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231.
232.
B Müller D Besser P Kleinw?chter O Arad S Reissmann 《The journal of peptide research》1999,54(5):383-393
To improve the assembly of backbone cyclic peptides, N-functionalized dipeptide building units were synthesized. The corresponding N-aminoalkyl or N-carboxyalkyl amino acids were formed by alkylation or reductive alkylation of amino acid benzyl or tert-butyl esters. In the case of N-aminoalkyl amino acid derivatives the aldehydes for reductive alkylation were obtained from N,O-dimethyl hydroxamates of N-protected amino acids by reduction with LiAlH4. N-carboxymethyl amino acids were synthesized by alkylation using bromoacetic acid ester and the N-carboxyethyl amino acids via reductive alkylation using aldehydes derived from formyl Meldrums acid. Removal of the carboxy protecting group leads to free N-alkyl amino acids of very low solubility in organic solvents, allowing efficient purification by extraction of the crude product. These N-alkyl amino acids were converted to their tetramethylsilane-esters by silylation with N,O-bis-(trimethylsilyl)acetamide and could thus be used for the coupling with Fmoc-protected amino acid chlorides or fluorides. To avoid racemization the tert-butyl esters of N-alkyl amino acids were coupled with the Fmoc-amino acid halides in the presence of the weak base collidine. Both the N-aminoalkyl and N-carboxyalkyl functionalized dipeptide building units could be obtained in good yield and purity. For peptide assembly on the solid support, the allyl type protection of the branching moiety turned out to be most suitable. The Fmoc-protected N-functionalized dipeptide units can be used like any amino acid derivative under the standard conditions for Fmoc-solid phase synthesis. 相似文献
233.
Emily Olfson Catherine E. Cottrell Nicholas O. Davidson Christina A. Gurnett Jonathan W. Heusel Nathan O. Stitziel Li-Shiun Chen Sarah Hartz Rakesh Nagarajan Nancy L. Saccone Laura J. Bierut 《PloS one》2015,10(9)
The American College of Medical Genetics and Genomics (ACMG) recommends that clinical sequencing laboratories return secondary findings in 56 genes associated with medically actionable conditions. Our goal was to apply a systematic, stringent approach consistent with clinical standards to estimate the prevalence of pathogenic variants associated with such conditions using a diverse sequencing reference sample. Candidate variants in the 56 ACMG genes were selected from Phase 1 of the 1000 Genomes dataset, which contains sequencing information on 1,092 unrelated individuals from across the world. These variants were filtered using the Human Gene Mutation Database (HGMD) Professional version and defined parameters, appraised through literature review, and examined by a clinical laboratory specialist and expert physician. Over 70,000 genetic variants were extracted from the 56 genes, and filtering identified 237 variants annotated as disease causing by HGMD Professional. Literature review and expert evaluation determined that 7 of these variants were pathogenic or likely pathogenic. Furthermore, 5 additional truncating variants not listed as disease causing in HGMD Professional were identified as likely pathogenic. These 12 secondary findings are associated with diseases that could inform medical follow-up, including cancer predisposition syndromes, cardiac conditions, and familial hypercholesterolemia. The majority of the identified medically actionable findings were in individuals from the European (5/379) and Americas (4/181) ancestry groups, with fewer findings in Asian (2/286) and African (1/246) ancestry groups. Our results suggest that medically relevant secondary findings can be identified in approximately 1% (12/1092) of individuals in a diverse reference sample. As clinical sequencing laboratories continue to implement the ACMG recommendations, our results highlight that at least a small number of potentially important secondary findings can be selected for return. Our results also confirm that understudied populations will not reap proportionate benefits of genomic medicine, highlighting the need for continued research efforts on genetic diseases in these populations. 相似文献
234.
An Ecological Imbalance Induced by a Non-Native Species: The Manila Clam in the Venice Lagoon 总被引:1,自引:0,他引:1
F. Pranovi G. Franceschini M. Casale M. Zucchetta P. Torricelli O. Giovanardi 《Biological invasions》2006,8(4):595-609
Among the 19 non-native species of marine invertebrates which have invaded the Venice Lagoon and have established populations, Ruditapes philippinarum, deliberately introduced in 1983, is surely the most successful species. According to the hypothesis that alien species invasion could be favoured by an altered ecological, chemical or physical state of the system induced by anthropogenic disturbance, R. philippinarum turned out to be ‘the right species at the right moment’. By comparing historical data (1968, 1985, 1990) with 1999 data, changes in macrobenthic community, in particular bivalve molluscs, of the lagoon induced by R. philippinarum introduction and subsequent clam exploiting activity were assessed. It has been possible to describe a sharp reduction, both in terms of distribution area and density, of all other filter feeder bivalves. Moreover, by using the clearance rate of the most abundant bivalve species in 1990 and 1999 (Cerastoderma glaucum and R. philippinarum, respectively), it was possible to estimate that the filtration capacity, expressed as l h−1 m−2, has more than doubled. This has altered the functioning of the ecosystem, resulting in a stronger benthic–pelagic coupling. In this context, R. philippinarum attains control of the system. Considering all this, it is possible to state that the Venice Lagoon ecosystem has entered into a new state, probably more resistant but less resilient, with implications for future management choices. 相似文献
235.
T A Zapara O G Simonova A A Zharkikh A S Ratushniak 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》1999,85(1):128-138
Infringement of the Lymnaea stagnalis cytoskeleton condition affected preservation and repeated development of plastic responses. Stabilising of the microtubules led to a dependence of the development and preservation dynamics of the plastic responses. Stabilising of the microfilaments transformed short-term plastic responses into long-term ones. The findings suggest a key role of reorganisation of the cytoskeleton in neuronal plasticity. 相似文献
236.
237.
Adriana Calderaro Giovanna Piccolo Chiara Gorrini Sara Montecchini Sabina Rossi Maria Cristina Medici Carlo Chezzi Georges Snounou 《PloS one》2012,7(10)
It has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasites: P. ovale curtisi and P. ovale wallikeri. We have extended and optimized a Real-time PCR assay targeting the parasite’s small subunit ribosomal RNA (ssrRNA) gene to detect both these species. When the assay was applied to 31 archival blood samples from patients diagnosed with P. ovale, it was found that the infection in 20 was due to P. ovale curtisi and in the remaining 11 to P. ovale wallikeri. Thus, this assay provides a useful tool that can be applied to epidemiological investigations of the two newly recognized distinct P. ovale species, that might reveal if these species also differ in their clinical manifestation, drugs susceptibility and relapse periodicity. The results presented confirm that P. ovale wallikeri is not confined to Southeast Asia, since the majority of the patients analyzed in this study had acquired their P. ovale infection in African countries, mostly situated in West Africa. 相似文献
238.
K. O. YANAGISAWA HIDEKO URUSHIHARA H. FUJIMOTO T. SHIROISHI K. MORIWAKI 《Differentiation; research in biological diversity》1980,16(1-3):185-188
Lethal mutations in the T/t complex cause stage-specific morphologic abnormalities during early embryogenesis of mice. Although mutant embryos are lethal at the early stages of development, we have succeeded in establishing several cell lines from one of these mutants ( T/T ). Mutant-specific abnormality was not observed in gross morphology and growth patterns of cells. They, however, retained the characters of freshly dissociated embryonic cells to form smaller aggregates than the wild-type in rotation-mediated aggregation.
One of the T/T cell lines (T-1) formed tumors when injected into one-day-old syngeneic and allogeneic host, Expression of H-2 antigens was serologically studied with H-2 specificity 5 as a marker antigen. All lines except T-1 were shown to have this specificity. 相似文献
One of the T/T cell lines (T-1) formed tumors when injected into one-day-old syngeneic and allogeneic host, Expression of H-2 antigens was serologically studied with H-2 specificity 5 as a marker antigen. All lines except T-1 were shown to have this specificity. 相似文献
239.
Behavioral relationships between two sympatric voles (Microtus): relevance to habitat segregation 总被引:1,自引:0,他引:1
J O Murie 《Journal of mammalogy》1971,52(1):181-186
240.
W. O. van der Knaap Jacqueline F. N. van Leeuwen Tomasz Goslar Robert Krisai Willy Tinner 《Vegetation History and Archaeobotany》2012,21(1):37-60
Three mires and a small lake in the Swiss and Austrian Alps were studied palynologically at high resolution, covering the
last 1,000, 400, 50 and 1,200 years, respectively. Methodological lessons include: (1) Sub-decadal resolution in upper, little-decomposed
peat layers reveals recurrent marked fluctuations in both percentages and influx of regional tree-pollen types, reflecting
variations in pollen production rather than in plant-population sizes. (2) Intermittent, single-spectrum pollen maxima in
samples of sub-decadal resolution indicate pollen transport in clumps. This type of pollen transport may remain unrecognized
in sections with lower sampling resolution, which may then lead to inappropriate interpretation in terms of plant-population
sizes. (3) The detection of short-lived phases of human impact in decomposed peat requires sampling intervals as close as
0.2 cm. (4) PAR (pollen influx) may reflect vegetation dynamics more faithfully than percentages. Reliable PAR, however, is
difficult to achieve in Alpine mires due to past human impact on peat growth, even when complex depth–age modelling techniques
are used. Critical comparison of PAR with percentages is therefore essential. (5) Careful consideration of spatial scales
in pollen signals (local–regional and subdivisions) is essential for a realistic palaeo-ecological interpretation. Results
in terms of past human impact on vegetation are summarized as follows: (1) Trends in pollen types reflecting regional human
action are in general agreement with earlier findings for the western Swiss Alps, allowing for regional differences. (2) All
mires in the Alps investigated here and in an earlier study experienced human impact during the last millennium. The studied
small lake, lying in sub-alpine pasture, records forest dynamics at a lower elevation since a.d. 800. 相似文献