Effect of osmotic stress on <Emphasis Type="Italic">Myrtus communis</Emphasis> germination

The effects of water potential on germination were studied in four provenances of Myrtus from different bioclimatic zones in Tunisia. Water potential between 0 and −10 bars were obtained using polyethylene glycol 6000 (PEG-6000) solutions. Seeds were planted in Petri dishes full of sterile perlite, and kept for one month under 1500 lux light with 16h photoperiod and at 25°C. A low water potential induced a reduction in germination percentage and germination speed. Significant variations between the provenances were found even under control conditions, especially at the speed germination level. The provenances from humid regions were the most susceptible to water stress, and their germination percentage showed significant reductions at −8 bars. These differences in germination ability of provenances might be attributed to intraspecific variations resulting from the effects of natural selection and genetic pool background.     

Draft Genome Sequence of Tsukamurella sp. Strain 1534

A draft genome sequence of Tsukamurella sp., an aerobic bacterium isolated from a human sputum specimen, is described here. A new virus or provirus, TPA4, was characterized.     

Mitochondrial disease patients with novel ND4 12058A > C and ND1 m.3911A > G variations: implications for a role in the phenotype following a bioinformatic investigation

Molecular Biology Reports - Mitochondrial diseases include a wide group of clinically heterogeneous disorders caused by a dysfunction of the mitochondrial respiratory chain and can be related to...     

A Rat Model of Neonatal Candidiasis Demonstrates the Importance of Lipases as Virulence Factors for <Emphasis Type="Italic">Candida albicans</Emphasis> and <Emphasis Type="Italic">Candida parapsilosis</Emphasis>

The host factors that contribute to the increased susceptibility of preterm neonates to invasive candidiasis have not been fully identified. In addition, there has been a lack of suitable models to study this problem. We show that rat pups, similar to premature neonates, display increased susceptibility to experimental Candida albicans infection. Further, we find that both C. albicans and Candida parapsilosis lipase disruptant mutants exhibit decreased virulence in rat pups, demonstrating the utility of the model to evaluate the impact of specific genes in disease pathogenesis. Our findings highlight the contribution of lipases to the virulence of C. albicans and C. parapsilosis and provide a new system to study the increased susceptibility of neonates to Candida infections.     

Association of three polymorphisms of scavenger receptor class BI gene (exon8, exon1, intron5) with coronary stenosis in a coronary Tunisian population

Background

The potential role of scavenger receptor class BI (gene name SCARB1) in the regulation of lipoproteins metabolism and atherosclerosis has attracted considerable interest. We tested the relationship of SCARB1 polymorphisms with significant coronary stenosis (SCS) and lipid profile in a coronary Tunisian population.

Methods

Three SCARB1 polymorphisms (exon8 (C/T), exon1 (G/A), intron5 (C/T)) were studied in 316 Tunisian patients undergoing coronary angiography. SCS was defined as a luminal narrowing of ≥ 50% in at least one major coronary artery. Lipid profile was measured. Genotyping was performed using PCR–RFLP.

Results

Individuals with TT genotypes of exon8 were associated with higher concentrations of plasma HDL-C and ApoAI in the group without SCS. Carriers of T allele of exon8 were associated with 41% lower risk of SCS. This protective effect seemed to be particularly significant in women, nondiabetics and nonsmokers. Subjects homozygous for the variant allele of intron5 were significantly associated with an increased risk of SCS, particularly in smokers. AA genotype of exon1 was associated with an increased risk of SCS in diabetics and in patients with metabolic syndrome. The (CAT) haplotype was associated with increase in the risk of SCS compared to the wild haplotype and had a 4-fold greater risk of SCS than patients with haplotype (TGC) which seems to be the most protective against SCS.

Conclusion

Carriers of T allele of exon8 in SCARB1 seemed to increase HDL-C and ApoAI concentrations and reduce the risk of SCS. The intron5, exon1 and (CAT) haplotype seemed to have an atherogenic effect.     

The GPS motif is a molecular switch for bimodal activities of adhesion class G protein-coupled receptors

Adhesion class G protein-coupled receptors (aGPCR) form the second largest group of seven-transmembrane-spanning (7TM) receptors whose molecular layout and function differ from canonical 7TM receptors. Despite their essential roles in immunity, tumorigenesis, and development, the mechanisms of aGPCR activation and signal transduction have remained obscure to date. Here, we use a transgenic assay to define the protein domains required in vivo for the activity of the prototypical aGPCR LAT-1/Latrophilin in Caenorhabditis elegans. We show that the GPCR proteolytic site (GPS) motif, the molecular hallmark feature of the entire aGPCR class, is essential for LAT-1 signaling serving in two different activity modes of the receptor. Surprisingly, neither mode requires cleavage but presence of the GPS, which relays interactions with at least two different partners. Our work thus uncovers the versatile nature of aGPCR activity in molecular detail and places the GPS motif in a central position for diverse protein-protein interactions.     

Evaluation of the capacity of three halophytes to desalinize their rhizosphere as grown on saline soils under nonleaching conditions

In the sabkha of Soliman (N‐E Tunisia), soil samples of the upper 20 cm were taken during the driest period of the year (July–August) from inside and outside tufts of two perennial halophytes: Arthrocnemum indicum (Willd.) Moq. and Suaeda fruticosa Forssk., both from family Chenopodiaceae. Samples were analysed for electrical conductivity of the saturation paste extract (ECe) and soluble sodium (Na⁺) content. Then, tufts were divided into three size categories and their shoot biomass production and Na⁺ content were determined. Our results showed a considerable contribution of shoot Na⁺ accumulation to rhizosphere desalination. The capacity of the two native halophytes A. indicum. and S. fruticosa to desalinize saline soils was compared with that of an introduced halophyte, Sesuvium portulacastrum L. (Aizoaceae). Seedlings were grown under greenhouse conditions in pots containing 8 kg of saline soil each. Pots were irrigated with tap water during 170 days without leaching. Our results confirmed the contribution of shoot Na⁺ accumulation to soil desalination. They showed also that among the three studied species, Sesuvium portulacastrum L. seems to be the most convenient to be used for this purpose in arid and semi‐arid regions where precipitation is too low to leach salts from rhizosphere.     

Development of a beverage from red grape juice fermented with the Kombucha consortium

Kombucha is a health-promoting fermented beverage traditionally made by fermenting a sweetened tea with a symbiotic culture of yeast species and acetic acid bacteria. The aim of this work was to develop a beverage using red grape juice as an alternative substrate. Grape juice contains various nutrient elements and phytochemicals, such as polyphenols, which possess a wide range of biological activities. We investigated the chemical characteristics and sensory and antimicrobial activities of the fermented grape juice Kombucha beverage. The pH decreased from 3.95 to 2.9 during the fermentation process and remained fairly constant thereafter, and the acetic acid bacteria and yeast counts in the broth increased up to 6 days of fermentation and subsequently decreased. Phenolic and anthocyanin contents and the antioxidant activity of the fermented beverage were higher after fermentation, with the maximum increase observed on the sixth day of fermentation when values were approximately 2.47- and 1.59-fold higher than pre-fermentation values, respectively, as assessed by 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis (3-ethylbenzothiazoline-6- sulfonic acid) radical scavenging assays. Fourier transform infrared spectroscopy was used for the qualitative analysis of the grape juice before and after fermentation. Distinct peak variations in the spectral region between 2500 and 1650 cm^?1 were observed, which matched the appearance of organic acids and changes in phenolic compounds. Fermented juice Kombucha showed antibacterial activity toward all tested bacteria, which can be primarily ascribed to the increased production of acetic acid, but also to the biosynthesis of other metabolites, during the fermentation process. The 6-day fermented juice was the most appreciated by the taste panel based on the overall quality evaluation; with prolongation of fermentation the fermented juice acquired a distinct sour flavor.     

ADCK3, an ancestral kinase, is mutated in a form of recessive ataxia associated with coenzyme Q10 deficiency

Muscle coenzyme Q(10) (CoQ(10) or ubiquinone) deficiency has been identified in more than 20 patients with presumed autosomal-recessive ataxia. However, mutations in genes required for CoQ(10) biosynthetic pathway have been identified only in patients with infantile-onset multisystemic diseases or isolated nephropathy. Our SNP-based genome-wide scan in a large consanguineous family revealed a locus for autosomal-recessive ataxia at chromosome 1q41. The causative mutation is a homozygous splice-site mutation in the aarF-domain-containing kinase 3 gene (ADCK3). Five additional mutations in ADCK3 were found in three patients with sporadic ataxia, including one known to have CoQ(10) deficiency in muscle. All of the patients have childhood-onset cerebellar ataxia with slow progression, and three of six have mildly elevated lactate levels. ADCK3 is a mitochondrial protein homologous to the yeast COQ8 and the bacterial UbiB proteins, which are required for CoQ biosynthesis. Three out of four patients tested showed a low endogenous pool of CoQ(10) in their fibroblasts or lymphoblasts, and two out of three patients showed impaired ubiquinone synthesis, strongly suggesting that ADCK3 is also involved in CoQ(10) biosynthesis. The deleterious nature of the three identified missense changes was confirmed by the introduction of them at the corresponding positions of the yeast COQ8 gene. Finally, a phylogenetic analysis shows that ADCK3 belongs to the family of atypical kinases, which includes phosphoinositide and choline kinases, suggesting that ADCK3 plays an indirect regulatory role in ubiquinone biosynthesis possibly as part of a feedback loop that regulates ATP production.