Ferrocarril Viking : ¿corredor o interfaz?. Limitaciones técnicas de ambiciones estratégicas

El final de la Guerra Fría en 1991, propició el desarrollo de mercados internacionales a una escala nunca vista hasta entonces. En lo que respecta al espacio ex soviético, dado que era básicamente de entidad continental, se debía llegar a los mercados, principalmente por medio de comunicaciones terrestres. En las grandes extensiones del continente eurasiático las antiguas rutas comerciales fueron revitalizadas gracias a la capacidad de transporte y la competitividad del transporte ferroviario. El tren Viking, que une los puertos de Klaipeda, en Lituania, y Odesa (Ilyichevsk) en Ucrania, a través de territorio bielorruso, fue una de las empresas pensadas para aprovechar nuevos mercados a través de las rutas comerciales antiguas. El proyecto compitió para establecerse como una de las principales vías destinadas a aglutinar productos occidentales hacia mercados orientales y viceversa, reabriendo el antiguo eje que unía a Escandinavia y el Báltico con el Imperio bizantino. Sin embargo, diez años después de su puesta en marcha, parece evidente que los países asociados al proyecto Viking, víctimas de las limitaciones tecnológicas y geográficas, no supieron aprovechar la ocasión de consolidarlo y fortalecerse ante futuros competidores.El final de la Guerra freda de 1991, va propiciar el desenvolupament de mercats internacionals a una escala mai vista fins llavors. Pel que fa a l'espai ex soviètic, atès que era bàsicament de entitat continental, s'havia arribar als mercats, principalment per mitjà de comunicacions terrestres. A les grans extensions del continent eurasiàtic les antigues rutes comercials van ser revitalitzades gràcies a la capacitat de transport i la competitivitat del transport ferroviari. El tren Vicking, que uneix els ports de Kaipleda, Lituània, i Odessa (llychevsk) a Ucraïna, a través de territori bielorús, va ser una de les empreses pensades per aprofitar nous mercats a través de les rutes comercials antigues. El projecte va competir per establir-se com una de les principals vies destinades a aglutinar productes occidentals cap a mercats orientals i viceversa, reobrint l'antic eix que unia Escandinàvia i el Bàltic amb l'imperi Bizantí. No obstant això, deu anys després de la seva posada en marxa, sembla evident que els països associats al projecte Viking, víctimes de les limitacions tecnològiques i geogràfiques, no van saber aprofitar l'ocasió de consolidar-lo i enfortir-se davant de futurs competidors.Cold War's engame in 1991 widened the scope of world markets in an unseen scale, but being the sovietic space a continental entity, it was mainly through land routes how markets could be reached. In the huge expanses of the Eurasaian continent, old trade routes were revitalized thanks to the transport capacity and competitiveness of the railway transport. The Viking railway, linking the ports of Kaipeda in Lithuania and Odessa (Ilychevsk) in Ucraine through byelorussian territory, was one of the entrepreneurships launched to take adavantage of new markets throught old trade routes. By reopenning the old axis that linked Scandinavia and the Baltic to the Bizantine empire, the project vied to establish itself as one of the main routes syphoning western products to eastern markets and vice versa. However, ten years after the start up, it seems clear that countries associated with the Viking project, victims of technological and geographical constraints, failed to seize the opportunity to consolidate and strengthen futur competitors

Structural changes in mitochondria and CRUs.

<p><b>A</b> and <b>C.</b> The intermyofibrillar mitochondria (small black arrows) are predominantly located at the I-band, next to CRUs or triads (white arrows) on both sides of Z-lines (arrowheads). <b>B.</b> and <b>D.</b> Enlargements of CRUs next to intermyofibrillar mitochondria. The two organelles are tethered together by small electron-dense bridges (arrows), whereas the width (dotted lines) of the terminal cystenae is reduced in dCASQ-null relative to WT. <b>E.</b> and <b>F.</b> Subsarcolemmal mitochondria (arrows) in WT and dCASQ-null, respectively. The green band indicates the 1 μm-wide region where frequency and volume fraction of subsarcolemmal mitochondria were determined. Scale bars, A and C: 0.2 μm; B and D: 0.1 μm; E and F: 0.5 μm.</p

Average amplitudes of the increase in the YFP/CFP ratio (ΔR) during contractile activity.

<p>In the presence of 1²⁺, ΔR (after correction for bleaching) increased with stimulation frequency in the range from 1–20 Hz in both WT and dCASQ-null fibers. The increases in [Ca²⁺]_mito at 60 Hz were very similar to those at 20 Hz and the values reached were significantly smaller in dCASQ-null fibers than in WT fibers (** P<0.01). The averaged values in the absence of extracellular Ca²⁺ (-Ca) are smaller than the corresponding values in the presence of Ca²⁺, but the difference was not statistically significant (3-way ANOVA).</p

Effect mNCX blockade on the increase in [Ca²⁺]_mito during repetitive stimulation at 5 Hz.

<p><b>A.</b> The 4mtD3cpv response (YFP, red; CFP, blue; ratio YFP/CFP, green) recorded at low illumination intensity to avoid bleaching of the probe in a WT fiber in the presence of 1 mM extracellular Ca²⁺. <b>B.</b> Response obtained in the fiber in the presence of 1 μM CGP37157 (CGP: a selective mitochondrial Na⁺/Ca²⁺ exchanger blocker). In the inset a comparison is shown of the recordings +/− CGP37157 on an expanded time scale, illustrating that in the presence of CGP37157 [Ca²⁺]_mito rises faster and reaches a higher final level. This is consistent with blockage of mitochondrial efflux via the mNCX during the stimulation period (10 s).</p

Time course of the decline in [Ca²⁺]_mito.

<p><b>A.</b> Time course of the variations in YFP/CFP ratio (green) <i>during</i> a train of stimuli at 1 Hz in a WT fiber. The time averaged response of the final 16 responses of the 20 s train of stimuli after subtraction of the baseline is shown. The time averaged YFP signal (red) is shown a surrogate marker of mechanical activity. A double exponential was fitted to the YFP/CFP data points R(t) = a₀+a₁. exp (−k₁. t) + a₂exp (−k₂. t). The parameter values of the recording shown are: a₀ = 0.149, a₁ = 0.107, k₁ = 39.8 s⁻¹; a₂ = 0.068, k₂ = 1.15 s⁻¹. <b>B.</b> Recording of the final decay of the (baseline subtracted) YFP/CFP ratio <i>after</i> a stimulus train at a frequency of 1 Hz. The time course of the decrease in YFP/CFP ratio was dominated by a single exponential (in bright green): R(t) = a₃. exp (−k₃.t), with amplitude (a₃) and rate constant (k₃) of 0.175 and 0.21 s⁻¹, respectively.</p

Data are expressed as mean±SEM. *p<0.01, AQP4 KO vs WT.

<p>Data are expressed as mean±SEM. *p<0.01, AQP4 KO vs WT.</p

Parameter values of the exponential equations describing the recovery of [Ca²⁺]_mito during and after 1 Hz stimulation.

<p>Amplitude (a₁, a₂ and a₃) and rate constants (k₁, k₂ and k₃ in s⁻¹) of the recovery of [Ca²⁺]_mito during and after 1 Hz stimulation (n =  number of fibers). ^*P<0.05: (−Ca)-value vs. corresponding (+ Ca)-value (Bonferroni post-hoc test). ^¶Averaged rate constants of slow phase derived from all stimulation frequencies were type-dependent (P<0.05, see text).</p

Cytosolic Ca²⁺ concentration in electrically stimulated WT and dCASQ-null fibers.

<p><b>A.</b> At low frequency of stimulation (1 Hz) Fura-2 transients have comparable amplitudes in WT and dCASQ-null fibers and, due to their short duration, are intercalated by periods of low resting cytosolic Ca²⁺ levels. <b>B.</b> At high frequency of stimulation (60 Hz) transients are fused and Ca²⁺ concentration remains high in WT, while it declines after an initial peak in dCASQ-null fibers. <b>C.</b> Average values of peak cytosolic Ca²⁺ concentration probed by Fura-2 ratio at the end of stimulation trains at various stimulation frequency in WT, in the presence (triangles) or absence (circles) of extracellular Ca²⁺.</p

Localization of 4mtD3cpv in FDB muscle fibers.

<p><b>A</b> and <b>C</b>: mitochondrial cameleon (4mtD3cpv) fluorescence (green) and anti-RyR antibody staining (red) in a merged image (A) and intensity profiles (C). <b>B</b> and <b>D</b>: mitochondrial cameleon (4mtD3cpv) fluorescence (green) and anti-Tom20 antibody staining (red) in a merged image (B) and intensity profiles (D). Segments 10 μm long were scanned on the images as indicated by the white bars.</p

Changes in Ca²⁺ concentration in the mitochondrial matrix ([Ca²⁺]_mito) during repetitive stimulation.

<p>The 4mtD3cpv responses (YFP, red; CFP, blue; YFP/CFP ratio, green) are shown in a WT fiber (<b>A</b>) and in dCASQ-null fiber (<b>B</b>) at 1 Hz, 5 Hz, 20 Hz and 60 Hz in the presence of 1 mM extracellular Ca²⁺. The YFP/CFP ratio is a measure of the free [Ca²⁺]_mito. During stimulation at 1 Hz, the pulsatile increase in free [Ca²⁺]_mito during each contraction can be identified; at higher stimulation frequencies the free [Ca²⁺]_mito increases more smoothly during the train of stimuli. After the train of stimuli the [Ca²⁺]_mito signal returned to baseline (indicated by the dotted line in the WT recording at 1 Hz). The increase in the YFP/CFP ratio relative to the baseline (ΔR), indicated by the double sided arrow, is a measure of the increase in [Ca²⁺]_mito during the train of stimuli. In the YFP signal, rapid increases in intensity can be observed, partly caused by repetitive contractions of the fiber (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0074919#pone.0074919.s001" target="_blank">File S1</a>).</p