Journal Highlights

Mineral Nutrition and In Vitro Growth of Gerbera hybrida (Asteraceae)

The majority of studies on gerbera daisy in vitro growth have examined the effects of plant growth regulators on shoot culture initiation, proliferation, and rooting, with considerably less research on the effects of mineral nutrients. Mineral nutrient experiments, in general, typically compare the effects of various basal media formulations on in vitro growth rather than the effects of specific salts or ions. Testing “classic” formulations can be useful for identifying formulations that result in improved growth, but provides no information on the quantitative relationship between mineral nutrients and various in vitro responses. We examined the effects of groups of salts, individual salts, and individual ions on in vitro growth. The first experiment varied groups of salts and was designed to identify nutrient groups that had large effects. We viewed this type of an experiment as a crude screening to detect effects that could be explored in detail with follow-up experimentation. The results of this first experiment revealed that the responses were affected differently by the different nutrients. This was not surprising and led us to design three follow-up experiments to determine the effects of 1) individual micronutrient salts, 2) the primary bulk solution ions NH₄⁺, NO₃^–, and K⁺, and 2) Fe and Fe chelation. The NH₄⁺/NO₃^–/K⁺ ion experiment is one of only a few examples in the literature of an experimental design that can determine ion-specific effects without the problem of ion confounding. Ion confounding occurs when a salt-based design is used to determine ion-specific effects. Because the concentration of the ion of interest is not varied independently of its co-ion counterpart in the salt, the main effect of that ion is indistinguishable from, or confounded with, its co-ion. Ion confounding is near universal in the literature. We utilized the inherent geometric aspects of experimental design to define the effects of various mineral nutrients on in vitro growth. The design spaces defined, though applied to Gerbera, would be useful with other plant species. As other plant species are “mapped” in these design spaces, higher order relationships of how various plant types respond would certainly emerge. Further, quantifying mineral nutrient effects in this manner compliments the advances in genomics, proteomics, and metabolomics. Relevant regions would be identified for further exploration by these technologies to understand the underlying biological mechanisms. Lastly, the practical consequence of exploring these design spaces in a systematic manner is the identification of formulations and conditions that result in improved growth and higher quality.

Randall P. Niedz, Scott E. Hyndman, Terrence J. Evens, Albert A. Weathersbee III. Mineral nutrition and in vitro growth of Gerbera hybrida (Asteraceae). In Vitro Cellular & Developmental Biology-Plant 50:458-470, 2014.

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Overexpression of Cyclin Dependent Kinase Inhibitor P27/Kip1 Increases Oligodendrocyte Differentiation from Induced Pluripotent Stem Cells

Cell transplantation with oligodendrocyte precursor cells (OPCs) is a promising and effective treatment for the diseases associated with demyelination in the central nervous system. In vitro directed differentiation of OPCs from induced pluripotent stem cells (iPSCs) is expected to provide a new source of graft for this therapy. However, the efficiency of in vitro differentiation into oligodendrocytes was lower for OPCs derived from mouse iPSCs than that for OPCs derived from mouse embryonic stem cells (ESCs). We found that the expression level of cyclin dependent kinase inhibitor P27/Kip1 protein in mouse iPSC-derived OPCs was lower than that of mouse ESC-derived OPCs. During the animal development, P27/Kip1 protein contributes cell proliferation and differentiation in many tissues. And P27/Kip1 protein is a component of the cell-intrinsic biological timer for oligodendrocyte development in the rodent optic nerve. During the development of the rodent optic nerve, P27/Kip1 protein accumulates in OPCs in a time-dependent manner. We attempted to compensate for the expression changes in P27/Kip1 protein in mouse iPSC-derived cells through retrovirus vector-mediated gene expression. The over expression of P27/Kip1 protein enhanced the efficiency of oligodendrocyte differentiation from iPSC-derived OPCs over eight fold in vitro.

Shinpei Tamaki, Yasuhito Tokumoto. Overexpression of cyclin dependent kinase inhibitor p27/Kip1 increases oligodendrocyte differentiation from induced pluripotent stem cells. In Vitro Cellular & Developmental Biology-Animal 50:778-785, 2014.

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