La corriente de Malvinas. Ramas y frentes oceánicos en el mar patagónico

La corriente de Malvinas corre de sur a norte sobre el borde del talud que marca el fin de la plataforma continental patagónica (océano Atlántico sudoccidental), a lo largo de unos 1800 kilómetros. Su presencia da lugar a una zona del mar con muy rica diversidad biológica y ecológica, lo que incluye pesquerías de importancia económica regional. Los datos satelitales permiten avanzar el estudio del mar patagónico en una zona en que las aguas de la plataforma continental cambian de temperatura por efecto de la corriente fría de Malvinas, lo que influye notablemente sobre la vida marina. Este artículo de divulgación científica incluye información sobre frentes oceánicos del Mar Argentino, datos satelitales y detección de ramas y frentes térmicos, la ecología de las especies marinas, finalizando con lecturas sugeridas.

Universidad y ciencias del mar: a treinta años del Instituto Interuniversitario de Biología Marina de Mar del Plata

Hace treinta años se creaba el Instituto Interuniversitario de Biología Marina de Mar del Plata (IIBM), Argentina, posteriormente desaparecido por influjo de las vicisitudes políticas acontecidas desde entonces. Uno de sus fundadores analiza los principios institucionales y científicos que guiaron el accionar de aquella entidad, a la vez que reflexiona acerca de la situación actual de las ciencias del mar.

特殊涡鞭毛虫（甲藻）尖尾藻(Oxyrrhis marina)核骨架的初步检查

为检查特殊的涡鞭毛虫－－尖尾藻(Oxyrrhis marina)是否已进化产生了核骨架结构，若有的话，又与典型真核细胞核骨架在形态结构上有何异同，用了两种方法。方法一是将分离出的尖尾藻细胞核，仿照P. R. Gook的方法用含高盐及去垢剂的分解液处理之后再经DNase除去DNA，用透射电镜观察。方法二是采用S. Penman实验室的分级抽提、DGD包埋－去包埋剂电镜技术，但根据尖尾藻的生理特性作了修改。此外还用了以热三氯醋酸除去核酸的方法。方法一的实验结果表明，尖尾藻细胞核内有一个起框架作用的纤维蛋白结构，此结构类似于用同一方法在典型真核细胞上所显示的“nuclear cage”结构。方法二的结果显示，尖尾藻细胞核内存在一个纤维网架结构，核仁与染色体都被网络于其间。其纤维粗细为2.8nm到24nm，它们与细胞（质）骨架中的中间纤维（IF）有着广泛的联系。此网架结构是由非DNA性质的纤维蛋白组成的，其中还含有对维持其三维结构所必需的RNA成分。它们的这些特点都十分相似于典型真核细胞核骨架的特点。另外尖尾藻的核纤层及核骨架纤维上所结合的核糖核蛋白颗粒（RNP）方面又与典型真核生物的有差别。本工作首次证明了特殊涡鞭毛虫毛类－－尖尾藻已有了核骨结构。

尖尾藻（Oxyrrhis marina）染色体固定特性的比较研究

本工作采用单纯戊二醛、单纯四氧化锇、戊二醛加四氧化锇双固定及Ryter和Kellenberger的细菌类核体“标准固定方法”等四种固定方法，在尖尾藻与典型涡鞭毛虫双甲藻(Prorocentrum micans)、典型原核生物肠道细菌、眼虫(Euglean sp.)、典型真核细胞小鼠胸腺细胞之间比较了电镜下所观察到的染色体和类核体的固定特性。实验结果表明尖尾藻染色体的固定特性异于典型涡鞭毛虫染色体的固定特性。而与眼虫染色体的相同，与典型真核细胞异染色质的相似。这些结果支持关于重新确定尖尾藻分类地位的设想；实验结果还指出尖尾藻染色体和眼虫染色体在碱性蛋白被抽提尽后，它们的固定特性均与细菌类核体的相似，这提示除了染色体碱性蛋白或组蛋白的含量是染色体固定特性的一个决定因素外，染色体碱性蛋白与DNA纤维的结合方式也可能影响染色体的固定特性。

鞭毛虫尾藻（Oxyrrhis marina）细胞核的有丝分裂

尖尾藻细胞核的有丝分裂在涡鞭毛虫中间是非常独特的，可能对于了解有丝分裂的进化具有重要的意义。利用低速离心处理和低温（4℃）正常温度（19 ± 1℃）周期性自理相结合的办法，成功地实现了尖尾藻的同步化培养。以同步化培养的群体作为材料，用电子显微镜研究了尖尾藻细胞核有丝分裂过程中的超微结构变化。根据核中染色体的形态，间期细胞核可以分为两种类型-I型和II型。在II型间期核中，染色体比I型间期核中的染我体粗，其中的一部份呈棒状，另一部分形状不规则。在这两种类型的间期核中，细胞核和核仁都作园形。尖尾藻的分裂态Y形和U形染色体是出现在分裂间期细胞核中。前期时，核变成卵形，核仁伸长，在核膜上出现核小板（Nuclear Plaqes）；从核小板向核内发出微管。我们的观察表明在尖尾藻的核分开明过程中，虽然没有赤道板出现，但中期仍然是存在的。与许多高等真核生物一样，类尾藻的后期也可以分成后期A和后期B。后期A时，核内染色体向两极度移动，细胞核没有显著的伸长。染色体的极度向运动可能是由于与染色体相连的牵引微管的缩短和位于正在移向两极度的两条染色体之是的微管的伸长两种因素相互协调地起作用而引起的。在后期A细胞核中，位于两极度的微管组织者是多个位于核膜上的核小板，它们并未融合成为统一的微管组织中心。在后期B时，在细胞核的中间共很少见到微管，细胞核伸长，到末期开始时，核的长度大约是后期A细胞核的两倍。这种伸长很可能是由于中间区核膜的生长。在整个核分裂过程中，始终有核膜存在。我们发现微管也会与分裂中的核仁相连，这表明微管在核仁分裂中可能起着重要的作用。根据已有的资料，讨论了有丝分裂的机制和有丝分裂的进化。

Seed-bank development, germination and early seedling survival of two seagrass species from The Netherlands: Zostera marina L. and Zostera noltii hornem

Flowering and seed-bank development of annual Zostera marina L. and perennial Z. noltii hornem. were studied in the Zandkreek (S.W. Netherlands). Flowering of Z. noltii started at the end of June and continued until the end of September. A maximum of ca. 1000 flowering shoots (11% of the total amount of shoots per square metre) occurred in early August. Flowering of Z. marina started at the end of July and continued throughout October. Seed banks of both species appeared to be annual. Actual seed densities of Z. noltii were much lower than predicted on the basis of the amount of inflorescences.Germination was studied in the laboratory in relation to temperature (10, 20 and 30°C), salinity (1.0, 10.0, 20.0, 30.0 and 40.0‰) and stratification (at 4°C). Both species showed a maximal germination at 30°C and 1.0‰ salinity, decreasing with higher salinities and lower temperatures. Stratification stimulated germination only at salinities 20.0‰. Desiccation and anaerobia were lethal to Z. marina seeds. Seedlings of Z. marina survived best at 10°C and 10.0–20.0‰ salinity and those of Z. noltii survived best at 10°C and 1.0‰ salinity. Overall, seedlings of Z. marina survived better than those of Z. noltii.

A new acylated iridoid glucoside from Avicennia marina

A new acylated iridoid glucoside, namely, 2'-O-(5-phenyl-2E, 4E-pentadienoyl)mussaenosidic acid, was isolated from the aerial parts of the mangrove plant Avicennia marina. The structure of the new compound was established on the basis of various NMR spectroscopic analyses, including 2D NMR techniques (H-1-H-1 COSY, HMQC, and HMBC) and HR-FAB-MS. This compound displayed moderate antioxidant activity.

Morphology and infraciliature of three species of Metaurostylopsis (Ciliophora, Stichotrichia): M. songi n. sp., M. salina n. sp., and M. marina (Kahl 1932) from sediments, saline ponds, and coastal waters.

Two new urostylid ciliates, Metaurostylopsis songi n. sp. and Metaurostylopsis salina n. sp. and Metaurostylopsis marina (Kahl 1932) are investigated using live observation and protargol impregnation. These species were isolated in Korea from intertidal sediments, saline ponds, and coastal waters. Metaurostylopsis songi is in vivo about 120 pm x 25 mu m, has a slenderly ellipsoidal body, colorless cortical granules in rows on ventral and dorsal body sides, about 54 macronuclear nodules, 28-47 adoral membranelles, five frontal, two or three frontoterminal and six or seven transverse cirri, and 9-12 midventral cirral pairs followed posteriorly by 1-3 single cirri. In vivo M. salina is about 60 pin x 25 mu m, has a pyriform body, colorless cortical granules irregularly arranged, about 45 macronuclear nodules, 18-23 adoral membranelles, three frontal, three to five frontoterminal and two to five transverse cirri, and four or five midventral cirral pairs followed posteriorly by five to seven single cirri. Both species have three marginal cirral rows on each body side and 3 long dorsal kineties. The Korean specimens of M. marina match the Chinese population in all main features. Metaurostylopsis songi differs from M. marina by the more slender body, the number of frontal cirri (invariably five vs. four), and the arrangement of cortical granules (in rows on dorsal and ventral cortex vs. only along dorsal kinetics and anterior body margin). Metaurostylopsis salina differs from its congeners by the distinctly smaller size, the pyriform body shape, the scattered cortical granules (vs. in rows), and number of frontal cirri. It differs from M. marina also by the number of midventral cirral pairs (four or five vs. seven to 11).

Une aventure franco Brésilienne vivante...

2007

Le Cheval de Mazeppa, un cas d'intertextualit? franco-anglaise

Sibona, Bruno, Le Cheval de Mazeppa, un cas d'intertextualit? franco-anglaise (L'Harmattan, 2006)

THE PERFORMER’S INFLUENCE ON FRANCO-BELGIAN COMPOSITIONS FROM 1870 TO 1930

The turn of the 20th century marked an ascendancy of the Franco-Belgian school of composers. French composers were inspired by the great German composers of the Romantic era, and they created their own defined national style that emerged toward the end of the 19th century. The Franco-Belgian composers’ special emphasis on tone, timbre and color encouraged a more individual, personally interpretative approach. These devices underscore the importance and influence a performer can have on the outcome of a piece. I researched the relationship between composers and violinists at a time when the Franco-Belgian style developed and flourished. The Franco-Belgian school of violin playing emerged from the Paris and Brussels conservatories as well as the symbiotic relationship between the performers and composers. Three recitals in collaboration with pianist David Ballena, which comprise this dissertation project, were performed at the University of Maryland. Each recital featured music for violin and piano from 1870 through 1930. The repertoire was chosen to reflect a performer’s influence on a composer. I examined specific composer/performer relationships that helped shape the birth of a newly defined “French” style of playing. My research focused on the stylistic interactions composers, such as César Franck, his disciple Guillaume Lekeu had with the leading prominent Belgian violinist Eugène Ysaye and between Maurice Ravel and the Hungarian violinist Jelly d’Aranyi. I also looked into the personal relationship between friends who inspired each other: Gabriel Fauré and Paul Viardot, Edouard Lalo and Pablo de Sarasate, Claude Debussy and Arthur Hartmann, and the young Lili Boulanger and Yvonne Astruc. Furthermore, I looked into the unfulfilled love between Maurice Ravel and Hélène Jourdan-Morhange, as well as the marriage of Olivier Messiaen with Claire Delbos, both relationships resulting in masterpieces for violin that have remained a part of the standard violin repertoire. My research led me to understand what type of violin playing each composer had in mind while composing, all of which led me to understand the importance a performer has in preserving national styles. The recitals were recorded on compact discs and archived within the Digital Repository at the University of Maryland (DRUM).

WORKS BY FRANCO-BELGIAN COMPOSERS AND THE VIOLINISTS WHO INSPIRED THEM

In the late nineteenth century, French composers such as Camille Saint- Saens, Cesar Franck, and Claude Debussy worked to elevate instrumental music in late-Romantic period France, creating symphonies, concertos, and chamber ensembles, including duo sonatas. These composers and followers like, Ernest Chausson and Guillaume Lekeu were all influenced by a particular violinist to whom they dedicated their compositions. The primary violinist who inspired these composers was Eugene Ysaye (1858-1931), a brilliant performer and composer. His freedom of expression motivated many prominent French composers to dedicate major works to him. For example, Debussy dedicated his string quartet to Ysaye, who established the Ysaye Quartet and premiered Debussy's composition. In 1886, Franck completed his sonata for violin and piano which he also dedicated to Ysaye. Fritz Kreisler (1875-1962), one of the most talented violinists of his era, had a relationship withYsaye that was quite special. They respected, supported, and befriended each other. To Ysaye, Kreisler dedicated his Recitativo and Scherzo. To Kreisler, Ysaye dedicated one ofhis celebrated Sonatas for Solo Violin. Pablo de Sarasate (1844-1908) was a magnificent Spanish violinist of the late nineteenth century, and his music and performances influenced many composers, especially Saint-Saens, who included Spanish gypsy fragments in his works. These motifs may found in his Havanaise, Introduction and Rondo Capriccioso and Violin Concerto No.3 which were dedicated to Sarasate. My goal for this dissertation project has been to find and present, in three recitals, works by French composers and also works by the violinists who inspired them. As a violinist, I have endeavored to understand the influence of the various violinists on these French composers and how that knowledge can inform my approach to performing these works. In my first recital, with pianist Soo Young Jung, I performed works by Saint-Saens, Ysaye and Sarasate. With pianist Sun Ha Yoon, I performed works by Ysaye, Debussy, Kreisler and Franck in my second recital. My third recital, again with pianist Sun Ha Yoon, featured works by Ysaye, Chausson, and Lekeu. All recitals were recorded and performed at the University ofMaryland, College Park.