The well-characterized secretory glycoprotein, rice (Oryza sativa) a-amylase isoform I-1 (AmyI-1), was localized within the plastids and proved to be involved in the degradation of starch granules in the organelles of rice cells. In addition, a large portion of transiently expressed AmyI-1 fused to green fluorescent protein (AmyI-1-GFP) colocalized with a simultaneously expressed fluorescent plastid marker in onion (Allium cepa) epidermal cells. The plastid targeting of AmyI-1 was inhibited by both dominant-negative and constitutively active mutants of Arabidopsis thaliana ARF1 and Arabidopsis SAR1, which arrest endoplasmic reticulum-to-Golgi traffic. In cells expressing fluorescent trans-Golgi and plastid markers, these fluorescent markers frequently colocalized when coexpressed with AmyI-1. Three-dimensional time-lapse imaging and electron microscopy of high-pressure frozen/freeze-substituted cells demonstrated that contact of the Golgi-derived membrane vesicles with cargo and subsequent absorption into plastids occur within the cells. The transient expression of a series of C-terminal-truncated AmyI-1-GFP fusion proteins in the onion cell system showed that the region from Trp-301 to Gln-369 is necessary for plastid targeting of AmyI-1. Furthermore, the results obtained by site-directed mutations of Trp-302 and Gly-354, located on the surface and on opposite sides of the AmyI-1 protein, suggest that multiple surface regions are necessary for plastid targeting. Thus, Golgi-to-plastid traffic appears to be involved in the transport of glycoproteins to plastids and plastid targeting seems to be accomplished in a sorting signal-dependent manner. INTRODUCTIONCereal a-amylases (EC 3.2.1.1) are typical secretory proteins found in many plants. In germinating cereal seeds, these enzyme molecules are biosynthesized and secreted from the secretory tissues, the scutellar epithelium and the aleurone, to the starchy endosperm, which has undergone programmed cell death. Numerous a-amylase isoforms have been identified in cereals, but the predominant a-amylase isoform I-1 (AmyI-1) in rice (Oryza sativa) is a unique glycoprotein that bears N-linked oligosaccharide side chains (Hayashi et al., 1990;Terashima et al., 1994). The biosynthesis and secretion of AmyI-1 have been extensively investigated: mRNA translation on endoplasmic reticulum (ER) membrane-bound ribosomes, signal sequence-dependent translocation of the ER, core glycosylation in the ER lumen, vesicular transport to the Golgi apparatus, oligosaccharide modification to the complex type, and exocytosis all proceed according to the canonical secretory mechanism (Palade, 1975;Blobel, 1980;Kornfeld and Kornfeld, 1985).Protein targeting into plastids is an essential cellular event for maintaining plant function and plant life. Plastids, including chloroplasts in green leaves and amyloplasts in starchy cells, contain the genetic machinery required to synthesize their own proteins, although most plastidial proteins are encoded in the nuclear DNA. Nuclear-encoded plastidial...

Dexmedetomidine exhibited a cardioprotective effect on global ischaemia in the isolated rat heart model, which was mediated by alpha-2 adrenergic stimulation.

Irruptions of ungulate populations have been observed, but little is known of their cause of initiation and termination. We documented an irruption of a naturally colonizing sika deer (Cervus nippon) population on Cape Shiretoko, Shiretoko Peninsula, northeastern Hokkaido, Japan, and we examined limiting factors on population growth. The population increased from 54 deer in 1986 to 592 deer in 1998 (11 to 118 deer/km2, respectively) and declined to 177 (35 deer/km2) the following winter of 1999. The intrinsic rate of increase from 1986 to 1998 was 0.19 (95% CI: 0.16 to 0.22). We estimated an annual survival for adult females of 0.92. The ratio of calves to adult females was 76%. We observed a density‐correlated reduction in winter food resources. Density‐dependent food resources and their interaction with climatic factors were the most important limiting factors for sika deer. The population recovered rapidly following the population crash in 1999 and increased to 512 deer (102 deer/km2) in 2002. We anticipate further increase and a second crash. To confirm whether the population will be regulated naturally and to establish sika deer management policy in Shiretoko National Park, long‐term monitoring of the relationship between sika deer and their habitat must be implemented.

A total of 32 wild Hokkaido sika deer ( Cervus nippon yesoensis ) were shot (13 in summer, nine in autumn and 10 in winter) in the Syari district, Shiretoko Peninsula of Hokkaido Island, Japan. The ingested foods, rumen fermentation parameters and microbes were determined to evaluate digestive strategy and food availability in each season. Ingested foods and ruminal characteristics greatly varied by season. Rumen digesta mainly comprised of graminoids in summer, graminoids and agricultural products in autumn, and bark and twigs in winter. Rumen pH showed seasonal differences ( P < 0.05) and was lowest in summer, highest in winter, and intermediate in autumn, reflecting the seasonal differences in ruminal concentration of total volatile fatty acids which were significantly lower ( P < 0.05) in winter than in summer and autumn. Acetate proportions were significantly higher in winter than in other seasons ( P < 0.05), while the opposite trend was seen in proportions of propionate and butyrate. Rumen ammonia levels showed significant seasonal differences ( P < 0.05), decreasing from summer to autumn to winter. Rumen protozoa levels in autumn and winter decreased to 28 and 10% of the levels observed in summer, respectively ( P < 0.05 for both). The rumen bacteria level in winter was lower ( P < 0.05) than that in autumn, but no difference was seen for the other seasonal comparisons. Gram negative cocci were present in significantly higher proportions in winter than in other seasons ( P < 0.05), while Gram negative curved rods were less frequently observed in winter ( P < 0.05). Based on these results, wild sika deer in this area are shown to survive with rumen microbial populations altered with the dietary conditions that vary greatly by season.

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