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11.
Tripp Nicole K. Kabalan Bana A. Stoeckel James Reisinger Lindsey S. 《Hydrobiologia》2022,849(16):3565-3579
Hydrobiologia - Species are often exposed to novel thermal regimes as a result of anthropogenic activities. Understanding the extent to which populations are locally adapted to the thermal regime... 相似文献
12.
Katja Stoeckel Leif Højvang Nielsen Herbert Fuhrmann Lisa Bachmann 《Acta veterinaria Scandinavica》2011,53(1):1-11
Background
Numerous signaling pathways function in the brain ventricular system, including the most important - GABAergic, glutaminergic and dopaminergic signaling. Purinergic signalization system - comprising nucleotide receptors, nucleotidases, ATP and adenosine and their degradation products - are also present in the brain. However, the precise role of nucleotide signalling pathway in the ventricular system has been not elucidated so far. The aim of our research was the identification of all three elements of purinergic signaling pathway in the porcine brain ventricular system.Results
Besides nucleotide receptors on the ependymocytes surface, we studied purines and pyrimidines in the CSF, including mechanisms of nucleotide signaling in the swine model (Sus scrofa domestica). The results indicate presence of G proteins coupled P2Y receptors on ependymocytes and also P2X receptors engaged in fast signal transmission. Additionally we found in CSF nucleotides and adenosine in the concentration sufficient to P receptors activation. These extracellular nucleotides are metabolised by adenylate kinase and nucleotidases from at least two families: NTPDases and NPPases. A low activity of these nucleotide metabolising enzymes maintains nucleotides concentration in ventricular system in micromolar range. ATP is degraded into adenosine and inosine.Conclusions
Our results confirm the thesis about cross-talking between brain and ventricular system functioning in physiological as well as pathological conditions. The close interaction of brain and ventricular system may elicit changes in qualitative and quantitative composition of purines and pyrimidines in CSF. These changes can be dependent on the physiological state of brain, including pathological processes in CNS. 相似文献13.
14.
Functional changes in sensorimotor representation occur in response to use and lesion throughout life. Emerging evidence suggests that functional changes are paralleled by respective macroscopic structural changes. In the present study we used voxel-based morphometry to investigate sensorimotor cortex in subjects with congenitally malformed upper extremities. We expected increased or decreased grey matter to parallel the enlarged or reduced functional representations we reported previously. More specifically, we expected decreased grey matter values in lateral sensorimotor cortex related to compromised hand function and increased grey matter values in medial sensorimotor cortex due to compensatory foot use. We found a medial cluster of grey matter increase in subjects with frequent, hand-like compensatory foot use. This increase was predominantly seen for lateral premotor, supplementary motor, and motor areas and only marginally involved somatosensory cortex. Contrary to our expectation, subjects with a reduced number of fingers, who had shown shrinkage of the functional hand representation previously, did not show decreased grey matter values within lateral sensorimotor cortex. Our data suggest that functional plastic changes in sensorimotor cortex can be associated with increases in grey matter but may also occur in otherwise macroscopically normal appearing grey matter volumes. Furthermore, macroscopic structural changes in motor and premotor areas may be observed without respective changes in somatosensory cortex. 相似文献
15.
Seston quality controls zebra mussel (Dreissena polymorpha ) energetics in turbid rivers 总被引:3,自引:1,他引:2
Daniel W. Schneider Sharook P. Madon James A. Stoeckel Richard E. Sparks 《Oecologia》1998,117(3):331-341
Feeding processes and energetic balance of zebra mussels were both related to the quantity and quality of natural seston.
Filtration rate and pseudofeces production increased while clearance rate remained constant with increasing seston concentration.
Ingestion rate, assimilation efficiency, and assimilation rate all increased with increasing food quality, measured as the
ratio of organic to inorganic material in the seston. Respiration rate did not change with either food quantity or quality.
As a result, scope for growth declined with decreasing food quality, and fell below 0 cal mg−1 h−1 at an organic:inorganic ratio of 0.5. The association between feeding processes and food quality appears related to a breakdown
in the ability of zebra mussels to selectively ingest high-quality organic particles when the organic content of the seston
is low. Ingestion, assimilation efficiency, assimilation rate and scope for growth were all higher when seston was amended
with an addition of a natural assemblage of algae. Food quality may be a better indicator of environmental conditions suitable
for growth than food quantity. These results suggest that the conditions of high suspended inorganic sediment concentrations
in large turbid rivers represent a difficult growth environment for the zebra mussel.
Received: 12 May 1997 / Accepted: 7 July 1998 相似文献
16.
Summary The rostral zone of the intermediate lobe of the mouse hypophysis can clearly be distinguished from the other lobes of the adenohypophysis, especially from the pars tuberalis and the remainder of the intermediate lobe. It consists almost exclusively of corticotrophic cells which show reactive changes after adrenalectomy. The hypophysial stalk is entirely surrounded by this zone; laterally it forms large cell aggregations which extend dorsally as thin cell strands. The corticotrophs are also found within the hypophysial stalk which they invade along the blood vessels; frequently they are dispersed among the typical cells of the intermediate lobe, especially along the neural lobe and the hypophysial cleft.On leave from the Department of Veterinary Anatomy, University of Missouri, Columbia, Mo., U.S.A. 相似文献
17.
M. E. Stoeckel H. D. Dellmann A. Porte M. J. Klein F. Stutinsky 《Cell and tissue research》1973,136(1):97-110
Summary In the mouse, the rostral zone of the pars intermedia is almost exclusively composed of typical corticotrophic cells. They are located around and even within the neural stalk, at the level of transition between stalk and neural lobe. In the rat, the corticotrophic cells of the rostral zone are found in scattered islets among the MSH producing cells, and also in the neural lobe. In both the rat and mouse, these cells are in direct contact with various types of nerve terminals. Synaptoid contacts with aminergic and neurosecretory nerve fibers are observed. Furthermore they are also closely related to the hypophysial portal vessels. Following adrenalectomy, the cells located in the neurohypophysis always react more intensely than tose in the rostral zone. The functional significance of these corticotrophic cells which are subject to both humoral and neural regulation remains as yet hypothetical. Their participation in neurogenic stress response seems probable. 相似文献
18.
Stoeckel S Grange J Fernández-Manjarres JF Bilger I Frascaria-Lacoste N Mariette S 《Molecular ecology》2006,15(8):2109-2118
Wild cherry (Prunus avium L.), a partially asexual self-incompatible forest tree, shows heterozygote excess, which is a poorly studied phenomenon. In three natural populations, we found significant heterozygote excess at almost all investigated loci (eight microsatellites and markers for the self-incompatibility locus). We examined four hypotheses to account for this observed heterozygote excess. First, negative F(IS) can result from a lack of selfed progeny in small populations of outcrossing species. A second explanation for negative F(IS) is selection during the life cycle of the most heterozygous individuals. A third explanation is negative assortative mating when reproduction occurs between individuals bearing phenotypes more dissimilar than by chance. The last explanation for negative F(IS) relies on asexual reproduction. Expectations for each hypothesis were tested using empirical data. Patterns of F(IS) differed among loci. Nevertheless, our experimental results did not confirm the small sample size hypothesis. Although one locus is probably under a hitch-hiking effect from the SI locus, we rejected the effect of the self-incompatibility locus for the genome as a whole. Similarly, although one locus showed a clear pattern consistent with the selection of heterozygous individuals, the heterosis effect over the whole genome was rejected. Finally, our results revealed that clonality probably explains significant negative F(IS) in wild cherry populations when considering all individuals. More theoretical effort is needed to develop expectations and hypotheses, and test them in the case of species combining self-incompatibility and partially asexual reproduction. 相似文献
19.
Julie Jaquiéry Solenn Stoeckel Chloé Larose Pierre Nouhaud Claude Rispe Lucie Mieuzet Jo?l Bonhomme Frédérique Mahéo Fabrice Legeai Jean-Pierre Gauthier Nathalie Prunier-Leterme Denis Tagu Jean-Christophe Simon 《PLoS genetics》2014,10(12)
Although evolutionary transitions from sexual to asexual reproduction are frequent in eukaryotes, the genetic bases of such shifts toward asexuality remain largely unknown. We addressed this issue in an aphid species where both sexual and obligate asexual lineages coexist in natural populations. These sexual and asexual lineages may occasionally interbreed because some asexual lineages maintain a residual production of males potentially able to mate with the females produced by sexual lineages. Hence, this species is an ideal model to study the genetic basis of the loss of sexual reproduction with quantitative genetic and population genomic approaches. Our analysis of the co-segregation of ∼300 molecular markers and reproductive phenotype in experimental crosses pinpointed an X-linked region controlling obligate asexuality, this state of character being recessive. A population genetic analysis (>400-marker genome scan) on wild sexual and asexual genotypes from geographically distant populations under divergent selection for reproductive strategies detected a strong signature of divergent selection in the genomic region identified by the experimental crosses. These population genetic data confirm the implication of the candidate region in the control of reproductive mode in wild populations originating from 700 km apart. Patterns of genetic differentiation along chromosomes suggest bidirectional gene flow between populations with distinct reproductive modes, supporting contagious asexuality as a prevailing route to permanent parthenogenesis in pea aphids. This genetic system provides new insights into the mechanisms of coexistence of sexual and asexual aphid lineages. 相似文献
20.
Luke E. Stoeckel Lori S. Palley Randy L. Gollub Steven M. Niemi Anne Eden Evins 《PloS one》2014,9(10)
Neural substrates underlying the human-pet relationship are largely unknown. We examined fMRI brain activation patterns as mothers viewed images of their own child and dog and an unfamiliar child and dog. There was a common network of brain regions involved in emotion, reward, affiliation, visual processing and social cognition when mothers viewed images of both their child and dog. Viewing images of their child resulted in brain activity in the midbrain (ventral tegmental area/substantia nigra involved in reward/affiliation), while a more posterior cortical brain activation pattern involving fusiform gyrus (visual processing of faces and social cognition) characterized a mother''s response to her dog. Mothers also rated images of their child and dog as eliciting similar levels of excitement (arousal) and pleasantness (valence), although the difference in the own vs. unfamiliar child comparison was larger than the own vs. unfamiliar dog comparison for arousal. Valence ratings of their dog were also positively correlated with ratings of the attachment to their dog. Although there are similarities in the perceived emotional experience and brain function associated with the mother-child and mother-dog bond, there are also key differences that may reflect variance in the evolutionary course and function of these relationships. 相似文献