Capture of Essential Trace Elements and Phosphate Accumulation as a Basis for the Antimicrobial Activity of a New Ultramicrobacterium—Microbacterium lacticum Str. F2E

Microbial interactions play an important role in natural habitat. The long-term coevolution of various species leads to the adaptation of certain types of microorganisms as well as to the formation of a wide variety of interactions such as competitive, antagonistic, pathogenic and parasitic relationships. The aim of this work is a comprehensive study of a new ultramicrobacterium Microbacterium lacticum str. F2E, isolated from perennial oil sludge, which is characterized by high antimicrobial activity and a unique ultrastructural organization of the cell envelope, which includes globular surface ultrastructures with a high negative charge. A previously undescribed mechanism for the antagonistic action of the F2E strain against the prey bacterium is proposed. This mechanism is based on the ability to preferentially capture essential microelements, in which charge interactions and the property of phosphate accumulation may play a significant role. The revealed type of intermicrobial interaction can probably be attributed to the non-contact type antagonistic action in the absence of any diffuse factor secreted by the antagonistic bacteria.

Survey of Antagonistic Action and the Mechanism of these Actions that Terpens, Phenols and their Derivatives Possess Against Different Pathogenic Agents

Folk medicine or herbal treatment has been used for centuries by different ancient civilizations against various ailment agents, herbal medicine has been dragged attention by researchers in different medical branches focusing on therapeutically characteristic features of each plant against different pathogenic agents responsible for most devastating and terrifying diseases, in addition to thorough investigation for the phytochemical compounds in each plant responsible for its potent against pathogens. Thus, this study highlights on two major groups of secondary metabolic compounds: terpens, phenols and their derivatives as antimicrobial agents against different bacterial and fungal strains especially drug resistant bacteria which responsible for the infectivity of treatments of most infectious diseases. Furthermore, mechanisms of actions of these secondary metabolites are reviewed as the causative factors responsible for the antimicrobial activity of plants and the promising results which have been achieved in multiply these activities by making combination between these natural products and chemical drugs.

Substrate recognition determinants of human eIF2α phosphatases

Phosphorylation of the translation initiation factor eIF2α is a rapid and vital cellular defence against many forms of stress. In mammals, the levels of eIF2α phosphorylation are set through the antagonistic action of four protein kinases and two heterodimeric protein phosphatases. The phosphatases are composed of the catalytic subunit PP1 and one of two related non-catalytic subunits, PPP1R15A or PPP1R15B (R15A or R15B). Attempts at reconstituting recombinant holophosphatases have generated two models, one proposing that substrate recruitment requires the addition of actin, whilst the second proposes that this function is encoded by R15s. The biological relevance of actin in substrate recruitment has not been evaluated. Here we generated a series of truncation mutants and tested their properties in mammalian cells. We show that substrate recruitment is encoded by an evolutionary conserved region in R15s, R15A325-554 and R15B340-639. Actin does not bind these regions establishing that it is not required for substrate recruitment. Activity assays in cells showed that R15A325-674 and R15B340-713, encompassing the substrate-binding region and the PP1 binding-region, exhibit wild-type activity. This study identifies essential regions of R15s and demonstrates they function as substrate receptors. This work will guide the design of future structural studies with biological significance.

Mode of antifungal action of a perspective bacterial strain-producer of microbiopreparations 11-3 Bacillus sp. on a pathogen of fusariose on oil flax Fusarium oxysporum var. orthoceras

The search of perspective strains-producers for microbiopreparations creation protecting oil flax of fusariose pathogen have been conducting in the laboratory of Biological methods of the V.S. Pustovoit All-Russian Research Institute of Oil Crops in recent years (2018–2020). These researches contemplate studying of a mode of antagonistic action of the promising strains-producers of microbiopreparations on a disease pathogen. There is presented an interaction between the promising strain-antagonist 11-3 Bacillus sp. selected by a stage screening and the pathogen Fusarium oxysporum var. orthoceras. Modifications of pathogen mycelium were stated at the second day of joint incubation, even before intergrowth with antagonist’s colony. They were as following: formation of spheroplasts (ball-shaped swellings of apical parts of hyphae), their explosion and lining appearance, and compression and discoloration of the separate mycelium plots. After intergrowth of pathogen and antagonist we noted the stronger compression, prolification, thickening and destruction of substrate airy mycelium and chlamidospores of fusariose pathogen. Pathogen’s mycelium at joint cultivation with the bacillary strain-antagonist was totally destructed at the eighth-tenth day.

Genomic imprinting drives eusociality

The origin of eusociality, altruistically foregoing personal reproduction to help others, has been a long-standing paradox ever since Darwin. Most eusocial insects and rodents likely evolved from subsocial precursors, in which older offspring “helpers” contribute to the development of younger siblings without a permanent sterile caste. The driving mechanism for the transition from subsociality (with helpers) to eusociality (with lifelong sterile workers) remains an enigma because individuals in subsocial groups are subject to direct natural selection rather than kin selection. Our genomic imprinting theory demonstrates that natural selection generates eusociality in subsocial groups when parental reproductive capacity is linked to a delay in the sexual development of offspring due to sex-antagonistic action of transgenerational epigenetic marks. Focusing on termites, our theory provides the missing evolutionary link to explain the evolution of eusociality from their subsocial wood-feeding cockroach ancestors, and provides a novel framework for understanding the origin of eusociality.

Germline sexual fate is determined by the antagonistic action of dmrt1 and foxl3/foxl2 in tilapia

Germline sexual fate has long been believed to be determined by the somatic environment, but this idea is challenged by recent studies of foxl3 mutants in medaka. Here we demonstrate that the sexual fate of tilapia germline is determined by the antagonistic interaction of dmrt1 and foxl3, which are transcriptionally repressed in male and female germ cells, respectively. Loss of dmrt1 rescued the germ cell sex reversal in foxl3Δ7/Δ7 XX fish, and loss of foxl3 partially rescued germ cell sex reversal but not somatic cell fate in dmrt1Δ5/Δ5 XY fish. Interestingly, germ cells lost sexual plasticity in dmrt1Δ5/Δ5 XY and foxl3Δ7/Δ7 XX single mutants, as aromatase inhibitor and estrogen treatment failed to rescue the respective phenotypes. However, recovery of germ cell sexual plasticity was observed in dmrt1/foxl3 double mutants. Importantly, mutation of somatic cell specific foxl2 resulted in testicular development in foxl3Δ7/Δ7 or dmrt1Δ5/Δ5 mutants. Our findings demonstrate that sexual plasticity of germ cells relies on the presence of both dmrt1 and foxl3. The existence of dmrt1 and foxl3 allows environmental factors to influence the sex fate decision in vertebrates.

Type IV pilus retraction enables sustained bacteremia and plays a key role in the outcome of meningococcal sepsis in a humanized mouse model

Neisseria meningitidis (the meningococcus) remains a major cause of bacterial meningitis and fatal sepsis. This commensal bacterium of the human nasopharynx can cause invasive diseases when it leaves its niche and reaches the bloodstream. Blood-borne meningococci have the ability to adhere to human endothelial cells and rapidly colonize microvessels. This crucial step enables dissemination into tissues and promotes deregulated inflammation and coagulation, leading to extensive necrotic purpura in the most severe cases. Adhesion to blood vessels relies on type IV pili (TFP). These long filamentous structures are highly dynamic as they can rapidly elongate and retract by the antagonistic action of two ATPases, PilF and PilT. However, the consequences of TFP dynamics on the pathophysiology and the outcome of meningococcal sepsis in vivo have been poorly studied. Here, we show that human graft microvessels are replicative niches for meningococci, that seed the bloodstream and promote sustained bacteremia and lethality in a humanized mouse model. Intriguingly, although pilus-retraction deficient N. meningitidis strain (ΔpilT) efficiently colonizes human graft tissue, this mutant did not promote sustained bacteremia nor induce mouse lethality. This effect was not due to a decreased inflammatory response, nor defects in bacterial clearance by the innate immune system. Rather, TFP-retraction was necessary to promote the release of TFP-dependent contacts between bacteria and, in turn, the detachment from colonized microvessels. The resulting sustained bacteremia was directly correlated with lethality. Altogether, these results demonstrate that pilus retraction plays a key role in the occurrence and outcome of meningococcal sepsis by supporting sustained bacteremia. These findings open new perspectives on the role of circulating bacteria in the pathological alterations leading to lethal sepsis.

In vitro antagonistic inhibitory effects of palm seed crude oils and their main constituent, lauric acid, with oxacillin in Staphylococcus aureus

Infections caused by Staphylococcus aureus are a serious global threat, and with the emergence of antibiotic resistance, even more difficult to treat. One of the possible complications in antistaphylococcal therapy represents negative interactions of antibiotics with food. In this study, the in vitro interaction between oxacillin and crude palm seed oil from Astrocaryum vulgare, Cocos nucifera, and Elaeis guineensis against nine strains of S. aureus was determined using the checkerboard method. Lauric acid was identified as a major constituent of all tested oils by gas chromatography. The results showed strong concentration dependent antagonistic interactions between palm oils and oxacillin with values of fractional inhibitory concentrations indices ranging from 4.02 to 8.56 at concentrations equal or higher than 1024 µg/mL of the tested oils. Similarly, lauric acid in combination with oxacillin produced antagonistic action with fractional inhibitory concentration indices ranging from 4.01 to 4.28 at 1024 µg/mL. These findings suggest that interference between oxacillin and palm oils and their constituents can negatively affect the treatment of staphylococcal infections in humans and other animals.