Abstract Obtaining representative samples from a term placenta for gene-expression studies is confounded by both within placental heterogeneity and sampling effects such as sample location and ...processing time. Epigenetic processes involved in the regulation of gene expression, such as DNA methylation, may show similar variability, but are less well studied. Therefore, we investigated the nature of within and between- placenta variation in gene expression and DNA methylation of genes that were chosen for being differentially expressed or methylated by cell type within the placenta. Methods In total, two or more samples from each of 38 normal term placentae were utilized. The expression levels of CDH1 , CDH11 , ID2 , PLAC1 and KISS1 were evaluated by real-time PCR. DNA methylation levels of LINE1 elements and CpGs within the promoter regions of KISS1, PTPN6, CASP8, and APC were similarly quantified by pyrosequencing. Results Despite considerable sample-to-sample variability within each placenta, the within-placenta correlation for both gene expression and methylation was significant for each studied gene. Most of this variability was not due to sample location. However, between placental differences in gene expression were inflated by the dramatic effect of processing time (0–24 h) on mRNA levels, particularly for PLAC1 and KISS1 (both expressed in the apical syncytiotrophoblast). In contrast, DNA methylation levels remained relatively constant over this same time period. Conclusion Due to extensive site-to-site variability, multiple sampled sites are needed to accurately represent a placenta for molecular studies. Furthermore, mRNA quantitation of some genes may be hampered by its rapid degradation post-delivery (and possibly perinatally) and thus processing time should be considered in such analyses. Within-placenta correlations in expression and methylation from unrelated genes raise the possibility that methylation and expression variation may potentially reflect cell composition differences between samples rather than true differences occurring at the cellular level.
Abstract We report the timing analysis of PSR J1846−0513, a pulsar discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Commensal Radio Astronomy FAST Survey. The pulsar ...possesses a spin period of 23.36 ms and a spin-down rate ( P ̇ ) of 1.0106(3) × 10 −18 s s −1 , and it is located in an eccentric orbit ( e ∼0.208) with an orbital period of 0.61 days. The characteristic age and surface magnetic field of the pulsar are found to be 366.62 Myr and 4.9178 × 10 9 G, respectively, indicating that it is a recycled pulsar. Using over two years of timing data, we measure the periastron advance ω ̇ = 0.8956(8) deg yr −1 . By assuming that this effect is purely relativistic, we have estimated the total mass M = 2.6287(35) M ⊙ and obtained an upper limit for the pulsar mass and a lower limit for the companion’s mass. Our results indicate that this is a double neutron star system.
The Mode Switching in Pulsar J1326-6700 Wen, Z. G.; Yan, W. M.; Yuan, J. P. ...
The Astrophysical journal,
11/2020, Letnik:
904, Številka:
1
Journal Article
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We report on a detailed study of the mode switching in pulsar J1326−6700 by analyzing the data acquired from the Parkes 64 m radio telescope at 1369 MHz. During the abnormal mode, the emission at the ...central and trailing components becomes extremely weak. Meanwhile, the leading emission shifts toward earlier longitude by almost 2°, and remains in this position for typically less than a minute. The mean flux density of the normal mode is almost five times that of the abnormal mode. Our data show that, for PSR J1326−6700, 85% of the time was spent in the normal mode and 15% was in the abnormal mode. The intrinsic distributions of mode timescales can be well described by Weibull distributions, which present a certain amount of memory in mode switching. Furthermore, a quasiperiodicity has been identified in the mode switching in pulsar J1326−6700. The estimated delay emission heights based on the kinematical effects indicate that the abnormal mode may have originated from higher altitude than the normal mode.
Contactin genes CNTN5 and CNTN6 code for neuronal cell adhesion molecules that promote neurite outgrowth in sensory-motor neuronal pathways. Mutations of CNTN5 and CNTN6 have previously been reported ...in individuals with autism spectrum disorders (ASDs), but very little is known on their prevalence and clinical impact. In this study, we identified CNTN5 and CNTN6 deleterious variants in individuals with ASD. Among the carriers, a girl with ASD and attention-deficit/hyperactivity disorder was carrying five copies of CNTN5. For CNTN6, both deletions (6/1534 ASD vs 1/8936 controls; P=0.00006) and private coding sequence variants (18/501 ASD vs 535/33480 controls; P=0.0005) were enriched in individuals with ASD. Among the rare CNTN6 variants, two deletions were transmitted by fathers diagnosed with ASD, one stop mutation CNTN6
was transmitted by a mother to her two sons with ASD and one variant CNTN6
was found de novo in a boy with ASD. Clinical investigations of the patients carrying CNTN5 or CNTN6 variants showed that they were hypersensitive to sounds (a condition called hyperacusis) and displayed changes in wave latency within the auditory pathway. These results reinforce the hypothesis of abnormal neuronal connectivity in the pathophysiology of ASD and shed new light on the genes that increase risk for abnormal sensory perception in ASD.
Abstract
We report on the pulse-to-pulse energy distribution and longitude-resolved modulation properties of PSR J1631+1252 discovered by the Five-hundred-meter Aperture Spherical radio Telescope. ...Our analysis made use of the data acquired at 1250 MHz from the follow-up timing observations that lasted over a year. PSR J1631+1252 has a rotational period of ∼0.310 s, and a dispersion measure of ∼32.73 pc cm
−3
. The energy distribution is well described by a lognormal distribution, the parameters of which do not vary with time. We show that large modulation occurs across the bridge emission of the pulse profile, with sporadic bright bursts at the leading emission region. The fluctuation spectral analysis reveals the existence of subpulse drifting in the leading component with vertical spacing between the drift bands of 3.28 ± 0.08 pulse periods between consecutive drift bands. Possible physical mechanisms for subpulse drifting are discussed.
Abstract
We have carried out a detailed study of single-pulse emission from the pulsar J2048−1616 (B2045−16), observed at 732, 1369, and 3100 MHz frequencies using the Parkes 64 m radio telescope. ...The pulsar possesses three well-resolved emission components, with the central component resembling core emission. The single pulses show the presence of two distinct periodic modulations using fluctuation spectral analysis. About 12% nulls are found to create alternating bunches of nulls and bursts in a quasiperiodic manner with longer periodicities of 83, 28, and 14 rotational periods for simultaneous observations at 732 and 3100 MHz. At 1369 MHz, the quasiperiodic nulling is detected, as well, to modulate across the entire profile both in the core and conal components simultaneously with a fluctuation rate of about 50 rotational periods, and the nulling fraction is estimated to be around 10%. Additionally, the quasiperiodic modulations are significantly dependent on time. In addition to nulling, the pulsar also presents subpulse drifting in the single-pulse sequences with shorter periodicity. The subpulse drifting is presented in the conal components and is absent in the central core emission. The leading component is modulated in longitude with a period of three pulses. The trailing component remains phase stationary within the pulse window but periodically modulates in amplitude with a period of three pulses. Finally, possible physical mechanisms are discussed.
ABSTRACT
In this study, we report on a detailed single pulse analysis of the radio emission from the pulsar J1401 − 6357 (B1358 − 63) based on data observed with the ultrawideband low-frequency ...receiver on the Parkes radio telescope. In addition to a weak leading component, the integrated pulse profile features a single-humped structure with a slight asymmetry. The frequency evolution of the pulse profile is studied. Well-defined nulls, with an estimated nulling fraction greater than 2 per cent, are present across the whole frequency band. No emission is detected with significance above 3σ in the average pulse profile integrated over all null pulses. Using fluctuation spectral analysis, we reveal the existence of temporal-dependent subpulse drifting in this pulsar for the first time. A clear double-peaked feature is present at exactly the alias border across the whole frequency band, which suggests that the apparent drift sense changes during the observation. Our observations provide further confirmation that the phenomena of pulse nulling and subpulse drifting are independent of observing frequency, which suggest that they invoke changes on the global magnetospheric scale.
Abstract
In this study, we report on a detailed single-pulse analysis of the radio emission from a rotating radio transient (RRAT) J1918−0449, which is discovered with the Five-hundred-meter Aperture ...Spherical radio Telescope (FAST). The sensitive observations were carried out on 2021 April 30 using the FAST with a central frequency of 1250 MHz and a short time resolution of 49.152
μ
s, which forms a reliable basis to probe single-pulse emission properties in detail. The source was successively observed for around 2 hr. A total of 83 dispersed bursts with significance above 6
σ
are detected over 1.8 hr. The source’s dispersion measure (DM) and rotational period are determined to be 116.1 ± 0.4 pc cm
−3
and 2479.21 ± 0.03 ms, respectively. The share of registered pulses from the total number of observed periods is 3.12%. No underlying emission is detected in the averaged off-pulse profile. For bursts with fluence larger than 10 Jy ms, the pulse energy follows a power-law distribution with an index of −3.1 ± 0.4, suggesting the existence of bright pulse emission. We find that the distribution of time between subsequent pulses is consistent with a stationary Poisson process and find no evidence of clustering over the 1.8 hr observations, giving a mean burst rate of one burst every 66 s. Close inspection of the detected bright pulses reveals that 21 pulses exhibit well-defined quasiperiodicities. The subpulse drifting is present in nonsuccessive rotations with periodicity of 2.51 ± 0.06 periods. Finally, possible physical mechanisms are discussed.
We investigate the emission properties of the pulsars that exhibit different drifting subpulses in different pulse profile components based on the model for obliquely rotating pulsar magnetospheres ...of multiple emission states. Emission from subpulses is assumed coming from
m
discrete areas located on carousels around the magnetic axis and flowing at rates determined by the
E
×
B
drift. An emission state is defined by this drift, and a change in the emission state corresponds to a change in the drift velocity. The model is applied to eight pulsars, all displaying drifting subpulses of particular properties along two different drift-bands at different parts of the pulse profile at 21 cm observing wavelength. Simulation is performed to identify the emission states for the different drifting subpulses and the associated values of
m
in the emission region. The results show that drifting subpulses in different profile components correspond to particular emission states and
m
, and that different emission states and
m
can coexist in an emission region. We determine the circulation time for plasma around the magnetosphere and show that it is related to the obliquity angle. By comparing with three other pulsars that display drifting subpulses of a single drift-band, we find that drifting subpulses demonstrate similar properties when considering the different drift-bands separately. We speculate, based on our results, that the coexistence of different drifting subpulses within a pulse profile may require additional mechanism, and the phenomenon is more common in pulsars with small obliquity angle.
Abstract
We report on the variation in the single-pulse emission from PSR J1900+4221 (CRAFTS 19C10) observed at frequency centered at 1.25 GHz using the Five-hundred-meter Aperture Spherical radio ...Telescope. The integrated pulse profile shows two distinct components, referred to here as the leading and trailing components, with the latter component also containing a third weak component. The single-pulse sequence reveals different emissions demonstrating as nulling, regular, and bright pulses, each with a particular abundance and duration distribution. There also exists pulses that follow a log-normal distribution suggesting the possibility of another emission, in which the pulsar is radiating weakly. Changes in the profile shape are seen across different emissions. We examine the emission variations in the leading and trailing components collectively and separately, and find moderate correlation between the two components. The inclination angle is estimated to be about 7° based on pulse-width, and we discuss that nulling in this pulsar does not seem to show correlation with age and rotation period.
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