Effects of ethyl-esterization, chain-lengths, unsaturation degrees, and hyperthermia on carcinostatic effect of omega-hydroxylated fatty acids

Aim: To evaluate promotive effect of hyperthermia on the carcinostatic activity of synthesized omega-hydroxy fatty acids (wHFAs) and their ethylesters agaist Ehrlich ascites tumor (EAT) cells. Methods: EAT cells were cultured with either wHFAs or their ethylester derivatives in a water bath at either 37 °C or 42 °C for 30 min, followed by incubation in a CO2 incubator for 20 or 72 h. Mitochondrial dehydrogenase-based WST-1 assay and trypan blue dye exclusion assay were then conducted after incubation. Morphological changes were observed by scanning electron microscopy (SEM). Results: Omega-HFA having a saturated 16-carbon straight-chain (wH16:0) was the most carcinostatic (at 37 °C – viability level: 60.0%; at 42 °C – 49.6% (WST-1)) among saturated and unsaturated wHFAs with 12, 15 or 16 carbon atoms, when administrated to EAT cells at 100 µM for 20 h. Carcinostatic activity was markedly enhanced by ethyl-esterization of saturated fatty acids, such as wH16:0 (at 37 °C – 42.3%; at 42 °C – 11.2% , ibid) and wH15:0 (at 37 °C – 74.6%; at 42 °C – 25.3% , ibid), and their unsaturated counterparts were extremely effective only in combination with hyperthermia. Prolongation of the incubation period to 72 h at the same concentration increased appreciably their carcinostatic effect (wH16:0 ethylesther: 1.3%; wH15:0 ethylesther: 8.0%). These values were also supported by dye exclusion assay. The carcinostatic activity enhanced more markedly by hyperthermia (1.2%; 2.1%, ibid). SEM shows that wH16:0 ethylester-exposed EAT cells underwent extensive injury, such as deformation of cell structure or disappearance of microvilli. Conclusions: wH16:0 ethylester possesses high carcinostatic activity in vitro in combination with hyperthermia and may be utilized as potent anticancer therapeutic agent.Цель: проанализировать усиливающий эффект гипертермии на канцеростатическую активность синтезированных омегагидроксилированных жирных кислот (HFAs) и их этиловых эфиров по отноению к клеткам асцитной опухоли рлиха (EAT). Методы: клетки EAT инкубировали с HFAs или их этилэфирными производными на водной ане при 37 ° или 42 ° в течение 30 мин с дальнейим культивированием в 2 инкубаторе на протяжении 20 или 72 ч, после чего анализировали жизнеспособность клеток методами анализа WST-1, основанного на активности митохондриальных дегидрогеназ, и по включению трипанового синего. Морфологические изменения клеток определяли с использованием сканирующей электронной микроскопии. Результаты: при культивации клеток EAT в присутствии 100 M соединений в течение 20 ч омега-HFA с насыщенной 16-углеродной прямой цепью (H16:0) проявляли наиболее выраженный канцеростатический эффект (при 37 ° уровень жизнеспосоности составил 60,0%; при 42 ° 49,6% (WST-1)) по сравнению с таковым насыщенных и ненасыщенных HFAs, содержащих 12, 15 или 16 атомов углерода. анцеростатическая активность значительно возрастала при этилэтерификации насыщенных жирных кислот, таких как H16:0 (при 37 ° 42,3%; при 42 ° 11,2%, ibid) и H15:0 (при 37 ° 74,6%; при 42 ° 25,3% , ibid), в то время как производные ненасыщенных кислот были высокоэффективны только в комбинации с гипертермией. Увеличение периода инкубации клеток до 72 ч при той же концентрации веществ приводило к значительному увеличению их канцеростатического действия (этиловый эфир H16:0 1,3%; этиловый эфир H15:0 ethylesther 8,0%), подтвержденного данными окраски трипановым синим. рименение гипертермии также усиливало канцеростатическое действие соединений (1,2%; 2,1%, ibid). Результаты исследования методом SEM показали, что клетки EAT, инкубированные с этиловым эфиром H16:0, разруаются с нарушением клеточной структуры и исчезновением микроволокон. Выводы: в комбинации с гипертермией этиловый эфир H16:0 про ет высокую канцеростатическую активность in vitro, что говорит о возможности применения соединения в терапии опухолевых заболеваний

Measurement of the cosmic-ray antiproton spectrum at solar minimum with a long-duration balloon flight over Antarctica

The energy spectrum of cosmic-ray antiprotons from 0.17 to 3.5 GeV has been measured using 7886 antiprotons detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary antiproton calculations. Cosmologically primary antiprotons have been investigated by comparing measured and calculated antiproton spectra. BESS-Polar II data show no evidence of primary antiprotons from evaporation of primordial black holes.Comment: 4 pages, 4 figures, submitted to Physical Review Letter

SIRT6 stabilizes DNA-dependent Protein Kinase at chromatin for DNA double-strand break repair

The Sir2 chromatin regulatory factor links maintenance of genomic stability to life span extension in yeast. The mammalian Sir2 family member SIRT6 has been proposed to have analogous functions, because SIRT6-deficiency leads to shortened life span and an aging-like degenerative phenotype in mice, and SIRT6 knockout cells exhibit genomic instability and DNA damage hypersensitivity. However, the molecular mechanisms underlying these defects are not fully understood. Here, we show that SIRT6 forms a macromolecular complex with the DNA double-strand break (DSB) repair factor DNA-PK (DNA-dependent protein kinase) and promotes DNA DSB repair. In response to DSBs, SIRT6 associates dynamically with chromatin and is necessary for an acute decrease in global cellular acetylation levels on histone H3 Lysine 9. Moreover, SIRT6 is required for mobilization of the DNA-PK catalytic subunit (DNA-PKcs) to chromatin in response to DNA damage and stabilizes DNA-PKcs at chromatin adjacent to an induced site-specific DSB. Abrogation of these SIRT6 activities leads to impaired resolution of DSBs. Together, these findings elucidate a mechanism whereby regulation of dynamic interaction of a DNA repair factor with chromatin impacts on the efficiency of repair, and establish a link between chromatin regulation, DNA repair, and a mammalian Sir2 factor

Structure and mechanism of human DNA polymerase η

The variant form of the human syndrome xeroderma pigmentosum (XPV) is caused by a deficiency in DNA polymerase eta (Pol eta), a DNA polymerase that enables replication through ultraviolet-induced pyrimidine dimers. Here we report high-resolution crystal structures of human Pol eta at four consecutive steps during DNA synthesis through cis-syn cyclobutane thymine dimers. Pol eta acts like a 'molecular splint' to stabilize damaged DNA in a normal B-form conformation. An enlarged active site accommodates the thymine dimer with excellent stereochemistry for two-metal ion catalysis. Two residues conserved among Pol eta orthologues form specific hydrogen bonds with the lesion and the incoming nucleotide to assist translesion synthesis. On the basis of the structures, eight Pol eta missense mutations causing XPV can be rationalized as undermining the molecular splint or perturbing the active-site alignment. The structures also provide an insight into the role of Pol eta in replicating through D loop and DNA fragile sites

Global raster dataset on historical coastline positions and shelf sea extents since the Last Glacial Maximum

Motivation: Historical changes in sea level caused shifting coastlines that affected the distribution and evolution of marine and terrestrial biota. At the onset of the Last Glacial Maximum (LGM) 26 ka, sea levels were >130 m lower than at present, resulting in seaward-shifted coastlines and shallow shelf seas, with emerging land bridges leading to the isolation of marine biota and the connection of land-bridge islands to the continents. At the end of the last ice age, sea levels started to rise at unprecedented rates, leading to coastal retreat, drowning of land bridges and contraction of island areas. Although a growing number of studies take historical coastline dynamics into consideration, they are mostly based on past global sea-level stands and present-day water depths and neglect the influence of global geophysical changes on historical coastline positions. Here, we present a novel geophysically corrected global historical coastline position raster for the period from 26 ka to the present. This coastline raster allows, for the first time, calculation of global and regional coastline retreat rates and land loss rates. Additionally, we produced, per time step, 53 shelf sea rasters to present shelf sea positions and to calculate the shelf sea expansion rates. These metrics are essential to assess the role of isolation and connectivity in shaping marine and insular biodiversity patterns and evolutionary signatures within species and species assemblages. Main types of variables contained: The coastline age raster contains cells with ages in thousands of years before present (bp), representing the time since the coastline was positioned in the raster cells, for the period between 26 ka and the present. A total of 53 shelf sea rasters (sea levels <140 m) are presented, showing the extent of land (1), shelf sea (0) and deep sea (NULL) per time step of 0.5 kyr from 26 ka to the present. Spatial location and grain: The coastline age raster and shelf sea rasters have a global representation. The spatial resolution is scaled to 120 arcsec (0.333° × 0.333°), implying cells of c. 3,704 m around the equator, 3,207 m around the tropics (±30°) and 1,853 m in the temperate zone (±60°). Time period and temporal resolution: The coastline age raster shows the age of coastline positions since the onset of the LGM 26 ka, with time steps of 0.5 kyr. The 53 shelf sea rasters show, for each time step of 0.5 kyr, the position of the shelf seas (seas shallower than 140 m) and the extent of land. Level of measurement: Both the coastline age raster and the 53 shelf sea rasters are provided as TIFF files with spatial reference system WGS84 (SRID 4326). The values of the coastline age raster per grid cell correspond to the most recent coastline position (in steps of 0.5 kyr). Values range from 0 (0 ka, i.e., present day) to 260 (26 ka) in bins of 5 (0.5 kyr). A value of “no data” is ascribed to pixels that have remained below sea level since 26 ka. Software format: All data processing was done using the R programming language

Measurement of Cosmic-Ray Antiproton Spectrum at Solar Minimum with a Long-Duration Balloon Flight in Antarctica

The energy spectrum of cosmic-ray antiprotons (p(raised bar)'s) collected by the BESS-Polar II instrument during a long-duration flight over Antarctica in the solar minimum period of December 2007 through January 2008. The p(raised bar) spectrum measured by BESS-Polar II shows good consistency with secondary p(raised bar) calculations. Cosmologically primary p(raised bar)'s have been searched for by comparing the observed and calculated p(raised bar) spectra. The BESSPolar II result shows no evidence of primary p(raised bar)'s originating from the evaporation of PBH

Heterologous expression and characterization of CpI, OcpA, and novel serine-type carboxypeptidase OcpB from Aspergillus oryzae

In the genome of Aspergillus oryzae, 12 genes have been predicted to encode serine-type carboxypeptidases. However, the carboxypeptidase activities of the proteins encoded by these genes have not yet been confirmed experimentally. In this study, we have constructed three of these 12 genes overexpressing strains using Aspergillus nidulans and characterized their overproduced recombinant proteins. Of these three genes, one was previously named cpI; the other two have not been reported yet, and hence, we named them ocpA and ocpB. The recombinant proteins released amino acid residues from the C terminus of peptides, and the activity of the enzymes was inhibited by phenylmethylsulfonyl fluoride, indicating the enzymes to be serine-type carboxypeptidases. Recombinant OcpA, OcpB, and CpI were stable at 45°C, 55°C, and 55°C, respectively, at a low pH. The enzymatic properties of recombinant OcpB were different from those of any reported serine-type carboxypeptidase. On the other hand, recombinant OcpA had similar enzymatic properties to A. oryzae carboxypeptidases O1 and O2. The DNA and N-terminal amino acid sequences of carboxypeptidases O1 and O2 from A. oryzae IAM2640 were similar to those of OcpA. Result of transcriptional analysis of ocpA, ocpB, and cpI suggest differences in transcriptional regulation between these genes

Search for Antihelium with the BESS-Polar Spectrometer

In two long-duration balloon flights over Antarctica, the BESS-Polar collaboration has searched for antihelium in the cosmic radiation with higher sensitivity than any reported investigation. BESSPolar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4 x 10(exp 6) [Z] = 2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0 x 10(exp 7) [Z] = 2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit of 6.9 x 10(exp -8) was determined by combining all the BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies from 1.6 to 14 GV, an upper limit of 1.0 x 10(exp -7) was determined for the combined BESS-Polar data. These are the most stringent limits obtained to date