Ultrastructure of poplar cortical cells during the transition from growing to wintering stages and vice versa

Summary Electron microscopic studies revealed that major cytological changes in the cortical cells of poplar (Populus euramericana cv. gelrica) began to occur in early September in conjunction with the metabolic transition from the growing to the wintering stage. During this transition, the cells became temporarily rich in endoplasmic reticulum, polysomes and vesicles. As the conspicuous formation of organelles progressed, the large vacuoles became smaller and filled with osmiophilic materials. Undefined organelles (protein-lipid bodies) also increased in number. From late October until March, organelles involved in protein synthesis were sparsely distributed in the cells, indicating that the number of these organelles is probably linked to the seasonal cycle of protein synthesis. In early February, after release from dormancy, fusion of vacuoles proceeded in the cells. The inclusion of organelles and a gradual decrease in the amount of osmiophilic materials in the vacuoles occurred at this stage. Subsequently, the structure of the cells continued to undergo changes to accommodate growth, which occurred in early May.     

The general occurrence of “plastid initials” and their development into plastids in cortical cells of woody plants in winter

Summary Electron microscopic studies revealed that plastid initials, presumed precursors of plastids, occur in cortical cells of the following plants studied in February and March: Betula ermanii Cham.; Prunus sargentii Rhed.; Pyrus communis L.; Ribes sinanense F. Maekawa; Salix matsudana Koidz. forma tortuosa Rhed.; and Sambucus sieboldiana var. miquelii Hara. Since plastid initials were found previously in Malus pumila Mill., Morus bombycis Koidz. and Populus euramericana cv. gelrica (Sagisaka 1991), plastid initials have been found in all woody plants examined to date. In P. euramericana cv. gelrica, at later stages of the development of the initials in March, the conglomerates of plastid initials became heterogeneous in terms of size, extent of thylakoid formation and ability to form starch granules. The formation of prolamellar structures was frequently observed in cells of Magnolia kobus var. borealis Sarg., which was sampled on April 19. These observations suggest the course of events in the development of the plastid initial and the continuity of the life of amyloplasts over a year in the life of woody plants.     

A cold environment is a prerequisite for formation of "plastid initials" in winter buds of poplar

The “plastid initial,” the presumed precursor of eoplasts and proplastids, is present in the cells of the apical meristem of winter buds of poplar (Populus euramericana). The formation of the plastid initial in the cells of winter buds is initiated soon after the breaking of the innate or resting stage of dormancy, even in winter under nongrowing conditions in mid-January or early February. From this stage to March, the conglomeration of the plastid initial and the formation of prolamellar bodies is evident. In contrast to the poplar samples kept outdoors, the cells of the apical meristem of the indoor winter buds did not show any indication of the formation of the plastid initial and the buds of the latter sample did not flush even at the end of May. These results suggest that the sequence of reactions involved in the onset of regrowth may be closely related to the formation of the plastid initial.     

Occurrence of nicotinamide adenine dinucleotide phosphatelinked glyoxylate reductase in nonphotosynthetic xylem tissue of perennials

Xylem extracts of poplar tree contained glyoxylate reductase specific for NADPH. By isoelectric focusing in the pH ranges 3.5 to 10 or 4 to 6, the enzyme exhibited a single peak of activity at pH 5.4. The enzyme showed essentially no activity toward hydroxypyruvate, pyruvate, or NADH. The reaction was optimal at pH 6.0 in phosphate buffer and the activity profile exhibited a sharp and narrow pH profile with half-maximal velocities at about pH 7.0. The K_m of the enzyme for glyoxylate was 0.11 millimolar. The xylem tissue of poplar tree exhibited high levels of enzyme activity (30 micromoles per gram dry weight per hour) even in the wintering stage and a slight change in activity occurred in spring and fall at the time when metabolism transition occurs.     

Efficient screening of predictive biomarkers for individual treatment selection

The development of molecular diagnostic tools to achieve individualized medicine requires identifying predictive biomarkers associated with subgroups of individuals who might receive beneficial or harmful effects from different available treatments. However, due to the large number of candidate biomarkers in the large‐scale genetic and molecular studies, and complex relationships among clinical outcome, biomarkers, and treatments, the ordinary statistical tests for the interactions between treatments and covariates have difficulties from their limited statistical powers. In this paper, we propose an efficient method for detecting predictive biomarkers. We employ weighted loss functions of Chen et al. to directly estimate individual treatment scores and propose synthetic posterior inference for effect sizes of biomarkers. We develop an empirical Bayes approach, namely, we estimate unknown hyperparameters in the prior distribution based on data. We then provide efficient screening methods for the candidate biomarkers via optimal discovery procedure with adequate control of false discovery rate. The proposed method is demonstrated in simulation studies and an application to a breast cancer clinical study in which the proposed method was shown to detect the much larger numbers of significant biomarkers than existing standard methods.     

Life cycle inventory analysis of co<Subscript>2</Subscript> emissions manufacturing commodity plastics in japan

The goal of this study was to calculate the average CO₂ emissions for manufacturing three commodity plastics, polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) in Japan. The CO₂ emissions were calculated from cradle to gate, excluding the calcination processes after use. As the results, the followings were observed: 1) The gross CO₂ emissions for the manufacture of plastics in Japan were 1.3, 1.4, and 1.7 kg-CO₂/kg-PE, PP, and PVC, respectively. These mainly reflected the difference of CO₂ emissions for the in-house electricity generation. 2) The CO₂ emissions for the electricity used for manufacturing PVC were higher than that used for PE and PP, because additional electricity was required for the electrolysis to produce chlorine. The gross electricity consumption for manufacturing PVC was 1.3 kWh/kg-PVC, and the other plastics consumed 0.5 kWh/kg-Products. In addition, the effects of energy saving were studied using a projected gas-diffusion electrode for the electrolysis of salt on the reduction of CO₂ emissions. It was estimated that the reduction in CO₂ emissions was 7% compared with the present PVC manufacturing processes.     

BmEts upregulates promoter activity of lebocin in Bombyx mori

The Ets family protein BmEts is assumed to be implicated in determination of diapause in the embryogenesis of Bombyx mori. In this study, we found that expression of BmEts was increased in the fat body and other tissues of the 5th instar larvae in response to Escherichia coli injection. Cotransfection experiments using a silkworm cell line revealed that overexpression of BmEts significantly elevated the activity of lebocin promoter but not of cecropin B1, cecropin D, attacin, and moricin promoters. Activation of the lebocin promoter by BmEts was dependent on at least two κB elements and the most proximal GGAA/T motif located on the 5'-upstream region. BmEts further synergistically enhanced E. coli or BmRelish1-d2 (active form)-stimulated lebocin promoter activation. Two κB elements were also found to be involved in promoter activation by BmRelish1-d2 and in synergistic promoter activation by BmEts and BmRelish1-d2 in the silkworm cells. Specific binding of recombinant BmEts to the proximal κB element and the most proximal GGAA/T motif and interaction between BmEts and BmRelish1 were also observed. To our knowledge, this is the first report of an Ets family protein directly regulating immune-related genes in invertebrates.     

Amino Acid Pools in Herbaceous Plants at the Wintering Stage and at the Beginning of Growth

Free amino acids in 40 herbaceous perennial plants were analyzedunder natural conditions. From the major amino acid contentat the wintering stage, the pools were separated into the followingfive types: 1) a group which accumulated arginine (20 plantsout of 40); 2) a group which accumulated arginine and proline(9 plants); 3) a group which accumulated glutamate and glutamine(3 plants); 4) a group which accumulated asparagine (4 plants);and 5) a group which accumulated proline (4 plants). Changesin the amino acid pools in the plants occurred under snow duringwintering for about five months. Particularly, asparagine wasno longer the major amino acid in the group which had accumulatedit in fall. There was a tendency for the glutamine content toincrease, suggesting that NH₃ is utilized for the synthesisof the amide. Also, the relative concentrations of almost allthe free amino acids increased several-fold, which was indicativeof the occurrence of biosynthetic processes of general aminoacids during wintering. As the mobile fractions of stored nitrogen,the amino acids appeared to contribute to the initial stageof rapid growth in early spring. (Received August 4, 1986; Accepted November 17, 1986)     

Effect of low temperature on amino Acid metabolism in wintering poplar: arginine-glutamine relationships

Analyses of free amino acids in poplar (Populus gelrica) were carried out throughout a year to see the effect of low temperature on a system regulating amino acid metabolism in the tree. The results indicated that during the wintering phase arginine was the major amino acid both in bark and xylem, particularly in xylem, and that at the time of budding and growing glutamine and glutamate became dominant. Changes in the relative levels of glutamine (plus glutamate) and arginine to the total amino acids of the α-ketoglutarate family indicated the presence of a regulatory system annually controlling the synthesis between glutamine (plus glutamate) and arginine. The system appeared to be governed and sensitized by low temperatures. Neither a transition of the synthesis from arginine to glutamine (plus glutamate) nor budding occurred in the poplars which spent the winter months in a greenhouse.     

Injuries of Cold Acclimatized Poplar Twigs Resulting from Enzyme Inactivation and Substrate Depression during Frozen Storage at Ambient Temperatures for a Long Period

Wintering twigs of poplar could be stored in frozen state forabout one year, but longer storage resulted in metabolic dysfunctionand death of the twigs. Analyses of enzyme activities revealedthat most of the activity of glucose-6-phosphate and 6-phosphogluconatedehydrogenases and glutathione reductase present normally inthe twigs disappeared. Another four enzyme activities assayedalso decreased to some extent. In the twigs, glucose 6-phosphatedecreased to a level of 10^–5 M and glutathione was presenttotally in the disulfide form. The extent of the decrease ofascorbate and ATP was considerably less than that of the abovetwo. Peroxide levels rose slightly, but lipid hydroperoxidelevels rose several fold. It is suggested that the reactions catalyzed by glucose-6-phosphatedehydrogenase and related ones are obligatory to the cells evenin the frozen state and that the activity to supply glucose6-phosphate, hence NADPH, is limited to a certain period oftime. Beyond this capacity, a decrease in the ability to removeperoxide may also occur, due to a shortage of NADPH supply,resulting in inactivation of some enzymes and the formationof lipid hydroperoxide in cellular membranes. (Received April 26, 1985; Accepted June 20, 1985)