Zooplankton distribution in four ponds of different salinity: a seasonal study in the solar salterns of Sfax (Tunisia)

The seasonal distribution of metazooplankton and large-sized ciliates was studied in four ponds of different salinity in the solar salterns of Sfax (Tunisia). Total zooplankton abundance varied from 1 × 10³ to 4.7 × 10⁶ ind m^–3. Salinity had a negative effect on the abundance of copepods and rotifers which were absent in the pond with the highest salt concentration (180) in which the number of taxa was low and Artemia or the ciliate Fabrea largely dominated the zooplankton community. Temperature and the presence of Dunaliella salina as prey appeared as key factors in controlling the abundance of Artemia, while organic detritus appeared as important in the diet of Fabrea. Change in zooplankton species composition along the hypersaline gradient (40–90) was primarily related to salinity. However, our data suggest the importance of both the abundance and composition of food in the spatial and temporal variations of some zooplankton species.     

Reconstituted TOM core complex and Tim9/Tim10 complex of mitochondria are sufficient for translocation of the ADP/ATP carrier across membranes

Precursor proteins of the solute carrier family and of channel forming Tim components are imported into mitochondria in two main steps. First, they are translocated through the TOM complex in the outer membrane, a process assisted by the Tim9/Tim10 complex. They are passed on to the TIM22 complex, which facilitates their insertion into the inner membrane. In the present study, we have analyzed the function of the Tim9/Tim10 complex in the translocation of substrates across the outer membrane of mitochondria. The purified TOM core complex was reconstituted into lipid vesicles in which purified Tim9/Tim10 complex was entrapped. The precursor of the ADP/ATP carrier (AAC) was found to be translocated across the membrane of such lipid vesicles. Thus, these components are sufficient for translocation of AAC precursor across the outer membrane. Peptide libraries covering various substrate proteins were used to identify segments that are bound by Tim9/Tim10 complex upon translocation through the TOM complex. The patterns of binding sites on the substrate proteins suggest a mechanism by which portions of membrane-spanning segments together with flanking hydrophilic segments are recognized and bound by the Tim9/Tim10 complex as they emerge from the TOM complex into the intermembrane space.     

Biosynthesis of fattiviracin FV-8, an antiviral agent

Streptomyces microflavus strain No. 2445 produces many derivatives of fattiviracin antibiotics. The major product of these derivatives is fattiviracin FV-8, which consists of four glucose and two trihydroxy fatty acid residues. We found that this strain has the ability to convert several sugars in the culture medium to glucose, and the glucose added to the medium is directly incorporated into the FV-8 molecule. Two trihydroxy fatty acid residues in the FV-8 molecule are derived from acetic acid, and production of FV-8 is inhibited by the addition of cerulenin, which is an inhibitor of fatty acid biosynthesis.     

The development of a potential single photon emission computed tomography (SPECT) imaging agent for the corticotropin-releasing hormone receptor type

A high-affinity radioligand for CRHR1 has been prepared that can serve as a template for the development of SPECT imaging agents. The 5-chloro-N-cyclopropylmethyl-N-(2,6-dichloro-4-iodophenyl)-2-methyl-N-propylpyrimidine-4,6-diamine (6b, Ki = 14 nM), and the corresponding 4-bromophenyl analogue (6a, Ki = 21 nM), were synthesized in four steps from compound 3.     

Quince (Cydonia oblonga Miller) peel polyphenols modulate LPS-induced inflammation in human THP-1-derived macrophages through NF-κB, p38MAPK and Akt inhibition

Chronic inflammation is a hallmark of several pathologies, such as rheumatoid arthritis, gastritis, inflammatory bowel disease, atherosclerosis and cancer. A wide range of anti-inflammatory chemicals have been used to treat such diseases while presenting high toxicity and numerous side effects. Here, we report the anti-inflammatory effect of a non-toxic, cost-effective natural agent, polyphenolic extract from the Tunisian quince Cydonia oblonga Miller. Lipopolysaccharide (LPS) treatment of human THP-1-derived macrophages induced the secretion of high levels of the pro-inflammatory cytokine TNF-α and the chemokine IL-8, which was inhibited by quince peel polyphenolic extract in a dose-dependent manner. Concomitantly, quince polyphenols enhanced the level of the anti-inflammatory cytokine IL-10 secreted by LPS-treated macrophages. We further demonstrated that the unexpected increase in IL-6 secretion that occurred when quince polyphenols were associated with LPS treatment was partially responsible for the polyphenols-mediated inhibition of TNF-α secretion. Biochemical analysis showed that quince polyphenols extract inhibited the LPS-mediated activation of three major cellular pro-inflammatory effectors, nuclear factor-kappa B (NF-κB), p38MAPK and Akt. Overall, our data indicate that quince peel polyphenolic extract induces a potent anti-inflammatory effect that may prove useful for the treatment of inflammatory diseases and that a quince-rich regimen may help to prevent and improve the treatment of such diseases.     

Interaction of a bacterial monorhamnolipid secreted by Pseudomonas aeruginosa MA01 with phosphatidylcholine model membranes

This work presents a biophysical study on the interactions of a monorhamnolipid (monoRL) produced by Pseudomonas aeruginosa MA01 with model phosphatidylcholine membranes. The molecular characterization of the biological activities, including the modulation of phospholipid membranes structure, of this monoRL biosurfactant is of importance for the validation of this particular Pseudomonas aeruginosa strain as a useful biosurfactant producer. The marked amphiphilic structure of monoRL is expected to result in strong interactions with the phospholipid constituents of membrane bilayers. Incorporation of monoRL into DMPC completely abolished the pretransition, and the main gel to liquid-crystalline phase transition was progressively broadened and shifted to lower temperatures, as observed by differential scanning calorimetry. Partial phase diagrams for DPPC and DSPC indicated near-ideal behavior. However, the DMPC diagram indicated fluid phase immiscibility. X-ray diffraction showed and apparent increase in d-value for DPPC containing monoRL, which might be the result of an effective increase in the bilayer thickness, or in the thickness of the hydration layer between bilayers. FTIR indicated that interaction of monoRL with the phospholipid acyl chains did not result in a large additional disordering of the acyl chain region of the fluid bilayer. Analysis of the CO stretching band of DPPC indicated an important effect of monoRL on the interfacial region of phosphatidylcholine bilayers, which might contribute to explain some of the biological activities of this glycolipid.     

KLC3 is involved in sperm tail midpiece formation and sperm function

Kinesin light chain 3 (KLC3) is the only known kinesin light chain expressed in post-meiotic male germ cells. We have reported that in rat spermatids KLC3 associates with outer dense fibers and mitochondrial sheath. KLC3 is able to bind to mitochondria in vitro and in vivo employing the conserved tetratrico-peptide repeat kinesin light chain motif. The temporal expression and association of KLC3 with mitochondria coincides with the stage in spermatogenesis when mitochondria move from the spermatid cell periphery to the developing midpiece suggesting a role in midpiece formation. In fibroblasts, expression of KLC3 results in formation of large KLC3 aggregates close to the nucleus that contain mitochondria. However, the molecular basis of the aggregation of mitochondria by KLC3 and its role in sperm tail midpiece formation are not clear. Here we show that KLC3 expression from an inducible system causes mitochondrial aggregation within 6h in a microtubule dependent manner. We identified the mitochondrial outer membrane porin protein VDAC2 as a KLC3 binding partner. To analyze a role for KLC3 in spermatids we developed a transgenic mouse model in which a KLC3ΔHR mutant protein is specifically expressed in spermatids: this KLC3 mutant protein binds mitochondria and causes aggregate formation, but cannot bind outer dense fibers. Male transgenic mice display significantly reduced reproductive efficiency siring small sized litters. We observed defects in the mitochondrial sheath structure in a number of transgenic spermatids. Transgenic males have a significantly reduced sperm count and produce spermatozoa that exhibit abnormal motility parameters. Our results indicate that KLC3 plays a role during spermiogenesis in the development of the midpiece and in the normal function of spermatozoa.     

Precipitating and relieving factors of migraine versus tension type headache

Background

The correlation between intracranial pressure (ICP) and intraocular pressure (IOP) is still controversial in literature and hence whether IOP can be used as a non-invasive surrogate of ICP remains unknown. The aim of the current study was to further clarify the potential correlation between ICP and IOP.

Methods

The IOP measured with Goldmann applanation tonometer was carried out on 130 patients whose ICP was determined via lumber puncture. The Pearson correlation coefficient between ICP and IOP was calculated, the fisher line discriminated analysis to evaluate the effectivity of using IOP to predict the ICP level.

Results

A significant correlation between ICP and IOP was found. ICP was correlated significantly with IOP of the right eyes (p?<?0.001) and IOP of the left eyes (p?=?0.001) and mean IOP of both eyes (p?<?0.001), respectively. However, using IOP as a measurement to predict ICP, the accuracy rate was found to be 65.4%.

Conclusion

Our data suggested that although a significant correlation exists between ICP and IOP, caution needs to be taken when using IOP readings by Goldmann applanation tonometer as a surrogate for direct cerebrospinal fluid pressure measurement of ICP.     

Hydroxyl radical modification of collagen type II increases its arthritogenicity and immunogenicity

Background

The oxidation of proteins by endogenously generated free radicals causes structural modifications in the molecules that lead to generation of neo-antigenic epitopes that have implications in various autoimmune disorders, including rheumatoid arthritis (RA). Collagen induced arthritis (CIA) in rodents (rats and mice) is an accepted experimental model for RA.

Methodology/Principal Findings

Hydroxyl radicals were generated by the Fenton reaction. Collagen type II (CII) was modified by ^•OH radical (CII-OH) and analysed by ultraviolet-visible (UV-VIS), fluorescence and circular dichroism (CD) spectroscopy. The immunogenicity of native and modified CII was checked in female Lewis rats and specificity of the induced antibodies was ascertained by enzyme linked immunosorbent assay (ELISA). The extent of CIA was evaluated by visual inspection. We also estimated the oxidative and inflammatory markers in the sera of immunized rats. A slight change in the triple helical structure of CII as well as fragmentation was observed after hydroxyl radical modification. The modified CII was found to be highly arthritogenic and immunogenic as compared to the native form. The CII-OH immunized rats exhibited increased oxidative stress and inflammation as compared to the CII immunized rats in the control group.

Conclusions/Significance

Neo-antigenic epitopes were generated on ^•OH modified CII which rendered it highly immunogenic and arthritogenic as compared to the unmodified form. Since the rodent CIA model shares many features with human RA, these results illuminate the role of free radicals in human RA.