北京西山侏罗纪大同锥叶蕨的研究

大同锥叶蕨Coniopteris tatungensis 是侏罗纪植物群常见的分子。由于对该植物特征认识的不同, 对其在分类上的归属有不同意见,或归入膜蕨型锥叶蕨C．hymenophylloides,或归入简单锥叶蕨C. simplex。通过对产自北京西山斋堂地区窑坡组下段的标本的深入研究,特别是用扫描电子显微镜对该 标本的孢子囊群和孢子囊的观察,确认大同锥叶蕨在锥叶蕨属的种级分类上的独立性。文中还初步讨论了其分类和地理分布。     

脉冲电场对真皮成纤维细胞生长和膜流动性的影响

采用MTT比色分析法检测脉冲电场(f=50Hz,t=20μs,Epp=1V/m),对真皮成纤维细胞增殖的影响,结果表明,电场作用1分钟和5分钟,均产生促进细胞增殖的效果(P<0.05和P<0.001),而较长时间(t≥10分钟)的电场作用则显著抑制细胞的正常增殖(P<0.001)。 采用荧光偏振法研究了脉冲电场对真皮成纤维细胞膜流动性的影响。结果表明,电场作用5分钟后即刻引起膜流动性的显著增加。而电场作用45分钟后,需经过一段时间的温育(30 分钟),才表现出膜流动性的降低。说明不同作用时间的电场可以造成膜流动性的增加或降低,而且对膜流动性的影响是可逆的。我们认为,脉冲电场所引起的膜流动性改变是细胞分裂能力发生变化的原因之一。     

水稻OsMS2基因在花药发育中的功能分析

拟南芥MS2(MALE STERILITY 2)是一个调控花药花粉发育的关键基因。水稻OsMS2(Os03g07140)基因与拟南芥MS2的序列具有高度同源性。利用RNA干扰技术研究OsMS2基因在水稻花药发育过程中的功能。与野生型水稻相比, 转基因 植株营养生长阶段正常, 但雄性育性降低。转基因植株雄性育性降低与RNA干扰引起的OsMS2基因表达水平降低有关。进一步对转基因植株花药进行细胞学观察, 结果表明OsMS2基因表达水平的降低导致绒毡层细胞退化延迟, 小孢子壁的形成出现异常。扫描电镜观察结果显示, 小孢子壁光滑, 不能形成正常的外壁。以上结果表明OsMS2基因在水稻花药发育过程中起重要作用。     

广西陆栖兽类动物分布格局及区划探讨

根据广西陆栖兽类种类,数量和分布特点。结合自然地理条件,探讨了广西陆栖兽类支持发布格局,并将广西兽类地理区划为7个小区：Ⅰ桂西南缘山地小区;Ⅱ桂南沿海台地平原小区;Ⅲ桂西南丘陵盆地小区;Ⅳ桂中丘陵山地小区;Ⅴ桂中及桂东低丘台地,山地,谷地小区;Ⅵ桂西北岩溶山原盆坝小区;Ⅶ桂东北南岭山地小区。广西陆栖兽类区域分化不明显,而受地形因素的更显著,海拔较高的桂西,北边缘山地区系成分较为近似,而与东部和南部沿海低海拔的丘陵,低山及盆地形成较明显的差异。盆地内弧形山脉的动物区系别具特色。     

Autotoxic potential of cucurbit crops

Soil sickness is often observed in cucurbit crops such as Citrullus lanatus, Cucumis melo and Cucumis sativus, but not in cucurbit crops such as Cucurbita moschata, Lagenaria leucantha and Luffa cylindrica. Results showed that root aqueous extracts of Citrullus lanatus, Cucumis melo and Cucumis sativus were autotoxic, but those of Cucurbita moschata, Momordica charantia and Luffa cylindrica were less autotoxic to the radicle elongation of respective species. Plant growth of Citrullus lanatus, Cucumis melo and Cucumis sativus were greatly inhibited by autotoxic substances released from powered root tissue at a rate of 1 g per seedling. Root exudates of Citrullus lanatus, Cucumis melo and Cucumis sativus were autotoxic to radicle elongation and seedling growth of respective species. However, root exudates of Citrullus lanatus did not inhibit radicle elongation of Cucurbita ficifolia, which is commonly used as rootstock for the grafting of Citrullus lanatus, Cucumis melo and Cucumis sativus to decrease soil-borne diseases in commercial production. It seems possible to overcome autotoxicity in cucurbit crops by grafting on Cucurbita ficifolia. This revised version was published online in June 2006 with corrections to the Cover Date.     

Olfactory receptors on the maxillary palps of small ermine moth larvae: evolutionary history of benzaldehyde sensitivity

In lepidopterous larvae the maxillary palps contain a large portion of the sensory equipment of the insect. Yet, knowledge about the sensitivity of these cells is limited. In this paper a morphological, behavioral, and electrophysiological investigation of the maxillary palps of Yponomeuta cagnagellus (Lepidoptera: Yponomeutidae) is presented. In addition to thermoreceptors, CO₂ receptors, and gustatory receptors, evidence is reported for the existence of two groups of receptor cells sensitive to plant volatiles. Cells that are mainly sensitive to (E)-2-hexenal and hexanal or to (Z)-3-hexen-1-ol and 1-hexanol were found. Interestingly, a high sensitivity for benzaldehyde was also found. This compound is not known to be present in Euonymus europaeus, the host plant of the monophagous Yponomeuta cagnagellus, but it is a prominent compound in Rosaceae, the presumed hosts of the ancestors of Y. cagnagellus. To elucidate the evolutionary history of this sensitivity, and its possible role in host shifts, feeding responses of three Yponomeuta species to benzaldehyde were investigated. The results confirm the hypothesis that the sensitivity to benzaldehyde evolved during the ancestral shift from Celastraceae to Rosaceae and can be considered an evolutionary relict, retained in the recently backshifted Celastraceae-specialist Y. cagnagellus.     

基于响应面分析的高抗原活性猪水肿病大肠杆菌疫苗培养基的研制及效果评价

【背景】猪水肿病大肠杆菌引发的疾病造成了很大的危害,但现有培养基存在培养密度低的问题。【目的】研制出高抗原活性猪水肿病大肠杆菌疫苗培养基。【方法】以常用的市售猪水肿培养基为对照,通过单因素试验、爬坡试验(Plackett-Burman, PB)、响应面(Box-Behnken, BB)试验对猪水肿培养基进行响应面优化,得到猪水肿培养基最优配方。以响应面试验得到的培养基培养猪水肿病大肠杆菌,评价不同培养时间点菌株的抗原活性,制作灭活疫苗,进行动物免疫保护试验。【结果】对研制的培养基进行扩大培养验证,发现扩大培养得到的菌株活菌数可达5×10⁹ CFU/mL以上,约为对照组的2倍。制备的灭活疫苗效价可达1:140 000,并在9 h时抗原蛋白效价达到最高。【结论】本研究研制出的疫苗培养基显著提高了猪大肠杆菌菌体密度,并可提高菌体抗原活性,为猪水肿病灭活疫苗的制备提供了技术指引。     

Lenvatinib for effectively treating antiangiogenic drug-resistant nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) clinical trials show that antiangiogenic drugs (AADs) fail to achieve the expected efficacy, and combining AAD with chemoradiotherapy does not show superiority over chemoradiotherapy alone. Accumulating evidence suggests the intrinsic AAD resistance in NPC patients with poorly understood molecular mechanisms. Here, we describe NPC-specific FGF-2 expression-triggered, VEGF-independent angiogenesis as a mechanism of AAD resistance. Angiogenic factors screening between AAD-sensitive cancer type and AAD-resistant NPC showed high FGF-2 expression in NPC in both xenograft models and clinical samples. Mechanistically, the FGF-2-FGFR1-MYC axis drove endothelial cell survival and proliferation as an alternative to VEGF-VEGFR2-MYC signaling. Genetic knockdown of FGF-2 in NPC tumor cells reduced tumor angiogenesis, enhanced AAD sensitivity, and reduced pulmonary metastasis. Moreover, lenvatinib, an FDA recently approved multi-kinase inhibitor targeting both VEGFR2 and FGFR1, effectively inhibits the tumor vasculature, and exhibited robust anti-tumor effects in NPC-bearing nude mice and humanized mice compared with an agent equivalent to bevacizumab. These findings provide mechanistic insights on FGF-2 signaling in the modulation of VEGF pathway activation in the NPC microenvironment and propose an effective NPC-targeted therapy by using a clinically available drug.Subject terms: Tumour angiogenesis, Head and neck cancer, Targeted therapies     

High auxin stimulates callus through SDG8-mediated histone H3K36 methylation in Arabidopsis

Callus induction,which results in fate transition in plant cells,is considered as the first and key step for plant regeneration.This process can be stimulated in different tissues by a callus-inducing medium(CIM),which contains a high concentration of phytohormone auxin.Although a few key regulators for callus induction have been identified,the multiple aspects of the regulatory mechanism driven by high levels of auxin still need further investigation.Here,we find that high auxin induces callus ...     

Epidemic management and control through risk-dependent individual contact interventions

Testing, contact tracing, and isolation (TTI) is an epidemic management and control approach that is difficult to implement at scale because it relies on manual tracing of contacts. Exposure notification apps have been developed to digitally scale up TTI by harnessing contact data obtained from mobile devices; however, exposure notification apps provide users only with limited binary information when they have been directly exposed to a known infection source. Here we demonstrate a scalable improvement to TTI and exposure notification apps that uses data assimilation (DA) on a contact network. Network DA exploits diverse sources of health data together with the proximity data from mobile devices that exposure notification apps rely upon. It provides users with continuously assessed individual risks of exposure and infection, which can form the basis for targeting individual contact interventions. Simulations of the early COVID-19 epidemic in New York City are used to establish proof-of-concept. In the simulations, network DA identifies up to a factor 2 more infections than contact tracing when both harness the same contact data and diagnostic test data. This remains true even when only a relatively small fraction of the population uses network DA. When a sufficiently large fraction of the population (≳ 75%) uses network DA and complies with individual contact interventions, targeting contact interventions with network DA reduces deaths by up to a factor 4 relative to TTI. Network DA can be implemented by expanding the computational backend of existing exposure notification apps, thus greatly enhancing their capabilities. Implemented at scale, it has the potential to precisely and effectively control future epidemics while minimizing economic disruption.