Reproductive characteristics that favor invasiveness in Leonotis nepetifolia (L.) R. Br.

Reproductive systems are life attributes important in defining the demography and genetic constitution of invasive alien species populations. We describe the phenology, floral behavior and floral visitors in Mexican populations of Leonotis nepetifolia considered invasive in America, Asia and Oceania. The mating system was determined through pollination experiments and, with a morphological analysis of flowers (outcrossing index, OCI) and pollen/ovule ratio, the breeding system was evaluated. Germination of 1 and 2-year-old seeds was tested to assess the potential characteristics of germination. Leonotis nepetifolia was reproductive for 7 months (June to December) and tended towards a specific season during autumn. Anthesis lasted 36 hr with protogyny and no hercogamy, with floral visitors of Apodiformes, Hymenoptera, Lepidoptera and Thysanoptera. Pollination experiments indicated a mixed mating system, whereas the OCI and the pollen/ovule ratio pointed towards a facultative xenogamous breeding system. Seed production was high (1,445 ± 132 seeds/plant); the seeds had potential longevity and were neutral photoblastic. One-year-old seeds germinated slightly later ( = 2.6 ± 0.11 days) than 2-year-old seeds ( = 1.9 ± 0.02 days), both synchronously (IS_1yr = 0.88 ± 0.03 and IS_2yr = 0.82 ± 0.02). Germination percentage for 1-year-old seeds was lower (55.33 ± 4.40%) than that of 2-year-old seeds (94.18 ± 0.59%), suggesting a potential longevity of the seeds in an optimal environment. Reproductive characteristics, such as wide reproductive period, mixed breeding system, copious seed production, seeds with potential longevity, and quick and synchronic germination in different light conditions, favor the invasive capacity of Leonotis nepetifolia.     

Synthesis and biological evaluation of glucose conjugated phthalocyanine as a second-generation photosensitizer

Photodynamic therapy (PDT) is a treatment method using light and photosensitizers (PSs), which is categorized as a non-invasive surgery treatment for cancers. When the tumor is exposed to a specific light, the PSs become active and generate reactive oxygen species (ROS), mainly singlet oxygen which kills nearby cancer cells. PDT is becoming more widely recognized as a valuable treatment option for localized cancers and pre-cancers of skin as it has no long-term effects on the patient. But, due to the limited penetration rate of light into the skin and other organs, PDT can’t be used to treat large cancer cells or cancer cells that have grown deeply into the skin or other organs. Hence, in this study, our focus centers on synthesizing glucose-conjugated phthalocyanine (Pc) compatible with near-infrared (NIR) irradiation as second-generation photosensitizer, so that PDT can be used in a wider range to treat cancers without obstacles.     

LncRNA HOXB-AS1 promotes cell growth in multiple myeloma via FUT4 mRNA stability by ELAVL1

Multiple myeloma (MM) is defined as the second most common hematological tumor in the globe. Long noncoding RNAs (lncRNAs) have been reported to play stimulative or suppressive role in the progression of different carcinomas. The investigation of lncRNAs in MM is still inadequate. LncRNA HOXB cluster antisense RNA 1 (HOXB-AS1) was once revealed to facilitate glioma progression by affecting cellular activities of glioma cells. However, whether HOXB-AS1 participates in the development of MM still remains an enigma. In this study, we unveiled that HOXB-AS1 was highly expressed in MM and loss-of-function assays certified that HOXB-AS1 obstruction suppressed MM cell proliferation, and stimulated cell apoptosis. In addition, HOXB-AS1 could modulate fucosyltransferase 4 (FUT4) and FUT4-mediated Wnt/β-catenin pathway. In subsequence, it was observed from mechanism assays that HOXB-AS1 enhanced the interaction between ELAVL1 and FUT4 so as to stabilize FUT4 messenger RNA. In the end, rescue experiments affirmed that HOXB-AS1 affected the cell growth through FUT4 in MM. In conclusion, the whole modulation mechanism of HOXB-AS1/ELAVL1/FUT4 axis in MM was validated in this study, which suggested that HOXB-AS1 might function as a powerful and promising therapeutic biomarker for the clinical treatment of patients with MM.     

N-phenyl ureidobenzenesulfonates,a novel class of promising human dihydroorotate dehydrogenase inhibitors

N-phenyl ureidobenzenesulfonates (PUB-SOs) is a new class of promising anticancer agents inducing replication stresses and cell cycle arrest in S-phase. However, the pharmacological target of PUB-SOs was still unidentified. Consequently, the objective of the present study was to identify and confirm the pharmacological target of the prototypical PUB-SO named 2-ethylphenyl 4-(3-ethylureido)benzenesulfonate (SFOM-0046) leading to the cell cycle arrest in S-phase. The antiproliferative and the cytotoxic activities of SFOM-0046 were characterized using the NCI-60 screening program and its fingerprint was analyzed by COMPARE algorithm. Then, human dihydroorotate dehydrogenase (hDHODH) colorimetric assay, uridine rescuing cell proliferation and molecular docking in the brequinar-binding site were performed. As a result, SFOM-0046 exhibited a mean antiproliferative activity of 3.5 μM in the NCI-60 screening program and evidenced that leukemia and colon cancer cell panels were more sensitive to SFOM-0046. COMPARE algorithm showed that the SFOM-0046 cytotoxic profile is equivalent to the ones of brequinar and dichloroallyl lawsone, two inhibitors of hDHODH. SFOM-0046 inhibited the hDHODH in the low nanomolar range (IC₅₀ = 72 nM) and uridine rescued the cell proliferation of HT-29, HT-1080, M21 and MCF-7 cancer cell lines in the presence of SFOM-0046. Finally, molecular docking showed a binding pose of SFOM-0046 interacting with Met43 and Phe62 present in the brequinar-binding site. In conclusion, PUB-SOs and notably SFOM-0046 are new small molecules hDHODH inhibitors triggering replication stresses and S-phase arrest.     

The tRNA A76 Hydroxyl Groups Control Partitioning of the tRNA-dependent Pre- and Post-transfer Editing Pathways in Class I tRNA Synthetase

Aminoacyl-tRNA synthetases catalyze ATP-dependent covalent coupling of cognate amino acids and tRNAs for ribosomal protein synthesis. Escherichia coli isoleucyl-tRNA synthetase (IleRS) exploits both the tRNA-dependent pre- and post-transfer editing pathways to minimize errors in translation. However, the molecular mechanisms by which tRNA^Ile organizes the synthetic site to enhance pre-transfer editing, an idiosyncratic feature of IleRS, remains elusive. Here we show that tRNA^Ile affects both the synthetic and editing reactions localized within the IleRS synthetic site. In a complex with cognate tRNA, IleRS exhibits a 10-fold faster aminoacyl-AMP hydrolysis and a 10-fold drop in amino acid affinity relative to the free enzyme. Remarkably, the specificity against non-cognate valine was not improved by the presence of tRNA in either of these processes. Instead, amino acid specificity is determined by the protein component per se, whereas the tRNA promotes catalytic performance of the synthetic site, bringing about less error-prone and kinetically optimized isoleucyl-tRNA^Ile synthesis under cellular conditions. Finally, the extent to which tRNA^Ile modulates activation and pre-transfer editing is independent of the intactness of its 3′-end. This finding decouples aminoacylation and pre-transfer editing within the IleRS synthetic site and further demonstrates that the A76 hydroxyl groups participate in post-transfer editing only. The data are consistent with a model whereby the 3′-end of the tRNA remains free to sample different positions within the IleRS·tRNA complex, whereas the fine-tuning of the synthetic site is attained via conformational rearrangement of the enzyme through the interactions with the remaining parts of the tRNA body.     

Dosimetric evaluation of Gafchromic EBT2 film for breast intraoperative electron radiotherapy verification

PurposeQuality assurance (QA) is one of the most important issues that should be addressed for intraoperative electron radiotherapy (IOERT), which is not benefiting from image-based treatment planning system. The aim of this study is to evaluate the dosimetric characteristics of Gafchromic EBT2 film for breast IOERT QA procedure.MethodsDue to the fact that some dedicated accelerators are being used for IOERT, dependence of the film response to energy, field size, dose rate and incidence angle of electron beam from the LIAC IOERT accelerator was studied. Then, film response curve to breast IOERT doses was obtained and its accuracy was evaluated and justified through comparison to the results of ionometric dosimetry.ResultsThe results of this study indicated that there are no significant differences between the film responses at different energies of 6, 8, 10 and 12 MeV (P-value = 0.99). Similarly, no field size dependency was found when evaluating the response of the film to different field sizes ranging from 4 to 10 cm (P-value = 0.94). Film response was found to be independent of the dose rate of intraoperative electron beam (P-value = 0.12). Film response variations with changing the beam incidence angle were not significant (P-value > 0.8). Calibration curve at the dose range of 8–24 Gy had an acceptable accuracy. The difference between the results of film dosimetry and ionometric dosimetry was around 5% which was in agreement with the results of dose uncertainty estimation.ConclusionThe EBT2 film was found to be a potentially appropriate tool for breast IOERT verification.     

Solution Structure of the HIV-1 Intron Splicing Silencer and Its Interactions with the UP1 Domain of Heterogeneous Nuclear Ribonucleoprotein (hnRNP) A1

Splicing patterns in human immunodeficiency virus type 1 (HIV-1) are maintained through cis regulatory elements that recruit antagonistic host RNA-binding proteins. The activity of the 3′ acceptor site A7 is tightly regulated through a complex network of an intronic splicing silencer (ISS), a bipartite exonic splicing silencer (ESS3a/b), and an exonic splicing enhancer (ESE3). Because HIV-1 splicing depends on protein-RNA interactions, it is important to know the tertiary structures surrounding the splice sites. Herein, we present the NMR solution structure of the phylogenetically conserved ISS stem loop. ISS adopts a stable structure consisting of conserved UG wobble pairs, a folded 2X2 (GU/UA) internal loop, a UU bulge, and a flexible AGUGA apical loop. Calorimetric and biochemical titrations indicate that the UP1 domain of heterogeneous nuclear ribonucleoprotein A1 binds the ISS apical loop site-specifically and with nanomolar affinity. Collectively, this work provides additional insights into how HIV-1 uses a conserved RNA structure to commandeer a host RNA-binding protein.     

Genetic diversity of the threatened Chinese endemic plant,Sinowilsonia henryi Hemsi. (Hamamelidaceae), revealed by inter-simple sequence repeat (ISSR) markers

Sinowilsonia henryi Hemsi., the only representative of the monotypic genus Sinowilsonia Hemsi. (Hamamelidaceae), is a threatened plant endemic to China with high phylogenetical, ecological and economical values. In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic diversity and differentiation of 214 individuals sampled from 14 populations. Fifteen selected primers yielded a total of 178 bright and discernible bands. The genetic diversity was low at the population level (h = 0.1025; I = 0.1506; PPL = 26.7%), but quite high at the species level (h = 0.2449; I = 0.3690; PPL = 72.5%). In line with the limited gene flow (N_m = 0.3537), the hierarchical analysis of molecular variance (AMOVA) revealed pronounced genetic differentiation among populations (Φ_ST = 0.6639). Furthermore, the Mantel test revealed a significant correlation between genetic and geographic distances among populations (r = 0.688, P = 0.001), indicating the role of geographic isolation in shaping its present population genetic structure. The present patterns of genetic diversity of S. henryi were assumed to result largely from its evolutionary history and geographic factors. Based on these findings, conservation strategies were proposed to preserve this threatened plant.