Uncovering cryptic species diversity of a termite community in a West African savanna

To uncover the termite species diversity of a natural African savanna ecosystem, we combined morphological analyses and sequencing of three gene fragments (cytochrome oxidase I, cytochrome oxidase II and 28SrDNA, total length about 2450 bp) to infer putative species from phylogenetic trees. We identified 18 putative species clusters with high support values and which we retrieved consistently. Samples from two genera (Ancistrotermes and Microcerotermes) were excluded from the mitochondrial phylogenetic analyses as they might represent nuclear mitochondrial sequences (NUMTs). In total, our data suggest a species richness of at least 20 species, all but one belonging to the Termitidae (higher termites), and among them the fungus-growing Macrotermitinae were most prevalent with at least nine putative species. Within the fungus-growers the most species-rich genus was Microtermes and its four putative species were all cryptic species. Their abundance in the samples suggests that they play an important ecological role which is completely unstudied also due to the lack of reliable identification means. Our study shows that morphological traits are unreliable means of species identification for several termite taxa. Yet reliable and consistent identification is necessary for studying the functional role of termites in ecosystem and global processes.     

Requirement for asparagine in the aquaporin NPA sequence signature motifs for cation exclusion

Two highly conserved NPA motifs are a hallmark of the aquaporin (AQP) family. The NPA triplets form N-terminal helix capping structures with the Asn side chains located in the centre of the water or solute-conducting channel, and are considered to play an important role in AQP selectivity. Although another AQP selectivity filter site, the aromatic/Arg (ar/R) constriction, has been well characterized by mutational analysis, experimental data concerning the NPA region--in particular, the Asn position--is missing. Here, we report on the cloning and mutational analysis of a novel aquaglyceroporin carrying one SPA motif instead of the NPA motif from Burkholderia cenocepacia, an epidemic pathogen of cystic fibrosis patients. Of 1357 AQP sequences deposited in RefSeq, we identified only 15 with an Asn exchange. Using direct and phenotypic permeability assays, we found that Asn and Ser are freely interchangeable at both NPA sites without affecting protein expression or water, glycerol and methylamine permeability. However, other mutations in the NPA region led to reduced permeability (S186C and S186D), to nonfunctional channels (N64D), or even to lack of protein expression (S186A and S186T). Using electrophysiology, we found that an analogous mammalian AQP1 N76S mutant excluded protons and potassium ions, but leaked sodium ions, providing an argument for the overwhelming prevalence of Asn over other amino acids. We conclude that, at the first position in the NPA motifs, only Asn provides efficient helix cap stabilization and cation exclusion, whereas other small residues compromise structural stability or cation exclusion but not necessarily water and solute permeability.     

Measuring and analyzing tissue specificity of human genes and protein complexes

Proteins and their interactions are essential for the survival of each human cell. Knowledge of their tissue occurrence is important for understanding biological processes. Therefore, we analyzed microarray and high-throughput RNA-sequencing data to identify tissue-specific and universally expressed genes. Gene expression data were used to investigate the presence of proteins, protein interactions and protein complexes in different tissues. Our comparison shows that the detection of tissue-specific genes and proteins strongly depends on the applied measurement technique. We found that microarrays are less sensitive for low expressed genes than high-throughput sequencing. Functional analyses based on microarray data are thus biased towards high expressed genes. This also means that previous biological findings based on microarrays might have to be re-examined using high-throughput sequencing results.     

Transient myeloproliferative disorder in a newborn with down syndrome treated with rasburicase for the risk of development of tumor lysis syndrome: A case report

Introduction

Transient myeloproliferative disorder is a hematologic abnormality characterized by an uncontrolled proliferation of myeloblasts in peripheral blood and bone marrow that primarily affects newborns and babies with Down syndrome. Tumor lysis syndrome is rarely associated with transient myeloproliferative disorder.

Case presentation

Transient myeloproliferative disorder was diagnosed in a seven-day-old baby girl with Down syndrome, who was referred to our department due to hyperleukocytosis. Our patient developed tumor lysis syndrome, successfully treated with rasburicase, as a complication of transient myeloproliferative disorder resulting from rapid degradation of myeloid blasts after initiation of effective chemotherapy.

Conclusions

Tumor lysis syndrome is rarely reported as a complication of transient myeloproliferative disorder. To the best of our knowledge, this is the first case of a newborn with Down syndrome and transient myeloproliferative disorder treated with rasburicase for developing tumor lysis syndrome.

     

The effect of ozone on the yellowing process of magnesium-deficient clonal Norway spruce grown under defined conditions

During two vegetation periods, young clonal spruce trees (Picea abies (L.) Karst.) with sufficient and poor magnesium (Mg) supply were exposed in the environmental chambers of the GSF phytotron to three levels of ozone (daily means: 18-22, 88-130, and 135-190 microg m(-3); 10% reduction at night). Previous year's needles were examined at 4-week intervals with respect to their contents of Mg, Ca, K, Mn, N, P, and chlorophyll (Chl), various parameters of Chl fluorescence, and the stability of the isolated light-harvesting Chl-a/b-protein complex LHC II. The needles of the two nutrition variants contained more than 0.53 or less than 0.27mg Mg g(-1) needle dry matter, respectively. The ratio of variable to maximal Chl-a fluorescence of the dark-adapted needles, Fv/Fm, and the photoinhibitory quenching of Fv after light treatment, SVi.v, were affected by the Mg content of the needles rather than the ozone levels. Changes of the Chl content and the behavior of the LHC II allowed differentiating between a slow process of needle yellowing occurring under Mg deficiency only, and a rapid process of needle yellowing occurring under the combined action of Mg deficiency and ozone pollution. Only the rapid yellowing process was accompanied by destabilization of the LHC II, and the degree of destabilization was correlated with the ozone concentration present in the days before sampling. The results are consistent with observations obtained at a research site in the Central Black Forest (J Plant Physiol 161 (2004) 423).     

The core TatABC complex of the twin-arginine translocase in Escherichia coli: TatC drives assembly whereas TatA is essential for stability

Current models for the action of the twin-arginine translocation (Tat) system propose that substrates bind initially to the TatBC subunits, after which a separate TatA complex is recruited to form an active translocon. Here, we have studied the roles of individual subunits in the assembly and stability of the core TatBC-containing substrate-binding complex. Previous studies have shown that TatB and TatC are active when fused together; we show here that deletion of the entire TatB transmembrane span from this Tat(BC) fusion inactivates the Tat system but does not affect assembly of the core complex. In this mutated complex, TatA is present but more loosely bound, indicating a role for TatB in the correct binding of TatA. In the absence of TatA, the truncated TatBC fusion protein still assembles into a complex of the correct magnitude, demonstrating that the transmembrane spans of TatC are the only determinants within the membrane bilayer that specify assembly of this complex. Further studies on both the Tat(BC) construct and the wild-type TatBC subunits show that the TatBC complex is unstable in the absence of TatA, and we show that TatA stabilises the TatB subunit specifically within this complex. The results demonstrate a dual role and location for TatA: in the functioning/maintenance of the core complex, and as a separate homo-oligomeric complex.     

Stability analysis of the elbow with a load

We present a model of the human elbow and study the problem of existence and stability of equilibrium states. Our main goal is to demonstrate that stable equilibrium states exist just on grounds of the mechanical properties of the muscles and the skeleton. In particular, additional control mechanisms such as reflexes are not necessary to obtain stability. We assume that the activation of flexor and extensor muscles is constant and such that the right angle is an equilibrium state. We give a complete bifurcation diagram of all equilibrium states in terms of the elbow angle, the activation of the muscles and the mass of a load. Moreover, we define a dimensionless model parameter which allows to determine whether or not there are stable equilibria at an angle of ninety degrees. It turns out that the dependency of the muscle forces on the length of the muscles is the crucial factor for the stability of such an equilibrium.     

Enhancement of DNA uptake in FUT8‐deleted CHO cells for transient production of afucosylated antibodies

Removal of the core α1,6 fucose from the glycans in the Fc region of IgG1 antibodies has been demonstrated to improve antibody‐dependent cellular cytotoxicity (ADCC) activity. In order to produce afucosylated antibodies using transient transfection, a FUT8 knockout (FUT8KO) cell line was generated in a CHO host cell line using the zinc finger nuclease technology. Transient transfection of DNA into mammalian cells using the cationic polymer, polyethylenimine (PEI), is commonly used for rapid generation of recombinant proteins. FUT8KO cells evaluated in PEI transfections yielded lower titers than parental CHO WT cells. FACS and HPLC analyses revealed that the FUT8KO cells had lower cell surface heparan sulfate (HS) levels than CHO WT. Removal of cell surface HS resulted in reduced uptake of PEI‐transfected DNA (PEI:DNA) and lower transfection titers suggesting that PEI:DNA relies on HS for binding and cellular entry. The absence of cell surface HS did not severely impact transfections performed with cationic liposomes. We undertook two approaches to improve transient production of afucosylated antibodies. First, we evaluated transfection of FUT8KO cells with cationic liposomes, which were observed to be less dependent on HS levels for uptake. Transfection of FUT8KO cells using the cationic liposome, DMRIE‐C, produced similar titers to CHO WT in both shake flask and large‐scale 10 L bioreactors. The second approach was to engineer a cell line overexpressing exostosin‐1 (EXT1), an enzyme responsible for HS chain elongation, to increase HS content. EXT1‐FUT8KO and CHO WT cells produced comparable levels of antibody from PEI transfections. Biotechnol. Bioeng. 2010;106: 751–763. © 2010 Wiley Periodicals, Inc.