Replacement of proteasome subunits X and Y by LMP7 and LMP2 induced by interferon-γ for acquirement of the functional diversity responsible for antigen processing

AbstractProteasomes catalyze the non-lysosomal, ATP-dependent selective breakdown of ubiquitinated proteins and are thought to be responsible for MHC class I-restricted antigen presentation. Recently, we reported that gamma interferon (IFN-γ) induced not only marked synthesis of the MHC-encoded proteasome subunits LMP2 and LMP7, but also almost complete loss of two unidentified proteasome subunits tentatively designated as X and Y in various human cells. Here, we show that subunit X is a new proteasomal subunit highly homologous to LMP7, and that subunit Y is identical to the LMP2-related proteasomal subunit delta. Thus, IFN-γ appears to induce subunit replacements of X and Y by LMP7 and LMP2, respectively, producing 'immuno-proteasomes' with the functional diversity responsible for processing of endogenous antigens

Response of a Wild Edible Plant to Human Disturbance: Harvesting Can Enhance the Subsequent Yield of Bamboo Shoots

Wild edible plants, ecological foodstuffs obtained from forest ecosystems, grow in natural fields, and their productivity depends on their response to harvesting by humans. Addressing exactly how wild edible plants respond to harvesting is critical because this knowledge will provide insights into how to obtain effective and sustainable ecosystem services from these plants. We focused on bamboo shoots of Sasa kurilensis, a popular wild edible plant in Japan. We examined the effects of harvesting on bamboo shoot productivity by conducting an experimental manipulation of bamboo shoot harvesting. Twenty experimental plots were prepared in the Teshio Experimental Forest of Hokkaido University and were assigned into two groups: a harvest treatment, in which newly emerged edible bamboo shoots were harvested (n = 10); and a control treatment, in which bamboo shoots were maintained without harvesting (n = 10). In the first year of harvesting (2013), bamboo shoot productivities were examined twice; i.e., the productivity one day after harvesting and the subsequent post-harvest productivity (2-46 days after harvesting), and we observed no difference in productivity between treatments. This means that there was no difference in original bamboo shoot productivity between treatments, and that harvesting did not influence productivity in the initial year. In contrast, in the following year (2014), the number of bamboo shoots in the harvested plots was 2.4-fold greater than in the control plots. These results indicate that over-compensatory growth occurred in the harvested plots in the year following harvesting. Whereas previous research has emphasized the negative impact of harvesting, this study provides the first experimental evidence that harvesting can enhance the productivity of a wild edible plant. This suggests that exploiting compensatory growth, which really amounts to less of a decline in productivity, may be s a key for the effective use of wild edible plants

Response of a Wild Edible Plant to Human Disturbance: Harvesting Can Enhance the Subsequent Yield of Bamboo Shoots.

Wild edible plants, ecological foodstuffs obtained from forest ecosystems, grow in natural fields, and their productivity depends on their response to harvesting by humans. Addressing exactly how wild edible plants respond to harvesting is critical because this knowledge will provide insights into how to obtain effective and sustainable ecosystem services from these plants. We focused on bamboo shoots of Sasa kurilensis, a popular wild edible plant in Japan. We examined the effects of harvesting on bamboo shoot productivity by conducting an experimental manipulation of bamboo shoot harvesting. Twenty experimental plots were prepared in the Teshio Experimental Forest of Hokkaido University and were assigned into two groups: a harvest treatment, in which newly emerged edible bamboo shoots were harvested (n = 1 O); and a control treatment, in which bamboo shoots were maintained without harvesting (n = 10). In the first year of harvesting (2013), bamboo shoot productivities were examined twice; i.e., the productivity one day after harvesting and the subsequent post-harvest productivity (2-46 days after harvesting), and we observed no difference in productivity between treatments. This means that there was no difference in original bamboo shoot productivity between treatments, and that harvesting did not influence productivity in the initial year. In contrast, in the following year (2014), the number of bamboo shoots in the harvested plots was 2.4-fold greater than in the control plots. These results indicate that over-compensatory growth occurred in the harvested plots in the year following harvesting. Whereas previous research has emphasized the negative impact of harvesting, this study provides the first experimental evidence that harvesting can enhance the productivity of a wild edible plant. This suggests that exploiting compensatory growth, which really amounts to less of a decline in productivity, may bes a key for the effective use of wild edible plants

Productivity of bamboo shoots in the year following harvesting (2014).

<p>(a) Numbers of bamboo shoots produced. Bars: SE values. (b) Relationship of produced bamboo shoots between the year of harvesting (2013) and the next year (2014). Red circles: harvest. Blue circles: control. Solid and dashed lines indicate the linear regression of the harvest and control treatment, respectively.</p

Change bamboo grass density after harvesting.

<p>Red circles: harvest treatment. Blue circles: control treatment. Solid and dashed lines indicate the linear regression of the harvest and control treatment, respectively. Dotted line denotes no change in bamboo grass density between 2013 and 2014.</p

Productivity of bamboo shoots in the year of harvesting.

<p>(a) Numbers of produced bamboo shoots one day after harvesting (on June 11th, 2013) and 2–46 days after harvesting (from June 12th to July 26th 2013). Red circles: harvest. Blue circles: control. (b) Total number of bamboo shoots produced in 2013. Bars: SE values.</p

Initial status of bamboo grass in the year the experiment was started (2013).

<p>(a) Relationship between the density of the matured bamboo grass and the bamboo shoot productivity. Red circles: harvest. Blue circles: control. Solid line indicates the linear regression between the density of matured bamboo grass and bamboo shoots. (b) Density of matured bamboo grass. Bars: SE values.</p