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91.
Nitrate, ammonia, urea, and glycine were compared as nitrogen sources for Acetabularia mediterranea. Cells grew normally in media containing nitrate or urea, while cells did not grow at all when the same amount of N was supplied as ammonium ion. The utilization of glycine remains questionable. Cells in medium without added N (NDM) increased in length and some formed reproductive caps. The whorls of vegetative cells showed considerable hypertrophy in NDM and in glycine. This hypertrophy was due to the elongation of only the first-(a1) and second- (a2) order articles. When cut, the basal portion of cells without added N regenerated new apices with whorls. The development of these whorls was inversely proportional to the NO2 concentration. Analyses showed that the intracellular nitrogen pool in young cells and regenerating bases was very small, about 1/10 of that of fully grown cells. Therefore we suggest that trace amounts of N contaminants in the medium supported growth and development, the uptake of which was facilitated by the hypertrophied whorls, under N-limited conditions. 相似文献
92.
Uterine vascular permeability and tissue blood volume during the development of the oil-induced decidual cell reaction (DCR) in ovariectomized steroid-treated rats were assessed by measuring the extravascular accumulation of 125I-labelled human serum albumin and the tissue content of 51Cr-labelled red cells 30 min after intravenous administration. Within 15 min of oil instillation into one uterine horn, the vascular permeability of the horn was significantly elevated. Permeability rose to a sharp peak (10 times control levels) 9 h after oil instillation, but dropped to 5 times control values by 12 h and continued a steady decline over the next 7 days. Although a marked increase in uterine weight was associated with the development of the DCR, there was no significant change in blood volume/g tissue until 4 days after oil instillation. 相似文献
93.
We have previously reported that treatment of CsA with aqueous HCl gives rise to the formation of a number of water-soluble compounds. Two of these were identified from their FAB-MS/MS spectra as open-chain nona- and decapeptides. We describe here the identification of two other main compounds deriving from the same treatment. Identification was rendered possible from the comparison of their FAB-MS/MS spectra with those of methyl and acetyl derivatives. The two compounds are water-soluble, open-chain undecapeptides corresponding to 1,11 seco-CsA and of 4,5 seco-isoCsA, respectively. 相似文献
94.
Aleksandra Topic Marina Milenkovic Snezana Uskokovic-Markovic Dragana Vucicevic 《Biological trace element research》2010,134(3):296-306
Investigations of effective, orally active, and safe antidiabetic metallopharmaceuticals have been carried out during the
last two decades. It has been reported that tungsten compounds mimic the action of insulin in intact cell systems. As insulin
mimetics, the most investigated tungsten compound was sodium tungstate (ST), rarely investigated was tungstophosphoric acid
(WPA), but never alanine complex of tungstophosphoric acid (WPA-A). In this study, the insulin mimetic activity of three different
tungsten compounds, ST, WPA, and WPA-A, was evaluated by means of in vitro measurements of the glucose uptake and inhibition
of free fatty acids release from epinephrine-treated isolated rat white adipocytes. We investigated the influence of concentration
(lower and higher, 0.1 and 1.0 mM, respectively) and solvent: isotonic salt solution—saline (0.9% w/v of NaCl) and dimethyl sulfoxide (DMSO; 2% v/v), on the biological effect of tested compounds. Our experimental data showed that all of the three investigated tungsten
compounds possess insulin mimetic activity in vitro on the isolated adipocytes. Influence of concentration and solvents on
insulin mimetic effect for the certain tungsten compounds were: WPA was shown effect independently of concentration and solvents;
higher concentration and DMSO were significant decreasing insulin mimetic effect of ST; lower concentration and saline led
to decreasing effect of WPA-A. Generally, there were no differences in insulin mimetic effect of three tungsten compounds
in lower concentration and dissolved in DMSO. When saline was used as solvent, it was needed higher concentration of investigated
compounds to accomplish the same effect. In conclusion, our results suggest that low concentration (0.1 mM) of ST, WPA, and
WPA-A dissolved in 2% DMSO could be the good candidates for in vivo investigation of their antidiabetic properties. 相似文献
95.
96.
97.
Dean E. Hammond Deborah M. Simpson Catarina Franco Marina Wright Muelas John Waters R.W. Ludwig Mark C. Prescott Jane L. Hurst Robert J. Beynon Edward Lau 《Molecular & cellular proteomics : MCP》2022,21(7):100252
Changes in the abundance of individual proteins in the proteome can be elicited by modulation of protein synthesis (the rate of input of newly synthesized proteins into the protein pool) or degradation (the rate of removal of protein molecules from the pool). A full understanding of proteome changes therefore requires a definition of the roles of these two processes in proteostasis, collectively known as protein turnover. Because protein turnover occurs even in the absence of overt changes in pool abundance, turnover measurements necessitate monitoring the flux of stable isotope–labeled precursors through the protein pool such as labeled amino acids or metabolic precursors such as ammonium chloride or heavy water. In cells in culture, the ability to manipulate precursor pools by rapid medium changes is simple, but for more complex systems such as intact animals, the approach becomes more convoluted. Individual methods bring specific complications, and the suitability of different methods has not been comprehensively explored. In this study, we compare the turnover rates of proteins across four mouse tissues, obtained from the same inbred mouse strain maintained under identical husbandry conditions, measured using either [13C6]lysine or [2H2]O as the labeling precursor. We show that for long-lived proteins, the two approaches yield essentially identical measures of the first-order rate constant for degradation. For short-lived proteins, there is a need to compensate for the slower equilibration of lysine through the precursor pools. We evaluate different approaches to provide that compensation. We conclude that both labels are suitable, but careful determination of precursor enrichment kinetics in amino acid labeling is critical and has a considerable influence on the numerical values of the derived protein turnover rates. 相似文献
98.
The paratabulate calcareous cyst of Calciodinellum operosum Deflandre was recorded in a sediment trap sample collected in the Bay of Naples (Tyrrhenian Sea, Italy). The germination of this resting stage produced a phototrophic vegetative cell that had the typical plate pattern of a Scrippsiella species. The cyst morphotypes, observed in a clonal culture of this species, ranged from cysts with well-developed paratabulation to cysts in which the paratabulation was barely visible, to cysts covered by irregularly shaped crystals. The analysis of thin sections of the calcareous cysts using the polarized light microscope equipped with crossed nicols and a gypsum plate showed that the optical orientation of the calcite crystals was tangential in all the morphotypes examined. We suggest that the crystallographic method we describe might provide insights for calcareous cyst taxonomy and phylogeny . 相似文献
99.
100.
S R Milligan 《Journal of reproduction and fertility》1978,54(2):309-311
Female voles were subjected to various regimens of subcutaneous injections of oestradiol-17beta, oestradiol benzoate and/or progesterone. Ovulation occurred in only a few of the mature females and in none of the immature animals. There was no indication of any increased LH levels in blood samples taken every 2 h for 50 h after 150 microgram oestradiol-17beta. 相似文献