Different aspects of bacterial communication signals

The communication or quorum-sensing signal molecules (QSSM) are specialized molecules used by numerous gram-negative bacterial pathogens of animals and plants to regulate or modulate bacterial virulence factor production. In plant-associated bacteria, genes encoding the production of these signal molecules, QSSMs, were discovered to be linked with the phenotype of bacterium, because mutation of these genes typically disrupts some behaviors of bacteria. There are other regulator genes which respond to the presence of signal molecule and regulate the production of signal molecule as well as some virulence factors. The synthesis and regulator genes (collectively called quorum-sensing genes hereafter) are repressed in low bacterial population but induced when bacteria reach to high cell density. Multiple regulatory components have been identified in the bacteria that are under control of quorum sensing. This review describes different communication signal molecules, and the various chemical, physical and genomic factors known to synthesize signals. Likewise, the role of some signal-degrading enzymes or compounds and the interaction of QSSMs with eukaryotic metabolism will be discussed here.     

Ethanesulfonic acid-based esterification of industrial acidic crude palm oil for biodiesel production

An industrial grade acidic crude palm oil (ACPO) pre-treatment process was carried out using ethanesulfonic acid (ESA) as a catalyst in the esterification reaction. ESA was used in different dosages to reduce free fatty acid (FFA) to a minimum level for the second stage of biodiesel production via alkaline transesterification reaction. Different process operating conditions were optimized such as ESA dosage (0.25-3.5% wt/wt), methanol to ACPO molar ratio (1:1-20:1), reaction temperature (40-70 °C), and reaction time (3-150 min). This study revealed the potential use of abundant quantities of ACPO from oil palm mills for biodiesel production. The lab scale results showed the effectiveness of the pre-treatment process using ESA catalyst. Three consecutive catalyst recycling runs were achieved without significant degradation in its performance. Second and third reuse runs needed more reaction time to achieve the target level of FFA content. Esterification and transesterification using ESA and KOH respectively is proposed for biodiesel industrial scale production. The produced biodiesel meets the international standards specifications for biodiesel fuel (EN 14214 and ASTM D6751).     

Optically active: microwave-assisted synthesis and characterization of L-lysine-derived poly (amide-imide)s

l-lysine hydrochloride was transformed to ethyl l-lysine dihydrochloride. This salt was reacted with trimellitic anhydride to yield the corresponding diacid (1). Microwave-assisted polycondensation results a series of novel Poly (amide-imide)s (PAI _a–i ). These polymers have inherent viscosities in the range of 0.23–0.66 dl g⁻¹, display optical activity from +8.02 to +15.11 (as there is no obvious regioselectivity between alpha and epsilon amino groups of the chiral diacid during the polymerization step then random orientation of diacid moieties along the polymer backbone can be predicted and the concept of “tacticity” cannot be addressed in this research), and are readily soluble in polar aprotic solvents. They start to decompose (T _10%) above 362°C and display glass-transition temperatures at 119–153°C. All of the above polymers were fully characterized by UV, FT-IR and ¹H NMR spectroscopy, elemental analysis, thermogravimetric analyses, DSC, inherent viscosity measurement and specific rotation.     

Accumulation and local proliferation of antigen-specific CD4+ T cells in antigen-bearing tissue

Although activation and subsequent expansion of naive CD4(+) T cells within lymph nodes is well characterized, the fate of T effector cells activated within peripheral tissues during secondary reactions is poorly defined. Therefore, we studied the recruitment, proliferation and egress of antigen-specific Th1 effector cells in comparison with nonspecific Th1 cells throughout a delayed-type hypersensitivity reaction (DTH). Although we observed a high turnover of Th1 effector cells with unspecific high-rate recruitment and CCR7-dependent egress from the inflamed tissue in the early, acute DTH phase, a strong, selective accumulation of antigen-specific T cells occurred during the chronic, late DTH phase. This was mainly based on local proliferation of CD4(+) effector cells within the DTH tissue and concomitant retention. Considering the strong CCR7-dependent Th cell egress found in this model, the reduced CCR7 expression on antigen-specific T cells isolated from late-phase DTH tissue most likely contributes to the retention of these cells within the tissue. Thus, peripheral tissues can support not only the proliferation of CD8(+) T cells, as recently shown, but also that of CD4(+) T effector cells, forming a pool of tissue-resident T cells.     

Ionic liquid catalyzed synthesis and characterization of heterocyclic and optically active poly (amide-imide)s incorporating <Emphasis Type="SmallCaps">l</Emphasis>-amino acids

N,N′-Pyromelliticdiimido-di-l-alanine (1), N,N′-Pyromelliticdiimido-di-l-phenylalanine (2), and N,N′-Pyromelliticdiimido-di-l-leucine (3) were prepared from the reaction of Pyromellitic dianhydride with corresponding l-amino acids in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. A series of poly (amide-imide)s containing l-amino acids were prepared from the synthesized dicarboxylic acids with two synthetic aromatic diamines in an ionic liquid (IL) as a green, safe and eco-friendly medium and also reactions catalysis agent. Evaluation of data shows that IL is the better polyamidation medium than the reported method and the catalysis stand on the higher inherent viscosities of the obtained PAIs and the rate of polymerizations beyond the greener reaction conditions and deletion of some essential reagents in conventional manners. Characterization were performs by means of IR, MS and ¹H NMR spectroscopy, elemental analysis, specific rotation, thermogravimetric analysis and differential scanning calorimetric techniques. Molecular weights of the obtained polymers were evaluated viscometrically, and the measured inherent viscosities were in the range 0.43–0.85 dL/g. These polymers were readily soluble in many organic solvents. These polymers still kept good thermal stability with glass transition temperatures in the range of 94–154°C, and the decomposition temperature under the nitrogen atmosphere for 10% weight-loss temperatures in excess of 308°C.     

Formation of dopamine quinone-DNA adducts and their potential role in the etiology of Parkinson's disease

The neurotransmitter dopamine is oxidized to its quinone (DA-Q), which at neutral pH undergoes intramolecular cyclization by 1,4-Michael addition, followed by oxidation to form leukochrome, then aminochrome, and finally neuromelanin. At lower pH, the amino group of DA is partially protonated, allowing the competitive intermolecular 1,4-Michael addition with nucleophiles in DNA to form the depurinating adducts, DA-6-N3Ade and DA-6-N7Gua. Catechol estrogen-3,4-quinones react by 1,4-Michael addition to form the depurinating 4-hydroxyestrone(estradiol)-1-N3Ade [4-OHE1(E2)-1-N3Ade] and 4-OHE1(E2)-1-N7Gua adducts, which are implicated in the initiation of breast and other human cancers. The effect of pH was studied by reacting tyrosinase-activated DA with DNA and measuring the formation of depurinating adducts. The most adducts were formed at pH 4, 5, and 6, and their level was nominal at pH 7 and 8. The N3Ade adduct depurinated instantaneously, but N7Gua had a half-life of 3 H. The slow loss of the N7Gua adduct is analogous to that observed in previous studies of natural and synthetic estrogens. The antioxidants N-acetylcysteine and resveratrol efficiently blocked formation of the DA-DNA adducts. Thus, slightly acidic conditions render competitive the reaction of DA-Q with DNA to form depurinating adducts. We hypothesize that formation of these adducts could lead to mutations that initiate Parkinson's disease. If so, use of N-acetylcysteine and resveratrol as dietary supplements may prevent initiation of this disease.     

Serum antibody titers against heat shock protein 27 are associated with the severity of coronary artery disease

Antibody titers to several heat shock proteins (anti-Hsps) have been reported to be associated with the severity and progression of cardiovascular disease. However, there are little data regarding anti-Hsp27 titers in patients with coronary artery disease (CAD). A total of 400 patients with suspected CAD were recruited. Based on the results of coronary angiography, these patients were classified into CAD⁺ (n = 300) and CAD⁻ (n = 100) groups defined as patients with ≥50% and <50% stenosis of any major coronary artery, respectively. Eighty-three healthy subjects were also recruited as the control group. Serum anti-Hsp27 IgG titers were measured using an in-house enzyme-linked immunosorbent assay. CAD⁺ patients had significantly higher anti-Hsp27 titers compared with both CAD⁻ and control groups. Anti-Hsp27 titers were also higher in the CAD⁻ group compared with the control group. With regard to the number of affected vessels in the CAD⁺ group, patients with three-vessel disease had higher anti-Hsp27 titers compared with both two-vessel disease (2VD) and one-vessel disease (1VD) subgroups. However, there was no significant difference between 1VD and 2VD subgroups. In multiple linear regression analysis, the number of narrowed vessels and smoking were significant independent determinants of serum anti-Hsp27 titers. The present findings indicate that serum anti-Hsp27 titers may be associated with the presence and severity of coronary artery disease.     

Cannulation of the Mouse Submandibular Salivary Gland via the Wharton's Duct

Severe salivary gland hypofunction is frequently found in patients with Sjögren''s syndrome and those who receiving therapeutic irradiation in their head and neck regions for cancer treatment. Both groups of patients experience symptoms such as xerostomia (dry mouth), dysphagia (impaired chewing and swallowing), severe dental caries, altered taste, oro-pharyngeal infections (candidiasis), mucositis, pain and discomfort.One innovative approach of regenerative medicine for the treatment of salivary gland hypo-function is speculated in RS Redman, E Mezey et al. 2009: stem cells can be directly deposited by cannulation into the gland as a potent method in reviving the functions of the impaired organ. Presumably, the migrated foreign stem cells will differentiate into glandular cells to function as part of the host salivary gland. Also, this cannulation technique is an expedient and effective delivery method for clinical gene transfer application.Here we illustrate the steps involved in performing the cannulation procedure on the mouse submandibular salivary gland via the Wharton''s duct (Fig 1). C3H mice (Charles River, Montreal, QC, Canada) are used for this experiment, which have been kept under clean conventional conditions at the McGill University animal resource center. All experiments have been approved by the University Animal Care Committee and were in accordance with the guidelines of the Canadian Council on Animal Care.For this experiment, a trypan blue solution is infused into the gland through the opening of the Wharton''s duct using a insulin syringe with a 29-gauge needle encased inside a polyethylene tube. Subsequently, the mouse is dissected to show that the infusions migrated into the gland successfully. Download video file.^{(31M, mov)}     

Establishing Embryonic Mouse Neural Stem Cell Culture Using the Neurosphere Assay

In mammalians, stem cells acts as a source of undifferentiated cells to maintain cell genesis and renewal in different tissues and organs during the life span of the animal. They can potentially replace cells that are lost in the aging process or in the process of injury and disease. The existence of neural stem cells (NSCs) was first described by Reynolds and Weiss (1992) in the adult mammalian central nervous system (CNS) using a novel serum‐free culture system, the neurosphere assay (NSA). Using this assay, it is also feasible to isolate and expand NSCs from different regions of the embryonic CNS. These in vitro expanded NSCs are multipotent and can give rise to the three major cell types of the CNS. While the NSA seems relatively simple to perform, attention to the procedures demonstrated here is required in order to achieve reliable and consistent results. This video practically demonstrates NSA to generate and expand NSCs from embryonic day 14-mouse brain tissue and provides technical details so one can achieve reproducible neurosphere cultures. The procedure includes harvesting E14 mouse embryos, brain microdissection to harvest the ganglionic eminences, dissociation of the harvested tissue in NSC medium to gain a single cell suspension, and finally plating cells in NSA culture. After 5-7 days in culture, the resulting primary neurospheres are passaged to further expand the number of the NSCs for future experiments.Download video file.^{(69M, mov)}     

A Study of <Emphasis Type="Italic">in vitro</Emphasis> Regeneration in Relation to Doses of Growth Regulators in Hybrids of Upland Cotton

The frequency of in vitro callus induction and plant regeneration is influenced by several factors, including composition of culture medium, explant source, and the genotype. Crosses between regenerable and non-regenerable upland cotton cultivars were evaluated for hybrid vigour towards regeneration responses, which is consequential in recalcitrant crop species like cotton where regeneration is limited only to a few cultivars. The results indicated that regenerable and non-regenerable parental cultivars had similar potential of producing callus, but differed in producing callus weight and embryogenic calli. Mean performance of crosses, regarding callus induction, callus weight, callus growth rate, percent embryo induction, and percentage of germinating embryos, deviated considerably from the performance of their parents, signifying the presence of hybrid vigour for the expression of these traits. Magnitude of hybrid vigour varied across hormonal levels. Genetic component was evident for all the traits although of lower magnitude. The results indicated that genetic component in the phenotypic expression of callus growth, percentages of embryo induction and germinating embryos was higher than that of callus induction, callus weight and percentage of embryogenic calli. Hormonal concentration in the media had affect on the degree of gene expression responsible for regeneration in upland cotton. Over, partial- and additive-dominance types of gene effects were apparent in the expression of these traits. Genotype × growth regulator level interaction caused considerable variation in the expression of regeneration responses, suggesting that determination of specific level of growth regulator concentration in the medium was necessary for a particular genotype to obtain optimum response. Genotype × explant source interaction was, however, relatively less important. Differences among genotypes for percent embryo induction were clearly evident.