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1.
Giuseppe Cassano Michele Maffia Sebastiano Vilella Carlo Storelli 《The Journal of membrane biology》1988,101(1):225-236
Summary The Na-dependent transport of a number of organic molecules (d-glucose,l-proline,l-alanine,l-phenylalanine) in brush-border membrane vesicles isolated from the intestine of the eel (Anguilla anguilla) was monitored by recording the fluorescence quenching of the voltage-sensitive cyanine dye 3,3-diethylthiacarbocyanine iodide (DiS-C2(5)). The experimental approach consisted of: a) generating an inside-negative membrane potential mimicking in vivo conditions: b) measuring the rate of membrane potential decay (i.e., the rate of fluorescence quenching decay) due to Na-neutral substrate cotransport. Rates of membrane potential decay showed saturation on substrate concentration andK
app values (the substrate concentration giving 50% of the maximal rate) were estimated for Na-dependent transport ofd-glucose (0,099mm),l-alanine (0.516mm),l-proline (0.118mm) andl-phenylalanine (2.04mm). The influence of an inside-negative membrane potential on the affinity of the transporter for glucose and for sodium is discussed. 相似文献
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Summary The expression and distribution of S-100 protein and type IV collagen was studied immunohistochemically in sympathetic neuroblasts
from the paravertebral region to the adrenal glands in human embryos and fetuses ranging from 7 to 12 weeks gestational age.
Prom 7 weeks gestational age, S-100 protein was detected in round or oval cells mingling with sympathetic neuroblasts, and
in spindle-shaped cells forming a continuous layer around them. The latter S-100 protein-positive cells were found in contact
with the Schwann cells of nerve fibres entering the groups of sympathetic neuroblasts. Staining for type IV collagen showed
that all groups of sympathetic neuroblasts were surrounded by a continuous basement membrane. By examining serial sections
stained for type IV collagen and S-100 protein, a continuous basement membrane was found along the distribution pattern of
the peripheral S-100 protein-positive spindle cells. The morphology of these cells, and their relationships with Schwann cells
and with the basement membrane of the sympathetic neuroblasts, indicated that they were Schwann-like cells probably capable
of synthesizing a continuous basement membrane separating the neuroblasts from the adjacent tissues. In contrast, the round
or oval S-100 protein-positive cells, in contact with the sympathetic neuroblasts and not associated with nerve fibres, were
considered as sustentacular or sustentacular precursor cells. At week 7 gestational age, the peri-adrenal sympathetic neuroblasts
and their sustentacular and Schwann-like cells started to invade the adrenal glands and mingled with the adrenal cortical
cells. These findings suggest the extra-adrenal origin of the sustentacular cells in embryonic and fetal adrenal glands. 相似文献
4.
Andrea?NardiniEmail author Fabio?Raimondo Mauro?Scimone Sebastiano?Salleo 《Trees - Structure and Function》2004,18(6):714-721
The leaf miner Cameraria ohridella causes premature defoliation of Aesculus hippocastanum trees. In order to assess the whole-plant loss of productivity caused by the parasite, we monitored seasonal changes of leaf gas exchange and leaf area losses in horse chestnut trees freely infested or chemically treated to prevent moth infestation (controls). Data were integrated in a model and the annual loss of net primary productivity (NPP) was calculated for infested trees with respect to controls. Measurements showed marked vertical stratification of C. ohridella attacks, with lower crown strata being more infested than higher ones. Leaf gas exchange was maximum between May and early June, but it strongly decreased starting from mid-June even in controls. Model calculations showed that NPP loss of infested trees was about 30% on an annual basis (when the first moth attack is recorded at the end of April). Model simulations showed that postponing the start day of attack would have important positive effects on plants NPP. For example, if the start day of attack was postponed to 20 May, the annual loss of NPP would be about 15%. Our study suggests that A. hippocastanum trees attacked by C. ohridella are not facing serious risks of decline, especially if methods are adopted to postpone the start day of attack (e.g. removal of fallen leaves in autumn). Our data do not support the view that plants need to be totally protected from the parasite by application of insecticides. 相似文献
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Biological Effects of Insulin and Its Analogs on Cancer Cells With Different Insulin Family Receptor Expression 下载免费PDF全文
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Claudia Giannetto Vincenzo Carcangiu Sebastiano Luridiana Albamaria Parmeggiani 《Chronobiology international》2020,37(7):974-979
ABSTRACT Photoperiodic treatments have been of practical interest in controlling seasonal reproduction in sheep, goats and horses. Melatonin is the principal mediator of the environmental photoperiodic message. To investigate the intra- and inter-subject variability of melatonin 24 h rhythm, ten female Italian Saddle horses (8–10 yrs old, mean body weight 525 ± 30 kg), ten female Sarda breed sheep (2–3 yrs old, mean body weight 40.5 ± 2.8 kg) and ten female Sarda breed goats (3–4 yrs old, mean body weight 38.9 ± 4.1 kg), housed individually in a 4 × 4 m soundproof box equipped with 50 × 100 cm opening windows, were subjected to a natural photoperiod of the vernal equinox (sunrise 06:00 h; sunset 18:00 h). Blood samples were collected from each animal, every 3 h over a 48 h period starting at 00:00 h of day 1 and ending at 00:00 h of day 3. Plasma melatonin concentrations were determined by direct radioimmunoassay (MelatoninDirect RIA, Labor Diagnostika Nord GmbH, Nordhorn, Germany). The application of single cosinor method substantiated a circadian rhythm of melatonin with a nocturnal peak in all studied species. The application of two-way ANOVA on the rhythmic parameters indicated statistically significant differences between the three species in all of the cosinor analysis-derived parameters of MESOR, amplitude, acrophase and robustness of rhythm. Analyses of intra- and inter-subject variability indicate that organization of the melatonin 24 h rhythm is characterized by great accuracy of control within and between the individuals of a breed. In conclusion, features of the 24 h rhythm of melatonin among species; however, the 24 h rhythmicity of melatonin each species showed high stability within the various subjects and within the same subject. These findings must be taken into consideration when applying photoperiod and melatonin treatments for breeding purposes. 相似文献
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Han Wang Guotao Wu Hujun Cao Claudio Pistidda Anna‐Lisa Chaudhary Sebastiano Garroni Martin Dornheim Ping Chen 《Liver Transplantation》2017,7(13)
Reversible hydrogen storage over hydrides of light elements (HLEs) under ambient condition has been pursued actively for nearly two decades. However, because of unfavorable thermodynamics and/or severe kinetic barrier of HLEs, limited progress has been made. Here, it is demonstrated that the interaction of LiBH4 with Mg(NH2)2 and LiH, three of the most investigated HLEs, can lead to a fully reversible dehydrogenation/rehydrogenation cycle at temperatures below 373 K. More importantly, with the desorption enthalpy of 24 kJ (mol H2)?1 the dehydrogenation process at 1.0 bar H2 is theoretically possible to be as low as 266 K. Characterization of this combination of HLEs shows that LiBH4 serves as a reagent complexing with intermediates and products of the dehydrogenation of Mg(NH2)2‐LiH, and significantly alters the overall thermodynamic and kinetic properties of the system. 相似文献
10.
This paper describes changes in leaf water status and in stem, petiole and leaf blade hydraulics preceding leaf senescence and shedding in Castanea sativa L. (chestnut). Measurements of maximum diurnal leaf conductance to water vapour (gL), minimum water potential (L), hydraulic conductance per unit leaf surface area of stems (KSL), petioles (KPL) and leaf blades (KLL) and number of functional conduits and inside diameter distribution were performed in June, September and October 1999. In September, still green leaves had undergone some dehydration as indicated by decreased gL (by 75 %) and L with respect to June. In the same time, KSL decreased by 88 %, while KPL and KLL decreased by 50 % and 20 % of the conduits of stems and 10 % of the petioles (all belonging to the widest diameter range) were no longer functioning, causing a decrease in the theoretical flow by 82 % in stems and 27 % in petioles. Stem xylem blockage was apparently due to tyloses growing into conduits. We advance the hypothesis that the entire process of leaf shedding and winter rest may be initiated by extensive stem embolism occurring during the summer. 相似文献