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Reproductive cycle, frequency and duration of spawning, energetic content of gonads, and reproductive output of the common
green sea urchin Loxechinus albus were analyzed in the Beagle Channel (Tierra del Fuego) between May 2004 and May 2005. Gonad indices (GI, percentages of gonad
mass in total body mass) were significantly higher in March, April, July, and August than in November and May, thus showing
a negative correlation with the photoperiod. Highest GI values of mature individuals were observed in August, and spawning
occurred from September to December. In females, the mass-specific energy content of gonads (ECG) was highest in spawned gonads
and lowest in mature ones, while in males ECG values were higher in immature stage and lower in premature and mature stages.
High ECG values can be explained by the abundance of nutritive phagocytes. Both ECG and total gonad energy content (TECG)
were higher in females than in males. Mean reproductive output was 7.28% for females and 6.15% for males (expressed as the
difference between mean GI of mature and spawned gonads) and 25.02 kJ for females and 19.26 kJ for males (expressed as the
difference between mean TECG of mature and spawned gonads). 相似文献
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Milla J Montesinos MS Machado JD Borges R Alonso E Moreno-Ortega AJ Cano-Abad MF García AG Ruiz-Nuño A 《Cell calcium》2011,50(4):332-342
The augmentation of neurotransmitter and hormone release produced by ouabain inhibition of plasmalemmal Na+/K+-ATPase (NKA) is well established. However, the mechanism underlying this action is still controversial. Here we have shown that in bovine adrenal chromaffin cells ouabain diminished the mobility of chromaffin vesicles, an indication of greater number of docked vesicles at subplasmalemmal exocytotic sites. On the other hand, ouabain augmented the number of vesicles undergoing exocytosis in response to a K+ pulse, rather than the quantal size of single vesicles. Furthermore, ouabain produced a tiny and slow Ca2+ release from the endoplasmic reticulum (ER) and gradually augmented the transient elevations of the cytosolic Ca2+ concentrations ([Ca2+]c) triggered by K+ pulses. These effects were paralleled by gradual increments of the transient catecholamine release responses triggered by sequential K+ pulses applied to chromaffin cell populations treated with ouabain. Both, the increases of K+-elicited [Ca2+]c and secretion in ouabain-treated cells were blocked by thapsigargin (THAPSI), 2-aminoethoxydiphenyl borate (2-APB) and caffeine. These results are compatible with the view that ouabain may enhance the ER Ca2+ load and facilitate the Ca2+-induced-Ca2+ release (CICR) component of the [Ca2+]c signal generated during K+ depolarisation. This could explain the potentiating effects of ouabain on exocytosis. 相似文献
66.
In this study, sugarcane bagasse was pretreated by six ionic liquids (ILs) using a bagasse/IL ratio of 1:20 (wt%). The solubilization of bagasse in the ILs was followed by water precipitation. On using 1-ethyl-3-methylimidazolium acetate [Emim] [Ac] at 120 °C for 120 min, 20.7% of the bagasse components remained dissolved and enzymatic saccharification experiments resulted on 80% glucose yield within 6h, which evolved to over 90% within 24 h. Moreover, FE-SEM analysis of the precipitated material indicated a drastic lignin extraction and the exposure of nanoscopic cellulose microfibrils with widths of less than 100 nm. The specific surface area (SSA) of the pretreated bagasse (131.84 m2/g) was found to be 100 times that of untreated bagasse. The ability of [Emim] [Ac] to simultaneously increase the SSA and to decrease the biomass crystallinity is responsible for the improved bagasse enzymatic saccharification rates and yields obtained in this work. 相似文献
67.
Janus kinase 3 (JAK3) is a non-receptor tyrosine kinase vital to the regulation of T-cells. We report that JAK3 is a mediator of interleukin-8 (IL-8) stimulation of a different class of hematopoietic relevant cells: human neutrophils. IL-8 induced a time- and concentration-dependent activation of JAK3 activity in neutrophils and differentiated HL-60 leukemic cells. JAK3 was more robustly activated by IL-8 than other kinases: p70S6K, mTOR, MAPK or PKC. JAK3 silencing severely inhibited IL-8-mediated chemotaxis. Thus, IL-8 stimulates chemotaxis through a mechanism mediated by JAK3. Further, JAK3 activity and chemotaxis were inhibited by the flavonoid apigenin (4′,5,7-trihydroxyflavone) at ∼5 nM IC50. These new findings lay the basis for understanding the molecular mechanism of cell migration as it relates to neutrophil-mediated chronic inflammatory processes. 相似文献
68.
MH Luciano Silveira M Rau E Pinto da Silva Bon J Andreaus 《Enzyme and microbial technology》2012,51(5):280-285
This study describes a procedure for the selective determination of endo- (EG) and exo- (ExG) cellulase activities using filter paper as the sole substrate. The procedure is based on the enzymes mode of action whereby EG activity predominantly forms insoluble reducing sugars and ExG activity soluble reducing sugars. The procedure was developed using filter paper as substrate for hydrolysis with three cellulase preparations of Hypocrea jecorina containing either endoglucanase (EG), predominantly exoglucanase (ExG) or both endo- and exoglucanase activities. Hydrolysis experiments, which were followed assessing the formation of total, soluble and insoluble reducing sugars (RS), showed that up to 30min of hydrolysis predominantly insoluble reducing sugars were formed, while after this initial hydrolysis stage soluble reducing sugar formation increased significantly, making it thus possible to measure separately EG and ExG activity. FPA activities obtained from the reaction products at different reaction times suggest that EG-activity (FPA(insol)) should be measured between 10 and 20min of hydrolysis. The proposed procedure allows to evaluate the EG and ExG activity contribution to total cellulase activity and to calculate the endo/exo activity ratio of any cellulase preparation. 相似文献
69.
Díaz-Flores M Ibáñez-Hernández MA Galván RE Gutiérrez M Durán-Reyes G Medina-Navarro R Pascoe-Lira D Ortega-Camarillo C Vilar-Rojas C Cruz M Baiza-Gutman LA 《Life sciences》2006,78(22):2601-2607
Hyperglycemia is associated with metabolic disturbances affecting cell redox potential, particularly the NADPH/NADP+ ratio and reduced glutathione levels. Under oxidative stress, the NADPH supply for reduced glutathione regeneration is dependent on glucose-6-phosphate dehydrogenase. We assessed the effect of different hyperglycemic conditions on enzymatic activities involved in glutathione regeneration (glucose-6-phosphate dehydrogenase and glutathione reductase), NADP(H) and reduced glutathione concentrations in order to analyze the relative role of these enzymes in the control of glutathione restoration. Male Sprague-Dawley rats with mild, moderate and severe hyperglycemia were obtained using different regimens of streptozotocin and nicotinamide. Fifteen days after treatment, rats were killed and enzymatic activities, NADP(H) and reduced glutathione were measured in liver and pancreas. Severe hyperglycemia was associated with decreased body weight, plasma insulin, glucose-6-phosphate dehydrogenase activity, NADPH/NADP+ ratio and glutathione levels in the liver and pancreas, and enhanced NADP+ and glutathione reductase activity in the liver. Moderate hyperglycemia caused similar changes, although body weight and liver NADP+ concentration were not affected and pancreatic glutathione reductase activity decreased. Mild hyperglycemia was associated with a reduction in pancreatic glucose-6-phosphate dehydrogenase activity. Glucose-6-phosphate dehydrogenase, NADPH/NADP+ ratio and glutathione level, vary inversely in relation to blood glucose concentrations, whereas liver glutathione reductase was enhanced during severe hyperglycemia. We conclude that glucose-6-phosphate dehydrogenase and NADPH/NADP+ were highly sensitive to low levels of hyperglycemia. NADPH/NADP+ is regulated by glucose-6-phosphate dehydrogenase in the liver and pancreas, whereas levels of reduced glutathione are mainly dependent on the NADPH supply. 相似文献
70.