We have taken advantage of an acclimation phenomenon in a chilling-sensitive maize inbred to investigate the molecular, biochemical, and physiological responses to chilling in preemergent maize seedlings. Three-day-old seedlings were exposed to 4[deg]C for 7 days and did not survive chilling stress unless they were preexposed to 14[deg]C for 3 days. cDNAs representing three chilling acclimation-responsive (CAR) genes were isolated by subtraction hybridization and differential screening and found to be differentially expressed during acclimation. Identification of one of these CAR genes as cat3, which encodes the mitochondrial catalase3 isozyme, led us to hypothesize that chilling imposes oxidative stress in the seedlings. Hydrogen peroxide levels were elevated during both acclimation and chilling of nonacclimated seedlings. Further molecular and biochemical analyses indicated that whereas superoxide dismutase activity was not affected, the levels of cat3 transcripts and the activities of catalase3 and guaiacol peroxidase were elevated in mesocotyls during acclimation. Accumulation of H2O2 following a short treatment with aminotriazole, a catalase inhibitor, indicated that catalase3 seems to be an important H2O2-scavenging enzyme in the seedlings. Control 3-day-old seedlings pretreated with H2O2 or menadione, a superoxide-generating compound, at 27[deg]C induced chilling tolerance. Both of these chemical treatments also increased cat3 transcripts and catalase3 and guaiacol peroxidase activities. We suggest that peroxide has dual effects at low temperatures. During acclimation, its early accumulation signals the production of antioxidant enzymes such as catalase3 and guaiacol peroxidase. At 4[deg]C, in nonacclimated seedlings, it accumulates to damaging levels in the tissues due to low levels of these, and perhaps other, antioxidant enzymes.

Since its inception, the concept of absorptive capacity has been closely linked with notions of organizational learning. Yet the precise nature of the relationship between these two concepts has never been established. This relationship is examined in a variety of ways, and it is suggested that the literature on these two concepts shares a conceptual affinity which needs to be delineated. It is suggested that absorptive capacity (a dynamic capability) is a concrete example of organizational learning that concerns an organization's relationship with new external knowledge. Using the 4I Model for organizational learning (Crossan, M.M., Lane, H.W. and White, R.E. (1999). An organizational learning framework: from intuition to institution. Academy of Management Review, 24, 522-537) and Zahra and George's conceptualization of absorptive capacity (Zahra, S.A. and George, G. (2002). Absorptive capacity: a review, reconceptualization, and extension. Academy of Management Review, 27, 185-203), this paper proposes an integration of the two concepts.

l h e response of antioxidants to acclimation and chilling in various tissues of dark-grown maize (Zea mays 1.) seedlings was examined in relation t o chilling tolerance and protection from chillinginduced oxidative stress. Chilling caused an accumulation of H,O, in both the coleoptile + leaf and the mesocotyl (but not roots), and acclimation prevented this accumulation. None of the antioxidant enzymes were significantly affected by acclimation or chilling i n the coleoptile + leaf or root. However, elevated levels of glutathione i n acclimated seedlings may contribute to an enhanced ability to scavenge H 2 0 2 i n the coleoptile + leaf. I n the mesocotyl (visibly most susceptible to chilling), catalase3 was elevated in acclimated seedlings and may represent the first line of defense from mitochondria-generated H,O,. Nine of the most prominent peroxidase isozymes were induced by acclimation, two of which were located in the cell wall, suggesting a role in lignification. Lignin content was elevated i n mesocotyls of acclimated seedlings, likely improving the mechanical strength of the mesocotyl. One cytosolic glutathione reductase isozyme was greatly decreased in acclimated seedlings, whereas two others were elevated, possibly resulting i n improved effectiveness of the enzyme at low temperature. When taken together, these responses to acclimation illustrate the potential ways in which chilling tolerance may be improved in preemergent maize seedlings.Stand establishment in maize (Zea mays L.) is greatly affected by exposure of seedlings to low temperature during germination and early seedling growth. Pioneer inbred G50 is particularly sensitive. By utilizing dark-grown seedlings to simulate a preemergent condition, Anderson et al. (1994) demonstrated that exposure of seedlings to a noninjuriou low temperature induced a degree of chilling tolerance, allowing them to survive subsequent exposure to more severe low temperatures. This acclimation phenomenon provided an opportunity to examine the molecular basis for the improvement in chilling tolerance. The discovery that cat3 (mitochondrial catalase) transcripts were up-regulated in response to acclimation led to inves-

U sing data from 138 independent samples, we meta-analytically examined three research questions concerning the roles of personality and network position in organizations. First, how do different personality characteristics-selfmonitoring and the Big Five personality traits-relate to indegree centrality and brokerage, the two most studied structurally advantageous positions in organizational networks? Second, how do indegree centrality and brokerage compare in explaining job performance and career success? Third, how do these personality variables and network positions relate to work outcomes? Our results show that self-monitoring predicted indegree centrality (across expressive and instrumental networks) and brokerage (in expressive networks) after controlling for the Big Five traits. Self-monitoring, therefore, was especially relevant for understanding why people differ in their acquisition of advantageous positions in social networks. But the total variance explained by personality ranged between 3% and 5%. Surprisingly, we found that indegree centrality was more strongly related to job performance and career success than brokerage. We also found that personality predicted job performance and career success above and beyond network position and that network position partially mediated the effects of certain personality variables on work outcomes. This paper provides an integrated view of how an individual's personality and network position combine to influence job performance and career success.

A central topic in leadership research concerns the impact of leadership style -the pattern of attitudes that leaders hold and behaviors they exhibit. Since the year 2000, several new leadership styles have been proposed to capture important missing aspects beyond the dominant charismatic/transformational and transactional framework. The authors review the emerging literature on these new styles -ideological leadership, pragmatic leadership, authentic leadership, ethical leadership, spiritual leadership, distributed leadership, and integrative public leadership -as well as the recent work on servant leadership. They also comment on the Ohio State studies on leadership, and then discuss the ways in which these many styles overlap with transformational leadership and each other, and issue a call to leadership researchers to collectively develop a new 'full-range' model of leadership that encompasses and distills what is unique about these various styles. The authors argue that such an integrated full-range model is necessary for research on leadership style to progress.

Acetyl-coenzyme A (CoA) is used in the cytosol of plant cells for the synthesis of a diverse set of phytochemicals including waxes, isoprenoids, stilbenes, and flavonoids. The source of cytosolic acetyl-CoA is unclear. We identified two Arabidopsis cDNAs that encode proteins similar to the amino and carboxy portions of human ATP-citrate lyase (ACL). Coexpression of these cDNAs in yeast (Saccharomyces cerevisiae) confers ACL activity, indicating that both the Arabidopsis genes are required for ACL activity. Arabidopsis ACL is a heteromeric enzyme composed of two distinct subunits, ACLA (45 kD) and ACLB (65 kD). The holoprotein has a molecular mass of 500 kD, which corresponds to a heterooctomer with an A 4 B 4 configuration. ACL activity and the ACLA and ACLB polypeptides are located in the cytosol, consistent with the lack of targeting peptides in the ACLA and ACLB sequences. In the Arabidopsis genome, three genes encode for the ACLA subunit (ACLA-1, At1g10670; ACLA-2, At1g60810; and ACLA-3, At1g09430), and two genes encode the ACLB subunit (ACLB-1, At3g06650 and ACLB-2, At5g49460). The ACLA and ACLB mRNAs accumulate in coordinated spatial and temporal patterns during plant development. This complex accumulation pattern is consistent with the predicted physiological needs for cytosolic acetyl-CoA, and is closely coordinated with the accumulation pattern of cytosolic acetyl-CoA carboxylase, an enzyme using cytosolic acetyl-CoA as a substrate. Taken together, these results indicate that ACL, encoded by the ACLA and ACLB genes of Arabidopsis, generates cytosolic acetyl-CoA. The heteromeric organization of this enzyme is common to green plants (including Chlorophyceae, Marchantimorpha, Bryopsida, Pinaceae, monocotyledons, and eudicots), species of fungi, Glaucophytes, Chlamydomonas, and prokaryotes. In contrast, all known animal ACL enzymes have a homomeric structure, indicating that a evolutionary fusion of the ACLA and ACLB genes probably occurred early in the evolutionary history of this kingdom.Acetyl-coenzyme A (CoA) is an intermediate metabolite that is juxtaposed between catabolic and anabolic processes. As the entry point for the tricarboxylic acid (TCA) cycle, acetyl-CoA can be considered the gateway in the oxidation of carbon derived from the catabolism of fatty acids, certain amino acids (e.g. Leu, Ile, Lys, and Trp), and carbohydrates. Furthermore, acetyl-CoA is the intermediate precursor for the biosynthesis of a wide variety of phytochemicals. Because membranes are impermeable to CoA derivatives, it can be inferred that acetyl-CoA is generated in at least four distinct metabolic pools representing the four subcellular compartments where acetyl-CoA metabolism occurs: plastids, mitochondria, peroxisomes, and the cytosol (Fig. 1). Therefore, plants should have distinct acetyl-CoA-generating systems in mitochondria (for the TCA cycle), in plastids (for de novo fatty acid biosynthesis), in peroxisomes (the product of ␤-oxidation of fatty acids), and in the cytosol (for the biosynthesis of isoprenoids, flavo...

SummaryInformation gathering is central to a variety of organizational behavior theories, but researchers have suggested that our understanding of the actual information gathering behaviors of managers is underdeveloped. Social network characteristics are theorized to be a key determinant of information gathering behaviors, but social network research has been criticized for: (1) not measuring the intervening mechanisms by which network characteristics are theorized to have their effects and (2) not considering how actors' motivation affects what network benefits are realized. This article addresses these concerns through an empirical study of the actual information gathering behaviors of managers. It posits that individual differences in a personality variable called need for cognition capture differences in actors' cognitive motivation to realize the potential information benefits that exist in their social networks. Results show that network characteristics do affect information benefits, but these effects are stronger for managers motivated to take advantage of them. These findings both support social capital theory and suggest the important role that personality can play in augmenting social network analyses.

Insulin receptors in podocytes are essential for normal kidney function. Here, we show that insulin evokes a rapid increase in the surface expression of canonical transient receptor potential-6 channel (TRPC6) channels in cultured podocytes, but caused a decrease in surface expression of TRPC5. These effects are accompanied by a marked increase in outwardly rectifying cationic currents that can be blocked by 10 μM SKF96365 or 100 μM La(3+). Application of oleoyl-2-acetyl-sn-glycerol (OAG) also increased SKF96365- and La(3+)-sensitive cationic currents in podocytes. Importantly, current responses to a combination of OAG and insulin were the same amplitude as those evoked by either agent applied alone. This occlusion effect suggests that OAG and insulin are targeting the same population of channels. In addition, shRNA knockdown of TRPC6 markedly reduced cationic currents stimulated by insulin. The effects of insulin on TRPC6 were mimicked by treating podocytes with H(2)O(2). Insulin treatment rapidly increased the generation of H(2)O(2) in podocytes, and it increased the surface expression of the NADPH oxidase NOX4 in cultured podocytes. Basal and insulin-stimulated surface expression of TRPC6 were reduced by pretreatment with diphenylene iodonium, an inhibitor of NADPH oxidases and other flavin-dependent enzymes, by siRNA knockdown of NOX4, and by manganese (III) tetrakis (4-benzoic acid) porphyrin chloride, a membrane-permeable mimetic of superoxide dismutase and catalase. These observations suggest that insulin increases generation of ROS in part through activation of NADPH oxidases, and that this step contributes to modulation of podocyte TRPC6 channels.