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排序方式: 共有149条查询结果,搜索用时 31 毫秒
91.
92.
Bovine SNRPN methylation imprint in oocytes and day 17 in vitro-produced and somatic cell nuclear transfer embryos 总被引:4,自引:0,他引:4
Lucifero D Suzuki J Bordignon V Martel J Vigneault C Therrien J Filion F Smith LC Trasler JM 《Biology of reproduction》2006,75(4):531-538
Findings from recent studies have suggested that the low survival rate of animals derived via somatic cell nuclear transfer (SCNT) may be in part due to epigenetic abnormalities brought about by this procedure. DNA methylation is an epigenetic modification of DNA that is implicated in the regulation of imprinted genes. Genes subject to genomic imprinting are expressed monoallelically in a parent of origin-dependent manner and are important for embryo growth, placental function, and neurobehavioral processes. The vast majority of imprinted genes have been studied in mice and humans. Herein, our objectives were to characterize the bovine SNRPN gene in gametes and to compare its methylation profile in in vivo-produced, in vitro-produced, and SCNT-derived Day 17 elongating embryos. A CpG island within the 5' region of SNRPN was identified and examined using bisulfite sequencing. SNRPN alleles were unmethylated in sperm, methylated in oocytes, and approximately 50% methylated in somatic samples. The examined SNRPN region appeared for the most part to be normally methylated in three in vivo-produced Day 17 embryos and in eight in vitro-produced Day 17 embryos examined, while alleles from Day 17 SCNT embryos were severely hypomethylated in seven of eight embryos. In this study, we showed that the SNRPN methylation profiles previously observed in mouse and human studies are also conserved in cattle. Moreover, SCNT-derived Day 17 elongating embryos were abnormally hypomethylated compared with in vivo-produced and in vitro-produced embryos, which in turn suggests that SCNT may lead to faulty reprogramming or maintenance of methylation imprints at this locus. 相似文献
93.
Hanessian S Simard D Bayrakdarian M Therrien E Nilsson I Fjellström O 《Bioorganic & medicinal chemistry letters》2008,18(6):1972-1976
Guided by available X-ray crystal structure data on the serine protease thrombin, a series of pyridin-2-one derivatives were designed and synthesized having diverse functionality at the P(1) and P(3) sites. Potent in vitro activity against thrombin, with excellent selectivity over trypsin was found for selected analogues. 相似文献
94.
Absorption cytophotometry was used to measure nuclear Feulgen-DNA content of myxamoebae and Plasmodia in seven heterothallic isolates of Didymium iridis. Measurements of myxamoebal nuclei from clones of four isolates (Hon 1, Pan 1, Pan 2, and CR 5) gave a mean DNA value of 0.34, whereas the nuclei of Plasmodia which develop from each of the four intraisolate crosses had a mean value of 0.63. These values correspond to the 2C haploid level in myxamoebae and the 4C diploid level in Plasmodia. DNA values in two additional isolates (Pan 3 and CR 2) are much higher than the mean for the other five. Accordingly, it is proposed that these may be polyploid. The question of polyploidy in D. iridis and in other myxomycetes is evaluated. The seventh isolate, Ky 1, is taxonomically very close to D. nigripes and was not included in calculations of mean values for D. iridis. 相似文献
95.
In crosses involving a polyploid myxamoebal clone. CR 2-25*, F1 plasmodia and myxamoebae display a variety of unexpected ploidy levels as indicated by nuclear DNA measurements. Genetic analyses of the F1 generations reveal either complete elimination of certain genetic markers or greatly skewed segregation ratios. On the basis of these two kinds of evidence, it is assumed that chromosome elimination occurs at some stage (or stages) following karyogamy between parental nuclei. The possible significance of polyploidy in relation to myxomycete speciation and evolution is discussed. 相似文献
96.
97.
Stefani Daryanto Lixin Wang William P. Gilhooly III Pierre-André Jacinthe 《Journal of Plant Ecology》2019,12(2):235
Aims
Nitrogen (N) in natural environments is typically supplied by a mixture of ammonia (NH4+) and nitrate (NO3-). However, factors that underlie either NH4+or NO3-preference, and how such preference will change across generations remain unclear. We conducted a series of experiments to answer whether: (i) NH4+:NO3-ratio is the driving factor for plant N preference, and (ii) this preference is consistent across generations. 相似文献
98.
Alastair Franke Jean‐François Therrien Sébastien Descamps Joël Bêty 《Journal of avian biology》2011,42(6):544-551
In long‐lived species, population growth rate is highly sensitive to changes in adult survival. Despite the growing concerns regarding recent climate changes, few studies have investigated the effect of climatic conditions on survival in long‐lived wildlife that are either resident or breed in the Arctic. In this study, we evaluated the effect of climate across the annual life cycle (breeding, outward migration, wintering, and inward migration) on apparent annual survival of arctic‐breeding peregrine falcons. From 1982 to 2008, peregrine falcons breeding near Rankin Inlet, Nunavut, Canada were monitored, in part, to assess apparent annual survival (the product of true survival and site fidelity) using re‐observations of marked individuals. Our study indicated that apparent annual survival of adult peregrine falcons was correlated with indices of climatic conditions during outward migration (i.e., flight from the Arctic breeding grounds). These climatic indices (fall NAO of the current year and fall NAO with a lag of one year) explained 35% of the temporal variation in apparent annual survival of peregrine falcons. Our results suggest that this top‐predator is vulnerable to weather‐related environmental conditions encountered during fall migration. 相似文献
99.
Sukhdev Manku Martin Allan Natalie Nguyen Alain Ajamian Jacques Rodrigue Eric Therrien James Wang Tim Guo Jubrail Rahil Andrea J. Petschner Alina Nicolescu Sylvain Lefebvre Zuomei Li Marielle Fournel Jeffrey M. Besterman Robert Déziel Amal Wahhab 《Bioorganic & medicinal chemistry letters》2009,19(7):1866-1870
We have recently reported on a novel class of histone deacetylase (HDAC) inhibitors bearing a sulfamide group as the zinc-binding unit. Herein, we report on the synthesis of sulfamide based inhibitors designed around a lysine scaffold and their structure–activity relationships against HDAC1 and HDAC6 isotypes as well as 293T cells. Our efforts led us to an improvement of the originally disclosed lysine-based sulfamide, 2a to compound 12h which has equal potency in enzyme and cell-based assays as well as enhanced metabolic stability and PK profile. 相似文献
100.
Eric Therrien Guillaume Larouche Sukhdev Manku Martin Allan Natalie Nguyen Sylvia Styhler Marie-France Robert Anne-Christine Goulet Jeffrey M. Besterman Hannah Nguyen Amal Wahhab 《Bioorganic & medicinal chemistry letters》2009,19(23):6725-6732
We have identified the N1-benzyl-N2-methylethane-1,2-diamine unit as a substitute for the (S)-alanine benzylamide moiety for the design of co-activator associated arginine methyltransferase 1 (CARM1) inhibitors. The potency of these inhibitors is in the same order of magnitude as their predecessors and their clearance, volume of distribution, and half lives were greatly improved. 相似文献