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Jeff A Johnson Heather RL Lerner Pamela C Rasmussen David P Mindell 《BMC evolutionary biology》2006,6(1):65-12
Background
Populations of the Oriental White-backed Vulture (Gyps bengalensis) have declined by over 95% within the past decade. This decline is largely due to incidental consumption of the non-steroidal anti-inflammatory veterinary pharmaceutical diclofenac, commonly used to treat domestic livestock. The conservation status of other Gyps vultures in southern Asia is also of immediate concern, given the lack of knowledge regarding status of their populations and the continuing existence of taxonomic uncertainties. In this study, we assess phylogenetic relationships for all recognized species and the majority of subspecies within the genus Gyps. The continuing veterinary use of diclofenac is an unknown but potential risk to related species with similar feeding habits to Gyps bengalensis. Therefore, an accurate assessment of the phylogenetic relationships among Gyps vultures should aid in their conservation by clarifying taxonomic uncertainties, and enabling inference of their respective relatedness to susceptible G. bengalensis. 相似文献3.
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GREGORY A. SWORD LAURA B. SENIOR JOHN F. GASKIN ANTHONY JOERN 《Systematic Entomology》2007,32(3):420-428
Abstract. Hesperotettix viridis grasshoppers (Orthoptera: Acrididae: Melanoplinae) exhibit intra-individual variation in both mitochondrial 12S-valine-16S and nuclear internal transcribed spacer (ITS) ribosomal DNA sequences. These findings violate core assumptions underlying DNA sequence data obtained via polymerase chain reaction (PCR) amplification for use in molecular systematics investigations. Undetected intra-individual variation of this sort can confound phylogenetic analyses at a range of taxonomic levels. The use of a DNA extraction protocol designed to enrich mitochondrial DNA as well as an initial long PCR of approximately 40% of the grasshopper mitochondrial genome failed to control for the presence of paralogous mitochondrial DNA-like sequences within individuals. These findings constitute the first demonstration of intra-individual heterogeneity in mitochondrial DNA-like sequences in the grasshopper subfamily, Melanoplinae, and only the second report of intra-individual variation in nuclear ITS ribosomal DNA sequences in grasshoppers. The fact that intra-individual variation was detected in two independent DNA marker sets in the same organism strengthens the notion that the orthology of PCR-derived DNA sequences should be examined thoroughly prior to their use in molecular phylogenetic analyses or as DNA barcodes. 相似文献
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When sixth abdominal or metathoracic ganglia of the cockroach Periplaneta americana L. were irrigated continuously with diazoxon (O, O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphate) solution in situ, the log. of the time required to block conduction in certain nerve pathways in the ganglia was directly proportional to the log. of the concentration of diazoxon applied. Inhibition of cholinesterase began peripherally before function was affected, and had begun to affect the neuropile by the time that conduction was first blocked. Longer exposure to diazoxon disrupted nerve function even more, especially in the sixth abdominal ganglion, and inhibited more cholinesterase, but much longer exposure was needed to inhibit nearly all the cholinesterase. Irrigation with saline, begun when block first occurred, failed to restore completely either nerve function or cholinesterase activity. The cholinesterase activity of ganglia from cockroaches treated topically with an LD90 of diazoxon and examined at intervals after treatment decreased steadily to a level similar to that of ganglia treated directly with diazoxon until conduction was just blocked, but rarely became less, even in moribund insects. Nerve function in metathoracic ganglia became badly affected and remained so in all cockroaches that failed to recover, but sixth abdominal ganglia, though usually badly affected for a time, always recovered normal function, even in prostrate cockroaches. The condition of a poisoned insect, therefore, corresponded much more closely to the functional condition of the metathoracic ganglion than to that of the sixth abdominal ganglion. Applying the insecticide close to a ganglion advanced the time of onset of symptoms but affected the final outcome very little. It was calculated that the highest concentration of diazoxon in the haemo-lymph in contact with the nervous systems of cockroaches treated topically with LDgo's of diazoxon was about 10-5M. 相似文献
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Revision of Palaearctic mountain midges (Diptera: Deuterophlebiidae), with phylogenetic and biogeographic analyses of world species 总被引:1,自引:0,他引:1
GREGORY W. COURTNEY 《Systematic Entomology》1994,19(1):1-24
Abstract. The mountain midges (Diptera: Deuterophlebiidae) of the Palaearctic Region are revised to include eight species. Four new species are described: D. brachyrhina sp. nov., D.oporina sp. nov. and D. blepharis sp.nov. from the Himalayas (Assam and Sikkim), and D.bicarinata sp. nov. from southern Korea. A lectotype is designated for D.mirabilis Edwards, and a key to adult males of all Palaearctic species is provided.
Larval, pupal and adult characters were used to reconstruct the phylogenetic and biogeographic relationships of world species of Deuterophlebiidae. Based on features of the adult male, the Himalayan species D. brachyrhina and D. oporina are considered the most primitive deuterophlebiids. The Nearctic species D. inyoensis is proposed as the sister group of the remaining species. Relationships among the latter are based primarily on larval and pupal characters; however, lack of information about the immature stages of several Palaearctic species contributes to a poorly resolved phylogeny. Several alternative hypotheses are presented and discussed. All phylogenetic alternatives suggest that the Nearctic fauna originated from at least two invasions of North America. 相似文献
Larval, pupal and adult characters were used to reconstruct the phylogenetic and biogeographic relationships of world species of Deuterophlebiidae. Based on features of the adult male, the Himalayan species D. brachyrhina and D. oporina are considered the most primitive deuterophlebiids. The Nearctic species D. inyoensis is proposed as the sister group of the remaining species. Relationships among the latter are based primarily on larval and pupal characters; however, lack of information about the immature stages of several Palaearctic species contributes to a poorly resolved phylogeny. Several alternative hypotheses are presented and discussed. All phylogenetic alternatives suggest that the Nearctic fauna originated from at least two invasions of North America. 相似文献
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Seed priming (imbibition in water or osmotic solutions followedby redrying) generally accelerates germination rates upon subsequentre-imbibition, but the response to priming treatments can varyboth within and among seed lots. Seed maturity could influenceresponsiveness to priming, perhaps explaining variable primingeffects among developmentally heterogeneous seed lots. In thecurrent study, muskmelon (Cucumis melo L.) seeds at two stagesof development, maturing (40 d after anthesis (DAA)) and fullymature (60 DAA), were primed in 0?3 M KNO3 for 48 h at 30 ?C,dried, and imbibed in polyethylene glycol 8000 solutions of0 to 1?2 MPa at 15, 20, 25, and 30 ?C. Germination sensitivitiesto temperature and water potential () were quantified as indicatorsof the influence of seed maturity and priming on seed vigour.Germination percentages of 40 and 60 DAA control seeds weresimilar in water at 30 ?C, but the mean germination rate (inverseof time to germination) of 40 DAA seeds was 50% less than thatof 60 DAA seeds. Germination percentages and rates of both 40and 60 DAA seeds decreased at temperatures below 25 ?C. Reductionsin also delayed and inhibited germination, with the 40 DAAseeds being more sensitive to low than the 60 DAA seeds. Primingsignificantly improved the performance of 40 DAA seeds at lowtemperatures and reduced , but had less effect on 60 DAA seeds.Priming lowered both the minimum temperature (Tb) and the minimum (b) at which germination occurred. Overall, priming of 40 DAAseeds improved their germination performance under stress conditionsto equal or exceed that of control 60 DAA seeds, while 60 DAAseeds exhibited only modest improvements due to priming. Asthe osmotic environment inside mature fruits approximates thatof a priming solution, muskmelon seeds may be primedin situ during the late stage of development after maximum dryweight accumulation. Key words: Cucumis melo L., seed priming, germination, vigour, development, temperature 相似文献
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Activity of ferredoxin-NADP+ reductase in leaf extracts of eastern hemlock [Tsuga canadensis (L.) Carr.] was relatively low, but could be markedly increased by use of protective agents. The best method employed polyvinylpolypyrrolidone (PVP) in the extraction medium plus removal of phenolic compounds by filtering the extracts through an insoluble PVP (Polyclar AT) column. Further purification of the enzyme was achieved by means of DEAE cellulose chromatography and DEAE Sephadex chromatography. A 94-fold purification of the enzyme with a total recovery of 43% was obtained. The eastern hemlock ferredoxin-NADP+ reductase was characterized by its diaphorase activity, i.e. the transfer of electrons from NADPH to an electron acceptor. 2,6-dichlorophenol indophenol. The pH optimum for the oxidation of NADPH is between 8.5 and 9.0. The enzyme is highly specific for its electron donor. NADPH, but shows low specificity for electron acceptors. The apparent Michaelis constant values of the enzyme for NADPH. NADH, and 2,6-dichlorophenol indophenol are 2.4 × 10?5, 5.4 × 10?3, and 4.7 × 10?5M respectively. The molecular weight of the enzyme, as estimated by gel filtration, is about 45,000. The enzyme is inhibited by both organic and inorganic mercurials and certain cations. Comparison of properties of eastern hemlock ferredoxin-NADP+ reductase and spinach ferredoxin-NADP+ reductase shows that both enzymes are similar. 相似文献