A SmD peptide induces better antibody responses to other proteins within the small nuclear ribonucleoprotein complex than to SmD protein via intermolecular epitope spreading

Autoantibody response against the small nuclear ribonucleoprotein (snRNP) complex is a characteristic feature of systemic lupus erythematosus. The current investigation was undertaken to determine whether activation of SmD-reactive T cells by synthetic peptides harboring T cell epitopes can initiate a B cell epitope spreading cascade within the snRNP complex. T cell epitopes on SmD were mapped in A/J mice and were localized to three regions on SmD, within aa 26-55, 52-69, and 86-115. Immunization with synthetic peptides SmD(31-45), SmD(52-66), and SmD(91-110) induced T and B cell responses to the peptides, with SmD(31-45) inducing the strongest response. However, only SmD(52-66) immunization induced T cells capable of reacting with SmD. Analysis of sera by immunoprecipitation assays showed that intermolecular B cell epitope spreading to U1RNA-associated A ribonucleoprotein and SmB was consistently observed only in the SmD(52-66)-immunized mice. Surprisingly, in these mice, Ab responses to SmD were at low levels and transient. In addition, the sera did not react with other regions on SmD, indicating a lack of intramolecular B cell epitope spreading within SmD. Our study demonstrates that T cell responses to dominant epitope on a protein within a multiantigenic complex are capable of inducing B cell responses to other proteins within the complex. This effect can happen without generating a good Ab response to the protein from which the T epitope was derived. Thus caution must be taken in the identification of Ags responsible for initiating autoimmune responses based solely on serological analysis of patients and animals with systemic autoimmune disorders.     

A new cell line from the embryonic tissue of Helicoverpa armigera HBN. (Lepidoptera: Noctuidae)

A new cell line from the embryonic tissue of Helicoverpa armigera was established and designated as NIV-HA-197. It was maintained in TNM-FH medium supplemented with 10% fetal bovine serum. The cell line at passage 20 had a heterogeneous population of cells consisting of mainly epithelial-like cells (70%), followed by fibroblast-like (27%), and multinucleated giant (3%) cells. The chromosome number ranged from 45 to 185. The growth curve at passage 40 showed a fivefold increase in cell number with a population-doubling time of approximately 60 h. The cell line was found infected with the microsporidium Nosema heliothids at passage 9. Using the antiprotozoan drug Metrogyl 400 and simultaneous heat treatment, the parasite was removed from the culture. The cell line can be cryopreserved for 30 mo. The species specificity of the new cell line was determined by studying the isoenzyme profile of four enzymes, viz., lactate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, and glucose 6-phosphate dehydrogenase, and by heteroduplex analysis. Heteroduplex analysis was used to analyze the mitochondrial 16S ribosomal ribonucleic acid gene sequences along with the host insect gene sequences, and 100% homology was obtained, confirming the conspecificity of the cell line. The cell line was found to be susceptible to the baculoviruses Autographa californica multiple nucleopolyhedrovirus, Spodoptera litura multiple nucleopolyhedrovirus, and H. armigera single nucleopolyhedrovirus (HaSNPV). More than 90% of the cells were infected by HaSNPV on the seventh post infection day (PID), and 28.8 x 10(6) NPV/ml was yielded on the 10th PID. The in vitro-grown HaSNPV caused 100% mortality, when fed to the second instar H. armigera larvae, in 6 d. Cessation of feeding was observed on the second PID.     

Comparison of 16S rRNA gene sequences of genus <Emphasis Type="Italic">Methanobrevibacter</Emphasis>

Background  

The phylogeny of the genus Methanobrevibacter was established almost 25 years ago on the basis of the similarities of the 16S rRNA oligonucleotide catalogs. Since then, many 16S rRNA gene sequences of newly isolated strains or clones representing the genus Methanobrevibacter have been deposited. We tried to reorganize the 16S rRNA gene sequences of this genus and revise the taxonomic affiliation of the isolates and clones representing the genus Methanobrevibacter.     

Fas ligand (CD178) cytoplasmic tail is a positive regulator of Fas ligand-mediated cytotoxicity

The cytotoxic function of CD178 (Fas ligand (FasL)) is critical to the maintenance of peripheral tolerance and immune-mediated tissue pathology. The active site of FasL resides at the FasL extracellular region (FasL(Ext)) and it functions through binding/cross-linking Fas receptor on target cells. In this study, we report that FasL(Ext)-mediated cytotoxicity is regulated by the FasL cytoplasmic tail (FasL(Cyt)). Deleting the N-terminal 2-70 aa (delta70) or N-terminal 2-33 aa (delta33) reduced the cytotoxic strength as much as 30- to 100-fold. By contrast, change in the cytotoxic strength was not observed with FasL deleted of the proline-rich domains (45-74 aa, delta PRD) in the FasL(Cyt). Our study identifies a novel function of FasL(Cyt) and demonstrates that FasL(2-33), a sequence unique to FasL, is critically required for the optimal expression of FasL(Ext)-mediated cytotoxicity.     

Homology modeling, simulation and molecular docking studies of catechol-2, 3-Dioxygenase from Burkholderia cepacia: Involved in degradation of Petroleum hydrocarbons

Catechol 2, 3-dioxygenase is present in several types of bacteria and undergoes degradation of environmental pollutants through an important key biochemical pathways. Specifically, this enzyme cleaves aromatic rings of several environmental pollutants such as toluene, xylene, naphthalene and biphenyl derivatives. Hence, the importance of Catechol 2, 3-dioxygenase and its role in the degradation of environmental pollutants made us to predict the three-dimensional structure of Catechol 2, 3-dioxygenase from Burkholderia cepacia. The 10ns molecular dynamics simulation was carried out to check the stability of the modeled Catechol 2, 3- dioxygenase. The results show that the model was energetically stable, and it attains their equilibrium within 2000 ps of production MD run. The docking of various petroleum hydrocarbons into the Catechol 2,3-dioxygenase reveals that the benzene, O-xylene, Toluene, Fluorene, Naphthalene, Carbazol, Pyrene, Dibenzothiophene, Anthracene, Phenanthrene, Biphenyl makes strong hydrogen bond and Van der waals interaction with the active site residues of H150, L152, W198, H206, H220, H252, I254, T255, Y261, E271, L276 and F309. Free energy of binding and estimated inhibition constant of these compounds demonstrates that they are energetically stable in their binding cavity. Chrysene shows positive energy of binding in the active site atom of Fe. Except Pyrene all the substrates made close contact with Fe atom by the distance ranges from 1.67 to 2.43 Å. In addition to that, the above mentioned substrate except pyrene all other made π-π stacking interaction with H252 by the distance ranges from 3.40 to 3.90 Å. All these docking results reveal that, except Chrysene all other substrate has good free energy of binding to hold enough in the active site and makes strong VdW interaction with Catechol-2,3-dioxygenase. These results suggest that, the enzyme is capable of catalyzing the above-mentioned substrate.     

IGF-1 modulates gene expression of proteins involved in inflammation,cytoskeleton, and liver architecture

Even though the liver synthesizes most of circulating IGF-1, it lacks its receptor under physiological conditions. However, according to previous studies, a damaged liver expresses the receptor. For this reason, herein, we examine hepatic histology and expression of genes encoding proteins of the cytoskeleton, extracellular matrix, and cell-cell molecules and inflammation-related proteins. A partial IGF-1 deficiency murine model was used to investigate IGF-1’s effects on liver by comparing wild-type controls, heterozygous igf1^+/?, and heterozygous mice treated with IGF-1 for 10 days. Histology, microarray for mRNA gene expression, RT-qPCR, and lipid peroxidation were assessed. Microarray analyses revealed significant underexpression of igf1 in heterozygous mice compared to control mice, restoring normal liver expression after treatment, which then normalized its circulating levels. IGF-1 receptor mRNA was overexpressed in Hz mice liver, while treated mice displayed a similar expression to that of the controls. Heterozygous mice showed overexpression of several genes encoding proteins related to inflammatory and acute-phase proteins and underexpression or overexpression of genes which coded for extracellular matrix, cytoskeleton, and cell junction components. Histology revealed an altered hepatic architecture. In addition, liver oxidative damage was found increased in the heterozygous group. The mere IGF-1 partial deficiency is associated with relevant alterations of the hepatic architecture and expression of genes involved in cytoskeleton, hepatocyte polarity, cell junctions, and extracellular matrix proteins. Moreover, it induces hepatic expression of the IGF-1 receptor and elevated acute-phase and inflammation mediators, which all resulted in liver oxidative damage.     

An analysis of Bat Hawk Macheiramphus alcinus diet in the Melaky Region of lowland western Madagascar

We present information on the prey taken by the Bat Hawk Macheiramphus alcinus in two different areas of lowland western central Madagascar. These are the first dietary data from Madagascar for this widespread Old World species. The recovered remains were almost exclusively of bats and birds, with a few examples of reptiles and insects. In total, 178 pellets were analysed. On the basis of minimum number of individuals and biomass, bats accounted for 58.3% and 30.3%, respectively, and birds 36.1% and 69.7%, respectively. Amongst the nine species of bats recovered from the pellets, four were represented by multiple individuals, particularly taxa belonging to the families Molossidae and Vespertilionidae that fly in open areas, and for the 11 species of identified birds, all were represented by a single individual. These patterns are interpreted as a specialisation of feeding on bats during a narrow window of time at dusk, as they leave day roost sites, and then using birds in a more general manner to fill in nutritional needs.     

Phylogenetic affiliation of Aeromonas culicicola MTCC 3249(T) based on gyrB gene sequence and PCR-amplicon sequence analysis of cytolytic enterotoxin gene

We determined the gyrB gene sequences of all 17 hybridizations groups of Aeromonas. Phylogenetic trees showing the evolutionary relatedness of gyrB and 16S rRNA genes in the type strains of Aeromonas were compared. Using this approach, we determined the phylogenetic position of Aeromonas culicicola MTCC 3249(T), isolated from midgut of Culex quinquefasciatus. In the gyrB based-analysis A. culicicola MTCC 3249(T) grouped with A. veronii whereas, it grouped with A. jandaei in the 16S rRNA based tree. The number of nucleotide differences in 16S rRNA sequences was less than found with the gyrB sequence data. Most of the observed nucleotide differences in the gyrB gene were synonymous. The Cophenetic Correlation Coefficient (CCC) for gyrB sequences was 0.87 indicating this gene to be a better molecular chronometer compared to 16S rRNA for delineation of Aeromonas species. This strain was found to be positive for the cytolytic enterotoxin gene. PCR-Amplicon Sequence Analysis (PCR-ASA) of this gene showed that the isolate is affiliated to type I and is potentially pathogenic. These PCR-ASA results agreed in part with the gyrB sequence results.