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1.
Monica Driscoll 《Developmental neurobiology》1992,23(9):1327-1351
In C. elegans, cell death can be readily studied at the cellular, genetic, and molecular levels. Two types of death have been characterized in this nematode: (1) programmed cell death, which occurs as a normal component in development; and (2) pathological cell death which occurs aberrantly as a consequence of mutation. Analysis of mutations that disrupt programmed cell death in various ways has defined a genetic pathway for programmed cell death which includes genes that perform such functions as the determination of which cells die, the execution of cell death, the engulfment of cell corpses, and the digestion of DNA from dead cells. Molecular analysis is providing insightinto the nature of the molecules that function in these aspects of programmed cell death. Characterization of some genes that mutate to induce abnormal cell death has defined a novel gene family called degenerins that encode putative membrane proteins. Dominant alleles of at least two degenerin genes, mec-4 and deg-1, can cause cellular swelling and late onset neurodegeneration of specific groups of cells. © 1992 John Wiley & Sons, Inc. 相似文献
2.
Populations of the Australian sleepy lizard, Tiliqua rugosa, near Mt. Mary, South Australia carry natural infestations of two tick species Aponomma hydrosauri and Amblyomma limbatum. In field experiments at two sites, 18 km apart, lizards with experimentally increased tick loads had smaller home ranges,
moved shorter distances in a day, and were found basking more but moving less often than lizards from which ticks were experimentally
removed. The results were consistent for adult lizards in two years, and for sub-adults in a third year. Laboratory trials
showed that juvenile lizards that had tick infestations had lower sprint speeds than uninfested siblings, and that adults
with tick infestations had less endurance than those that were uninfested. The results contrast with those of a previous survey
that showed that lizards with high tick loads had greater body size and remained longer at a site, but indicate that there
may be a balance, for lizards, between the fitness advantages in occupying habitats with high-quality resources, and the costs
from parasites that also prefer those habitats.
Received: 02 March 1999 / Accepted: 07 October 1999 相似文献
3.
Delays in the development of exploratory and locomotor behavior in neonatal male rats (up to 21 days of age) are shown to accrue as a consequence of low level lead exposure. Cross fostering experiments indicate that these delays are primarily due to prenatal exposure. These Pb induced behavioral modifications appear to be associated with the delays in synaptogenesis and biochemical development of the cerebral cortex reported previously (4, 18). A new behavioral bioassay for detecting delays in brain development is described. 相似文献
4.
Filippo Genovese Stefania Ferrari Giambattista Guaitoli Monica Caselli M. Paola Costi Glauco Ponterini 《Protein science : a publication of the Protein Society》2010,19(5):1023-1030
An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43′ with an excitation energy donor/acceptor pair. The dimer–monomer equilibrium of the enzyme is then characterized through steady‐state fluorescence determination of the intersubunit resonance energy transfer efficiency. 相似文献
5.
Exploratory behavior and locomotor activity is enhanced in male rat pups (aged 10 to 20 days) whose dams received a chronic dose (1.25 ml/l) of Tween 80 via their drinking water. This enhancement manifests itself during the diurnal period of the day. These data suggest that Tween 80 has an effect on the CNS which could lead to misinterpretation of results in toxicology studies that use this compound as a dosage vehicle. 相似文献
6.
Monica BreurkenEdith H.M. Lempens Rinske P. TemmingBrett A. Helms E.W. MeijerMaarten Merkx 《Bioorganic & medicinal chemistry》2011,19(3):1062-1071
Collagen is an attractive marker for tissue remodeling in a variety of common disease processes. Here we report the preparation of protein dendrimers as multivalent collagen targeting ligands by native chemical ligation of the collagen binding protein CNA35 to cysteine-functionalized dendritic divalent (AB2) and tetravalent (AB4) wedges. The binding of these multivalent protein constructs was studied on collagen-immobilized chip surfaces as well as to native collagen in rat intestinal tissues. To understand the importance of target density we also created collagen-mimicking surfaces by immobilizing synthetic collagen triple helical peptides at various densities on a chip surface. Multivalent display of a weak-binding variant (CNA35-Y175K) resulted in a large increase in collagen affinity, effectively restoring the collagen imaging capacities for the AB4 system. In addition, dissociation of these multivalent CNA35 dendrimers from collagen surfaces was found to be strongly attenuated. 相似文献
7.
Javier J Gonzalez-Rosa Manuel Vazquez-Marrufo Encarnacion Vaquero Pablo Duque Monica Borges Carlos M Gomez-Gonzalez Guillermo Izquierdo 《BMC neurology》2011,11(1):64-19
Background
Event-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills is increasingly recognised as a hallmark of patients suffering from multiple sclerosis (MS). We sought to determine the psychophysiological pattern of information processing among MS patients with the relapsing-remitting form of the disease and low physical disability considered as two subtypes: 'typical relapsing-remitting' (RRMS) and 'benign MS' (BMS). Furthermore, we subjected our data to a cluster analysis to determine whether MS patients and healthy controls could be differentiated in terms of their psychophysiological profile. 相似文献8.
9.
Species-specific algal responses to zooplankton: experimental and field observations in three nutrient-limited lakes 总被引:3,自引:0,他引:3
Elser James J.; Goff Nancy C.; MacKay Neil A.; Amand Ann L.St.; Elser Monica M.; Carpenter Stephen R. 《Journal of plankton research》1987,9(4):699-717
A series of 4-day manipulations of zooplankton biomass and nutrientavailability was performed in enclosures in three lakes to determinespecies-specific algal responses to herbivory and nutrient enrichment.Algal performance in enclosures was compared to the relationshipsbetween weekly algal growth rates and the zooplankton in situ.When in situ growth rates were significant functions of zooplanktonbiomass, the responses were generally consistent with responsesin the enclosure experiments. The importance of both nutrientsand zooplankton in mediating algal growth was demonstrated bynumerous observations: strong algal community response to enrichment,unimodal or positive responses of certain algal taxa to zooplanktonbiomass, differences in degree of nutrient limitation amongthe algal response types, lack of nutrient limitation of non-grazedalgal taxa and a preponderance of taxa with no net responseto increasing zooplankton biomass. Variation in the zooplanktoncommunity may be the largest source of variability in nutrientsupply rate during summer in stratified lakes, and causes substationalvariability in the algae. Algae responded more strongly to changesin zooplankton composition than to changes in zooplankton biomass.We conclude that, due to the close coupling of phytoplanktonand zooplankton communities in these nutrient-limited lakes,major compositional changes in the zooplankton have greatereffects on the algae than do changes in biomass of grazers alreadypresent.
1Present address: Division of Environmental Studies, Universityof California, Davis, CA 95616, USA
2Present address: Division of Biological Sciences, Universityof California, Davis, CA 95616, USA 相似文献
10.
H. M. Lappin-Scott G. Holt A. T. Bull 《World journal of microbiology & biotechnology》1987,3(2):95-102
Summary Soil microorganisms from one site were shown to be consistently capable of the transformation of 1,6-dichloro-1,6-dideoxy-,d-fructofuranosyl-4-chloro-4-deoxy-,d-galactopyranoside (TGS) in laboratory batch cultures. With fresh soils, all of the available chloride ions were released from the molecule. Subcultures of a TGS-dehalogenating bacterial community produced a progressive decline in the dehalogenating capabilities towards the substrate. The soil organisms did not utilise TGS as a carbon source. The transformation was achieved by co-metabolism and was probably supported by an unknown component in the soil. Four bacterial species were isolated from the TGS-dehalogenating soil community: twoBacillus species, anAcinetobacter group isolate and aMicrococcus group isolate. Thin-layer chromatography confirmed the disappearance of the chlorosugar and high-performance liquid chromatography demonstrated that neither of the constituent monosaccharides—1,6-dichlorofructose nor 4-chlorogalactosucrose was accumulated as an intermediate.
Resumen Microorganismos de suelo de cierto lugar demostraron consistemente ser capaces de realizar la transformación de 1,6-dicloro-1,6 dideoxi--D-fructofuranosil-4-cloro-4-deoxi-,D-alactopiranosa (TGS) in culturas de laboratorio de tipo discontinuo. Con muestras frescas de suelo, todos los iones cloruro fueron liberados de la molecula. Subculturas de una comunidad bacterial capaz de dehalogenizar TGS produjeron una declinación progresiva de la capacidad de dehalogenizar el substrato. Los microorganismos no utilizaron el TGS como fuente de carbono. La transformación se realiza por co-metabolismo y probablemente se base en un componente del suelo, no determinado. Cuatro especies bacteriales fueron aisladas de la comunidad de bacterias de suelo con capacidad de dehalogenar el TGS: dos especies deBacilo, unaAcinelobacteria y unMicrococo. Estudios de cromatografía de capa delgada confirmaron la desaparición del clorosacárido, y estadios de cromatografía liquida demostraron que ninguno de los componentes monoscáridos — 1,6-diclorofructuosa y 4-clorogalactosucrosa — eran acumulados como productors intermedios.
Résumé Les microorganismes du sol d'un certain endroit ont été démontrés être capable, sans exception, de la transformation de 1,6-dichloro-1,6-dideoxy-,D-fructofuranosyl-4-chloro-4-deoxy-,D-galactopyranoside (TGS) en cultures de laboratoire du type discontinu. Avec des prélèvements frais du sol, tous les ions disponibles de chlorure ont été libérés de la molécule. Des souscultures d'une communauté bactérienne capable de déhalogeniser le TGS ont produit un déclin progressif de la capacité de déhalogeniser le substrat. Les microorganismes du sol n'ont pas utilisé le TGS comme source de carbone. La transformation s'est accomplie par cometabolisme et, probablement, s'est basée sur un component indéterminé du sol. Quatre espèces bactériennes ont été isolées de la communauté de bactéries du sol capable de déhalogeniser le TGS: deux espèces deBacillus, unAcinetobacter et unMicrococcus. Des études de chromatographie de couches fines ont confirmées la disparition du chlorosaccharide, tandis que des études de chromatographie liquide de haut rendement ont démontrées que, des monosaccharides constituants, ni 1,6-dichlorofructose ni 4-chlorogalactosucrose, n'ont été accumulés comme produits intermédiaires.相似文献