相似文献   

11.
Obesity and diabetes are increasingly attributed to environmental factors, however, little attention has been paid to the influence of the ‘local’ food economy. This paper examines the association of measures relating to the built environment and ‘local’ agriculture with U.S. county-level prevalence of obesity and diabetes. Key indicators of the ‘local’ food economy include the density of farmers’ markets and the presence of farms with direct sales. This paper employs a robust regression estimator to account for non-normality of the data and to accommodate outliers. Overall, the built environment is associated with the prevalence of obesity and diabetes and a strong local’ food economy may play an important role in prevention. Results imply considerable scope for community-level interventions.  相似文献   

12.
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   

13.

Background  

Polypodium hydriforme is a parasite with an unusual life cycle and peculiar morphology, both of which have made its systematic position uncertain. Polypodium has traditionally been considered a cnidarian because it possesses nematocysts, the stinging structures characteristic of this phylum. However, recent molecular phylogenetic studies using 18S rDNA sequence data have challenged this interpretation, and have shown that Polypodium is a close relative to myxozoans and together they share a closer affinity to bilaterians than cnidarians. Due to the variable rates of 18S rDNA sequences, these results have been suggested to be an artifact of long-branch attraction (LBA). A recent study, using multiple protein coding markers, shows that the myxozoan Buddenbrockia, is nested within cnidarians. Polypodium was not included in this study. To further investigate the phylogenetic placement of Polypodium, we have performed phylogenetic analyses of metazoans with 18S and partial 28S rDNA sequences in a large dataset that includes Polypodium and a comprehensive sampling of cnidarian taxa.  相似文献   

14.
The first reports of wild caught Australian redclaw crayfish from Mexico, in the states of Morelos and Tamaulipas, are presented. Redclaw crayfish were first brought to Mexico in 1995 to initiate experimental cultures at several research centers. In the following years a number of private ventures started commercial cultures, several of which in the states of Morelos and Tamaulipas are thought to have been the sources for the wild populations recorded in this study. The farms that acted as the original sources have not been operating for at least 2 years. In Morelos, high densities and all size classes of redclaws, including ovigerous females, were captured in natural waterways; whereas in Tamaulipas they were found at four sites occurring in irrigation canals in an agricultural district. The size attained by the wild redclaws, the abiotic conditions in which they were found and the potential for spread within the drainage systems of the Balsas and Tamesi Rivers are discussed.  相似文献   

15.
Abstract: The regional distributions of the G protein β subunits (Gβ1–β5) and of the Gγ3 subunit were examined by immunohistochemical methods in the adult rat brain. In general, the Gβ and Gγ3 subunits were widely distributed throughout the brain, with most regions containing several Gβ subunits within their neuronal networks. The olfactory bulb, neocortex, hippocampus, striatum, thalamus, cerebellum, and brainstem exhibited light to intense Gβ immunostaining. Negative immunostaining was observed in cortical layer I for Gβ1 and layer IV for Gβ4. The hippocampal dentate granular and CA1–CA3 pyramidal cells displayed little or no positive immunostaining for Gβ2 or Gβ4. No anti-Gβ4 immunostaining was observed in the pars compacta of the substantia nigra or in the cerebellar granule cell layer and Purkinje cells. Immunoreactivity for Gβ1 was absent from the cerebellar molecular layer, and Gβ2 was not detected in the Purkinje cells. No positive Gγ3 immunoreactivity was observed in the lateral habenula, lateral septal nucleus, or Purkinje cells. Double-fluorescence immunostaining with anti-Gγ3 antibody and individual anti-Gβ1–β5 antibodies displayed regional selectivity with Gβ1 (cortical layers V–VI) and Gβ2 (cortical layer I). In conclusion, despite the widespread overlapping distributions of Gβ1–β5 with Gγ3, specific dimeric associations in situ were observed within discrete brain regions.  相似文献   

16.
17.
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   

18.
A new biozonation is proposed for the Late Carboniferous strata of the northeastern Paraná Basin (São Paulo and Paraná States), based on well-preserved palynological assemblages recovered from outcrops and core samples retrieved from the Itararé Subgroup. Assemblages include forty-nine species of trilete spores and twenty-five pollen species. The oldest biozone, the Ahrensisporites cristatus Interval Zone (AcZ), in the basal portion of the Itararé Subgroup, includes eleven exclusive spore species, and is assigned a Pennsylvanian (late Bashkirian to Kasimovian) age. The overlying proposed biozone, the Crucisaccites monoletus Interval Zone (CmZ), dated late Pennsylvanian (Kasimovian to Gzhelian), ranges approximately from the top of the lower portion to the middle portion of the Itararé Subgroup, bears only one exclusive species of pollen. Both zones are characterized by the dominance of trilete spores and monosaccate pollen grains, including also few taeniate pollen grains. Furthermore, the basal Protohaploxypinus goraiensis Subzone of the Vittatina costabilis Interval Zone (VcZ) is broadly recognized for the first time in the upper portion of the Itararé Subgroup in the northeastern Paraná Basin. This subzone is attributed to the Early Permian (Early Cisuralian), and is characterized by the dominance of monosaccate pollen grains, a significant increase of taeniate grains (mainly Protohaploxypinus spp.), apart from the appearance of polyplicate pollen (Vittatina spp.). Reference sections and the main characteristics of the two new zones (AcZ and CmZ) are presented, along with a preliminary palynological correlation and discussion on their ages.  相似文献   

19.
Schoch, R.R. and Witzmann, F. 2011. Bystrow’s Paradox – gills, fossils, and the fish‐to‐tetrapod transition. —Acta Zoologica (Stockholm) 92 : 251–265. The issue of which breathing mechanism was used by the earliest tetrapods is still unsolved. Recent discoveries of stem tetrapods suggest the presence of internal gills and fish‐like underwater breathing. The same osteological features were used by Bystrow to infer a salamander‐like breathing through external gills in temnospondyl amphibians. This apparent contradiction – here called Bystrow’s Paradox – is resolved by reviewing the primary fossil evidence and the anatomy of the two gill types in extant taxa. Rather unexpectedly, we find that internal gills were present in a range of early crown tetrapods (temnospondyls), based on the anatomy of gill lamellae and location of branchial arteries on the ventral side of gill arch elements (ceratobranchials). Although it remains to be clarified which components are homologous in external and internal gills, both gill types are likely to have been present in Palaeozoic tetrapods – internal gills in aquatic adults of some taxa, and external gills in the larvae of these taxa and in larvae of numerous forms with terrestrial adults, which resorbed the external gills after the larval phase. Future developmental studies will hopefully clarify which mechanistic pathways are involved in gill formation and how these might have evolved.  相似文献   

20.
We present a framework for explaining variation in predator invasion success and predator impacts on native prey that integrates information about predator–prey naïveté, predator and prey behavioral responses to each other, consumptive and non‐consumptive effects of predators on prey, and interacting effects of multiple species interactions. We begin with the ‘naïve prey’ hypothesis that posits that naïve, native prey that lack evolutionary history with non‐native predators suffer heavy predation because they exhibit ineffective antipredator responses to novel predators. Not all naïve prey, however, show ineffective antipredator responses to novel predators. To explain variation in prey response to novel predators, we focus on the interaction between prey use of general versus specific cues and responses, and the functional similarity of non‐native and native predators. Effective antipredator responses reduce predation rates (reduce consumptive effects of predators, CEs), but often also carry costs that result in non‐consumptive effects (NCEs) of predators. We contrast expected CEs versus NCEs for non‐native versus native predators, and discuss how differences in the relative magnitudes of CEs and NCEs might influence invasion dynamics. Going beyond the effects of naïve prey, we discuss how the ‘naïve prey’, ‘enemy release’ and ‘evolution of increased competitive ability’ (EICA) hypotheses are inter‐related, and how the importance of all three might be mediated by prey and predator naïveté. These ideas hinge on the notion that non‐native predators enjoy a ‘novelty advantage’ associated with the naïveté of native prey and top predators. However, non‐native predators could instead suffer from a novelty disadvantage because they are also naïve to their new prey and potential predators. We hypothesize that patterns of community similarity and evolution might explain the variation in novelty advantage that can underlie variation in invasion outcomes. Finally, we discuss management implications of our framework, including suggestions for managing invasive predators, predator reintroductions and biological control.  相似文献   

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