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21.
JUN FENG ZHANG 《Palaeontology》2010,53(2):307-317
Abstract: Four new Brachycera fossils were collected from the Daohugou biota, China. Among these, two impressions demonstrating peculiar wing venation can be designated as two new species of a new genus (Mostovskisargus portentosus gen. et sp. nov. and M. signatus sp. nov.) referred to a new subfamily Mostovskisarginae (subfam. nov.) within Archisargidae. The third impression belongs to a new species (Calosargus (Pterosargus) sinicus sp. nov.) referred to the subgenus Pterosargus Mostovski, 1997 of Calosargus Mostovski, 1997 within Archisarginae, Archisargidae. It is only the second member of the subgenus Pterosargus worldwide. The fourth impression is a nearly complete fly, Jurassinemestrinus orientalis gen. et sp. nov. referable to Rhagionemestriidae. It reveals new morphological data about rhagionemestriids and extends the geographical distribution of this group beyond Europe and Central Asia during the Mesozoic. A correlation for the archisargid composition of taxa in Daohugou and Karabastau formations is discussed. The age of the fly‐bearing strata is briefly reassessed and can be more accurately limited to the Callovian–Oxfordian based on both biostratigraphical correlation and radiometric dating. 相似文献
22.
Pollen germination and pollen‐tube growth under natural conditions were observed in a population of a distylous species, Primula sieboldii, in which partial self‐compatibility has been demonstrated in some long‐styled genets. We observed post‐pollination processes microscopically in styles collected after self‐morph and inter‐morph hand pollination (with standardized pollen load on the stigmas) in four genets each from the following three ‘genet types’: self‐incompatible long‐styled (SI), partially self‐compatible long‐styled (SC) and self‐incompatible short‐styled morph genets. Irrespective of the genet type, pollen germination began within 24 h after pollination and tubes of pollen reached to the style base with 48–96 h after inter‐morph pollination. Although pollen tubes germinated after self‐pollination in the SC genets, the number of germinated pollen tubes was significantly lower than in the case of inter‐morph pollination. Few pollen tubes germinated after self‐pollination of the SI or short‐styled genets. In SC genets, the rate of pollen‐tube growth did not differ between self‐morph and inter‐morph pollination (~1.9 mm/day). Therefore, differences in self‐compatibility between SC and SI genets in P. sieboldii are likely to be attributable to differential pollen germination rates rather than to differential pollen‐tube growth rates. 相似文献
23.
24.
LIMIN LU JUN WEN ZHIDUAN CHEN 《Botanical journal of the Linnean Society. Linnean Society of London》2012,168(1):43-63
Parthenocissus (the Virginia creeper genus, Vitaceae) consists of 13 species and shows a disjunct distribution between Asia and North America. We investigated the inflorescence structure, calyx morphology, appendages on the inner side of petals, leaf epidermis, pollen and seed characters throughout the genus. A combined phylogenetic analysis with 27 morphological and 4137 molecular characters was conducted and the result was largely congruent with that of the previous molecular work, but with higher resolution. The combined analysis identified two clades corresponding to the Asian and North American taxa. Parthenocissus feddei was resolved as closely related to the clade containing P. cuspidifera, P. heterophylla and P. semicordata. The four species share synapomorphies of having conspicuously raised veinlets, an obscurely five‐ (to eight‐) lobed calyx, appendages on the inner side of petals covering the entire length of anthers and foveolate pollen exine ornamentation. Within the Old World clade, the pentafoliolate species were weakly supported as more closely related to species with both simple and trifoliolate leaves. Furthermore, the ancestral states of tendril apices, inflorescence structure, appendages on the inner side of petals and exine ornamentation of pollen grains were reconstructed on the molecular strict consensus tree. The appendages on the inner side of petals and exine ornamentation of pollen grains were suggested to be important characters in the taxonomy of Parthenocissus, especially for species with trifoliolate leaves. Finally, the previous classifications of Parthenocissus were evaluated within the phylogenetic framework. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, ?? , ??–??. 相似文献
25.
HuYJ ZangL 《Cell research》2001,11(4):293-300
INTRODUCTIONThe CD4 T cells can be subdivided intoTh1 and Th2 subsets based on their secreted cy-tokine profile. Th1 cells characteristical1y secreteInterferonry (IFN--ry), whereas Th2 cells maiuly pro--duce IL--4[1]. IL-12 po1arizes the differentiation ofnaitre, CD4 T cells towards Th1 pathWay, in con-trast IL--4 directs T cell differentiation towards Th2pathWay The broken balance between Th1 and Th2immune responses and predominant Th1 responseare crucial factors in initiation… 相似文献
26.
GUO XING ZHONG JUN DA SU QING WEN SUN BING HUA JIAO Department of Biochemistry Molecular Biology Second Military Medical University Shanghai School of Life Sciences Medical Engineering Tongji University Shanghai China Shangha 《Cell research》2001,(4)
INTRODUCTIONEstrogen has been known to exert extensive effects via estrogen receptor (ER) on diverse physio-logical and develoPmental functions of the brain[1,2]. It has been observed that the distribution ofthe classical ER subtype-a (ERa) and the recentlycharacterized novel ER subtype--fi (ERg), and theirexpression patterns (ERcr/ERfi) vary greatly amongvarious brain regions[1, 3]. These evidences suggestthat each ER subtype may play a different role inestrogen's effects on the br… 相似文献
27.
Human fibrinogen-related protein-1/liver fibrinogen-related protein-1 (HFREP-1/LFIRE-1), a liver-specificprotein, is a member of fibrinogen superfamily that exerts various biological activities. However, the func-tion of HFREP-1/LFIRE-1 in liver remains unknown. Here we isolated its mouse ortholog gene-mousefibrinogen-related protein-1 (mfrep-1), which encoded 314 amino acids, exhibiting 80.4% similarity toHFREP-1/LFIRE-1. Northern blot analysis revealed that 1.2-kb mfrep-1 mRNA was detected selectivelyin mouse liver. To explore the function of MFREP-1, we examined the levels of mfrep-1 mRNA duringregeneration after 70% partial hepatectomy (PHx) in mice. mfrep-1 mRNA increased in the regeneratingliver and reached the first shoulder peak at 2-4 h after PHx. Cycloheximide pretreatment could suppress theinduction of mfrep-1, indicating the up-regulation of this gene need de novo protein synthesis. Its mRNAcontinued to elevate at 6 h thereafter and reached the second peak at 24 h. The enhanced expression ofmfrep-1 maintained high until 72 h and then declined slowly to the basal level. Immunohistochemistryassessment confirmed the up-regulated expression of MFREP-1 protein in parenchymal cells during liverregeneration. These data suggested that MFREP-1 might play an important role in liver regeneration andbe involved in the regulation of cell growth. 相似文献
28.
XU LIANG ZHI‐HE ZHANG LIANG ZHANG WEN‐PING ZHANG FU‐JUN SHEN ZHI YANG RONG HOU WEI HE KUN WEI BI‐SONG YUE 《Molecular ecology resources》2007,7(6):1012-1014
A total of 15 polymorphic tetranucleotide microsatellite loci in the red panda, Ailurus fulgens, were characterized in this study. Based on evaluations of 33 red pandas, the number of observed alleles for each locus ranged from seven to 17 and the expected and observed heterozygosities were 0.412–0.897 and 0.121–0.909, respectively. The mean polymorphic information content was 0.721. These markers would greatly strengthen the utilization of microsatellite tools in genetic variation studies in red panda populations. 相似文献
29.
大鼠初级感觉神经外周末梢间信息传递的观察 总被引:6,自引:1,他引:5
实验切断麻醉大鼠一侧T5-L1脊神经背部皮支的中枢端,用50Hz,0.2ms,总时间为2s的方波逆行刺激其中一皮支的外周端,记录其相邻皮支的电活动。结果发现刺激停止后25s内被记录皮支的放电迅速增加,继而逐渐恢复到刺激前的水平;414个序列实验结果的累积时程分析表明:被记录皮支的放电频率在刺激停止后的第2秒达最大值,并持续3s,从第5秒开始逐渐下降,第25秒及以后恢复到刺激前的水平;放电频率的增加 相似文献
30.
本文用膜片箝技术研究了孕烯酮硫酸醌对大脑皮层锥体神经元膜48pS延迟整流型钾通道开放概率和平均开放时间的影响。在加入PS后40s,即可观察到IK通道的开放概率增大,平均开放时间延长,表明PS加强IK通道的活动。在浓度为300-100μmol/L的范围内,其增大程度与PS的浓度呈正相关,但PS不影响通道的电流幅度。 相似文献