F-box proteins in flowering plants

In eukaryotes, the ubiquitin-mediated protein degradation pathway has been shown to control several key biological processes such as cell division, development, metabolism and immune response. F-box proteins, as a part of SCF (Skp1-Cullin (or Cdc53)-F-box) complex, functioned by interacting with substrate proteins, leading to their subsequent degradation by the 26S proteasome. To date, several F-box proteins identified in Arabidopsis and Antirrhinum have been shown to play important roles in auxin signal transduction, floral organ formation, flowering and leaf senescence. Arabidopsis genome sequence analysis revealed that it encodes over 1000 predicted F-box proteins accounting for about 5% of total predicted proteins. These results indicate that the ubiquitin-mediated protein degradation involving the F-box proteins is an important mechanism controlling plant gene expression. Here, we review the known F-box proteins and their functionsin flowering plants.     

Peat record reflecting Holocene climatic change in the Zoigê Plateau and AMS radiocarbon dating

Through the use of reliable AMS dating of high resolution (15–30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.     

对"矛盾"、"对立"范畴的再认识

韩非的“矛盾”富言属于逻辑矛盾。他的“矛盾”思想则是非此即彼、非彼即此,二者必居其一。这种仅仅在对立两极中的思维方法并非完全正确。哲学上的辩证关系,借用“矛盾”、“对立”范畴来表述,也不十分恰当,因为矛与盾不是对立的双方,而辩证关系也应包括对立统一、鼎立统一、多立统一。所以我们必须确立立体矛盾观,即对立面-中介-对立面,或正中反矛盾论,或同异反分析法。     

Sensitivity dependence of surface plasmon resonance based sensors on prism refractive index

We theoretically and experimentally demonstrate that refractive index of the prism used to load metal film has significant influence on sensitivity of surface plasmon resonance based sensors. The prism with lower refractive index gives the sensors a higher sensitivity in detecting refractive index variations of a sample. We attribute this effect to the fact that a prism with low refractive index will increase coupling distance between surface plasmons and the medium under investigation. Foundation item: Supported by Wuhan University and National Education Ministry of China Biography: Wang Guo-ping (1964-), male, Professor, research direction: bolographic materials, diffractive optical elements, optical properties of metallic nanopracticles and metal-dielectric nanostructures     

A semantic retrieval method based on the fuzzy reasoning

This paper gives a semantic fuzzy retrieval method of multimedia object, discusses the principle of fuzzy semantic retrieval technique, presents a fuzzy reasoning mechanism based on the knowledge base, and designs the relevant reasoning algorithms. Researchful results have innovative significance. Foundation item: Supported by the Natural Science Foundation of Hubei Province(No. 200J157) Biography: Cao Jia-heng(1946-), male, Professor, research direction: multimedia software, artificial intelligence.     

Model of production planning and scheduling in shop floor based on collaboration and competition

The planning and scheduling in real shop floor is actually achieved by coordination between different persons. In this process, cooperation is mainstream, but competition also exists, for example, the competition between different groups, operators with the same skill, etc. In multi-agent based shop floor management and control system, this competition and cooperation relation must be embodied. The general process of shop floor production planning and scheduling is studied, and a colored Petri-net model for the competition and cooperation process of three main agents in such system to achieve shop floor production planning and scheduling is presented. The evaluating method of bids in bidding process that especially embodies the competition relationship is also presented. This colored Petri-net model gives a clear illustration of this complex coordination process to system designers, effectively promotes the cooperative development. Foundation item: Supported partly by the Hi-tech Program of China (China 863) (No. 863-511-943-009) and the National Natural Science Foundation of China(No. 59990470) Biography: Liu Shi-ping(1971-), male, Ph. D. candidate, research direaction: CIMS, intelligent manufacturing.     

Crosstalk model and estimation formula for VLSI interconnect wires

We develop an interconnect crosstalk estimation model on the assumption of linearity for CMOS device. First, we analyze the terminal response of RC model on the worst condition from the S field to the time domain. The exact 3 order coefficients in S field are obtained due to the interconnect tree model. Based on this, a crosstalk peak estimation formula is presented. Unlike other crosstalk equations in the literature, this formula is only used coupled capacitance and grand capacitance as parameter. Experimental results show that, compared with the SPICE results, the estimation formulae are simple and accurate. So the model is expected to be used in such fields as layout-driven logic and high level synthesis, performance-driven floorplanning and interconnect planning.     

Genetic analysis of the mouse brain proteome

Proteome analysis is a fundamental step in systematic functional genomics. Here we have resolved 8,767 proteins from the mouse brain proteome by large-gel two-dimensional electrophoresis. We detected 1,324 polymorphic proteins from the European collaborative interspecific backcross. Of these, we mapped 665 proteins genetically and identified 466 proteins by mass spectrometry. Qualitatively polymorphic proteins, to 96%, reflect changes in conformation and/or mass. Quantitatively polymorphic proteins show a high frequency (73%) of allele-specific transmission in codominant heterozygotes. Variations in protein isoforms and protein quantity often mapped to chromosomal positions different from that of the structural gene, indicating that single proteins may act as polygenic traits. Genetic analysis of proteomes may detect the types of polymorphism that are most relevant in disease-association studies.     

Thyroid hormone controls carnitine status through modifications of γ-butyrobetaine hydroxylase activity and gene expression

The carnitine system plays a key role in β-oxidation of long-chain fatty acids by permitting their transport into the mitochondrial matrix. The effects of hypothyroidism and hyperthyroidism were studied on γ-butyrobetaine hydroxylase (BBH), the enzyme responsible for carnitine biosynthesis in the rat. In rat liver, BBH activity was decreased in the hypothyroid state and increased in hyperthyroid animals. The modifications in BBH activity correlated with changes in the enzyme Vmax values. These changes were shown to be related to hepatic BBH mRNA abundance. Thyroid hormones are known to interact with lipid metabolism, in particular by increasing long-chain fatty acid oxidation through activation of carnitine-dependent fatty acid import into mitochondria. Our study showed that thyroid hormones also increased carnitine bioavailability. Received 23 October 2001; received after revision 11 January 2002; accepted 15 January 2002     

Differential multiplicity of MDR alcohol dehydrogenases: enzyme genes in the human genome versus those in organisms initially studied

Screens were made for alcohol dehydrogenase (ADH) of the classical type (the MDR superfamily) in translations of human and other relevant genomes, corresponding to the organism types from which the enzyme was initially purified. Considerable multiplicities were detected in the dimeric enzymes from higher eukaryotes: seven forms in the human (plus three pseudogenes), all genes on chromosome 4, in the order class IV --> class Igamma --> class Ibeta --> class Ialpha --> class V --> class II --> class III, and eight forms in Arabidopsis thaliana (plus one pseudogene). These multiplicity patterns, and the species variability in the animal (human/mouse) and plant (Arabidopsis/pea) lines, suggest parallel but separate duplicatory events, giving rise to three families of dimeric MDR-ADH: class III, the animal non-class III, and the plant non-class III enzymes, with functions in formaldehyde elimination, in alcohol/aldehyde detoxication and in special pathways in higher eukaryotes. Multiplicity, although to a lesser extent, was also noted in tetrameric MDR-ADH, suggesting functional divergence between the dimeric and tetrameric enzymes. Combining these observations, at least five levels of divergence are reflected in the present ADH forms, corresponding to nodes at the SDR/MDR, the dimer/tetramer, the class III/non-class III, the class I/P, and the more recent class splits, each branch associated with separate functional patterns.