Giant Vesicles under Oxidative Stress Induced by a Membrane-Anchored Photosensitizer

We have synthesized the amphiphile photosensitizer PE-porph consisting of a porphyrin bound to a lipid headgroup. We studied by optical microscopy the response to light irradiation of giant unilamellar vesicles of mixtures of unsaturated phosphatidylcholine lipids and PE-porph. In this configuration, singlet oxygen is produced at the bilayer surface by the anchored porphyrin. Under irradiation, the PE-porph decorated giant unilamellar vesicles exhibit a rapid increase in surface area with concomitant morphological changes. We quantify the surface area increase of the bilayers as a function of time and photosensitizer molar fraction. We attribute this expansion to hydroperoxide formation by the reaction of the singlet oxygen with the unsaturated bonds. Considering data from numeric simulations of relative area increase per phospholipid oxidized (15%), we measure the efficiency of the oxidative reactions. We conclude that for every 270 singlet oxygen molecules produced by the layer of anchored porphyrins, one eventually reacts to generate a hydroperoxide species. Remarkably, the integrity of the membrane is preserved in the full experimental range explored here, up to a hydroperoxide content of 60%, inducing an 8% relative area expansion.     

Phylogeographic patterns in Hypochaeris section Hypochaeris (Asteraceae, Lactuceae) of the western Mediterranean

Aim  To analyse phylogeographic patterns in the four species of Hypochaeris sect. Hypochaeris , evaluating possible areas of origin and the microevolutionary processes that have shaped their morphology, genetics and distribution.
Location  Western Mediterranean area.
Methods  We applied amplified fragment length polymorphism (AFLP) markers to a total of 494 individuals belonging to 82 populations of Hypochaeris arachnoidea , H. glabra , H. radicata and H. salzmanniana to determine population structure.
Results  Populations with the largest proportion of private and rare AFLP fragments were found in Morocco. This region was consequently inferred to be the ancestral area for H. arachnoidea , H. glabra , H. radicata and H. salzmanniana . The Guadalquivir River (southern Spain) was inferred to be an effective dispersal barrier for H. glabra and H. radicata. The Strait of Gibraltar was inferred to be a somewhat weaker barrier than the Guadalquivir River for H. radicata and a much weaker barrier for H. glabra . The main barrier for H. salzmanniana coincides with the extension of the Rif Mountains to the Atlantic coast in Morocco, and the Strait of Gibraltar is a much weaker barrier for this species. Hypochaeris arachnoidea appears to have originated in the Atlas Mountains.
Main conclusions  The highest levels of genetic variation in La Mamora forest ( H. glabra and H. salzmanniana ) or the adjacent central Middle Atlas ( H. arachnoidea and H. radicata ) in Morocco suggest that these areas were a centre of origin of Hypochaeris sect. Hypochaeris . All three potential barriers – the Guadalquivir River, the Strait of Gibraltar, and the Rif Mountains – have been important in shaping genetic diversity in species of section Hypochaeris .     

Glutamate receptors modulate sodium-dependent and calcium-independent vitamin C bidirectional transport in cultured avian retinal cells

Vitamin C is transported in the brain by sodium vitamin C co‐transporter 2 (SVCT‐2) for ascorbate and glucose transporters for dehydroascorbate. Here we have studied the expression of SVCT‐2 and the uptake and release of [¹⁴C] ascorbate in chick retinal cells. SVCT‐2 immunoreactivity was detected in rat and chick retina, specially in amacrine cells and in cells in the ganglion cell layer. Accordingly, SVCT‐2 was expressed in cultured retinal neurons, but not in glial cells. [¹⁴C] ascorbate uptake was saturable and inhibited by sulfinpyrazone or sodium‐free medium, but not by treatments that inhibit dehydroascorbate transport. Glutamate‐stimulated vitamin C release was not inhibited by the glutamate transport inhibitor l ‐β‐threo‐benzylaspartate, indicating that vitamin C release was not mediated by glutamate uptake. Also, ascorbate had no effect on [³H] d ‐aspartate release, ruling out a glutamate/ascorbate exchange mechanism. 2‐Carboxy‐3‐carboxymethyl‐4‐isopropenylpyrrolidine (Kainate) or NMDA stimulated the release, effects blocked by their respective antagonists 6,7‐initroquinoxaline‐2,3‐dione (DNQX) or (5R,2S)‐(1)‐5‐methyl‐10,11‐dihydro‐5H‐dibenzo[a,d]cyclohepten‐5,10‐imine hydrogen maleate (MK‐801). However, DNQX, but not MK‐801 or 2‐amino‐5‐phosphonopentanoic acid (APV), blocked the stimulation by glutamate. Interestingly, DNQX prevented the stimulation by NMDA, suggesting that the effect of NMDA was mediated by glutamate release and stimulation of non‐NMDA receptors. The effect of glutamate was neither dependent on external calcium nor inhibited by 1,2‐bis (2‐aminophenoxy) ethane‐N′,N′,N′,N′,‐tetraacetic acid tetrakis (acetoxy‐methyl ester) (BAPTA‐AM), an internal calcium chelator, but was inhibited by sulfinpyrazone or by the absence of sodium. In conclusion, retinal cells take up and release vitamin C, probably through SVCT‐2, and the release can be stimulated by NMDA or non‐NMDA glutamate receptors.     

Studies on woloszynskioid dinoflagellates IV: The genus Biecheleria gen. nov.

The well known freshwater dinoflagellate Woloszynskia pseudopalustris is transferred to the new genus Biecheleria , based on the very unusual structure of the eyespot (comprising a stack of cisternae), the apical apparatus of a single elongate amphiesma vesicle, the structure of the resting cyst, and molecular data. Biecheleria is phylogenetically related to Symbiodinium and Polarella of the family Suessiaceae. This family, which extends back to the Jurassic, is redefined with the eyespot (Type E sensu Moestrup and Daugbjerg) and apical apparatus as diagnostic features, unknown elsewhere in the dinoflagellates. Biecheleria also comprises the brackish water species Biecheleria baltica sp. nov. (presently identified as Woloszynskia halophila ) and the marine species Biecheleria natalensis (syn. Gymnodinium natalense ). Gymnodinium halophilum described in 1952 by B. Biecheler but apparently not subsequently refound, is transferred to Biecheleria . The Suessiaceae further includes the marine species Protodinium simplex , described by Lohmann in 1908 but shortly afterwards (1921) transferred to Gymnodinium by Kofoid and Swezy and subsequently known as Gymnodinium simplex . It only distantly related to Gymnodinium . A new family, the Borghiellaceae, is proposed for the sister group to the Suessiaceae, based on eyespot structure (Type B of Moestrup and Daugbjerg), the morphology of the apical apparatus (if present), and molecular data. It presently comprises the genera Baldinia and Borghiella . Cells of Biecheleria pseudopalustris and B. baltica contain a microtubular strand (msp) associated with vesicles containing opaque material. Such structures are known in other dinoflagellates to serve as a peduncle, indicating that the two species may be mixotrophic.     

Gene expression profiling predicts a three-gene expression signature of endometrial adenocarcinoma in a rat model

Background  

In the Western world, endometrial cancers are the most common gynaecological neoplastic disorders among women. Initial symptoms are often vague and may be confused with several other conditions or disorders. Thus, there is a need for an easy and reliable diagnostic tool. The objective of this work was to identify a gene expression signature specific for endometrial adenocarcinomas to be used for testing potential endometrial biomarkers.     

Pathogenesis of tendinopathies: inflammation or degeneration?

The intrinsic pathogenetic mechanisms of tendinopathies are largely unknown and whether inflammation or degeneration has the prominent role is still a matter of debate. Assuming that there is a continuum from physiology to pathology, overuse may be considered as the initial disease factor; in this context, microruptures of tendon fibers occur and several molecules are expressed, some of which promote the healing process, while others, including inflammatory cytokines, act as disease mediators. Neural in-growth that accompanies the neovessels explains the occurrence of pain and triggers neurogenic-mediated inflammation. It is conceivable that inflammation and degeneration are not mutually exclusive, but work together in the pathogenesis of tendinopathies.     

mRuby,a Bright Monomeric Red Fluorescent Protein for Labeling of Subcellular Structures

A monomeric variant of the red fluorescent protein eqFP611, mRuby, is described. With excitation and emission maxima at 558 nm and 605 nm, respectively, and a large Stokes shift of 47 nm, mRuby appears particularly useful for imaging applications. The protein shows an exceptional resistance to denaturation at pH extremes. Moreover, mRuby is about ten-fold brighter compared to EGFP when being targeted to the endoplasmic reticulum. The engineering process of eqFP611 revealed that the C-terminal tail of the protein acts as a natural peroxisomal targeting signal (PTS). Using an mRuby variant carrying the eqFP611-PTS, we discovered that ordered inheritance of peroxisomes is widespread during mitosis of different mammalian cell types. The ordered partitioning is realized by the formation of peroxisome clusters around the poles of the mitotic spindle and ensures that equal numbers of the organelle are inherited by the daughter cells. The unique spectral properties make mRuby the marker of choice for a multitude of cell biological applications. Moreover, the use of mRuby has allowed novel insights in the biology of organelles responsible for severe human diseases.     

Prospective Study of Chikungunya Virus Acute Infection in the Island of La Réunion during the 2005–2006 Outbreak

Background

Chikungunya virus (CHIKV) is a recently re-emerged arthropod borne virus responsible for a massive outbreak in the Indian Ocean and India, and extended to Southeast Asia as well as Italy. CHIKV has adapted to Aedes albopictus, an anthropophilic mosquito species widely distributed in Asia, Europe, Africa and America. Our objective was to determine the clinical and biological features of patients at the acute phase of CHIKV infection.

Methods and Findings

A prospective study enrolled 274 consecutive patients with febrile arthralgia recorded at the Emergency Department of the Groupe Hospitalier Sud-Réunion between March and May 2006. Three groups were defined: one group of 180 viremic patients (positive CHIKV RT-PCR), one group of 34 patients with acute post-viremic infection (negative CHIKV RT-PCR, positive anti-CHIKV IgM and negative IgG), and one group of 46 uninfected patients (negative CHIKV RT-PCR, anti-CHIKV IgM and IgG). Bivariate analyses of clinical and biological features between groups were performed. Patients with CHIKV viremia presented typically with asymmetrical bilateral polyarthralgia (96.5%) affecting the lower (98%) and small joints (74.8%), as well as asthenia (88.6%), headache (70%), digestive trouble (63.3%), myalgia (59%), exanthems (47.8%), conjunctival hyperhemia (23%) and adenopathy (8.9%). Vertigo, cutaneous dysesthesia, pharyngitis and haemorrhages were seldom observed. So far unreported symptoms such as chondrocostal arthralgia (20%), entesopathies (1.6%), talalgia (14%) were also noted. Prurit was less frequent during the viremic than post-viremic phase (13.9% vs. 41.2%; p<0.001), whereas lymphopenia was more frequent (87.6% vs. 39.4%; p<0.001). Others biological abnormalities included leukopenia (38.3%), thrombocytopenia (37.3%), increased ASAT and ALAT blood levels (31.6 and 7.3%, respectively) and hypocalcemia (38.7%). Lymphopenia <1,000/mm³ was very closely associated with viremic patients (Yule coefficient 0.82, positive predictive value 92.3%). Age under 65 was associated with a benign course, as no patients younger than 65 had to be hospitalized (Yule coefficient 0.78).

Conclusions

The diagnosis of CHIKV infection in acute phase is based on commonly accepted clinical criteria (fever and arthralgia), however clinical and biological diffrences exist in acute phase depending on whether or not the patient is within the viremic phase of the infection.     

Regulation of apoptosis-associated lysosomal membrane permeabilization

Lysosomal membrane permeabilization (LMP) occurs in response to a large variety of cell death stimuli causing release of cathepsins from the lysosomal lumen into the cytosol where they participate in apoptosis signaling. In some settings, apoptosis induction is dependent on an early release of cathepsins, while under other circumstances LMP occurs late in the cell death process and contributes to amplification of the death signal. The mechanism underlying LMP is still incompletely understood; however, a growing body of evidence suggests that LMP may be governed by several distinct mechanisms that are likely engaged in a death stimulus- and cell-type-dependent fashion. In this review, factors contributing to permeabilization of the lysosomal membrane including reactive oxygen species, lysosomal membrane lipid composition, proteases, p53, and Bcl-2 family proteins, are described. Potential mechanisms to safeguard lysosomal integrity and confer resistance to lysosome-dependent cell death are also discussed.