ABSTRACT: Photoperiod regulates genes encoding melanocortin 3 and serotonin receptors, and secretogranins expressed in the dmpARC of the Siberian hamster
Project description:The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster is currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study was conducted to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified in the dmpARC several photoperiodically regulated genes that are known to have roles in secretory and intracellular signaling pathways. These include secretogranin III (SgIII) and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signaling pathway), all of which increase in expression in short photoperiod. The spatial relationship between receptor signaling and potential secretory pathways was investigated by dual in situ hybridization, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurons expressing VGF mRNA and that a sub-population (approximately 40%) of these neurons express MC3-R. These gene expression changes in dmpARC neurons may reflect the functional requirement of these neurons for seasonal physiology responses of the hamster Samples were taken from 10 individual animals, 5 of which had lived under a short day (SD) photoperiod, the other 5 under a long day (LD) photoperiod. Each hybridisation compared a LD sample (labelled with Cy5) with a SD sample (labelled with Cy3).
Project description:The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster is currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study was conducted to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified in the dmpARC several photoperiodically regulated genes that are known to have roles in secretory and intracellular signaling pathways. These include secretogranin III (SgIII) and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signaling pathway), all of which increase in expression in short photoperiod. The spatial relationship between receptor signaling and potential secretory pathways was investigated by dual in situ hybridization, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurons expressing VGF mRNA and that a sub-population (approximately 40%) of these neurons express MC3-R. These gene expression changes in dmpARC neurons may reflect the functional requirement of these neurons for seasonal physiology responses of the hamster
Project description:With the goal to contribute for the understanding of satellite DNA evolution and its genomic involvement, in this work it was isolated and characterized the first satellite DNA (PSUcentSat) from Phodopus sungorus (Cricetidae). Physical mapping of this sequence in P. sungorus showed large PSUcentSat arrays located at the heterochromatic (peri)centromeric region of five autosomal pairs and Y-chromosome. The presence of orthologous PSUcentSat sequences in the genomes of other Cricetidae and Muridae rodents was also verified, presenting however, an interspersed chromosomal distribution. This distribution pattern suggests a PSUcentSat-scattered location in an ancestor of Muridae/Cricetidae families, that assumed afterwards, in the descendant genome of P. sungorus a restricted localization to few chromosomes in the (peri)centromeric region. We believe that after the divergence of the studied species, PSUcentSat was most probably highly amplified in the (peri)centromeric region of some chromosome pairs of this hamster by recombinational mechanisms. The bouquet chromosome configuration (prophase I) possibly displays an important role in this selective amplification, providing physical proximity of centromeric regions between chromosomes with similar size and/or morphology. This seems particularly evident for the acrocentric chromosomes of P. sungorus (including the Y-chromosome), all presenting large PSUcentSat arrays at the (peri)centromeric region. The conservation of this sequence in the studied genomes and its (peri)centromeric amplification in P. sungorus strongly suggests functional significance, possibly displaying this satellite family different functions in the different genomes. The verification of PSUcentSat transcriptional activity in normal proliferative cells suggests that its transcription is not stage-limited, as described for some other satellites.
Project description:Papillomaviruses (PVs) are considered highly species-specific with cospeciation as the main driving force in their evolution. However, a recent increase in the available PV genome sequences has revealed inconsistencies in virus-host phylogenies, which could be explained by adaptive radiation, recombination, host-switching events and a broad PV host range. Unfortunately, with a relatively low number of animal PVs characterized, understanding these incongruities remains elusive. To improve knowledge of biology and the spread of animal PV, we collected 60 swabs of the anogenital and head and neck regions from a healthy colony of 30 Roborovski hamsters (Phodopus roborovskii) and detected PVs in 44/60 (73.3%) hamster samples. This is the first report of PV infection in Roborovski hamsters. Moreover, Phodopus sungorus papillomavirus type 1 (PsuPV1), previously characterized in Siberian hamsters (Phodopus sungorus), was the only PV detected in Roborovski hamsters. In addition, after a detailed literature search, review and summary of published evidence and construction of a tanglegram linking the cladograms of PVs and their hosts, our findings were discussed in the context of available knowledge on PVs described in at least two different host species.