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121.
122.
Fried B. and Huffman J. E. 1982. Excystation and development in the chick and on the chick chorioallantois of the metacercaria of Sphaeridiotrema globulus (Trematoda). International Journal for Parasitology12: 427–431. Encysted metacercariae of Sphaeridiotrema globulus were obtained from naturally infected Goniobasis virginica snails in Morris County, New Jersey, U.S.A. These metacercariae were successfully excysted within l h in an alkaline bile salts trypsin medium maintained at 41°C in the absence of acid pepsin pretreatment. Encysted metacercariae treated in 3% sodium bicarbonate produced successful infections in day-old domestic chicks and worms became ovigerous in the lower ileum by day 4. Excysted metacercariae transferred to the chorioallantois of 6–10-day-old chick embryos maintained at 41°C developed into ovigerous adults by day 4. 相似文献
123.
Enrique Angeles Kirsten Folting Paul A. Grieco John C. Huffman R. Miranda Manuel Salmón 《Phytochemistry》1982,21(7):1804-1806
From the methanolic extract of Stevia polycephala a new clerodane-type diterpene, stephalic acid, was isolated. The structure and stereochemistry were determined by a combination of spectral data and single-crystal X-ray analysis. 相似文献
124.
Yukio Takahata Michael A. Huffman Shigeru Suzuki Naoki Koyama Juichi Yamagiwa 《Primates; journal of primatology》1999,40(1):143-158
There is wide interest in the effects of reproductive biology, mating partner preference, and rank on mating success (MS)
and reproductive success (RS) in primates. In particular, theory stresses importance on the mechanisms for attaining RS. Most
theory hedges on competitive ability and priority of access to resources, whether they be food or estrous females. However,
the majority of data used in favor of such hypotheses come from relatively short-term studies. We review these hypotheses
based on long-term data from provisioned and unprovisioned populations of Japanese macaques. Neither MS nor RS were consistently
attained by high-ranking males and females. For males, female choice and mating partner preference is seen to over-ride most
male-male competitive behaviors likely to affect MS and RS through priority of access to estrous females. Long-term mating
patterns driven largely by female partner preferences, results in decreasing MS and RS for older higher-ranking males. The
long-term trend for females to prefer less familiar or novel partners results in higher MS and RS for younger, middle-ranking
males. The effects of this vary according to troop size and the duration of male tenure. For females, no consistent trend
was recognized for rank related RS in either provisioned or unprovisioned troops. Non-reproductive mating may provide differential
benefit to high-ranking females for access to limited food resources in some habitats but overall the relationship was inconclusive.
Distribution and defendability of food resource, rather than provisioning per se may be more important. 相似文献
125.
126.
The Atx1 metallochaperone protein is a cytoplasmic Cu(I) receptor that functions in intracellular copper trafficking pathways in plants, microbes, and humans. A key physiological partner of the Saccharomyces cerevisiae Atx1 is Ccc2, a cation transporting P-type ATPase located in secretory vesicles. Here, we show that Atx1 donates its metal ion cargo to the first N-terminal Atx1-like domain of Ccc2 in a direct and reversible manner. The thermodynamic gradient for metal transfer is shallow (K(exchange) = 1.4 +/- 0.2), establishing that vectorial delivery of copper by Atx1 is not based on a higher copper affinity of the target domain. Instead, Atx1 allows rapid metal transfer to its partner. This equilibrium is unaffected by a 50-fold excess of the Cu(I) competitor, glutathione, indicating that Atx1 also protects Cu(I) from nonspecific reactions. Mechanistically, we propose that a low activation barrier for transfer between partners results from complementary electrostatic forces that ultimately orient the metal-binding loops of Atx1 and Ccc2 for formation of copper-bridged intermediates. These thermodynamic and kinetic considerations suggest that copper trafficking proteins overcome the extraordinary copper chelation capacity of the eukaryotic cytoplasm by catalyzing the rate of copper transfer between physiological partners. In this sense, metallochaperones work like enzymes, carefully tailoring energetic barriers along specific reaction pathways but not others. 相似文献
127.
José S. Carrión Louis Scott Tom Huffman Cobus Dreyer 《Vegetation History and Archaeobotany》2000,9(4):239-249
Thick accumulations of consolidated cow dung occur in ancientkraals (byres or corrals) in the bushveld and highveld areas of Zimbabwe, Botswana, and South Africa dating from the last 2000 years. They originated from long-term cattle herding by Iron Age people. The vitrified or baked dung deposits are thought to be a product of the burning of cow dung as fuel, either for domestic purposes or for iron smelting. In order to establish the palaeoecological potential of this material, 36 samples of cow dung from archaeological sites within the present-day savanna and grassland biomes were analyzed for pollen and other microfossils. Of the samples, 29 contained pollen together with other microfossils that support a faecal origin of the material such as sordariaceous ascospores,Thecaphora, Gelasinospora, andChaetomium, and eggs of the intestinal parasiteTrichuris. Similar microfossils were also found in recent fresh cow dung from the same study areas. The presence of pollen grains and spores in most of the Iron Age samples lead to the assumption that they survived the burning because fire temperatures were not high enough to destroy them. Pollen in these cow dung pieces is apparently sealed and can be preserved under open-air conditions at sites under which pollen in other deposits like soils, will decay away. Good pollen preservation and palynomorph diversity were found with mainly Poaceae, and secondly Chenopodiaceae and Cyperaceae as the most important pollen types, while trees and shrubs indicating savanna are rare. In the case of the samples that came from the subtropical savanna biome the latter result is unexpected and suggests that the cattle were kept in more open vegetation than the woody environments of today. Recent cow dung samples reflect the composition of present-day vegetation by showing considerably higher proportions of tree pollen than the fossil assemblages. 相似文献
128.
Hasegawa H Ikeda Y Fujisaki A Moscovice LR Petrzelkova KJ Kaur T Huffman MA 《The Journal of parasitology》2005,91(6):1314-1317
129.
Giblin GM Box PC Campbell IB Hancock AP Roomans S Mills GI Molloy C Tranter GE Walker AL Doctrow SR Huffman K Malfroy B 《Bioorganic & medicinal chemistry letters》2001,11(11):1367-1370
A series of novel manganese(III) complexes is described based on a 6,6'-bis(2-hydroxyphenyl)-2,2'-bipyridine template. These complexes show superoxide dismutase and catalase activity. The effect of the aromatic substitution pattern on the SAR is described. 相似文献
130.