Antimicrobial and antioxidative activity of extracts and essential oils of Myrtus communis L.

Since synthetic antimicrobial agents and food additives can cause a number of adverse effects, there is a growing interest from consumers in ingredients from natural sources. Medicinal plants, such as Myrtus communis L. are a source of new compounds which can be used in both the food industry and for medical purposes, primarily as antimicrobial agents. In this review, the characteristics of myrtle essential oils and extracts are summarized, with particular attention to their chemical composition, biological activities and potential applications.     

Is drug release necessary for antimicrobial activity of siderophore-drug conjugates? Syntheses and biological studies of the naturally occurring salmycin “Trojan Horse” antibiotics and synthetic desferridanoxamine-antibiotic conjugates

The recent rise in drug resistance found amongst community acquired infections has sparked renewed interest in developing antimicrobial agents that target resistant organisms and limit the natural selection of immune variants. Recent discoveries have shown that iron uptake systems in bacteria and fungi are suitable targets for developing such therapeutic agents. The use of siderophore-drug conjugates as “Trojan Horse” drug delivery agents has attracted particular interest in this area. This review will discuss efforts in our research group to study the salmycin class of “Trojan Horse” antibiotics. Inspired by the natural design of the salmycins, a series of desferridanoxamine-antibiotic conjugates were synthesized and tested in microbial growth inhibition assays. The results of these studies will be related to understanding the role of drug release in siderophore-mediated drug delivery with implications for future siderophore-drug conjugate design.     

The Minimal Complexity of Adapting Agents Increases with Fitness

What is the relationship between the complexity and the fitness of evolved organisms, whether natural or artificial? It has been asserted, primarily based on empirical data, that the complexity of plants and animals increases as their fitness within a particular environment increases via evolution by natural selection. We simulate the evolution of the brains of simple organisms living in a planar maze that they have to traverse as rapidly as possible. Their connectome evolves over 10,000s of generations. We evaluate their circuit complexity, using four information-theoretical measures, including one that emphasizes the extent to which any network is an irreducible entity. We find that their minimal complexity increases with their fitness.     

Application of antimicrobial peptides in agriculture and food industry

Antimicrobial peptides have captured the attention of researchers in recent years because of their efficiency in fighting against pathogens. These peptides are found in nature and have been isolated from a wide range of organisms. Furthermore, analogs or synthetic derivatives have successfully been developed on the basis of natural peptide patterns. Long use of pesticides and antibiotics has led to development of resistance among pathogens and other pests as well as increase of environmental and health risks. Antimicrobial peptides are under consideration as new substitutes for conventional pesticides and antibiotics. Many plants and animals have been manipulated with antimicrobial peptide-encoding genes and several pesticides and drugs have been produced based on these peptides. Such strategies and products may still have a long way to go before being confirmed by regulatory bodies and others need to surmount technical problems before being accepted as applicable ones. In spite of these facts, several cases of successful use of antimicrobial peptides in agriculture and food industry indicate a promising future for extensive application of these peptides. In this review, we consider the developing field of antimicrobial peptide applications in various agricultural activities.     

Antimicrobial peptides: Modes of mechanism,modulation of defense responses

Complicated schemes of classical breeding and their drawbacks, environmental risks imposed by agrochemicals, decrease of arable land, and coincident escalating damages of pests and pathogens have accentuated the necessity for highly efficient measures to improve crop protection. During co-evolution of host-microbe interactions, antimicrobial peptides (AMPs) have exhibited a brilliant history in protecting host organisms against devastation by invading pathogens. Since the 1980s, a plethora of AMPs has been isolated from and characterized in different organisms. Nevertheless the AMPs expressed in plants render them more resistant to diverse pathogens, a more orchestrated approach based on knowledge of their mechanisms of action and cellular targets, structural toxic principle, and possible impact on immune system of corresponding transgenic plants will considerably improve crop protection strategies against harmful plant diseases. This review outlines the current knowledge on different modes of action of AMPs and then argues the waves of AMPs'' ectopic expression on transgenic plants'' immune system.Key words: antimicrobial peptides, durable resistance, gene technology, immune system, metchnikowin, sustainable agriculture     

Antibiotic resistance and resistance mechanisms in Campylobacter jejuni and Campylobacter coli

Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world and infections with these organisms occur more frequently than do infections due to Salmonella species, Shigella species, or Escherichia coli 0157:H7. The incidence of human Campylobacter infections has increased markedly in both developed and developing countries worldwide and, more significantly, so has the rapid emergence of antibiotic-resistant Campylobacter strains, with evidence suggesting that the use of antibiotics, in particular the fluoroquinolones, as growth promoters in food animals and the veterinary industry is accelerating this trend. In this minireview, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter spp are discussed.     

Natural products and their semi-synthetic derivatives against antimicrobial-resistant human pathogenic bacteria and fungi

Human infectious diseases caused by various microbial pathogens, in general, impact a large population of individuals every year. These microbial diseases that spread quickly remain to be a big issue in various health-related domains and to withstand the negative drug impacts, the antimicrobial-resistant pathogenic microbial organisms (pathogenic bacteria and pathogenic fungi) have developed a variety of resistance processes against many antimicrobial drug classes. During the COVID-19 outbreak, there seems to be an upsurge in drug and multidrug resistant-associated pathogenic microbial species. The preponderance of existing antimicrobials isn’t completely effective, which limits their application in clinical settings. Several naturally occurring chemicals produced from bacteria, plants, animals, marine species, and other sources are now being studied for antimicrobial characteristics. These natural antimicrobial compounds extracted from different sources have been demonstrated to be effective against a variety of diseases, although plants remain the most abundant source. These compounds have shown promise in reducing the microbial diseases linked to the development of drug tolerance and resistance. This paper offers a detailed review of some of the most vital and promising natural compounds and their derivatives against various human infectious microbial organisms. The inhibitory action of different natural antimicrobial compounds, and their possible mechanism of antimicrobial action against a range of pathogenic fungal and bacterial organisms, is provided. The review will be useful in refining current antimicrobial (antifungal and antibacterial) medicines as well as establishing new treatment strategies to tackle the rising number of human bacterial and fungal-associated infections.     

Current status of defensins and their role in innate and adaptive immunity

Naturally occurring antimicrobial cationic polypeptides play a major role in innate and adaptive immunity. These polypeptides are found to be either linear and unstructured or structured through disulfide bonds. Among the structured antimicrobial polypeptides, defensins comprise a family of cysteine-rich cationic polypeptides that contribute significantly to host defense against the invasion of microorganisms in animals, humans, insects and plants. Their wide-spread occurrence in various tissues of these diverse organisms, and their importance in innate and adaptive immunity have led to their identification, isolation and characterization. A large volume of literature is available on defensins' occurrence, structural characterization, gene expression and regulation under normal and pathological conditions. Much has also been published regarding their antimicrobial, antiviral and chemoattractive properties, and their molecular and cellular interactions. In this review, we describe the current status of our knowledge of defensins with respect to their molecular, cellular and structural biology, their role in host defense, future research paradigms and the possibility of their utilization as a new class of non-toxic antimicrobial agents and immuno-modulators.     

Molecular strategies for overcoming antibiotic resistance in bacteria

Overuse of antibiotics in humans and livestock has led to the rapid evolution of bacteria that are resistant to multiple drugs such that even vancomycin, the drug of last resort, is no longer effective against some strains. Apart from the discovery and exploitation of the natural peptide antimicrobial agents that form part of the innate immune systems of plants and animals, there have been few new antibiotics developed in recent years. Here we review strategies designed to exploit recent advances in molecular biology, including recombinant DNA technology, molecular modelling and genomics to develop new antibacterial agents that overcome antibiotic resistance.     

芳香植物精油的抗菌性及在动物生产中的应用

芳香植物精油为具特征性气味的挥发性油状液体, 是从芳香植物中提取的一种重要次生代谢物质。芳香植物精油的抗菌活性由其化学成分和浓度决定, 其中酚类、含氧萜类和萜烯类在抗菌方面表现出较强的活性。芳香植物精油的抗菌机制主要涉及脂肪酸外膜的改变、细胞质膜的损坏、质子动力的消耗、代谢物及离子泄露。在畜牧业生产体系中, 抗生素的无序使用不仅可能引发“超级细菌”的产生, 其残留亦会造成畜产品不安全和环境污染。芳香植物精油作为一种天然植物抗菌剂, 毒性较低且无残留, 作为饲料添加剂可用于维持动物机体的健康, 有望成为重要的抗生素替代品。该文阐述了芳香植物精油的活性成分、抗菌作用机制及其在动物生产中的应用, 为抗菌机理研究和新技术开发利用提供了理论依据。     

A reverse chemical ecology approach to explore wood natural durability

The natural durability of wood species, defined as their inherent resistance to wood-destroying agents, is a complex phenomenon depending on many biotic and abiotic factors. Besides the presence of recalcitrant polymers, the presence of compounds with antimicrobial properties is known to be important to explain wood durability. Based on the advancement in our understanding of fungal detoxification systems, a reverse chemical ecology approach was proposed to explore wood natural durability using fungal glutathione transferases. A set of six glutathione transferases from the white-rot Trametes versicolor were used as targets to test wood extracts from seventeen French Guiana neotropical species. Fluorescent thermal shift assays quantified interactions between fungal glutathione transferases and these extracts. From these data, a model combining this approach and wood density significantly predicts the wood natural durability of the species tested previously using long-term soil bed tests. Overall, our findings confirm that detoxification systems could be used to explore the chemical environment encountered by wood-decaying fungi and also wood natural durability.     

Garlic and onions: their effect on eicosanoid metabolism and its clinical relevance

Garlic (Allium sativum) and onion (Allium cepa) are among the oldest of all cultivated plants. Additionally, both plants have been used as medicinal agents for thousands of years. Both garlic and onion have been shown to have applications as antimicrobial, antithrombotic, antitumor, hypolipidaemic, antiarthritic and hypoglycemic agents. In recent years, extensive research has focussed on the beneficial and medicinal properties of garlic and onions. In particular, the use of these agents in the treatment and prevention of cardiovascular disease and cancer is an area of considerable investigation and interest.     

The chemistry and applications of antimicrobial polymers: a state-of-the-art review

Microbial infection remains one of the most serious complications in several areas, particularly in medical devices, drugs, health care and hygienic applications, water purification systems, hospital and dental surgery equipment, textiles, food packaging, and food storage. Antimicrobials gain interest from both academic research and industry due to their potential to provide quality and safety benefits to many materials. However, low molecular weight antimicrobial agents suffer from many disadvantages, such as toxicity to the environment and short-term antimicrobial ability. To overcome problems associated with the low molecular weight antimicrobial agents, antimicrobial functional groups can be introduced into polymer molecules. The use of antimicrobial polymers offers promise for enhancing the efficacy of some existing antimicrobial agents and minimizing the environmental problems accompanying conventional antimicrobial agents by reducing the residual toxicity of the agents, increasing their efficiency and selectivity, and prolonging the lifetime of the antimicrobial agents. Research concerning the development of antimicrobial polymers represents a great a challenge for both the academic world and industry. This article reviews the state of the art of antimicrobial polymers primarily since the last comprehensive review by one of the authors in 1996. In particular, it discusses the requirements of antimicrobial polymers, factors affecting the antimicrobial activities, methods of synthesizing antimicrobial polymers, major fields of applications, and future and perspectives in the field of antimicrobial polymers.     

Microbiological interactions with cold plasma

There is a diverse range of microbiological challenges facing the food, healthcare and clinical sectors. The increasing and pervasive resistance to broad‐spectrum antibiotics and health‐related concerns with many biocidal agents drives research for novel and complementary antimicrobial approaches. Biofilms display increased mechanical and antimicrobial stability and are the subject of extensive research. Cold plasmas (CP) have rapidly evolved as a technology for microbial decontamination, wound healing and cancer treatment, owing to the chemical and bio‐active radicals generated known collectively as reactive oxygen and nitrogen species. This review outlines the basics of CP technology and discusses the interactions with a range of microbiological targets. Advances in mechanistic insights are presented and applications to food and clinical issues are discussed. The possibility of tailoring CP to control specific microbiological challenges is apparent. This review focuses on microbiological issues in relation to food‐ and healthcare‐associated human infections, the role of CP in their elimination and the current status of plasma mechanisms of action.     

Cytosolic metal handling in plants: determinants for zinc specificity in metal transporters and metallothioneins

The handling of trace elements by plants plays a fundamental role in food security and safety. Therefore, there is a need to understand the mechanisms that govern metal ion trafficking in plants. The past decade has seen an immense expansion of knowledge on metal ion transport in a variety of biological systems including plants, but as for other organisms, the mechanisms for intracellular zinc trafficking remain enigmatic. The current report highlights recent advances in understanding zinc transport in plants and in identifying the biomolecules involved in this process. A particular focus is put on pinpointing determinants for zinc specificity, and we also highlight areas in need of development. Reliable experimental speciation data are a first step towards systems biology approaches to mineral nutrition in plants-but there is also a need to understand molecular details. One intriguing question, in particular in the context of predicting protein function, concerns how discrimination between metal ions in a biological system functions.     

Genome edited animals: Learning from GM crops?

Genome editing of livestock is poised to become commercial reality, yet questions remain as to appropriate regulation, potential impact on the industry sector and public acceptability of products. This paper looks at how genome editing of livestock has attempted to learn some of the lessons from commercialisation of GM crops, and takes a systemic approach to explore some of the complexity and ambiguity in incorporating genome edited animals in a food production system. Current applications of genome editing are considered, viewed from the perspective of past technological applications. The question of what is genome editing, and can it be considered natural is examined. The implications of regulation on development of different sectors of livestock production systems are studied, with a particular focus on the veterinary sector. From an EU perspective, regulation of genome edited animals, although not necessarily the same as for GM crops, is advocated from a number of different perspectives. This paper aims to open up new avenues of research on genome edited animals, extending from the current primary focus on science and regulation, to engage with a wider-range of food system actors.     

Knowledge-based vision and simple visual machines.

The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the ''knowledge'' in knowledge-based vision or form the ''models'' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the knowledge-based vision approach in the understanding of evolved systems (machines or animals) may well lead to theories and models that are internally consistent, computationally plausible, and entirely wrong.     

Natural occurrence of Bacillus thuringiensis and Bacillus cereus in eukaryotic organisms: a case for symbiosis

Bacillus thuringiensis and Bacillus cereus, two members of the Bacillus cereus sensu lato group, are most noted for their virulence in, respectively, arthropods and mammals including humans. Because of their pathogenicity to insects in particular, and their narrow host range, strains of B. thuringiensis have been utilised successfully as biocontrol agents of insect pests. Whereas B. cereus is not an established entomopathogen, certain strains of this species are well known to be etiological agents of gastrointestinal and emetic syndromes in humans. While much is known about the taxonomic properties and molecular basis for virulence of B. thuringiensis and B. cereus, comparatively less is known about their ecology in natural environments. Thus, there are limited data regarding their resilience, i.e. recycling of vegetative and sporulated phases of growth in soil, ecolgical niches including symbiotic interactions with other organisms, and the impact on ecosystems in which they proliferate. Nevertheless, based on recent data, a picture is beginning to emerge that B. thuringiensis and B. cereus are capable of establishing mutual and commensal relationships with both animals and plants. In this regard, these bacilli can proliferate in the digestive tracts of animals, where upon defecation they form dormant spores in the soil, and to a lesser extent on the phylloplane and rhizospheres of plants. Altogether, current evidence strongly suggests that B. thuringiensis and B. cereus are capable of completing their life cycles and recycling through various reservoirs, including animals, plants, and soil. This review focuses on the current knowledge pertaining to the ecologic interactions between B. thuringiensis and B. cereus and eukaryotic hosts, with special emphasis on symbiosis.     

On the thermodynamics of multilevel evolution

Biodiversity is hierarchically structured both phylogenetically and functionally. Phylogenetic hierarchy is understood as a product of branching organic evolution as described by Darwin. Ecosystem biologists understand some aspects of functional hierarchy, such as food web architecture, as a product of evolutionary ecology; but functional hierarchy extends to much lower scales of organization than those studied by ecologists. We argue that the more general use of the term “evolution” employed by physicists and applied to non-living systems connects directly to the narrow biological meaning. Physical evolution is best understood as a thermodynamic phenomenon, and this perspective comfortably includes all of biological evolution. We suggest four dynamical factors that build on each other in a hierarchical fashion and set the stage for the Darwinian evolution of biological systems: (1) the entropic erosion of structure; (2) the construction of dissipative systems; (3) the reproduction of growing systems and (4) the historical memory accrued to populations of reproductive agents by the acquisition of hereditary mechanisms. A particular level of evolution can underpin the emergence of higher levels, but evolutionary processes persist at each level in the hierarchy. We also argue that particular evolutionary processes can occur at any level of the hierarchy where they are not obstructed by material constraints. This theoretical framework provides an extensive basis for understanding natural selection as a multilevel process. The extensive literature on thermodynamics in turn provides an important advantage to this perspective on the evolution of higher levels of organization, such as the evolution of altruism that can accompany the emergence of social organization.     

Effect of urbanization on daily behavior and seasonal functions in vertebrates

Abstract

Most of the organisms are seasonal and live in a periodic environment and rely on external cues to optimally time their annual life history stages. The most predictable environmental cue which organisms use to time reproduction is the photoperiod, but food, temperature, and humidity may play role as a crucial factors. Urbanization is greatly increasing phenomenon and leads to change in landscape and habitat destruction for wildlife and brings extra hours of light at night (LAN), altering the natural signal of light and darkness, hence the temperature and availability of food. This artificial LAN has been implemented to affect behavior, endocrinology, and reproductive physiology and to advance seasonal reproduction in birds. Here, we review the literature available on the effects of urbanization on diverse processes of organisms with particular emphasis on avian system. We consider further research with long-term data-sets on phenological and physiological parameters from diverse group of organisms and diverse habitat is essential for better understanding of impact of global climate change on the biodiversity.