Biology

10 pages, 2596 KiB

Open AccessArticle

Oncostatin M Mediates Adipocyte Expression and Secretion of Stromal-Derived Factor 1

by Hardy Hang, Jennifer L. Bailey and Carrie M. Elks

Biology 2019, 8(1), 19; https://doi.org/10.3390/biology8010019 - 23 Mar 2019

Cited by 5 | Viewed by 3833

Adipose tissue homeostasis depends on interactions between stromal cells, adipocytes, and the cytokines and chemokines they produce. The gp130 cytokine, oncostatin M (OSM), plays a role in adipose tissue homeostasis. Mice, lacking the OSM receptor (OSMR) in adipocytes (Osmr^FKO mice), exhibit [...] Read more.

Adipose tissue homeostasis depends on interactions between stromal cells, adipocytes, and the cytokines and chemokines they produce. The gp130 cytokine, oncostatin M (OSM), plays a role in adipose tissue homeostasis. Mice, lacking the OSM receptor (OSMR) in adipocytes (Osmr^FKO mice), exhibit derangements in adipose tissue, insulin sensitivity, and immune cell balance. Here, we describe a possible role for the chemokine stromal-derived factor 1 (SDF-1) in these alterations. We treated 3T3-L1 adipocytes with OSM and observed a suppression of SDF-1 gene expression and protein secretion, an effect which was partially blunted by OSMR knockdown. However, Osmr^FKO mice also exhibited decreased SDF-1 gene and protein expression in adipose tissue. These contrasting results suggest that the loss of adipocyte OSM–OSMR signaling in vivo may be indirectly affecting adipokine production and secretion by altering OSM target genes to ultimately decrease SDF-1 expression in the Osmr^FKO mouse. We conclude that adipocyte OSM–OSMR signaling plays a role in adipose tissue SDF-1 production and may mitigate its effects on adipose tissue homeostasis. Full article

(This article belongs to the Special Issue New Players in Adipocyte Biology)

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15 pages, 1048 KiB

Open AccessReview

Telling the Time with a Broken Clock: Quantifying Circadian Disruption in Animal Models

by Laurence A. Brown, Angus S. Fisk, Carina A. Pothecary and Stuart N. Peirson

Biology 2019, 8(1), 18; https://doi.org/10.3390/biology8010018 - 21 Mar 2019

Cited by 21 | Viewed by 7551

Abstract

Circadian rhythms are approximately 24 h cycles in physiology and behaviour that enable organisms to anticipate predictable rhythmic changes in their environment. These rhythms are a hallmark of normal healthy physiology, and disruption of circadian rhythms has implications for cognitive, metabolic, cardiovascular and [...] Read more.

Circadian rhythms are approximately 24 h cycles in physiology and behaviour that enable organisms to anticipate predictable rhythmic changes in their environment. These rhythms are a hallmark of normal healthy physiology, and disruption of circadian rhythms has implications for cognitive, metabolic, cardiovascular and immune function. Circadian disruption is of increasing concern, and may occur as a result of the pressures of our modern 24/7 society—including artificial light exposure, shift-work and jet-lag. In addition, circadian disruption is a common comorbidity in many different conditions, ranging from aging to neurological disorders. A key feature of circadian disruption is the breakdown of robust, reproducible rhythms with increasing fragmentation between activity and rest. Circadian researchers have developed a range of methods for estimating the period of time series, typically based upon periodogram analysis. However, the methods used to quantify circadian disruption across the literature are not consistent. Here we describe a range of different measures that have been used to measure circadian disruption, with a particular focus on laboratory rodent data. These methods include periodogram power, variability in activity onset, light phase activity, activity bouts, interdaily stability, intradaily variability and relative amplitude. The strengths and limitations of these methods are described, as well as their normal ranges and interrelationships. Whilst there is an increasing appreciation of circadian disruption as both a risk to health and a potential therapeutic target, greater consistency in the quantification of disrupted rhythms is needed. Full article

(This article belongs to the Special Issue Biological Clocks)

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16 pages, 2466 KiB

Open AccessReview

Circadian Clocks in Fish—What Have We Learned so far?

by Inga A. Frøland Steindal and David Whitmore

Biology 2019, 8(1), 17; https://doi.org/10.3390/biology8010017 - 19 Mar 2019

Cited by 70 | Viewed by 7901

Abstract

Zebrafish represent the one alternative vertebrate, genetic model system to mice that can be easily manipulated in a laboratory setting. With the teleost Medaka (Oryzias latipes), which now has a significant following, and over 30,000 other fish species worldwide, there is [...] Read more.

Zebrafish represent the one alternative vertebrate, genetic model system to mice that can be easily manipulated in a laboratory setting. With the teleost Medaka (Oryzias latipes), which now has a significant following, and over 30,000 other fish species worldwide, there is great potential to study the biology of environmental adaptation using teleosts. Zebrafish are primarily used for research on developmental biology, for obvious reasons. However, fish in general have also contributed to our understanding of circadian clock biology in the broadest sense. In this review, we will discuss selected areas where this contribution seems most unique. This will include a discussion of the issue of central versus peripheral clocks, in which zebrafish played an early role; the global nature of light sensitivity; and the critical role played by light in regulating cell biology. In addition, we also discuss the importance of the clock in controlling the timing of fundamental aspects of cell biology, such as the temporal control of the cell cycle. Many of these findings are applicable to the majority of vertebrate species. However, some reflect the unique manner in which “fish” can solve biological problems, in an evolutionary context. Genome duplication events simply mean that many fish species have more gene copies to “throw at a problem”, and evolution seems to have taken advantage of this “gene abundance”. How this relates to their poor cousins, the mammals, remains to be seen. Full article

(This article belongs to the Special Issue Biological Clocks)

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16 pages, 281 KiB

Open AccessReview

Targeting White Adipose Tissue with Exercise or Bariatric Surgery as Therapeutic Strategies in Obesity

by Flávia Giolo De Carvalho and Lauren M. Sparks

Biology 2019, 8(1), 16; https://doi.org/10.3390/biology8010016 - 15 Mar 2019

Cited by 19 | Viewed by 5469

Abstract

Adipose tissue is critical to whole-body energy metabolism and has become recognized as a bona fide endocrine organ rather than an inert lipid reservoir. As such, adipose tissue is dynamic in its ability to secrete cytokines, free fatty acids, lipokines, hormones and other [...] Read more.

Adipose tissue is critical to whole-body energy metabolism and has become recognized as a bona fide endocrine organ rather than an inert lipid reservoir. As such, adipose tissue is dynamic in its ability to secrete cytokines, free fatty acids, lipokines, hormones and other factors in response to changes in environmental stimuli such as feeding, fasting and exercise. While excess adipose tissue, as in the case of obesity, is associated with metabolic complications, mass itself is not the only culprit in obesity-driven metabolic abnormalities, highlighting the importance of healthy and metabolically adaptable adipose tissue. In this review, we discuss the fundamental cellular processes of adipose tissue that become perturbed in obesity and the impact of exercise on these processes. While both endurance and resistance exercise can promote positive physiological adaptations in adipose tissue, endurance exercise has a more documented role in remodeling adipocytes, increasing adipokine secretion and fatty acid mobilization and oxidation during post-exercise compared with resistance exercise. Exercise is considered a viable therapeutic strategy for the treatment of obesity to optimize body composition, in particular as an adjuvant therapy to bariatric surgery; however, there is a gap in knowledge of the molecular underpinnings of these exercise-induced adaptations, which could provide more insight and opportunity for precision-based treatment strategies. Full article

(This article belongs to the Special Issue New Players in Adipocyte Biology)

20 pages, 3326 KiB

Open AccessReview

Episodic Ultradian Events—Ultradian Rhythms

by Grace H. Goh, Shane K. Maloney, Peter J. Mark and Dominique Blache

Biology 2019, 8(1), 15; https://doi.org/10.3390/biology8010015 - 14 Mar 2019

Cited by 47 | Viewed by 8068

Abstract

In the fast lane of chronobiology, ultradian events are short-term rhythms that have been observed since the beginning of modern biology and were quantified about a century ago. They are ubiquitous in all biological systems and found in all organisms, from unicellular organisms [...] Read more.

In the fast lane of chronobiology, ultradian events are short-term rhythms that have been observed since the beginning of modern biology and were quantified about a century ago. They are ubiquitous in all biological systems and found in all organisms, from unicellular organisms to mammals, and from single cells to complex biological functions in multicellular animals. Since these events are aperiodic and last for a few minutes to a few hours, they are better classified as episodic ultradian events (EUEs). Their origin is unclear. However, they could have a molecular basis and could be controlled by hormonal inputs—in vertebrates, they originate from the activity of the central nervous system. EUEs are receiving increasing attention but their aperiodic nature requires specific sampling and analytic tools. While longer scale rhythms are adaptations to predictable changes in the environment, in theory, EUEs could contribute to adaptation by preparing organisms and biological functions for unpredictability. Full article

(This article belongs to the Special Issue Biological Clocks)

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17 pages, 1411 KiB

Open AccessReview

The Plant Circadian Oscillator

by C. Robertson McClung

Biology 2019, 8(1), 14; https://doi.org/10.3390/biology8010014 - 12 Mar 2019

Cited by 95 | Viewed by 10638

Abstract

It has been nearly 300 years since the first scientific demonstration of a self-sustaining circadian clock in plants. It has become clear that plants are richly rhythmic, and many aspects of plant biology, including photosynthetic light harvesting and carbon assimilation, resistance to abiotic [...] Read more.

It has been nearly 300 years since the first scientific demonstration of a self-sustaining circadian clock in plants. It has become clear that plants are richly rhythmic, and many aspects of plant biology, including photosynthetic light harvesting and carbon assimilation, resistance to abiotic stresses, pathogens, and pests, photoperiodic flower induction, petal movement, and floral fragrance emission, exhibit circadian rhythmicity in one or more plant species. Much experimental effort, primarily, but not exclusively in Arabidopsis thaliana, has been expended to characterize and understand the plant circadian oscillator, which has been revealed to be a highly complex network of interlocked transcriptional feedback loops. In addition, the plant circadian oscillator has employed a panoply of post-transcriptional regulatory mechanisms, including alternative splicing, adjustable rates of translation, and regulated protein activity and stability. This review focuses on our present understanding of the regulatory network that comprises the plant circadian oscillator. The complexity of this oscillatory network facilitates the maintenance of robust rhythmicity in response to environmental extremes and permits nuanced control of multiple clock outputs. Consistent with this view, the clock is emerging as a target of domestication and presents multiple targets for targeted breeding to improve crop performance. Full article

(This article belongs to the Special Issue Biological Clocks)

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22 pages, 1875 KiB

Open AccessEditor’s ChoiceReview

The Mammalian Circadian Timing System and the Suprachiasmatic Nucleus as Its Pacemaker

by Michael H. Hastings, Elizabeth S. Maywood and Marco Brancaccio

Biology 2019, 8(1), 13; https://doi.org/10.3390/biology8010013 - 11 Mar 2019

Cited by 99 | Viewed by 12145

Abstract

The past twenty years have witnessed the most remarkable breakthroughs in our understanding of the molecular and cellular mechanisms that underpin circadian (approximately one day) time-keeping. Across model organisms in diverse taxa: cyanobacteria (Synechococcus), fungi (Neurospora), higher plants ( [...] Read more.

The past twenty years have witnessed the most remarkable breakthroughs in our understanding of the molecular and cellular mechanisms that underpin circadian (approximately one day) time-keeping. Across model organisms in diverse taxa: cyanobacteria (Synechococcus), fungi (Neurospora), higher plants (Arabidopsis), insects (Drosophila) and mammals (mouse and humans), a common mechanistic motif of delayed negative feedback has emerged as the Deus ex machina for the cellular definition of ca. 24 h cycles. This review will consider, briefly, comparative circadian clock biology and will then focus on the mammalian circadian system, considering its molecular genetic basis, the properties of the suprachiasmatic nucleus (SCN) as the principal circadian clock in mammals and its role in synchronising a distributed peripheral circadian clock network. Finally, it will consider new directions in analysing the cell-autonomous and circuit-level SCN clockwork and will highlight the surprising discovery of a central role for SCN astrocytes as well as SCN neurons in controlling circadian behaviour. Full article

(This article belongs to the Special Issue Biological Clocks)

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17 pages, 1955 KiB

Open AccessReview

Pinniped- and Cetacean-Derived ETosis Contributes to Combating Emerging Apicomplexan Parasites (Toxoplasma gondii, Neospora caninum) Circulating in Marine Environments

by Rodolfo Villagra-Blanco, Liliana M. R. Silva, Iván Conejeros, Anja Taubert and Carlos Hermosilla

Biology 2019, 8(1), 12; https://doi.org/10.3390/biology8010012 - 09 Mar 2019

Cited by 22 | Viewed by 6376

Abstract

Leukocytes play a major role in combating infections either by phagocytosis, release of antimicrobial granules, or extracellular trap (ET) formation. ET formation is preceded by a certain leukocyte cell death form, known as ETosis, an evolutionarily conserved mechanism of the innate immune system [...] Read more.

Leukocytes play a major role in combating infections either by phagocytosis, release of antimicrobial granules, or extracellular trap (ET) formation. ET formation is preceded by a certain leukocyte cell death form, known as ETosis, an evolutionarily conserved mechanism of the innate immune system also observed in marine mammals. Besides several biomolecules and microbial stimuli, marine mammal ETosis is also trigged by various terrestrial protozoa and metazoa, considered nowadays as neozoan parasites, which are circulating in oceans worldwide and causing critical emerging marine diseases. Recent studies demonstrated that pinniped- and cetacean-derived polymorphonuclear neutrophils (PMNs) and monocytes are able to form different phenotypes of ET structures composed of nuclear DNA, histones, and cytoplasmic peptides/proteases against terrestrial apicomplexan parasites, e.g., Toxoplasma gondii and Neospora caninum. Detailed molecular analyses and functional studies proved that marine mammal PMNs and monocytes cast ETs in a similar way as terrestrial mammals, entrapping and immobilizing T. gondii and N. caninum tachyzoites. Pinniped- and cetacean leukocytes induce vital and suicidal ETosis, with highly reliant actions of nicotinamide adenine dinucleotide phosphate oxidase (NOX), generation of reactive oxygen species (ROS), and combined mechanisms of myeloperoxidase (MPO), neutrophil elastase (NE), and DNA citrullination via peptidylarginine deiminase IV (PAD4).This scoping review intends to summarize the knowledge on emerging protozoans in the marine environment and secondly to review limited data about ETosis mechanisms in marine mammalian species. Full article

(This article belongs to the Special Issue Neutrophil Extracellular Traps)

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18 pages, 2710 KiB

Open AccessReview

Histone 4 Lysine 20 Methylation: A Case for Neurodevelopmental Disease

by Rochelle N. Wickramasekara and Holly A. F. Stessman

Biology 2019, 8(1), 11; https://doi.org/10.3390/biology8010011 - 03 Mar 2019

Cited by 16 | Viewed by 6941

Abstract

Neurogenesis is an elegantly coordinated developmental process that must maintain a careful balance of proliferation and differentiation programs to be compatible with life. Due to the fine-tuning required for these processes, epigenetic mechanisms (e.g., DNA methylation and histone modifications) are employed, in addition [...] Read more.

Neurogenesis is an elegantly coordinated developmental process that must maintain a careful balance of proliferation and differentiation programs to be compatible with life. Due to the fine-tuning required for these processes, epigenetic mechanisms (e.g., DNA methylation and histone modifications) are employed, in addition to changes in mRNA transcription, to regulate gene expression. The purpose of this review is to highlight what we currently know about histone 4 lysine 20 (H4K20) methylation and its role in the developing brain. Utilizing publicly-available RNA-Sequencing data and published literature, we highlight the versatility of H4K20 methyl modifications in mediating diverse cellular events from gene silencing/chromatin compaction to DNA double-stranded break repair. From large-scale human DNA sequencing studies, we further propose that the lysine methyltransferase gene, KMT5B (OMIM: 610881), may fit into a category of epigenetic modifier genes that are critical for typical neurodevelopment, such as EHMT1 and ARID1B, which are associated with Kleefstra syndrome (OMIM: 610253) and Coffin-Siris syndrome (OMIM: 135900), respectively. Based on our current knowledge of the H4K20 methyl modification, we discuss emerging themes and interesting questions on how this histone modification, and particularly KMT5B expression, might impact neurodevelopment along with current challenges and potential avenues for future research. Full article

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29 pages, 852 KiB

Open AccessReview

Cold and Exercise: Therapeutic Tools to Activate Brown Adipose Tissue and Combat Obesity

by Carmem Peres Valgas da Silva, Diego Hernández-Saavedra, Joseph D. White and Kristin I. Stanford

Biology 2019, 8(1), 9; https://doi.org/10.3390/biology8010009 - 12 Feb 2019

Cited by 61 | Viewed by 15421

Abstract

The rise in obesity over the last several decades has reached pandemic proportions. Brown adipose tissue (BAT) is a thermogenic organ that is involved in energy expenditure and represents an attractive target to combat both obesity and type 2 diabetes. Cold exposure and [...] Read more.

The rise in obesity over the last several decades has reached pandemic proportions. Brown adipose tissue (BAT) is a thermogenic organ that is involved in energy expenditure and represents an attractive target to combat both obesity and type 2 diabetes. Cold exposure and exercise training are two stimuli that have been investigated with respect to BAT activation, metabolism, and the contribution of BAT to metabolic health. These two stimuli are of great interest because they have both disparate and converging effects on BAT activation and metabolism. Cold exposure is an effective mechanism to stimulate BAT activity and increase glucose and lipid uptake through mitochondrial uncoupling, resulting in metabolic benefits including elevated energy expenditure and increased insulin sensitivity. Exercise is a therapeutic tool that has marked benefits on systemic metabolism and affects several tissues, including BAT. Compared to cold exposure, studies focused on BAT metabolism and exercise display conflicting results; the majority of studies in rodents and humans demonstrate a reduction in BAT activity and reduced glucose and lipid uptake and storage. In addition to investigations of energy uptake and utilization, recent studies have focused on the effects of cold exposure and exercise on the structural lipids in BAT and secreted factors released from BAT, termed batokines. Cold exposure and exercise induce opposite responses in terms of structural lipids, but an important overlap exists between the effects of cold and exercise on batokines. In this review, we will discuss the similarities and differences of cold exposure and exercise in relation to their effects on BAT activity and metabolism and its relevance for the prevention of obesity and the development of type 2 diabetes. Full article

(This article belongs to the Special Issue New Players in Adipocyte Biology)

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23 pages, 3730 KiB

Open AccessReview

The Importance of Peripheral Nerves in Adipose Tissue for the Regulation of Energy Balance

by Magdalena Blaszkiewicz, Jake W. Willows, Cory P. Johnson and Kristy L. Townsend

Biology 2019, 8(1), 10; https://doi.org/10.3390/biology8010010 - 12 Feb 2019

Cited by 49 | Viewed by 12300

Abstract

Brown and white adipose tissues are essential for maintenance of proper energy balance and metabolic health. In order to function efficiently, these tissues require both endocrine and neural communication with the brain. Brown adipose tissue (BAT), as well as the inducible brown adipocytes [...] Read more.

Brown and white adipose tissues are essential for maintenance of proper energy balance and metabolic health. In order to function efficiently, these tissues require both endocrine and neural communication with the brain. Brown adipose tissue (BAT), as well as the inducible brown adipocytes that appear in white adipose tissue (WAT) after simulation, are thermogenic and energy expending. This uncoupling protein 1 (UCP1)-mediated process requires input from sympathetic nerves releasing norepinephrine. In addition to sympathetic noradrenergic signaling, adipose tissue contains sensory nerves that may be important for relaying fuel status to the brain. Chemical and surgical denervation studies of both WAT and BAT have clearly demonstrated the role of peripheral nerves in browning, thermogenesis, lipolysis, and adipogenesis. However, much is still unknown about which subtypes of nerves are present in BAT versus WAT, what nerve products are released from adipose nerves and how they act to mediate metabolic homeostasis, as well as which cell types in adipose are receiving synaptic input. Recent advances in whole-depot imaging and quantification of adipose nerve fibers, as well as other new research findings, have reinvigorated this field of research. This review summarizes the history of research into adipose innervation and brain–adipose communication, and also covers landmark and recent research on this topic to outline what we currently know and do not know about adipose tissue nerve supply and communication with the brain. Full article

(This article belongs to the Special Issue New Players in Adipocyte Biology)

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13 pages, 291 KiB

Open AccessReview

Immunometabolic Links between Estrogen, Adipose Tissue and Female Reproductive Metabolism

by Sally A. Eaton and Jaswinder K. Sethi

Biology 2019, 8(1), 8; https://doi.org/10.3390/biology8010008 - 07 Feb 2019

Cited by 25 | Viewed by 7822

Abstract

The current knowledge of sex-dependent differences in adipose tissue biology remains in its infancy and is motivated in part by the desire to understand why menopause is linked to an increased risk of metabolic disease. However, the development and characterization of targeted genetically-modified [...] Read more.

The current knowledge of sex-dependent differences in adipose tissue biology remains in its infancy and is motivated in part by the desire to understand why menopause is linked to an increased risk of metabolic disease. However, the development and characterization of targeted genetically-modified rodent models are shedding new light on the physiological actions of sex hormones in healthy reproductive metabolism. In this review we consider the need for differentially regulating metabolic flexibility, energy balance, and immunity in a sex-dependent manner. We discuss the recent advances in our understanding of physiological roles of systemic estrogen in regulating sex-dependent adipose tissue distribution, form and function; and in sex-dependent healthy immune function. We also review the decline in protective properties of estrogen signaling in pathophysiological settings such as obesity-related metaflammation and metabolic disease. It is clear that the many physiological actions of estrogen on energy balance, immunity, and immunometabolism together with its dynamic regulation in females make it an excellent candidate for regulating metabolic flexibility in the context of reproductive metabolism. Full article

(This article belongs to the Special Issue New Players in Adipocyte Biology)

2 pages, 158 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Biology in 2018

by Biology Editorial Office

Biology 2019, 8(1), 7; https://doi.org/10.3390/biology8010007 - 24 Jan 2019

Viewed by 2619

Abstract

Rigorous peer-review is the corner-stone of high-quality academic publishing [...] Full article

19 pages, 3555 KiB

Open AccessReview

Role of Rhodopsins as Circadian Photoreceptors in the Drosophila melanogaster

by Pingkalai R. Senthilan, Rudi Grebler, Nils Reinhard, Dirk Rieger and Charlotte Helfrich-Förster

Biology 2019, 8(1), 6; https://doi.org/10.3390/biology8010006 - 10 Jan 2019

Cited by 28 | Viewed by 8276

Abstract

Light profoundly affects the circadian clock and the activity levels of animals. Along with the systematic changes in intensity and spectral composition, over the 24-h day, light shows considerable irregular fluctuations (noise). Using light as the Zeitgeber for the circadian clock is, therefore, [...] Read more.

Light profoundly affects the circadian clock and the activity levels of animals. Along with the systematic changes in intensity and spectral composition, over the 24-h day, light shows considerable irregular fluctuations (noise). Using light as the Zeitgeber for the circadian clock is, therefore, a complex task and this might explain why animals utilize multiple photoreceptors to entrain their circadian clock. The fruit fly Drosophila melanogaster possesses light-sensitive Cryptochrome and seven Rhodopsins that all contribute to light detection. We review the role of Rhodopsins in circadian entrainment, and of direct light-effects on the activity, with a special emphasis on the newly discovered Rhodopsin 7 (Rh7). We present evidence that Rhodopsin 6 in receptor cells 8 of the compound eyes, as well as in the extra retinal Hofbauer-Buchner eyelets, plays a major role in entraining the fly’s circadian clock with an appropriate phase-to-light–dark cycles. We discuss recent contradictory findings regarding Rhodopsin 7 and report original data that support its role in the compound eyes and in the brain. While Rhodopsin 7 in the brain appears to have a minor role in entrainment, in the compound eyes it seems crucial for fine-tuning light sensitivity to prevent overshooting responses to bright light. Full article

(This article belongs to the Special Issue Biological Clocks)

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13 pages, 3807 KiB

Open AccessDiscussion

Lipid Production in Nannochloropsis gaditana during Nitrogen Starvation

by Jorijn H. Janssen, René H. Wijffels and Maria J. Barbosa

Biology 2019, 8(1), 5; https://doi.org/10.3390/biology8010005 - 08 Jan 2019

Cited by 27 | Viewed by 5139

Abstract

The microalga Nannochloropsis gaditana is a natural producer of triacylglycerol (TAG) and the omega-3 fatty acid eicosapentaenoic acid (EPA). TAG accumulation is induced by nitrogen starvation. The biomass-specific photon supply rate used had an effect on EPA and TAG accumulation during nitrogen starvation [...] Read more.

The microalga Nannochloropsis gaditana is a natural producer of triacylglycerol (TAG) and the omega-3 fatty acid eicosapentaenoic acid (EPA). TAG accumulation is induced by nitrogen starvation. The biomass-specific photon supply rate used had an effect on EPA and TAG accumulation during nitrogen starvation as well as on the localization of EPA accumulation. Clear differences in TAG yield on light were found for different biomass-specific photon supply rates and light regimes during nitrogen starvation. De novo EPA synthesis or the translocation of EPA between lipid fractions might be limiting for EPA accumulation in TAG. Further studies are needed to fully understand EPA accumulation in TAG during nitrogen starvation. To elucidate the function of EPA in TAG nitrogen recovery, experiments are suggested. The overexpression of genes involved in de novo EPA synthesis and translocation is proposed to elucidate the exact metabolic routes involved in these processes during nitrogen starvation. This work addresses future opportunities to increase EPA accumulation. Full article

(This article belongs to the Special Issue Microalgal Biotechnology)

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14 pages, 3645 KiB

Open AccessArticle

Formyl-methionyl-leucyl-phenylalanine Induces Apoptosis in Murine Neurons: Evidence for NO-Dependent Caspase-9 Activation

by Chiara Porro, Antonia Cianciulli, Teresa Trotta, Dario Domenico Lofrumento, Rosa Calvello and Maria Antonietta Panaro

Biology 2019, 8(1), 4; https://doi.org/10.3390/biology8010004 - 04 Jan 2019

Cited by 6 | Viewed by 3527

Abstract

Formyl-methionyl-leucyl-phenylalanine (fMLP) may be present in the brain in the course of some infectious diseases of the central nervous system (CNS), although little is known about its role. This investigation was performed to study the effect of fMLP on neuron apoptosis. Our results [...] Read more.

Formyl-methionyl-leucyl-phenylalanine (fMLP) may be present in the brain in the course of some infectious diseases of the central nervous system (CNS), although little is known about its role. This investigation was performed to study the effect of fMLP on neuron apoptosis. Our results showed that fMLP treatment of primary cultures of neurons was able to induce morphological features of apoptosis in cell cultures, as well as activation of the intrinsic apoptotic pathway, through the upregulation of caspase-9 and caspase-3. This effect contextually occurred to the pro-apoptotic protein Bax activation and cytochrome c release. The in vitro fMLP treatment was also able to induce, in a dose-dependent manner, the increase of inducible nitric oxide synthase (iNOS) expression accompanied by an up-regulation of nitric oxide (NO) release. When neuron cultures were pre-treated with 1400 W, a selective iNOS inhibitor, all of the apoptotic features were significantly reversed. Overall, these results demonstrated that fMLP treatment of neurons leads to intrinsic apoptosis activation, through iNOS expression regulation, suggesting a role for fMLP in CNS neurodegenerative processes. Full article

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23 pages, 2822 KiB

Open AccessReview

Cyclin C: The Story of a Non-Cycling Cyclin

by Jan Ježek, Daniel G. J. Smethurst, David C. Stieg, Z. A. C. Kiss, Sara E. Hanley, Vidyaramanan Ganesan, Kai-Ti Chang, Katrina F. Cooper and Randy Strich

Biology 2019, 8(1), 3; https://doi.org/10.3390/biology8010003 - 04 Jan 2019

Cited by 21 | Viewed by 8126

Abstract

The class I cyclin family is a well-studied group of structurally conserved proteins that interact with their associated cyclin-dependent kinases (Cdks) to regulate different stages of cell cycle progression depending on their oscillating expression levels. However, the role of class II cyclins, which [...] Read more.

The class I cyclin family is a well-studied group of structurally conserved proteins that interact with their associated cyclin-dependent kinases (Cdks) to regulate different stages of cell cycle progression depending on their oscillating expression levels. However, the role of class II cyclins, which primarily act as transcription factors and whose expression remains constant throughout the cell cycle, is less well understood. As a classic example of a transcriptional cyclin, cyclin C forms a regulatory sub-complex with its partner kinase Cdk8 and two accessory subunits Med12 and Med13 called the Cdk8-dependent kinase module (CKM). The CKM reversibly associates with the multi-subunit transcriptional coactivator complex, the Mediator, to modulate RNA polymerase II-dependent transcription. Apart from its transcriptional regulatory function, recent research has revealed a novel signaling role for cyclin C at the mitochondria. Upon oxidative stress, cyclin C leaves the nucleus and directly activates the guanosine 5’-triphosphatase (GTPase) Drp1, or Dnm1 in yeast, to induce mitochondrial fragmentation. Importantly, cyclin C-induced mitochondrial fission was found to increase sensitivity of both mammalian and yeast cells to apoptosis. Here, we review and discuss the biology of cyclin C, focusing mainly on its transcriptional and non-transcriptional roles in tumor promotion or suppression. Full article

(This article belongs to the Special Issue Top 35 of Biology Travel Awards 2018)

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13 pages, 1420 KiB

Open AccessArticle

ISSR Analysis of Genetic Diversity and Structure of Plum Varieties Cultivated in Southern China

by Weifeng Wu, Faxing Chen, Kaiwun Yeh and Jianjun Chen

Biology 2019, 8(1), 2; https://doi.org/10.3390/biology8010002 - 21 Dec 2018

Cited by 32 | Viewed by 5936

Abstract

Plums (Prunus spp.) are important deciduous fruit crops in the world. China is a major producer of P. salicina Lindl., but the genetic relationship of Chinese plums in key production regions remain unclear. In this study, 14 University of British Columbia (UBC) [...] Read more.

Plums (Prunus spp.) are important deciduous fruit crops in the world. China is a major producer of P. salicina Lindl., but the genetic relationship of Chinese plums in key production regions remain unclear. In this study, 14 University of British Columbia (UBC) inter simple sequence repeats (ISSR) primers were used to analyze 33 plum varieties cultivated in Fujian Province to determine their genetic diversity and population structure. A total of 146 bands were generated, of which 130 were polymorphic. Mean percentage of polymorphic bands was 89.04%, Shannon’s information index value was 0.38, and the Nei’s genetic index value was 0.24. Using unrooted trees (Neighbor-Joining method), 33 varieties were classified into four groups. Split graph separated them into two major groups, each with two subgroups. The two phylogenetic trees indicate that environmental or natural selection pressure is an important factor influencing their genetic relationship. Analysis of population structure revealed that they have frequent genetic exchanges among closed subpopulations; thus, genetic variation mainly occurs within the population. Additionally, based on the phylogenetic analysis and unique morphological characteristics of fruits, we propose that the Chinese landrace Nai could contribute significantly to development of the famous variety Wickson. Full article

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16 pages, 599 KiB

Open AccessReview

Guide snoRNAs: Drivers or Passengers in Human Disease?

by Manisha Deogharia and Mrinmoyee Majumder

Biology 2019, 8(1), 1; https://doi.org/10.3390/biology8010001 - 20 Dec 2018

Cited by 30 | Viewed by 6832

Abstract

In every domain of life, RNA-protein interactions play a significant role in co- and post-transcriptional modifications and mRNA translation. RNA performs diverse roles inside the cell, and therefore any aberrancy in their function can cause various diseases. During maturation from its primary transcript, [...] Read more.

In every domain of life, RNA-protein interactions play a significant role in co- and post-transcriptional modifications and mRNA translation. RNA performs diverse roles inside the cell, and therefore any aberrancy in their function can cause various diseases. During maturation from its primary transcript, RNA undergoes several functionally important post-transcriptional modifications including pseudouridylation and ribose 2′-O-methylation. These modifications play a critical role in the stability of the RNA. In the last few decades, small nucleolar RNAs (snoRNAs) were revealed to be one of the main components to guide these modifications. Due to their active links to the nucleoside modification, deregulation in the snoRNA expressions can cause multiple disorders in humans. Additionally, host genes carrying snoRNA-encoding sequences in their introns also show differential expression in disease. Although few reports support a causal link between snoRNA expression and disease manifestation, this emerging field will have an impact on the way we think about biomarkers or identify novel targets for therapy. This review focuses on the intriguing aspect of snoRNAs that function as a guide in post-transcriptional RNA modification, and regulation of their host genes in human disease. Full article

(This article belongs to the Special Issue Top 35 of Biology Travel Awards 2018)

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Biology, Volume 8, Issue 1 (March 2019) – 19 articles

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