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PubMed · 9235119

Tree-structured logistic models for over-dispersed binomial data with application to modeling developmental effects.

H Ahn·J J Chen
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Abstract

This article proposes tree-structured logistic regression modeling for over-dispersed binomial data. Recursive partitioning is performed using a combination of statistical tests and residual analysis. The splitting criterion in cross-validation is based on the deviance function. A nested grid algorithm to estimate the bootstrap parameters is developed. The regression tree procedure provides a new approach for exploring in detail the relationship between the binomial response and explanatory variables. The proposed procedure is used to model the relationship between the incidence of malformation and dose and fetal weight using data from a developmental experiment conducted at the National Center for Toxicological Research. A conditional Gaussian chain model is used to account for the effect of fetal weight by dose.

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2,4,5-Trichlorophenoxyacetic AcidAbnormalities, Drug-InducedAnimalsBiometryBody WeightCleft PalateComputer SimulationData Interpretation, StatisticalDose-Response Relationship, DrugFemaleFetusHerbicidesLogistic ModelsMiceMice, Inbred AMice, Inbred BALB CMice, Inbred C3HMice, Inbred C57BLModels, BiologicalMonte Carlo MethodPregnancyJournal ArticleResearch Support, U.S. Gov't, P.H.S.

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H Ahn, J J Chen. 1997. Tree-structured logistic models for over-dispersed binomial data with application to modeling developmental effects.. https://pubmed.ncbi.nlm.nih.gov/9235119/

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PubMed2006

2,4,5-Trichlorophenoxyacetic acid promotes somatic embryogenesis in the rose cultivar "Livin' Easy" (Rosa sp.).

Somatic embryogenesis (SE) offers vast potential for the clonal propagation of high-value roses. However, some recalcitrant cultivars unresponsive to commonly employed SE-inducing agents and low induction rates currently hinder the commercialization of SE technology in rose. Rose SE technology requires improvement before it can be implemented as a production system on a commercial scale. In the present work, we assessed 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a synthetic auxin not previously tested in rose, for its effectiveness to induce SE in the rose cultivar "Livin' Easy" (Rosa sp.). We ran a parallel comparison to the commonly used 2,4-dichlorophenoxyacetic acid (2,4-D). We tested each auxin with two different basal media: Murashige and Skoog (MS) basal medium and woody plant medium (WPM). MS medium resulted in somatic embryo production, whereas WPM did not. 2,4,5-T induced SE over a greater concentration range than 2,4-D's and resulted in significantly greater embryo yields. 2,4,5-T at a concentration of 10 or 25 microM was better for embrygenic tissue initiation than 2,4,5-T at 5 microM. Further embryo development occurred when the tissue was transferred to plant growth regulator (PGR) free medium or media with 40% the original auxin concentration. However, the PGR-free medium resulted in a high percentage of abnormal embryos (32.31%) compared to the media containing auxins. Upon transfer to germination medium, somatic embryos successfully converted into plantlets at rates ranging from 33.3 to 95.2%, depending on treatment. Survival rates 3 months ex vitro averaged 14.0 and 55.6% for 2,4-D- and 2,4,5-T-derived plantlets, respectively. Recurrent SE was observed in 60.2% of the plantlets growing on germination medium. This study is the first report of SE in the commercially valuable rose cultivar 'Livin' Easy' (Rosa sp.) and a suitable methodology was developed for SE of this rose cultivar.

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