On the effect of glucono-δ-lactone on the yeast Pichia polymorpha

Investigation has been made into the action of glucono--lactone on living cells of Pichia polymorpha in relation to the uptake of D-(U-¹⁴C) glucose, and the incorporation of (2-¹⁴C) uracil and L-(U-¹⁴C)-threonine into RNA and protein respectively. Other factors such as the action of glucono--lactone on cell morphology and on enzymic synthesis have also been studied. The action of this compound on -glucanase has been found to take place in the hydrolytic power and not in the synthesis.     

Synthesis of β-glucanase and other extracellular proteins by cells and protoplasts of the yeast Pichia polymorpha

The synthesis of β-glucanase either by cells or by protoplasts of the yeast Pichia polymorpha has been found to occur in the presence of 2-deoxy-d-glucose in the growth medium. On the other hand, the synthesis of typical extracellular proteins such as invertase and acid phosphatase is strongly affected by the presence of the drug. The degree of inhibition is, however, directly related to the 2-deoxy-d-glucose concentration.     

Diet of breeding Eleonora's falcon Falco eleonorae in Algeria: Insights for the autumn trans‐Mediterranean avian migration

How environmental changes are affecting bird population dynamics is one of the most challenging conservation issues. Dietary studies of top avian predators could offer scope to monitor anthropogenic drivers of ecosystem changes. We investigated the diet of breeding Eleonora''s falcon in an area of Northeastern Algeria in the years 2010–2012. Feathers and insect remains originating from prey plucking behavior were analyzed, providing insights into the seasonally changing diet of this raptor, as well as the trans‐Mediterranean avian migration. A total of 77 species of birds (16 Sylviidae, 11 Turdidae, and 4 Emberizidae), 3 species of insects, and 1 lizard were identified among prey remains, reflecting a diverse diet. Diet composition and prey abundance varied seasonally, faithfully correlating with the passage of migrant birds as recorded from bird ring recoveries. Our findings suggest that dietary studies of predators might be deployed to investigate changes in bird migration. We discuss our results in the context of trans‐Mediterranean migration, with early‐season prey mainly comprising trans‐Saharan migrants (Apus apus and Merops apiaster) and late‐season prey being dominated by Mediterranean winter migrants (Erithacus rubecula, Turdus philomelos, Sylvia atricapilla, and Sturnus vulgaris). Notably, we observed a significant reduction in species richness of passerine remains in 2012, potentially highlighting a decline in the diversity of avian migrants.     

Laying low: Rugged lowland rainforest preferred by feral cats in the Australian Wet Tropics

Invasive mesopredators are responsible for the decline of many species of native mammals worldwide. Feral cats have been causally linked to multiple extinctions of Australian mammals since European colonization. While feral cats are found throughout Australia, most research has been undertaken in arid habitats, thus there is a limited understanding of feral cat distribution, abundance, and ecology in Australian tropical rainforests. We carried out camera‐trapping surveys at 108 locations across seven study sites, spanning 200 km in the Australian Wet Tropics. Single‐species occupancy analysis was implemented to investigate how environmental factors influence feral cat distribution. Feral cats were detected at a rate of 5.09 photographs/100 days, 11 times higher than previously recorded in the Australian Wet Tropics. The main environmental factors influencing feral cat occupancy were a positive association with terrain ruggedness, a negative association with elevation, and a higher affinity for rainforest than eucalypt forest. These findings were consistent with other studies on feral cat ecology but differed from similar surveys in Australia. Increasingly harsh and consistently wet weather conditions at higher elevations, and improved shelter in topographically complex habitats may drive cat preference for lowland rainforest. Feral cats were positively associated with roads, supporting the theory that roads facilitate access and colonization of feral cats within more remote parts of the rainforest. Higher elevation rainforests with no roads could act as refugia for native prey species within the critical weight range. Regular monitoring of existing roads should be implemented to monitor feral cats, and new linear infrastructure should be limited to prevent encroachment into these areas. This is pertinent as climate change modeling suggests that habitats at higher elevations will become similar to lower elevations, potentially making the environment more suitable for feral cat populations.     

Division of labor within the DNA damage tolerance system reveals non-epistatic and clinically actionable targets for precision cancer medicine

Crosslink repair depends on the Fanconi anemia pathway and translesion synthesis polymerases that replicate over unhooked crosslinks. Translesion synthesis is regulated via ubiquitination of PCNA, and independently via translesion synthesis polymerase REV1. The division of labor between PCNA-ubiquitination and REV1 in interstrand crosslink repair is unclear. Inhibition of either of these pathways has been proposed as a strategy to increase cytotoxicity of platinating agents in cancer treatment. Here, we defined the importance of PCNA-ubiquitination and REV1 for DNA in mammalian ICL repair. In mice, loss of PCNA-ubiquitination, but not REV1, resulted in germ cell defects and hypersensitivity to cisplatin. Loss of PCNA-ubiquitination, but not REV1 sensitized mammalian cancer cell lines to cisplatin. We identify polymerase Kappa as essential in tolerating DNA damage-induced lesions, in particular cisplatin lesions. Polk-deficient tumors were controlled by cisplatin treatment and it significantly delayed tumor outgrowth and increased overall survival of tumor bearing mice. Our results indicate that PCNA-ubiquitination and REV1 play distinct roles in DNA damage tolerance. Moreover, our results highlight POLK as a critical TLS polymerase in tolerating multiple genotoxic lesions, including cisplatin lesions. The relative frequent loss of Polk in cancers indicates an exploitable vulnerability for precision cancer medicine.     

Using electroporation and lipid-mediated transfection of GFP-expressing plasmids to label embryonic avian cells for vital confocal and two-photon microscopy

Fluorescent proteins have emerged as an ideal fluorescent marker for studying cell morphologies in vital systems. These proteins were first applied in whole organisms with established germ-line transformation protocols, but now it is possible to label cells with fluorescent proteins in other organisms. Here we present two ways to introduce GFP expressing plasmids into avian embryos for vital confocal and two-photon imaging. First, electroporation is a powerful approach to introduce GFP into the developing neural tube, offering several advantages over dye labeling. Second, we introduce a new lipid-based transfection system for introducing plasmid DNA directly to a small group of injected cells within live, whole embryos. These complementary approaches make it possible to transfect a wide-range of cell types in the avian embryo and the bright, stable, uniform expression of GFP offers great advantages for vital fluorescence imaging.     

A global analysis of the determinants of alien geographical range size in birds

Aim Determining the causes of range size variation in the distributions of alien species is important for understanding the spread of invasive species. Factors influencing alien range size have been explored for some species at a regional level, but to date there has been no global analysis of an entire class. Here, we present such an analysis for birds, testing for the effects of introduction event, location and species‐level variables on alien range sizes. Location Global. Methods We used a novel dataset on the global distributions of alien bird species to test for relationships between alien range size and colonization pressure, residence time, extent of the global climatic niche, native range size, body mass and specialization, using a statistical approach based on phylogenetic generalized least squares models. We performed this analysis globally, and for separate biogeographical realms. Results Approximately half of the variation in alien bird range size is explained by colonization pressure in univariate analysis. We identified consistent effects of higher colonization pressure at global and realm levels, as well as support for effects of native range size and residence time. We found less support for effects of body mass, specialization or extent of the global climatic niche on alien range size. Main conclusions Alien bird range sizes are generally small relative to their native range sizes, and many are continuing to expand. Nevertheless, current variation is predictable, most strongly by the event‐level factor of colonization pressure. Whether a species is widespread is a better predictor of alien range size than whether a species could be widespread (estimated by global climatic niche extent), while we also find effects of residence time on alien range size. These relationships may help to identify those alien species that are more likely to spread and hence have greater environmental and economic impacts where they have been introduced.     

Involvement of 1,25D3-MARRS (membrane associated, rapid response steroid-binding), a novel vitamin D receptor, in growth inhibition of breast cancer cells

In addition to classical roles in calcium homeostasis and bone development, 1,25 dihydroxyvitamin D₃ [1,25(OH)₂D₃] inhibits the growth of several cancer types, including breast cancer. Although cellular effects of 1,25(OH)₂D₃ traditionally have been attributed to activation of a nuclear vitamin D receptor (VDR), a novel receptor for 1,25(OH)₂D₃ called 1,25D₃-MARRS (membrane-associated, rapid response steroid-binding) protein was identified recently. The purpose of this study was to determine if the level of 1,25D₃-MARRS expression modulates 1,25(OH)₂D₃ activity in breast cancer cells.Relative levels of 1,25D₃-MARRS protein in MCF-7, MDA MB 231, and MCF-10A cells were estimated by real-time RT-PCR and Western blotting. To determine if 1,25D₃-MARRS receptor was involved in the growth inhibitory effects of 1,25(OH)₂D₃ in MCF-7 cells, a ribozyme construct designed to knock down 1,25D₃-MARRS mRNA was stably transfected into MCF-7 cells. MCF-7 clones in which 1,25D₃-MARRS receptor expression was reduced showed increased sensitivity to 1,25(OH)₂D₃ ( IC₅₀ 56 ± 24 nM) compared to controls (319 ± 181 nM; P < 0.05). Reduction in 1,25D₃-MARRS receptor lengthened the doubling time in transfectants treated with 1,25(OH)₂D₃. Knockdown of 1,25D₃-MARRS receptor also increased the sensitivity of MCF-7 cells to the vitamin D analogs KH1060 and MC903, but not to unrelated agents (all-trans retinoic acid, paclitaxel, serum/glucose starvation, or the isoflavone, pomiferin). These results suggest that 1,25D₃-MARRS receptor expression interferes with the growth inhibitory activity of 1,25(OH)₂D₃ in breast cancer cells, possibly through the nuclear VDR. Further research should examine the potential for pharmacological or natural agents that modify 1,25D₃-MARRS expression or activity as anticancer agents.     

赤潮棕囊藻(Phaeocystis globosa)rDNA ITS区序列变异与二级结构分析

测定了南海球形棕囊藻香港株P1、P2和湛江株ZhJ1的rDNAITS区序列(含5.8srDNA),结合Gen Bank的13条同源序列,比对长度为904bp,变异位点271个,简约信息位点221个,平均(A+T)(34.5%)<(G+C)(65.4%).藻株P1、P2和ZhJ1序列存在变异位点20个,序列间相似性为97.9%～98.5%.ITS序列在种间和种内的解析度高于18srDNA和28srDNA基因;构建的NJ树、MP树、贝叶斯推断系统树的结构是一致的,不同种类的棕囊藻单独聚类,不同地理来源的球形棕囊藻混杂分布但相同地理来源的藻株多聚类在一起.RNA二级结构显示,不同藻种间5.8srDNA区结构基本一致,表现出属的特异性;ITS1、2区结构表现较大的种间差异,表明ITS区RNA二级结构可为棕囊藻分类鉴定提供有用的分子结构信息.