Screening Mangrove Endophytic Fungi for Antimalarial Natural Products

We conducted a screening campaign to investigate fungi as a source for new antimalarial compounds. A subset of our fungal collection comprising Chinese mangrove endophytes provided over 5000 lipophilic extracts. We developed an accelerated discovery program based on small-scale cultivation for crude extract screening and a high-throughput malaria assay. Criteria for hits were developed and high priority hits were subjected to scale-up cultivation. Extracts from large scale cultivation were fractionated and these fractions subjected to both in vitro malaria and cytotoxicity screening. Criteria for advancing fractions to purification were developed, including the introduction of a selectivity index and by dereplication of known metabolites. From the Chinese mangrove endophytes, four new compounds (14–16, 18) were isolated including a new dimeric tetrahydroxanthone, dicerandrol D (14), which was found to display the most favorable bioactivity profile.     

The use of a T-maze to measure cognitive–motor function in cats (Felis catus)

Few tests have been developed to evaluate the cognitive and motor capabilities of domestic cats, despite the suitability of cats for specific studies of neuroanatomy, infectious diseases, development, aging, and behavior. The present study evaluated a T-maze apparatus as a sensitive and reliable measure of cognition and motor function in cats. Eighteen purpose-bred, specific pathogen-free, male, neutered domestic short-haired cats (Felis catus), 1-2 years of age, were trained and tested to a T-maze protocol using food rewards. The test protocol consisted of positional discrimination training (left arm or right arm) to reach a predetermined criterion, followed by 2 discrimination reversal tests. The 2 reversal tests documented the ability of the subjects to respond to a new reward location by switching arms of the T-maze. Data were collected on side preference, number of correct responses, and latency of the responses by the subjects. Aided by a customized computer program (CanCog Technologies), data were recorded electronically as each cat progressed from the start box to the reward arm. The protocol facilitated rapid training to a high and consistent level of performance during the discrimination training. This learning was associated with a decrease in the latency to traverse the maze to a mean of 4.80 ± 0.87 seconds, indicating strong motivation and consistent performance. When the rewarded side was reversed in the test phase, the cats required more trials to reach the criterion, as expected, but again showed reliable learning. The latency to the reward in the first session of reversal increased 86% from the first to the last trial, indicating that it may provide a useful index of cognitive processing. Latencies subsequently decreased as the new reversal paradigm was learned. This paradigm provides a relatively rapid and reliable test of cognitive–motor performance that can be used in various settings for the evaluation of feline cognitive and motor function.     

Life after the regime: market instability with the fall of the US food regime

The US food regime maintained some degree of stability in terms of prices and production levels for commodities in the world economy. This food regime, resting on supply management policy, began to falter in the early 1970s. In the late-1980s and 1990s, notable changes occurred in the world economy regarding agriculture as the food regime became more market-oriented. The end of the twentieth century saw the breakdown of many institutions, organizations, and international agreements that had tried to stabilize prices and production from 1945 to 1975. This paper examines this period of change (roughly 1960–2010) and explores the effects on five commodities: cocoa, coffee, corn, soybeans, and wheat. These commodities offer important points of comparison. First, while cocoa, coffee, and wheat were regulated by international organizations and agreements, corn and soybeans were not. Second, the US dominated the international corn and soybean markets, but the cocoa, coffee, and wheat markets were much more competitive. And third, corn, soybeans, and wheat were commodities largely produced in the core of the world economy, while cocoa and coffee were produced in the periphery. Thus, comparing the effect of the fall of the US food regime on these commodities reveals the importance of previous regulation, the level of market competition, and geographic origin in the world economy.     

酶制剂在家禽日粮中的应用

<正>国际家禽科学论坛于2008年1月21-22日在美国亚特兰大世界议会中心举办。本次论坛由美国南部家禽科学会(southern poultry science society)、南部禽病协商会(southern conference on avain disease)和美国家禽与蛋品协会联合发起。     

Sequencing of Culex quinquefasciatus establishes a platform for mosquito comparative genomics

Culex quinquefasciatus (the southern house mosquito) is an important mosquito vector of viruses such as West Nile virus and St. Louis encephalitis virus, as well as of nematodes that cause lymphatic filariasis. C. quinquefasciatus is one species within the Culex pipiens species complex and can be found throughout tropical and temperate climates of the world. The ability of C. quinquefasciatus to take blood meals from birds, livestock, and humans contributes to its ability to vector pathogens between species. Here, we describe the genomic sequence of C. quinquefasciatus: Its repertoire of 18,883 protein-coding genes is 22% larger than that of Aedes aegypti and 52% larger than that of Anopheles gambiae with multiple gene-family expansions, including olfactory and gustatory receptors, salivary gland genes, and genes associated with xenobiotic detoxification.     

The effect of potassium deficiency on chemical, biochemical and physical factors commonly associated with blackspot development in potato tubers

Blackspot bruise is a physiological disorder of potato tubers resulting from mechanical damage to tissues during handling. This study examined the effect of potassium nutrition on biochemical and physical changes normally associated with blackspot bruise in potato tubers. Four potato (Solanum tuberosum L.) genotypes (TXA 763-5 [very resistant], Ranger Russet [very susceptible], Russet Burbank [susceptible], and Lemhi Russet [very susceptible]) differing in susceptibility to blackspot bruise were grown at three potassium nutrition levels (100%, 10% and 0% of the potassium in full strength Hoagland’s solution). Tubers from the three treatments were tested for their chemical, biochemical and physical characteristics commonly related to blackspot bruise susceptibility. The potential to develop malanin pigments was measured as total oxidative potential (optical density, OD₄₇₅) of clarified tuber homogenates. Tuber tissue extracts were assayed for polyphenol oxidase (PPO) activity with catechol, measured as increase in OD₄₁₀ over time. Specific gravity of tubers was determined with a brine solution series. Physical property measurements were made by impacting cores of tuber tissue in a specially designed instrumented pendulum. Shock wave speed, Young’s modulus, failure stress, and failure strain were all measured dynamically during impact. Tubers produced under both the 10% and 0% potassium regimens had almost 2x the free tyrosine of control tubers. The 0% potassium tubers had significantly higher PPO activity than the control. Both of these factors likely contributed to the significantly higher total oxidative potential that was observed in tubers from both the 10% and 0% potassium treatments. Tubers from both the 0% and 10% potassium treatments had a significantly lower Young’s modulus (a measure of stiffness), significantly lower failure stress and the shock wave of impact propagated through both of them significantly slower. Although the cultivars were significantly different in their susceptibility to black pigment development, they all responded similarly to the treatment with regards to the variables measured. The TXA-763-5 clone was much more susceptible to developing black pigments in these tests than expected. The other three cultivars performed as they do in commerce.