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81.
Teresa Orlikowska Marta Zawadzka Danuta Kucharska Lesław B. Lahuta 《Acta Physiologiae Plantarum》2010,32(2):333-340
We examined the effects of cooling applied for 4 to 20 weeks on donor cultures of four dwarfing apple rootstocks (P16, P22,
P59 and M26). Our aim includes increasing their competence for in vitro adventitious shoot regeneration from the leaves. Donor
cultures were maintained on a shoot multiplication medium at 4°C in the dark for 4 months, followed by subculture on a fresh
medium for 4 weeks. The cooling of the cultures caused an increase in the adventitious shoot number and a decrease in the
starch content and an increase in the soluble sugar content (monosaccharides, raffinose and stachyose). The accumulation of
stachyose in response to cold is a new observation, and it suggests that raffinose and stachyose play important role in the
acclimation of dwarf apple rootstocks to low temperatures. 相似文献
82.
83.
Ecological opportunity and ecomorphological convergence in Australasian robins (Petroicidae)
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Ecological theories of adaptive radiation predict that ecological opportunity (EO) stimulates cladogenesis through entry into a novel environment and/or release of competition pressures. Due to its dynamic paleoclimatic and geological history, the Australo‐Papuan region constitutes an opportune scenario to study patterns of diversification in relation to the colonization of new ecological niches. Here, we employ a comparative framework using the Australasian robins (Petroicidae) as a model system to test whether the diversification of this bird family fulfils a niche‐filling process as predicted by the EO model, and to test whether the observed morphological similarity is described by a pattern of phylogenetic niche conservatism (PNC) or convergence. Although we detected an early‐burst, we did not find a slowdown in speciation or morphological evolution as expected in a niche‐filling scenario. Divergence in tarsus length and tail length (PC1) was consistent with a multi‐peak model, in which PC1 represents a convergent trait among distantly related clades sharing the same foraging strategy. Our study thus shows that convergence rather than PNC seems to explain the existence of morphological similarity across independent lineages in the Petroicidae. We also found a low level of PNC regarding annual variations in temperature and precipitation, which is in agreement with the hypothesis that diversification within the Petroicidae involved repeated radiations. We suggest two non‐mutually exclusive hypotheses to explain the overall lack of density‐dependent cladogenesis. First, the extreme spatial and temporal heterogeneity of this region may have generated a pattern of repeated ecological opportunity over time and, second, this family may not yet have reached equilibrium diversity. 相似文献
84.
Lakshmaiah Gingipalli Michael H. Block Larry Bao Emma Cooke Les A. Dakin Christopher R. Denz Andrew D. Ferguson Jeffrey W. Johannes Nicholas A. Larsen Paul D. Lyne Timothy W. Pontz Tao Wang Xiaoyun Wu Allan Wu Hai-Jun Zhang Xiaolan Zheng James E. Dowling Michelle L. Lamb 《Bioorganic & medicinal chemistry letters》2018,28(8):1336-1341
The design and synthesis of a novel series of 2,6-disubstituted pyrazine derivatives as CK2 kinase inhibitors is described. Structure-guided optimization of a 5-substituted-3-thiophene carboxylic acid screening hit (3a) led to the development of a lead compound (12b), which shows inhibition in both enzymatic and cellular assays. Subsequent design and hybridization efforts also led to the unexpected identification of analogs with potent PIM kinase activity (14f). 相似文献
85.
Janette A. Norman Les Christidis Richard Schodde 《Organisms Diversity & Evolution》2018,18(2):241-259
Understanding how the complex geotectonic and climatic history of the Australo-Papuan region has promoted the ecological and evolutionary diversification of its avifauna remains a challenge. Outstanding questions relate to the nature and timing of biogeographical connections between Australia and the emerging island of New Guinea and the mechanisms by which distinctive altitudinal replacement sequences have evolved amongst congeneric species in montane New Guinea. Here, we combine analyses of phylogenetic and eco-morphological data to investigate ecological and evolutionary patterns of diversification in the largely mesic-adapted Australo-Papuan scrubwrens (Sericornis) and mouse-warblers (Crateroscelis). We find evidence of ecological convergence and present a revised taxonomic and systematic treatment of the subfamily integrating information from new (ND2) and existing molecular phylogenetic reconstructions. Biogeographical connections indicate at least three phases of faunal interchange between Australia and New Guinea commencing in the mid to late Miocene. We also find little support for the proposed time dependency of ecological sorting mechanisms linked to divergence in foraging niche amongst altitudinal replacements. Instead, physiological adaptations to hypoxia and increased thermal efficiency at higher altitudes may better account for observed patterns of diversification in montane New Guinea. Indirect support for this hypothesis is derived from molecular clock calibrations that indicate a pulse of diversification across the Miocene-Pliocene boundary coincident with a phase of rapid mountain uplift. Simple ecological and climatic models appear inadequate for explaining observed patterns and mechanisms of diversification in the New Guinean montane avifauna. Further insights will require multidisciplinary research integrating geotectonic, palaeoclimatic, genetic, ecological and physiological approaches. 相似文献
86.
The toxicity of dung from cattle treated with an ivermectin sustained-release bolus was estimated in terms of ivermectin or ivermectin equivalents, using a laboratory bioassay with the dung fly Neomyia cornicina Fabricius (Diptera, Muscidae). The mortalities of flies measured 7 days after feeding for 24 h on dung containing known concentrations of ivermectin (between 0.125 and 1 g ivermectin per gram fresh dung) were compared with the mortalities of insects fed for 24 h on dung from cattle treated 21 days previously with an ivermectin sustained-release bolus. The toxicity of the bolus dung was equivalent to dung containing 0.66 g ivermectin per gram fresh dung. To determine whether insects could differentiate between control dung and dung from bolus-treated cattle, choice-chamber tests were carried out. There was no significant difference in the percentage of females that chose either dung type, suggesting that they were unable to distinguish the dung of bolus-treated cattle from control dung. Results are discussed in relation to the impact that bolus use can have on the insect fauna of cattle dung. 相似文献
87.
88.
T. Gregory Ross Craig F. Barrett Marybel Soto Gomez Vivienne K.Y. Lam Claudia L. Henriquez Donald H. Les Jerrold I. Davis Argelia Cuenca Gitte Petersen Ole Seberg Marcela Thadeo Thomas J. Givnish John Conran Dennis W. Stevenson Sean W. Graham 《Cladistics : the international journal of the Willi Hennig Society》2016,32(2):160-178
Past phylogenetic studies of the monocot order Alismatales left several higher‐order relationships unresolved. We addressed these uncertainties using a nearly complete genus‐level sampling of whole plastid genomes (gene sets representing 83 protein‐coding and ribosomal genes) from members of the core alismatid families, Tofieldiaceae and additional taxa (Araceae and other angiosperms). Parsimony and likelihood analyses inferred generally highly congruent phylogenetic relationships within the order, and several alternative likelihood partitioning schemes had little impact on patterns of clade support. All families with multiple genera were resolved as monophyletic, and we inferred strong bootstrap support for most inter‐ and intrafamilial relationships. The precise placement of Tofieldiaceae in the order was not well supported. Although most analyses inferred Tofieldiaceae to be the sister‐group of the rest of the order, one likelihood analysis indicated a contrasting Araceae‐sister arrangement. Acorus (Acorales) was not supported as a member of the order. We also investigated the molecular evolution of plastid NADH dehydrogenase, a large enzymatic complex that may play a role in photooxidative stress responses. Ancestral‐state reconstructions support four convergent losses of a functional NADH dehydrogenase complex in Alismatales, including a single loss in Tofieldiaceae. 相似文献
89.
Richard Whitkus Finley A. Bryan Donald H. Les Lucy E. Tyrrell 《Plant Species Biology》1987,2(1-2):67-73
Abstract Species of Trillium in the subgenus Phyllantherum are either polymorphic for flower color, or monomorphic for flower color and related to a polymorphic species. This leads to the suggestion that polymorphic species may be the progenitors for monomorphic ones. For this to be true, it must be demonstrated that genetic divergence among flower morphs can occur within polymorphic populations. Genetic structure was assessed in a population of T. sessile that contains a polymorphism for flower color. A survey of 11 enzyme systems using starch gel electrophoresis revealed three polymorphic loci: 6PGD-1, AAT-1 and AAT-2. Analysis of large and small scale spatial structure, stage classes, and flower color classes revealed significant genetic divergence in all instances. Spatial structure in the population is likely a result of genetic neighborhoods which can maintain populational variation via random genetic drift. Genetic divergence of the yellow flower color morph was probably initiated through genetic drift since the morph occurs in low frequencies. The results imply that the initial genetic divergence of species in the subgenus can arise within polymorphic populations. 相似文献
90.
A series of nucleoside transport inhibitors has been tested for their ability to displace [3H]diazepam binding to CNS membranes. No correlation between their potency as [3H]adenosine uptake blockers and as inhibitors of [3H]diazepam binding was found, either in rat or guinea-pig brain tissue. Dipyridamole, a potent adenosine transport inhibitor interacted strongly (Ki = 54 nM) with peripheral-type benzodiazepine binding sites (“acceptor sites”) and was 4–5 fold weaker in displacing [3H]methylclonazepam and [3H]Ro15-1788, ligands selective for the specific central benzodiazepine “receptor”. Unlike the benzodiazepines, dipyridamole had no anticonvulsant action against metrazole-induced convulsions in mice. Ro5-4864, a benzodiazepine which selectively interacts with the peripheral-type benzodiazepine binding site, was approximately equipotent with diazepam in inhibiting [3H]adenosine uptake in brain tissue. These results do not support the idea of a very close link between high-affinity central binding sites for clinically-active benzodiazepines and the adenosine uptake site. The possibility of a connection between benzodiazepine “acceptor” sites and the membrane nucleoside transporter is discussed. 相似文献