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排序方式: 共有132条查询结果,搜索用时 15 毫秒
1.
R Mathur K Alvares A S Balasubramanian 《Biochemical and biophysical research communications》1984,123(3):1185-1193
Lysosomal alpha-D-mannosidase of monkey brain existed in two forms. One form of mannosidase was bound to the Ricinus communis agglutinin120 (RCA1)-Sepharose and could be specifically eluted with lactose. The other form did not bind to the RCA1-Sepharose. Both forms of mannosidase could bind to a similar extent to the immobilized brain lysosomal receptor protein. Both the forms were purified to apparent homogeneity. Neutral sugar analysis by GLC showed the presence of glucose, mannose and galactose in the RCA1-Sepharose bindable mannosidase and glucose and mannose in the non-bindable mannosidase. Several other brain lysosomal hydrolases did not bind to the RCA1-Sepharose. The results suggested the existence of only high mannose oligosaccharides in the RCA1 non-bindable mannosidase and both high mannose and complex oligosaccharides in the bindable mannosidase. 相似文献
2.
Jorge Assis Nelson Castilho Coelho Filipe Alberto Myriam Valero Pete Raimondi Dan Reed Ester Alvares Serr?o 《PloS one》2013,8(7)
The genetic consequences of living on the edge of distributional ranges have been
the subject of a largely unresolved debate. Populations occurring along
persistent low latitude ranges (rear-edge) are expected to retain high and
unique genetic diversity. In contrast, currently less favourable environmental
conditions limiting population size at such range-edges may have caused genetic
erosion that prevails over past historical effects, with potential consequences
on reducing future adaptive capacity. The present study provides an empirical
test of whether population declines towards a peripheral range might be
reflected on decreasing diversity and increasing population isolation and
differentiation. We compare population genetic differentiation and diversity
with trends in abundance along a latitudinal gradient towards the peripheral
distribution range of
Saccorhiza
polyschides
, a large brown
seaweed that is the main structural species of kelp forests in SW Europe.
Signatures of recent bottleneck events were also evaluated to determine whether
the recently recorded distributional shifts had a negative influence on
effective population size. Our findings show decreasing population density and
increasing spatial fragmentation and local extinctions towards the southern
edge. Genetic data revealed two well supported groups with a central contact
zone. As predicted, higher differentiation and signs of bottlenecks were found
at the southern edge region. However, a decrease in genetic diversity associated
with this pattern was not verified. Surprisingly, genetic diversity increased
towards the edge despite bottlenecks and much lower densities, suggesting that
extinctions and recolonizations have not strongly reduced diversity or that
diversity might have been even higher there in the past, a process of shifting
genetic baselines. 相似文献
3.
4.
Ledig MM McKinnell IW Mrsic-Flogel T Wang J Alvares C Mason I Bixby JL Mueller BK Stoker AW 《Journal of neurobiology》1999,39(1):81-96
Receptor tyrosine kinases and receptor protein tyrosine phosphatases (RPTPs) appear to coordinate many aspects of neural development, including axon growth and guidance. Here, we focus on the possible roles of RPTPs in the developing avian retinotectal system. Using both in situ hybridization analysis and immunohistochemistry, we show for the first time that five RPTP genes--CRYPalpha, CRYP-2, PTPmu, PTPgamma, and PTPalpha--have different but overlapping expression patterns throughout the retina and the tectum. PTPalpha is restricted to Muller glia cells and radial glia of the tectum, indicating a possible function in controlling neuronal migration. PTPgamma expression is restricted to amacrine neurons. CRYPalpha and CRYP-2 mRNAs in contrast are expressed throughout the retinal ganglion cell layer from where axons grow out to their tectal targets. PTPmu is expressed in a subset of these ganglion cells. CRYPalpha, CRYP-2, and PTPmu proteins are also localized in growth cones of retinal ganglion cell axons and are present in defined laminae of the tectum. Thus, the spatial and temporal expression of three distinct RPTP subtypes--CRYPalpha, CRYP-2, and PTPmu--are consistent with the possibility of their involvement in axon growth and guidance of the retinotectal projection. 相似文献
5.
R H Weichbrod C F Cisar J G Miller R C Simmonds A P Alvares T H Ueng 《Laboratory animal science》1988,38(3):296-298
The purpose of the present studies was to evaluate the effects of some commercially available cage beddings on rat liver microsomal cytochrome P-450-dependent drug-metabolizing enzyme, ethylmorphine N-demethylase, and the carcinogen-metabolizing enzyme, benzo(a)pyrene hydroxylase. Sprague-Dawley rats were housed in cages containing cedar chip, corncob or heat-treated pinewood bedding for 3 weeks. Control rats were housed in cages on wire bottom floors containing no bedding material. Rats housed in cages containing cedar chip showed 18, 46 and 49% increases in liver cytochrome P-450 content, ethylmorphine N-demethylase and benzo(a)pyrene hydroxylase activities, respectively. The liver enzyme activities of rats housed in cages containing corncob bedding were similar to those obtained with control rats. In contrast, the pinewood-bedded rats showed a 21% decrease in ethylmorphine N-demethylase activity without affecting cytochrome P-450 content and benzo(a)pyrene hydroxylase activity. Hexobarbital-induced sleep times of the variously bedded rats were similar to those of control animals. These data suggest that the commercial bedding materials differ in their abilities to affect liver microsomal enzymes. Thus, interlaboratory variability in basal enzyme activities reported in the literature may be partly due to bedding materials used in the animal's cages. 相似文献
6.
Assembly of the type I procollagen molecule begins with interactions among the C-pro alpha1(I) and C-pro alpha2(I) domains. The C-propeptide domains themselves have subdomains of distinct structures. The important questions are where chain association begins and the basis of the chain selectivity which leads to the preferential formation of the [C-pro alpha1(I)]2[C-pro alpha2(I)] heterotrimer. These questions are addressed by energy minimization modeling of the individual C-propeptide structures, study of their docking interactions, and comparison of the heterotrimeric and homotrimeric C-pro structures and stability. The comparisons show the remarkable impact of the C-pro alpha2 chain on the structure of the assembled trimeric C-propeptide. In the modeling, the three chains were anchored and registered by a short C-terminal collagen triple-helical segment followed by the C-telopeptides in their docked conformation, and then the remaining C-propeptide chains were allowed to interact and dock. Surprisingly, propeptide trimerization did not proceed through the previously proposed N-terminal "oligomerization domain" of the C-propeptide [McAlinden et al. (2003) J. Biol. Chem. 278, 42200] but rather in the most C-terminal domains of type I procollagen chains. Molecular dynamics showed heterotrimer assembly to begin with dimer formation between globular G2alpha2 and the G2alpha1(2) domains followed by trimerization at the G1 domains. Assembly initiation in the putative oligomerization coiled-coil domain is not possible because of the Pro residues at positions 3, 7, and 11 at the N-terminus of the alpha2 C-propeptide chain. To confirm the computations and proposed assembly pathway, the G2alpha1 and G2alpha2 domains were prepared recombinantly as the maltose binding protein constructs, and their interactions were studied by dynamic light scattering and gel filtration chromatography. Under the conditions examined MBP remained as monomer, MBP-G2alpha1 and MBP-G2alpha2 alone formed dimers, but a 2:1 mixture of MBP-G2alpha1 and MBP-G2alpha2 favored trimer formation. Thus, the C-terminal globular domains (G2) of the type I collagen C-propeptides play a crucial role in the initiation of intermolecular assembly and heterotrimer selectivity. 相似文献
7.
Annemarie MM Vlaar Angela EP Bouwmans Marinus JPG van Kroonenburgh Werner H Mess Selma C Tromp Piet GWM Wuisman Alfons GH Kessels Ania Winogrodzka Wim EJ Weber 《BMC neurology》2007,7(1):28
Background
Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD. 相似文献8.
Sheila Merlo Garcia Luciana Sim?es Rafagnin Marinho Paula Alvares Lunardelli Marcelo Marcondes Seneda Flávio Vieira Meirelles 《PloS one》2015,10(3)
The aims of this study were to determine if the protein source of the medium influences zebu embryo development and if developmental kinetics, developmental block and programmed cell death are related. The culture medium was supplemented with either fetal calf serum or bovine serum albumin. The embryos were classified as Fast (n = 1,235) or Slow (n = 485) based on the time required to reach the fourth cell cycle (48 h and 90 h post insemination - hpi -, respectively). The Slow group was further separated into two groups: those presenting exactly 4 cells at 48 hpi (Slow/4 cells) and those that reached the fourth cell cycle at 90 hpi (Slow). Blastocyst quality, DNA fragmentation, mitochondrial membrane potential and signs of apoptosis or necrosis were evaluated. The Slow group had higher incidence of developmental block than the Fast group. The embryos supplemented with fetal calf serum had lower quality. DNA fragmentation and mitochondrial membrane potential were absent in embryos at 48 hpi but present at 90 hpi. Early signs of apoptosis were more frequent in the Slow and Slow/4 cell groups than in the Fast group. We concluded that fetal calf serum reduces blastocyst development and quality, but the mechanism appears to be independent of DNA fragmentation. The apoptotic cells detected at 48 hpi reveal a possible mechanism of programmed cell death activation prior to genome activation. The apoptotic cells observed in the slow-developing embryos suggested a relationship between programmed cell death and embryonic developmental kinetics in zebu in vitro-produced embryos. 相似文献
9.
Luiz Henrique Saes Zobiole Rubem Silvério de Oliveira Jr Don Morgan Huber Jamil Constantin César de Castro Fábio Alvares de Oliveira Adilson de Oliveira Jr. 《Plant and Soil》2010,328(1-2):57-69
Although glyphosate-resistant (GR) technology is used in most countries producing soybeans (Glycine max L.), there are no particular fertilize recommendations for use of this technology, and not much has been reported on the influence of glyphosate on GR soybean nutrient status. An evaluation of different cultivar maturity groups on different soil types, revealed a significant decrease in macro and micronutrients in leaf tissues, and in photosynthetic parameters (chlorophyll, photosynthetic rate, transpiration and stomatal conductance) with glyphosate use (single or sequential application). Irrespective of glyphosate applications, concentrations of shoot macro- and micronutrients were found lower in the near-isogenic GR-cultivars compared to their respective non-GR parental lines Shoot and root dry biomass were reduced by glyphosate with all GR cultivars evaluated in both soils. The lower biomass in GR soybeans compared to their isogenic normal lines probably represents additive effects from the decreased photosynthetic parameters as well as lower availability of nutrients in tissues of the glyphosate treated plants. 相似文献
10.
Shobha Thangada Keith Alvares Mario Mangino Mohammed I. Usman M.Sambasiva Rao Janardan K. Reddy 《FEBS letters》1989,250(2):205-210
Using the normal adult rat hepatocytes, plated on rat tail collagen-coated dishes and fed a chemically defined medium, we demonstrate here that ciprofibrate at 0.1 mM concentration, increases significantly the mRNA levels of fatty acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein, and thiolase (the three enzymes of the β-oxidation system), and causes peroxisome proliferation. Increase in mRNA levels of these genes was evident within 1 h and was maximal 24 h after the addition of ciprofibrate. In hepatocytes cultured in the absence of ciprofibrate, the basal levels of these enzymes were low and further declined with time. Concomitant treatment of hepatocytes with cycloheximide did not inhibit or superinduce the mRNA levels, indicating that this induction may represent a primary (direct) effect of this compound on the expression of these genes and does not apparently involve short-lived repressor protein(s). 相似文献