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- Guilford, Tim, et al.
(author)
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Migratory navigation in birds: new opportunities in an era of fast-developing tracking technology
- 2011
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In: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 214:22, s. 3705-3712
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Journal article (other academic/artistic)abstract
- Birds have remained the dominant model for studying the mechanisms of animal navigation for decades, with much of what has been discovered coming from laboratory studies or model systems. The miniaturisation of tracking technology in recent years now promises opportunities for studying navigation during migration itself (migratory navigation) on an unprecedented scale. Even if migration tracking studies are principally being designed for other purposes, we argue that attention to salient environmental variables during the design or analysis of a study may enable a host of navigational questions to be addressed, greatly enriching the field. We explore candidate variables in the form of a series of contrasts (e. g. land vs ocean or night vs day migration), which may vary naturally between migratory species, populations or even within the life span of a migrating individual. We discuss how these contrasts might help address questions of sensory mechanisms, spatiotemporal representational strategies and adaptive variation in navigational ability. We suggest that this comparative approach may help enrich our knowledge about the natural history of migratory navigation in birds.
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- Shukla, Padma Kant
(author)
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Excitation of electrostatic ion-cyclotron-like modes by the electron density ripple in dusty magnetoplasmas
- 2009
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In: Journal of Plasma Physics. - New York : Cambridge University Press. - 0022-3778 .- 1469-7807. ; 75, s. 433-436
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Journal article (other academic/artistic)abstract
- It is shown that electrostatic ion-eyelotron (EIC)-like modes can be excited by the pre-existing electron density ripple across the external magnetic field in a dusty magnetoplasma. For this purpose, we use the ion continuity and momentum equations, together with the Boltzmann-distributed electrons, and derive the standard Mathieu equation. The latter admits unstable solutions, demonstrating that the EIC-like modes in dusty magnetoplasms can be driven due to the free energy in the electron density ripple. the electron density ripple.
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| 7. |
- Van Booven, Derek, et al.
(author)
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Alcohol use disorder causes global changes in splicing in the human brain
- 2021
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In: Translational Psychiatry. - : SPRINGERNATURE. - 2158-3188. ; 11:1
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Journal article (peer-reviewed)abstract
- Alcohol use disorder (AUD) is a widespread disease leading to the deterioration of cognitive and other functions. Mechanisms by which alcohol affects the brain are not fully elucidated. Splicing constitutes a nuclear process of RNA maturation, which results in the formation of the transcriptome. We tested the hypothesis as to whether AUD impairs splicing in the superior frontal cortex (SFC), nucleus accumbens (NA), basolateral amygdala (BLA), and central nucleus of the amygdala (CNA). To evaluate splicing, bam files from STAR alignments were indexed with samtools for use by rMATS software. Computational analysis of affected pathways was performed using Gene Ontology Consortium, Gene Set Enrichment Analysis, and LncRNA Ontology databases. Surprisingly, AUD was associated with limited changes in the transcriptome: expression of 23 genes was altered in SFC, 14 in NA, 102 in BLA, and 57 in CNA. However, strikingly, mis-splicing in AUD was profound: 1421 mis-splicing events were detected in SFC, 394 in NA, 1317 in BLA, and 469 in CNA. To determine the mechanism of mis-splicing, we analyzed the elements of the spliceosome: small nuclear RNAs (snRNAs) and splicing factors. While snRNAs were not affected by alcohol, expression of splicing factor heat shock protein family A (Hsp70) member 6 (HSPA6) was drastically increased in SFC, BLA, and CNA. Also, AUD was accompanied by aberrant expression of long noncoding RNAs (lncRNAs) related to splicing. In summary, alcohol is associated with genome-wide changes in splicing in multiple human brain regions, likely due to dysregulation of splicing factor(s) and/or altered expression of splicing-related lncRNAs.
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- van Dijk Härd, Iris F
(author)
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Human antibody repertoires in normal physiology and in autoimmune disease
- 2000
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Doctoral thesis (other academic/artistic)abstract
- The immune system has to balance the need for a broad protection from infectious agents against the risk of developing autoimmune disease. The elements of the immune system should provide clues about conditions under which physiological autoreactivity may develop into autoaggressive immunity, if analyzed against the background of the immune system in healthy individuals. A possible object for this analysis is the antibody repertoire, since antibodies have been implicated in the effector phase and etiology of several autoimmune diseases. Therefore, we studied utilization of the genes coding for the variable part of the immunoglobulin molecule in healthy individuals as well as in patients with autoimmune disease, using RNA in situ hybridization and a newly developed competitive quantitative DNA-based PCR. For the analysis of gene utilization and mutational frequencies, we used a VH-family specific PCR in combination with cloning and nucleotide sequence analysis. Our results demonstrate that in adults the VH gene family repertoire is remarkably stable in time, as well as very similar between individuals of similar genetic backgrounds. We also found differences in VH, D and JH expression between lymphocytes from the spleen and from peripheral blood. On the level of the single gene we found, in healthy individuals, an age-related differential utilization of D and JH genes and an impaired affinity maturation in VH6-containing rearrangements. The number of cells carrying mutations decreased with age, as did the number of mutations per gene. To learn more about the possible role of B cell repertoires in the pathogenesis of autoimmune aggression, we studied two autoimmune diseases: IDDM (insulin dependent diabetes mellitus) as a model for a T cell mediated disease, and AITP (autoimmune idiopathic thrombocytopenic purpura) as a model for an antibody mediated disease. On VH gene family level, our results show an increase in VH6 gene utilization in the spleen of AITP patients. Interestingly, this change occurs in small resting lymphocytes rather than in naturally activated ones, indicating the absence of selection and actual utilization of the VH6 gene in these patients. This was confirmed by a sequence analysis of recombinations containing the VH6 gene, in which we found low mutational frequencies in functional VH6-containing recombinations both in AITP and in IDDM patients. Among non- functional rearrangements, however, we observed an increase in mutational frequencies in VH6-containing recombinations that appeared to be based in part on different mechanisms. In IDDM patients, the higher mutational frequencies were due both to an increase in the relative number of VH6 genes carrying mutations and to an actual increase in the number of mutations per gene, which suggests the presence of a high number of activated and differentiated B cells in the periphery. In AITP patients, however, only the number of clones that carried mutations was increased. In conclusion, the VH gene family repertoire appears to be remarkably stable both in time and between individuals, indicating a strict, genetic control. Deviations found in patients with autoimmune disease indicate a modified selection which, however, does not affect the actual VH gene family repertoire of these patients. Therefore, these deviations are more likely a consequence than a cause of the autoimmune process. The age-related changes found in our studies do not correlate with the changes observed in our two models of autoimmune disease and are therefore not likely to be related to the reported increase in autoreactivity in elderly individuals.
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