bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for genomic imprinting in unisexual triploid hybrid frogs
Authors: Tunner Heinz
Published: July 2002

The hybridogenetic hybrid R. esculenta arose through hybridization between R. ridibunda and R. lessonae. Usually hybrids are diploid. In some populations, however, they are triploid, with one genome from R. ridibunda and two genomes from R. lessonae (LLR-genotype). These triploids live with and mate with R. ridibunda. Thus, hybrids and R. ridibunda are sexual competitors. I studied the influence of the additional lessonae genome (dosage effect) on the morphology, biology and the electrophoretic pattern of two polymorphic proteins of triploid hybrids. The two lessonae genomes are not expressed according to a simple dose effect. Genetic information of the lessonae genome is obviously switched off because it would increase the dissimilarity between triploids and R. ridibunda, the parental species upon which reproduction of hybrids depends. Imprinting can account for the observed unusual pattern of inheritance.
Breeding biology of the leaf frog, Phyllomedusa boliviana (Anura, Hylidae)
Authors: Vaira Marcos
Published: July 2002

Spawning behavior, clutch characteristics, and egg deposition site of the leaf frog, Phyllomedusa boliviana, were described at an artificial pool in a subtropical montane forest of Jujuy, Argentina. Mating behavior was observed during the wet season (November-January) in unmarked frogs on eight separate occasions. A prespawning period characterized by repeated struggles between amplexed and unamplexed males for possession of the female was observed lasting from 2 to 4 hours. The entire sequence of leaf folding and extrusion of both eggless capsules and eggs occurred in less than 30 minutes. After the pair separated, the female remained at the top of the leaf nest extruding a mass of eggless capsules leaving the nest 22-70 min later. Egg masses were deposited every month of the breeding season on almost every plant species at the pool perimeter, but P.boliviana appeared to choose certain species. Deposition heights between 5 and 35 cm occurred most frequently and heights above 100 cm were uncommon. The results of this study indicate that P. boliviana is able to breed in artificial ponds, information that could be useful in the management of altered habitats.
RISK-TAKING BY THREESPINE STICKLEBACK (GASTEROSTEUS ACULEATUS) PELVIC PHENOTYPES: DOES MORPHOLOGY PREDICT BEHAVIOUR?
Authors: Grand Tamara
Published: July 2002

The relationship between risk-taking behaviour and anti-predator morphology was studied in benthic threespine stickleback fish (Gasterosteus aculeatus) from Paxton and Priest Lakes on Texada Island, British Columbia, Canada. In general, Priest Lake benthics possess complete pelvic girdles and numerous lateral plates. In contrast, Paxton Lake benthics exhibit an apparent polymorphism in anti-predator morphology; some individuals possess complete pelvic girdles while others lack them entirely. Although phenotypes tended to differ in their willingness to risk exposure to a trout predator while foraging, the predicted positive relationship between risk-taking behaviour and anti-predator morphology was not observed. While 'girdled' Paxton individuals were more willing to forage in the vicinity of the predator than 'girdleless' Paxton individuals, the more heavily armoured Priest fish were intermediate in their risk-taking behaviour. These results suggest that the relationship between risktaking behaviour and anti-predator morphology may be influenced by differences between phenotypes in predation regime and life history.
MALE MATING SUCCESS AND FEMALE PREFERENCE FOR MULTIPLE TRAITS IN THE TWOLINE PUPFISH (CYPRINODON BIFASCIATUS)
Authors: Itzkowitz Murray , Baird David , Ludlow Anna
Published: July 2002

Summary Using the twoline pupfish (Cyprinodon bifasciatus), a species with a resource-based polygynous breeding system, we examined male mating success in the wild, and we experimentally investigated effects of male body size and substrate type on female association patterns in the laboratory. Our purpose was to (a) identify the traits contributing to male reproductive success in the field, (b) measure preferences for each trait independently in the laboratory, and (c) determine the relative importance of each trait. Field observations revealed that substrate type was the main determinant of male reproductive success: males defending territories on rocks mated significantly more often than males defending territories on silt or sand. Laboratory experiments supported the field data, and revealed that the female preference for substrate type was independent of male body size effects. When given a choice between two males matched for size but differing in the type of substrates they were defending, females preferred the male on the rocky substrate over the male on the sandy substrate. Laboratory experiments also revealed a female preference for larger males when substrate type was held constant. Finally, when females were presented with a choice between a large male on a sandy substrate and a small male on a rocky substrate, no clear preference emerged. We provide several interpretations for this result, and we argue that both traits may be strong predictors of the male's competitive ability.
Variation in Number of Elements in the Perch-Coo Vocalization of the Collared Dove (Streptopelia Decaocto) and What it May Tell About the Sender
Authors: Ballintijn Mechteld , Cate Carel Ten
Published: July 2002

We examined the variation in element number in the perch-coo of the collared dove and its possible causes. A negative correlation was present between body weight of an individual and the occurrence of two instead of three elements in one coo. In birds showing them, coos consisting of two elements were more common towards the end of longer coo bouts. An analysis of the spectro-temporal structure of three-element coos showed a decrease in duration of the third element in long coo-bouts. This, and a comparison of the spectrotemporal parameters of three- and two-element coos, suggests that reduction in element number is due to replacing the third element by silence. Possible causes might be muscular exhaustion and insufficient respiration, which might explain why two element coos are more common in lighter, and presumably weaker, birds. However, declining motivation cannot be ruled out as an alternative explanation. Four-element coos were produced by one male. Their occurrence was not linked to specific positions in a bout. The spectro-temporal structure of these coos suggest that they result from a programming error causing a 'stutter' to proceed a normal coo. Two different mechanisms may thus underlie variation in element number in the collared dove.
FISSION, FUSION AND NONRANDOM ASSOCIATIONS IN FEMALE BECHSTEIN'S BATS (MYOTIS BECHSTEINII)
Authors: Kerth Gerald , Konig Barbara
Published: July 2002

Maternity colonies of the Bechstein's bat (Myotis bechsteinii) are socially closed units that frequently split into subgroups which occupy different roosts. We analysed the social structure of one colony over three years in the field and quantified associations among pairs of females by using three association indices. Colony members exhibited marked mixing, although individual composition of subgroups was not completely random. Females associated according to the reproductive status, with lactating females preferentially roosting together. Relatedness, determined from 5 nuclear and 1 mitochondrial microsatellite, had no consistent influence on the degree of association. In combination, the indices allowed for the interpretation that nonrandom associations occur even in the absence of shared roost and group size preferences. High individual associations among reproducing female Bechstein's bats might reflect the importance of cooperation in maternity colonies. The frequent fission and fusion of subgroups suggests a flexible reaction of Bechstein's bats according to enviromental conditions.
ON SEX-SPECIFIC DISPERSAL AND MATING TACTICS IN THE COMMON EIDER SOMATERIA MOLLISSIMA AS INFERRED FROM THE GENETIC STRUCTURE OF BREEDING COLONIES
Authors: Tiedemann Ralph , Von Kistowski Kristin G. , Noer Henning
Published: July 2002

The common eider is a colony breeding seaduck with extreme female philopatry. Molecular genetic techniques (mtDNA sequencing and microsatellite analysis) were applied on Baltic eiders to infer sex-specific dispersal and mating tactics among breeding colonies with different seasonal migration behaviour, i.e. sedentary, short distance migratory, and long distance migratory. MtDNA patterns show pronounced differentiation among colonies in maternally inherited traits. The estimated number of exchanged females per generation was 1.0-1.4. Smaller colonies showed a lower level of genetic variation in mtDNA. Microsatellite patterns suggest male-mediated gene flow to be sufficient for preventing inbreeding even in smaller colonies. However, though eiders of different geographic origin mix on wintering grounds, where mating occurs, mate choice is not random: The bias towards mates of similar geographic origin might reflect a different time of arrival at the wintering ground for eiders of different origin, together with the adaptive significance of early pair formation.
TWO NEW SPECIES OF THE SUBFAMILY CANDONINAE (OSTRACODA) FROM MONTENEGRO (SE EUROPE)
Authors: Karanovic Ivana , Petkovski Trajan
Published: July 2002

Two new species of the subfamily Candoninae from Montenegro are described in the present paper. Pseudocandona regisnikolai n. sp. is an epigean species characterized by the absence of male bristles. The second new species, Candonopsis mareza n. sp., is a hypogean species, collected in a spring near Podgorica. This species has a triangular form of carapace. Deux nouvelles especes de la sous-famille des Candoninae provenant du Montenegro sont decrites dans le present article. Pseudocandona regisnikolai n. sp. est une espece epigee caracterisee par l'absence de soies chez le male. La seconde espece nouvelle, Candonopsis mareza n. sp. est hypogee, recueillie dans une source pres de Podgorica. Cette espece a une carapace de forme triangulaire.
Chemical and biological induction of resistance to the clover cyst nematode (Heterodera trifolii) in white clover (Trifolium repens)
Authors: Scott Eileen , Kempster Valerie , Davies Kerrie
Published: July 2002

Possible induction of resistance to the clover cyst nematode, Heterodera trifolii, in white clover, Trifolium repens, by application of two chemical inducers and of soil-borne Pseudomonas-like spp. and Bacillus cereus was investigated. Salicylic acid and benzo(1,2,3)thiadiazole-7-carbothioic acid-S-methyl ester, applied as a root drench in growth cabinet soil bioassays, affected development of H. trifolii in cvs Haifa and Grasslands Huia. Treatments reduced fecundity of the nematodes, increasing the proportions of distorted females and of females with fewer eggs compared to water-treated controls. Application of pectinolytic fluorescent pseudomonad strains P29 and P80, and B. cereus strain B1, induced a response similar to that resulting from the chemical induction. Both live and dead cells of P29, but not cell-free culture filtrate, induced these effects on H. trifolii. A non-pectinolytic, fluorescent pseudomonad, strain P37, had no effect. From the nature of the responses, it is concluded that the effects of both the chemical and bacterial agents have similarities to resistance. From the timing of applications and known properties of both agents, these effects seem similar to induced systemic resistance.
Microflora of Meloidogyne egg masses: species composition, population density and effect on the biocontrol agent Verticillium chlamydosporium (Goddard)
Authors: Kok C.J.(Hans) , Papert Artemis , Bok-A-Bin C.B.(Chula)
Published: July 2002

Egg masses of Meloidogyne fallax from tomato and potato growing in soil from a nematode suppressive and a nonsuppressive field sustained bacterial population densities two to three orders of magnitude higher than those of the rhizosphere soil. BIOLOG metabolic profiling identified 16 bacterial species from egg masses. Results further indicated 20 species not listed in the BIOLOG database. 122 isolates of bacteria and 19 isolates of fungi from M. fallax or M. hapla were tested for in vitro antagonism against the nematode egg parasitic fungus Verticillium chlamydosporium: 23% of the bacteria and 74% of the fungi showed antagonistic activity. Pseudomonads showed an overall stronger antagonistic activity than the other bacteria. Our conclusions are that Meloidogyne egg masses are a densely populated microbial niche and that their microflora may well be an important factor in determining the success of nematode antagonists. However, we could not find a relationship between the egg mass microflora and differences in soil suppressiveness between the sample sites.
The Baumwollfrage: Cotton Colonialism in German East Africa
Authors: Sunseri Thaddeus
Published: July 2002

In March 1907, as newly-appointed Colonial Minister Bernhard Dernburg prepared to visit German East Africa to assess the colony's potential for economic development following the recent Maji Maji rebellion, requests poured in from businessmen seeking to accompany the minister. Prominent among the select few allowed on the trip were representatives of the German textile industry interested in founding cotton plantations in the colony. Among those participants was Gustav Hertle, director of the Leipzig Cotton Spinnery, the largest cotton spinner in Germany, who had long expressed interest in colonial cotton production. Following the trip the Leipzig Spinnery went on to acquire land in German East Africa, where it founded one of the biggest cotton plantations in the colony. Other textile industrialists who accompanied Dernburg also established cotton plantations in East Africa.
Bentonite and double hydroxides as emulsifying agents
Authors: Abend S. , Lagaly G.
Published: July 2002

The use of solid-laden emulsions (Pickering emulsions) provides an interesting alternative to normal emulsions because the need for organic surfactants is removed or reduced. Combination of a bentonite with a layered double hydroxide represents an effective emulsifying system and provides high stability against coalescence. Solid contents as low as 0.1% (w/w, related to the total mass of the emulsion) are sufficient to prepare very stable O/W emulsions; the mass ratio of hydroxide/bentonite is not critical but should vary between 0.25 and 4 (corresponding to mass fractions of the hydroxide between χ = 0.2 and 0.8). With large hydroxide contents, stabilization is mainly caused by the envelope of hydroxide particles around the oil droplets. This shell provides a mechanical barrier against coalescence, typical of Pickering emulsions described so far. Addition of increasing amounts of bentonite provides an additional stabilization by building-up a threedimensional network consisting of both types of particles spanning the coherent phase. A high storage modulus at mass fractions of the hydroxide between 0.2 and 0.8 indicates high flexibility for the inorganic framework which is considered to be an important factor in the high stability of these emulsions.
Influence of counterion species on the dehydroxylation of Ca2+-, Mg2+-, Na+- and K+-exchanged Wyoming montmorillonite
Authors: Bray H. J. , Redfern S. A. T.
Published: July 2002

The dehydroxylation of Ca-, K-, Mg- and Na-saturated Wyoming montmorillonite has been studied by thermogravimetry (TG), infrared (IR) spectroscopy and X-ray diffraction (XRD). Samples saturated with either Ca2+ or Mg2+ show a predominantly diffusion-controlled reaction step, whereas Wyoming montmorillonite with Na+ and K+ in the interlayer exhibit control closer to first order. The activation energy of dehydroxylation is not significantly correlated to the type of interlayer cation present, in turn demonstrating that the role of vacancy location in the octahedral sheet is more significant a control on dehydroxylation.
Pressure buffering in a diamond anvil cell
Authors: Arlt T. , Angel R. J.
Published: July 2002

The clinopyroxenes kanoite and spodumene were studied by single-crystal X-ray diffraction in a diamond anvil cell (DAC) at room temperature. At the displacive phase transitions between the C2/c and P21/c polymorphs both phases coexist within the same crystal. In this two-phase region the pressure in the DAC remains constant. The experimental results demonstrate that pressure buffering at first-order phase transitions can occur in the DAC.
Crystal structure of Na4[Cu4O2(SO4)4]·MeCl (Me: Na, Cu, ☐) – the synthetic Na-analogue of piypite (caratiite)
Authors: Kahlenberg V. , Piotrowski A. , Giester G.
Published: July 2002

The crystal structure of Na4[Cu4O2(SO4)4] MeCl (Me: Na,Cu,☐) has been solved by direct methods and refined to R1 = 0.028 using 2466 independent reflections. The compound is tetragonal with space group P4/n, a = 18.451(1)Å, c = 4.9520(2)Å, Z = 4. The two main building units running parallel to the c-axis comprise: (1) slabs containing SO4 and OCu4 tetrahedra; and (2) chains of corner sharing Me(Cl,O)6 octahedra. The displacement ellipsoids of the atoms occupying the Me sites and of the Cl ions indicate a short-range static disorder. Copper in the slabs exhibits a (4+1) coordination. Both elements form a tunnel structure in which additional Na atoms are incorporated for charge compensation. The structure is closely related to the mineral piypite (K4Cu4O2(SO4)4 MeCl (Me: Na,Cu,☐)): . Furthermore, the structure has a pronounced pseudo-translational symmetry: apart from some of the oxygen sites, all of the nineteen crystallographically distinct positions are related by a pseudo F centring.
Determination of six new polytypes in parisite-(Ce) by means of high resolution electron microscopy
Authors: Dawei Meng , Xiuling Wu , Tao Mou , Douxing Li
Published: July 2002

The ultrastructures of parisite-(Ce) from a rare-earth mineral deposit of Sichuan Province, southwest China, have been observed and investigated by selected area electron diffraction (SAED) and high resolution electron microscopy (HREM). Six new polytypes 4H, 10H, 16H, 18R, 24R and 30R were determined in parisite-(Ce), as were their crystal structure types, subcell (a′c‴, a′c″, a′c′) and supercell (ac) parameters, reflection conditions, polytype features and probable space groups. The HREM studies revealed the complex polytypism in parisite-(Ce) whereby the six new polytypes, formed by long-period ordered stacking, always coexist with the common polytype parisite-(Ce)-6R by syntaxy and thus constitute the complex microstructural ‘syntactic polycrystals’, the host of which is the polytype parisite-(Ce)-6R.
Rapid exsolution behaviour in the bornite–digenite series, and implications
for natural ore assemblages
Authors: Grguric B. A. , Putnis A.
Published: July 2002

Intermediate compositions along the bornite–digenite join exsolve during
quenching from above-solvus temperatures. This involves vacancy clustering and
cation ordering processes, and is facilitated by fast cation diffusion rates in
the presence of a large (10–25%) metal vacancy population. Samples of six
different compositions across the
bornite–Cu9S5 join, synthesised from
component elements in sealed quartz capsules, were water-quenched from 600°C and
analysed using high-resolution neutron powder diffraction (HRPD). Time-of-flight
spectra measured at room temperature showed all intermediate compositions had
exsolved into mixtures of bornite and low digenite with a
5.0a superstructure. No evidence for the presence of
any other phase was found. Variations in the lattice parameters of the exsolved
bornite phase were observed for different bulk compositions across the join, and
ascribed to variations in the degree of order. Bornite exsolved from digenite-rich
compositions may not be fully ordered due to the much lower solvus temperatures at
the Cu-rich end of the solid solution. As only slight differences were observed
between the diffraction patterns of a visibly exsolved and a rapidly quenched
sample of the same bulk composition, the formation of optically-visible exsolution
lamellae on {100} is ascribed to a process of coalescence of sub-microscopic
domains initially formed during the quenching process. The rapid kinetics of
exsolution at geologically low temperatures, explains the lack of authenticated
natural occurrences of intermediate compositions in the solid solution in nature,
and the limited degree of stoichiometric variation observed in
end-members.
High-temperature diffusion of oxygen in synthetic diopside measured by nuclear
reaction analysis
Authors: Pacaud L. , Ingrin J. , Jaoul O.
Published: July 2002

We have performed O self-diffusion experiments in synthetic diopside single
crystals along the b-axis at temperatures ranging from
1473–1643 K, under controlled O partial pressure
(10−11–10−2 atm). The
18O tracer diffusion was imposed by solid/gas exchange
between 16O in diopside and
18O2-enriched
argon-hydrogen-H2O gas mixture. Diffusion profiles of
18O were measured by Nuclear Reaction Analysis
18O (p,α) 15N. The diffusion
coefficients are described by , with log
D0(m2/s)=−9.2
± 1.0 and E 310 ± 30 kJ/mol.

Our results are in agreement with Ryerson and McKeegan's (1994) data and
Farver's (1989) data along a direction perpendicular to the
c direction. Experiments performed in a wide
pO2 range show that
D is independent of
pO2.

We observe no change in the diffusion regime up to 1643 K (i.e. 22 K prior to
melting temperature). This result differs from the diffusion study of Ca in
diopside by Dimanov and Ingrin (1995), where a strong enhancement of Ca mobility,
attributed to an excess disorder in the Ca-sublattice, was observed above 1523 K.
We conclude that O diffusion in diopside is not affected by this premelting
phenomenon.
Induction of tolerance to human factor VIII in mice
Authors: Chao Hengjun , Walsh Christopher E.
Published: July 2002

This paper reports loss of human factor VIII (hFVIII) inhibitory antibody in immunocompetent C57BL/6 mice. High-titer anti-hFVIII antibody developed in the mice within 7 to 14 days of intraportal administration of adeno-associated virus (AAV) carrying FVIII that coincided with a reduction in plasma hFVIII antigen. Bethesda titers (> 100 units) persisted relatively unchanged for 9 to 10 months. Unexpectedly, at 10 months after injection of the virus, hFVIII protein (up to 59 ng/mL) was detected in 3 mice at the same time as disappearance of hFVIII inhibitor. The level of hFVIII was similar to that found in immunodeficient mice receiving the same dose of recombinant AAV carrying hFVIII without hFVIII inhibitor. These results suggest that tolerance to hFVIII can be induced by sustained expression of hFVIII in a mouse model. Further elucidation of this observation may affect use of FVIII gene transfer in the treatment of inhibitor-positive patients with hemophilia A.
Genetic basis of hemolytic anemia caused by pyrimidine 5′ nucleotidase deficiency
Authors: Marinaki Anthony M. , Escuredo Emilia , Duley John A. , Simmonds H. Anne , Amici Adolfo , Naponelli Valeria , Magni Giulio , Seip Martin , Ben-Bassat Isaac , Harley Eric H. , Thein Swee Lay , Rees David C.
Published: July 2002

Pyrimidine 5′ nucleotidase (P5′N-1) deficiency is an autosomal recessive condition causing hemolytic anemia characterized by marked basophilic stippling and the accumulation of high concentrations of pyrimidine nucleotides within the erythrocyte. It is implicated in the anemia of lead poisoning and is possibly associated with learning difficulties. Recently, a protein with P5′N-1 activity was analyzed and a provisional complementary DNA (cDNA) sequence published. This sequence was used to study 3 families with P5′N-1 deficiency. This approach generated a genomic DNA sequence that was used to search GenBank and identify the gene for P5′N-1. It is found on chromosome 7, consists of 10 exons with alternative splicing of exon 2, and produces proteins 286 and 297 amino acids long. Three homozygous mutations were identified in this gene in 4 subjects with P5′N-1 deficiency: codon 98 GAT→GTT, Asp→Val (linked to a silent polymorphism codon 92, TAC→TAT), codon 177, CAA→TAA, Gln→termination, and IVS9-1, G→T. The latter mutation results in the loss of exon 9 (201 bp) from the cDNA. None of these mutations was found in 100 normal controls. The DNA analysis was complicated by P5′N-1 pseudogenes found on chromosomes 4 and 7. This study is the first description of the structure and location of the P5′N-1 gene, and 3 mutations have been identified in affected patients from separate kindreds.
Down-regulation of interleukin-3/granulocyte-macrophage colony-stimulating factor receptor β-chain in BCR-ABL+human leukemic cells: association with loss of cytokine-mediated Stat-5 activation and protection from apoptosis after BCR-ABL inhibition
Authors: Donato Nicholas J. , Wu Ji Y. , Zhang Ling , Kantarjian Hagop , Talpaz Moshe
Published: July 2002

Several signaling cascades are engaged by expression of the p210 bcr-abl tyrosine kinase, and evidence suggests that these signals drive leukemogenesis. In this report, signaling pathways were examined and compared between cells derived from leukemic patients and cells expressing a bcr-abl construct (MBA). The effects of acute inhibition of bcr-abl with STI-571 on these signals and the survival of bcr-abl–expressing cells were also evaluated. Expression of bcr-abl in interleukin-3 (IL-3)/granulocyte-macrophage colony-stimulating factor (GM-CSF)–dependent Mo7e cells (MBA) resulted in growth factor independence, constitutive activation of Stat-5 phosphorylation, engagement of mitogen-activated protein (MAP) kinase signals, and increased expression of PTP1B and bcl-xL. STI-571 inhibited cell growth and induced apoptosis in bcr-abl–expressing cells (MBA, K562, BV-173, KBM5) but not in bcr-abl− tumor cells (Mo7e, KG-1, ME-180, Daudi). STI-571–mediated apoptosis correlated with the inhibition of Stat-5 and MAP kinase activation and a reduction in overexpressed bcl-xL but not in PTP1B. Inhibitor had no effect on IL-3/GM-CSF–dependent Mo7e cell signaling and did not prevent activation of the other Jak/Stat pathways (interferon α, IL-3/GM-CSF). However, neither IL-3 nor GM-CSF could reactivate Stat-5 after the STI-571–mediated inhibition of bcr-abl. Expression of the common β-chain of the IL-3/GM-CSF receptor was down-regulated in Stat-5–activated myeloid leukemic cells, suppressing IL-3/GM-CSF signal transduction and the ability of these cytokines to provide apoptotic protection. These studies suggest that bcr-abl activates cytokine-independent mechanisms of survival while inactivating intrinsic cytokine signaling cascades, making bcr-abl+myeloid cells vulnerable to apoptosis after bcr-abl inactivation.
Induction of cytotoxic T-cell responses against immunoglobulin V region–derived peptides modified at human leukocyte antigen–A2 binding residues
Authors: Harig Sabine , Witzens Mathias , Krackhardt Angela M. , Trojan Andreas , Barrett Patrick , Broderick Ryan , Zauls A. Jason , Gribben John G.
Published: July 2002

Cytotoxic T-lymphocyte (CTL) responses can be generated against peptides derived from the immunoglobulin (Ig) V region in some but not all patients. The main reason for this appears to be the low peptide-binding affinity of Ig-derived peptides to major histocompatibility complex (MHC) class I molecules and their resulting low immunogenicity. This might be improved by conservative amino acid modifications at the MHC-binding residues of the peptides (heteroclitic peptides). In this study, it was found that in 18 Ig-derived peptides, that heteroclitic peptides from the Ig gene with improved binding to human leukocyte antigen (HLA)-A*0201 can be used to improve CTL responses. Amino acid substitution substantially increased predicted binding affinity, and there was a strong correlation between predicted and actual binding to HLA-A*0201. CTLs generated against the heteroclitic peptide had not only enhanced cytotoxicity against the heteroclitic peptide but also increased killing of antigen-presenting cells pulsed with the native peptide. Surprisingly, no difference was observed in the frequency of T cells detected by MHC class I peptide tetramers after stimulation with the heteroclitic peptide compared with the native peptide. CTLs generated against heteroclitic peptides could kill patients' tumor cells, showing that Ig-derived peptides can be presented by the tumor cell and that the failure to mount an immune response (among other reasons) likely results from the low immunogenicity of the native Ig-derived peptide. These results suggest that heteroclitic Ig-derived peptides can enhance immunogenicity, thereby eliciting immune responses, and that they might be useful tools for enhancing immunotherapy approaches to treating B-cell malignant diseases.
Correlation of peripheral blood OX40+(CD134+) T cells with chronic graft-versus-host disease in patients who underwent allogeneic hematopoietic stem cell transplantation
Authors: Kotani Ai , Ishikawa Takayuki , Matsumura Yumi , Ichinohe Tatsuo , Ohno Hitoshi , Hori Toshiyuki , Uchiyama Takashi
Published: July 2002

There is no reliable laboratory indicator of the onset of chronic graft-versus-host disease (cGVHD). This study looks at whether the expression of OX40, a member of the tumor necrosis factor receptor family, is related to the development of cGVHD in patients who underwent allogeneic hematopoietic stem cell transplantation. Peripheral blood mononuclear cells from 22 patients after day 100 were subjected to multicolor flow cytometry. The percentages of both OX40+CD4+ and OX40+CD8+T cells were significantly higher in patients with cGVHD than those without (P < .0001 and P = .001, respectively). Serial analyses showed that OX40+CD4+ T cells elevated before the onset of cGVHD and closely correlated with the therapeutic response. The expression of CD25, CD69, and HLA-DR was partially detectable on OX40+ T cells. These results indicate that serial measurement of OX40+ T cells is useful for predicting the onset as well as the therapeutic response of cGVHD and raise a possibility that the OX40/gp34 system is involved in the pathogenesis of cGVHD.
Perverted responses of the human granulocyte-macrophage colony-stimulating factor receptor in mouse cell lines due to cross-species β-subunit association
Authors: McClure Barbara , Stomski Frank , Lopez Angel , Woodcock Joanna
Published: July 2002

Transfected murine cell lines are commonly used to study the function of many human cytokine or receptor mutants. This study reports the inappropriate activation of the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) receptor by the human GM-CSF antagonist, E21R, when the human receptor is introduced into the murine cell line BaF-B03. E21R-induced proliferation of the BaF-B03 cells is dependent on transfection with both hGM-CSF receptor α and βc subunits. Studies on the underlying mechanism revealed constitutive association between human and mouse βc and GM-CSF receptor-α, tyrosine phosphorylation of mouse and human βc, and association of phosphorylated mouse βc into an activated human GM-CSF receptor complex in response to E21R and GM-CSF. This interspecies receptor cross-talk of receptor signaling subunits may produce misleading results and emphasizes the need to use cell lines devoid of the cognate endogenous receptors for functional analysis of ligand and receptor mutants.
Expression of p15ink4b gene during megakaryocytic differentiation of normal and myelodysplastic hematopoietic progenitors
Authors: Teofili Luciana , Martini Maurizio , Di Mario Antonella , Rutella Sergio , Urbano Raffaella , Luongo Myriam , Leone Giuseppe , Larocca Luigi Maria
Published: July 2002

In myelodysplastic syndrome (MDS), the expression of the cyclin-dependent kinase inhibitor p15ink4B (p15) is frequently decreased because of the aberrant methylation of the gene promoter; p15 is normally up-regulated during megakaryocytic differentiation. It was hypothesized that p15 methylation and deregulation of gene expression contribute to defective megakaryocytopoiesis in patients with MDS. Here it is shown that the increasing autocrine production of TGF-β1 stimulates megakaryocytic differentiation in normal CD34+ cells and that p15 mediates, at least in part, this effect. This TGF-β1–dependent pathway is altered in MDS CD34+progenitors because of p15 methylation. The demethylating agent 2-deoxyAZAcytidin can restore the normal demethylated state of thep15 gene and increase its expression. Nevertheless, MDS CD34+ cells only poorly differentiate to the megakaryocytic lineage. These findings suggest that p15 methylation occurs in a neoplastic clone with a profound defect of cell proliferation, survival, and differentiation that cannot be overcome by using a demethylating drug.
Defective hematopoiesis and hepatic steatosis in mice with combined deficiencies of the genes encoding Fancc and Cu/Zn superoxide dismutase
Authors: Hadjur Suzana , Ung Karen , Wadsworth Louis , Dimmick James , Rajcan-Separovic Evica , Scott Richard W. , Buchwald Manuel , Jirik Frank R.
Published: July 2002

Several lines of evidence point to an abnormality in the response of Fanconi anemia cells to reactive oxygen species. To investigate the potential pathologic consequences of an in vivo alteration of redox state in mice lacking one of the Fanconi anemia genes, animals were generated having combined deficiencies of the cytosolic Cu/Zn superoxide dismutase (Sod1) and Fanconi anemia complementation group C (Fancc) genes. Interestingly, hepatocytes of Fancc−/−Sod1−/−mice exhibited a zonal pattern of microvesicular steatosis, possibly as a result of oxidative stress-induced injury to hepatocyte membranes. Consistent with this idea, freshly explantedFancc−/−Sod1−/−hepatocytes demonstrated increased spontaneous production of superoxide in vitro. The second phenotypic feature ofFancc−/− Sod1−/−mice was that of bone marrow hypocellularity accompanied by significant decreases in peripheral blood erythrocyte and leukocyte numbers as compared with wild-type controls. Although flow cytometry analysis with monoclonal antibodies against cell surface antigens revealed normal numbers of primitive hematopoietic progenitor populations inFancc−/−Sod1−/−marrow, lineage-positive progenitor numbers were significantly reduced in these mice. Furthermore, the in vitro clonogenic growth ofFancc−/−Sod1−/−erythroid, myeloid, and early B-lymphoid colonies in semisolid media was profoundly compromised. These results suggested that the altered redox state likely present inFancc−/− Sod1−/−hematopoietic progenitors was responsible for an impairment of cell proliferation or survival.
An in vitro model of hematopoietic stem cell homing demonstrates rapid homing and maintenance of engraftable stem cells
Authors: Frimberger Angela E. , Stering Allen I. , Quesenberry Peter J.
Published: July 2002

Hematopoietic stem cell (HSC) homing is believed to rely heavily on adhesion interactions between stem cells and stroma. An in vitro assay was developed for adhesion of engraftable HSCs in bone marrow suspensions to pre-established Dexter-type long-term bone marrow culture stromal layers. The cell numbers in the adherent layer and supernatant were examined, along with the engraftment capability of adherent layer cells to indicate the number of HSCs that homed to in vitro stroma. The cell number in the supernatant declined over the 24-hour period. The number of test cells adhering to the stromal layer increased during the first hour and then fell at 6 and 24 hours. The number of test HSCs adhering to the stromal layer was substantial at 20 minutes, increased during the first hour, and then remained constant at 1, 6, and 24 hours of adhesion. These data indicate that adhesion of engraftable HSCs occurs quickly and increases during the first hour of contact with pre-established stroma, that adhesion plateaus within 1 hour of contact, and that HSCs maintain their engraftment capability for at least 24 hours of stromal adhesion. Long-term engraftment from test cells at more than 1 hour of adhesion represents 70.7% of the predicted engraftment from equivalent numbers of unmanipulated marrow cells, indicating that 2 of 3 test engraftable HSCs adhered. These findings demonstrate the usefulness of this model system for studying stem-stromal adhesion, allowing further dissection of the mechanism of HSC homing and exploration of possible manipulations of the process.
The Kit-activating mutation D816V enhances stem cell factor–dependent chemotaxis
Authors: Taylor Marcia L. , Dastych Jaroslaw , Sehgal Devinder , Sundstrom Magnus , Nilsson Gunnar , Akin Cem , Mage Rose G. , Metcalfe Dean D.
Published: July 2002

The D816V mutation of c-kit has been detected in patients with mastocytosis. This mutation leads to constitutive tyrosine kinase activation of Kit. Because stem cell factor (SCF), the ligand for Kit (CD117+), is a chemoattractant for CD117+ cells and one feature of mastocytosis is an abnormal collection of mast cells in tissues derived from CD34+CD117+ mast cell precursors, the hypothesis was considered that the D816V mutation would enhance chemotaxis of these precursor cells. Constructs encoding wild-type Kit or Kit bearing the D816V mutation were transfected into Jurkat cells, labeled with Calcein-am, and migration to SCF assessed in the presence or absence of tyrosine kinase inhibitors. Chemotaxis to SCF was enhanced in D816V transfectants compared to wild-type Kit transfectants (P < .002). Migration of both transfectants was inhibited by tyrosine kinase inhibitors, although D816V transfectants were more sensitive. Chemotaxis was next performed on CD34+CD117+ circulating mast cell precursors obtained from patients with mastocytosis. Analysis of prechemotaxis and migrated cells showed that whereas less than 10% in the prechemotaxis sample had the D816V mutation, 40% to 80% of migrated cells had this mutation. These results demonstrate that the D816V Kit mutation enhances chemotaxis of CD117+ cells, offering one explanation for increased mast cells observed in tissues of patients with mastocytosis.
Characterization of immunologic tolerance induced by transfusion of UV-B–irradiated allogeneic mononuclear leukocytes
Authors: Kao Kuo-Jang , Huang Eileen S. , Donahue Sandra
Published: July 2002

Transfusions of UV-B–irradiated peripheral blood mononuclear cells (UV-B–PBMCs) from BALB/c (H-2d) mice into CBA (H-2k) mice can induce humoral immune tolerance to H-2d antigens, and the induced tolerance is partially mediated by negative regulatory PBMCs. To further identify which subset of spleen mononuclear leukocytes (MNLs) in the tolerant CBA mice is responsible for the negative regulatory activity, adoptive transfer experiments were conducted using spleen MNLs from the tolerant CBA mice. Results showed that only CD4+ T cells could transfer the negative regulatory activity in a dose-dependent manner. This negative regulatory activity was significantly reduced when CD25+ helper T cells were removed. Further study suggested that inhibition of IL-12 production by UV-B–irradiated PBMCs played a role in the induction of immune tolerance. In vitro study of the cytokine production profile by CBA CD4+ T cells, after stimulation with gamma-irradiated BALB/c spleen cells, revealed an enhanced production of the type 2 T-cell cytokines after tolerance induction. Induction of tolerance also prevented the development of cytotoxic T cells in CBA mice against BALB/c MNLs. Adoptive transfer study suggested that the cellular immune tolerance was also mediated by CD4+ negative regulatory T cells. The induced immune tolerance was nullified after 400 cGy sublethal gamma irradiation. These results suggest that the ex vivo study of cytokine production by T cells may be used to monitor tolerance induction and the selection of gamma radiation dose is critical for potential clinical application of the tolerance induced by UV-B–PBMCs.
Inhibition of granulocyte-macrophage colony-stimulating factor receptor function by a splice variant of the common β-receptor subunit
Authors: Wagner Katharina , Kafert-Kasting Sabine , Heil Gerhard , Ganser Arnold , Eder Matthias
Published: July 2002

The receptors for human granuloctye-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are composed of a ligand-specific α-chain (eg, α–GM-CSF receptor [α-GMR]) and a common β-subunit (β-GMR). Ligand binding is believed to induce assembly or conformational changes in preformed complexes containing more than one α- and β-subunit in the activated receptor complex. To analyze the function of a splice variant of β-GMR with a truncation in the intracellular domain (β-GMRIT), BaF-3 cells expressing human α-GMR plus β-GMR were transfected with β-GMRIT. In these cells, coexpression of β-GMRIT inhibits GM-CSF–mediated survival and proliferation in a GM-CSF concentration–dependent manner. To analyze the effect of cytoplasmic assembly of truncated and full-length intracellular β-GMR sequences, β-GMR and β-GMRIT were coexpressed with different chimeric α/β-GMR constructs. Whereas both β-GMR and β-GMRIT generate high-affinity GMR complexes in the presence of α/β-GMR, β-GMRITinhibits while β-GMR supports proliferation and cell survival mediated by α/β-GMR. Correspondingly, β-GMR, but not β-GMRIT, generates functional GMR complexes when coexpressed with a defective α/β-GMR construct. These data indicate that β-GMRIT can inhibit survival and mitogenic signaling of the wild-type GMR and demonstrate that recruitment of alternatively spliced receptor subunits may regulate the function of heteromeric cytokine receptors.
Analysis of natural killer cells in TAP2-deficient patients: expression of functional triggering receptors and evidence for the existence of inhibitory receptor(s) that prevent lysis of normal autologous cells
Authors: Vitale Massimo , Zimmer Jacques , Castriconi Roberta , Hanau Daniel , Donato Lionel , Bottino Cristina , Moretta Lorenzo , de la Salle Henri , Moretta Alessandro
Published: July 2002

Natural killer (NK) cells are characterized by the ability to kill cells that lack HLA class I molecules while sparing autologous normal (HLA class I+) cells. However, patients with transporter-associated antigen processing (TAP) deficiency, though displaying strong reductions of HLA class I surface expression, in most instances do not experience NK-mediated autoimmune phenomena. A possible mechanism by which TAP−/− NK cells avoid autoreactivity against autologous HLA class I–deficient cells could be based on either quantitative or qualitative defects of surface receptors involved in NK cell triggering. In this study we show that NK cells derived from 2 patients with TAP2−/− express normal levels of all known triggering receptors. As revealed by the analysis of polyclonal and clonal NK cells, these receptors display normal functional capabilities and allow the killing of a panel of NK-susceptible targets, including autologous B-LCLs. On the other hand, TAP2−/− NK cells were unable to kill either allogeneic (HLA class I+) or autologous (HLA class I− ) phytohemagglutinin (PHA) blasts even in the presence of anti-HLA class I monoclonal antibody. These data suggest that TAP2−/− NK cells express still unknown inhibitory receptor(s) capable of down-regulating the NK cell cytotoxicity on binding to surface ligand(s) expressed by T cell blasts. Functional analyses, both at the polyclonal and at the clonal level, are consistent with the concept that the putative inhibitory receptor is expressed by virtually all TAP2−/− NK cells, whereas it is present only in rare NK cells from healthy persons. Another possibility would be that TAP2−/− NK cells are missing a still unidentified triggering receptor involved in NK cell-mediated killing of PHA blasts.
Effects of fractures on NMO velocities andP‐wave azimuthal AVO response
Authors: Shen Feng , Zhu Xiang , Toksöz M. Nafi
Published: July 2002

This paper attempts to explain the relationships between fractured medium properties and seismic signatures and distortions induced by geology‐related influences on azimuthal AVO responses. In the presence of vertically aligned fractures, the relationships between fracture parameters (fracture density, fracture aspect ratio, and saturated fluid content) and their seismic signatures are linked with rock physics models of fractured media. The P‐wave seismic signatures studied in this paper include anisotropic parameters (δ(v),(v), and γ(v)), NMO velocities, and azimuthal AVO responses, where δ(v)is responsible for near‐vertical P‐wave velocity variations,(v)defines P‐wave anisotropy, and γ(v)governs the degree of shearwave splitting. The results show that in gas‐saturated fractures, anisotropic parameters δ(v)and(v)vary with fracture density alone. However, in water‐saturated fractures δ(v)and(v)depend on fracture density and crack aspect ratio and are also related to Vp/VSand Vpof background rocks, respectively. Differing from δ(v)and(v), γ(v)is the parameter most related to crack density. It is insensitive to the saturated fluid content and crack aspect ratio. The P‐wave NMO velocities in horizontally layered media are a function of δ(v), and their properties are comparable with those of δ(v).

Results from 3‐D finite‐difference modeling show that P‐wave azimuthal AVO variations do not necessarily correlate with the magnitude of fracture density. Our studies reveal that, in addition to Poisson's ratio, other elastic properties of background rocks have an effect on P‐wave azimuthal AVO variations. Varying the saturated fluid content of fractures can lead to azimuthal AVO variations and may greatly change azimuthal AVO responses. For a thin fractured reservoir, a tuning effect related to seismic wavelength and reservoir thickness can result in variations in AVO gradients and in azimuthal AVO variations. Results from instantaneous frequency and instantaneous bandwidth indicate that tuning can also lead to azimuthal variations in the rates of changes of the phase and amplitude of seismic waves. For very thin fractured reservoirs, the effect of tuning could become dominant. Our numerical results show that AVO gradients may be significantly distorted in the presence of overburden anisotropy, which suggests that the inversion of fracture parameters based on an individual AVO response would be biased unless this influence were corrected. Though P‐wave azimuthal AVO variations could be useful for fracture detection, the combination of other types of data is more beneficial than using P‐wave amplitude signatures alone, especially for the quantitative characterization of a fractured reservoir.