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11.
Embryo survival and alevin emergence pattern of brown trout were studied in simulated redds with different homogeneous gravel sizes and different concentrations of peat material. Optimal survival (95%) occurred in 18 mm gravel and survival decreased with decreasing gravel size. High concentrations (40%) of peat material resulted in low survival (65%). The proportion of premature emerging alevins increased in finer gravels and at high peat concentrations. Premature alevins had a large yolk sac and are probably very vulnerable to predators. 相似文献
12.
A Egesten J Alumets C von Mecklenburg M Palmegren I Olsson 《The journal of histochemistry and cytochemistry》1986,34(11):1399-1403
An immunoelectron microscopic technique using protein A-gold as a specific marker was used for precise intracellular localization of eosinophil granule proteins. Eosinophils from healthy individuals were isolated in metrizamide gradients. Eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO) were clearly located in the matrix of the large crystalloid-containing granules. In addition, ECP was probably present in the small granules of eosinophils. Major basic protein (MBP) was present in the crystalloid structure of specific granules. This method can be applied in studies of eosinophil degranulation to trace the release of biological effector molecules. 相似文献
13.
Non-specific binding of protein-stabilized gold sols as a source of error in immunocytochemistry 总被引:3,自引:0,他引:3
O Behnke T Ammitzb?ll H Jessen M Klokker K Nilausen J Tranum-Jensen L Olsson 《European journal of cell biology》1986,41(2):326-338
The observation that protein-A conjugated gold sols bound to fibronectin-collagen (FNC) fibres in human fibroblast cultures prompted a series of studies on the binding of gold particles stabilized in various ways (Staphylococcal protein A, bovine serum albumin, avidin, streptavidin, gelatin, hemoglobin, polyethylene glycol (MW 20 000), methylcellulose and the nonionic detergent Tween 20) to cell and tissue components, to protein dot blots and SDS-PAGE blots on nitrocellulose paper. We found that binding of gold particles to certain cell and tissue components and to various immobilized proteins did occur irrespective of the stabilizing agent. We argue that, albeit gold sols are stabilized against salt coagulation by adsorption of proteins and other stabilizing agents, "naked areas" are (constantly or intermittently) present on particle surfaces, available for interaction with cell and tissue components that have a high electrostatic affinity for the charged gold surface under prevailing experimental conditions. Non-specific binding may be reduced or abolished by competing proteins (i.e. proteins with a higher affinity for gold than any component in the object studied) provided the proteins and the gold conjugate are present concomitantly during incubation. We found gelatin (Bloom number 60-100) to be an effective competitive protein probably due to its high affinity for gold over a wide pH range. Further, gelatin did not appreciably inhibit the specific interaction in dot blots between SpA and IgG except at very low IgG concentrations. A protocol for the use of gold-protein conjugates to circumvent the hazards of unspecific gold binding is suggested. 相似文献
14.
15.
16.
B Edlund L Rask P Olsson O W?linder O Zetterqvist L Engstr?m 《European journal of biochemistry》1969,9(4):451-455
17.
Simulation of the dynamics in a fed batch process for production of Baker's yeast is discussed and applied. Experimental evidences are presented for a model of the energy metabolism. The model involves the concept of a maximum respiratory capacity of the cell. If the sugar concentration is increased above a critical value, corresponding to a critical rate of glycolysis and a maximum rate of respiration, then all additional sugar consumed at higher sugar concentrations is converted into ethanol.In a fed batch process with constant sugar feed the sugar concentration declines slowly. If ethanol is present when the sugar concentration declines below the critical value of 110 mg/dm3 fructose +glucose the metabolism switches rapidly into combined oxidation of sugar and ethanol. Thus, no diauxic growth is involved under process conditions. The rate of ethanol consumption is determined by the free capacity of respiration under these conditions. The invertase activity of the cells was found to be so high that mainly fructose and glucose were present in the medium, typically in the concentration range around 100 mg/dm3. These components are consumed at the same rate but with fructose at a higher concentration, indicating a higher K
s
for fructose consumption.The model was used in simulation experiments to demonstrate the dynamics of the Baker's yeast process and the influence of different process conditions.List of Symbols
DOT % air sat
dissolved oxygen tension
-
F dm3/h
rate of inlet medium flow
-
H kg/(dm3 % air sat.)
oxygen solubility
-
K kg/m3
saturation constant specified by index
-
K
L
a 1/h
volumetric oxygen transfer coefficient
-
m g/(g · h)
maintenance coefficient specified by index
-
P kg/(m3 · h)
mean productivity of biomass in the process
-
q g/(g · h)
specific consumption or production rate
-
S kg/m3
concentration of sugar in reactor
-
S
0 kg/m3
concentration of inlet medium sugar
medium
t h
process time
-
V dm3
medium volume
-
X kg/m3
concentration of biomass
-
Y g/g
yield coefficient specified by index
-
1/h
specific growth rate
Index
aa
anaerobic condition
-
c
critical value
-
e
ethanol
-
ec
ethanol consumption
-
ep
ethanol production
-
max
maximum value
-
o
oxygen
-
oe
oxygen for growth on ethanol
-
os
oxygen for growth on sugar
-
s
sugar
-
x
biomass 相似文献
18.
Ove Nilsson C. H. Anthony Little Göran Sandberg Olof Olsson 《Plant molecular biology》1996,31(4):887-895
We monitored, for the first time, the activity of two model heterologous promoters, the Agrobacterium rhizogenes rolC and the cauliflower mosaic virus (CaMV) 35S, throughout the annual cycle of growth and dormancy in a perennial species, hybrid aspen. Each promoter was fused to the uidA -glucuronidase (GUS) reporter gene and the constructs were introduced into the hybrid aspen genome by Agrobacterium-mediated transformation. Both wildtype and transgenic plants were cultivated under different regimes of photoperiod and temperature to induce passage through one growth-dormancy-reactivation cycle, and at intervals GUS staining was assessed in stem sections. In rolC::uidA transformants, GUS activity in rapidly growing current-year shoots was not only tissue-specific, being localized to the phloem, but also cell-specific at the shoot base, where it was present only in the companion cells. However, during the onset of dormancy induced by short photoperiod, GUS activity shifted laterally from the phloem to include the cortex and pith. After subsequent exposure to chilling temperatures to induce the transition between the dormancy stages of rest and quiescence, GUS activity almost disappeared from all stem tissues, but regained its original phloem specificity and intensity after the shoots were reactivated by exposing them to long photoperiod and high temperatures. In contrast, GUS activity in the stem of 35S::uidA transformants was strong in all tissues except for the vascular cambium and xylem, and did not vary in intensity during the growth-dormancy-reactivation cycle. The lateral shift and increased intensity of GUS activity in the stem of rolC::uidA transformants during dormancy induction was shown to be associated with the accumulation of starch, and to be mimicked by incubating stem sections in sucrose, as well as glucose and fructose, but not sorbitol, prior to the GUS assay. Our results demonstrate that the activities of the rolC and 35S promoters varied in very different, unpredictable ways during the annual cycle of growth and dormancy in a perennial species, and indicate that the spatial and temporal variation in rolC promoter activity that we observed in the stem of transgenic hybrid aspen plants is attributable to cellular and seasonal changes in sucrose content. 相似文献
19.
Distribution of PACAP (pituitary adenylate cyclase-activating polypeptide)-like and helospectin-like peptides in the teleost gut 总被引:2,自引:0,他引:2
Pituitary adenylate cyclase-activating polypeptide (PACAP) and helospectin are two vasoactive intestinal polypeptide (VIP)-related neuropeptides that have recently been demonstrated in the mammalian gut; the aim of this study was to reveal their occurrence and localisation in the gastrointestinal tract, swimbladder, urinary bladder and the vagal innervation of the gut of teleosts, using immunohistochemical methods on whole-mounts and sections of these tissues from the Atlantic cod, Gadus morhua and the rainbow trout, Oncorhynchus mykiss. Both PACAP-like and helospectin-like peptides were present in the gut wall of the two species. Immunoreactive nerve fibres were found in all layers but were most frequent in the myenteric plexus and along the circular muscle fibres. Immunoreactivity was also demonstrated in nerves innervating the swimbladder wall, the urinary bladder and blood vessels to the gut. Immunoreactive nerve cell bodies were found in the myenteric plexus of the gut and in the muscularis mucosae of the swimbladder. In the vagus nerve, non-immunoreactive nerve cells were surrounded by PACAP-immunoreactive fibres. Double staining revealed the coexistence of PACAP-like and helospectin-like peptides with VIP in all visualized nerve fibres and in some endocrine cells. It is concluded that PACAP-like and helospectin-like peptides coexist with VIP in nerves innervating the gut of two teleost species. The distribution suggests that both PACAP and helospectin, like VIP, are involved in the control of gut motility and secretion. 相似文献
20.
Christine L. Olsson Monique Graffe Mathias Springer John W. B. Hershey 《Molecular genetics and genomics : MGG》1996,250(6):705-714
To investigate the physiological roles of translation initiation factor IF3 and ribosomal protein L20 inEscherichia coli, theinfC, rpmI andrpIT genes encoding IF3, L35 and L20, respectively, were placed under the control oflac promoter/operator sequences. Thus, their expression is dependent upon the amount of inducer isopropyl thiogalactoside (IPTG) in the medium. Lysogenic strains were constructed with recombinant lambda phages that express eitherrpmI andrplT orinfC andrpmI in trans, thereby allowing depletion of only IF3 or L20 at low IPTG concentrations. At low IPTG concentrations in the IF3-limited strain, the cellular concentration of IF3, but not L20, decreases and the growth rate slows. Furthermore, ribosomes run off polysomes, indicating that IF3 functions during the initiation phase of protein synthesis in vivo. During slow growth, the ratio of RNA to protein increases rather than decreases as occurs with control strains, indicating that IF3 limitation disrupts feedback inhibition of rRNA synthesis. As IF3 levels drop, expression from an AUU-infC-lacZ fusion increases, whereas expression decreases from an AUG-infC-lacZ fusion, thereby confirming the model of autogenous regulation ofinfC. The effects of L20 limitation are similar; cells grown in low concentrations of IPTG exhibited a decrease in the rate of growth, a decrease in cellular L20 concentration, no change in IF3 concentration, and a small increase in the ratio of RNA to protein. In addition, a decrease in 50S subunits and the appearance of an aberrant ribosome peak at approximately 41–43S is seen. Previous studies have shown that the L20 protein negatively controls its own gene expression. Reduction of the cellular concentration of L20 derepresses the expression of anrplT-lacZ gene fusion, thus confirming autogenous regulation by L20. 相似文献