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71.
Bruno Brambati Lucia Tului Alessandro Lanzani Giuseppe Simoni Maurizio Travi 《黑龙江环境通报》1991,11(10):767-774
Both the principles of first-trimester genetic diagnosis in multiple pregnancy and the special considerations required to avoid potential diagnostic pitfalls are presented. The experience consisted of 65 cases of twins and one case of quadruplets. Dichorionic twins were recognized by sonography in 54 cases. Transabdominal aspiration was generally preferred to trans-cervical for obtaining chorionic tissue, although in two cases both approaches were used. Diagnostic error following erroneous sampling was reported in 3 out of 54 sets of dichorionic twins (5.5 per cent). When like-sex dichorionic twins cannot be differentiated by cytogenetic or DNA polymorphism studies, amniocentesis should be recommended to confirm the reliability of the result on chorionic tissue. 相似文献
72.
de la Torre FR Salibián A Ferrari L 《Environmental pollution (Barking, Essex : 1987)》2000,109(2):277-282
The impact of long-term exposure to waterborne cadmium (Cd) on Cyprinus carpio was evaluated through changes of selected parameters considered as biomarkers of toxicity. Fish were exposed to 1.6 mg l(-1) Cd for 14 days and then transferred to Cd-free water for 19 days. The measured parameters were gill ATPases, brain acetylcholinesterase (AchE), liver glutamate oxaloacetate (GOT) and glutamate pyruvate (GPT) transaminases, muscle water content, and protein content of liver, gills and brain. Condition factor and liver somatic index were also calculated. Branchial ATPase activities were impaired in a dissimilar way: the (Na(+),K(+))-ATPases were inhibited by approximately 30%, while the Mg(2+)-ATPase was significantly activated by 70%. Brain AchE showed no changes after Cd exposure. Both liver GOT and GPT activities were increased by the metal by 63 and 98%. Water content of the skeletal muscle showed no significant alterations. After the 19-day recovery phase, changes in the Mg(2+)-ATPase and GPT were reversed to values similar to controls, but the Cd exposure resulted in an irreversible alteration in GOT activity. Results indicate that the sublethal Cd concentrations are stressful to carp, particularly with reference to branchial enzymes which may disrupt the osmotic and ionic balance of the animals. 相似文献
73.
Grant E. Brown Alix C. Rive Maud C. O. Ferrari Douglas P. Chivers 《Behavioral ecology and sociobiology》2006,61(1):9-16
Prey animals often have to face a dynamic tradeoff between the costs of antipredator behavior and the benefits of other fitness-related activities such as foraging and reproduction. According to the threat-sensitive predator avoidance hypothesis, prey animals should match the intensity of their antipredator behavior to the degree of immediate threat posed by the predator. Moreover, longer-term temporal variability in predation risk (over days to weeks) can shape the intensity of antipredator behavior. According to the risk allocation hypothesis, changing the background level of risk for several days is often enough to change the response intensity of the prey to a given stimulus. As the background level of risk increases, the response intensity of the prey decreases. In this study, we tested for possible interactions between immediate threat-sensitive responses to varying levels of current perceived risk and temporal variability in background risk experienced over the past 3 days. Juvenile convict cichlids were preexposed to either low or high frequencies of predation risk (using conspecific chemical alarm cues) for 3 days and were then tested for a response to one of five concentrations (100, 50, 25, 12.5%, or a distilled water control). According to the threat-sensitive predator avoidance hypothesis, we found greater intensity responses to greater concentrations of alarm cues. Moreover, in accordance with the risk allocation hypothesis, we found that cichlids previously exposed to the high background level of risk exhibited a lower overall intensity response to each alarm cue concentration than those exposed to the low background level of risk. It is interesting to note that we found that the background level of risk over the past 3 days influenced the threshold level of response to varying concentrations of alarm cues. Indeed, the minimum stimulus concentration that evoked a behavioral response was lower for fish exposed to high background levels of predation than those exposed to low background levels of predation. These results illustrate a remarkable interplay between immediate (current) risk and background risk in shaping the intensity of antipredator responses. 相似文献
74.
Chelli–Cheheb Razika Arzarello Marta Arnaud Julie Berto Claudio Cáceres Isabel Caracausi Sandro Colopi Francesco Daffara Sara Canini Guido Montanari Huguet Rosa Karambatsou Theodora Sala Benedetto Zambaldi Maurizio Berruti Gabriele L. F. 《Die Naturwissenschaften》2020,107(4):1-13
The Science of Nature - Female-only colour polymorphism is rare in birds, but occurs in brood parasitic cuckoos (Cuculidae). Obligate brood parasites leave incubation and parental care to other... 相似文献
75.
Summary. Predation is a pervasive selective agent highly variable in space and time. Due to the costs associated with antipredator
responses, prey would be at a selective advantage if they respond to predation threats with an intensitfy matching the threat
posed by the predator. Many aquatic organisms have been shown to use chemical alarm cues present in the water to assess the
level of risk in their environment. This includes mosquito larvae which show antipredator responses to conspecific alarm cues.
In this study, we investigated the nature of the responses of larval mosquitoes Culex restuans to those cues. In our initial observations, we showed pond/population differences in the response intensity of C. restuans to alarm cues. In experiment 1, we showed that the response intensity to alarm cues could be increased by increasing the
background level of risk in the mosquitoes’ environment (by adding salamander predators) and once turned on, the response
intensity to alarm cues was likely maintained for the remainder of the mosquitoes’ aquatic life. In experiments 2 and 3, we
investigated if the increase in response intensity to alarm cues was directly correlated with the level of background risk
in the mosquitoes’ environment. When given increasing levels of background risk, mosquito larvae subsequently showed a graded
response to conspecific alarm cues. This series of experiments demonstrates that the response intensity of larval mosquitoes
to a standard concentration of alarm cues is not fixed, but rather dependent on the background level of risk in the environment.
An understanding of the background level of risk is particularly important for comparing antipredator responses of prey between
habitats. 相似文献
76.
A sampling campaign for the determination of concentrations of nonylphenol isomers (NPs) in freshwaters and sediments of the hydrologic system of the Rieti district (central Italy) was conducted from 2002 to 2003. Eighteen sampling points, selected on the basis of the different human activities in the vicinity, were monitored; six series of water samples (from June 2002 to February 2003) and one of sediment samples (summer 2002) were analyzed by GC/MS.
There was a direct relationship between concentrations of NPs and the presence of urban or industrial activities near the sampling point. However, concentrations of NPs in water were in the range of <0.1–1.4 μg l−1, and their presence limited to short distances from the sources of contamination. Accumulation factors in sediment samples ranged from 102 to 5 × 103. 相似文献
77.
78.
Maurizio Manigrasso Claudio Vernale Pasquale Avino 《Environmental science and pollution research international》2017,24(16):13866-13873
Aerosol pollution in urban environments has been recognized to be responsible for important pathologies of the cardiovascular and respiratory systems. In this perspective, great attention has been addressed to Ultra Fine Particles (UFPs?<?100 nm), because they efficiently penetrate into the respiratory system and are capable of translocating from the airways into the blood circulation. This paper describes the aerosol regional doses deposited in the human respiratory system in a high-traffic urban area. The aerosol measurements were carried out on a curbside in downtown Rome, on a street characterized by a high density of autovehicular traffic. Aerosol number-size distributions were measured by means of a Fast Mobility Particle Sizer in the range from 5.6 to 560 nm with a 1 s time resolution. Dosimetry estimates were performed with the Multiple-Path Particle Dosimetry model by means of the stochastic lung model. The exposure scenario close to traffic is represented by a sequence of short-term peak exposures: about 6.6?×?1010 particles are deposited hourly into the respiratory system. After 1 h of exposure in proximity of traffic, 1.29?×?1010, 1.88?×?1010, and 3.45?×?1010 particles are deposited in the head, tracheobronchial, and alveolar regions. More than 95 % of such doses are represented by UFPs. Finally, according to the greater dose estimated, the right lung lobes are expected to be more susceptible to respiratory pathologies than the left lobes. 相似文献
79.
Dale M. Jefferson Keith A. Hobson Brandon S. Demuth Maud C. O. Ferrari Douglas P. Chivers 《Die Naturwissenschaften》2014,101(4):291-303
Tadpoles show considerable behavioral plasticity. When population densities become high, tadpoles often become cannibalistic, likely in response to intense competition. Conspecific tissues are potentially an ideal diet by composition and should greatly improve growth and development. However, the potential release of alarm cues from the tissues of injured conspecifics may act to deter potential cannibals from feeding. We conducted multiple feeding experiments to test the relative effects that a diet of conspecifics has on tadpole growth and development. Results indicate that while conspecific tissues represent a better alternative to starvation and provide some benefits over low-protein diets, such a diet can have detrimental effects to tadpole growth and/or development relative to diets of similar protein content. Additionally, tadpoles raised individually appear to avoid consuming conspecific tissues and may continue to do so until they suffer from the effects of starvation. However, tadpoles readily fed upon conspecific tissues immediately when raised with competitors. These results suggest that cannibalism may occur as a result of competition rather than the specific quality of available diets, unless such diets lead to starvation. 相似文献
80.
Silvia Lampis Anita Ferrari A. Cristina F. Cunha-Queda Paula Alvarenga Simona Di Gregorio Giovanni Vallini 《Environmental science and pollution research international》2009,16(6):663-670