Closed-Loop Control of Active Sensing Movements Regulates Sensory Slip

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播种密度和基肥条件对晚籼稻旱育秧苗某些生理特性的影响

研究了1995年晚季不同播种密度和不同基肥对华南稻区晚籼稻旱育秧苗某些生理特性的影响。结果表明,在2种播种密度和5种基肥构成的10个处理中,秧苗叶龄、苗高和假茎宽等均无明显差异。在播种量为125g m-2条件下,虽然秧苗的总生长量较低,但其干/鲜重比值仍较播种密度为65gm-2略高;不同处理间的功能叶叶绿素含量(a b)、白根数/株和根活力呈显著差异,其中以沤熟有机肥和高无机肥用量作基肥的处理效果明显优于低无机肥用量作基肥的处理。因此,在进行旱育秧苗床培肥中,应注意以施用有机肥为主,适当补充无机肥,才能获得根系发达、活力强的健壮旱秧,为移栽后的叶蘖早发打基础。     

Thuja occidentalis: identification of volatiles and electroantennographic response by the invasive cedar bark beetle,Phloeosinus aubei

Recently, the distribution of the Mediterranean cedar bark beetle, Phloeosinus aubei Perris (Coleoptera: Scolytidae), has expanded to Central Europe. Reported mostly on cypress in the Mediterranean area, potential host plants in the invaded range include other scale‐leafed conifers, such as cultivars of arborvitae, Thuja occidentalis L. To reveal potential kairomonal cues for P. aubei, volatiles of T. occidentalis were collected and analysed by gas chromatography with electroantennographic detection (GC‐EAD). Assignments of chemical structures of antennally active components were carried out by gas chromatography linked to mass spectrometry (GC‐MS) using authentic reference samples. Antennal responses to synthetic samples of the identified compounds were studied by electroantennography (EAG), with antennae of female and male P. aubei. GC‐EAD analysis of head space volatiles of T. occidentalis revealed 22 antennally active compounds, of which 21 were identified. The most abundant components were α‐ and β‐thujone, fenchone, camphor, terpinen‐4‐ol, bornyl acetate and α‐terpinyl acetate, all of which are oxygenated monoterpenes. When EAG activities of synthetic samples were compared, the most intensive responses from female antennae were elicited by a mixture of α‐ and β‐thujone, followed by (–)‐terpinen‐4‐ol, (+)‐camphor, cis‐4‐thujanol, (+)‐sabina ketone, (+)‐terpinen‐4‐ol, isopulegone, (–)‐fenchone, borneol, (3Z)‐hexen‐1‐ol, (–)‐1‐octen‐3‐ol and (+)‐sulcatol. Male antennae responded the most to (–)‐terpinen‐4‐ol and cis‐4‐thujanol followed by the mixture of α‐ and β‐thujone. The next highest responses were elicited by (+)‐camphor, borneol, (+)‐terpinen‐4‐ol, (+)‐sulcatol and (+)‐sabina ketone. Striking differences were found between responses to the enantiomers of fenchone, sulcatol and 1‐octen‐3‐ol, whereas responses to the enantiomers of terpinen‐4‐ol did not differ significantly from each other. Several antennally active volatiles of T. occidentalis have also been reported from cypress and various other members of the Cupressaceae, suggesting that the sensory apparatus of P. aubei may recognize the shared components, which may enable rapid adaptation to new hosts in the invaded areas.     

Membrane phosphorylation leads to the partial detachment of the chlorophyll a/b protein from Photosystem II

The hypothesis that the chlorophyll fluorescence decline due to membrane phosphorylation is caused principally by the detachment and removal of LHCP from the LHCP-PS II matrix is examined. It is demonstrated that when membranes are phosphorylated in the dark (a) the fluorescence decline is greater when excited by light enriched in wavelengths absorbed mainly by LHCP (475 nm) than when excited by light absorbed to a large extent also by the PS II complex (435 nm), (b) titration with different artificial quenchers of chlorophyll fluorescence is unchanged after the phosphorylation-induced fluorescence decline, and (c) the F_v/F_m ratio does not change after the phosphorylation-induced fluorescence decline. These data indicate that it is indeed principally LHCP that interacts with the quencher (PS I presumably). This interaction involves a small fraction of the total PS II-coupled LHCP, which becomes functionally detached from the LHCP-PS II matrix.     

Mapping of recognition sites for the restriction endonuclease from Escherichia coli K12 on bacteriophage PM2 DNA.

Several mutations in gene B of phage S13 appear to shorten the B protein by elimination of an N-terminal fragment, without destroying the B protein function. The shortened B protein resulting from each of these mutations can block the unique DNA-nicking properties of the S13 gene A protein. Because of the block in gene A function, normal gene B protein may have a function in phage DNA synthesis in addition to its known role in catalyzing capsid assembly.From gel electrophoresis the mutant B protein is estimated to be shorter than the normal S13 B protein by 1720 ± 70 daltons and is therefore believed to be an internal reinitiation fragment. The reinitiated fragments are functional and are made in about twice the amount of the normal B protein.The phage mutants which yield the reinitiation fragments are double mutants, each phage containing the same gene B nonsense mutation and each appearing to contain a different compensating gene B mutation. Various data support the assumption that the compensating mutations are frame-shifts, including the fact that suppression does not restore the normal-sized B protein. The reinitiation is assumed to occur at a pre-existing out-of-phase initiator codon, near the nonsense triplet; the correct reading frame would then be restored by each of the several different compensating mutations.The position of the normal S13 B protein in the gel electrophoresis pattern has been located both by elimination and shifting of the B peak, using appropriate amber mutants. The molecular weight of the S13 B protein is about 17,200, and is 2100 daltons less than the B protein of phage φX174; the S13 B protein can nevertheless substitute for the φX 174 B protein. Thus substantial portions of the B protein can be deleted without destroying its function.     

Modeling Metal Flow Systems

Substance flow analysis (SFA) is a frequently used industrial ecology technique for studying societal metal flows, but it is limited in its ability to inform us about future developments in metal flow patterns and how we can affect them. Equation‐based simulation modeling techniques, such as dynamic SFA and system dynamics, can usefully complement static SFA studies in this respect, but they are also restricted in several ways. The objective of this article is to demonstrate the ability of agent‐based modeling to overcome these limitations and its usefulness as a tool for studying societal metal flow systems. The body of the article summarizes the parallel implementation of two models—an agent‐based model and a system dynamics model—both addressing the following research question: What conditions foster the development of a closed‐loop flow network for metals in mobile phones? The results from in silico experimentation with these models highlight three important differences between agent‐based modeling (ABM) and equation‐based modeling (EBM) techniques. An analysis of how these differences affected the insights that could be extracted from the constructed models points to several key advantages of ABM in the study of metal flow systems. In particular, this analysis suggests that a key advantage of the ABM technique is its flexibility to enable the representation of societal metal flow systems in a more native manner. This added flexibility endows modelers with enhanced leverage to identify options for steering metal flows and opens new opportunities for using the metaphor of an ecosystem to understand metal flow systems more fully.     

A vector for recombinant DNA in Staphylococcus aureus

Staphylococcal plasmids pS194 and pSC194 which confer streptomycin and streptomycin-chloramphenicol resistance respectively have been used as vectors for construction of recombinant DNA, since they each carry one single recipient site for endonuclease EcoRI. Hybrid DNA does not express streptomycin resistance, a marker which is present in both vectors, presumably because the marker gene is cleaved by EcoRI. A chloramphenicol marker present in pSC194 was used for positive hybrid selection. Hybrid plasmids generated by joining pSC194 with one or more of the four EcoRI fragments of the large (18.1-10(6) daltons) staphylococcal plasmid pI258 were constructed and permitted us to develop a physical map for pI258.     

Development of an anti-hepatitis B virus (HBV) agent through the structure-activity relationship of the interferon-like small compound CDM-3008

Hepatitis B, a viral infectious disease caused by hepatitis B virus (HBV), is a life-threatening disease that leads liver cirrhosis and liver cancer. Because the current treatments for HBV, such as an interferon (IFN) formulation or nucleoside/nucleotide analogues, are not sufficient, the development of a more effective agent for HBV is urgent required.CDM-3008 (1, 2-(2,4-bis(trifluoromethyl)imidazo[1,2-a][1,8]naphthyridin-8-yl)-1,3,4-oxadiazole) (RO8191)) is a small molecule with an imidazo[1,2-a][1,8]naphthyridine scaffold that shows anti-HCV activity with an IFN-like effect. Here, we report that 1 was also effective for HBV, although the solubility and metabolic stability were insufficient for clinical use. Through the structure-activity relationship (SAR), we discovered that CDM-3032 (11, N-(piperidine-4-yl)-2,4-bis(trifluoromethyl)imidazo[1,2-a][1,8]naphthyridine-8-carboxamide hydrochloride) was more soluble than 1 (>30?mg/mL for 11 versus 0.92?mg/mL for 1). In addition, the half-life period of 11 was dramatically improved in both mouse and human hepatic microsomes (T1/2, >120?min versus 58.2?min in mouse, and >120?min versus 34.1?min in human, for 11 and 1, respectively).     

Incidence and management of white grub, Schizonycha ruficollis on seedlings of teak （Tectona grandis Linn, f,）

In investigation was conducted annually from 2002 to 2005 between the second week of May and the end of September on the incidence of scarab beetle, Schizonycha ruficollis （Fabricius） in a teak （Tectona grandis L.f.） nursery at Ramdongari, Nagpur, India. The immature stages, that is white grubs of the scarab beetle damaged 14%-52% of teak seedlings in the nursery beds, whereas the adult of the species, that is scarab beetles, were recorded on three new host trees （ Ziziphus xylopyra, Acacia catechu and A. leucophloea） in addition to the reported hosts such as ziziphus （Z. jujuba and Z. mauritiana）. Beetles of the S. ruficollis started emerging from the nursery beds just after the pre-monsoon showers and continued for 10-18 days. While beetle of S. ruficollis defoliated tree hosts available in the surroundings, the immature stages of the beetle caused major damage by feeding on root systerfls of teak seedlings with symptoms of wilting and mortality in forest nursery beds. The result of chemical and biological treatments for the management of grubs of S. ruficollis in nursery beds indicated phorate 10% granular at the rate of 20 g/m^2 and chlorpyriphos 20% emulsifiable concentrate at the rate of 5.0 mL/m^2 to be effective. Grubs of S. ruficollis have not been recorded previously as a major pest of teak （T. grandis）. This is also the first report on occurrence of S. ruficollis adults on tree hosts such as Z. xylopyra, A. catechu and A. leucophloea. White grubs being pests of economic importance and the toughest insects to manage, information given in this paper on incidence, pest status and management of Schizonycha ruficollis is of importance to researchers and forest nursery managers.