洪河自然保护区典型湿地植物群落组成及物种多样性梯度变化

以洪河自然保护区两类典型湿地——河漫滩湿地与碟形洼地湿地的植物群落为研究对象,探讨其物种组成及物种多样性的梯度变化规律。结果表明,由沼泽至岛状林的梯度上:(1)各群落建群种、优势种和伴生种的种类及其优势度,地表覆盖藓类等组成特征均变化明显;(2)群落的物种丰富度呈逐渐增加格局,丰富度指数分别为26、41、51、68和82;(3)群落的α多样性的变化格局与丰富度格局不太一致,Shannon-Wiener多样性与Pielou均匀度的变化格局基本一致,呈不规则"N"型格局,Simpson优势度的变化格局正好与它们相反,呈不规则倒"N"型格局;上述格局的两个"拐点"出现在沼泽化草甸群落和湿草甸群落中;(4)群落的β多样性——相异性系数和Cody指数均呈先降后升的格局,二者的最小值出现在沼泽化草甸群落和湿草甸群落之间,最大值出现在灌丛草甸和岛状林群落之间;研究认为,典型湿地植物群落物种组成和物种丰富度的梯度变化主要于生境的变化有关,α多样性的变化格局主要与生境的变化和优势种的生物学特性有关,β多样性的格局的原因比较复杂,尚需进一步探讨。     

三江平原沼泽湿地群落演替系列β多样性

选择三江平原沼泽湿地4个群落演替系列,采用样方法研究其β多样性的变化.结果表明:以水分条件最充分的群落为起点,随着水分梯度递减和水平距离的增大,各群落与起始群落的相似性系数呈减小趋势.不同演替系列内群落间物种更替速率从低地向高地呈现增大趋势.各系列的基本演替趋势是物种数逐渐增多,共有种逐渐减少,群落间β多样性增大.演替机制分析支持了“初始植物区系组成说”.在三江平原沼泽湿地中,小叶章的优势地位将进一步扩大.     

三江平原湿地典型植物群落物种多样性研究

以三江平原分布最广的毛果苔草(Carex lasiocarpa)群落和小叶章(Calamagrostis angustifolia)群落为研究对象,研究2个群落的植物物种及其组成特征。结果表明,毛果苔草群落以毛果苔草为优势种,以漂筏苔草(C.pseudocuraica)为亚优势种,二者的重要值之和为56.4%;小叶章群落以小叶章为优势种,其重要值为50.8%。物种多样性分析表明,毛果苔草群落和小叶章群落的Simpson指数(D)、Shannon-Wiener指数(H)和Pielou均匀度指数(J)均有较大波动,且H与J呈显著正相关,与D呈显著负相关,与S无显著相关关系;毛果苔草群落的H、D、J和S均高于小叶章群落,但差异不显著;2群落的相似性指数为46.5%,表明二者间存在一定的联系。     

三江平原典型沼泽湿地螺类组成生态指示

螺类作为湿地的重要生物类群,对环境变化响应敏感,这使得螺类成为潜在的环境指示物种。为了研究中国东北沼泽湿地不同类型湿地螺类群落结构的差异以及螺类作为不同类型湿地指示物种的可能,在2014年9月和2015年5月对小叶章沼泽化草甸湿地、臌囊苔草湿地、毛苔草湿地、漂筏苔草湿地共17个采样点进行螺类样品采集。共采集到了螺类8科13属17种4452个。研究表明,螺类以扁卷螺科Planorbidae、椎实螺科Lymnaeidae、膀胱螺科Physidae为主;4种不同类型湿地螺的种类组成不同,这些螺类的种类组成与不同类型湿地的水深、植物类型组成等湿地特征是相对应。螺类的生物多样性指数(ShannonWiener指数和Marglef指数)在不同类型湿地之间也存在一定差异,筛选了指示螺类6种,无褶螺是小叶章沼泽化草甸的指示物种,小土蜗、半球多脉扁螺和虹蛹螺是臌囊苔草湿地的指示物种,琥珀螺是毛苔草湿地的指示物种,平盘螺是漂筏苔草湿地的指示物种,这表明了螺类是沼泽湿地类型的重要指示生物。也为螺类生物多样性资源的保护、恢复和生态评价提供科学依据和资料积累。     

三江平原沼泽湿地群落演替系列β多样性

选择三江平原沼泽湿地4个群落演替系列,采用样方法研究其β多样性的变化.结果表明:以水分条件最充分的群落为起点,随着水分梯度递减和水平距离的增大,各群落与起始群落的相似性系数呈减小趋势.不同演替系列内群落间物种更替速率从低地向高地呈现增大趋势.各系列的基本演替趋势是物种数逐渐增多,共有种逐渐减少,群落间卢多样性增大.演替机制分析支持了"初始植物区系组成说".在三江平原沼泽湿地中,小叶章的优势地位将进一步扩大.     

三江平原小叶章群落近30年的动态变化

由于生境的改变,三江平原沼泽湿地典型植物群落中小叶章群落内部发生了显著的变化。本文以定点观测和典型湿地植物调查为基础,分析了近30年来小叶章群落的动态变化。结果表明,小叶章群落的物种频度符合Raunkiaer频度定律,即5个频度级的关系都具有A〉B〉C≥D〈E的规律性。小叶章群落的物种构成发生了明显变化,灌木类型植物逐渐增多。植物物种多样性减少。小叶章的多度、分盖度和高度都有降低趋势。     

环境因子对甘南高寒草甸地表大型节肢动物多样性的影响

地表节肢动物是生态系统的重要生物指示物,研究甘南高寒草甸地表节肢动物群落多样性与环境因子的关系,有助于揭示其分布格局对高寒草甸生态环境变化的响应。2018年5至9月,采用陷阱法调查甘南高寒草甸4种典型类型生境,即沼泽湿地、沼泽化草甸、草甸和成熟草甸地表大型节肢动物群落组成与多样性。研究时段共采集地表大型节肢动物2 545头,属于3纲9目29科30属,以狼蛛属(Lycosa)、弓背蚁属(Camponotus)和蚁属(Formica)为优势类群。营养功能群以捕食类和植食类为主。研究结果显示,成熟草甸生境大型节肢动物类群数明显高于沼泽化草甸和草甸生境的类群数(P <0.05);沼泽湿地生境Pielou均匀度指数(Js)明显大于草甸和成熟草甸生境的Pielou均匀度指数(P <0.05);Shannon-Wiener多样性指数(H′)差异不显著(P> 0.05);4种生境之间地表大型节肢动物群落相似性指数较低。研究时段基于物种“出现-不出现”C-score、V-ratio、SES与Pianka生态重叠指数的实测值与预测值的差异均没有规律性,显示研究区域地表大型节肢动物群落随机...     

封育年限对高寒草甸群落组分和物种多样性的影响

高寒草甸在青藏高原畜牧业发展中占有重要地位,然而气候和人为活动的干扰对原本脆弱的生态系统产生了深刻影响。虽然封育是被广泛采用的草地恢复有效措施之一,但封育年限对群落组分和多样性的影响一直是受关注的核心问题,探明这一问题对高寒草甸的可持续发展具有重要意义。研究了封育2、7、17a的高寒矮嵩草(Kobresia humilis)草甸的群落组分和物种多样性变化特征,并探讨了不同封育年限影响物种多样性的可能原因。结果表明:1)随封育年限延长,群落上层禾本科植物的总体重要值明显增加,其中异针茅(Stipa aliena)最为显著,其重要值封育2a(13.87%)封育7a(21.76%)封育17a(23.95%),而豆科植物总体重要值显著降低,莎草科和杂类草植物变化不明显;2)α多样性:随封育年限延长,高寒草甸群落物种丰富度指数(Patrick和Margalef指数)没有发生显著变化,然而物种多样性指数(Simpson、Shannon-Wiener和种间相遇机率指数)及均匀度指数(Alatalo和Pielou指数)均表现为封育2a封育7a封育17a,且封育2a与封育7、17a呈显著性差异(P0.05);3)β多样性:Cody指数和Morisita-Horn相似指数的变化表明,封育2a与封育7、17a之间的物种差异较大,而封育7a和17a之间的物种差异较小;4)封育后凋落物的覆盖时间及其分解引起的土壤养分变化是导致物种多样性降低的重要原因之一,土壤碳氮比(C/N)与物种均匀度指数(Alatalo指数)和多样性指数(Simpson指数和种间相遇机率指数)均呈显著性负相关关系(P0.05),说明土壤养分元素之间的耦合效应对物种多样性变化具有重要影响。本研究说明,虽然物种丰富度指数随封育年限的延长没有变化,但物种均匀度和多样性指数均降低,且封育前期对物种多样性的影响大于后期,就物种多样性而言,该高寒草甸不宜进行长期封育。该研究以期为高寒草甸生物多样性的保护和可持续利用及管理提供科学依据。     

松嫩平原湿地植物群落多样性的环境梯度分布格局及控制因子

物种丰富度格局及其决定因素是生态学核心问题,但对其形成机制仍缺乏共识。为探究松嫩平原西部半干旱区沿湖岸至高地环境梯度(局地尺度)植物群落多样性分布格局及其决定因素,以沿该梯度依次分布的7种群落(狭叶香蒲沼泽、小香蒲沼泽、芦苇沼泽、草丛沼泽、拂子茅草甸、羊草草甸和榆树疏林)为对象,采用样带网格调查法及聚类分析法划分群落类型,测定物种丰富度、α多样性和β多样性及其环境因子(水位、土壤含水率、有机质等),揭示群落多样性空间分布规律及其形成机制。结果表明,沿湖岸至高地环境梯度：(1)物种丰富度(2.00—18.00)和α多样性(Simpson指数0.12—0.90;Shannon-Wiener指数0.23—2.57和Pielou指数0.34—0.88)总体上均呈类似N字型分布(在下部深水生境狭叶香蒲沼泽最低、中下部季节性积水生境草丛沼泽最高、中上部湿润生境拂子茅草甸较低、上部沙丘干旱生境榆树疏林又较高);(2)广义的β多样性(Jaccard指数0.56—0.96)可以分解成物种周转(丰富度没有变化的地点间的物种替代)和嵌套(物种贫乏地点是物种丰富地点子集时的物种差异)两个过程,其在该梯度上半段...     

不同水位梯度下拉鲁湿地典型湿草甸植物群落特征

以位于拉鲁湿地国家级自然保护区的高寒湿草甸为研究对象,基于微地貌差异选取了5个水位带(水位分别为-15.0、-5.0、0.0、2.5和6.5 cm),通过典型样地群落调查,分析了生长初期和生长旺盛期拉鲁湿地湿草甸植物群落的物种多样性及地上部分生物量特征对水位梯度的响应规律。结果表明:生长初期和生长旺盛期不同水位下拉鲁湿地湿草甸植物群落的物种多样性及地上部分生物量特征均存在显著差异(P0.05)。群落的物种丰富度指数、Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数总体上在-15.0 cm水位下最大,在6.5cm水位下最小。随着水位的升高,2个生长期群落的物种丰富度指数、Simpson多样性指数和Shannon-Wiener多样性指数总体上呈降低的趋势;生长初期Pielou均匀度指数呈先降低后升高的趋势,而生长旺盛期则呈"降低—升高—降低"的趋势;而在-5.0~2.5 cm水位范围内,随着水位的升高,2个生长期群落的物种丰富度指数、Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数总体上呈升高的趋势。随着水位的升高,群落的地上部分生物量(地上部分鲜质量和干质量)呈"升高—降低—升高"的趋势,而地上部分干鲜比呈降低的趋势。在生长初期,地上部分鲜质量和干质量均在6.5 cm水位下最大,在-15.0和0.0 cm水位下较小;在生长旺盛期,地上部分鲜质量和干质量均在-5.0 cm水位下最大,在0.0和2.5 cm水位下较小。研究结果显示:物种丰富度指数和Shannon-Wiener多样性指数可以用于高寒湿草甸植被的监测和评价。     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。