Enzymatic Engineering of Polysialic Acid on Cells in Vitro and in Vivo Using a Purified Bacterial Polysialyltransferase

In vertebrates, polysialic acid (PSA) is typically added to the neural cell adhesion molecule (NCAM) in the Golgi by PST or STX polysialyltransferase. PSA promotes plasticity, and its enhanced expression by viral delivery of the PST or STX gene has been shown to promote cellular processes that are useful for repair of the injured adult nervous system. Here we demonstrate a new strategy for PSA induction on cells involving addition of a purified polysialyltransferase from Neisseria meningitidis (PST_Nm) to the extracellular environment. In the presence of its donor substrate (CMP-Neu5Ac), PST_Nm synthesized PSA directly on surfaces of various cell types in culture, including Chinese hamster ovary cells, chicken DF1 fibroblasts, primary rat Schwann cells, and mouse embryonic stem cells. Similarly, injection of PST_Nm and donor in vivo was able to produce PSA in different adult brain regions, including the cerebral cortex, striatum, and spinal cord. PSA synthesis by PST_Nm requires the presence of the donor CMP-Neu5Ac, and the product could be degraded by the PSA-specific endoneuraminidase-N. Although PST_Nm was able to add PSA to NCAM, most of its product was attached to other cell surface proteins. Nevertheless, the PST_Nm-induced PSA displayed the ability to attenuate cell adhesion, promote neurite outgrowth, and enhance cell migration as has been reported for endogenous PSA-NCAM. Polysialylation by PST_Nm occurred in vivo in less than 2.5 h, persisted in tissues, and then decreased within a few weeks. Together these characteristics suggest that a PST_Nm-based approach may provide a valuable alternative to PST gene therapy.     

Contrasting association of Leptin receptor polymorphisms and haplotypes with polycystic ovary syndrome in Bahraini and Tunisian women: a case–control study

Background: The present study examined the contribution of ethnicity to the association of leptin receptor gene (LEPR) gene variants with polycystic ovary syndrome (PCOS) in Tunisian and Bahraini Arabic-speaking women.Methods: Subjects consisted of 320 women with PCOS, and 446 eumenorrhic women from Tunisia, and 242 women with PCOS and 238 controls from Bahrain. Genotyping of (exonic) rs1137100 and rs1137101 and (intronic) rs2025804 LEPR variants was done by allelic exclusion.Results: The minor allele frequencies (MAFs) of rs1137100 and rs1137101 were significantly different between PCOS cases and control women from Bahrain but not Tunisia, and LEPR rs1137101 was associated with increased PCOS susceptibility only in Bahraini subjects. Furthermore, rs1137100 was associated with decreased PCOS risk among Bahrainis under codominant and recessive models; rs1137100 was negatively associated with PCOS in Tunisians after controlling for testosterone. In addition, rs2025804 was associated with increased PCOS risk among Tunisian but not Bahraini women, after adjusting for key covariates. Negative correlation was seen between rs1137101 and triglycerides in Tunisians, while homeostasis model assessment of insulin resistance (HOMA-IR) and insulin correlated with rs2025804 and rs1137101 among Bahraini subjects, and rs1137101 correlated with estradiol and prolactin. Taking TAG haplotype as common, positive association of TAA and negative association of TGG haplotype with PCOS was seen among Bahraini women; no three-locus PCOS-associated haplotypes were found in Tunisians.Conclusions: The present study is the first to demonstrate the contribution of ethnicity to the association of LEPR gene variants with PCOS, thereby highlighting the significance of controlling for ethnicity in gene association investigations.     

COMPARATIVE FUNCTIONAL ANALYSES OF ULTRABITHORAX REVEAL MULTIPLE STEPS AND PATHS TO DIVERSIFICATION OF LEGS IN THE ADAPTIVE RADIATION OF SEMI‐AQUATIC INSECTS

Invasion of new ecological habitats is often associated with lineage diversification, yet the genetic changes underlying invasions and radiations are poorly understood. Over 200 million years ago, the semi‐aquatic insects invaded water surface from a common terrestrial ancestor and diversified to exploit a wide array of niches. Here, we uncover the changes in regulation and function of the gene Ultrabithorax associated with both the invasion of water surface and the subsequent diversification of the group. In the common ancestor of the semi‐aquatic insects, a novel deployment of Ubx protein in the mid‐legs increased their length, thereby enhancing their role in water surface walking. In derived lineages that specialize in rowing on the open water, additional changes in the timing of Ubx expression further elongated the mid‐legs thereby facilitating their function as oars. In addition, Ubx protein function was selectively reversed to shorten specific rear‐leg segments, thereby enabling their function as rudders. These changes in Ubx have generated distinct niche‐specialized morphologies that account for the remarkable diversification of the semi‐aquatic insects. Therefore, changes in the regulation and function of a key developmental gene may facilitate both the morphological change necessary to transition to novel habitats and fuel subsequent morphological diversification.     

Association between plasmid carrying an expanded-spectrum cephalosporin resistance and biofilm formation in Escherichia coli

The formation of biofilm is a universal bacterial survival strategy. Biofilms occur on inert and living support in the natural environment and in industrial installations. This microenvironment leads to the horizontal transfer of genetic material between bacteria by physical contact. In order to evaluate the relationship between biofilm-forming capabilities, surface characteristics and plasmid content we purified from Salmonella a plasmid conferring resistance to cephalosporin and transferred it by electroporation to E.coli DH10B originally unable to form biofilm in inert surface. We demonstrated the association between a plasmid conferring resistance to expanded-spectrum cephalosporin and biofilm formation. We also noted that this plasmid influences the cell surface properties and cell motility.     

On the Stock Estimation for a Harvested Fish Population

We consider a stage-structured model of a harvested fish population and we are interested in the problem of estimating the unknown stock state for each class. The model used in this work to describe the dynamical evolution of the population is a discrete time system including a nonlinear recruitment relationship. To estimate the stock state, we build an observer for the considered fish model. This observer is an auxiliary dynamical system that uses the catch data over each time interval and gives a dynamical estimate of the stock state for each stage class. The observer works well even if the recruitment function in the considered model is not well known. The same problem for an age-structured model has been addressed in a previous work (Ngom et al., Math. Biosci. Eng. 5(2):337–354, 2008).     

Anticonvulsant and analgesic activities of crude extract and its fractions of the defensive secretion from the Mediterranean sponge, Spongia officinalis

ABSTRACT: This study progresses in the direction of identifying component(s) from the Mediterranean sponge, Spongia officinalis with anticonvulsant and analgesic activities. We investigated the efficacy of crude extract and its semi-purified fractions (F1-F3) of the defensive secretion from Spongia officinalis for their in vivo anticonvulsant activity using the pentylenetetrazole (PTZ) seizure model and analgesic activity using the writhing test in mice. Among the series the crude extract exhibited interesting analgesic activity in a dose dependent manner. Similarly the fraction F2 showed a partial protection of mice from PTZ-induced seizure and interesting analgesic activity in a dose dependent manner. The purification and the determination of chemical structure(s) of compound(s) of this active fraction are under investigation.     

Multi-stage Vector-Borne Zoonoses Models: A Global Analysis

A class of models that describes the interactions between multiple host species and an arthropod vector is formulated and its dynamics investigated. A host-vector disease model where the host’s infection is structured into n stages is formulated and a complete global dynamics analysis is provided. The basic reproduction number acts as a sharp threshold, that is, the disease-free equilibrium is globally asymptotically stable (GAS) whenever \({\mathcal {R}}_0^2\le 1\) and that a unique interior endemic equilibrium exists and is GAS if \({\mathcal {R}}_0^2>1\). We proceed to extend this model with m host species, capturing a class of zoonoses where the cross-species bridge is an arthropod vector. The basic reproduction number of the multi-host-vector, \({\mathcal {R}}_0^2(m)\), is derived and shown to be the sum of basic reproduction numbers of the model when each host is isolated with an arthropod vector. It is shown that the disease will persist in all hosts as long as it persists in one host. Moreover, the overall basic reproduction number increases with respect to the host and that bringing the basic reproduction number of each isolated host below unity in each host is not sufficient to eradicate the disease in all hosts. This is a type of “amplification effect,” that is, for the considered vector-borne zoonoses, the increase in host diversity increases the basic reproduction number and therefore the disease burden.     

Spasmolytic and anti-inflammatory effects of constituents from Hertia cheirifolia

A sesquiterpenoid Bakkenolide (1), and two steroids, (3β, 22E)-Stigmasta-5, 22-diène-3-ol (Stigmasterol) (2) and stigmasterol 3β-glucoside (3), isolated from the Hertia cheirifolia (L.) chloroform extract, were evaluated respectively for their spasmolytic and anti-inflammatory activities. We note that these natural products were isolated and purified for the first time from the specie Hertia cheirifolia. Their structures have been established by spectroscopy (1 and 2D NMR experiences) and mass spectrometry. Chloroform-, ethyl acetate- and methanol-extracts were also tested for their spasmolytic and anti-inflammatory activities. Spasmolytic and anti-inflammatory screening were based respectively on the contractile response effects on rat isolated smooth muscles and on the dose-related carrageenan induced paw edema in rats. screening of the crude extracts showed spasmolytic and anti-inflammatory positive results. The antispasmodic effect of Bakkenolide was found in the same range as that of Alverine, a standard musculotropic spasmolytic agent.     

Date stones of Phoenix dactylifera and jujube shells of Ziziphus lotus as potential biosorbents for anionic dye removal

This study investigated the biosorption of Congo Red (CR) from aqueous solution by Date stones (DS) of Phoenix dactylifera and jujube shells (JS) of Ziziphus lotus. Batch operations were carried out in the liquid phase to observe the effect of various experimental parameters such as contact time, pH, temperature, and initial dye concentration on removal of CR. The characteristics of the DS and JS were also examined by Fourier transform infrared analysis. The biosorption data of CR on DS and JS samples were well fitted with the Langmuir isotherm and pseudo-second kinetics model with a maximum biosorption amount of 45.08 mg g^?1 for DS and 59.55 mg g^?1 for JS at pH = 4, temperature of 50°C, and an initial concentration of 100–800 mg L^?1 after 90 minutes of contact time. The outcomes indicated that DS and JS can be used as a good low-cost alternative for the treatment of effluents containing CR in water.