Conservation and loss of ribosomal RNA gene sites in diploid and polyploid Fragaria (Rosaceae)

<p>Abstract</p> <p>Background</p> <p>The genus <it>Fragaria </it>comprises species at ploidy levels ranging from diploid (2<it>n </it>= 2<it>x </it>= 14) to decaploid (2<it>n </it>= 10<it>x </it>= 70). Fluorescence <it>in situ </it>hybridization with 5S and 25S rDNA probes was performed to gather cytogenetic information that illuminates genomic divergence among different taxa at multiple ploidy levels, as well as to explore the evolution of ribosomal RNA genes during polyploidization in <it>Fragaria</it>.</p> <p>Results</p> <p>Root tip cells of diploid taxa were typified by two 5S and six 25S rDNA hybridization signals of varying intensities, providing a baseline for comparisons within the genus. In three exceptional diploid genotypes, <it>F. nilgerrensis </it>(CFRA 1358 and CFRA 1825) and <it>F. vesca </it>'Yellow Wonder', two 5S but only four 25S rDNA sites were found but with differing site losses. The numbers of 5S and 25S rDNA signals, respectively were three and nine in a triploid <it>F</it>. ×<it>bifera </it>accession, and were four and twelve in three tetraploids, thus occurring in proportional 1.5× and 2× multiples of the typical diploid pattern. In hexaploid <it>F</it>. <it>moschata</it>, a proportional multiple of six 5S rDNA sites was observed, but the number of 25S rDNA sites was one or two less than the proportionate prediction of eighteen. This apparent tendency toward rDNA site loss at higher ploidy was markedly expanded in octoploids, which displayed only two 5S and ten 25S rDNA sites. In the two decaploids examined, the numbers of 5S and 25S rDNA signals, respectively, were four and fifteen in <it>F. virginiana </it>subsp. <it>platypetala</it>, and six and twelve in <it>F. iturupensis</it>.</p> <p>Conclusions</p> <p>Among diploid <it>Fragaria </it>species, a general consistency of rDNA site numbers implies conserved genomic organization, but highly variable 25S signal sizes and intensities and two instances of site loss suggest concurrent high dynamics of rDNA copy numbers among both homologs and non-homologs. General conservation of rDNA site numbers in lower ploidy, but marked site number reductions at higher ploidy levels, suggest complex evolution of rDNA sites during polyploidization and/or independent evolutionary pathways for 6<it>x </it>versus higher ploidy strawberries. Site number comparisons suggest common genomic composition among natural octoploids, and independent origins of the two divergent decaploid accessions.</p

Microvascular endothelial cells of the corpus luteum

The cyclic nature of the capillary bed in the corpus luteum offers a unique experimental model to examine the life cycle of endothelial cells, involving discrete physiologically regulated steps of angiogenesis, blood vessel maturation and blood vessel regression. The granulosa cells and theca cells of the developing antral follicle and the steroidogenic cells of the corpus luteum produce and respond to angiogenic factors and vasoactive peptides. Following ovulation the neovascularization during the early stages of corpus luteum development has been compared to the rapid angiogenesis observed during tumor formation. On the other end of the spectrum, the microvascular endothelial cells are the first cells to undergo apoptosis at the onset of corpus luteum regression. Important insights on the morphology and function of luteal endothelial cells have been gained from a combination of in vitro and in vivo studies on endothelial cells. Endothelial cells communicate with cells comprising the functional unit of the corpus luteum, i.e., other vascular cells, steroidogenic cells, and immune cells. This review is designed to provide an overview of the types of endothelial cells present in the corpus luteum and their involvement in corpus luteum development and regression. Available evidence indicates that microvascular endothelial cells of the corpus luteum are not alike, and may differ during the process of angiogenesis and angioregression. The contributions of vasoactive peptides generated by the luteal endothelin-1 and the renin-angiotensin systems are discussed in context with the function of endothelial cells during corpus luteum formation and regression. The ability of two cytokines, tumor necrosis factor alpha and interferon gamma, are evaluated as paracrine mediators of endothelial cell function during angioregression. Finally, chemokines are discussed as a vital endothelial cell secretory products that contribute to the recruitment of eosinophils and macrophages. The review highlights areas for future investigation of ovarian microvascular endothelial cells. The potential clinical applications of research directed on corpus luteum endothelial cells are intriguing considering reproductive processes in which vascular dysfunctions may play a role such as ovarian failure, polycystic ovary syndrome (PCOS), and ovarian hyperstimulation syndrome (OHSS)

Stingless bees in Miocene amber of southeastern China (Hymenoptera: Apidae)

Among the many inclusions from the exceptionally rich fossiliferous amber of Zhangpu, China (Middle Miocene: Langhian), stingless bees (Apinae: Meliponini) are particularly common, analogous to the merely slightly older amber sites of Mexico and the Dominican Republic. While there is a large number of workers in Zhangpu amber, only two species are represented. The systematics and morphology of the tribe Meliponini is outlined, including a revision to terms of orientation and direction when discussing surfaces and features of appendages, all in order to better discuss the traits of the fossils as well as place them into a broader context in the global systematics of stingless bees. The two amber species are representative of two Old World genera of Meliponini: Tetragonula Moure and Austroplebeia Moure. While the former is widespread across southern Asia, Malesia, Papuasia, and Australia, the latter is today known only from New Guinea and Australia. Neither genus occurs in the environs of Zhangpu today. Tetragonula (Tetragonula) florilega Engel, new species, is a generally typical species of the subgenus although it intermingles traits otherwise found in two large species groups of non-Australian Tetragonula s.str. The species of Austroplebeia from Zhangpu is sufficiently distinct to place in a new subgenus, Anteplebeina Engel. Austroplebeia (Anteplebeina) fujianica Engel, new species, shares a long list of character states with Austroplebeia s.str., including the presence of yellow maculation on the face, mesoscutum, mesoscutellum, and metepisternum, found only in this clade among Asiatic Meliponini. Nonetheless, the species differs in the length of the malar space and various features of wing venation. Keys are provided to the genera in Zhangpu amber and the subgenera of both genera. The diversity of stingless bees in amber is discussed, as well as the presence of these two fossils in the Middle Miocene of mainland Asia in relation to prior divergence time estimates, phylogenetic relationships, as well as the paleogeography of the region and potential biogeographic hypotheses. The biological association of stingless bees with resins, particularly the collection of dipterocarp resins, is discussed as Zhangpu amber is a Class II resin likely produced by an extinct species of Dipterocarpaceae (Malvales). Also discussed are the ecological preferences of modern Tetragonula and Austroplebeia relative to the reconstructed paleoenvironment of the Zhangpu amber rainforest. Emendations to the classification of Meliponini are appended, with the following new taxa proposed: Atrichotrigona Engel, new subgenus of Axestotrigona Moure; Lispotrigona V.H. Gonzalez &amp; Engel, new subgenus of Nannotrigona Cockerell; Asperplebeia Engel, new genus; Nanoplebeia Engel, new subgenus of Plebeia Schwarz; Aphaneuropsis Engel, Koilotrigona Engel, Necrotrigona Engel, Dichrotrigona Engel, Nostotrigona Engel, Ktinotrofia Engel, all new subgenera of Trigona Jurine; Chapadapis Engel, new subgenus of Schwarziana Moure. The following higher groups are also established: Hypotrigonina Engel, new sutribe; Heterotrigonitae Engel, new infratribe; Trigoniscitae Engel, new infratribe

A Plant Virus Substrate Induces Early Upregulation of BMP2 for Rapid Bone Formation

Many nanoscale materials have been developed to investigate the effects on stem cell differentiations via topographical and chemical cues for applications in tissue engineering and regenerative medicine. The use of plant viruses as cell supporting substrates has been of particular interest due to the rapid induction of bone marrow derived mesenchymal stem cells (BMSCs) towards osteogenic cells. In this study, the role of Tobacco mosaic virus (TMV) and its early effects on osteoinduction with particular emphasis on the regulation of bone morphogenetic protein-2 (BMP2) was examined. We observed that the cells on the virus substrate immediately aggregated and formed bone-like nodules within 24 hours. An immediate increase in BMP2 gene and protein expression for cells on the TMV substrate was observed within 8 hours of osteoinduction. Moreover, BMP2 expression was highly localized to cells within the cell aggregates. This enhanced differentiation only occurred when TMV was coated on a solid support but not upon adding the virus to the media solution. Taken together, the results from this study highlight the potential of virus-based nanomaterials to promote endogenous BMP2 production which may prove to be a unique approach to studying the regulatory mechanisms involved in early osteoblastic differentiation

Plant-level real-time monitoring data reveal substantial abatement potential of air pollution and CO₂ in China's cement sector

China is the world’s greatest cement producer, generating significant air pollution and CO2 emissions. To combat these impacts, China introduced stricter air pollution standards for the cement industry in 2015, yet no plant-level analysis exists to determine their effectiveness. To analyze the impacts of emission regulations, we coupled 2014–2018 smokestack-level real-time observations with plant-specific information and constructed an hourly based dataset of air pollutants (particulate matter [PM], sulfur dioxide [SO2], nitrogen oxide [NOX]) and CO2 emissions. Our analysis shows that regulations introduced in 2015 led to PM, SO2, and NOX reductions of 50.3%, 43.6%, and 34.2%, respectively, but CO2 increased by 5%. Interestingly, 9.4% of the plants analyzed reached China’s 2020 ultralow air pollution standards in 2018. Further analysis shows that if small and old plants are phased out and all remaining plants implement advanced equipment and improve fuels and energy efficiency, PM, SO2, NOX, and CO2 could be further reduced by 68.8%, 66.1%, 82.2%, and 62.0% by 2060. Our results reveal the co-benefits of clean air and climate policies for cement production

Médium et discours

Ce numéro des Cahiers de Praxématique propose une réflexion sur la question du médium, et plus précisément sur son rôle dans la production des discours et sur les façons dont il l’influence. Le terme médium est défini par le Trésor de la langue française, dans son emploi en langage courant, comme « ce qui sert de support, d’intermédiaire à quelque chose » et, dans le domaine de la sociologie de la communication, comme « moyen de transmission d’un message » (TLFi, s.v. médium). Régis Debray es..

The Effect of Matrix Stiffness of Biomimetic Gelatin Nanofibrous Scaffolds on Human Cardiac Pericyte Behaviour

Congenital heart disease (CHD) is the most common and deadly congenital anomaly, accounting for up to 7.5% of all infant deaths. Survival in children born with CHD has improved dramatically over the past several decades (this positive trend being counterbalanced by the fact that more patients develop heart failure). Seminal data indicate an alteration of the extracellular matrix occurs with time in these hearts due to diffuse and abundant interstitial fibrosis. This results in an escalation in the stiffness of the local myocardial microenvironment. However, the influence of matrix stiffness in regulating the function of resident human stromal cells has not been reported. The objective of this study was to determine the impact of scaffold stiffness on the antigenic and functional profile of cardiac pericytes (CPs) isolated from patients with CHD. To this end, we have first manufactured gelatin nanofibrous scaffolds with varying degrees of stiffness using an in situ cross-linking electrospinning technique in a pure water solvent system. We assessed Young’s modulus and performed a comprehensive physicochemical characterization of the scaffolds employing scanning electron microscopy and Fourier transform infrared spectroscopy. We next evaluated the changes induced by a different scaffold stiffness on CP morphology, antigenic profile, viability, proliferation, angiocrine activity, and induced differentiation. Results indicate that soft matrixes with a fiber diameter of ∼400 nm increase CP proliferation, secretion of angiopoietin 2, and F-actin stress fiber formation, without affecting the antigenic profile, viability, or differentiation. These data indicate for the first time that human CPs can be functionally influenced by slight changes in matrix stiffness. The study elucidates the importance of mechanical/morphological cues in modulating the behavior of stromal cells isolated from patients with CHD