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Raquel Chaves - One of the best experts on this subject based on the ideXlab platform.

  • The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia)
    Chromosome Research, 2015
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, Raquel Chaves
    Abstract:

    Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus ) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus . A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other’s domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.

  • The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia)
    Chromosome Research, 2015
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, Raquel Chaves
    Abstract:

    Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus ) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus . A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other’s domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.

  • The involvement of repetitive sequences in the remodelling of karyotypes: the Phodopus genomes (Rodentia, Cricetidae).
    Micron (Oxford England : 1993), 2012
    Co-Authors: Ana Paço, Raquel Chaves, A. Vieira-da-silva, Filomena Adega
    Abstract:

    In this work we characterize the Phodopus roborovskii and Phodopus sungorus karyotypes, describing the constitutive heterochromatin and the telomeric repeats distribution in these chromosomes. In the two species, (peri)centromeric, interstitial and (sub)telomeric C-bands were revealed, presenting a very high colocalization with evolutionary breakpoint regions identified in these karyotypes. Also both species present telomeric sequences located interstitially (ITS), as short ITS blocks or as large ITS blocks, mainly at the (peri)centromeric heterochromatic regions. The number and degree of ITSs amplification varies greatly in the two hamsters, indicating independent evolutionary events of these repeats in each genome. The combination of the data provided interesting insights about the genome organization of these hamster species, also allowing establishing evolutionary considerations on their chromosomes. The obtained results clearly suggest an involvement of the repetitive genomic fraction in the reshaping of P. roborovskii and P. sungorus karyotypes.

  • Construction of repetitive DNA libraries from the genomes of two hamster species, Phodopus sungorus and Phodopus roborovskii (Cricetinae)
    2011
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, A.m.b. Silva, Raquel Chaves
    Abstract:

    We report the construction of two libraries of repetitive sequences from genomes of Phodopus sungorus to Phodopus roborovskii. For this, a series of experimental steps were performed: restriction of P. sungorus or P. roborovskii total genomic DNA, cloning of the restriction products and colony lift hybridization using the restriction products as probes. Sequencing of these repeats revealed 20 different sequences of P. sungorus and 17 of P. roborovskii. Moreover, blast searches revealed that only one of P. roborovskii sequences shares similarity with a known repetitive sequence, a chromosome-specific satellite DNA of the Chinese hamster (Cricetulus griseus, Cricetinae). The remaining sequences seem to correspond to new repetitive DNA elements, isolated for the first time in this work. All the sequences were physically mapped by fluorescent in situ hybridization on chromosomes of species of origin. C banding performed after in situ hybridization revealed that hybridization patterns of these sequences are consistent with the distribution of C-positive bands. Here, we present results that show different and diverse chromosomal distributions of these sequences: some of them are almost chromosome-specific, while some are distributed genome-wide, displaying (peri)centromeric, interstitial or telomeric locations in several autosomal pairs and/or sex chromosomes.

Ana Paço - One of the best experts on this subject based on the ideXlab platform.

  • The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia)
    Chromosome Research, 2015
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, Raquel Chaves
    Abstract:

    Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus ) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus . A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other’s domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.

  • The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia)
    Chromosome Research, 2015
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, Raquel Chaves
    Abstract:

    Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus ) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus . A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other’s domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.

  • The involvement of repetitive sequences in the remodelling of karyotypes: the Phodopus genomes (Rodentia, Cricetidae).
    Micron (Oxford England : 1993), 2012
    Co-Authors: Ana Paço, Raquel Chaves, A. Vieira-da-silva, Filomena Adega
    Abstract:

    In this work we characterize the Phodopus roborovskii and Phodopus sungorus karyotypes, describing the constitutive heterochromatin and the telomeric repeats distribution in these chromosomes. In the two species, (peri)centromeric, interstitial and (sub)telomeric C-bands were revealed, presenting a very high colocalization with evolutionary breakpoint regions identified in these karyotypes. Also both species present telomeric sequences located interstitially (ITS), as short ITS blocks or as large ITS blocks, mainly at the (peri)centromeric heterochromatic regions. The number and degree of ITSs amplification varies greatly in the two hamsters, indicating independent evolutionary events of these repeats in each genome. The combination of the data provided interesting insights about the genome organization of these hamster species, also allowing establishing evolutionary considerations on their chromosomes. The obtained results clearly suggest an involvement of the repetitive genomic fraction in the reshaping of P. roborovskii and P. sungorus karyotypes.

  • Construction of repetitive DNA libraries from the genomes of two hamster species, Phodopus sungorus and Phodopus roborovskii (Cricetinae)
    2011
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, A.m.b. Silva, Raquel Chaves
    Abstract:

    We report the construction of two libraries of repetitive sequences from genomes of Phodopus sungorus to Phodopus roborovskii. For this, a series of experimental steps were performed: restriction of P. sungorus or P. roborovskii total genomic DNA, cloning of the restriction products and colony lift hybridization using the restriction products as probes. Sequencing of these repeats revealed 20 different sequences of P. sungorus and 17 of P. roborovskii. Moreover, blast searches revealed that only one of P. roborovskii sequences shares similarity with a known repetitive sequence, a chromosome-specific satellite DNA of the Chinese hamster (Cricetulus griseus, Cricetinae). The remaining sequences seem to correspond to new repetitive DNA elements, isolated for the first time in this work. All the sequences were physically mapped by fluorescent in situ hybridization on chromosomes of species of origin. C banding performed after in situ hybridization revealed that hybridization patterns of these sequences are consistent with the distribution of C-positive bands. Here, we present results that show different and diverse chromosomal distributions of these sequences: some of them are almost chromosome-specific, while some are distributed genome-wide, displaying (peri)centromeric, interstitial or telomeric locations in several autosomal pairs and/or sex chromosomes.

Filomena Adega - One of the best experts on this subject based on the ideXlab platform.

  • The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia)
    Chromosome Research, 2015
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, Raquel Chaves
    Abstract:

    Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus ) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus . A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other’s domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.

  • The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia)
    Chromosome Research, 2015
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, Raquel Chaves
    Abstract:

    Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus ) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus . A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other’s domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.

  • The involvement of repetitive sequences in the remodelling of karyotypes: the Phodopus genomes (Rodentia, Cricetidae).
    Micron (Oxford England : 1993), 2012
    Co-Authors: Ana Paço, Raquel Chaves, A. Vieira-da-silva, Filomena Adega
    Abstract:

    In this work we characterize the Phodopus roborovskii and Phodopus sungorus karyotypes, describing the constitutive heterochromatin and the telomeric repeats distribution in these chromosomes. In the two species, (peri)centromeric, interstitial and (sub)telomeric C-bands were revealed, presenting a very high colocalization with evolutionary breakpoint regions identified in these karyotypes. Also both species present telomeric sequences located interstitially (ITS), as short ITS blocks or as large ITS blocks, mainly at the (peri)centromeric heterochromatic regions. The number and degree of ITSs amplification varies greatly in the two hamsters, indicating independent evolutionary events of these repeats in each genome. The combination of the data provided interesting insights about the genome organization of these hamster species, also allowing establishing evolutionary considerations on their chromosomes. The obtained results clearly suggest an involvement of the repetitive genomic fraction in the reshaping of P. roborovskii and P. sungorus karyotypes.

  • Construction of repetitive DNA libraries from the genomes of two hamster species, Phodopus sungorus and Phodopus roborovskii (Cricetinae)
    2011
    Co-Authors: Ana Paço, Filomena Adega, Nevenka Meštrović, Miroslav Plohl, A.m.b. Silva, Raquel Chaves
    Abstract:

    We report the construction of two libraries of repetitive sequences from genomes of Phodopus sungorus to Phodopus roborovskii. For this, a series of experimental steps were performed: restriction of P. sungorus or P. roborovskii total genomic DNA, cloning of the restriction products and colony lift hybridization using the restriction products as probes. Sequencing of these repeats revealed 20 different sequences of P. sungorus and 17 of P. roborovskii. Moreover, blast searches revealed that only one of P. roborovskii sequences shares similarity with a known repetitive sequence, a chromosome-specific satellite DNA of the Chinese hamster (Cricetulus griseus, Cricetinae). The remaining sequences seem to correspond to new repetitive DNA elements, isolated for the first time in this work. All the sequences were physically mapped by fluorescent in situ hybridization on chromosomes of species of origin. C banding performed after in situ hybridization revealed that hybridization patterns of these sequences are consistent with the distribution of C-positive bands. Here, we present results that show different and diverse chromosomal distributions of these sequences: some of them are almost chromosome-specific, while some are distributed genome-wide, displaying (peri)centromeric, interstitial or telomeric locations in several autosomal pairs and/or sex chromosomes.

Katherine E. Wynne-edwards - One of the best experts on this subject based on the ideXlab platform.

  • In Three Brain Regions Central to Maternal Behaviour, Neither Male Nor Female Phodopus Dwarf Hamsters Show Changes in Oestrogen Receptor Alpha Distribution with Mating or Parenthood
    Journal of neuroendocrinology, 2008
    Co-Authors: Mary E. Timonin, Bruce S. Cushing, Katherine E. Wynne-edwards
    Abstract:

    Oestrogen receptor (ER)alpha immunoreactivity in three brain regions relevant to maternal behaviour (medial preoptic area, bed nucleus of the stria terminalis and medial amygdala) was measured in two species of dwarf hamster that both mate during a postpartum oestrous but differ in expression of paternal behaviour. Male and female Phodopus campbelli and Phodopus sungorus were sampled as sexually naive adults, following mating to satiety, and as new parents. In all brain regions, females expressed higher levels of ER alpha than males. Species did not have an effect on ER alpha distribution except in the medial amygdala, where P. sungorus females had higher expression levels than all other groups. Behavioural status was not associated with altered ER alpha expression. These results were not expected for females and suggest that a primary activational role for oestrogen, acting through ER alpha in these regions, does not generalize to maternal behaviour in Phodopus. In males, these results are consistent with previous manipulations of the ER alpha ligand, oestrogen, and suggest that paternal behaviour in P. campbelli is likely to be regulated by developmental effects of oestrogen on the brain during early life (similar to Microtus ochrogaster), rather than through activation by oestrogen at the time of fatherhood (similar to Peromyscus californicus).

  • Phodopus campbelli detect reduced photoperiod during development but, unlike Phodopus sungorus, retain functional reproductive physiology.
    Reproduction (Cambridge England), 2006
    Co-Authors: Mary E. Timonin, Ned J. Place, Esther Wanderi, Katherine E. Wynne-edwards
    Abstract:

    Golden (Mesocricetus auratus) and Siberian (Phodopus sungorus) hamsters are widely used as animal models for seasonal reproduction; but M. auratus shows no developmental delay in short days until after sexual maturity, whereas P. sungorus juveniles delay development in short days. As the photoperiodic response of Phodopus campbelli is not well established, litters of the two Phodopus species were gestated and reared under long days (14 h light:10 h darkness) or short days (10 h light:14 h darkness) until 70 days of age. As expected, under short photoperiod P. sungorus showed reduced body, testes, epididymides, uterus, and ovary weight; antral follicles and corpora lutea were absent and vaginae remained closed. Animals moulted to winter pelage, and low concentrations of each of leptin, testosterone, and prolactin were present in male serum. Phodopus campbelli juveniles also responded to the short photoperiod as measured by reduced body, testes, epididymides, and ovary weight. The summer pelage persisted. However, both sexes of P. campbelli developed functional reproduction under 10 h light:14 h darkness. All females had a patent vagina by 10 weeks; ovaries contained antral follicles and corpora lutea, and uteri were not reduced in weight. In males, the concentrations of testosterone, leptin, and prolactin were not reduced by short photoperiod. Developmental patterns in the three species of hamster, therefore, differ and are not predicted by relatedness or latitude of origin. Other ecological traits, such as predictability of summer rainfall, ambient temperature, and differential responses to social cues might be important.

  • Male and female prolactin receptor mRNA expression in the brain of a biparental and a uniparental hamster, Phodopus, before and after the birth of a litter.
    Journal of neuroendocrinology, 2005
    Co-Authors: J. Lau, David R. Grattan, D. A. Lovejoy, Katherine E. Wynne-edwards
    Abstract:

    Prolactin receptor (PRL-R) mRNA transcript level was quantified in the choroid plexus (ChP) of a naturally biparental hamster, Phodopus campbelli, and its otherwise similar, yet nonpaternal, sibling species, Phodopus sungorus. Pair-housed males and females on the day before the birth of their first litter (G17), the day after birth (L1), lactation day 5 (L5), and unpaired animals that were sexually naive, were tested. PRL-R mRNA transcript level relative to total RNA, was evaluated by reverse transcriptase-polymerase chain reaction using primers common to the long- and short-form of the PRL-R in Phodopus. In the ChP, a region implicated in prolactin transport into the central nervous system, females had the expected increase in PRL-R mRNA transcript from dioestrus to L5, consistent with known actions of prolactin. As predicted, males and females of the biparental species were similar, although PRL-R mRNA in naive males was higher than in dioestrus females. Males of the two species also differed as predicted. PRL-R mRNA transcript levels were higher in the biparental males. In addition, P. campbelli males had low PRL-R mRNA at G17 compared to L5. By contrast, non-paternal P. sungorus males had elevated PRL-R mRNA transcript levels on G17 relative to unpaired males. We conclude that PRL-R mRNA in the ChP is differentially regulated before and after birth in a paternal and a nonpaternal male.

  • Estradiol and progesterone in paternal and non-paternal hamsters (Phodopus) becoming fathers: conflict with hypothesized roles
    Hormones and behavior, 2005
    Co-Authors: Jennifer E. Schum, Katherine E. Wynne-edwards
    Abstract:

    Abstract Phodopus campbelli has an extensive paternal behavior repertoire whereas the closely-related Phodopus sungorus is not paternally responsive to a displaced pup. For the first time in a naturally paternal mammal, male estradiol and progesterone were determined during two critical phases: (1) the transition from sexually naive male to paired, expectant father that occurs in the absence of stimuli from pups (sexually naive males, paired males on G8, G12, G15, or G17 of the 18-day gestation) and (2) after pup stimuli became available to the males (paired males on days L1, L3, L5, or L12 of pup development). Hormone concentrations in naive males and between G17 and L1 (as stimuli from the birth and the pups became available to males) were also compared. Paternal responsiveness was tested on L3–L5 and confirmed species differences. Hormone concentrations in naive males were similar in the two species and males of both species had estradiol concentrations as high as fertile adult females. However, in direct contrast to predictions, estradiol concentrations were stable in P. campbelli males but increased before the birth, fell across the birth, and increased over pup development in P. sungorus males. Progesterone concentrations in P. campbelli males increased from G17 to L1 whereas a decrease had been predicted. Testosterone dynamics were consistent with previous studies. Either hormonal facilitation of paternal behavior is a hyper-variable trait that has evolved differently in different species, or, more probably, peripheral hormone concentrations are inadequate to explain the role of sex steroid hormones in paternal behavior.

  • Differences in Endogenous Activity within the Genus Phodopus
    Journal of Mammalogy, 1999
    Co-Authors: Katherine E. Wynne-edwards, A V Surov, A. Yu. Telitzina
    Abstract:

    Timing, distances, and durations of above-ground activity were monitored during three successive years in wild populations of dwarf hamsters ( Phodopus ). Both P. campbelli (Djungarian hamsters) and P. sungorus (Siberian hamsters) were nocturnal. However, P. campbelli arose earlier (before dark or soon after dark versus well after dark) and remained above ground 2.5 times longer than P. sungorus . Longer expeditions allowed female P. campbelli to travel farther than both sexes of P. sungorus at the same speed. In contrast, P. campbelli males were active for the same amount of time as females but travelled almost three times faster, covering much greater distances and larger areas. Patterns of wheel running by females in the laboratory confirmed the earlier onset and longer duration of activity in P. campbelli , demonstrating that differences between species in the wild were not simply responses to different environmental stimuli. Activity before and after dark and prolonged activity throughout the dark are interpreted as evidence that resource acquisition in the colder, drier, more seasonal habitat of P. campbelli requires more energy and time than resource acquisition in habitat of P. sungorus . As such, constraints on energy and time during the breeding season may have been important in the evolution of biparental care in P. campbelli but not P. sungorus .

Andrzej Bartke - One of the best experts on this subject based on the ideXlab platform.

  • Vitamin D (soltriol) target cells in the harderian gland of the Siberian hamster (Phodopus sungorus).
    Cells Tissues Organs, 1993
    Co-Authors: María Del Mar Pérez-delgado, Andrzej Bartke, H. J. Bidmon, Walter E. Stumpf
    Abstract:

    Harderian glands of female and male Siberian hamsters (Phodopus sungorus) were studied after a subcutaneous injection of 3H-dihydroxycholecalciferol (vitamin D, soltriol). Autoradiograms revealed the

  • catecholamines stimulate testicular steroidogenesis in vitro in the siberian hamster Phodopus sungorus
    Biology of Reproduction, 1993
    Co-Authors: Artur Mayerhofer, Andrzej Bartke, Tim Began
    Abstract:

    : We have examined direct effects of catecholamines on testicular testosterone production in a seasonally breeding species, the Siberian hamster, Phodopus sungorus. Testicular parenchyma from gonadally active long photoperiod (LD)-exposed and gonadally regressed short photoperiod (SD)-exposed animals was incubated for 6 h with norepinephrine, epinephrine, beta-adrenoceptor agonist isoproterenol, or alpha-adrenoreceptor agonist phenylephrine (all at 10 microM), as well as with various concentrations of norepinephrine (10 nM-10 microM), and 10 microM norepinephrine with or without hCG (0.7, 3.1, and 12.5 mIU/ml). In addition, effects of alpha-adrenoreceptor antagonist prazosin and beta-adrenoreceptor antagonist propranolol (50 microM) were tested in the incubations containing 10 microM norepinephrine. In the incubations of testes from both LD and SD Siberian hamsters, norepinephrine was most effective in stimulating testosterone production, followed by epinephrine and phenylephrine, while isoproterenol failed to increase testosterone accumulation. The stimulatory effects of norepinephrine were dose-dependent and were prevented by coincubation with prazosin, but not affected by coincubation with propranolol. In combination with various doses of hCG, norepinephrine failed to stimulate testosterone production above the levels obtained with hCG alone. These data indicate that the testicular receptors mediating the action of catecholamines on testicular steroidogenesis in Phodopus sungorus are of the alpha 1-subtype, a result in accordance with a previous study in the golden hamster. However, the results of the present study are strikingly different from the findings obtained in the golden hamster in terms of the effects of photoperiod on the responsiveness of testicular steroidogenesis to catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)

  • Vitamin D (soltriol) target cells in the harderian gland of the Siberian hamster (Phodopus sungorus).
    Acta anatomica, 1993
    Co-Authors: María Del Mar Pérez-delgado, Andrzej Bartke, H. J. Bidmon, Walter E. Stumpf
    Abstract:

    Harderian glands of female and male Siberian hamsters (Phodopus sungorus) were studied after a subcutaneous injection of 3H-dihydroxycholecalciferol (vitamin D, soltriol). Autoradiograms revealed the presence of nuclear concentration of the hormone in certain alveolar cells and in myoepithelial cells. The proportion of labeled cells varied between 5.5 and 19% of the total cell number, with an average of 9.5% in female and 12.4% in male hamsters. The data suggest that the functions of the Harderian gland could undergo seasonal changes under the control of vitamin D.

  • Isolation and culture of testicular macrophages from a seasonally breeding species, Phodopus sungorus. Evidence for functional differences between macrophages from active and regressed testes
    International journal of andrology, 1992
    Co-Authors: D. Mayerhofer, Artur Mayerhofer, Andrzej Bartke
    Abstract:

    We have developed an isolation and cultivation protocol for testicular macrophages from the seasonally breeding Siberian hamster, Phodopus sungorus which allows serum-free culture. Macrophages were isolated from the active testes of adult Phodopus kept in long photoperiod (LD, 18hL:6hD), and from the inactive testes of animals with gonadal regression induced by exposure to a short photoperiod (SD, 6hL;18hD; for 10 weeks). The isolated cells were identified as macrophages by (a) electron microscopy, (b) non-specific phagocytosis, and (c) the presence of Fc-receptors. Treatment of the cultures with oFSH (at 0.5 and 1 micrograms ml-1 for 1 and 4 days) significantly stimulated lactate secretion by testicular macrophages from LD hamsters, as expected from studies in the rat. In marked contrast, oFSH did not affect lactate secretion by testicular macrophages from SD hamsters, or by peritoneal macrophages. To test possible macrophage-Leydig cell interactions, the influence of testicular macrophage-conditioned medium (TM-CM) from FSH-responsive LD macrophage cultures was assessed and compared with the effect of peritoneal macrophage-conditioned medium (PM-CM) on testosterone production by testicular parenchyma from LD hamsters. Unexpectedly, and in contrast to previous reports in rats, testosterone production by testes was inhibited significantly by TM-CM from cultures pretreated with either 0.1 or 0.5 micrograms FSH ml-1. FSH alone stimulated testosterone production (due either to LH contamination or to possible paracrine effects). PM-CM from cultures pretreated with FSH did have an inhibitory effect. It is concluded that: (i) There is indirect evidence for the presence of functional FSH receptors on macrophages from the active testes of Phodopus. (ii) Testicular macrophages from inactive testes of Phodopus are not responsive to FSH, implicating impaired macrophage function in the regressed testes of Phodopus exposed to SD. (iii) Testicular macrophages produce a factor which can inhibit testosterone production by incubated testicular tissue.