JOURNAL OF PHYCOLOGY, Issue 1 2008
Chantal Vis
A survey of the spatial distribution of benthic macroalgae in a fluvial lake of the St. Lawrence River (Lake Saint-Pierre, Quebec, Canada) revealed a shift in composition from chlorophytes to cyanobacteria along the flow path of nutrient-rich waters originating from tributaries draining farmlands. The link between this shift and changes in water quality characteristics was investigated by sampling at 10 sites along a 15 km transect. Conductivity, current, light extinction, total phosphorus (TP; >25 ,g P · L,1), and ammonium (8,21 ,g N · L,1) remained fairly constant along the transect in contrast to nitrate concentrations, which fell sharply. Filamentous and colonial chlorophytes [Cladophora sp. and Hydrodictyon reticulatum (L.) Bory] dominated in the first 5 km where nitrate concentrations were >240 ,g N · L,1. A mixed assemblage of chlorophytes and cyanobacteria characterized a 1 km transition zone where nitrate decreased to 40,80 ,g N · L,1. In the last section of the transect, nitrate concentrations dropped below 10 ,g N · L,1, and cyanobacteria (benthic filamentous mats of Lyngbya wollei Farl. ex Gomont and epiphytic colonies of Gloeotrichia) dominated the benthic community. The predominance of nitrogen-fixing, potentially toxic cyanobacteria likely resulted from excessive nutrient loads and may affect nutrient and trophic dynamics in the river. [source]

STREAMFLOW DEPLETION: MODELING OF REDUCED BASEFLOW ANI INDUCED STREAM INFILTRATION FROM SEASONALLY PUMPED WELLS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2001
Xunhong Chen
ABSTRACT: Numerical modeling techniques are used to analyze streamflow depletion for stream-aquifer systems with baseflow. The analyses calculated two flow components generated by a pumping well located at a given distance from a river that is hydraulically connected to an unconfined aquifer. The two components are induced stream infiltration and reduced baseflow; both contribute to total streamflow depletion. Simulation results suggest that the induced infiltration, the volume of water discharged from the stream to the aquifer, has a shorter term impact on streamflow, while the reduced baseflow curves show a longer term effect. The peak impacts of the two hydrologic processes on streamflow occur separately. The separate analysis helps in understanding the hydrologic interactions between stream and aquifer. Practically, it provides useful information about contaminant transport from stream to aquifer when water quality is a concern, and for areas where water quantity is an issue, the separate analysis offers additional information to the development of water resource management plan. [source]

TOGp regulates microtubule assembly and density during mitosis and contributes to chromosome directional instability

CYTOSKELETON, Issue 8 2009
Lynne Cassimeris
Abstract TOGp, a member of the XMAP215 MAP family, is required for bipolar mitotic spindle assembly. To understand how TOGp contributes to spindle assembly, we examined microtubule dynamics after depleting TOGp by siRNA. Fluorescence recovery after photobleaching of GFP-tubulin demonstrated that spindle microtubule turnover is slowed two-fold in the absence of TOGp. Consistent with photobleaching results, microtubule regrowth after washout of the microtubule depolymerizing drug nocodazole was slower at the centrosomes and in the vicinity of mitotic chromatin in cells depleted of TOGp. The slower microtubule turnover is likely due to either nucleation or the transitions of dynamic instability because TOGp depletion did not effect the rate of plus end growth, measured by tracking EB1-GFP at microtubule ends. In contrast, microtubule regrowth after nocodazole washout was unaffected by prior depletion of TACC3, a centrosomal protein that interacts with TOGp. Kinetochore fibers in both untreated and TOGp-depleted cells were stable to incubation at 4°C or lysis in buffer containing calcium indicating that stable kinetochore-microtubule attachments are formed in the absence of TOGp. Depletion of TOGp, but not TACC3, reduced kinetochore oscillations during prometaphase/metaphase. Defects in oscillations are not due simply to multipolarity or loss of centrosome focus in the TOGp-depleted cells, since kinetochore oscillations appear normal in cells treated with the proteosome inhibitor MG132, which also results in multipolar spindles and centrosome fragmentation. We hypothesize that TOGp is required for chromosome motility as a downstream consequence of reduced microtubule dynamics and/or density. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source]

Dan is required for normal morphogenesis and patterning in the developing chick inner ear

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2007
Takahiro Yamanishi
During vertebrate inner ear development, compartmentalization of the auditory and vestibular apparatuses along two axes depends on the patterning of transcription factors expressed in a region-specific manner. Although most of the patterning is regulated by extrinsic signals, it is not known how Nkx5.1 and Msx1 are patterned. We focus on Dan, the founding member of the Cerberus/Dan gene family that encodes BMP antagonists, and describe its function in morphogenesis and patterning. First, we confirmed that Dan is expressed in the dorso-medial region of the otic vesicle that corresponds to the presumptive endolymphatic duct and sac (ed/es). Second, we used siRNA knockdown to demonstrate that depletion of Dan induced both a severe reduction in the size of the ed/es and moderate deformities of the semicircular canals and cochlear duct. Depletion of Dan also caused suppression of Nkx5.1 in the dorso-lateral region, suppression of Msx1 in the dorso-medial region, and ectopic induction of Nkx5.1 and Msx1 in the ventro-medial region. Most of these phenotypes also appeared following misexpression of the constitutively active form of BMP receptor type Ib. Thus, Dan is required for the normal morphogenesis of the inner ear and, by inhibiting BMP signaling, for the patterning of the transcription factors Nkx5.1 and Msx1. [source]

Dopamine and sensory tissue development in Drosophila melanogaster

DEVELOPMENTAL NEUROBIOLOGY, Issue 4 2001
Wendi Neckameyer
Abstract Dopamine is an important signaling molecule in the nervous system; it also plays a vital role in the development of diverse non-neuronal tissues in the fruit fly Drosophila melanogaster. The current study demonstrates that males depleted of dopamine as third instar larvae (via inhibition of the biosynthetic enzyme tyrosine hydroxylase) demonstrated abnormalities in courtship behavior as adults. These defects were suggestive of abnormalities in sensory perception and/or processing. Electroretinograms (ERGs) of eyes from adults depleted of dopamine for 1 day as third instar larvae revealed diminished or absent on- and off-transients. These sensory defects were rescued by the addition of L -DOPA in conjunction with tyrosine hydroxylase inhibition during the larval stage. Depletion of dopamine in the first or second larval instar was lethal, but this was not due to a general inhibition of proliferative cells. To establish that dopamine was synthesized in tissues destined to become part of the adult sensory apparatus, transgenic lines were generated containing 1 or 4 kb of 5, upstream sequences from the Drosophila tyrosine hydroxylase gene (DTH) fused to the E. coli ,-galactosidase reporter. The DTH promoters directed expression of the reporter gene in discrete and consistent patterns within the imaginal discs, in addition to the expected expression in gonadal, brain, and cuticular tissues. The ,-galactosidase expression colocalized with tyrosine hydroxylase protein. These results are consistent with a developmental requirement for dopamine in the normal physiology of adult sensory tissues. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 280,294, 2001 [source]

Changes in antioxidant defense status in response to cisplatin and 5-FU in esophageal carcinoma

DISEASES OF THE ESOPHAGUS, Issue 2 2008
T. Kaur
SUMMARY., The ability of reactive oxygen species to induce cellular damage and to cause cell death opens the possibility of exploiting this property in the treatment of esophageal cancer through a free radical mediated mechanism. The present study was carried out with the aim of evaluating the changes in the antioxidant defense status in esophageal cancer patients treated without and with neoadjuvant therapy (NAT). Forty surgically resected tissue specimens from tumors, tissue adjoining the tumors and paired macroscopically normal mucosa were obtained from esophageal cancer patients treated with or without chemo-radiotherapy. An evaluation of antioxidant defense system in the normal, adjoining and tumor esophageal tissues in response to NAT revealed decreased catalase activity in tumor and adjoining tissues as compared to their respective normal tissue levels. Similarly, decreased superoxide dismutase activity was observed in tumor tissue in response to NAT. In both the treatment groups (with and without NAT), no significant change was observed in the enzyme activity of glutathione reductase in the normal, adjoining and tumor tissues. Enhanced glutathione peroxidase activity was found in tumor tissue, as compared to the adjoining and paired normal tissue of patients after NAT. Estimation of reduced glutathione (GSH) levels showed a significant decline in GSH levels in esophageal tumors after NAT. Depletion of GSH, an endogenous antioxidant, would elevate drug sensitivity and might predispose neoplastic cells to apoptosis in response to NAT. The antioxidant enzymes in the esophageal carcinoma thus may play an important role in influencing the final outcome upon NAT course. [source]

The PPAR, agonist GW501516 suppresses interleukin-6-mediated hepatocyte acute phase reaction via STAT3 inhibition

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 5 2007
T. Kino
Abstract Background, Interleukin-6 and downstream liver effectors acute phase reactants are implicated in the systemic inflammatory reaction. Peroxisome proliferator-activated receptor , (PPAR,), which binds to and is activated by a variety of fatty acids, was recently shown to have anti-inflammatory actions. Materials and methods, We examined the ability of the synthetic PPAR, agonist GW501516 to suppress interleukin-6-induced expression of acute phase proteins in human hepatoma HepG2 cells and rat primary hepatocytes. Results, GW501516 dose-dependently suppressed interleukin-6-induced mRNA expression of the acute phase protein ,1-antichymotrypsin in HepG2 cells. The compound also suppressed interleukin-6-induced mRNA expression of ,2-acid glycoprotein, ,-fibrinogen and ,2-macroglobulin in and the secretion of C-reactive protein by rat primary hepatocytes. Depletion of the PPAR, receptor, but not of PPAR, or ,, attenuated the suppressive effect of GW501516 on interleukin-6-induced ,1-antichymotrypsin mRNA expression, indicating that PPAR, specifically mediated this effect. Since interleukin-6 stimulates the transcriptional activity of the ,1-antichymotrypsin promoter by activating the signal transducer and activator of transcription (STAT) 3, we examined functional interaction of this transcription factor and PPAR, on this promoter. Overexpression of PPAR, enhanced the suppressive effect of GW501516 on STAT3-activated transcriptional activity of the ,1-antichymotrypsin promoter, while GW501516 suppressed interleukin-6-induced binding of this transcription factor to this promoter. Conclusions, These findings indicate that agonist-activated PPAR, interferes with interleukin-6-induced acute phase reaction in the liver by inhibiting the transcriptional activity of STAT3. PPAR, agonists might be useful for the suppression of systemic inflammatory reactions in which IL-6 plays a central role. [source]

Depletion of tumor-induced Treg prior to reconstitution rescues enhanced priming of tumor-specific, therapeutic effector T cells in lymphopenic hosts

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2009
Christian H. Poehlein
Abstract We reported previously that vaccination of reconstituted, lymphopenic mice resulted in a higher frequency of tumor-specific effector T cells with therapeutic activity than vaccination of normal mice. Here, we show that lymphopenic mice reconstituted with spleen cells from tumor-bearing mice (TBM), a situation that resembles the clinical condition, failed to generate tumor-specific T cells with therapeutic efficacy. However, depletion of CD25+ Treg from the spleen cells of TBM restored tumor-specific priming and therapeutic efficacy. Adding back TBM CD25+ Treg to CD25, naïve and TBM donor T cells prior to reconstitution confirmed their suppressive role. CD25+ Treg from TBM prevented priming of tumor-specific T cells since subsequent depletion of CD4+ T cells did not restore therapeutic efficacy. This effect may not be antigen-specific as three histologically distinct tumors generated CD25+ Treg that could suppress the T-cell immune response to a melanoma vaccine. Importantly, since ex vivo depletion of CD25+ Treg from TBM spleen cells prior to reconstitution and vaccination fully restored the generation of therapeutic effector T cells, even in animals with established tumor burden, we have initiated a translational clinical trial of this strategy in patients with metastatic melanoma. [source]

Loss of FOXP3 expression in natural human CD4+CD25+ regulatory T cells upon repetitive in vitro stimulation

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2009
Petra Hoffmann
Abstract The adoptive transfer of CD4+CD25+ natural regulatory T cells (Treg) is a promising strategy for the treatment of autoimmune diseases and the prevention of alloresponses after transplantation. Clinical trials exploring this strategy require efficient in vitro expansion of this rare cell population. Protocols developed thus far rely on high-grade purification of Treg prior to culture initiation, a process still hampered by the lack of Treg cell-specific surface markers. Depletion of CD127+ cells was shown to separate activated conventional T cells from natural Treg cell populations allowing the isolation of highly enriched FOXP3+ cells with all functional and molecular characteristics of natural Treg. Here, we demonstrate that upon in vitro expansion, CpG methylation in a conserved region within the FOXP3 gene locus increased in CD4+CD25+CD127low Treg, correlating with loss of FOXP3 expression and emergence of pro-inflammatory cytokines. Further analysis identified CD45RA,FOXP3+ memory-type Treg as the main source of converting cells, whereas CD45RA+FOXP3+ Treg from the same donors showed no conversion within 3,wk of in vitro expansion. Thus, Treg cell lineage differentiation does not seem to represent a final fate decision, as natural Treg can lose their cell-type-specific characteristics after repetitive TCR stimulation. [source]

CD4+CD25+ regulatory T,cells control the magnitude ofT-dependent humoral immune responses to exogenous antigens

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 4 2006
Fouad Eddahri
Abstract CD4+CD25+ T,reg cells are critical for peripheral tolerance and prevention of autoimmunity. Here we show that CD4+CD25+ T,reg also regulate the magnitude of humoral responses against a panel of T-dependent antigens of foreign origin during both primary and secondary immune responses. Depletion of CD4+CD25+ T,cells leads to increased antigen-specific antibody production and affinity maturation but does not affect T-independent B,cell responses, suggesting that CD4+CD25+ T,reg exert a feedback mechanism on non-self antigen-specific antibody secretion by dampening the T,cell help for B,cell activation. Moreover, we show that CD4+CD25+ T,reg also suppress in vitro B,cell immunoglobulin production by inhibiting CD4+CD25, T,cell help delivery, and that blockade of TGF-, activity abolishes this suppression. [source]

CpG ODN enhance antigen-specific NKT cell activation via plasmacytoid dendritic cells

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2005
Anja Marschner
Abstract Human V,24+ V,11+ natural killer T cells (NKT cells) are "natural memory" T cells that detect glycolipid antigens such as ,-galactosylceramide (,-GalCer) presented on CD1d. In the present study we found that highly purified V,24+ NKT cells lack TLR9 mRNA, and thus are not sensitive towards stimulation with CpG oligodeoxynucleotides (ODN). Within PBMC, however, CpG ODN synergistically activated NKT cells stimulated with their cognate antigen ,-GalCer. Depletion of plasmacytoid dendritic cells (PDC) or myeloid dendritic cells (MDC) revealed that both DC subsets were necessary for the synergistic activation of NKT cells by ,-GalCer and CpG ODN. While PDC were responsible for the stimulation of NKT cells with CpG ODN, MDC but not PDC presented ,-GalCer via CD1d. Partial activation of NKT cells was mediated by PDC-derived IFN-,, whereas full activation of NKT cells as indicated by IFN,, production required cell-to-cell contact of PDC and NKT cells in addition to IFN-,; OX40 was involved in this interaction. We conclude that CpG-activated PDC enhance ,-GalCer-specific NKT cell activation, and bias activated NKT cells towards a Th1 phenotype. Our results lead to a novel concept of PDC function: to regulate effector activity of antigen-stimulated T cells in a cell contact-dependent manner without the need of simultaneous presentation of the cognate T cell antigen. [source]

Depletion of immature B,cells during Trypanosoma cruzi infection: involvement of myeloid cells and the cyclooxygenase pathway

EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2005
Elina Zuniga
Abstract The ability of a microorganism to elicit or evade B,cell responses represents a determinant factor for the final outcome of an infection. Although pathogens may subvert humoral responses at different stages of B,cell development, most studies addressing the impact of an infection on the B,cell compartment have focused on mature B,cells within peripheral lymphoid organs. Herein, we report that a protozoan infection, i.e. a Trypanosoma cruzi infection, induces a marked loss of immature B,cells in the BM, which also compromises recently emigrated B,cells in the periphery. The depletion of BM immature B,cells is associated with an increased rate of apoptosis mediated by a parasite-indirect mechanism in a Fas/FasL-independent fashion. Finally, we demonstrated that myeloid cells play an important role in B,cell depletion, since CD11b+ BM cells from infected mice secrete a product of the cyclooxygenase pathway that eliminates immature B,cells. These results highlight a previously unrecognized maneuver used by a protozoan parasite to disable B,cell generation, limiting host defense and favoring its chronic establishment. [source]

Different pathways leading to cutaneous leukocytoclastic vasculitis in mice

EXPERIMENTAL DERMATOLOGY, Issue 6 2001
C. Sunderkötter
Abstract: To investigate the pathomechanisms of leukocytoclastic vasculitis (LcV) we compared mouse models of LcV with non-vasculitic irritant contact dermatitis (ICD). Criteria for LcV as met by the immune complex-mediated Arthus reaction (Art-r) were also fulfilled by the localized Shwartzman reaction (Shw-r) and by cutaneous Loxoscelism (Lox) (injection of venom from Loxosceles reclusa containing sphingomyelinase D). After depletion of PMN (by ,-irradiation) vessel damage could not be elicited in these models, distinguishing them from models of direct endothelial insult (necrotizing ICD). Depletion of complement could only delay, but not inhibit the Art-r, and did not change ICD, Lox or the Shw-r. The Shw-r exclusively revealed a sustained local expression of vascular adhesion molecules for 24 h in the preparatory phase (LPS s.c.), not observed in the Art-r, in Lox or ICD. Subsequent challenge with LPS i.p. was associated with upregulation of Mac-1 and ICAM-1 on PMN, but not of VLA-4 or LFA-1 (FACS analysis). Cytokines which were able to replace LPS in priming for LcV in the Shw-r (TNF-, and IL-1,) also induced sustained expression of adhesion molecules, whereas IL-12 and IFN-, did neither. Neutralizing IL-12 or IFN-, also inhibited neither LcV nor sustained expression of adhesion molecules, whereas anti-TNF-, inhibited both. Anti-TNF-, had no marked inhibitory effects in the Art-r, in Lox or ICD. Combined (but not separate) neutralization of both E-selectin and VCAM-1 by antibodies suppressed LcV independent from reducing influx of PMN, proving that their sustained expression is decisive for the Shw-r and interferes with normal diapedesis. Since Loxosceles venom is known to dysregulate diapedesis and degranulation of PMN in vitro, since adherent immune complexes activate PMN at the vessel wall, and since adhesion molecules are dysregulated in the Shw-r, we suggest that LcV develops when activation of PMN coincides with vascular alterations which interfere with normal diapedesis. [source]

Effect of Losartan on Sodium Appetite of Hypothyroid Rats Subjected to Water and Sodium Depletion and Water, Sodium and Food Deprivation

EXPERIMENTAL PHYSIOLOGY, Issue 5 2001
D. Badauê-Passos Jr
The involvement of angiotensin AT1 receptors in sodium appetite was studied in hypothyroid rats treated with the angiotensin II antagonist losartan. Losartan was administered chronically by the oral route or acutely by the subcutaneous route after water and sodium depletion or water, sodium and food deprivation. Three days after addition of losartan to the food at the dose of 1.0 mg g,1, the rats significantly reduced (P < 0.02) their spontaneous intake of 1.8% NaCl. Increasing the dose of losartan to 2.0 and 4.0 mg g,1 did not reduce NaCl intake; in contrast, the intensity of the sodium appetite gradually returned to previous levels. The simultaneous administration of captopril, an angiotensin converting enzyme inhibitor, and losartan significantly increased (P < 0.05) NaCl intake and after captopril removal NaCl intake returned to the levels observed with losartan treatment alone. The administration of losartan 4 days after the beginning of captopril treatment significantly reduced (P < 0.0001) NaCl intake. Following acute administration of losartan, water- and sodium-depleted rats significantly reduced their NaCl and water intake (P < 0.001). The administration of losartan also induced a significant reduction in NaCl and water intake in water, NaCl and food-deprived rats (P < 0.0001 and P < 0.001, respectively). The present results show that chronic treatment with oral losartan inhibited spontaneous sodium appetite in hypothyroid rats. Continuation of treatment rendered rats resistant to the blockade of AT1 receptors. Water and sodium depletion and water, NaCl and food deprivation induced sodium appetite, which in the short term depends on cerebral angiotensinergic activity mediated by the activation of AT1 receptors. [source]

Utp25p, a nucleolar Saccharomyces cerevisiae protein, interacts with U3 snoRNP subunits and affects processing of the 35S pre-rRNA

FEBS JOURNAL, Issue 13 2010
Mauricio B. Goldfeder
In eukaryotes, pre-rRNA processing depends on a large number of nonribosomal trans -acting factors that form intriguingly organized complexes. Two intermediate complexes, pre-40S and pre-60S, are formed at the early stages of 35S pre-rRNA processing and give rise to the mature ribosome subunits. Each of these complexes contains specific pre-rRNAs, some ribosomal proteins and processing factors. The novel yeast protein Utp25p has previously been identified in the nucleolus, an indication that this protein could be involved in ribosome biogenesis. Here we show that Utp25p interacts with the SSU processome proteins Sas10p and Mpp10p, and affects 18S rRNA maturation. Depletion of Utp25p leads to accumulation of the pre-rRNA 35S and the aberrant rRNA 23S, and to a severe reduction in 40S ribosomal subunit levels. Our results indicate that Utp25p is a novel SSU processome subunit involved in pre-40S maturation. Structured digital abstract ,,MINT-7889901: SAS10 (uniprotkb:Q12136) physically interacts (MI:0915) with Utp25p (uniprotkb:P40498) by pull down (MI:0096) ,,MINT-7889915: NIP7 (uniprotkb:Q08962) physically interacts (MI:0915) with RRP43 (uniprotkb:P25359) by two hybrid (MI:0018) ,,MINT-7889852: Utp25p (uniprotkb:P40498) physically interacts (MI:0915) with MPP10 (uniprotkb:P47083) by two hybrid (MI:0018) ,,MINT-7890065: NOP1 (uniprotkb:P15646) and Utp25p (uniprotkb:P40498) colocalize (MI:0403) by fluorescence microscopy (MI:0416) ,,MINT-7889865: Utp25p (uniprotkb:P40498) physically interacts (MI:0915) with SAS10 (uniprotkb:Q12136) by two hybrid (MI:0018) [source]

Biogenesis of the yeast frataxin homolog Yfh1p

FEBS JOURNAL, Issue 11 2000
Tim44-dependent transfer to mtHsp70 facilitates folding of newly imported proteins in mitochondria
Tim44 is an essential component of the mitochondrial inner membrane protein import machinery. In this study we asked if Tim44 is of relevance in intramitochondrial protein folding. We investigated the role of Tim44 in the biogenesis of the authentic mitochondrial protein Yfh1p, the yeast homolog of mammalian frataxin, which was recently implicated in Friedreich ataxia. After inactivation of Tim44, binding of mitochondrial heat shock protein (mtHsp)70 to translocating Yfh1p and subsequent folding to the native state was nearly completely blocked. Residual amounts of imported Yfh1p showed an increased tendency to aggregate. To further characterize the functions of Tim44 in the matrix, we imported dihydrofolate reductase (DHFR) as a model protein. Depletion of Tim44 allowed import of DHFR, although folding of the newly imported DHFR was delayed. Moreover, the depletion of Tim44 caused a strongly reduced binding of mtHsp70 and Mge1 to the translocating polypeptide. Subsequent dissociation of mtHsp70 from imported DHFR was delayed, indicating that mtHsp70,substrate complexes formed independently of Tim44 differ from the complexes that form under the control of Tim44. We conclude that Tim44 not only plays a role in protein translocation but also in the pathways of mitochondrial protein folding. [source]

Toxicity to Candida albicans mediated by human serum and peripheral blood mononuclear cells

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2006
Joseph M. Bliss
Abstract This study evaluates the conditions in which peripheral blood mononuclear cells mediate toxicity to Candida albicans opsonized with heat-inactivated human serum. Serum concentrations as low as 1% resulted in 50% inhibition of C. albicans metabolic activity after incubation with peripheral blood mononuclear cells at an effector to target ratio of 8. Measurable inhibition was also achieved at lower effector to target ratios and lower serum concentrations, and at least a portion of the metabolic inhibition reflected fungal cell death. Depletion of C. albicans -specific antibody decreased the toxic effect while opsonization with purified human IgG restored toxicity, and cell,cell contact between peripheral blood mononuclear cells and fungus was required. Depletion of or enrichment for monocytes from the peripheral blood mononuclear cells preparation diminished the toxic effect and the monocytic cell line, THP-1, was likewise incapable of toxicity. These studies provide evidence that antibody augments antifungal host defense and underscore the complex interrelationship between humoral and cellular immunity in these infections. [source]

Restoration of sturgeons: lessons from the Caspian Sea Sturgeon Ranching Programme

FISH AND FISHERIES, Issue 3 2000
D.H. Secor
Depletion of sturgeon stocks world-wide has increased interest in aquaculture-based restoration programmes. The Caspian Sea Sturgeon Ranching Programme (SRP) of the former Soviet Union represents a unique opportunity to evaluate expense, benefits and potential ecological and genetic effects of such restoration programmes. The SRP was initiated in the 1950s to compensate for lost spawning habitat in the Volga River and elsewhere. After its completion in 1962, the Volgograd Dam reduced spawning grounds in the Volga River system, the principal spawning tributary of the Caspian Sea, by ,80%. For two of the three commercial sturgeon species (Russian sturgeon, Acipenser güldenstädti, and stellate sturgeon, A. stellatus), yields improved after the imposition of the 1962 moratorium on sturgeon harvests in the Caspian Sea. Volga River fisheries were managed for spawning escapement. Although imprecisely known, the contribution of the millions of stocked Russian and stellate juveniles during 1962,91 was most likely important to sustaining fisheries, although less so (contributing to <30% of the adult stock) than natural recruitment. Apparently, reduced spawning grounds, supplemented with artificial spawning reefs were sufficient to support reproduction and large fishery yields of Russian and stellate sturgeons. For beluga sturgeon, Huso huso, harvests in the Volga River were nearly all dependent upon hatchery stocking. Beluga sturgeon spawning grounds were mostly eliminated with the construction of the Volgograd Dam. Without the hatchery programme, beluga sturgeon in the Volga River and Caspian Sea would in all likelihood have been extirpated. Currently, sturgeons are severely depleted in the Volga River and Caspian Sea due to poaching and lack of co-operation between countries exploiting the species. Aquaculture-based restoration in Russia is now viewed a chief means of rebuilding stocks of Caspian Sea sturgeons. [source]

hnRNP K interacts with RNA binding motif protein 42 and functions in the maintenance of cellular ATP level during stress conditions

GENES TO CELLS, Issue 2 2009
Toshiyuki Fukuda
Heterogeneous nuclear ribonucleoprotein K (hnRNP K) is a conserved RNA-binding protein that is involved in multiple processes of gene expression, including chromatin remodeling, transcription, RNA splicing, mRNA stability and translation, together with diverse groups of molecular partners. Here we identified a previously uncharacterized protein RNA binding motif protein 42 (RBM42) as hnRNP K-binding protein. RBM42 directly bound to hnRNP K in vivo and in vitro. RBM42 also directly bound to the 3, untranslated region of p21 mRNA, one of the target mRNAs for hnRNP K. RBM42 predominantly localized within the nucleus and co-localized with hnRNP K there. When cells were treated with agents, puromycin, sorbitol or arsenite, which induced the formation of stress granules (SGs), cytoplasmic aggregates of stalled translational pre-initiation complexes, both hnRNP K and RBM42 localized at SGs. Depletion of hnRNP K by RNA interference decreased cellular ATP level following release from stress conditions. Simultaneous depletion of RBM42 with hnRNP K enhanced the effect of the hnRNP K depletion. Our results indicate that hnRNP K and RBM42 are components of SGs and suggest that hnRNP K and RBM42 have a role in the maintenance of cellular ATP level in the stress conditions possibly through protecting their target mRNAs. [source]

Comprehensive analysis of the ICEN (Interphase Centromere Complex) components enriched in the CENP-A chromatin of human cells

GENES TO CELLS, Issue 6 2006
Hiroshi Izuta
The centromere is a chromatin structure essential for correct segregation of sister chromatids, and defects in this region often lead to aneuploidy and cancer. We have previously reported purification of the interphase centromere complex (ICEN) from HeLa cells, and have demonstrated the presence of 40 proteins (ICEN1,40), along with CENP-A, -B, -C, -H and hMis6, by proteomic analysis. Here we report analysis of seven ICEN components with unknown function. Centromere localization of EGFP-tagged ICEN22, 24, 32, 33, 36, 37 and 39 was observed in transformant cells. Depletion of each of these proteins by short RNA interference produced abnormal metaphase cells carrying misaligned chromosomes and also produced cells containing aneuploid chromosomes, implying that these ICEN proteins take part in kinetochore functions. Interestingly, in the ICEN22, 32, 33, 37 or 39 siRNA-transfected cells, CENP-H and hMis6 signals disappeared from all the centromeres in abnormal mitotic cells containing misaligned chromosomes. These results suggest that the seven components of the ICEN complex are predominantly localized at the centromeres and are required for kinetochore function perhaps through or not through loading of CENP-H and hMis6 onto the centromere. [source]

Distinct roles of DNA polymerases delta and epsilon at the replication fork in Xenopus egg extracts

GENES TO CELLS, Issue 3 2004
Tomoyuki Fukui
DNA polymerases , and , (Pol, and Pol,) are widely thought to be the major DNA polymerases that function in elongation during DNA replication in eukaryotic cells. However, the precise roles of these polymerases are still unclear. Here we comparatively analysed DNA replication in Xenopus egg extracts in which Pol, or Pol, was immunodepleted. Depletion of either polymerase resulted in a significant decrease in DNA synthesis and accumulation of short nascent DNA products, indicating an elongation defect. Moreover, Pol, depletion caused a more severe defect in elongation, as shown by sustained accumulation of both short nascent DNA products and single-stranded DNA gaps, and also by elevated chromatin binding of replication proteins that function more frequently during lagging strand synthesis. Therefore, our data strongly suggest the possibilities that Pol, is essential for lagging strand synthesis and that this function of Pol, cannot be substituted for by Pol,. [source]

Nucleotide-induced Ca2+ signaling in sustentacular supporting cells of the olfactory epithelium

GLIA, Issue 15 2008
Thomas Hassenklöver
Abstract Extracellular purines and pyrimidines are important signaling molecules acting via purinergic cell-surface receptors in neurons, glia, and glia-like cells such as sustentacular supporting cells (SCs) of the olfactory epithelium (OE). Here, we thoroughly characterize ATP-induced responses in SCs of the OE using functional Ca2+ imaging. The initial ATP-induced increase of the intracellular Ca2+ concentration [Ca2+]i always occurred in the apical part of SCs and subsequently propagated toward the basal lamina, indicating the occurrence of purinergic receptors in the apical part of SCs. The mean propagation velocity of the Ca2+ signal within SCs was 17.10 ± 1.02 ,m/s. ATP evoked increases in [Ca2+]i in both the presence and absence of extracellular Ca2+. Depletion of the intracellular Ca2+ stores abolished the responses. This shows that the ATP-induced [Ca2+]i increases were in large part, if not entirely, due to the activation of G protein-coupled receptors followed by Ca2+ mobilization from intracellular stores, suggesting an involvement of P2Y receptors. The order of potency of the applied purinergic agonists was UTP > ATP > ATP,S (with all others being only weakly active or inactive). The ATP-induced [Ca2+]i increases could be reduced by the purinergic antagonists PPADS and RB2, but not by suramin. Our findings suggest that extracellular nucleotides in the OE activate SCs via P2Y2/P2Y4 -like receptors and initiate a characteristic intraepithelial Ca2+ wave. © 2008 Wiley-Liss, Inc. [source]

Pumping-Induced Drawdown and Stream Depletion in a Leaky Aquifer System

GROUND WATER, Issue 2 2007
James J. Butler Jr
The impact of ground water pumping on nearby streams is often estimated using analytic models of the interconnected stream-aquifer system. A common assumption of these models is that the pumped aquifer is underlain by an impermeable formation. A new semianalytic solution for drawdown and stream depletion has been developed that does not require this assumption. This solution shows that pumping-induced flow (leakage) through an underlying aquitard can be an important recharge mechanism in many stream-aquifer systems. The relative importance of this source of recharge increases with the distance between the pumping well and the stream. The distance at which leakage becomes the primary component of the pumping-induced recharge depends on the specific properties of the aquifer, aquitard, and streambed. Even when the aquitard is orders of magnitude less transmissive than the aquifer, leakage can be an important recharge mechanism because of the large surface area over which it occurs. Failure to consider aquitard leakage can lead to large overestimations of both the drawdown produced by pumping and the contribution of stream depletion to the pumping-induced recharge. The ramifications for water resources management and water rights adjudication can be significant. A hypothetical example helps illustrate these points and demonstrates that more attention should be given to estimating the properties of aquitards underlying stream-aquifer systems. The solution presented here should serve as a relatively simple but versatile tool for practical assessments of pumping-induced stream-aquifer interactions. However, this solution should not be used for such assessments without site-specific data that indicate pumping has induced leakage through the aquitard. [source]

Semianalytical Solutions for Stream Depletion in Partially Penetrating Streams

GROUND WATER, Issue 1 2004
Xunhong Chen
In the analysis of streamflow depletion, the Hunt (1999) solution has an important advantage because it considers a partially penetrating stream. By extending the Hunt drawdown solution, this paper presents semianalytical solutions for gaining streams that evaluate the induced stream infiltration and base flow reduction separately. Simulation results show that for a given ,h (the initial hydraulic head difference between stream and aquifer beneath the channel), the base flow reduction is in direct proportion to the product of streambed leakage (,) and the distance between pumping well and stream (L), and the induced stream infiltration is in inverse proportion to ,L. ,h has a significant effect on the ratio of stream infiltration to base flow reduction. The results from the semianalytical solutions agree well with those from MODFLOW simulations. The semianalytical solutions are useful in the verification of numerical simulations and in the analysis of stream-aquifer interactions where water quantity or quality is concerned. [source]

Drawdown and Stream Depletion Produced by Pumping in the Vicinity of a Partially Penetrating Stream

GROUND WATER, Issue 5 2001
James J. Butler Jr.
Commonly used analytical approaches for estimation of pumping-induced drawdown and stream depletion are based on a series of idealistic assumptions about the stream-aquifer system. A new solution has been developed for estimation of drawdown and stream depletion under conditions that are more representative of those in natural systems (finite width stream of shallow penetration adjoining an aquifer of limited lateral extent). This solution shows that the conventional assumption of a fully penetrating stream will lead to a significant overestimation of stream depletion (> 100%) in many practical applications. The degree of overestimation will depend on the value of the stream leakance parameter and the distance from the pumping well to the stream. Although leakance will increase with stream width, a very wide stream will not necessarily be well represented by a model of a fully penetrating stream. The impact of lateral boundaries depends upon the distance from the pumping well to the stream and the stream leakance parameter. In most cases, aquifer width must be on the order of hundreds of stream widths before the assumption of a laterally infinite aquifer is appropriate for stream-depletion calculations. An important assumption underlying this solution is that stream-channel penetration is negligible relative to aquifer thickness. However, an approximate extension to the case of nonnegligible penetration provides reasonable results for the range of relative penetrations found in most natural systems (up to 85%). Since this solution allows consideration of a much wider range of conditions than existing analytical approaches, it could prove to be a valuable new tool for water management design and water rights adjudication purposes. [source]

Neutrophil depletion protects against murine acetaminophen hepatotoxicity,,

HEPATOLOGY, Issue 6 2006
Zhang-Xu Liu
We previously reported that liver natural killer (NK) and NKT cells play a critical role in mouse model of acetaminophen (APAP)-induced liver injury by producing interferon gamma (IFN-,) and modulating chemokine production and subsequent recruitment of neutrophils into the liver. In this report, we examined the role of neutrophils in the progression of APAP hepatotoxicity. C57BL/6 mice were given an intraperitoneal toxic dose of APAP (500 mg/kg), which caused severe acute liver injury characterized by significant elevation of serum ALT, centrilobular hepatic necrosis, and increased hepatic inflammatory cell accumulation. Flow cytometric analysis of isolated hepatic leukocytes demonstrated that the major fraction of increased hepatic leukocytes at 6 and 24 hours after APAP was neutrophils (Mac-1+Gr-1+). Depletion of neutrophils by in vivo treatment with anti-Gr-1 antibody (RB6-8C5) significantly protected mice against APAP-induced liver injury, as evidenced by markedly reduced serum ALT levels, centrilobular hepatic necrosis, and improved mouse survival. The protection was associated with decreased FasL-expressing cells, cytotoxicity against hepatocytes, and respiratory burst in hepatic leukocytes. In intracellular adhesion molecule (ICAM)-1,deficient mice, APAP caused markedly reduced liver injury when compared with wild-type mice. The marked protection in ICAM-1,deficient mice was associated with decreased accumulation of neutrophils in the liver. Hepatic GSH depletion and APAP-adducts showed no differences among the antibody-treated, ICAM-1,deficient, and normal mice. In conclusion, accumulated neutrophils in the liver contribute to the progression and severity of APAP-induced liver injury. (HEPATOLOGY 2006;43:1220,1230.) [source]

Depletion of PCBM at the Cathode Interface in P3HT/PCBM Thin Films as Quantified via Neutron Reflectivity Measurements

ADVANCED MATERIALS, Issue 22 2010
Andrew J. Parnell
Using neutron reflectivity, self-stratification in a model P3HT/PCBM blend is observed. The as-spun and solvent-annealed films show a depletion of PCBM near the top surface and enrichment of PCBM at the substrate (see figure). Depletion of PCBM at the cathode interface in a photovoltaic device could act as a barrier to efficient electron extraction. On thermal annealing, the PCBM depleted region is eliminated; an effect that partially explains the improvement of P3HT/PCBM devices on thermal annealing. [source]

Breaking the Barriers in Bio Research

IMAGING & MICROSCOPY (ELECTRONIC), Issue 1 2007
STED Superresolution Microscopy
More than 130 years ago, Ernst Abbe set up the law that far-field optical microscopes are limited in resolution to approximately half of the wavelength of light. Today, these limits have been broken by two new concepts of microscopy: 4Pi and STED (Stimulated Emission Depletion) microscopy. Both techniques are revolutionizing the biomedical research environment, by providing resolution beyond what is possible with best light microscopes today, while maintaining all advantages of structure-specific fluorescence tagging. The principles have been invented by Stefan Hell of the Max Planck Institute for Biophysical Chemistry in Goettingen, Germany, and are commercialized by Leica Microsystems CMS. While the Leica TCS 4Pi is already available, the Leica TCS STED system will be introduced to the market in 2007. [source]

Control of T-cell activation by CD4+ CD25+ suppressor T cells

IMMUNOLOGICAL REVIEWS, Issue 1 2001
Ethan M. Shevach
Summary: Depletion of the minor (,10%) subpopulation of CD4+ T cells that co-expresses CD25 (interleukin (IL)-2 receptor ,-chain) by thymectomy of neonates on the third day of life or by treatment of adult CD4+ T cells with anti-CD25 and complement results in the development of organ-specific autoimmunity. Autoimmune disease can be prevented by reconstitution of the animals with CD4+ CD25+ cells. CD4+ CD25+ -mediated protection of autoimmune gastritis does not require the suppressor cytokines IL-4, IL-10, or transforming growth factor (TGF)-,. Mice that express a transgenic T-cell receptor (TCR) derived from a thymectomized newborn that recognizes the gastric parietal cell antigen H/K ATPase all develop severe autoimmune gastritis very early in life. CD4+ CD25+ T cells are also powerful suppressors of the activation of both CD4+ and CD8+ T cells in vitro. Suppression is mediated by a cell contact-dependent, cytokine-independent T,T interaction. Activation of CD4+ CD25+ via their TCR generates suppressor effector cells that are capable of non-specifically suppressing the activation of any CD4+ or CD8+ T cell. Activation of suppressor effector function is independent of co-stimulation mediated by CD28/CTLA-4 interactions with CD80/CD86. We propose that CD4+ CD25+ T cells recognize organ-specific antigens, are recruited to sites of autoimmune damage where they are activated by their target antigen, and then physically interact with autoreactive CD4+ or CD8+ effector cells to suppress the development of autoimmune disease. [source]

Tumoricidal activity of high-dose tumor necrosis factor-, is mediated by macrophage-derived nitric oxide burst and permanent blood flow shutdown

INTERNATIONAL JOURNAL OF CANCER, Issue 2 2008
Chandrakala Menon
Abstract This study investigates the role of tumor nitric oxide (NO) and vascular regulation in tumor ulceration following high-dose tumor necrosis factor-, (TNF) treatment. Using TNF-responsive (MethA) and nonresponsive (LL2) mouse tumors, tumor NO concentration was measured with an electrochemical sensor and tumor blood flow by Doppler ultrasound. Mice were also pretreated with a selective inducible nitric oxide synthase (iNOS) inhibitor, 1400 W. Tumors harvested from TNF-treated mice were cryosectioned and immunostained for murine macrophages, or/and iNOS. MethA tumor-bearing mice were depleted of macrophages. Pre- and post-TNF tumor NO levels were measured continuously, and mice were followed for gross tumor response. In MethA tumors, TNF caused a 96% response rate, and tumor NO concentration doubled. Tumor blood flow decreased to 3% of baseline by 4 hr and was sustained at 24 hr and 10 days post-TNF. Selective NO inhibition with 1400 W blocked NO rise and decreased response rate to 38%. MethA tumors showed tumor infiltration by macrophages post-TNF and the pattern of macrophage immunostaining overlapped with iNOS immunostaining. Depletion of macrophages inhibited tumor NO increase and response to TNF. LL2 tumors had a 0% response rate to TNF and exhibited no change in NO concentration. Blood flow decreased to 2% of baseline by 4 hr, recovered to 56% by 24 hr and increased to 232% by 10 days. LL2 tumors showed no infiltration by macrophages post-TNF. We conclude that TNF causes tumor infiltrating, macrophage-derived iNOS-mediated tumor NO rise and sustained tumor blood flow shutdown, resulting in tumor ulceration in the responsive tumor. © 2008 Wiley-Liss, Inc. [source]