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91.
Male development of chromosomally female mice transgenic for Sry 总被引:117,自引:0,他引:117
The initiation of male development in mammals requires one or more genes on the Y chromosome. A recently isolated gene, termed SRY in humans and Sry in mouse, has many of the genetic and biological properties expected of a Y-located testis-determining gene. It is now shown that Sry on a 14-kilobase genomic DNA fragment is sufficient to induce testis differentiation and subsequent male development when introduced into chromosomally female mouse embryos. 相似文献
92.
Segregation of a missense mutation in the amyloid precursor protein gene with familial Alzheimer's disease. 总被引:165,自引:0,他引:165
A Goate M C Chartier-Harlin M Mullan J Brown F Crawford L Fidani L Giuffra A Haynes N Irving L James 《Nature》1991,349(6311):704-706
A locus segregating with familial Alzheimer's disease (AD) has been mapped to chromosome 21, close to the amyloid precursor protein (APP) gene. Recombinants between the APP gene and the AD locus have been reported which seemed to exclude it as the site of the mutation causing familial AD. But recent genetic analysis of a large number of AD families has demonstrated that the disease is heterogeneous. Families with late-onset AD do not show linkage to chromosome 21 markers. Some families with early-onset AD show linkage to chromosome 21 markers, but some do not. This has led to the suggestion that there is non-allelic genetic heterogeneity even within early onset familial AD. To avoid the problems that heterogeneity poses for genetic analysis, we have examined the cosegregation of AD and markers along the long arm of chromosome 21 in a single family with AD confirmed by autopsy. Here we demonstrate that in this kindred, which shows linkage to chromosome 21 markers, there is a point mutation in the APP gene. This mutation causes an amino-acid substitution (Val----Ile) close to the carboxy terminus of the beta-amyloid peptide. Screening other cases of familial AD revealed a second unrelated family in which this variant occurs. This suggests that some cases of AD could be caused by mutations in the APP gene. 相似文献
93.
Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere 总被引:15,自引:0,他引:15
Oren R Ellsworth DS Johnsen KH Phillips N Ewers BE Maier C Schäfer KV McCarthy H Hendrey G McNulty SG Katul GG 《Nature》2001,411(6836):469-472
Northern mid-latitude forests are a large terrestrial carbon sink. Ignoring nutrient limitations, large increases in carbon sequestration from carbon dioxide (CO2) fertilization are expected in these forests. Yet, forests are usually relegated to sites of moderate to poor fertility, where tree growth is often limited by nutrient supply, in particular nitrogen. Here we present evidence that estimates of increases in carbon sequestration of forests, which is expected to partially compensate for increasing CO2 in the atmosphere, are unduly optimistic. In two forest experiments on maturing pines exposed to elevated atmospheric CO2, the CO2-induced biomass carbon increment without added nutrients was undetectable at a nutritionally poor site, and the stimulation at a nutritionally moderate site was transient, stabilizing at a marginal gain after three years. However, a large synergistic gain from higher CO2 and nutrients was detected with nutrients added. This gain was even larger at the poor site (threefold higher than the expected additive effect) than at the moderate site (twofold higher). Thus, fertility can restrain the response of wood carbon sequestration to increased atmospheric CO2. Assessment of future carbon sequestration should consider the limitations imposed by soil fertility, as well as interactions with nitrogen deposition. 相似文献
94.
In the fast evolving field of nanoscience and nanotechnology,where size and shape are crucial in deciding the optoelectronic properties of nanomaterials,the understanding of size and shape dependent behavior is of direct relevance to device applications.Present study reports the synthesis of Au nanorods with well controlled aspect ratios,and the influence of the aspect ratio on the surface enhanced Raman scattering(SERS) activity using crystal violet(CV) as the probe molecule.The influence of pH and the concentrations of reducing agent and Ag ions in controlling the aspect ratio of gold nanorods are also investigated.The structural and optical properties of the synthesized samples have been characterized by transmission electron microscopy(TEM) and UV-visible absorption spectroscopy.The nonlinear optical(NLO) transmission of the Au nanorods investigated using the open aperture Z-scan technique revealed the absorption saturation followed by an optical limiting behavior,which may find potential applications in optoelectronic nanodevices. 相似文献
95.
96.
Minagawa H Yoshida Y Kenmochi N Furuichi M Shimada J Kaneko H 《Cellular and molecular life sciences : CMLS》2007,64(1):77-81
Lactate oxidase is used in biosensors to measure the concentration of lactate in the blood and other body fluids. Increasing
the thermostability of lactate oxidase can significantly prolong the lifetime of these biosensors. We have previously obtained
a variant of lactate oxidase from Aerococcus viridans with two mutations (E160G/V198I) that is significantly more thermostable than the wild-type enzyme. Here we have attempted
to further improve the thermostability of E160G/V198I lactate oxidase using directed evolution. We made a mutant lactate oxidase
gene library by applying error-prone PCR and DNA shuffling, and screened for thermostable mutant lactate oxidase using a plate-based
assay. After three rounds of screening we obtained a thermostable mutant lactate oxidase, which has six mutations (E160G/V198I/G36S/T103S/A232S/F277Y).
The half-life of this lactate oxidase at 70 °C was about 2 times that of E160G/V198I and about 36 times that of the wild-type
enzyme. The amino acid mutation process suggests that the combined neutral mutations are important in protein evolution.
Received 15 September 2006; received after revision 21 October 2006; accepted 2 November 2006 相似文献
97.
Crnković-Mertens I Wagener N Semzow J Gröne EF Haferkamp A Hohenfellner M Butz K Hoppe-Seyler F 《Cellular and molecular life sciences : CMLS》2007,64(9):1137-1144
Cancer cells are typically characterized by apoptosis deficiency. In order to investigate a possible role for the anti-apoptotic
livin gene in renal cell cancer (RCC), we analyzed its expression in tumor tissue samples and in RCC-derived cell lines. In addition,
we studied the contribution of livin to the apoptotic resistance of RCC cells by RNA interference (RNAi). Livin gene expression was detected in a significant portion of RCC tumor tissue specimens (13/14, 92.9%) and tumor-derived cell
lines (12/15, 80.0%). Moreover, targeted inhibition of livin by RNAi markedly sensitized RCC cells towards proapoptotic stimuli, such as UV irradiation or the chemotherapeutic drugs
etoposide, 5-fluorouracil, and vinblastine. These effects were specific for livin expressing tumor cells. We conclude that livin can contribute significantly to the apoptosis resistance of RCC cells. Targeted inhibition of livin could represent a novel therapeutic strategy to increase the sensitivity of renal cancers towards pro-apoptotic agents.
Received 30 November 2006; received after revision 22 February 2007; accepted 20 March 2007 相似文献
98.
Larrucea S Butta N Rodriguez RB Alonso-Martin S Arias-Salgado EG Ayuso MS Parrilla R 《Cellular and molecular life sciences : CMLS》2007,64(22):2965-2974
Podocalyxin (PODXL) is a mucin protein of the CD34 family expressed in kidney glomerular podocytes, vascular endothelium,
progenitor bone marrow and tumor cells. It is assumed that PODXL plays an anti-adherent role in kidney podocytes. CHO cells
stably expressing human PODXL (CHO-PODXL) or human tumor cells (Tera-1) inherently expressing PODXL showed increased adherence
to platelets. The adherence of cells was inhibited (70%) by blockers of platelet P-selectin, prevented by the soluble ectodomain
of human PODXL (PODXL-Δ) or by the arginine-glycine-aspartate (RGDS) peptide and partially impeded by inhibition of integrin
αVβ3/αVβ5, suggesting a coordinated action of P-selectin and integrins. Colocalization of platelet P-selectin and PODXL expressed
on CHO cells was demonstrated by confocal immunofluorescence. No adherence to platelets was observed when PODXL was expressed
in glycomutant CHO cells deficient in sialic acid.
Received 14 August 2007; received after revision 12 September 2007; accepted 13 September 2007 相似文献
99.
100.
Samuel CS Hewitson TD Unemori EN Tang ML 《Cellular and molecular life sciences : CMLS》2007,64(12):1539-1557
The peptide hormone relaxin is emerging as a multi-functional factor in a broad range of target tissues including several
non-reproductive organs, in addition to its historical role as a hormone of pregnancy. This review discusses the evidence
that collectively demonstrates the many diverse and vital roles of relaxin: the homeostatic role of endogenous relaxin in
mammalian pregnancy and ageing; its gender-related effects; the therapeutic effects of relaxin in the treatment of fibrosis,
inflammation, cardioprotection, vasodilation and wound healing (angiogenesis) amongst other pathophysiological conditions,
and its potential mechanism of action. Furthermore, translational issues using experimental models (to humans) and its use
in various clinical trials, are described, each with important lessons for the design of future trials involving relaxin.
The diverse physiological and pathological roles for relaxin have led to the search for its significance in humans and highlight
its potential as a drug of the future.
Received 12 December 2006; received after revision 12 February 2007; accepted 15 March 2007 相似文献