We investigated the effects of different photoperiods on the expression level of GUS genes regulated by the CaMV-35S promoter in leaf lettuce (Lactuca sativa L. cv. ‘Greenwave’) for a recombinant protein production system. A leaf disk experiment and a cultivation experiment were conducted in different photoperiods. A linear relationship (R²=0.9934) was observed between the lengths of photoperiods and GUS activities per unit fresh weight in the leaf disk experiment. This result indicates that the expression of the CaMV-35S promoter during a photoperiod was much more enhanced than that during a dark period. In the cultivation experiment, a longer photoperiod helped not only to enhance the growth of a lettuce plant but also to increase its GUS activity. As a result, GUS activity per plant under the 24:0 h photoperiod was significantly (P‹0.05) higher than that under the 16:8 and 8:16 h photoperiods. However, the question remains whether these results for GUS-CaMV-35S promoter can be applied to other recombinant proteins or promoters. Further studies are thus required to establish a practical strategy for designing an efficient recombinant production system in a plant factory.

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The possibility of reusing water treatment residue (WTR) was examined as an alternative material for sand that is now widely used as a growing medium. Physical properties such as water retention curve, relative gas diffusivity (D/D₀), saturated hydraulic conductivity, porosity, available water-holding capacity and bulk density were compared between WTR and sand. D/D₀, water retention capacity, total available water-holding capacity, total and capillary porosities, and bulk density were higher for WTR than for sand. This is attributed to creation of intra- and inter-aggregate pores through binding of silt and clay particles in the flocculation process of aggregates in the WTR. These physical characteristics of the WTR endorse a high possibility of reusing the WTR as an alternative for sand as a growing medium.

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Genetically modified (GM) rice varieties that store up pharmaceutical proteins in seeds have recently been developed. Since the pharmaceutical protein-encoding genes of these varieties are connected with the promoter of seed storage protein-encoding genes, the pharmaceutical protein content increases as the seed protein content increases. Rice varieties were grown in hydroponic culture at different nutrient solution concentrations at the heading time in a controlled environment. Emergence of non-productive stems was inhibited through an early reduction in the nutrient solution concentration due to accelerated translocation from the leaf blade, leaf sheath, and stem to the seed. Further, the seed storage protein composition was altered by regulating the concentration of the nutrient solution. When the nutrient solution concentration was increased just before heading occurred, translocation to the seeds as well as the generation of non-productive stems decreased. The total protein concentration of rice seeds was not increased by the treatments of nutrient solution concentration, however, it was greater in the plants grown in the present study than in plants grown in field cultivation. Seeds in which high concentrations of total protein and seed storage protein accumulate can be produced when the nutritional content is kept constant in hydroponic culture.

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The Closed Geosphere Experiment Facility (CGEF), which is highly airtight, is designed to facilitate the investigation of carbon cycles of terrestrial ecosystems. The Geosphere Module has 5.8 m×8.7 m ground area and 11.9 m average height, including 3.1 m soil depth. A wetland ecosystem, with Phragmites australis-dominated vegetation, is scheduled to be introduced into the Geosphere Module. This study characterizes the distribution and variation of the environmental factors of the Geosphere Module (air temperature, light intensity, and air CO₂ concentration) that influence the carbon cycles of ecosystems before introducing the wetland ecosystem into the Module. The CGEF can control the average air temperature within 1°C of a set value. The Geosphere Module has heterogeneous light intensity, which decreases from south to north ranged from 54% to 79%. However, the heterogeneity of light conditions caused no serious problem for the growth of P. australis as shown by a pot test over two years. The CO₂ separation capacity was sufficient for driving carbon circulation in the Geosphere Module under a condition of maximum CO₂ flux from ecosystem respiration of P. australis-dominated vegetation including soils during the night. The initial performance tests showed that CGEF can serve as an experimental means for analyzing ecosystem processes on carbon cycles under controlled conditions.

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