Diversity oriented synthesis of chromene-xanthene hybrids as anti-breast cancer agents

A diverse library of chromene-xanthene hybrids were synthesized through intramolecular Friedel-Crafts reaction of the arenoxy carbinols. Examples include first incorporation of amino acid tyrosine into xanthene skeletons with polar functionalities. A careful structural evaluation revealed that tyrosine crafted chromene-xanthene hybrids exhibited good activities against breast cancer cell lines MCF-7, MDA-MB-231. The lead compound 16 displays significant cell cycle arrest at G1 phase and induces apoptosis in MDA-MB-231 cells.     

Regulation of Stomatal Defense by Air Relative Humidity

It has long been observed that environmental conditions play crucial roles in modulating immunity and disease in plants and animals. For instance, many bacterial plant disease outbreaks occur after periods of high humidity and rain. A critical step in bacterial infection is entry into the plant interior through wounds and natural openings, such as stomata, which are adjustable microscopic pores in the epidermal tissue. Several studies have shown that stomatal closure is an integral part of the plant immune response to reduce pathogen invasion. In this study, we found that high humidity can effectively compromise Pseudomonas syringae-triggered stomatal closure in both Phaseolus vulgaris and Arabidopsis (Arabidopsis thaliana), which is accompanied by early up-regulation of the jasmonic acid (JA) pathway and simultaneous down-regulation of salicylic acid (SA) pathway in guard cells. Furthermore, SA-dependent response, but not JA-dependent response, is faster in guard cells than in whole leaves, suggesting that the SA signaling in guard cells may be independent from other cell types. Thus, we conclude that high humidity, a well-known disease-promoting environmental condition, acts in part by suppressing stomatal defense and is linked to hormone signaling in guard cells.The phyllosphere is one of the most diverse niches for microbe inhabitation. Numerous bacteria can survive and proliferate on the surface of the plant without causing any harm (Lindow and Brandl, 2003). However, for a bacterial pathogen to cause disease, it must penetrate through the plant epidermis and be able to survive and proliferate inside the plant. The mode and mechanism of penetration into the plant tissue is a critical step for infection, especially for bacterial pathogens that rely on natural openings and accidental wounds on the plant surface to colonize internal tissues (Misas-Villamil et al., 2013). Stomata are an example of such openings, providing one of the main routes through which the foliar pathogen Pseudomonas syringae transitions from avirulent epiphytic to virulent endophytic lifestyles (Melotto et al., 2008). This abundant opening in the epidermal tissue is not a passive port that allows unrestricted entry of microbes. It has been shown that plants are able to respond to human and plant bacterial pathogens by actively closing the stomatal pore (McDonald and Cahill, 1999; Melotto et al., 2006; Gudesblat et al., 2009; Zhang et al., 2010; Roy et al., 2013; Arnaud and Hwang, 2015), a phenomenon described as stomatal immunity (Sawinski et al., 2013). Several lines of evidence point to the complexity of this response and show that stomatal closure is an integral basal plant defense mechanism to restrict the invasion of pathogenic bacteria into plant tissues (Ali et al., 2007; Melotto et al., 2008; Zhang et al., 2008; Gudesblat et al., 2009). However, certain bacterial pathogens, such as Xanthomonas campestris pv campestris (Gudesblat et al., 2009), P. syringae pv syringae (Pss) B728a (Schellenberg et al., 2010), and P. syringae pvs tabaci, tomato, and maculicola (Melotto et al., 2006), can successfully cause disease by producing toxins that overcome stomatal immunity. Specifically, P. syringae pv tomato (Pst) DC3000 uses coronatine (COR) as such a toxin.In this study, we focused on elucidating environmental regulation of stomatal-based defense against bacterial invasion. Changes in environmental conditions, such as air relative humidity (RH), light, and carbon dioxide concentration regulate guard cell turgidity that consequently alters stomatal aperture size and the basic functions of stomata in plants, i.e. exchange of photosynthetic gases and regulation of water loss by transpiration (Zelitch, 1969; Schroeder et al., 2001; Fan et al., 2004). In natural conditions, plants are exposed to both biotic and abiotic stresses, and guard cells need to prioritize their response to the simultaneous occurrence of these stresses. For instance, it is a common observation that severe outbreaks of bacterial disease in the field are often associated with periods of heavy rain or high air humidity (Goode and Sasser, 1980). Mechanical wounding of plant tissues by rain might be one way that allows pathogens to bypass the stomatal route and gain unprecedented access to the plant interior. Additionally, the formation of large bacterial aggregates under high humidity on the leaf surface (Monier and Lindow, 2004) and splashing of bacteria during rain may also contribute to the spreading of disease at a higher rate. Interestingly, to ensure infection in the laboratory, researchers commonly expose plants to very high humidity for an extended period after surface inoculation. Here, we demonstrate that high RH compromises stomatal defense in Arabidopsis (Arabidopsis thaliana) and common bean (Phaseolus vulgaris) against P. syringae, allowing more bacteria to enter the leaf tissue and contributing to severe infections. Compromised bacterial-triggered stomatal closure due to high RH is accompanied by changes in plant hormone signaling in Arabidopsis. Specifically, high RH leads to activation of the jasmonic acid (JA) signaling pathway and down-regulation of the salicylic acid (SA) signaling in guard cells. These results connect plant physiology with epidemiology and advance the current understanding of foliar bacterial infection in plants.     

Cell Adhesion on Amyloid Fibrils Lacking Integrin Recognition Motif

Amyloids are highly ordered, cross-β-sheet-rich protein/peptide aggregates associated with both human diseases and native functions. Given the well established ability of amyloids in interacting with cell membranes, we hypothesize that amyloids can serve as universal cell-adhesive substrates. Here, we show that, similar to the extracellular matrix protein collagen, amyloids of various proteins/peptides support attachment and spreading of cells via robust stimulation of integrin expression and formation of integrin-based focal adhesions. Additionally, amyloid fibrils are also capable of immobilizing non-adherent red blood cells through charge-based interactions. Together, our results indicate that both active and passive mechanisms contribute to adhesion on amyloid fibrils. The present data may delineate the functional aspect of cell adhesion on amyloids by various organisms and its involvement in human diseases. Our results also raise the exciting possibility that cell adhesivity might be a generic property of amyloids.     

Uranyl tris nitrato as a luminescent probe for trace water detection in acetonitrile

Uranyl tris nitrato i.e. [UO₂(NO₃)₃]^– was formed by adding tetramethylammonium nitrate to uranyl nitrate in acetonitrile medium. The luminescence features of this complex in acetonitrile are very sensitive to water content, which could lead to the use of it as a luminescent probe for water present in acetonitrile. The luminescence intensity ratio of 507 to 467 nm peak of uranyl tris nitrato showed a linear response in the range 0–5% (v/v) water content in acetonitrile. The present method was applied for three synthetic samples of acetonitrile for water detection and the results obtained were compared using Karl Fischer titration. There was a good agreement in the values obtained by both the methods.     

臭虫击倒抗性基因突变检测及抗性测定

近20多年,臭虫（Cimex spp.）在世界范围内成为常见的卫生害虫,其防治主要采用化学防治,但很多种群发现击倒抗性（Knockdown resistance gene, kdr）基因突变的存在以及抗药性。监测kdr的发生频率以及不同种群对农药的抗性对臭虫有效防治很重要,但我国对臭虫种群的抗药性报道很少。本试验采用点滴法测定了1个温带臭虫Cimex lectularius野外种群对氯虫苯甲酰胺、呋虫胺、吡虫啉、噻虫嗪和高效氯氰菊酯等5种药剂的毒性及抗性水平,使用区分剂量快速鉴定抗性方法对2个温带臭虫和2个热带臭虫Cimex hemipterus种群对高效氯氰菊酯的抗性水平进行了检测,此外用PCR方法检测8个臭虫地理种群（1个温带臭虫实验室种群,1个温带臭虫野外种群和6个热带臭虫野外种群）174个个体的kdr突变频率。点滴法结果表明,5种杀虫剂对温带臭虫的毒性是吡虫啉和呋虫胺>噻虫嗪>氯虫苯甲酰胺和高效氯氰菊酯,测试的野外温带臭虫种群仅对噻虫嗪无明显抗性。热带臭虫2个野外种群对高效氯氰菊酯的抗性均远高于温带臭虫。在温带臭虫的实验室种群中未检测到突变,在野外种群中检测到了V419L和L925I突变,可分为2种基因型类型（A：无突变位点;B：同时有L925I和V419L）,而在热带臭虫的6个种群检测到M918I和L1014F突变,只有1种基因型类型,即M918I和L1014F双位点突变。温带臭虫1个野外种群及热带臭虫6个野外种群kdr突变的存在与臭虫对高效氯氰菊酯敏感密切关联。基于kdr基因突变检测结果推测我国臭虫种群广泛存在对拟除虫菊酯的抗性。     

Modelling of phytoplankton allelopathy with Monod–Haldane-type functional response—A mathematical study

In this paper, a three-tier model of phytoplankton, zooplankton and nutrient is considered and stability of different equilibrium points is analyzed along with Hopf-bifurcation around coexisting equilibrium point. Here, we have assumed toxication process as the guiding factor for bloom formation as well as its termination and this process is incorporated into our model by choosing the zooplankton grazing function as a Monod–Haldane function due to the phytoplankton toxicity. Extensive numerical simulations have been performed to validate the analytical findings and these simulation work reveal the chaotic oscillation exhibited by the model system for certain choice of the parameter values.     

Home ranges, movements, and activity of wolves (Canis lupus) in the Dalmatian part of Dinarids, Croatia

Home-range sizes, movements, and daily activity of wolves (Canis lupus L. 1758) were studied in Dalmatia, Croatia in 1998–2001. The total home ranges (100% MCP) of two packs were 160 km² and 141 km², mean=150.5 km². Core areas (50% kernel) were 26.2 km² and 3.3 km², respectively. Differences in core area sizes were influenced by human activity—hunting and sheep grazing. Compared with random locations, wolf locations were closer to the nearest water source (mean=937 m) and farther from houses (mean=653 m). Wolves were significantly more active during the night than during the day (activity indexes were 0.53 vs. 0.35), and night activity was higher during summer (0.58), and lower during winter (0.48). A correlation was found between distances traveled and activity index (r=0.58, p=0.003). Home range, seasonal variations in home-range size, habitat use, and activity of wolves in Dalmatia were oriented to make the compromise from danger of proximity to humans and also to benefit from human-related food sources.