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31.
Fiona J. Hemming Laurent Pays Ariane Soubeyran Catherine Larruat Raymond Saxod 《Cell and tissue research》1994,277(3):519-529
In bird skin, nerve fibres develop in the dermis but do not enter the epidermis. In co-cultures of 7-day-old chick embryo dorsal root ganglia and epidermis, the neurites also avoid the epidermis. Previous studies have shown that chondroitin sulphate proteoglycans may be involved. Chondroitin sulphate has therefore been visualized by immunocytochemistry, using themonoclonal antibody CS-56, both in vivo and in vitro using light and electron microscopy. Its distribution was compared to those of 2 other chondroitin sulphate epitopes and to that of the growing nerve fibres. In cultures of epidermis from 7-day-old embryonic chicks, immunoreactivity is found uniformly around the epidermal cells while at 7.5 days the distribution in dermis is heterogeneous, and particularly marked in feather buds. In vivo, chondroitin sulphate immunoreactivity is detected in the epidermis, on the basal lamina, on the surfaces of fibroblasts and along collagen fibrils. This localization is complementary to the distribution of cutaneous nerves. Chondroitin sulphate in the basal lamina could prevent innervation of the epidermis and the dermal heterogeneities could partly explain the nerve fibres surrounding the base of the feathers. Chondroitin sulphate could therefore be important for neural guidance in developing chick skin. 相似文献
32.
Recently the gut fluorescence technique has been critisized because of the possible degradation of chlorophyll into nonfluorescent derivatives during passage through copepod guts and changes of the gut passage time with food concentration. Here pigment budgets have been calculated in 6 experiments with Calanus finmarchicus CIV caught 2 km offshore of the Murmansk Marine Biological Institute (the Barents Sea, Dalnije Zelentsi) in September 1992. Copepods were fed with culture of Platymonas viridis at different concentrations. Gut pigment and ingestion rate increased with food concentration in a similar way. On average between 78% and 89% of ingested chlorophyll was recovered in the guts and faecal pellets. No trend for a greater loss of fluorescence at low food concentration than at high was observed. Pigment content of faecal pellets incubated in filtered seawater decreased by 20–30% in the first 7–12 h and by up to 60% in 48 h. The decline of pigment content was accompanied by a rapid bacterial growth (by a factor of 3 in 48 h). Gut passage time increased with decreasing food concentration (from 40 min at 9 µg pigm l–1 to 64 min at 0.9 µg pigm l–1). These results together with some data by other authors suggest that the gut fluorescence method can be used to estimate in situ grazing rate providing gut passage time is measured properly and there are no losses of faecal material. However, careful consideration should be given to the previous feeding history of copepods. 相似文献
33.
We hypothesized that manganese deficient animals fed high vs moderate levels of polyunsaturated fat would either manifest
evidence of increased oxidative stress or would experience compensatory changes in antioxidant enzymes and/or shifts in manganese
utilization that result in decreased endogenous gut manganese losses. Rats (females in Study 1, males in Study 2,n = 8/treatment) were fed diets that contained 5 or 20% corn oil by weight and either 0.01 or 1.5 μmol manganese/g diet. In
study 2,54Mn complexed to albumin was injected into the portal vein to assess gut endogenous losses of manganese. The manganese deficient
rats:
Gut endogenous losses of manganese tended to account for a smaller proportion of absorbed manganese in rats fed high-fat diets;
otherwise fat intake had few effects on tissue manganese concentrations. 相似文献
1. | Had 30–50% lower liver, tibia, kidney, spleen, and pancreas manganese concentrations than manganese adequate rats; |
2. | Conserved manganese through ≈70-fold reductions in endogenous fecal losses of manganese; |
3. | Had lower heart manganese superoxide dismutase (MnSOD) activity; and |
4. | Experienced only two minor compensatory changes in the activity of copper-zinc superoxide dismutase (CuZnSOD) and catalase. |
34.
B. Illek H. Fischer W. Clauss 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(7):556-562
Basolateral K+ channels and their regulation during aldosterone- and thyroxine-stimulated Na+ transport were studied in the lower intestinal epithelium (coprodeum) of embryonic chicken in vitro. Isolated tissues of the coprodeum were mounted in Ussing chambers and investigated under voltage-clamped conditions. Simultaneous stimulation with aldosterone (1 mol·l-1) and thyroxine (1 mol·l-1) raised short-circuit current after a 1- to 2-h latent period. Maximal values were reached after 6–7 h of hormonal treatment, at which time transepithelial Na+ absorption was more than tripled (77±11 A·cm-2) compared to control (24±8 A·cm-2). K+ currents across the basolateral membrane with the pore-forming antibiotic amphotericin B and application of a mucosal-to-serosal K+ gradient. This K+ current could be dose dependently depressed by the K+ channel blocker quinidine. Fluctuation analysis of the short-circuit current revealed a spontaneous and a blocker-induced Lorentzian noise component in the power density spectra. The Lorentzian corner frequencies increased linearly with the applied blocker concentration. This enabled the calculation of single K+ channel current and K+ channel density. Single K+ channel current was not affected by stimulation, whereas the number of quinidine-sensitive K+ channels in the basolateral membrane increased from 11 to 26·106·cm-2 in parallel to the hormonal stimulation transepithelial Na+ transport. This suggests that the basolateral membrane is a physiological target during synergistic aldosterone and thyroxine regulation of transepithelial Na+ transport for maintaining intracellular K+ homeostasis.Abbreviations
f
frequency
-
f
c
Lorentzian corner frequency
-
g
K
single K+ channel conductance
- HEPES
N-2-hydroxyethylpiperazin-N'-2-ethansulfonic acid
-
i
K
single K+ channel current
- IAmpho
amphotericin B induced K+ current
-
I
sc
short-circuit current
-
I
K
quinidine blockable K+ current
-
I
max
maximally blocked current by quinidine
-
IC
50
half-maximal blocker concentration
-
k
on, k
off
on- and off-rate coefficients of reversible single channel block by quinidine
-
M
K
number of conducting K+ channels
- [Q]
quinidine concentration
-
R
t
transepithelial resistance
-
S
spectral density
-
S
o
Lorentzian plateau
- TBM cells
toad urinary bladder cell line
Present address: University of California at Berkeley, Dept. of Molecular and Cell Biology Berkeley, CA 94720, USA 相似文献
35.
Antisera towards neurotensin (NT) and the structurally related peptide, LANT6, were used to characterize immunoreactive peptides and proteins in extracts of chicken tissues. A 17 kDa protein was identified by Western blotting as a potential precursor to NT and LANT6. However, the posttranslational processing of this common precursor appeared to be tissue specific, giving rise to disproportionate amounts of NT and LANT6, along with varying expression of a large molecular LANT6 (Mr, 15 kDa). The intestinal cells containing immunoreactive NT, LANT6, and large molecular LANT6 behaved similarly during fractionation by size and density. These activities also banded together in particles resembling vesicles during centrifugation of isotonic homogenates of tissue. These results suggest that chicken NT and LANT6 are biosynthesized as parts of the same precursor, the processing of which can give rise to a variety of products stored within secretory vesicles. 相似文献
36.
37.
A systematic survey for the presence of birefringent (anisotropic) structures in rotifers was undertaken. Several common features of rotifers exhibit anisotropism (e.g. trophi & muscles). However, unusual anisotropic crystalline structures (ACS) were found in late stage embryos (i.e. possessing eyespots and trophi, and showing movement). ACS were found in 18 of 26 species of monogonont rotifers (comprising 11 genera of 5 families). In Sinantherina socialis, ACS were present in the lower gut as compact, spherical masses of minute crystals that slowly broke apart and disappeared within 20 hours of hatching. Although several authors have described the existence of refractive bodies in rotifers, to my knowledge this is the first report of their birefringent properties. 相似文献
38.
Cholinesterases present homologies with some cell adhesion molecules; however, it is unclear whether and how they perform adhesive functions. Here, we provide the first direct evidence showing that neurite growth in vitro from various neuronal tissues of the chick embryo can be modified by some, but not all, anticholinesterase agents. By quantifying the neuritic G4 antigen in tectal cell cultures, the effect of anticholinesterases on neurite growth is directly compared with their cholinesterase inhibitory action. BW 284C51 and ethopropazine, inhibiting acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively, strongly decrease neurite growth in a dose-dependent manner. However, echothiophate which inhibits both cholinesterases, does not change neuritic growth. These quantitative data are supplemented by morphological observations in retinal explant cultures grown on striped laminin carpets, viz., defasciculation of neurite bundles by BW 284C51 and Bambuterol occurs, indicating that these drugs disturb adhesive mechanisms. These data strongly suggest that a) cholinesterases can participate in regulating axonal growth, b) both AChE and BChE can perform such a nonsynaptic function, and c) this function is not the result of the enzyme activity per se, since at least one drug was found that inhibits all cholinesterase activities but not neurite growth. Thus, a secondary site on cholinesterase molecules must be responsible for adhesive functions. 相似文献
39.
Chicken oocyte growth: receptor-mediated yolk deposition 总被引:8,自引:0,他引:8
Xinvi Shen Ernst Steyrer Helmut Retzek Esmond J. Sanders Wolfgang J. Schneider 《Cell and tissue research》1993,272(3):459-471
During the rapid final stage of growth, chicken oocytes take up massive amounts of plasma components and convert them to yolk. The oocyte expresses a receptor that binds both major yolk lipoprotein precursors, vitellogenin (VTG) and very low density lipoprotein (VLDL). In the present study, in vivo transport tracing methodology, isolation of coated vesicles, ligand- and immuno-blotting, and ultrastructural immunocytochemistry were used for the analysis of receptor-mediated yolk formation. The VTG/VLDL receptor was identified in coated profiles in the oocyte periphery, in isolated coated vesicles, and within vesicular compartments both outside and inside membrane-bounded yolk storage organelles (yolk spheres). VLDL particles colocalized with the receptor, as demonstrated by ultrastructural visualization of VLDL-gold following intravenous administration, as well as by immunocytochemical analysis with antibodies to VLDL. Lipoprotein particles were shown to reach the oocyte surface by passage across the basement membrane, which possibly plays an active and selective role in yolk precursor accessibility to the oocyte surface, and through gaps between the follicular granulosa cells. Following delivery of ligands from the plasma membrane into yolk spheres, proteolytic processing of VTG and VLDL by cathepsin D appears to correlate with segregation of receptors and ligands which enter disparate sub-compartments within the yolk spheres. In small, quiescent oocytes, the VTG/VLDL receptor was localized to the central portion of the cell. At onset of the rapid growth phase, it appears that this pre-existing pool of receptors redistributes to the peripheral region, thereby initiating yolk formation. Such a redistribution mechanism would obliterate the need for de novo synthesis of receptors when the oocyte's energy expenditure is to be utilized for plasma membrane synthesis, establishment and maintenance of intracellular topography and yolk formation, and preparation for ovulation. 相似文献
40.
Vasil Pirgozliev Stephen C. Mansbridge Izzy M. Whiting Stephen P. Rose Kristina Kljak Amy E. Johnson Falko Drijfhout Sylwia Orczewska-Dudek Atanas G. Atanasov Teodora Mihova 《The Annals of applied biology》2023,183(1):7-14
The aim of this study was to assess the effects of graded levels (0, 3, 6, 9 and 12 g/kg) of dry Sea buckthorn (SB) berries on growth performance, gastrointestinal tract (GIT) development, jejunal histomorphology, bird antioxidant status and caecal short-chain fatty acid concentration when fed to female Ross 308 broiler chickens. In addition, expression of cytokine biomarker genes in the jejunum was evaluated. The five experimental diets were fed from 7 to 21 days age to 8 pens (two birds in each) following randomisation. Feeding SB did not influence bird growth performance (p > .05). There was a linear decrease in butyric, acetic and valeric acid concentrations in caecal digesta (p < .05) and a decrease (p < .05) in crypt depth. The expression of IFNG and CD40LG responded quadratically (p < .05), peaking at 6–9 g/kg dietary inclusion of SB, respectively. Other studied variables were not affected by dietary SB inclusion (p > .05). Feeding dry SB berries up to 12 g/kg of diet did not improve the zootechnical variables of healthy commercial-strain broilers in this study. 相似文献