Environmental scanning electron microscopy of the surface of normal and vitrified leaves of Gypsophila paniculata (Babies Breath) cultured in vitro

Leaf surfaces of non-tissue-cultured, vitrified and non-vitrified plantlets of Gypsophila paniculata (Babies Breath) were examined using an environmental scanning electron microscope. Non-tissue-cultured plants had a complete epidermal surface, recessed stomata and wax present on the leaf surface. The surface of tissue-cultured plantlets appeared similar to non-tissue-cultured plants excepting stomata were slightly protruding and less wax appeared to be present. In both non-tissue-cultured and tissue-cultured plants stomata were found both opened and closed and were observed closing. In contrast vitrified plantlets had abnormal, malformed stomata which appeared non-functional. The ventral surfaces of leaves seemed more normal than the dorsal, this may be due to the former receiving more light. Additionally, discontinuities were found in the epidermis. Often epidermal holes were found in association with stomatal apertures. It is suggested that the main cause of desiccation of vitrified G. paniculata plantlets ex vitro is due to loss of water from the discontinuity in epidermis and not because of non-functional stomata. Liquid water could be seen through the epidermal holes indicating that at least some of the extra water in vitrified plantlets is contained in the intercellular spaces.Abbreviations ESEM Environmental scanning election microscope - IAA Indole acetic acid - NTC Non-tissue-cultured - TC Tissue-cultured - V vitrified     

Massively Parallel Sequencing Reveals the Complex Structure of an Irradiated Human Chromosome on a Mouse Background in the Tc1 Model of Down Syndrome

Down syndrome (DS) is caused by trisomy of chromosome 21 (Hsa21) and presents a complex phenotype that arises from abnormal dosage of genes on this chromosome. However, the individual dosage-sensitive genes underlying each phenotype remain largely unknown. To help dissect genotype – phenotype correlations in this complex syndrome, the first fully transchromosomic mouse model, the Tc1 mouse, which carries a copy of human chromosome 21 was produced in 2005. The Tc1 strain is trisomic for the majority of genes that cause phenotypes associated with DS, and this freely available mouse strain has become used widely to study DS, the effects of gene dosage abnormalities, and the effect on the basic biology of cells when a mouse carries a freely segregating human chromosome. Tc1 mice were created by a process that included irradiation microcell-mediated chromosome transfer of Hsa21 into recipient mouse embryonic stem cells. Here, the combination of next generation sequencing, array-CGH and fluorescence in situ hybridization technologies has enabled us to identify unsuspected rearrangements of Hsa21 in this mouse model; revealing one deletion, six duplications and more than 25 de novo structural rearrangements. Our study is not only essential for informing functional studies of the Tc1 mouse but also (1) presents for the first time a detailed sequence analysis of the effects of gamma radiation on an entire human chromosome, which gives some mechanistic insight into the effects of radiation damage on DNA, and (2) overcomes specific technical difficulties of assaying a human chromosome on a mouse background where highly conserved sequences may confound the analysis. Sequence data generated in this study is deposited in the ENA database, Study Accession number: ERP000439.     

Sex‐specific aging in animals: Perspective and future directions

Sex differences in aging occur in many animal species, and they include sex differences in lifespan, in the onset and progression of age‐associated decline, and in physiological and molecular markers of aging. Sex differences in aging vary greatly across the animal kingdom. For example, there are species with longer‐lived females, species where males live longer, and species lacking sex differences in lifespan. The underlying causes of sex differences in aging remain mostly unknown. Currently, we do not understand the molecular drivers of sex differences in aging, or whether they are related to the accepted hallmarks or pillars of aging or linked to other well‐characterized processes. In particular, understanding the role of sex‐determination mechanisms and sex differences in aging is relatively understudied. Here, we take a comparative, interdisciplinary approach to explore various hypotheses about how sex differences in aging arise. We discuss genomic, morphological, and environmental differences between the sexes and how these relate to sex differences in aging. Finally, we present some suggestions for future research in this area and provide recommendations for promising experimental designs.     

The identification of a selective dopamine D2 partial agonist,D3 antagonist displaying high levels of brain exposure

The identification of a highly selective D₂ partial agonist, D₃ antagonist tool molecule which demonstrates high levels of brain exposure and selectivity against an extensive range of dopamine, serotonin, adrenergic, histamine, and muscarinic receptors is described.     

Molecular determinants of KATP channel inhibition by ATP.

ATP-sensitive K+ (KATP) channels are both inhibited and activated by intracellular nucleotides, such as ATP and ADP. The inhibitory effects of nucleotides are mediated via the pore-forming subunit, Kir6.2, whereas the potentiatory effects are conferred by the sulfonylurea receptor subunit, SUR. The stimulatory action of Mg-nucleotides complicates analysis of nucleotide inhibition of Kir6. 2/SUR1 channels. We therefore used a truncated isoform of Kir6.2, that expresses ATP-sensitive channels in the absence of SUR1, to explore the mechanism of nucleotide inhibition. We found that Kir6.2 is highly selective for ATP, and that both the adenine moiety and the beta-phosphate contribute to specificity. We also identified several mutations that significantly reduce ATP inhibition. These are located in two distinct regions of Kir6.2: the N-terminus preceding, and the C-terminus immediately following, the transmembrane domains. Some mutations in the C-terminus also markedly increased the channel open probability, which may account for the decrease in apparent ATP sensitivity. Other mutations did not affect the single-channel kinetics, and may reduce ATP inhibition by interfering with ATP binding and/or the link between ATP binding and pore closure. Our results also implicate the proximal C-terminus in KATP channel gating.     

Rotifers as experimental tools for investigating aging

Comparative biogerontology has much to contribute to the study of aging. A broad range of aging rates have evolved to meet environmental challenges, and understanding these adaptations can produce valuable insights into aging. The supra Phylum Lophotrochozoa is particularly understudied and has several groups that have intriguing patterns of aging. Members of the Lophotrochozoan phylum Rotifera are particularly useful for aging studies because cohort life tables can be conducted with them easily, and biochemical and genomic tools are available for examining aging mechanisms. This paper reviews a variety of caloric restriction (CR) regimens, small molecule inhibitors, and dietary supplements that extend rotifer lifespan, as well as important interactions between CR and genotype, antioxidant supplements, and TOR and jun-N-terminal kinase (JNK) pathways, and the use of RNAi to identify key genes involved in modulating the aging response. Examples of how rapamycin and JNK inhibitor exposure keeps mortality rates low during the reproductive phase of the life cycle are presented, and the ease of conducting life table experiments to screen natural products from red algae for life extending effects is illustrated. Finally, experimental evolution to produce longer-lived rotifer individuals is demonstrated, and future directions to determine the genetic basis of aging are discussed.     

Interleukin-6 enhances insulin secretion by increasing glucagon-like peptide-1 secretion from L cells and alpha cells

Exercise, obesity and type 2 diabetes are associated with elevated plasma concentrations of interleukin-6 (IL-6). Glucagon-like peptide-1 (GLP-1) is a hormone that induces insulin secretion. Here we show that administration of IL-6 or elevated IL-6 concentrations in response to exercise stimulate GLP-1 secretion from intestinal L cells and pancreatic alpha cells, improving insulin secretion and glycemia. IL-6 increased GLP-1 production from alpha cells through increased proglucagon (which is encoded by GCG) and prohormone convertase 1/3 expression. In models of type 2 diabetes, the beneficial effects of IL-6 were maintained, and IL-6 neutralization resulted in further elevation of glycemia and reduced pancreatic GLP-1. Hence, IL-6 mediates crosstalk between insulin-sensitive tissues, intestinal L cells and pancreatic islets to adapt to changes in insulin demand. This previously unidentified endocrine loop implicates IL-6 in the regulation of insulin secretion and suggests that drugs modulating this loop may be useful in type 2 diabetes.