Discovery of Four New Compounds from Macropanax membranifolius and Their Cytotoxic Activity

A phytochemical investigation of the methanolic extract of the Macropanax membranifolius C.B. Shang leaves led to the isolation of three new flavans, (2R,3R)-4′-O-methylcatechin 5-O-β-D-glucopyranoside ( 1 ), (2S,3S)-4′-O-methylcatechin 5-O-β-D-glucopyranoside ( 2 ), (2S,3R)-4′-O-methylcatechin 5-O-β-D-glucopyranoside ( 3 ), one new triterpene glycoside 3-O-β-D-xylopyranosyl-(1→6)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-oleanolic acid 28-O-β-D-glucopyranoside ( 4 ), together with nine known compounds ( 5 - 13 ). Their chemical structures were elucidated based on HR-ESI-MS, NMR spectroscopic data. The absolute configurations of compounds 1 – 3 were established by electronic circular dichroism (ECD) spectra. At concentration of 20 μM, compounds 1 – 13 showed the percentages of dead cell in the range of 2.14 % to 33.61 % against KB, HepG2, HL60, P388, HT29, and MCF7 cancerous cell lines by SRB assay.     

The influence of host and bacterial genotype on the development of disseminated disease with Mycobacterium tuberculosis

The factors that govern the development of tuberculosis disease are incompletely understood. We hypothesized that some strains of Mycobacterium tuberculosis (M. tuberculosis) are more capable of causing disseminated disease than others and may be associated with polymorphisms in host genes responsible for the innate immune response to infection. We compared the host and bacterial genotype in 187 Vietnamese adults with tuberculous meningitis (TBM) and 237 Vietnamese adults with uncomplicated pulmonary tuberculosis. The host genotype of tuberculosis cases was also compared with the genotype of 392 cord blood controls from the same population. Isolates of M. tuberculosis were genotyped by large sequence polymorphisms. The hosts were defined by polymorphisms in genes encoding Toll-interleukin 1 receptor domain containing adaptor protein (TIRAP) and Toll-like receptor-2 (TLR-2). We found a significant protective association between the Euro-American lineage of M. tuberculosis and pulmonary rather than meningeal tuberculosis (Odds ratio (OR) for causing TBM 0.395, 95% confidence intervals (C.I.) 0.193-0.806, P = 0.009), suggesting these strains are less capable of extra-pulmonary dissemination than others in the study population. We also found that individuals with the C allele of TLR-2 T597C allele were more likely to have tuberculosis caused by the East-Asian/Beijing genotype (OR = 1.57 [95% C.I. 1.15-2.15]) than other individuals. The study provides evidence that M. tuberculosis genotype influences clinical disease phenotype and demonstrates, for the first time, a significant interaction between host and bacterial genotypes and the development of tuberculosis.     

Native bacterial endophytes promote host growth in a species-specific manner; phytohormone manipulations do not result in common growth responses

Background

All plants in nature harbor a diverse community of endophytic bacteria which can positively affect host plant growth. Changes in plant growth frequently reflect alterations in phytohormone homoeostasis by plant-growth-promoting (PGP) rhizobacteria which can decrease ethylene (ET) levels enzymatically by 1-aminocyclopropane-1-carboxylate (ACC) deaminase or produce indole acetic acid (IAA). Whether these common PGP mechanisms work similarly for different plant species has not been rigorously tested.

Methodology/ Principal Findings

We isolated bacterial endophytes from field-grown Solanum nigrum; characterized PGP traits (ACC deaminase activity, IAA production, phosphate solubilization and seedling colonization); and determined their effects on their host, S. nigrum, as well as on another Solanaceous native plant, Nicotiana attenuata. In S. nigrum, a majority of isolates that promoted root growth were associated with ACC deaminase activity and IAA production. However, in N. attenuata, IAA but not ACC deaminase activity was associated with root growth. Inoculating N. attenuata and S. nigrum with known PGP bacteria from a culture collection (DSMZ) reinforced the conclusion that the PGP effects are not highly conserved.

Conclusions/ Significance

We conclude that natural endophytic bacteria with PGP traits do not have general and predictable effects on the growth and fitness of all host plants, although the underlying mechanisms are conserved.     

Mechanism of skin pigmentation

Melanin is a pigment that plays an important role in providing coloration and protecting human skin from the harmful effects of UV light radiation. Human skin color is determined by the type and amount of melanins that are synthesized and deposited within the melanosomes. In addition, the transfer of these specialized membrane-bound organelles from melanocytes to surrounding keratinocytes also plays a role in dictating human skin color. In order to investigate the principle features of skin pigmentation, the origin, function, and production ability of melanin should be highly understood in terms of biological and pathophysiological aspects. Furthermore, a deep understanding of melanin synthesis will also contribute to cosmetics and drugs development. In this review, the processes of melanin biosynthesis, such as survival, proliferation, and differentiation of melanin cells, as well as the biological regulation of human pigmentation were described.     

Fishborne Trematode Metacercariae Detected in Freshwater Fish from Vientiane Municipality and Savannakhet Province, Lao PDR

Freshwater fish from Vientiane Municipality and Savannakhet Province, Lao PDR were examined by the muscle compression and artificial digestion methods to know the infection status with trematode metacercariae. In the fish from Savannakhet, 2 species of metacercariae, Opisthorchis viverrini and Haplorchis taichui, were detected. O. viverrini metacercariae were found in 6 species of fish, Puntius brevis, Hampala dispar, Esomus metallicus, Mystacoleucus marginatus, Puntioplites falcifer, and Cyclocheilichthys armatus. H. taichui metacercariae were detected in 3 species of fish, P. brevis, P. falcifer, and M. marginatus. In the fish from Vientiane, 4 species of metacercariae, O. viverrini, H. taichui, Haplorchis yokogawai, and Centrocestus formosanus, were detected. Among them, O. viverrini metacercariae were found in 7 species of fish, Onychostoma elongatum, C. armatus, H. dispar, P. brevis, Cyclocheilichthys repasson, Osteochilus hasseltii, and Hypsibarbus lagleri. The metacercariae of H. taichui were detected in 6 species of fish, C. repasson, O. elongatum, C. armatus, H. dispar, Labiobarbus leptocheila, and Cirrhinus molitorella. The metacercariae of H. yokogawai were found in 9 species of fish, C. repasson, O. elongatum, C. armatus, H. dispar, Labiobarbus leptocheila, O. hasseltii. C. molitorella, Hypsibarbus wetmorei, and H. lagleri. The metacercariae of C. formosanus were detected in 4 species of fish, C. repasson, P. brevis, O. hasseltii, and C. molitorella. From these results, it is confirmed that fishborne trematode metacercariae, i.e. O. viverrini, H. taichui, H. yokogawai and C. formosanus, are prevalent in various species of freshwater fish from Savannakhet Province and Vientiane Municipality, Lao PDR.     

In nucleoli, the steady state of nucleolar proteins is leptomycin B-sensitive

Background information. The nucleolus is a dynamic structure. It has been demonstrated that nucleolar proteins rapidly associate with and dissociate from nucleolar components in continuous exchanges with the nucleoplasm using GFP (green fluorescent protein)‐tagged proteins. However, how the exchanges within one nucleolus and between nucleoli within the nuclear volume occurred is still poorly understood. Results. The movement of PAGFP (photoactivatable GFP)‐tagged proteins that become visible after photoactivation can be followed. In the present study, we establish the protocol allowing quantification of the traffic of PAGFP‐tagged nucleolar proteins in nuclei containing two nucleoli. The traffic in the activated area, at the periphery of the activated area and to the neighbouring nucleolus is measured. Protein B23 is rapidly replaced in the activated area, and at the periphery of the activated area the steady state suggests intranucleolar recycling of B23; this recycling is LMB (leptomycin B)‐sensitive. The pool of activated B23 is equally distributed in the volume of the two nucleoli within 2 min. The three‐dimensional distribution of the proteins Nop52 and fibrillarin is less rapid than that of B23 but is also LMB‐sensitive. In contrast, traffic of fibrillarin from the nucleoli to the CB (Cajal body) was not modified by LMB. Conclusions. We propose that the steady state of nucleolar proteins in nucleoli depends on the affinity of the proteins for their partners and on intranucleolar recycling. This steady state can be impaired by LMB but not the uptake in the neighbouring nucleolus or the CB.     

Assessment of the diagnostic accuracy and relevance of a novel ELISA system developed for seroepidemiologic surveys of Helicobacter pylori infection in African settings

Beside diagnostic uncertainties due to the lack of a perfect gold standard test for Helicobacter pylori infection, the diagnosis and the prevalence estimation for this infection encounter particular challenges in Africa including limited diagnostic tools and specific genetic background. We developed and evaluated the accuracy of an enzyme-linked immunosorbent assay (ELISA) system tailored for H. pylori genetics in Africa (HpAfr-ELISA). Strains belonging to main genetic populations infecting Africans were exploited as sources for whole-cell antigens to establish in-house the ELISA system. A phase II unmatched case-control study explored the diagnostic accuracy of the HpAfr-ELISA using a training set of samples collected from dyspeptic patients from Kinshasa, the Democratic Republic of Congo (DRC) who had been tested with invasive standard tests (i.e., histology, culture, and rapid urease test) in 2017. Then the assay was cross-validated through a community-based survey assessing the prevalence of H. pylori and associated factors in 425 adults from Mbujimayi, DRC in 2018. Bayesian inferences were used to deal with statistical uncertainties of estimates (true prevalence, sensitivity, and specificity) in the study population. At its optimal cut-off-value 20.2 U/mL, the assay achieved an estimated sensitivity of 97.6% (95% credible interval [95%CrI]: 89.2; 99.9%) and specificity of 90.5% (95%CrI: 78.6; 98.5). Consistent outcomes obtained at repeated tests attested the robustness of the assay (negative and positive agreements always > 70%). The true prevalence of H. pylori was estimated 53.8% [95%CrI: 42.8; 62.7%]. Increasing age (adjusted odds ratio [aOR] > 1.0 [95% confidence interval (CI): > 1.0; 1.1]; p<0.001), overcrowding households (aOR = 3.2 [95%CI: 2.0; 5.1]; p<0.001), and non-optimal hand hygiene (aOR = 4.5 [95%CI: 2.0; 11.4]; p = 0.001) were independently associated with the H. pylori-seropositivity. The novel ELISA system has demonstrated good diagnostic accuracy and potential usefulness for management and mitigation strategies for H. pylori infection in African settings.