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排序方式: 共有169条查询结果,搜索用时 15 毫秒
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Mario L. Suvà Esther Rheinbay Shawn M. Gillespie Anoop P. Patel Hiroaki Wakimoto Samuel D. Rabkin Nicolo Riggi Andrew S. Chi Daniel P. Cahill Brian V. Nahed William T. Curry Robert L. Martuza Miguel N. Rivera Nikki Rossetti Simon Kasif Samantha Beik Sabah Kadri Itay Tirosh Ivo Wortman Alex K. Shalek Orit Rozenblatt-Rosen Aviv Regev David N. Louis Bradley E. Bernstein 《Cell》2014
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Melanoides tuberculata in the Kuala Lumpur area of Malaysia were found to be entirely female, reproducing parthenogenetically. The reproductive system is extremely simple in structure and histology, lacking all the glandular developments common in most mesogastropods. Eggs pass into a cephalic brood-pouch where they develop to juveniles of 5–6 shell whorls before emergence. Numbers of developing young in the brood-pouches increased with shell height of the parents except for a decline in the few very largest snails. The highest brood-pouch count was 265, but average counts were much lower. 85 % of developing young in the brood-pouches were very early stages from eggs to embryos of one whorl only, perhaps implying that many eggs fail to develop successfully to young snails. Three localities studied yielded consistently different brood-pouch counts, implying variation in fecundity. Juveniles emerge from the brood-pouch most commonly between nightfall and midnight and normal emergence seems to require diurnal alternation of light and dark. In continuous darkness, brood-pouch counts increased markedly, perhaps as a result of greater activity and feeding during darkness. Several features of the reproductive biology suggest that Melanoides might become a useful experimental animal in freshwater studies. 相似文献
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Dayane Priscilla de Souza Queiroz Carlos Alexandre Carollo M?nica Cristina Toffoli Kadri Yasmin Silva Rizk Vanessa Carneiro Pereira de Araujo Paulo Eduardo de Oliveira Monteiro Patrik Oening Rodrigues Elisa Teruya Oshiro Maria de Fátima Cepa Matos Carla Cardozo Pinto de Arruda 《Memórias do Instituto Oswaldo Cruz》2016,111(3):147-154
The polar hydroethanolic extract from Selaginella sellowii(SSPHE)
has been previously proven active on intracellular amastigotes (in vitro test) and
now was tested on hamsters infected with Leishmania (Leishmania)
amazonensis (in vivo test). SSPHE suppressed a 100% of the parasite load
in the infection site and draining lymph nodes at an intralesional dose of 50
mg/kg/day × 5, which was similar to the results observed in hamsters treated with
N-methylglucamine antimonate (Sb) (28 mg/Kg/day × 5). When orally
administered, SSPHE (50 mg/kg/day × 20) suppressed 99.2% of the parasite load in
infected footpads, while Sb suppressed 98.5%. SSPHE also enhanced the release of
nitric oxide through the intralesional route in comparison to Sb. The chemical
fingerprint of SSPHE by high-performance liquid chromatography with diode-array
detection and tandem mass spectrometry showed the presence of biflavonoids and high
molecular weight phenylpropanoid glycosides. These compounds may have a synergistic
action in vivo. Histopathological study revealed that the intralesional treatment
with SSPHE induced an intense inflammatory infiltrate, composed mainly of mononuclear
cells. The present findings reinforce the potential of this natural product as a
source of future drug candidates for American cutaneous leishmaniasis. 相似文献
168.
Ligularia sibirica (L.) Cass. (Asteraceae) is a EU Habitats Directive Annex II plant species that has suffered a lot from human-caused major changes in quality and availability of habitats in Estonia. The aim of this study was to find out if the observed decline in population size is reflected in the amount of genetic variation and fertility in remnant populations of this species. AFLP technique was used for that purpose. Genetic diversity within populations was assessed as the percentage of polymorphic loci in a given population and average gene diversity over loci. The degree of genetic differentiation among populations and genetic differentiation between pairs of populations was estimated. The amount of viable seeds per flower stem was compared among populations and between years (2007 and 2008). Average genetic diversity over loci and proportion of polymorphic loci in L. sibirica populations were significantly correlated with population size, suggesting the action of genetic drift and/or inbreeding. No correlation was found between genetic and geographic distances. Natural barriers like forests may have been efficiently preventing seed migration even between geographically closer populations. Results of this study suggest that genetic erosion could be partially responsible for the lower fitness in smaller populations of this species. 相似文献
169.