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1.
Transport of reduced nicotinamide–adenine dinucleotide into mitochondria of rat white adipose tissue 总被引:2,自引:0,他引:2
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Mitochondria from rat white adipose tissue were prepared, exhibiting good respiratory control and P/O ratios. They would not oxidize NADH unless NNN'N'-tetramethyl-p-phenylenediamine was added as a carrier of reducing equivalents. These mitochondria were found to oxidize neither l-glycerol 3-phosphate nor l-glutamate plus l-malate at significant rates. The activity of aspartate aminotransferase in these mitochondria was found to be low compared with that found in rat liver mitochondria. As a consequence of this, the adipose-tissue mitochondria exhibited very low rates of cytoplasmic NADH oxidation in a reconstituted Borst (1962) cycle compared with liver mitochondria. 相似文献
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Megan R. Underhill 《Ethnic and racial studies》2018,41(11):1934-1951
This paper examines what white, middle-class parents report saying to their children about racial tension and racial protest when events like Michael Brown’s death and the Ferguson protests are the top news stories. The data come from interviews with forty white, middle-class parents in 2014–15. The study results indicate that few parents recalled speaking with their children about racial tension or racial protest even when such discussions were highly visible in the news and on social media. I argue parents’ silence stemmed from a desire to create a protected, worry-free childhood combined with an inability to understand how such subjects related to their white life. However, not all parents were silent. Twelve participants reported speaking with their children about these subjects via a neutral or a defensive colour-blind frame. Only two participants drew attention to issues of power and privilege. 相似文献
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Summary The effect of increasing concentrations of p,p DDT on dry matter production and nitrogen fixation of white clover (Trifolium repens L.) growing in pots with volcanic soils of the southern region of Chile was studied. The chlorinated insecticides content of the soils ranged from low to very high (>20 mg/kg), being associated with the amount of insecticide applied. A detrimental effect of medium and high levels of DDT on growth, dry matter production and N-accumulation of clover was observed. The effects on nodulation and nitrogenase activity were smaller. These effects were higher when nutrient solutions were used instead of soil, because of the protective effects of soil colloids.
Resumen Se estudió el efecto de concentraciones crecientes de p,p DDT sobre la producción y parámetros de fijación de N del trébol blanco (Trifolium repens L.) en condiciones de invernadero en suelos volcánicos de la zona sur de Chile. Los contenidos de insecticidas clorados de los suelos de la región son desde bajos hasta muy altos (>20 mg/kg), dependiendo de las aplicaciones. Se apreció un efecto depresivo del DDT a dosis medias y altas sobre el crecimiento, producción de materia seca y N-acumulado del trébol y un efecto menor sobre nodulación y actividad nitrogenásica. Estos efectos fueron más acentuados cuando se trabajó con soluciones nutritivas que con suelo, debido a la protección ejercida por los coloides del suelo.
Résumé On a étudié l'effet de concentrations croissantes de p,p-DDT sur la production de matière sèche et sur la fixation de l'azote par le trèfle blanc (Trifolium repens L.) cultivé en serre sur des échantillons de sols volcaniques du sud du Chili. Dans les sols de cette région, la teneur en résidus d'insecticides chlorés varie entre <1 et >20 mg/kg suivant le niveau des prelévements. Le DDT inhibe la croissance, la production de matière sèche et l'accumulation d'azote par le trèfle. De plus, nous avons constaté un effet secondaire sur la nodulation et l'activité nitrogénasique. Ces effets sont plus marqués lorsqu'on utilise des solutions nutritives au lieu de terre, ce qui est dû à une protection éxercée par les colloides du sol.相似文献
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Kang Cheng Howard C. Haspel Mary Lou Vallano Babatunde Osotimehin Martin Sonenberg 《The Journal of membrane biology》1980,56(3):191-201
Summary The accumulation of the lipophilic cation, triphenylmethylphosphonium, has been employed to determine the resting membrane potential in human erythrocytes, turkey erythrocytes, and rat white adipocytes. The triphenylmethylphosphonium cation equilibrates rapidly in human erythrocytes in the presence of low concentrations of the hydrophobic anion, tetraphenylborate. Tetraphenylborate does not accelerate the uptake of triphenylmethylphosphonium ion by adipocytes. The cell associatedvs. extracellular distribution of the triphenylmethylphosphonium ion is proportional to changes in membrane potential. The distribution of this ion reflects the membrane potential determining concentration of the ion with dominant permeability in a Nernst fashion. The resting membrane potentials for the human erythrocyte, turkey erythrocyte, and rat white adipocyte were found to be –8.4±1.3, –16.8±1.1, and –58.3±5.0 mV, respectively, values which compare favorably with values obtained by other methods. In addition, changes in membrane potential can be assessed by following triphenylmethylphosphonium uptake without determining the intracellular water space. The method has been successfully applied to a study of hormonally induced changes in membrane potential of rat white adipocytes. 相似文献
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Ultrastructural characterisation of the host–pathogen interface in white blister-infected Arabidopsis leaves 总被引:3,自引:0,他引:3
Soylu S 《Mycopathologia》2004,158(4):457-464
In this study transmission electron microscopy (TEM) was used to examine details of the host–pathogen interface in Arabidopsis
thaliana cotyledons infected by Albugo candida, causal agent of white blister. After successful entry through stomatal pores, the pathogen developed a substomatal vesicle
and subsequently produced intercellular hyphae. TEM observations revealed that coenocytic intercellular hyphae ramified and
spread intercellularly throughout the host tissue forming several haustoria in host mesophyll cells. Intracellular haustoria
were spherical and 4.5 μm in diameter. Each haustorium was connected to intercellular hyphae by a narrow, slender haustorium neck. The cytoplasm of
the haustorium included the organelles characteristic of the pathogen. No obvious response was observed in host cells following
formation of haustoria. Most of the mesophyll cells contained normal haustoria and the host cytoplasm displayed a high degree
of structural integrity. Absence of host cell wall alteration and cell death in penetrated host cells suggest that the pathogen
exerts considerable control over basic cellular processes and in this respect, response to this biotrophic Oomycete differs
considerably from responses to other pathogens such as necrotrophs. Modification of the host plasma membrane (PM) along the
cell wall and around the haustoria, was detected by applying the periodic acid-chromic acid-phosphotungstic acid (PACP) staining
technique. After staining with PACP, the host PM was found to be intensely electron dense where it was adjacent to the host
cell wall and the distal region of the haustorial neck. By contrast, the extrahaustorial membrane, where the host PM surrounded
the haustorium, was consistently very lightly stained. 相似文献
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Oudin’s principle of single immunodiffusion in agar gel was modified for quantitative determination of IgA in bronchoalveolar lavage (BAL) of normal 20–25 g mice. The reaction took place at 25 °C in 0.3 % agarose with 16.7 % pig serum against mouse IgA, and was evaluated on the basis of a relationship between the progress of the precipitin zone and the square root of time. The linear dependence of the derived constantk on the logarithmic concentration of antibody in the sample permitted to express the results as titre, corresponding to a dilution wherek = 0. Examination of seven samples of pooled blood serum of normal mice shoved taht (1) the IgA level was practically constant, (2) serum IgA possessed under given conditions similar properties as IgA from the bronchoalveolar secretion; it is therefore possible to employ pooled sera as a reliable control of the immunodiffusion system in ease of lack of reference standards with defined IgA content. Examination of 82 individual BAL samples of normal mice revealed that the mean IgA concentration in 2.5 mL samples was almost 1000 times lower than in blood serum. 相似文献
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Pontes ZB Ramos AL Lima Ede O Guerra Mde F Oliveira NM Santos JP 《Memórias do Instituto Oswaldo Cruz》2002,97(5):747-750
White piedra is a superficial mycoses characterized by nodules on the hair shaft, caused by the basidiomycetous yeasts. In the present study, clinical and mycological findings of scalp white piedra caused by Trichosporon spp. are related. Twenty three cases of scalp white piedra were observed with a high incidence in women (87%) and preschool children from 2 to 6 (74%) years old. These groups presented a relationship of dependence with this infection. Despite the low socio-economic status, poor standards of hygiene, (48% of the patients) as well as the fact that 30.4% of the children shared the same nursery, these factors were not significant for the transmission of the mycosis. These were the first reports of scalp white piedra in Jo?o Pessoa city, Paraíba, Brazil. 相似文献
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Dominique Langin 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2010,1801(3):372-376
The role of white and brown adipose tissues in energy metabolism is well established. However, the existence of brown fat in adult humans was until very recently a matter of debate, and the molecular mechanisms underlying brown adipocyte development remained largely unknown. In 2009, several studies brought direct evidence for functional brown adipose tissue in adults. New factors involved in brown fat cell differentiation have been identified. Moreover, work on the origin of fat cells took an unexpected path with the recognition of different populations of brown fat cell precursors according to the anatomical location of the fat depots: a precursor common to skeletal muscle cells and brown adipocytes from brown fat depots, and a progenitor cell common to white adipocytes and brown adipocytes that appear in certain conditions in white fat depots. There is also mounting evidence that mature white adipocytes, including human fat cells, can be converted into brown fat-like adipocytes, and that the typical fatty acid storage phenotype of white adipocyte can be altered towards a fat utilization phenotype. These data open up new opportunities for the development of drugs for obesity and its metabolic and cardiovascular complications. 相似文献
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Matthew W. Hughey 《Ethnic and racial studies》2013,36(8):1289-1309
This article examines the processes of white racial identity formation in the United States via an examination of a white nationalist organization and a white antiracist organization. Findings indicate that the construction of white racial identity in both groups is based on the reproduction of various racist and essentialist ideologies. The realization that there is a shared ‘groupness’ to outwardly different white identities has the potential to destabilize the recent trend that over-emphasizes white heterogeneity at the expense of discussion of power, racism and discrimination. As a resolution to this analytic dilemma, this article advances a conceptual framework entitled ‘hegemonic whiteness’. White identity formation is thereby understood as a cultural process in which (1) racist, reactionary and essentialist ideologies are used to demarcate inter-racial boundaries, and (2) performances of white racial identity that fail to meet those ideals are marginalized and stigmatized, thereby creating intra-racial distinctions within the category ‘white’. 相似文献
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《Biochemical medicine》1984,31(1):73-79
Cross-reacting material (CRM) to human β-d-glucocerebrosidase has been demonstrated in circulating mononuclear white blood cells of normal controls, heterozygotes, and homozygotes for Gaucher's disease. The major CRM in both normal and mutant cells corresponds to a species with Mr ≈ 63,000 Da. Traces of CRM at Mr ≈ 61,000 and 56,000 Da are also present. In contrast, the CRM in other human tissues differs markedly from that found in circulating mononuclear cells. Evidence is presented to support the hypothesis that the CRM found in white cells is a precursor of the enzyme. The significance of these results is discussed in relation to the problems of subtype determination and heterozygote detection. 相似文献
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A few species of Morpho butterflies have a distinctive white stripe pattern on their structurally coloured blue wings. Since the colour pattern of a butterfly wing is formed as a mosaic of differently coloured scales, several questions naturally arise: are the microstructures the same between the blue and white scales? How is the distinctive whiteness produced, structurally or by means of pigmentation? To answer these questions, we have performed structural and optical investigations of the stripe pattern of a butterfly, Morpho cypris. It is found that besides the dorsal and ventral scale layers, the wing substrate also has the corresponding stripe pattern. Quantitative optical measurements and analysis using a simple model for the wing structure reveal the origin of the higher reflectance which makes the white stripe brighter. 相似文献
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Francesca Gherardi Patrizia Acquistapace Silvia Barbaresi 《Marine and Freshwater Behaviour and Physiology》2013,45(3):187-200
As in other benthic decapods, crayfish have chelae that are important for intra‐specific agonistic encounters. In Austropotamobius pallipes, scars and mutilations are present mostly on the chelae, these being the main targets of agonistic contacts. Because males participate in more aggressive interactions than females do and compete with other males for acquiring females in escalating contests, selection for large chelae should be stronger in males. Thus, in A. pallipes (i) chelae are longer, wider and higher in males than in females; (ii) chelar size in males increases allometrically with cephalothorax length; (iii) male specimens are more often deprived of at least one cheliped and (iv) large males have the highest frequency of scars. Males with one regenerated cheliped, when opposed to a competitor with both large chelipeds, display the same motivation to fight, but perform less chelae threat displays than normal crayfish and immediately get a lower hierarchical rank. In these contests, Resource Holding Potential (= chelar size) is highly different between the crayfish and the information of this asymmetry is correctly transferred between the two opponents. 相似文献
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Although roost choice in bats has been studied previously, little is known about how opposing roost colours affect the expression of torpor quantitatively. We quantified roost selection and thermoregulation in a captive Australian insectivorous bat, Nyctophilus gouldi (n=12) in winter when roosting in black and white coloured boxes using temperature-telemetry. We quantified how roost choice influences torpor expression when food was provided ad libitum or restricted in bats housed together in an outdoor aviary exposed to natural fluctuations of ambient temperature. Black box temperatures averaged 5.1 °C (maximum 7.5 °C) warmer than white boxes at their maximum daytime temperature. Bats fed ad libitum chose black boxes on most nights (92.9%) and on 100% of nights when food-restricted. All bats used torpor on all study days. However, bats fed ad libitum and roosting in black boxes used shorter torpor and spent more time normothermic/active at night than food-restricted bats and bats roosting in white boxes. Bats roosting in black boxes also rewarmed passively more often and to a higher skin temperature than those in white boxes. Our study suggests that N. gouldi fed ad libitum select warmer roosts in order to passively rewarm to a higher skin temperature and thus save energy required for active midday rewarming as well as to maintain a normothermic body temperature for longer periods at night. This study shows that colour should be considered when deploying bat boxes; black boxes are preferable for those bats that use passive rewarming, even in winter when food availability is reduced. 相似文献
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Recent studies showed that white spot syndrome virus (WSSV) isolates from different geographic locations share a high genetic
similarity except the variable regions in ORF23/24 and ORF14/15, and variable number of tandem repeats (VNTR) within ORF94.
In this study, genotyping was performed according to these three variable regions among WSSV isolates collected during 1998/1999
from Southern China. These WSSV isolates contain a deletion of 1168, 5657, 5898, 9316 and 11093 bp, respectively in the variable
region ORF23/24 compared with WSSV-TW, and a deletion of 4749 or 5622 bp in the variable region ORF14/15 relative to TH-96-II.
Four types of repeat units (RUs) (6, 8, 9 and 13 RUs) in ORF94 were detected in these isolates, with the shortest 6 RUs as
the most prevalent type. Our results provide important information for a better understanding of the spatio-temporal transmission
mode and the WSSV genetic evolution lineage. 相似文献