bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitric oxide post-transcriptionally up-regulates LPS-induced IL-8 expression through p38 MAPK activation
Authors: Ma Penglin , Cui Xiaolin , Wang Shuibang , Zhang Jianhua , Nishanian Ervant V , Wang Weihan , Wesley Robert A , Danner Robert L
Published: June 2004

Nitric oxide (NO·) contributes to vascular collapse in septic shock and regulates inflammation. Here, we demonstrate in lipopolysaccharide (LPS)-stimulated human THP-1 cells and monocytes that NO· regulates interleukin (IL)-8 and tumor necrosis factor α (TNF-α) by distinct mechanisms. Dibutyryl-cyclic guanosine 5′-monophosphate (cGMP) failed to simulate NO·-induced increases in TNF-α or IL-8 production. In contrast, dibutyryl-cyclic adenosine monophosphate blocked NO·-induced production of TNF-α (P=0.009) but not IL-8. NO· increased IL-8 (5.7-fold at 4 h; P=0.04) and TNF-α mRNA levels (2.2-fold at 4 h; P=0.037). However, nuclear run-on assays demonstrated that IL-8 transcription was slightly decreased by NO· (P=0.08), and TNF-α was increased (P=0.012). Likewise, NO· had no effect on IL-8 promoter activity (P=0.84) as measured by reporter gene assay. In THP-1 cells and human primary monocytes treated with actinomycin D, NO· had no effect on TNF-α mRNA stability (P>0.3 for both cell types) but significantly stabilized IL-8 mRNA (P=0.001 for both cell types). Because of its role in mRNA stabilization, the p38 mitogen-activated protein kinase (MAPK) pathway was examined and found to be activated by NO· in LPS-treated THP-1 cells and human monocytes. Further, SB202190, a p38 MAPK inhibitor, was shown to block NO·-induced stabilization of IL-8 mRNA (P<0.02 for both cell types). Thus, NO· regulates IL-8 but not TNF-α post-transcriptionally. IL-8 mRNA stabilization by NO· is independent of cGMP and at least partially dependent on p38 MAPK activation.
A record of soil loss from Butrint, southern Albania, using mineral magnetism indicators and charcoal (AD 450 to 1200)
Authors: Hounslow Mark W. , Chepstow-Lusty Alex
Published: June 2004

Mineral magnetic and charcoal analyses were carried out on two sections 0.6 km apart on the Vrina Plain at Shën Dëlli, a suburb of Roman Butrint (ancient Buthrotum), southern Albania. Using a chronology developed by archaeomagnetic dating, the two sections postdate Roman archaeological structures on the site, providing a sediment record between c. ad 450 and 1200. Environmental magnetic data were analysed using cluster analysis to interpret a consistent stratigraphic development between the two sections. Above the archaeo logical remains on the western side of the Shën Dëli settlement, marsh clay sedimentation started ad 450–500, contemporaneous with evidence of site occupation. Anthropogenic activity is evident from the high macro-charcoal content, which declines at ad 750–800, and may mark the end of settlement in the vicinity. Both sections show similar sedimentation rates which, when extrapolated, suggest that marsh growth to the present day levels would have been completed between about ad 1500 and 1600. From about ad 750 to 850 sedimentation continued consistently across the site, with low microcharcoal input, but an increasingly important pres ence of magnetic minerals, including superparamagnetic magnetite, associated with top soil input. Between ad 1050 and 1200 the input from magnetically enhanced topsoil had increased tenfold over 300 years earlier, indicating that soil erosion was a major sediment source. This marked increase in soil loss could be due either to different land-management practices or to local deforestation. Whether this change in topsoil loss is linked to climatic changes associated with the beginning of the ‘Mediaeval Warm Period’ (c. ad 1000–1400) needs further investigation.
A twentieth-century neoparaglacial rock topple on a glacier foreland, Ö tztal Alps, Austria
Authors: Matthews John A. , Shakesby Richard A.
Published: June 2004

A small-scale rock-slope failure firmly dated by historical photographic evidence, supported by lichenometry, to between ad 1977 and 1991 is described from the glacier foreland of Marzellferner and Schalf ferner, Ö tztal Alps, Austria. There was a timelag of 90–100 years between deglacierization of the site around ad 1890 and slope failure. An extreme rainfall event in ad 1987 is suggested as the most likely trigger factor affecting a rock slope weakened by several possible processes including debuttressing (producing dilation joints), fluctuating cleft-water pressure, and permafrost aggradation and degradation. The rock topple is considered to represent an example of subaerial geomorphological processes conditioned by‘Little Ice Age’ glacierization; similar neoparaglacial effects can be expected to follow other neoglacial events.
The history of Holocene soil erosion in the Phlious Basin, NE Peloponnese, Greece, based on optical dating
Authors: Fuchs M. , Lang A. , Wagner G. A.
Published: June 2004

Anthropogenic induced soil erosion has occurred in the Mediterranean during historic and pre historic times, but precise timeframes for periods of past soil erosion are largely missing due to the lack of datable material and suitable dating methods. In this study, optical dating of colluvial sediments from the Phlious Basin, NE Peloponnese, Greece, was applied. The results show that soil erosion derived colluvium formed under a Mediterranean type climate can be successfully dated by optical stimulated luminescence (OSL), and a high-resolution chronology of Holocene soil erosion could be established. Colluvial formation occurred in the early Holocene, but increased distinctly in the seventh millennium, parallel with the onset of the Neolithic (the start of farming activities). Other periods of strong colluviation are the Middle and Late Bronze Age (second millennium), the Roman period (first century to sixth century) and the period since the sixteenth century. Rates of reduced colluviation occurred during the Chalcolithic to the Early Bronze Age (4500–2050 a) and the Early Iron Age (1065–725 a). Based on thin section analysis of the colluvial sediments, no traces of in-situ soil formation and thus no periods of landscape stability were detected for the Holocene. Results show that human activity is the dominant factor for Holocene landscape changes in the area studied.
Palaeoecological and archaeological evidence for Bronze Age human activity on the Isle of Man
Authors: Chiverrell R. C. , Innes J. B. , Blackford J. J. , Woodcock J. J. , Davey P. J. , Tomlinson P. R. , Rutherford M. M. , Thomas G. S.P.
Published: June 2004

Pollen analytical data and the archaeological record for the Isle of Man identify increased human impact on the landscape during the Bronze Age. Pollen profiles from seven sites are presented, all identifying a greater scale of activity than existed during the preceding Neolithic. The archaeological record shows similar increases in both the number and the distribution of finds. Both the archaeology and palaeoecology indicate an increase in human presence in the lowlands, with some sustained arable and pastoral farming and increased evidence of burials. The uplands were perhaps less affected. Four sites have yielded palaeoecological information from archaeological contexts that unambiguously link pollen analytical evidence for disturbance with archaeological evidence for the presence of people. The scale of human disturbance of woodlands on the Isle of Man is similar to that found in southern Scotland and northern England during the Bronze Age, but less intensive than that encountered in northern Ireland. Cereal pollen indicates limited cultivation in lowland areas of the Isle of Man throughout the Bronze Age, perhaps on a lesser scale compared with surrounding regions and with some periods of woodland regeneration.
Pollen evidence for late-Holocene climatic variability at Laguna de Aculeo, Central Chile (lat. 34°S)
Authors: Villa-Martínez Rodrigo , Villagrán Carolina , Jenny Bettina
Published: June 2004

A pollen record is presented from Laguna de Aculeo (33°50'S, 70°55'W, 360m a.s.l.) that documents important vegetation changes over the last 2500cal. yr in Central Chile. Grasses, composites, trees, paludal and aquatic taxa dominated the Aculeo watershed between 2500 and 100cal. yr BP under a humid climate. Large amplitude fluctuations of pollen and microalgal accumulation rates and numerous turbidite layers during this interval, however, suggest high precipitation variability probably linked to El Niño-Southern Oscillation (ENSO) events. Although the expansion of warm sclerophyllous forest taxa over the last 100 years could be interpreted as an onset of a drier and warmer climate, this trend was more likely linked to human activities in the watershed. High accumulation rates of microscopic charcoal particles, exotic pollen taxa, and a shift from oligo-mesotrophic to hypereutrophic indicators would seem to back the latter hypothesis.
Past uppermost tree limit in the Central European Alps (Switzerland) based on soil and soil charcoal
Authors: Carnelli Adriana L. , Theurillat Jean-Paul , Thinon Michel , Vadi Gaëlle , Talon Brigitte
Published: June 2004

The uppermost limits of past treelines in the Alps are established using soil type and soil charcoal mass. In all the studied sites, a sharp decrease of soil charcoal mass is correlated with the upper altitudinal limit of podzols. On the basis of this evidence, the uppermost tree limit reached 2500±100m a.s.l. in the Valaisan Alps during the Holocene, i.e., it was 250±100 m higher than today's potential treeline. Consequently, the timberline would have reached 2400±100m a.s.l.. From the strong decline of charcoals concentration in soils above 2500m a.s.l., we infer that conifer species were rare or very rare above this altitude during the Holocene. Joint interpretation of charcoal, pollen, soil and macrofossil data suggest that alpine meadows with at most scattered conifers were present throughout the Holocene in the today's middle and upper alpine belt.
Mid-to late-Holocene coastal dune event stratigraphy for the north coast of Northern Ireland
Authors: Wilson Peter , McGourty John , Bateman Mark D.
Published: June 2004

An event stratigraphy of dune stability/instability phases has been reconstructed, using 22 radiocarbon and 13 luminescence dates, for six dunefields along the north coast of Northern Ireland. There is no evidence for dune development prior to ċ. 7000 cal. years BP, during the early-Holocene rapid rise in RSL, and only limited evidence for sand accumulation in association with the RSL maximum. Dunefield dates correspond to either the subsequent regressive phase or, later, the gradual transgressive phase of RSL history in the mid-and late Holocene. At these times accommodation space for dune development and sediment supply were maximized. Episodes of climatic deterioration, particularly at 3100–2400 cal. years BP and 650–50 cal. years BP (the‘Little Ice Age’) were marked by widespread dune instability. A similar coincidence in timing has been recorded for dune systems elsewhere in northwestern Europe and is generally attributed to an increased frequency of storms and storm surges associated with the climatic downturns. However, between-site inconsistencies in the event stratigraphy suggest that site-specific factors (e.g., sediment availability) had a modulating influence on dune regional controls.
A diatom-based Holocene palaeoenvironmental record from a mid-arctic lake on Boothia Peninsula, Nunavut, Canada
Authors: LeBlanc M. , Gajewski K. , Hamilton P. B.
Published: June 2004

A 485 cm sediment core from a lake unoffcially called JR01, Boothia Peninsula, Nunavut, Canada, yielded a high-resolution diatom record documenting environmental change in the mid-arctic. Five radiocarbon dates provided the chronology. Changes in diatom composition and sediment character istics indicated distinct shifts in the Holocene climate. A more diverse and productive diatom flora implies warmer temperatures in the middle Holocene. A subsequent complete shift in diatom composition to a predominantly Fragilaria sensu lato flora and a reduction in diversity and production suggests cooler climates in this region after 4600cal. BP. Smaller-scale climatic fluctuations, such as the‘Little Ice Age’ (LIA, 600–150 cal. BP) and the‘Mediaeval Warm Period’ (MWP, 1150–600 cal. BP), caused shifts in the diatom flora and production. Subtle shifts in floristic diversity within the LIA may reflect climatic variability at a century scale. A gradual shift to a more diverse and productive flora in the last 150 years suggests a response to the recent warming trend.
Late-Holocene teleconnections between tropical Pacific climatic variability and precipitation in the western USA: evidence from proxy records
Authors: Graham Nicholas E.
Published: June 2004

Decadal to multidecadal fluctuations between drought and relatively more moist conditions are a defining characteristic of precipitation variability in the western USA. In an attempt to better understand the forcing mechanisms responsible for producing this variability, relationships between proxy indices of tropical climatic variability and precipitation-related reconstructions in the western USA are examined. The tropical proxies include the δ18O record from the Quelccaya ice cap (southern subtropical Andes) and the lacustrine sedimentation record from Laguna Pallcacocha (near-equatorial Andes). The precipi tation-related records are tree-ring reconstructions of river flow, drought severity and precipitation over the contiguo USA. One new finding is a consistent relation between decadal variability in El Niñno activity and precipitation-related proxies through much of the western USA during the past 1200 years. Surpris ingly, the proxy records do not show a systematic link between inferred El Niñno activity and precipitation in the interior Southwest USA. A second new result is the existence of relationships at decadal to multidecadal timescales between fluctuations in Quelccaya δ18O, precipitation-related proxies from the western USA, and proxy records from the Pacific Basin. This finding links the Quelccaya record to the transhemi spheric Pacific decadal-scale climatic variability documented from proxy records by Villalba et al. (2001), and suggests that similar changes in the large-scale circulation changes accompany both the decadal and multidecadal signals. A composite constructed using gridded proxy precipitation constructed on the basis of decadal-scale fluctuations in inferred-El Niñno activity shows a pattern rather different to Niñno-based teleconnection maps for the instrumental record. In the proxy-based composite, positive values cover much of the extreme western, west central and southeastern USA, with negative values in the central Mis sissippi Valley. The interior Southwest shows essentially no response. A second composite based on multi decadal variability in Quelccayaδ18O shows a well-developed dipole pattern across the western USA with opposing centres in the interior Southwest and Northwest. It is suggested that this dipole pattern results from multidecadal variability in tropical Pacific SSTs and resulting changes in the strength of the Northeast Pacific High and the latitudinal distribution of cool season westerlies across the eastern North Pacific and western USA.
Middle-Holocene mobilization of aeolian sand in western upper Michigan and the potential relationship with climate and fire
Authors: Arbogast Alan F. , Packman Susan C.
Published: June 2004

A forested dunefield covers the Baraga Plains in western upper Michigan. The ages of five dunes, from across the dunefield, were determined by optically stimulated luminescence (OSL), employing the single-aliquot regenerative-dose (SAR) method on quartz grains. The results indicate that sand mobilization was restricted to the middle Holocene, at around 7 ka. Four environmental variables, rapid climatic oscillations, fire, strong winds and a dry climate are invoked as a combined cause of dune formation. This study provides further evidence for the wide extent of aeolian activity in the upper Midwest of North America during the middle Holocene.
Benefits and Costs of Interventions to Improve Breast Cancer Outcomes in African American Women
Authors: Mandelblatt Jeanne S. , Schechter Clyde B. , Yabroff K. Robin , Lawrence William , Dignam James , Muennig Peter , Chavez Yoko , Cullen Jennifer , Fahs Marianne
Published: June 2004

Purpose

Historically, African American women have experienced higher breast cancer mortality than white women, despite lower incidence. Our objective was to evaluate whether costs of increasing rates of screening or application of intensive treatment will be off-set by survival benefits for African American women.

Methods

We use a stochastic simulation model of the natural history of breast cancer to evaluate the incremental societal costs and benefits of status quo versus targeted biennial screening or treatment improvements among African Americans 40 years of age and older. Main outcome measures were number of mammograms, stage, all-cause mortality, and discounted costs per life year saved (LYS).

Results

At the current screening rate of 76%, there is little incremental benefit associated with further increasing screening, and the costs are high: $124,053 and $124,217 per LYS for lay health worker and patient reminder interventions, respectively, compared with the status quo. Using reminders would cost $51,537 per LYS if targeted to virtually unscreened women or $78,130 per LYS if targeted to women with a two-fold increase in baseline risk. If all patients received the most intensive treatment recommended, costs increase but deaths decrease, for a cost of $52,678 per LYS. Investments of up to $6,000 per breast cancer patient could be used to enhance treatment and still yield cost-effectiveness ratios of less than $75,000 per LYS.

Conclusion

Except in pockets of unscreened or high-risk women, further investments in interventions to increase screening are unlikely to be an efficient use of resources. Ensuring that African American women receive intensive treatment seems to be the most cost-effective approach to decreasing the disproportionate mortality experienced by this population.
XPD and XRCC1 Genetic Polymorphisms Are Prognostic Factors in Advanced Non—Small-Cell Lung Cancer Patients Treated With Platinum Chemotherapy
Authors: Gurubhagavatula Sarada , Liu Geoffrey , Park Sohee , Zhou Wei , Su Li , Wain John C. , Lynch Thomas J. , Neuberg Donna S. , Christiani David C.
Published: June 2004

Purpose

Platinum agents cause DNA cross-linking and oxidative damage. Genetic polymorphisms of DNA repair genes are associated with differential DNA repair activity and may explain interindividual differences in overall survival after therapy with platinum agents for non–small-cell lung cancer (NSCLC).

Methods

We used polymerase chain reaction–restriction fragment length polymorphism to evaluate genetic polymorphisms of the XPD (Asp312Asn) and XRCC1 (Arg399Gln) DNA repair genes in 103 patients with stage III (54%) and IV (46%) NSCLC treated with platinum-based chemotherapy.

Results

Median age was 58 years (range, 32 to 77 years), 49% were females, and there were 86 deaths. Median follow-up period was 61.9 months. Median survival time (MST) was 14.9 months; by stage, MST was 28.6 months (IIIA), 16.0 months (IIIB), and 9.3 months (IV). Genotypes were not associated with stage. Increasing numbers of either XPD or XRCC1 variant alleles were associated with shorter overall survival (P = .003 and P = .07, respectively, by log-rank test). Similarly, when we compared combinations of variant alleles across both polymorphisms, we found that a greater number of variant alleles was associated with decreasing overall survival (P = .009, log-rank test). These polymorphisms independently predicted overall survival even after taking into account stage, performance status, and chemotherapy regimen.

Conclusion

Genetic polymorphisms in XPD and XRCC1 may be important prognostic factors in platinum-treated patients with advanced NSCLC.
Phase I Trial of Yttrium-90—Labeled Anti—Prostate-Specific Membrane Antigen Monoclonal Antibody J591 for Androgen-Independent Prostate Cancer
Authors: Milowsky Matthew I. , Nanus David M. , Kostakoglu Lale , Vallabhajosula Shankar , Goldsmith Stanley J. , Bander Neil H.
Published: June 2004

Purpose

To determine the maximum-tolerated dose (MTD), toxicity, human antihuman antibody (HAHA) response, pharmacokinetics, organ dosimetry, targeting, and preliminary efficacy of yttrium-90–labeled anti–prostate-specific membrane antigen monoclonal antibody J591 (90Y-J591) in patients with androgen-independent prostate cancer (PC).

Patients and Methods

Patients with androgen-independent PC and evidence of disease progression received indium-111–J591 for pharmacokinetic and biodistribution determinations followed 1 week later by 90Y-J591 at five dose levels: 5, 10, 15, 17.5, and 20 mCi/m2. Patients were eligible for up to three re-treatments if platelet and neutrophil recovery was satisfactory.

Results

Twenty-nine patients with androgen-independent PC received 90Y-J591, four of whom were re-treated. Dose limiting toxicity (DLT) was seen at 20 mCi/m2, with two patients experiencing thrombocytopenia with non–life-threatening bleeding episodes requiring platelet transfusions. The 17.5-mCi/m2 dose level was determined to be the MTD. No re-treated patients experienced DLT. Nonhematologic toxicity was not dose limiting. Targeting of known sites of bone and soft tissue metastases was seen in the majority of patients. No HAHA response was seen. Antitumor activity was seen, with two patients experiencing 85% and 70% declines in prostate-specific antigen (PSA) levels lasting 8 and 8.6 months, respectively, before returning to baseline. Both patients had objective measurable disease responses. An additional six patients (21%) experienced PSA stabilization.

Conclusion

The recommended dose for 90Y-J591 is 17.5 mCi/m2. Acceptable toxicity, excellent targeting of known sites of PC metastases, and biologic activity in patients with androgen-independent PC warrant further investigation of 90Y-J591 in the treatment of patients with PC.
Chip-mediated partnerships of the homeodomain proteins Bar and Aristaless with the LIM-HOM proteins Apterous and Lim1 regulate distal leg development
Authors: Pueyo Jose Ignacio , Couso Juan Pablo
Published: June 2004

Proximodistal patterning in Drosophila requires division of the developing leg into increasingly smaller, discrete domains of gene function. The LIM-HOM transcription factors apterous (ap) and Lim1 (also known as dlim1), and the homeobox genes Bar and aristaless (al) are part of the gene battery required for the development of specific leg segments. Our genetic results show that there are posttranslational interactions between Ap, Bar and the LIM-domain binding protein Chip in tarsus four, and between Al, Lim1 and Chip in the pretarsus, and that these interactions depend on the presence of balanced amounts of such proteins. We also observe in vitro protein binding between Bar and Chip, Bar and Ap, Lim1 and Chip, and Al and Chip. Together with the previous evidence for interactions between Ap and Chip, these results suggest that these transcription factors form protein complexes during leg development. We propose that the different developmental outcomes of LIM-HOM function are due to the precise identity and dosage of the interacting partners present in a given cell.
The mitotic-to-endocycle switch inDrosophilafollicle cells is executed by Notch-dependent regulation of G1/S, G2/M and M/G1 cell-cycle transitions
Authors: Shcherbata Halyna R. , Althauser Cassandra , Findley Seth D. , Ruohola-Baker Hannele
Published: June 2004

The Notch signaling pathway controls the follicle cell mitotic-to-endocycle transition in Drosophila oogenesis by stopping the mitotic cycle and promoting the endocycle. To understand how the Notch pathway coordinates this process, we have identified and performed a functional analysis of genes whose transcription is responsive to the Notch pathway at this transition. These genes include the G2/M regulator Cdc25 phosphatase, String; a regulator of the APC ubiquitination complex Hec/CdhFzr and an inhibitor of the CyclinE/CDK complex, Dacapo. Notch activity leads to downregulation of String and Dacapo, and activation of Fzr. All three genes are independently responsive to Notch. In addition, CdhFzr, an essential gene for endocycles, is sufficient to stop mitotic cycle and promote precocious endocycles when expressed prematurely during mitotic stages. In contrast,overexpression of the growth controller Myc does not induce premature endocycles but accelerates the kinetics of normal endocycles. We also show that Archipelago (Ago), a SCF-regulator is dispensable for mitosis, but crucial for endocycle progression in follicle epithelium. The results support a model in which Notch activity executes the mitotic-to-endocycle switch by regulating all three major cell cycle transitions. Repression of String blocks the M-phase, activation of Fzr allows G1 progression and repression of Dacapo assures entry into the S-phase. This study provides a comprehensive picture of the logic that external signaling pathways may use to control cell cycle transitions by the coordinated regulation of the cell cycle.
Asymmetric production of surface-dividing and non-surface-dividing cortical progenitor cells
Authors: Miyata Takaki , Kawaguchi Ayano , Saito Kanako , Kawano Masako , Muto Tetsuji , Ogawa Masaharu
Published: June 2004

Mature neocortical layers all derive from the cortical plate (CP), a transient zone in the dorsal telencephalon into which young neurons are continuously delivered. To understand cytogenetic and histogenetic events that trigger the emergence of the CP, we have used a slice culture technique. Most divisions at the ventricular surface generated paired cycling daughters (P/P divisions) and the majority of the P/P divisions were asymmetric in daughter cell behavior; they frequently sent one daughter cell to a non-surface (NS)position, the subventricular zone (SVZ), within a single cell-cycle length while keeping the other mitotic daughter for division at the surface. The NS-dividing cells were mostly Hu+ and their daughters were also Hu+, suggesting their commitment to the neuronal lineage and supply of early neurons at a position much closer to their destiny than from the ventricular surface. The release of a cycling daughter cell to SVZ was achieved by collapse of the ventricular process of the cell, followed by its NS division. Neurogenin2 (Ngn2) was immunohistochemically detected in a certain cycling population during G1 phase and was further restricted during G2-M phases to the SVZ-directed population. Its retroviral introduction converted surface divisions to NS divisions. The asymmetric P/P division may therefore contribute to efficient neuron/progenitor segregation required for CP initiation through cell cycle-dependent and lineage-restricted expression of Ngn2.
Tbx1has a dual role in the morphogenesis of the cardiac outflow tract
Authors: Xu Huansheng , Morishima Masae , Wylie John N. , Schwartz Robert J. , Bruneau Benoit G. , Lindsay Elizabeth A. , Baldini Antonio
Published: June 2004

Dysmorphogenesis of the cardiac outflow tract (OFT) causes many congenital heart defects, including those associated with DiGeorge syndrome. Genetic manipulation in the mouse and mutational analysis in patients have shown that Tbx1, a T-box transcription factor, has a key role in the pathogenesis of this syndrome. Here, we have dissected Tbx1 function during OFT development using genetically modified mice and tissue-specific deletion, and have defined a dual role for this protein in OFT morphogenesis. We show that Tbx1 regulates cell contribution to the OFT by supporting cell proliferation in the secondary heart field, a source of cells fated to the OFT. This process might be regulated in part by Fgf10, which we show for the first time to be a direct target of Tbx1 in vitro. We also show that Tbx1 expression is required in cells expressing Nkx2.5 for the formation of the aorto-pulmonary septum, which divides the aorta from the main pulmonary artery. These results explain why aortic arch patterning defects and OFT defects can occur independently in individuals with DiGeorge syndrome. Furthermore, our data link, for the first time, the function of the secondary heart field to congenital heart disease.
Odd-skipped related 2 (Osr2) encodes a key intrinsic regulator of secondary palate growth and morphogenesis
Authors: Lan Yu , Ovitt Catherine E. , Cho Eui-Sic , Maltby Kathleen M. , Wang Qingru , Jiang Rulang
Published: June 2004

Development of the mammalian secondary palate involves multiple steps of highly regulated morphogenetic processes that are frequently disturbed during human development, resulting in the common birth defect of cleft palate. Neither the molecular processes governing normal palatogenesis nor the causes of cleft palate is well understood. In an expression screen to identify new transcription factors regulating palate development, we previously isolated the odd-skipped related 2 (Osr2) gene, encoding a zinc-finger protein homologous to the Drosophila odd-skipped gene product, and showed that Osr2 mRNA expression is specifically activated in the nascent palatal mesenchyme at the onset of palatal outgrowth. We report that a targeted null mutation in Osr2 impairs palatal shelf growth and causes delay in palatal shelf elevation, resulting in cleft palate. Whereas palatal outgrowth initiates normally in the Osr2 mutant embryos, a significant reduction in palatal mesenchyme proliferation occurs specifically in the medial halves of the downward growing palatal shelves at E13.5, which results in retarded, mediolaterally symmetric palatal shelves before palatal shelf elevation. The developmental timing of palatal growth retardation correlates exactly with the spatiotemporal pattern of Osr1 gene expression during palate development. Furthermore, we show that the Osr2 mutants exhibit altered gene expression patterns, including those of Osr1, Pax9 and Tgfb3, during palate development. These data identify Osr2 as a key intrinsic regulator of palatal growth and patterning.
Organization of cardiac chamber progenitors in the zebrafish blastula
Authors: Keegan Brian R. , Meyer Dirk , Yelon Deborah
Published: June 2004

Organogenesis requires the specification of a variety of cell types and the organization of these cells into a particular three-dimensional configuration. The embryonic vertebrate heart is organized into two major chambers, the ventricle and atrium, each consisting of two tissue layers, the myocardium and endocardium. The cellular and molecular mechanisms responsible for the separation of ventricular and atrial lineages are not well understood. To test models of cardiac chamber specification, we generated a high-resolution fate map of cardiac chamber progenitors in the zebrafish embryo at 40% epiboly, a stage prior to the initiation of gastrulation. Our map reveals a distinct spatial organization of myocardial progenitors: ventricular myocardial progenitors are positioned closer to the margin and to the dorsal midline than are atrial myocardial progenitors. By contrast, ventricular and atrial endocardial progenitors are not spatially organized at this stage. The relative orientations of ventricular and atrial myocardial progenitors before and after gastrulation suggest orderly movements of these populations. Furthermore, the initial positions of myocardial progenitors at 40% epiboly indicate that signals residing at the embryonic margin could influence chamber fate assignment. Indeed, via fate mapping, we demonstrate that Nodal signaling promotes ventricular fate specification near the margin, thereby playing an important early role during myocardial patterning.
HUA ENHANCER3 reveals a role for a cyclin-dependent protein kinase in the specification of floral organ identity inArabidopsis
Authors: Wang Wenming , Chen Xuemei
Published: June 2004

In plants, organs are generated post-embryonically from highly organized structures known as meristems. Cell division in the meristem is closely integrated with cell fate specification and organ formation. The presence of multiple cyclin-dependent kinases (CDKs) and their partner cyclins in plants and other multicellular organisms probably reflects the complexity of cell cycle regulation within developmental contexts. The Arabidopsisgenome encodes at least eight CDKs and 30 cyclins. However, no mutants in any CDKs have been reported, and the function of the great majority of these genes in plant development is unknown. We show that HUA ENHANCER3(HEN3), which encodes CDKE, a homolog of mammalian CDK8, is required for the specification of stamen and carpel identities and for the proper termination of stem cells in the floral meristem. Therefore, CDK8 plays a role in cell differentiation in a multicellular organism.
The zebrafish Iroquois geneiro7positions the r4/r5 boundary and controls neurogenesis in the rostral hindbrain
Authors: Lecaudey Virginie , Anselme Isabelle , Rosa Frédéric , Schneider-Maunoury Sylvie
Published: June 2004

Early brain regionalisation involves the activation of genes coding for transcription factors in distinct domains of the neural plate. The limits of these domains often prefigure morphological boundaries. In the hindbrain,anteroposterior patterning depends on a segmentation process that leads to the formation of seven bulges called rhombomeres (r). The molecular cues involved in the early subdivision of the hindbrain and in rhombomere formation are not well understood. We show that iro7, a zebrafish gene coding for a transcription factor of the Iroquois family, is expressed at the end of gastrulation in the future midbrain and hindbrain territories up to the prospective r4/r5 boundary. This territory is strictly complementary to the expression domain of another homeobox gene, vhnf1, in the caudal neural plate. We demonstrate that Iro7 represses vhnf1 expression anterior to their common border and that, conversely, vHnf1 represses iro7 expression caudal to it. This suggests that the r4/r5 boundary is positioned by mutual repression between these two transcription factors. In addition, iro7 is involved in the specification of primary neurons in the rostral hindbrain. In particular, it is essential for the formation of the Mauthner neurons in r4. We propose that iro7 has a dual function in the hindbrain of the zebrafish embryo: it is required for the proper positioning of the prospective r4/r5 boundary and it promotes neurogenesis in the anterior hindbrain.
Thedachsousgene, a member of the cadherin family, is required for Wg-dependent pattern formation in theDrosophilawing disc
Authors: Rodríguez Isabel
Published: June 2004

The dachsous (ds) gene encodes a member of the cadherin family involved in the non-canonical Wnt signaling pathway that controls the establishment of planar cell polarity (PCP) in Drosophila. ds is the only known cadherin gene in Drosophila with a restricted spatial pattern of expression in imaginal discs from early stages of larval development. In the wing disc, ds is first expressed distally, and later is restricted to the hinge and lateral regions of the notum. Flies homozygous for strong ds hypomorphic alleles display previously uncharacterized phenotypes consisting of a reduction of the hinge territory and an ectopic notum. These phenotypes resemble those caused by reduction of the canonical Wnt signal Wingless (Wg) during early wing disc development. An increase in Wg activity can rescue these phenotypes,indicating that Ds is required for efficient Wg signaling. This is further supported by genetic interactions between ds and several components of the Wg pathway in another developmental context. Ds and Wg show a complementary pattern of expression in early wing discs, suggesting that Ds acts in Wg-receiving cells. These results thus provide the first evidence for a more general role of Ds in Wnt signaling during imaginal development, not only affecting cell polarization but also modulating the response to Wg during the subdivision of the wing disc along its proximodistal (PD) axis.
Homotypic signalling regulates Gata1 activity in the erythroblastic island
Authors: Gutiérrez Laura , Lindeboom Fokke , Langeveld An , Grosveld Frank , Philipsen Sjaak , Whyatt David
Published: June 2004

Gata1 is a transcription factor essential for erythropoiesis. Erythroid cells lacking Gata1 undergo apoptosis, while overexpression of Gata1 results in a block in erythroid differentiation. However, erythroid cells overexpressing Gata1 differentiate normally in vivo when in the presence of wild-type cells. We have proposed a model, whereby a signal generated by wild-type cells (red cell differentiation signal; REDS) overcomes the intrinsic defect in Gata1-overexpressing erythroid cells. The simplest interpretation of this model is that wild-type erythroid cells generate REDS. To substantiate this notion, we have exploited a tissue specific Cre/loxP system and the process of X-inactivation to generate mice that overexpress Gata1 in half the erythroid cells and are Gata1 null in the other half. The results show that the cells supplying REDS are erythroid cells. This study demonstrates the importance of intercellular signalling in regulating Gata1 activity and that this homotypic signalling between erythroid cells is crucial to normal differentiation.
Binding of 14-3-3β but not 14-3-3σ controls the cytoplasmic localization of CDC25B: binding site preferences of 14-3-3 subtypes and the subcellular localization of CDC25B
Authors: Uchida Sanae , Kuma Akiko , Ohtsubo Motoaki , Shimura Mari , Hirata Masato , Nakagama Hitoshi , Matsunaga Tsukasa , Ishizaka Yukihito , Yamashita Katsumi
Published: June 2004

The dual specificity phosphatase CDC25B positively controls the G2-M transition by activating CDK1/cyclin B. The binding of 14-3-3 to CDC25B has been shown to regulate the subcellular redistribution of CDC25B from the nucleus to the cytoplasm and may be correlated with the G2 checkpoint. We used a FLAG-tagged version of CDC25B to study the differences among the binding sites for the 14-3-3 subtypes, 14-3-3β, 14-3-3ϵ and 14-3-3σ, and the relationship between subtype binding and the subcellular localization of CDC25B. All three subtypes were found to bind to CDC25B. Site-directed mutagenesis studies revealed that 14-3-3β bound exclusively near serine-309 of CDC25B1, which is within a potential consensus motif for 14-3-3 binding. By contrast, 14-3-3σ bound preferentially to a site around serine-216, and the presence of serine-137 and -309 enhanced the binding. In addition to these binding-site differences, we found that the binding of 14-3-3β drove CDC25B to the cytoplasm and that mutation of serine-309 to alanine completely abolished the cytoplasmic localization of CDC25B. However, co-expression of 14-3-3σ and CDC25B did not affect the subcellular localization of CDC25B. Furthermore, serine-309 of CDC25B was sufficient to produce its cytoplasmic distribution with co-expression of 14-3-3β, even when other putative 14-3-3 binding sites were mutated. 14-3-3ϵ resembled 14-3-3β with regard to its binding to CDC25B and the control of CDC25B subcellular localization. The results of the present study indicate that two 14-3-3 subtypes can control the subcellular localization of CDC25B by binding to a specific site and that 14-3-3σ has effects on CDC25B other than the control of its subcellular localization.
Marrow-isolated adult multilineage inducible (MIAMI) cells, a unique population of postnatal young and old human cells with extensive expansion and differentiation potential
Authors: D'Ippolito Gianluca , Diabira Sylma , Howard Guy A. , Menei Philippe , Roos Bernard A. , Schiller Paul C.
Published: June 2004

We report here the isolation of a population of non-transformed pluripotent human cells from bone marrow after a unique expansion/selection procedure. This procedure was designed to provide conditions resembling the in vivo microenvironment that is home for the most-primitive stem cells. Marrow-adherent and -nonadherent cells were co-cultured on fibronectin, at low oxygen tension, for 14 days. Colonies of small adherent cells were isolated and further expanded on fibronectin at low density, low oxygen tension with 2% fetal bovine serum. They expressed high levels of CD29, CD63, CD81, CD122, CD164, hepatocyte growth factor receptor (cMet), bone morphogenetic protein receptor 1B (BMPR1B), and neurotrophic tyrosine kinase receptor 3 (NTRK3) and were negative for CD34, CD36, CD45, CD117 (cKit) and HLADR. The embryonic stem cell markers Oct-4 and Rex-1, and telomerase were expressed in all cultures examined. Cell-doubling time was 36 to 72 hours, and cells have been expanded in culture for more than 50 population doublings. This population of cells was consistently isolated from men and women of ages ranging from 3- to 72-years old. Colonies of cells expressed numerous markers found among embryonic stem cells as well as mesodermal-, endodermal- and ectodermal-derived lineages. They have been differentiated to bone-forming osteoblasts, cartilage-forming chondrocytes, fat-forming adipocytes and neural cells and to attachment-independent spherical clusters expressing genes associated with pancreatic islets. Based on their unique characteristics and properties, we refer to them as human marrow-isolated adult multilineage inducible cells, or MIAMI cells. MIAMI cells proliferate extensively without evidence of senescence or loss of differentiation potential and thus may represent an ideal candidate for cellular therapies of inherited or degenerative diseases.
Human topoisomerase IIα nuclear export is mediated by two CRM-1-dependent nuclear export signals
Authors: Turner Joel G. , Engel Roxanne , Derderian Jennifer A. , Jove Richard , Sullivan Daniel M.
Published: June 2004

Resistance to chemotherapeutic drugs is a major obstacle in the treatment of leukemia and multiple myeloma. We have previously found that myeloma and leukemic cells in transition from low-density log phase conditions to high-density plateau phase conditions export substantial amounts of endogenous topoisomerase II alpha from the nucleus to the cytoplasm. In order for topoisomerase-targeted chemotherapy to function, the topoisomerase target must have access to the nuclear DNA. Therefore, the nuclear export of topoisomerase II alpha may contribute to drug resistance, and defining this mechanism may lead to methods to preclude this avenue of resistance. We have identified nuclear export signals for topoisomerase II alpha at amino acids 1017-1028 and 1054-1066, using FITC-labeled BSA-export signal peptide conjugates microinjected into the nuclei of HeLa cells. Functional confirmation of both signals (1017-1028 and 1054-1066) was provided by transfection of human myeloma cells with plasmids containing the gene for a full-length human FLAG-topoisomerase fusion protein, mutated at hydrophobic amino acid residues in the export signals. Of the six putative export signals tested, the two sites above were found to induce export into the cytoplasm. Export by both signals was blocked by treatment of the cells with leptomycin B, indicating that a CRM-1-dependent pathway mediates export. Site-directed mutagenesis of two central hydrophobic residues in either export signal in full-length human topoisomerase blocked export of recombinant FLAG-topoisomerase II alpha, indicating that both signals may be required for export. Interestingly, this pair of nuclear export signals (1017-1028 and 1054-1066) also defines a dimerization domain of the topoisomerase II alpha molecule.
Impairment of SHOX nuclear localization as a cause for Léri-Weill syndrome
Authors: Sabherwal Nitin , Schneider Katja U. , Blaschke Rüdiger J. , Marchini Antonio , Rappold Gudrun
Published: June 2004

We report the characterization of the nuclear localization signal (NLS) of the short stature homeobox gene SHOX. Mutations within the SHOX gene cause Léri-Weill dyschondrosteosis (LWD) and Langer mesomelic dysplasia (LD) as well as idiopathic short stature (ISS). Furthermore, haploinsufficiency of SHOX has also been implicated in Turner syndrome. SHOX has been shown to be a cell-type-specific transcriptional activator that localizes to the nucleus. The SHOX protein contains a central homeodomain that together with its transactivation domain regulates the transcription of its target sequences within the nucleus. The sequences for its nuclear localization have not been identified yet. Experimental characterization of SHOX-NLS by deletion mapping identified a non-classic type basic signal, AKCRK, in the recognition helix of the homeodomain. Fusion of this stretch of five amino acids to a cytoplasmic reporter protein resulted in its nuclear translocation. Functional analysis of a missense mutation R173C (C517T) affecting the identified SHOX-NLS in two families with LWS and LD showed that the mutated SHOX protein is unable to enter the nucleus. Conversely, we can demonstrate that insertion of the identified signal adjacent to the mutant site can restore its nuclear translocation. These results establish impairment of nuclear localization as a mechanistic basis for SHOX-related diseases.
Mammalian class E Vps proteins, SBP1 and mVps2/CHMP2A, interact with and regulate the function of an AAA-ATPase SKD1/Vps4B
Authors: Fujita Hideaki , Umezuki Yusuke , Imamura Kanako , Ishikawa Daisuke , Uchimura Seiko , Nara Atsuki , Yoshimori Tamotsu , Hayashizaki Yoshihide , Kawai Jun , Ishidoh Kazumi , Tanaka Yoshitaka , Himeno Masaru
Published: June 2004

SKD1 belongs to the AAA-ATPase family and is one of the mammalian class E Vps (vacuolar protein sorting) proteins. Previously we have reported that the overexpression of an ATPase activity-deficient form of SKD1 (suppressor of potassium transport growth defect), SKD1(E235Q), leads the perturbation of membrane transport through endosomes and lysosomes, however, the molecular mechanism behind the action of SKD1 is poorly understood. We have identified two SKD1-binding proteins, SBP1 and mVps2, by yeast two-hybrid screening and we assign them as mammalian class E Vps proteins. The primary sequence of SBP1 indicates 22.5% identity with that of Vta1p from Saccharomyces cerevisiae, which was recently identified as a novel class E Vps protein binding to Vps4p. In fact, SBP1 binds directly to SKD1 through its C-terminal region (198-309). Endogenous SBP1 is exclusively localized to cytosol, however it is redirected to an aberrant endosomal structure, the E235Q compartment, in the cells expressing SKD1(E235Q). The ATPase activity of SKD1 regulates both the membrane association of, and assembly of, a large hetero-oligomer protein complex, containing SBP1, which is potentially involved in membrane transport through endosomes and lysosomes. The N-terminal half (1-157) of human SBP1 is identical to lyst-interacting protein 5 and intriguingly, SKD1 ATPase activity significantly influences the membrane association of lyst protein. The SKD1-SBP1 complex, together with lyst protein, may function in endosomal membrane transport. A primary sequence of mVps2, a mouse homologue of human CHMP2A/BC-2, indicates 44.4% identity with Vps2p/Did4p/Chm2p from Saccharomyces cerevisiae. mVps2 also interacts with SKD1 and is localized to the E235Q compartment. Intriguingly, the N-terminal coiled-coil region of mVps2 is required for the formation of the E235Q compartment but not for binding to SKD1. We propose that both SBP1 and mVps2 regulate SKD1 function in mammalian cells.