442 resultados para Wolffia globosa


Relevância:

10.00% 10.00%

Publicador:

Resumo:

A subtribo Elephantopinae tem sido alvo de poucos estudos taxonômicos e palinológicos, necessitando de uma reavaliação em seus limites. Assim, o presente estudo teve como proposta atualizar e ampliar o conhecimento de 13 espécies de Elephantopinae ocorrentes no Brasil através de um acurado estudo palinológico, da anatomia foliar e taxonômico, promovendo a delimitação das espécies dos gêneros Elephantopus (10 espécies) Orthopappus (uma espécie) e Pseudelephantopus (duas espécies)além de oferecer subsídios para posteriores análises filogenéticas. O material botânico utilizado foi obtido através de exsicatas depositadas nos herbários brasileiros e de material coletado em campo. Os grãos de pólen foram tratados pelo método acetolítico, sendo posteriormente mensurados, descritos, e analisados sob microscopia de luz e eletrônica de varredura. As eletromicrografias foram obtidas de grãos de pólen não acetolisados, as análises taxonômicas baseiam-se na metodologia clássica. A anatomia foliar deu-se através da metodologia usual. Os resultados mostram grãos de pólen médios, 3-porados, de exina equinolofada com malhas poligonais organizadas ou não em Elephantopus e Pseudelephantopus, podendo apresentar interrupção na malha poral em Elephantopus. Em Orthopapus os grãos de pólen são 3-colporados, de sexina subequinolofada. A anatomia foliar possibilitou a separação de E. hirtiflorus e E. riparius através da forma ou contorno da nervura principal (planoconvexo), nas demais espécies o contorno é biconvexo. As espécies apresentaram tricomas capitados bisseriados com 8 células, tricomas filamentosos 3-4 celulares, bem como filamentosos de célula distal globosa ou ovóide em E. biflorus, E. micropappus, E. tomentous e Orthopappus angustifolius. Registrou-se variação na ornamentação da cutícula podendo ser lisa ou estriada entre as espécies, bem como a presença de substâncias pécticas na epiderme e drusas nos parênquimas. Em relação aos microcaracteres florais, foram considerados de importância diagnóstica os lóbulos da corola, que variaram entre glandular, glabro e penicilado, este ultimo apenas em E. hirtiflorus, os ápices das anteras que variaram entre obtuso, retuso em E. hirtiflorus e apiculado, lancelolado em E. mollis e E. racemosus, a base da antera variou entre sagitada, caudada lisa em E. riparius e E. tomentosus e caudada em E. riparius. Os macrocaracteres que apresentaram maior valor taxonômico foram a cipsela e o papus, a organização das coflorescências, o número de flores por capítulo e limbo foliar. Neste trabalho aceitou-se a segregação dos três gêneros, com base nos caracteres analisados

Relevância:

10.00% 10.00%

Publicador:

Resumo:

半寄生植物马先蒿属(Pedicularis)是列当科(Orobanchaceae)中最大的属,也是北温带被子植物最大的属之一。该属至少有500种植物,主要分布在北半球的高山、亚高山地区或高纬度地区,其中超过一半的种类分布在东喜马拉雅至横断山区,构成该地区高山植物区系的主要成分。马先蒿属花部器官的强烈分化程度在被子植物中极为罕见,导致这种分化发生的机制仍是难解之谜。马先蒿属下系统非常混乱,迄今为止该属属下分类系统不下10个。关于该属的起源时间、地点及迁移散布过程只是基于一些间接证据的推测。针对以上问题,本文通过大量的标本查阅、野外考察、传粉生物学观察以及分子系统学研究,得出了一些初步的结果。   1.形态学 通过大量的野外考察及标本观察,发现马先蒿属花部器官变异非常复杂,是区分近缘种的主要性状依据,但是花部器官存在明显的平行进化现象,不适合作为划分群、组等属下高级分类单元的主要依据;而营养性状比较保守,可作为划分群、组的主要依据。通过考证,发现直管群万叶系的德钦马先蒿(P. deqinensis)实属轮枝群纤细系多枝马先蒿(P. ramosissima)的异名。同时发现一个新种,即折喙马先蒿(P. inflexirostris),该种属于直管群的万叶系。   2.传粉生物学 对27种马先蒿的昆虫传粉行为进行了初步的观察。发现横断山区的马先蒿主要靠熊蜂进行有效的传粉。昆虫的传粉方式有两种,即背触式(Nototribic)和腹触式(Sternotribic)。不同花冠类型的马先蒿属植物中,昆虫的传粉方式也有所区别。对短管、无喙、无花蜜的马先蒿,昆虫主要以腹触式完成传粉;对短管、无喙、具花蜜的马先蒿,昆虫既可以通过背触式也可以通过腹触式完成传粉;而对短管、具喙和长管、具喙的马先蒿,昆虫都以腹触式完成传粉。没有发现鳞翅目的昆虫访问长管类型的马先蒿。不同花冠类型传粉方式的不同说明马先蒿花部形态结构和传粉媒介的行为之间存在协同进化关系。 3.核rDNA ITS分析 对12个群的42种马先蒿的核rDNA ITS序列进行了分析。基于ITS序列构建的基因树和经典的属下分类系统很不一致,基因树上的大部分分支和经典系统中的高级分类单元不相吻合,原因可能是马先蒿属花部器官发生了平行进化,而经典的分类系统过于权重这些花部形态性状。此外,发现在横断山区这一相对狭小的地域范围内,nrDNA ITS序列在马先蒿种间存在很大差异。造成此差异的原因可能有两个方面:一方面是马先蒿属的起源和分化的时间可能较早,不同的支系从其他地域先后多次迁入横断山区;另一方面可能是由于半寄生植物马先蒿中快速的分子进化造成的。 4.叶绿体基因组trnT-F区序列分析 对8个群的11种马先蒿的trnT-F区序列进行了分析,发现种间存在大量的插入/缺失序列,其中甘肃马先蒿(P. kansuensis)和大王马先蒿(P. rex)分别在trnT-trnL(UAA)和trnL–trnF基因间区发生了长达228bp和303bp碱基序列缺失,说明半寄生植物的叶绿体基因组也可能存在大量基因丢失现象。 5. GLOBOSA-like MADS-box基因的研究 对11种马先蒿属植物(8个群)中控制花瓣发育的GLOBOSA(PGLO)基因的部分片段进行了分离、克隆和测序,发现该基因在种间发生了明显的分化,但是碱基的变异主要发生在非编码区或非结构域,基因的同义突变率远高于非同义突变率,说明PGLO基因的进化受到强烈的功能制约。PGLO基因在马先蒿种间的明显分化表明:在辐射分化类群中,调节基因也可能发生了快速分化。对11种马先蒿属植物的PGLO基因树、nrDNA ITS基因树以及trnT-F基因树的比较发现:三个树图在结构上既有一致、也有相互矛盾之处,推测可能是因为这些基因具有不同的遗传体系或经历了不同的进化历史所致,另一方面说明GLOBOSA基因在探讨近缘类群系统发育关系方面的价值有待进一步验证。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

在已发现的超积累植物中,镉超积累植物种类较少,对其重金属耐性及超积累机理的研究还未有突破性进展,这些植物金属耐性机理的描述对于镉污染土壤的植物修复研究是非常有意义的。本研究以镉超积累植物龙葵(Solanum nigrum L.)、球果蔊菜(Rorippa globosa (Turcz.) Thell.)为研究对象,以茄子(Solanum melongena L.)和风花菜(Rorippa islandica (Oeder.) Borb.)为对照植物,描述了镉超积累植物污染耐性的生态特征,系统探讨了镉超积累植物的耐性机制。 (1)龙葵较茄子有更高的镉耐性及镉积累性;球果蔊菜较风花菜有更高的镉耐性及镉积累性,球果蔊菜茎部受抑制现象是实现其特异吸收和积累重金属的适应性反应,这种地上部营养物质的重新分配现象可能是球果蔊菜作为超积累植物独特的生态特征。 (2)龙葵根系中SOD和CAT活性及叶片中POD和CAT活性的协同作用在缓解镉积累引起的膜脂过氧化损伤中发挥着积极作用,球果蔊菜叶片SOD和CAT的协同作用在缓解镉积累引起的膜脂过氧化损伤中也发挥重要作用,可以推断龙葵、球果蔊菜体内抗氧化酶防御系统在其镉耐性中扮演重要的角色。 (3)镉的污染胁迫均能明显促进龙葵和球果蔊菜体内脯氨酸的积累,脯氨酸在其镉耐性及积累性中扮演着重要角色,其中叶片脯氨酸可能发挥着更大的作用。 (4)龙葵叶片中柠檬酸和乙酸含量的动态变化与其镉积累有关,球果蔊菜叶片中苹果酸和酒石酸含量的动态变化与其镉积累有关,有机酸可能在龙葵及球果蔊菜镉耐性及积累性中起到一定的作用,但高含量的有机酸并不是植物镉耐性和超积累性的主要原因。 (5)植物螯合肽可以作为植物镉超积累特征的生物指标,但植物螯合肽的合成并非镉超积累植物耐性的主要机制。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

采用盆栽方法,以风花菜(Rorippa islandica)为对照植物,研究Cd超积累植物球果蔊菜[Rorippa globosa(Turcz.)Thell.]脯氨酸的积累、丙二醛含量、生物量及叶绿素含量的变化,及其与Cd生物积累的关系.结果显示,Cd处理能明显促进2种植物体内脯氨酸的积累,当土壤中Cd浓度≤25μg/g时,球果蔊菜叶片脯氨酸的积累效应尤为显著;此时叶片生物量、叶绿素及丙二醛含量与对照相比均无显著差异,表明其叶片脯氨酸的积累在一定程度上可缓解Cd胁迫造成的氧化损伤.相关分析表明,球果蔊菜根系脯氨酸可指示球果蔊菜根系中Cd的积累.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Qianyanzhou(QYZ) Ecological Station established in 1983 with an area of 204 hm~2 is affiliated to the Chinese Ecosystem Research Network.Before 1982,herbs had been dominant,sparsely dotted with shrubs.After 20-year restoration of the vegetation,the vegetation showed significant changes in both forest coverage and species diversity.Forest coverage had increased to 93.3% in 1999 from 0.4% in 1982.The vegetation could be broadly classified into two groups: artificial forest,accounting for the most percent,and natural secondary forest.These two groups could be subdivided into 12 types.Based on the 2003 field work,The authors studied plant community composition and vertical structure.The results were as follows: 1) On the study plots were there about 150 species,of which 100,49,and 47 grew in arbor layer and shrub layer and herb layer,respectively.Of 12 community types,the amount of species in shrub layer was larger than that of other two layers.As to the species richness in the different community types,Liquidambar formosana community showed the highest and Imperata cylindrical var.major community the least.The amount of species in arbor layer of artificial forest was smaller than those of natural Pinus massoniana forest,but no difference in understory.2) Loropetalum chinense,Quercus fabric and Vaccinium bracteatum were dominant shrub species with a wide distribution.Three ferns Woodwardia japonica、Dryopteris atrata and Dicrannepteris dichotoma were dominant herb species.Lianas were sparse,but Milletlia reticulata were found in all forest types.3) Up to now some natural regeneration species,such as Eurya muricata、Quercus fabri、Vaccinium bracteatum、Rhus chinensis、Adinandra bockiana,had grown in the arbor layer of artificial forests.Some herb species,such as Arundinella setosa、Miscanthus floridulus、Isachne globosa、Scirpus triqueter,which were dominant ones in the herb layer before the restoration of vegetation,disappeared now.4) The vertical structure of natural Pinus massoniana community and Liquidambar formosana community showed more complex comparing with artificial forests.For the artificial forests,the conifer and broad-leaves mixed forest had a more complex structure.In both natural Pinus(massoniana) community and Liquidambar formosana community,it was dominated by individuals with height of 3~4 m,while 10~12 m in the artificial forests.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The toxicity of seven major HAB (harmful algal bloom) species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense (AT-6, non-PSP producer), Alexandrium lusitanicum, Alexandrum tamarense (ATHK) and Heterosigma akashiwo were studied against rotifer Brachionus plicatilis under laboratory conditions. The results show that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6), or A. lusitanicum could maintain the individual survival and reproduction, as well as the population increase of the rotifer, but the individual reproduction would decrease when exposed to these five algae at higher densities for nine days; H. akashiwo could decrease the individual survival and reproduction, as well as population increase of the rotifer, which is similar to that of the starvation group, indicating that starvation might be its one lethal factor except for the algal toxins; A. tamarense (ATHK) has strong lethal effect on the rotifer with 48h LC50 at 800 cells/mL. The experiment on ingestion ability indicated by gut pigment change shows that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6) and A. lusitanicum can be taken by the rotifers as food, but A. tamarense (ATHK) or H. akashiwo can be ingested by the rotifers. The results indicate that all the indexes of individual survival and reproduction, population increase, gut pigment change of the rotifers are good and convenient to be used to reflect the toxicities of HAB species. Therefore, rotifer is suggested as one of the toxicity testing organisms in detecting the toxicity of harmful algae.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A new species of Spionidae, Scolelepis (Scolelepis) daphoinos sp. nov., is described and illustrated from northern China seas. The species was frequently encountered and highly abundant on sand beaches, but rarely found in subtidal areas. It was formerly misidentified as S. (S.) squamata (Muller, 1806) in China but differed from the latter species in several details in morphology, including the presence of obvious reddish pigmentation patches and the absence of unidentate hooded hooks. Another two Scolelepis species, S. (S.) lingulata Imajima, 1992 and S. (S.) variegata Imajima, 1992, are reported for the first time from Chinese waters. Two species of Scolelepis, S. (S.) globosa Wu & Chen, 1964 and S. (S.) lefebvrei (Gravier, 1905), were reported previously; therefore, five species in this genus are known from China in total. A key to all Scolelepis species from Chinese waters is provided.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The detection of dense harmful algal blooms (HABs) by satellite remote sensing is usually based on analysis of chlorophyll-a as a proxy. However, this approach does not provide information about the potential harm of bloom, nor can it identify the dominant species. The developed HAB risk classification method employs a fully automatic data-driven approach to identify key characteristics of water leaving radiances and derived quantities, and to classify pixels into “harmful”, “non-harmful” and “no bloom” categories using Linear Discriminant Analysis (LDA). Discrimination accuracy is increased through the use of spectral ratios of water leaving radiances, absorption and backscattering. To reduce the false alarm rate the data that cannot be reliably classified are automatically labelled as “unknown”. This method can be trained on different HAB species or extended to new sensors and then applied to generate independent HAB risk maps; these can be fused with other sensors to fill gaps or improve spatial or temporal resolution. The HAB discrimination technique has obtained accurate results on MODIS and MERIS data, correctly identifying 89% of Phaeocystis globosa HABs in the southern North Sea and 88% of Karenia mikimotoi blooms in the Western English Channel. A linear transformation of the ocean colour discriminants is used to estimate harmful cell counts, demonstrating greater accuracy than if based on chlorophyll-a; this will facilitate its integration into a HAB early warning system operating in the southern North Sea.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Meroplankton are seasonally important contributors to the zooplankton, particularly at inshore sites, yet their feeding ecology is poorly known relative to holoplankton. While several studies have measured feeding in decapod larvae, few studies have examined the feeding rates of decapod larvae on natural prey assemblages throughout the reproductive season. We conducted 8 feeding experiments with Necora puber, Liocarcinus spp. and Upogebia spp. zoea larvae collected from the L4 monitoring site off Plymouth (50°15.00′N, 4°13.02′W) during spring–summer 2009 and 2010. This period spanned moderate-to-high food availability (0.5–1.6 µg chl-a L−1), but a great range in food composition with small cells <20 µm dominating in 2010. Daily rations averaged 17, 60 and 22 % of body C for the 3 respective decapod species. Clearance rates differed according to prey type, and all 3 decapod genera showed evidence of selection of dinoflagellates. Importantly, small cells including nano- and pico-plankton were ingested, this being demonstrated independently by flow cytometric analysis of the feeding experiments and molecular analysis. PCR-based analysis of the haptophyte portion of the diet revealed ingestion of Isochrysis galbana by decapod larvae in the bottle incubations and Isochrysis galbana and Phaeocystis globosa by decapod larvae collected directly from the field. This study has shown that pico- and nano-sized plankton form an important supplement to the diverse and variable diet of decapod larvae.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The yeasts of the Malassezia genus are opportunistic microorganisms and can cause human and animal infections. They are commonly isolated from the skin and auricular canal of mammalians, mainly dogs and cats. The present study was aimed to isolate Malassezia spp. from the acoustic meatus of bats (Molossus molossus) in the Montenegro region, `` Rondonia ``, Brazil. From a total of 30 bats studied Malassezia spp. were isolated in 24 (80%) animals, the breakdown by species being as follows (one Malassezia sp. per bat, N=24): 15 (62.5%) M. pachydermatis, 5 (20.8%) M. furfur, 3 (12.5%) M. globosa and 1 (4.2%) M. sympodialis. This study establishes a new host and anatomic place for Malassezia spp., as it presents the first report ever of the isolation of this genus of yeasts in the acoustic meatus of bats.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

O potencial alelopático de quatro diferentes extratos de plantas medicinais (Eclipta alba, Gomphrena globosa, Tabernaemontana catharinensis e Tithonia diversifolia) foi avaliado na germinação de Bidens pilosa e Lactuca sativa. Dentre os resultados obtidos no teste de germinação, notou-se um maior poder inibitório do extrato de G. globosa sobre sementes e plântulas de Bidens pilosa e Lactuca sativa independente da concentração utilizada e aumento da atividade inibitória de extratos T. catharinensis e de T. diversifolia com aumento da concentração destes. Quanto ao Índice de Velocidade de Germinação, os dados demonstraram redução do índice devido a elevada mortalidade das plântulas submetidas aos extratos de G. globosa e de T. catharinensis e a germinação tardia das sementes submetidas ao extrato de T. diversifolia. Quanto ao vigor das sementes, as menores porcentagens de sobrevivência ocorreram extratos à 2,5% para B. pilosa e 10% para L. sativa.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Obtiveram-se parâmetros fisiológicos que pudessem ser utilizados como referência para diagnóstico e prognóstico confiáveis de doença prostática em cães. Trinta e seis cães, sem sinais clínicos de doença prostática ou distúrbios reprodutivos, foram distribuídos em três grupos de acordo com a idade.Os animais foram submetidos à colheita manual de sêmen para exames microbiológicos, à ultrassonografia transabdominal, para avaliar as dimensões, a ecogenicidade e a ecotextura prostática, e à punção aspirativa com agulha fina, para análise citológica e microbiológica. A ultrassonografia revelou que a forma predominante da próstata foi globosa, com superfície de contorno regular. As dimensões variaram de acordo com a idade, sendo pequena em animais jovens e grande nos animais idosos. Houve correlação positiva entre as dimensões prostáticas e o peso corporal. Os exames microbiológicos detectaram microrganismos no plasma seminal de 11 cães e no tecido prostático aspirado de 10 animais, embora eles fossem saudáveis. A citologia não revelou nenhuma alteração inflamatória, proliferativa ou neoplásica nos cães jovens e de meia idade, mas, em três cães idosos foram encontrados sinais de hiperplasia/hipertrofia. Foi observada correlação positiva entre a idade e a área celular e correlação negativa entre a relação núcleo:citoplasma e a dimensão craniocaudal.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)