Taxonomy of Tabanus cordiger Species Group (Diptera: Tabanidae) in Korea

ABSTRACT Horseflies of the Tabanus cordiger species group from Korea is revised taxonomically. A total of four species are arranged herein: T. divulsus sp. nov., T. fulvimedioides, T. kinoshitai and T. loukashkini. A key to discriminate species, annotated check lists of domestic records, and collection data for each species are provided.     

Polymerization of cardanol using soybean peroxidase and its potential application as anti-biofilm coating material

Soybean peroxidase (20 mg) catalyzed the oxidative polymerization of cardanol in 2-propanol/phospate buffer solution (25 ml, 1:1 v/v) and yielded 62% polycardanol over 6 h. Cobalt naphthenate (0.5% w/w) catalyzed the crosslinking of polycardanol and the final hardness of crosslinked polycardanol film exceeded 9 H scale as pencil scratch hardness, which shows a high potential as a commercial coating material. In addition, it showed an excellent anti-biofouling activity to Pseudomonas fluorescens compared to other polymeric materials such as polypropylene.     

Responses of medullary and spinal cord neurons to simulataneous stimulation of two locomotor points

Responses of neurons in the medulla and cervical segments of the spinal cord to simultaneous repetitive stimulation (50 pps) of two locomotor points (LP) that exceed the threshold for evoking walking by one to two times were investigated in mesencephalic cats. In most cases a neuron responsed to stimulation of only one LP. Stimulation of a second LP usually enhanced the firing index of that response, if it was low. Or it decreased the firing index if it was high, and it had no effect if the firing index was about 0.1. Some of the neurons responded to stimulation of one LP by increasing the baseline activity, though the pulses were not locked to individual stimuli. The effect of stimulation of the second LP on this increase in activity depended on the size of the increase. Data were also obtained on the convergence of effects on single neurons from the ipsi- and contralateral LPs of the midbrain and medulla. Possible mechanisms of the summation of subthreshold excitation of a pair of LPs during the initiation of locomotion are discussed.Institute of Information Transmission Problems, Russian Academy of Sciences, Moscow. Translated from Neirofiziologiya, Vol. 24, No. 4, pp. 471–481, July–August, 1992.     

Identification of noncoding transcripts from within CENP-A chromatin at fission yeast centromeres

The histone H3 variant CENP-A is the most favored candidate for an epigenetic mark that specifies the centromere. In fission yeast, adjacent heterochromatin can direct CENP-A(Cnp1) chromatin establishment, but the underlying features governing where CENP-A(Cnp1) chromatin assembles are unknown. We show that, in addition to centromeric regions, a low level of CENP-A(Cnp1) associates with gene promoters where histone H3 is depleted by the activity of the Hrp1(Chd1) chromatin-remodeling factor. Moreover, we demonstrate that noncoding RNAs are transcribed by RNA polymerase II (RNAPII) from CENP-A(Cnp1) chromatin at centromeres. These analyses reveal a similarity between centromeres and a subset of RNAPII genes and suggest a role for remodeling at RNAPII promoters within centromeres that influences the replacement of histone H3 with CENP-A(Cnp1).     

Protein signaling networks from single cell fluctuations and information theory profiling

Protein signaling networks among cells play critical roles in a host of pathophysiological processes, from inflammation to tumorigenesis. We report on an approach that integrates microfluidic cell handling, in situ protein secretion profiling, and information theory to determine an extracellular protein-signaling network and the role of perturbations. We assayed 12 proteins secreted from human macrophages that were subjected to lipopolysaccharide challenge, which emulates the macrophage-based innate immune responses against Gram-negative bacteria. We characterize the fluctuations in protein secretion of single cells, and of small cell colonies (n = 2, 3,···), as a function of colony size. Measuring the fluctuations permits a validation of the conditions required for the application of a quantitative version of the Le Chatelier's principle, as derived using information theory. This principle provides a quantitative prediction of the role of perturbations and allows a characterization of a protein-protein interaction network.     

A new culture system for in situ observation of the growth and development of Eucyclops serrulatus (Copepoda: Cyclopoida)

A practical and convenient method of rearing Eucyclops serrulatus in a microculture environment is described. A complete life cycle of E. serrulatus was maintained in a narrow space on a microscope slide glass on which a cover glass of 22 x 40 mm in size was mounted at a height of 0.8 mm. The culture medium was constituted by bottled mineral water boiled with grains of Glycine max (soybean). Chilomonas paramecium, a free-living protozoan organism, was provided as live food. Growth of nauplii hatched from eggs to the first stage of copepodite took an average of 7.7 days, and the growth of copepodite 1 to the egg-bearing adult female took an average of 20.1 days in the microculture cell with an average life time of 44.7 days. Continuous passage of copepods was successfully maintained as long as sufficient medium and food were provided. The microculture method enables an in situ microscopic observation on the growth and developmental process of helminth larvae experimentally infected to copepods as well as of copepod itself. Furthermore, it does not require anesthetization and, therefore, minimize the amount of stress exposed to copepods during the handling process.     

Nucleolin: acharan sulfate-binding protein on the surface of cancer cells

Glycosaminoglycans (GAGs) are complex polysaccharides that participate in the regulation of physiological processes through the interactions with a wide variety of proteins. Acharan sulfate (AS), isolated from the giant African snail Achatina fulica, primarily consists of the repeating disaccharide structure alpha-D-N-acetylglucosaminyl (1-->4) 2-sulfoiduronic acid. Exogenous AS was injected subcutaneously near the tumor tissue in C57BL/6 mice that had been implanted with Lewis lung carcinoma cells (LLCs). The location of AS in the tumor was assessed by staining of sectioned tissues with alcian blue and periodic acid-Schiff (PAS) reagent. In vitro assays indicated binding of cells to 50 microg/ml AS (or heparin) after a 5-h incubation. Immunofluorescence assays, using anti-AS antibody, detected AS at the cell surface. The outer-surface of LLCs were next biotinylated to identify the AS-binding proteins. Biotinylated cells were lysed, and the lysates were fractionated on the AS affinity column using a stepwise salt gradient (0, 0.1, 0.3, 0.5, 0.7, 1.0, and 2.0 M). The fractions were analyzed by SDS-PAGE with silver staining and western blotting. We focused on the proteins with high affinity for AS (eluting at 1 M NaCl) and detected only two bands by western blotting. ESI Q-TOF MS analysis of one of these bands, molecular weight approximately 110 kDa, showed it to be nucleolin. A phosphorylated form of nucleolin on the surface of cells acts as a cell surface receptor for a variety of ligands, including growth factors (i.e., basic fibroblast growth factor) and chemokines (i.e., midkine). These results show that nucleolin is one of several AS-binding proteins and suggest that AS might demonstrate its tumor growth inhibitory activity by binding the nucleolin receptor protein on the surface of cancer cells.     

Sepiapterin reductases from Chlorobium tepidum and Chlorobium limicola catalyze the synthesis of L-threo-tetrahydrobiopterin from 6-pyruvoyltetrahydropterin

The ORF sequences of the gene encoding sepiapterin reductase were cloned from the genomic DNAs of Chlorobium tepidum and Chlorobium limicola, which are known to produce L-threo- and L-erythro-tetrahydrobiopterin (BH4)-N-acetylglucosamine, respectively. The deduced amino acid sequence of C. limicola consists of 241 residues, while C. tepidum SR has three residues more at the C-terminal. The overall protein sequence identity was 87.7%. Both recombinant proteins generated from Escherichia coli were identified to catalyze reduction of diketo compound 6-pyruvoyltetrahydropterin to L-threo-BH4. This result suggests that C. limicola needs an additional enzyme for L-erythro-BH4 synthesis to yield its glycoside. The catalytic activity of Chlorobium SRs also supports the previously proposed mechanism of two consecutive reductions of C1' carbonyl group of 6-pyruvoyltetrahydropterin via isomerization reaction.     

Dictyostelium phenylalanine hydroxylase is activated by its substrate phenylalanine

We have studied the regulatory function of Dictyostelium discoideum Ax2 phenylalanine hydroxylase (dicPAH) via characterization of domain structures. Including the full-length protein, partial proteins truncated in regulatory, tetramerization, or both, were prepared from Escherichia coli as his-tag proteins and examined for oligomeric status and catalytic parameters for phenylalanine. The proteins were also expressed extrachromosomally in the dicPAH knockout strain to examine their in vivo compatibility. The results suggest that phenylalanine activates dicPAH, which is functional in vivo as a tetramer, although cooperativity was not observed. In addition, the results of kinetic study suggest that the regulatory domain of dicPAH may play a role different from that of the domain in mammalian PAH.

Structured summary of protein interactions

dicPAH and dicPAHbind by molecular sieving (View Interaction: 1, 2, 3, 4)     

Fission yeast Rap1 homolog is a telomere-specific silencing factor and interacts with Taz1p

Taz1p is the fission yeast orthologue of human TRF2, a telomeric repeat-binding protein. Delta(taz1) mutants are defective in telomeric silencing, telomere length control, and meiotic recombination events. A recent report demonstrated that the human Rap1p homolog (hRap1) is recruited to telomere by interaction with TRF2, arguing that the telomere control mechanism of higher eukaryotes is distinct from that of the budding yeast. Taz1p showed a significant similarity to human TRF2, but not with the budding yeast Rap1p (scRap1p). This suggests that Taz1p and TRF2 share common features in telomere regulation. To assess the roles of Taz1p in telomere-related functions in detail, we attempted to identify a protein(s) that interacts with Taz1p by using two-hybrid screening. Interestingly, the sequence analysis of a positive clone revealed a perfect match with a Rap1 homolog in S. pombe (spRap1), which showed a significant homology with scRap1p and hRap1p. Here we show that the spRap1 deficiency in haploid cells is viable, which results in increased telomere length regulation, disruption of telomere silencing, and aberrant meiosis (like the delta(taz1) mutant). This suggests that spRap1p might be recruited to the telomere by Taz1p and play crucial roles in telomere function. Interestingly, the delta(rap1) mutants in fission yeast are defective only for telomere silencing. Therefore, the role of spRap1p may be distinct from that of scRap1p, which is involved in the silencing at both the telomere and mating type locus. Our data, therefore, suggest that the regulation mechanisms of telomere in fission yeast resemble that of higher eukaryotic cells rather than the budding yeast.