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排序方式: 共有318条查询结果,搜索用时 62 毫秒
1.
Vimal Nair Min Cheol Kim James A. Golen Arnold L. Rheingold Gabriel A. Castro Paul R. Jensen William Fenical 《Marine drugs》2020,18(11)
A new cytotoxic thiodepsipeptide, verrucosamide (1), was isolated along with the known, related cyclic peptide thiocoraline, from the extract of a marine-derived actinomycete, a Verrucosispora sp., our strain CNX-026. The new peptide, which is composed of two rare seven-membered 1,4-thiazepane rings, was elucidated by a combination of spectral methods and the absolute configuration was determined by a single X-ray diffraction study. Verrucosamide (1) showed moderate cytotoxicity and selectivity in the NCI 60 cell line bioassay. The most susceptible cell lines were MDA-MB-468 breast carcinoma with an LD50 of 1.26 µM, and COLO 205 colon adenocarcinoma with an LD50 of 1.4 µM. Also isolated along with verrucosamide were three small 3-hydroxy(alkoxy)-quinaldic acid derivatives that appear to be products of the same biosynthetic pathway. 相似文献
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Ashalatha?S.?Nair Chee?How?Teo Trude?Schwarzacher Pat?Heslop?HarrisonEmail author 《Euphytica》2005,143(3):285-290
Summary The banana cultivars are originated from the intra- and inter-specific hybridization of two wild diploid species, Musa acuminata Colla and Musa balbisiana Colla, contributing the A and B genomes, respectively. They are classified into genomic groups by scoring morphological features.
Molecular markers provide a quick and reliable system of genome characterization and manipulation in breeding lines. In the
present study a PCR based molecular marker specific for B genomes is been reported. The IRAP primer, designed based on the
LTR sequence of banana Ty3-gypsy-like retroelement (Musa acuminata Monkey retrotransposon, AF 143332), was used to identify the B genome in the banana cultivars. Further a primer pair designed
from B specific bands of Musa balbisiana `Pisang Gala' was used to classify AAB and ABB cultivars in the collection. Among the 36 cultivars tested with this primer,
the B specific band was absent in the AA and AAA cultivars (except in one AAA and AAB cultivar) but present in all other AB,
AAB and ABB cultivars. Among the triploid AAB/ABB, the PCR products with B specific primers showed restriction pattern polymorphism
with AluI. In ABB genomes the band intensity was high whereas low intensity band observed in AAB genomes. Four cultivars reported
to have the ABB genome showed a pattern similar to AAB, and one cultivar reported to have AAA genome showed a pattern similar
to ABB genome, suggesting missampling or misidentification. The primers used in this study are useful to identify the presence
of B genome in banana cultivars, and band intensity may be a preliminary indicator of ploidy level of the B genome but needs
further studies with competitive PCR for clarification.
These authors contributed equally in this paper. 相似文献
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Summary A high degree of fruit and seed set was obtained in Dioscorea alata L. by hand pollination. The sexual progeny was studied in comparison with the clonal plants. In general, the seedlings were poor in growth vigour, flowering and tuber production but the variations observed in the different characters were unprecedented, indicating scope for efficacious genetic improvement in this vegetatively propagated crop. 相似文献
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When multipurpose-tree (MPT) prunings are used as a source of nitrogen to annual corps in agroforestry systems, it is important
that high levels of N recovery are attained. In order to test the effect of pruning quality and method of pruning application
on N-recovery rates, a field experiment was conducted using prunings of five MPT species and two methods of application (surface
versus incorporation). There was an interaction of pruning quality and method of pruning application on N recovery and maize
grain yield. For most MPT species used, incorporated prunings gave high nitrogen recovery compared to surface applied prunings.
In order to achieve synchrony between N supply from prunings and N demand by a maize crop, relatively large amounts of N should
be released into the soil before peak N demand by the maize crop. This could be achieved by incorporating adequate quantities
of high quality prunings such as those ofCajanus cajan andLeucaena leucocephala.
Florida Agricultural Experiment Station Journal Series Number R-05489. 相似文献
8.
Herrera MR Machocho AK Nair JJ Campbell WE Brun R Viladomat F Codina C Bastida J 《Fitoterapia》2001,72(4):444-448
The alcoholic extract of the fresh bulbs of Cyrtanthus elatus yielded zephyranthine (1) and 1,2-O-diacetylzephyranthine (2), together with three other known alkaloids. Complete assignment of 1H and 13C NMR spectra of compounds 1 and 2 was done by employment of two-dimensional NMR techniques. 相似文献
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Multipurpose trees, the integral components of homegardens, contribute significantly to the closed nutrient cycling processes
and sustainability of the ecosystem. Although, the litter production and probable nutrient returns via litter in homegardens
have been documented, quantification and characterization of the decomposition and bioelement release from the litter have
received relatively little scientific attention. The objective of the present study is to explore the litter dynamics of six
locally important multipurpose trees (Mangifera indica L., Artocarpus heterophyllus Lamk., Anacardium occidentale L., Ailanthus triphysa Dennst., Artocarpus hirsutus L. and Swietenia macrophylla L.), in an agroforestry homegarden in Southern Kerala, India. Litterfall and nutrient additions in the six species ranged
from 383 to 868 g m−2 yr−1, nitrogen, 6.4 to 8.8, phosphorus, 0.17 to 0.42 and potassium, 1.1 to 2.8 g m−2 yr−1. The annual litter output in the homegarden was 425 kg with A. hirsutus, M. indica, A. heterophyllus and A. occidentale recording significantly higher litter and nutrient additions. Leaf litter decay studies revealed A. heterophyllus and A. occidentale to be the most labile litter species and S. macrophylla the most recalcitrant. The decay rate coefficients varied significantly among the species. Foliage decomposition rates related
to the initial chemical composition of the litter revealed best correlation with lignin. NPK release was almost complete by
the end of decay in all species inspite of the initial phases of accumulation observed for nitrogen and phosphorus. Two-way
analysis of variance test revealed significant differences in the contents of the three elements as a function of species
and time elapsed. Macronutrients were released in the order K>N/P. The higher rates of decay and nutrient turnover in M. indica, A. heterophyllus and A. occidentale foliage indicated the potential of using these species’ litter as nutrient inputs in agriculture while A. triphysa, A. hirsutus and S. macrophylla perform better as organic mulches taking a longer time for decay and hence nutrient release. 相似文献
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