bluuebunny/crossref_metadata_2025_split huggingface dataset:
Odontoblast primary cilia: facts and hypotheses
Authors: Magloire Henry , Couble Marie‐Lise , Romeas Annick , Bleicher Françoise 
Published: January 2004

AbstractOdontoblasts, the cells responsible for the dentine formation, are organized as a single layer of highly polarized and differentiated post‐mitotic cells along the interface between the dental pulp and the mineralized tubules. They lay down the physiological secondary dentine throughout the life of the teeth. Odontoblasts play a central role in the transportation of calcium to the dentine and they possibly mediate early stages of sensory processing in teeth. A primary cilium, 9+0 configuration, have been regularly identified in a supra nuclear location. Calbindin D28k has been detected at the base of the cilium membrane. The cilium structure was positive with detyrosinated α tubulin antibodies in vivo and in cultured human odontoblasts. Transcripts of tektin, a protein involved in ciliogenesis, were expressed in vitro. The putative role of the primary cilium constituting a critical link between external teeth stimuli and odontoblast responses is extensively discussed.
A perspective on inversin
Authors: Eley Lorraine , Turnpenny Lee , Yates Laura M , Craighead A. Scott , Morgan David , Whistler Catherine , Goodship Judith A , Strachan Tom 
Published: January 2004

AbstractOver the past 5 years, there has been increasing evidence for the role of primary (9+0) cilia in renal physiology and in establishing the left—right axis. The cilia in the renal tract are immotile and thought to have a sensory function. Cilia at the murine embryonic node have a vortical movement that sets up a leftward flow. Inversin, the protein defective in the inv mouse and in patients with type‐2 nephronophthisis, localizes to both renal and node primary cilia. However, we present evidence that it is also expressed before the node forms and that its subcellular localization in renal tubular cells is not confined to the cilia. Its role in both the pathway determining left—right axis and renal function remains to be elucidated.
Co‐treatment with dexamethasone and octanoate induces adipogenesis in 3T3‐L1 cells
Authors: Takenouchi Takato , Takayama Yoshiharu , Takezawa Toshiaki 
Published: January 2004

AbstractWe report here that octanoate, a medium chain fatty acid, induces adipocyte differentiation in 3T3‐L1 cells by co‐treatment with dexamethasone, although octanoate has been known not to stimulate 3T3‐L1 adipogenesis. A low concentration of exogenous glucose prevented 3T3‐L1 adipogenesis induced by 1‐methyl 3‐isobutylxanthine, dexamethasone, and insulin (MDI) treatment (a common protocol for adipocyte differentiation). In contrast, co‐treatment with dexamethasone and octanoate (D‐OCT) induced adipogenesis under the same conditions. These findings imply that octanoate, rather than glucose, is the source of accumulated lipids in D‐OCT‐induced adipogenesis. D‐OCT increased expression of the differentiation markers peroxisome proliferator‐activated receptor (PPAR)γ2 and caveolin‐1. A specific inhibitor of p38 mitogen‐activated protein (MAP) kinase inhibited D‐OCT‐induced adipogenesis. These results suggest that the p38 MAP kinase pathway followed by up‐regulation of PPARγ2 may be involved in 3T3‐L1 adipocyte differentiation induced by D‐OCT, as well as by MDI.
Analysis of age dependent changes of Topoisomerase II α and β in rat brain
Authors: Kondapi Anand K. , Mulpuri Neelima , Mandraju R.K. , Sasikaran B. , Subba Rao K. 
Published: January 2004

AbstractEukaryotic Topoisomerase II (Topo II) is present in two isoforms α and β. The α isoform is predominantly localized in proliferative tissue, while β isoform is present in all tissues. In the present study we report the activity and protein levels of Topoisomerase II α and β in rat brains of different age groups viz.: E11 (Embryo day 11), E18 (Embryo day 18), post‐natal day 1, young (<10 days), adult (<6 months) and old (>2 years). Topoisomerase II β isoform is found to be the predominant form in brain tissue but Topoisomerase II α is found in embryos up to post‐natal day 1. The studies to examine the regional distribution of Topoisomerase II β in brain showed highest activity in cerebellar region and that too only neuronal cell fraction. There was a significant age‐dependent decline in this activity. Hence, Topoisomerase II β may have some unknown function in cerebellum and the low levels of Topoisomerase II β activity in ageing cerebellum may contribute to the genomic instability in cerebellar region of ageing brain.
Targeted delivery of progenitor cells for cartilage repair
Authors: Dennis James E. , Cohen Nir , Goldberg Victor M. , Caplan Arnold I. 
Published: January 2004

AbstractAn approach for promoting the adherence of chondrogenic progenitor cells to specific matrix molecules has been tested in a cartilage defect model. Culture‐expanded pre‐chondrocytes fluorescently labeled with a vital dye were coated by a two‐step method wherein lipidated protein G was first allowed to intercalate into cell membranes, and a second incubation in a solution of antibodies to cartilage matrix antigens allowed the binding of the antibodies to the protein G, on the external surface of the cell. The coating technique (termed „cell painting”︁) does not effect cell viability or inhibit growth and chondrogenic potential. Painted cells were then added to rabbit cartilage explants that had a partial‐thickness defect, washed, and prepared for histological examination and for confocal microscopy. The histological observations and the confocal observations and fluorescent intensity quantification consistently demonstrated that progenitor cells painted with multiple antibodies were capable of preferential binding to the exposed cartilage matrix within the defect. These results demonstrate that painting cell membranes with antibodies to matrix molecules is an effective method for promoting the adherence of stem or progenitor cells to a cartilage injury site. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
An Update on Cystic Ovarian Degeneration in Cattle
Authors: Peter AT 
Published: January 2004

ContentsCystic ovarian degeneration (COD) is considered to be one of the most important causes of reproductive failure in cattle. There is a severe economic loss to dairy industry because COD increases days‐open in the postpartum period and the culling rates. The disease process is a consequence of a mature follicle that fails to ovulate at the appointed time of ovulation in the oestrous cycle. This anovulatory follicular structure either regresses or persists as a follicular or luteal cyst depending upon its structural/functional characteristics. The cells lining the follicular cyst synthesize oestrogen that, in certain instances, forces the animal to exhibit clinical signs of nymphomania. Besides oestrogen production, as per recent findings, they are also capable of secreting varying amount of progesterone which may dictate their fate. The animals that carry a luteal cyst may tend to be in anoestrus as the higher amount of progesterone secreted by this luteinized structure may change the pattern of gonadotrophins’ secretion. Present findings suggest that perturbation of the hypothalamo‐hypophyseal‐ovarian (HHO) axis, due to many exogenous and endogenous factors, as the cause for anovulation. For example, it has been suggested that lack of hypothalamic or hypophyseal response to the positive feedback effect of oestrogens that are secreted by the dominant follicle as one of the many causes. The non‐physiological changes that occur in the receptor expression of the HHO axis for the hormones involved in maturation, deviation, dominance and ovulation of the follicle may be yet another cause. The changes that occur at the cellular and molecular level in the ovary (in response to the factors mentioned above) that contribute to anovulation remain to be documented. This approach would allow us to completely understand the disease process. Hitherto, hormonal preparations that release luteinizing hormone from the anterior pituitary or have luteinizing hormone‐like action are used to treat follicular cysts. GnRH belongs to the former group and human chorionic gonadotrophin (hCG) hormone forms the latter group. Treatment with a luteolytic agent, prostaglandin F2α(PGF2α), is successful if a luteal cyst is diagnosed properly. Many agents may be developed in the future if the cellular and molecular pathways of the disease process are delineated. This article will review recent advances in our understanding of the pathogenesis of COD and suggest direction for future studies to completely understand the disease mechanism. This review will also discuss the existing method of treatments for cysts and methods proposed for treatment of cysts that tend to be refractory in nature.
The Legionella pneumophila LidA protein: a translocated substrate of the Dot/Icm system associated with maintenance of bacterial integrity
Authors: Conover Gloria M. , Derré Isabelle , Vogel Joseph P. , Isberg Ralph R. 
Published: January 2004

Summary Legionella pneumophila
establishes a replication vacuole within phagocytes that requires the bacterial Dot/Icm apparatus for its formation. This apparatus is predicted to translocate effectors into host cells. We hypothesized that some translocated proteins also function to maintain the integrity of the Dot/Icm translocator. Mutations that destroy this function are predicted to result in a Dot/Icm complex that poisons the bacterium, resulting in reduced viability. To identify such mutants, strains were isolated (called
lid
–
) that showed reduced viability on bacteriological medium in the presence of an intact Dot/Icm apparatus, but which had high viability in the absence of the translocator. Several such mutants were analysed in detail to identify candidate strains that may have lost the ability to synthesize a translocated substrate of Dot/Icm. Two such strains had mutations in the
lidA
gene. The LidA protein exhibits properties expected for a translocated substrate of Dot/Icm that is important for maintenance of bacterial cell integrity: it associates with the phagosomal surface, promotes replication vacuole formation, and is important for both efficient intracellular growth and high viability on bacteriological media after introduction of a plasmid that allows high level expression of the
dotA gene.
Neisseria meningitidis App, a new adhesin with autocatalytic serine protease activity
Authors: Serruto Davide , Adu‐Bobie Jeannette , Scarselli Maria , Veggi Daniele , Pizza Mariagrazia , Rappuoli Rino , Aricò Beatrice 
Published: January 2004

Summary Neisseria meningitidis
is a Gram‐negative bacterium which colonizes the human upper respiratory tract. Occasionally, it translocates to the bloodstream causing sepsis and from there it can cross the blood–brain barrier and cause meningitis. Many of the molecules, which mediate the interaction of
N. meningitidis
to host cells, are still unknown. Recently, App (
A
dhesion and
p
enetration
p
rotein) was described as a member of the autotransporter family and a homologue to the Hap (
H
aemophilus
a
dhesion and
p
enetration) protein of
Haemophilus influenzae
, a molecule that plays a role in the interaction with human epithelial cells. In this study we expressed
app
in
Escherichia coli
in order to analyse the functional properties of the protein. We show that the protein is exported to the
E. coli
surface, processed by an endogenous serine‐protease activity and released in the culture supernatant.
Escherichia coli
expressing
app
adhere to Chang epithelial cells, showing that App is able to mediate bacterial adhesion to host cells. The serine protease activity is localized at the amino‐terminal domain, whereas the binding domain is in the carboxy‐terminal region. The role of App in adhesion was confirmed also in
N. meningitidis .
Turnover of FlhD and FlhC, master regulator proteins for Salmonella flagellum biogenesis, by the ATP‐dependent ClpXP protease
Authors: Tomoyasu Toshifumi , Takaya Akiko , Isogai Emiko , Yamamoto Tomoko 
Published: January 2004

SummaryIn enterobacteria such as Salmonella, flagellar biogenesis is dependent upon the master operon flhDC at the apex of the flagellar gene hierarchy, which is divided into three classes 1, 2 and 3. Previously we reported that depletion of the ClpXP ATP‐dependent protease results in dramatic enhancement of class 2 and class 3 gene transcription, whereas the transcription level of the flhDC operon remains normal in Salmonella enterica serovar Typhimurium. This suggests that the ClpXP protease may be responsible for the turnover of the FlhD and FlhC master regulators (Tomoyasu, T., Ohkishi, T., Ukyo, Y., Tokumitsu, A., Takaya, A., Suzuki, M. et al., 2002, J Bacteriol 184:645–653). In this study, to establish the role of the ClpXP protease in the turnover of FlhD and FlhC proteins, we analysed levels of the FlhD and FlhC proteins in wild‐type and ClpXP mutant cells using anti‐FlhD and anti‐FlhC antibodies. The results show that both FlhD and FlhC proteins are markedly accumulated in ClpXP mutant cells and the half‐life of FlhC is approximately fivefold longer in the ClpXP mutant, suggesting that the ClpXP protease is responsible for the degradation of FlhD and FlhC. The results also show that the ClpXP protease degrades both proteins in FlhD2FlhC2 complex but does not seem to recognize the respective subunits synthesized individually. Taken together, it is suggested that the cellular concentration of the FlhD2FlhC2 master regulator is tightly controlled at the post‐translational level by the ClpXP protease. We also examined the role of other members of the ATP‐dependent protease family in the regulation of flagellar biogenesis and concluded that only ClpXP in this family functions as a negative regulator for flagellar biogenesis in Salmonella.
The Lrp family of transcriptional regulators
Authors: Brinkman Arie B. , Ettema Thijs J. G. , De Vos Willem M. , Van Der Oost John 
Published: January 2004

SummaryGenome analysis has revealed that members of the Lrp family of transcriptional regulators are widely distributed among prokaryotes, both bacteria and archaea. The archetype Leucine‐responsive Regulatory Protein from Escherichia coli is a global regulator involved in modulating a variety of metabolic functions, including the catabolism and anabolism of amino acids as well as pili synthesis. Most Lrp homologues, however, appear to act as specific regulators of amino acid metabolism‐related genes. Like most prokaryotic transcriptional regulators, Lrp‐like regulators consist of a DNA‐binding domain and a ligand‐binding domain. The crystal structure of the Pyrococcus furiosus LrpA revealed an N‐terminal domain with a common helix–turn–helix fold, and a C‐terminal domain with a typical αβ‐sandwich fold. The latter regulatory domain constitutes a novel ligand‐binding site and has been designated RAM. Database analysis reveals that the RAM domain is present in many prokaryotic genomes, potentially encoding (1) Lrp‐homologues, when fused to a DNA‐binding domain (2) enzymes, when fused as a potential regulatory domain to a catalytic domain, and (3) stand‐alone RAM modules with unknown function. The architecture of Lrp regulators with two distinct domains that harbour the regulatory (effector‐binding) site and the active (DNA‐binding) site, and their separation by a flexible hinge region, suggests a general allosteric switch of Lrp‐like regulators.
The uncoupling of oxygen sensing, phosphorylation signalling and transcriptional activation in oxygen sensor FixL and FixJ mutants
Authors: Saito Ken , Ito Eiichi , Hosono Kaito , Nakamura Kayako , Imai Kiyohiro , Iizuka Tetsutaro , Shiro Yoshitsugu , Nakamura Hiro 
Published: January 2004

SummaryThe rhizobial FixL/FixJ system, a member of the superfamily of bacterial two‐component signal transducing systems, regulates the expression of nitrogen fixation‐related genes by sensing environmental oxygen tension. Oxygen‐free (deoxy) FixL is autophosphorylated at an invariant histidine residue with ATP, and the phosphoryl group is transferred to FixJ, leading to an enhancement in transcriptional activity at low oxygen tensions, but the histidine kinase activity of the oxygen‐bound (oxy) form is inhibited. To investigate the mechanism of oxygen sensing, we established a FixL/FixJ‐mediated PfixK‐lacZ reporter system in Escherichia coli, and isolated FixL and FixJ mutations conferring an upregulation of lacZ gene expression on the reporter cells even under aerobic conditions. FixL mutant proteins, which contain single amino acid changes near the autophosphorylation site, showed elevated levels of autophosphorylation and a concomitant phosphoryl transfer to FixJ in the presence of oxygen, although their oxygen‐binding affinities were unimpaired. These mutational analyses suggest that the autophosphorylation domain plays a crucial role in regulatory coupling between oxygen binding and kinase activity. FixJ mutants in helix α1 and strand β5 of the N‐terminal half exhibited the formation of a stable acyl phosphate bond. In contrast, those in helices α4 and α5 constitutively bound to the fixK promoter in a monomeric form, suggesting that the α4 and α5 helices may be involved in the post‐phosphorylation/dimerization signal transfer to liberate the DNA‐binding activity of the C‐terminal domain, not only serving as a dimerization interface.
Protein–peptidoglycan interactions modulate the assembly of the needle complex in the Salmonella invasion‐associated type III secretion system
Authors: Pucciarelli M. Graciela , García‐del Portillo Francisco 
Published: January 2004

SummaryThe invasion‐associated type III secretion system of Salmonella enterica assembles as a supra‐molecular structure, termed needle complex, which spans the bacterial envelope. Here, we present evidence for protein–peptidoglycan interactions that modulate the assembly of this organelle. The presence of major membrane components of the needle complex (PrgH, PrgK and InvG) and InvH, required for efficient assembly of the organelle, was examined in peptidoglycan purified by extensive boiling of bacteria in 4% SDS. InvH, PrgH and PrgK, but not InvG, were detected in this purified material. InvH was present in the peptidoglycan in higher relative amounts than PrgH or PrgK, and was the only protein efficiently bound to peptidoglycan in cross‐linking experiments. Analysis in mutants defective for needle complex proteins showed that the needle proteins PrgI and PrgJ and, to a lesser extent, InvH, sustain the association of PrgH and PrgK with peptidoglycan. In contrast, the association of InvH with peptidoglycan did not necessitate other needle complex proteins. Functional analysis showed that the association of InvH, PrgH and PrgK with peptidoglycan is abolished in live bacteria carrying structural modifications in the peptidoglycan. The loss of these interactions caused a marked reduction in the number of needle complexes and, concomitantly, in protein secretion and bacterial invasion of cultured eukaryotic cells. Altogether, these data provide the first evidence for an association between proteins of the Salmonella needle complex and the peptidoglycan. In addition, we demonstrate that these protein–peptidoglycan interactions are critical for an efficient and correct assembly of this specialized organelle.
Co‐ordination of pathogenicity island expression by the BipA GTPase in enteropathogenic Escherichia coli (EPEC)
Authors: Grant Andrew J. , Farris Michele , Alefounder Peter , Williams Peter H. , Woodward Martin J. , O'Connor C. David 
Published: January 2004

SummaryBipA is a novel member of the ribosome binding GTPase superfamily and is widely distributed in bacteria and plants. We report here that it regulates ­multiple cell surface‐ and virulence‐associated ­components in the enteropathogenic Escherichia coli (EPEC) strain E2348/69. The regulated components include bacterial flagella, the espC pathogenicity island and a type III secretion system specified by the locus of enterocyte effacement (LEE). BipA positively regulated the espC and LEE gene clusters through transcriptional control of the LEE‐encoded regulator, Ler. Additionally, it affected the pattern of proteolysis of intimin, a key LEE‐encoded adhesin specified by the LEE. BipA control of the LEE operated independently of the previously characterized regulators Per, integration host factor and H‐NS. In contrast, it negatively regulated the flagella‐mediated motility of EPEC and in a Ler‐independent manner. Our results indicate that the BipA GTPase functions high up in diverse regulatory   cascades   to   co‐ordinate   the   expression of key pathogenicity islands and other virulence‐associated factors in E. coli.
Comparative Study on Five Different Commercial Extenders for Boar Semen
Authors: Vyt P , Maes D , Dejonckheere E , Castryck F , Van Soom A 
Published: January 2004

ContentsIncreasing interest in a longer preservation of diluted boar sperm raises questions in the field concerning the choice of the extender. The aim of this study was to evaluate the longevity of boar sperm extended in currently used commercial semen extenders. Three long‐term extenders and two short‐term extenders were compared for different semen quality parameters that can be assessed under routine laboratory conditions. Sperm morphology, motility, pH and bacteriological contamination were investigated during a 7‐day period. The number of dead spermatozoa did not differ significantly among the extenders (p > 0.05). Sperm motility was not only related with storage period but most of all with pH, especially in long‐term extenders. Differences between the different extenders were prominent (p < 0.05); the sperm preserved in only one long‐term extender showed good motility during the whole test period. In all cases, the pH of the extended semen increased by 0.3–0.5 in the first days of storage and was significantly correlated with a decrease in motility. Bacteriological quality had no significant influence on motility or pH of the semen. In conclusion, we can state that in both short‐term extenders and in only one long‐term extender, sperm longevity, as evaluated by the parameters used in this study, was sufficient during the preservation period. To preserve the quality of diluted boar semen during long‐term storage, the choice of the long‐term extender is important. In addition, the monitoring of the pH of extended boar semen in our study emphasizes the importance of the buffering capacity of semen extenders.
Stage‐specific Expression of Leukaemia Inhibitory Factor and its Receptor in Rabbit Pre‐implantation Embryo and Uterine Epithelium During Early Pregnancy
Authors: Lei T , Yang ZQ , Xia T , Gan L , Chen XD , Yuan JH , Zhu Y 
Published: January 2004

ContentsLeukaemia inhibitory factor (LIF) has been shown to play an important role in the development and implantation of blastocysts in mice. In the current study, the reverse transcription–polymerase chain reaction (RT‐PCR) was employed to examine the expression patterns of LIF and its receptor (LIFR) genes in rabbit embryos during pre‐implantation development, and the uterine expression of LIF and LIFR was also evaluated by Western blotting. Transcripts for LIFR were detected within morula and blastocyst‐stage embryos, while the LIF mRNA was only found in blastocysts (from early to fully expanded blastocoel cavities), indicating that embryo‐derived LIF can act in an autocrine manner on the process of blastocyst formation. The expression levels of LIF and LIFR in uterine epithelium were gradually increased during pre‐implantation period and reached their highest levels on days 6.5 of pregnancy, just before the time of blastocyst implantation, suggest that paracrine LIF circuit should exist between the endometrium and the early embryos, which may be involved in the embryo‐maternal dialogue and important for the blastocyst implantation. The data present here show the stage‐specific and dynamic expression patterns of LIF and LIFR, both in embryos and endometrium, during early pregnancy in rabbits, which indicated that LIF might play an important role in the pre‐implantation development and subsequent implantation of rabbit embryos.