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81.
Lunaria annua is overviewed and its two subspecies, subsp. annua and subsp. pachyrrhiza, discussed, the latter described. Two cultivars of subsp. pachyrrhiza, ‘Corfu Blue’ and ‘Mistras’ are illustrated and described. Details of cultivation are also included. 相似文献
82.
Deletion analysis of the essentiality of penicillin-binding proteins 1A, 2B and 2X of Streptococcus pneumoniae 总被引:5,自引:0,他引:5
Christopher M. Kell Umender K. Sharma Christopher G. Dowson Christine Town Tanjore S. Balganesh Brian G. Spratt 《FEMS microbiology letters》1993,106(2):171-175
Abstract An internal fragment from each of the penicillinebinding protein (PBP) 1A, 2B and 2X genes of Streptococcus pneumoniae , which included the region encoding the active-site serine residue, was replaced by a fragment encoding spectinomycin resistance. The resulting constructs were tested for their ability to transform S. pneumoniae strain R6 to spectinomycin resistance. Spectinomycin-resistant transformants could not be obtained using either the inactivated PBP 2X or 2B genes, suggesting that deletion of either of these genes was a lethal event, but they were readily obtained using the inactivated PBP 1A gene. Analysis using the polymerase chain reaction confirmed that the latter transformants had replaced their chromosomal copy of the PBP 1A gene with the inactivated copy of the gene. Deletion of the PBP 1A gene was therefore tolerated under laboratory conditions and appeared to have little effect on growth or susceptibility to benzylpenicillin. 相似文献
83.
Christopher A. Demitrius Anthony P. Duran Virginia C. Chamberlain Victoria M. Hitchins 《Journal of industrial microbiology & biotechnology》1993,12(6):399-402
Summary Biological indicators (BIs) are used to monitor ethylene oxide (EO) gas sterilization processes for medical devices. Several European and United States BIs for EO sterilization were evaluated for resistance according to both United States Pharmacopeia (USP) XXI and United Kingdom's (UK) tests for D-values. US BIs areB. subtilis var. niger spores on paper strips or disc carriers while European BIs use aluminum strips, quartz sand, or cotton yarn. Numerous BIs per run and runs per lot, as well as 2–3 different lots of BIs from each manufacturer, were examined. Both British and US BIs met their respective label claims for rates of inactivation when tested against British and USP EO test parameters, respectively. However, Danish BIs, on cotton yarn or quartz sand, were not inactivated following USP specifications during the exposure dwell times tested (600 mg L–1 EO, 54°C, 60% RH, 0–110 min). The Danish BIs will require further testing in order for us to determine if theirB. subtilis spores are unusually resistant to EO or if the spore carrier substrates protect the spores from the sterilizing gas. In conclusion, the British and American BIs for EO sterilization are equivalent in resistance despite differences in carrier substrate, recovery conditions, calculation methods for D-values, and the labeled sterilization conditions for use. 相似文献
84.
85.
Iain M. McIntyre Christopher V. King Stan Skafidis Olaf H. Drummer 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1993,621(2)
A sensitive method suitable for the determination of tricyclic and other antidepressants in postmortem and clinical specimens is presented. The procedure, which utilizes reversed-phase HPLC combined with dual ultraviolet wavelength detection, enables the separation of 17 commonly prescribed antidepressants and some selected metabolites in a single extraction. Peak purity was confirmed using absorbance ratios at 220 nm and 254 nm wavelengths and revealed little interference from other eluting analytes. The blood detection limit for most antidepressants was 50 ng/ml. The most commonly observed antidepressants in 281 forensic cases analysed over a two-year period with the described method were dothiepin, amitriptyline, nortriptyline and doxepin. 相似文献
86.
ExbB acts as a chaperone-like protein to stabilize TonB in the cytoplasm 总被引:19,自引:5,他引:14
The TonB protein is required to transduce energy from the cytoplasmic membrane to outer membrane transport proteins of Gram-negative bacteria. Two accessory proteins, ExbB and ExbD, are required for TonB function and it has been suggested that TonB and ExbBD form a complex in the membrane. In this paper we demonstrate that there are two spatially distinct, functional interactions between ExbBD and TonB. First, there is an interaction between ExbBD and the N-terminal signal-like peptide of TonB, probabiy the formation of a stable complex in the membrane. Second, ExbB interacts with TonB in the cytoplasm. This interaction involves the domain of TonB that is normally periplasmic. Thus, this is a transient interaction which occurs during the synthesis and/or localization of TonB, implying a chaperone-like role for ExbB. The transmembrane topology of ExbB was shown to be consistent with this role. 相似文献
87.
Jérémy Gauthier Joana Meier Fabrice Legeai Melanie McClure Annabel Whibley Anthony Bretaudeau Hélène Boulain Hugues Parrinello Sam T. Mugford Richard Durbin Chenxi Zhou Shane McCarthy Christopher W. Wheat Florence Piron-Prunier Christelle Monsempes Marie-Christine François Paul Jay Camille Noûs Emma Persyn Emmanuelle Jacquin-Joly Camille Meslin Nicolas Montagné Claire Lemaitre Marianne Elias 《Molecular ecology resources》2023,23(4):872-885
The ithomiine butterflies (Nymphalidae: Danainae) represent the largest known radiation of Müllerian mimetic butterflies. They dominate by number the mimetic butterfly communities, which include species such as the iconic neotropical Heliconius genus. Recent studies on the ecology and genetics of speciation in Ithomiini have suggested that sexual pheromones, colour pattern and perhaps hostplant could drive reproductive isolation. However, no reference genome was available for Ithomiini, which has hindered further exploration on the genetic architecture of these candidate traits, and more generally on the genomic patterns of divergence. Here, we generated high-quality, chromosome-scale genome assemblies for two Melinaea species, M. marsaeus and M. menophilus, and a draft genome of the species Ithomia salapia. We obtained genomes with a size ranging from 396 to 503 Mb across the three species and scaffold N50 of 40.5 and 23.2 Mb for the two chromosome-scale assemblies. Using collinearity analyses we identified massive rearrangements between the two closely related Melinaea species. An annotation of transposable elements and gene content was performed, as well as a specialist annotation to target chemosensory genes, which is crucial for host plant detection and mate recognition in mimetic species. A comparative genomic approach revealed independent gene expansions in ithomiines and particularly in gustatory receptor genes. These first three genomes of ithomiine mimetic butterflies constitute a valuable addition and a welcome comparison to existing biological models such as Heliconius, and will enable further understanding of the mechanisms of adaptation in butterflies. 相似文献
88.
Christopher S. Evans 《Ethology : formerly Zeitschrift fur Tierpsychologie》1991,89(2):125-134
Distress calls of mallard ducklings consist of a highly stereotyped series of notes. When two ducklings are simultaneously separated from the brood, they characteristically call in alternation. Each bird inhibits its calls while the other is vocalizing, thus preventing masking and facilitating localization by the hen. I examined whether exposure of ducklings to calls presented in a naturalistic alternating pattern affected subsequent responsiveness to them. Individual ducklings were exposed to either 40 s or 80 s of computer-controlled distress call playbacks, using an algorithm that mimicked the behavior of another duckling. Calls were presented only when the subject was silent and ended as soon as it began to vocalize. Each of these ducklings was paired with a ‘yoked’ control. Birds in these control groups experienced exactly the same pattern of playbacks as the ‘interactive’ birds, but the stimuli had no consistent relationship to their own vocal behavior. When the same calls were played back 24 h later, in a fixed pattern that was independent of the ducklings' behavior, birds that had received 80 s of prior interactive exposure were significantly more responsive than both their yoked controls and birds receiving only 40 s of such playbacks. This result suggests that interactive vocal experience, characteristic of natural communication, affects the subsequent perceptual sensitivity of ducklings. 相似文献
89.
Christopher B. Boyko 《Palaeontology》2004,47(4):929-932
The fossil genus Paralbunea Hu and Tao, described as an anomuran albuneid, is a junior homonym of Paralbunea Serène and a possible synonym of either the brachyuran raninid Ranilia H. Milne Edwards, 1837, or Cosmonotus Adams and White, 1848. The type series of P. taipeiensis Hu and Tao is composed of at least two species belonging to two raninid genera and appears (in part) assignable to the genus Ranilia and (in part) to Cosmonotus grayi Adams and White, 1848. However, due to both limited availability and poor quality of the holotype of Paralbunea taipeiensis , and destruction of the paratypes, this taxon cannot be unequivocally synonymized with any particular raninid taxon and a new name is proposed to replace Hu and Tao's preoccupied generic name. Caution is urged when describing purported albuneid fossils, due to strong convergence with raninid crabs, which are far more common in the fossil record. 相似文献
90.
Pedro Lamosa David L Turner Rita Ventura Christopher Maycock Helena Santos 《European journal of biochemistry》2003,270(23):4606-4614
Heteronuclear NMR relaxation measurements and hydrogen exchange data have been used to characterize protein dynamics in the presence or absence of stabilizing solutes from hyperthermophiles. Rubredoxin from Desulfovibrio gigas was selected as a model protein and the effect of diglycerol phosphate on its dynamic behaviour was studied. The presence of 100 mM diglycerol phosphate induces a fourfold increase in the half-life for thermal denaturation of D. gigas rubredoxin. A model-free analysis of the protein backbone relaxation parameters shows an average increase of generalized order parameters of 0.015 reflecting a small overall reduction in mobility of fast-scale motions. Hydrogen exchange data acquired over a temperature span of 20 degrees C yielded thermodynamic parameters for the structural opening reactions that allow for the exchange. This shows that the closed form of the protein is stabilized by an additional 1.6 kJ x mol(-1) in the presence of the solute. The results seem to indicate that the stabilizing effect is due mainly to a reduction in mobility of the slower, larger-scale motions within the protein structure with an associated increase in the enthalpy of interactions. 相似文献