The Dynamics of the Policies of Ethnic Cleansing in Silesia in the Nineteenth and Twentieth Centuries

Through studying German, Polish and Czech publications on Silesia, Mr. Kamusella found that most of them, instead of trying to objectively analyse the past, are devoted to proving some essential "Germanness", "Polishness" or "Czechness" of this region. He believes that the terminology and thought-patterns of nationalist ideology are so deeply entrenched in the minds of researchers that they do not consider themselves nationalist. However, he notes that, due to the spread of the results of the latest studies on ethnicity/nationalism (by Gellner, Hobsbawm, Smith, Erikson Buillig, amongst others), German publications on Silesia have become quite objective since the 1980s, and the same process (impeded by under funding) has been taking place in Poland and the Czech Republic since 1989. His own research totals some 500 pages, in English, presented on disc. So what are the traps into which historians have been inclined to fall? There is a tendency for them to treat Silesia as an entity which has existed forever, though Mr. Kamusella points out that it emerged as a region only at the beginning of the 11th century. These same historians speak of Poles, Czechs and Germans in Silesia, though Mr. Kamusella found that before the mid-19th century, identification was with an inhabitant's local area, religion or dynasty. In fact, a German national identity started to be forged in Prussian Silesia only during the Liberation War against Napoleon (1813-1815). It was concretised in 1861 in the form of the first Prussian census, when the language a citizen spoke was equated with his/her nationality. A similar census was carried out in Austrian Silesia only in 1881. The censuses forced the Silesians to choose their nationality despite their multiethnic multicultural identities. It was the active promotion of a German identity in Prussian Silesia, and Vienna's uneasy acceptance of the national identities in Austrian Silesia which stimulated the development of Polish national, Moravian ethnic and Upper Silesian ethnic regional identities in Upper Silesia, and Polish national, Czech national, Moravian ethnic and Silesian ethnic identities in Austrian Silesia. While traditional historians speak of the "nationalist struggle" as though it were a permanent characteristic of Silesia, Mr. Kamusella points out that such a struggle only developed in earnest after 1918. What is more, he shows how it has been conveniently forgotten that, besides the national players, there were also significant ethnic movements of Moravians, Upper Silesians, Silesians and the tutejsi (i.e. those who still chose to identify with their locality). At this point Mr. Kamusella moves into the area of linguistics. While traditionally historians have spoken of the conflicts between the three national languages (German, Polish and Czech), Mr Kamusella reminds us that the standardised forms of these languages, which we choose to dub "national", were developed only in the mid-18th century, after 1869 (when Polish became the official language in Galicia), and after the 1870s (when Czech became the official language in Bohemia). As for standard German, it was only widely promoted in Silesia from the mid 19th century onwards. In fact, the majority of the population of Prussian Upper Silesia and Austrian Silesia were bi- or even multilingual. What is more, the "Polish" and "Czech" Silesians spoke were not the standard languages we know today, but a continuum of West-Slavic dialects in the countryside and a continuum of West-Slavic/German creoles in the urbanised areas. Such was the linguistic confusion that, from time to time, some ethnic/regional and Church activists strove to create a distinctive Upper Silesian/Silesian language on the basis of these dialects/creoles, but their efforts were thwarted by the staunch promotion of standard German, and after 1918, of standard Polish and Czech. Still on the subject of language, Mr. Kamusella draws attention to a problem around the issue of place names and personal names. Polish historians use current Polish versions of the Silesian place names, Czechs use current Polish/Czech versions of the place names, and Germans use the German versions which were in use in Silesia up to 1945. Mr. Kamusella attempted to avoid this, as he sees it, nationalist tendency, by using an appropriate version of a place name for a given period and providing its modern counterpart in parentheses. In the case of modern place names he gives the German version in parentheses. As for the name of historical figures, he strove to use the name entered on the birth certificate of the person involved, and by doing so avoid such confusion as, for instance, surrounds the Austrian Silesian pastor L.J. Sherschnik, who in German became Scherschnick, in Polish, Szersznik, and in Czech, Sersnik. Indeed, the prospective Silesian scholar should, Mr. Kamusella suggests, as well as the three languages directly involved in the area itself, know English and French, since many documents and books on the subject have been published in these languages, and even Latin, when dealing in depth with the period before the mid-19th century. Mr. Kamusella divides the policies of ethnic cleansing into two categories. The first he classifies as soft, meaning that policy is confined to the educational system, army, civil service and the church, and the aim is that everyone learn the language of the dominant group. The second is the group of hard policies, which amount to what is popularly labelled as ethnic cleansing. This category of policy aims at the total assimilation and/or physical liquidation of the non-dominant groups non-congruent with the ideal of homogeneity of a given nation-state. Mr. Kamusella found that soft policies were consciously and systematically employed by Prussia/Germany in Prussian Silesia from the 1860s to 1918, whereas in Austrian Silesia, Vienna quite inconsistently dabbled in them from the 1880s to 1917. In the inter-war period, the emergence of the nation-states of Poland and Czechoslovakia led to full employment of the soft policies and partial employment of the hard ones (curbed by the League of Nations minorities protection system) in Czechoslovakian Silesia, German Upper Silesia and the Polish parts of Upper and Austrian Silesia. In 1939-1945, Berlin started consistently using all the "hard" methods to homogenise Polish and Czechoslovakian Silesia which fell, in their entirety, within the Reich's borders. After World War II Czechoslovakia regained its prewar part of Silesia while Poland was given its prewar section plus almost the whole of the prewar German province. Subsequently, with the active involvement and support of the Soviet Union, Warsaw and Prague expelled the majority of Germans from Silesia in 1945-1948 (there were also instances of the Poles expelling Upper Silesian Czechs/Moravians, and of the Czechs expelling Czech Silesian Poles/pro-Polish Silesians). During the period of communist rule, the same two countries carried out a thorough Polonisation and Czechisation of Silesia, submerging this region into a new, non-historically based administrative division. Democratisation in the wake of the fall of communism, and a gradual retreat from the nationalist ideal of the homogeneous nation-state with a view to possible membership of the European Union, caused the abolition of the "hard" policies and phasing out of the "soft" ones. Consequently, limited revivals of various ethnic/national minorities have been observed in Czech and Polish Silesia, whereas Silesian regionalism has become popular in the westernmost part of Silesia which remained part of Germany. Mr. Kamusella believes it is possible that, with the overcoming of the nation-state discourse in European politics, when the expression of multiethnicity and multilingualism has become the cause of the day in Silesia, regionalism will hold sway in this region, uniting its ethnically/nationally variegated population in accordance with the principle of subsidiarity championed by the European Union.

[Head movements during simulated direct digital radiography]

The aim of this study was to simulate direct-digital cephalometric procedures and to record the head movements of probands. This study was prompted by the Committee for Insurance Matters of the Swiss National Invalidity Insurance which does not accept scanned digital cephalometric radiographs as a basis for its decisions. The reason for this is the required scanning time of several seconds during which even slight head movements can lead to kinetic blurring and landmark displacement. Incorrect angular measurements may result. By means of a Sirognathograph and a cephalostat of non-ferromagnetic material, the head movements of a total of 264 subjects were recorded in three dimensions, with a scanning time of up to 25 seconds. In a second series, the influence of a chin support to reduce head movements was also tested. The results of the first series of tests showed that, with an increasing scan time, movements became greater, mostly in the sagittal plane, and that maximum displacements could occur already at the start of the recording. With a scan time of 10 seconds the median movement amplitude in the vertical dimension was 2.14 mm. The second series of tests revealed a significant reduction in head movements in all dimensions owing to an additional stabilizing chin support. To minimize head movements, scanning times must be reduced and additional head stabilizing elements together with existing ones are necessary.

Rhyming the National Spirit: Taras Shevchenko and Ilia Chavchavadze

The paper is a comparative inquiry into the roles of Ilia Chavchavadze (1837-1907) and Taras Shevchenko (1818-1861) as national poets and anti-colonial (anti-Tsarist) intellectuals within the context of their respective national traditions (Georgia and Ukraine). During the period of their activity (19th and the beginning of 20th century) both Ukraine and Georgia were under Tsarist imperial rule, albeit the two poets lived in different periods of Russian empire history. Through their major works, each called on their communities to ‘awaken’ and ‘revolt’ against oppression, rejected social apathy caused by Tsarist subjugation and raised awareness about the historical past of their nations. The non-acceptance of present and belief in an independent future was one of the dominant themes in the poetry and prose of both. Their contemporary importance is illustrated in political discourse both after Orange Revolution in Ukraine (2004), and Rose Revolution in Georgia (2003) where both poets are referred “as founding fathers of national ideology”, the history textbooks alluding to them as “symbols of anti-colonial resistance”. To this day, however, there has been surprisingly little academic writing in the West endeavoring to compare the works and activities of the two poets and their impact on national mobilization in Tsarist Ukraine and Georgia, even though their countries are often mentioned in a same breath by commentators on contemporary culture and politics. The paper attempts to fill this gap and tries to understand the relationship between literature and social mobilization in 19th century Russian Empire. By reflecting on Taras Shevchenko’s and Ilia Chavchavadze’s poetry, prose and social activism, I will try to explain how in different periods of Russian imperial history, the two poets helped to develop a modern form of political belonging among their compatriots and stimulated an anti-colonial mobilization with different political outcomes. To theorize on the role of poets and novelists in anti-colonial national movement, I will reflect on the writings of Benedict Anderson (1991), John Hutchinson (1994; 1999), Rory Finnin (2005; 2011) and problematize Miroslav Hroch’s (1996) three phase model of the development of national movements. Overall, the paper would aim to show the importance of, what John Hutchinson called, ‘cultural nationalists’ in understanding contemporary nationalist discourse in Georgian and Ukrainian societies.

Las Fuerzas Armadas Revolucionarias : Orígenes y desarrollo de una particular conjunción entre marxismo, peronismo y lucha armada [1960-1973]

Desde mediados de la década del cincuenta hasta la última dictadura militar, la Argentina vivió un período de gran conflictividad social y política. Particularmente desde el Cordobazo de 1969, amplios sectores de la clase trabajadora, el campo cultural, la iglesia y el movimiento estudiantil protagonizaron un intenso proceso de politización, dando lugar a un conjunto de movimientos de oposición de diverso orden. Las organizaciones armadas, al desafiar el monopolio estatal de la violencia legítima y establecer diversos lazos con el movimiento de protesta social más amplio, fueron uno de los actores destacados de ese proceso. Entre ellas, las 'Fuerzas Armadas Revolucionarias' [FAR] condensan varias problemáticas de relevancia en el período: el proceso de identificación con el peronismo de numerosos sectores de izquierda, la reivindicación de la violencia como forma de intervención política y la opción por la lucha armada como modalidad específica de ponerla en práctica. Pese a su importancia, hasta el momento no se había realizado ningún trabajo académico específico sobre esta organización. La presente tesis analiza los orígenes y el desarrollo de las FAR considerando el período que va desde los primeros sesenta, en que comenzaron a perfilarse sus grupos fundadores, hasta las elecciones presidenciales del 11 de marzo de 1973. Desde entonces no sólo cambia notablemente la dinámica política nacional, sino que la realidad de la organización ya está signada por el proceso de fusión con Montoneros, que fue anunciada de modo público en octubre de ese año. El problema de investigación articula dos ejes analíticos. Por un lado, el proceso de identificación de las FAR con el peronismo, cuyos antecedentes se remontan a las sucesivas reinterpretaciones realizadas por sus grupos fundadores sobre el fenómeno. El segundo, con su dinámica de funcionamiento como organización político-militar de actuación nacional y urbana, gestada al calor de los cambios de estrategias que se plantearon aquellos grupos fundadores para lograr el proceso de liberación nacional y social que impulsaban. Ambas líneas de análisis implican, además, adentrarse en los modos en que la organización concibió sus vínculos con sectores más amplios de la sociedad, particularmente con aquellos que buscaba movilizar. Para realizar la tesis se apeló a una estrategia metodológica cualitativa. Se relevaron fuentes escritas [diarios y revistas de alcance nacional, documentos de las FAR y de otras organizaciones con que se vincularon] y se realizaron entrevistas semiestructuradas a ex-miembros de la organización

Las Fuerzas Armadas Revolucionarias : Orígenes y desarrollo de una particular conjunción entre marxismo, peronismo y lucha armada [1960-1973]

Desde mediados de la década del cincuenta hasta la última dictadura militar, la Argentina vivió un período de gran conflictividad social y política. Particularmente desde el Cordobazo de 1969, amplios sectores de la clase trabajadora, el campo cultural, la iglesia y el movimiento estudiantil protagonizaron un intenso proceso de politización, dando lugar a un conjunto de movimientos de oposición de diverso orden. Las organizaciones armadas, al desafiar el monopolio estatal de la violencia legítima y establecer diversos lazos con el movimiento de protesta social más amplio, fueron uno de los actores destacados de ese proceso. Entre ellas, las 'Fuerzas Armadas Revolucionarias' [FAR] condensan varias problemáticas de relevancia en el período: el proceso de identificación con el peronismo de numerosos sectores de izquierda, la reivindicación de la violencia como forma de intervención política y la opción por la lucha armada como modalidad específica de ponerla en práctica. Pese a su importancia, hasta el momento no se había realizado ningún trabajo académico específico sobre esta organización. La presente tesis analiza los orígenes y el desarrollo de las FAR considerando el período que va desde los primeros sesenta, en que comenzaron a perfilarse sus grupos fundadores, hasta las elecciones presidenciales del 11 de marzo de 1973. Desde entonces no sólo cambia notablemente la dinámica política nacional, sino que la realidad de la organización ya está signada por el proceso de fusión con Montoneros, que fue anunciada de modo público en octubre de ese año. El problema de investigación articula dos ejes analíticos. Por un lado, el proceso de identificación de las FAR con el peronismo, cuyos antecedentes se remontan a las sucesivas reinterpretaciones realizadas por sus grupos fundadores sobre el fenómeno. El segundo, con su dinámica de funcionamiento como organización político-militar de actuación nacional y urbana, gestada al calor de los cambios de estrategias que se plantearon aquellos grupos fundadores para lograr el proceso de liberación nacional y social que impulsaban. Ambas líneas de análisis implican, además, adentrarse en los modos en que la organización concibió sus vínculos con sectores más amplios de la sociedad, particularmente con aquellos que buscaba movilizar. Para realizar la tesis se apeló a una estrategia metodológica cualitativa. Se relevaron fuentes escritas [diarios y revistas de alcance nacional, documentos de las FAR y de otras organizaciones con que se vincularon] y se realizaron entrevistas semiestructuradas a ex-miembros de la organización

Las Fuerzas Armadas Revolucionarias : Orígenes y desarrollo de una particular conjunción entre marxismo, peronismo y lucha armada [1960-1973]

Desde mediados de la década del cincuenta hasta la última dictadura militar, la Argentina vivió un período de gran conflictividad social y política. Particularmente desde el Cordobazo de 1969, amplios sectores de la clase trabajadora, el campo cultural, la iglesia y el movimiento estudiantil protagonizaron un intenso proceso de politización, dando lugar a un conjunto de movimientos de oposición de diverso orden. Las organizaciones armadas, al desafiar el monopolio estatal de la violencia legítima y establecer diversos lazos con el movimiento de protesta social más amplio, fueron uno de los actores destacados de ese proceso. Entre ellas, las 'Fuerzas Armadas Revolucionarias' [FAR] condensan varias problemáticas de relevancia en el período: el proceso de identificación con el peronismo de numerosos sectores de izquierda, la reivindicación de la violencia como forma de intervención política y la opción por la lucha armada como modalidad específica de ponerla en práctica. Pese a su importancia, hasta el momento no se había realizado ningún trabajo académico específico sobre esta organización. La presente tesis analiza los orígenes y el desarrollo de las FAR considerando el período que va desde los primeros sesenta, en que comenzaron a perfilarse sus grupos fundadores, hasta las elecciones presidenciales del 11 de marzo de 1973. Desde entonces no sólo cambia notablemente la dinámica política nacional, sino que la realidad de la organización ya está signada por el proceso de fusión con Montoneros, que fue anunciada de modo público en octubre de ese año. El problema de investigación articula dos ejes analíticos. Por un lado, el proceso de identificación de las FAR con el peronismo, cuyos antecedentes se remontan a las sucesivas reinterpretaciones realizadas por sus grupos fundadores sobre el fenómeno. El segundo, con su dinámica de funcionamiento como organización político-militar de actuación nacional y urbana, gestada al calor de los cambios de estrategias que se plantearon aquellos grupos fundadores para lograr el proceso de liberación nacional y social que impulsaban. Ambas líneas de análisis implican, además, adentrarse en los modos en que la organización concibió sus vínculos con sectores más amplios de la sociedad, particularmente con aquellos que buscaba movilizar. Para realizar la tesis se apeló a una estrategia metodológica cualitativa. Se relevaron fuentes escritas [diarios y revistas de alcance nacional, documentos de las FAR y de otras organizaciones con que se vincularon] y se realizaron entrevistas semiestructuradas a ex-miembros de la organización

Effects of different swimming race constraints on turning movements

The aim of this study was to investigate the effects of different swimming race constraints on the evolution of turn parameters. One hundred and fifty-eight national and regional level 200-m (meters) male swimming performances were video-analyzed using the individualized-distance model in the Open Comunidad de Madrid tournament. Turn (p < .001, ES = 0.36) and underwater distances (p < .001, ES = 0.38) as well as turn velocity (p < .001, ES = 0.69) significantly dropped throughout the race, although stroke velocity and underwater velocity were maintained in the last lap of the race (p > .05). Higher expertise swimmers obtained faster average velocities and longer distances in all the turn phases (p < .001, ES = 0.59), except the approach distance. In addition, national level swimmers showed the ability to maintain most of the turn parameters throughout the race, which assisted them in improving average velocity at the end of races. Therefore, the variations in the turning movements of a swimming race were expertise-related and focused on optimizing average velocity. Turning skills should be included in the swimming race action plan.

CONSOLIDAÇÃO OU MUDANÇA? UMA ANÁLISE FEMINISTA DA PASTORAL DA CRIANÇA

O objetivo central desta tese é investigar o potencial de transformação social da organização não-governamental, ligada a CNBB(Confederação Nacional dos Bispos do Brasil).- Pastoral da Criança - para a libertação de mulheres que lá atuam, das relações de dominação e opressões inerentes ao contexto kyriarchal. Esta pesquisa procura considerar o espaço religioso subjacente à organização em decorrência das influências das CEBs (Comunidades Eclesiais de Base) e do MRCC (Movimento de Renovação Católica Carismática). É feita pesquisa de campo na região de Curitiba com observações e entrevistas semi-estruturadas com doze mulheres atuando na Pastoral da Criança, valorizando-se a relação intersubjetiva entre pesquisadora e pessoas envolvidas na pesquisa. A análise qualitativa de dados em relação ao marco teórico feminista desenvolvido em Ciências Sociais pela sociologia, psicanálise e também a teologia, mostra o discurso das representações sociais das mulheres envolvidas, a percepção de suas próprias identidades e a importância da organização na construção de suas vidas. Nos traz a conclusão que a organização reproduz o perfil tradicional de mulheres na função materna e facilita a formação de redes comunitárias. Averigua-se que a Pastoral da Criança está vinculada ao sistema neoliberal de pensamento que reproduz os discursos de dominação do sistema kyriarchal da hierarquia da Igreja Católica e da medicina higienista. Essas instituições de apropriam da vida e dos corpos das mulheres e os reduzem às suas funções meramente biológicas, reprodutivas e de cuidados. A Pastoral da Criança é caracterizada por atividades que não consideram as causas estruturais da pobreza, mas apenas tentam amenizar os seus efeitos e conseqüências. Em suas capacitações, a organização usa a forma bancária de educação que reproduz as relações de dominação e dependência de mulheres pobres. A organização, mesmo com a estrutura da ideologia religiosa analisada, não está vinculada sistematicamente em um espaço religioso. Sugere-se em relação à situação da organização, a abertura das idéias e valores feministas nos campos da saúde e religião a fim de promover a libertação e empoderamento reais de mulheres pobres. Esta recomendação está ligada com a abertura, a necessidade de reflexão e de conhecimento, mostradas pelas mulheres entrevistadas durante a pesquisa de campo. Considera-se como limitação aos resultados da pesquisa, o local pesquisado por não ter influências de movimentos sociais.(AU)

Morphogenetic movements at gastrulation require the SH2 tyrosine phosphatase Shp2

The SH2 domain-containing tyrosine phosphatase Shp2 plays a pivotal role during the gastrulation of vertebrate embryos. However, because of the complex phenotype observed in mouse mutant embryos, the precise role of Shp2 during development is unclear. To define the specific functions of this phosphatase, Shp2 homozygous mutant embryonic stem cells bearing the Rosa-26 LacZ transgene were isolated and used to perform a chimeric analysis. Here, we show that Shp2 mutant cells amass in the tail bud of embryonic day 10.5 chimeric mouse embryos and that this accumulation begins at the onset of gastrulation. At this early stage, Shp2 mutant cells collect in the primitive streak of the epiblast and thus show deficiencies in their contribution to the mesoderm lineage. In high-contribution chimeras, we show that overaccumulation of Shp2 mutant cells at the posterior end of the embryo results in two abnormal phenotypes: spina bifida and secondary neural tubes. Consistent with a failure to undergo morphogenic movements at gastrulation, Shp2 is required for embryo fibroblast cells to mount a positive chemotactic response to acidic fibroblast growth factor in vitro. Our results demonstrate that Shp2 is required at the initial steps of gastrulation, as nascent mesodermal cells form and migrate away from the primitive streak. The aberrant behavior of Shp2 mutant cells at gastrulation may result from their inability to properly respond to signals initiated by fibroblast growth factors.

Dynamic characteristics and adaptability of mouse vestibulo-ocular and optokinetic response eye movements and the role of the flocculo-olivary system revealed by chemical lesions

The dynamic characteristics of reflex eye movements were measured in two strains of chronically prepared mice by using an infrared television camera system. The horizontal vestibulo-ocular reflex (HVOR) and horizontal optokinetic response (HOKR) were induced by sinusoidal oscillations of a turntable, in darkness, by 10° (peak to peak) at 0.11–0.50 Hz and of a checked-pattern screen, in light, by 5–20°at 0.11–0.17 Hz, respectively. The gains and phases of the HVOR and HOKR of the C57BL/6 mice were nearly equivalent to those of rabbits and rats, whereas the 129/Sv mice exhibited very low gains in the HVOR and moderate phase lags in the HOKR, suggesting an inherent sensory-motor anomaly. Adaptability of the HOKR was examined in C57BL/6 mice by sustained screen oscillation. When the screen was oscillated by 10° at 0.17 Hz, which induced sufficient retinal slips, the gain of the HOKR increased by 0.08 in 1 h on average, whereas the stimuli that induced relatively small or no retinal slips affected the gain very little. Lesions of the flocculi induced by local applications of 0.1% ibotenic acid and lesions of the inferior olivary nuclei induced by i.p. injection of 3-acetylpyridine in C57BL/6 mice little affected the dynamic characteristics of the HVOR and HOKR, but abolished the adaptation of the HOKR. These results indicate that the olivo-floccular system plays an essential role in the adaptive control of the ocular reflex in mice, as suggested in other animal species. The data presented provide the basis for analyzing the reflex eye movements of genetically engineered mice.

Centrosome positioning and directionality of cell movements

In several cell types, an intriguing correlation exists between the position of the centrosome and the direction of cell movement: the centrosome is located behind the leading edge, suggesting that it serves as a steering device for directional movement. A logical extension of this suggestion is that a change in the direction of cell movement is preceded by a reorientation, or shift, of the centrosome in the intended direction of movement. We have used a fusion protein of green fluorescent protein (GFP) and γ-tubulin to label the centrosome in migrating amoebae of Dictyostelium discoideum, allowing us to determine the relationship of centrosome positioning and the direction of cell movement with high spatial and temporal resolution in living cells. We find that the extension of a new pseudopod in a migrating cell precedes centrosome repositioning. An average of 12 sec elapses between the initiation of pseudopod extension and reorientation of the centrosome. If no reorientation occurs within approximately 30 sec, the pseudopod is retracted. Thus the centrosome does not direct a cell’s migration. However, its repositioning stabilizes a chosen direction of movement, most probably by means of the microtubule system.

Movements of truncated kinesin fragments with a short or an artificial flexible neck

To investigate the role of the neck domain of kinesin, we used optical trapping nanometry to perform high-resolution measurements of the movements and forces produced by recombinant kinesin fragments in which the neck domains were shortened or replaced by an artificial random coil. Truncated kinesin fragments (K351) that contain a motor domain consisting of ≈340 aa and a short neck domain consisting of ≈11 aa showed fast movement (800 nm/s) and 8-nm steps. Such behavior was similar to that of recombinant fragments containing the full-length neck domain (K411) and to that of native kinesin. Kinesin fragments lacking the short neck domain (K340), however, showed very slow movement (<50 nm/s), as previously reported. Joining an artificial 11-aa sequence that was expected to form a flexible random chain to the motor domain (K340–chain) produced normal fast (≈700 nm/s) and stepwise movement. The results suggest that the neck domain does not act as a rigid lever arm to magnify the structural change at the catalytic domain as has been believed for myosin, but it does act as a flexible joint to guarantee the mobility of the motor domain.

Active hair-bundle movements can amplify a hair cell’s response to oscillatory mechanical stimuli

To enhance their mechanical sensitivity and frequency selectivity, hair cells amplify the mechanical stimuli to which they respond. Although cell-body contractions of outer hair cells are thought to mediate the active process in the mammalian cochlea, vertebrates without outer hair cells display highly sensitive, sharply tuned hearing and spontaneous otoacoustic emissions. In these animals the amplifier must reside elsewhere. We report physiological evidence that amplification can stem from active movement of the hair bundle, the hair cell’s mechanosensitive organelle. We performed experiments on hair cells from the sacculus of the bullfrog. Using a two-compartment recording chamber that permits exposure of the hair cell’s apical and basolateral surfaces to different solutions, we examined active hair-bundle motion in circumstances similar to those in vivo. When the apical surface was bathed in artificial endolymph, many hair bundles exhibited spontaneous oscillations of amplitudes as great as 50 nm and frequencies in the range 5 to 40 Hz. We stimulated hair bundles with a flexible glass probe and recorded their mechanical responses with a photometric system. When the stimulus frequency lay within a band enclosing a hair cell’s frequency of spontaneous oscillation, mechanical stimuli as small as ±5 nm entrained the hair-bundle oscillations. For small stimuli, the bundle movement was larger than the stimulus. Because the energy dissipated by viscous drag exceeded the work provided by the stimulus probe, the hair bundles powered their motion and therefore amplified it.

Evidence for the existence of a sulfonylurea-receptor-like protein in plants: Modulation of stomatal movements and guard cell potassium channels by sulfonylureas and potassium channel openers

Limitation of water loss and control of gas exchange is accomplished in plant leaves via stomatal guard cells. Stomata open in response to light when an increase in guard cell turgor is triggered by ions and water influx across the plasma membrane. Recent evidence demonstrating the existence of ATP-binding cassette proteins in plants led us to analyze the effect of compounds known for their ability to modulate ATP-sensitive potassium channels (K-ATP) in animal cells. By using epidermal strip bioassays and whole-cell patch-clamp experiments with Vicia faba guard cell protoplasts, we describe a pharmacological profile that is specific for the outward K+ channel and very similar to the one described for ATP-sensitive potassium channels in mammalian cells. Tolbutamide and glibenclamide induced stomatal opening in bioassays and in patch-clamp experiments, a specific inhibition of the outward K+ channel by these compounds was observed. Conversely, application of potassium channel openers such as cromakalim or RP49356 triggered stomatal closure. An apparent competition between sulfonylureas and potassium channel openers occurred in bioassays, and outward potassium currents, previously inhibited by glibenclamide, were partially recovered after application of cromakalim. By using an expressed sequence tag clone from an Arabidopsis thaliana homologue of the sulfonylurea receptor, a 7-kb transcript was detected by Northern blot analysis in guard cells and other tissues. Beside the molecular evidence recently obtained for the expression of ATP-binding cassette protein transcripts in plants, these results give pharmacological support to the presence of a sulfonylurea-receptor-like protein in the guard-cell plasma membrane tightly involved in the outward potassium channel regulation during stomatal movements.