天童常绿阔叶林演替系列植物群落的N∶P化学计量特征

 土壤氮磷养分对植物生长的限制性可通过植被的N∶P化学计量特征来反映。该研究以常绿阔叶林演替系列为对象,将N∶P作为诊断指标,揭示 常绿阔叶林次生演替过程中植物群落的N∶P化学计量特征和养分限制作用。结果显示：1)物种水平的N∶P大小不一,但演替系列总体的变化特 征表现出了较高的一致性。2）在群落水平上,次生演替初期的灌草丛N∶P极小(7.38),远远低于14,当演替进入灌丛阶段,N∶P 显著增高到 19.96,在进入演替中期的针叶林(14.29)和针阔混交林(14.21)时,N∶P显著下降到 14～16之间,演替中后期的木荷(Schima superba)群落 (18.77)和栲树(Castanopsis fargesii)群落(20.13)的N∶P发生了显著的升高过程 。根据以往对N∶P临界值的确定,可以认为,常绿阔叶林次 生演替初期的植物群落生产力主要受到氮素的限制作用;演替中期的针叶林和针阔混交林主要受氮磷的共同限制,但以氮素的限制作用更为强 烈;演替中后期植物群落主要受到土壤磷素的限制作用。     

天童常绿阔叶林演替系列植物群落的N：P化学计量特征

土壤氮磷养分对植物生长的限制性可通过植被的N：P化学计量特征来反映。该研究以常绿阔叶林演替系列为对象,将N：P作为诊断指标,揭示常绿阔叶林次生演替过程中植物群落的N：P化学计量特征和养分限制作用。结果显示：1）物种水平的N：P大小不一,但演替系列总体的变化特征表现出了较高的一致性。2）在群落水平上,次生演替初期的灌草丛N：P极小（7．38）,远远低于14,当演替进入灌丛阶段,N：P显著增高到19．96,在进入演替中期的针叶林（14．29）和针阔混交林（14．21）时,N：P显著下降到14～16之间,演替中后期的木荷（Schima superba）群落（18．77）和栲树（Castanopsis fargesii）群落（20．13）的N：P发生了显著的升高过程。根据以往对N：P临界值的确定,可以认为,常绿阔叶林次生演替初期的植物群落生产力主要受到氮素的限制作用;演替中期的针叶林和针阔混交林主要受氮磷的共同限制,但以氮素的限制作用更为强烈;演替中后期植物群落主要受到土壤磷素的限制作用。     

海岛森林不同演替阶段土壤和植物的碳、氮、磷化学计量特征

该研究采用空间代替时间的方法,对福建省东部海域的平潭岛林区不同演替阶段群落(灌草丛、针叶林、针阔混交林、常绿阔叶林)的土壤和植物的C、N、P含量进行测定,分析不同演替阶段土壤和植物的C、N、P及生态化学计量特征的变化规律,并探讨植物与土壤养分之间的相互关系。结果表明:(1)由于土壤C、N、P的来源不同,导致土壤有机碳(SOC)和全氮(STN)含量随着演替进行逐渐增加,土壤全磷(STP)含量呈先下降后上升的趋势;土壤C∶N随演替进行呈增加趋势,土壤C∶P和N∶P呈先升高后下降的趋势。(2)植物叶片碳(LC)含量随着演替进行呈先升高后下降的趋势,叶片氮(LN)和磷(LP)含量呈先下降后升高的趋势,反映了各演替阶段植物采取不同的生态适应性;植物叶片C∶N和C∶P随演替进行呈先升高后下降的趋势,植物叶片N∶P呈逐渐增加的趋势。(3)相关分析表明,土壤SOC与STN呈显著正相关关系,表明土壤C、N元素有较强的耦合关系;植物LN与LP呈显著正相关关系,共同反映植物的光合作用;植物叶片LP与土壤STP呈显著正相关关系,且植物叶片N∶P在各演替阶段均大于16,说明平潭岛植物生长主要受到土壤P限制。     

哈巴湖国家级自然保护区油蒿群落生态化学计量特征对群落生物量和物种多样性的影响

以宁夏哈巴湖国家级自然保护区内的油蒿群落为研究对象,测定了油蒿群落不同发育阶段植物叶C、N、P含量,分析了植物叶C∶N∶P比化学计量特征,探讨了油蒿群落生态化学计量特征对物种多样性和生物量的影响。结果表明,在哈巴湖国家级自然保护区,油蒿群落发育早期,植物生长受N限制,发育中后期,植物生长受P限制;油蒿群落发育早期阶段的植物具有较高的叶C∶N比和较低的叶N∶P比,而油蒿群落发育后期阶段的植物具有较低的叶C∶N比和较高的叶N∶P比。随着叶C∶N比的增大,油蒿群落生物量呈指数函数显著降低,物种多样性呈对数函数降低的趋势,但不显著;而随着叶N∶P比的增大,油蒿群落生物量和物种多样性均呈幂函数显著增加,表明生态化学计量特征对油蒿群落的物种多样性和生物量有重要影响。     

湘西南石漠化地区灌丛植物叶N、P化学计量特征

以湘西南石漠化地区灌丛植物叶片为研究对象,分析了不同功能群植物以及3种不同石漠化程度(轻度、中度、重度)下植物叶片N、P化学计量特征.结果表明: 湘西南石漠化地区常见植物叶片平均N含量为12.89 g·kg^-1,P含量为1.19 g·kg^-1,N/P值为11.24,大部分植物生长受到N的限制.不同生活型之间植物叶片N含量为落叶灌木>常绿灌木>一年生草本>多年生草本,P含量与N/P值为落叶灌木>多年生草本.不同科植物之间叶片N、P含量和N/P值差异显著,禾本科植物叶片N、P含量最低,与其他科植物共同受N限制;豆科植物叶片N含量和N/P值最高,主要受P限制.双子叶植物与C3植物叶片N、P含量分别高于单子叶植物与C4植物,N/P值差异均不显著.固氮植物叶片N含量以及N/P值均高于非固氮植物,P含量差异不显著.各样地中植物叶片N、P含量之间的相关性显著,N/P值与N含量的相关性显著,仅与中度石漠化样地P含量差异显著.不同石漠化程度之间植物叶N、P含量以及N/P值差异不显著.     

武夷山不同海拔黄山松新叶和老叶氮磷化学计量特征

土壤是植物养分的直接来源,植物叶片的养分特征在一定程度上能反映土壤养分状况。叶片氮磷比(N∶P)被广泛用于指示土壤养分有效性和养分限制性,选择对土壤养分最敏感的叶片来指示土壤养分状况具有重要意义。为比较黄山松新叶和老叶指示土壤养分状况的准确性,在福建武夷山选择了3个海拔(1100、1500和1900 m)的黄山松新叶和老叶作为研究对象,通过测定土壤碳(C)、氮(N)、磷(P)含量,黄山松叶片N、P含量及土壤和叶片15N丰度值,并计算土壤和叶片的化学计量比,从而揭示黄山松新叶和老叶对不同海拔土壤养分状况的敏感性。结果表明:(1)不同海拔土壤氮有效性无显著差异,而土壤和叶片15N丰度值随海拔呈递增趋势,说明土壤氮素对植物的有效性随海拔升高而增加;低海拔(1100 m)土壤总P和有效P含量低于高海拔(1500和1900 m)处,且低海拔叶片P含量也显著低于高海拔;(2)黄山松新叶N、P和N∶P随海拔升高均无显著变化,且新叶N∶P与土壤养分相关性不大;老叶N、P含量与土壤养分相关性较密切,表明黄山松老叶较新叶对不同海拔土壤养分状况响应更敏感,更能指示土壤养分状况。因此,这些研究结果明晰了不同海拔植物新叶和老叶对土壤养分状况的敏感性差异,对于我们进一步了解未来气候变化背景下不同海拔植物生长对土壤养分状况变化的响应具有重要意义。     

黄土高原子午岭林区两种天然次生林植物叶片-凋落叶-土壤生态化学计量特征

了解我国黄土高原子午岭林区两种天然林下植物叶片-凋落叶-土壤生态化学计量特征,有助于人们更深入地认识黄土高原子午岭天然次生林生态系统养分循环规律和系统稳定机制。结果表明:(1)辽东栎和白桦两种植物叶片碳、氮、磷平均含量为468.6、17.1、2.1 g/kg;凋落叶碳、氮、磷平均含量为457.3、12.5、1.6 g/kg;土壤碳、氮、磷平均含量分别为17.6、1.4、0.5 g/kg。(2)白桦叶片N、P含量之间II类线性回归斜率大于1(P=0.07),表明白桦叶片建成过程中存在N、P元素按比例投入的依赖。白桦凋落叶N、P含量之间的II类线性回归斜率显著小于1(P0.05),两种天然次生林凋落叶整体N、P含量之间的II类线性回归斜率也显著小于1(P0.05),反映了凋落叶中单位P含量与单位N含量间不存在等速损耗关系。(3)黄土高原子午岭两种天然次生林凋落叶氮含量与土壤氮含量具有显著相关性(P0.01),表明凋落叶分解对土壤氮库有增加作用。相比于凋落叶,植物叶片磷含量与土壤磷含量具有较紧密的关系,表现为高的土壤P含量则植物叶片也具有较高的P含量。黄土高原子午岭林区两种天然次生林下土壤有机质具有较快的矿化作用。(4)辽东栎作为植被演替到顶极群落的优势物种,其凋落叶C∶N值为26.7远低于白桦凋落叶C∶N值44.9(P0.05),有利于微生物对凋落叶的分解。两种天然次生林的植物叶片N∶P均值为7.9714,低于全国和全球尺度的其他研究结果,表明这两种天然次生林主要受N限制。     

阔叶红松林不同演替阶段灌木器官的N、P分配特征

氮（N）、磷（P）是植物生长发育重要的限制元素,N、P以及N、P间的关系是化学计量学研究的重要内容。植物不同器官对N、P的需求存在差异,因此N、P的分配与权衡对植物的生长发育起到重要的调节作用。为了探究阔叶红松（Pinus koraiensis）林不同演替阶段主要灌木器官的N、P化学计量特征及其分配格局,了解灌木的养分限制因子及其分配策略,在黑龙江凉水国家级自然保护区的阔叶红松林四个演替阶段——白桦（Betula platyphylla）次生林、阔叶混交林、针阔混交林和阔叶红松林内,选取主要灌木种,分析了叶片、枝条、茎干和根的N、P化学计量特征以及异速生长关系。结果发现：灌木不同器官之间的N、P含量差异显著,其中叶的N、P含量均为最高,茎干的N、P含量均为最低。所有器官中,叶的N ： P最高,为7.59;根的N ： P最低,为5.47。灌木叶、茎干、根之间的N ： P存在显著差异,而茎干、根与枝条之间的N ： P没有显著差异。阔叶红松林不同演替阶段对灌木同一器官N、P化学计量的影响不同,灌木叶片的N含量在不同演替中具有显著差异,其他器官的差异不显著;不同演替阶段灌木器官的P含量均无显著差异。在不同演替阶段中各器官的N ： P均小于14,说明N元素是阔叶红松林各演替阶段灌木生长的限制因子,而P对灌木的生长没有起到限制作用。研究表明在不同演替阶段中,N、P的异速生长关系普遍存在于灌木器官中,呈现显著的正相关关系;整体上各器官之间的斜率没有显著差异,说明灌木采取保守分配策略,以此来适应环境和满足自身生长发育的需要。     

黄河三角洲贝壳堤湿地优势灌木碳、氮、磷化学计量特征

为探讨黄河三角洲海岸带湿地不同水盐条件下植物叶片化学计量特征的季节动态及植物生长的限制性营养元素,以滨州贝壳堤岛与湿地国家级自然保护区内的柽柳、杠柳、酸枣3种优势灌木为研究对象,于2017-2018年的生长季（5-10月）每月定期采集叶片样品,测定叶片C、N、P含量。结果表明,生长季内3种灌木叶片C含量呈逐渐上升趋势;叶片N、P含量呈先下降后上升趋势,说明3种灌木采用防御性生活史策略适应盐生和干旱生境。3种灌木叶片C平均含量分别为（399.65±2.66）mg/g、（424.32±1.59）mg/g、（437.47±1.08）mg/g,低于全国（455.1 mg/g）及全球（461.6 mg/g）水平,呈现盐生生境下较低的植物碳储存能力。3种灌木叶片N和P平均含量分别为（30.14±0.26）mg/g和（1.81±0.03）mg/g、（23.18±0.38）mg/g和（2.06±0.04）mg/g、（27.36±0.49）mg/g和（2.01±0.03）mg/g,显著高于全国（N∶20.2 mg/g,P：1.46 mg/g）及全球（N∶19.3-20.1 mg/g,P：1.11-1.42 mg/g）水平。叶片C∶N∶P比呈先上升后下降的趋势,叶片P含量对C∶N∶P比变化具有主导作用。3种灌木叶片C∶N∶P质量比分别为246∶17∶1、224∶12∶1、237∶14∶1,说明柽柳的水盐胁迫适应能力高于杠柳和酸枣。从叶片N、P化学计量特征看,生长季内,柽柳生长一定程度上受土壤P限制,杠柳生长受到土壤N限制,酸枣生长则受土壤N、P共同限制,说明3种灌木的生物地球化学生态位发生了分化,避免了对同种资源的竞争,利于物种共生。     

辽东山区不同森林类型生态化学计量特征

森林生态系统化学计量对于阐明养分元素在生态系统中的供应状况及其耦合关系,揭示影响森林结构与功能恢复的限制性因子具有重要作用。本研究以辽东山区主要森林类型——次生阔叶混交林、柞树林、油松林和落叶松人工林、红松人工林为研究对象,通过测定叶片、凋落物和土壤的C、N、P含量,分析了不同林型的化学计量特征及差异。结果表明:1)不同林型的C、N、P含量差异显著,且各林型叶片和凋落物C、N、P含量均大于土壤;其中阔叶混交林土壤N含量最高,而柞树林土壤N含量最低。2)5种林型C∶N和C∶P变化趋势均为凋落物叶片土壤,N∶P为叶片凋落物土壤;其中叶片N∶P平均值为12.16,表明该地区植物生长可能存在N限制。阔叶混交林和柞树林与油松林、落叶松林和红松林N∶P差异显著,前者受N、P共同限制,后者受N限制。3)辽东山区森林植被叶片与凋落物的N、P、C∶N和N∶P均表现为正相关关系,土壤与叶片和凋落物N、C∶N均呈负相关关系。本研究表明,理解养分元素在"植物-凋落物-土壤"之间的生态化学计量特征,对于揭示整个森林生态系统的养分状况和生物化学循环过程极为重要。     

Correlations of calcium accumulations in arteries, veins, cartilages, ligaments, and bones in single humans

To show the relationships of calcium accumulation in the thoracic aorta to the other tissues, calcium contents were determined with a microwave-induced plasma-atomic emission spectrometer on arteries, veins, cartilages, ligaments, and bones. These tissues were resected from 18 individuals, consisting of 11 men and 7 women who died in the age range 59–91 yr. As thoracic and abdominal aortas are routinely used for radiographic examination of arterial calcification, they appear to be standard tissues of the calcium accumulation. The calcium accumulations were determined in the femoral artery, the superior and inferior venae cavae, the internal jugular vein, cartilages of the articular disk of the temporomandibular joint and the intervertebral disk, both the ligaments of the anterior cruciate ligament and the ligamentum capitis femoris, and the calcaneus, in contrast with the thoracic aorta. As calcium increased in the thoracic aorta, it increased in the femoral artery, the articular disk of the temporomandibular joint, the intervertebral disk, both ligaments of the anterior cruciate ligament, and the ligamentum capitis femoris, but it did not increase in veins, such as the superior and inferior venae cavae and the internal jugular vein. In contrast, it decreased in the calcaneus.     

Seroepidemiology of human parechovirus types 1, 3, and 6 in Yamagata,Japan, in 2014

To clarify the seroepidemiology of human parechovirus type 1 (HPeV1), 3 and 6, neutralizing antibodies (NT Abs) were measured in 214 serum specimens collected in 2014 in Yamagata, Japan. The seroprevalence against HPeV1 was 100% in all age groups, while that against HPeV3 and HPeV6 was 79.4% and 66.8%, respectively, overall. The geometric mean titers of NT Abs against HPeV1, 3 and 6 were 755.2, 255.0 and 55.9, respectively, overall. Our findings indicate that HPeV1 is the most prevalent HPeV circulating in Yamagata, followed by HPeV3 and HPeV6.     

Distribution of N,P, K,Ca, Mg,S, Zn,Fe, Mn and Cu in groundnut

Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.     

Changes in iron, calcium, magnesium, copper, and zinc levels in different tissues of riboflavin-deficient rats

To clarify the changes of mineral levels in different tissues of riboflavin-deficient rats, Wistar rats were separated into three groups. One group was fed a diet ad libitum that was deficient in riboflavin. The other two were fed either the complete diet that was weight-matched to the riboflavin-deficient group or fed a complete diet ad libitum. In riboflavin-deficient rats, the hemoglobin concentration and riboflavin contents of blood, liver, and kidney were significantly decreased, compared with weight-matched and ad libitum-fed controls. The mineral concentrations of tissues are summarized as follows: The iron (Fe) concentration in the heart, liver, and spleen was decreased in the riboflavin-deficient group compared with the other groups. Calcium (Ca) and magnesium (Mg) concentrations in tibia were decreased in the riboflavin-deficient group compared with the other two groups. Copper (Cu) concentration was increased in the heart and liver when the riboflavin-deficient group was compared with the other groups. Zinc (Zn) concentration was increased in tibia when the riboflavin-deficient group was compared with the other groups.     

Frequency of Discrimination,Harassment, and Violence in Lesbian,Gay Men,and Bisexual in Italy

Background

This cross-sectional study assessed the frequency of discrimination, harassment, and violence and the associated factors among a random sample of 1000 lesbian, gay men, and bisexual women and men recruited from randomly selected public venues in Italy.

Methods

A face-to-face interview sought information about: socio-demographics, frequency of discrimination, verbal harassment, and physical and sexual violence because of their sexual orientation, and their fear of suffering each types of victimization.

Results

In the whole sample, 28.3% and 11.9% self-reported at least one episode of victimization because of the sexual orientation in their lifetime and in the last year. Those unmarried, compared to the others, and with a college degree or higher, compared to less educated respondents, were more likely to have experienced an episode of victimization in their lifetime. Lesbians, compared to bisexual, had almost twice the odds of experiencing an episode of victimization. The most commonly reported experiences across the lifetime were verbal harassment, discrimination, and physical or sexual violence. Among those who had experienced one episode of victimization in their lifetime, 42.1% self-reported one episode in the last year. Perceived fear of suffering violence because of their sexual orientation, measured on a 10-point Likert scale with a higher score indicative of greater fear, ranges from 5.7 for verbal harassment to 6.4 for discrimination. Participants were more likely to have fear of suffering victimization because of their sexual orientation if they were female (compared to male), lesbian and gay men (compared to bisexual women and men), unmarried (compared to the others), and if they have already suffered an episode of victimization (compared to those who have not suffered an episode).

Conclusions

The study provides important insights into the violence experiences of lesbian, gay men, and bisexual women and men and the results may serve for improving policy initiatives to reduce such episodes.     

Syntheses of 4,6-dihydroxypyrimidine diones,their urease inhibition,in vitro,in silico,and kinetic studies

A library of 4,6-dihydroxypyrimidine diones (1–35) were synthesized and evaluated for their urease inhibitory activity. Structure-activity relationships, and mechanism of inhibition were also studied. All compounds were found to be active with IC₅₀ values between 22.6 ± 1.14–117.4 ± 0.73 µM, in comparison to standard, thiourea (IC₅₀ = 21.2 ± 1.3 µM). Kinetics studies on the most active compounds 2–7, 16, 17, 28, and 33 were performed to investigate their modes of inhibition, and dissociation constants K_i. Compounds 2, 3, 7, 16, 28, and 33 were found to be mixed-type of inhibitors with K_i values in the range of 7.91 ± 0.024–13.03 ± 0.013 µM, whereas, compounds 4–6, and 17 were found to be non-competitive inhibitors with K_i values in the range of 9.28 ± 0.019–13.05 ± 0.023 µM. In silico study was also performed, and a good correlation was observed between experimental and docking studies. This study is continuation of our previously reported urease inhibitory activity of pyrimidine diones, representing potential leads for further research as possible treatment of diseases caused by ureolytic bacteria.     

Clusters of Toxoplasmosis in Ganghwa-gun,Cheorwon-gun,and Goseong-gun,Korea

We find out the clusters with high toxoplasmosis risk to discuss the geographical pattern in Gyodong-myeon and Samsan-myeon of Ganghwa-gun, Cheorwon-gun, and Goseong-gun, Korea. Seroepidemiological data of toxoplasmosis surveyed using rapid diagnostic tests for the residents in the areas in 2019 were analyzed to detect clusters of the infection. The cluster was investigated using the SaTScan program which is based on Kulldorff’s scan statistic. The clusters were found with P-values in each region analyzed in the program, and the risk and patient incidence of specific areas can be examined by the values such as relative risk and log likelihood ratio. Jiseok-ri and Insa-ri were found to be a cluster in Gyodong-myeon and Seokmo-ri was the cluster in Samsan-myeon. Yangji-ri and Igil-ri were found to be a cluster in Cheorwon-gun and Madal-ri and Baebong-ri were the cluster in Goseong-gun. This findings can be used to monitor and prevent toxoplasmosis infections occurring in vulnerable areas.     

Quantitation of the involvement of the recA, recB, recC, recF, recJ, recN, lexA, radA, radB, uvrD, and umuC genes in the repair of X-ray-induced DNA double-strand breaks in Escherichia coli

Isogenic Escherichia coli strains carrying single DNA-repair mutations were compared for their capacity for (i) the repair of X-ray-induced DNA double-strand breaks (DSB) as measured using neutral sucrose gradients; (ii) medium-dependent resistance, i.e., a recA-dependent X-ray survival phenomenon that correlates closely with the capacity for repairing DSB; and (iii) the growth medium-dependent, recA-dependent repair of X-ray-induced DNA single-strand breaks (SSB) as measured using alkaline sucrose gradients (about 80% of these SSB are actually parts of DSB). These three capacities were measured to quantitate more accurately the involvement of the various genes in the repair of DSB over a wide dose range. The mutations tested were grouped into five classes according to their effect on the repair of X-ray-induced DSB: (I) the recA, recB, recC, and lexA mutants were completely deficient; (II) the radB and recN mutants were about 90% deficient; (III) the recF and recJ mutants were about 70% deficient; (IV) the radA and uvrD mutants were about 30% deficient; and (V) the umuC mutant resembled the wild-type strains in its capacity for the repair of DSB.