Non-coding RNAs: the dark side of nuclear–mitochondrial communication

Mitochondria are critical hubs for the integration of several key metabolic processes implicated in cell growth and survival. They originated from bacterial ancestors through endosymbiosis, following the transfer of more than 90% of their endosymbiont genome to the host cell nucleus. Over time, a mutually beneficial symbiotic relationship has been established, which relies on continuous and elaborate signaling mechanisms between this life-essential organelle and its host. The ability of mitochondria to signal their functional state and trigger compensatory and adaptive cellular responses has long been recognized, but the underlying molecular mechanisms involved have remained poorly understood. Recent evidence indicates that non-coding RNAs (ncRNAs) may contribute to the synchronization of a series of essential cellular and mitochondrial biological processes, acting as “messengers” between the nucleus and the mitochondria. Here, we discuss the emerging putative roles of ncRNAs in various bidirectional signaling pathways established between the host cell and its mitochondria, and how the dysregulation of these pathways may lead to aging-related diseases, including cancer, and offer new promising therapeutic avenues.     

Is it really the “dark side” of herbal medicine?

正Aristolochic acids (AAs), previously rarely mentioned compounds, have been brought into the public eye several times since the beginning of this century; and currently, they have drawn even greater attention due to their association with liver cancer, as was recently reported by Ng et al.(Ng et al., 2017). The authors sequenced the whole exomes of 98patients with hepatocellular carcinomas (HCC) from Taiwan and reported that 78%of the cases carried the AAs mutational signature, A:TT:A transversion. Further examination of publicly available data from Chinese patients with HCC     

High-density lipoprotein: does it have a dark side?

There are proven pleiotropic anti-atherogenic actions of high-density lipoprotein (HDL). However, in systemic inflammation, HDL can have pro-inflammatory properties that may contribute to accelerated atherosclerosis, likely mediated by a change in the structure of HDL to pro-inflammatory HDL (PiHDL). Validation of the technically challenging assay for PiHDL, and confirmation of an association of PiHDL in multiple populations with known risk for atherosclerosis will eventually provide a useful biomarker. Identification of PiHDL in patients with rheumatic disease may help identify patients at risk of accelerated atherosclerosis, and focus our therapeutic interventions.     

Light for the dark side of plant life: —Planar optodes visualizing rhizosphere processes

Recent developments in the field of in vivo plant imaging have advanced the current state of the art to the point of near real-time visualization of water transport both through the soil matrix and the vascular system of plants. The application of these non-destructive methods holds great promise for addressing many of the unanswered questions related to plant hydraulics, in particular the below-ground processes at the soil-root interface. Warren et al. in this issue of Plant and Soil demonstrate the utility of neutron radiography and tomography in the study of hydraulic redistribution in the roots of Panicum virgatum and Zea mays in undisturbed soil. This new non-destructive imaging tool that can be used in pulse-chase experiments with D₂O adds to the growing number of visualization techniques available to plant scientists.     

The dark side of the “redundancy hypothesis” and ecosystem assessment

Intricacy of biotic interactions (predator-prey relationship, strength of food web links and other type of intra- and inter-specific relationships), as well as shifts in species functions in ecosystems, could affect the accuracy of predictions derived from the theory of redundancy of species, when applied to ecosystems assessment.This opinion paper is based on three main considerations: 1) some fundamental differences between ecological and engineering definition of “redundancy”, underlying the main concerns related to the use frameworks derived from economical or engineering disciplines, as the ecosystems services paradigm; 2) presence of empirical obstacles to establish whether two different species are fully or partially redundant. When species redundancy in a particular community is estimated using a matrix with species-specific functional traits, often forgetting potential biotic interactions not directly related to the trophic chains or neglecting the variability in strengths of the links connecting these species; and 3) recent evidence offered by studies that shed doubts on the validity of the ecological redundancy hypothesis.Finally, we claim that more attention must to be paid to intrinsic ecological aspects of ecosystem components (per se values rather than derived values), and a precautionary principle is necessary for decisions related to the assessment of ecosystems.     

Fifty years of entomological publications in the Revista de Biología Tropical

Over its fifty year history nearly twenty percent of the papers published in the Revista de Biología Tropical have been about insects and arachnids. In the 1950's papers on arthropods of medical importance were dominant, in the 1960's there was a poliferation of papers on bees, and in more recent years the subjects have become increasingly diverse. In terms of nationality of contributing authors, the journal appears to have become increasingly international in later years.     

Mast cells: the missing source of cardiac renin?

The renin-angiotensin system (RAS) acts to regulate blood volume and arterial pressure, and has direct effects on the heart. Renin, released by the kidney, circulates and acts-in the rate-limiting step of angiotensin II (Ang II) production-to convert angiotensinogen to inactive angiotensin I (Ang I). Ang II constricts vessels, leading to increased arterial pressure, among other effects. Components of the RAS have been found in a number of extra-renal tissues. Recent research indicates that mast cells in the heart may produce renin, creating a cardiac-specific RAS that acts locally to produce Ang II. These results, however, are not without controversy. Others have searched for sites of renin production and have found no other significant source that was physiologically important or that could not be completely ruled out as a possible contaminant. How important is mast cell-synthesized renin for direct cardiac-related effects?     

The first fossil spider cricket (Orthoptera: Gryllidae: Phalangopsinae): 20 million years of troglobiomorphosis or exaptation in the dark?

A new spider cricket (Orthoptera: Gryllidae: Phalangopsinae) is described from an adult female preserved in Early Miocene (Burdigalian) amber from the Dominican Republic. Araneagryllus dylani gen. et sp. nov. represents the first fossil record of Phalangopsinae, and is assigned to the tribe Luzarini, subtribe Amphiacustina stat. nov. A cladistic analysis of Amphiacustina places Araneagryllus gen. nov. within a clade comprising Arachnopsita, Leptopedetes, Longuripes, Mayagryllus, Nemoricantor, and Prolonguripes. This clade is the sister group to a clade comprising Amphiacusta, Cantrallia, and Noctivox. The results of this analysis suggest that: (1) the common ancestor of all Amphiacustina was epigean, and was likely to have been cavicolous and/or straminicolous; (2) strict troglobitism evolved twice within Amphiacustina, once in the lineage leading to Noctivox and again in the clade comprising Mayagryllus, Arachnopsita, Longuripes, and Prolonguripes; and (3) Prolonguripes is secondarily epigean, having reverted to life above ground. The occurrence of Araneagryllus gen. nov. in amber indicates that it was not troglobitic, but was instead more likely to have been straminicolous, living on the ground and foraging amongst leaf litter. Araneagryllus gen. nov. possesses a number of characters that are usually considered to be adaptive to a troglobitic life history, suggesting that many so‐called troglobiomorphies are not adaptations to life in caves, but are instead likely to have been exaptive. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 56–65.     

Circadian clocks: A cry in the dark?

Cryptochrome proteins are key components of the circadian systems of both Drosophila and mammals. In Drosophila, they appear to be responsible for the entrainment of the circadian clock by the light-dark cycle, while in mammals they perform an important role in rhythm generation itself.     

Phosphorylation switches specific for the cardiac isoform of myosin binding protein-C: a modulator of cardiac contraction?

Cardiac myosin binding protein-C (cardiac MyBP-C, cardiac C protein) belongs to a family of proteins implicated in both regulatory and structural functions of striated muscle. For the cardiac isoform, regulatory phosphorylation in vivo by cAMP-dependent protein kinase (PKA) upon adrenergic stimulation is linked to modulation of cardiac contraction. The sequence of human cardiac MyBP-C now reveals regulatory motifs specific for this isoform. Site-directed mutagenesis identifies a LAGGGRRIS loop in the N-terminal region of cardiac MyBP-C as the key substrate site for phosphorylation by both PKA and a calmodulin-dependent protein kinase associated with the native protein. Phosphorylation of two further sites by PKA is induced by phosphorylation of this isoform-specific site. This phosphorylation switch can be mimicked by aspartic acid instead of phosphoserine. Cardiac MyBP-C is therefore specifically equipped with sensors for adrenergic regulation of cardiac contraction, possibly implicating cardiac MyBP-C in cardiac disease. The gene coding for cardiac MyBP-C has been assigned to the chromosomal location 11p11.2 in humans, and is therefore in a region of physical linkage to subsets of familial hypertrophic cardiomyopathy (FHC). This makes cardiac MyBP-C a candidate gene for chromosome 11-associated FHC.