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The study aimed to identify the changes of anatomic and microscopic structure and the expression and localization of hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) in the myocardium and coronary artery of the yak heart adapted to chronic hypoxia with aging. Thirty-two yaks (1 day, 6 months, 1 year, 2 years, and 5 year old) were included, and immunoelectronmicroscopy, immunohistochemistry, and enzyme-linked immunosorbent assay (ELISA) were used. Right ventricular hypertrophy was not present in yaks with aging. There was no intima thickening phenomenon in the coronary artery. The ultrastructure of myofibrils, mitochondria, and collagen fibers and the diameter and quantity of collagen changed significantly with aging. The enzymatic activity of complexes I, II, and V increased with age. Immunogold labeling showed the localization of HIF-1α protein in the cytoplasm and nuclei of endothelial cells and cytoplasm of cardiac muscle cells, and VEGF protein in the nuclei and perinuclei areas of smooth muscle cells of coronary artery, and in the cytoplasm and nuclei of endothelial cells. ELISA results showed that HIF-1α secretion significantly increased in the myocardium and coronary artery from an age of 1 day to 2 years of yaks and decreased in old yaks. However, VEGF protein always increased with aging. The findings of this study suggest that 6 months is a key age of yak before which there are some adaptive changes to deal with low-oxygen environment, and there is a maturation of the yak heart from the age of 6 months to 2 years. 相似文献
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Phytochemicals: the good, the bad and the ugly? 总被引:2,自引:0,他引:2
Phytochemicals are constitutive metabolites that enable plants to overcome temporary or continuous threats integral to their environment, while also controlling essential functions of growth and reproduction. All of these roles are generally advantageous to the producing organisms but the inherent biological activity of such constituents often causes dramatic adverse consequences in other organisms that may be exposed to them. Nevertheless, such effects may be the essential indicator of desirable properties, such as therapeutic potential, especially when the mechanism of bioactivity can be delineated. Careful observation of cause and effect, followed by a coordinated approach to identify the responsible entities, has proved extremely fruitful in discovering roles for phytochemical constituents. The process is illustrated by selected examples of plants poisonous to animals and include the steroidal alkaloid toxin of Veratrum californicum (Western false hellebore), piperidine alkaloids of Lupinus species (lupines), and polyhydroxy indolizidine, pyrrolizidine and nortropane alkaloids of Astragalus and Oxytropis species (locoweeds), Castanospermum australe (Moreton Bay chestnut) and Ipomoea species (morning glories). 相似文献
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Peripheral blood and tissue eosinophilia characterize trichinellosis in humans, and present in addition to the increased total IgE levels that occur in many helminth infections. Both processes are the consequence of T-helper 2 activation. Blood and tissue eosinophilia begins with eosinophilopoiesis in the bone marrow, which is followed by the migration of eosinophils through the circulatory system, the eosinophil infiltration of tissues at the inflammatory foci and, finally, degranulation and cell death. Recently, some aspects of eosinophilia caused by Trichinella spiralis infection have been elucidated; however, the protective role of this population of cells against Trichinella parasites remains controversial. Furthermore, when eosinophils are numerous, they can be toxic for host tissues. This review discusses these issues in both human and rodent infection models. 相似文献
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Dr. Neville N. Osborne 《Cell and tissue research》1984,237(3):605-608
Summary The presence of dopamine--hydroxylase (DBH) and phenylethanol-amine-N-methyltransferase (PNMT) immunoreactivity in specific neurones of the snail Helix aspersa has been demonstrated. In addition, high performance liquid chromatography and electrochemical detection have revealed the presence of noradrenaline and adrenaline in the snail central nervous system, although the major catecholamine is dopamine. These results suggest that adrenaline, and perhaps noradrenaline, have transmitter or modulatory functions in the snail nervous system. 相似文献
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Masahiko Idei Keigo Osada Shinya Sato Takeshi Nakayama Tamotsu Nagumo David G. Mann 《Protoplasma》2013,250(4):833-850
The most complete account to date of the ultrastructure of flagellate cells in diatoms is given for the sperm of Thalassiosira lacustris and Melosira moniliformis var. octogona, based on serial sections. The sperm are uniflagellate, with no trace of a second basal body, and possess a 9?+?0 axoneme. The significance of the 9?+?0 configuration is discussed: lack of the central pair microtubules and radial spokes does not compromise the mastigoneme-bearing flagellum’s capacity to perform planar beats and thrust reversal and may perhaps be related to sensory/secretory function of the sperm flagellum during plasmogamy. The basal bodies of diatoms are confirmed to contain doublets rather than triplets, which may correlate with the absence of some centriolar proteins found in most cells producing active flagella. Whereas Melosira possesses a normal cartwheel structure in the long basal body, no such structure is present in Thalassiosira, which instead possesses ‘intercalary fibres’ linking the basal body doublets. No transitional helices or transitional plates are present in either species studied. Cones of microtubules are associated with the basal body and partially enclose the nucleus in M. moniliformis and T. lacustris. They do not appear to be true microtubular roots and may arise through transformation of the meiosis II spindle. A close association between cone microtubules and tubules containing mastigonemes may indicate a function in intracellular mastigoneme transport. No correlation can yet be detected between methods of spermatogenesis and phylogeny in diatoms, contrary to previous suggestions. 相似文献
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The good,the bad and the ugly? 总被引:3,自引:0,他引:3
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Dean Jolliffe 《Economics & Human Biology》2011,9(4):342-355
Contrary to conventional wisdom, NHANES data indicate that the poor have never had a statistically significant higher prevalence of overweight status at any time in the last 35 years. Despite this empirical evidence, the view that the poor are less healthy in terms of excess accumulation of fat persists. This paper provides evidence that conventional wisdom is reflecting important differences in the relationship between income and the body mass index. The first finding is based on distribution-sensitive measures of overweight which indicates that the severity of overweight has been higher for the poor than the nonpoor throughout the last 35 years. The second finding is from a newly introduced estimator, unconditional quantile regression (UQR), which provides a measure of the income-gradient in BMI at different points on the unconditional BMI distribution. The UQR estimator indicates that the strongest relationship between income and BMI is observed at the tails of the distribution. There is a statistically significant negative income gradient in BMI at the obesity threshold and some evidence of a positive gradient at the underweight threshold. Both of these UQR estimates imply that for those at the tails of the BMI distribution, increases in income are correlated with healthier BMI values. 相似文献
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Novel and recurrent mutations in the tyrosinase gene and the P gene in the German albino population 总被引:5,自引:0,他引:5
Albinism is a heterogeneous group of genetic disorders resulting from deficiencies in pigmentation. Clinically, it is divided into ocular (OA) and oculocutaneous albinism (OCA). OCA involves lack of pigment in the skin, hair, and eyes and results from mutations in the tyrosinase gene or in the P gene. OA mainly affects pigmentation in the visual system and may be a mild form of OCA or may be caused by other genetic defects. Clinical diagnosis of albinism type is difficult, because of the observed range of phenotypic variation. Thus, genetic analysis may be helpful with respect to a more accurate diagnosis. Here, we report the mutational profile, determined by genetic analysis of the tyrosinase and P genes, of a large German albino population. We have revealed a total of 42 distinct mutations, 19 of which are novel. Of the 74 unrelated patients screened, 32 (43%) had mutations in the tyrosinase gene, 16 (22%) had P gene mutations, and 26 (35%) patients had no detectable genetic abnormalities. This defines a population of albino patients who are tyrosinase-gene- and P-gene-negative and who thus may represent a good study group for searching for additional genes associated with albinism. 相似文献
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The origin of life and the left-handed amino-acid excess: the furthest heavens and the deepest seas?
The origin of life is an extraordinary problem that leads back to the structure and dynamics of the cosmos and early development of organic molecules. Within that wider question lies an unsolved problem that has troubled biologists for 150 years. What is the origin of the dominant presence of left-handed stereoisomers of amino acids in nature even though their synthesis normally results in an equal mixture of the right- and left-handed molecular forms? We propose that asymmetric Earth rotation caused at dawn and dusk circularly polarized UV light (CPUVL) of opposite polarity and reversed temperature profiles in the oceans. Destruction of the d-isomer by CPUVL at dusk in a sea surface hotter than at dawn created a daily l-isomer excess protected from radiation by nightfall, preserved by down-flow (diffusive, mechanical) into cold, darker regions, eventually initiating an l-amino-acid excess embodied in early marine forms. Innumerable mechanisms have been proposed for the origin of l-chiral dominance in amino acids and none proven. Since the thalidomide tragedy, homochirality of amino acids has been a growing practical issue for medicine. Understanding its origin may bring further and unexpected benefits. It may also be a modest pointer to the possibility of positive answers to whether intelligent life will have the capacity to continue to protect itself from conditions inimical to survival. 相似文献
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Littorals in the in the Exuma Cays, Bahamas and the Bath Plantation, Barbados are comparative in many ways. These edges of
the sea have provided critical services to local people during the time of slavery and since. More than food and medicine,
the littoral is the nightly sea bath, where children are instructed, and the last ecosystem effectively used by the elderly.
Independence and self-respect derive from use and protection of these littoral by individuals and communities. Local patterns
of conservation and use are argued to be essential in the ecological structure and functions of the littoral. Development
projects and marine protected areas alike are seen as potentially breaking local ties with the littoral causing trophic skew
and damaging local society. If development occurs, mitigation solutions potentially derive from legally recognizing local
people as partners in the co-management of their traditional littoral.
相似文献
Richard W. Stoffle (Corresponding author)Email: |
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S. Rodríguez E. H. Navarrete K. Vio C. González K. Schöbitz E. M. Rodríguez 《Cell and tissue research》1999,296(3):457-469
The subcommissural organ (SCO) secretes glycoproteins into the cerebrospinal fluid (CSF) that aggregate and form Reissner's fiber (RF). The factors involved in this aggregation are not known. One factor may be the hydrodynamics of the CSF when flowing through the aqueduct. This hypothesis was tested by isografting rat SCO and xenografting bovine SCO into the lateral ventricle of rats. Xenografts were either fresh bovine SCO or explants cultured for 30 days before transplantation. The grafts were investigated by electron microscopy and immunocytochemistry using antibodies against RF glycoproteins, serotonin and the glucose transporter I. Maximal time of transplantation was 43 days for isografts and 14 days for xenografts. The isografts were not reinnervated but were revascularized; they secreted into the ventricle RF glycoproteins that became progressively packed into pre-RF and RF structures identical to those formed by the SCO in situ. RF was confined to the host ventricle and at its distal end the constituent proteins disassembled. Xenografts were neither reinnervated nor revascularized and secreted into the host ventricle a material that never formed an RF. These findings indicate that the CSF factor responsible for the formation of RF is species specific, and that this process does not depend on the hydrodynamics of the CSF. The blood vessels revascularizing the isografted SCO acquired the characteristics of the vessels irrigating the SCO in situ, namely, a tight endothelium displaying glucose transporter I, and a perivascular space containing long-spacing collagen, thus indicating that basal release of glycoproteins may also occur in the grafted SCO. 相似文献
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Char Ullman 《Ethnos》2015,80(2):223-247
ABSTRACTGiven the harsh environment for Mexican migrants in the US state of Arizona, migrants must think carefully about instantiating their identities in White public space through clothing, bodily movements, and language. This article explores the ways some unauthorized Mexican migrants in Arizona perform belonging to the USA by performing Chicano. Performing Chicano means passing as a US citizen, and migrants’ well-being can depend upon the recognition of those performances. Other unauthorized migrants perform the Supermexicana, to pass as Mexicans who are shopping in the USA, and need to hide the fact that they clandestinely live there. This article examines how some migrants perform a commitment to the USA in public while privately disavowing it, and how others perform a commitment to Mexico that they simply cannot have. This analysis argues that the experiences of unauthorized migrants in the USA can be productively seen through the lens of national performativity. 相似文献
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Mark S. Springer 《Journal of Mammalian Evolution》1997,4(4):285-302
Paleostratigraphic estimates of divergence time for nine independent cladogenic events within Mammalia, ranging from 14 to 130 million years, were regressed against Tamura–Nei-corrected 12S rRNA transversions. Relative rate-adjusted distances were also regressed against paleostratigraphic divergence times. The resulting equations were used to estimate interordinal divergence times within Eutheria and Metatheria for a data set that includes representatives of all orders in each infraclass. Without the adjustment for rate variation, divergence times range from 34 to 156 million years for placental orders, versus 32 to 86 million years for marsupial orders. With rate adjustments, the range of divergence estimates decreases to 53 to 133 million years for placentals versus 40 to 79 million years for marsupials. The effect of rate adjustments is most noticeable for carnivores and perissodactyls, where rates are slow, and proboscideans, where rates are fast. In agreement with studies based on nuclear genes, both unadjusted and rate-adjusted estimates of sequence divergence indicate that the majority of placental orders originated before the terminal Cretaceous extinction. Exceptions include the perissodactyl–carnivore split and cladogenesis among paenungulate orders. Most marsupial orders, in turn, may have originated in the early Tertiary although didelphimorphs, at least, appear to have split from other lineages in the late Cretaceous. Marsupial divergence times based on 12S rRNA data are in good agreement with estimates based on single-copy DNA hybridization and disagree with the suggestion of Hershkovitz (1992) that Dromiciops separated from other marsupials in the Jurassic. 相似文献
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Mediterranean islands (MI) are hotspots of global biodiversity and lie in one of the most susceptible to climate change (CC) areas of the world; a big challenge for any conservation strategy. In fact, there is already increasing evidence for CC in the region and associated biological responses in MI ecosystems. These include phenological changes and upward elevation shifts of species and plant communities; although evidence is frequently contrasting for different taxa. Threats are also evident, mainly for endemic species from most taxonomic groups, while communities in mountain and coastal regions are likely to be affected most. For MI conservation under CC additional factors need to be considered: (i) their position at the crossroads of three continents; with which they share common environmental characteristics, (ii) their great variability in sizes and topography and (iii) their climatic differences; with a clear west-east basin divide. CC synergies with changing tourist aspiration and agricultural practices will, in the medium term, modify island landscapes and provide further challenges for biodiversity conservation. Such a combined impact from CC, land-use change, fragmentation of habitats and tourism is difficult to predict. Furthermore, the limited space on islands (especially habitat availability and climatic range limitations) imposes a barrier to species range expansion. Thus, conservation of MI biodiversity under CC requires: (i) future research to focus on improved climate predictions linked to improved understanding of ecological (climate-biotic) responses, incorporating lessons learnt from (island) biogeography, (ii) specific adaptation measures for spatial planning and improvement in regional institutional capacities. 相似文献
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Knowles TJ Browning DF Jeeves M Maderbocus R Rajesh S Sridhar P Manoli E Emery D Sommer U Spencer A Leyton DL Squire D Chaudhuri RR Viant MR Cunningham AF Henderson IR Overduin M 《EMBO reports》2011,12(2):123-128
Insertion of folded proteins into the outer membrane of Gram-negative bacteria is mediated by the essential β-barrel assembly machine (Bam). Here, we report the native structure and mechanism of a core component of this complex, BamE, and show that it is exclusively monomeric in its native environment of the periplasm, but is able to adopt a distinct dimeric conformation in the cytoplasm. BamE is shown to bind specifically to phosphatidylglycerol, and comprehensive mutagenesis and interaction studies have mapped key determinants for complex binding, outer membrane integrity and cell viability, as well as revealing the role of BamE within the Bam complex. 相似文献
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