One's colleagues can be situated in close physical proximity, yet seem quite distant. Conversely, one's colleagues can be quite far away in objective terms, yet seem quite close. In this paper, we explore this paradoxical phenomenon of feeling close to geographically distant colleagues and propose a model of perceived proximity (a dyadic and asymmetric construct which reflects one person's perception of how close or how far another person is). The model shows how communication and social identification processes, as well as certain individual and socio-organizational factors, affect feelings of proximity. The aim is to broaden organizational studies' theoretical understandings of proximity to include the subjective perception of it. By shifting the focus from objective to perceived proximity, we believe that scholars can resolve many conflicting findings regarding dispersed work. By understanding what leads to perceived proximity, we also believe that managers can achieve many of the benefits of co-location without actually having employees work in one place.

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SummaryThis study examined the development of shared mental models in software development teams over time. Contrary to predictions, team members' mental models about the group's work and each other's expertise did not become more similar over time. Structural equation modelling revealed that as role differentiation increased in these teams, it led to a decrease in interaction and a corresponding decline in shared mental models. Implications for research on shared cognition and team development are explored.

Because plants depend on light for growth, their development and physiology must suit the particular light environment. Plants native to different environments show heritable, apparently adaptive, changes in their response to light. As a first step in unraveling the genetic and molecular basis of these naturally occurring differences, we have characterized intraspecific variation in a light-dependent developmental process-seedling emergence. We examined 141 Arabidopsis thaliana accessions for their response to four light conditions, two hormone conditions and darkness. There was significant variation in all conditions, confirming that Arabidopsis is a rich source of natural genetic diversity. Hierarchical clustering revealed that some accessions had response patterns similar to known photoreceptor mutants, suggesting changes in specific signaling pathways. We found that the unusual far-red response of the Lm-2 accession is due to a single amino-acid change in the phytochrome A (PHYA) protein. This change stabilizes the light-labile PHYA protein in light and causes a 100-fold shift in the threshold for far-red light sensitivity. Purified recombinant Lm-2 PHYA also shows subtle photochemical differences and has a reduced capacity for autophosphorylation. These biochemical changes contrast with previously characterized natural alleles in loci controlling plant development, which result in altered gene expression or loss of gene function.

SummaryNeisseria gonorrhoeae attaches to host epithelial cells via pili and opacity-associated (Opa) outer membrane proteins. Pilus-gonococci (Gc) of strain MS11 adhere to both human and nonhuman cells, but only when particular Opa proteins are expressed; OpaA + variants adhere best, OpaC § variants are next best, and the seven other Opa + variants adhere poorly or not at all. The adherence of OpaA + Gc to Chinese hamster ovary (CHO) cells is inhibited by heparin or heparan sulfate (HS), but not by chondroitin sulfate. OpaA + Gc do not adhere to CHO cells devoid of HS proteoglycans; low concentrations of heparin restore OpaA + Gc adherence to these HS-deficient CHO cells and high concentrations inhibit it. 3H-heparin binding to whole Gc parallels their adherence abilities (OpaA § > OpaC + > OpaH § >> Opas B, D, E, F, G, I = Opa-= 0). Opa proteins separated by SDS-PAGE also bind 3H-heparin. These data suggest that adherence of pilus-, Opa + Gc involves HS-proteoglycan of eukaryotic cells.

Continuous growth and development in plants are accomplished by meristems, groups of undifferentiated cells that persist as stem cells and initiate organs. While the structures of the apical and f loral meristems in dicotyledonous plants have been well described, little is known about the underlying molecular mechanisms controlling cell proliferation and differentiation in these structures. We have shown previously that the CLAVATA1 (CLV1) gene in Arabidopsis encodes a receptor kinase-like protein that controls the size of the apical and f loral meristems. Here, we show that KAPP, a gene encoding a kinase-associated protein phosphatase, is expressed in apical and young f loral meristems, along with CLV1. Overexpression of KAPP mimics the clv1 mutant phenotype. Furthermore, CLV1 has kinase activity: it phosphorylates both itself and KAPP. Finally, KAPP binds and dephosphorylates CLV1. We present a model where KAPP functions as a negative regulator of the CLAVATA1 signal transduction pathway.Flowering plant development is characterized by the establishment and maintenance of shoot apical meristems (SAMs). These are structures, usually at the growing tips of the plants, that contain slowly dividing stem cells in the center that are surrounded by more mitotically active cells that produce organ primordia (1). In Arabidopsis, the SAM is initiated during embryonic growth and then lies dormant until germination. After germination, the SAM initiates leaves, branches, and floral meristems in succession. The floral meristems then produce sepal, petal, stamen, and carpel primordia. The SAM and floral meristems have a similar structure, but differ in the types of organs initiated, in the phyllotactic pattern of organ initiation, and in ultimate meristem fate. SAMs initiate primordia in a spiral pattern and retain indeterminate growth and meristematic activity. In contrast, floral meristems produce organs in a whorled pattern and are determinate-ceasing growth after the initiation of carpels. Therefore, the control of cell proliferation is developmentally regulated, and in addition, cell division patterns result from communication between cells (2).Mutations have been isolated that disrupt meristem structure and͞or function in Arabidopsis. Among these, mutations in the CLAVATA1 (CLV1) and CLAVATA3 (CLV3) loci result in plants with enlarged apical and floral meristems, indicating a defect in the control of cell proliferation versus differentiation in these meristems (3-7). On the basis of double mutant phenotypes and interactions of clv1 and clv3 alleles, the CLV1 and clv3 gene products are thought to function in the same pathway (7). A third gene, WUSCHEL (WUS; ref. 8), has mutant phenotypes opposite those of and epistatic to clv1, suggesting that WUS may encode a downstream component in the CLV1 pathway.CLV1 encodes a putative receptor kinase similar in organization and sequence to the Arabidopsis RLK5 protein, which was isolated by its sequence similarity to protein kinases but is of unknown function (9, 10). Both ...

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