Factors involved in the degradation of mangrove forests in Iran: A mixed study for the management of this ecosystem

In Iran, mangroves are located in the south of the country, where they fulfill essential ecosystem functions, but some parts of them have been destroyed for various reasons in recent years so that it seems necessary to have a management plan consistent with the conservation of this ecosystem. But, it needs knowledge of the trend of and reasons for the degradation of these forests. So, the primary idea of this research was to discover the factors involved in the degradation of these forests and how to manage them. So, the research first used the remote sensing technique to determine the rate of their degradation over the last 20 years. Then, using the Delphi technique, 45 factors were identified for the degradation of these forests and they were classified into five categories including climatic and environmental, anthropogenic, socioeconomic, psychological, and policymaking and legal. Finally, the analytic hierarchy process (AHP) was used to rank these factors within two management paradigms of remediability and preventability so that the ecosystem can be soundly managed by classifying these factors. Overall, the results can provide policymakers with new insights into forest management and the policies presented here can contribute to the sustainability of this ecosystem.     

Improvement of glycine biosynthesis from one-carbon compounds and ammonia catalyzed by the glycine cleavage system in vitro

Glycine cleavage system (GCS) plays a central role in one-carbon (C1) metabolism and receives increasing interest as a core part of the recently proposed reductive glycine pathway (rGlyP) for assimilation of CO₂ and formate. Despite decades of research, GCS has not yet been well understood and kinetic data are barely available. This is to a large degree because of the complexity of GCS, which is composed of four proteins (H, T, P, and L) and catalyzes reactions involving different substrates and cofactors. In vitro kinetics of reconstructed microbial multi-enzyme glycine cleavage/synthase system is desired to better implement rGlyP in microorganisms like Escherichia coli for the use of C1 resources. Here, we examined in vitro several factors that may affect the rate of glycine synthesis via the reverse GCS reaction. We found that the ratio of GCS component proteins has a direct influence on the rate of glycine synthesis, namely higher ratios of P protein and especially H protein to T and L proteins are favorable, and the carboxylation reaction catalyzed by P protein is a key step determining the glycine synthesis rate, whereas increasing the ratio of L protein to other GCS proteins does not have significant effect and the ratio of T protein to other GCS proteins should be kept low. The effect of substrate concentrations on glycine synthesis is quite complex, showing interdependence with the ratios of GCS component proteins. Furthermore, adding the reducing agent dithiothreitol to the reaction mixture not only results in great tolerance to high concentration of formaldehyde, but also increases the rate of glycine synthesis, probably due to its functions in activating P protein and taking up the role of L protein in the non-enzymatic reduction of H_ox to H_red. Moreover, the presence of some monovalent and divalent metal ions can have either positive or negative effect on the rate of glycine synthesis, depending on their type and their concentration.     

钼靶和超声检查在乳腺癌临床诊断的准确性的比较分析

摘要 目的：比较与分析钼靶和超声检查在乳腺癌临床诊断的准确性。方法：2018年8月到2021年1月选择在本院进行诊治的乳腺肿瘤患者110例作为研究对象,所有患者都给予钼靶和超声检查,记录影像学特征并判断诊断价值。结果：在110例患者中,病理诊断为乳腺良性肿瘤76例、乳腺癌34例。恶性组钼靶的分叶征、钙化、大角征、毛刺征等比例高于良性组,病灶大小也高于良性组(P<0.05)。恶性组超声的形态不规则、边缘不光整、高回声晕、回声衰减、微钙化等比例高于良性组(P<0.05)。钼靶乳腺影像报告及数据系统(Breast imaging report and data system,BI-RADS)判断为乳腺良性肿瘤72例,乳腺癌38例;超声BI-RADS判断为乳腺良性肿瘤75例,乳腺癌35例,钼靶鉴别诊断乳腺癌的敏感性为93.4%,特异性为97.1%,准确性为94.5%;超声鉴别诊断乳腺癌的敏感性为98.7%,特异性为100.0%,准确性为99.1%。多因素logistic回归分析显示病灶大小、分叶征、回声衰减、毛刺征为导致误诊的重要因素(P<0.05)。结论：乳腺癌在钼靶和超声检查中都有明显的征象特征,超声诊断的准确性更高,病灶大小、分叶征、回声衰减、毛刺征为影响诊断效果的很重要因素。     

研究报告：缓激肽上调豚鼠肠道黏膜下神经丛环氧合酶2的表达

目的缓激肽和缓激肽B2受体在肠神经系统中起重要作用。缓激肽通常参与肠道的炎症反应和神经保护,这种作用取决于缓激肽诱导前列腺素的形成。环氧合酶1 (COX1)和环氧合酶2 (COX2)催化花生四烯酸转化为前列腺素。本研究旨在探讨缓激肽刺激对豚鼠肠神经前列腺素E2 (p GE2)释放和COX2表达的影响及信号机制。方法本文通过免疫荧光检测肠神经细胞中COX2与神经细胞标志物Anti-Hu和ch AT的表达;采用PCR及蛋白质印迹(Western blot)检测不同条件下缓激肽刺激对COX2表达的影响;使用缓激肽B1受体的选择性拮抗剂Leu-8和B2受体的选择性拮抗剂HOE-140,研究缓激肽影响COX2表达的信号机制;利用COX2选择性拮抗剂NS398和COX1拮抗剂FR12207,观察COX2在缓激肽诱导p EG2释放的作用。结果 COX2与神经细胞标志物Anti-Hu和ch AT在肠神经细胞上共同表达,缓激肽可通过B2受体诱导肠神经细胞COX2的表达。缓激肽刺激引起的肠神经细胞p GE2的释放与COX2表达升高密切相关。结论缓激肽通过B2R影响肠道黏膜下神经丛COX2的表达,肠道缓激肽...     

西双版纳热带季雨林通量分配及能量平衡问题北大核心CSCD

为了探讨我国西双版纳热带季雨林的能量分配和平衡问题,利用涡度相关系统和常规气象仪器的连续监测结果,分析了不同季节的能量通量特征和闭合特点。结果表明,西双版纳热带季雨林全年的净辐射、潜热通量、显热通量、土壤热通量和热储存量分别是4546.07、2453.24、492.22、-10.47和45.93 MJ/m^(2),土壤为热源,潜热年总值占净辐射的54.0%,显热占10.8%,能量以蒸发散为主要的耗损形式。辐射和能量有明显的日变化和季节动态,各能量分量的日变化几乎都呈白天高夜间低的单峰趋势,反照率整体为0.10~0.12,波动不大;波文比季节差异明显,为0~0.8。热带季雨林的全年闭合度为0.67,未考虑热储量时,闭合度为0.51~0.79,考虑热储量为0.53~0.80。可见,在林冠茂密的热带季雨林中,热储量对能量闭合度的贡献不大,忽略热储量并不是导致能量不闭合的主要原因。     

华南国家植物园发展历史与未来展望

该文系统回顾了华南国家植物园近百年来几个关键时期的历史发展、主要成就和社会贡献,从国家、中国科学院、地方政府三个层面分析了华南国家植物园率先设立的缘由,展望了华南国家植物园的未来发展前景,提出了我国国家植物园体系建设的思考和建议。     

商代前期中原地区多品种农作物种植制度的初探：以河南新郑望京楼遗址为例

农业经济的发展是华夏文明形成的最重要的前提条件之一,郑洛地区作为夏商王朝建都和统治的核心区域,其农业经济发展状况一直是学术界研究的重点问题。相关研究表明,多品种农作物种植制度在龙山时期中原地区的出现,在华夏文明的形成过程中可能起到了至关重要的作用。为了探索这一种植制度在商代前期中原地区的具体实践情况,本文选取河南新郑望京楼遗址夏商时期（二里头文化和二里岗文化时期）29例先民肢骨和23例先民肋骨进行C、N稳定同位素分析。结果表明,先民骨胶原的δ¹³C值变化范围为-18.1‰~7.0‰,平均值为-9.5‰±2.1‰（n=52）,δ¹⁵N值变化范围为7.3‰~10.5‰,平均值为8.9‰±0.7‰（n=52）,先民仍以C₄类食物（粟黍）为主,但是也包含少量C₃类（水稻、小麦或大豆）食物,证明中原地区自龙山时代出现的多品种农作物种植制度,在商代得以延续,但是粟作农业的主导地位,始终未发生明显变化,这可能与中原地区长期以来的旱作农业经济模式习惯有关。     

神经前体细胞表达发育性下调蛋白4在消化系统肿瘤发生中的作用

神经前体细胞表达发育性下调蛋白4(neural precursor cell expressed,developmentally down-regulated protein 4,NEDD4-1,部分文章也称NEDD4)是近年来才备受关注的肿瘤相关基因,属于E3 HECT(homologous to E6 associated protein C terminus,E6蛋白c端同源基因)泛素连接酶NEDD4样家族成员。泛素连接酶,能够参与多种蛋白质的泛素化、溶酶体及蛋白酶体的降解、胞核-胞质转位等,间接影响不同恶性肿瘤的多种信号通路。随着大量NEDD4-1与肿瘤相关实验的不断深入,目前已发现其可通过调控细胞周期、癌细胞侵袭转移、拮抗耐药性等许多途径影响肿瘤的生物学行为。在消化系统肿瘤中,NEDD4-1主要通过PTEN/PI3K/AKT、TGF-β、Hippo、LDLRAD4等多条通路促进肝细胞癌的增殖、侵袭和迁移能力;在胰腺癌中发现,NEDD4-1在PI3K/AKT信号通路中发挥癌基因作用,但在与Myc-SIRT2所形成的信号环路中,却发挥抑癌基因的作用;在胃癌和结直肠癌中,NEDD4-1所参与的信号通路与其他消化系统肿瘤均不相同,NEDD4-1能独立于PTEN/PI3K/AKT通路而发挥促进胃癌恶化、转移(EGFR信号通路)和抑制结直肠癌肿瘤生长(WNT信号通路)的作用。NEDD4-1已经成为人们治愈肿瘤的热门研究方向。本文通过系统总结NEDD4-1在不同消化系统肿瘤中的功能、信号通路和潜在抑制剂等,进行探讨NEDD4-1与不同信号通路的关系,旨为临床在癌症治疗领域提供重要的参考数据。     

福建省多花黄精生态适宜性区划研究

通过研究多花黄精(Polygonatum cyrtonema)的生态适宜性,为其野生资源保护及人工规范化栽培提供依据。收集237份多花黄精分布位置和55个生态因子,导入最大熵(MaxEnt)模型运算,结合地理信息系统(GIS)分析其适合生长区域。结果表明,影响多花黄精生态适宜性的主要生态因子是3月降水量、年均降水量、6月降水量、5月降水量、4月降水量、2月降水量和最冷季降水量,在福建省具有广泛适宜生长区域。模型预测结果可靠,可为多花黄精野生资源保护提供参考,并为其科学种植提供指导。     

G6P-capturing molecules in the periplasm of Escherichia coli accelerate the shikimate pathway

Escherichia coli, the most studied prokaryote, is an excellent host for producing valuable chemicals from renewable resources as it is easy to manipulate genetically. Since the periplasmic environment can be easily controlled externally, elucidating how the localization of specific proteins or small molecules in the periplasm affects metabolism may lead to bioproduction development using E. coli. We investigated metabolic changes and its mechanisms occurring when specific proteins are localized to the E. coli periplasm. We found that the periplasmic localization of β-glucosidase promoted the shikimate pathway involved in the synthesis of aromatic chemicals. The periplasmic localization of other proteins with an affinity for glucose-6-phosphate (G6P), such as inactivated mutants of Pgi, Zwf, and PhoA, similarly accelerated the shikimate pathway. Our results indicate that G6P is transported from the cytoplasm to the periplasm by the glucose transporter protein EIICB^Glc, and then captured by β-glucosidase.