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1.
2.
G. Pellegrino D. Caimi M. E. Noce A. Musacchio 《Plant Systematics and Evolution》2005,251(2-4):119-129
The rewardless orchid Dactylorhiza sambucina shows a stable flower colour polymorphism, with both yellow- and red-flowered morphs growing sympatrically. Pollination biology and breeding system were investigated to examine the effects of density of plants, colour polymorphism, inflorescence dimension, and flower position within inflorescence on male and female reproductive success in three natural populations of D. sambucina. There were significant differences among sites in the number of pollinia removed and in fruit set per inflorescence. Number of removed pollinia and capsule production in D. sambucina were independent from flower and inflorescence size or flower position. As a whole, the red morphs showed the highest number of capsules produced, while the yellow morphs had the greatest male success. The relative male and female reproductive success were independent from plant density but were significantly correlated with the yellow morph frequency at the population level. Overall, our findings show that the contribution to the total reproductive success deriving from the two colour morphs does not conform with the predictions of negative frequency-dependent selection. 相似文献
3.
A Bobba I Munno B Greco N M Pellegrino P Riccio E Jirillo E Quagliariello 《Biochemical and biophysical research communications》1991,180(2):1125-1129
We have applied a double tagging system in order to study whether purified myelin basic protein is able to adhere to normal human peripheral T lymphocytes without the need to purify cells. Evaluation of myelin basic protein adherence to peripheral blood mononuclear cells was determined with biotinylated myelin basic protein and fluoresceinated avidin, and lymphocyte population was identified by the corresponding phycoerythrinated monoclonal antibody. The observed adherence of myelin basic protein to T lymphocytes was found to depend on protein conformation. 相似文献
4.
Summary Rat pineal nerve endings contain a population of small and of large synaptic vesicles that are either electron lucent or have electron-dense cores. It has been reported that their osmiophilia is elminated when collidine buffer is used in the fixation procedure. We investigated this effect and found that osmium tetroxide and potassium dichromate reactivity were abolished when excised pineal glands were briefly incubated with collidine buffer before glutaraldehyde-cacodylate fixation. Such an effect was not observed when collidine was applied after fixation. Glands that had been fixed in glutaraldehyde or osmium tetroxide buffered with collidine exhibited a peripheral zone containing reactive synaptic vesicles and a deeper, central zone where such reactivity was absent. These results indicate that the effect of collidine is due to depletion of monoamines rather than to chemical blockage of their reactivity, and further suggest that collidine has a higher rate of penetration into tissues than the tested fixatives. 相似文献
5.
Summary In previous work of our laboratory it was demonstrated that collidine (2,4,6-trimethylpyridine) abolishes the core osmiophilia and chromaffin reaction from rat pineal gland and vas deferens nerves. This abolition was apparent when tissues were briefly incubated in collidine or when they were fixed in glutaraldehyde or osmium tetroxide using collidine as a buffer substance. These and other results strongly suggested that the histochemical effect of collidine was due to depletion of monoamines stored in the vesicles core. To examine this hypothesis we studied in this work the effect of collidine on tissues that have taken up tritiated noradrenaline. It was found that tritium was released very rapidly to the incubation medium when collidine was applied to fresh tissues. This effect was not observed with other commonly used buffers such as cacodylate or phosphate. It was also found that tritium release also occurred, although to a lesser extent, when tissues were fixed in glutaraldehyde or osmium tetroxide using collidine as a buffer, and this release was not significant when collidine was applied to previously fixed tissues. Paper chromatographic analysis showed that the radioactive compound(s) extracted from tissues by collidine corresponded to noradrenaline and/or closely related compounds. An abstract of this work was sent to the 17th Annual Meeting of the Society for Neuroscience, New Orleans, Nov 16–21, 1987. Tomsig J.L. and Pellegrino de Iraldi A. Abstract 369-11. 相似文献
6.
Immunoglobulins in human schistosomiasis mansoni 总被引:3,自引:0,他引:3
L J Antunes A P Reis J Pellegrino C A Tavares N Katz 《The Journal of parasitology》1971,57(3):539-542
7.
Schistosoma mansoni: defined system for stepwise transformation of cercaria to schistosomule in vitro 总被引:38,自引:0,他引:38
F J Ramalho-Pinto G Gazzinelli R E Howells T A Mota-Santos E A Figueiredo J Pellegrino 《Experimental parasitology》1974,36(3):360-372
Defined conditions are described for the in vitro production of large numbers of tail-free viable schistosomules. These consist of (1) the centrifugation of cold cercarial suspension and the incubation of the packed cercariae in a minimal volume of medium at 30 C for 40 min to effect tail loss and glandular secretion; (2) the isolation of the bodies by resuspension and sedimentation and (3) the induction of surface changes by incubating the bodies in inactivated serum or a defined tissue culture medium for a further 40 min interval at 37 C with mild agitation.The resultant schistosomules are characterized by the depletion of their penetration gland contents, loss of tail, fluoride and water sensitivities, complement insensitivity, negative “Cercarien-hüllen Reaktion,” and loss of the surface coat as demonstrated by periodic acid-Schiff (PAS) staining and electron microscope observations. 相似文献
8.
Summary The osmium tetroxide-zinc iodide fixative of Champy-Maillet has been used to study the rat's retina at the electron microscope level. Electron opaque deposits were observed all along the photoreceptor cells and concentrated in the outer segments of rods and cones and in the nerve endings. In the outer segments that deposits are located in the inter and intra disk spaces as well as between the disk and outer membranes. In the outer plexiform layer reactive sites include synaptic vesicles and mitochondria; other minor reactive sites are described in the inner segment and inner plexiform layer.Electron opaque deposits were not seen if potassium iodide substitutes zinc iodide in the fixative. However, if osmium tetroxide-potassium iodide fixed retinae are immersed in osmium tetroxide-zinc iodide the characteristic electron-dense material is evidenced at those same sites. The effect of other several fixatives were studied with a similar double fixation procedure. Our finding points to the histochemical demonstration of an unidentified component (s) of the retina which shows a striking specificity of localization and which is made evident when zinc iodide is used in the Champy-Maillet mixture.This work has been supported by grants of the Consejo Nacional de Investigaciones Cientificas y Técnicas, Argentina and U.S. Air Force AF-AFOSR 67-0963 A.We are greatly indebted to Miss Haydée Agoff and to Mr. Alberto Saenz for their skillful technical assistance. 相似文献
9.
Purification of L-[3H]nicotine eliminates low affinity binding 总被引:3,自引:0,他引:3
Some studies of L-[3H]nicotine binding to rodent and human brain tissue have detected two binding sites as evidenced by nonlinear Scatchard plots. Evidence presented here indicates that the low affinity binding site is not stereospecific, is not inhibited by low concentrations of cholinergic agonists and is probably due to breakdown products of nicotine since purification of the L-[3H]nicotine eliminates the low affinity site. 相似文献
10.
Kathleen L. Summers Dr. Patrick Lippiello Ezio Giacobini 《Neurochemical research》1996,21(10):1181-1186
Transcortical dialysis was employed to investigate the effects of subcutaneous (s.c.) injections of RJR-2403 (1.2–7.2 μmol/kg)
on extracellular levels of acetylcholine (ACh), norepinephrine (NE), dopamine (DA), and serotonin (5-HT) in rat. Systemic
administration of RJR-2403 produced a 90% increase of cortical extracellular ACh levels that persisted for up to 90 minutes
after injection. Norepinephrine and DA release were increased 124% and 131% above basal values, respectively. Serotonin (5-HT)
levels in the dialysate were also significantly elevated by RJR-2403 (3.6 μmol/kg, s.c.) 70% above baseline at 90 minutes
post-injection. Comparison of these responses to those of (−)nicotine from a previous study reveals little difference between
the two compounds in their ability to influence cortical neurotransmitter release following systemic administration. 相似文献