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981.
Hubert Gantelet Christine Ladrat Anne Godfroy Georges Barbier Francis Duchiron 《Biotechnology letters》1998,20(9):819-823
Two out of three extremely thermophilic anaerobic archaea, isolated from deep-sea hydrothermal vents, produced pullulanase activity in the presence of maltose in the growth medium. Enzyme activities were mainly extracellular and characterized by optimum temperatures of 95°C and 80–95°C, optimum pH of 5.0–7.0 and a high degree of thermostability. One strain when grown in a fermenter with maltose as inducer produced pullulanase at 35 U/l. © Rapid Science Ltd. 1998 相似文献
982.
983.
Sophie Godard Laurent Schibler Anne Oustry Edmond P. Cribiu Gérard Guérin 《Mammalian genome》1998,9(8):633-637
A horse BAC library was constructed with about 40, 000 clones and mean insert size of 110 kb representing a 1.5 genome equivalent
coverage and a probability of finding a single sequence of 0.75. It was characterized by PCR screening of about 130 sequences
of horse microsatellites and exonic gene sequences retrieved from databases. BACs containing 8 microsatellites and 12 genes
were subsequently localized by fluorescent in situ hybridization (FISH) on chromosomes. Two linkage groups were newly assigned
to chromosomes: LG2 to ECA3 and LG5 to ECA24, and five linkage groups were also oriented—LG3, LG4, LG5, LG8, and LG12—leaving
only three groups unassigned. This work showed how this library makes an integrated map a realistic objective for the near
future and how it can make comparative mapping more efficient in a search for candidate genes of interest.
Received: 9 January 1998 / Accepted: 13 April 1998 相似文献
984.
985.
Anne Schoendorf Roberte Bronner Jean Broadhvest François Bernier 《Sexual plant reproduction》1998,11(3):140-147
In the tobacco (Nicotiana tabacum) Appendix mutant, anthers are tipped by a miniature style and stigma. The outgrowth appears on the anther when it is already
differentiating and follows the developmental timing of the central carpel. The Appendix mutation thus represents a late homeotic
transformation suggesting that the APPENDIX (APX) gene either could be a misregulated organ identity gene or could be involved in regulating the expression of such genes.
RFLP analysis with two class B (TM6 and NTGLO) and a class C (NAG) probes revealed that the Appendix phenotype is not caused by a mutation in one of these genes. However, in situ hybridization
showed important changes in the expression of NTGLO and NAG in the mutant when compared with wild-type tobacco. Surprisingly, although no phenotypic alteration other than the style
and stigma outgrowth is observed in the Appendix mutant, changes in class B and class C gene expession were not restricted
to the anther tip cells from which the outgrowth originates. As expected, NAG was expressed in the Appendix outgrowth but it was also overexpressed in the normal third and fourth whorl organs at the
time the outgrowth, as well as the central styles and stigmas, differentiated. Overexpression of a class C gene is probably
responsible for the Appendix phenotype. In normal and mutant flowers, NTGLO was expressed in the second, third and fourth whorls up to the time of carpel fusion. Expression of this class B gene then
ceased in the fourth whorl organs but was reactivated at later stages only in the styles and stigmas as well as in the outgrowths
of the mutant. It thus seems that the function of the APX gene is either to regulate the late expression of organ identity genes or to control cell proliferation in such a way that,
in the mutant, some cells are in a state where they respond in an unusual way to developmental signals.
Received: 17 October 1997 / Revision accepted: 24 March 1998 相似文献
986.
LCA of concrete and steel building frames 总被引:1,自引:0,他引:1
Asa Jonsson Thomas Bjorklund Anne -Marie Tillman 《The International Journal of Life Cycle Assessment》1998,3(4):216-224
The effects on the external environment of seven concrete and steel building frames representative of present-day building
technology in Sweden were analysed using LCA methodology. Objects of the study included frame construction and supplementary
materials. Several-storey offices and dwellings were studied. The functional unit was defined as one average m2 of floor area during the lifetime of the building. Inventory data were elaborated for concrete and steel production, the
building site, service life, demolition and final disposal. Parameters included were raw material use, energy use, emissions
to air, emissions to water and waste generation. The inventory results were presented and evaluated as such, in addition to
an interpretation by using three quantitative impact assessment methods. Parameters that weighed heavily were use of fossil
fuels, CO2, electricity, SOx
2 NOx
2 alloy materials and waste, depending on what assessment method was used. Over the life cycle, building production from cradle
to gate accounted for about the same contribution to total environmental loads as maintenance and replacement of heat losses
through external walls during service life, whereas demolition and final disposal accounted for a considerably lower contribution. 相似文献
987.
988.
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990.
Recent work on cell division and chromosome orientation and partitioning in Bacillus subtilis has provided insights into cell cycle regulation during growth and development. The cell cycle is an integral part of development and entrance into sporulation is modulated by signals that transmit the status of DNA integrity, chromosome replication and segregation. In addition, B. subtilis modifies cell division and DNA segregation to establish cell-type-specific gene expression during sporulation. 相似文献