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141.
为了解珍稀濒危植物细果秤锤树(Sinojackia microcarpa)开花特征和有性繁殖,对其花部形态特征、开花动态、花粉胚珠比(P/O)、柱头可授性、花粉活力、套袋试验、访花昆虫及访花频率进行观测。结果表明:(1)细果秤锤树的杂交指数(OCI)为4,单花期5~7 d,种群花期可持续20 d左右。花粉与胚珠比为4 093.21±498.56。开花后第3天的花粉活力最高(76.21%),而开花后第7天时花粉活力较低(18.37%)。细果秤锤树柱头最适可授期在开花后第2天。(2)套袋试验表明,细果秤锤树存在部分自交不亲和性,同时不存在无融合生殖,传粉昆虫是其完成生殖过程所必需的,且异株授粉能够提高其坐果率和结籽率。细果秤锤树的访花昆虫有3目5科7种,主要访花昆虫有黄胸木蜂(Xylocopa appendiculata)、熊蜂(Bombus sp.)、胡蜂(Vespa sp.)、中华蜜蜂(Apis cerana)、黑带食蚜蝇(Episyrphus balteatus)、其中熊蜂平均访花频率最高,达(8.67±0.21) 次·h-1。对该物种开花生物学特征与繁育系统进行深入研究,有利于进一步探究其濒危机制,为后续珍稀濒危植物的研究提供理论依据和参考。 相似文献
142.
Xinyue Ye Jian Wang Pengfei Xu Xiaoqian Yang Qixue Shi Genyan Liu Zhaoshi Bai Changlin Zhou Lingman Ma 《Microbial biotechnology》2023,16(9):1755-1773
Polymyxin resistance is conferred by MCR-1 (mobile colistin resistance 1)-induced lipopolysaccharide (LPS) modification of G− bacteria. However, the peptide MSI-1 exerts potent antimicrobial activity against mcr-1-carrying bacteria. To further investigate the potential role of MCR-1 in improving bacterial virulence and facilitating immune evasion, and the immunomodulatory effect of peptide MSI-1, we first explored outer membrane vesicle (OMV) alterations of mcr-1-carrying bacteria in the presence and absence of sub-MIC MSI-1, and host immune activation during bacterial infection and OMV stimulation. Our results demonstrated that LPS remodelling induced by MCR-1 negatively affected OMV formation and protein cargo by E. coli. In addition, MCR-1 diminished LPS-stimulated pyroptosis but facilitated mitochondrial dysfunction, further aggravating apoptosis in macrophages induced by OMVs of E. coli. Similarly, TLR4-mediated NF-κB activation was markedly alleviated once LPS was modified by MCR-1. However, peptide MSI-1 at the sub-MIC level inhibited the expression of MCR-1, further partly rescuing OMV alteration and attenuation of immune responses in the presence of MCR-1 during both infection and OMV stimulation, which can be exploited for anti-infective therapy. 相似文献
143.
Jing‐Fang Guo Baosheng Wang Zhan‐Lin Liu Jian‐Feng Mao Xiao‐Ru Wang Wei Zhao 《植物分类学报:英文版》2023,61(1):143-156
Endemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping-by-sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global FST 0.234) even at regional scales, reflecting long-term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction. 相似文献
144.
145.
Frankia菌种保藏 总被引:5,自引:0,他引:5
对用4种方法保藏的Frankia菌,进行了培养物存活、形态及其固氮活性的检测.发现在无氮液体培养基中保藏6年的Frankia.菌丝断裂,孢囊不完整.同期经有氮液体保藏的Frankia菌孢囊较完整.冷冻干燥保藏3.5年和砂管保藏8年,孢囊和菌丝均较完整.上述方法保藏的菌种,经活化后均能生长,且具有典型的Frankia菌形态特征和固氮活性.4种方法比较,无氮液体保藏法的菌体细胞生长速度快,固氮活性强,有侵染结瘤能力. 相似文献
146.
The anatomy of the arthropod Squamacula clypeata Hou and Bergström, 1997 from the Lower Cambrian Chengjiang Lagersta¨tte is redescribed based on four newly excavated specimens. The new material was collected from localities recently discovered in the Kunming area, Yunnan Province, south-west China, and preserves remarkable details of the ventral morphology, revealed by preparation. Squamacula clypeata is dorsoventrally flattened and rounded in outline. The cephalon was covered by a wide, short shield, with a large doublure and a pair of uniramous antennae on the ventral side. The thorax consists of nine somites, each protected by a tergite and carrying at least one pair of biramous limbs. The pygidium is covered with a small rounded tergum. The endopod is segmented, equipped with short spines on the inner margin of the coxa and a claw-like structure distally, and the exopod flap-like, fringed with setae. The limbs in the pygidium are like those in the thorax in shape. Squamacula was most probably a nektobenthic predator. The spinose endopod could walk, grasp and grind. The large flap-like exopod was adapted for swimming and respiration. Its affinities lie with the Arachnomorpha, but the relationships with other known taxa remain ambiguous. 相似文献
147.
海甘蓝种子在成熟过程中,棕榈酸、硬脂酸和亚麻酸的含量不断下降,而二十碳烯酸和芥酸的含量呈上升趋势。选用开花后25~27d的海甘蓝幼胚分别在含不同浓度的ABA或高渗透剂的培养基中培养1~3d,发现其各种脂肪酸的变化趋势和种子自然成熟过程中脂肪酸的变化相似,说明ABA或高渗透剂可能是种子成熟过程中各种脂肪酸合成和相互转化所需的条件。 相似文献
148.
木文用31P核磁共振(NME)观察了人淋巴瘤白血病细胞系Molt-4和人早幼粒白血病细胞系HL-60的细胞代谢。Molt-4和HL-60细胞系的31P谱主要由磷酸单酯、无机磷(Pi)、双磷酸双酯、ATP的共振峰组成。31P谱显示Molt-4细胞在受肿瘤坏死因子α(TNF-α)作用后,ATP/Pi比值降低。HL-60细胞在受TNF-α作用后,ATP减少。31P-NMR提供了一种非损伤性研究细胞代谢的重要方法。 相似文献
149.
150.
利用改进的kar交配法,将一个含有340kb人基因组DNA的YAC片段的供体酵母菌株YAC23与受体菌株YLB504进行交配,以选择平板对所形成的候选YAC导入菌进行筛选。经PCR分析,候选YAC导入菌在404bp处有一个扩增带,即具有受体菌株的交配型(MAT α)。进一步用脉冲电泳进行核型鉴定,证实YACs己成功地进入受体,实现了YACs从一个宿主到另一个宿主之间的转移。 相似文献