Comparison of direct esterification and transesterification of fructose by Candida antartica lipase

Fructose oleates synthesis was performed in a batch reactor by trans- or direct esterification. An immobilized lipase from Candida antartica was used. When a solvent was used, 65% and 46% of conversion of fructose were obtained by transesterification and direct esterification, respectively. These two reactions were also compared in a solvent-free melt. Both in molten media and with cosolvent, two isomeric forms of fructose oleates were produced.     

The influence of dietary lipid composition on liver mitochondria from mice following 1 month of calorie restriction

To investigate the role mitochondrial membrane lipids play in the actions of CR (calorie restriction), C57BL/6 mice were assigned to four groups (control and three 40% CR groups) and the CR groups were fed diets containing soya bean oil (also in the control diet), fish oil or lard. The fatty acid composition of the major mitochondrial phospholipid classes, proton leak and H₂O₂ production were measured in liver mitochondria following 1 month of CR. The results indicate that mitochondrial phospholipid fatty acids reflect the PUFA (polyunsaturated fatty acid) profile of the dietary lipid sources. CR significantly decreased the capacity of ROS (reactive oxygen species) production by Complex III but did not markedly alter proton leak and ETC (electron transport chain) enzyme activities. Within the CR regimens, the CR-fish group had decreased ROS production by both Complexes I and III, and increased proton leak when compared with the other CR groups. The CR-lard group showed the lowest proton leak compared with the other CR groups. The ETC enzyme activity measurements in the CR regimens showed that Complex I activity was decreased in both the CR-fish and CR-lard groups. Moreover, the CR-fish group also had lower Complex II activity compared with the other CR groups. These results indicate that dietary lipid composition does influence liver mitochondrial phospholipid composition, ROS production, proton leak and ETC enzyme activities in CR animals.     

Arthropod toxins inhibiting Ca2+ and Na+ channels prevent AC‐1001 H3 peptide‐induced apoptosis

Peptide toxins of arthropods are one of the potential sources of bioactive substances. Toxins are able to bind to calcium channels and block them. Ca²⁺ ions play an important role in many cell processes, in particular, in apoptosis. In this work, we study the effect of some arthropod toxins on intracellular processes associated with the induction of apoptosis. Synthetic analogs of U₅‐scytotoxin‐Sth1a, ω‐hexatoxin‐Hv1a, ω‐theraphotoxin‐Hhn2a, and μ‐agatoxin‐Aa1a toxins—inhibitors of calcium L, P, and Q channels and sodium channels were used in the study. Apoptosis was induced by AC‐1001 H3 peptide. We study the effect of toxins on the level of apoptosis, ROS, mitochondrial potential, GSH, and ATP in CHO‐K1 cells. We show that all the tested toxins are able to dose dependently block the induction of apoptosis triggered by AC‐1001 H3 and reduce the level of natural apoptosis in CHO‐K1 cells. Cell incubation with apoptosis inducer AC‐1001 H3 in the presence and absence of toxins causes an increase in the intracellular concentrations of ROS, ATP, and mitochondrial potential and decreases the GSH concentration. The present study reveals the antiapoptotic effect of a number of arthropod peptide toxins. The toxins studied can represent a novel approach used in the treatment of pathologies associated with the activation of apoptotic mechanisms.     

A Bacterial Phosphatase-Like Enzyme of the Malaria Parasite Plasmodium falciparum Possesses Tyrosine Phosphatase Activity and Is Implicated in the Regulation of Band 3 Dynamics during Parasite Invasion

Eukaryotic parasites of the genus Plasmodium cause malaria by invading and developing within host erythrocytes. Here, we demonstrate that PfShelph2, a gene product of Plasmodium falciparum that belongs to the Shewanella-like phosphatase (Shelph) subfamily, selectively hydrolyzes phosphotyrosine, as shown for other previously studied Shelph family members. In the extracellular merozoite stage, PfShelph2 localizes to vesicles that appear to be distinct from those of rhoptry, dense granule, or microneme organelles. During invasion, PfShelph2 is released from these vesicles and exported to the host erythrocyte. In vitro, PfShelph2 shows tyrosine phosphatase activity against the host erythrocyte protein Band 3, which is the most abundant tyrosine-phosphorylated species of the erythrocyte. During P. falciparum invasion, Band 3 undergoes dynamic and rapid clearance from the invasion junction within 1 to 2 s of parasite attachment to the erythrocyte. Release of Pfshelph2 occurs after clearance of Band 3 from the parasite-host cell interface and when the parasite is nearly or completely enclosed in the nascent vacuole. We propose a model in which the phosphatase modifies Band 3 in time to restore its interaction with the cytoskeleton and thus reestablishes the erythrocyte cytoskeletal network at the end of the invasion process.     

Chapter 15: Disease Gene Prioritization

Disease-causing aberrations in the normal function of a gene define that gene as a disease gene. Proving a causal link between a gene and a disease experimentally is expensive and time-consuming. Comprehensive prioritization of candidate genes prior to experimental testing drastically reduces the associated costs. Computational gene prioritization is based on various pieces of correlative evidence that associate each gene with the given disease and suggest possible causal links. A fair amount of this evidence comes from high-throughput experimentation. Thus, well-developed methods are necessary to reliably deal with the quantity of information at hand. Existing gene prioritization techniques already significantly improve the outcomes of targeted experimental studies. Faster and more reliable techniques that account for novel data types are necessary for the development of new diagnostics, treatments, and cure for many diseases.

This article is part of the “Translational Bioinformatics" collection for PLOS Computational Biology.

What to Learn in This Chapter

• Identification of specific disease genes is complicated by gene pleiotropy, polygenic nature of many diseases, varied influence of environmental factors, and overlying genome variation.
• Gene prioritization is the process of assigning likelihood of gene involvement in generating a disease phenotype. This approach narrows down, and arranges in the order of likelihood in disease involvement, the set of genes to be tested experimentally.
• The gene “priority" in disease is assigned by considering a set of relevant features such as gene expression and function, pathway involvement, and mutation effects.
• In general, disease genes tend to 1) interact with other disease genes, 2) harbor functionally deleterious mutations, 3) code for proteins localizing to the affected biological compartment (pathway, cellular space, or tissue), 4) have distinct sequence properties such as longer length and a higher number of exons, 5) have more orthologues and fewer paralogues.
• Data sources (directly experimental, extracted from knowledge-bases, or text-mining based) and mathematical/computational models used for gene prioritization vary widely.

     

I. Primexine development in Passiflora racemosa Brot.: overlooked aspects of development

Developmental stages during the tetrad period were examined in detail by transmission electron microscopy with an emphasis on substructure. Our purpose was to find out whether the sequence of sporoderm developmental events provides additional evidence for our recent hypothesis on the underlying cause of exine ontogeny as a sequence of self-assembling micellar mesophases initiated by genomically given physicochemical parameters. Osmiophilic globules encrusting the surface of postmeiotic microspores and tapetal cells are temporary prepattern units which come first. The second prepattern structures are highly ordered bundles of microfilaments and microtubules which determine the position of microspore surface invaginations and clusters of the glycocalyx inside them. The first glycocalyx units are microgranules which during the middle tetrad stage rearrange into radially oriented rod-like units. The latter form lens-like clusters of the glycocalyx-1, located inside the invaginations. These clusters predestine the position of the future luminae in the exine reticulum. The second glycocalyx layer is laid down as a continuous layer over the whole microspore surface and has similar substructure, that is radial rods. Glycocalyx-2 is a framework for procolumellae which appear at the late tetrad stage. Therefore, the sequence of substructural units in the primexine is: globules, microgranules, rod-like units, and layers of radially oriented rods tightly packed in the periplasmic space. This sequence corresponds to the first three mesophases of self-assembling micelles: spherical micelles, cylindrical micelles, and layers of hexagonally packed cylindrical micelles (middle mesophase). We observed the same sequence in other species during primexine development, and the findings of this study provide new evidence for our hypothesis.     

Pseudangularia gonzalezi n. sp. and Gibsonilepis swifti (Singh, 1952) n. g., n. comb. (Cestoda, Dilepididae) from the House Swift, Apus affinis (J.E. Gray) (Aves, Apodiformes) from Franceville, Republic of Gabon

Nine specimens of Apus affinis (J.E. Gray) were studied at Franceville, Haut-Ogooué Province, Republic of Gabon, for the presence of helminth parasites. Two cestode species of the family Dilepididae were recorded. Pseudangularia gonzalezi n. sp. is distinguished from the most similar species P. europaea Georgiev & Murai, 1993 by having elliptical cirrus-sac, longer vagina, longer rostellar sheath and greater diameter of suckers. An identification key to the species of the genus Pseudangularia Burt, 1938 is proposed. The present study is the first record of the genus Pseudangularia in the Afrotropical Region. Our study confirms that, in dilepidids with vaginal sclerites from swifts, breaking off the cirrus after copulation is a frequent phenomenon. The genus Gibsonilepis n. g. is erected as monotypic for Vitta swifti Singh, 1952 (originally described from the same host species in India) and Gibsonilepis swifti n. comb. is proposed. Gibsonilepis n. g. is distinguished from Vitta Burt, 1938 by its highly elongate rostellum, rostellar sheath much bigger than rostellum, relatively small rostellar hooks possessing strongly developed guard, disc-shaped suckers with weak peripheral musculature and flat or convex central part, long and well-expressed neck, highly lobed two-winged ovary (lobes rounded) and presence of a band consisting of rows of spine-like microtriches along posterior margin of each proglottis. This is the first record of G. swifti in the Afrotropical Region. The separation of G. swifti from the genus Vitta (parasites of swallows) suggests that, contrary to previous opinions, no dilepidid genera are shared by Apodidae (swifts) and Hirundinidae (swallows).     

Purification and antibacterial activity of recombinant warnericin RK expressed in Escherichia coli

Warnericin RK is a small cationic peptide produced by Staphylococcus warneri RK. This peptide has an antimicrobial spectrum of activity almost restricted to the Legionella genus. It is a membrane-active peptide with a proposed detergent-like mechanism of action at high concentration. Moreover, the fatty acids content of Legionella was shown to modulate the peptide activity. In order to decipher the mode of action in details using solid-state NMR spectroscopy, large amount of an isotopic labeled peptide is required. Since it is less expensive to obtain such a peptide biologically, we report here methods to express warnericin RK in Escherichia coli with or without a fusion partner and to purify resulting recombinant peptides. The cDNA fragment encoding warnericin RK was synthesized and ligated into three expression vectors. Two fusion peptides, carrying polyhistidine tag in N- or C-terminal and a native peptide, without tag, were expressed in E. coli cells. Fusion peptides were purified, with a yield of 3 mg/l, by affinity chromatography and reverse-phase HPLC. The recombinant native peptide was purified using a two-step purification method consisting of a hydrophobic chromatography followed by a reverse-phase HPLC step with a yield of 1.4 mg/l. However, the anti-Legionella activity was lower for both tagged peptide probably because of structural modifications. So, the native recombinant peptide was preferentially chosen for ¹⁵N-labeling experiments. Our results suggest that the developed production and purification procedures will be useful in obtaining a large quantity of recombinant isotope-labeled warnericin RK for further studies.