A Review of Different Approaches to the FMS Loading Problem

Loading in flexible manufacturing systems (FMSs) is affected by the characteristics of the FMS under analysis, by the type of plant where the FMS is introduced, and by the production planning hierarchy where the loading module operates. We propose an analysis of the various aspects that influence the problem formulation, identifying the alternatives available in real systems and possible future evolutions. We then provide a survey of different approaches proposed in the literature to tackle the loading problem. Articles are classified according to the type of FMS analyzed, the objective function, and the constraints. Finally, based on our analysis, we suggest some problem issues which need to be addressed, and also directions for future research.     

Antagonistic effects of ocean acidification and warming on hunting sharks

Ocean warming and acidification alter the physiological performance and behaviour of many small‐bodied fishes, yet the potential interactive effects of these stressors on larger predators remains poorly understood. In particular, the combined effects of elevated temperature on metabolism and of elevated CO₂ on the behaviour of large predators may not only affect their foraging behaviour, but also the communities in which their prey live. We used a factorial design to assess how projected warming and acidification create synergies or antagonisms between physiological and behavioural processes, such as swimming activity and feeding behaviour through odour tracking and vision. Temperature increased swimming activity during feeding, independent of CO₂. Although temperature also increased motivational drive to locate and accept prey, elevated CO₂ negated chemical and visual behavioural responses that enable effective hunting. Fundamental to these effects was the negligible effect of high CO₂ in isolation, but its power to negate the positive effects of temperature when brought in conjunction. The reduced potential to locate prey due to the interactive effects of ocean acidification and warming, in combination with increases in energetic demand, suggests that energetic tradeoffs will be needed for sharks to sustain themselves at an individual and population level in a future ocean.     

Phenotypical and Pharmacological Characterization of Stem-Like Cells in Human Pituitary Adenomas

The presence and functional role of tumor stem cells in benign tumors, and in human pituitary adenomas in particular, is a debated issue that still lacks a definitive formal demonstration. Fifty-six surgical specimens of human pituitary adenomas were processed to establish tumor stem-like cultures by selection and expansion in stem cell-permissive medium or isolating CD133-expressing cells. Phenotypic and functional characterization of these cells was performed (1) ex vivo, by immunohistochemistry analysis on paraffin-embedded tissues; (2) in vitro, attesting marker expression, proliferation, self-renewal, differentiation, and drug sensitivity; and (3) in vivo, using a zebrafish model. Within pituitary adenomas, we identified rare cell populations expressing stem cell markers but not pituitary hormones; we isolated and expanded in vitro these cells, obtaining fibroblast-free, stem-like cultures from 38 pituitary adenoma samples. These cells grow as spheroids, express stem cell markers (Oct4, Sox2, CD133, and nestin), show sustained in vitro proliferation as compared to primary cultures of differentiated pituitary adenoma cells, and are able to differentiate in hormone-expressing pituitary cells. Besides, pituisphere cells, apparently not tumorigenic in mice, engrafted in zebrafish embryos, inducing pro-angiogenic and invasive responses. Finally, pituitary adenoma stem-like cells express regulatory pituitary receptors (D2R, SSTR2, and SSTR5), whose activation by a dopamine/somatostatin chimeric agonist exerts antiproliferative effects. In conclusion, we provide evidence that human pituitary adenomas contain a subpopulation fulfilling biological and phenotypical signatures of tumor stem cells that may represent novel therapeutic targets for therapy-resistant tumors.     

Subcellular analysis of Ca2+ homeostasis in primary cultures of skeletal muscle myotubes.

Specifically targeted aequorin chimeras were used for studying the dynamic changes of Ca2+ concentration in different subcellular compartments of differentiated skeletal muscle myotubes. For the cytosol, mitochondria, and nucleus, the previously described chimeric aequorins were utilized; for the sarcoplasmic reticulum (SR), a new chimera (srAEQ) was developed by fusing an aequorin mutant with low Ca2+ affinity to the resident protein calsequestrin. By using an appropriate transfection procedure, the expression of the recombinant proteins was restricted, within the culture, to the differentiated myotubes, and the correct sorting of the various chimeras was verified with immunocytochemical techniques. Single-cell analysis of cytosolic Ca2+ concentration ([Ca2+]c) with fura-2 showed that the myotubes responded, as predicted, to stimuli known to be characteristic of skeletal muscle fibers, i.e., KCl-induced depolarization, caffeine, and carbamylcholine. Using these stimuli in cultures transfected with the various aequorin chimeras, we show that: 1) the nucleoplasmic Ca2+ concentration ([Ca2+]n) closely mimics the [Ca2+]c, at rest and after stimulation, indicating a rapid equilibration of the two compartments also in this cell type; 2) on the contrary, mitochondria amplify 4-6-fold the [Ca2+]c increases; and 3) the lumenal concentration of Ca2+ within the SR ([Ca2+]sr) is much higher than in the other compartments (> 100 microM), too high to be accurately measured also with the aequorin mutant with low Ca2+ affinity. An indirect estimate of the resting value (approximately 1-2 mM) was obtained using Sr2+, a surrogate of Ca2+ which, because of the lower affinity of the photoprotein for this cation, elicits a lower rate of aequorin consumption. With Sr2+, the kinetics and amplitudes of the changes in [cation2+]sr evoked by the various stimuli could also be directly analyzed.     

A genetically encoded, fluorescent indicator for cyclic AMP in living cells

Cyclic AMP controls several signalling cascades within cells, and changes in the amounts of this second messenger have an essential role in many cellular events. Here we describe a new methodology for monitoring the fluctuations of cAMP in living cells. By tagging the cAMP effector protein kinase A with two suitable green fluorescent protein mutants, we have generated a probe in which the fluorescence resonance energy transfer between the two fluorescent moieties is dependent on the levels of cAMP. This new methodology opens the way to the elucidation of the biochemistry of cAMP in vivo.     

Proton electrochemical gradient and phosphate potential in submitochondrial particles

1. The aerobic uptake of inorganic ions, such as ⁸⁶Rb⁺ or ¹²⁵I^?, by submitochondrial particles, is about one order of magnitude lower than the uptake of organic ions, such as acridines or 8-anilino-1-naphthalene sulphonate. The values of ΔpH, the transmembrane pH differential, and Δψ, the transmembrane membrane potential are between 60 and 100 mV when calculated on the inorganic ions and between 150 and 240 mV when calculated on the organic ions. The discrepancy between the ΔpH and Δψ values from organic and inorganic ions is large at high but not at low ion/protein ratios.2. In the absence of weak bases and strong acids the values of $\text{Δ}\text{}\text{?}\text{gm}{}_{\mathrm{<mtext>H</mtext>}}$, the proton electrochemical potential difference, are close to 100 mV and the magnitude of ΔpH and Δψ are similar. Weak bases decrease ΔpH and enhance Δψ. Strong acids decrease Δψ and enhance ΔpH. Interchangeability of ΔpH with Δψ occurs at low concentrations of weak bases and strong acids. High concentrations of weak bases and strong acids cause depression of $\text{Δ}\text{}\text{?}\text{gm}{}_{\mathrm{<mtext>H</mtext>}}$.3. Concentrations of weak bases capable of abolishing ΔpH, do not affect ATP synthesis. Concentrations of strong acids capable of abolishing Δψ affect only slightly ATP synthesis. Concentrations of weak bases and strong acids capable of causing a decline of ΔpH + Δψ inhibit ATP synthesis.4. Depression of $\text{Δ}\text{}\text{?}\text{gm}{}_{\mathrm{<mtext>H</mtext>}}$ is paralleled by inhibition of ATP synthesis and decline of ΔGp, the phosphate potential. Abolition of ATP synthesis occurs only when $\text{Δ}\text{}\text{?}\text{gm}{}_{\mathrm{<mtext>H</mtext>}}$ is below 20 mV. The $\text{ΔG}\text{p}\text{/Δ}\text{}\text{?}\text{gm}{}_{\mathrm{<mtext>H</mtext>}}$ ratio increases hyperbolically with the decrease of $\text{Δ}\text{}\text{?}\text{gm}{}_{\mathrm{<mtext>H</mtext>}}$.     

“Eumeiosi” e “Meiosi Apoomeotipica” Seguita da “Mitosi a Diplounivalenti” Nel Tessuto Somatico di Sambucus

Summary

The Authors describe in Sambucus nigra L the occurrence of the » apohomeotypic teiosis « followed by a »mitosis with diplounivalents « (Battaglia 1945, 1947) in ae somatic tissue of the style. The AA. observed also the occasional formation f four haploid nuclei and then the occurence of the »eumeiosis« (Battaglia 1945).     

Zeaxanthin and non‐photochemical quenching in sun and shade leaves of C3 and C4 plants

The relationships between non‐radiative energy dissipation and the carotenoid content, especially the xanthophyll cycle components, were studied in sun and shade leaves of several plants possessing C₃ ( Hedera helix and Laurus nobilis ) or C₄ ( Zea mays and Sorghum bicolor ) photosynthetic pathways. Sun‐shade acclimation caused marked changes in the organisation and function of photosynthetic apparatus, including significant variation in carotenoid content and composition. The contents of zanthophyll cycle pigments were higher in sun than in shade leaves in all species, but this difference was considerably greater in C₃ than in C₄ plants. The proportion of photoconvertible violaxanthin, that is the amount of violaxanthin (V) which can actually be de‐epoxidised to zeaxanthin, was much greater in sun than in shade leaves. The amount of photoconvertible V was always linearly dependent on the chlorophyll a/b ratio, although the slope of the relationship varied especially between C₃ and C₄ species. The leaf zeaxanthin and antheraxanthin contents were correlated with non‐radiative energy dissipation in all species under different light environments. These relationships were curvilinear and variable between sun and shade leaves and between C₃ and C₄ species. Hence, the dissipation of excess energy does not appear to be univocally dependent on zeaxanthin content and other photoprotective mechanisms may be involved under high irradiance stress. Such mechanisms appear largely variable between C₃ and C₄ species according to their photosynthetic characteristics.