Natural attenuation of Fukushima-derived radiocesium in soils due to its vertical and lateral migration

Processes of vertical and lateral migration lead to gradual reduction in contamination of catchment soil, particularly its top layer. The reduction can be considered as natural attenuation. This, in turn, results in a gradual decrease of radiocesium activity concentrations in the surface runoff and river water, in both dissolved and particulate forms. The purpose of this research is to study the dynamics of Fukushima-derived radiocesium in undisturbed soils and floodplain deposits exposed to erosion and sedimentation during floods. Combined observations of radiocesium vertical distribution in soil and sediment deposition on artificial lawn-grass mats on the Niida River floodplain allowed us to estimate both annual mean sediment accumulation rates and maximum sedimentation rates corresponding to an extreme flood event during Tropical Storm Etau, 6-11 September 2015. Dose rates were reduced considerably for floodplain sections with high sedimentation because the top soil layer with high radionuclide contamination was eroded and/or buried under cleaner fresh sediments produced mostly due to bank erosion and sediments movements. Rate constants of natural attenuation on the sites of the Takase River and floodplain of Niida River was found to be in range 0.2-0.4 year-1. For the site in the lower reach of the Niida River, collimated shield dose readings from soil surfaces slightly increased during the period of observation from February to July 2016. Generally, due to more precipitation, steeper slopes, higher temperatures and increased biological activities in soils, self-purification of radioactive contamination in Fukushima associated with vertical and lateral radionuclide migration is faster than in Chernobyl. In many cases, monitored natural attenuation along with appropriate restrictions seems to be optimal option for water remediation in Fukushima contaminated areas

Impacts of Dry Season and Forest Fire 1997-1998 Episodes on Mixed Dipterocarp Forest at Bukit Bangkirai, East Kalimantan*[pengaruh Musim Kering Dan Kebakaran Hutan Episode 1997-1998 Terhadap Hutan Dipterocarp Campuran Di Bukit Bangkirai, Kalimantan Timur]

Kawasan Kalimantan Timur mengalami musim kemarau panjang yang merangsang terjadinya kebakaran hutan yang luas pada 1982-1983 dan 1997-1998.Naskah ini mengemukakan hasil penelitian di Bukit Bangkirai, Kalimantan Tengah mengenai dampak dari kemarau panjang dan kebakaran hutan 1997-1998 terhadap diversitas tumbuhan pohon hutan dipterokarp campuran.Penelitian dilakukan dengan cara memperbandinkan hasil pencacahan tumbuhan pohon berlingkar batang setinggi dada lebih daripada 15cm yang terdapat dalam tiga petak penelitian, masing-masing: lha di hutan alam yang tidak terbakar (K-plot), 0,3 ha di hutan yang terbakar ringan (LD) dan lha di hutan yang terbakar berat (HD).Hasil penelitian menunjukkan bahwa musim kemarau panjang 1997-1998 menyebabkan 12,02% mortalitas individual pohon di hutan alam yang tidak terbakar, yang terlihat dari pohon mati berdiri tegak akibat kekeringan, atau kehilangan 21,67% dari total basal area. Secara keseluruhan terlihat bahwa kebakaran hutan menyebabkan kerusakan berat terhadap struktur dan komposisi hutan. Secara kumulatif, kemarau panjang dan kebakaran hutan menyebabkan mortalitas individual pohon berkisar 36-70% dan kehilangan total basal area antara 45-85% dan menyebabkan lantai hutan terbuka terhadap penyinaran matahari langsung karena menurunnya penutupan tajuk sebesar 23-79%.Kebakaran hutan juga berdampak terhadap penurunan biodiversitas tumbuhan pohon sebesar 23-79% pada tingkat jenis, 53-66% pada tingkat marga dan 18-21% pada tingkat suku.Tercatat Perubahan komposisi jenis pada hutan yang terbakar; dominasi jenis Dipterocarpaceae dipetak hutan tak terbakar (K) menjadi dominasi pionir sekunder Macaranga gigantea-Vernonia arborea di petak terbakar berat (HD) dan dominasi Macaranga gigantea-Shorea smilhiana di petak terbakar ringan (LD).Beberapa jenis seperti Durio acutifolius dan Syzygium incarnaium mungkin dapat digolongkan sebagai jenis yang relative lebih tahan terhadap api

Research and management challenges following soil and landscape decontamination at the onset of the reopening of the Difficult-to-Return Zone, Fukushima (Japan)

Twelve years after the nuclear accident that occurred at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in March 2011, radiocesium contamination (with a large dominance of 137Cs, with a 30-year half-life) remains a major concern in various municipalities of north-eastern Japan. The Japanese authorities completed an unprecedented soil decontamination programme in residential and cultivated areas affected by the main radioactive plume (8953 km2). They implemented a complex remediation programme scheme to remediate soils that are fundamental to life on Earth, relying on different decision rules depending on the waste type, its contamination level and its region of origin, after delineating different zones exposed to contrasted radiation rates. The central objective was not to expose local inhabitants to radioactive doses exceeding 1 mSv yr−1 in addition to the natural levels. At the onset of the full reopening of the Difficult-to-Return Zone (DTRZ) in spring 2023, the current review provides an update of a previous synthesis published in 2019 (Evrard et al., 2019). Although this ambitious soil remediation and reconstruction programme has almost been completed in the 12 municipalities of Fukushima Prefecture in which an evacuation order was imposed in at least one neighbourhood in 2011, from the 147 443 inhabitants who lived there before the accident, only 29.9 % of them had returned by 2020. Waste generated by decontamination and tsunami cleaning/demolition work is planned to have been fully transported to (interim) storage facilities by the end of 2023. The cost of the operations conducted between 2011 and 2020 for the so-called “nuclear recovery” operations (including decontamination) was estimated by the Board of Audit of Japan in 2023 as JPY 6122.3 billion (∼ EUR 44 billion). Decontamination of cropland was shown to have impacted soil fertility, and potassium fertilisation is recommended to limit the transfer of residual radiocesium to new crops. In forests that cover 71 % of the surface area of Fukushima Prefecture and that were not targeted by remediation, radiocesium is now found in the upper mineral layer of the soil in a quasi-equilibrium state. Nevertheless, 137Cs concentrations in forest products (including wood for heating and construction, wild plants, wildlife game, mushrooms) often keep exceeding the threshold values authorised in Japan, which prohibits their exploitation in the area affected by the main plume. Radionuclides from forests were shown to be exported in dissolved and particle-bound forms to downstream river systems and floodplains, although multiple monitoring records showed the continuous decrease in radiocesium concentrations in both river water and sediment across the main plume between 2011 and 2021. Fish contamination is now generally found to be below the threshold limits although reputational damage remains a major concern for local fishing communities. The remobilisation of radiocesium from sediment accumulated in reservoirs of the region is also of potential concern as it may lead to secondary contamination of fish or irrigation waters supplied to decontaminated fields. Overall, this synthesis demonstrates the need to continue monitoring post-accidental radiocesium transfer in these environments and to keep sharing data in order to refine our predictive understanding of radiocesium mobility and consolidate the tools available to model contaminant transfer in ecosystems. In forests in particular, novel countermeasures and wood uses remain to be developed and tested. Furthermore, the hydrologic connectivity between soils under different ecosystems greatly influences long-term radiocesium transport. The consequences of extreme phenomena (e.g. typhoons, forest fires) that may become more frequent in the future as a result of global change in these contaminated environments should be further anticipated.</p

Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity and therefore probability to detect planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.Comment: 10 pages, 5 figures, 1 table; ApJ in pres

Suppression of Cellular Transformation by Poly (A) Binding Protein Interacting Protein 2 (Paip2)

Controlling translation is crucial for the homeostasis of a cell. Its deregulation can facilitate the development and progression of many diseases including cancer. Poly (A) binding protein interacting protein 2 (Paip2) inhibits efficient initiation of translation by impairing formation of the necessary closed loop of mRNA. The over production of Paip2 in the presence of a constitutively active form of hRasV12 can reduce colony formation in a semi-solid matrix and focus formation on a cell monolayer. The ability of Paip2 to bind to Pabp is required to suppress the transformed phenotype mediated by hRasV12. These observations indicate that Paip2 is able to function as a tumor suppressor

Generation of Germline-Competent Rat Induced Pluripotent Stem Cells

Recent progress in rat pluripotent stem cell technology has been remarkable. Particularly salient is the demonstration that embryonic stem cells (ESCs) in the rat (rESCs) can contribute to germline transmission, permitting generation of gene-modified rats as is now done using mouse ESCs (mESCs) or mouse induced pluripotent stem cells (iPSCs; miPSCs). However, determinations of whether rat iPSCs (riPSCs) can contribute to germ cells are not published. Here we report the germline competency of riPSCs.We generated riPSCs by transducing three mouse reprogramming factors (Oct3/4, Klf4, and Sox2) into rat somatic cells, followed by culture in the presence of exogenous rat leukemia inhibitory factor (rLIF) and small molecules that specifically inhibit GSK3, MEK, and FGF receptor tyrosine kinases. We found that, like rESCs, our riPSCs can contribute to germline transmission. Furthermore we found, by immunostaining of testis from mouse-rat interspecific chimeras with antibody against mouse vasa homolog, that riPSCs can contribute to embryonic development with chimera formation in mice (rat-mouse interspecific chimeras) and to interspecific germlines.Our data clearly demonstrate that using only three reprogramming factors (Oct3/4, Klf4, and Sox2) rat somatic cells can be reprogrammed into a ground state. Our generated riPSCs exhibited germline transmission in either rat-rat intraspecific or mouse-rat interspecific chimeras

Use of MicroRNA Let-7 to Control the Replication Specificity of Oncolytic Adenovirus in Hepatocellular Carcinoma Cells

Highly selective therapy for hepatocellular carcinoma (HCC) remains an unmet medical need. In present study, we found that the tumor suppressor microRNA, let-7 was significantly downregulated in a proportion of primary HCC tissues (12 of 33, 36.4%) and HCC cell lines. In line with this finding, we have engineered a chimeric Ad5/11 fiber oncolytic adenovirus, SG7011let7T, by introducing eight copies of let-7 target sites (let7T) into the 3′ untranslated region of E1A, a key gene associated with adenoviral replication. The results showed that the E1A expression (both RNA and protein levels) of the SG7011let7T was tightly regulated according to the endogenous expression level of the let-7. As contrasted with the wild-type adenovirus and the control virus, the replication of SG7011let7T was distinctly inhibited in normal liver cells lines (i.e. L-02 and WRL-68) expressing high level of let-7 (>300 folds), whereas was almost not impaired in HCC cells (i.e. Hep3B and PLC/PRF/5) with low level of let-7. Consequently, the cytotoxicity of SG7011let7T to normal liver cells was successfully decreased while was almost not attenuated in HCC cells in vitro. The antitumor ability of SG7011let7T in vivo was maintained in mice with Hep3B xenograft tumor, whereas was greatly decreased against the SMMC-7721 xenograft tumor expressing a high level of let-7 similar with L-02 when compared to the wild-type adenovirus. These results suggested that SG7011let7T may be a promising anticancer agent or vector to mediate the expression of therapeutic gene, broadly applicable in the treatment for HCC and other cancers where the let-7 gene is downregulated

microRNA-Mediated Messenger RNA Deadenylation Contributes to Translational Repression in Mammalian Cells

Animal microRNAs (miRNAs) typically regulate gene expression by binding to partially complementary target sites in the 3′ untranslated region (UTR) of messenger RNA (mRNA) reducing its translation and stability. They also commonly induce shortening of the mRNA 3′ poly(A) tail, which contributes to their mRNA decay promoting function. The relationship between miRNA-mediated deadenylation and translational repression has been less clear. Using transfection of reporter constructs carrying three imperfectly matching let-7 target sites in the 3′ UTR into mammalian cells we observe rapid target mRNA deadenylation that precedes measureable translational repression by endogenous let-7 miRNA. Depleting cells of the argonaute co-factors RCK or TNRC6A can impair let-7-mediated repression despite ongoing mRNA deadenylation, indicating that deadenylation alone is not sufficient to effect full repression. Nevertheless, the magnitude of translational repression by let-7 is diminished when the target reporter lacks a poly(A) tail. Employing an antisense strategy to block deadenylation of target mRNA with poly(A) tail also partially impairs translational repression. On the one hand, these experiments confirm that tail removal by deadenylation is not strictly required for translational repression. On the other hand they show directly that deadenylation can augment miRNA-mediated translational repression in mammalian cells beyond stimulating mRNA decay. Taken together with published work, these results suggest a dual role of deadenylation in miRNA function: it contributes to translational repression as well as mRNA decay and is thus critically involved in establishing the quantitatively appropriate physiological response to miRNAs