椭圆食粉螨线粒体DNA CO Ⅰ基因片段序列分析

采用苯酚-氯仿-异戊醇抽提法提取了采自江西南昌和广州潮州2个地理种群的椭圆食粉螨Aleuro-glyphus ovatus Troupeau,1878基因组DNA。以相应引物对椭圆食粉螨线粒体DNA细胞色素氧化酶I亚基基因(mtDNA COI)进行PCR扩增,直接测序,得到379bp的碱基片断(国际基因库索引号EF527825),其碱基序列A、C、G、T含量分别为71bp(18.73%)、53bp(13.98%)、89bp(23.48%)、166bp(43.80%);江西南昌和广州潮州2个地理种群间的椭圆食粉螨mtDNACOI基因片段完全一致,未发现地理差异。     

Inhibition of fipronil and nonane metabolism in human liver microsomes and human cytochrome P450 isoforms by chlorpyrifos

Previous studies have established that chlorpyrifos (CPS), fipronil, and nonane can all be metabolized by human liver microsomes (HLM) and a number of cytochrome P450 (CYP) isoforms. However, metabolic interactions between these three substrates have not been described. In this study the effect of either coincubation or preincubation of CPS with HLM or CYP isoforms with either fipronil or nonane as substrate was investigated. In both co- and preincubation experiments, CPS significantly inhibited the metabolism of fipronil or nonane by HLM although CPS inhibited the metabolism of fipronil more effectively than that of nonane. CPS significantly inhibited the metabolism of fipronil by CYP3A4 as well as the metabolism of nonane by CYP2B6. In both cases, preincubation with CPS caused greater inhibition than coincubation, suggesting that the inhibition is mechanism based.     

Heterologous expression and in vitro assembly of the transmembrane cytochrome b6

Folding and assembly studies with alpha-helical membrane proteins are often hampered by the absence of high-level expression systems as well as by missing suitable in vitro refolding procedures. Experimental constraints and requirements for heterologous expression and in vitro assembly of cytochrome b6 have been examined and conditions for in vitro reconstitutions of the protein have been optimized. Cytochrome b6 can serve as an excellent model system for in vitro studies on the dynamic interplay of an apo-protein and heme cofactors during assembly of a transmembrane b-type cytochrome. In vitro assembled cytochrome b6 binds two hemes with different midpoint potentials and both ferri as well as ferro heme bind to the apo-cytochrome. However, the ferro cytochrome appears to be less stable than the ferri form.     

A molecular phylogeny of the nightjars (Aves: Caprimulgidae) suggests extensive conservation of primitive morphological traits across multiple lineages

We report a molecular re-assessment of the classification of the nightjars which draws conclusions that are strongly at odds with the traditional, morphology-based classifications. We used maximum likelihood and Bayesian methods to compare the cytochrome b gene for 14 species from seven of the 15 genera of the Caprimulgidae and partial cytochrome b sequence data was available for a further seven species including three further genera. We found that within the Caprimulgidae there were four geographically isolated clades with bootstrap support greater than 70%. One of these clades contained just Chordeiles species, the remaining three clades each contained a mixture of genera including Caprimulgus sp. A clade of exclusively South American nightjars included the genera Caprimulgus, Uropsalis, Eleopthreptus and Hydropsalis. A clade of African and Eurasian birds included Caprimulgus and Macrodipteryx. Phalaenoptilus nuttallii and Caprimulgus vociferous formed a clade of North American birds. Two ecological factors appear to make morphological classification potentially misleading: first, the apparent retention of primitive anti-predator and foraging-related traits across genetically divergent groups; second, rapid divergence in other traits, especially those related to mating, which generate high levels of morphological divergence between species that are genetically very similar. The cytochrome b data suggests that the genus Caprimulgus is not monophyletic and is restricted to Africa and Eurasia and that Caprimulgus species from outside this area have been misclassified as a consequence of retention of primitive adaptations for crepuscular/nocturnal living. Some other genera also appear to have little support from the cytochrome b data.     

Phylogenetic analysis of freshwater sponges provide evidence for endemism and radiation in ancient lakes

Morphologic and phylogenetic analysis of freshwater sponges endemic to lakes in Central Sulawesi, Siberia and South-East Europe is presented. We also analyzed several cosmopolitan sponge species from Eurasia and North America and included sponge sequences from public databases. In agreement with previous reports [Addis, J.S., Peterson, K.J., 2005. Phylogenetic relationships of freshwater sponges (Porifera, Spongillina) inferred from analyses of 18S rDNA, COI mtDNA, and ITS2 rDNA sequences. Zool. Scr. 34, 549-557], the metaniid sponge Corvomeyenia sp. was the most deeply branching species within a monophyletic lineage of the suborder Spongillina. Pachydictyum globosum (Malawispongiidae) and Nudospongilla vasta (Spongillidae), two morphologically quite distinct species from Sulawesi were found in a joint clade with Trochospongilla (Spongillidae) rendering Trochospongilla paraphyletic. Furthermore, Ochridaspongia sp., another Malawispongiidae, clustered far away from that clade, together with Ephydatia fluviatilis, making the latter family polyphyletic. The Lubomirskiidae endemic to Lake Baikal, Lubomirskia abietina, Baikalospongia bacillifera, B. intermedia, and Swartschewskia papyracea formed a well-supported clade that was most closely linked to the genus Ephydatia (99.9% identity over a total length of 2169 concatenated nucleotide positions). Our study indicates the frequent and independent origin of sponge species endemic to different freshwater ecosystems from a few cosmopolitan founder species. The highly specific primer sets newly developed here facilitate work on the molecular phylogeny and DNA barcoding of sponges.     

Molecular phylogeny and evolutionary history of Southeast Asian macaques forming the M. silenus group

The 12 presently recognized taxa forming the Macaca silenus group represent the most diverse lineage within the genus Macaca. The present study was set up to clarify the phylogenetic relationships of the extant members of the M. silenus group and to explain their geographical distribution patterns seen today. A combined approach involving the analysis of one paternal (TSPY) and two maternal (cyt b and 12S-16S rRNA) molecular markers enabled us to resolve the phylogenetic relationships within this lineage. Our Y chromosomal marker is not informative enough to allow detailed conclusion. Based on our mitochondrial data, however, M. pagensis, endemic to the three southern Mentawai islands (Sipora, North- and South Pagai), split off early (2.4-2.6 mya) and represents a sister clade to the macaques from the northern Mentawai island of Siberut and from those of the Southeast Asian mainland, which diverged in a radiation-like splitting event about 1.5-1.7 mya. By combining our new results with available data on behavioural as well as climate and sea level changes in Southeast Asia during the Plio- and Pleistocene, we have developed two scenarios for the evolutionary history of this primate group, which may help explain the current geographical distribution of its members.     

A polysaccharide of the marine alga Capsosiphon fulvescens induces apoptosis in AGS gastric cancer cells via an IGF-IR-mediated PI3K/Akt pathway

Because seaweed extracts have recently been found to have antioxidant and anti-tumor activities, we analyzed a hot-water-soluble polysaccharide (PS) of the marine alga Capsosiphon fulvescens for its potential as a functional foodstuff by determining its effects on cell growth and DNA synthesis. MTS assays showed that the C. fulvescens PS (Cf-PS) significantly inhibited the proliferation of cultured human cancer cells in a dose-dependent manner. Cf-PS-treated AGS cells exhibited a marked increase in caspase-3 activation and a decrease in Bcl-2 expression. In addition, phosphorylation of insulin-like growth factor-I receptor (IGF-IR) was decreased in Cf-PS-treated AGS cells as compared to non-treated control cells, which is consistent with PI3-kinase (PI3K)/Akt activation. Cf-PS also decreased IGF-I-stimulated recruitment of p85 to IGF-IR and IRS-1. These results indicate that Cf-PS inhibits cell proliferation and induces apoptosis by inhibiting IGF-IR signaling and the PI3K/Akt pathway.     

Apoptotic effect of Semecarpus anacardium nut extract on T47D breast cancer cell line

There is an increasing interest in identifying potent cancer-preventive and therapeutic agents against breast cancer. A great number of reports have in recent years dealt with anticancer characteristics of Semecarpus anacardium nut extract (SA). The majority of these studies has been targeted on the protective effect rendered to the living system rather than the preventive effect on cancer cells. SA was tested for its inhibitory effect on human breast cancer cells (T47D). Cytotoxicity analyses suggested that these cells had become apoptotic. SA was discovered to induce rapid Ca(2+) mobilization from intracellular stores of T47D cell line, and its cytotoxicity against T47D was well correlated with altered mitochondrial transmembrane potential. At the molecular level, these changes are accompanied by decrease in bcl(2) and increase in bax, cytochrome c, caspases and PARP cleavage, and ultimately by internucleosomal DNA fragmentation. Taken together, our results provide unprecedented evidence that SA triggers apoptotic signals in T47D cells.     

Forms of LonB protease from Archaeoglobus fulgidus devoid of the transmembrane domain: The contribution of the quaternary structure to the regulation of enzyme proteolytic activity

Deletion of the transmembrane domain (TM-domain) of Archaeoglobus fulgidus LonB protease (Archaeoglobus fulgidus (AfLon)) was shown to result in uncontrollable activation of the enzyme proteolytic site and in vivo autolysis yielding a stable and functionally inactive fragment consisting of both α-helical and proteolytic domains (αP). The ΔTM-AfLon-S509A enzyme form, obtained by site-directed mutagenesis of the catalytic Ser residue, is capable of recombination with the αP fragment. The mixed oligomers were shown to be proteolytically active, which indicates a crucial role of subunit interactions in the activation of the AfLon proteolytic site. The thermophilic nature of AfLon protease was found to be due to the special features of the enzyme activity regulation, the structure of ATPase domain, and the quaternary structure.