bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance to NaCl induces changes in plasma membrane lipid composition, fluidity and H+‐ATPase activity of tomato calli
Authors: Kerkeb Loubna , Donaire Juan Pedro , Venema Kees , Rodríguez‐Rosales María Pilar
Published: March 2003

Two tomato (Lycopersicon esculentum Mill. cv. Pera) callus lines tolerant to NaCl were obtained by successive subcultures of NaCl‐sensitive calli in 50 and 100 mM NaCl‐supplemented medium. Growth and ion content, as well as plasma membrane lipid composition, fluidity and H+‐ATPase (EC 3.6.1.35) activity, were studied in both NaCl‐sensitive and NaCl‐tolerant calli. Although calli tolerant to 100 mM NaCl exhibited a reduced growth relative to calli sensitive to NaCl or tolerant to 50 mM NaCl, growth of calli tolerant to 100 mM NaCl was higher than that of NaCl‐sensitive calli grown for one subculture in 100 mM NaCl. Growth in the presence of 100 mM NaCl provoked an increase of Na+ and Cl− content, but no significant changes in K+ and Ca2+. As compared with NaCl‐sensitive and 50 mM NaCl‐tolerant calli, plasma membrane vesicles isolated from calli tolerant to 100 mM NaCl exhibited a higher phospholipid and sterol content as well as a lower phospholipid/free sterol ratio and a lower double bond index (DBI) of phospholipid fatty acids. The changes in plasma membrane lipid composition were correlated with a decrease of plasma membrane fluidity in calli tolerant to 100 mM NaCl, as indicated by fluorimetric studies using diphenylhexatriene (DPH) as probe. Plasma membrane‐enriched vesicles isolated from calli tolerant to 100 mM NaCl showed lower ATP hydrolysis and ATP‐dependent H+‐pumping activities, as well as a lower passive permeability to H+ than plasma membrane from NaCl‐sensitive and 50 mM NaCl‐tolerant calli. The involvement of the changes in plasma membrane lipid content and composition, fluidity and H+‐ATPase activity in salt tolerance of tomato calli is discussed.
Boron compartmentation in roots of sunflower plants of different boron status: A study using the stable isotopes 10B and 11B adopting two independent approaches
Authors: Pfeffer Heidrun , Dannel Frank , Römheld Volker
Published: March 2003

The intracellular compartmentation of boron (B) in roots of sunflower plants precultured with 100 μM B (high B) or 1 μM B (low B) was studied using two independent approaches. In the first approach, short‐term efflux studies using the stable isotopes 11B and 10B were carried out. In roots of high B plants, the calculated concentrations of B (nmol gFW −1) were 52.6 in the cell wall, 7.5 in the vacuole, 27.1 in the cytosol and 48.0 in the free space. In roots of low B plants, the concentrations of B (nmol gFW −1) were 43.4 in the cell wall, 2.8 in the vacuole, 17.9 in the cytosol and almost zero in the free space. Although the B supply differed by a factor 100, the B concentrations in the cytosol and the vacuole of low B plants were 66 and 37% of the respective concentrations in high B plants. This suggests an additional role for B in plant metabolism, besides its function in the cell wall. In the second approach, root B pools (cell sap and water‐insoluble residue) were determined for comparison, and found to be in good agreement with the results from the efflux study.
Light activates H2 15O flow in rice: Detailed monitoring using a positron‐emitting tracer imaging system (PETIS)
Authors: Kiyomiya S. , Nakanishi H. , Uchida H. , Nishiyama S. , Tsukada H. , Ishioka N. S. , Watanabe S. , Osa A. , Mizuniwa C. , Ito T. , Matsuhashi S. , Hashimoto S. , Sekine T. , Tsuji A. , Mori S.
Published: March 2003

Water (H2 15O) translocation from the roots to the top of rice plants (Oryza saliva L. cv. Nipponbare) was visualized over time by a positron‐emitting tracer imaging system (PETIS). H2 15O flow was activated 8 min after plants were exposed to bright light (1 500 μmol m−2 s−1). When the light was subsequently removed, the flow gradually slowed and completely stopped after 12 min. In plants exposed to low light (500 μmol m−2 s−1), H2 15O flow was activated more slowly, and a higher translocation rate of H2 15O was observed in the same low light at the end of the next dark period. NaCl (80 mM) and methylmercury (1 mM) directly suppressed absorption of H2 15O by the roots, while methionine sulfoximine (1 mM), abscisic acid (10 μM) and carbonyl cyanide m‐chlorophenylhydrazone (10 mM) were transported to the leaves and enhanced stomatal closure, reducing H2 15O translocation.
Nickel and copper tolerance and toxicity in three Tuscan populations of Silene paradoxa
Authors: Gonnelli Cristina , Galardi Francesca , Gabbrielli Roberto
Published: March 2003

Three Tuscan ecotypes of Silene paradoxa L. were studied to evaluate the occurrence of multiple tolerance or co‐tolerance mechanisms and to underline some tolerance strategies in plants naturally adapted to toxic concentrations of heavy metals. Seeds were collected from non‐toxic calcareous soil, a serpentine outcrop with high nickel content and a copper mine dump. The evaluation of the toxic effects of the metals on root growth showed the copper‐tolerant population as nickel co‐tolerant, whereas the opposite was not the case. This suggests the occurrence of a non‐reciprocal co‐tolerance mechanism.

The nickel‐tolerant population seemed able to tolerate nickel by limiting its inhibiting effect on the peroxisomal H2O2 scavenging enzymes since, in the sensitive population, this inhibition revealed itself as one of the causes of nickel‐induced oxidative stress. A very low copper root and shoot concentration seemed to be characteristic of the copper‐tolerant population, combined with a low susceptibility to metal‐induced oxidative stress.
Cell wall modifications of bean (Phaseolus vulgaris) cell suspensions during habituation and dehabituation to dichlobenil
Authors: Encina Antonio , Sevillano José Manuel , Acebes José Luis , Alvarez Jesús
Published: March 2003

Bean (Phaseolus vulgaris L.) cell suspensions were adapted for growth in 12 µM dichlobenil (2,6‐dichlorobenzonitrile or DCB) by a stepwise increase in the concentration of the inhibitor in each subculture. Non‐tolerant suspensions (I50 = 0.3 µM) gave rise to single cells or small clusters while tolerant cell suspensions (I50 = 30 µM) grown in DCB formed large clusters. The cells in these clusters were surrounded by a thick and irregular cell wall with a lamellate structure and lacking a differentiated middle lamella. Analysis of habituated cell walls by Fourier transform infrared spectroscopy and cell wall fractionation revealed: (1) a reduced amount of cellulose and hemicelluloses, mainly xyloglucan (2) qualitative and quantitative differences in pectin levels, and (3) a non‐crystalline and soluble β‐1,4‐glucan. When tolerant cells were returned to medium lacking DCB, the size of the cell clusters was reduced; the middle lamella was only partly formed, and the composition of the cell wall gradually reverted to that obtained with non‐tolerant cells. However, dehabituated cells (I50 = 12 µM) were 40‐fold more tolerant to DCB than non‐tolerant cells and were only 2.5‐fold more sensitive than tolerant cells.
The dose–response curve of the gravitropic reaction: a re‐analysis
Authors: Perbal Gérald , Jeune Bernard , Lefranc Agnès , Carnero‐Diaz Eugénie , Driss‐Ecole Dominique
Published: March 2003

The dose–response curve of the gravitropic reaction is often used to evaluate the gravisensing of plant organs. It has been proposed (Larsen 1957) that the response (curvature) varies linearly as a function of the logarithm of the dose of gravistimulus. As this model fitted correctly most of the data obtained in the literature, the presentation time (tp, minimal duration of stimulation in the gravitational field to induce a response) or the presentation dose (dp, minimal quantity in g.s of stimulation to induce a response) were estimated by extrapolating down to zero curvature the straight line representing the response as a function of the logarithm of the stimulus. This method was preferred to a direct measurement of dp or tp with minute stimulations, since very slight gravitropic response cannot be distinguished from the background oscillations of the extremity of the organs. In the present review, it is shown that generally the logarithmic model (L) does not fit the experimental data published in the literature as well as the hyperbolic model (H). The H model in its simplest form is related to a response in which a ligand‐receptor system is the limiting phase in the cascade of events leading to the response (Weyers et al. 1987). However, it is demonstrated that the differential growth, responsible for the curvature (and the angle of curvature), would vary as a hyperbolic function of the dose of stimulation, even if several steps involving ligand‐receptor systems are responsible for the gravitropic curvature. In the H model, there is theoretically no presentation time (or presentation dose) since the curve passes through the origin. The value of the derivative of the H function equals a/b and represents the slope of the cune at the origin. It could be therefore used to estimate gravisensitivity. This provides a measurement of graviresponsiveness for threshold doses of stimulation. These results imply that the presentation time (or presentation dose) derived from the L model cannot be used anymore as an estimate of gravisensitivity. On the contrary, the perception time (minimal duration of a repeated stimulation which induces a response), which is less than 1 s, should be related to the perception of gravity. The consequences of these results on the mode of action and the nature of graviperception are discussed.
Jasmonic acid affects plant morphology and calcium‐dependent protein kinase expression and activity in Solanum tuberosum
Authors: Ulloa Rita M. , Raíces Marcela , MacIntosh Gustavo C. , Maldonado Sara , Téllez‐Iñón María T.
Published: March 2003

The effect of jasmonic acid (JA) on plant growth and on calcium‐dependent protein kinase (CDPK) activity and expression was studied in non‐photoperiodic potato plants, Solanum tuberosum L. var. Spunta, grown in vitro. Stem cuttings were grown for 45 days (long treatment, LT) in MS medium with increasing concentrations of JA. For short treatments (ST) adult plants grown in MS were transferred for 1, 4 and 20 h to JA containing media. During the LT, low concentrations of JA promoted cell expansion and shoot elongation while higher concentrations caused growth inhibition. Under these conditions, treated plants showed root shortening and tuber formation was not induced. Morphological and histochemical studies using light microscopy and TEM analysis of leaves from treated plants revealed that JA also affected subcellular organelles of mesophyll cells. Peroxisomes increased in size and number, and an autophagic process was triggered in response to high concentrations of the hormone. CDPK activity, determined in crude extracts of treated plants (LT), was inhibited (up to 80%). Plant growth and CDPK inhibition were reverted upon transfer of the plants to hormone‐free medium. Soluble CDPK activity decreased in response to JA short treatment. Concomitantly, a decline in the steady state levels of StCDPK2 mRNA, a potato CDPK isoform that is expressed in leaves, was observed. These data suggest that the phytohormone down‐regulated the expression and activity of the kinase.
Effect of regurgitant from Leptinotarsa decemlineata on wound responses in Solanum tuberosum and Phaseolus vulgaris
Authors: Kruzmane Dace , Jankevica Liga , Ievinsh Gederts
Published: March 2003

The effect of regurgitant from Leptinotarsa decemlineata Say larvae on wound‐induced responses was studied using two plant species, Solanum tuberosum L. and Phaseolus vulgaris L. Wounding of one leaf of intact S. tuberosum plants differentially affected ethylene production and activities of peroxidase and polyphenol oxidase. Only polyphenol oxidase activity was stimulated by wounding in both wounded and systemic leaves. Peroxidase activity was not affected by wounding. Wounding caused only a transient increase of ethylene production from wounded leaves. The application of regurgitant to wound surfaces stimulated ethylene production as well as activities of peroxidase and polyphenol oxidase in both wounded and systemic leaves. Wounding significantly enhanced ethylene production and polyphenol oxidase activity in wounded and systemic leaves of P. vulgaris. The application of regurgitant caused an amplification of ethylene production, peroxidase activity, and polyphenol oxidase activity, in both wounded and systemic leaves of bean plants. Several substances were tested for their role as possible endogenous signals in P. vulgaris. Hydrogen peroxide and methyl jasmonate appeared as potential local and systemic signals of ethylene formation in wounded bean plants. Local ethylene production in leaf discs was differentially affected by the regurgitant application in potato versus bean plants. While all tested concentrations of regurgitant caused stimulation of ethylene formation from potato leaf discs, ethylene production was completely inhibited by increasing concentrations of the regurgitant in bean leaf discs. Our data present evidence that ethylene may play an important role in the interaction between plants and herbivores at the level of recognition of a particular herbivore leading to specific induction of signalling cascades.
Transport interactions between cadmium and zinc in roots of bread and durum wheat seedlings
Authors: Hart Jonathan J. , Welch Ross M. , Norvell Wendell A. , Kochian Leon V.
Published: March 2003

Field studies have shown that the addition of Zn to Cd‐containing soils can help reduce accumulation of Cd in crop plants. To understand the mechanisms involved, this study used 109Cd and 65Zn to examine the transport interactions of Zn and Cd at the root cell plasma membrane of bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var. durum). Results showed that Cd2+ uptake was inhibited by Zn2+ and Zn2+ uptake was inhibited by Cd2+. Concentration‐dependent uptake of both Cd2+ and Zn2+ consisted of a combination of linear binding by cell walls and saturable, Michaelis‐Menten influx across the plasma membrane. Saturable influx data from experiments with and without 10 µm concentrations of the corresponding inhibiting ion were converted to double reciprocal plots. The results revealed a competitive interaction between Cd2+ and Zn2+, confirming that Cd2+ and Zn2+ share a common transport system at the root cell plasma membrane in both bread and durum wheat. The study suggests that breeding or agronomic strategies that aim to decrease Cd uptake or increase Zn uptake must take into account the potential accompanying change in transport of the competing ion.
Celery (Apium graveolens) parenchyma cell walls: cell walls with minimal xyloglucan
Authors: Thimm Julian C. , Burritt David J. , Sims Ian M. , Newman Roger H. , Ducker William A. , Melton Laurence D.
Published: March 2003

The primary walls of celery (Apium graveolens L.) parenchyma cells were isolated and their polysaccharide components characterized by glycosyl linkage analysis, cross‐polarization magic‐angle spinning solid‐state 13C nuclear magnetic resonance (CP/MAS 13C NMR) and X‐ray diffraction. Glycosyl linkage analysis showed that the cell walls consisted of mainly cellulose (43 mol%) and pectic polysaccharides (51 mol%), comprising rhamnogalacturonan (28 mol%), arabinan (12 mol%) and galactan (11 mol%). The amounts of xyloglucan (2 mol%) and xylan (2 mol%) detected in the cell walls were strikingly low. The small amount of xyloglucan present means that it cannot coat the cellulose microfibrils. Solid‐state 13C NMR signals were consistent with the constituents identified by glycosyl linkage analysis and allowed the walls to be divided into three domains, based on the rigidity of the polymers. Cellulose (rigid) and rhamnogalacturonan (semi‐mobile) polymers responded to the CP/MAS 13C NMR pulse sequence and were distinguished by differences in proton spin relaxation time constants. The arabinans, the most mobile polymers, responded to single‐pulse excitation (SPE), but not CP/MAS 13C NMR. From solid‐state 13C NMR of the cell walls the diameter of the crystalline cellulose microfibrils was determined to be approximately 3 nm while X‐ray diffraction of the cell walls gave a value for the diameter of approximately 2 nm.
Cytokinins and bud morphology in Pinus radiata
Authors: Zhang Huaibi , Horgan Kathryn Joan , Reynolds Paul Hugh Stewart , Jameson Paula Elizabeth
Published: March 2003

Cytokinins (CKs) play essential roles in the regulation of plant growth and development. In the previous paper (Zhang et al. 2001), we reported the detection and identification of a wide spectrum of CKs, including several novel forms, in the buds of Pinus radiata D. Don. In this paper we examine the relationship between the CKs and buds from juvenile and adult trees of P. radiata. During development the morphology of buds alters significantly, from buds bearing primary needles during their juvenile phase to buds sealed in scales at the adult phase. The morphology of adult buds is a very stable character, as fascicle meristems released from apical dominance, or cultured in vitro, produced only secondary needles. However, exogenous CK causes the adult buds to revert to juvenile bud development in vitro. Analyses of the endogenous CKs revealed that juvenile buds had a relatively higher level of isopentenyladenine and isopentenyladenosine, extremely low levels of phosphorylated CKs and a relatively low level of novel CK glycosides. The adult buds contained lower levels of free base and riboside CKs but very high levels of phosphorylated CKs and novel CK glycosides. Possible roles for CKs in the regulation of bud development are discussed.
Aldehyde oxidase isoforms and subunit composition in roots of barley as affected by ammonium and nitrate
Authors: Omarov Rustem , Dräger Dörthe , Tischner Rudolf , Lips Herman
Published: March 2003

Aldehyde oxidase (AO; EC 1.2.3.1) isoforms in roots of barley plants grown on ammonium or nitrate as nitrogen sources were studied. Roots of ammonium‐grown barley plants exhibited considerable levels of AO2, AO3, and AO4 activities after native PAGE. Significantly lower AO2 and AO3 activity bands were observed in roots of plants grown on nitrate. When abscisic aldehyde was used as a substrate a strong response of the AO2 band was observed as well as a faint reaction of the AO3 band, but no activity of AO4 was observed using this substrate. The 160 and 145 kDa polypeptides were detected in ammonium grown plants. Root extracts of nitrate‐fed plants revealed only a minor 145 kDa protein band and none of the 160 kDa subunit was detected. The assembly of the AO3 heterodimer requires the simultaneous presence of 160 and 145 kDa subunits. Subunit analysis of AO2 and AO4 revealed homodimeric composition of 160 and 145 kDa, respectively. Western blot analysis revealed changing AO subunits levels during germination and plant development. Differential expression of AO subunits (160 and 145 kDa) and subsequent formation of isoforms, which differ in substrate specificity, distribution and fulfil different enzymatic reactions, may constitute an important regulatory mechanism in the plant.
Effect of pig‐specific cytokines on mobilization of hematopoietic progenitor cells in pigs and on pig bone marrow engraftment in baboons
Authors: Kozlowski Tomasz , Monroy Rodney , Giovino Maria , Hawley Robert J. , Glaser Roseann , Li Zhifang , Meshulam Deborah H. , Spitzer Thomas R. , Cooper David K. C. , Sachs David H.
Published: March 2003

Kozlowski T, Monroy R, Giovino M, Hawley RJ, Glaser R, Li Z, Meshulam DH, Spitzer TR, Cooper DKC and Sachs DH Effect of pig specific cytokines on mobilization of hematopoietic progenitor cells in pigs and on pig bone marrow engraftment in baboons. Xenotransplantation 1999; 6: 00‐00. ©Munksgaard, Copenhagen.

Abstract: Mixed hematopoietic chimerism has been found to be a requirement for achieving specific immunologic hyporesponsiveness. Some of the requirements for in vitro and in vivo coexistence of discordant hematopoietic systems in the pig‐to‐baboon (or human) model have been investigated. We have tested the efficacy of pig‐specific cytokines (PSC) (IL3, SCF, GM‐CSF) in the mobilization of porcine bone marrow (BM) progenitors in vivo (i) in the pig and (ii) in baboons that underwent a conditioning regimen and porcine BM transplantation. In a preliminary in vitro study, porcine BM cells were incubated in various media to assess the effect of human plasma on pig progenitors in a colony‐forming unit (CFU) assay. In in vivo studies, four pigs received PSC and one control pig did not. Six baboons underwent natural antibody removal, with subsequent pig BM transplantation. Four of these six underwent nonmyeloablative (n=2) or myeloablative (n=2) conditioning and all received PSC treatment. Two baboons did not receive PSC, one of which underwent a nonmyeloablative regimen. Sequential blood samples and BM biopsies in pigs and baboons were analyzed by CFU assay for the detection of porcine cells. Baboon samples were analyzed by polymerase chain reaction (PCR) to detect porcine DNA.

In the case of the in vitro tests, colony forming by porcine progenitors was not inhibited by media containing human plasma and for the in vivo tests, PSC increased the number of progenitors in pig BM; mobilization of progenitors into the peripheral blood was observed. PSC‐treated baboons which experienced transient depletion of leukocytes < 1,000/ml (as an effect of the conditioning regimen) had porcine BM cells detectable by PCR for as long as day 316 after BM transplantation. In conclusion we found that: (i) under the conditions of these studies, in vitro porcine progenitor cell growth was not inhibited by human plasma containing natural antibody and complement; (ii) PSC treatment led to an increased number of progenitors in pig BM and peripheral blood; (iii) the combination of an effective conditioning regimen and treatment with PSC was capable of inducing long‐term survival of pig progenitors in baboons, although only a low level of engraftment was achieved.
The role of chemokines and their receptors in the rejection of pig islet tissue xenografts
Authors: Solomon Michelle F. , Kuziel William A. , Mann David A. , Simeonovic Charmaine J.
Published: March 2003

Solomon MF, Kuziel WA, Mann DA, Simeonovic CJ. The role of chemokines and their receptors in the rejection of pig islet tissue xenografts. Xenotransplantation 2003; 10: 164–177. © Blackwell Munksgaard, 2003

The mechanism by which inflammatory cells are recruited to pig islet tissue (proislet) xenografts was investigated by examining the intragraft mRNA expression of murine α‐ and β‐chemokines in CBA/H mice from days 3 to 10 post‐transplant. Xenograft rejection was associated with early intragraft transcript expression for monocyte chemotactic protein‐1 (MCP‐1) (3 to 5 days), IP‐10 (3 to 4 days) and macrophage inflammatory protein‐1α (MIP‐1α) (3 to 5 days) and subsequent expression of eotaxin (days 4 to 10), MIP‐1β (days 4 and 5) and regulated on activation, normal T cell expressed and secreted (RANTES) (days 4 to 6) mRNA. This pattern was consistent with the early recruitment of macrophages (MCP‐1, MIP‐1α), the influx of CD4 T cells (MCP‐1, MIP‐1α, MIP‐1β, IP‐10 and RANTES) and the characteristic infiltrate of eosinophils (eotaxin and RANTES) associated with islet xenograft rejection. Inhibition of β‐chemokine signaling in CCR2−/− mice (which lack the major co‐receptor for MCP‐1) resulted in retarded macrophage and CD4 T cell recruitment, enhanced eosinophil influx and a minor delay in rejection, compared with wildtype mice; there was little effect on leukocyte infiltration in xenografts harvested from CCR5−/− mice (lacking the co‐receptor for MIP‐1α, MIP‐1β and RANTES). The impeded migration of leukocytes into xenografts in CCR2−/− hosts was associated with delayed intragraft expression of MCP‐1 and RANTES mRNA; absence of MCP‐1/CCR2‐mediated signaling led to enhanced intragraft expression of MCP‐1, MIP‐1α and MIP‐1β mRNA. These findings suggest that MCP‐1 plays an important role in regulating macrophage and CD4 T cell infiltration to xenograft sites via the CCR2 signaling pathway. Additional treatment of xenografted CCR2−/− transplant recipients with anti‐interleukin‐(IL)‐4 and anti‐IL‐5 mAbs further delayed xenograft rejection demonstrating the potential for combined antirejection strategies in facilitating pig islet xenotransplantation.
Temperature and egg‐laying experience influence breeding performance of captive female houbara bustards
Authors: Van Heezik Yolanda , Jalme Michel Saint , Hémon Stéphane , Seddon Philip
Published: March 2003

The influence of climate, age and egg‐laying experience on reproductive performance (propensity, fecundity, timing) of a flock of captive houbara bustards was determined. The flock, established in Saudi Arabia for reintroduction purposes, was housed in outdoor pens, and fed food and water ad libitum. Birds were artificially inseminated when they came into breeding condition and eggs were removed soon after laying. Winter temperatures, rather than rainfall, synchronized reproduction in the captive flock. Cooler winter temperatures led to higher proportions of females laying, an earlier start to laying, and greater numbers of eggs laid per season. The first significant rainfall of the season stimulated some females to lay their last egg. Age per se had little effect on breeding performance independent of egg‐laying experience. Females with no previous egg‐laying experience laid fewer eggs than similarly aged females with previous experience. This difference, in combination with a pattern of increasing recruitment into the breeding population between 1 and 5 years of age, led to improved breeding performance in the population with age. The inferior performance of first‐time egg‐layers, despite ad libitum food, indicates restraint in the onset of breeding, which may be an adaptation for optimizing life‐time fitness.
Influence of hatching order on growth rate and resting metabolism of kestrel nestlings
Authors: Massemin Sylvie , Korpimäki Erkki , Pöyri Ville , Zorn Thierry
Published: March 2003

Hatching asynchrony in altricial birds may result in a competitive disadvantage for the youngest nestlings compared to older siblings. We studied the effects of a size hierarchy on the growth rate of Eurasian kestrelsFalco tinnunculuschicks in nests with and without access to supplemented food in western Finland. Body mass stopped increasing on the 19th day after hatching while body size, estimated by a combination of bone and feather lengths continued to increase at least until fledging at 26 days. Body condition, reflecting muscle and fat, did not change markedly during the growth period from the 12th day to fledging. Body temperature and resting metabolism were usually lower in nestlings 12 days old than in nestlings at fledging. Growth of body mass, size and condition, and resting metabolism were delayed in last‐hatched nestlings aged 19 days. Just before fledging, last‐hatched nestlings attained a similar body mass and size, and had a similar resting metabolism to those of older siblings. At fledging, only in nests without access to supplemented food was the body condition of last‐hatched chicks lower than that of its siblings, but in nests with access to supplemented food no such difference was detected. Our results highlight that the level of lipids in the last‐hatched nestling can be affected by the food restriction imposed by hatching order.
Life, activation and death of intrahepatic lymphocytes in chronic hepatitis C
Authors: Valiante Nicholas M. , D'Andrea Annalisa , Crotta Stefania , Lechner Franziska , Klenerman Paul , Nuti Sandra , Wack Andreas , Abrignani Sergio
Published: March 2003

Summary: The healthy liver of adult humans has little or no lymphocyte component and the histological finding of intrahepatic lymphocytes (IHL) is evidence of liver pathology. In a liver injured by chronic hepatitis C, the most common chronic liver disease, most IHL are activated/pro‐inflammatory cells, which are particularly enriched for effectors of innate immunity (natural killer (NK), natural T, and other NK‐like T cells). IHL do not undergo clonal expansion in the liver but migrate from extrahepatic sites to the chronically infected liver, where they display effector function and subsequently die, suggesting that maintenance of the IHL pool depends on continuous lymphocyte migration. The cytotoxic and inflammatory functions of these IHL have three potential outcomes: 1) they could be helpful in clearing the virus (a rare case in hepatitis C virus (HCV) infection);    2) they could be useless and have no effect on the infection; or 3) they could be harmful, whereby overaggressive lymphocyte responses destroy the liver in a continuous and unsuccessful attempt to clear the virus. Unfortunately, we do not know as of yet which of these possibilities is the case and, therefore, a more complete picture of the intrahepatic immune response will be relevant to the development of new therapeutic strategies against HCV. Additionally and from a more general perspective, due to the availability of biopsied material and the high prevalence (~3%) of HCV infection worldwide, studying the chronically inflamed liver of hepatitis C patients is an ideal model to investigate the poorly understood processes of lymphocyte trafficking, activation and death to non‐lymphoid sites of chronic inflammation in man.
Clinical bond failure of pre‐coated and operator‐coated orthodontic brackets
Authors: Kula K , Schreiner R , Brown J , Glaros A
Published: March 2003

Structured Abstract

Objectives –
To test the hypothesis that there is no significant difference in clinical bracket failure between the 3M APC Mini Twin™ bracket system and the Transbond XT™ adhesive during orthodontic treatment.

Design –
A randomized, split mouth, prospective clinical trial.

Setting and Sample Population –
The Department of Orthodontics and Dentofacial Orthopedics at University of Missouri, Kansas City. Twenty‐nine subjects who were treatment planned to receive comprehensive orthodontics using 0.018 slot appliances.

Experimental Variable –
The adhesive pre‐coated brackets (APC ) system was randomly assigned to one side of the mouth and the Transbond XTTMwas assigned to the opposite side.

Outcome Measure –
The absence of any of the brackets at the time of a regular or emergency orthodontic appointment.

Results –
There was no significant difference (P > 0.05) in bracket failure between the 3M APC Mini TwinTM bracket system and the Transbond XTTM adhesive at any time period (90, 180, or 365 days). The failure rate of brackets on premolars was higher than on incisors or canines.

Conclusion –
APC Mini TwinTM bracket system and Transbond XTTMadhesive are equally effective in maintaining brackets clinically. Inexperienced operators had an overall 7.5% bond failure 12 months following bracket placement.
Tgf‐β1, Tgf‐β2, Tgf‐β3 and Msx2 expression is elevated during frontonasal suture morphogenesis and during active postnatal facial growth
Authors: Adab K , Sayne JR , Carlson DS , Opperman LA
Published: March 2003

Structured Abstract

Authors –
Adab K, Sayne JR, Carlson DS, Opperman LA.

Objectives –
It is hypothesized that regulation of facial suture morphogenesis is similar to that of cranial sutures, with expression of similar regulatory molecules, governing suture formation and patency. The present study was designed to characterize the morphology of the frontonasal (FN) suture of the rat at different developmental stages and to investigate the presence and temporal‐spatial expression of transforming growth factor‐beta 1 (Tgf‐β1), Tgf‐β2, Tgf‐β3 and Msx2 mRNA within these structures.

Setting and sample population –
The Department of Biomedical Sciences at Texas A&M University System Health Science Center, Baylor College of Dentistry, Dallas, TX USA. Histological sections and RNA isolated from FN suture tissues of Sprague‐Dawley rats, aged embryonic day 16 through postnatal day 20.

Method –
Sections were examined after immunohistochemical staining. Gene expression was determined by densitometric analysis of RT‐PCR products run on agarose gels.

Results –
FN sutures develop slightly later than cranial sutures and show increased complexity over time when compared to cranial sutures. FN sutures were closely associated with the nasal capsular cartilage, with intervening layers of perichondrium and periosteum. The pattern of expression of Tgf‐βs within the FN suture tissues was similar to that seen in the cranial sutures. However, mRNA and protein of the Tgf‐βs were differentially expressed over time compared to cranial sutures. In FN sutures, Tgf‐β mRNA levels were elevated both during the period of suture morphogenesis and during active bone growth from the suture in the early postnatal period. Msx2 mRNA expression was elevated in both the prenatal and postnatal periods, similar to Tgf‐β mRNA expression.

Conclusion –
Tgf‐β and Msx2 are present in facial sutures similar to cranial sutures, but are differenentially expressed over time, perhaps reflecting different bone growth rates from these sutures.
Mannose‐binding lectin: targeting the microbial world for complement attack and opsonophagocytosis
Authors: Jack Dominic L. , Klein Nigel J. , Turner Malcolm W.
Published: March 2003

Mannose‐binding lectin (MBL) is an important constituent of the innate immune system. This protein binds through multiple lectin domains to the repeating sugar arrays that decorate many microbial surfaces, and is then able to activate the complement system through a specific protease called MBL‐associated protease‐2. We have used flow cytometry to study both the binding of MBL to microorganisms and the subsequent activation of complement. For selected Gram‐negative organisms, such as Salmonella and Neisseria, we have examined the relative roles of lipopolysaccharide (LPS) structure and capsule in determining binding and conclude that the LPS is of major importance. Our results from studies with several clinically relevant organisms also show that MBL binding detected by flow cytometry leads to measurable activation of purified C4, suggesting that the bound lectin is capable of initiating opsonophagocytosis and/or bacterial lysis. There is an increasing literature suggesting that MBL deficiency, which mainly results from three relatively common single point mutations in exon 1 of the gene, predisposes both to infection by extracellular pathogens and to autoimmune disease. In addition, the protein also modulates disease severity, at least in part through a complex, dose‐dependent influence on cytokine production. The mechanisms and signalling pathways involved in such processes remain to be elucidated.

We thank the Medical Research Council, the Wellcome Trust and Action Research for their support. Research at the Institute of Child Health and Great Ormond Street Hospital for Children NHS Trust benefits from R&D funding received from the NHS Executive. We thank David Smithson for graphic design of the figures.
The centromeric part of the human natural killer (NK) receptor complex: lectin‐like receptor genes expressed in NK, dendritic and endothelial cells
Authors: Hofer Erhard , Sobanov Yuri , Brostjan Christine , Lehrach Hans , Düchler Markus
Published: March 2003

Summary: The human natural killer (NK) receptor complex encompasses a region of about 2 Mb on the short arm of chromosome 12. It contains at least 18 lectin‐like receptor genes, of which some are expressed in NK and NK/T cells and function as NK receptors. Close to the CD94 and NKG2 NK receptor genes in the centromeric part, a novel family of genes, expressed in myeloid, dendritic and/or endothelial cells, recently became evident. These genes encode a receptor for oxidized low density lipoprotein in endothelial cells and three other receptors potentially serving regulatory functions in dendritic cells. Although the overall structure of the human NK receptor complex is similar to the syntenic rodent regions, the centromeric part lacks the cluster of Ly49 genes. This supports the notion that recognition of MHC class Ia molecules has evolved separately in rodents and humans in the lectin‐like Ly49 and the killer immunoglobulin‐like receptors, respectively. In the telomeric part, other lectin‐like genes expressed in different hematopoietic lineages are found. The receptors of the NK receptor complex apparently serve important functions in several leukocytes and in endothelial cells, and the exact role of these receptors, their ligands, and their distinct and co‐ordinate regulation in different cell lineages warrants further investigation.()

This work was supported by grants of the Austrian National Bank and the European Commission.
Rat natural killer cell receptor systems and recognition of MHC class I molecules
Authors: Rolstad Bent , Naper Christian , Løvik Guro , Vaage John Torgils , Ryan James C. , Bäckman‐Petersson Eva , Kirsch Ralf D. , Butcher Geoffrey W.
Published: March 2003

Summary: Rat natural killer (NK) cells recognize MHC‐I molecules encoded by both the classical (RT1‐A) and non‐classical (RT1‐C/E/M) MHC class I (MHC‐I) regions. We have identified a receptor, the STOK2 antigen, which belongs to the Ly‐49 family of killer cell lectin‐like receptors, and we have localized the gene encoding it to the rat natural killer cell gene complex. We have also shown that it inhibits NK cytotoxicity when recognizing its cognate MHC‐I ligand RT1‐A1c on a target cell. This is the first inhibitory Ly‐49–MHC‐I interaction identified in the rat and highlights the great similarity between rat and mouse Ly‐49 receptors and their MHC ligands. However, the mode of rat NK‐cell recognition of target cells indicates that positive recognition of allo‐MHC determinants, especially those encoded by the RT1‐C/E/M region, is a prevalent feature. NK cells recruited to the peritoneum as a consequence of alloimmunization display positive recognition of allodeterminants. In one case, NK cells activated in this way have been shown to be specific for the immunizing, non‐classical class I molecule RT1‐Eu. These findings show that allospecific NK cells sometimes show features reminiscent of the adaptive immune response.

This research was supported by grants from the Norwegian Cancer Society, the Research Council of Norway, the Anders Jahre's Fund, the UK BBSRC to RDK (PhD studentship) and GWB (Competitive Strategic Grant). EBP also acknowledges support from The Swedish Foundation for International Cooperation in Research and Higher Education, The Knut and Alice Wallenberg Foundation and the Swedish Institute.
Immunobiology of natural killer cells and bone marrow transplantation: merging of basic and preclinical studies
Authors: Murphy William J. , Koh Crystal Y. , Raziuddin Arati , Bennett Michael , Longo Dan L.
Published: March 2003

Summary: Natural killer (NK) cells mediate acute rejection of bone marrow, but not solid tissue, allografts in lethally irradiated mice. Precisely how and why this rejection occurs is still unclear. In allogeneic bone marrow transplantation (BMT), a spectrum of results is possible; one result can be marrow graft failure due to host rejection of the graft by NK and T cells and, at the opposite spectrum, the occurrence of graft‐versus‐host disease (GVHD). Donor NK cells, however, appear capable of improving donor engraftment without giving rise to GVHD and thus may be of use as an immunotherapy following BMT. As NK‐cell inhibitory receptors play a role in bone marrow cell rejection, these same inhibitory receptors may also affect NK responses towards tumor cells. It has been demonstrated that blocking the interaction of inhibitory receptors with MHC determinants on tumor cells can result in greater antitumor effects. Thus, NK cells are capable of mediating both positive and negative effects during BMT depending on whether they are of host versus donor origin and their state of activation. Understanding their role in BMT provides insights as to their physiological roles and points the way to potential clinical uses.

The authors are grateful for the excellent secretarial assistance by Ms Laura Knott. The authors thank Dr Lisbeth Welniak for critically reviewing the manuscript. WJM is particularly grateful to the members of his laboratory for contributing to the projects over the years and to his two mentors, MB and DLL, for their training and guidance, which allowed him to develop his studies on the basic and preclinical aspects of NK cells in BMT in his laboratory. This project has been funded in whole or in part with Federal funds from the National Cancer Institute, National Institutes of Health, under Contract No. N01‐CO‐56000, and by NIH grants CA36922, CA70134, and AI38938. The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.
Regulatory T cells in spontaneous autoimmune encephalomyelitis
Authors: De Camargo Furtado Gláucia , Olivares‐Villagómez Danyvid , Curotto de Lafaille Maria A. , Wensky Allen K. , Latkowski Jo‐Ann , Lafaille Juan J.
Published: March 2003

Summary: Spontaneous experimental autoimmune encephalomyelitis (EAE) develops in 100% of mice harboring a monoclonal myelin basic protein (MBP)‐specific CD4+αβ T‐cell repertoire. Monoclonality of the αβ T‐cell repertoire can be achieved by crossing MBP‐specific T‐cell receptor (TCR) transgenic mice with either RAG−/− mice or TCR α−/−/TCR β−/− double knockout mice. Spontaneous EAE can be prevented by a single administration of purified CD4+ splenocytes or thymocytes obtained from wild‐type syngeneic mice. The regulatory T cells (T‐reg) that protect from spontaneous EAE need not express the CD25 marker, as effective protection can be attained with populations depleted of CD25+ T cells. Although the specificity of the regulatory T cells is important for their generation or regulatory function, T cells that protect from spontaneous EAE can have a diverse TCR α and β chain composition. T‐reg cells expand poorly in vivo, and appear to be long lived. Finally, precursors for T‐reg are present in fetal liver as well as in the bone marrow of aging mice. We propose that protection of healthy individuals from autoimmune diseases involves several layers of regulation, which consist of CD4+CD25+ regulatory T cells, CD4+CD25− T‐reg cells, and anti‐TCR T cells, with each layer potentially operating at different stages of T‐helper cell‐mediated immune responses.
Neuroinflammation in the rat – CNS cells and their role in the regulation of immune reactions
Authors: Piehl Fredrik , Lidman Olle
Published: March 2003

Summary: Recent discoveries suggest that the resident cells of the central nervous system (CNS) the nerve cells and glia, play a more immunologically active role than was previously assumed. Neuroglial communication is of central interest in virtually all types of pathological conditions that affect the brain and several features of the activation that results from nerve cell damage resemble the type of innate immune reactions that occur in other parts of the body. In particular, the characteristics of the activation of these CNS cells will affect both the interaction with cells of the immune system as well as processes related to neurodegeneration and regeneration. We here review data regarding 3 different aspects of local inflammatory activation in the rat nervous system: (i) the genetic heterogeneity of glial activation across inbred strains after nerve injury, (ii) expression of MHC class I genes in the CNS and (iii) neuroprotective effects of CNS antigen autoreactive immune reactions. Apart from neuroimmune diseases such as experimental autoimmune encephalomyelitis/multiple sclerosis, these features are also of relevance for a wider range of neurological diseases which present pathological signs of inflammation, such as Alzheimer's dementia, cerebrovascular diseases and CNS trauma.
Regulation of inflammatory responses by natural anticoagulants
Authors: Okajima Kenji
Published: March 2003

Summary: Proinflammatory cytokines such as tumor necrosis factor‐α (TNF‐α) are critically involved in activation of the coagulation system in sepsis, leading to disseminated intravascular coagulation (DIC). Natural anticoagulants such as antithrombin (AT) and activated protein C (APC) regulate the coagulation system by inhibiting thrombin generation. In addition to these anticoagulant effects, both AT and APC have been shown to attenuate inflammatory responses induced by various noxious stimuli in rats such as lipopolysaccharide (LPS) challenge. AT promotes the endothelial release of prostacyclin, a potent anti‐inflammatory prostaglandin that inhibits the monocytic production of TNF‐α, by interacting with cell‐surface heparin‐like substances. APC directly inhibits the production of TNF‐α by inhibiting the activation of both nuclear factor κB (NFκB) and activator protein‐1 in monocytes stimulated with LPS. Thrombomodulin, an endothelial membranous integral protein that binds thrombin, exerts anti‐inflammatory effects by generating APC. Furthermore, tissue factor pathway inhibitor, a natural anticoagulant for the extrinsic pathway of the coagulation system, also attenuates LPS‐induced inflammatory responses in rats by inhibiting TNF‐α production by monocytes. These findings strongly suggest that natural anticoagulants could regulate inflammatory responses as well as the coagulation system in rats by inhibiting the monocytic production of TNF‐α. Such anti‐inflammatory properties of natural anticoagulants are potentially important for their replacement in patients with sepsis who frequently develop DIC and organ failure as inflammatory responses.
DNA methylation and Z‐DNA formation as mediators of quantitative differences in the expression of alleles
Authors: Rothenburg Stefan , Koch‐Nolte Friedrich , Haag Friedrich
Published: March 2003

Summary: With draft copies of several model genomes available in the near future, attention is turning towards the genetic mechanisms that determine differences between individuals. While mutations in protein coding regions affect the structure of gene products, polymorphisms outside such regions may cause quantitative differences in gene expression. Here we summarize observations indicating that such differences may be mediated by allele‐specific alterations in the modification or structure of DNA. Mono‐allelic expression of the rat T‐cell differentiation marker RT6 in a subpopulation of cells is associated with allele‐specific differences in DNA methylation in the RT6 promoter. In contrast to previously described examples of mono‐allelic expression, these are determined neither stochastically nor by parental origin, but by cis‐acting elements within the alleles. An attractive candidate is a rodent identifier (ID) element exclusively present in the RT6a allele. In the case of the rat nucleolin gene, a polymorphic dinucleotide repeat in the 5′ region modulates promoter strength and forms left‐handed Z‐DNA in vivo. Models explaining putative effects of Z‐DNA formation on transcription are presented. These observations suggest novel mechanisms by which repetitive DNA, an abundant source of polymorphism in the mammalian genome, may exert quantitative effects on gene expression.