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11.
Bo-Yang Sun Xiu-Xi Wang Min-Xiao Ji Li-Bo Pang Qin-Qin Shi Su-Kuan Hou Dan-Hui Sun Shi-Qi Wang 《Palaeoworld》2018,27(2):258-270
We report Miocene mammalian faunas from three nearby localities: Kangping, Nanyu, and Yangping, in the Wushan Subbasin, Gansu Province, China. From the Kangping locality, we identified four species, Platybelodon grangeri, Hispanotherium wushanense n. sp., Kubanochoerus sp., and Turcocerus cf. kekemaidengensis, which indicate that this fauna can be correlated with MN7/8. From the Nanyu locality, we identified Platybelodon aff. tongxinensis, which, together with the previously reported specimens of Gomphotherium wimani and Micromeryx cf. flourensianus, enables us to correlate this fauna with MN6. The Yangping locality is found to be early Miocene in age based on the presence of cf. Gomphotherium sp. This occurrence is the earliest record of proboscideans in China, and thus represents the “Proboscidean Datum Event”. Evolutionary trends of Platybelodon and Hispanotherium are figured and discussed. The possibility of a geographic boundary associated with the eastern and western differentiation of species of Turcocerus and bunodont listriodonts in China is also evaluated. This boundary was consistent with the major division of the eastern and western mammalian faunas of the middle Miocene in China. The localities in Inner Mongolia suggest a large area with transitional habitats. 相似文献
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Shi-Qi Wang Xue-Ping Ji Nina G. Jablonski Denise F. Su Jun-Yi Ge Chang-Fen Ding Teng-Song Yu Wen-Qi Li Jaroon Duangkrayom 《Journal of Mammalian Evolution》2016,23(2):155-173
The origin of the Old World brevirostrine gomphotheriid taxon Sinomastodon has been debated intensively. The discovery of the oldest known Sinomastodon cranium, reported herein, supports its endemic origin and contradicts the prevalent theory of its North America origin. The new cranium was discovered from the Shuitangba locality, southwestern China, and is dated at about 6.5–6.0 Ma, corresponding to the latest Miocene. The new specimen shows distinct characters from the other species of Sinomastodon and was therefore named Sinomastodon praeintermedius, sp. nov. Newly discovered, isolated Sinomastodon-like teeth from the upper Miocene to the lower Pleistocene of southwestern China and Southeast Asia indicate a long evolution of Sinomastodon endemically. Remains of this species are frequently accompanied by those of stegodontid species. These two groups may have had a similar migration route, invading northern China and Japan during the latest Miocene, and retreating or becoming extinct from the Palearctic realm by the end of the Pliocene. The migrations of proboscideans may have been sparked by major paleoenviromental changes, i.e., the strengthened summer monsoon beginning in the late Miocene (~7–8 Ma) and global cooling due to the expansion of ice sheets from the middle Pliocene to the early Pleistocene. The new finding reveals a close relationship of the early Pliocene fauna of northern China and the latest Miocene fauna of southwestern China, and thus provides novel insight into the origin and components of Pliocene fauna in northern China. 相似文献
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胃癌是发病率及死亡率均较高的消化道恶性肿瘤之一,严重威胁人类的生命健康。血清肿瘤标志物的检测对提高早期胃癌的检出率,改善胃癌的治疗有重要的意义。核酸适配体以其灵敏度高、靶向性强等优势显示出了较强的临床适用性。本研究以双向热循环消减指数富集式配基系统进化(systematic evolution of ligands by exponential enrichment,SELEX)技术为支持,纳米(琼脂)磁珠材料为载体,胃癌血清及正常人血清为筛选靶标,结合高通量测序技术建立了快速高效的核酸适配体筛选方法。经过19轮双向筛选,获得高重复率的胃癌血清特异性核酸适配体序列10条及正常人血清特异性核酸适配体序列8条。将这些序列分别混合并制成检测试剂A、B,结合实时荧光定量PCR(quantitative real-time PCR,qPCR)技术,对100份临床血清样本进行特异性验证。通过比较分析,建立了快速高效的胃癌血清检测技术。结果显示,核酸适配体G AP1与N AP1的二级结构类似于抗体的“Y”型,且呈茎环状。检测试剂A、B对胃癌及正常人血清的检出率分别为92%和88%。表明本技术可以较准确地筛选得到高特异性和强亲和力的核酸适配体,体现了核酸适配体作为新型肿瘤标志物在临床检测及治疗的应用潜力。 相似文献
14.
Zhou SQ 《Hereditas》2003,138(1):65-72
The aneuploidy of Gossypium hirsutum L. (upland cotton) aneusomatics were obtained by induced parthenogenesis. These aneuploids could grow and set seeds normally. In the process of meiosis there appeared large quantities of heteromorphic pairs and multivalent chromosomes and many cases of cytomixis and multisperm fertilization occurred. The aneuploids produced offsprings through sexual propagation. We explored penetratingly the questions how and why these aneuploids could survive. Through this research, we found that the upland cotton possessed an immense latent capacity to adapt to adverse environments. More importantly, in the case of the upland cotton, we discovered that the genetic pattern of the polyploid differs in some respects from that of the diploid. 相似文献
15.
Joan H. Schiller Gerard Bittner Shi-Qi Wu Lorraine Meisner 《In vitro cellular & developmental biology. Animal》1998,34(4):283-289
Summary In this study, we describe the karyotypic changes associated with the spontaneous acquisition of tumorigenicity in an immortalized
tumor bronchial cell line. Neoplastic transformation of the NL20 human bronchial epithelial cell line occurred after 3 yr
in culture, and was associated with loss of chromosome 18 together with acquisition of multiple copies of 9q21.2→34. The nontumorigenic
NL20 cell line had been established by transfection of human bronchial epithelial cells with the SV40 T antigen, and had retained
a relatively stable karyotype after the first 32 passages in vitro. However, when cells from p184 were inoculated into nude mice, a transplantable tumor was obtained that was derived from
a minor clone present in this otherwise stable line. Subsequent passaging of the NL20 cells in vitro did not yield further tumors, and the minor clone from which the tumorigenic NL20T cell line derived was no longer evident
in NL20 cells by Passage 205. Furthermore, the original tumorigenic NL20T cells lost the neoplastic phenotype after 25 passages
in vitro and reverted to the nontumorigenic karyotype observed at p189. In contrast to the loss of the tumorigenic phenotype and karyotype,
which occurred with in vitro passaging of the original tumor, when the NL20T cells were passaged in other nude mice, they continued to give rise to tumors
with sevenfold amplifications of 9q sequences and loss of chromosome 18, and cells from the secondary tumors (NL20T-A cells)
have maintained a stable karyotype and remain tumorigenic even after 64 passages in vitro. A mixture of 10% tumorigenic NL20T-A and 90% nontumorigenic NL20 cells formed tumors in athymic nude mice when cultured
in vitro on fibronectin, but not on plastic; cytogenetic analysis demonstrated that the tumors and cell cultures were composed of
tumorigenic NL20T-A cells, whereas cytogenetic analysis of cells cultured on plastic were identical to the nontumorigenic
NL20 cells. These data support the hypothesis that neoplastic transformation in our original cell line arose from in vivo selection of a small mutant clone, which had arisen in culture and was subsequently selected in vivo but was lost with in vitro culture. 相似文献
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Wen-Jing Liu Gang Zhao Chen-Yan Zhang Chang-Qing Yang Xiang-Bin Zeng Jin Li Kun Zhu Shi-Qi Zhao Hui-Meng Lu Da-Chuan Yin Sheng-Xiang Lin 《Journal of cellular biochemistry》2020,121(4):2756-2769
Breast cancer (BC) and prostate cancer (PC) are the second most common malignant tumors in women and men in western countries, respectively. The risks of death are 14% for BC and 9% for PC. Abnormal estrogen and androgen levels are related to carcinogenesis of the breast and prostate. Estradiol stimulates cancer development in BC. The effect of estrogen on PC is concentration-dependent, and estrogen can regulate androgen production, further affecting PC. Estrogen can also increase the risk of androgen-induced PC. Androgen has dual effects on BC via different metabolic pathways, and the role of the androgen receptor (AR) in BC also depends on cell subtype and downstream target genes. Androgen and AR can stimulate both primary PC and castration-resistant PC. Understanding the mechanisms of the effects of estrogen and androgen on BC and PC may help us to improve curative BC and PC treatment strategies. 相似文献
19.
Di Wu Xian-Wei Wang Shi-Qi Xu Chong-Juan Chen Rong Mao Xue-Yan Liu 《Journal of Plant Ecology》2020,13(6):713
气候变暖和大气氮沉降增加会改变北方泥炭地的养分状态,从而影响其植被的物种组成和固碳功能。酚类物质是植物用于 防御植食性动物和适应环境的次生代谢产物,由于其具有抗分解的特性,在调节泥炭地碳动态方面也起着重要的作用。然而,北方 泥炭地不同功能型植物的酚含量及其如何随氮有效性变化尚不清楚。本论文通过测定中国东北大兴安岭地区18个泥炭地共11 种植物的叶片总酚含量(Total Phenols Contents, TPC),研究了它们随叶片氮、磷含量的变化关系,并探讨了其潜在机制。结果表明,灌木叶片TPC高于草本植物,说明生长较快且无菌根的草本植物比生长较慢且具有菌根的灌木对防御的碳投入较少。灌木叶片TPC随叶片氮含量增 加而降低,表明其防御碳投入随氮有效性增加而减少。相反,草本植物叶片TPC随氮含量增加而增加,随磷含量增加而减少,由于草本植物相对于灌木具有较强的氮限制和较弱的磷限制,草本植物防御碳投入可能随养分有效性增加而增加。我们的结果表明,泥炭地在氮有效性随气候变暖和氮沉降增加而增加的背景下,灌木将投入相对较多的碳用于生长而非防御,而草本植物则与之相反。这些发现将有助于对北方泥炭地灌木入侵及其资源竞争机制的理解。 相似文献