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1.
Dialectical Anthropology - The thesis of value neutrality is logically untenable and anthropologically naive. It is logically untenable because it does not attend to contextual (i.e. historical,...  相似文献   

2.
Evidence is presented which supports the concept of a functional membrane barrier in the transition zone at the base of each flagellum of Chlamydomonas eugametos gametes. This makes it unlikely that agglutination factors present on the surface of the cell body can diffuse or be transported to the flagellar membrane. The evidence is as follows: 1) The glycoprotein composition of the flagellar membrane is very different to that of the cell-body plasma membrane. 2) The flagella of gametes treated with cycloheximide, tunicamycin or , -dipyridyl become non-agglutinable but the source of agglutination factors on the cell body is not affected. 3) Even under natural conditions when the flagella are non-agglutinable, for example in vis-à-vis pairs or in appropriate cell strains that are non-agglutinable in the dark, the cell bodies maintain the normal complement of active agglutinins. 4) When flagella of living cells are labeled with antibodies bound to fluorescein, the label does not diffuse onto the cell-body surface. 5) When gametes fuse to form vis-à-vis pairs, the original mating-type-specific antigenicity of each cell body is slowly lost (probably due to the antigens diffusing over both cell bodies), while the specific antigenicity of the flagellar surface is maintained. Even when the flagella of vis-à-vis pairs are regenerated from cell bodies with mixed antigenicity, the antigenicity of the flagella remains matingtype-specific. 6) Evidence is presented for the existence of a pool of agglutination factors within the cell bodies but not on the outer surface of the cells.Abbreviations and symbols CHI cycloheximide - GTC guaniline thiocyanate - mt +/mt - mating type plus or minus - PAS Periodic-acid-Schiff reagent - SDS sodium dodecyl sulphate  相似文献   

3.
A new study of sexual agglutination between Chlamydomonas eugametos gametes and between vis-à-vis pairs has been made using techniques that allow one to distinguish between the flagella or cell bodies of individual mating types (mt+ or mt-). It is shown that before mt+ and mt- gametes fuse in pairs, their flagella, which adhere over their whole length, are maintained in a particular conformation around the mt- cell body. In clumps of agglutinating gametes the cells are asymmetrically distributed with the mt+ gametes constituting the outer surface of the clumps with the mt- gametes on the inside. The flagella are then all directed towards the middle of the clump. This orientation of the flagella is maintained for approx. 8 min after cell fusion before the vis-à-vis pair becomes motile. At this stage, all the flagellar tips are activated. The original mt+ flagellar tips then deactivate and swimming is resumed. The original mt- flagella remain immotile and activated after cell fusion and eventually shorten by a third, but only 30 min or more after fusion. Motile vis-à-vis pairs eventually settle to the substrate when the gamete bodies fuse completely to form a zygote. Settling vis-à-vis pairs are attracted to those that have already settled, to glutaraldehyde-fixed pairs and to flagella isolated from mt- gametes. They are not chemotactically attracted, rather they are weakly agglutinated. Living vis-à-vis pairs can be shown to aggregate in rows with the cell bodies lying side by side. It is argued that the flagellar agglutination sites involved in gamete recognition are also involved in vis-à-vis pair aggregationAbbreviations mt+/- mating type plus or minus - FTA flagellar tip activation  相似文献   

4.
An alteration of the form and ultrastructure of the tips of the flagella of Chlamydomonas eugametos, occurring during sexual agglutination, is shown to be persistent in the mt - flagella of the resulting vis-à-vis pairs. It is argued that this phenomenon is related to the lack of motility of mt - flagella in vis-à-vis pairs of this species.  相似文献   

5.
This essay introduces Christian psychiatrists into the growing literature on Western psychiatry and biomedicine. It seeks to describe specific beliefs and practices of Christian psychiatrists as a means of examining the reality of an ascribed corporate existence, i.e., Christian Psychiatry. Beliefs and practices examined here include conceptions of therapeutic relationships and processes, conceptions of Divinity, Explanatory Models, notions of the nature and sources of healing, self identity, and role relationships of Christian psychiatrists vis-à-vis patients and the wider society. The data suggest that there is no Christian Psychiatry, but only Christian psychiatrists. Implications for patient care and the cultural basis of ideology and practice in psychiatry are also discussed.  相似文献   

6.
Summary The distribution of functions within genomes of higher organisms relative to processes that lead to the spread of mutations in populations is examined in its general outlines. A number of points are enumerated that collectively put in question the concept of junk DNA: the plausible compatibility of DNA function with rapid substitution rates; the likelihood of superimposed functions along much of eukaryotic DNA; the potential for a merely conditional functionality in sequence repeats; the apparent adoption of macromolecular waste as a strategy for maintaining a function without selective grooming of individual sequence repeats that carry out the function; the likely requirement that any DNA sequence must be polite vis-à-vis (compatible with) functional sequences in its genomic environment; the existence in germ-cell lineages of selective constraints that are not apparent in populations of individuals; and the fact that DNA tectonics-the appearance and disappearance of genomic DNA-are not incompatible with function. It is pointed out that the inverse correlation between functional constraints and rates of substitution cannot be claimed to be a pillar of the neutral theory, because it is also predicted from a selectionist view-point. The dispensability of functional structures is brought into relation with the concept of reproductive sufficiency-the survivability of genotypes in the absence of fitter alleles.  相似文献   

7.
The extent of induction of aldrin epoxidation and glutathione S-transferase (GST) in the bulb mite Rhizoglyphus robini was dependent on the ingested plant material or on the type of inducer. GST was strongly induced in mites fed on garlic or exposed to trans-stilbene oxide as well as by the pesticides fenpropathrin and propoxur. Several phytochemicals such as 3-indoleacetonitrile, flavone, chalcone and pulegone were potent GST inducers stimulating the enzyme activity by 2–4-fold. Other toxicants, pesticides and allelochemicals yielded moderate to slight stimulation and a few were even inhibitory. In general, aldrin epoxidation was moderately stimulated by plant materials and xenobiotics. The epoxidation activity was increased in mites fed on garlic and carrot, or exposed to toxicants such as pentobarbital and -hexachlorocyclohexane, pesticides like chlordimeform, propoxur, carbaryl and lindane, as well as allelochemicals such as flavone, ß-carotene, indole-3-carbinol and safrole. The relevance of the study vis-à-vis adaptation of herbivorous arthropods to their habitats and acquirement of tolerance to chemical control agents, is discussed.  相似文献   

8.
Within the first 2 h of sexual reproduction, gametes of the green alga Chlamydomonas eugametos agglutinate, fuse via their mating structures, de-agglutinate and swim off as vis-à-vis pairs. During this period, increases in intracellular inositol 1,4,5-trisphosphate levels and changes in polyphosphoinositide synthesis were associated with cell fusion. The protein-kinase-C inhibitor staurosporine (0.1–0.2 M) inhibited the de-agglutination of pairs and therefore prevented them swimming away, while earlier stages of mating such as agglutination or cell fusion were unaffected. The results suggest that inositol 1,4,5-trisphosphate and diacylglycerol are fertilization signals in C. eugametos. The idea that they could also be fertilization signals in higher plants is discussed in relation to in vitro embryogenesis.Abbreviations DAG diacylglycerol - InsP3 inositol 1,4,5-trisphosphate - mt+/mt mating-type plus or minus - PKC protein kinase C - PtdOH phosphatidic acid - PtdInsP phosphatidylinositol - 4-phosphate PtdInsP2 phosphatidylinositol 4,5-bisphosphate  相似文献   

9.
Grouping of spectral peaks into J-connected spin systems is essential in the analysis of macromolecular NMR data as it provides the basis for disentangling chemical shift degeneracies. It is a mandatory step before resonance and NOESY cross-peak identities can be established. We have developed SPI, a computational protocol that scrutinizes peak lists from homo- and hetero-nuclear multidimensional NMR spectra and progressively assembles sets of resonances into consensus J- and/or NOE-connected spin systems. SPI estimates the likelihood of nuclear spin resonances appearing at defined frequencies given sets of cross-peaks measured from multi-dimensional experiments. It quantifies spin system matching probabilities via Bayesian inference. The protocol takes advantage of redundancies in the number of connectivities revealed by suites of diverse NMR experiments, systematically tracking the adequacy of each grouping hypothesis. SPI was tested on 2D homonuclear and 2D/3D15N-edited data recorded from two protein modules, the col 2 domain of matrix metalloproteinase-2 (MMP-2) and the kringle 2 domain of plasminogen, of 60 and 83 amino acid residues, respectively. For these protein domains SPI identifies 95% unambiguous resonance frequencies, a relatively good performance vis-à-vis the reported `manual' (interactive) analyses. Abbreviations and Acronyms: SPI, SPin Identification; BMRB, BioMagResBank (Madison, WI).  相似文献   

10.
The hypothesis of optimal host species selection predicts that when a parasitoid has the choice between two host species, it will choose the species thay gives the best survival chances for its progeny. We confirmed this hypothesis by laboratory experiments with Leptopilina boulardi Barb. et al., a cynipid parasitoid which prefers Drosophila melanogaster Meigen (the host species most suitable for parasitoid survival) above D. simulans Sturt. As far as fitness parameters are concerned, the fertility of L. boulardi is higher with D. melanogaster; the egg laying can be spread out over a long period when this host is relatively scarce. This does not occur with D. simulans in which parasitic oviposition stops soon when this host is not abundant.Investigations of this foraging strategy were done under more complex natural conditions. We found that L. boulardi has a type III functional response with D. melanogaster only; furthermore, it seems that a switching effect may exist with this host. Parasitoid females appear to distribute their eggs more regularly on D. melanogaster, thus avoiding superparasitism. This seems to be independent of the relative frequency of this host. However, superparasitism of D. simulans did occur more frequently when this host was scarce.
Stratégie de ponte de Leptopilina boulardi (hyménoptère parasite de drosophiles) dans les conditions naturelles
Résumé Le concept de réponse optimale d'un parasite vis-à-vis de l'hôte le plus favorable pour son développement demeure surtout théorique et n'a pu être vérifié que dans les conditions de laboratoire. Nous avons montré que Drosophila melanogaster s'avère être, par rapport à D. simulans, l'hôte le plus favorable pour le développement du cynipide parasite Leptopilina boulardi. Une étude sur le terrain a démontré que ce parasite présente une réponse fonctionnelle densité dépendante vis-à-vis de D. melanogaster et non vis-à-vis de D. simulans, avec un effet de bascule. D'autre part, il s'avère que ce parasite exploite beaucoup mieux son hôte, en évitant le superparasitisme, ceci étant démontré au laboratoire et dans la nature. Enfin, il apparaît qu'il est capable d'allonger sa période de ponte lorsque cet hôte est rare, ce qui ne se produit pas avec D. simulans.
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11.
Chloroplasts isolated from elevated temperature treated 8-day-old continuous-white-light-grown wheat primary leaves lost the ability to photo-oxidize water. Also, the ability of ascorbate to donate electrons to photosystem II declined. However, a significant increase in reduced dichlorophenolindophenol-supported photosystem-I-mediated methylviologen photo-reduction activity was observed. The plants stressed at 45°C and 47°C were subsequently grown at 25°C and the partial photochemical activities were measured in chloroplasts isolated from the plants at 24-h intervals. The post stress alterations observed are (1) a significant restoration of water oxidation capacity in 45°C- and partial restoration in 47°C-treated leaves. Ascorbate-supported photochemical activities recovered more or less in similar fashion; (2) reversal of enhanced photosystem I activity in both 45°C- and 47°C-treated leaves. These results suggest that the restoration in water oxidation capacity is possible in 45°C-treated leaves and is limited by the severity of heat stress in 47°C-treated leaves. Restoration of water oxidation capacity vis-à-vis to the reversal of heat-enhanced photosystem I activity also indicates the existence of possible endogenous control for repair of alterations during the post stress.Abbreviations DCPIP-2,6 Dichlorophenol-indophenol - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - FeCN Ferricyanide - Hepes N-2-Hydroxyethylpiperazine-N-2-ethanesulfonic acid - PD Phenylene diimine - MV Methyl Viologen  相似文献   

12.
A BDI-based continuous-time modelling approach for intracellular dynamics is presented. It is shown how temporalised BDI-models make it possible to model intracellular biochemical processes as decision processes. By abstracting from some of the details of the biochemical pathways, the model achieves understanding in nearly intuitive terms, without losing veracity: classical intentional state properties such as beliefs, desires and intentions are founded in reality through precise biochemical relations. In an extensive example, the complex regulation of Escherichia coli vis-à-vis lactose, glucose and oxygen is simulated as a discrete-state, continuous-time temporal decision manager. Thus a bridge is introduced between two different scientific areas: the area of BDI-modelling and the area of intracellular dynamics.  相似文献   

13.
Résumé Une souche de la diatomée marine Chaetoceros lauderi a montré une activité antifongique très spécifique vis-à-vis des Dermatophytes. Dans l'état actuel des travaux de purification, cette activité semble liée à l'activité antibactérienne à large spectre mise en évidence précédemment chez cette même espèce.
In fungicidal action researches from phytoplanctonic algae strains in culture an significant activity against pathogenic fungi of man was found for substances from the marine diatom Chaetoceros lauderi.
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14.
Scientific and craft representations of medicaldiagnosis can be regarded as complementary discursivesystems used by physicians in order to legitimate andmonopolize their professional power. This paperexamines the medical record as a context for theinterplay of these two discourses. During interviewsconducted with 78 Israeli physicians, 94% haverefused to give patients access to their medicalrecords. This refusal is discussed vis-à-vis a readingof the actual contents of medical records, which areshown to contain many errors, inconsistencies andambiguities. The paper concludes by offering analternative, anthropological model for medical recordsas fieldnotes.  相似文献   

15.
Synthesis of new bichromophoric di- and pentanuclear complexes 2-7 by datively binding (bpy)2RuII, (phen)2RuII and Cp (PPh3)RuII units to the periphery of [Co(OBTTAP)], 1, and their spectroscopic properties are described. IR, 1H NMR, UV-Vis, and mass spectral data were used for their characterization. Relative intensities and positions of the Soret and Q-bands absorptions in the di- and pentanuclear complexes were observed shifted vis-à-vis that in the precursor complex [Co(OBTTAP)], 1. These complexes particularly, those possessing [Co(OBTTAP)] and (bpy)2RuII/(phen)2RuII units, exhibited efficient inter-component electronic excitation energy transfer in their fluorescence excitation-emission spectra, that are suggestive of a high degree of inter-component electronic interaction in them. Also, the electrode activity of the complexes improved upon binding of the peripheral units and they exhibited multiple one-electron reversible oxidation waves in the cyclic voltammograms. These effects have been explained in terms of dπ(S)-dπ(Ru) interactions.  相似文献   

16.
Sampedro  L.  Uziel  A.  Latgé  J. P. 《Mycopathologia》1984,86(1):3-19
Résumé L'influence de différents facteurs physiques (température, pH, lumière, pression osmotique) et nutritionnels (sels, vitamines, sucres et hydrolysats de protéine) a été étudiée sur la germination des conidies primaires de Conidiobolus obscurus. Les germinations globales les plus élevées sont obtenues à 24 °C, à la lumière sur un milieu gélosé contenant du glucose et des vitamines ou de l'extrait de levure. Une température comprise entre 19 et 24 °C, un pH basique (8–10), l'obscurité et la présence de glucose et/ ou d'hydrolysats de protéine stimulent l'émission de tubes germinatifs. Les souches ont pu être classées en 2 groupes en fonction de leur mode de germination in vitro et de leur agressivité vis-à-vis du puceron du pois.
Different physical (temperature, pH, light and osmotic pressure) and nutritional factors (salts, vitamins, sugars and protein hydrolysates) were tested on the germination of primary conidia of Conidiobolus obscurus. The most important total germination levels were obtained at 24 C, in continuous light on an agar medium containing dextrose and vitamins or yeast extract. Temperatures ranging from 19 to 24°, a basic pH (8–10), darkness and the presence of dextrose and/ or protein hydrolysates stimulated the formation of germ tubes. The strains of C. obscurus studied were classified in 2 groups depending on their aggressivity against the pea aphid and their mode of germination in vitro.
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17.
Summary In everyday life red forest ants (Formica rufa) very often carry into their nests glittering particles which are parts of integuments of insects which died long time ago.Some experiments demonstrating attitude of antsF. rufa towards shining and glittering articles are described. Many-colored beads have always attracted a very intensive attention of ants. Considerable variety in reaction of workers in one of the nests has been registered. The degree of attention displayed by ants to such articles in many cases was quite different. Attention of old ants was more intensive than that shown by the the younger ones.Indifferent to beads were antsF. fusca, F. gagates and ants ofCamponotus andMyrmica Genera.Different attitude of antsF. rufa to bright glistering articles is one of the mysteries of psychic life of these insects.
Réumé Dans leur va-et-vient quotidien, les fourmis rousses forestières, ramènent souvent à la fourmilière les parties brillantes du tégument d'insectes depuis longtemps privés de vie.Les expériences décrites ici expliquent le comportement des fourmis du groupeF. rufa vis-à-vis des objets clairs et brillants. L'attention de ces fourmis est toujours fortement et particulièrement attirée par des menues perles multicolores. Mais les réactions des travailleuses d'une même fourmilière envers ce chatoiement sont très diverses. La concentration de l'attention envers le chatoiement des couleurs est également très variable d'un individu à l'autre. Les perles multicolores attirent le plus l'attention des vieilles fourmilières, alors que celle des fourmilières plus jeunes l'est beaucoup moins fortement.Les fourmisF. fusca, F. gagates ainsi que les fourmis du genreCamponotus etMyrmica sont absolument indifférentes au chatoiement des perles.Le comportement des fourmis du groupeF. rufa vis-à-vis des objets clairs et brillants est encore une énigme de la vie psychique de ces insectes.
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18.
The widespread occurrence of high inorganic arsenic in natural waters is attributed to human carcinogen and is identified as a major global public health issue. The scale of the problem in terms of population exposure (36 million) and geographical area coverage (173 × 103 Km2) to high arsenic contaminated groundwater (50–3200 gL–1) compared to the National drinking water standard (50 gL–1) and WHO recommended provisional limit (10 gL–1) is greatest in the Holocene alluvium and deltaic aquifers of the Bengal Delta Plain (Bangladesh and West Bengal, India). This large-scale 'natural' high arsenic groundwater poses a great threat to human health via drinking water. Mobilization, metabolism and mitigation issues of high arsenic groundwater are complex and need holistic approach for sustainable development of the resource. Mobilization depends on the redox geo-chemistry of arsenic that plays a vital role in the release and subsequent transport of arsenic in groundwater. Metabolism narrates the biological response vis-à-vis clinical manifestations of arsenic due to various chemical and biological factors. Mitigation includes alternative source for safe drinking water supply. Drinking water quality regulatory standards as well as guidelines are yet to cover risk assessments for such metal toxicity. Lowering of the ingested inorganic arsenic level and introduction of newer treatment options (implementation of laterite, the natural material) to ensure safe water supply (arsenic free and/or low arsenic within permissible limit) are the urgent need to safe guard the mass arsenic poisoning and internal arsenic related health problems.  相似文献   

19.
Galeodes arabs is shown by aktograph experiments to be nocturnal in habit especially in the hot season. It has a low rate of water-loss by transpiration in dry air. Behaviour responses to enemies and prey are classified as alertness, threat, high intensity threat (accompanied by stridulation) leading to attack or flight (often followed by displacement sanddigging). Feeding habits are described.
Resume Les moeurs nocturnes, particulièrement durant la saison chaude, des araignées Galeodes arabs ont été montrées par des expériences avec l'actographe.Dans la nature elles passent la journée dans des abris profonds, dont l'ouverture est fermée par un tampon de feuilles mortes. Leur perte en eau par transpiration à l'air sec présente un taux assez bas et elles peuvent survivre à une forte dessiccation. Leurs réactions de comportement vis-à-vis des ennemis et des proies sont classées en promptitude, frayeur, frayeur très intense (accompagnée de stridulation) conduisant à l'attaque ou à la fuite (souvent suivie de déplacement avec rejet de sable). Les habitudes alimentaires sont décrites et on montre que la fuite se produit plus facilement chez mâles que chez les femelles.
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20.
Résumé Le rubidium et le césium introduits à l'état de chlorure dans le milieu de culture ont à faible dose un effet stimulant sur la croissance de Chara fragilis et de Chara vulgaris. La résistance de ces végétaux à l'action toxique des deux ions est accrue par l'addition de potassium au milieu.Les analyses chimiques confirment que le rubidium et le césium sont antagonistes vis-à-vis du potassium et du sodium alors qu'ils ne modifient pas de manière significative le taux de calcium.
Chara fragilis and Chara vulgaris were cultivated in a natural medium containing rubidium and caesium as chloride.The growth of Characeae was increased after culture in the solutions containing Rb and Cs in small amount. The resistance to the toxic effects of these two ions is enhanced if potassium chloride is added to the medium.Quantitative analyses indicate that Rb and Cs decrease the rate of Na and K but have no significative influence on the rate of Ca.
Université de Dijon, Laboratoire de Nutrition minérale des Végétaux  相似文献   

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