Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 17 de 17
Filter
1.
J Inherit Metab Dis ; 46(4): 649-661, 2023 07.
Article in English | MEDLINE | ID: mdl-36680547

ABSTRACT

Mutations in the LPIN1 gene constitute a major cause of severe rhabdomyolysis (RM). The TLR9 activation prompted us to treat patients with corticosteroids in acute conditions. In patients with LPIN1 mutations, RM and at-risk situations that can trigger RM have been treated in a uniform manner. Since 2015, these patients have also received intravenous corticosteroids. We retrospectively compared data on hospital stays by corticosteroid-treated patients vs. patients not treated with corticosteroids. Nineteen patients were hospitalized. The median number of admissions per patient was 21 overall and did not differ when comparing the 10 corticosteroid-treated patients with the 9 patients not treated with corticosteroids. Four patients in the non-corticosteroid group died during a RM (mean age at death: 5.6 years). There were no deaths in the corticosteroid group. The two groups did not differ significantly in the number of RM episodes. However, for the six patients who had RM and occasionally been treated with corticosteroids, the median number of RM episodes was significantly lower when intravenous steroids had been administered. The peak plasma creatine kinase level and the area under the curve were or tended to be higher in patients treated with corticosteroids-even after the exclusion of deceased patients or focusing on the period after 2015. The median length of stay (10 days overall) was significantly longer for corticosteroid-treated patients but was similar after the exclusion of deceased patients. The absence of deaths and the higher severity of RM observed among corticosteroid-treated patients could suggest that corticotherapy is associated with greater survival.


Subject(s)
Rhabdomyolysis , Humans , Child, Preschool , Retrospective Studies , Rhabdomyolysis/drug therapy , Rhabdomyolysis/chemically induced , Glucocorticoids , Acute Disease , Phosphatidate Phosphatase/genetics
2.
Pharm Dev Technol ; 26(3): 328-334, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33428504

ABSTRACT

Hydroxychloroquine is an antimalarial drug indicated in the treatment of acute attacks of malaria due to Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum. It is also used for the treatment of rheumatoid arthritis, discoid and systemic lupus erythematosus, and more recently proposed in COVID-19 therapy. Hydroxychloroquine is only available in tablets which are not easy to administer for pediatric and geriatric patients, and patients unable to swallow such as patients found in intensive care units. The aim of this work was to develop and optimize a ready to use liquid hydroxychloroquine formulation and to carry out the corresponding chemical and microbiological stability studies. The formulation was evaluated for ease of preparation, physical properties, and palatability. Its stability was performed at ambient temperature and under refrigeration. After 6 months of stability testing, the results showed no pH change, no drug loss, no microbial development, and no visual change. The formulation, employing excipients in a range that EMA has recommended, showed chemical and microbiological stability for at least 6 months even in the worst storage conditions.


Subject(s)
Antimalarials/chemistry , COVID-19 Drug Treatment , Hydroxychloroquine/chemistry , Chromatography, High Pressure Liquid , Drug Compounding , Drug Contamination/prevention & control , Drug Stability , Humans , Quality Control , Suspensions , Taste
3.
Br J Clin Pharmacol ; 86(10): 2063-2069, 2020 10.
Article in English | MEDLINE | ID: mdl-32250462

ABSTRACT

In X-linked hypohidrotic ectodermal dysplasia, the most frequent ectodermal dysplasia, an inherited deficiency of the signalling protein ectodysplasin A1 (EDA1) impairs the development of the skin and its appendages, various eccrine glands, and dentition. The severe hypohidrosis common to X-linked hypohidrotic ectodermal dysplasia patients may lead to life-threatening hyperthermia, especially during hot weather or febrile illness. Fc-EDA, an EDA1 replacement protein known to prevent the disease in newborn animals, was tested in 2 clinical trials (human adults and neonates) and additionally administered under compassionate use to 3 infants in utero. The data support the safety of Fc-EDA and efficacy if applied prenatally. Anti-drug antibodies were detected after intravenous administration in adult males and nonpregnant females, but not in pregnant women when Fc-EDA was delivered intra-amniotically. Most importantly, there was no detectable immune response to the investigational drug in neonates treated by intravenous infusions and in infants who had received Fc-EDA in utero. In conclusion, the safety profile of this drug encourages further development of prenatal EDA1 replacement therapy.


Subject(s)
Ectodysplasins , Immunoglobulin Fc Fragments , Adult , Animals , Female , Humans , Infant , Infant, Newborn , Male , Pregnancy , Recombinant Fusion Proteins , Research Subjects
4.
Transl Res ; 266: 57-67, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38013006

ABSTRACT

TMEM165-CDG has first been reported in 2012 and manganese supplementation was shown highly efficient in rescuing glycosylation in isogenic KO cells. The unreported homozygous missense c.928G>C; p.Ala310Pro variant leading to a functional but unstable protein was identified. This patient was diagnosed at 2 months and displays a predominant bone phenotype and combined defects in N-, O- and GAG glycosylation. We administered for the first time a combined D-Gal and Mn2+ therapy to the patient. This fully suppressed the N-; O- and GAG hypoglycosylation. There was also striking improvement in biochemical parameters and in gastrointestinal symptoms. This study offers exciting therapeutic perspectives for TMEM165-CDG.


Subject(s)
Cation Transport Proteins , Congenital Disorders of Glycosylation , Humans , Manganese/metabolism , Galactose , Antiporters/metabolism , Golgi Apparatus/genetics , Golgi Apparatus/metabolism , Cation Transport Proteins/metabolism , Congenital Disorders of Glycosylation/genetics , Congenital Disorders of Glycosylation/metabolism
5.
Plant Physiol ; 159(4): 1658-70, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22645070

ABSTRACT

Root tips of many plant species release a number of border, or border-like, cells that are thought to play a major role in the protection of root meristem. However, little is currently known on the structure and function of the cell wall components of such root cells. Here, we investigate the sugar composition of the cell wall of the root cap in two species: pea (Pisum sativum), which makes border cells, and Brassica napus, which makes border-like cells. We find that the cell walls are highly enriched in arabinose and galactose, two major residues of arabinogalactan proteins. We confirm the presence of arabinogalactan protein epitopes on root cap cell walls using immunofluorescence microscopy. We then focused on these proteoglycans by analyzing their carbohydrate moieties, linkages, and electrophoretic characteristics. The data reveal (1) significant structural differences between B. napus and pea root cap arabinogalactan proteins and (2) a cross-link between these proteoglycans and pectic polysaccharides. Finally, we assessed the impact of root cap arabinogalactan proteins on the behavior of zoospores of Aphanomyces euteiches, an oomycetous pathogen of pea roots. We find that although the arabinogalactan proteins of both species induce encystment and prevent germination, the effects of both species are similar. However, the arabinogalactan protein fraction from pea attracts zoospores far more effectively than that from B. napus. This suggests that root arabinogalactan proteins are involved in the control of early infection of roots and highlights a novel role for these proteoglycans in root-microbe interactions.


Subject(s)
Aphanomyces/cytology , Aphanomyces/growth & development , Brassica napus/metabolism , Chemotaxis/drug effects , Mucoproteins/pharmacology , Pisum sativum/metabolism , Plant Root Cap/metabolism , Aphanomyces/drug effects , Brassica napus/cytology , Brassica napus/drug effects , Brassica napus/microbiology , Cell Wall/drug effects , Cell Wall/metabolism , Chemical Precipitation , Electrophoresis, Polyacrylamide Gel , Glucosides/metabolism , Microscopy, Fluorescence , Monosaccharides/chemistry , Monosaccharides/metabolism , Mucoproteins/chemistry , Pisum sativum/cytology , Pisum sativum/drug effects , Pisum sativum/microbiology , Phloroglucinol/analogs & derivatives , Phloroglucinol/metabolism , Plant Proteins/chemistry , Plant Proteins/pharmacology , Plant Root Cap/cytology , Plant Root Cap/drug effects
6.
Biomed Pharmacother ; 163: 114813, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37150031

ABSTRACT

BACKGROUND: Lipin-1 deficiency is a life-threatening disease that causes severe rhabdomyolysis (RM) and chronic symptoms associated with oxidative stress. In the absence of treatment, Hydroxychloroquine sulfate (HCQ) was administered to patients off label use on a compassionate basis in order to improve their physical conditions. METHODS: Eleven patients with LPIN1 mutations were treated with HCQ. Clinical and biological efficacy and tolerance were assessed, including pain and quality of life, physical capacities, cardiopulmonary parameters, creatine kinase levels and plasma proinflammatory cytokines. To explore a dose-dependent effect of HCQ, primary myoblasts from 4 patients were incubated with various HCQ concentrations in growth medium (GM) or during starvation (EBSS medium) to investigate autophagy and oxidative stress. FINDINGS: Under HCQ treatment, patient physical capacities improved. Abnormal cardiac function and peripheral muscle adaptation to exercise were normalized. However, two patients who had the highest mean blood HCQ concentrations experienced RM. We hypothesized that HCQ exerts deleterious effects at high concentrations by blocking autophagy, and beneficial effects on oxidative stress at low concentrations. We confirmed in primary myoblasts from 4 patients that high in vitro HCQ concentration (10 µM) but not low concentration (1 µM and 0.1 µM) induced autophagy blockage by modifying endolysosomal pH. Low HCQ concentration (1 µM) prevented reactive oxygen species (ROS) and oxidized DNA accumulation in myoblasts during starvation. INTERPRETATION: HCQ improves the condition of patients with lipin-1 deficiency, but at low concentrations. In vitro, 1 µM HCQ decreases oxidative stress in myoblasts whereas higher concentrations have a deleterious effect by blocking autophagy.


Subject(s)
Hydroxychloroquine , Quality of Life , Humans , Hydroxychloroquine/pharmacology , Hydroxychloroquine/therapeutic use , Cytokines , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Phosphatidate Phosphatase/genetics
7.
Cell Rep Med ; 2(8): 100370, 2021 08 17.
Article in English | MEDLINE | ID: mdl-34467247

ABSTRACT

LPIN1 mutations are responsible for inherited recurrent rhabdomyolysis, a life-threatening condition with no efficient therapeutic intervention. Here, we conduct a bedside-to-bench-and-back investigation to study the pathophysiology of lipin1 deficiency. We find that lipin1-deficient myoblasts exhibit a reduction in phosphatidylinositol-3-phosphate close to autophagosomes and late endosomes that prevents the recruitment of the GTPase Armus, locks Rab7 in the active state, inhibits vesicle clearance by fusion with lysosomes, and alters their positioning and function. Oxidized mitochondrial DNA accumulates in late endosomes, where it activates Toll-like receptor 9 (TLR9) and triggers inflammatory signaling and caspase-dependent myolysis. Hydroxychloroquine blocks TLR9 activation by mitochondrial DNA in vitro and may attenuate flares of rhabdomyolysis in 6 patients treated. We suggest a critical role for defective clearance of oxidized mitochondrial DNA that activates TLR9-restricted inflammation in lipin1-related rhabdomyolysis. Interventions blocking TLR9 activation or inflammation can improve patient care in vivo.


Subject(s)
Mitochondria/metabolism , Phosphatidate Phosphatase/metabolism , Rhabdomyolysis/pathology , Autophagosomes/metabolism , Child , Child, Preschool , Chloroquine/pharmacology , DNA, Mitochondrial/metabolism , Endosomes/metabolism , Female , Follow-Up Studies , GTPase-Activating Proteins/metabolism , Humans , Inflammation/pathology , Lysosomes/metabolism , Male , Myoblasts/metabolism , Phosphatidate Phosphatase/deficiency , Phosphatidylinositol Phosphates , Signal Transduction , Toll-Like Receptor 9/metabolism , rab7 GTP-Binding Proteins/metabolism
8.
J Exp Bot ; 61(14): 3827-31, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20643806

ABSTRACT

Roots of many plants are known to produce large numbers of 'border' cells that play a central role in root protection and the interaction of the root with the rhizosphere. Unlike border cells, border-like cells were described only recently in the model plant Arabidopsis thaliana and other Brassicaceae species and very little is known about the functional properties of border-like cells as compared with 'classical' border cells. To stimulate discussion and future research on this topic, the function of border cells and the way border-like cells are organized, maintained, and possibly involved in plant protection is discussed here.


Subject(s)
Brassicaceae/cytology , Plant Roots/cytology , Arabidopsis/cytology , Brassicaceae/physiology , Cell Wall/metabolism , Plant Proteins/physiology
10.
JIMD Rep ; 51(1): 25-29, 2020 Jan.
Article in English | MEDLINE | ID: mdl-32071836

ABSTRACT

Beta-hydroxybutyrate (BHB) is a synthetic ketone body used as an adjuvant energy substrate in the treatment of patients with metabolic cardiomyopathy. A medication prescribing error led to the administration of the general anesthetic sodium gamma-hydroxybutyrate (GHB) instead of sodium BHB in a liver transplant recipient with propionic acidemia and cardiomyopathy, causing acute coma. A 15-year-old boy suffering from neonatal propionic acidemia underwent liver transplantation (LT) for metabolic decompensation and cardiomyopathy (treated with cardiotropic drugs and BHB) diagnosed a year previously. The patient had been rapidly extubated after LT, and was recovering well. Eight days after LT, the patient suddenly became comatose. No metabolic, immunological, hypertensive, or infectious complications were apparent. The brain magnetic resonance imaging and electroencephalography results were normal. The coma was soon attributed to a medication prescribing error: administration of GHB instead of BHB on day 8 post-LT. The patient recovered fully within a few hours of GHB withdrawal. The computerized prescription system had automatically suggested the referenced anesthetic GHB (administered intravenously) instead of the non-referenced ketone body BHB, triggering coma in our patient. A computerized prescription system generated a medication prescribing error for a rare disease, in which the general anesthetic GHB was mistaken for the nonreferenced energy substrate BHB.

11.
Trends Plant Sci ; 12(1): 14-9, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17157548

ABSTRACT

Plant roots release a large number of border cells into the rhizosphere, which are believed to play a key role in root development and health. The formation and loss of these cells from the root cap region is a developmentally regulated process that is also controlled by phytohormones and environmental factors. The separation of border cells involves the complete dissociation of individual cells from each other and from root tissue. This process requires the activity of cell wall-degrading enzymes that solubilize the cell wall connections between cells. We present and discuss the solubilization process with an emphasis on pectin-degrading enzymes as well as the recently discovered root border-like cells of Arabidopsis thaliana.


Subject(s)
Cell Physiological Phenomena , Plant Roots/cytology , Arabidopsis/cytology , Arabidopsis/genetics , Cell Adhesion , Gene Expression Regulation, Plant , Mutation/genetics
12.
Hum Gene Ther ; 30(6): 753-761, 2019 06.
Article in English | MEDLINE | ID: mdl-30700149

ABSTRACT

Seventy-five percent of patients with beta thalassemia (ß-thalassemia) do not have human leukocyte antigen-matched siblings and until recently had no access to a curative treatment. Gene therapy is a promising treatment that can be proposed to these patients. This study estimates its cost and efficacy. In a monocentric retrospective study and cost-efficacy analysis, this study compared the two-year outcomes and costs of patients with ß-thalassemia treated by gene therapy and hematopoietic stem-cell transplantation (HSCT). Grade III and grade IV complications, hospitalizations, and length of stay were extracted from the hospital discharge data. Costs were estimated from hospital accounting information and national cost studies. A total of seven patients with ß-thalassemia treated between 2009 and 2016 were included, of whom four received gene therapy. Patients treated by gene therapy were older and had fewer complications and hospital admissions. Infectious complications were three times more frequent for patients treated with HSCT than for gene therapy. Average costs were €608,086 for patients treated by gene therapy and €215,571 for HSCT. The total cost of the vector was 48% of the total cost of gene therapy. Gene therapy as a curative alternative for patients lacking human leukocyte antigen-matched donors was costlier but resulted in fewer complications than HSCT.


Subject(s)
Genetic Therapy , Hematopoietic Stem Cell Transplantation , beta-Thalassemia/genetics , beta-Thalassemia/therapy , Adolescent , Child , Child, Preschool , Clinical Trials as Topic , Cost-Benefit Analysis , Genetic Therapy/economics , Genetic Therapy/methods , Genetic Vectors , Graft vs Host Disease/diagnosis , Graft vs Host Disease/etiology , Health Care Costs , Hematopoietic Stem Cell Transplantation/adverse effects , Hematopoietic Stem Cell Transplantation/economics , Hematopoietic Stem Cell Transplantation/methods , Humans , Infant , Prognosis , Retrospective Studies , Tissue Donors , Transplantation, Homologous , Treatment Outcome , beta-Thalassemia/diagnosis , beta-Thalassemia/mortality
13.
Mol Ther Methods Clin Dev ; 13: 303-309, 2019 Jun 14.
Article in English | MEDLINE | ID: mdl-30911587

ABSTRACT

Although the risk of developing lymphoma has decreased in the highly active antiretroviral therapy era, this cancer remains the major cause of mortality in HIV-infected patients. Autologous hematopoietic stem cell transplantation (ASCT) outcome does not differ for HIV-infected versus HIV-uninfected patients. We propose to develop a new treatment for HIV-associated high-risk lymphoma based on autologous transplantation of two genetically modified products: CD4+ T lymphocytes and CD34+ hematopoietic stem cells (HSPCs). The cells will be transduced ex vivo with the Cal-1 lentiviral vector encoding for both a short hairpin RNA (shRNA) against CCR5 (sh5) and the HIV-1 fusion inhibitor C46. The transduced cells will be resistant to HIV infection by two complementary mechanisms: impaired binding of the virus to the cellular CCR5 co-receptor and decreased fusion of the virus as C46 interacts with gp41 and inhibits HIV infection. This phase I/II pilot study, also entitled GENHIV, will involve two French participating centers: Saint Louis Hospital and Necker Hospital in Paris. We plan to enroll five HIV-1-infected patients presenting with high-risk lymphoma and require a treatment with ASCT. The primary objective of this study is to evaluate the safety, feasibility, and success of engraftment of Cal-1 gene-transduced CD4+ T lymphocytes and CD34+ HSPCs.

14.
Meat Sci ; 72(3): 467-74, 2006 Mar.
Article in English | MEDLINE | ID: mdl-22061730

ABSTRACT

Chemical, physical and sensory aspects of quality were compared on encased rolls (1kg) prepared from single muscle beef (biceps femoris) cooked in a steam oven (80°C) or by radio frequency (RF) heating (500W, 27.12MHz) under recirculating water at 80°C. The RF protocol reduced cooking times to 23 and 31% of steam cooking times, respectively, in non-injected meat (PG1) and in rolls prepared with curing brines possessing similar dielectric properties (PG2-4). Compared to steam heating, cooking yields were significantly higher (P<0.05) and instrumental texture measurements related to toughness significantly lower (P<0.05) for RF cooked PG1 rolls and for meat injected with brines containing water binding dielectrically inactive additives (PG4) but not for brined rolls lacking the latter ingredients (PG2 and PG3). Participants in a 50 member untrained sensory panel were unable to detect texture differences which had been indicated by instrumental analysis for PG1 and PG4.

15.
Lancet Infect Dis ; 15(3): 285-92, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25662592

ABSTRACT

BACKGROUND: Human infection with the avian influenza A H5N1 virus results in disease with a high fatality rate, against which antiviral treatments have limited efficacy. We aimed to investigate the safety, pharmacokinetics, and therapeutic potential of specific polyclonal immunoglobulin equine F(ab')2 fragments raised against influenza A/Vietnam/1194/2004 virus (H5N1 subtype) in healthy volunteers. METHODS: We did a randomised, double-blind, placebo-controlled, single-centre phase 1 study. In stage 1 (one infusion) and stage 2 (five infusions) of the trial, we randomly assigned healthy male volunteers to receive once-daily intravenous infusions of 0·85 U/kg body weight of F(ab')2 or once-daily saline placebo. Randomisation was done centrally, with one block of four patients and one block for substitutes (three actives, one placebo) in stage 1, and two blocks of six patients (five actives and one placebo) and the same block for substitutes in stage 2. The primary objective was assessment of the clinical and laboratory safety of F(ab')2, which was monitored for 22 days in the group that received one dose (assessments on days 0-2, 4, 8, 15, and 22) and 33 days in the group that received five doses (days 0-6, 8, 10, 12, 19, 26, and 33). A final post-study safety assessment was done at 120 days. We also assessed pharmacokinetic outcomes, and assayed haemagglutination and seroneutralisation activity. Analysis was done according to intention-to-treat. This trial is registered with ClinicalTrials.gov, number NCT02295813. FINDINGS: We enrolled 16 healthy Asian men between Sept 28 and Dec 28, 2012, and randomly assigned 13 to one or five doses of F(ab')2 and three to placebo. F(ab')2 was well tolerated, and no deaths or serious adverse events occurred. Three patients had mild adverse events (one each of blepharospasm, sinusitis, and pyrexia). The pyrexia (38°C) was regarded as probably related to the infusion, and resolved after 37 min. Our laboratory assessments of blood and urine samples and physical examinations of heart rate, electrocardiogram readings, and weight showed no clinically significant safety issues. Mean peak plasma concentrations were 19·3 µg/mL (SD 3·5) with the one dose schedule and 23·0 µg/mL (4·5) with the five-dose schedule. F(ab')2 were still detectable in plasma on average up to 5 days after five doses. Haemagglutination inhibition was only increased after the third dose, but in-vitro seroneutralisation activity was transiently increased after each of the five doses to concentrations regarded as clinically beneficial in infected patients. INTERPRETATION: F(ab')2 showed good safety, tolerability, and therapeutic potential for managing of H5N1 exposed patients. FUNDING: Fab'entech.


Subject(s)
Antibodies, Viral/therapeutic use , Immunoglobulin Fab Fragments/therapeutic use , Influenza A Virus, H5N1 Subtype/immunology , Influenza, Human/therapy , Adult , Antibodies, Viral/adverse effects , Antibodies, Viral/blood , Antibodies, Viral/pharmacology , Double-Blind Method , Healthy Volunteers , Humans , Immunoglobulin Fab Fragments/adverse effects , Immunoglobulin Fab Fragments/blood , Immunoglobulin Fab Fragments/pharmacology , Influenza, Human/virology , Infusions, Intravenous , Male , Placebos/administration & dosage , Plasma/chemistry , Plasma/immunology
16.
J Biosci Bioeng ; 108(2): 160-7, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19619865

ABSTRACT

The effects of Na-butyrate on the physiological behaviour and on the specific productivity of recombinant tissue plasminogen activator (t-PA) Chinese Hamster Ovary (CHO) cells were characterized. Batch cultures were performed in a 3.5-L bioreactor. Na-butyrate was added either at the mid-exponential growth phase (48 h) or at the end of the exponential growth phase (74 h). The cultures with Na-butyrate showed higher net specific productivity of t-PA and lower final cell density and viability. Maximum specific productivity of t-PA for all cultures coincided with the early plateau phase (84 h). The cell's specific oxygen uptake rate (qO2) increased after the Na-butyrate addition and remained higher than that of the controlled culture. Triphosphate nucleotides, ADP, AMP and UDP-sugars all increased after 84 h in the cultures with Na-butyrate, showing different behaviours when Na-butyrate was added at 48 h or 74 h. Na-butyrate did not affect the cell's adenylate energy charge until the cell's viability started to decrease (156-168 h). The controlled culture and the culture with Na-butyrate addition, showed at 74 h, similar time trends as for purine and nucleotide ratios ((ATP+GTP)/(UTP+CTP) and UTP/ATP) with clear shifts in behaviour at 84 h and 168 h. However, the addition of Na-butyrate at 48 h resulted in damped variations of purine and nucleotide ratios in comparison to both the control culture and the culture with Na-butyrate addition at 74 h.


Subject(s)
Butyrates/pharmacology , Energy Metabolism/drug effects , Recombinant Proteins/biosynthesis , Tissue Plasminogen Activator/biosynthesis , Animals , CHO Cells , Cell Culture Techniques , Cricetinae , Cricetulus , Humans , Nucleotides/metabolism , Time Factors
17.
Plant Physiol ; 150(3): 1411-21, 2009 Jul.
Article in English | MEDLINE | ID: mdl-19448034

ABSTRACT

Border-like cells are released by Arabidopsis (Arabidopsis thaliana) root tips as organized layers of several cells that remain attached to each other rather than completely detached from each other, as is usually observed in border cells of many species. Unlike border cells, cell attachment between border-like cells is maintained after their release into the external environment. To investigate the role of cell wall polysaccharides in the attachment and organization of border-like cells, we have examined their release in several well-characterized mutants defective in the biosynthesis of xyloglucan, cellulose, or pectin. Our data show that among all mutants examined, only quasimodo mutants (qua1-1 and qua2-1), which have been characterized as producing less homogalacturonan, had an altered border-like cell phenotype as compared with the wild type. Border-like cells in both lines were released as isolated cells separated from each other, with the phenotype being much more pronounced in qua1-1 than in qua2-1. Further analysis of border-like cells in the qua1-1 mutant using immunocytochemistry and a set of anti-cell wall polysaccharide antibodies showed that the loss of the wild-type phenotype was accompanied by (1) a reduction in homogalacturonan-JIM5 epitope in the cell wall of border-like cells, confirmed by Fourier transform infrared microspectrometry, and (2) the secretion of an abundant mucilage that is enriched in xylogalacturonan and arabinogalactan-protein epitopes, in which the cells are trapped in the vicinity of the root tip.


Subject(s)
Arabidopsis/cytology , Cell Wall/metabolism , Pectins/metabolism , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis Proteins/genetics , Cell Wall/genetics , Galactans/metabolism , Glucans/analysis , Hexosyltransferases/genetics , Hexuronic Acids/metabolism , Immunohistochemistry , Mutation , Pectins/analysis , Pectins/genetics , Phenotype , Plant Roots/cytology , Plant Roots/genetics , Plant Roots/metabolism , Spectroscopy, Fourier Transform Infrared , Xylans/analysis
SELECTION OF CITATIONS
SEARCH DETAIL