Role of mechanistic Target of Rapamycin (mTOR) signaling in the crustacean molting gland

2012 Fall.Includes bibliographical references.Regulation of the molt cycle in decapod crustaceans is mainly controlled by the X-organ/sinus gland complex (XO/SG) and the Y-organ (YO). Molt-inhibiting hormone (MIH), secreted by the XO/SG complex, suppresses production of molting hormone (ecdysteroids) by a pair of YOs. In the blackback land crab, Gecarcinus lateralis, molting can be induced by eyestalk ablation (ESA) or autotomy of 5 or more walking legs (multiple leg autotomy or MLA). During the molt cycle, the YO transitions through four physiological states: "basal" state at postmolt and intermolt; "activated" state at early premolt; "committed" state at mid premolt and "repressed" state at late premolt. The basal to activated state transition is triggered by a transient reduction in MIH; the YOs hypertrophy, but remain sensitive to MIH. The main hypothesis is that up-regulation of mechanistic Target of Rapamycin (mTOR) signaling, which controls global translation of mRNA into protein, is necessary for YO hypertrophy and ecdysteroidogenesis. cDNAs encoding mTOR, Rheb, Akt (protein kinase B) and p70 S6 kinase (S6k) were cloned from blackback land crab, G. lateralis, and green shore crab, Carcinus maenas. All four genes were expressed in all tissues examined. mTOR appears to be involved in YO activation in early premolt, as rapamycin inhibited YO ecdysteroidogenesis in vivo and in vitro. In addition, the expression of Gl-elongation factor 2 (EF2), Gl-mTOR, and Gl-Akt increased significantly in YOs from premolt, suggesting that an increase in protein synthetic capacity is necessary for YO activation. A putative transforming growth factor-beta (TGFâ) appeared to be involved in the transition of the YO from the activated to committed state, as SB431542, an Activin receptor antagonist, lowered hemolymph ecdysteroid titers in mid premolt animals and abrogated the premolt increases in Gl-EF2, Gl-mTOR, and Gl-Akt mRNA levels. By contrast, molting had no effect on Cm-EF2, Cm-mTOR, Cm-Rheb, Cm-Akt, and Cm-S6k expression in C. maenas YOs. Unlike G. lateralis, adult C. maenas was refractory to ESA. ESA caused a small increase in hemolymph ecdysteroid titers, but animals did not immediately enter premolt. Some ES-ablated animals molted after many months, but most failed to molt at all. We hypothesized that other regions of the nervous system, specifically the brain and/or thoracic ganglion, were secondary source(s) of MIH. Nested endpoint RT-PCR showed that MIH transcript was present in brain and thoracic ganglion of intermolt crabs. Sequencing of the PCR product confirmed its identity as MIH. Real time PCR was used to quantify the effects of ESA on MIH expression in brain and thoracic ganglion on C. maenas red and green color morphs. ESA had little effect on MIH transcript levels, indicating that MIH was not regulated transcriptionally by the loss of the eyestalks. The data suggest that MIH secreted by neurons in the brain and thoracic ganglion is sufficient to prevent molt induction when the primary source of MIH is removed by ESA. There was also no effect of ESA on the expression of Gl-EF2 and mTOR signaling components in C. maenas YOs

A CFD study of two-phase frozen flow of air/water through a safety relief valve

The air-water two phase critical flows through a safety relief valve commonly used in the refrigeration industry is examined with particular emphasis on the prediction of the critical mass flowrates using CFD based approaches. The expansion of the gas through the valve and the associated acceleration is coupled to the liquid phase and results in changes to the velocity slip with the possibility of influencing the choking conditions and the magnitude of the critical mass flows. These conditions are poorly reported in the literature for safety valves. This paper presents a study where the ability of established two phase multi-dimensional modelling approaches to predict such conditions are investigated. Comparison with the simplified mixture model will show that this model tends to underestimate mass flowrates for medium to high liquid mass fraction. However, the two fluid model can adequately account for the thermal and mechanical non equilibrium for these complex flow conditions with the use of simplified droplet sizing rules

An unusual metastatic site of head and neck cancer; Case Report and literature review

The annual occurrence of Head and Neck caner (HNC) is documented to be more than 650,000 cases with 330,000 deaths. In the United States, it represents 3% of all malignancies and affects 53,000 Americans. Metastasis to the lung, liver and bones are considered the most common locations. Herein, We are reporting a case of HNC and an unusual synchronous gastric metastasis found on an upper gastrointestinal endoscopy (EGD) after CECT scanning of Abdomen shows only the mass that related to stomach fundus and MRI pelvic no mass could be seen. Both cancers were poorly differentiation on histopathology, which raises the flag of possible disease aggressiveness and poor treatment respons

Diatom Assemblage in the Lake of Gaberoun, Southern Libya

The lake of Gaberoun in the southern district of Libya was studied to assess the diatom community composition in the littoral zone. Planktic and attached diatoms were listed and information on the constituent species made known (images are shown). Some criteria of the water characteristics are also given such as the pH, which is an average of 8.3, electrical conductivity which accounted for 1.4 µSim/cm1- and total dissolved salts (TDS) of 189.0mg/L1-

The effects of growth hormone receptor-associated ERK activation on adipocyte differentiation and function

Growth hormone (GH) modulates adipocyte function to promote lipolysis via a cell surface GH receptor (GHR) which activates multiple signalling cascades including STAT5 and p42/44 MAP kinase (MAPK) pathways. The growth promoting effects of GH are mediated primarily by STAT5 activation but little is known about pathways mediating the effects of GH on adipocyte function. We therefore studied the effect of GH on STAT5 and MAPK (ERK) activation in the 3T3-L1 mouse pre-adipocyte cell line during adipogenesis. Cells were plated, allowed to reach confluence and cultured in adipogenic medium containing the PPAR agonist, pioglitazone. GH induced activation (10 minutes exposure) of STAT5 and MAPK was analysed on days 0, 2, 5 and 8 during adipogenesis by phospho-specific western blotting and densitometry. During adipogenesis, GH progressively loses the ability to activate p42/44 MAPK despite elevated GHR and unaltered total ERK levels. In contrast, GH-stimulated STAT5 activation increases as 3T3-L1 differentiation proceeds. Subsequently we investigated possible explanations for the altered GHR signalling. The adapter protein p66Shc is thought to be necessary to link GHR activation to the ERK pathway. However levels of this protein, measured by western blotting and densitometry, did not decrease as 3T3-L1 cells underwent adipocyte differentiation. GHR levels increase with adipogenic differentiation of 3T3-L1 cells leading us to hypothesize that this may lead to preferential association with JAK2-STAT5. This was tested by overexpressing the GHR in 3T3-L1; similar GH-stimulated ERK pathway activation was obtained in cells transfected with the GHR vector and in those transfected with the empty vector. Finally, we have investigated whether changes in GHR signalling also occur during adipogenesis of primary pre-adipocytes from mice and various human depots. There was minimal GH-induced phosphorylation of ERK at all-time points before and during differentiation (required up to 15 days in primary cells) and no depot, either murine or human, demonstrated a reduction in p ERK, suggesting that this feature is unique to 3T3-L1. Furthermore, ERK phosphorylation may be the stimulus for mitotic clonal expansion which occurs in the cell line but not in human primaries. GH-stimulated STAT5 activation increases as human and mouse primary pre-adipocytes differentiation progresses, as in the 3T3-L1 cell-line, and may be the result of increased GHR transcript levels as differentiation proceeds. Future studies could investigate the mechanisms responsible for these similarities and differences

Towards the solution of the CP/CAC_{P}/C_{A} anomaly in shell-model calculations of muon capture

Recently many authors have performed shell-model calculations of nuclear matrix elements determining the rates of the ordinary muon capture in light nuclei. These calculations have employed well-tested effective interactions in large scale shell-model studies. For one of the nuclei of interest, namely $^{28}$Si, there exists recent experimental data which can be used to deduce the value of the ratio $C_{P}/C_{A}$ by using the calculated matrix elements. Surprisingly enough, all the abovementioned shell-model results suggest a very small value ($\simeq 0$) for $C_{P}/C_{A}$, quite far from the PCAC prediction and recent data on muon capture in hydrogen. We show that this rather disturbing anomaly is solved by employing effective transition operators. This finding is also very important in studies of the scalar coupling of the weak charged current of leptons and hadrons.Comment: Revtex, 6 pages, 2 figs include

Differentially expressed microRNAs in maternal plasma for the noninvasive prenatal diagnosis of Down syndrome (trisomy 21).

OBJECTIVES: Most developmental processes are under the control of small regulatory RNAs called microRNAs (miRNAs). We hypothesize that different fetal developmental processes might be reflected by extracellular miRNAs in maternal plasma and may be utilized as biomarkers for the noninvasive prenatal diagnosis of chromosomal aneuploidies. In this proof-of-concept study, we report on the identification of extracellular miRNAs in maternal plasma of Down syndrome (DS) pregnancies. METHODS: Using high-throughput quantitative PCR (HT-qPCR), 1043 miRNAs were investigated in maternal plasma via comparison of seven DS pregnancies with age and fetal sex matched controls. RESULTS: Six hundred and ninety-five miRNAs were identified. Thirty-six significantly differentially expressed mature miRNAs were identified as potential biomarkers. Hierarchical cluster analysis of these miRNAs resulted in the clear discrimination of DS from euploid pregnancies. Gene targets of the differentially expressed miRNAs were enriched in signaling pathways such as mucin type-O-glycans, ECM-receptor interactions, TGF-beta, and endocytosis, which have been previously associated with DS. CONCLUSIONS: miRNAs are promising and stable biomarkers for a broad range of diseases and may allow a reliable, cost-efficient diagnostic tool for the noninvasive prenatal diagnosis of DS

The predictors of adolescents’ smoking in Egypt, the global youth tobacco survey findings

This study secondary analysed the last Global Youth Tobacco Survey (GYTS) implemented in Egypt which is a cross-sectional school-based survey used self-administered questionnaire to research smoking among a national representative sample of (2,141) adolescents aged 13–15 years. The study identified that male adolescents are more likely to smoke than female adolescents in Egypt. The likelihood of adolescents’ smoking in Egypt was significantly associated with age; low educational level of fathers; having no weekly pocket of money; poor self-confidence to refuse friends’ smoking offers; absence of restriction on selling cigarettes to adolescents near their schools; and observing teachers’ smoking inside schools. Whereas accessing information, through schools, about smoking consequences prevents adolescents’ smoking. Adolescence is critical period for experimenting and continue smoking. The study identified some personal, parenteral, and school related factors that influence adolescents’ smoking in Egypt. These factors should be considered in designing smoking prevention program that targets adolescents

Cryptic Eimeria genotypes are common across the southern but not northern hemisphere

The phylum Apicomplexa includes parasites of medical, zoonotic and veterinary significance. Understanding the global distribution and genetic diversity of these protozoa is of fundamental importance for efficient, robust and long-lasting methods of control. Eimeria spp. cause intestinal coccidiosis in all major livestock animals and are the most important parasites of domestic chickens in terms of both economic impact and animal welfare. Despite having significant negative impacts on the efficiency of food production, many fundamental questions relating to the global distribution and genetic variation of Eimeria spp. remain largely unanswered. Here, we provide the broadest map yet of Eimeria occurrence for domestic chickens, confirming that all the known species (Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, Eimeria tenella) are present in all six continents where chickens are found (including 21 countries). Analysis of 248 internal transcribed spacer sequences derived from 17 countries provided evidence of possible allopatric diversity for species such as E. tenella (FST values ⩽0.34) but not E. acervulina and E. mitis, and highlighted a trend towards widespread genetic variance. We found that three genetic variants described previously only in Australia and southern Africa (operational taxonomic units x, y and z) have a wide distribution across the southern, but not the northern hemisphere. While the drivers for such a polarised distribution of these operational taxonomic unit genotypes remains unclear, the occurrence of genetically variant Eimeria may pose a risk to food security and animal welfare in Europe and North America should these parasites spread to the northern hemisphere