The complex climatic and geological history of Southeast Asia has been hypothesised to determine the most important aspects of the current phylogeographical structure and distribution of living organisms throughout the region. To test existing hypotheses, the genetic structure of the tire track eel, Mastacembelus favus, was investigated using 823 bp of mitochondrial DNA cytochrome b from 469 individuals from 51 localities encompassing its native range. The results classified all haplotypes into two major lineages, Lineage 1, which was further divided into Lineages 1a (lower Mekong, eastern Gulf of Thailand and Malay—Thai Peninsula), 1b (Banpakong River), 1c (Chao Phraya, Gulf of Thailand and Malay—Thai Peninsula) and 1d (Khlang Yai River), and Lineage 2, the upper reaches of the lower Mekong and the middle Mekong. Strong genetic discontinuities dated approximately 5 MYA were discovered in the Mekong with limited geographical overlap, suggesting a historically dissected drainage between two sections and species colonisation via different routes. The widespread Lineage 1 showed a strong signature of population expansion during the Pleistocene climate oscillation. Haplotype characteristics in the Malay—Thai Peninsula are hypothesised to result from postglacial dispersal from the Mekong and Chao Phraya through an extended Pleistocene drainage network.
Plant Molecular Biology - The knowledge of substrate specificity of XET enzymes is important for the general understanding of metabolic pathways to challenge the established notion that these... 相似文献
First total synthesis of methylgerambullone (MGB, 1) isolated from Glycosmis angustifolia was completed via a convergent route. The effect of MGB on the contractile responses of the isolated guinea-pig ileum induced by acetylcholine was investigated. As a result, it showed a potent relaxation rate (78.66 ± 4.30% at 100 mg/L) in a concentration-dependent manner on longitudinal smooth muscle contraction of isolated guinea-pig ileum induced by 1 μM acetylcholine. 相似文献
Studies of the effect of capsaicin (CAP) on the smooth muscle contractions have shown both contraction and relaxation in various preparations. The direct effect of CAP on gastric smooth muscle itself has not yet been reported, though CAP was reported to relax the isolated guinea-pig stomach by releasing nitric oxide from the CAP-sensitive sensory neurons. Here we showed an evidence that CAP evokes a prolonged relaxation of gastric antral circular smooth muscle (CAP-induced relaxation) by blocking the voltage-operated Ca2+ channels (VOCC) from inside of the cell. CAP suppressed dose-dependently the spontaneous contractions of guinea-pig gastric circular muscle strip under the condition without neural influence (IC50 = 5.8 microM). The inhibitory effects of CAP both on the high K+ contracture induced by 50 mM K+ Tyrode solution and on the slow waves recorded using a conventional intracellular microelectrode technique were similar to those of Ca2+ channel antagonists, indicating that Ca2+ influx through the VOCC is decreased by CAP. Ca2+ channel current (I(Ba)) decreased in a concentration-dependent manner on superfusing the physiological salt solution containing various concentrations of CAP. The steady-state activation and inactivation curves of I(Ba) were not affected by the treatment with CAP. The experiment using a synthetic water-soluble analog of CAP, DA-5018 x HCl, suggested that the acting site of CAP is present in the intracellular side. Spontaneous transient outward K+ currents (STOCs) recorded at a holding potential of 0 mV were also inhibited by CAP and verapamil, Ca channel blocker. Taken together, these results indicate that CAP-induced relaxation is associated with the direct inhibitory action on the VOCC from inside of the cell. 相似文献
Using homology-based PCR, we have isolated cDNA encoding a novel member (491 amino acids) of the angiopoietin (Ang) family from human adult heart cDNA and have designated it angiopoietin-3 (Ang3). The NH2-terminal and COOH-terminal portions of Ang-3 contain the characteristic coiled-coil domain and fibrinogen-like domain that are conserved in other known Angs. Ang3 has a highly hydrophobic region at the N-terminus (approximately 21 amino acids) that is typical of a signal sequence for protein secretion. Ang3 mRNA is most abundant in adrenal gland, placenta, thyroid gland, heart and small intestine in human adult tissues. Additionally, Ang3 is a secretory protein, but is not a mitogen in endothelial cells. 相似文献
Reactive oxygen species (ROS) cause oxidative stress and aging. The catalase gene is a key component of the cellular antioxidant defense network. However, the molecular mechanisms that regulate catalase gene expression are poorly understood. In this study, we have identified a DNA replication-related element (DRE; 5'-TATCGATA) in the 5'-flanking region of the Drosophila catalase gene. Gel mobility shift assays revealed that a previously identified factor called DREF (DRE- binding factor) binds to the DRE sequence in the Drosophila catalase gene. We used site-directed mutagenesis and in vitro transient transfection assays to establish that expression of the catalase gene is regulated by DREF through the DRE site. To explore the role of DRE/DREF in vivo, we established transgenic flies carrying a catalase-lacZ fusion gene with or without mutation in the DRE. The beta-galactosidase expression patterns of these reporter transgenic lines demonstrated that the catalase gene is upregulated by DREF through the DRE sequence. In addition, we observed suppression of the ectopic DREF-induced rough eye phenotype by a catalase amorphic Cat(n1) allele, indicating that DREF activity is modulated by the intracellular redox state. These results indicate that the DRE/DREF system is a key regulator of catalase gene expression and provide evidence of cross-talk between the DRE/DREF system and the antioxidant defense system. 相似文献