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1.
J Biophotonics ; 17(1): e202300079, 2024 01.
Article in English | MEDLINE | ID: mdl-37725434

ABSTRACT

During thyroid surgery fast and reliable intra-operative pathological feedback has the potential to avoid a two-stage procedure and significantly reduce health care costs in patients undergoing a diagnostic hemithyroidectomy (HT). We explored higher harmonic generation (HHG) microscopy, which combines second harmonic generation (SHG), third harmonic generation (THG), and multiphoton excited autofluorescence (MPEF) for this purpose. With a compact, portable HHG microscope, images of freshly excised healthy tissue, benign nodules (follicular adenoma) and malignant tissue (papillary carcinoma, follicular carcinoma and spindle cell carcinoma) were recorded. The images were generated on unprocessed tissue within minutes and show relevant morphological thyroid structures in good accordance with the histology images. The thyroid follicle architecture, cells, cell nuclei (THG), collagen organization (SHG) and the distribution of thyroglobulin and/or thyroid hormones T3 or T4 (MPEF) could be visualized. We conclude that SHG/THG/MPEF imaging is a promising tool for clinical intraoperative assessment of thyroid tissue.


Subject(s)
Microscopy , Thyroid Gland , Humans , Thyroid Gland/diagnostic imaging , Thyroid Gland/pathology , Collagen , Microscopy, Fluorescence, Multiphoton/methods
2.
World J Surg ; 47(5): 1211-1218, 2023 05.
Article in English | MEDLINE | ID: mdl-36303039

ABSTRACT

INTRODUCTION: The 2015 American Thyroid Association guidelines recommend to de-escalate treatment such as Thyroid lobectomy instead of total thyroidectomy for 1-4 cm papillary thyroid cancer (PTC). Dutch guidelines endorse restricted work-up for thyroid incidentalomas recommending only fine needle aspiration in case of a 'palpable thyroid nodule'. This diagnostic work-up algorithm may result in the identification of less indolent PTCs and may lead to a patient population with relatively more aggressive PTCs. This study aims to retrospectively analyze recurrence rates of low-risk 1-4 cm PTC in the Netherlands. METHODS: From the national cancer registry, patients with low-risk 1-4 cm PTC between 2005 and 2015 were included for analysis. Disease free survival (DFS) and overall survival were compared between patients who underwent TT ± RAI and TL without RAI. Post-hoc propensity score analysis was performed correcting for age, sex, T-stage, and N-stage. RESULTS: In total 901 patients were included, of which 711 (78.9%) were females, with a median follow-up of 7.7 years. TT was performed in 893 (94.8%) patients. Recurrence occurred in 23 (2.6%) patients. Multivariable analysis showed no significant correlation between extent of surgery and DFS (p = 0.978), or overall survival (p = 0.590). After propensity score matching, multivariable analysis showed no significant difference on extent of surgery and recurrence. CONCLUSION: Low-risk PTC patients with 1-4 cm tumor who underwent TL showed similar recurrence rates as those who underwent TT ± adjuvant RAI, which suggests that TL can be sufficient in treating low-risk 1-4 cm PTC, possibly reducing morbidity of these patients in the Netherlands.


Subject(s)
Thyroid Neoplasms , Thyroidectomy , Female , Humans , Male , Neoplasm Recurrence, Local/epidemiology , Neoplasm Recurrence, Local/surgery , Retrospective Studies , Thyroid Cancer, Papillary/diagnosis , Thyroid Cancer, Papillary/surgery , Thyroid Neoplasms/diagnosis , Thyroid Neoplasms/surgery , Thyroid Neoplasms/pathology , Thyroidectomy/methods
3.
BJS Open ; 2020 Oct 06.
Article in English | MEDLINE | ID: mdl-33022150

ABSTRACT

BACKGROUND: Evidence for limiting the extent of surgery in patients with low-risk thyroid cancer is lacking. METHODS: A systematic search was performed according to the PRISMA and MOOSE guidelines to assess the effect of total thyroidectomy (TT) with or without radioactive iodine (RAI) treatment versus hemithyroidectomy (HT) on recurrence and overall mortality in patients with differentiated (papillary or follicular) T1-2 N0 thyroid cancer. PubMed, Embase and Cochrane databases were searched, and two authors independently assessed the articles. RESULTS: A total of ten eligible articles were identified. All were observational cohort series, representing a total of 23 134 patients, of which 17 699 were available for meta-analysis. Six studies included patients who had TT followed by RAI treatment. The pooled recurrence rate after TT ± RAI and HT was 2·3 and 2·8 per cent respectively (odds ratio (OR) 1·12, 95 per cent c.i. 0·82 to 1·53; P = 0·48). The pooled 20-year overall survival rate after TT ± RAI was 96·8 per cent, compared with 97·4 per cent for HT (OR 1·30, 0·71 to 2·37; P = 0·40). Overall, higher complication rates were found in the TT ± RAI group. CONCLUSION: Recurrence rates after HT for treatment of well differentiated T1-2 N0 thyroid cancer were similar to those after TT ± RAI, with a lower incidence of treatment-related complications.


ANTECEDENTES: No hay evidencia para limitar la extensión de la cirugía en pacientes con cáncer de tiroides de bajo riesgo. MÉTODOS: Se realizó una búsqueda sistemática siguiendo las recomendaciones PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) y MOOSE (Meta-analysis of Observational Studies in Epidemiology) para evaluar el efecto de la tiroidectomía total (TT) +/− yodo radioactivo (radioactive iodine treatment, RAI) versus hemitiroidectomía (HT) en la recidiva y en la mortalidad global en el cáncer de tiroides diferenciado (papilar/folicular) T1-T2N0. Se realizaron búsquedas en las bases de datos PubMed, Embase y Cochrane, y dos autores evaluaron los artículos de forma independiente. RESULTADOS: Se identificaron un total de 10 artículos de interés. Todos ellos eran estudios de cohortes observacionales, con un total de 23.134 pacientes, de los cuales 17.699 se incluyeron en el metaanálisis. En seis estudios, los pacientes fueron tratados mediante TT seguida de RAI. Las tasas agrupadas de recidiva tras TT +/− RAI y HT fueron 2,3% and 2,8%, respectivamente (razón de oportunidades, odds ratio, OR = 1,12, i.c. del 95% 0,82-1,54, P = 0.48). La supervivencia global a 20 años de TT +/− RAI fue del 96,8% en comparación con el 97,4% para la HT (OR = 1,30, i.c. del 95% 0,71-2,37, P = 0,40). Globalmente, se observaron más complicaciones en el grupo de TT +/− RAI. CONCLUSIÓN: Esta revisión sistemática con metaanálisis demuestra tasas de recidiva similares tras una HT para el tratamiento del cáncer de tiroides T1-2N0 bien diferenciado en comparación con TT +/− RAI, con una menor incidencia de complicaciones relacionadas con el tratamiento.

4.
Genome Announc ; 5(3)2017 Jan 19.
Article in English | MEDLINE | ID: mdl-28104651

ABSTRACT

The microalgae Tetradesmus obliquus is able to maintain a high photosynthetic efficiency under nitrogen limitation and is considered a promising green microalgae for sustainable production of diverse compounds, including biofuels. Here, we report the first draft whole-genome shotgun sequencing of T. obliquus The final assembly comprises 108,715,903 bp with over 1,368 scaffolds.

5.
Biotechnol Biofuels ; 8: 150, 2015.
Article in English | MEDLINE | ID: mdl-26388937

ABSTRACT

BACKGROUND: The development of biological processes that replace the existing petrochemical-based industry is one of the biggest challenges in biotechnology. Aspergillus niger is one of the main industrial producers of lignocellulolytic enzymes, which are used in the conversion of lignocellulosic feedstocks into fermentable sugars. Both the hydrolytic enzymes responsible for lignocellulose depolymerisation and the molecular mechanisms controlling their expression have been well described, but little is known about the transport systems for sugar uptake in A. niger. Understanding the transportome of A. niger is essential to achieve further improvements at strain and process design level. Therefore, this study aims to identify and classify A. niger sugar transporters, using newly developed tools for in silico and in vivo analysis of its membrane-associated proteome. RESULTS: In the present research work, a hidden Markov model (HMM), that shows a good performance in the identification and segmentation of functionally validated glucose transporters, was constructed. The model (HMMgluT) was used to analyse the A. niger membrane-associated proteome response to high and low glucose concentrations at a low pH. By combining the abundance patterns of the proteins found in the A. niger plasmalemma proteome with their HMMgluT scores, two new putative high-affinity glucose transporters, denoted MstG and MstH, were identified. MstG and MstH were functionally validated and biochemically characterised by heterologous expression in a S. cerevisiae glucose transport null mutant. They were shown to be a high-affinity glucose transporter (K m = 0.5 ± 0.04 mM) and a very high-affinity glucose transporter (K m = 0.06 ± 0.005 mM), respectively. CONCLUSIONS: This study, focusing for the first time on the membrane-associated proteome of the industrially relevant organism A. niger, shows the global response of the transportome to the availability of different glucose concentrations. Analysis of the A. niger transportome with the newly developed HMMgluT showed to be an efficient approach for the identification and classification of new glucose transporters.

6.
Mol Genet Genomics ; 267(2): 218-22, 2002 Apr.
Article in English | MEDLINE | ID: mdl-11976965

ABSTRACT

Using EST sequence information available from the filamentous fungus Aspergillus nidulans as a starting point, we have cloned the prolidase-encoding gene, designated pepP. Introduction of multiple copies of this gene into the A. nidulansgenome leads to overexpression of an intracellular prolidase activity. Prolidase was subsequently purified and characterised from an overexpressing strain. The enzyme activity is dependent on manganese as a cofactor, is specific for dipeptides and hydrolyses only dipeptides with a C-terminal proline residue. Although these proline dipeptides are released both intracellularly and extracellularly, prolidase activity was detected only intracellularly.


Subject(s)
Aspergillus nidulans/enzymology , Aspergillus nidulans/genetics , Dipeptidases/genetics , Dipeptidases/metabolism , Genes, Fungal , Base Sequence , Cloning, Molecular , DNA, Fungal/genetics , Dipeptides/chemistry , Dipeptides/metabolism , Gene Expression , Kinetics , Molecular Sequence Data , Phylogeny , Substrate Specificity
7.
J Photochem Photobiol B ; 64(1): 69-74, 2001 Nov 01.
Article in English | MEDLINE | ID: mdl-11705732

ABSTRACT

Total cyclic-3'-5'-adenosine monophosphate (cAMP) levels were measured in the gametophyte of the red macroalga Porphyra leucosticta under different light conditions in order to study its regulation by phytochrome or photosynthesis. cAMP levels were relatively low when samples were incubated in darkness, or exposed to red or far-red light. Irradiation with red+far-red light induced a moderate increase in cAMP levels, while white light induced a pronounced increase in cAMP levels. When incubated under increasing white light irradiance, cAMP levels closely followed the increase in photosynthetic oxygen evolution rate, suggesting a direct relationship between photosynthesis and cAMP accumulation. cAMP levels were not dependent on cellular ATP concentration, as inhibitors of ATP synthesis did not significantly affect cAMP levels in light. We conclude that cAMP depends on photosynthetic activity regardless of ATP synthesis and concentration or phytochrome activity.


Subject(s)
Cyclic AMP/metabolism , Light , Rhodophyta/radiation effects , Adenosine Triphosphate/metabolism , Cells, Cultured , Kinetics , Lighting , Photosynthesis/radiation effects , Phytochrome/metabolism , Phytochrome/radiation effects , Rhodophyta/metabolism
8.
EMBO J ; 20(16): 4341-8, 2001 Aug 15.
Article in English | MEDLINE | ID: mdl-11500361

ABSTRACT

A new Dictyostelium discoideum cyclase gene was identified that encodes a protein (sGC) with 35% similarity to mammalian soluble adenylyl cyclase (sAC). Gene disruption of sGC has no effect on adenylyl cyclase activity and results in a >10-fold reduction in guanylyl cyclase activity. The scg- null mutants show reduced chemotactic sensitivity and aggregate poorly under stringent conditions. With Mn(2+)/GTP as substrate, most of the sGC activity is soluble, but with the more physiological Mg(2+)/GTP the activity is detected in membranes and stimulated by GTPgammaS. Unexpectedly, orthologues of sGC and sAC are present in bacteria and vertebrates, but absent from Drosophila melanogaster, Caenorhabditis elegans, Arabidopsis thaliana and Saccharomyces cerevisiae.


Subject(s)
Adenylyl Cyclases/genetics , Dictyostelium/enzymology , Guanylate Cyclase/genetics , Adenylyl Cyclases/classification , Adenylyl Cyclases/metabolism , Amino Acid Sequence , Animals , Catalytic Domain , Dictyostelium/genetics , Guanylate Cyclase/classification , Guanylate Cyclase/metabolism , Humans , Mammals , Molecular Sequence Data , Phenotype , Phylogeny , Sequence Homology, Amino Acid , Solubility
9.
Dev Biol ; 234(1): 151-60, 2001 Jun 01.
Article in English | MEDLINE | ID: mdl-11356026

ABSTRACT

cAMP oscillations, generated by adenylyl cyclase A (ACA), coordinate cell aggregation in Dictyostelium and have also been implicated in organizer function during multicellular development. We used a gene fusion of the ACA promoter with a labile lacZ derivative to study the expression pattern of ACA. During aggregation, most cells expressed ACA, but thereafter expression was lost in all cells except those of the anterior tip. Before aggregation, ACA transcription was strongly upregulated by nanomolar cAMP pulses. Postaggregative transcription was sustained by nanomolar cAMP pulses, but downregulated by a continuous micromolar cAMP stimulus and by the stalk-cell-inducing factor DIF. Earlier work showed that the transcription factor StatA displays tip-specific nuclear translocation and directs tip-specific expression of the nuclear protein CudA, which is essential for culmination. Both StatA and CudA were present in nuclei throughout the entire slug in an aca null mutant that expresses ACA from the constitutive actin15 promoter. This suggests that the tip-specific expression of ACA directs tip-specific nuclear translocation of StatA and tip-specific expression of CudA.


Subject(s)
Adenylyl Cyclases/biosynthesis , Cyclic AMP/metabolism , Dictyostelium/growth & development , Nuclear Proteins/biosynthesis , Transcription Factors/metabolism , Active Transport, Cell Nucleus , Adenylyl Cyclases/genetics , Animals , Cell Communication , Gene Expression Regulation , Morphogenesis , Protozoan Proteins/metabolism , STAT Transcription Factors
11.
Addiction ; 95(8): 1173-83, 2000 Aug.
Article in English | MEDLINE | ID: mdl-11092065

ABSTRACT

AIMS: Animal studies have shown that nicotine releases dopamine, a neurotransmitter implicated in drug reinforcement. We hypothesized that bromocriptine would decrease smoking behavior in humans. DESIGN: The study was conducted double blind and subjects' order of dose exposure was randomized. PARTICIPANTS: The smoking behavior of 20 heavy smokers was recorded for 5 hours after ingesting placebo or one of two doses of bromocriptine (2.50 mg, 3.75 mg) over three sessions (one dose per session). FINDINGS: There was a significant negative linear trend by dosage indicating shorter total puffing time with increasing bromocriptine dosages (p < 0.02). Other significant negative linear trends by increasing dosage include fewer number of puffs, fewer number of cigarettes smoked and mean latency to smoke after 3 hours (expected CMAX on the drug (all ps < 0.05). There was a negative significant linear trend showing decreased plasma nicotine (p < 0.02) and cotinine (p < 0.005) with increasing dosages of bromocriptine. Shiffman/Jarvik Withdrawal Scale (SJWS) cigarette craving subscale scores decreased significantly across increasing dosages (linear trend p < 0.02). There was a significant negative linear trend (p < 0.05) on the Profile of Mood States (POMS) Vigor and Depression subscales, with subjects reporting decreased vigor and depression with increasing bromocriptine doses. No other mood effects were observed. CONCLUSION: These results support the hypothesis that dopaminergic mechanisms mediate cigarette smoking reinforcement.


Subject(s)
Bromocriptine/administration & dosage , Dopamine Agonists/administration & dosage , Smoking Cessation/methods , Adolescent , Adult , Analysis of Variance , Bromocriptine/adverse effects , Bromocriptine/therapeutic use , Cotinine/blood , Dopamine Agonists/adverse effects , Dopamine Agonists/therapeutic use , Double-Blind Method , Drug Administration Schedule , Female , Humans , Male , Middle Aged , Mood Disorders/etiology , Nausea/etiology , Nicotine/blood , Self Disclosure , Smoking Cessation/psychology
12.
Pharmacol Biochem Behav ; 66(3): 553-8, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10899369

ABSTRACT

This study examined cigarette craving and blood nicotine levels in 11 male heavy smokers who were observed during 16 h of tobacco abstinence. Subjects rated their urge to smoke on a new brief 10-item questionnaire, Urge to Smoke (UTS), Schuh and Stitzer's four-item Visual Analog Scale (SSI), and a Strength of Urge to Smoke (SUTS) item. Testing occurred: 1) after 16 h (1700 h the night before to 0900 h the next morning) of abstinence from smoking; 2) after an ad lib smoking period following the 16 h abstinence; 3) every hour during 6 hours of abstinence; 4) and finally, after the 6 h abstinence, another ad lib smoking period. Thus, subjects smoked twice in each session. Blood plasma nicotine levels were measured before, after, and every 2 h during the 6-h abstinence period for a total of six measures. Blood pressure and heart rate were measured prior to each blood draw. There was a significant negative correlation between blood nicotine levels and craving for cigarettes on all craving questionnaires (rs = -0.55 to -0.78; ps < 0.002). Carbon monoxide was shown to correlate highly with nicotine blood levels (rs = 0.83 to 0.98 across subjects; ps < 0.001). Results are consistent with the hypothesis that "urge to smoke" reflects nicotine seeking in continuing smokers.


Subject(s)
Behavior, Addictive , Nicotine/blood , Smoking/blood , Adult , Behavior, Addictive/blood , Humans , Pilot Projects , Smoking/psychology , Smoking Cessation/psychology , Substance Withdrawal Syndrome/blood , Substance Withdrawal Syndrome/psychology , Surveys and Questionnaires , Time Factors
13.
J Biol Chem ; 275(29): 22147-56, 2000 Jul 21.
Article in English | MEDLINE | ID: mdl-10747978

ABSTRACT

We report here that guanylyl cyclase activity is associated with two large integral membrane proteins (PfGCalpha and PfGCbeta) in the human malaria parasite Plasmodium falciparum. Unusually, the proteins appear to be bifunctional; their amino-terminal regions have strong similarity with P-type ATPases, and the sequence and structure of the carboxyl-terminal regions conform to that of G protein-dependent adenylyl cyclases, with two sets of six transmembrane sequences, each followed by a catalytic domain (C1 and C2). However, amino acids that are enzymatically important and present in the C2 domain of mammalian adenylyl cyclases are located in the C1 domain of the P. falciparum proteins and vice versa. In addition, certain key residues in these domains are more characteristic of guanylyl cyclases. Consistent with this, guanylyl cyclase activity was obtained following expression of the catalytic domains of PfGCbeta in Escherichia coli. In P. falciparum, expression of both genes was detectable in the sexual but not the asexual blood stages of the life cycle, and PfGCalpha was localized to the parasite/parasitophorous vacuole membrane region of gametocytes. The profound structural differences identified between mammalian and parasite guanylyl cyclases suggest that aspects of this signaling pathway may be mechanistically distinct.


Subject(s)
Guanylate Cyclase/genetics , Guanylate Cyclase/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Plasmodium falciparum/enzymology , Amino Acid Sequence , Animals , Guanylate Cyclase/analysis , Humans , Membrane Proteins/analysis , Molecular Sequence Data , Protozoan Proteins/analysis , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , Sequence Alignment
14.
Appl Environ Microbiol ; 66(1): 363-8, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10618249

ABSTRACT

Secreted yields of foreign proteins may be enhanced in filamentous fungi through the use of translational fusions in which the target protein is fused to an endogenous secreted carrier protein. The fused proteins are usually separated in vivo by cleavage of an engineered Kex2 endoprotease recognition site at the fusion junction. We have cloned the kexin-encoding gene of Aspergillus niger (kexB). We constructed strains that either overexpressed KexB or lacked a functional kexB gene. Kexin-specific activity doubled in membrane-protein fractions of the strain overexpressing KexB. In contrast, no kexin-specific activity was detected in the similar protein fractions of the kexB disruptant. Expression in this loss-of-function strain of a glucoamylase human interleukin-6 fusion protein with an engineered Kex2 dibasic cleavage site at the fusion junction resulted in secretion of unprocessed fusion protein. The results show that KexB is the endoproteolytic proprotein processing enzyme responsible for the processing of (engineered) dibasic cleavage sites in target proteins that are transported through the secretion pathway of A. niger.


Subject(s)
Aspergillus niger/enzymology , Proprotein Convertases , Saccharomyces cerevisiae Proteins , Subtilisins/genetics , Subtilisins/metabolism , Aspergillus niger/genetics , Blotting, Western , Cloning, Molecular , Genetic Engineering , Glucan 1,4-alpha-Glucosidase/genetics , Glucan 1,4-alpha-Glucosidase/metabolism , Humans , Interleukin-6/genetics , Interleukin-6/metabolism , Molecular Sequence Data , Open Reading Frames/genetics , Plasmids/genetics , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Sequence Analysis, DNA , Substrate Specificity
15.
Mol Biochem Parasitol ; 104(2): 205-17, 1999 Nov 30.
Article in English | MEDLINE | ID: mdl-10593176

ABSTRACT

The parasitic protozoan Trypanosoma cruzi undergoes several differentiation events during its life cycle. Some of these transitions are thought to involve activation of adenylyl cyclase via the binding of peptide ligands to the cell surface. Here we describe the characterisation of the adenylyl cyclase gene family of T. cruzi. Two complete genes and one pseudogene have been sequenced. The protein products appear to have a large extracellular domain, a single transmembrane helix and a cytosolic catalytic domain. The adenylyl cyclase genes are present on at least six chromosomes and are scattered rather than clustered. They form a large polymorphic family in which the extracellular domain is particularly variable. An Escherichia coli adenylyl cyclase mutant could be complemented by expression of the catalytic domain of the T. cruzi enzyme. The recombinant protein had adenylyl cyclase activity in vitro, which was enhanced by increasing concentrations of divalent cations (Mn2+ > Mg2+). This constitutively active recombinant protein will be a useful tool for dissecting the catalytic mechanism of adenylyl cyclase.


Subject(s)
Adenylyl Cyclases/genetics , Adenylyl Cyclases/metabolism , Multigene Family , Trypanosoma cruzi/genetics , Adenylyl Cyclases/chemistry , Amino Acid Sequence , Animals , Blotting, Southern , Catalytic Domain , Chromosome Mapping , DNA, Complementary , Genes, Protozoan , Genetic Complementation Test , Molecular Sequence Data , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Analysis, DNA , Trypanosoma cruzi/enzymology , Trypanosoma cruzi/growth & development
16.
Dev Biol ; 212(1): 182-90, 1999 Aug 01.
Article in English | MEDLINE | ID: mdl-10419694

ABSTRACT

Activation of cAMP-dependent protein kinase (PKA) triggers terminal differentiation in Dictyostelium, without an obvious requirement for the G-protein-coupled adenylyl cyclase, ACA, or the osmosensory adenylyl cyclase, ACG. A third adenylyl cyclase, ACB, was recently detected in rapidly developing mutants. The specific characteristics of ACA, ACG, and ACB were used to determine their respective activities during development of wild-type cells. ACA was highly active during aggregation, with negligible activity in the slug stage. ACG activity was not present at significant levels until mature spores had formed. ACB activity increased strongly after slugs had formed with optimal activity at early fruiting body formation. The same high activity was observed in slugs of ACG null mutants and ACA null mutants that overexpress PKA (acaA/PKA), indicating that it was not due to either ACA or ACG. The detection of high adenylyl cyclase activity in acaA/PKA null mutants contradicts earlier conclusions (B. Wang and A. Kuspa, Science 277, 251-254, 1997) that these mutants can develop into fruiting bodies in the complete absence of cAMP. In contrast to slugs of null mutants for the intracellular cAMP-phosphodiesterase REGA, where both intact cells and lysates show ACB activity, wild-type slugs only show activity in lysates. This indicates that cAMP accumulation by ACB in living cells is controlled by REGA. Both REGA inhibition and PKA overexpression cause precocious terminal differentiation. The developmental regulation of ACB and its relationship to REGA suggest that ACB activates PKA and induces terminal differentiation.


Subject(s)
Adenylyl Cyclases/metabolism , Adenylyl Cyclases/physiology , Dictyostelium/enzymology , Dictyostelium/physiology , Protozoan Proteins , Animals , Bacterial Proteins/metabolism , Cell Division , Cells, Cultured , Chromatography, High Pressure Liquid , Cyclic AMP/metabolism , Cyclic AMP-Dependent Protein Kinases/metabolism , Kinetics , Mutagenesis , Time Factors
17.
Appl Environ Microbiol ; 65(8): 3347-53, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10427018

ABSTRACT

A 300-bp repetitive element was found in the genome of the white button mushroom, Agaricus bisporus, and designated Abr1. It is present in approximately 15 copies per haploid genome in the commercial strain Horst U1. Analysis of seven copies showed 89 to 97% sequence identity. The repeat has features typical of class II transposons (i.e., terminal inverted repeats, subterminal repeats, and a target site duplication of 7 bp). The latter shows a consensus sequence. When used as probe on Southern blots, Abr1 identifies relatively little variation within traditional and present-day commercial strains, indicating that most strains are identical or have a common origin. In contrast to these cultivars, high variation is found among field-collected strains. Furthermore, a remarkable difference in copy numbers of Abr1 was found between A. bisporus isolates with a secondarily homothallic life cycle and those with a heterothallic life cycle. Abr1 is a type II transposon not previously reported in basidiomycetes and appears to be useful for the identification of strains within the species A. bisporus.


Subject(s)
Agaricus/genetics , DNA Transposable Elements/genetics , DNA, Fungal/genetics , Genome, Fungal , Agaricus/classification , Agaricus/growth & development , Base Sequence , Chromosomes, Fungal/genetics , DNA Primers/genetics , DNA, Fungal/isolation & purification , Molecular Sequence Data
18.
FEBS Lett ; 452(3): 335-40, 1999 Jun 11.
Article in English | MEDLINE | ID: mdl-10386617

ABSTRACT

Nuclear import usually relies on the presence of nuclear localization sequences (NLSs). NLSs are recognized by NLS receptors (importins), which target their substrates to the nuclear pore. We identified the NLSs of the yeast ribosomal proteins S22 and S25 and studied the former by mutational analysis. Furthermore, in S25 the nucleolar targeting information was found to overlap with its NLS. Comparison with previously published data on yeast ribosomal protein NLSs and computer analysis indicates the existence of a novel type of ribosomal protein-specific NLS that differs from the classical Chelsky and bipartite NLSs. The existence of such a ribosomal protein-specific NLS is in accordance with the recent identification of ribosomal protein-specific importins.


Subject(s)
Cell Nucleolus/ultrastructure , Cell Nucleus/ultrastructure , Ribosomal Proteins/analysis , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae/cytology , Amino Acid Sequence , Immunohistochemistry , Molecular Sequence Data , Peptide Fragments/chemistry , Recombinant Fusion Proteins/analysis , Recombinant Fusion Proteins/chemistry , Ribosomal Proteins/chemistry , Ribosomal Proteins/genetics , Saccharomyces cerevisiae/ultrastructure , beta-Galactosidase/analysis , beta-Galactosidase/chemistry
19.
Development ; 126(15): 3391-405, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10393118

ABSTRACT

Dd-STATa is a structural and functional homologue of the metazoan STAT (Signal Transducer and Activator of Transcription) proteins. We show that Dd-STATa null cells exhibit several distinct developmental phenotypes. The aggregation of Dd-STATa null cells is delayed and they chemotax slowly to a cyclic AMP source, suggesting a role for Dd-STATa in these early processes. In Dd-STATa null strains, slug-like structures are formed but they have an aberrant pattern of gene expression. In such slugs, ecmB/lacZ, a marker that is normally specific for cells on the stalk cell differentiation pathway, is expressed throughout the prestalk region. Stalk cell differentiation in Dictyostelium has been proposed to be under negative control, mediated by repressor elements present in the promoters of stalk cell-specific genes. Dd-STATa binds these repressor elements in vitro and the ectopic expression of ecmB/lacZ in the null strain provides in vivo evidence that Dd-STATa is the repressor protein that regulates commitment to stalk cell differentiation. Dd-STATa null cells display aberrant behavior in a monolayer assay wherein stalk cell differentiation is induced using the stalk cell morphogen DIF. The ecmB gene, a general marker for stalk cell differentiation, is greatly overinduced by DIF in Dd-STATa null cells. Also, Dd-STATa null cells are hypersensitive to DIF for expression of ST/lacZ, a marker for the earliest stages in the differentiation of one of the stalk cell sub-types. We suggest that both these manifestations of DIF hypersensitivity in the null strain result from the balance between activation and repression of the promoter elements being tipped in favor of activation when the repressor is absent. Paradoxically, although Dd-STATa null cells are hypersensitive to the inducing effects of DIF and readily form stalk cells in monolayer assay, the Dd-STATa null cells show little or no terminal stalk cell differentiation within the slug. Dd-STATa null slugs remain developmentally arrested for several days before forming very small spore masses supported by a column of apparently undifferentiated cells. Thus, complete stalk cell differentiation appears to require at least two events: a commitment step, whereby the repression exerted by Dd-STATa is lifted, and a second step that is blocked in a Dd-STATa null organism. This latter step may involve extracellular cAMP, a known repressor of stalk cell differentiation, because Dd-STATa null cells are abnormally sensitive to the inhibitory effects of extracellular cyclic AMP.


Subject(s)
Dictyostelium/cytology , Dictyostelium/physiology , Protozoan Proteins/physiology , Repressor Proteins/physiology , 8-Bromo Cyclic Adenosine Monophosphate/pharmacology , Animals , Cell Differentiation/drug effects , Cell Differentiation/physiology , Chemotaxis/drug effects , Chemotaxis/physiology , DNA, Complementary/genetics , DNA, Protozoan/genetics , Dictyostelium/genetics , Genes, Protozoan , Genes, Reporter , Genetic Markers , Lac Operon , Microscopy, Video , Mutagenesis, Insertional , Mutation , Protozoan Proteins/genetics , Repressor Proteins/genetics
20.
Mol Gen Genet ; 261(3): 452-62, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10323225

ABSTRACT

The NAD+-dependent glutamate dehydrogenase (NAD-GDH) of Agaricus bisporus, a key enzyme in nitrogen metabolism, was purified to homogeneity. The apparent molecular mass of the native enzyme is 474 kDa comprising four subunits of 116 kDa. The isoelectric point of the enzyme is about 7.0. Km values for ammonium, 2-oxoglutarate, NADH, glutamate and NAD+ were 6.5, 3.5, 0.06, 37.1 and 0.046 mM, respectively. The enzyme is specific for NAD(H). The gene encoding this enzyme (gdhB) was isolated from an A. bisporus H39 recombinant lambda phage library. The deduced amino acid sequence specifies a 1029-amino acid protein with a deduced molecular mass of 115,463 Da, which displays a significant degree of similarity with NAD-GDH of Saccharomyces cerevisiae and Neurospora crassa. The ORF is interrupted by fifteen introns. Northern analysis combined with enzyme activity measurements suggest that NAD-GDH from A. bisporus is regulated by the nitrogen source. NAD-GDH levels in mycelium grown on glutamate were higher than NAD-GDH levels in mycelium grown on ammonium as a nitrogen source. Combined with the kinetic parameters, these results suggest a catabolic role for NAD-GDH. However, upon addition of ammonium to the culture transcription of the gene is not repressed as strongly as that of the gene encoding NADP-GDH (gdhA). To date, tetrameric NAD-GDHs with large subunits, and their corresponding genes, have only been isolated from a few species. This enzyme represents the first NAD-GDH of basidiomycete origin to be purified and is the first such enzyme from basidiomycetes whose sequence has been determined.


Subject(s)
Agaricus/enzymology , Agaricus/genetics , Glutamate Dehydrogenase/chemistry , Glutamate Dehydrogenase/genetics , Amino Acid Sequence , Base Sequence , Cloning, Molecular , DNA Primers/genetics , Enzyme Stability , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Fungal , Genes, Fungal , Glutamate Dehydrogenase/metabolism , Kinetics , Molecular Sequence Data , RNA, Fungal/genetics , RNA, Fungal/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Homology, Amino Acid
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