Environmentally-Friendly Pesticidal Activities of Callicarpa and Karomia Essential Oils from Vietnam and Their Microemulsions

There is an ongoing interest to identify alternative pesticidal agents to avoid the chronic problems associated with synthetic pesticides. Essential oils have shown promise as botanical pest control agents. In the present study, the essential oils of four members of the Lamiaceae (Callicarpa candicans, C. erioclona, C. macrophylla, and Karomia fragrans; Vietnamese names: Nàng nàng, Tu châu lông mem, Tu châu lá to and Cà diện, respectively), obtained from wild populations in Vietnam, have been obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The essential oils were formulated into microemulsions and the essential oils and their microemulsions were screened for mosquito larvicidal activity against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and for molluscicidal activity against Pomacea canaliculata. Atractylone and (E)-caryophyllene dominated the volatiles of C. candicans (CCEO) and C. erioclona (CEEO), while the major component in C. macrophylla (CMEO) and K. fragrans (KFEO) was (E)-caryophyllene. The essential oils and microemulsions of both C. candicans and C. erioclona exhibited excellent larvicidal activity against all three mosquito species (Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus) with LC₅₀ values <10 μg/mL. Additionally, the larvicidal activity of the microemulsions were significantly improved compared with their free essential oils, especially for C. candicans and C. erioclona. All four essential oils and their microemulsions showed excellent molluscicidal activity with LC₅₀ <10 μg/mL. In most cases, the essential oils and microemulsions showed greater pesticidal activity against target organisms than the non-target freshwater fish, Oreochromis niloticus. The in silico studies on physicochemical and ADMET properties of the major components in the studied essential oils were also investigated and most of the compounds possessed a favorable ADMET profile. Computational modeling studies of the studied compounds demonstrated a favorable binding interaction with the mosquito odorant-binding protein target and support atractylone, β-selinene, and caryophyllene oxide as potential inhibitors. Based on the observed pesticidal activities of the essential oils and their microemulsions, the Callicarpa species and K. fragrans should be considered for potential cultivation and further exploration as botanical pesticidal agents.     

Novel (E)-3-(3-Oxo-4-substituted-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-N-hydroxypropenamides as Histone Deacetylase Inhibitors: Design,Synthesis and Bioevaluation

Herein, we report the design, synthesis and evaluation of novel (E)-3-(3-oxo-4-substituted-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-N-hydroxypropenamides ( 4 a – i , 7 a – g ) targeting histone deacetylases. Three human cancer cell lines were used to test the cytotoxicity of the synthesized compounds (SW620, colon; PC-3, prostate; NCI−H23, lung cancer); inhibitory activity towards HDAC; anticancer activity; as well as their impact on the cell cycle and apoptosis. As a result, compounds 4 a – i bearing the alkyl substituents seemed to be less potent than the benzyl-containing compounds 7 a – g in all biological assays. Compounds 7 e – f were found to be the most active HDAC inhibitors with IC₅₀ of 1.498±0.020 μM and 1.794±0.159 μM, respectively. In terms of cytotoxicity and anticancer assay, 7 e and 7 f also showed good activity with IC₅₀ values in the micromolar range. In addition, the cell cycle and apoptosis of SW620 were affected by compound 7 f in almost a similar manner to that of reference compound SAHA. Docking assays were carried out for analysis the binding mode and selectivity of this compound toward 8 HDAC isoforms. Overall, our data confirmed that the inhibition of HDAC plays a pivotal role in their anticancer activity.     

Application of an Escherichia coli triple reporter strain for at-line monitoring of single-cell physiology during L-phenylalanine production

Biotechnological production processes are sustainable approaches for the production of biobased components such as amino acids for food and feed industry. Scale-up from ideal lab-scale bioreactors to large-scale processes is often accompanied by loss in productivity. This may be related to population heterogeneities of cells originating from isogenic cultures that arise due to dynamic non-ideal conditions in the bioreactor. To better understand this phenomenon, deeper insights into single-cell physiologies in bioprocesses are mandatory before scale-up. Here, a triple reporter strain (3RP) was developed by chromosomally integrating the fluorescent proteins mEmerald, CyOFP1, and mTagBFP2 into the L-phenylalanine producing Escherichia coli strain FUS4 (pF81_kan) to allow monitoring of growth, oxygen availability, and general stress response of the single cells. Functionality of the 3RP was confirmed in well-mixed lab-scale fed-batch processes with glycerol as carbon source in comparison to the strain without fluorescent proteins, leading to no difference in process performance. Fluorescence levels could successfully reflect the course of related process state variables, revealed population heterogeneities during the transition between different process phases and potentially subpopulations that exhibit superior process performance. Furthermore, indications were found for noise in gene expression as regulation strategy against environmental perturbation.     

Amino- and carboxy-terminal domains of the yeast Rab escort protein are both required for binding of Ypt small G proteins.

The Rab escort protein (REP) is an essential component of the heterotrimeric enzyme Rab geranylgeranyl transferase that modifies the carboxy-terminal cysteines of the Ras-like small G proteins belonging to the Rab/Ypt family. Deletions in the human CHM locus, encoding one of the two REPs known in humans, result in a retinal degenerative syndrome called choroideremia. The only known yeast homologue of the choroideremia gene product is encoded by an essential gene called MRS6. Besides three structurally conserved regions (SCRs) previously detected in the amino-terminal half of REPs and RabGDIs, three other regions in the carboxy-terminal domain (RCR 1-3) are here identified as being characteristic of REPs alone. We have performed the first mutational analysis of a REP protein to experimentally define the regions functionally important for Rab/Ypt protein binding, making use of the genetic system of the yeast Saccharomyces cerevisiae. This analysis has shown that the SCRs are necessary but not sufficient for Ypt1p binding by the yeast REP, the carboxy-terminal region also being required.     

The temperature-sensitive (ts) phenotype of a cold-passaged (cp) live attenuated respiratory syncytial virus vaccine candidate, designated cpts530, results from a single amino acid substitution in the L protein.

cpts530, a candidate live-virus vaccine, is an attenuated strain of human respiratory syncytial virus (RSV). It was derived by subjecting a cold-passaged (cp) strain of RSV to a single round of chemical mutagenesis. cpts530 is a temperature-sensitive (ts) mutant that is attenuated in mice and chimpanzees, and its ts phenotype exhibits a high level of stability during replication in both species. In the present study, the complete nucleotide sequence of cpts530 RSV was determined. The five mutations known to be present in the parent cpRSV were retained in its cpts530 derivative, and one additional nucleotide change was identified at nucleotide (nt) 10060, which resulted in a phenylalanine-to-leucine change at amino acid 521 in the large polymerase (L) protein. To determine if this single amino acid substitution was indeed responsible for the ts phenotype of cpts530, it was introduced alone or in combination with the cp mutations into the full-length cDNA clone of the wild-type A2 RSV. Analysis of infectious viruses recovered from mutant cDNAs indicated that this single mutation specified complete restriction of plaque formation of recombinant cp530 in HEp-2 cell monolayer cultures at 40 degrees C, and the level of temperature sensitivity was not influenced by the presence of the five cpRSV mutations. These findings identify the phenylalanine-to-leucine change at amino acid 521 in the L protein as the mutation that specifies the ts phenotype of cpts530. Furthermore, these findings illustrate the feasibility of using the cDNA-based recovery system to analyze and construct defined attenuated vaccine viruses.     

Immunogenicity of the Shigella flexneri Serotype Y (SFL124) Vaccine Strain Expressing Cloned Glucosyl Transferase Gene of Converting Bacteriophage SfX

The glucosyl transferase gene (gtr) from bacteriophage phage X (SfX) caused partial conversion of serotype Y (group antigen 3, 4) to X (group antigen 7, 8) when introduced into a candidate vaccine strain of Shigella flexneri serotype Y (SFL124). The gtr gene caused conversion of O-antigens but did not eliminate the adsorption of the corresponding phage SfX. The hybrid strain expressing both group antigens 7, 8 and 3, 4 showed 75% protection when immunized guinea pigs were challenged with a wild-type S. flexneri serotype X strain. No protection was observed against serotype Y challenge, although group antigen 3, 4 was detected in the LPS of the hybrid strain. This suggests the importance of O-antigen immunity in the host defense against shigellosis.     

Cellular Lipid and Fatty Acid Compositions of Burkholderia pseudomallei Strains Isolated from Human and Environment in Viet Nam

Viet nam is known as an endemic area of melioidosis but its etiologic agent originated in Viet nam was not extensively studied. For the first time, we analyzed the cellular lipid and fatty acid compositions of 15 Vietnamese isolates of Burkholderia pseudomallei, 10 from humans and 5 from the environment. Cellular lipid compositions were analyzed by two-dimensional thin-layer chromatography on silica gel G plates. Cellular fatty acid methyl esters were analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major lipids in all the isolates were phosphatidylglycerol (PG), two forms of phosphatidylethanolamine (PE-1 and PE-2), and two forms of ornithine-containing lipid (OL-1 and OL-2). PE-1 contained non-hydroxy fatty acids at both sn-1 and ?2 positions, while PE-2 possessed 2-hydroxy fatty acids and non-hydroxy fatty acids in a ratio of 1: 1. Since snake venom phospholipase A₂ digestion of PE-2 liberated 2-hydroxy fatty acids, it was confirmed that these acids are at the sn-2 position of glycerol moiety. In both OL-1 and OL-2, amide-linked fatty acid was 3-hydroxy palmitic acid (3-OH-C16: 0), while ester-linked fatty acids were non-hydroxy acids in OL-1 and 2-hydroxy acids in OL-2. The total cellular fatty acid compositions of the test strains were characterized by the presence of 2-hydroxy palmitic (2-OH-C16: 0), 2-hydroxy hexadecenoic (2-OH-C16: 1), 2-hydroxy octadecenoic (2-OH-C18: 1), 2-hydroxy methylene octadecanoic (2-OH-C19CPA), 3-hydroxy myristic (3-OH-C14: 0) and 3-hydroxy palmitic (3-OH-C16: 0) acids. There were significant differences in the concentration of hexadecenoic (C16: 1), methylene hexadecanoic (C17CPA), octadecenoic (C18: 1) and methylene octadecanoic (C19CPA) acids among the Vietnamese isolates of B. pseudomallei. However, no significant difference was observed in cellular lipid and fatty acid components between strains of human and environmental origins.     

DNA content in the genus Xenopus

Nuclear DNA amounts were determined by cytofluorometry for twelve species and subspecies of the genus Xenopus. Absolute values, in pg per nucleus, were obtained by direct comparison with human lymphocyte nuclei. The lowest DNA amount (3.55 pg) was found in X. tropicalis, which possess only 20 chromosomes, and the highest (16.25 pg), in the hexaploid X. ruwenzoriensis, with 108 chromosomes. The two recently discovered tetraploid species, X. sp.n. and X. vestitus have, respectively, 12.57 and 12.83 pg of DNA. Among the species and subspecies with 36 chromosomes, the DNA content ranges from 6.35 to 8.45 pg.     

A modelized distribution of actomyosin interactions in the vertebrate cardiac muscle

Preliminary assumption of this model is that interactions between actin and myosin presupposes an exact three-dimensional geometrical correspondence between sites, due to the very short time constants present under physiological conditions. Only small and controlled torsions of the actin filaments are accepted. The model uses geometrical information concerning orientations and dimensions of myosin crossbridges and actin monomeres to modelize the distribution of their inter-actions. An orientation map of actin sites in the cross-section perpendicular to the filament axis is proposed, adapted to the specific filament array of vertebrate muscle. Orientation of myosin crossbridges follows Luther's rules. According to the model, any interaction between actin and myosin implies the superimposition of their respective cross-sectional planes. The axial length of actin monomere is 55 A; the distance between two crossbridges along the myosin filament axis is 143 A. The following properties are derived: 1) The shortening step of the sliding actin filament must be a multiple of 11 A (highest common factor). Taking into account the staggered disposition of the two actin strands and the presence of two heads for each cross-bridge, the most probable value for this shortening step is equal to 99 A. A specific scheme is proposed to describe the shortening process. The behavior of the modelized crossbridge does not need any elastic structure--2) Planes situated at 715 A (lowest common multiple) of actin and myosin coinciding planes are also in coincidence. In a hemi-sarcomere the maximal number of these planes, referred to as simultaneously activable planes, is 10 (20 if both myosin heads are considered). The proportion of interactions authorized by the site orientations is 1/12. In the model, the concept of randomly recruited crossbridges is replaced by a discretized recruitment, based on geometrical properties at an ultrastructural level. The proposed distribution is homogeneous: it can be extended radially in the sarcomere and authorizes the actin filament sliding in the whole physiological range under the control of a dual activation function, reproducing Ca++ temporal and spatial distribution.