Early ossicle growth in the regenerating disc of a brittle star

1994 ◽  
Vol 52 ◽  
pp. 364-365
Author(s):  
M. Shlepr ◽  
R. L. Turner
Keyword(s):  
Cell Membrane ◽  
Light Microscopy ◽  
De Novo ◽  
Current Model ◽  
Syncytium Formation ◽  
Brittle Star ◽  
Intracellular Location ◽  
Limited Volume ◽  
Tissue Calcification

Calcification in the echinoderms occurs within a limited-volume cavity enclosed by cytoplasmic extensions of the mineral depositing cells, the sclerocytes. The current model of this process maintains that the sheath formed from these cytoplasmic extensions is syncytial. Prior studies indicate that syncytium formation might be dependent on sclerocyte density and not required for calcification. This model further envisions that ossicles formed de novo nucleate and grow intracellularly until the ossicle effectively outgrows the vacuole. Continued ossicle growth occurs within the sheath but external to the cell membrane. The initial intracellular location has been confirmed only for elements of the echinoid tooth.The regenerating aboral disc integument of ophiophragmus filograneus was used to test the current echinoderm calcification model. This tissue is free of calcite fragments, thus avoiding questions of cellular engulfment, and ossicles are formed de novo. The tissue calcification pattern was followed by light microscopy in both living and fixed preparations.

scholarly journals Lipid synthesis in human erythroid cells: the effect of sickling

Blood ◽  
1976 ◽  
Vol 47 (2) ◽  
pp. 189-195 ◽  
Author(s):  
TA Lane ◽  
SK Ballas ◽  
ER Burka
Keyword(s):  
Cell Membrane ◽  
Neutral Lipid ◽  
Sickle Cell Anemia ◽  
De Novo ◽  
Membrane Lipids ◽  
Membrane Damage ◽  
Lipid Synthesis ◽  
Membrane Lipid ◽  
Erythroid Cell ◽  
Cell Membrane Damage

Abstract Human reticulocytes are capable of synthesizing membrane lipids from 14C-glycerol de novo. In both sickle and nonsickle reticulocytes the majority of 14C-glycerol was incorporated into phospholipids, primarily phosphatidylserine and phosphatidylcholine. Incorporation into sphingomyelin was minimal. The most abundant neutral lipid synthesized was triglyceride. In the absence of sickling, the rate of lipid synthesis in sickle reticulocytes was similar to that of nonsickle reticulocytes. With the induction of sickling under anoxic conditions sickle reticulocytes showed a prompt increase in the rate of lipid synthesis to an average of 69% above control values, while nonsickle reticulocytes under similar conditions decreased the rate of lipid synthesis. An increase in the rate of membrane lipid synthesis is associated in the mammalian erythroid cell with cell membrane damage. The findings further confirm that lesions of the erythroid cell membrane in sickle cell anemia are secondary to the sickling process itself.

scholarly journals Locations and contributions of the phosphotransferases EPT1 and CEPT1 to the biosynthesis of ethanolamine phospholipids

2020 ◽  
Vol 61 (8) ◽  
pp. 1221-1231 ◽  
Author(s):  
Yasuhiro Horibata ◽  
Hiromi Ando ◽  
Hiroyuki Sugimoto
Keyword(s):  
Fatty Acids ◽  
De Novo ◽  
Brefeldin A ◽  
Hek293 Cells ◽  
Intracellular Location ◽  
De Novo Biosynthesis ◽  
Substrate Preferences ◽  
Ethanolamine Phosphate ◽  
Immunohistochemical Analyses

The final step of the CDP-ethanolamine pathway is catalyzed by ethanolamine phosphotransferase 1 (EPT1) and choline/EPT1 (CEPT1). These enzymes are likely involved in the transfer of ethanolamine phosphate from CDP-ethanolamine to lipid acceptors such as 1,2-diacylglycerol (DAG) for PE production and 1-alkyl-2-acyl-glycerol (AAG) for the generation of 1-alkyl-2-acyl-glycerophosphoethanolamine. Here, we investigated the intracellular location and contribution to ethanolamine phospholipid (EP) biosynthesis of EPT1 and CEPT1 in HEK293 cells. Immunohistochemical analyses revealed that EPT1 localizes to the Golgi apparatus and CEPT1 to the ER. We created EPT1-, CEPT1-, and EPTI-CEPT1-deficient cells, and labeling of these cells with radio- or deuterium-labeled ethanolamine disclosed that EPT1 is more important for the de novo biosynthesis of 1-alkenyl-2-acyl-glycerophosphoethanolamine than is CEPT1. EPT1 also contributed to the synthesis of PE species containing the fatty acids 36:1, 36:4, 38:5, 38:4, 38:3, 40:6, 40:5, and 40:4. In contrast, CEPT1 was important for PE formation from shorter fatty acids such as 32:2, 32:1, 34:2, and 34:1. Brefeldin A treatment did not significantly affect the levels of the different PE species, indicating that the subcellular localization of the two enzymes is not responsible for their substrate preferences. In vitro enzymatic analysis revealed that EPT1 prefers AAG 16–20:4 > DAG 18:0–20:4 > DAG 16:0–18:1 = AAG 16–18:1 as lipid acceptors and that CEPT1 greatly prefers DAG 16:0–18:1 to other acceptors. These results suggest that EPT1 and CEPT1 differ in organelle location and are responsible for the biosynthesis of distinct EP species.

scholarly journals Developmental transcriptomics of the brittle star Amphiura filiformis reveals gene regulatory network rewiring in echinoderm larval skeleton evolution

2017 ◽  
Author(s):  
David Dylus ◽  
Liisa M. Blowes ◽  
Anna Czarkwiani ◽  
Maurice R. Elphick ◽  
Paola Oliveri
Keyword(s):  
Gene Regulatory Network ◽  
Regulatory Network ◽  
De Novo ◽  
Sea Urchins ◽  
Brittle Star ◽  
Stages Of Development ◽  
Sequence Alignments ◽  
Amphiura Filiformis ◽  
Gene Regulatory ◽  
Network Rewiring

ABSTRACTAmongst the echinoderms the class Ophiuroidea is of particular interest for its phylogenetic position, ecological importance, developmental and regenerative biology. However, compared to other echinoderms, notably echinoids (sea urchins), relatively little is known about developmental changes in gene expression in ophiuroids. To address this issue we have generated and assembled a large RNAseq data set of four key stages of development in the brittle star Amphiura filiformis and a de novo reference transcriptome of comparable quality to that of a model echinoderm - the sea urchin Strongyloncentrotus purpuratus. Furthermore, we provide access to the new data via a web interface: http://www.echinonet.eu/shiny/Amphiura_filiformis/. With a focus on skeleton development, we have identified highly conserved genes associated with the development of a biomineralized skeleton. We also identify important class-specific characters, including the independent duplication of the msp130 class of genes in different echinoderm classes and the unique occurrence of spicule matrix (sm) genes in echinoids. Using a new quantification pipeline for our de novo transcriptome, validated with other methodologies, we find major differences between brittle stars and sea urchins in the temporal expression of many transcription factor genes. This divergence in developmental regulatory states is more evident in early stages of development when cell specification begins, than when cells initiate differentiation. Our findings indicate that there has been a high degree of gene regulatory network rewiring in the evolution of echinoderm larval development.Data DepositionsAll sequence reads are available at Genbank SRR4436669 - SRR4436674. Any sequence alignments used are available by the corresponding author upon request.

scholarly journals Insights into the Relationship between Cobamide Synthase and the Cell Membrane

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Victoria L. Jeter ◽  
Jorge C. Escalante-Semerena
Keyword(s):  
Cell Membrane ◽  
Membrane Protein ◽  
Lipid Bilayer ◽  
De Novo ◽  
Integral Membrane Protein ◽  
Phospholipid Bilayer ◽  
Multienzyme Complex ◽  
Coenzyme B ◽  
Lower Ligand

ABSTRACT Cobamides are cobalt-containing cyclic tetrapyrroles used by cells from all domains of life but only produced de novo by some bacteria and archaea. The “late steps” of the adenosylcobamide biosynthetic pathway are responsible for the assembly of the nucleotide loop and are required during de novo synthesis and precursor salvaging. These steps are characterized by activation of the corrin ring and lower ligand base, condensation of the activated precursors to adenosylcobamide phosphate, and removal of the phosphate, yielding a complete adenosylcobamide molecule. The condensation of the activated corrin ring and lower ligand base is performed by an integral membrane protein, cobamide (5′ phosphate) synthase (CobS), and represents an important convergence of two pathways necessary for nucleotide loop assembly. Interestingly, membrane association of this penultimate step is conserved among all cobamide producers, yet the physiological relevance of this association is not known. Here, we present the purification and biochemical characterization of the CobS enzyme of the enterobacterium Salmonella enterica subsp. enterica serovar Typhimurium strain LT2, investigate its association with liposomes, and quantify the effect of the lipid bilayer on its enzymatic activity and substrate affinity. We report a purification scheme that yields pure CobS protein, allowing in vitro functional analysis. Additionally, we report a method for liposome reconstitution of CobS, allowing for physiologically relevant studies of this inner membrane protein in a phospholipid bilayer. In vitro and in vivo data reported here expand our understanding of CobS and the implications of membrane-associated adenosylcobamide biosynthesis. IMPORTANCE Salmonella is a human pathogen of worldwide importance, and coenzyme B12 is critical for the pathogenic lifestyle of this bacterium. The importance of the work reported here lies on the improvements to the methodology used to isolate cobamide synthase, a polytopic integral membrane protein that catalyzes the penultimate step of coenzyme B12 biosynthesis. This advance is an important step in the analysis of the proposed multienzyme complex responsible for the assembly of the nucleotide loop during de novo coenzyme B12 biosynthesis and for the assimilation of incomplete corrinoids from the environment. We proposed that cobamide synthase is likely localized to the cell membrane of every coenzyme B12-producing bacterium and archaeum sequenced to date. The new knowledge of cobamide synthase advances our understanding of the functionality of the enzyme in the context of the lipid bilayer and sets the foundation for the functional-structural analysis of the aforementioned multienzyme complex.

82 EXPRESSION OF CELL MEMBRANE Mg2+ INORGANIC PHOSPHATE CHANNELS IN THE HUMAN PLACENTA DERIVED FROM PREGNANT WOMEN AND HUMAN PLACENTAL CELL LINES (BeWo, JEG3, hPC)

2012 ◽  
Vol 24 (1) ◽  
pp. 153
Author(s):  
H. Yang ◽  
S. H. Hyun ◽  
E. B. Jeung
Keyword(s):  
Cell Membrane ◽  
Cell Lines ◽  
Human Placenta ◽  
Hormonal Regulation ◽  
Inorganic Phosphate ◽  
Transient Receptor Potential ◽  
De Novo ◽  
First Trimester ◽  
Placental Cell ◽  
Major Function

Preeclampsia is a pregnancy-specific disease characterised by de novo development of concurrent hypertension and oxidative stress in the placenta. The human placenta is a highly vascularized organ whose major function is to allow maternal–fetal exchange of solutes such as Ca2+ and oxygen. The transient receptor potential cation channel subfamily is known to contain channels activated by such various stimuli as intracellular Ca2+ membrane potential, cold and pH. However, signalling mechanisms mediating hormonal regulation of Mg2+ inorganic phosphate channels during the placenta duration of pregnancy are incompletely understood. We examined the expression of cell membrane Mg2+ inorganic channels in 3 sections (fetal-, central-, maternal-) of preeclamptic placenta (PEP) and from placental cell lines, BeWo, JEG3 and hPC (isolated during the first trimester) by real-time PCR and Western blot analysis. Placental tissues (∼3 cm) from women (n = 75) between the ages of 28 to 45 years undergoing normal or Caesarean delivery were dissected into 1-cm sections. Data were analysed by one-way ANOVA, followed by Tukey's multiple comparison test. P < 0.05 was considered to be statistically significant. During preterm labour, human placental expression of Mg2+ inorganic channel mRNA and protein fluctuated in the 3 sections of PEP compared with normal placenta. In hPC, the expression of Mg2+ inorganic channel (TRPM6/7, MagT1, NIPA2, SLC41A1 to 3 and SLC34A1 to 3) mRNA and protein were decreased in placental cell lines by hypoxic stress (2% O2/93% N2/5% CO2) compared with normoxia (20% O2/75% N2/5% CO2). The levels of Mg2+ inorganic channel mRNA and protein were distinctly expressed between BeWo and JEG3 cells. These results indicate that placental Mg2+ inorganic channels play potential roles in differential sections of placenta between normal and PEP, suggesting that induced Mg2+ inorganic channels of PEP may be involved in preeclamptic stress in human placenta and placental cell lines, which are a determinant factor affecting calcium transfer.

De novo transcriptome of the European brittle star Amphiura filiformis pluteus larvae

2015 ◽  
Vol 23 ◽  
pp. 109-121 ◽  
Author(s):  
Jérôme Delroisse ◽  
Olga Ortega-Martinez ◽  
Sam Dupont ◽  
Jérôme Mallefet ◽  
Patrick Flammang
Keyword(s):  
De Novo ◽  
Brittle Star ◽  
De Novo Transcriptome ◽  
Amphiura Filiformis

scholarly journals Transient CD4+T Cell Depletion Results in Delayed Development of Functional Vaccine-Elicited Antibody Responses

2016 ◽  
Vol 90 (9) ◽  
pp. 4278-4288 ◽  
Author(s):  
Nicholas M. Provine ◽  
Alexander Badamchi-Zadeh ◽  
Christine A. Bricault ◽  
Pablo Penaloza-MacMaster ◽  
Rafael A. Larocca ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Specific Antibody ◽  
De Novo ◽  
Current Model ◽  
Critical Role ◽  
T Cell Responses ◽  
Antibody Responses ◽  
Cell Responses ◽  
T Cell Help

ABSTRACTWe have recently demonstrated that CD4+T cell help is required at the time of adenovirus (Ad) vector immunization for the development of functional CD8+T cell responses, but the temporal requirement for CD4+T cell help for the induction of antibody responses remains unclear. Here we demonstrate that induction of antibody responses in C57BL/6 mice can occur at a time displaced from the time of Ad vector immunization by depletion of CD4+T cells. Transient depletion of CD4+T cells at the time of immunization delays the development of antigen-specific antibody responses but does not permanently impair their development or induce tolerance against the transgene. Upon CD4+T cell recovery, transgene-specific serum IgG antibody titers develop and reach a concentration equivalent to that in undepleted control animals. These delayed antibody responses exhibit no functional defects with regard to isotype, functional avidity, expansion after boosting immunization, or the capacity to neutralize a simian immunodeficiency virus (SIV) Env-expressing pseudovirus. The development of this delayed transgene-specific antibody response is temporally linked to the expansion ofde novoantigen-specific CD4+T cell responses, which develop after transient depletion of CD4+T cells. These data demonstrate that functional vaccine-elicited antibody responses can be induced even if CD4+T cell help is provided at a time markedly separated from the time of vaccination.IMPORTANCECD4+T cells have a critical role in providing positive help signals to B cells, which promote robust antibody responses. The paradigm is that helper signals must be provided immediately upon antigen exposure, and their absence results in tolerance against the antigen. Here we demonstrate that, in contrast to the current model that the absence of CD4+T cell help at priming results in long-term antibody nonresponsiveness, antibody responses can be induced by adenovirus vector immunization or alum-adjuvanted protein immunization even if CD4+T cell help is not provided until >1 month after immunization. These data demonstrate that the time when CD4+T cell help signals must be provided is more dynamic and flexible than previously appreciated. These data suggest that augmentation of CD4+T cell helper function even after the time of vaccination can enhance vaccine-elicited antibody responses and thereby potentially enhance the immunogenicity of vaccines in immunocompromised individuals.

scholarly journals Discovery of tumoricidal DNA oligonucleotides by effect-directedin-vitroevolution

2019 ◽  
Author(s):  
Noam Mamet ◽  
Yaniv Amir ◽  
Erez Lavi ◽  
Liron Bassali ◽  
Gil Harari ◽  
...  
Keyword(s):  
Drug Discovery ◽  
De Novo ◽  
Ex Vivo ◽  
Binding Capacity ◽  
Biological Effects ◽  
Current Model ◽  
Target Cells ◽  
Dna Oligonucleotides

AbstractOur current model of drug discovery is challenged by the relative ineffectiveness of drugs against highly variable and rapidly evolving diseases and their relatively high incidence of adverse effects due to poor selectivity. Here we describe a robust and reproducible platform which could potentially address these limitations. The platform enables rapid,de-novodiscovery of DNA oligonucleotides evolvedin-vitroto exert specific biological effects on target cells. Unlike aptamers, which are selected by their ligand binding capacity, this platform is driven directly by therapeutic effect and selectivity towards target vs negative target cells. The process could, therefore, operate without anya-prioriknowledge (e.g. mutations, biomarker expression, or known drug resistance) of the target. We report the discovery of DNA oligonucleotides with direct and selective cytotoxicity towards several tumor cell lines as well as primary, patient-derived solid and hematological tumors, some with chemotherapy resistance. Oligonucleotides discovered by this platform exhibited favorable biodistribution in animals, persistence in target tumors up to 48 hours after injection, and safety in human blood. These oligonucleotides showed remarkable efficacyin-vivoas well asex-vivoin freshly obtained, 3D cultured human tumors resistant to multiple chemotherapies. With further improvement, these findings could lead to a drug discovery model which is target-tailored, mechanism-flexible, and nearly on-demand.

scholarly journals A single de novo substitution in SARS-CoV-2 spike informs enhanced adherence to human ACE2.

2021 ◽  
Author(s):  
Elena Erausquin ◽  
Jacinto Lopez-Sagaseta
Keyword(s):  
Amino Acid ◽  
Cell Membrane ◽  
Receptor Binding ◽  
De Novo ◽  
Binding Domain ◽  
Host Cells ◽  
Structural Basis ◽  
Receptor Binding Domain ◽  
To Come ◽  
Single Substitution

SARS-CoV-2 initiates colonization of host cells by binding to cell membrane ACE2 receptor. This binding is mediated by the viral spike receptor binding domain (RBD). The COVID-19 pandemic has brought devastating consequences at a clinical, social and economical levels. Therefore, anticipation of potential novel SARS-causing species or SARS-CoV-2 variants with enhanced binding to ACE2 is key in the prevention of future threats to come. We have characterized a de novo single substitution, Q498Y, in SARS-CoV-2 RBD that confers stronger adherence to ACE2. While the SARS-CoV-2 beta variant, which includes three simultaneous amino acid replacements, induces a 4-fold stronger affinity, a single Q498Y substitution results in 2.5-fold tighter binding, compared to the Wuhan-Hu-1 SARS-CoV-2 2019 strain. Additionally, we crystallized RBDQ498Y complexed with ACE2 and provide here the structural basis for this enhanced affinity. These studies inform a rationale for prevention of potential SARS-causing viruses to come.

Comparative analysis of crystalline lens gap junctions

1984 ◽  
Vol 42 ◽  
pp. 114-117
Author(s):  
J.R. Kuszak ◽  
Y.H. Shek ◽  
K.C. Carney ◽  
J.L. Rae
Keyword(s):  
Comparative Analysis ◽  
Cell Membrane ◽  
Gap Junctions ◽  
Gap Junction ◽  
Transmembrane Proteins ◽  
Crystalline Lens ◽  
Species Variation ◽  
Intracellular Location ◽  
Fiber Cells ◽  
Electrophysiological Studies

In freeze-etch replicas, gap junctions are identifiable on PF faces as raised plaques of membrane with aggregated hexameric transmembrane proteins. On EF faces, gap junctions are seen as imprinted membrane plaques that have pits corresponding to the connexons of the gap junction from the previously conjoined cell. By these criteria, several investigators have demonstrated that gap junctions are more numerous between fiber cells of the crystalline lens than between cells of any other organ. A review of this literature suggests that there is considerable species variation in the percent of fiber cell membrane specialized as gap junction in crystalline lenses. In electrophysiological studies, cells are considered to be electrotonically coupled to one another if an intracellular potential change can be elicited at essentially all locations when current is applied at a single intracellular location. Electrotonic coupling is presumed to be mediated by gap junctions.

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