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61.
62.
A Soler C García del Río L García-Torres F Vargas A Martín-Andrés C Osorio 《Revista Espanola de Fisiología》1985,41(1):107-116
The effects of changes in arterial pressure and in circulating volume on Plasma Renin Activity (PRA) in the intact rat were compared by two experimental procedures. Gradual volume depletion was induced by intraperitoneal injection of a hyperoncotic polyethyleneglycol solution (PEG) in absence of acute changes in Systolic Arterial Pressure (SAP). SAP was measured in the conscious state by the tail cuff technique. Plasma Protein Concentration (PPC) and Hematocrit (Hct) increases after PEG injection were compared as the index for measuring the Plasma Volume Reduction (PVR). PRA showed a significant (p less than 0.001) linear relationship with PPC, suggesting a direct dependence of renin secretion on volume depletion. Acute changes in the circulating volume were induced by controlled hemorrhages of 5.0, 10.0, 15.0 and 20.0 ml of blood/kg body weight. The increase in PRA showed a significant relationship with the changes in circulating volume, but it did not show any dependence on the changes in Mean Arterial Pressure (MAP). Our results suggest that, in the intact and conscious rat, renin secretion responds to the information from the cardiopulmonary volume receptors rather than to that from the high pressure receptors. 相似文献
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65.
Hana Votavová Vladimír Gut Karel Bláha Jaroslav Šponar 《International journal of biological macromolecules》1982,4(6):341-346
DNA complexes with polypeptides (Lys-Ala-Ala)1)] and (Lys-Ala-Ala)34 have been studied using the methods of thermal melting and circular dichroism. Derivative melting curves of (Lys-Ala-Ala)10 DNA differed substantially from those of (Lys-Ala-Ala)34 prepared either by salt gradient dialysis or by direct mixing. Melting curves of the former complex were unimodal or bimodal with Tm increasing continuously withn input lysin-to-DNA phosphate ratio (r); those of the latter complex consisted of three separate transitions with Tm values almost independent of r. Complete reversibility of binding in the (Lys-Ala-Ala)10-DNA system but a slow redistribution of (Lys-Ala-Ala)34 on DNA at low temperature were found in the redistribution experiments Much faster redistribution from denatured to native DNA occurs at the temperature of melting, contributing to the unusual trimodal melting pattern. Circular dichroism curves are very similar for both complexes and indicate little change of DNA conformation upon polypeptide binding. 相似文献
66.
E. L. García Diez J. L. Labajo Salazar F. de Pablo Dávila 《International journal of biometeorology》1993,37(4):194-199
The present paper offers data on the effect of certain meteorological parameters on the outbreak of forest fires in Galicia (Spain). In a day-to-day analysis, the values of the stability of the air column and the saturation deficit at the lower levels are related to the number of fires occurring in the following 24 h. 相似文献
67.
F Rabanal I Haro F Reig J M García-Antón 《International journal of peptide and protein research》1990,36(1):26-30
The synthesis of three hepatitis B surface antigens derived from S and pre-S proteins (adw S(140-147), [Tyr148] adw S(139-148), and adw pre-S(120-145)) has been accomplished by the continuous flow Fmoc-polyamide solid phase method. The use of different scavengers and trimethylsilyl bromide (TMSBr) in trifluoroacetic acid as deprotecting procedures is discussed. 相似文献
68.
Development of the visual system of anchovy larvae,Engraulis anchoita: A microanatomical description
Valeria Miranda Stefanía Cohen Alcira O. Díaz Marina V. Diaz 《Journal of morphology》2020,281(4-5):465-475
During the early ontogeny of fish larvae, the accurate development of the visual system plays a key role, because it is involved in locating food, orientation, selection of favorable habitat, and evasion of predators. The structure of the eye of the fish is typical of vertebrates, with some modifications related to the aquatic environment. In the present work, we describe the development of the larval eye of Engraulis anchoita for the first time. Larvae were collected at the Permanent Station of Environmental Studies (EPEA) in coastal waters of the Southwestern Atlantic Ocean during research cruises in 2015 and 2016. We describe the histology of the retina layers, determine the beginning of the functionality of the eye, and discuss a possible synchronization with the development of the digestive tract. This study provides information about the biology of E. anchoita, the most abundant fish species in the southwestern Atlantic Ocean. Also, recent studies have shown responses of the retina and other tissues to the increase in environmental acidity. Therefore, results of this study are also discussed with respect to the possible effect of acidification on the larvae of this species. The continuity of the time series developed at the EPEA will allow monitoring the effect of long-term environmental and biological variables on the early ontogeny of anchovy in the context of climate change. The high commercial fishing potential of E. anchoita due to its high abundance, as well as its essential role in the trophic web of other commercially valuable fishing resources of Argentina, reinforce the need to continue deepening knowledge about this species. Research highlights:
- Eyes of Engraulis anchoita larvae are functional from early larval stages.
- At hatching, the retina is formed by only few layers from which the other layers differentiates during ontogeny.
- Focal distance increases with larval growth.
69.
Three different fluorochrome and specific counterstain combination (DAPI/AMD, DA/DAPI and CMA/DA) treatments were applied to the chromosomes of four Microtidae (Rodentia) species. The results complete the data obtained in our previous paper (Burgos, M., Jiménez, R., & Dìaz de la Guardia, R., Genome 30:540–546, 1988) and prove that the changes in the constitutive heterochromatin in the evolution of the karyotypes of these species are not only due to gain or loss of heterochromatin, but are qualitative with respect to their nucleotide composition, repeated base pair organization or DNA-protein complex modification. These variations lead to the differential response to the fluorescence dye combinations used. 相似文献
70.
Martha L. Bohórquez Alonso Jorge Martínez Cotrina David Aguilar Pardo Enrique Font Miguel Molina-Borja 《Journal of Ethology》2010,28(2):305-311
Many vertebrate species show display behaviors when predators are in their vicinity. Some of these displays may inform the
predator of the improbability of capturing the prey (i.e., pursuit-deterrent displays) and are potentially advantageous to
both predator and prey. Here we present data on a tail display performed by Gonatodes albogularis, a diurnal tropical gecko. We performed transect surveys in three habitats near Bogotá in Colombia. Geckos detected during
transects were approached by the observer in a standardized way, and details of their tail-waving displays were recorded.
In control recordings animals were watched from a distant site without approaching them. Results showed sexual differences
in tail-waving display: when approached by the observer, males performed this behavior more frequently than females. We found
no significant differences between males and females in flight-initiation distances and height above the substratum when they
were initially located. Results also showed that males displayed more frequently when approached than when the simulated predator
remained stationary. We interpret these results as evidence that the display functions as a pursuit-deterrent signal to potential
predators. However, as some tail displays were performed in the presence of conspecifics, the display may also have a social
function. 相似文献