Amplification of CRAC current by STIM1 and CRACM1 (Orai1)

Depletion of intracellular calcium stores activates store-operated calcium entry across the plasma membrane in many cells. STIM1, the putative calcium sensor in the endoplasmic reticulum, and the calcium release-activated calcium (CRAC) modulator CRACM1 (also known as Orai1) in the plasma membrane have recently been shown to be essential for controlling the store-operated CRAC current (I(CRAC)). However, individual overexpression of either protein fails to significantly amplify I(CRAC). Here, we show that STIM1 and CRACM1 interact functionally. Overexpression of both proteins greatly potentiates I(CRAC), suggesting that STIM1 and CRACM1 mutually limit store-operated currents and that CRACM1 may be the long-sought CRAC channel.     

Soybean ferritin: isolation, characterization, and free radical generation

The main aim of this work was to assess the multi-task role of ferritin(Ft)in the oxidative metabolism of soybean(Glycine max).Soybean seeds incubated for 24 h yielded 41 ± 5 μg Ft/g fresh weight.The rate of in vitro incorporation of iron(Fe)into Ft was tested by supplementing the reaction medium with physiological Fe chelators.The control rate,observed in the presence of 100 μM Fe,was not significantly different from the values observed in the presence of 100 μM Fe-his.However,it was significantly higher in the presence of 100 μM Fe-citrate(approximately 4.5-fold)or of 100 μM Fe-ATP(approximately 14-fold).Moreover,a substantial decrease in the Trp-dependent fluorescence of the Ft protein was determined during Fe uptake from Fe-citrate,as compared with the control.On the other hand,Ft addition to homogenates from soybean embryonic axes reduced endogenously generated ascorbyl radical,according to its capacity for Fe uptake.The data presented here suggest that Ft could be involved in the generation of free radicals,such as hydroxyl radical,by Fe-catalyzed reactions.Moreover,the scavenging of these radicals by Ft itself could then lead to protein damage.However,Ft could also prevent cellular damage by the uptake of catalytically active Fe.     

Population structure of North Atlantic and North Pacific sei whales (<Emphasis Type="Italic">Balaenoptera borealis</Emphasis>) inferred from mitochondrial control region DNA sequences and microsatellite genotypes

Currently, three stocks of sei whales (Balaenoptera borealis) are defined in the North Atlantic; the Nova Scotian, Iceland-Denmark Strait and Eastern North Atlantic stocks, which are mainly based upon historical catch and sighting data. We analyzed mitochondrial control region DNA (mtDNA) sequences and genotypes from 7 to 11 microsatellite loci in 87 samples from three sites in the North Atlantic; Iceland, the Gulf of Maine and the Azores, and compared against the North Pacific using 489 previously published samples. No statistically significant deviations from homogeneity were detected among the North Atlantic samples at mtDNA or microsatellite loci. The genealogy estimated from the mtDNA sequences revealed a clear division of the haplotypes into a North Atlantic and a North Pacific clade, with the exception of one haplotype detected in a single sample from the Azores, which was included in the North Pacific clade. Significant genetic divergence between the North Atlantic and North Pacific Oceans was detected (mtDNA Φ_ST?=?0.72, microsatellite Weir and Cockerham’s ? = 0.20; p?<?0.001). The coalescent-based estimate of the population divergence time between the North Atlantic and North Pacific populations from the sequence variation among the mtDNA sequences was at 163,000 years ago. However, the inference was limited by an absence of samples from the Southern Hemisphere and uncertainty regarding mutation rates and generation times. The estimates of inter-oceanic migration rates were low (Nm at 0.007 into the North Pacific and at 0.248 in the opposite direction). Although estimates of genetic divergence among the current North Atlantic stocks were low and consistent with the extensive range of movement observed in satellite tagged sei whales, the high uncertainty of the genetic divergence estimates precludes rejection of multiple stocks in the North Atlantic.