贵州四个民族人群线粒体DNA Region V的遗传多态性

目的研究世居贵州的侗族、仡佬族、土家族和彝族人群线粒体DNA Region V的遗传多态性。方法采用PCR-PAGE和克隆测序法对4个群体108份样本的mtDNA Region V进行序列分析。结果只检测到标准型和短型（即9-bp缺失）两种多态。贵州四个民族人群的平均9-bp缺失频率为22．2％，在侗族、仡佬族、土家族和彝族人群中依次为32．1％、22．6％、17．2％和15．0％。结论贵州四个民族mtDNA9-bp缺失频率均较高，这与其地域分布相一致；贵州彝族和土家族显示了相似的缺失频率，提示两者可能有共同的祖先。     

Artefactual responses of mesophyll conductance to CO2 and irradiance estimated with the variable J and online isotope discrimination methods

Studies with the variable J method have reported that mesophyll conductance (g_m) rapidly decreases with increasing intercellular CO₂ partial pressures (C_i) or decreasing irradiance. Similar responses have been suggested with the online isotope discrimination method, although with less consistency. Here we show that even when the true g_m is constant, the variable J method can produce an artefactual dependence of g_m on C_i or irradiance similar to those reported in previous studies for any of the following factors: day respiration and chloroplastic CO₂ photocompensation point are estimated with Laisk method; C_i or electron transport rate is positively biased; net photosynthetic rate is negatively biased; insufficient NADPH is assumed while insufficient ATP limits RuBP regeneration. The isotopic method produces similar artefacts if fractionation of carboxylation or C_i is positively biased or Δ¹³ negatively biased. A non‐zero chloroplastic resistance to CO₂ movement results in a qualitatively different dependence of g_m on C_i or irradiance and this dependence is only sensitive at low C_i. We thus cannot rule out the possibility that previously reported dependence of g_m on C_i or irradiance is a methodological artefact. Recommendations are made to take advantage of sensitivities of the variable J and isotopic methods for estimating g_m.     

Transgenic mice overexpressingγ-aminobutyric acid transporter subtypeⅠ develop obesity

INTRODUCTION7-aminobutyricacid(GABA)isthemajorinhibitoryneurotransmitterinthevertebratecelltralnervoussystemwhereitactingesavaxietyofGABAreceptortypes.TheneurotransmissionofGABAisthoughttobeterllilnatedbyit'srapidre-uptakeviaGABAtransportersintopresynapticneuronsandsurroundingglialcellsll,2].BesidesfUnctioningintheterminationofsynaptictransmission,GABAtransportersplayacriticalroleintheregUlationofthemagnitudeanddurationofGABA'sactionandmayajsomediatethereleaseofGABAintotheedrac…     

Jurassic artematopodid beetles and their implications for the early evolution of Artematopodidae (Coleoptera)

Fossil Artematopodidae are rarely collected and previously confined to middle Eocene Baltic amber. Here we report the first definitive artematopodid, Sinobrevipogon jurassicus gen. et sp.n. , from the Middle Jurassic Daohugou beds (c. 165 Ma) in Inner Mongolia, northeastern China. It exhibits a number of defining features of Artematopodidae, including paired carinae on prosternum and an internal apical interlocking tongue on the ventral side of each elytron. However, it differs from any modern Artematopodidae by having the mesocoxal cavitiy closed by the mesepimeron and the anterolateral edge of metanepisternum. The discovery of this new genus represents the earliest fossil record for Artematopodidae, highlighting the antiquity of the family. The systematic positions of Forticatinius Tan & Ren and Tarsomegamerus Zhang are discussed, and the latter is formally transferred to Artematopodidae. Phylogenetic relationships within Artematopodidae were investigated to elucidate the relationships between the two Jurassic genera and Recent genera. Eleven in‐group taxa and two out‐groups were included in a cladistic analysis based on 30 adult characters; the resulting tree recovered the family Artematopodidae in three clades: (i) Electribius authority, (ii) Ctesibius authority + Brevipogon authority + Sinobrevipogon + Tarsomegamerus and (iii) the remaining Recent genera, including Allopogonia authority.