基数比较法—高效的信息表求核方法

目前的求核方法大多基于决策表,基于信息表的报道不多。为此,先寻找理论依据,说明了U/C与U(/C-{a})的内在关系,证明了U(/C-{a})≠U/C与真细分的等价性,证明了可以通过比较等价类和它子类的基数来判断是否真细分。然后基于最高位优先基数排序思想,应用正整数有序分拆特性定义了一个用于记录和比较等价类基数的数组,接着设计了一个信息表求核算法,时间复杂度为O(|C|2|U)|,空间复杂度为O(|U)|。算法的主要贡献是将求核问题转化为等价类生成过程中的集合基数比较问题。通过实例验证了算法的正确性。

A PSTAIRE CDK-like protein localizes in nuclei and cytoplasm of Physarum polycephalum and functions in the mitosis

CDKs play key roles in controlling cell cycle progression in all eukaryotes. In plants, multiple CDKs are present,among which the best characterized CDKs are PSTAIRE CDKs. In this study, we carried out Western blot,immunoelectron microscopy and antibody treatment with an anti-PSTAIRE monoclonal antibody to explore the subcellular localization and functions of PSTAIRE CDKs in Physarum polycephalum. The results of Western blot and immunoelectron microscopy showed that in P. polycephalum, a PSTAIRE CDK-like protein was 34 kD in molecular weight and located in both nuclei and cytoplasm. In nuclei, the protein was mainly associated with chromosomes and nucleoli. The expression of the PSTAIRE CDK-like protein in both the plasmodia and nuclei showed little fluctuation through the whole cell cycle. When treated with an anti-PSTAIRE monoclonal antibody at early S phase, the cells were arrested in S phase, and the mitotic onset of P. polycephalum was blocked for about 1 h when treated at early G2 phase.Our data indicated that the PSTAIRE CDK- like protein has a direct bearing on the mitosis.

Termination of DNA Replication and the Role of Enzymes in Recombination

DNA is the genetic material of all cells, containing coded information about cellular molecules and processes. DNA consists of two polynucleofide strands twisted around each other in a double helix. The first step in cellular division is to replicate DNA so that copies can be distributed to daughter cells. Additionally, DNA is involved in transcribing proteins that direct cell growth and activities. However, DNA is tightly packed into genes and chromosomes. In order for replication or transcription to take place, DNA must firstly unpack itself so that it can interact with enzymes. DNA packing can be visualized as two very long strands that have been intertwined millions of times, tied into knots, and subjected to successive coiling. However, replication and transcription are much easier to accomplish if the DNA is neatly arranged rather than tangled up in knots. Enzymes are essential to unpacking DNA. Enzymes act to slice through individual knots and reconnect strands in a more orderly way. Hypothesizing that Termination of DNA replication proteins gave rise to those of eukaryotes during evolution, we chose the DNA polymerase （which infects microalgae） as the basis of this analysis, as it represents a primitive recombination. We show that it has significant similarity with replicative DNA polymerases of eukaryotes and certain of their large DNA. Sequence alignment confirms this similarity and establishes the presence of highly conserved domains in the polymerase amino terminus. Subsequent reconstruction of a phylogenetic tree indicates that these algal DNA are near the root of the containing all recombination. DNA polymerase delta members but that this does not contain the polymerases of other DNA. We consider arguments for the polarity of this relationship and present the hypothesis that the replication genes of DNA. DNA can be visualized as a complicated knot that must be unknotted by enzymes in order for replication or transcription to occur. It is perhaps not surprising then that connections between mathematical knot theory and biology have been discovered. By thinking of DNA as a knot, we can use knot theory to estimate how hard DNA is to unknot. This can help us estimate properties of the enzymes that unknot DNA.

The Biological Activity of Some Bacteria as Biocides to Protect Sesame Crop （Sesamum indicum） from Fungi Diseases

Two experiments were conducted during 2006-2007 in Complete Randomized Design （CRD） to test the biological activity of Pseudomonas bacteria as biocides to protect sesame crop from some fungi and to evaluate its efficiency as plant growth promoting First experiment investigated the effects of Pseudomonas putida2 and Pseudomonas fluorescens3 on germination and seedlings growth of sesame crop against Pythium, Alternaria and Fusarium under plastic house conditions. Second experiment conducted in large pots to investigate the effects of the two bacterial isolates on some morphological, productive and physiological characters of sesame plants against same fungi under normal conditions. Results showed very low germination and slowly seedlings growth in Pythium, Fusarium and Alternaria treatments respectively, but adding bacterial vaccine of Pseudomonas putida2 and Pseudomonas fluorescens3 as a Biocide to fungi treatments, increased the germination percent and seedlings growth of sesame crop significantly, 20 days after planting compared with control treatment. In the second experiment, control treatment scored germination by 52%, while vaccines of Pseudornonas putida2 and Pseudomonas fluorescence3 treatments increased germination percentage in Fusarium, Pythium and Alternaria treatments significantly in average more than 71%. Both isolates increased significantly Leaf number per plant, leaf area per plant, height of plant, branches number per plant, total dry weight of shoot per plant and chlorophyll content compared with other and control treatments. Similar significant effect for both isolates was recorded in seeds number per pod per plant, total weight of 1,000 seeds per plant and pods number per plant and percentage of N, P, K in total dry weight of shoot per plant and oil percentage in seeds per plant compared with other and control treatments. P. putida2 increased oil percentage in seeds by 43.3, 48.0 and 45.0% respectively while with P. fluorescens3 increased to 42.7, 44.0 and 43.7% respectively compared with control treatment （27.7%）. In general Pseudomonas putida2 increased most of growth characters much higher than Pseudomonas fluorescens3, it may related to siderophores compound and genetic factors.

Recruitment and reinforcement: maintaining epigenetic silencing

Cells need to appropriately balance transcriptional stability and adaptability in order to maintain their identities while responding robustly to various stimuli. Eukaryotic cells use an elegant "epigenetic" system to achieve this functionality. "Epigenetics" is referred to as heritable information beyond the DNA sequence, including histone and DNA modifications, nc RNAs and other chromatin-related components. Here, we review the mechanisms of the epigenetic inheritance of a repressive chromatin state,with an emphasis on recent progress in the field. We emphasize that(i) epigenetic information is inherited in a relatively stable but imprecise fashion;(ii) multiple cis and trans factors are involved in the maintenance of epigenetic information during mitosis; and(iii) the maintenance of a repressive epigenetic state requires both recruitment and self-reinforcement mechanisms.These mechanisms crosstalk with each other and form interconnected feedback loops to shape a stable epigenetic system while maintaining certain degrees of flexibility.

Greater soil microbial biomass loss at low frequency of N addition in an Inner Mongolia grassland

Soil microbial biomass is critical for biogeochemical cycling and serves as precursor for carbon(C)sequestration.The anthropogenic nitrogen(N)input has profoundly changed the pool of soil microbial biomass.However,traditional N deposition simulation experiments have been exclusively conducted through infrequent N addition,which may have caused biased effects on soil microbial biomass compared with those under the natural and continuous N deposition.Convincing data are still scarce about how the different N addition frequencies affect soil microbial biomass.By independently manipulating the frequencies(2 times vs.12 times N addition yr^(–1))and the rates(0–50 g N m^(−2) yr^(−1))of N addition,our study aimed to examine the response of soil microbial biomass C(MBC)to different N addition frequencies with increasing N addition rates.Soil MBC gradually decreased with increasing N addition rates under both N addition frequencies,while the soil MBC decreased more at low frequency of N addition,suggesting that traditional studies have possibly overestimated the effects of N deposition on soil microbial biomass.The greater soil microbial biomass loss with low N frequency resulted from the intensifed soil acidifcation,higher soil inorganic N,stronger soil C and N imbalance,less net primary production allocated to belowground and lower fungi to bacteria ratio.To reliably predict the effects of atmospheric N deposition on soil microbial functioning and C cycling of grassland ecosystems in future studies,it is necessary to employ both the dosage and the frequency of N addition.

A series of naphthalimide azoles: Design, synthesis and bioactive evaluation as potential antimicrobial agents

A series of naphthalimide azoles as potential antibacterial and antifungal agents were conveniently and efficiently synthesized starting from commercially available 6-bromobenzo[de]isochromene-l,3-dione. All the new compounds were characterized by NMR, IR, MS and HRMS spectra. Their antimicrobial activities were evaluated against four Gram-positive bacteria, four Gram-negative bacteria and two fungi using two-fold serial dilution technique. The biological assay indicated that most of the prepared compounds exhibited inhibition to the tested strains. In particular, the triazolium derivatives not only gave higher ef- ficacy than their corresponding precursory azoles, but also demonstrated comparable or even better potency than the reference drugs Chloromycin, Orbifloxacin and Fluconazole. Some factors including structural fragments, pH and ClogP values of the target molecules were also preliminarily discussed.