Search Results (8)

Background: Purple loosestrife (Lythrum salicaria L.) is a medicinal plant native to the spontaneous Romanian flora. The aim of this study was to investigate the phenolic profile, total phenolic content (TPC), and antioxidant capacity (AC) of two L. salicaria L. extracts, a hydro-methanolic extract (LSmet-1) and a hydro-ethanolic extract (LSeth-2), and their putative toxicity, as well as the effect on eye pigment content in the case of Drosophila melanogaster of an extract derived from LSmet-1 (LSmet-3). To the best of our knowledge, this is the first study to evaluate the influence of L. salicaria L. extracts on cytotoxicity and the expression of genes as determined by eye pigment levels, using a D. melanogaster-based model system. Methods: High-performance liquid chromatography was carried out to investigate the chemical composition of the extracts. Spectrophotometric methods were used to estimate their TPC and AC. Cytotoxicity was evaluated using an in vivo D. melanogaster diet-dependent viability assay and eye pigments of w^m4h males, suitable for position-effect variegation studies, which were quantified by a spectrophotometric method. Results: The results indicated that the main phenolic compounds were gallic acid, resveratrol, and rutin in LSmet-1, whereas in LSeth-2, gallic acid and quercetin were the most relevant. LSmet-1 had a higher TPC compared to LSeth-2. Both extracts exhibited notable efficacy in the applied in vitro antioxidant tests. The viability of flies on normal media increased in a concentration-dependent manner at lower concentrations, with the extract being toxic at higher concentrations. On a high-sugar diet, even lower concentrations were toxic. All tested concentrations influenced the eye pigment content. Conclusions: Our study brings new findings on L. salicaria L. extracts, suggesting the need for further investigation before introducing them in therapy. Full article

Spermatogonial stem cells (SSCs) possess the characteristics of self-renewal and differentiation, as well as the ability to generate functional sperm. Their unique stemness has broad applications in male infertility treatment and species preservation. In rodents, research on SSCs has been widely reported, but progress is slow in large livestock such as cattle and pigs due to long growth cycles, difficult proliferation in vitro, and significant species differences. Previously, we showed that histone 3 (H3) lysine 9 (K9) trimethylation (H3K9me3) is associated with the proliferation of bovine SSCs. Here, we isolated and purified SSCs from calf testicular tissues and investigated the impact of different H3K9me3 levels on the in vitro proliferation of bovine SSCs. The enriched SSCs eventually formed classical stem cell clones in vitro in our feeder-free culture system. These clones expressed glial cell-derived neurotrophic factor family receptor alpha-1 (GFRα1, specific marker for SSCs), NANOG (pluripotency protein), C-KIT (germ cell marker), and strong alkaline phosphatase (AKP) positivity. qRT-PCR analysis further showed that these clones expressed the pluripotency genes NANOG and SOX2, and the SSC-specific marker gene GFRα1. To investigate the dynamic relationship between H3K9me3 levels and SSC proliferation, H3K9me3 levels in bovine SSCs were first downregulated using the methyltransferase inhibitor, chaetocin, or transfection with the siRNA of H3K9 methyltransferase suppressor of variegation 3-9 homologue 1 (SUV39H1). The EDU (5-Ethynyl-2′-deoxyuridine) assay revealed that SSC proliferation was inhibited. Conversely, when H3K9me3 levels in bovine SSCs were upregulated by transfecting lysine demethylase 4D (KDM4D) siRNA, the EDU assay showed a promotion of cell proliferation. In summary, this study established a feeder-free culture system to obtain bovine SSCs and explored its effects on the proliferation of bovine SSCs by regulating H3K9me3 levels, laying the foundation for elucidating the regulatory mechanism underlying histone methylation modification in the proliferation of bovine SSCs. Full article

Chloroplast movement rapidly ameliorates the effects of suboptimal light intensity by accumulating along the periclinal cell walls, as well as the effects of excess light by shifting to the anticlinal cell walls. These acclimation responses are triggered by phototropins located at the plasma membrane and chloroplast envelope. Here, we used a recently developed non-invasive system sensitive to very small changes in red light leaf transmittance to perform long-term continuous measurements of dark–light transitions. As a model system, we used variegated Pelargonium zonale leaves containing green sectors (GS) with fully developed chloroplasts and achlorophyllous, white sectors (WS) with undifferentiated plastids, and higher phototropin expression levels. We observed biphasic changes in the red-light transmittance and oscillations triggered by medium intensities of white light, described by a transient peak preceded by a constant decrease in transmittance level. A slight change in red-light transmittance was recorded even in WS. Furthermore, the chloroplast position at lower light intensities affected the rapid light curves, while high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids. Our results extend the knowledge of light-dependent chloroplast movements and thus contribute to a better understanding of their role in regulating photosynthesis under fluctuating light conditions. Full article

Reporter genes inserted via P-element integration into different locations of the Drosophila melanogaster genome have been routinely used to monitor the functional state of chromatin domains. It is commonly thought that P-element-derived reporter genes are subjected to position effect variegation (PEV) when transposed into constitutive heterochromatin because they acquire heterochromatin-like epigenetic modifications that promote silencing. However, sequencing and annotation of the D. melanogaster genome have shown that constitutive heterochromatin is a genetically and molecularly heterogeneous compartment. In fact, in addition to repetitive DNAs, it harbors hundreds of functional genes, together accounting for a significant fraction of its entire genomic territory. Notably, most of these genes are actively transcribed in different developmental stages and tissues, irrespective of their location in heterochromatin. An open question in the genetic and molecular studies on PEV in D. melanogaster is whether functional heterochromatin domains, i.e., heterochromatin harboring active genes, are able to silence reporter genes therein transposed or, on the contrary, can drive their expression. In this work, we provide experimental evidence showing that strong silencing of the Pw⁺ reporters is induced even when they are integrated within or near actively transcribed loci in the pericentric regions of chromosome 2. Interestingly, some Pw⁺ reporters were found insensitive to the action of a known PEV suppressor. Two of them are inserted within Yeti, a gene expressed in the deep heterochromatin of chromosome 2 which carries active chromatin marks. The difference sensitivity to suppressors-exhibited Pw⁺ reporters supports the view that different epigenetic regulators or mechanisms control different regions of heterochromatin. Together, our results suggest that there may be more complexity regarding the molecular mechanisms underlying PEV. Full article

Open systems can only exist by self-organization as pulsing structures exchanging matter and energy with the outer world. This review is an attempt to reveal the organizational principles of the heterochromatin supra-intra-chromosomal network in terms of nonlinear thermodynamics. The accessibility of the linear information of the genetic code is regulated by constitutive heterochromatin (CHR) creating the positional information in a system of coordinates. These features include scale-free splitting-fusing of CHR with the boundary constraints of the nucleolus and nuclear envelope. The analysis of both the literature and our own data suggests a radial-concentric network as the main structural organization principle of CHR regulating transcriptional pulsing. The dynamic CHR network is likely created together with nucleolus-associated chromatin domains, while the alveoli of this network, including springy splicing speckles, are the pulsing transcription hubs. CHR contributes to this regulation due to the silencing position variegation effect, stickiness, and flexible rigidity determined by the positioning of nucleosomes. The whole system acts in concert with the elastic nuclear actomyosin network which also emerges by self-organization during the transcriptional pulsing process. We hypothesize that the the transcriptional pulsing, in turn, adjusts its frequency/amplitudes specified by topologically associating domains to the replication timing code that determines epigenetic differentiation memory. Full article

Chromatin organization is developmentally regulated by epigenetic changes mediated by histone-modifying enzymes and chromatin remodeling complexes. In Drosophila melanogaster, the Tip60 chromatin remodeling complex (dTip60) play roles in chromatin regulation, which are shared by evolutionarily-related complexes identified in animal and plants. Recently, it was found that most subunits previously assigned to the dTip60 complex are shared by two related complexes, DOM-A.C and DOM-B.C, defined by DOM-A and DOM-B isoforms, respectively. In this work, we combined classical genetics, cell biology, and reverse genetics approaches to further investigate the biological roles played during Drosophila melanogaster development by a number of subunits originally assigned to the dTip60 complex. Full article

The human genome has been under selective pressure to evolve in response to emerging pathogens and other environmental challenges. Genome evolution includes the acquisition of new genes or new isoforms of genes and changes to gene expression patterns. One source of genome innovation is from transposable elements (TEs), which carry their own promoters, enhancers and open reading frames and can act as ‘controlling elements’ for our own genes. TEs include LINE-1 elements, which can retrotranspose intracellularly and endogenous retroviruses (ERVs) that represent remnants of past retroviral germline infections. Although once pathogens, ERVs also represent an enticing source of incoming genetic material that the host can then repurpose. ERVs and other TEs have coevolved with host genes for millions of years, which has allowed them to become embedded within essential gene expression programmes. Intriguingly, these host genes are often subject to the same epigenetic control mechanisms that evolved to combat the TEs that now regulate them. Here, we illustrate the breadth of host gene regulation through TEs by focusing on examples of young (The New), ancient (The Old), and disease-causing (The Ugly) TE integrants. Full article

(1) Background: This study examines the impact of Synar policy adoption on youth commercial access to tobacco products in Mississippi, the South, and the remaining U.S. The principal focus on youth commercial access is complemented by analyses of Synar’s impact on minors’ non-commercial access to tobacco and tobacco use patterns. Mississippi has been especially aggressive in implementing Synar, as evidenced by its unusually low retailer violation rates (RVRs). Synar, a mandatory, enforceable regulation meant to limit youth’s retail access to tobacco, was implemented nationwide in 1997. This study is governed by a combination of conceptual insights from a diffusion of health innovation perspective and structuration theory. (2) Methods: Repeated cross-sectional data from 1995 to 2011 from the CDC Youth Risk Behavior Survey are analyzed using a pre/post-implementation, quasi-experimental analytic strategy. Tobacco access and use in the pre-Synar era (1995–1997) are compared with two post-Synar periods (1999–2005 and 2007–2011), thereby highlighting diffusion effects related to this policy innovation within Mississippi, the South, and the remaining U.S. (3) Results: Analyses of temporal trends reveal that Mississippi and other study regions effectively restricted commercial access to tobacco. Positive outcomes associated with Synar adoption were observed several years after initial implementation, thus supporting a diffusion of innovation perspective. However, results also reveal that Mississippi youth were more inclined than their counterparts elsewhere to gain access to tobacco through non-commercial means after Synar implementation, and that declines in tobacco use among Mississippi youth were less robust than those observed elsewhere. Such variegated effects are in line with expectations linked to structuration theory. (4) Conclusions: Synar policy implementation has been generally effective at deterring youth access to tobacco and, in many cases, has yielded declines in tobacco use. However, there is no evidence that especially aggressive retailer compliance checks in Mississippi have yielded distinctive benefits for youth in this state. Full article