基于生物真核细胞的人工智能程序研究

针对传统人工智能系统具有训练成本高且处理复杂逻辑问题耗时较大的局限性,从生物真核细胞的结构与机理中汲取改进人工智能的启示,构建基于真核生物细胞的人工智能基本组成单位虚拟细胞。完成了对虚拟细胞的数据及行为建模,并对细胞运行感知展开了仿真实验。通过对仿真结果的分析,说明设计的生物真核细胞程序对人工智能领域的发展具有一定的研究价值。

制药专业的激生物生理学教学探讨

微生物生理学是从生理生化的角度研究微生物细胞的形态、结构和功能,揭示微生物生命活动规律的科学。作为微生物制药专业的主课之一,微生物生理学涉及到药品生产、药物设计及药品检验等方面的内容。近年来微生物生理学在基础理论实际应用方面有很大进展,每年都有大量的文献报道产生,而国内有关微生物生理学的教材,最近的出版日期也是1993年。

医学微生物学理论课教学浅谈

医学微生物学是医学基础重要课程之一,如何在现有的条件下,在有限的时间内充分发挥师生双方的积极性,做到师生同步思维,这是理论课教学的重要课题。1 认真备课1.1 参考教学大纲 教学大纲是教学活动的纲领性文件,在全面熟悉教学大纲的基础上才能进一步研究教材,根据大纲写出教学计划和学时安排。

Distributions of Picophytoplankton and Phytoplankton Pigments Along a Salinity Gradient in the Changjiang River Estuary, China

We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary.The average numbers of Synechococcus spp.（Syn） and picoeukaryotes （Euk） were （2.7 ±5.1）×l03 and （1.1±1.4）×l03 cells mL-1,respectively.Prochlorococcus spp.（Pro） was only found in the high-salinity brackish water with the concentration of 3.0× 10^3 cells mL-1.Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk.The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean.The response of different picophytoplankton groups to environmental variables was different.Water temperature was more important in its control over Euk than over Syn,while nutrients were more important in their influence over Syn than over Euk.Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient （i.e.,freshwater zone with 0-5 range,fresh and saline water mixing zone with 5-20 range,and high-salinity brackish water zone with 20-32 range）,where three different phytoplankton communities were discovered,suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.

Epigenetics： heterochromatin meets RNAi

The term epigenetics refers to heritable changes not encoded by DNA. The organization of DNA into chromatin fibers affects gene expression in a heritable manner and is therefore one mechanism of epigenetic inheritance. Large parts of eukaryotic genomes consist of constitutively highly condensed heterochromatin, important for maintaining genome integrity but also for silencing of genes within. Small RNA, together with factors typically associated with RNA interference （RNAi） targets homologous DNA sequences and recruits factors that modify the chromatin, com- monly resulting in formation of heterochromatin and silencing of target genes. The scope of this review is to provide an overview of the roles of small RNA and the RNAi components, Dicer, Argonaute and RNA dependent polymerases in epigenetic inheritance via heterochromatin formation, exemplified with pathways from unicellular eukaryotes, plants and animals.

A versatile cloning vector facilitates target geneexpression in prokaryotic and eukaryotic cells

Objective： To facilitate manipulation of gene expression in different host cells, we used pEGFP-N1 as backbone to construct a versatile vector that can drive foreign gene expression in prokaryotic and eukaryotic cells. Methods： A cloning and expression vector, pEGFP-NI-lac, was constructed by inserting the prokaryotic lac promoter of pUC 19 into the eukaryotic expression vector, pEGFP-N1, between the eukaryotic PCMV promoter and enhanced green fluorescent protein （EGFP） open reading frames. To assess the function of pEGFP-NI-lac, the nucleotide sequence encoding the hepatitis C virus （HCV） core protein was cloned into the multiple cloning sites. Western blotting analysis was used to detect the expression of the HCV core protein in Escherichia coli DH5a and HepG2 cells. Results： Restriction enzyme digestion and sequence analysis indicated that pEGFP-NI-lac was successfully constructed and the HCV core gene was cloned into this vector. The Western blotting results showed that pEGFP-NI-lac promoted expression of HCV core gene in prokaryotic E. coli DH5a and eukaryotic HepG2 cells. Conclusion： The pEGFP-NI-lac vector has been successfully constructed and functions in both prokaryotic and eukaryotic cells. The EGFP reporter can be used as an insert-inactivation marker for clone selection or as an expression tag. This vector can be used for cloning and expression of genes in both prokaryotic and eukaryotic cells, making gene cloning, expression and functional studies convenient as well as time- and labor-efficient

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.

Total chemical and semisynthetic approaches for the preparation of ubiquitinated proteins and their applications

Protein ubiquitination is an important post-translational modification(PTM) in eukaryotic organisms that regulates a variety of cellular processes, such as protein degradation, signal transduction, apoptosis, and DNA damage tolerance. To decipher mechanistically the diverse biological functions of ubiquitination, homogeneous ubiquitinated proteins are greatly needed.Although direct isolation from cell source and in vitro enzymatic methods can be used to produce such proteins, these methods often suffer from problems of low yield or heterogeneous products. Comparably, total chemical and semisynthetic approaches offer good alternatives to produce the ubiquitinated proteins with high purity and selectivity. This review summarizes the recent developments of protein ubiquitination strategies and the use of the synthesized proteins to help garner structural and functional insight into the inner workings of the ubiquitin system.

Archaeal chromatin proteins

Archaea, along with Bacteria and Eukarya, are the three domains of life. In all living cells, chromatin proteins serve a crucial role in maintaining the integrity of the structure and function of the genome. An array of small, abundant and basic DNA-binding proteins, considered candidates for chromatin proteins, has been isolated from the Euryarchaeota and the Crenarchaeota, the two major phyla in Archaea. While most euryarchaea encode proteins resembling eukaryotic histories, crenarchaea appear to synthesize a number of unique DNA-binding proteins likely involved in chromosomal organization. Several of these proteins （e.g., archaeal histones, Sacl0b homologs, Sul7d, Cren7, CC1, etc.） have been extensively studied. However, whether they are chromatin proteins and how they function in vivo remain to be fully understood. Future investiga- tion of archaeal chromatin proteins will lead to a better understanding of chromosomal organization and gene expression in Archaea and provide valuable information on the evolution of DNA packaging in cellular life.