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71.
Jostein Sigurd Solbakken Birgitta Norberg Kuninori Watanabe Karin Pittman 《Environmental Biology of Fishes》1999,56(1-2):53-65
The response of morphological, histological and endocrinological development to exogenous 1-thyroxine (T4) and to water depth during metamorphosis in Atlantic halibut, Hippoglossus hippoglossus, was investigated. Exogenous T4 was given in daily doses of 0.1, 0.05 ppm or a control treatment to halibut larvae at 550 daydegrees (posthatch, premetamorphic) for 14 days. Water depths of 40 cm, 10 cm or 1.5 cm were used to rear halibut larvae from 590 daydegrees for 21 days. Halibut larvae given exogenous T4 at 0.1 ppm had accelerated eye migration relative to MH in fish given 0.05 ppm and in control fish. Pigmentation was correlated with dosage after 14 days. The volume of thyroid tissue was expressed in a dose-dependent manner and exhibited a size-dependency within each treatment. However, the follicles were atypical with reduced colloid, increased lumen and low epithelial cells even in the control group. The results indicate that T4 is a mediator in halibut metamorphosis. In the water depth experiment, only cortisol levels of larvae reared in 1.5 cm water were significantly affected after 21 days, but this was not correlated with metamorphic rate. Hormone profiles, morphological changes and size suggest the existence of a window of opportunity for metamorphosis in halibut extending from about 16 mm and tapering off about 21 mm SL. The pooled hormone profiles indicate the commencement of a hormonal cascade similar to that of other flatfishes during metamorphosis. The results indicate that growth, neural and skeletal transformation, and pigmentation are biochemically separate processes in the metamorphosis of Atlantic halibut. 相似文献
72.
Puffer AM Fite JE French JA Rukstalis M Hopkins EC Patera KJ 《American journal of primatology》2004,64(1):29-37
Behavioral and endocrine suppression of reproduction in subordinate females produces the high reproductive skew that characterizes callitrichid primate mating systems. Snowdon et al. [American Journal of Primatology 31:11-21, 1993] reported that the eldest daughters in tamarin families exhibit further endocrinological suppression immediately following the birth of siblings, and suggested that dominant females exert greater control over subordinate endocrinology during this energetically challenging phase of reproduction. We monitored the endocrine status of five Wied's black tufted-ear marmoset daughters before and after their mother delivered infants by measuring concentrations of urinary estradiol (E(2)), pregnanediol glucuronide (PdG), testosterone (T), and cortisol (CORT). Samples were collected from marmoset daughters 4 weeks prior to and 9 weeks following three consecutive sibling-litter births when the daughters were prepubertal (M=6.1 months of age), peripubertal (M=11.9 months), and postpubertal (M=17.6 months). The birth of infants was associated with reduced ovarian steroid excretion only in the prepubertal daughters. In contrast, ovarian steroid levels tended to increase in the postpubertal daughters. Urinary E(2) and T levels in the postpubertal daughters were 73.8% and 37.6% higher, respectively, in the 3 weeks following the birth of infants, relative to prepartum levels. In addition, peak urinary PdG concentrations in peri- and postpubertal daughters were equivalent to luteal phase concentrations in nonpregnant, breeding adult females, and all of the peri- and postpubertal daughters showed clear ovulatory cycles. Cortisol excretion did not change in response to the reproductive status of the mother, nor did the concentrations change across age. Our data suggest that marmoset daughters of potential breeding age are not hormonally suppressed during the mother's peripartum period or her return to fertility. These findings provide an additional example of species diversity in the social regulation of reproduction in callitrichid primates. 相似文献
73.
The chemical composition of the vomeronasal organ (VNO) was investigated by means of in vitro proton magnetic resonance spectroscopy (MRS) in prepubertal and adult mice of both sexes. Results demonstrate that MRS detects several chemical constituents in the VNO, showing their age- and sex-associated changes in concentration. Preliminary experiments also suggest the ability of MRS to show compositional changes in the VNO after pheromonal stimulation. MRS can serve as a useful technique to investigate vomeronasal chemoreception. 相似文献
74.
Aging is associated with a decline in immunity described as immunosenescence. This is paralleled by a decline in the production of several hormones, as typically illustrated by the menopausal loss of ovarian oestrogen production. However, other hormonal changes that occur with aging and that potentially impact on immune function include the release of the pineal gland hormone melatonin and pituitary growth hormone, adrenal production of dehydroepiandrosterone and tissue-specific availability of active vitamin D. It remains to be established whether hormonal changes with aging actually contribute to immunosenescence and this area is at the interface of fact and fiction, clearly inviting systematic research efforts. As a step in this direction, the present review summarizes established facts on the physiology of secretion and function of hormones that, in most cases, decline with aging and that are likely to affect the immune system. 相似文献
75.
Catheter-associated urinary tract infections (CAUTIs) are the most common kind of nosocomial infection. Recent years have seen a significant increase in numbers of infections caused by yeasts of the genus Candida. The adherence of a microorganism to the host surface is a decisive factor in the success of colonization and the pathogenesis of infection. The objective of this work was to evaluate the adherence of species of the genus Candida to urinary catheters. In vitro adherence to the sections of latex and silicon catheters of Candida albicans and Candida parapsilosis were studied. Adherence was measured by counting the number of adhering viable cells and the results were expressed as Colonies Forming Units per mL. The results demonstrated that the latex catheter facilitated adherence more than the silicon catheter (p < 0.01). The adherence of the C. albicans was significantly greater than C. parapsilosis on latex, but it was similar on silicon. 相似文献
76.
77.
Bellés M Albina ML Sanchez DJ Corbella J Domingo JL 《Biological trace element research》2001,79(1):67-81
The present study was conducted to assess in rats the effects of oral aluminum (Al) exposure on calcium (Ca), magnesium (Mg),
manganese (Mn), copper (Cu), zinc (Zn), and iron (Fe) accumulation and urinary excretion. Three groups of plug-positive Sprague-Dawley
(SD) rats were given by gavage 0, 200, and 400 mg/kg/d of Al(OH)3 on gestational days 1–20. Three groups of nonpregnant female SD rats of the same age received Al(OH)3 by gavage at the same doses for 20 consecutive days. At the end of the treatment period, 24-h urine samples were collected
for analysis of Al and essential elements. Subsequently, all animals were sacrificed and samples of liver, bone, spleen, kidneys,
and brain were removed for metal analyses. With some exceptions, the urinary amounts of Al, Mn, and Cu excreted by pregnant
animals as well as the urinary levels of Al excreted by nonpregnant rats were higher in the Al-treated groups than in the
respective control groups. Although higher Al levels were found in the liver of pregnant rats, the concentrations of Al in
the brain of these animals were lower than those found in the same tissues of nonpregnant rats. With regard to the essential
elements, tissue accumulation was most affected in pregnant than in nonpregnant animals. In pregnant rats, the hepatic and
renal concentrations of Ca, Mg, Mn, Cu, Zn, and Fe, as well as the levels of Ca in bone, and the concentrations of Cu in brain
were significantly higher in the Al-exposed groups than in the control group. According to the current results, oral Al exposure
during pregnancy can produce significant changes in the tissue distribution of a number of essential elements. 相似文献
78.
Kurosaka Y Ishida Y Yamamura E Takase H Otani T Kumon H 《Microbiology and immunology》2001,45(1):9-15
This study established a rat model of foreign body-associated urinary tract infection. A spiral polyethylene tube (PT) was placed transurethrally into the bladder without surgical manipulation, followed by transurethral inoculation with Pseudomonas aeruginosa. The persistence of P. aeruginosa in the kidneys and bladder was significantly enhanced by placement of the PT, whereas the bacteria were eliminated rapidly from the urinary tract in the animals without the PT. Scanning electron microscopy revealed a thick biofilm on the surface of the PT from the early stage of infection. Histopathologically, acute pyelonephritis was followed by chronic renal inflammation as well as continuous and sporadic polymorphonuclear leukocyte accumulation and hemorrhage in the pelvis and adjacent tissues, suggesting continuous ascending introduction of the bacteria from the biofilm adhering to the PT. We believe our model simulates the pathophysiology of foreign body-associated urinary tract infection characterized by biofilm formation on the surface of a foreign body. 相似文献
79.
Sharrow SD Vaughn JL Zídek L Novotny MV Stone MJ 《Protein science : a publication of the Protein Society》2002,11(9):2247-2256
Mouse major urinary proteins (MUPs) have been proposed to play a role in regulating the release and capture of pheromones. Here, we report affinity measurements of five recombinant urinary MUP isoforms (MUPs-I, II, VII, VIII, and IX) and one recombinant nasal isoform (MUP-IV) for each of three pheromonal ligands, (+/-)-2-sec-butyl-4,5-dihydrothiazole (SBT), 6-hydroxy-6-methyl-3-heptanone (HMH), and (+/-)dehydro-exo-brevicomin (DHB). Dissociation constants for all MUP-pheromone pairs were determined by isothermal titration calorimetry, and data for SBT were corroborated by measurements of intrinsic protein fluorescence. We also report the isolation of MUP-IV protein from mouse nasal extracts, in which MUP-IV mRNA has been observed previously. The affinity of each MUP isoform for SBT (K(d) approximately 0.04 to 0.9 micro M) is higher than that for DHB (K(d) approximately 26 to 58 micro M), which in turn is higher than that for HMH (K(d) approximately 50 to 200 micro M). Isoforms I, II, VIII, and IX show very similar affinities for each of the ligands. MUP-VII has approximately twofold higher affinity for SBT but approximately twofold lower affinity for the other pheromones, whereas MUP-IV has approximately 23-fold higher affinity for SBT and approximately fourfold lower affinity for the other pheromones. The variations in ligand affinities of the MUP isoforms are consistent with structural differences in the binding cavities of the isoforms. The data indicate that the concentrations of available pheromones in urine may be influenced by changes in the expression levels of urinary MUPs or the excretion levels of other MUP ligands. The variation in pheromone affinities of the urinary MUP isoforms provides only limited support for the proposal that MUP heterogeneity plays a role in regulating profiles of available pheromones. However, the binding data support the proposed role of nasal MUPs in sequestering pheromones and possibly transporting them to their receptors. 相似文献
80.
Brown ghost knife fish, Apteronotus leptorhynchus, continually emit a weakly electric discharge that serves as a communication signal and is sensitive to sex steroids. Males modulate this signal during bouts of aggression by briefly (approximately 15 ms) increasing the discharge frequency in signals termed "chirps." The present study examined the effects of short-term (1-7 days) and long-term (6-35 days) male-male interaction on the continuous electric organ discharge (EOD), chirping behavior, and plasma levels of cortisol and two androgens, 11-ketotestosterone (11KT) and testosterone. Males housed in isolation or in pairs were tested for short-term and long-term changes in their EOD frequency and chirping rate to standardized sinusoidal electrical stimuli. Within 1 week, chirp rate was significantly higher in paired fish than in isolated fish, but EOD frequency was equivalent in these two groups of fish. Plasma cortisol levels were significantly higher in paired fish than in isolated fish, but there was no difference between groups in plasma 11KT levels. Among paired fish, cortisol levels correlated positively with chirp rate. To determine whether elevated cortisol can cause changes in chirping behavior, isolated fish were implanted with cortisol-filled or empty Silastic tubes and tested for short-term and long-term changes in electrocommunication signals and steroid levels. After 2 weeks, fish that received cortisol implants showed higher chirp rates than blank-implanted fish; there were no difference between groups in EOD frequency. Cortisol implants significantly elevated plasma cortisol levels compared to blank implants but had no effect on plasma 11KT levels. These results suggest that male-male interaction increases chirp rate by elevating levels of plasma cortisol, which, in turn, acts to modify neural activity though an 11KT-independent mechanism. 相似文献