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101.
Desorption electrospray ionization mass spectrometry (DESI-MS) imaging of biological samples allows untargeted analysis and structural characterization of lipids ionized from the near-surface region of a sample under ambient conditions. DESI is a powerful and sensitive MS ionization method for 2D and 3D imaging of lipids from direct and unmodified complex biological samples. This review describes the strengths and limitations of DESI-MS for lipid characterization and imaging together with the technical workflow and a survey of applications. Included are discussions of lipid mapping and biomarker discovery as well as a perspective on the future of DESI imaging. 相似文献
102.
Chapman DD Simpfendorfer CA Wiley TR Poulakis GR Curtis C Tringali M Carlson JK Feldheim KA 《The Journal of heredity》2011,102(6):643-652
Sawfish (family Pristidae) are among the most critically endangered marine fish in the world, yet very little is known about how genetic bottlenecks, genetic drift, and inbreeding depression may be affecting these elasmobranchs. In the US Atlantic, the smalltooth sawfish (Pristis pectinata) has declined to 1-5% of its abundance in the 1900s, and its core distribution has contracted to southwest Florida. We used 8 polymorphic microsatellite markers to show that this remnant population still exhibits high genetic diversity in terms of average allelic richness (18.23), average alleles per locus (18.75, standard deviation [SD] 6.6) and observed heterozygosity (0.43-0.98). Inbreeding is rare (mean individual internal relatedness = -0.02, SD 0.14; F(IS) = -0.011, 95% confidence interval [CI] = -0.039 to 0.011), even though the estimated effective population size (N(e)) is modest (250-350, 95% CI = 142-955). Simulations suggest that the remnant smalltooth sawfish population will probably retain >90% of its current genetic diversity over the next century even at the lower estimate of N(e). There is no evidence of a genetic bottleneck accompanying last century's demographic bottleneck, and we discuss hypotheses that could explain this. We also discuss features of elasmobranch life history and population biology that could make them less vulnerable than other large marine vertebrates to genetic change associated with reduced population size. 相似文献
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Coccé MC Villa O Obregon MG Salido M Barreiro C Solé F Gallego MS 《Cytogenetic and genome research》2007,118(1):84-86
We report on a novel case of pure partial tandem duplication 1q42q43 confirmed by fluorescence in situ hybridization (FISH). We compare the manifestations of our patient with similar cases previously reported. We conclude that the most common clinical manifestations of trisomy 1q42qter are prenatal and postnatal growth retardation, relative macrocephaly, triangular face, prominent forehead, broad nasal bridge, abnormal philtrum, micro/retrognathia, cardiac defects and mental retardation. We would like to emphasize the importance of the FISH technique in the identification of the duplicated segment. 相似文献
106.
During the development of neural networks, what sets synaptogenic interactions apart from nonsynaptogenic interactions is not well understood at the subcellular level. Using a combination of intracellular dye injection and electron microscopy, we show that a specific motoneuron (RP3) and its synaptic partners (muscles 6 and 7), both often bearing microprocesses, develop intimate membrane contact sites characterized by junctional structures, prior to their initiating synaptogenesis in Drosophila embryos. Other motoneuron growth cones that extend alongside the RP3 growth cone to innervate surrounding muscles do not form such contacts with muscles 6 and 7. We also examined how specific target recognition molecules affect the development of these ultrastructural associations between synaptic partner cells. When Fasciclin III (Fas3), a “positive” target recognition molecule for RP3, is ectopically expressed in neighboring muscles, the RP3 growth cone ectopically develops membrane contact sites with Fas3‐misexpressing muscles with which it would not normally associate. In contrast, when Toll, a “negative” target recognition molecule normally expressed by a subset of muscles that surrounds muscles 6 and 7, is misexpressed on muscles 6 and 7, the RP3 growth cone fails to exhibit its normal close contact with these muscles. We propose that the formation of close membrane associations and junctional structures can be regulated under the influence of synaptic target recognition molecules and signifies the beginning of subcellular events during synaptic target recognition. © 2000 John Wiley & Sons, Inc. J Neurobiol 43: 448–459, 2000 相似文献
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Combined quantum mechanical/molecular mechanical (QM/MM) simulations are carried out to analyze factors that dictate the proton transfer in carbonic anhydrase II (CAII), an enzyme that has been used as a prototypical example of long-range proton transfers in biomolecules. In contrast to the long-held conjecture in the experimental literature, the computed potentials of mean force (PMF) suggest that the proton transfer in CAII is not very sensitive to the orientation of the acceptor group (His 64) and, therefore, the number of water molecules that bridge the donor (zinc-water) and acceptor groups. Perturbative analysis indicates that a series of polar and charged residues close to the transfer pathways make the dominant contribution to the barrier and exothermicity of the proton transfer reaction, thus supporting the proposal from previous studies of Warshel and co-workers using a somewhat simpler QM/MM model that electrostatic interactions play a major role in the proton transfer in CAII. The PMF results are in striking contrast to previous analysis using the same QM/MM method but an ensemble of minimum energy path (MEP) calculations, which found a steep dependence of the barrier height on the number of bridging water molecules. Analysis of the configurations sampled in the PMF and MEP simulations suggests that this difference arises because the PMF simulations sample a largely stepwise mechanism while the local MEP calculations artificially favored concerted transfers due to the specific protocol used to generate the initial configurations. Therefore, this study presents a compelling argument for carrying out proper conformational sampling in the study of long-range proton transfers. Finally, we illustrate that Phi analysis, which has been widely used in protein folding studies, can potentially generate new mechanistic information for long-range proton transfers regarding the sequence of events. The results of the perturbation analysis and the Phi analysis provide opportunities for experimentally testing the mechanistic proposals from this study and our recent work in which a stepwise "proton hole" transfer pathway has been proposed. 相似文献
109.
Demian D. Chapman Debra L. Abercrombie Christophe J. Douady Ellen K. Pikitch Michael J. Stanhopen Mahmood S. Shivji 《Conservation Genetics》2003,4(4):415-425
The great white shark, Carcharodoncarcharias, is the most widely protectedelasmobranch in the world, and is classified asVulnerable by the IUCN and listed on AppendixIII of CITES. Monitoring of trade in whiteshark products and enforcement of harvest andtrade prohibitions is problematic, however, inlarge part due to difficulties in identifyingmarketed shark parts (e.g., dried fins, meatand processed carcasses) to species level. Toaddress these conservation and managementproblems, we have developed a rapid, moleculardiagnostic assay based on species-specific PCRprimer design for accurate identification ofwhite shark body parts, including dried fins. The assay is novel in several respects: Itemploys a multiplex PCR assay utilizing bothnuclear (ribosomal internal transcribed spacer2) and mitochondrial (cytochrome b) locisimultaneously to achieve a highly robustmeasure of diagnostic accuracy; it is verysensitive, detecting the presence of whiteshark DNA in a mixture of genomic DNAs from upto ten different commercially fished sharkspecies pooled together in a single PCR tube;and it successfully identifies white shark DNAfrom globally distributed animals. Inaddition to its utility for white shark trademonitoring and conservation applications, thishighly streamlined, bi-organelle, multiplex PCRassay may prove useful as a general model forthe design of genetic assays aimed at detectingbody parts from other protected and threatenedspecies. 相似文献
110.
Demian Koop Paula Cisternas Valerie B. Morris Dario Strbenac Jean Yee Hwa Yang Gregory A. Wray Maria Byrne 《BMC developmental biology》2017,17(1):4