Faster Cell Division Research Articles

Mathematical model for the role of multiple pericentromeric repeats on heterochromatin assembly.

Although the length and constituting sequences for pericentromeric repeats are highly variable across eukaryotes, the presence of multiple pericentromeric repeats is one of the conserved features of the eukaryotic chromosomes. Pericentromeric heterochromatin is often misregulated in human diseases, with the expansion of pericentromeric repeats in human solid cancers. In this article, we have developed a mathematical model of the RNAi-dependent methylation of H3K9 in the pericentromeric region of fission yeast. Our model, which takes copy number as an explicit parameter, predicts that the pericentromere is silenced only if there are many copies of repeats. It becomes bistable or desilenced if the copy number of repeats is reduced. This suggests that the copy number of pericentromeric repeats alone can determine the fate of heterochromatin silencing in fission yeast. Through sensitivity analysis, we identified parameters that favor bistability and desilencing. Stochastic simulation shows that faster cell division and noise favor the desilenced state. These results show the unexpected role of pericentromeric repeat copy number in gene silencing and provide a quantitative basis for how the copy number allows or protects repetitive and unique parts of the genome from heterochromatin silencing, respectively.

Cancerous Genome and Mass of Autoinfected Cells, Resulting in Cancer

Cancer is one of the types of genomic diseases. It is caused by pathogenic mutation in the Genome inside a cell so that the cell can be activated to divide & grow uncontrollably. The key objective of this study is to verify that the actual causative agent of the disease cancer is the pathogenic mutation in Genome. The contents of Figures displayed are designed to serve as Results in the targetful strategy of this study. The actual causative agent of cancer and the precancerous effects of risk factors of cancer are identified and made available in order to have strong conclusive statements. Cancer occurs if and only if Cancerous Genome synthesizes enormous number of autoinfected (cancered) cells rapidly by way of apoptosisless and uncontrolled growth of cancered cells involving fast cell division, using its chemical energy-containing nutrients as raw materials; otherwise, none of the precancerous effects of risk factors of cancer can cause the occurrence of cancer.

Technical Electrosmog May be Dangerous

It is scientifically controversial so far whether EMF (non-ionizing electromagnetic fields) can have negative effects on the DNA of cell nuclei. In terms of their energy, they could not do so. However, there is clinical and molecular biological evidence that this can be. There exists a 3-stage mechanism of action, via peroxinitrite, which could lead to DNA damage. The sequence of these processes will be described. Therefore, there is a reasonable suspicion that EMF could also cause DNA damage. The organs with fast and high cell division rate are particularly affected. The general exposure to technical electrosmog (especially 5G) must therefore be marked with a question mark.

An environment-benign approach of bamboo pulp bleaching using extracellular xylanase of strain Bacillus stratosphericus EB-11 isolated from elephant dung.

The use of microbial enzymes is highly encouraged in paper and pulp industries to reduce the excessive use of hazardous chemicals. During the study, xylanase of BacillusstratosphericusEB-11 was characterized for pulp bleaching applications. The extracellular xylanase was produced under submerged fermentation using bamboo wasteas a natural carbon source. There was fast cell division and enzyme production under optimized fermentation conditions in the bioreactor. The highest activity was 91,200Uafter30h of growth with Km and Vmax of 3.52mg/mL and 391.5μmol/min per mgrespectively. The purified enzyme with molecular mass ~ 60kDa had conferred positive activity on native PAGE. The strong inhibition by ethylenediaminetetraacetate and SDS showed the metallo-xylanase nature of the purified enzyme.The bacterial xylanase reduces the use of hydrogen peroxide by 0.4%. Similarly, biological oxygen demand and chemical oxygen demand were reduced by 42.6 and 35.2%. The xylanase-hydrogen peroxide combined treatment and conventional chlorine dioxide-alkaline (CDE1D1D2) bleaching showed almost similar improvement in physicochemical properties of bamboo pulp. Xylanase-peroxide bleaching reduces the lignin content to 4.95% from 13.32% unbleached pulp. This content after CDE1D1D2treatment was 4.21%. The kappa number decreased from 15.2 to 9.46 with increasing the burst factor (15.51),crystallinity index (60.25%), viscosity (20.1 cp), and brightness (65.4%). The overall finding will encourage the development of new cleaner methods of bleaching in the paper and pulp industry.

A Synthetic Small RNA Homologous to the D-Loop Transcript of mtDNA Enhances Mitochondrial Bioenergetics.

Mitochondrial malfunction is a hallmark of many diseases, including neurodegenerative disorders, cardiovascular and lung diseases, and cancers. We previously found that alveolar progenitor cells, which are more resistant to cigarette smoke-induced injury than the other cells of the lung parenchyma, upregulate the mtDNA-encoded small non-coding RNA mito-ncR-805 after exposure to smoke. The mito-ncR-805 acts as a retrograde signal between the mitochondria and the nucleus. Here, we identified a region of mito-ncR-805 that is conserved in the mammalian mitochondrial genomes and generated shorter versions of mouse and human transcripts (mmu-CR805 and hsa-LDL1, respectively), which differ in a few nucleotides and which we refer to as the “functional bit”. Overexpression of mouse and human functional bits in either the mouse or the human lung epithelial cells led to an increase in the activity of the Krebs cycle and oxidative phosphorylation, stabilized the mitochondrial potential, conferred faster cell division, and lowered the levels of proapoptotic pseudokinase, TRIB3. Both oligos, mmu-CR805 and hsa-LDL1 conferred cross-species beneficial effects. Our data indicate a high degree of evolutionary conservation of retrograde signaling via a functional bit of the D-loop transcript, mito-ncR-805, in the mammals. This emphasizes the importance of the pathway and suggests a potential to develop this functional bit into a therapeutic agent that enhances mitochondrial bioenergetics.

Linking the genotypes and phenotypes of cancer cells in heterogenous populations via real-time optical tagging and image analysis.

Linking single-cell genomic or transcriptomic profiles to functional cellular characteristics, in particular time-varying phenotypic changes, could help unravel molecular mechanisms driving the growth of tumour-cell subpopulations. Here we show that a custom-built optical microscope with an ultrawide field of view, fast automated image analysis and a dye activatable by visible light enables the screening and selective photolabelling of cells of interest in large heterogeneous cell populations on the basis of specific functional cellular dynamics, such as fast migration, morphological variation, small-molecule uptake or cell division. Combining such functional single-cell selection with single-cell RNA sequencing allowed us to (1) functionally annotate the transcriptomic profiles of fast-migrating and spindle-shaped MCF10A cells, of fast-migrating MDA-MB-231 cells and of patient-derived head-and-neck squamous carcinoma cells, and (2) identify critical genes and pathways driving aggressive migration and mesenchymal-like morphology in these cells. Functional single-cell selection upstream of single-cell sequencing does not depend on molecular biomarkers, allows for the enrichment of sparse subpopulations of cells, and can facilitate the identification and understanding of the molecular mechanisms underlying functional phenotypes.

Epigenetic regulation of replication origin assembly: A role for histone H1 and chromatin remodeling factors.

During early embryonic development in several metazoans, accurate DNA replication is ensured by high number of replication origins. This guarantees rapid genome duplication coordinated with fast cell divisions. In Xenopus laevis embryos this program switches to one with a lower number of origins at a developmental stage known as mid-blastula transition (MBT) when cell cycle length increases and gene transcription starts. Consistent with this regulation, somatic nuclei replicate poorly when transferred to eggs, suggesting the existence of an epigenetic memory suppressing replication assembly origins at all available sites. Recently, it was shown that histone H1 imposes a non-permissive chromatin configuration preventing replication origin assembly on somatic nuclei. This somatic state can be erased by SSRP1, a subunit of the FACT complex. Here, we further develop the hypothesis that this novel form of epigenetic memory might impact on different areas of vertebrate biology going from nuclear reprogramming to cancer development.

CXCR3high CD8+ T cells with naïve phenotype and high capacity for IFN-γ production are generated during homeostatic T-cell proliferation.

Naïve phenotype (NP) Tcells spontaneously initiate homeostatic proliferation (HP) as T-cell output is reduced because of physiologic thymic involution with age. However, the effects of sustained HP on overall immune function are poorly understood. We demonstrated that the NP CD8+ Tcell population in adult thymectomized mice showing accelerated HP has an increased capacity for TCR-mediated interferon-γ and tumor necrosis factor α production, which is attributed to an increase in CXCR3+ cells in the NP CD8+ Tcell population. The CXCR3+ NP CD8+ Tcells developed during persistent HP with a slow cell division rate, but rarely during robust antigen-driven proliferation with a fast cell division rate. In ontogeny, the proportions of CXCR3+ cells in the NP CD8+ Tcell population showed a biphasic profile, which was high at the newborn and aged stages. Upon transfer, CXCR3+ NP CD8+ Tcells, but not CXCR3- NP CD8+ Tcells, potently enhanced Th17-mediated inflammatory tissue reactions in vivo. Furthermore, CXCR3high NP CD8+ Tcells with similar features were also detected at variable levels in healthy human blood. These results suggest that CXCR3+ NP CD8+ Tcells generated during physiological HP significantly impact overall immunity at the immunologically vulnerable neonatal and aged stages.

Precise Control and Measurement of Temperature with Femtosecond Optical Tweezers

Optical traps have often been used for physical manipulation and transport within liquids for studying bio-systems. In this connection, though a lot of work has focused on the property of the trapped particle, there is little effort on utilizing the effect of the trapping environment. Here we demonstrate a novel method for exploiting the effect of trapping environment in observing the temperature rise in liquids directly at the vicinity of an optical trap center. Our approach utilizes the photo-thermal effect at micro-volume dimension to measure temperature, which could eventually be extended to in-vivo conditions. Our two-color experiment is a unique combination of a non-heating femtosecond trapping laser at 780 nm, which is coupled to a femtosecond infrared heating laser at 1560 nm. Femtosecond pulsed laser heating is much more effective than the traditional continuous-wave laser, which increases the sensitivity of our measurements. The heating laser precisely controls temperature at the focal volume of the trap center using low powers at high repetition rate. The changed values of corner frequency of the optical trap due to this local heating is recognized from its power spectra. The solvent having hydroxyl group is very sensitive to 1560 nm laser due to non-radiative relaxation from their higher excited state. Since most bio-systems contain hydroxyl group, they would be highly responsive to our heating laser, while our trapping laser is highly transparent for such systems. Our method could be used to specifically heat a particular cell to evaluate its faster cell division and also can be utilized for the possible phototherapy of cancer cells. The advantage of this technique over the conventional phototherapy is that this is highly localized due to focusing through high numerical aperture resulting in a high gradient of temperature.

Transcriptional Regulation During Zygotic Genome Activation in Zebrafish and Other Anamniote Embryos.

Embryo development commences with the fusion of two terminally differentiated haploid gametes into the totipotent fertilized egg, whichthrough a series of major cellular and molecular transitions generate a pluripotent cell mass. The activation of the zygotic genome occurs during the so-called maternal to zygotic transition and prepares the embryo for zygotic takeover from maternal factors, in the control of the development of cellular lineages during differentiation. Recent advances in next generation sequencing technologies have allowed the dissection of the genomic and epigenomic processes mediating this transition. These processes include reorganization of the chromatin structure to a transcriptionally permissive state, changes in composition and function of structural and regulatory DNA-binding proteins, and changeover of the transcriptome as it is overhauled from that deposited by the mother in the oocyte to a zygotically transcribed complement. Zygotic genome activation in zebrafish occurs 10 cell cycles after fertilization and provides an ideal experimental platform for elucidating the temporal sequence and dynamics of establishment of a transcriptionally active chromatin state and helps in identifying the determinants of transcription activation at polymerase II transcribed gene promoters. The relatively large number of pluripotent cells generated by the fast cell divisions before zygotic transcription provides sufficient biomass for next generation sequencing technology approaches to establish the temporal dynamics of events and suggest causative relationship between them. However, genomic and genetic technologies need to be improved further to capture the earliest events in development, where cell number is a limiting factor. These technologies need to be complemented with precise, inducible genetic interference studies using the latest genome editing tools to reveal the function of candidate determinants and to confirm the predictions made by classic embryological tools and genome-wide assays. In this review we summarize recent advances in the characterization of epigenetic regulation, transcription control, and gene promoter function during zygotic genome activation and how they fit with old models for the mechanisms of the maternal to zygotic transition. This review will focus on the zebrafish embryobut draw comparisons with other vertebrate model systems and refer to invertebrate models where informative.

Harnessing the helminth secretome for therapeutic immunomodulators.

Helminths are the largest and most complex pathogens to invade and live within the human body. Since they are not able to outpace the immune system by rapid antigen variation or faster cell division or retreat into protective niches not accessible to immune effector mechanisms, their long-term survival depends on influencing and regulating the immune responses away from the mode of action most damaging to them. Immunologists have focused on the excretory and secretory products that are released by the helminths, since they can change the host environment by modulating the immune system. Here we give a brief overview of the helminth-associated immune response and the currently available helminth secretome data. We introduce some major secretome-derived immunomodulatory molecules and describe their potential mode of action. Finally, the applicability of helminth-derived therapeutic proteins in the treatment of allergic and autoimmune inflammatory disease is discussed.

Cloning, characterization and expression of $\emph{OsFMO}_{{\mathbf{(}\emph{t}\mathbf{)}}}$ in rice encoding a flavin monooxygenase

Flavin monooxygenases (FMO) play a key role in tryptophan (Trp)-dependent indole-acetic acid (IAA) biosynthesis in plants and regulate plant growth and development. In this study, the full-length genomic DNA and cDNA of OsFMO(t), a FMO gene that was originally identified from a rolled-leaf mutant in rice, was isolated and cloned from wild type of the rolled-leaf mutant. OsFMO(t) was found to have four exons and three introns, and encode a protein with 422 amino acid residues that contains two basic conserved motifs, with a 'GxGxxG' characteristic structure. OsFMO(t) showed high amino acid sequence identity with FMO proteins from other plants, in particular with YUCCA from Arabidopsis, FLOOZY from Petunia, and OsYUCCA1 from rice. Our phylogenetic analysis showed that OsFMO(t) and the homologous FMO proteins belong to the same clade in the evolutionary tree. Overexpression of OsFMO(t) in transformed rice calli produced IAA-excessive phenotypes that showed browning and lethal effects when exogenous auxins such as naphthylacetic acid (NAA) were added to the medium. These results suggested that the OsFMO(t) protein is involved in IAA biosynthesis in rice and its overexpression could lead to the malformation of calli. Spatio-temporal expression analysis using RT-PCR and histochemical analysis for GUS activity revealed that expression of OsFMO(t) was totally absent in the rolled-leaf mutant. However, in the wild type variety, this gene was expressed at different levels temporally and spatially, with the highest expression observed in tissues with fast growth and cell division such as shoot apexes, tender leaves and root tips. Our results demonstrated that IAA biosynthesis regulated by OsFMO(t) is likely localized and might play an essential role in shaping local IAA concentrations which, in turn, is critical for regulating normal growth and development in rice.

Homeostatic Proliferation of Naive CD4+ T Cells in Mesenteric Lymph Nodes Generates Gut-Tropic Th17 Cells

Homeostatic proliferation of naive T cells in the spleen and cutaneous lymph nodes supplies memory-phenotype T cells. The "systemic" proliferative responses divide distinctly into fast or slow cell division rates. The fast proliferation is critical for generation of effector memory T cells. Because effector memory T cells are abundant in the lamina propria of the intestinal tissue, "gut-specific" homeostatic proliferation of naive T cells may be important for generation of intestinal effector memory T cells. However, such organ-specific homeostatic proliferation of naive T cells has not yet been addressed. In this study, we examined the gut-specific homeostatic proliferation by transferring CFSE-labeled naive CD4(+) T cells into sublethally irradiated mice and separately evaluating donor cell division and differentiation in the intestine, mesenteric lymph nodes (MLNs), and other lymphoid organs. We found that the fast-proliferating cell population in the intestine and MLNs had a gut-tropic α4β7(+) Th17 phenotype and that their production was dependent on the presence of commensal bacteria and OX40 costimulation. Mesenteric lymphadenectomy significantly reduced the Th17 cell population in the host intestine. Furthermore, FTY720 treatment induced the accumulation of α4β7(+)IL-17A(+) fast-dividing cells in MLNs and eliminated donor cells in the intestine, suggesting that MLNs rather than intestinal tissues are essential for generating intestinal Th17 cells. These results reveal that MLNs play a central role in inducing gut-tropic Th17 cells and in maintaining CD4(+) T cell homeostasis in the small intestine.

Genetic Surgery - A Right Strategy to Attack Cancer

The approaches now united under the term "gene therapy" can be divided into two broad strategies: (1) strategy using the ideology of molecular targeted therapy, but with genes in the role of agents targeted at certain molecular component(s) or pathways presumably crucial for cancer maintenance; (ii) strategy aimed at the destruction of tumors as a whole exploiting the features shared by all cancers, for example relatively fast mitotic cell division. While the first strategy is "true" gene therapy, the second one, as e.g. suicide gene therapy, is more like genetic surgery, when a surgeon just cuts off a tumor being not interested in subtle genetic mechanisms of cancer emergence and progression. This approach inherits the ideology of chemotherapy but escapes its severe toxic effects due to intracellular formation of toxic agents. Genetic surgery seems to be the most appropriate approach to combat cancer, and its simplicity is paradoxically adequate to the super-complexity of tumors. The review consists of three parts: (i) analysis of the reasons of tumor supercomplexity and fatally inevitable failure of molecular targeted therapy, (ii) general principles of the genetic surgery strategy, and (iii) examples of genetic surgery approaches with analysis of their drawbacks and the ways for their improvement.

From callus to embryo: a proteomic view on the development and maturation of somatic embryos in Cyclamen persicum

In this study, the proteome structures following the pathway in somatic embryogenesis of Cyclamen persicum were analysed via high-resolution 2D-SDS-PAGE with two objectives: (1) to identify the significant physiological processes during somatic embryogenesis in Cyclamen and (2) to improve the maturation of somatic embryos. Therefore, the effects of maturation-promoting plant growth regulator abscisic acid (ABA) and high sucrose levels on torpedo-shaped embryos were investigated. In total, 108 proteins of differential abundance were identified using a combination of tandem mass spectrometry and a digital proteome reference map. In callus, enzymes related to energy supply were especially distinct, most likely due to energy demand caused by fast growth and cell division. The switch from callus to globular embryo as well as from globular to torpedo-shaped embryo was associated with controlled proteolysis via the ubiquitin-26S proteasome pathway. Storage compound accumulation was first detected 21 days after transfer to plant growth regulator (PGR)-free medium in early torpedo-shaped embryos. Increase in abundance of auxin-amidohydrolase during embryogenesis suggests a possible increase in auxin release in the late embryo stages of Cyclamen. A development-specific isoelectric point switch of catalases has been reported for the first time for somatic embryogenesis. Several proteins were identified to represent markers for the different developmental stages analysed. High sucrose levels and ABA treatment promoted the accumulation of storage compounds in torpedo-shaped embryos. Additionally, proteins of the primary metabolic pathways were decreased in the proteomes of ABA-treated embryos. Thus, ABA and high sucrose concentration in the culture medium improved maturation and consequently the quality of somatic embryos in C. persicum.

E. coli filament formation induced by heterologous S-layer expression

Escherichia coli is a rod-shaped intestinal bacterium which has a size of 1.1-1.5 µm x 2.0-6.0 µm. The fast cell division process and the uncomplicated living conditions have turned E. coli into a widely used host in genetic engineering and into one of the best studied microorganisms of all. We used E. coli BL21(DE3) as host for heterologous expression of S-layer proteins of Lysinibacillus sphaericus JG-A12 in order to enable a fast and high efficient protein production. The S-layer expression induced in E. coli an unusual elongation of the cells, thus producing filaments of >100 µm in length. In the stationary growth phase, E. coli filaments develop tube-like structures that contain E. coli single cells. Fluorescence microscopic analyses of S-layer expressing E. coli cells that were stained with membrane stain FM® 5-95 verify the membrane origin of the tubes. Analyses of DAPI stained GFP-S-layer expressing E. coli support the assumption of a disordered cell division that is induced by the huge amount of recombinant S-layer proteins. However, the underlying mechanism is still not characterized in detail. These results describe the occurrence of a novel stable cell form of E. coli as a result of a disordered cell division process.

Characterization of copper/zinc and manganese superoxide dismutase in green bamboo (Bambusa oldhamii): Cloning, expression and regulation

Bamboo is distinguished by its rapid growth, for growth more than 100cm per day. Because of the rapid growth, tissues have significant ATP requirements, which results in intense reduction of oxygen and thus oxidative stress. For this reason, bamboo may have a special and efficient scavenger system to release the stress during fast cell division and elongation. Here, we investigated superoxide dismutase (SOD, E.C.1.15.1.1), the first line of antioxidant enzymes, in green bamboo (Bambusa oldhamii). The SOD activity profile in this species was complex, with 5 genes and 7 isozymes of CuZnSOD and 4 genes and 1 isozyme of MnSOD. We isolated one of each of the green bamboo CuZnSOD and MnSOD genes, and their activities were stable under a broad range of pH and temperature treatments, even at room temperature for more than 3 days. Bamboo SODs showed developmental and tissue-specific regulation, and both transcript and protein levels were responsive to abscisic acid, UV-B and high-light treatments. The complexity of the cis-elements in promoter regions implied that the regulation mechanisms of SOD might help accomplish the unique fast-growth phenotype of green bamboo.

Not gene therapy, but genetic surgery-the right strategy to attack cancer.

In this review, I will suggest to divide all the approaches united now under common term “gene therapy” into two broad strategies of which the first one uses the methodology of targeted therapy with all its characteristics, but with genes in the role of agents targeted at a certain molecular component(s) presumably crucial for cancer maintenance. In contrast, the techniques of the other strategy are aimed at the destruction of tumors as a whole using the features shared by all cancers, for example relatively fast mitotic cell division or active angiogenesis. While the first strategy is “true” gene therapy, the second one is more like genetic surgery when a surgeon just cuts off a tumor with his scalpel and has no interest in knowing delicate mechanisms of cancer emergence and progression. I will try to substantiate the idea that the last strategy is the only right one, and its simplicity is paradoxically adequate to the super-complexity of tumors that originates from general complexity of cell regulation, strongly disturbed in tumor cells, and especially from the complexity of tumors as evolving cell populations, affecting also their ecological niche formed by neighboring normal cells and tissues. An analysis of the most widely used for such a “surgery” suicide gene/prodrug combinations will be presented in some more details.

Distribution of p53 binding protein 1 (53BP1) and phosphorylated H2A.X during mouse preimplantation development in the absence of DNA damage

The cells in the preimplantation mammalian embryo undergo several rounds of fast cell division. Whether the known DNA repair pathways are active during these early stages of development where cell division is of primary importance, has not been fully established. Because of the important role of phosphorylated H2A.X (gammaH2A.X) in the DNA damage response as well as its putative role in assembly of embryonic chromatin, we analysed its distribution in the preimplantation mouse embryo. We found that H2A.X is highly phosphorylated throughout preimplantation development in the absence of any induced DNA damage. Moreover, gammaH2A.X levels vary significantly throughout the cell cycle. Interestingly, after the 4-cell stage, we detected high levels of H2A.X phosphorylation in mitosis, where telomeres appeared focally enriched with gammaH2A.X. In contrast, 53BP1, which is known to be recruited to DNA damage sites, is undetectable at mitotic chromosomes at these stages and its localisation changes upon blastocyst formation from mainly nuclear to cytoplasmic. We also show that 53BP1 and gammaH2A.X rarely colocalise, suggesting that the high levels of phosphorylation of H2A.X in the embryo might not be directly linked to the DNA damage response in the embryo. Our data suggest that phosphorylation of H2A.X is an important event in the fast dividing cells of the early embryo in the absence of any induced DNA damage. We discuss the possible consequences of these findings on the genome-wide chromatin remodelling that ocurs in the preimplantation mammalian embryo.

Ribosomal protein S6 phosphorylation is a determinant of cell size and glucose homeostasis

The regulated phosphorylation of ribosomal protein (rp) S6 has attracted much attention since its discovery in 1974, yet its physiological role has remained obscure. To directly address this issue, we have established viable and fertile knock-in mice, whose rpS6 contains alanine substitutions at all five phosphorylatable serine residues (rpS6(P-/-)). Here we show that contrary to the widely accepted model, this mutation does not affect the translational control of TOP mRNAs. rpS6(P-/-) mouse embryo fibroblasts (MEFs) display an increased rate of protein synthesis and accelerated cell division, and they are significantly smaller than rpS6(P+/+) MEFs. This small size reflects a growth defect, rather than a by-product of their faster cell division. Moreover, the size of rpS6(P-/-) MEFs, unlike wild-type MEFs, is not further decreased upon rapamycin treatment, implying that the rpS6 is a critical downstream effector of mTOR in regulation of cell size. The small cell phenotype is not confined to embryonal cells, as it also selectively characterizes pancreatic beta-cells in adult rpS6(P-/-) mice. These mice suffer from diminished levels of pancreatic insulin, hypoinsulinemia, and impaired glucose tolerance.