Beneficial effects of dithiothreitol on relative levels of glutathione S-transferase activity and thiols in oocytes, and cell number, DNA fragmentation and allocation at the blastocyst stage in the mouse

We analyzed the effect of in vitro aging of mouse oocytes in the presence of dithiothreitol (DTT) on relative levels of glutathione S-transferase (GST) activity and thiols in oocytes, and cell number, DNA fragmentation and cellular allocation to the inner cell mass (ICM) and trophectoderm (TE) lineage at the blastocyst stage. Ovulated oocytes from gonadotropin primed hybrid female mice of 6-8 weeks of age were aged in vitro in the presence of 0, 5, 50, or 500 microM DTT for 6 hr prior to insemination. Relative levels of GST activity and thiols in oocytes were determined by confocal laser scanning microscopy, DNA fragmentation using a single-step TUNEL method, and cell allocation to the ICM and TE lineage by blastocyst staining with propidium iodide and Hoechst 33258. Non-aged oocytes exhibited higher relative levels of GST activity and thiols when compared to oocytes aged in the presence of 0, 5, and 50 microM DTT. Day 5 blastocysts from the 5, 50, and 500 microM DTT groups exhibited higher total number of cells, number of ICM cells, and ICM/TE ratio, but lower percentage of number of nuclei with DNA fragmentation/number of ICM cells than blastocyst from the 0 microM DTT group. These data show that DTT counteracts the negative effects of a post-ovulatory aging of mouse oocytes in vitro on relative levels of GST activity and thiols in oocytes, and percentage of number of nuclei with DNA fragmentation/number of ICM cells, total number of cells, number of ICM cells and ICM/TE ratio in Day 5 blastocysts.     

镉离子诱导BA/F3β细胞发生奇特的细胞凋亡

细胞凋亡一般都伴随有ＤＮＡ 片段化, 活性氧含量增加, 并能被过量的Ｂｃｌ２ 所抑制。以ＢＡ／Ｆ３β细胞为模型, 利用ＭＴＴ 检测、Ｈｏｃｈｅｓｔ 染色以及透射电镜检测等技术却发现, 镉离子虽然可以诱导该细胞凋亡, 但是这种凋亡没有ＤＮＡ 片段化, 也没有活性氧含量增加。此外, 过量Ｂｃｌ２ 对这种凋亡也没有保护作用。因此, 可以确认镉离子诱导ＢＡ／Ｆ３β细胞发生了奇特的细胞凋亡。     

基于简化基因组测序揭示水角的濒危机制

物种的遗传多样性是决定物种适应性和生存能力的关键因素。生境片段化是造成生物多样性丧失的重要因素之一,对植物种群的遗传多样性有着重要影响。水角(Hydrocera triflora)作为一种濒危植物,其遗传多样性状况和濒危机制尚未有报道。该文收集了水角7个种群共计34个样本,利用简化基因组测序技术(RAD-seq)获得了单核苷酸变异位点(SNP)。通过种群遗传多样性和遗传结构的分析,并结合种群历史动态分析和不同气候情景下物种潜在分布区预测,探讨了水角的濒危机制。结果表明:(1)水角遗传多样性较低(H_o=0.156 9、H_e=0.165 4、π=0.186 5),遗传分化系数较高; AMOVA分析表明,遗传变异主要发生在种群内。(2)Mantel检测表明环境距离与遗传距离、地理距离均呈显著正相关,分别为P=0.041 2和P=0.008 2。(3)水角的有效种群大小从全新世中期开始持续下降,与琼北火山群的喷发时间一致。(4)与当代气候相比,虽然在未来气候变化下水角的潜在分布区总面积变动不大,但在高CO₂排放的情景下,大量的高适生区将会丧失并转化为低适生区,特别是位于马来群岛的适生区几乎完全消失。该研究结果表明,生境片段化导致了水角较低的遗传多样性和有效种群大小的持续下降。因此,自身更新能力低以及人为活动干扰、城市化等不利的环境条件是导致其濒危的主要原因。建议加强对水角的就地保护,采用人工授粉等方法提高其基因流以增加其种群的遗传多样性,同时,要着重保护湿地免遭破坏。     

Genetic evidence for landscape effects on dispersal in the army ant Eciton burchellii

Inhibited dispersal, leading to reduced gene flow, threatens populations with inbreeding depression and local extinction. Fragmentation may be especially detrimental to social insects because inhibited gene flow has important consequences for cooperation and competition within and among colonies. Army ants have winged males and permanently wingless queens; these traits imply male‐biased dispersal. However, army ant colonies are obligately nomadic and have the potential to traverse landscapes. Eciton burchellii, the most regularly nomadic army ant, is a forest interior species: colony raiding activities are limited in the absence of forest cover. To examine whether nomadism and landscape (forest clearing and elevation) affect population genetic structure in a montane E. burchellii population, we reconstructed queen and male genotypes from 25 colonies at seven polymorphic microsatellite loci. Pairwise genetic distances among individuals were compared to pairwise geographical and resistance distances using regressions with permutations, partial Mantel tests and random forests analyses. Although there was no significant spatial genetic structure in queens or males in montane forest, dispersal may be male‐biased. We found significant isolation by landscape resistance for queens based on land cover (forest clearing), but not on elevation. Summed colony emigrations over the lifetime of the queen may contribute to gene flow in this species and forest clearing impedes these movements and subsequent gene dispersal. Further forest cover removal may increasingly inhibit Eciton burchellii colony dispersal. We recommend maintaining habitat connectivity in tropical forests to promote population persistence for this keystone species.     

Sex-sorted bovine spermatozoa and DNA damage: II. Dynamic features

This study examined the dynamic response of Spermatozoa DNA Fragmentation after sex selection in bulls using a MoFlo^® SX (Beckman Coulter, Miami FL) spermatozoa sorter. The dynamic response of spermatozoa DNA fragmentation refers to the changing values of SDF, i.e., rate of SDF (rSDF), when analyzed periodically over a set incubation time at 37 °C. A dynamic assessment of SDF using non-sorted and sex-sorted spermatozoa samples during 72 h of incubation at 37 °C was performed. Results showed a reduced DNA longevity in sex-sorted frozen-thawed spermatozoa, with spermatozoa DNA damage appearing between 24 h and 48 h. The baseline SDF level was higher in conventional frozen-thawed than in sex-sorted frozen-thawed spermatozoa samples; while the reverse occurred for the rSDF. The afore-mentioned result produced a crossover point between both dynamic tendencies of SDF for sex-sorted versus conventional samples. We defined this crossover point as the Crossover Positioning Time (CPT) or the time (in hours) where both curves crossover after a period of spermatozoa incubation at 37 °C. The point at which the CPT occurs could be used as an indicator of the rSDF for individual bulls after X- and Y-chromosome bearing spermatozoa selection. CPT values produced a window of SDF ranging between 24 h and 48 h in the present experiment. It is proposed that higher values for CPT are indicative of bulls presenting chromatin that is more resistant to the external stressors affecting spermatozoa DNA after spermatozoa sorting.     

Targeted discovery and identification of novel nucleoside biomarkers in Apostichopus japonicus viscera using metabonomics

In this study, we investigated the metabonomic profiles of Apostichopus japonicus using an LC-MS-based method in conjunction with multivariate data analysis. Based on the PLS-DA model, 85 differential metabolites (VIP value >1.0) were obtained from viscera and body wall samples. The MS/MS and NMR experiments were used for the qualitative identification of the characteristic peaks. Sphingoid-based nucleoside analogues were the main components in Chinese A. japonicus viscera. Our findings demonstrate that A. japonicus viscera contain a large number of compounds that may have applications as nutraceuticals or pharmaceuticals.     

Antiproliferative activity of Pterodon pubescens Benth. seed oil and its active principle on human melanoma cells

On a preliminary screening, relevant in vitro antiproliferative activity was observed to the crude ethanolic extract of Pterodon pubescens seed oil against the human melanoma cell line SK MEL 37. The diethyl ether fraction from crude ethanolic extract which exhibited stronger activity was submitted to fractionation by gradient elution with hexane/ethyl acetate. Subfraction A, eluted by hexane/ethyl acetate (80:20), was essentially the most active between all the assayed subfractions with an IC₅₀ of 37 μg/ml calculated by the MTT colorimetric method. At this concentration, subfraction A caused morphological features and internucleosomal DNA fragmentation pattern of apoptosis. Through chromatographic separation, the furane diterpene 1 was isolated from this active subfraction and identified by spectral techniques. Compound 1 showed an IC₅₀ value of 32 μM and fluorescence staining with DAPI revealed some typical nuclear changes which are characteristic of apoptosis. These findings support a role for diterpenoids vouacapan-type skeleton as a model to develop new anticancer agents.     

Home range area in the tortoise Testudo hermanni in relation to habitat complexity: implications for conservation of biodiversity

The tortoise Testudo hermanni is endangered by habitat fragmentation and loss in western Europe, where its high public profile and specific conservation projects make this a flagship species. Studies of movement in the peak reproductive season (June) showed that home ranges were substantially larger in France than in Greece. This difference was due to the intensity of use of the home range, not to the distance moved which was remarkably similar in the two areas. There was no sexual difference in home range area. The home range was therefore not large in France because of movement to nesting sites, but rather for utilization of the greater habitat complexity there. The need for reserves to include different vegetation types makes conservation of T. hermanni in France more difficult. Conversely, the need for large reserves increases its value as an umbrella species for conservation of biodiversity.     

Sequential abundant ion fragmentation analysis (SAIFA): an alternative approach for phosphopeptide identification using an ion trap mass spectrometer

Phosphorylation has been the most studied of all the posttranslational modifications of proteins. Mass spectrometry has emerged as a powerful tool for phosphomapping on proteins/peptides. Collision-induced dissociation (CID) of phosphopeptides leads to the loss of phosphoric or metaphosphoric acid as a neutral molecule, giving an intense neutral loss product ion in the mass spectrum. Dissociation of the neutral loss product ion identifies peptide sequence. This method of data-dependent constant neutral loss (DDNL) scanning analysis has been commonly used for mapping phosphopeptides. However, preferential losses of groups other than phosphate are frequently observed during CID of phosphopeptides. Ions that result from such losses are not identified during DDNL analysis due to predetermined scanning for phosphate loss. In this study, we describe an alternative approach for improved identification of phosphopeptides by sequential abundant ion fragmentation analysis (SAIFA). In this approach, there is no predetermined neutral loss molecule, thereby undergoing sequential fragmentation of abundant peak, irrespective of the moiety lost during CID. In addition to improved phosphomapping, the method increases the sequence coverage of the proteins identified, thereby increasing the confidence of protein identification. To the best of our knowledge, this is the first report to use SAIFA for phosphopeptide identification.     

Plant distribution patterns related to species characteristics and spatial and temporal habitat heterogeneity in a network of ditch banks

In this study we investigated the relationship between the distributionpatterns of a number of herbaceous plant species and the isolation and age ofhabitat patches. The study was conducted for a network of ditch banks in anagricultural landscape in The Netherlands. Thirteen plant species were selectedrepresenting contrasting dispersal and seed bank characteristics. Isolation ofhabitat patches was determined by the distance to the nearest occupied patchandby the number of occupied patches in circles of increasing radius around thepatches. Age was the number of years since the creation of the ditches. In amultiple logistic regression model the separate effects of age of the habitatand the spatial variables were analyzed. A number of habitat variables wereusedto correct the effect of habitat quality. We concluded that distributionpatterns of plant species were mainly determined by habitat quality and thepresence of seed sources at short distances (< 25 m). Thisconclusion was independent of the dispersal characteristics of the species.Mostspecies had higher occupation frequencies in older than younger ditch banks.Only species with persistent seeds had comparable occupation probabilities inolder and younger habitat patches, indicating the importance of the soil seedbank as a source of colonization after large-scale disturbances. The effect ofage and management on the occupation probabilities of the species was oftendiminished in the regression model, probably due to correlation between somehabitat variables and the age of the patches.