Browsing by Author "Zhang, Song"

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    Development of Efficient Plant Regeneration and Transformation System for Impatiens Using Agrobacterium tumefaciens and Multiple Bud Cultures as Explants
    Dan, Yinghui; Baxter, Aaron; Zhang, Song; Pantazis, Christopher J.; Veilleux, Richard E. (BMC, 2010-08-09)
    Background: Impatiens (Impatiens walleriana) is a top selling floriculture crop. The potential for genetic transformation of Impatiens to introduce novel flower colors or virus resistance has been limited by its general recalcitrance to tissue culture and transformation manipulations. We have established a regeneration and transformation system for Impatiens that provides new alternatives to genetic improvement of this crop. Results: In a first step towards the development of transgenic INSV-resistant Impatiens, we developed an efficient plant regeneration system using hypocotyl segments containing cotyledonary nodes as explants. With this regeneration system, 80% of explants produced an average of 32.3 elongated shoots per initial explant plated, with up to 167 elongated shoots produced per explant. Rooting efficiency was high, and 100% of shoots produced roots within 12 days under optimal conditions, allowing plant regeneration within approximately 8 weeks. Using this regeneration system, we developed an efficient Agrobacterium-mediated Impatiens transformation method using in vitro multiple bud cultures as explants and a binary plasmid (pHB2892) bearing gfp and nptII genes. Transgenic Impatiens plants, with a frequency up to 58.9%, were obtained within 12 to 16 weeks from inoculation to transfer of transgenic plants to soil. Transgenic plants were confirmed by Southern blot, phenotypic assays and T1 segregation analysis. Transgene expression was observed in leaves, stems, roots, flowers, and fruit. The transgenic plants were fertile and phenotypically normal. Conclusion: We report the development of a simple and efficient Agrobacterium-mediated transformation system for Impatiens. To the best of our knowledge, there have been no reports of Agrobacterium-mediated transformation of Impatiens with experimental evidence of stable integration of T-DNA and of Agrobacterium-mediated transformation method for plants using in vitro maintained multiple bud cultures as explants. This transformation system has the advantages of 1) efficient, simple and rapid regeneration and transformation (with no need for sterilization or a greenhouse to grow stock plants), 2) flexibility (available all the time) for in vitro manipulation, 3) uniform and desirable green tissue explants for both nuclear and plastid transformation using Agrobacteriummediated and biolistics methods, 4) no somaclonal variation and 5) resolution of necrosis of Agrobacteriuminoculated tissues.
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    Epigenetic modulation of inflammation and synaptic plasticity promotes resilience against stress in mice
    Wang, Jun; Hodes, Georgia E.; Zhang, Hongxing; Zhang, Song; Zhao, Wei; Golden, Sam A.; Bi, Weina; Menard, Caroline; Kana, Veronika; Leboeuf, Marylene; Xie, Marc; Bregman, Dana; Pfau, Madeline L.; Flanigan, Meghan E.; Estebam-Fernández, Adelaida; Yemul, Shrishailam; Sharma, Ali; Ho, Lap; Dixon, Richard A.; Merad, Miriam; Han, Ming-Hu; Russo, Scott J.; Pasinetti, Giulio M. (Nature, 2018)
    Major depressive disorder is associated with abnormalities in the brain and the immune system. Chronic stress in animals showed that epigenetic and inflammatory mechanisms play important roles in mediating resilience and susceptibility to depression. Here, through a highthroughput screening, we identify two phytochemicals, dihydrocaffeic acid (DHCA) and malvidin-3′-O-glucoside (Mal-gluc) that are effective in promoting resilience against stress by modulating brain synaptic plasticity and peripheral inflammation. DHCA/Mal-gluc also significantly reduces depression-like phenotypes in a mouse model of increased systemic inflammation induced by transplantation of hematopoietic progenitor cells from stresssusceptible mice. DHCA reduces pro-inflammatory interleukin 6 (IL-6) generations by inhibiting DNA methylation at the CpG-rich IL-6 sequences introns 1 and 3, while Mal-gluc modulates synaptic plasticity by increasing histone acetylation of the regulatory sequences of the Rac1 gene. Peripheral inflammation and synaptic maladaptation are in line with newly hypothesized clinical intervention targets for depression that are not addressed by currently available antidepressants.
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    An evaluation of visual and verbal based standards for landscape assessment
    Zhang, Song (Virginia Tech, 1994)
    Existing verbal standards accepted in visual resource management (U.S.D.A. Forest Service, 1975 and U.S.D.I., Bureau of Land Management, 1980) as a reference for evaluating the landscape have certain shortcomings. One hypothesis is that visual images of the landscape which are used as a basis or standard along with landscape descriptions for measuring different levels or categories of a landscape attribute (visual standards) will produce more consistent ratings than using verbal standards. The purpose of this thesis is to examine the use of visual standards as a predictive tool to improve landscape assessment. This study involved the development of visual standards and a comparative survey study. One group of survey respondents was asked to rate or evaluate selected landscape variables (complexity and vividness) for a set of 15 landscape scenes. Another group used more traditional verbal standards to evaluate the same variables for the same landscape scenes. The effects of visual standards was compared with the effect of verbal standards on (1) assessing the landscape; (2) people’s attitudes toward landscape ratings; and (3) people’s attitudes toward the rating process. The findings indicate that using visual standards cannot produce more consistent results for rating landscape variables. Further research needs to be conducted for excluding the external variables which may affect the quality of visual standards. In fact, there is evidence to suggest that visual standards are perceived by the user as a more accurate reference. The findings also indicate that using visual standards result in a broader use of the rating scale particularly at the lower end of the scale and cause lower rating results for the tested scenes compared to verbal standards. Although using visual standards to access complexity and vividness cannot improve their predictive relationship to preference, the past research indicating a strong relationship between landscape complexity and visual quality may be influenced or biased by people’s preference for the landscape. In terms of the use of image based visual standards in computer application, this limited research has been unable to find any clear advantages in terms or reliability or validity. However, visual standards do not appear to be any less reliable and valid than verbal standards.