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Ling Bai

Publications and source records attributed to Ling Bai.

15 recordsLinked to original sources
PubMed2006

Generating novel allelic variation through Activator insertional mutagenesis in maize.

The maize transposable element Activator (Ac) has been exploited as an insertional mutagen to disrupt, clone, and characterize genes in a number of plant species. To develop an Ac-based mutagenesis platform for maize, a large-scale mutagenesis was conducted targeting the pink scutellum1 locus. We selected 1092 Ac transposition events from a closely linked donor Ac, resulting in the recovery of 17 novel ps1 alleles. Multiple phenotypic classes were identified corresponding to Ac insertions in the 5'-UTR and coding region of the predicted Ps1 gene. To generate a stable allelic series, we employed genetic screens and identified 83 germinally heritable ps1 excision alleles. Molecular characterization of these excision alleles revealed a position-dependent bias in excision allele frequencies and the predominance of 7- and 8-bp footprint products. In total, 19 unique ps1 excision alleles were generated in this study, including several that resulted in weak mutant phenotypes. The analysis of footprint alleles suggests a model of Ac excision in maize that is consistent with recent in vitro studies of hAT element excision. Importantly, the genetic and molecular methods developed in this study can be extended to generate novel allelic variation at any Ac-tagged gene in the genome.

Alleles↗
PubMed2006

Coculture with endothelial cells enhances vascular smooth muscle cell adhesion and spreading via activation of beta1-integrin and phosphatidylinositol 3-kinase/Akt.

The interactions between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) play significant roles in the homeostasis of the blood vessel during vascular remodeling. Cell adhesion and spreading are an essential process for VSMC migration, survival and proliferation in the events of vascular physiology and pathophysiology. However, effects of ECs on adhesion and spreading of VSMCs have not been characterized yet. Here, the interaction of ECs and VSMCs on adhesion and spreading of VSMCs were investigated by using a coculture system. The results showed that VSMCs cocultured with ECs exhibited a significant increase in the number of adherent and spreading cells, and much more mRNA (twofold, P<0.01) and protein (threefold, P<0.05) expression of beta(1)-integrin comparing to the control, i.e., VSMCs cultured alone. Furthermore, the enhanced functional activity of beta(1)-integrin expression was confirmed by FACS. A beta(1)-integrin blocking antibody (P5D2) could inhibit the EC-induced VSMC adhesion and spreading. It was demonstrated that in correspondence with enhanced cell adhesion, ECs also prompted focal adhesion complex assembly and stress fiber formation of VSMCs. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway was more pronouncedly activated in response to VSMC attachment. Our results for the first time show that coculture with ECs enhances VSMC adhesion and spreading by up-regulating beta(1)-integrin expression and activating the PI3K/Akt pathway, suggesting that the interaction between ECs and VSMCs serves an important role in vascular homeostasis and remodeling.

Cell Adhesion↗
PubMed2005

The effects of aging on different C-terminal splice forms of the zeta1(NR1) subunit of the N-methyl-d-aspartate receptor in mice.

Changes in NMDA receptors in the prefrontal/frontal cortex and hippocampus of C57BL/6 mice during aging show a relationship to declines in spatial learning. The present study was designed to determine whether aging influences the mRNA expression of different splice forms of the zeta1 subunit of the NMDA receptor. We examined the mRNA of 4 C-terminal splice forms with the use of in situ hybridization. The zeta1-1 splice form (+C1 and +C2 cassettes) overall showed a maintenance of mRNA density from 3 to 10 months of age, followed by a significant decline by 26 months of age. In contrast, the mRNA for the zeta1-3 splice form [+C1 and +C2'(-C2)] showed significant declines between 3- and 10-month-old mice. These declines were maintained in the old mice. The zeta1-2 splice form (-C1 and +C2) showed a near-significant decrease in expression during aging across all brain regions. The zeta1-4 subunit mRNA [-C1 and +C2' (-C2)] showed no significant changes with increased age. These results indicate that there is a differential effect of aging on different splice variants of the zeta1 subunit of the NMDA receptor and those that are affected show a different temporal pattern of aging. This heterogeneity has implications for producing imbalances in the modulation of the remaining receptors.

Aging↗
PubMed2005

Tissue factor as a link between wounding and tissue repair.

The initial phase of wound repair involves inflammation, induction of tissue factor (TF), formation of a fibrin matrix, and growth of new smooth muscle actin (alpha-SMA)-positive vessels. In diabetes, TF induction in response to cutaneous wounding, which ordinarily precedes increased expression of vascular endothelial growth factor (VEGF) and alpha-SMA transcription, is diminished, though not to a degree causing excessive local bleeding. Enhanced TF expression in wounds of diabetic mice caused by somatic TF gene transfer increased VEGF transcription and translation and, subsequently, enhanced formation of new blood vessels and elevated blood flow. Furthermore, increased levels of TF in wounds of diabetic mice enhanced wound healing; the time to achieve 50% wound closure was reduced from 5.5 days in untreated diabetic mice to 4.1 days in animals undergoing TF gene transfer (this was not statistically different from wound closure in nondiabetic mice). Thus, cutaneous wounds in diabetic mice display a relative deficiency of TF compared with nondiabetic controls, and this contributes to delayed wound repair. These data establish TF expression as an important link between the early inflammatory response to cutaneous wounding and reparative processes.

Animals↗
PubMed2004

Apoptosis pathway of liver cells in chronic hepatitis.

AIM: To study the pathway of apoptosis in chronic liver disease and the role of mitochondria in programmed cell death. METHODS: Liver biopsy specimens from 72 cases of chronic hepatitis and 29 cases of post hepatitis cirrhosis were studied. The pro-apoptotic protein Fas, FasL, Bax and the anti-apoptotic protein Bcl-2, Bcl-x(L), Bcl-2 alpha were studied immunohistochemically by SP method. Specimens from 15 cases of chronic hepatitis and post hepatitis cirrhosis were examined for their ultramicrostructures with special attention to their mitochondrial changes. Specimens from 3 normal adults (demised in traffic accidents) were used as control. RESULTS: The expression of proapoptotic proteins (Fas, FasL, Bax) in hepatocytes was significantly higher in the chronic hepatitis group than in the cirrhosis group (P<0.001). In the study of ultramicrostructure 364 hepatocytes were examined, from 12 cases of chronic hepatitis (including 10 mild cases, 1 moderate case and 1 severe case). Out of 364 hepatocytes 40 (11.0%) hepatocytes were found with various kinds of destruction in their mitochondria. Rupture of the outer membrane of mitochondria and the leakage of matrix from the intermembrane space were definitely demonstrated. The ultramicrostructural changes of mitochondria in the chronic hepatitis group were statistically higher than that in normal adults control group (chi(2)=4.32, P<0.05). CONCLUSION: The result of the study was in support of the current view that the apoptotic process in chronic hepatitis patients were largely along the intrinsic pathway (mitochondrial pathway), given that the intrinsic and extrinsic pathways could interlinked (converged) at some point on their progression, also it is impossible at present to exclude the possibility that the two pathways could be chosen by hepatocytes in parallel simultaneously.

Apoptosis↗
PubMed2004

Changes in the expression of the NR2B subunit during aging in macaque monkeys.

Humans, non-human primates and rodents show declines in spatial memory abilities with increased age. Some of these declines in mice are related to changes in the expression of the epsilon2 (epsilon2) (NR2B) subunit of the N-methyl-D-aspartate receptor. The purpose of this study was to determine whether primates show changes during aging in the mRNA expression of the NR2B subunit. In situ hybridization was performed on tissue sections from three different ages of Rhesus monkeys (Macaca mulatta; 6-8, 10-12, and 24-26 years). There was a significant decrease in the mRNA expression of the NR2B subunit overall in the prefrontal cortex and in the caudate nucleus between young and old monkeys. There were no significant changes in NR2B mRNA expression in the hippocampus or the parahippocampal gyrus. The results in the prefrontal cortex, caudate and hippocampus were similar to those seen previously in C57BL/6 mice during aging, which suggests that mice may be useful as a model for primates to further examine the age-related changes in the expression of the NR2B subunit of the NMDA receptor in several important regions of the brain.

Aging↗
PubMed2004

Expression of hepatitis B virus antigen and Helicobacter pylori infection in gastric mucosa of patients with chronic liver disease.

BACKGROUND: It is common for the gastroendoscopist to find patients infected simultaneously with hepatitis B virus (HBV) and Helicobacter pylori (H pylori). Considering that HBV infection is linked to hepatocellular carcinoma and H pylori to gastric cancer, we investigated the incidence in this kind of patients in the northern Jiangsu Province, China. Rational management of these patients was also discussed. METHODS: Seventy-two patients including 28 patients with chronic hepatitis B and 44 patients with post hepatitis B liver cirrhosis served as observation group. Thirty patients with gastritis but without liver disease were included as controls. Diagnostic endoscopy was performed in all the patients. Three biopsy specimens were taken from the pyloric antrum 3 cm from the pyloric ring. Urease test staining of hematoxylin and eosin or fuchsin, and immunohistochemical analysis of H pylori IgG antigen and HBV antigen (HBsAg, HBcAg) were performed. RESULTS: The extent and intensity of chronic inflammation were identified in 95.5% (42/44) of the antrum mucosa of the patients with cirrhosis and in 92.9% (26/28) of the patients with chronic hepatitis. The expression of H pylori in the mucosa was found in 29 of the 42 patients with cirrhosis associated with antrum inflammation (69.0%). The expression of H pylori was observed in 20 of the 26 patients with chronic hepatitis combined with antrum inflammation (76.9%). No significant difference existed between the cirrhosis group and the chronic hepatitis group. The rates of HBV antigen expression in the H pylori positive and negative gastric antrum mucosa were 69.8% (37/53)and 73.7% (14/19), respectively (P>0.05). CONCLUSIONS: Over-expression of HBV antigen (HBsAg and HBcAg) coexists with the expression of H pylori antigen in the H pylori infected gastric mucosa. Difficult clearance of HBsAg and HBcAg from gastric epithelial cells may be related to persistent H pylori infection. Early treatment of H pylori infection may be beneficial to the prognosis of patients with chronic liver disease.

China↗
PubMed2003

Age-related deficits in mice performing working memory tasks in a water maze.

This study determined whether mice exhibit spatial working memory deficits with increased age. C57BL/6JNia mice of 3 different ages were tested in the Morris water maze with 2 protocols designed to assess immediate and delayed working memory abilities. Young mice required multiple trials in order to show improvements in the working memory task. Deficits in immediate working memory were detected in both 10- and 24- to 26-month-old mice. Reference memory deficits and declines in performance in the delayed working memory task were only seen in 24- to 26-month-olds. This increased susceptibility of immediate working memory processes to the aging process in mice may be related to their need for more rehearsal in the water maze than other species.

Aging↗
PubMed2003

Comparison of opioid and alpha-2 adrenergic receptor binding in horse and dog brain using radioligand autoradiography.

OBJECTIVE: To test the hypothesis that the distribution, density, and subtype of opioid and alpha (alpha)-2 adrenergic receptors within the central nervous system (CNS) are significantly different between horse and dog. STUDY DESIGN: Prospective experimental study. ANIMALS: Three dogs (3 years of age) and three horses (2-5 years of age). Animals were opioid- and alpha-2 agonist-free at the time of euthanasia. METHODS: Brain tissue was obtained at 126 days post-surgery from dogs and 72 days post-surgery from horses. The brains were removed, sectioned coronally into 1-cm slabs, frozen in methylbutane, which was cooled by liquid nitrogen, and stored at -70 degrees C. Receptor autoradiography was performed using established techniques. [3H]DAMGO, [3H]U-69593, and [3H]RX821002 were used for mu ( micro )-opioid, kappa (kappa)-opioid, and alpha-2 adrenergic-binding assays, respectively. Species differences were analyzed separately for each major brain region by repeated measures anova for subregions followed by Fisher's protected Latin square design (LSD). p < 0.05 was considered significant. RESULTS: There was higher binding of micro -opioid receptors in the frontal cortex, left somatosensory cortex, colliculus (mid-brain), and granule cell layer of the cerebellum of horses than that of dogs. There was higher binding to kappa-opioid receptors in the frontal cortex of dogs compared to horses, whereas binding to kappa-opioid receptors in the cerebellum was higher in horses. Binding to alpha-2 adrenergic receptors in the mid-brain was significantly higher in dogs than in horses. There was higher binding of alpha-2 adrenergic receptors in the dorsomedial and dorsolateral periaqueductal grey of dogs as compared to that of horses. CONCLUSION: The results of this study show that the distribution of these receptors is different between horses and dogs. Further work is needed to understand the relevance of these differences to clinical responses to opioids and alpha-2 adrenergic agonists in these species.

Animals↗
PubMed2003

Activator mutagenesis of the pink scutellum1/viviparous7 locus of maize.

The transposable elements Activator/Dissociation (Ac/Ds) were first discovered in maize, yet they have not been used extensively in their native host for gene-tagging experiments. This can be attributed largely to the low forward mutation rate and the propensity for closely linked transpositions associated with Ac and its nonautonomous deletion derivative Ds. To overcome these limitations, we are developing a series of nearly isogenic maize lines, each with a single active Ac element positioned at a well-defined location. These Ac elements are distributed at 10- to 20-centimorgan intervals throughout the genome for use in regional mutagenesis. Here, we demonstrate the utility of this Ac-based gene-tagging approach through the targeted mutagenesis of the pink scutellum1/viviparous7 (ps1/vp7) locus. Using a novel PCR-based technique, the Ps1 gene was cloned and Ac elements positioned precisely in each of the seven alleles recovered. The Ps1 gene is predicted to encode lycopene beta-cyclase and is necessary for the accumulation of both abscisic acid and the carotenoid zeaxanthin in mature maize embryos. This study demonstrates the utility of an Ac mutagenesis program to efficiently generate allelic diversity at closely linked loci in maize.

Abscisic Acid↗
PubMed2003

Variation and significance of microtubules in rat volume overload cardiac hypertrophy.

OBJECTIVE: To investigate the function of microtubules in volume overload cardiac hypertrophy of rat. METHODS: The structure of microtubules was observed using an immunofluorescent microscope, while the pixel intensity and distribution of microtubule imaging was estimated from laser scanning confocal images of left ventricular cardiocytes immuno-labeled with an antibody to beta-tubulin. RESULTS: The pixels of the microtubule image taken just after volume overload were not evenly distributed. At 6 hours after overload, the pixel intensity of the microtubule image was decreased to less than 150 (arbitrary units), which was the same as the pixel intensity and distribution of the colchicine depolymerized microtubule image. The changes were partially recovered to 200 (arbitrary units) after 4 more days. The pixel intensity of the control microtubule image was 250 (arbitrary units) and had an even distribution. The structuring of the microtubules was more disordered as volume overload hypertrophy developed. CONCLUSIONS: There are disorders in the signal transduction pathways governing the hypertrophic response of cardiomyocytes in the hypertrophic myocardium and microtubule is one of the members of the signal transduction pathways governing the hypertrophic response of cardiomyocytes in the hypertrophic myocardium. The disordered microtubule array may be targeted during heart failure treatment.

Animals↗
PubMed2002

[Differentially expressed genes in vascular endothelial cell line ECV 304 induced by high density lipoprotein].

OBJECTIVE: To isolate and clone the differentially expressed genes in vascular endothelial cell induced by high density lipoprotein (HDL) so as to study the anti- atherogenesis molecular mechanism of HDL. METHODS: Differential display reverse transcription PCR method was used to analyze the differentially expressed cDNA in vascular endothelial cell line ECV 304 induced by HDL. After sequencing and homology research, several differentially expressed cDNA fragments were confirmed by Northern blot analysis. RESULTS: Up-regulated and down-regulated cDNA fragments in ECV 304 induced by HDL were isolated. Nine cDNA fragments were highly homologous to the known human genes and four were fragments of novel genes. The known up-regulated genes included genes of human STE20-like kinase, PBK1 protein, transglutaminase, myosin alkali light chain, apobec-1 binding protein 1, and death- associated protein (DAP). The known down-regulated genes included genes of ribosomal protein L7a (RPL7A), voltage-dependent anion channel isoform 2, and glycinamide ribonucleotide transformylase. Northern blot analysis revealed that the expression levels of transglutaminase and apobec-1 binding protein 1 were upregulated by 50% and 70% respectively. CONCLUSION: HDL upregulates the expression of apobec-1 binding protein 1 and transglutaminase in endothelial cells. The high level expression of transglutaminase and apobec-1 binding protein 1 in endothelial cells induced by HDL may be related to anti-atherogenesis function of HDL.

Blotting, Northern↗
PubMed2002

[Experimental methods for mechanically stimulating the cells in vitro].

Cellular mechanics is a branch of tissue engineering and cellular engineering. As one of the important method, loading different mechanical stimuli to culturing cells in vitro so as to study the influence that the stress has on the cells is one of the important fields of cellular mechanics. This paper reviews the experimental methods for mechanically stimulating the cells in vitro, according to the different loading modalities, the methods can be categorized into micropipette aspiration, compression loading, substrate distention, fluid shear, etc. And it also points out their advantages and disadvantages.

Cell Culture Techniques↗