CDC6 controls dynamics of the first embryonic M-phase entry and progression via CDK1 inhibition

CDC6 is essential for S-phase to initiate DNA replication. It also regulates M-phase exit by inhibiting the activity of the major M-phase protein kinase CDK1. Here we show that addition of recombinant CDC6 to Xenopus embryo cycling extract delays the M-phase entry and inhibits CDK1 during the whole M-phase. Down regulation of endogenous CDC6 accelerates the M-phase entry, abolishes the initial slow and progressive phase of histone H1 kinase activation and increases the level of CDK1 activity during the M-phase. All these effects are fully rescued by the addition of recombinant CDC6 to the extracts. Diminution of CDC6 level in mouse zygotes by two different methods results in accelerated entry into the first cell division showing physiological relevance of CDC6 in intact cells. Thus, CDC6 behaves as CDK1 inhibitor regulating not only the M-phase exit, but also the M-phase entry and progression via limiting the level of CDK1 activity. We propose a novel mechanism of M-phase entry controlled by CDC6 and counterbalancing cyclin B-mediated CDK1 activation. Thus, CDK1 activation proceeds with concomitant inhibition by CDC6, which tunes the timing of the M-phase entry during the embryonic cell cycle.     

TRS-based PCR as a potential tool for inter-serovar discrimination of Salmonella Enteritidis,S. Typhimurium,S. Infantis,S. Virchow,S. Hadar,S. Newport and S. Anatum

Salmonella enterica subsp. enterica comprises a number of serovars, many of which pose an epidemiological threat to humans and are a worldwide cause of morbidity and mortality. Most reported food infection outbreaks involve the serovars Salmonella Enteritidis and Salmonella Typhimurium. Rapid identification to determine the primary sources of the bacterial contamination is important to the improvement of public health. In recent years, many DNA-based techniques have been applied to genotype Salmonella. Herein, we report the use of a manual TRS-PCR approach for the differentiation of the Salmonella enterica subspecies enterica serovars in a single-tube assay. One hundred seventy Salmonella strains were examined in this work. These consisted of serovars S. Enteritidis, S. Typhimurium, S. Infantis, S. Virchow, S. Hadar, S. Newport and S. Anatum. Five of the TRS-primers, N₆(GTG)₄, N₆(CAC)₄, N₆(CGG)₄, N₆(CCG)₄ and N₆(CTG)₄, perfectly distinguished the S. Enteritidis and S. Typhimurium serovars, and the N₆(GTG)₄ primer additionally grouped the other five frequently isolated serovars. In our opinion, the TRS-PCR methodology could be recommended for a quick and simple DNA-based test for inter-serovar discrimination of Salmonella strains.     

Syntheses and thermal characterization of the magnesium phthalocyanine complexes with 2-methoxy- and with 2-ethoxyethanol. X-ray structure of (2-ethoxyethanol)magnesium phthalocyanine

The syntheses of the magnesium phthalocyanine complexes with dry 2-methoxy-ethanol and 2-ethoxyethanol have been performed by recrystallization method using both anhydrous MgPc and aquated magnesium phthalocyanine, MgPcH₂O, as a starting material. It has turned out that in the temperature range below ca. 140 °C, the bi-axially ligated complexes are formed, i.e., MgPc(2-methoxyethanol)₂ and MgPc(2-ethoxyethanol)₂ with 4 + 2 coordination of Mg, whereas at higher temperatures, up to about 200 °C, the mono-axially ligated complexes are stable, i.e., MgPc(2-methoxyethanol) and MgPc(2-ethoxyethanol) with 4 + 1 coordination of Mg.The single crystal structure of MgPc(2-ethoxyethanol) complex has been determined. The central Mg atom is displaced towards the hydroxyl group of the ligand by about 0.37 Å from the (N-isoindole)₄ plane of the Pc ring. Hydrogen bonds of the type O-H?N between the hydroxyl groups of 2-ethoxyethanol and one of the azamethine N-atoms of the Pc ring link the molecules related by a centre of symmetry. Such a packing arrangement in the crystal leads to a dimerization with the ligand-to-Pc connections. The syntheses, thermogravimetric results and structure characteristics are compared with the known MgPc complexes with O- and N-donating molecules.     

Impact of Single Nucleotide Polymorphisms of Base Excision Repair Genes on DNA Damage and Efficiency of DNA Repair in Recurrent Depression Disorder

Elevated level of DNA damage was observed in patients with depression. Furthermore, single nucleotide polymorphisms (SNPs) of base excision repair (BER) genes may modulate the risk of this disease. Therefore, the aim of this study was to delineate the association between DNA damage, DNA repair, the presence of polymorphic variants of BER genes, and occurrence of depression. The study was conducted on peripheral blood mononuclear cells of 43 patients diagnosed with depression and 59 controls without mental disorders. Comet assay was used to assess endogenous (oxidative) DNA damage and efficiency of DNA damage repair (DRE). TaqMan probes were employed to genotype 12 SNPs of BER genes. Endogenous DNA damage was higher in the patients than in the controls, but none of the SNPs affected its levels. DRE was significantly higher in the controls and was modulated by BER SNPs, particularly by c.977C>G–hOGG1, c.972G>C–MUTYH, c.2285T>C–PARP1, c.580C>T–XRCC1, c.1196A>G–XRCC1, c.444T>G–APEX1, c.-468T>G–APEX1, or c.*50C>T–LIG3. Our study suggests that both oxidative stress and disorders in DNA damage repair mechanisms contribute to elevated levels of DNA lesions observed in depression. Lower DRE can be partly attributed to the presence of specific SNP variants.     

Colonization of Fungi and Bacteria in Stumps and Roots of Scots Pine after Thinning and Treatment with Rotstop

The research areas were located in the Pisz Forest District, northeast Poland, in 10‐year‐old Scots pine (Pinus sylvestris L.) plantations, established in 2004 on a clear‐cut area. Reforestation was performed without a biological treatment against root pathogens, despite the presence of Heterobasidion annosum and Armillaria ostoyae in roots and stumps of trees growing previously. The aim of this research was to evaluate how thinning and treatment with the biological control agent Rotstop influences bacterial and fungal communities within roots and stumps. Twelve months after thinning, samples were collected from five stumps in each of two seasons, autumn and spring, from stands on two types of site, one previously forested and one agricultural (20 stumps in total). Wood samples were cultured on agar media, and (i) fungi in the upper part of the stump and (ii) in roots and (iii) bacteria in roots were genetically identified. Sequences were genetically identified by comparing sequences with records held in the GenBank database. We found great differences in the frequency of both fungi and bacteria in roots: they were more frequent (i) in healthy stumps compared to stumps infected with pathogens (H. annosum and A. ostoyae), (ii) in postagricultural soil than in forest soil and (iii) after spring rather than autumn biological treatment. The introduced species Phlebiopsis gigantea was only identified in the parts of the stumps which were above ground level. The bacterium Paenibacillus pini was associated with the presence of H. annosum infecting the stumps from the roots side. In areas seriously threatened by root pathogens, biological treatment can play only a limited role. It can spread to the upper part and impede the production of fruitbodies; however, it has no impact on the development of pathogens in deeper root areas.     

ICA69(null) nonobese diabetic mice develop diabetes, but resist disease acceleration by cyclophosphamide.

ICA69 (islet cell Ag 69 kDa) is a diabetes-associated autoantigen with high expression levels in beta cells and brain. Its function is unknown, but knockout of its Caenorhabditis elegans homologue, ric-19, compromised neurotransmission. We disrupted the murine gene, ica-1, in 129-strain mice. These animals aged normally, but speed-congenic ICA69(null) nonobese diabetic (NOD) mice developed mid-life lethality, reminiscent of NOD-specific, late lethal seizures in glutamic acid decarboxylase 65-deficient mice. In contrast to wild-type and heterozygous animals, ICA69(null) NOD congenics fail to generate, even after immunization, cross-reactive T cells that recognize the dominant Tep69 epitope in ICA69, and its environmental mimicry Ag, the ABBOS epitope in BSA. This antigenic mimicry is thus driven by the endogenous self Ag, and not initiated by the environmental mimic. Insulitis, spontaneous, and adoptively transferred diabetes develop normally in ICA69(null) NOD congenics. Like glutamic acid decarboxylase 65, ICA69 is not an obligate autoantigen in diabetes. Unexpectedly, ICA69(null) NOD mice were resistant to cyclophosphamide (CY)-accelerated diabetes. Transplantation experiments with hemopoietic and islet tissue linked CY resistance to ICA69 deficiency in islets. CY-accelerated diabetes involves not only ablation of lymphoid cells, but ICA69-dependent drug toxicity in beta cells that boosts autoreactivity in the regenerating lymphoid system.     

云南含笑天然居群的表型多样性分析

为揭示云南含笑天然居群表型变异程度和变异规律,以云南昆明地区天然分布的云南含笑为研究对象,调查了6个居群180个单株的14个表型性状,采用巢式方差分析、变异系数、相关分析、Shannon-Weaver多样性指数分析和聚类分析等方法,分析了居群间和居群内表型多样性.结果表明:(1)云南含笑表型性状在居群间和居群内存在极其丰富的多样性,14个表型性状平均表型分化系数(24.38％)小于居群内变异(75.62％),居群内变异是表型变异的主要来源;14个表型性状的变异系数(CV)在16.20％～60.11％之间,表明云南含笑居群内表型性状离散程度较高.(2)对云南含笑各居群的Shannon-Weaver指数分析表明,云南含笑各居群具有丰富的多样性,总体表型多样性指数为1.772.(3)利用居群间欧氏距离进行的UPGMA聚类分析结果表明,云南含笑6个天然居群可以聚为3类,而且表型性状并没有严格依地理距离而聚类.     

Cytoplasmic modification of the nuclear lamina during pronuclear-like transformation of mouse blastomere nuclei.

During the successive interphases of cleaving mouse embryos the nuclear periphery diminishes its reactivity to anti-lamin A and C antibodies. This developmentally regulated characteristic can be modified by exposure of the blastomere nuclei to metaphase II (M II) oocyte cytoplasm followed by activation. In the current study we define the cytoplasmic conditions necessary for this modification of 8-cell and 16-cell stage nuclei in hybrids obtained by fusion with metaphase II arrested oocytes, oocytes at various time points after parthenogenetic activation, naturally fertilized eggs (zygotes) and interphase 2-cell embryo blastomeres. The intensity of fluorescence obtained with anti-lamins A/C in the blastomere nuclei increases as a result of fusion with freshly activated oocytes or early zygotes (first 3.0-5.5 h in the case of parthenogenetic activation), and not when eggs or 2-cell blastomeres advanced in interphase are used as partners for fusion. This transformation of the A/C lamin pattern is correlated with the ability to promote pronucleus-like growth of blastomere nuclei in hybrids. Blastomere nuclei introduced into M II-arrested oocytes undergo premature chromatin condensation and dissolution of the nuclear lamina. The results are discussed with regard to certain particularities of the first embryonic interphase of the mouse and the potential involvement of nuclear lamins in pronuclear growth.     

Molecular Interlayers in Hybrid Perovskite Solar Cells

Organic–inorganic hybrid perovskite solar cells (PSC) are promising third‐generation solar cells. They exhibit good power conversion efficiencies and in principle they can be fabricated with lower energy consumption than many more established technologies. To improve the efficiency and long‐term stability of PSC, organic molecules are frequently used as “interlayers.” Interlayers are thin layers or monolayers of organic molecules that modify a specific interface in the solar cell. Here, the latest progress in the use of interlayers to optimize the performance of PSC is reviewed. Where appropriate interesting examples from the field of organic photovoltaics (OPV) are also presented as there are many similarities in the types of interlayers that are used in PSC and OPV. The review is organized into three parts. The first part focuses on why organic molecule interlayers improve the performance of the solar cells. The second section discusses commonly used molecular interlayers. In the last part, different approaches to make thin and uniform interlayers are discussed.     

Spontaneous restoration of epiphytic lichen biota in managed forests planted on habitats typical for temperate deciduous forest

The study examines the changes of epiphytic lichen diversity in differently aged stands developing after clear cutting and pine planting on fertile habitats typical for deciduous forests. The study was conducted within one large complex consisting of pine, mixed pine-hornbeam and typical old oak-linden-hornbeam forests in northern Poland. Epiphytic lichens were recorded in 50 study plots randomly selected within 5 forest stand classes of a different structure and age, ranging from 80 to over 220 years. Altogether 143 lichen species were recorded, of which only 41 were entirely nonspecific, and were occurring in all the studied forest stand classes. Significant differences in lichen species richness between stand classes were found and the number of species increases with the forest age. Lichen species composition also differs and its changes progress towards restoration of lichen biota typical for deciduous forest consistent with the habitat. The age of the forest has the most significant effect on the biodiversity of lichen biota. Microhabitat space provided by oaks is highly desirable since it greatly enriches lichen biota in forests. Phorophyte specificity of particular lichens were assessed. Hornbeam and oak have the greatest number of species mostly confined to them and constitute a main refuge for lichens with a high conservation value. The changes of lichen biota are basically parallel with the changes of the forest stand structure. The selection of some parts within managed pine forests that should not be assigned for cutting in the future can be a simple procedure which helps to restore and preserve forest biodiversity.