Conformationally controlled chemistry: excited-state dynamics dictate ground-state reaction     

Kim MH  Shen L  Tao H  Martinez TJ  Suits AG 《Science (New York, N.Y.)》2007,315(5818):1561-1565

Ion imaging reveals distinct photodissociation dynamics for propanal cations initially prepared in either the cis or gauche conformation, even though these isomers differ only slightly in energy and face a small interconversion barrier. The product kinetic energy distributions for the hydrogen atom elimination channels are bimodal, and the two peaks are readily assigned to propanoyl cation or hydroxyallyl cation coproducts. Ab initio multiple spawning dynamical calculations suggest that distinct ultrafast dynamics in the excited state deposit each conformer in isolated regions of the ground-state potential energy surface, and, from these distinct regions, conformer interconversion does not effectively compete with dissociation.  相似文献   

Effects of organic chromium supplementation to ifnishing lambs diet on growth performance,carcass characteristics and meat quality     

Laura Moreno-Camarena  Ignacio Domnguez-Vara  Jos Brquez-Gastelum  Juan Snchez-Torres  Juan Pinos-Rodrguez  Antonia Mariezcurrena-Berasain  Ernesto Morales-Almarz  Abdelfattah Z M Salem 《中国农业科学(英文版)》2015,(3)

The objective of this study was to evaluate supplemental organic chromium (Cr) to ifnishing lambs on growth performance, carcass characteristics, and meat quality. Eighteen Suffolk lambs (age (4.5±0.2)...  相似文献   

Growth,hormonal status and protein turnover in rats fed on a diet containing peas (Pisum sativum L.) as the source of protein     

J. A. Martinez  R. Marcos  M. T. Macarulla  J. Larralde 《Plant foods for human nutrition (Dordrecht, Netherlands)》1995,47(3):211-220

The inclusion of peas (Pisum sativum L.) as the source of protein in the diet of growing rats brings about a reduction in growth rate as well as the impairment in the liver, muscle and spleen weights as compared with casein fed controls. Also, a fall in plasma glucose, triglycerides and protein was observed in the legume fed animals, while no changes in cholesterol levels were found. Furthermore, the rats fed on the diet containing peas showed lower levels of plasma insulin, corticosterone, IGF-I and T₄ as compared with casein controls. Liver and muscle total protein (mg) and total DNA (mg) were markedly decreased in the legume fed animals, but DNA/g, protein/DNA and RNA/protein ratios were similar in both dietary groups. Likewise, liver and muscle fractional synthesis rates were similar in the casein and legume groups, while the whole body protein synthesis is assumed to be lower in the legume fed animals due to differences in body weights. It is concluded that animals fed on a diet containing peas (Pisum sativum L.) as the only source of protein showed less adverse effects than those found with other legumes such asVicia faba L. orPhaseolus vulgaris L., in which protein quality, antinutritional factors and nutrient availability could be involved.  相似文献   

Comparison of density gradient and single layer centrifugation of stallion spermatozoa: Yield,motility and survival     

J. M. Morrell  A‐M. Dalin  H. Rodriguez‐Martinez 《Equine veterinary journal》2009,41(1):53-58

Reasons for performing study: A new, simpler, technique of colloidal centrifugation has recently been developed, designated single layer centrifugation (SLC). This technique requires evaluation by comparison with a density gradient for its ability to select the best quality spermatozoa and its practicality of use on studfarms. Objective: To compare the effect of 2 methods of colloidal centrifugation, density gradient centrifugation and single layer centrifugation, on stallion sperm motility, yield and survival, using freshly collected extended stallion semen. Methods: Aliquots of extended stallion semen from 10 stallions (38 ejaculates) were processed by the 2 methods of colloidal centrifugation. For both uncentrifuged and centrifuged samples, sperm yield was calculated and subjective sperm motility assessed over several days to provide an estimate of sperm survival. Some stored semen samples, held at 4°C overnight, were also available for testing. Results: For fresh, extended semen, a similar recovery yield of motile spermatozoa was seen for the 2 methods of preparation for single layers and density gradients, respectively. Sperm motility and survival rate were significantly improved by colloidal centrifugation compared to unprocessed ejaculate, without any significant difference between methods (SLC vs. gradient). However, the yield was reduced by 18–20% when cold‐stored semen was used for centrifugation compared to fresh semen; and more variation between ejaculates was observed than for fresh ejaculates. Again, sperm motility and sperm survival were improved in the centrifuged sperm preparations compared to stored, unprocessed ejaculates. Potential relevance: The 2 colloid centrifugation techniques produce equivalent sperm preparations in terms of sperm quality. However, the SLC method would be more practical and convenient for use in the field.  相似文献   

Short‐term intake of β‐carotene‐supplemented diets enhances ovarian function and progesterone synthesis in goats     

G. Arellano‐Rodriguez  C. A. Meza‐Herrera  R. Rodriguez‐Martinez  R. Dionisio‐Tapia  D. M. Hallford  M. Mellado  A. Gonzalez‐Bulnes 《Journal of animal physiology and animal nutrition》2009,93(6):710-715

The effect of β‐carotene supplementation upon luteal activity, measured as number (CLT) and volume (VLT) of corpus luteum, and P4 synthesis in goats, was evaluated. Goats (n = 22, 34 months) were randomly assigned to one of two experimental groups: (i) β‐carotene [Beta, n = 10; body weight (BW = 44.8 ± 1.45 kg), body condition score (BCS = 3.25 ± 0.07)], and (ii) Control (Control, n = 12; BW = 45.30 ± 1.32 kg, BCS = 3.33 ± 0.06). Upon oestrus synchronization, the Beta group received 50 mg of β‐carotene per day during 35 days pre‐ and 17 days post‐ovulation. The day 4, 8, 12 and 16 post‐ovulation, blood samples were collected for quantification of serum P4 concentrations by radioimmmunoassay, and transrectal ultrasonographic scanning was performed at day 18 for evaluating CLT and VLT. Overall, CLT and VLT mean were 3.10 and 2211.1 mm³ respectively. The Beta‐goats depicted both the largest values for CLT (p = 0.07) and serum P4 levels (p = 0.05), with no differences (p = 0.53) for VLT between treatments. Results suggest a higher efficiency within the cellular‐enzymatic groups defining the steroidogenic pathways in the β‐carotene‐supplemented goats, generating a larger P4 synthesis. The last is essential for ovulation of healthy oocytes, maintenance of uterine quiescence, nourishment and survival of the embryo around implantation; all of them of paramount significance during the maternal recognition of pregnancy process.  相似文献   

Free-choice mineral consumption in Iberian red deer (Cervus elaphus hispanicus) response to diet deficiencies     

Francisco Ceacero  Toms Landete-Castillejos  Andrs J. García  Jos A. Estvez  Alberto Martinez  Antonio Calatayud  Enrique Gaspar-Lpez  Laureano Gallego 《Livestock Science》2009,122(2-3):345-348

All mammals have the ability to taste salt, so several studies have focus on mineral selection in the diet. Sodium and phosphorus are usually the most limiting for ungulates and thus some ruminants may regulate their consumption according to mineral needs and content of food sources. The aim of this study was to assess if the amount of minerals consumed is related to daily requirements. It was performed during lactation, examining consumption of 23 adult hinds and their calves. Animals were captive in 10,000 m² enclosures without pasture. Eleven highly bioavailable mineral compounds were offered in a cafeteria test and weighed weekly. Consumption behaviour was recorded by two cameras from dawn till dusk during the whole lactation period. Incidentally, meal offered had enough minerals to meet daily requirements of all elements except Na and Co. Mineral consumption of supplements was scarce for most elements (less than 10% of daily requirements) except for Na (44%) and Co (36%). Cobalt-supplement was consumed by calves much more than by hinds (90% vs. 10%), probably because requirements for growing ruminants are about 10 times higher than for adults. Animals consumed high percentages of Na and Co but not other minerals, even though flavours of NaCl, KCl and salt-mixed trace minerals are very similar. Thus, consumption seems to reflect physiological needs.  相似文献   

Coliform retention and release in biofilms formed on new and weathered irrigation pipes     

D. R. Shelton  L. A. Kiefer  Y. A. Pachepsky  R. A. Blaustein  G. Martinez 《Irrigation Science》2013,31(5):971-981

Irrigation waters have come under increasing scrutiny as a potential source of pathogenic microorganisms contaminating fresh produce. It is generally assumed that the microbial concentrations entering and leaving irrigation pipe networks are identical. However, this may not be true if biofilms form on the inner surfaces of irrigation pipes. The retention and release of pathogens in biofilms are well documented in drinking water distribution systems, but very little data are available for irrigation systems. We examined the attachment and/or incorporation of total coliform, fecal coliform, and Escherichia coli bacteria into biofilms in new and used aluminum irrigation pipe. Water from a local creek in Maryland was used to conduct weekly irrigation events. Prior to each event, removable sections of pipe (coupons) were scraped to determine the extent of bacterial attachment; in addition, bacterial concentrations in residual water were determined. Substantial populations of coliform bacteria were found on the pipe surfaces. Old pipes had fewer attached or biofilm-incorporated coliforms and lower coliform concentrations in the residual water. High probabilities were found for average fecal coliform and total coliform concentrations being different between creek water and sprinkler water. These results have implications for monitoring and control of microbial quality of irrigation waters.  相似文献   

Induced spat production from Ostrea chilensis Philippi 1845 in mid-winter     

Louis H. DiSalvo  Elias Alarcon  Edwin Martinez 《Aquaculture (Amsterdam, Netherlands)》1983,30(1-4):357-362

Oysters transferred from south to north-central Chile were induced to mature and spawn outside their natural breeding season. The larvae were set on shell particles and whole shell as cultch, and early growth data were obtained. Hatchery production of this species in winter months may help the development of commercial oyster production in southern Chile which is currently limited by summer spatfall.  相似文献   

Growth and gonad development of the tropical black-lip pearl oyster, Pinctada margaritifera (L.), in the Gambier archipelago (French Polynesia)     

Gilles Le Moullac  Jér?me Tiapari  Hinano Teissier  Elodie Martinez  Jean-Claude Cochard 《Aquaculture International》2012,20(2):305-315

The growth and reproductive cycle of cultured black-lipped pearl oysters, Pinctada margaritifera (L.), were studied in the Gambier Islands (134°52′ W, 23°07′ S) from September 2002 to August 2003. Temperatures were recorded throughout the year, revealing seasonal temperature variations between 22.3 and 27.8°C. The mean annual chlorophyll a value, as computed from satellite data, was 0.188 ± 0.075 μg L⁻¹. To study growth and reproduction, 720 two-year-old individuals were ear hung on long-lines suspended at a depth of 7 m. Samples were taken twice a month to obtain the following measurements: shell height; wet weight of flesh and total oyster; dry weight of adductor muscle, mantle and visceral mass; and glycogen content. Gonad development was also studied by histology on parallel samples. Growth was relatively fast during the first 6 months of the study: average shell height increased from 89.1 ± 9.1 to 119.7 ± 10.8 mm and total weight from 93.4 ± 24.5 to 155.1 ± 33.6 g, between September and the end of March. Subsequently, from April to August, no significant growth was observed for shell and flesh, while the muscle weight decreased significantly. Condition index (CI), defined as the ratio of wet weight of the visceral mass to shell weight, and histological changes in the gonad revealed 3 significant reproductive events of different intensities. The analysis of correlations revealed a specific effect of the chlorophyll a concentration on the growth of shell and soma, and one of the temperature on tissue glycogen content. This study also showed also that CI could be an efficient indicator of reproductive events in pearl oyster. It thus appears that the development of gonads goes on throughout the year in the Gambier Islands, without any detectable phase of sexual rest.  相似文献   

Effects of Pro-Tex on zebrafish (Danio rerio) larvae,adult common carp (Cyprinus carpio) and adult yellowtail kingfish (Seriola lalandi)     

Jeroen G. J. Boerrigter  Hans W. van de Vis  Ruud van den Bos  Wout Abbink  Tom Spanings  Jan Zethof  Laura Louzao Martinez  Wouter F. M. van Andel  Javier Lopez-Luna  Gert Flik 《Fish physiology and biochemistry》2014,40(4):1201-1212

Aquaculture practices bring several stressful events to fish. Stressors not only activate the hypothalamus–pituitary–interrenal-axis, but also evoke cellular stress responses. Up-regulation of heat shock proteins (HSPs) is among the best studied mechanisms of the cellular stress response. An extract of the prickly pear cactus (Opuntia ficus indica), Pro-Tex, a soluble variant of TEX-OE^®, may induce expression of HSPs and reduce negative effects of cellular stress. Pro-Tex therefore is used to ameliorate conditions during stressful aquaculture-related practices. We tested Pro-Tex in zebrafish (Danio rerio), common carp (Cyprinus carpio L.) and yellowtail kingfish (Seriola lalandi) exposed to aquaculture-relevant stressors (thermal stress, net confinement, transport) and assessed its effects on stress physiology. Heat shock produced a mild increase in hsp70 mRNA expression in 5-day-old zebrafish larvae. Pro-Tex increased basal hsp70 mRNA expression, but decreased heat-shock-induced expression of hsp70 mRNA. In carp, Pro-Tex increased plasma cortisol and glucose levels, while it did not affect the mild stress response (increased plasma cortisol and glucose) to net confinement. In gills, and proximal and distal intestine, stress increased hsp70 mRNA expression; in the distal intestine, an additive enhancement of hsp70 mRNA expression by Pro-Tex was seen under stress. In yellowtail kingfish, Pro-Tex reduced the negative physiological effects of transport more efficiently than when fish were sedated with AQUI-S^®. Overall, our data indicate that Pro-Tex has protective effects under high levels of stress only. As Pro-Tex has potential for use in aquaculture, its functioning and impact on health and welfare of fish should be further studied.  相似文献