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491.
Moran Farhi Magali Kozin Shai Duchin 《Biotechnology & genetic engineering reviews》2013,29(2):135-148
Artemisinin, a natural compound from Artemisia annua, is highly effective in treating drug-resistant malaria. Because chemical synthesis of this natural terpenoid is not economically feasible, its only source remains as the native plant which produces only small quantities of it, resulting in a supply that is far short of demand. Extensive efforts have been invested in metabolic engineering for the biosynthesis of artemisinin precursors in microbes. However, the production of artemisinin itself has only been achieved in plants. Since, A. annua possesses only poorly developed genetic resources for traditional breeders, molecular breeding is the best alternative. In this review, we describe the efforts taken to enhance artemisinin production in A. annua via transgenesis and advocate metabolic engineering of the complete functional artemisinin metabolic pathway in heterologous plants. In both cases, we emphasize the need to apply state-of-the-art synthetic biology approaches to ensure successful biosynthesis of the drug. 相似文献
492.
Tabashnik BE Fabrick JA Henderson S Biggs RW Yafuso CM Nyboer ME Manhardt NM Coughlin LA Sollome J Carrière Y Dennehy TJ Morin S 《Journal of economic entomology》2006,99(5):1525-1530
Transgenic crops producing toxins from the bacterium Bacillus thuringiensis (Bt) kill insect pests and can reduce reliance on insecticide sprays. Although Bt cotton (Gossypium hirsutum L.) and Bt corn (Zea mays L.) covered 26 million ha worldwide in 2005, their success could be cut short by evolution of pest resistance. Monitoring the early phases of pest resistance to Bt crops is crucial, but it has been extremely difficult because bioassays usually cannot detect heterozygotes harboring one allele for resistance. We report here monitoring of resistance to Bt cotton with DNA-based screening, which detects single resistance alleles in heterozygotes. We used polymerase chain reaction primers that specifically amplify three mutant alleles of a cadherin gene linked with resistance to Bt cotton in pink bollworm, Pectinophora gossypiella (Saunders), a major pest. We screened DNA of 5,571 insects derived from 59 cotton fields in Arizona, California, and Texas during 2001-2005. No resistance alleles were detected despite a decade of exposure to Bt cotton. In conjunction with data from bioassays and field efficacy tests, the results reported here contradict predictions of rapid pest resistance to Bt crops. 相似文献
493.
Gabriel Henrique de Oliveira Caetano David G. Chapple Richard Grenyer Tal Raz Jonathan Rosenblatt Reid Tingley Monika Bhm Shai Meiri Uri Roll 《PLoS biology》2022,20(5)
The Red List of Threatened Species, published by the International Union for Conservation of Nature (IUCN), is a crucial tool for conservation decision-making. However, despite substantial effort, numerous species remain unassessed or have insufficient data available to be assigned a Red List extinction risk category. Moreover, the Red Listing process is subject to various sources of uncertainty and bias. The development of robust automated assessment methods could serve as an efficient and highly useful tool to accelerate the assessment process and offer provisional assessments. Here, we aimed to (1) present a machine learning–based automated extinction risk assessment method that can be used on less known species; (2) offer provisional assessments for all reptiles—the only major tetrapod group without a comprehensive Red List assessment; and (3) evaluate potential effects of human decision biases on the outcome of assessments. We use the method presented here to assess 4,369 reptile species that are currently unassessed or classified as Data Deficient by the IUCN. The models used in our predictions were 90% accurate in classifying species as threatened/nonthreatened, and 84% accurate in predicting specific extinction risk categories. Unassessed and Data Deficient reptiles were considerably more likely to be threatened than assessed species, adding to mounting evidence that these species warrant more conservation attention. The overall proportion of threatened species greatly increased when we included our provisional assessments. Assessor identities strongly affected prediction outcomes, suggesting that assessor effects need to be carefully considered in extinction risk assessments. Regions and taxa we identified as likely to be more threatened should be given increased attention in new assessments and conservation planning. Lastly, the method we present here can be easily implemented to help bridge the assessment gap for other less known taxa.The Red List of Threatened Species, published by the IUCN, is a crucial tool for conservation decision making, but is subject to various sources of uncertainty and bias. Modelling the threat status of all global reptiles identifies increased threat to many groups of reptiles across many regions of the world, beyond those currently recognized; moreover, it highlights the effects of the IUCN assessment procedure on eventual threat categories. 相似文献
494.
The ‘gardening concept’ for reef restoration focuses on coral colonies farming in mid-water nurseries before their transplantation onto denuded reef areas. Nurseries situated in a nutrient-enriched environment significantly curtail nursery time, but extend labor, as nursery construction and farmed corals must be frequently cleaned from competing fouling organisms. Mass farming of corals calls, therefore, for efficient and cheap maintenance methodologies, which we here tested by employing Aqua-guard M250, an anti-fouling agent used in the fish farming industry. We found that this anti-fouling paint, while reducing fouling organisms on nursery components during the crucial phase of coral ramets' development from nubbins and small fragments sizes to colony sizes suitable for transplantation, is not toxic to maricultured coral fragments that staged more than 2 cm away from the paint. Applying small quantities of such antifouling paint to coral nurseries, while restricting its use to nursery components that are not in direct contact with farmed coral material, reduces fouling coverage and cleaning procedures by 90%. 相似文献
495.
496.
Shai Meiri Erik Meijaard Serge A. Wich Colin P. Groves Kristofer M. Helgen 《Journal of Biogeography》2008,35(6):1087-1094
Aim Island mammals have featured prominently in models of the evolution of body size. Most of these models examine size evolution across a wide range of islands in order to test which island characteristics influence evolutionary pathways. Here, we examine the mammalian fauna of a single island, Borneo, where previous work has detected that some mammal species have evolved a relatively small size. We test whether Borneo is characterized by smaller mammals than adjacent areas, and examine possible causes for the different trajectories of size evolution between different Bornean species. Location Sundaland: Borneo, Sumatra, Java and the Malay/Thai Peninsula. Methods We compared the mammalian body size frequency distributions in the four areas to examine whether the large mammal fauna of Borneo is more depauperate than elsewhere. We measured specimens belonging to 54 mammal species that are shared between Borneo and any of the other areas in order to determine whether there is an intraspecific tendency for Bornean mammals to evolve small body size. Using data on diet, body size and geographical ranges we examine factors that are thought to influence body size. Results Borneo has fewer large mammals than the other areas, but this is not statistically significant. Large Bornean mammals are significantly smaller than their conspecifics in the other regions, while there are no differences between the body sizes of mammals on Sumatra, Java and the Malay/Thai Peninsula. The finding that large mammals show the greatest size difference between Borneo and elsewhere contrasts with some models of size evolution on islands of different areas. Diet does not correlate with the degree of size reduction. Sunda region endemics show a weaker tendency to be small on Borneo than do widespread species. Main conclusions We suggest that soil quality may drive size evolution by affecting primary productivity. On Borneo, where soils are generally poor in nutrients, this may both limit biomass and cause mammals to be reduced in body size. We hypothesize that widespread species respond to low resource abundance by reducing in size, while endemic elements of the fauna have had longer to adjust to local conditions by altering their behaviour, physiology and/or ecology, and are thus similar in size across the region. 相似文献
497.
Protein folding and clearance networks sense and respond to misfolded and aggregation-prone proteins by activating
cytoprotective cell stress responses that safeguard the proteome against damage, maintain the health of the cell, and
enhance lifespan. Surprisingly, cellular proteostasis undergoes a sudden and widespread failure early in Caenorhabditis
elegans adulthood, with marked consequences on proteostasis functions later in life. These changes in the regulation of
quality control systems, such as chaperones, the ubiquitin proteasome system and cellular stress responses, are controlled
cell-nonautonomously by the proliferation of germline stem cells. Here, we review recent studies examining changes in
proteostasis upon transition to adulthood and how proteostasis is modulated by reproduction onset, focusing on C. elegans.
Based on these and our own findings, we propose that the regulation of quality control systems is actively remodeled
at the point of transition between development and adulthood to influence the subsequent course of aging. 相似文献
498.
Eran Brokovich Shai Einbinder Salit Kark Nadav Shashar Moshe Kiflawi 《Environmental Biology of Fishes》2007,80(1):1-6
Juveniles of many coral reef fish species are thought to either follow the same bathymetric distribution patterns as the adults,
or to occupy shallower waters. However, our knowledge base suffers a dearth of data from the deep reefs (>40 m). In a recent
survey of the deep reefs of the northern Gulf of Aqaba (<65 m), we examined the bathymetric distribution of 26 diurnal zooplanktivorous
species. In sharp contrast to the general trend known from the literature and from this research, the abundance of juvenile
zebra angelfish, Genicanthus caudovittatus, peaked at deeper waters (60–65 m) compared with the adults (30 m). This suggests that the deeper reefs may serve as nursery
grounds for the zebra angelfish. Peak juvenile abundance coincided with relatively low predator abundances. This raises the
question, which factors constrain the bathymetric distribution of the remaining species. Our findings stress the potential
importance of deep coral reef research for understanding the ecological patterns and processes that govern reef community
structure. 相似文献
499.
Neuropeptide Y (NPY) and polypeptide YY (PYY) are two ubiquitous neuropeptides, found in brain and intestines, respectively, where they exert important regulatory functions. In this study, a new member of the YY family recently isolated from amphibian skin, skin-PYY (SPYY), is reported to inhibit irreversibly the proliferation of a broad spectrum of pathogenic microorganisms. NPY and PYY are shown to be endowed with the same activity. Their potency is similar to that of other antibacterial peptides which have been shown to exert their function by disintegrating the bacterial membrane. These findings and the fact that the C-terminal alpha-helical domain SPYY14–36, which is highly conserved among the family members, was responsible for killing microorganisms and for permeation of phospholipid vesicles, suggested that the antibiotic activity may emerge via a membrane permeation mechanism. These findings also raise the question whether NPY and PYY exert in vivo a similar function in mammals. 相似文献
500.
Brian Kidd Shai Shen‐Orr Jordan Price Justin Jarrell Tiffany Tse Huang Huang Peder Lund Holden T Maecker Paul J Utz Cornelia L Dekker Daphne Koller Mark M Davis 《Molecular systems biology》2013,9(1)
Despite the importance of the immune system in many diseases, there are currently no objective benchmarks of immunological health. In an effort to identifying such markers, we used influenza vaccination in 30 young (20–30 years) and 59 older subjects (60 to >89 years) as models for strong and weak immune responses, respectively, and assayed their serological responses to influenza strains as well as a wide variety of other parameters, including gene expression, antibodies to hemagglutinin peptides, serum cytokines, cell subset phenotypes and in vitro cytokine stimulation. Using machine learning, we identified nine variables that predict the antibody response with 84% accuracy. Two of these variables are involved in apoptosis, which positively associated with the response to vaccination and was confirmed to be a contributor to vaccine responsiveness in mice. The identification of these biomarkers provides new insights into what immune features may be most important for immune health. 相似文献