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11.
The life history and ecology of a harpacticoid copepod, Apolethon sp., were investigated for one year in the intertidal zone of a subarctic bay in southeastern Alaska. Core samples were collected biweekly at the 0 m tidal level from March, 1992 through March, 1993; zonation and vertical distribution were determined from additional samples. Large seasonal variations in density of Apolethon sp. parallelled that of the total harpacticoid community, with highest densities (124.3±12.5 10 cm–2; mean ± standard error) in March and lowest densities in May and October (7.6±4.5). The sex ratio of Apolethon sp. varied directly with population density, varying from <0.1 to 1.2 (male:female) during the study period. The species was restricted to a relatively narrow vertical band within the intertidal zone, having its greatest density at – 1 m and being rare above + 1 m tidal height. Adult Apolethon sp. bear conspicuous ovoid mucin structures located laterally on the genital double-somite. The mucin structures are unique to the species; several putative functions are discussed. 相似文献
12.
Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro
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The effects of liquid fluorocarbons as bathing media were determined by use of in vitro neuromuscular preparations. Rat hemidiaphragms were bathed in either oxygenated fluorocarbon (FC) emulsion or standard oxygenated Krebs solution. Contractile force in response to simple supramaximal nerve stimuli as well as to high frequency stimulation was greater, while twitch:tetanus ratio was smaller in FC emulsion. With such medium, post-tetanic potentiation of contraction was also more consistently observed. Indirectly stimulated diaphragms survived longer in FC emulsion. After cessation of oxygenation, oxygen tension (ρO(2)) of the medium declined more rapidly with Krebs than with FC emulsion; ρO(2) directly correlated with force of contraction. Similarly, in the chick biventer cervicis preparation, FC emulsion enhanced nerve-stimulated force of contraction; returning the preparation to standard Krebs solution reversed this phenomenon. Dose-resonse curves of muscle contraction in response to acetycholine and KCl administration were shifted upward during FC emulsion superfusion. Frequency of miniature endplate potentials was lower in FC emulsion than that observed in Krebs solution, measured from the same cell of the rat diaphragm. Resting membrane potentials were also greater in muscle cells sampled from FC emulsion-bathed preparations. These data suggest that FC emulsion is superior to standard Krebs solution as a bathing medium for in vitro neuromuscular preparations by virtue of the high solubility of oxygen in it. 相似文献
13.
Carla DB Fernandez Fernanda F Bellentani Glaura SA Fernandes Juliana E Perobelli Ana Paula A Favareto André F Nascimento Antonio C Cicogna Wilma DG Kempinas 《Reproductive biology and endocrinology : RB&E》2011,9(1):32
Background
Obesity is rapidly becoming a worldwide epidemic that affects children and adults. Some studies have shown a relationship between obesity and infertility, but until now it remains controversial. Thus, the aim of the present study was to investigate the effect of high-fat diet-induced obesity on male reproductive parameters. 相似文献14.
Background
Clonal marine organisms exhibit high levels of morphological variation. Morphological differences may be a response to environmental factors but also they can be attributed to accumulated genetic differences due to disruption of gene flow among populations. In this study, we examined the extensive morphological variation (of 14 characters) in natural populations observed in the gorgonian Eunicea flexuosa, a widely distributed Caribbean octocoral. Eco-phenotypic and genetic effects were evaluated by reciprocal transplants of colonies inhabiting opposite ends of the depth gradient and analysis of population genetics of mitochondrial and nuclear genes, respectively. 相似文献15.
Mixing zones between aquatic ecosystems are known diversity hot spots, but so far no study evaluated the effect of mixing waters on bacterial metabolism. Samplings were performed in four of the major Amazonian rivers, and aquatic bacterial production (BP) was measured both before the confluences and in the mixing zones downstream of the confluences. BP in mixing zones was higher than before the confluence in 75% of cases, representing an increase ranging from 31% to more than 1,000% of BP. In most of these cases, the confluence zone was formed by aquatic ecosystems that differed in the water type (environmental conditions and limiting nutrients to BP). The proportional contribution of the water from each source in the mixture had no impact on the outcome of BP in the mixtures, while BP in the mixtures peaked after 12 h of mixing, indicating that the increase in BP can continue downstream from the confluence zone. Overall, the results presented here do not contradict the low aquatic bacterial metabolism suggested for most Amazonian waters, but show that this general pattern may be sprinkled with hot spot areas of high bacterial metabolism in the confluence of aquatic ecosystems. 相似文献
16.
DNA microarrays are being used to comprehensively examine gene expression networks during the plant defense response that
is triggered when a plant encounters a pathogen or an elicitor molecule. In addition to identifying new genes induced during
defense, these studies are providing new insights into the complex pathways governing defense gene regulation. 相似文献
17.
Is there an inner nose? 总被引:3,自引:3,他引:0
Although behavioral and neuropsychological data regarding the existence of
images for odors are inconclusive, reconsideration of earlier EEG work
provides reasonably clear evidence for an inner nose. However, further EEG
studies and neuroimaging data seem essential for conclusive demonstration
of an inner nose.
相似文献
18.
New records of pontarachnid mites (Acari: Hydrachnidia) from the Caribbean island of Puerto Rico are presented. Litarachna lopezae
sp. n., from substrata collected from Bajo de Sico, a mesophotic coral reef ecosystem in Mona Passage off Puerto Rico, is described as new to science. The new species was collected from nearly 70 m depth, the greatest depth from which pontarachnid mites have been found until now. In addition, a Litarachna sp. was also found in association with the tube of the polychaete Sabellastarte magnifica (Shaw, 1800) at the shallow waters of north Puerto Rico. 相似文献
19.
Magdalena Nutu Birgitta Weijdegård Peter Thomas Ann Thurin-Kjellberg Håkan Billig DG Joakim Larsson 《Reproductive biology and endocrinology : RB&E》2009,7(1):89
Background
The controlled beating of cilia of the fallopian tube plays an important role in facilitating the meeting of gametes and subsequently transporting the fertilized egg to its implantation site. Rapid effects of progesterone on ciliary beat frequency have been reported in the fallopian tubes of cows, but the identity of the receptors mediating this non-genomic action of progesterone is not known. We recently identified a member of the non-genomic membrane progesterone receptor family, mPR gamma, as a candidate for mediating these actions of progesterone. Here, we investigated the possible presence of a related receptor, mPR beta, in the fallopian tubes of mice and women as well as the possible hormonal regulation of mPR beta and gamma. 相似文献20.
Damian DG Gessler Gary S Schiltz Greg D May Shulamit Avraham Christopher D Town David Grant Rex T Nelson 《BMC bioinformatics》2009,10(1):309-21