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21.
De León A Breceda GB Barba de la Rosa AP Jiménez-Bremont JF López-Revilla R 《Biotechnology letters》2003,25(17):1397-1402
The expression of penicillin acylase (PA), cloned in the pPA102 plasmid under control of the wild-type lac promoter and using galactose as inducer in Escherichia coli JM101, JM103 and JM105 transformant cells, was analyzed. The E. coli JM101/pPA102 cultures attained the highest specific activity of PA. For large scale PA production based on E. coli JM101/pPA102 a culture media with galactose instead of isopropyl-thio-galactopyranoside as inducer would be as successful and less expensive. 相似文献
22.
Diosque P Barnabé C Padilla AM Marco JD Cardozo RM Cimino RO Nasser JR Tibayrenc M Basombrío MA 《International journal for parasitology》2003,33(10):997-1003
A set of 65 Trypanosoma cruzi stocks from dogs, opossums, insect vectors and humans was isolated in a geographically restricted endemic area for Chagas' disease in Argentina and was analysed by multilocus enzyme electrophoresis for 15 loci. The results show that at least five multilocus genotypes (clonets) circulate in the study area, one belonging to T. cruzi IIe, one to T. cruzi IId and three clonets belonging to T. cruzi I; and they confirm the presence of these lineages in the country. The three clonets attributed to T. cruzi I were identical to each other for all loci except for Sod-2, where three different patterns were identified. These patterns suggest the presence of two homozygous genotypes and one heterozygous genotype. Our results also suggest association of clonet IIe with dogs, clonet IId with humans and the three T. cruzi I clonets with Didelphis albiventris. On the other hand, there was no significant association between Triatoma infestans and any particular clonet circulating in the area. These findings are consistent with the hypothesis of natural selection, from mixed populations of T. cruzi in vectors, toward more restricted populations in mammals. The epidemiological implications of the possible selection of different clonets by different mammal hosts and the significance of two homozygous genotypes and one heterozygous genotype for the Sod-2 locus are discussed. 相似文献
23.
León LG Machín RP Rodríguez CM Ravelo JL Martín VS Padrón JM 《Bioorganic & medicinal chemistry letters》2008,18(19):5171-5173
A set of gamma-lactones alpha,beta-fused and beta,gamma-fused to carbocycles have been synthesized and evaluated for their in vitro antiproliferative activities using the human cancer cell lines SW1573 (lung), T-47D (breast) and WiDr (colon). The compounds are obtained by intramolecular ring closing metathesis of the corresponding dienes. Active compounds exhibited GI(50) values in the range 8-18 microM. A structure-activity relationship is also discussed. 相似文献
24.
Karen Bersine Valance E. F. Brenneis Robyn C. Draheim A. Michelle Wargo Rub Jeannette E. Zamon Rodney K. Litton Susan A. Hinton Mark D. Sytsma Jeffery R. Cordell John W. Chapman 《Biological invasions》2008,10(8):1381-1388
Estuaries play an important role as nurseries and migration corridors for Chinook salmon and other fishes. The invasive New
Zealand mudsnail, Potamopyrgus antipodarum (Gray, 1843), has been noted in the Columbia River Estuary and other estuaries in the western USA, yet no studies have addressed
the estuarine impacts of this invader. Our data show P. antipodarum is currently found in five peripheral bays and many tributaries of the Columbia River Estuary, where it can constitute a
major portion of the benthic invertebrate biomass and where it co-occurs with native amphipod species. We review the history
of the P. antipodarum invasion in the Columbia River Estuary and discuss potential impacts on estuarine food webs. We also report the first occurrence
of P. antipodarum in the diet of juvenile Chinook salmon from the Columbia River Estuary. Although present in Chinook diets at very low frequencies,
our observations of P. antipodarum in Chinook gut contents may represent early stages of food web change due to the establishment of dense estuarine snail populations.
Additional research is needed to determine the effects of P. antipodarum on benthic resources, native benthic invertebrates, and benthic predators. We encourage biologists working in western USA
estuaries to be alert to the possibility of encountering P. antipodarum in benthic habitats and predator diets.
相似文献
Jeannette E. ZamonEmail: |
25.
Rubén Limiñana Martín Surroca Stephan Miralles Vicente Urios Juan Jiménez 《Bird Study》2013,60(2):126-131
Capsule Reproductive output in a natural habitat was higher than in birds breeding in cereal crops, highlighting the importance of natural habitats for the species. Aims To evaluate breeding in a natural habitat in inland Castellon province, Spain, and compare breeding parameters with other European populations. Methods Breeding population size in inland Castellon was recorded between 1981 and 2003. A logistic growth model was used to describe population increase. We also calculated clutch size, brood size, productivity, percentage of successful nests and fledging success for the period 1989–2003. Results Population size increased from three pairs in 1981 to 98 pairs in 2003. During 1989–2003, productivity (2.74 ± 1.49 fledglings/pair) and percentage of successful nests (84.%) were higher than observed in other European populations. Conclusions Our results show the importance of our study area for the conservation of this species in the Iberian Peninsula, as it might act as a source of colonists for other areas. Food and protection against predators might explain the high breeding output, which may in turn explain the rapid population growth in the area. The study also suggests that natural habitats might be important for the species elsewhere. 相似文献
26.
Laura Gangoso Pascual López-López Juan Manuel Grande Ugo Mellone Rubén Limi?ana Vicente Urios Miguel Ferrer 《PloS one》2013,8(4)
Background
The adaptive transition between behavioral strategies, such as the shift from migratoriness to sedentariness, remains an outstanding question in evolutionary ecology. Density-dependent variation in the age of first breeding has been proposed as a feasible mechanism through which long-lived migratory birds with deferred sexual maturity should become sedentary to persist on islands. Although this pattern seems to hold for most raptors and herons, a few exceptions have been identified. One of these exceptions is the Eleonora’s falcon, a long-distance migratory bird, which shows one of the most peculiar adaptations in the timing of reproduction and food requirements among raptors.Methodology/Principal Findings
Here, we compiled data concerning demography, banding recoveries and satellite tracking of Eleonora’s falcons to discuss likely explanations for the exceptional behavior of this insular long-distance migratory species.Conclusions/Significance
New data reveal that Eleonora’s falcons do return to the natal colonies in their first year and young birds are able to breed. However, in contrast to previous hypothesis, the highly specialized strategy of this and other ecologically similar species, as well as the virtual lack of food during winter at breeding areas prevent them from becoming sedentary on islands. Although the ultimate mechanisms underlying the process of sedentarization remain poorly understood, the evidence provided reveal the existence of important trade-offs associated with ecological specialization that may become particularly relevant in the present context of global change. 相似文献27.
28.
29.
Almada R Cabrera N Casaretto JA Peña-Cortés H Ruiz-Lara S González Villanueva E 《Plant cell reports》2011,30(10):1959-1968
Grapevine sexual reproduction involves a seasonal separation between inflorescence primordia (flowering induction) and flower
development. We hypothesized that a repression mechanism implicating epigenetic changes could play a role in the seasonal
separation of these two developmental processes in grapevine. Therefore, the expression of five grapevine genes with homology
to the Arabidopsis epigenetic repressor genes FERTILIZATION INDEPENDENT ENDOSPERM (FIE), EMBRYONIC FLOWER 2 (EMF2), CURLY LEAF (CLF), MULTICOPY SUPPRESSOR OF IRA 1 (MSI1) and SWINGER (SWN) was analyzed during the development of buds and vegetative and reproductive organs. During bud development, the putative
grapevine epigenetic repressor genes VvCLF, VvEMF2, VvMSI1, VvSWN and VvFIE are mainly expressed in latent buds at the flowering induction period, but also detected during bud burst and inflorescence/flower
development. The overlapping expression patterns of grapevine PcG-like genes in buds suggest that chromatin remodeling mechanisms could be operating during grapevine bud development for controlling
processes such as seasonal flowering, dormancy and bud burst. Furthermore, the expression of grapevine PcG-like genes was also detected in fruits and vegetative organs, suggesting that epigenetic changes could be at the basis of
the regulation of various proliferation–differentiation cell transitions that occur during grapevine development. 相似文献
30.