Galapagos hydrothermal mounds: stratigraphy and chemistry revealed by deep-sea drilling     

Natland JH  Rosendahl B  Hekinian R  Dmitriev Y  Fodor RV  Goll RM  Hoffert M  Humphris SE  Mattey DP  Petersen N  Roggenthen W  Schrader EL  Srivastava RK  Warren N 《Science (New York, N.Y.)》1979,204(4393):613-616

The Galápagos mounds sea-floor hydrothermal system is at least 300,000 years old and once produced manganese-poor sediments, which nearly blanketed the area of the present mounds field. Present-day mound deposits are limited manganese-rich exposures, suggesting that the system has changed from rock-to water-dominated and has diminished in intensity with time.  相似文献   

Molecular cloning of the chicken progesterone receptor   总被引：16，自引：0，他引：16  

O M Conneely  W P Sullivan  D O Toft  M Birnbaumer  R G Cook  B L Maxwell  T Zarucki-Schulz  G L Greene  W T Schrader  B W O'Malley 《Science (New York, N.Y.)》1986,233(4765):767-770

To define the functional domains of the progesterone receptor required for gene regulation, complementary DNA (cDNA) clones encoding the chicken progesterone receptor have been isolated from a chicken oviduct lambda gt11 cDNA expression library. Positive clones expressed antigenic determinants that cross-reacted with six monospecific antibodies derived from two independent sources. A 36-amino acid peptide sequence obtained by microsequencing of purified progesterone receptor was encoded by nucleotide sequences in the longest cDNA clone. Analysis of the amino acid sequence of the progesterone receptor deduced from the cDNA clones revealed a cysteine-rich region that was homologous to a region found in the estrogen and glucocorticoid receptors and to the avian erythroblastosis virus gag-erb-A fusion protein. Northern blot analysis with chicken progesterone receptor cDNA's indicated the existence of at least three messenger RNA species. These messages were found only in oviduct and could be induced by estrogens.  相似文献   

Representation of Potato Virus Y Control Strategies in Current and Past Extension Literature     

Thomas F. Döring  Joachim Schrader  Christian Schüler 《Potato Research》2006,49(3):225-239

The aphid-vectored Potato virus Y (PVY) is currently seen as an important limiting factor in the production of potatoes in many countries. Using a content-analysis approach, we investigated the German extension literature for recommendations regarding the control of PVY. Media included articles from periodicals addressing farmers and agricultural textbooks published in the last five decades (1955–2004). In the current literature (1995–2004), the clearly dominating strategy was found to be insecticidal control, although this strategy has been subject to some criticism in the scientific literature. Over the last five decades we also found a strongly increasing representation of insecticidal strategies. Furthermore, over this period of time, information diversity, measured as the number of different strategies proposed per article or per textbook, decreased consistently. Electronic supplementary material The online version of this article () contains supplementary material that is available to authorized users.  相似文献   

Photoinduced Chemical Dynamics of High-Spin Alkali Trimers     

J Higgins  C Callegari  J Reho  F Stienkemeier  WE Ernst  KK Lehmann  M Gutowski  G Scoles 《Science (New York, N.Y.)》1996,273(5275):629-631

Nanometer-sized helium droplets, each containing about 10(4) helium atoms, were used as an inert substrate on which to form previously unobserved, spin-3/2 (quartet state) alkali trimers. Dispersed fluorescence measurements reveal that, upon electronic excitation, the quartet trimers undergo intersystem crossing to the doublet manifold, followed by dissociation of the doublet trimer into an atom and a covalently bound singlet dimer. As shown by this work, aggregates of spin-polarized alkali metals represent ideal species for the optical study of fundamental chemical dynamics processes including nonadiabatic spin conversion, change of bonding nature, and unimolecular dissociation.  相似文献   

Three Quarter-Centuries of Cytology     

Schrader F 《Science (New York, N.Y.)》1948,107(2772):155-159

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Detection of off-flavour in channel catfish (Ictalurus punctatus Rafinesque) fillets by trained dogs     

Richard A Shelby  Lawrence J Myers  Kevin K Schrader  & Phillip H Klesius 《Aquaculture Research》2006,37(3):299-301

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Polymerase chain reaction-based identity assay for pathogenic turkey Eimeria     

Cook SM  Higuchi DS  McGowan AL  Schrader JS  Withanage GS  Francis MJ 《Avian diseases》2010,54(4):1152-1156

Diagnosis of turkey Eimeria infection by conventional parasitologic methods is challenging and, until now, no molecular tools existed that clearly distinguished the four widely recognized pathogenic species: Eimeria adenoeides, E. meleagrimitis, E. gallopavonis, and E. dispersa. In this study, the internal transcribed spacer region one (ITS-1) was amplified and sequenced from 23 conventionally characterized reference samples. Phylogenic analysis segregated samples into five distinct cluster groups. The ITS-1 region(s) within each cluster were of a particular length and shared from 96% to 100% identity, while amplified ITS-1 region(s) between clusters differed in length and shared only 10.6% to 49.7% sequence identity. In addition, we developed PCR primer sets as diagnostic tools capable of specifically identifying members of each of the five clusters.  相似文献   

In vitro comparisons of the inhibitory activity of florfenicol,copper sulphate and potassium permanganate towards Aeromonas hydrophila and Flavobacterium columnare     

Kevin K. Schrader  Marcuslene D. Harries  Ahmed M. Darwish 《Aquaculture Research》2013,44(2):212-219

Aeromonas hydrophila and Flavobacterium columnare, the aetiological agents of motile aeromonas septicaemia (MAS) and columnaris disease respectively, have been recently causing crippling mortalities to the sunshine bass, Morone chrysops female ×Morone saxatilis male (Percichthyidae), industry in the United States. Isolates of A. hydrophila and F. columnare obtained from fish that died during farm outbreaks were subjected to in vitro evaluation of florfenicol (FFC), copper sulphate (CuSO₄) and potassium permanganate (KMnO₄). Florfenicol inhibited the growth of A. hydrophila and F. columnare more than CuSO₄ and KMnO₄. The minimum inhibition concentration (MIC) of FFC was 0.04 ± 0 and 0.2 ± 0.1 mg L^?1 for A. hydrophila and F. columnare respectively, while the 50% inhibition concentration (IC50) for A. hydrophila and F. columnare was 0.23 ± 0.01 and 0.4 ± 0.2 mg L^?1 respectively. Copper sulphate was more effective against A. hydrophila than KMnO₄; CuSO4 had a MIC of 83.2 ± 0 mg L^?1 compared to 158.0 ± 0 mg L^?1 for KMnO₄. Copper sulphate was also more effective against F. columnare than KMnO₄. The IC50 values of CuSO₄ and KMnO₄ towards F. columnare were 4.8 ± 0.3 and 8.7 ± 1.6 mg L^?1 respectively, and the minimum bactericidal concentration values of CuSO₄ and KMnO₄ towards F. columnare were 25.0 ± 0 and > 158.0 mg L^?1 respectively. In addition, F. columnare was more sensitive to CuSO₄ and KMnO₄ than A. hydrophila.  相似文献   

Identification of pests and pathogens recorded in Europe with relation to fruit imports          下载免费PDF全文

K. Steffen  F. Grousset  G. Schrader  F. Petter  M. Suffert 《EPPO Bulletin》2015,45(2):223-239

Within the framework of the EU project DROPSA (‘Strategies to develop effective, innovative and practical approaches to protect major European fruit crops from pests and pathogens’), a review on pests (including pathogens) that have fruit species as their host plants was conducted. The focus was on pests that have been introduced into Europe or were found in the fruit trade during the last 10–15 years. Among the 387 recorded pests, the following groups were identified: 1. fruit and vinegar flies, 2. scale insects, 3. fungi, 4. plant viruses, 5. bacteria, 6. pests of unknown risk, 7. tropical fruit pests, 8. pests that had an unexpected change of hosts, 9. fruit pests not likely to be transported on fruit and 10. ‘hitchhikers’ (non‐fruit pests intercepted on fruit/fruit plants, fruit pests intercepted on other commodities than fruit). The large number of pests identified, from different taxonomic groups and origins, shows that fruit are an important pathway for pests, threatening fruit production in Europe.  相似文献   

Ultrasound during mid‐gestation: Agreement with physical foetal and placental measurements and use in predicting gestational age in sheep          下载免费PDF全文

AK Jones  RE Gately  KK McFadden  ML Hoffman  SM Pillai  SA Zinn  KE Govoni  SA Reed 《Reproduction in domestic animals》2017,52(4):649-654

To determine the effects of poor maternal nutrition and litter size on foetal growth during mid‐gestation, pregnant ewes (n = 82) were fed 100%, 60% or 140% of NRC TDN beginning at day 30.2 ± 0.2 of gestation. Transabdominal ultrasound was performed weekly between day 46.0 ± 0.4 and 86.0 ± 0.7 to monitor foetal heart width (HW), umbilical diameter (UMB), rib width (RW) and placentome outer (OD) and inner diameter (ID). Data were analysed with repeated‐measures using the mixed procedure for effects of maternal diet, litter size and gestation, and equations predictive of gestational age were generated using the regression procedure. To determine the agreement of ultrasound measurement and actual size, ewes (n = 20–21) were euthanized at day 45 or 90 to obtain corresponding postmortem measurements for Bland–Altman analysis. The HW, UMB and placentome OD and ID increased with gestation (p < .0001) but were unaffected by maternal diet or litter size (p ≥ .12). Ultrasound underestimated postmortem measurements of HW (14.8%), UMB (7.3%), placentome OD (4.5%) and ID (37.3%) at day 90 of gestation. Ultrasound underestimated RW at day 45 (7.7%) but overestimated RW (23.8%) at day 90, indicating inconsistent bias when reporting RW by ultrasound. Combining the HW, UMB, RW and placentome OD generated the strongest equation predictive of gestational age (R² = .91). These findings indicate that during mid‐gestation, maternal diet or litter size did not affect HW, UMB or placentome diameters and these factors can be used to estimate gestational age.  相似文献