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Changes in acanthocephalan infection of the Antarctic fish Notothenia coriiceps in Admiralty Bay, King George Island, over 29 years
Get PDFA comparison between the levels of infection with Acanthocephala of the fish
Notothenia coriiceps in Admiralty Bay (South Shetland Islands, Antarctic) in 1978/79 and
2007/08 is presented. The same eight acanthocephalan species, three echinorhynchids ma−
turing in fish, Aspersentis megarhynchus (dominant species), Metacanthocephalus john−
stoni (subdominant species) and M. dalmori (common species), and five polymorphids ma−
turing in mammals and birds, Corynosoma hamanni, C. pseudohamanni (both co−dominant
species), C. arctocephali and C. bullosum (both common species), and C. shackletoni (rare
species), were found. Echinorhynchids were more numerous in 2007/08 (mean abundance
46.54 versus 35.35 in 1978/79), whereas polymorphids more numerous in 1978/79 (mean
abundance 74.35 versus 36.40 in 2007/08). The overall results therefore demonstrated that
echinorhynchids were more numerous than polymorphids in 2007/08 and the reverse was
true in 1978/79. This situation is dependent mainly upon the decreased infections with C.
hamanni, C. pseudohamanni and C. bullosum, and to a lesser degree upon the increasing of
infections with M. johnstoni. The decrease of the three Corynosoma spp. is possibly associ−
ated with the decreasing of populations of final hosts, seals, on the shore of Admiralty Bay
in the vicinity of Arctowski Station
Life with too much polyprenol: polyprenol reductase deficiency
Get PDFCongenital disorders of glycosylation (CDG) are caused by a dysfunction of glycosylation, an essential step in
the manufacturing process of glycoproteins. This paper focuses on a 6-year-old patient with a new type of
CDG-I caused by a defect of the steroid 5α reductase type 3 gene (SRD5A3). The clinical features were psychomotor
retardation, pathological nystagmus, slight muscular hypotonia and microcephaly. SRD5A3 was recently
identified encoding the polyprenol reductase, an enzyme catalyzing the final step of the biosynthesis
of dolichol, which is required for the assembly of the glycans needed for N-glycosylation.
Although an early homozygous stop-codon (c.57G>A [W19X]) with no functional protein was found in the
patient, about 70% of transferrin (Tf) was correctly glycosylated. Quantification of dolichol and unreduced
polyprenol in the patient's fibroblasts demonstrated a high polyprenol/dolichol ratio with normal amounts
of dolichol, indicating that high polyprenol levels might compete with dolichol for the initiation of
N-glycan assembly but without supporting normal glycosylation and that there must be an alternative
pathway for dolichol biosynthesis
C16orf57, a gene mutated in poikiloderma with neutropenia, encodes a putative phosphodiesterase responsible for the U6 snRNA 3′ end modification.
Get PDFC16orf57 encodes a human protein of unknown function, and mutations in the gene occur in poikiloderma with neutropenia (PN), which is a rare, autosomal recessive disease. Interestingly, mutations in C16orf57 were also observed among patients diagnosed with Rothmund-Thomson syndrome (RTS) and dyskeratosis congenita (DC), which are caused by mutations in genes involved in DNA repair and telomere maintenance. A genetic screen in Saccharomyces cerevisiae revealed that the yeast ortholog of C16orf57, USB1 (YLR132C), is essential for U6 small nuclear RNA (snRNA) biogenesis and cell viability. Usb1 depletion destabilized U6 snRNA, leading to splicing defects and cell growth defects, which was suppressed by the presence of multiple copies of the U6 snRNA gene SNR6. Moreover, Usb1 is essential for the generation of a unique feature of U6 snRNA; namely, the 3'-terminal phosphate. RNAi experiments in human cells followed by biochemical and functional analyses confirmed that, similar to yeast, C16orf57 encodes a protein involved in the 2',3'-cyclic phosphate formation at the 3' end of U6 snRNA. Advanced bioinformatics predicted that C16orf57 encodes a phosphodiesterase whose putative catalytic activity is essential for its function in vivo. Our results predict an unexpected molecular basis for PN, DC, and RTS and provide insight into U6 snRNA 3' end formation
A global diatom database – abundance, biovolume and biomass in the world ocean
Get PDFAbstract. Phytoplankton identification and abundance data
are now commonly feeding plankton distribution databases
worldwide. This study is a first attempt to compile the largest
possible body of data available from different databases as
well as from individual published or unpublished datasets
regarding diatom distribution in the world ocean. The data
obtained originate from time series studies as well as spatial
studies. This effort is supported by the Marine Ecosystem
Model Inter-Comparison Project (MAREMIP), which aims
at building consistent datasets for the main plankton functional
types (PFTs) in order to help validate biogeochemical
ocean models by using carbon (C) biomass derived from
abundance data. In this study we collected over 293 000 individual
geo-referenced data points with diatom abundances
from bottle and net sampling. Sampling site distribution was
not homogeneous, with 58% of data in the Atlantic, 20%
in the Arctic, 12% in the Pacific, 8% in the Indian and 1%
in the Southern Ocean. A total of 136 different genera and
607 different species were identified after spell checking and
name correction. Only a small fraction of these data were
also documented for biovolumes and an even smaller fraction
was converted to C biomass. As it is virtually impossible
to reconstruct everyone’s method for biovolume calculation,
which is usually not indicated in the datasets, we decided to
undertake the effort to document, for every distinct species,
the minimum and maximum cell dimensions, and to convert
all the available abundance data into biovolumes and C
biomass using a single standardized method. Statistical correction
of the database was also adopted to exclude potential
outliers and suspicious data points. The final database contains
90 648 data points with converted C biomass. Diatom
C biomass calculated from cell sizes spans over eight orders
of magnitude. The mean diatom biomass for individual locations,
dates and depths is 141.19 μg Cl−1, while the median
value is 11.16 μg Cl−1. Regarding biomass distribution,
19% of data are in the range 0–1 μg Cl−1, 29% in the range
1–10 μg Cl−1, 31% in the range 10–100 μg Cl−1, 18% in
the range 100–1000 μg Cl−1, and only 3% > 1000 μg Cl−1.
Interestingly, less than 50 species contributed to >90% of
global biomass, among which centric species were dominant.
Thus, placing significant efforts on cell size measurements,
process studies and C quota calculations of these
species should considerably improve biomass estimates in
the upcoming years. A first-order estimate of the diatom
biomass for the global ocean ranges from 444 to 582 Tg C,
which converts to 3 to 4 Tmol Si and to an average Si
biomass turnover rate of 0.15 to 0.19 d−
Comparison of siRNA-mediated silencing of glycosaminoglycan synthesis genes and enzyme replacement therapy for mucopolysaccharidosis in cell culture studies
Get PDFCytotoxicity of laronidase (Aldurazyme®), employed in
enzyme replacement therapy (ERT) for mucopolysaccharidosis
type I (MPS I) and various siRNAs, tested previously
in studies on substrate reduction therapy (SRT)
for mucopolysaccharidoses, was tested. The enzyme did
not cause any cytotoxic effects, and the siRNAs did not
inhibit growth of most investigated cell lines. However,
some cytotoxic effects of some tested siRNAs were observed
in one MPS IIIA cell line. The efficacy of a combination
of enzyme replacement therapy and siRNA-based
substrate deprivation therapy was tested on three MPS I
cell lines. Surprisingly, different results were obtained for
different cell lines. The decrease of glycosaminoglycan
storage in cells treated simultaneously with both methods
was: (i) less pronounced than obtained with either
of those methods used alone in one cell line, (ii) similar
to that observed for enzyme replacement therapy in another
cell line, and (iii) stronger than that obtained with
either of the methods used alone in the third cell line.
Therefore, it appears that the effects of various therapeutic
methods may strongly depend on the features of
the MPS cell line
Post-translational S-Nitrosylation Is an Endogenous Factor Fine Tuning the Properties of Human S100A1 Protein
No full textS100A1 is a member of the Ca2+-binding S100 protein family. It is expressed in brain and heart tissue, where it plays a crucial role as a modulator of Ca2+ homeostasis, energy metabolism, neurotransmitter release, and contractile performance. Biological effects of S100A1 have been attributed to its direct interaction with a variety of target proteins. The (patho)physiological relevance of S100A1 makes it an important molecular target for future therapeutic intervention. S-Nitrosylation is a post-translational modification of proteins, which plays a role in cellular signal transduction under physiological and pathological conditions. In this study, we confirmed that S100A1 protein is endogenously modified by Cys85 S-nitrosylation in PC12 cells, which are a well established model system for studying S100A1 function. We used isothermal calorimetry to show that S-nitrosylation facilitates the formation of Ca2+-loaded S100A1 at physiological ionic strength conditions. To establish the unique influence of the S-nitroso group, our study describes high resolution three-dimensional structures of human apo-S100A1 protein with the Cys85 thiol group in reduced and S-nitrosylated states. Solution structures of the proteins are based on NMR data obtained at physiological ionic strength. Comparative analysis shows that S-nitrosylation fine tunes the overall architecture of S100A1 protein. Although the typical S100 protein intersubunit four-helix bundle is conserved upon S-nitrosylation, the conformation of S100A1 protein is reorganized at the sites most important for target recognition (i.e. the C-terminal helix and the linker connecting two EF-hand domains). In summary, this study discloses cysteine S-nitrosylation as a new factor responsible for increasing functional diversity of S100A1 and helps explain the role of S100A1 as a Ca2+ signal transmitter sensitive to NO/redox equilibrium within cells
Highly mutagenic exocyclic DNA adducts are substrates for the human nucleotide incision repair pathway
Get PDFBackground: Oxygen free radicals induce lipid peroxidation (LPO) that damages and breaks polyunsaturated fatty acids in cell membranes. LPO-derived aldehydes and hydroxyalkenals react with DNA leading to formation of etheno(ε)-bases including 1,N6-ethenoadenine (εA) and 3,N4-ethenocytosine (εC). The εA and εC residues are highly mutagenic in mammalian cells and eliminated in the base excision repair (BER) pathway and/or by AlkB family proteins in the direct damage reversal process. BER initiated by DNA glycosylases is thought to be the major pathway for the removal of non-bulky endogenous base damage. Alternatively, in the nucleotide incision repair (NIR) pathway, the apurinic/apyrimidinic (AP) endonucleases can directly incise DNA duplex 5’ to a damaged base in a DNA glycosylase-independent manner.
Methodology/Principal Findings: Here, we characterized the substrate specificity of human major AP endonuclease 1, APE1, towards εA, εC, thymine glycol (Tg) and 7,8-dihydro-8-oxoguanine (8oxoG) residues when present in duplex DNA. APE1 cleaves oligonucleotide duplexes containing εA, εC and Tg, but not those containing 8oxoG. The activity depends strongly on sequence context. The apparent kinetic parameters of the reactions suggest that APE1 has high affinity to DNA containing ε-bases but cleaves DNA duplex at an extremely slow rate. Consistent with this observation, the oligonucleotide duplexes containing an ε-base strongly inhibit AP site nicking activity of APE1 with IC50 values in the range of 5-10 nM. MALDI-TOF MS analysis of the reaction products demonstrated that APE1-catalyzed cleavage of εA•T and εC•G duplexes generates as expected DNA fragments containing 5’-terminal ε-base residue.
Conclusions/Significance: The fact that ε-bases and Tg in duplex DNA are recognized and cleaved by APE1 in vitro, suggest that NIR may act as a backup pathway to BER one to remove a large variety of genotoxic base lesions in human cells
Synthesis and Physico-Chemical Properties in Aqueous Medium of All Possible Isomeric Bromo Analogues of Benzo-1H-Triazole, Potential Inhibitors of Protein Kinases.
Get PDFIn ongoing studies on the role of the individual bromine atoms of 4,5,6,7-tetrabromobenzotriazole (TBBt) in its relatively selective inhibition of protein kinase CK2α, we have prepared all the possible two mono-, four di-, and two tri- bromobenzotriazoles, and determined their physico-chemical properties in aqueous medium. They exhibited a general trend of a decrease in solubility with an increase in the number of bromines on the benzene ring, significantly modulated by the pattern of substitution. For a given number of attached bromines, this was directly related to the electronic effects resulting from different sites of substitution, leading to marked variations of pKa values for dissociation of the triazole proton. Experimental data (pKa, solubility) and ab initio calculations demonstrated that hydration of halogenated benzotriazoles is driven by a subtle balance of hydrophobic and polar interactions. The combination of QM-derived free energies for solvation and proton dissociations was found to be a reasonably good predictor of inhibitory activity of halogenated benzotriazoles vs CK2α. Since the pattern of halogenation of the benzene ring of benzotriazole has also been shown to be one of the determinants of inhibitory potency vs some viruses and viral enzymes, the present comprehensive description of their physico-chemical properties should prove helpful in efforts to elucidate reaction mechanisms, including possible halogen bonding, and the search for more selective and potent inhibitors
Functioning of the TA cassette of streptococcal plasmid pSM19035 in various Gram-positive bacteria.
Get PDFToxin-antitoxin (TA) systems are common in microorganisms and are frequently found in the chromosomes and low-copy number plasmids of bacterial pathogens. One such system is carried by the low copy number plasmid pSM19035 of the pathogenic bacterium Streptococcus pyogenes. This plasmid encodes an omega-epsilon-zeta cassette that ensures its stable maintenance by postsegregational killing of plasmid-free cells. In this study, the activity of the ω-ε-ζ cassette was examined in various Gram-positive bacteria with a low G/C content in their DNA. The broad host range of pSM19035 was confirmed and the copy number of a truncated derivative in transformed strains was determined by real-time qPCR
Localization of key amino acid residues in the dominant conformational epitopes on thyroid peroxidase recognized by mouse monoclonal antibodies.
Get PDFAutoantibodies to thyroid peroxidase (TPO), the major target autoantigen in autoimmune thyroid diseases, recognize conformational epitopes limited to two immunodominant regions (IDRs) termed IDR-A and -B. The apparent restricted heterogeneity of TPO autoantibodies was discovered using TPO-specific mouse monoclonal antibodies (mAbs) and later confirmed by human recombinant Fabs. In earlier studies we identified key amino acids crucial for the interaction of human autoantibodies with TPO. Here we show the critical residues that participate in binding of five mAbs to the conformational epitopes on the TPO surface. Using ELISA we tested the reactivity of single and multiple TPO mutants expressed in CHO cells with a panel of mAbs specifically recognizing IDR-A (mAb 2 and 9) and IDR-B (mAb 15, 18, 64). We show that antibodies recognizing very similar regions on the TPO surface may interact with different sets of residues. We found that residues K713 and E716 contribute to the interaction between mAb 2 and TPO. The epitope for mAb 9 is critically dependent on residues R646 and E716. Moreover, we demonstrate that amino acids E604 and D630 are part of the functional epitope for mAb 15, and amino acids D624 and K627 for mAb 18. Finally, residues E604, D620, D624, K627, and D630 constitute the epitope for mAb 64. This is the first detailed study identifying the key resides for binding of mAbs 2, 9, 15, 18, and 64. Better understanding of those antibodies' specificity will be helpful in elucidating the properties of TPO as an antigen in autoimmune disorders