Centipedes are one of the oldest terrestrial arthropods belonging to the sub phylum Myriapoda. With the expansion of our understanding of the application of the two centipedes Scolopendra morsitans and Scolopendra hainanum, belonging to the order Scolopendromorpha, an exhaustive classification was required. Although consensus has been reached on the phylogeny of Chilopoda based on morphological traits, recent analyses based on molecular data exhibited differences in results.
Methods and results
The mitochondrial genome sequences of S. morsitans and S. hainanum were obtained by next-generation sequencing. S. morsitans contains 13 PCGs, two rRNAs, 11 tRNAs, and one CR. whereas S. hainanum contains 12 PCGs, of which ATP8 remains unpredicted, two rRNAs, 14 tRNAs, and one CR. An obvious tRNA rearrangement was found in the genus Scolopendra. S. morsitans exhibited a loss of trnW, trnC, trnI, trnK, trnD, trnA, trnN, trnQ, trnF, trnT, trnS, trnL, and trnV, and a repeat of trnR and trnL. S. hainanum exhibited a loss of trnQ, trnC, trnW, trnI, trnD, trnQ, trnP, and trnV. Phylogenetic analyses of centipedes based on 12 PCGs supported the sister relationship between the orders Geophilomorpha and Lithobiomorpha and a close relationship between Scolopendra dehaani and S. hainanum.
Conclusions
The new mitogenomes determined in this study provide new genomic resources for gene rearrangements and contribute to the understanding of the evolution of gene rearrangement in Chilopoda.
Serine proteases play a crucial role in host-pathogen interactions. In the innate immune system of invertebrates, multi-domain protease inhibitors are important for the regulation of host-pathogen interactions and antimicrobial activities. Serine protease inhibitors, 9.3-kDa CrSPI isoforms 1 and 2, have been identified from the hepatopancreas of the horseshoe crab, Carcinoscorpius rotundicauda. The CrSPIs were biochemically active, especially CrSPI-1, which potently inhibited subtilisin (Ki = 1.43 nM). CrSPI has been grouped with the non-classical Kazal-type inhibitors due to its unusual cysteine distribution. Here we report the crystal structure of CrSPI-1 in complex with subtilisin at 2.6 Å resolution and the results of biophysical interaction studies. The CrSPI-1 molecule has two domains arranged in an extended conformation. These two domains act as heads that independently interact with two separate subtilisin molecules, resulting in the inhibition of subtilisin activity at a ratio of 1:2 (inhibitor to protease). Each subtilisin molecule interacts with the reactive site loop from each domain of CrSPI-1 through a standard canonical binding mode and forms a single ternary complex. In addition, we propose the substrate preferences of each domain of CrSPI-1. Domain 2 is specific towards the bacterial protease subtilisin, while domain 1 is likely to interact with the host protease, Furin. Elucidation of the structure of the CrSPI-1: subtilisin (1∶2) ternary complex increases our understanding of host-pathogen interactions in the innate immune system at the molecular level and provides new strategies for immunomodulation. 相似文献
A series of 4(3H)-quinazolinone derivatives with dithiocarbamate side chains were synthesized and tested for their in vitro antitumor activity against human myelogenous leukemia K562 cells. Among them, (3,4-dihydro-2-methyl-4-oxoquinazolin-6-yl)methyl 4-(4-fluorophenyl)piperazine-1-carbodithioate 8q exhibited significant inhibitory activity against K562 cells with IC(50) value of 0.5 microM. 相似文献
Extracellular domains of the transmembrane glycoprotein, neuropilin-1 (Np1), specifically bind an array of factors and co-receptors
including class-3 semaphorins (Sema3a), vascular endothelial growth factor (VEGF), hepatocyte growth factor, platelet-derived
growth factor BB, transforming growth factor-β 1 (TGF-β1), and fibroblast growth factor2 (FGF2). Np1 may have a role in immune
response, tumor cell growth, and angiogenesis, but its relative expression in comparison to its co-primary receptors, VEGF
and Sema3a, is not known. In this study we determined the mRNA expression of Np1 and its co-receptors, VEGF and Sema3a, and
the ratio of VEGF/Sema3a in different human and rodent cell lines. Expression of Np1, VEGF and Sema3a is very low in cells
derived from normal tissues, but these proteins are highly expressed in tumor-derived cells. Furthermore, the ratio of VEGF/Sema3a
is highly variable in different tumor cells. The elevated mRNA expression of Np1 and its putative receptors in tumor cells
suggests a role for these proteins in tumor cell migration and angiogenesis. As different tumor cells exhibit varying VEGF/Sema3a
ratios, it appears that cancer cells show differential response to angiogenic factors. These results bring to light the individual
variation among the cancer-related genes, Np1, VEGF, and Sema3a, and provide an important impetus for the possible personalized
therapeutic approaches for cancer patients. 相似文献
Large-scale patterns of spatial variation in species geographic range size are central to many fundamental questions in macroecology and conservation biology. However, the global nature of these patterns has remained contentious, since previous studies have been geographically restricted and/or based on small taxonomic groups. Here, using a database on the breeding distributions of birds, we report the first (to our knowledge) global maps of variation in species range sizes for an entire taxonomic class. We show that range area does not follow a simple latitudinal pattern. Instead, the smallest range areas are attained on islands, in mountainous areas, and largely in the southern hemisphere. In contrast, bird species richness peaks around the equator, and towards higher latitudes. Despite these profoundly different latitudinal patterns, spatially explicit models reveal a weak tendency for areas with high species richness to house species with significantly smaller median range area. Taken together, these results show that for birds many spatial patterns in range size described in geographically restricted analyses do not reflect global rules. It remains to be discovered whether global patterns in geographic range size are best interpreted in terms of geographical variation in species assemblage packing, or in the rates of speciation, extinction, and dispersal that ultimately underlie biodiversity. 相似文献
In this study, we tested the hypothesis that spontaneously diabetic TallyHo (TH) mice, a novel polygenic model for type 2 diabetes, will exhibit endothelial dysfunction associated with an increased contribution from endothelium-derived contractile factors (EDCF). The cellular mechanisms underlying the increased contribution of EDCF were explored in 16 and 30-week-old male TH and age-matched male C57BL/6J mice (n=4-9). Blood glucose and serum lipid profiles were markedly increased in the TH mice. Superoxide generation, assessed with a lucigenin chemiluminescence assay, was markedly increased in the aortae of TH mice. Endothelium-dependent vascular relaxations and contractions to acetylcholine (ACh), but not endothelium-independent relaxations to sodium nitroprusside, were impaired and vascular contractions to phenylephrine were significantly enhanced in aortae from TH mice. Nomega-nitro-L-arginine methyl ester markedly increased the ACh-induced contractions in TH mice, whereas SQ29548, a thromboxane receptor antagonist, and cytochrome P450 (CYP) inhibitors 17-octadecynoic acid and sulfaphenazole, the latter being specific for CYP2C6 and 2C9, decreased and (or) normalized the contractile response to ACh in TH mice. The present study indicates that enhanced contribution of prostaglandin H2/thromboxane A2 receptor and CYP, likely CYP2C6 and 2C9, play a critical role in the pathogenesis of increased EDCF in the aortae of type 2 diabetic TH mice. 相似文献