[Show abstract][Hide abstract] ABSTRACT: Forward genetic screens in mice provide an unbiased means to identify genes and other functional genetic elements in the genome. Previously, a large scale ENU mutagenesis screen was conducted to query the functional content of a ~50 Mb region of the mouse genome on proximal Chr 5. The majority of phenotypic mutants recovered were embryonic lethals.
We report the high resolution genetic mapping, complementation analyses, and positional cloning of mutations in the target region. The collection of identified alleles include several with known or presumed functions for which no mutant models have been reported (Tbc1d14, Nol14, Tyms, Cad, Fbxl5, Haus3), and mutations in genes we or others previously reported (Tapt1, Rest, Ugdh, Paxip1, Hmx1, Otoe, Nsun7). We also confirmed the causative nature of a homeotic mutation with a targeted allele, mapped a lethal mutation to a large gene desert, and localized a spermiogenesis mutation to a region in which no annotated genes have coding mutations. The mutation in Tbc1d14 provides the first implication of a critical developmental role for RAB-GAP-mediated protein transport in early embryogenesis.
This collection of alleles contributes to the goal of assigning biological functions to all known genes, as well as identifying novel functional elements that would be missed by reverse genetic approaches.
[Show abstract][Hide abstract] ABSTRACT: PDCD2 is a conserved eukaryotic protein implicated in cell cycle regulation by virtue of its interactions with HCFC1 and the NCOR1/SIN3A corepressor complex. Pdcd2 transcripts are enriched in ES cells and other somatic stem cells, and its ortholog is essential for hematopoietic stem cell maintenance in Drosophila. To characterize the physiological role(s) of mammalian PDCD2, we created a disruption allele in mice. Pdcd2(-/-) embryos underwent implantation but did not undergo further development. Inner cell masses (ICMs) from Pdcd2(-/-) blastocysts failed to outgrow in vitro. Furthermore, embryonic stem cells (ESCs) require PDCD2 as demonstrated by the inability to generate Pdcd2(-/-) ESCs in the absence of an ectopic transgene. Upon differentiation of ESCs by retinoic acid treatment or LIF deprivation, PDCD2 levels declined. In conjunction with prior studies, these results indicate that in vivo, PDCD2 is critical for blastomere and ESC maintenance by contributing to the regulation of genes in a manner essential to the undifferentiated state of these cells.
Full-text · Article · Nov 2010 · Developmental Biology
[Show abstract][Hide abstract] ABSTRACT: Pax transactivation domain-interacting protein (PTIP, or PAXIP1) is required for mouse development and has been implicated
in DNA damage responses and histone modification. However, the physiological roles of PTIP during embryogenesis remain unclear
due to early embryonic lethality of null mutants. We describe two N-ethyl N-nitrosourea-induced hypomorphic missense alleles of Ptip, each of which alters one of the six encoded BRCT domains. Phenotypic characterization of these mutants revealed important
functions of PTIP in vasculogenesis and chorioplacental development that appear unrelated to activities in DNA repair or global
histone modification. The results of gene expression profiling and in vitro angiogenesis assays indicated that PTIP modulates
a transcriptional program, centered around Vegfa, that drives the migration of endothelial cells to properly form the embryonic vasculature. These and other data suggest
that PTIP has multiple functions, one of which is to promote the formation of transcriptional complexes that provide specificity
of developmental gene expression.
[Show abstract][Hide abstract] ABSTRACT: To compare the toxicity between sodium selenite and selenomethionine (SeM) and to investigate the indicators of selenium toxicity.
Weanling Wistar rats of both sexes were randomly divided into seven groups, 14 rats each group. One group was fed basal diet and the others were fed basal diets containing 3, 6, 10 mg greater than that of SeM and female rats were more sensitive to excessive selenium than male rats. Se/kg added as sodium selenite or SeM for 12 weeks.
Histopathological changes of the liver were observed in rats on Se 3 mg/kg diets while the decreasing of body weight occurred in rats on 6 Se mg/kg diet. Among the rats fed Se 6, 10 mg/kg diet, the body weight of rats in selenite-treated groups was lower than that of rats in SeM-treated groups. At the 3 or 6 mg/kg Se level, the rats fed SeM suffered slighter hepatic damage than those fed sodium selenite and in male rats slighter than female rats. The abnormal change of ratio of liver weight to body weight was found to be more obvious both in female rats and in selenite-treated rats. GPX activity in liver of female rats reduced with the increase of Se level in diets. However, GPX activity in RBC, plasma, kidneys and liver showed an ascending tendency with the increasing level of dietary Se.
The minimum dose of intoxication of Se in diet may be around 3 mg/kg. The toxicity of selenite is greater than that of SeM and female rats were more sensitive to excessive selenium than male rats.
No preview · Article · Dec 2004 · Wei sheng yan jiu = Journal of hygiene research
[Show abstract][Hide abstract] ABSTRACT: Insulin resistance, a hallmark of type 2 diabetes, is associated with oxidative stress. However, the role of reactive oxygen species or specific antioxidant enzymes in its development has not been tested under physiological conditions. The objective of our study was to investigate the impact of overexpression of glutathione peroxidase 1 (GPX1), an intracellular selenoprotein that reduces hydrogen peroxide (H(2)O(2)) in vivo, on glucose metabolism and insulin function. The GPX1-overexpressing (OE) and WT male mice (n = 80) were fed a selenium-adequate diet (0.4 mg/kg) from 8 to 24 weeks of age. Compared with the WT, the OE mice developed (P < 0.05) hyperglycemia (117 vs. 149 mg/dl), hyperinsulinemia (419 vs. 1,350 pg/ml), and elevated plasma leptin (5 vs. 16 ng/ml) at 24 weeks of age. Meanwhile, these mice were heavier (37 vs. 27 g, P < 0.001) and fatter (37% vs. 17% fat, P < 0.01) than the WT mice. At 30-60 min after an insulin challenge, the OE mice had 25% less (P < 0.05) of a decrease in blood glucose than the WT mice. Their insulin resistance was associated with a 30-70% reduction (P < 0.05) in the insulin-stimulated phosphorylations of insulin receptor (beta-subunit) in liver and Akt (Ser(473) and Thr(308)) in liver and soleus muscle. Here we report the development of insulin resistance in mammals with elevated expression of an antioxidant enzyme and suggest that increased GPX1 activity may interfere with insulin function by overquenching intracellular reactive oxygen species required for insulin sensitizing.
Full-text · Article · Jun 2004 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: A method for the detection of the (genetically modified organism GMOs) in genetically modified soybean (Round-up Ready soybean, RR soybean) and maize(Bt-176 maize) is described. The polymerase chain reaction (PCR) method is discussed with the genetically modified soybean and maize whose contents are known. The detection limit can be 0.1%, that is to say, we can detect the GMO in the food whose content is only 0.1%, the detection method is just a screening method. The procedure includes: (1) extraction of genomic DNA of maize and soybean, (2) amplification of the inserted genes, CaMV35S promoter and the NOS terminator inserted by means of the polymerase chain reaction (PCR) method, (3) amplification of the specific genes of maize and soybean in order to determine that the samples are maize and soybean, (4) characterization and confirmation of the PCR products by restriction enzyme analysis and the electrophoresis on agarose gel. The RR soybean contains CaMV35S promoter and NOS terminator, and the Bt-176 maize contains only CaMV35S promoter. Due to the high content of the starch in maize, the effect of the electrophororesis is not so good as of the soybean's.
No preview · Article · Jul 2002 · Wei sheng yan jiu = Journal of hygiene research