Histamine and H1 -histamine receptors faster venous circulation

The study has analysed the action of histamine in the rabbit venous system and evaluated its potential role in contraction during increased venous pressure. We have found that a great variety exists in histamine sensitivity and H(1) -histamine receptor expression in various types of rabbit veins. Veins of the extremities (saphenous vein, femoral vein, axillary vein) and abdomen (common iliac vein, inferior vena cava) responded to histamine by a prominent, concentration-dependent force generation, whereas great thoracic veins (subclavian vein, superior vena cavas, intrathoracic part of inferior vena cava) and a pelvic vein (external iliac vein) exhibited slight sensitivity to exogenous histamine. The lack of reactivity to histamine was not due to increased activity of nitric oxide synthase (NOS) or heme oxygenase-1. H(1) -histamine receptor expression of veins correlated well with the histamine-induced contractions. Voltage-dependent calcium channels mediated mainly the histamine-induced force generation of saphenous vein, whereas it did not act in the inferior vena cava. In contrast, the receptor-operated channels were not involved in this response in either vein. Tyrosine phosphorylation occurred markedly in response to histamine in the saphenous vein, but not in the inferior vena cava. Histamine induced a prominent ρ kinase activation in both vessels. Protein kinase C and mitogen-activated protein kinase (MAPK) were not implicated in the histamine-induced intracellular calcium sensitization. Importantly, transient clamping of the femoral vein in animals caused a short-term constriction, which was inhibited by H(1) -histamine receptor antagonist in vivo. Furthermore, a significantly greater histamine immunopositivity was detected in veins after stretching compared to the resting state. We conclude that histamine receptor density adapts to the actual requirements of the circulation, and histamine liberated by the venous wall during increased venous pressure contributes to the contraction of vessels, providing a force for the venous return.     

Human iron transporters

Human iron transporters manage iron carefully because tissues need iron for critical functions, but too much iron increases the risk of reactive oxygen species. Iron acquisition occurs in the duodenum via divalent metal transporter (DMT1) and ferroportin. Iron trafficking depends largely on the transferrin cycle. Nevertheless, non-digestive tissues have a variety of other iron transporters that may render DMT1 modestly redundant, and DMT1 levels exceed those needed for the just-mentioned tasks. This review begins to consider why and also describes advances after 2008 that begin to address this challenge.     

Structural characterization of inhibitor complexes with checkpoint kinase 2 (Chk2), a drug target for cancer therapy

Chk2 (checkpoint kinase 2) is a serine/threonine kinase that participates in a series of signaling networks responsible for maintaining genomic integrity and responding to DNA damage. The development of selective Chk2 inhibitors has recently attracted much interest as a means of sensitizing cancer cells to current DNA-damaging agents used in the treatment of cancer. Additionally, selective Chk2 inhibitors may reduce p53-mediated apoptosis in normal tissues, thereby helping to mitigate adverse side effects from chemotherapy and radiation. Thus far, relatively few selective inhibitors of Chk2 have been described and none have yet progressed into clinical trials. Here, we report crystal structures of the catalytic domain of Chk2 in complex with a novel series of potent and selective small molecule inhibitors. These compounds exhibit nanomolar potencies and are selective for Chk2 over Chk1. The structures reported here elucidate the binding modes of these inhibitors to Chk2 and provide information that can be exploited for the structure-assisted design of novel chemotherapeutics.     

Genetic analysis of D-xylose metabolism by endophytic yeast strains of Rhodotorula graminis and Rhodotorula mucilaginosa

Two novel endophytic yeast strains, WP1 and PTD3, isolated from within the stems of poplar (Populus) trees, were genetically characterized with respect to their xylose metabolism genes. These two strains, belonging to the species Rhodotorula graminis and R. mucilaginosa, respectively, utilize both hexose and pentose sugars, including the common plant pentose sugar, D-xylose. The xylose reductase (XYL1) and xylitol dehydrogenase (XYL2) genes were cloned and characterized. The derived amino acid sequences of xylose reductase (XR) and xylose dehydrogenase (XDH) were 32%～41% homologous to those of Pichia stipitis and Candida. spp., two species known to utilize xylose. The derived XR and XDH sequences of WP1 and PTD3 had higher homology (73% and 69% identity) with each other. WP1 and PTD3 were grown in single sugar and mixed sugar media to analyze the XYL1 and XYL2 gene regulation mechanisms. Our results revealed that for both strains, the gene expression is induced by D-xylose, and that in PTD3 the expression was not repressed by glucose in the presence of xylose.     

Exploitation of mitochondrial nad6 as a complementary marker for studying population variability in Lepidoptera

The applicability of mitochondrial nad6 sequences to studies of DNA and population variability in Lepidoptera was tested in four species of economically important moths and one of wild butterflies. The genetic information so obtained was compared to that of cox1 sequences for two species of Lepidoptera. nad6 primers appropriately amplified all the tested DNA targets, the generated data proving to be as informative and suitable in recovering population structures as that of cox1. The proposal is that, to obtain more robust results, this mitochondrial region can be complementarily used with other molecular sequences in studies of low level phylogeny and population genetics in Lepidoptera.     

The origin of the Tibetan Mastiff and species identification of Canis based on mitochondrial cytochrome c oxidase subunit I (COI) gene and COI barcoding

DNA barcoding is an effective technique to identify species and analyze phylogenesis and evolution. However, research on and application of DNA barcoding in Canis have not been carried out. In this study, we analyzed two species of Canis, Canis lupus (n = 115) and Canis latrans (n = 4), using the cytochrome c oxidase subunit I (COI) gene (1545 bp) and COI barcoding (648 bp DNA sequence of the COI gene). The results showed that the COI gene, as the moderate variant sequence, applied to the analysis of the phylogenesis of Canis members, and COI barcoding applied to species identification of Canis members. Phylogenetic trees and networks showed that domestic dogs had four maternal origins (A to D) and that the Tibetan Mastiff originated from Clade A; this result supports the theory of an East Asian origin of domestic dogs. Clustering analysis and networking revealed the presence of a closer relative between the Tibetan Mastiff and the Old English sheepdog, Newfoundland, Rottweiler and Saint Bernard, which confirms that many well-known large breed dogs in the world, such as the Old English sheepdog, may have the same blood lineage as that of the Tibetan Mastiff.     

Complete mitochondrial genome of Tubulipora flabellaris (Bryozoa: Stenolaemata): the first representative from the class Stenolaemata with unique gene order

Mitochondrial genomes play a significant role in the reconstruction of phylogenetic relationships within metazoans. There are still many controversies concerning the phylogenetic position of the phylum Bryozoa. In this research, we have finished the complete mitochondrial genome of one bryozoan (Tubulipora flabellaris), which is the first representative from the class Stenolaemata. The complete mitochondrial genome of T. flabellaris is 13,763 bp in length and contains 36 genes, which lacks the atp8 gene in contrast to the typical metazoan mitochondrial genomes. Gene arrangement comparisons indicate that the mitochondrial genome of T. flabellaris has unique gene order when compared with other metazoans. The four known bryozoans complete mitochondrial genomes also have very different gene arrangements, indicates that bryozoan mitochondrial genomes have experienced drastic rearrangements. To investigate the phylogenetic relationship of Bryozoa, phylogenetic analyses based on amino acid sequences of 11 protein coding genes (excluding atp6 and atp8) from 26 metazoan complete mitochondrial genomes were made utilizing Maximum Likelihood (ML) and Bayesian methods, respectively. The results indicate the monopoly of Lophotrochozoa and a close relationship between Chaetognatha and Bryozoa. However, more evidences are needed to clarify the relationship between two groups. Lophophorate appeared to be polyphyletic according to our analyses. Meanwhile, neither analysis supports close relationship between Branchiopod and Phoronida. Four bryozoans form a clade and the relationship among them is T. flabellaris + (F. hispida + (B. neritina + W. subtorquata)), which is in coincidence with traditional classification system.     

Physiological and biochemical response of potato (Solanum tuberosum L. cv. Kara) to O3 and antioxidant chemicals: possible roles of antioxidant enzymes

An Egyptian cultivar of potato (Solanum tuberosum L. cv. Kara) was grown in the field at two locations in northern Egypt: a ‘rural’ and a ‘suburban’ site, from October 2000 and November 2002. The antiozonant ethylenediurea (EDU) and the fungicide chlorothalonil (1,3‐benzenedicarbonitrile‐2,4,5,6 tetrachloroisophthalnitrile) were applied as a foliar spray to plants at both sites. It was found that foliar injury symptoms were reduced greatly in plants treated with EDU and/or chlorothalonil, and the yield of treated plants was higher than that of the untreated ones, with the EDU having a greater protection than chlorothalonil. Antiozonant (EDU) and fungicide (chlorothalonil) combination sprays were even more effective in reducing O₃ injury. Moreover, the percentage of protection was higher in the rural area than in the suburban one, and this was associated with higher levels of O₃ recorded in the rural area. The response to O₃, EDU, and chlorothalonil of the leaf antioxidant scavenger system was examined. Antiozonant‐treated plants had the highest reduced glutathione/oxidised glutathione ratio. The results suggest that EDU and chlorothalonil do not act directly as antiozonant to inhibit O₃ injury but act through maintaining some antioxidant enzymes during O₃ exposure. To the best of knowledge, this is the first report demonstrating the marked enhancement of yield and plant oxidative enzymes by fungicides as a mechanism of protecting plants against noxious oxidative stress from the environment in the developing world.     

REMARKABLE CONSERVATION OF INTERNALLY TRANSCRIBED SPACER SEQUENCES OF ARTHROSPIRA (“SPIRULINA” ) (CYANOPHYCEAE,CYANOBACTERIA) STRAINS FROM FOUR CONTINENTS AND OF RECENT AND 30‐YEAR‐OLD DRIED SAMPLES FROM AFRICA1

The internally transcribed spacer (ITS) sequences of 21 Arthrospira clonal strains from four continents and assigned to four different species (A. platensis, A. maxima, A. fusiformis, A. indica) in the culture collections were determined. Two main clusters, I and II, were differentiated by 49 positions out of 475 nt or 477 nt, respectively. Each cluster was further subdivided into two subclusters. Subclusters I.A and I.B were separated by two substitutions, whereas subclusters II.A and II.B were distinguished by four substitutions. After direct sequencing of the PCR products, three dried samples from Chad aged between 3 months and 35 years yielded a sequence belonging to subcluster I.A, as did a recent commercial product. The strains grown in production plants belonged to the same (sub)clusters as strains from culture collections, mainly I.A and II. PCR primers specific for each cluster and subcluster were designed and tested with crude cell lysates of Arthrospira strains. One dried sample (“dihé” 1) and a herbarium sample from Lake Sonachi (Kenya) only contained I.A sequences, whereas the commercial product was a mixture of the four genotypes and the other two dried samples contained minor polymorphisms characteristic of different clusters. Five clonal Arthrospira strains, thought to be duplicates, showed the simultaneous presence of the two forms of the four diagnostic positions that distinguish subclusters genotype II.A and genotype II.B. This is likely to be caused by multiple copies of the rDNA operon, in a intermediate stage of homogenization between subcluster II.A and subcluster II.B. The high conservation of ITS sequences is in contrast with the assignment to four different species, the great morphological variability of the strains, and their wide geographic distribution.