The effect of short-term starvation on ovarian development and egg viability in rainbow trout (Salmo gairdneri)

Adult female rainbow trout (Salmo gairdneri) were fed a commercial trout production diet until approximately 40 days prior to spawning at which time the fish were divided in two groups. One group continued to be fed while the other group was starved until spawning. Egg size, egg number, ovary weight, and egg proximate composition were examined periodically starting 5 months before spawning. Muscle tissues of the fish were sampled at spawning to measure somatic depletion of proximate consituents in the two groups. Egg hatchability was determined by incubating test lots from each spawning female. No significant differences (P > 0.05) were found in egg hatchability between the fed and starved groups. Changes in proximate composition were observed in the eggs during the months prior to spawning, but no differences were detected between the eggs of the starved and the fed groups. Short-term starvation did not significantly alter the proximate composition of muscle tissue of the spawned female trout.     

大豆粕在鲑鳟鱼类饲料中的利用(续)

~~大豆粕在鲑鳟鱼类饲料中的利用(续)@Ronald W.Hardy     

水产饵料成分新进展和酶添加剂的潜力

从世界范围来看,提炼产品的年产量大约等于鱼粉年产量,其中80%由肉骨粉和禽类副产品组成。这些产品质量变动大、灰分含量高,它们被农林的其它部门充分利用。它们不大可能满足鱼饲料的高蛋白需要,但它们有利的氨基酸组成能弥补植物来源的蛋白质的不足。将海产品加工废弃物和渔获副产品转化成鱼粉,其数量大致相当于世界鱼粉年产量,它们就有可能为水产饲料提供数量可观的鱼粉和鱼油。但是,灰分含量高和收集加工上的困难制约了对它们的充分利用。因此粮食和含油种子的副产品成为未来水产饲料蛋白质和能量最有希望的来源。尽管对植物来源的饲料成分的利用的研究已取得了很多进展,但还有一些重大问题尚待解决。遗传学家、鱼类营养学家以及生产这些产品的工业部门创新的合作研究正在解决这些问题。使用酶添加剂来增加这些替代饲料原料的营养价值和效力是有潜力的。     

Expanding the utilization of sustainable plant products in aquafeeds: a review

Continued growth and intensification of aquaculture production depends upon the development of sustainable protein sources to replace fish meal in aquafeeds. This document reviews various plant feedstuffs, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various fish species in aquaculture. The plant feedstuffs considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuffs are considered along with the presence of any bioactive compounds that may positively or negatively affect the target organism. Lipid composition of these feedstuffs is not specifically considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid profiles to meet the metabolic requirements of fish and maximize human health benefits are important aspects. Specific strategies and techniques to optimize the nutritional composition of plant feedstuffs and limit potentially adverse effects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuffs in aquaculture to reduce dependence of animal feedstuffs and thereby enhance the sustainability of aquaculture.     

Anomalous weak magnetism in superconducting YBa2Cu3O6+x

For some time now, there has been considerable experimental and theoretical effort to understand the role of the normal-state "pseudogap" phase in underdoped high-temperature cuprate superconductors. Recent debate has centered on the question of whether the pseudogap is independent of superconductivity. We provide evidence from zero-field muon spin relaxation measurements in YBa2Cu3O6+x for the presence of small spontaneous static magnetic fields of electronic origin intimately related to the pseudogap transition. Our most significant finding is that, for optimal doping, these weak static magnetic fields appear well below the superconducting transition temperature. The two compositions measured suggest the existence of a quantum critical point somewhat above optimal doping.     

Exotic nuclei and their decay

Recent advances in nuclear accelerators and experimental techniques have led to an increased ability to synthesize new isotopes. As isotopes are produced with more and more extreme combinations of neutrons and protons in their nuclei, new phenomena are observed, and the versatility of the nucleus is increased as a laboratory for studying fundamental forces. Among the newly discovered decay modes are (i) proton radioactivity, (ii) triton, two-proton, two-neutron, and three-neutron decays that are beta-delayed, as well as (iii)(14)C emission in radioactive decay. Precise tests of the properties of the weak force have also been achieved.     

Carbon dioxide sensitivity of mosquitoes infected with California encephalitis virus

Four species of mosquitoes became sensitive to carbon dioxide approximately 3 to 4 days after they received intrathoracic injectins of California encephalitis virus. Aedes melanimon and Aedes dorsalis infected orally with California encephalitis virus also became carbon dioxide-sensitive, but mosquitoes infected transovarially did not. Sensitivity to carbon dioxide was inhibited by antiserum to California encephalitis virus. To our knowledge this is the first report of carbon dioxide sensitivity induced in arthropods by a bunyavirus and the first demonstration of this phenomenon by an arbovirus in its proven vector.     

Extracellular replication of Listeria monocytogenes in the murine gall bladder

The bacterium Listeria monocytogenes can cause a life-threatening systemic illness in humans. Despite decades of progress in animal models of listeriosis, much remains unknown about the processes of infection and colonization. Here, we report that L. monocytogenes can replicate in the murine gall bladder and provide evidence that its replication there is extracellular and intraluminal. In vivo bioluminescence imaging was employed to determine the location of the infection over time in live animals, revealing strong signals from the gall bladder over a period of several days, in diseased as well as asymptomatic animals. The data suggest that L. monocytogenes may be carried in the human gall bladder.