bluuebunny/crossref_metadata_2025 huggingface dataset:
Osteoclastic Potential of Human CFU-GM: Biphasic Effect of GM-CSF
Authors: Hodge Jason M , Kirkland Mark A , Aitken Cathy J , Waugh Caryll M , Myers Damian E , Lopez Carolina M , Adams Brendan E , Nicholson Geoffrey C
Published: April 2006

Human osteoclasts can be efficiently generated in vitro from cord blood mononuclear cells and derived CFU-GM colonies. However, CFU-M colonies are poorly osteoclastogenic. Short-term (2–48 h) treatment with GM-CSF stimulates osteoclast formation by proliferating precursors, whereas longer exposure favors dendritic cell formation.

Introduction: Osteoclasts (OC) differentiate from cells of the myelomonocytic lineage under the influence of macrophage-colony stimulating factor (M-CSF) and RANKL. However, cells of this lineage can also differentiate to macrophages and dendritic cells (DC) depending on the cytokine environment. The aims of this study were to develop an efficient human osteoclastogenesis model and to investigate the roles of granulocyte macrophage-colony stimulating factor (GM-CSF) and M-CSF in human OC differentiation.

Materials and Methods: A human osteoclastogenesis model, using as precursors colony forming unit-granulocyte macrophage (CFU-GM) colonies generated from umbilical cord mononuclear cells cultured in methylcellulose with GM-CSF, interleukin (IL)–3 and stem cell factor (SCF), has been developed. CFU-GM, colony forming unit-macrophage (CFU-M), or mixed colonies were cultured on dentine with soluble RANKL (sRANKL) and human M-CSF with and without GM-CSF. Major endpoints were OC number, dentine resorption, and CD1a+ DC clusters.

Results: Osteoclast generation from CFU-GM and mixed colonies treated with M-CSF and sRANKL for 7–14 days was highly efficient, but CFU-M colonies were poorly osteoclastogenic under these conditions. Pretreatment of precursors with M-CSF for 7 or 14 days maintained the precursor pool, but OCs were smaller and resorption was reduced. The effect of GM-CSF treatment was biphasic, depending on the timing and duration of exposure. Short-term treatment (2–48 h) at the beginning of the culture stimulated cell proliferation and enhanced OC formation up to 100%, independent of sRANKL. Longer-term GM-CSF treatment in the presence of sRANKL, however, inhibited OC generation with the formation of extensive CD1a+ DC clusters, accompanied by downregulation of c-Fos mRNA. Delaying the addition of GM-CSF resulted in progressively less inhibition of osteoclastogenesis.

Conclusions: Human CFU-GM, but not CFU-M, progenitors have high osteoclastogenic potential. GM-CSF plays an important role in osteoclastogenesis and has a biphasic effect: Short-term treatment potentiates OC differentiation by proliferating precursors, but persistent exposure favors DC formation.
The Signaling Adapter Protein DAP12 Regulates Multinucleation During Osteoclast Development
Authors: Humphrey Mary Beth , Ogasawara Kouetsu , Yao Wei , Spusta Steven C , Daws Michael R , Lane Nancy E , Lanier Lewis L , Nakamura Mary C
Published: April 2006

Deficiency of the signaling adapter protein DAP12 is associated with bony abnormalities in both mice and humans. We identify specific DAP12-associated receptors expressed by osteoclasts and examine function of DAP12 in murine osteoclasts in vivo and in vitro. These data show a new role for DAP12 signaling in regulating formation of multinucleated osteoclasts.

Introduction: Osteoclasts are bone-resorbing cells derived from hematopoietic precursors in the myeloid lineage. In other myeloid cell types, the signaling adapter protein DAP12 transmits activating signals on ligation of a DAP12-associated receptor (DAR). The aim of this study was to clarify the role of DAP12 signaling during osteoclast development.

Materials and Methods: Osteoclasts from DAP12−/− or control mice were analyzed in vitro for morphology, function, and for osteoclast markers. DARs were identified in osteoclast cultures through reverse transcriptase-polymerase chain reaction (RT-PCR). Bone density of DAP12−/− and control mice were analyzed by microcomputed tomography. DAP12−/− osteoclasts were retrovirally reconstituted with DAP12. RAW264.7 cells were transfected with FLAG-tagged DAP12 or TREM2 and stimulated by anti-FLAG antibody during in vitro osteoclastogenesis.

Results: C57BL/6 DAP12-deficient mice have higher bone mass than C57BL/6 wildtype controls. We verified the presence of DAP12 in pre-osteoclasts and osteoclasts derived from C57BL/6 or the pre-osteoclast line RAW 264.7 and identified the DARs expressed. DAP12−/− osteoclasts developed in vitro with macrophage colony-stimulating factor (M-CSF) and RANKL formed only intensely TRACP+ mononuclear cells and failed to generate multinuclear osteoclasts. These mononuclear cells are functional osteoclast-like cells because, by RT-PCR, they express other osteoclast markers and generate resorption pits on dentine slices, although quantitative assessment of bone resorption shows decreased resorption by DAP12−/− osteoclasts compared with C57BL/6 osteoclasts. Restoration of DAP12 expression by retroviral transduction of DAP12−/− osteoclast precursors rescued in vitro osteoclast multinucleation. Direct stimulation of DAP12 expressed in RAW264.7 during in vitro osteoclastogenesis led to a marked increase in the number of TRACP+ multinucleated osteoclast-like cells formed.

Conclusion: Our studies indicate that stimulation of the DAP12 adapter protein plays a significant role in formation of multinuclear osteoclasts and that DAP12 and DARs likely participate in the regulation of bony remodeling.
Pamidronate Prevents Bone Loss and Decreased Bone Strength in Adult Female and Male Rats Fed an Isocaloric Low-Protein Diet
Authors: Mekraldi Samia , Toromanoff Anne , Rizzoli René , Ammann Patrick
Published: April 2006

Isocaloric dietary protein deficiency is associated with decreased BMD and bone strength as well as depressed somatotroph and gonadotroph axis. Inhibition of increased bone resorption by the bisphosphonate pamidronate in rats fed an isocaloric low-protein diet fully prevents bone loss and alteration of bone strength.

Introduction: Isocaloric dietary protein deficiency is associated with decreased BMD and bone strength as well as depressed somatotroph and gonadotroph axis. This negative bone balance is the consequence of increased bone resorption and decreased bone formation. Whether inhibition of bone resorption could prevent low-protein diet-induced bone loss and alteration of biomechanics is not known.

Materials and Methods: The effect of the bisphosphonate pamidronate was studied in 5.5-month-old female or 6-month-old male rats pair-fed a control (15% casein) or an isocaloric low-protein (2.5% casein) diet for 19 and 26 weeks, respectively. Pamidronate (0.6 mg/kg) was given subcutaneously 5 days/month for 4 months in female rats or for 5 months in male rats. BMD, microarchitecture, and bone strength were measured at the level of the proximal and midshaft tibia. Urinary deoxypyridinoline excretion, serum osteocalcin, and IGF-I were also measured.

Results: The increase in bone resorption in female rats (+100%) and in male rats (+33%) fed a low-protein diet was prevented by pamidronate treatment. The reduced osteocalcin levels observed in rats fed a low-protein diet were further decreased in both female (−34%) and male (−30%) rats treated with pamidronate. The bone turnover decrease induced by pamidronate prevented bone strength reduction, trabecular bone loss, microarchitecture, and BMD alterations induced by the isocaloric low-protein diet. Similar effects were observed at the level of the midshaft tibia. Significant decrease of plasma IGF-I was observed in rats fed a low-protein diet independently of the pamidronate treatment.

Conclusion: In conclusion, inhibition of increased bone resorption in rats fed an isocaloric low-protein diet fully prevents bone loss and alteration of bone strength.
Spontaneous Fractures in the Mouse Mutant sfx Are Caused by Deletion of the Gulonolactone Oxidase Gene, Causing Vitamin C Deficiency
Authors: Mohan Subburaman , Kapoor Anil , Singgih Anny , Zhang Zhang , Taylor Tim , Yu Hongrun , Chadwick Robert B , Chung Yoon-Suk , Donahue Leah Rae , Rosen Clifford , Crawford Grace C , Wergedal Jon , Baylink David J
Published: April 2006

Using a mouse mutant that fractures spontaneously and dies at a very young age, we identified that a deletion of the GULO gene, which is involved in the synthesis of vitamin C, is the cause of impaired osteoblast differentiation, reduced bone formation, and development of spontaneous fractures.

Introduction: A major public health problem worldwide, osteoporosis is a disease characterized by inadequate bone mass necessary for mechanical support, resulting in bone fracture. To identify the genetic basis for osteoporotic fractures, we used a mouse model that develops spontaneous fractures (sfx) at a very early age.

Materials and Methods: Skeletal phenotype of the sfx phenotype was evaluated by DXA using PIXImus instrumentation and by dynamic histomorphometry. The sfx gene was identified using various molecular genetic approaches, including fine mapping and sequencing of candidate genes, whole genome microarray, and PCR amplification of candidate genes using cDNA and genomic DNA as templates. Gene expression of selected candidate genes was performed using real-time PCR analysis. Osteoblast differentiation was measured by bone marrow stromal cell nodule assay.

Results: Femur and tibial BMD were reduced by 27% and 36%, respectively, in sfx mice at 5 weeks of age. Histomorphometric analyses of bones from sfx mice revealed that bone formation rate is reduced by >90% and is caused by impairment of differentiated functions of osteoblasts. The sfx gene was fine mapped to a 2 MB region containing ∼30 genes in chromosome 14. By using various molecular genetic approaches, we identified that deletion of the gulonolactone oxidase (GULO) gene, which is involved in the synthesis of ascorbic acid, is responsible for the sfx phenotype. We established that ascorbic acid deficiency caused by deletion of the GULO gene (38,146-bp region) contributes to fractures and premature death because the sfx phenotype can be corrected in vivo by treating sfx mice with ascorbic acid and because osteoblasts derived from sfx mice are only able to form mineralized nodules when treated with ascorbic acid. Treatment of bone marrow stromal cells derived from sfx/sfx mice in vitro with ascorbic acid increased expression levels of type I collagen, alkaline phosphatase, and osteocalcin several-fold.

Conclusion: The sfx is a mutation of the GULO gene, which leads to ascorbic acid deficiency, impaired osteoblast cell function, and fractures in affected mice. Based on these and other findings, we propose that ascorbic acid is essential for the maintenance of differentiated functions of osteoblasts and other cell types.
RANKL is a Marker and Mediator of Local and Systemic Bone Loss in Two Rat Models of Inflammatory Arthritis
Authors: Stolina Marina , Adamu Stephen , Ominsky Mike , Dwyer Denise , Asuncion Frank , Geng Zhaopo , Middleton Scot , Brown Heather , Pretorius Jim , Schett Georg , Bolon Brad , Feige Ulrich , Zack Debra , Kostenuik Paul J
Published: April 2006

RANKL is an essential mediator of bone erosions, but the role of RANKL in systemic bone loss had not been studied in arthritis. RANKL protein was increased in rat joint extracts and serum at the earliest stages of arthritis. Osteoprotegerin (OPG) treatment reversed local and systemic bone loss, suggesting that RANKL is both a marker and mediator of bone loss in arthritis.

Introduction: RANKL is well established as an essential mediator of bone erosions in inflammatory arthritis, but the role of RANKL in systemic bone loss in arthritis had not been studied. We hypothesized that serum RANKL could serve as both a mediator and as a novel biomarker for local and systemic bone loss in arthritis. We challenged this hypothesis in two established rat models of inflammatory arthritis. We sought to determine whether serum RANKL was elevated early in disease progression and whether RANKL suppression could prevent both local and systemic bone loss in these models.

Materials and Methods: Detailed time-course studies were conducted in animals with collagen-induced (CIA) or adjuvant-induced (AIA) arthritis to evaluate the onset and progression of inflammation (paw swelling), bone erosions, osteoclast numbers, and RANKL protein levels in arthritic joints and in serum. Additional CIA and AIA rats (n = 8/group) received placebo (PBS) or recombinant OPG (3 mg/kg three times weekly) for 10 days beginning 4 days after disease onset (first macroscopic evidence of hind paw erythema and edema) to assess the role of RANKL in local and systemic bone loss.

Results: RANKL protein was significantly elevated in the joints and serum of CIA and AIA rats within 1–2 days of disease onset. Increased RANKL levels were associated with local (hind paw) and systemic (vertebral) osteopenia in both models. The RANKL inhibitor OPG prevented local and systemic osteopenia in both models of established disease.

Conclusions: RANKL protein is significantly increased both locally and systemically during the earliest stages of inflammatory arthritis in rats, suggesting that serum RANKL might have prognostic value for bone erosions and systemic osteopenia in this condition. RANKL inhibition through OPG prevented local and systemic bone loss in these arthritis models, suggesting that RANKL inhibition is a promising new approach for treating bone loss in arthritis.
Rutin Inhibits Ovariectomy-Induced Osteopenia in Rats
Authors: Horcajada-Molteni Marie-Noëlle , Crespy Vanessa , Coxam Véronique , Davicco Marie-Jeanne , Rémésy Christian , Barlet Jean-Pierre
Published: April 2006

Several studies suggest that polyphenols might exert a protective effect against osteopenia. The present experiment was conducted to observe the effects of rutin (quercetin-3-O-glucose rhamnose) on bone metabolism in ovariectomized (OVX) rats. Thirty 3-month-old Wistar rats were used. Twenty were OVX while the 10 controls were sham-operated (SH). Among the 20 OVX, for 90 days after surgery 10 were fed the same synthetic diet as the SH or OVX ones, but 0. 25% rutin (OVX + R) was added. At necropsy, the decrease in uterine weight was not different in OVX and OVX + R rats. Ovariectomy also induced a significant decrease in both total and distal metaphyseal femoral mineral density, which was prevented by rutin consumption. Moreover, femoral failure load, which was not different in OVX and SH rats, was even higher in OVX + R rats than in OVX or SH rats. In the same way, on day 90, both urinary deoxypyridinoline (DPD) excretion (a marker for bone resorption) and calciuria were higher in OVX rats than in OVX + R or SH rats. Simultaneously, plasma osteocalcin (OC) concentration (a marker for osteoblastic activity) was higher in OVX + R rats than in SH rats. High-performance liquid chromatography (HPLC) profiles of plasma samples from OVX + R rats revealed that mean plasma concentration of active metabolites (quercetin and isorhamnetin) from rutin was 9.46 + 1 μM, whereas it was undetectable in SH and OVX rats. These results indicate that rutin (and/or its metabolites), which appeared devoid of any uterotrophic activity, inhibits ovariectomy-induced trabecular bone loss in rats, both by slowing down resorption and increasing osteoblastic activity.
On Exposure to Anorexia Nervosa, the Temporal Variation in Axial and Appendicular Skeletal Development Predisposes to Site-Specific Deficits in Bone Size and Density: A Cross-Sectional Study
Authors: Seeman Ego , Karlsson Magnus K. , Duan Yunbo
Published: April 2006

Skeletal development is heterogeneous. Throughout growth, bone size is more maturationally advanced than the mineral being accrued within its periosteal envelope; before puberty, appendicular growth is more rapid than axial growth; during puberty, appendicular growth slows and axial growth accelerates. We studied women with differing age of onset of anorexia nervosa to determine whether this temporal heterogeneity in growth predisposed to the development of deficits in bone size and volumetric bone mineral density (vBMD), which varied by site and severity depending on the age at which anorexia nervosa occurred. Bone size and vBMD of the third lumbar vertebra and femoral neck were measured using dual-energy X-ray absorptiometry in 210 women aged 21 years (range, 12–40 years) with anorexia nervosa. Results were expressed as age-specific SDs (mean ± SEM). Bone width depended on the age of onset of anorexia nervosa; when the onset of anorexia nervosa occurred (1) before 15 years of age, deficits in vertebral body and femoral neck width did not differ (−0.77 ± 0.27 SD and −0.55 ± 0.17 SD, respectively); (2) between 15 and 19 years of age, deficits in vertebral body width (−0.95 ± 0.16 SD) were three times the deficits in femoral neck width (−0.28 ± 0.14 SD; p < 0.05 comparing the deficits), (3) after 19 years of age, deficits in the vertebral body width (−0.49 ± 0.26 SD; p = 0.05) were half that in women with earlier onset of anorexia nervosa. No deficit in bone width was observed at the femoral neck. Deficits in vBMD at the vertebra and femoral neck were independent of the age of onset of anorexia nervosa but increased as the duration of anorexia nervosa increased, being about 0.5 SD lower at the vertebra than femoral neck. We infer that the maturational development of a region at the time of exposure to disease, and disease duration, determine the site, magnitude, and type of trait deficit in anorexia nervosa. Bone fragility due to reduced bone size and reduced vBMD in adulthood is partly established during growth.
Genetic Contribution to Bone Metabolism, Calcium Excretion, and Vitamin D and Parathyroid Hormone Regulation
Authors: Hunter D. , De Lange M. , Snieder H. , MacGregor A. J. , Swaminathan R. , Thakker R. V. , Spector T. D.
Published: April 2006

A classical twin study was performed to assess the relative contribution of genetic and environmental factors to bone metabolism, calcium homeostasis, and the hormones regulating them. It was examined further whether the genetic effect is menopause dependent. The subjects were 2136 adult twins (98.3% female): 384 monozygotic (MZ) and 684 dizygotic (DZ) twin pairs. The intraclass correlations were calculated, and maximum likelihood model fitting was used to estimate genetic and environmental variance components. The intraclass correlations for all of the variables assessed were higher in MZ twin pairs. The heritabilities (95% CIs) obtained from model fitting for hormones regulating bone metabolism and calcium homeostasis were parathyroid hormone (PTH), 60% (54–65%); 25-hydroxyvitamin D [25(OH)D]; 43% (28–57%), 1,25-hydroxyvitamin D [1,25(OH)], 65% (53–74%); and vitamin D binding protein 62% (56–66%). The heritabilities (95% CIs) for markers of bone formation also were assessed; bone-specific alkaline phosphatase (BSAP), 74% (67–80%), and osteocalcin, 29% (14–44%); marker of bone resorption deoxypyridinoline (DPD), 58% (52–64%); and measure of calcium homeostasis 24 h urine calcium, creatinine (Cr), 52% (41–61%). The magnitude of genetic influence differed with menopause for most variables. This study provides evidence for the importance of genetic factors in determining bone resorption and formation, calcium excretion, and the hormones regulating these processes. It shows for the first time a clear genetic effect on bone resorption in premenopausal women and the regulation of PTH, vitamin D metabolism, and calcium excretion. The genes controlling bone hormones and markers are likely to be useful therapeutic and diagnostic targets.
Exposure of KS483 Cells to Estrogen Enhances Osteogenesis and Inhibits Adipogenesis
Authors: Dang Z. C. , Van Bezooijen R. L. , Karperien M. , Papapoulos S. E. , Löwik C. W. G. M.
Published: April 2006

Osteoblasts and adipocytes arise from a common progenitor cell in bone marrow. Whether estrogen directly regulates the progenitor cells differentiating into osteoblasts or adipocytes remains unknown. Using a mouse clonal cell line KS483 cultured in charcoal-stripped fetal bovine serum (FBS), we showed that 17β-estradiol (E2) stimulates the differentiation of progenitor cells into osteoblasts and concurrently inhibits adipocyte formation in an estrogen receptor (ER)-dependent way. E2 increased alkaline phosphate (ALP) activity and nodule formation and stimulated messenger RNA (mRNA) expression of core-binding factor α-1 (Cbfa1), parathyroid hormone/parathyroid hormone-related protein receptors (PTH/PTHrP-Rs), and osteocalcin. In contrast, E2 decreased adipocyte numbers and down-regulated mRNA expression of peroxisome proliferator-activated receptor-γ (PPARγ)2, adipocyte protein 2 (aP2), and lipoprotein lipase (LPL). Furthermore, the reciprocal control of osteoblast and adipocyte differentiation by E2 was observed also in the presence of the adipogenic mixture of isobutylmethylxanthine, dexamethasone, and insulin. Immunohistochemical staining showed that ERα and ERβ were present in osteoblasts and adipocytes. A new mouse splice variant ERβ2 was identified, which differed in two amino acid residues from the rat isoform. E2 down-regulated mRNA expression of ERα, ERβ1, and ERβ2. The effects of E2 are not restricted to the KS483 cell line because similar results were obtained in mouse bone marrow cell cultures. Our results indicate that estrogen, in addition to stimulation of osteogenesis, inhibits adipogenesis, which might explain the clinical observations that estrogen-deficiency leads to an increase in adipocytes.
This Little Piggy Went to Market; This Little Piggy Stayed Home
Authors: Rich Ronald
Published: April 2006

Live U.S. hog market prices were unstable in the 1990s and crashed in the fall/winter of 1998 99. I situate the 1998 99 crash in the context of ongoing long‐term integration of a U.S. pork filiere and, using ethnographic data collected from Illinois contract hog producers, describe the role of market and production contracting in the unstable livehog markets of the 1990s. Production and market contracting in the 1990s linked large animal producers and large packers through new nonmarket channels. As a result, unstable markets and then the 1998 99 crash affected smaller, spot‐market‐selling hog producers more severely than it did larger producers. My analysis speaks to the structure of power in agricultural markets where contracts are used and warns against economistic understandings of markets that do not consider how different actors are related to commodity markets.
Centromere Locations and Associated Chromosome Rearrangements in Arabidopsis lyrata and A. thaliana
Authors: Kawabe Akira , Hansson Bengt , Hagenblad Jenny , Forrest Alan , Charlesworth Deborah
Published: April 2006

We analyzed linkage and chromosomal positions of genes in A. lyrata ssp. petraea that are located near the centromere (CEN) regions of A. thaliana, using at least two genes from the short and long arms of each chromosome. In our map, genes from all 10 A. thaliana chromosome arms are also tightly linked in A. lyrata. Genes from the regions on the two sides of CEN5 have distant map localizations in A. lyrata (genes on the A. thaliana short-arm genes are on linkage group AL6, and long-arm genes are on AL7), but genes from the other four A. thaliana centromere regions remain closely linked in A. lyrata. The observation of complete linkage between short- and long-arm centromere genes, but not between genes in other genome regions that are separated by similar physical distances, suggests that crossing-over frequencies near the A. lyrata ssp. petraea centromere regions are low, as in A. thaliana. Thus, the centromere positions appear to be conserved between A. thaliana and A. lyrata, even though three centromeres have been lost in A. thaliana, and the core satellite sequences in the two species are very different. We can now definitively identify the three centromeres that were eliminated in the fusions that formed the A. thaliana chromosomes. However, we cannot tell whether genes were lost along with these centromeres, because such genes are absent from the A. thaliana genome, which is the sole source of markers for our mapping.
Unusual DNA Structures Associated With Germline Genetic Activity in Caenorhabditis elegans
Authors: Fire Andrew , Alcazar Rosa , Tan Frederick
Published: April 2006

We describe a surprising long-range periodicity that underlies a substantial fraction of C. elegans genomic sequence. Extended segments (up to several hundred nucleotides) of the C. elegans genome show a strong bias toward occurrence of AA/TT dinucleotides along one face of the helix while little or no such constraint is evident on the opposite helical face. Segments with this characteristic periodicity are highly overrepresented in intron sequences and are associated with a large fraction of genes with known germline expression in C. elegans. In addition to altering the path and flexibility of DNA in vitro, sequences of this character have been shown by others to constrain DNA∷nucleosome interactions, potentially producing a structure that could resist the assembly of highly ordered (phased) nucleosome arrays that have been proposed as a precursor to heterochromatin. We propose a number of ways that the periodic occurrence of An/Tn clusters could reflect evolution and function of genes that express in the germ cell lineage of C. elegans.
A Genetic Suppressor of Two Dominant Temperature-Sensitive Lethal Proteasome Mutants of Drosophila melanogaster Is Itself a Mutated Proteasome Subunit Gene
Authors: Neuburger Peter J , Saville Kenneth J , Zeng Jue , Smyth Kerrie-Ann , Belote John M
Published: April 2006

Two dominant temperature-sensitive (DTS) lethal mutants of Drosophila melanogaster are Pros261 and Prosβ21, previously known as DTS5 and DTS7. Heterozygotes for either mutant die as pupae when raised at 29°, but are normally viable and fertile at 25°. Previous studies have identified these as missense mutations in the genes encoding the β6 and β2 subunits of the 20S proteasome, respectively. In an effort to isolate additional proteasome-related mutants a screen for dominant suppressors of Pros261 was carried out, resulting in the identification of Pros25SuDTS [originally called Su(DTS)], a missense mutation in the gene encoding the 20S proteasome α2 subunit. Pros25SuDTS acts in a dominant manner to rescue both Pros261 and Prosβ21 from their DTS lethal phenotypes. Using an in vivo protein degradation assay it was shown that this suppression occurs by counteracting the dominant-negative effect of the DTS mutant on proteasome activity. Pros25SuDTS is a recessive polyphasic lethal at ambient temperatures. The effects of these mutants on larval neuroblast mitosis were also examined. While Prosβ21 shows a modest increase in the number of defective mitotic figures, there were no defects seen with the other two mutants, other than slightly reduced mitotic indexes.
The Saccharomyces cerevisiae 14-3-3 Proteins Are Required for the G1/S Transition, Actin Cytoskeleton Organization and Cell Wall Integrity
Authors: Lottersberger Francisca , Panza Andrea , Lucchini Giovanna , Piatti Simonetta , Longhese Maria Pia
Published: April 2006

14-3-3 proteins are highly conserved polypeptides that participate in many biological processes by binding phosphorylated target proteins. The Saccharomyces cerevisiae BMH1 and BMH2 genes, whose concomitant deletion is lethal, encode two functionally redundant 14-3-3 isoforms. To gain insights into the essential function(s) shared by these proteins, we searched for high-dosage suppressors of the growth defects of temperature-sensitive bmh mutants. Both the protein kinase C1 (Pkc1) and its upstream regulators Wsc2 and Mid2 were found to act as high dosage suppressors of bmh mutants' temperature sensitivity, indicating a functional interaction between 14-3-3 and Pkc1. Consistent with a role of 14-3-3 proteins in Pkc1-dependent cellular processes, shift to the restrictive temperature of bmh mutants severely impaired initiation of DNA replication, polarization of the actin cytoskeleton, and budding, as well as cell wall integrity. Because Pkc1 acts in concert with the Swi4-Swi6 (SBF) transcriptional activator to control all these processes, the defective G1/S transition of bmh mutants might be linked to impaired SBF activity. Indeed, the levels of the G1 cyclin CLN2 transcripts, which are positively regulated by SBF, were dramatically reduced in bmh mutants. Remarkably, budding and DNA replication defects of bmh mutants were suppressed by CLN2 expression from an SBF-independent promoter, suggesting that 14-3-3 proteins might contribute to regulating the late G1 transcriptional program.
Ribosomal RNA Gene Silencing in Interpopulation Hybrids of Tigriopus californicus: Nucleolar Dominance in the Absence of Intergenic Spacer Subrepeats
Authors: Flowers Jonathan M , Burton Ronald S
Published: April 2006

A common feature of interspecific animal and plant hybrids is the uniparental silencing of ribosomal RNA gene transcription, or nucleolar dominance. A leading explanation for the genetic basis of nucleolar dominance in animal hybrids is the enhancer-imbalance model. The model proposes that limiting transcription factors are titrated by a greater number of enhancer-bearing subrepeat elements in the intergenic spacer (IGS) of the dominant cluster of genes. The importance of subrepeats for nucleolar dominance has repeatedly been supported in competition assays between Xenopus laevis and X. borealis minigene constructs injected into oocytes. However, a more general test of the importance of IGS subrepeats for nuclear dominance in vivo has not been conducted. In this report, rRNA gene expression was examined in interpopulation hybrids of the marine copepod Tigriopus californicus. This species offers a rare opportunity to test the role of IGS subrepeats in nucleolar dominance because the internal subrepeat structure, found in the IGS of virtually all animal and plant species, is absent in T. californicus. Our results clearly establish that nucleolar dominance occurs in F1 and F2 interpopulation hybrids of this species. In the F2 generation, nucleolar dominance appears to break down in some hybrids in a fashion that is inconsistent with a transcription factor titration model. These results are significant because they indicate that nucleolar dominance can be established and maintained without enhancer-bearing repeat elements in the IGS. This challenges the generality of the enhancer-imbalance model for nucleolar dominance and suggests that dominance of rRNA transcription in animals may be determined by epigenetic factors as has been established in plants.
Divergence With Gene Flow in Anopheles funestus From the Sudan Savanna of Burkina Faso, West Africa
Authors: Michel Andrew P , Grushko Olga , Guelbeogo Wamdaogo M , Lobo Neil F , Sagnon N'Fale , Costantini Carlo , Besansky Nora J
Published: April 2006

Anopheles funestus is a major vector of malaria across Africa. Understanding its complex and nonequilibrium population genetic structure is an important challenge that must be overcome before vector populations can be successfully perturbed for malaria control. Here we examine the role of chromosomal inversions in structuring genetic variation and facilitating divergence in Burkina Faso, West Africa, where two incipient species (chromosomal forms) of A. funestus, defined principally by rearrangements of chromosome 3R, have been hypothesized. Sampling across an ∼300-km east–west transect largely contained within the Sudan–Savanna ecoclimatic zone, we analyzed chromosomal inversions, 16 microsatellite loci distributed genomewide, and 834 bp of the mtDNA ND5 gene. Both molecular markers revealed high genetic diversity, nearly all of which was accounted for by within-population differences among individuals, owing to recent population expansion. Across the study area there was no correlation between genetic and geographic distance. Significant genetic differentiation found between chromosomal forms on the basis of microsatellites was not genomewide but could be explained by chromosome 3R alone on the basis of loci inside and near inversions. These data are not compatible with complete reproductive isolation but are consistent with differential introgression and sympatric divergence between the chromosomal forms, facilitated by chromosome 3R inversions.
Art, Science, and Humor: The Study of Humorous Experience at the Intersection between Psychology and the Art World
Authors: Bonaiuto Paolo
Published: April 2006

A theoretical model of humorous experience, organically interlinking different components (Bonaiuto & Giannini, 1987, 2003) is presented. In particular, we studied the world of illustrations, which are easy to manipulate through systematic collections and/or experimental modifications. Essential conditions found for humor consist of the perceptibility of illustrations' configurations based on “completion” skills favored by a beholder's dispositions. Moreover, necessary conditions include the presence of one or more paradoxes, i.e., contradiction of expectations (motivations, habits, and mental schemata), and other conflicts, with ambivalence between conflict repulsion vs. conflict attraction and protection. From these conflicts, the dynamics move toward humor only if there are conditions for a feeling of superiority and relative emotional detachment. The technical contrivances used by visual artists to guarantee these ingredients in the average beholder are listed. Summarized are phenomenological analyses and experimental investigations that show the role of rounded and stylized vs. angulated detailed shapes, and playful-reassuring vs. alarming-serious colors, in facilitating humor through the avoidance of conflict overloading and excessive emotional involvement. The use of humor in scientific demonstrations is described with reference to studies on serial reproduction. Examples from art works of different periods show how the conditions for humor have been intuitively and effectively taken into account even by famous artists such as Leonardo, Michelangelo, Picasso, Magritte, and by contemporary illustrators. Parodies of famous paintings and humorous illustrations on current visual art expectations of the ordinary beholder are included in the article. Also cited are cases of kitsch productions and the nature of humor in disciplines besides the visual arts, such as literature and the performing arts. The high frequency of humor elicited by art works is explained as a correlate of the higher levels of tolerance for conflict and incongruity characterizing artists' and their followers' personalities.
The Semantic Representation of Actresses and Actors
Authors: Marques J. Frederico
Published: April 2006

The present study explores the structure of moviegoers knowledge about actors and actresses considered as categories of semantic knowledge. For this purpose, participants generated either names of actors or names of actresses and, in a second phase of the experiment, judged their responses in terms of aesthetic preference and frequency of instantiation. Both categories exhibited a graded structure in terms of typicality but while frequency of instantiation was the strongest response determinant for actresses, aesthetic preference was the strongest response determinant for actors. Moviegoing frequency was positively related to the number of names produced for actors but not for actresses. Main conclusions suggest that actresses and actors are relevant semantic categories for moviegoers. Possible factors for differences between the two categories are also discussed.
The Magical Number Five in Art Appreciation
Authors: van Meel-Jansen Annelies
Published: April 2006

To describe differences in art appreciation between children of different ages, between children and adults, and between adults with different educational backgrounds, five components of aesthetic judgment were defined. These were named: “Attraction,” “Representation and realism,” “Emotional expression,” “Style and form,” and “Interpretation.” In a review of six studies with participants ranging from primary and secondary school children to various adult groups, it was investigated in which amount the five components characterized each group. For that purpose, explanations for art preferences in these studies were analyzed. The results indicate that individuals or groups can be characterized with respect to their art appreciation as showing a particular “profile” of the five aesthetic components. Also, it seems justified to distinguish one stage-like transition in aesthetic development, in early adolescence. This is seen as a transition from a chiefly semantic (content-related) to a mainly aesthetic (style-, emotion-, and interpretation-related) orientation.
Fostering authentic relationships in the transformative classroom
Authors: Cranton Patricia
Published: April 2006

Authentic relationships between teacher and student form a central process in transformative learning in the classroom. Based on research and theory, this chapter provides practical strategies for educators looking to foster authentic relationships.
Engaging emotions in adult learning: A jungian perspective on emotion and transformative learning
Authors: Dirkx John M.
Published: April 2006

Emotion‐laden images that arise within adult learning provide a symbolic language for helping teachers and learners understand and facilitate transformation at both the individual and group levels.
Transformational teaching and the practices of black women adult educators
Authors: Johnson‐Bailey Juanita , Alfred Mary V.
Published: April 2006

This chapter uses the classroom experiences of two black women professors as a lens to examine how transformational theory affects learning and teaching. It also explores the ways in which dimensions of power have an impact on student‐teacher interactions.
Ethical demands of transformative learning
Authors: Ettling Dorothy
Published: April 2006

This chapter addresses ethical issues that can arise for an educator who ascribes to and practices from the theoretical perspective of transformative learning.
Familial thoracic aortic aneurysms and dissections: Three families with early‐onset ascending and descending aortic dissections in women
Authors: Tran‐Fadulu Van , Chen Julia H. , Lemuth Danielle , Neichoy Bo T. , Yuan Jiuhong , Gomes Nathan , Sparks Elizabeth , Kramer Larry A. , Guo Dongchuan , Pannu Hariyadarshi , Braverman Alan C. , Shete Sanjay , Milewicz Dianna M.
Published: April 2006

Ascending thoracic aortic aneurysms leading to type A dissections can be inherited in an autosomal dominant manner with variable age of onset and decreased penetrance, primarily in women. Three families are described with autosomal dominant inheritance of either ascending aortic aneurysms leading to type A dissections or type B dissections, and a young age of onset of aortic dissections in both men and women. Pedigree analysis suggests that a de novo mutation is responsible for the disease in one family. The discordant age of onset of aortic disease in a monozygotic twin pair in a different family indicates that environmental or stochastic factors may influence the variable expression of disease. Genetic analysis of one family excluded linkage to known loci for TAAD (TAAD1, TAAD2, FAA1, or FBN1) and sequence analysis failed to identify mutations in TGFBR2, the gene encoding transforming growth factor beta receptor type II. Thus, a novel unidentified loci may be responsible for the phenotype in these three families. © 2006 Wiley‐Liss, Inc.
Formkontrolle von Halbleiter‐ und Metalloxid‐Nanokristallen durch nichthydrolytische Kolloidverfahren
Authors: Jun Young‐wook , Choi Jin‐sil , Cheon Jinwoo
Published: April 2006

Anorganische Nanokristalle mit gezielt präparierten Formen und Abmessungen haben einzigartige, formabhängige Eigenschaften und sind als Bausteine zur Herstellung von Nanofunktionseinheiten von großem Interesse. In diesem Aufsatz fassen wir die jüngsten Entwicklungen bei der Formkontrolle von kolloidalen Nanokristallen zusammen, wobei der Schwerpunkt auf den wissenschaftlich und technologisch wichtigen Halbleiter‐ und Metalloxid‐Nanokristallen liegt, die sich durch nichthydrolytische Synthesemethoden erhalten lassen. Viele ungewöhnliche Strukturmotive wurden entdeckt, darunter Polyeder, Stäbchen und Drähte, Scheiben und Prismen sowie komplexere Formen wie verzweigte Stäbchen, Sterne, anorganische Dendrimere und Hanteln. Der gegenwärtig favorisierte Mechanismus der Formkontrolle wird vorgestellt, ebenso wie richtungsweisende Studien zur Anordnung formkontrollierter Nanokristalle zu geordneten Übergittern und zur Herstellung hochentwickelter Prototypen von Nanofunktionseinheiten.
Shape Control of Semiconductor and Metal Oxide Nanocrystals through Nonhydrolytic Colloidal Routes
Authors: Jun Young‐wook , Choi Jin‐sil , Cheon Jinwoo
Published: April 2006

Inorganic nanocrystals with tailored geometries exhibit unique shape‐dependent phenomena and subsequent utilization of them as building blocks for the fabrication of nanodevices is of significant interest. Herein, we review the recent developments in the shape control of colloidal nanocrystals with a focus on the scientifically and technologically important semiconductor and metal oxide nanocrystals obtained by nonhydrolytic synthetic methods. Many structurally unprecedented motifs have been discovered including polyhedrons, rods and wires, plates and prisms, and other advanced shapes such as branched rods, stars, inorganic dendrites, and dumbbells. The currently proposed shape‐guiding mechanisms are presented and the important pioneering studies on the assembly of shape‐controlled nanocrystals into ordered superlattices and the fabrication of prototype advanced nanodevices are discussed.
Cover Picture: Proteolytic Actuation of Nanoparticle Self‐Assembly (Angew. Chem. Int. Ed. 19/2006)
Authors: Harris Todd J. , von Maltzahn Geoffrey , Derfus Austin M. , Ruoslahti Erkki , Bhatia Sangeeta N.
Published: April 2006

Sterically shielded …︁…︁ nanoparticles diffuse freely in solution and biological fluids until proteases expressed by cancer cells trigger them to self‐assemble. In their Communication on page 3161ff., S. N. Bhatia and co‐workers show that complimentary Fe3O4 nanoparticle binding is inhibited by the attachment of protease‐cleavable polymers. Cleavage of these polymers triggers “latent” nanoparticles to form multimeric assemblies with emergent properties.
Study on morphology of high impact polypropylene prepared by in situ blending
Authors: Jiang Tao , Chen Hongxia , Ning Yingnan , Kuang Dongting , Qu Guangmiao
Published: April 2006

High impact polypropylene (HIPP) was prepared by in situ blending of isotactic polypropylene and ethylene–propylene rubber (EPR) with spherical Ziegler–Natta catalyst. Morphology and pore characteristics of such HIPP were investigated by scanning electron microscope, atomic force microscopy, and mercury intrusion. Amorphous phase was removed from polypropylene matrix and characterized by 13C NMR spectrum. It was found that the EPR prepared in this manner contained variable composition polymer chains with a distribution of ethylene and propylene sequence lengths. Final products of HIPP were free flowing, spherical granules. There were small pores in HIPP, which seemed not to be filled up, and could be determined by mercury intrusion even when the content of rubber was up to 24 wt %. Homopolypropylene with pore diameter between 100 and 10,000 nm was suitable for EPR to fill in during ethylene–propylene copolymerization. The block copolymer fractions act as a compatilizer between matrix and EPR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1386–1390, 2006
Competitive transport of hydrochloric acid and zinc chloride through polymeric anion‐exchange membrane
Authors: Palatý Zdeněk , Žáková Alena
Published: April 2006

Competitive transport of hydrochloric acid and zinc chloride has been investigated in a two‐compartment mixed cell with an anion‐exchange membrane Neosepta‐AFN developed and produced by Tokuyama Soda Co. These experiments have proved that hydrochloric acid permeates well through the membrane used but, on the other hand, zinc chloride is not effectively rejected. The flux of zinc chloride has been found to be increasing with increasing acid and salt concentrations. Furthermore, it has been found that it is approximately one order of magnitude higher than that found in the case of simultaneous transport of sulfuric acid and zinc sulfate through the same membrane. The further calculations concerning the ionic equilibria with sorption isotherms for the HClZnCl2 system, which have been measured experimentally, have revealed that high flux of ZnCl2 is due to the fact that a considerable amount of zinc chloride in the membrane is in the form of ZnCl3− complex, which is relatively small and passes well through this membrane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1391–1397, 2006
Swelling studies in electrochemically prepared acrylamide/N,N′ methylene bisacrylamide gels
Authors: Yildiz Gülcemal , Paril Ahmet , Giz Ahmet , Çatalgil‐Giz Huceste
Published: April 2006

Acrylamide/N,N′ methylene bisacrylamide gels were prepared at different voltages electrochemically. The dependence of the swelling properties on the preparation voltage was investigated. A set of gel samples was swollen as prepared and another set was swollen after being dried to constant weight. Swelling versus time curves were all in stretched exponential form, rather than pure exponential form, indicating that the gels are of heterogeneous nature. Maximum swelling increased with the preparation voltage in both gel types. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1398–1401, 2006
Systemic lupus erythematosus in a multiethnic US cohort: Clinical features, course, and outcome in patients with late‐onset disease
Authors: Bertoli Ana M. , Alarcón Graciela S. , Calvo‐Alén Jaime , Fernández Mónica , Vilá Luis M. , Reveille John D.
Published: April 2006

Objective

To examine the clinical differences and the type and extent of organ damage in late‐ versus early‐onset systemic lupus erythematosus (SLE).

Methods

A nested case–control study was performed in the context of LUMINA (LUpus in MInorities, NAture versus nurture), a large, longitudinal, multiethnic cohort. Patients who developed SLE at or after the age of 50 years were considered cases. Two controls (patients who developed SLE at age ≤49 years) per case, matched for sex and disease duration, were randomly chosen. Selected baseline socioeconomic/demographic, behavioral, and psychological features, self‐reported quality of life, and cumulative clinical data (clinical manifestations, laboratory data, disease activity, damage, and mortality) were compared between cases and controls. Multivariable analyses with late‐onset lupus, damage accrual, and mortality as dependent variables were then performed.

Results

Two hundred seventeen patients were studied. Of them, 73 were cases. Cases were more likely to have neurologic involvement, arterial thrombotic events, osteoporosis, and hypertriglyceridemia, while renal involvement and anti‐Sm antibodies were less frequent. Disease activity at baseline was lower among cases. Cases also exhibited more cardiovascular and ocular damage. Late‐onset lupus was an independent predictor of damage accrual (t‐test = 2.23, P = 0.028), any damage at last visit (odds ratio [OR] 23.32, 95% confidence interval [95% CI] 3.98–141.56) (P < 0.001), and mortality (OR 10.74, 95% CI 3.07–37.56) (P < 0.001).

Conclusion

Patients with late‐onset lupus exhibit distinct clinical features. Although disease activity tends to be lower in these patients, they tend to accrue more damage and experience higher mortality than patients with early‐onset lupus. These findings probably reflect the contribution exerted by other comorbid conditions in the overall impact of lupus in these patients.