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1.
Background
In heterogeneous environments, sex-biased dispersal could lead to environmental adaptive parental effects, with offspring selected to perform in the same way as the parent dispersing least, because this parent is more likely to be locally adapted. We investigate this hypothesis by simulating varying levels of sex-biased dispersal in a patchy environment. The relative advantage of a strategy involving pure maternal (or paternal) inheritance is then compared with a strategy involving classical biparental inheritance in plants and in animals. 相似文献2.
Use of ATP bioluminescence measurements for the estimation of biomass during biological humification
Summary The development of the microflora during the humification of grape pulp has been investigated by the determination of ATP using the bioluminescence technique. Several extraction methods were tested including the use of dimethylsulphoxide, trichloroacetic acid, grinding and ultrasonification. Dimethylsulphoxide and ultrasonification for 15 sec appeared to be the most effective. The ATP extract was stabilized when it was mixed with 0.75 mM glycine, 4.4 mM Mg-EDTA, pH 7.5 and frozen. The relative error of the ATP assay by bioluminescence did not exceed 6.5%. This method allowed us to show that at least five distinct reproducible microbial phases exist during grape pulp humification. These results show that the microbial biomass changes noticeably and at distinct times during composting. 相似文献
3.
An assessment was made of two methods for determining the potency of tissue-type plasminogen activator (TPA). A chromogenic microtitre plate assay was established which contained TPA, plasminogen, a synthetic plasmin substrate (H-D-valyl-L-leucyl-L-lysyl-p-nitroaniline dihydrochloride, S2251) and any one of the following stimulators: native fibrinogen, enzymatic and chemical digests of fibrinogen, poly-D-lysine (PDL) and chemical derivatives of the latter. The chromogen assay was compared with an automated clot-lysis (turbidimetric) assay for sensitivity, reproducibility and validity for potency determination. Reference preparations of TPA were titrated in both assays: in the chromogen assay the dose-response curves were non-parallel, whereas parallelism was observed in the clot-lysis assay. Thus, the chromogen assay was restricted in its applicability and disqualified from any routine regulatory use. The potency of individual lots of recombinant (r)TPA could only be estimated in International Units (IU) of TPA activity with the automated clot-lysis assay and the potency values obtained (IU/vial) were in remarkably close agreement with the manufacturers' values. 相似文献
4.
Alain Couté 《Hydrobiologia》1982,97(3):255-274
Résumé L'ultrastructure de Geitleria calcarea Friedmann, cyanophycée filamenteuse aérienne, calcifiée et cavernicole, rarement signalée, est étudiée ici pour la première fois. La cytologie de cet organisme présente des originalités. Huit enveloppes cellulaires concentriques sont dénombrées: membrane plasmique, L I, L II, L III, L IV, enveloppe pariétale, gaine fibreuse et gaine carbonatée. La dernière est décrite à l'aide du M.E.B. Les thylacoïdes très nombreux ont une forme extrêmement contournée. Ils supportent des phycobilisomes cylindriques alternant avec des polysaccharides de même allure. L'organisation des synapses est détaillée. L'élongation est apicale et le mode de ramification est soit latéral, soit dichotomique.
The ultrastructure of the atmophytic lime-encrusted filamentous blue-green alga Geitleria calcarea Friedmann, which grows in caves, is studied here for the first time. The cytology of this organism presents original features concerning the cellular sheath, envelopes, wall, thylacoïds and pit connections. Its filament growth is apical and its type of branching is lateral and dichotomous.相似文献
5.
Diuron belongs to the family of halogenophenylureas, one of the main groups of herbicides used for more than 40 years. These herbicides absorb sunlight and can be photochemically transformed in the environment (herbicides are transformed on the soil surface exposed to sunlight) or biotransformed by microorganisms present in soil or in water. The metabolites (chlorohydroxyphenylurea, chlorophenylaniline, respectively) are more toxic than the parent compound, as demonstrated by a bioluminescence inhibition assay performed with a marine bacterium (Vibrio fischeri toxicity test). The lipophilicity of these pesticides makes the cell membrane a target for their action, especially the spermatozoa cell membrane. The aim of this study is to use human spermatozoa to evaluate the effect of this urea pesticide and its biotransformed product on the spermatozoa membrane. We investigated the structural and functional effects of these environmental pollutants on spermatozoa. Three million spermatozoa purified on a 95/47.5% Percoll gradient were suspended in 250 μl of modified Earle’s medium (without phenol red) supplemented with 7.5% of human decomplemented serum. Pesticides (Diuron or 3,4-dichloroaniline (3,4-DCA)) were added at a final concentration of 0.1; 1 and 5 mM. Samples were incubated at room temperature for 24 hours. We show that both Diuron and 3,4-DCA decrease motility and vitality of spermatozoa incubated with the highest concentration of pesticides. Our preliminary results show that the effects are more rapid and more intense with the biotransformed product (3,4-DCA) than with Diuron. Addition of herbicide to human spermatozoa increases membrane fluidity, assessed by measuring the fluorescence polarisation anisotropy with a fluorescent probe: 1,6-diphenyl-1,3,5-hexatriene (DPH). Changes in membrane fluidity may be a primary toxic effect of these herbicides. These results suggest that human spermatozoa may constitute a valuable indicator of the toxic effects of pesticides. 相似文献
6.
Expression of alternatively spliced mRNA variants at specific stages of development or in specific cells and tissues contributes to the functional diversity of the human genome. Aberrations in alternative splicing were found as a cause or a contributing factor to the development, progression, or maintenance of numerous diseases. The use of antisense oligonucleotides (ON) to modify aberrant expression patterns of alternatively spliced mRNAs is a novel means of potentially controlling such diseases. Oligonucleotides can be designed to repair genetic mutations, to modify genomic sequences in order to compensate for gene deletions, or to modify RNA processing in order to improve the effects of the underlying gene mutation. Steric block ON approach have proven to be effective in experimental model for various diseases. Here, we describe our experience in investigating two strategies for ON delivery: ON conjugation with basic peptides and lipid-based particulate system (lipoplex). Basic peptides or Cell Penetrating Peptides (CPP) such as the TAT-derived peptide appear to circumvent many problems associated with ON and drug delivery. This strategy may represent the next paradigm in our ability to modulate cell function and offers a unique avenue for the treatment of disease. Lipoplexes result from the intimate interaction of ON with cationic lipids leading to ON carrying particles able to be taken up by cells and to release ON in the cytoplasm. We have used as an experimental model the correction of a splicing alteration of the mutated β-globin intron causing thalassemia. Data on cell penetration and efficacy of correction of specific steric block ON delivered either by basic peptides or lipoplex are described. A comparison of the properties of both delivery systems is made respective to the use of this new class of therapeutic molecules. 相似文献
7.
Audray Dugrand-Judek Alexandre Olry Alain Hehn Gilles Costantino Patrick Ollitrault Yann Froelicher Frédéric Bourgaud 《PloS one》2015,10(11)
Citrus plants are able to produce defense compounds such as coumarins and furanocoumarins to cope with herbivorous insects and pathogens. In humans, these chemical compounds are strong photosensitizers and can interact with medications, leading to the “grapefruit juice effect”. Removing coumarins and furanocoumarins from food and cosmetics imply additional costs and might alter product quality. Thus, the selection of Citrus cultivars displaying low coumarin and furanocoumarin contents constitutes a valuable alternative. In this study, we performed ultra-performance liquid chromatography coupled with mass spectrometry analyses to determine the contents of these compounds within the peel and the pulp of 61 Citrus species representative of the genetic diversity all Citrus. Generally, Citrus peel contains larger diversity and higher concentrations of coumarin/furanocoumarin than the pulp of the same fruits. According to the chemotypes found in the peel, Citrus species can be separated into 4 groups that correspond to the 4 ancestral taxa (pummelos, mandarins, citrons and papedas) and extended with their respective secondary species descendants. Three of the 4 ancestral taxa (pummelos, citrons and papedas) synthesize high amounts of these compounds, whereas mandarins appear practically devoid of them. Additionally, all ancestral taxa and their hybrids are logically organized according to the coumarin and furanocoumarin pathways described in the literature. This organization allows hypotheses to be drawn regarding the biosynthetic origin of compounds for which the biogenesis remains unresolved. Determining coumarin and furanocoumarin contents is also helpful for hypothesizing the origin of Citrus species for which the phylogeny is presently not firmly established. Finally, this work also notes favorable hybridization schemes that will lead to low coumarin and furanocoumarin contents, and we propose to select mandarins and Ichang papeda as Citrus varieties for use in creating species devoid of these toxic compounds in future breeding programs. 相似文献
8.
Elli Kohen Cahide Kohen Joseph G. Hirschberg Alain W. Wouters Bo Thorell 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,720(4):420-424
A microspectrofluorimetric study is made of the influence of dimethylnitrosamine on NADP reduction, following sequential microinjections into the same L cell, of two substrates: (1) isocitrate, with activity of isocitrate dehydrogenase both in the extramitochondrial and intramitochondrial compartments, (2) 6-phosphogluconate, with activity of the dehydrogenase in the extramitochondrial compartment. In control L cells a two-step reduction of NAD(P) is obtained followed by relatively slow reoxidation. In the minutes which follow addition of carcinogen, e.g., dimethylnitrosamine, to the cell medium the isocitrate and 6-phosphogluconate-induced transient NADP reoxidation is decreased in magnitude compared to control, while the rate constant of NADPH reoxidation is considerably accelerated, possibly due to requirements at the level of the microsomal metabolizing system. Observations within the first hour of carcinogen addition suggest an interesting system for evaluating the immediate actions of carcinogens at extranuclear sites: i.e., a comparative study of NADP reduction-reoxidation rate constants via injection of substrates for extra- vs. intramitochondrial pathways. 相似文献
9.
After 30 years of continuous research into the mechanisms of human hypertension, we summarize the results obtained by the members of the multidisciplinary research group on hypertension of the Clinical Research Institute of Montreal on the disturbances of minerlocorticoid activity in a rigorously selected group of patients with early, mild essential hypertension. We attempt to integrate these findings with those of many other groups working on other aspects of hypertensive cardiovascular diseases. On the assumption that the increased peripheral resistance responsible for hypertension results from an imbalance or a disturbance of the equilibrium between the sympathetic nervous system and norepinephrine on one hand, and the vascular tone, sensitivity and responsiveness of the arterial smooth muscle to norepinephrine and to angiotensin II on the other hand, three models that fit the experimental and clinical facts as known at present are described. 相似文献
10.