The role of muscarinic receptors in the beneficial effects of adenosine against myocardial reperfusion injury in rats

Adenosine, a catabolite of ATP, displays a wide variety of effects in the heart including regulation of cardiac response to myocardial ischemia and reperfusion injury. Nonetheless, the precise mechanism of adenosine-induced cardioprotection is still elusive. Isolated Sprague-Dawley rat hearts underwent 30 min global ischemia and 120 min reperfusion using a Langendorff apparatus. Both adenosine and acetylcholine treatment recovered the post-reperfusion cardiac function associated with adenosine and muscarinic receptors activation. Simultaneous administration of adenosine and acetylcholine failed to exert any additive protective effect, suggesting a shared mechanism between the two. Our data further revealed a cross-talk between the adenosine and acetylcholine receptor signaling in reperfused rat hearts. Interestingly, the selective M(2) muscarinic acetylcholine receptor antagonist methoctramine significantly attenuated the cardioprotective effect of adenosine. In addition, treatment with adenosine upregulated the expression and the maximal binding capacity of muscarinic acetylcholine receptor, which were inhibited by the selective A(1) adenosine receptor antagonist 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX) and the nitric oxide synthase inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME). These data suggested a possible functional coupling between the adenosine and muscarinic receptors behind the observed cardioprotection. Furthermore, nitric oxide was found involved in triggering the response to each of the two receptor agonist. In summary, there may be a cross-talk between the adenosine and muscarinic receptors in ischemic/reperfused myocardium with nitric oxide synthase might serve as the distal converging point. In addition, adenosine contributes to the invigorating effect of adenosine on muscarinic receptor thereby prompting to regulation of cardiac function. These findings argue for a potentially novel mechanism behind the adenosine-mediated cardioprotection.     

Habenula "cholinergic" neurons co-release glutamate and acetylcholine and activate postsynaptic neurons via distinct transmission modes

Acetylcholine is an important neurotransmitter, and the habenulo-interpeduncular projection is a major cholinergic pathway in the brain. To study the physiological properties of cholinergic transmission in the interpeduncular nucleus (IPN), we used a transgenic mouse line in which the light-gated cation channel ChannelRhodopsin-2 is selectively expressed in cholinergic neurons. Cholinergic axonal terminals were activated by light pulses, and postsynaptic responses were recorded from IPN neurons. Surprisingly, brief photostimulation produces fast excitatory postsynaptic currents that are mediated by ionotropic glutamate receptors, suggesting wired transmission of glutamate. By contrast, tetanic photostimulation generates slow inward currents that are largely mediated by nicotinic acetylcholine receptors, suggesting volume transmission of acetylcholine. Finally, vesicular transporters for glutamate and acetylcholine are coexpressed on the same axonal terminals in the IPN. These results strongly suggest that adult brain "cholinergic" neurons can corelease glutamate and acetylcholine, but these two neurotransmitters activate postsynaptic neurons via different transmission modes.     

The Vacuolar Na+/H+ Antiporter Gene SsNHX1 from the Halophyte Salsola soda Confers Salt Tolerance in Transgenic Alfalfa (Medicago sativa L.)

A putative vacuolar Na⁺/H⁺ antiporter gene (SsNHX1) was isolated from the halophyte Salsola soda using the rapid amplification of cDNA ends method. Highly conserved regions of plant vacuolar Na⁺/H⁺ antiporter, including amiloride-binding domain, NHE (Na⁺/H⁺ exchange) domain, and 12 transmembrane segments, were found in the deduced amino acid sequence of SsNHX1. Multiple alignments of vacuolar Na⁺/H⁺ antiporters showed that SsNHX1 shared high identity with other plant vacuolar Na⁺/H⁺ antiporters. Phylogenetic relationship analysis indicated that SsNHX1 was clustered into the vacuolar Na⁺/H⁺ antiporter group. Taken together, these results suggest that SsNHX1 is a new member of the vacuolar Na⁺/H⁺ antiporter family. The effective expression of SsNHX1 in alfalfa (Medicago sativa L.) enhanced the salt tolerance of transgenic alfalfa which could grow in high concentrations of NaCl (up to 400 mM) over 50 days. This was the highest level of salt tolerance reported in transgenic plants. A further analysis of the physiological characteristics of transgenic and wild-type plants, including the Na⁺ and K⁺ contents, superoxide dismutase activity, the rate of electrolyte leakage, and the proline content, showed that large amounts of Na⁺ in the cytoplasm of leaves were transported into vacuoles by the exogenous Na⁺/H⁺ antiporter, which averted the toxic effects of Na⁺ to the cell of transgenic alfalfa.     

Seasonal Variation in the Activity Patterns and Time Budgets of <Emphasis Type="Italic">Trachypithecus francoisi</Emphasis> in the Nonggang Nature Reserve,China

Activity patterns and time budgets are 2 important aspects of animal behavior that researchers use to investigate ecological influences on individual behavior. We collected data on activity patterns and time budgets in 1 group of François’ langurs (Trachypithecus francoisi) from August 2003 to July 2004 in the Nonggang Nature Reserve, Guangxi Province, China, via instantaneous scan sampling method with 15-min intervals. The diurnal activity pattern of François’ langurs showed morning and afternoon feeding peaks, with a midday resting peak. Seasonal change was apparent in the activity pattern: 2 significant feeding peaks occurred in the dry season and only 1 significant feeding peak in the rainy season. The group spent an average of 51.5% of the daytime resting. Feeding and moving accounted on average for 23.1% and 17.3% of the activity budget, respectively. Subjects spent little time on social activities, averaging 2% for grooming and 5.5% for playing. Their time budgets showed significant seasonal variation: they spent a greater proportion of time on feeding and less time on resting and grooming in the dry season than in the rainy season. They also differed among different sex-age classes: immatures spent more time playing, whereas adults devoted more time to resting, feeding, and grooming. Correlations between time budgets and food items or food availability clearly indicated that François’ langurs might adopt an energy-maximizing strategy when preferred foods were scarce in the dry season.     

抗HIV-1 gp160独特型阳性抗体的序列分析及表达

为了确定从噬菌体抗体文库中筛选出的抗体的属性和方便目的基因的表达及其产物的纯化,对两株具有“１Ｆ７”独特型的抗ＨＩＶ－１ｇｐ１６０抗体基因进行了序列分析并构建了可溶性表达载体．发现３Ｂ株含有完整的Ｆａｂ段,１Ｄ株只有重链Ｆｄ段．序列测定表明两株克隆的Ｆｄ段基因完全相同,其可变区ＶＨ属于ＶＨⅠ亚群,而３Ｂ株的“轻链”序列与已知的人的κ和λ轻链无同源性．用从另外的Ｆａｂ抗体文库中筛选出来的３株抗乙肝表面抗原抗体的轻链与３Ｂ的重链重组,并选择一个ＨＩＶ－１ｇｐ１６０特异性较好的重组抗体株,命名为３Ｂｓ．构建了１Ｄ株与３Ｂｓ株的可溶性表达载体,免疫印迹实验证实了具有“１Ｆ７”独特型的抗ｇｐ１６０独特型阳性抗体的表达．     

Characterization of Wild-Type Adeno-Associated Virus Type 2-Like Particles Generated during Recombinant Viral Vector Production and Strategies for Their Elimination

The pSub201-pAAV/Ad plasmid cotransfection system was developed to eliminate homologous recombination which leads to generation of the wild-type (wt) adeno-associated virus type 2 (AAV) during recombinant vector production. The extent of contamination with wt AAV has been documented to range between 0.01 and 10%. However, the precise mechanism of generation of the contaminating wt AAV remains unclear. To characterize the wt AAV genomes, recombinant viral stocks were used to infect human 293 cells in the presence of adenovirus. Southern blot analyses of viral replicative DNA intermediates revealed that the contaminating AAV genomes were not authentic wt but rather wt AAV-like sequences derived from recombination between (i) AAV inverted terminal repeats (ITRs) in the recombinant plasmid and (ii) AAV sequences in the helper plasmid. Replicative AAV DNA fragments, isolated following amplification through four successive rounds of amplification in adenovirus-infected 293 cells, were molecularly cloned and subjected to nucleotide sequencing to identify the recombinant junctions. Following sequence analyses of 31 different ends of AAV-like genomes derived from two different recombinant vector stocks, we observed that all recombination events involved 10 nucleotides in the AAV D sequence distal to viral hairpin structures. We have recently documented that the first 10 nucleotides in the D sequence proximal to the AAV hairpin structures are essential for successful replication and encapsidation of the viral genome (X.-S. Wang et al., J. Virol. 71:3077–3082, 1997), and it was noteworthy that in each recombinant junction sequenced, the same 10 nucleotides were retained. We also observed that adenovirus ITRs in the helper plasmid were involved in illegitimate recombination with AAV ITRs, deletions of which significantly reduced the extent of wt AAV-like particles. Furthermore, the combined use of recombinant AAV plasmids lacking the distal 10 nucleotides in the D sequence and helper plasmids lacking the adenovirus ITRs led to complete elimination of replication-competent wt AAV-like particles in recombinant vector stocks. These strategies should be useful in producing clinical-grade AAV vectors suitable for human gene therapy.     

应用MUCAP试剂快速检测沙门氏菌

报告了用4-甲基伞形酮辛酯(4-Methylumbelliferyl-caprylate, MUCAP)快速检测沙门氏菌的特异性、敏感性和实用性。经HE,DHL,SS和麦康凯琼脂平板分离的65株沙门氏菌标准菌株和48株从食品中分离的沙门氏菌,用MUCAP测试均呈阳性反应;394株非沙门氏菌中呈阳性反应的假单胞菌、气单胞菌、邻单胞菌可通过氧化酶试验与沙门氏菌区分开;与粘质沙雷氏菌的交叉反应改用加1％蔗糖的分离平板也可排除。此方法的敏感性和特异性均达到97％以上,而且操作简便、快速,数分钟内即可完成。     

抗人肺腺癌单克隆抗体重,轻链可变区基因的分离克隆和序列测定

根据鼠免疫球蛋白重。轻链可变区基因ＦＲ１和ＦＲ４的序列保守性,化学合成了适于体外扩增Ｉｇ重、轻链可变区基因（Ｖ_Ｈ和Ｖ_Ｌ）的数对引物。以分泌抗人肺腺癌单抗的杂交瘤细胞株ＷＬＡ－２Ｃ４的基因组ＤＮＡ为模板,ＰＣＲ扩增Ｖ_Ｈ和Ｖ_Ｌ基因,分别克隆人ｐＵＣ１９载体。转化子经蓝、白斑筛选,酶切鉴定,双脱氧测序证实确为鼠单抗可变区基因,其中Ｖ_Ｈ基因全长为３４８ｂｐ,编码１１６ａａ,属重链ⅡＢ亚类;Ｖ_Ｌ基因全长３１８ｂｐ,编码１０６ａａ,属Ｋ轻链Ⅵ亚类。     

桔小实蝇国内研究概况

本综述了桔小实蝇的研究概况,包括桔小实蝇的分布、寄主、为害情况、种类、生物学、生态学、生理生化、经济重要性评价、综合防治等方面。