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111.
Pacheco FC Villa-Pulgarin JA Mollinedo F Martín MN Fernández JJ Daranas AH 《Marine drugs》2011,9(11):2220-2235
The red seaweed Laurencia viridis is a rich source of secondary metabolites derived from squalene. New polyethers, such as iubol (2), 22-hydroxy-15(28)- dehydrovenustatriol (3), 1,2-dehydropseudodehydrothyrsiferol (4), and secodehydrothyrsiferol (5) have been isolated and characterized from this alga. The structures were determined through the interpretation of NMR spectroscopic data and the relative configuration was proposed on the basis of NOESY spectrum and biogenetic considerations. All new compounds exhibited significant cytotoxic activity against a panel of cancer cell lines. 相似文献
112.
María G Domínguez-Bello M Andreína Pacheco Marie C Ruiz Fabián Michelangeli Matthias Leippe Miguel A de Pedro 《BMC ecology》2004,4(1):1-6
Background
In many species of birds, pair bonded males and females precisely co-ordinate their vocalisations to form duets. Duetting behaviour, although still somewhat of an enigma, is thought to function primarily in territorial defence and mate guarding. We identify an additional function of duetting in an afrotropical bird, the tropical boubou (Laniarius aethiopicus), that uses one duet type as a postconflict display probably to advertise victory to other boubous.Results
We simulated intrusions into boubou territories in the field in Ivory Coast, West Africa using playbacks of four different types of boubou duets to test the use of the presumptive acoustic victory display before, during and after playbacks. These staged encounters resulted in either retreat of the focal birds during playback or continued presence accompanied by vocal displays after playback had ceased. Losers of encounters never sung after retreating whereas 11 out of 18 pairs sung the presumptive victory duet after the encounter. Analysis revealed that the presumptive victory display was sung significantly more often after than before or during the playback treatment.Conclusion
We conclude that, most likely, the investigated duet type is a postconflict victory display – a novel function of duets. Furthermore the duet is a rare example among birds of a context-specific song. The conspicuousness of the display suggests that it is directed not only to losers of an agonistic encounter but also to other pairs of birds in neighbouring territories. 相似文献113.
CASE HISTORY: A neonatal Thoroughbred foal was presented with rib fractures and left forelimb lameness secondary to dystocia. CLINICAL FINDINGS: The foal developed a head tilt, seizures and watery diarrhoea during hospitalisation and died at 7 days of age. Histological examination of the brain and spinal cord revealed a suppurative meningoencephalomyelitis with vasculitis, and numerous intralesional, gram-negative bacilli. Similar microscopic lesions were noted in the lungs, renal medullary interstitium, and umbilicus. Bacilli in the brain, spinal cord and umbilicus were identified immunohistochemically as Salmonella group B. Salmonella agona was isolated in pure culture from the brain, lung, liver, kidney, and intestine. CONCLUSION: This is the first report of meningoencephalomyelitis and septicaemia due to Salmonella infection in an equine neonate. 相似文献
114.
Extract Listeria monocytogenes is widely distributed in the environment of farm animals. It is found in soil, faeces and nasal secretions of healthy animals, water troughs and animal feeds. Under certain conditions it becomes pathogenic, causing serious disease in cattle and sheep. Most commonly it causes meningoencephalitis but, on occasion, septicaemic listeriosis results in abortion, and more recently it has been associated with gastroenteritis. 相似文献
115.
116.
Testosterone serum profile,semen characteristics and testicular biometry of Mangalarga Marchador stallions in a tropical environment
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B Waddington JM Penitente‐Filho JGS Neves RO Pinho AY Chaya PP Maitan CO Silveira MG Neves SEF Guimarães GR de Carvalho JD Guimarães 《Reproduction in domestic animals》2017,52(2):335-343
This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20‐min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations along the day were higher at the beginning of the afternoon (from 12:00 to 15:00 hr), but a circadian secretion was not clearly observed. Mean testosterone concentrations did not differ among seasons (p > .05), but a pattern of secretion along the day showed variations with higher concentrations in the afternoon during the winter. Ejaculate volume was higher during summer; however, sperm motility decreased in summer and spring. Total sperm in ejaculate, sperm morphology and testicular biometry kept constant along the year showing no differences among the seasons. The results demonstrated that in a tropical region, reproductive aspects of stallions did not show a clearly defined seasonal variation, and months of autumn and winter were not unsuitable for reproduction of the males. 相似文献
117.
Wesley Pacheco Calixto Luciano Martins Neto 《Computers and Electronics in Agriculture》2010,71(1):1-6
The aim of this paper is to present an optimization methodology based on a genetic algorithm to obtain the soil electrical conductivity and its respective thicknesses. The method uses an experimental conductivity curve generated from the measurements made in the soil. This experimental curve is compared with a theoretical electrical conductivity curve produced by a genetic algorithm. The theoretical curve is based on Sunde’s algorithm and is exactly the inverse process of soil horizontal stratification into multi layers. The comparison between the two curves provides the error produced by the soil stratification process. Using the obtained values of electrical conductivity, the method intends to estimate characteristics such as water content, texture and salinity of the subsoil layers. 相似文献
118.
R. Esten Mason Suchismita Mondal Francis W. Beecher Arlene Pacheco Babitha Jampala Amir M. H. Ibrahim Dirk B. Hays 《Euphytica》2010,174(3):423-436
Heat stress adversely affects wheat production in many regions of the world and is particularly detrimental during reproductive
development and grain-filling. The objective of this study was to identify quantitative trait loci (QTL) associated with heat
susceptibility index (HSI) of yield components in response to a short-term heat shock during early grain-filling in wheat.
The HSI was used as an indicator of yield stability and a proxy for heat tolerance. A recombinant inbred line (RIL) population
derived from the heat tolerant cultivar ‘Halberd’ and heat sensitive cultivar ‘Cutter’ was evaluated for heat tolerance over
2 years in a controlled environment. The RILs and parental lines were grown in the greenhouse and at 10 days after pollination
(DAP) half the plants for each RIL received a three-day heat stress treatment at 38°C/18°C day/night, while half were kept
at control conditions of 20°C/18°C day/night. At maturity, the main spike was harvested and used to determine yield components.
A significant treatment effect was observed for most yield components and a HSI was calculated for individual components and
used for QTL mapping. QTL analysis identified 15 and 12 QTL associated with HSI in 2005 and 2006, respectively. Five QTL regions
were detected in both years, including QTL on chromosomes 1A, 2A, 2B, and 3B. These same regions were commonly associated
with QTL for flag leaf length, width, and visual wax content, but not with days to flowering. Pleiotropic trade-offs between
the maintenance of kernel number versus increasing single kernel weight under heat stress were present at some QTL regions.
The results of this study validate the use of the main spike for detection of QTL for heat tolerance and identify genomic
regions associated with improved heat tolerance that can be targeted for future studies. 相似文献
119.
Dinoflagellates are single-celled organisms that reflect the ecological conditions in modern oceans and lakes. Ultrastructural data and molecular phylogeny suggest that they originated in the Neoproterozoic, yet dinoflagellate ancestors are classified only to the Middle Triassic ( approximately 240 million years ago). Examination of dinoflagellate-specific biological markers (dinosteranes and 4alpha-methyl-24-ethylcholestane) in concentrated microfossils with known morphology identified ancient dinoflagellate ancestors from the Early Cambrian ( approximately 520 million years ago). 相似文献
120.
SL Collins AK Knapp JMB riggs JM Blair EM Steinauer 《Science (New York, N.Y.)》1998,280(5364):745-747
Species diversity has declined in ecosystems worldwide as a result of habitat fragmentation, eutrophication, and land-use change. If such decline is to be halted ecological mechanisms that restore or maintain biodiversity are needed. Two long-term field experiments were performed in native grassland to assess the effects of fire, nitrogen addition, and grazing or mowing on plant species diversity. In one experiment, richness declined on burned and fertilized treatments, whereas mowing maintained diversity under these conditions. In the second experiment, loss of species diversity due to frequent burning was reversed by bison, a keystone herbivore in North American grasslands. Thus, mowing or the reestablishment of grazing in anthropogenically stressed grasslands enhanced biodiversity. 相似文献