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81.
COMPETITION BETWEEN HERMIT HUMMINGBIRDS PHAETHORNINAE AND INSECTS FOR NECTAR IN A COSTA RICAN RAIN FOREST 总被引:1,自引:0,他引:1
Hummingbirds in the tropical rainforests of southwestern Costa Rica face intense competition from stingless bees Trigona that steal nectar from hummingbird flowers. Here we document both interference and exploitative competition between bees and hummingbirds at scarlet, hummingbird pollinated flowers of Passiflora vitifolia. Aggressive stingless bees prevented Long-tailed Hermit Hummingbirds Phaethornis superciliosus from feeding at nearly one-third of the passion flowers approached. In exclusion experiments, bees and hummingbirds each removed most of the nectar from treated flowers. Experimental exclusion of bees also increased hummingbird use of both natural and artificial flowers. 相似文献
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RAY GIBSON 《Zoologica scripta》1989,18(3):357-364
Amphiporus elongatus Stephenson, 1911, is redescribed from histological studies of five specimens obtained from near the type locality. The systematic position of the species is reassessed and a new genus, Psammamphiporus , is established for it. Psammamphiporus elongatus (Stephenson) is so far known only from two intertidal sandy localities in the Firth of Clyde. 相似文献
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JANET E. BERTRAM TIM J. CLOUGH ROBERT R. SHERLOCK LEO M. CONDRON MAUREEN O'CALLAGHAN† NAOMI S. WELLS JESSICA L. RAY 《Global Change Biology》2009,15(8):2067-2077
Atmospheric concentrations of the greenhouse gas nitrous oxide (N2 O) have continued to rise since the advent of the industrial era, largely because of the increase in agricultural land use. The urine deposited by grazing ruminant animals is a major global source of agricultural N2 O. With the first commitment period for reducing greenhouse gas emissions under the Kyoto Protocol now underway, mitigation options for ruminant urine N2 O emissions are urgently needed. Recent studies showed that increasing the urinary concentration of the minor urine constituent hippuric acid resulted in reduced emissions of N2 O from a sandy soil treated with synthetic bovine urine, due to a reduction in denitrification. A similar effect was seen when benzoic acid, a product of hippuric acid hydrolysis, was used. This current laboratory experiment aimed to investigate these effects using real cow urine for the first time. Increased concentrations of hippuric acid or benzoic acid in the urine led to reduction of N2 O emissions by 65% (from 17% to <6% N applied), with no difference between the two acid treatments. Ammonia volatilization did not increase significantly with increased hippuric acid or benzoic acid concentrations in the urine applied. Therefore, there was a net reduction in gaseous N loss from the soil with higher urinary concentrations of both hippuric acid and benzoic acid. The results show that elevating hippuric acid in the urine had a marked negative effect on both nitrification and denitrification rates and on subsequent N2 O fluxes. This study indicates the potential for developing a novel mitigation strategy based on manipulation of urine composition through ruminant diet. 相似文献
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ERIC LAM JAMES SHINE JR † JORGE DA SILVA‡ MICHAEL LAWTON STACY BONOS§ MARTIN CALVINO¶ HELAINE CARRER MARCIO C. SILVA-FILHO NEIL GLYNN†† ZANE HELSEL§ JIONG MA ‡‡ EDWARD RICHARD JR §§ GLAUCIA MENDES SOUZA¶¶ RAY MING 《Global Change Biology Bioenergy》2009,1(3):251-255
Sugarcane is a proven biofuel feedstock and accounts for about 40% of the biofuel production worldwide. It has a more favorable energy input/output ratio than that of corn, the other major biofuel feedstock. The rich resource of genetic diversity and the plasticity of autopolyploid genomes offer a wealth of opportunities for the application of genomics and technologies to address fundamental questions in sugarcane towards maximizing biomass production. In a workshop on sugarcane engineering held at Rutgers University, we identified research areas and emerging technologies that could have significant impact on sugarcane improvement. Traditional plant physiological studies and standardized phenotypic characterization of sugarcane are essential for dissecting the developmental processes and patterns of gene expression in this complex polyploid species. Breeder friendly DNA markers associated with target traits will enhance selection efficiency and shorten the long breeding cycles. Integration of cold tolerance from Saccharum spontaneum and Miscanthus has the potential to expand the geographical range of sugarcane production from tropical and subtropical regions to temperate zones. The Flex-stock and mix-stock concepts could be solutions for sustaining local biorefineries where no single biofuel feedstock could provide consistent year-round supplies. The ever increasing capacities of genomics and biotechnologies pave the way for fully exploring these potentials to optimize sugarcane for biofuel production. 相似文献
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Protein structure and enzyme action 总被引:1,自引:0,他引:1
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Fine needle aspiration (FNA) and non-suction fine needle sampling (FNS) were performed consecutively in 107 lesions from 100 patients. the quality of diagnostic material was assessed using a scoring system based on the cellularity and amount of blood in the smear. the total score in the FNS group was significantly higher (P < 0.05) than that of FNA technique. the FNS procedure is less traumatic and equally cost effective and can be safely undertaken in liver, orbital and thyroid lesions. In lymph nodes, especially in children, FNS gives an excellent cellular yield. However, this procedure can not be advocated in cystic, bony and fibrous lesions. 相似文献