Beta-amyloid peptides stimulate endozepine biosynthesis in cultured rat astrocytes

Accumulation of beta-amyloid peptide (Abeta), which is a landmark of Alzheimer's disease, may alter astrocyte functions before any visible symptoms of the disease occur. Here, we examined the effects of Abeta on biosynthesis and release of diazepam-binding inhibitor (DBI), a polypeptide primarily expressed by astroglial cells in the CNS. Quantitative RT-PCR and specific radioimmunoassay demonstrated that aggregated Abeta(25-35), at concentrations up to 10(-4) m, induced a dose-dependent increase in DBI mRNA expression and DBI-related peptide release from cultured rat astrocytes. These effects were totally suppressed when aggregation of Abeta(25-35) was prevented by Congo red. Measurement of the number of living cells revealed that Abeta(25-35) induced a trophic rather than a toxic effect on astrocytes. Administration of cycloheximide blocked Abeta(25-35)-induced increase of DBI gene expression and endozepine accumulation in astrocytes, indicating that protein synthesis is required for DBI gene expression. Altogether, the present data suggest that Abeta-induced activation of endozepine biosynthesis and release may contribute to astrocyte proliferation associated with Alzheimer's disease.     

Effects of mycorrhizal fungi inoculation and soil amendment with hydrogel on leaf anatomy,growth and physiology performance of olive plantlets under two contrasting water regimes

Abiotic stresses present a real environmental problem in agriculture field. In our paper, we examine the significance of arbuscular mycorrhizal fungi (AMF) and soil amendment with water retaining superpolymers (hydrogel) on growth and physiology performance of olive plantlets. Our experiment was carried out in nursery conditions, to test the impact of hydrogel (TH) and mycorrhizal fungi (TM), used individually or combined (THM), and compare them with non inoculated plants (TC), to understand and reduce the water stress damage in olive plantlets (cv. Chemlali). We also evaluate interactions between hydrogel, mycorrhizal treatments and water regimes. Results of mycorrhization (M%) show that roots colonized by Rhizophagus irregularis of well-watered plants were about 40.87%. In combined treatment (THM), M% was about 32.14%. Compared to TC treatment, TM treatment enhances significantly the dry weights of the whole plant under the two water regimes. The TM treatment had the highest relative water content (66.50%) and Chl (a?+?b) (0.83 mg g^??1) in stressed conditions. We found also that under water stress, the maximal quantum efficiency of the photosystem II measurements in leaves were significantly improved by 50.70% in TH treatment compared to control. For phenolic contents, TH treatment decreased significantly total phenols by 50.10% compared to TC. Our study gives evidence that the use of AMF and the hydrogel separately or in combination may enhance the capacity to avoid drought damages of olive plantlets and improve olive performances.     

Hyporientalin A,an anti-<Emphasis Type="Italic">Candida</Emphasis> peptaibol from a marine <Emphasis Type="Italic">Trichoderma orientale</Emphasis>

A Trichoderma orientale strain LSBA1 was isolated from the Mediterranean marine sponge Cymbaxinella damicornis. The crude extract of T. orientale mycelium showed inhibitory activity against growth of Gram-positive and Gram-negative bacteria as well as clinical isolates of Candida albicans. Purification of the anti-Candida component was performed using a combination of open silica gel-60 column and reverse phase high performance liquid chromatography. The active compound called hyporientalin A has been identified as a peptaibol analogue of longibrachin-A-II using mass spectrometry. It exhibited fungicidal activity against clinical isolates of C. albicans with minimal inhibitory concentrations (MICs) ranging from 2.49 to 19.66 µM, comparable to that of the antifungal agent amphotericin B. Our data support the use of hyporientalin A as a promising new and efficient antifungal drug in the treatment of candidiasis while controlling toxicity.     

Role of PACAP and VIP in astroglial functions

Astrocytes represent at least 50% of the volume of the human brain. Besides their roles in various supportive functions, astrocytes are involved in the regulation of stem cell proliferation, synaptic plasticity and neuroprotection. Astrocytes also influence neuronal physiology by responding to neurotransmitters and neuropeptides and by releasing regulatory factors termed gliotransmitters. In particular, astrocytes express the PACAP-specific receptor PAC1-R and the PACAP/VIP mutual receptors VPAC1-R and VPAC2-R during development and/or in the adult. There is now clear evidence that PACAP and VIP modulate a number of astrocyte activities such as proliferation, plasticity, glycogen production, and biosynthesis of neurotrophic factors and gliotransmitters.     

Production of doubled haploids in durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> Desf.) through culture of unpollinated ovaries

The objective of this work was to produce doubled haploid plants from durum wheat through gynogenesis using unpollinated ovary culture of three local Tunisian genotypes (Jenah Khotifa, Hmira, Azizi) and three improved cultivars (Karim, Khiar, Razzek). A total of 12,000 unpollinated ovaries were cultured in this study. Spikes were either pretreated at 4°C for 14 days or at 4°C in a mannitol solution (0.3 M) for 7 days. Induction was performed using two media. We showed that ovary development, callus and plantlet regeneration was influenced significantly by genotype and growth conditions. The highest regeneration frequency was obtained when the microspore population was in the late mononucleate to binucleate stage. Our results suggested that the cold pretreatment for 14 days was more efficient than the cold treatment in a mannitol solution. Furthermore, the addition of 2,4-D, vitamins and glutamine, and the use of maltose as sugar source in media improved the ovary culture. When the unpollinated ovaries were cultured under the conditions found to be optimal in the present study, a total of 84 plants were produced, all green and haploid. The best levels for regenerated plants were obtained with the cultivars Khiar (3.5%), Hmira (3.1%) and Karim (1.5%). Fertile doubled haploid plants were obtained by colchicine treatment. This result represents a modern tool for breeders to produce durum wheat homozygous lines in a few months.     

Biological control of Botrytis cinerea using the antagonistic and endophytic Burkholderia cepacia Cs5 for vine plantlet protection

Antifungal activity of the Burkholderia cepacia Cs5 was tested in vitro and in vivo for the control of Botrytis cinerea . Bacterial biomass was significantly improved by the amendment of ZnSO(4), Mo(7)(NH(4))(6)O(24), and mannitol to the NBY medium; consequently, the amount of the secreted fungicides was increased. The quantification of B. cinerea inhibition, in liquid and solid conditions, showed an important sensitivity of this fungus to the strain Cs5 fungicides. Microscopic monitoring impact of these fungicides on mycelium structure showed an important increase in their diameter and ramifications in the presence of 0.75% supernatant. For the in vivo application of the strain Cs5, Vitis vinifera plantlets were inoculated with a Cs5 bacterial suspension, then with B. cinerea spores. The plantlets protection was total and durable when these two inoculations were made 3 weeks apart, which is the time for the endophytic bacterium to colonize the plantlets up to the top leaves. This protection is due to Cs5 antagonism and the elicitation of the plantlets self-defense via the root overgrowth.     

Shrimp waste fermentation with Pseudomonas aeruginosa A2: optimization of chitin extraction conditions through Plackett-Burman and response surface methodology approaches

A Box-Bhenken design with four variables (shrimp shell concentration (SSC), glucose concentration, incubation time and inoculum size) and three levels was used for the determination of the deproteinization and demineralization efficiencies in fermented shrimp shells by Pseudomonas aeruginosa A2. The fermentation variables were selected in accordance with Plackett-Burman design. Maximum demineralization of 96%, with about 89% of protein removal occurs under the following conditions: SSC 50 g/l, glucose 50 g/l, 5 days and inoculum of 0.05 OD. This environment friendly method (biological treatment) can be considered as an effective pretreatment to produce a high-quality chitin.     

Glucokinase regulatory protein genetic variant interacts with omega-3 PUFA to influence insulin resistance and inflammation in metabolic syndrome

Glucokinase Regulatory Protein (GCKR) plays a central role regulating both hepatic triglyceride and glucose metabolism. Fatty acids are key metabolic regulators, which interact with genetic factors and influence glucose metabolism and other metabolic traits. Omega-3 polyunsaturated fatty acids (n-3 PUFA) have been of considerable interest, due to their potential to reduce metabolic syndrome (MetS) risk.

Objective

To examine whether genetic variability at the GCKR gene locus was associated with the degree of insulin resistance, plasma concentrations of C-reactive protein (CRP) and n-3 PUFA in MetS subjects.

Design

Homeostasis model assessment of insulin resistance (HOMA-IR), HOMA-B, plasma concentrations of C-peptide, CRP, fatty acid composition and the GCKR rs1260326-P446L polymorphism, were determined in a cross-sectional analysis of 379 subjects with MetS participating in the LIPGENE dietary cohort.

Results

Among subjects with n-3 PUFA levels below the population median, carriers of the common C/C genotype had higher plasma concentrations of fasting insulin (P = 0.019), C-peptide (P = 0.004), HOMA-IR (P = 0.008) and CRP (P = 0.032) as compared with subjects carrying the minor T-allele (Leu446). In contrast, homozygous C/C carriers with n-3 PUFA levels above the median showed lower plasma concentrations of fasting insulin, peptide C, HOMA-IR and CRP, as compared with individuals with the T-allele.

Conclusions

We have demonstrated a significant interaction between the GCKR rs1260326-P446L polymorphism and plasma n-3 PUFA levels modulating insulin resistance and inflammatory markers in MetS subjects. Further studies are needed to confirm this gene-diet interaction in the general population and whether targeted dietary recommendations can prevent MetS in genetically susceptible individuals.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00429195","term_id":"NCT00429195"}}NCT00429195     

A novel MT-CO1 m.6498C>A variation associated with the m.7444G>A mutation in the mitochondrial COI/tRNASer(UCN) genes in a patient with hearing impairment,diabetes and congenital visual loss

Mitochondrial diseases are a clinically heterogeneous group of disorders that arise as a result of dysfunction of the mitochondrial respiratory chain. Sensorineural hearing loss (SNHL) has been described in association to different mitochondrial multisystem syndromes, often involving the central nervous system, neuromuscular, or endocrine organs. In this study, we described a Tunisian young girl with hearing impairment, congenital visual loss and maternally inherited diabetes. No mutation was found in the mitochondrial tRNA^Leu(UUR) and the 12S rRNA genes. However, we detected the m.7444G>A mutation in the mitochondrial COI/tRNA^Ser(UCN) genes. This mutation eliminates the termination codon of the MT-CO1 gene and extends the COI polypeptide by three amino acids (Lys–Gln–Lys) to the C-terminal. The whole mitochondrial genome screening revealed the presence of a novel mutation m.6498C>A (L199I) in the mitochondrial DNA-encoded subunit I of the cytochrome c oxidase (COX). This “probably damaging” transversion affects a highly conserved domain and it was absent in 200 Tunisian controls. The studied patient was classified under the haplogroup H2a.     

PIVL,a new serine protease inhibitor from Macrovipera lebetina transmediterranea venom,impairs motility of human glioblastoma cells

A novel Kunitz-type serine proteinase inhibitor, termed PIVL, was purified to homogeneity from the venom of the Tunisian snake Macrovipera lebetina transmediterranea. It is a monomeric polypeptide chain cross-linked by three disulfide linkages with an isotope-averaged molecular mass of 7691.7 Da. The 67-residue full-length PIVL sequence was deduced from a venom gland cDNA clone. Structurally, PIVL is built by a single Kunitz/BPTI-like domain. Functionally, it is able to specifically inhibit trypsin activity. Interestingly, PIVL exhibits an anti-tumor effect and displays integrin inhibitory activity without being cytotoxic. Here we show that PIVL is able to dose-dependently inhibit the adhesion, migration and invasion of human glioblastoma U87 cells. Our results also show that PIVL impairs the function of αvβ3 and to a lesser extent, the activity of αvβ6, αvβ5, α1β1 and α5β1 integrins. Interestingly, we demonstrate that the ⁴¹RGN⁴³ motif of PIVL is likely responsible for its anti-cancer effect. By using time lapse videomicroscopy, we found that PIVL significantly reduced U87 cells motility and affected cell directionality persistence by 68%. These findings reveal novel pharmacological effects for a Kunitz-type serine proteinase inhibitor.