The relative abundance of the three decay modes B 0 → D − K + , B 0 → D − π + , and B 0 s → D − s π + produced in 7 TeV p p collisions at the LHC is determined from data corresponding to an ...integrated luminosity of 35 pb − 1 . The branching fraction of B 0 → D − K + is found to be B ( B 0 → D − K + ) = ( 2.01 ± 0.18 stat ± 0.14 syst ) × 10 − 4 . The ratio of fragmentation fractions f s / f d is determined through the relative abundance of B 0 s → D − s π + to B 0 → D − K + and B 0 → D − π + , leading to f s / f d = 0.253 ± 0.017 ± 0.017 ± 0.020 , where the uncertainties are statistical, systematic, and theoretical, respectively.
A search is performed for the lepton number violating decay B + → h − μ + μ + , where h − represents a K − or a π − , using an integrated luminosity of 36 pb − 1 of data collected with the LHCb ...detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B ( B + → K − μ + μ + ) < 5.4 × 10 − 8 and B ( B + → π − μ + μ + ) < 5.8 × 10 − 8 are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.
A search is performed for the lepton number violating decay B + → h − μ + μ + , where h − represents a K − or a π − , using an integrated luminosity of 36 pb − 1 of data collected with the LHCb ...detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B ( B + → K − μ + μ + ) < 5.4 × 10 − 8 and B ( B + → π − μ + μ + ) < 5.8 × 10 − 8 are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.
The Λ¯/Λ and Λ¯/K0S production ratios are measured by the LHCb detector from 0.3 nb−1 of pp collisions delivered by the LHC at s√=0.9 TeV and 1.8 nb−1 at s√=7 TeV. Both ratios are presented as a ...function of transverse momentum, p T, and rapidity, y, in the ranges 0.15 < p T < 2.50 GeV/c and 2.0 < y < 4.5. Results at the two energies are in good agreement as a function of rapidity loss, ∆y = y beam − y, and are consistent with previous measurements. The ratio Λ¯/Λ , measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted in simulation, particularly at high rapidity. The ratio Λ¯/K0S , measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected.
The Λ¯/Λ and Λ¯/K0S production ratios are measured by the LHCb detector from 0.3 nb−1 of pp collisions delivered by the LHC at s√=0.9 TeV and 1.8 nb−1 at s√=7 TeV. Both ratios are presented as a ...function of transverse momentum, p T, and rapidity, y, in the ranges 0.15 < p T < 2.50 GeV/c and 2.0 < y < 4.5. Results at the two energies are in good agreement as a function of rapidity loss, ∆y = y beam − y, and are consistent with previous measurements. The ratio Λ¯/Λ , measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted in simulation, particularly at high rapidity. The ratio Λ¯/K0S , measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected.
Spermatozoa of marine invertebrates are attracted to their conspecific female gamete by diffusive molecules, called chemoattractants, released from the egg investments in a process known as ...chemotaxis. The information from the egg chemoattractant concentration field is decoded into intracellular Ca
concentration (Ca
) changes that regulate the internal motors that shape the flagellum as it beats. By studying sea urchin species-specific differences in sperm chemoattractant-receptor characteristics we show that receptor density constrains the steepness of the chemoattractant concentration gradient detectable by spermatozoa. Through analyzing different chemoattractant gradient forms, we demonstrate for the first time that
sperm are chemotactic and this response is consistent with frequency entrainment of two coupled physiological oscillators: i) the stimulus function and ii) the Ca
changes. We demonstrate that the slope of the chemoattractant gradients provides the coupling force between both oscillators, arising as a fundamental requirement for sperm chemotaxis.
Over the last 25 years, researchers, mostly paleontologists, have developed a system of rank-free, phylogenetically defined names for the primary clades of turtles. As these names are not considered ...established by the PhyloCode, the newly created nomenclatural system that governs the naming of clades, we take the opportunity to convert the vast majority of previously defined clade names for extinct and extant turtles into this new nomenclatural framework. Some previously defined names are converted with minor adjustments. We also define a number of new clade names to close apparent nomenclatural gaps. In total, we establish 113 clade names, of which 79 had already received phylogenetic definitions and 34 are new.
Rotavirus genome replication and assembly take place in cytoplasmic electron dense inclusions termed viroplasms (VPs). Previous conventional optical microscopy studies observing the intracellular ...distribution of rotavirus proteins and their organization in VPs have lacked molecular-scale spatial resolution, due to inherent spatial resolution constraints. In this work we employed super-resolution microscopy to reveal the nanometric-scale organization of VPs formed during rotavirus infection, and quantitatively describe the structural organization of seven viral proteins within and around the VPs. The observed viral components are spatially organized as five concentric layers, in which NSP5 localizes at the center of the VPs, surrounded by a layer of NSP2 and NSP4 proteins, followed by an intermediate zone comprised of the VP1, VP2, VP6. In the outermost zone, we observed a ring of VP4 and finally a layer of VP7. These findings show that rotavirus VPs are highly organized organelles.
We have previously shown that, while the intrinsic quality of the oocyte is the main factor affecting blastocyst yield during
bovine embryo development in vitro, the main factor affecting the quality ...of the blastocyst is the postfertilization culture
conditions. Therefore, any improvement in the quality of blastocysts produced in vitro is likely to derive from the modification
of the postfertilization culture conditions. The objective of this study was to examine the effect of the presence or absence
of serum and the concentration of BSA during the period of embryo culture in vitro on 1) cleavage rate, 2) the kinetics of
embryo development, 3) blastocyst yield, and 4) blastocyst quality, as assessed by cryotolerance and gene expression patterns.
The quantification of all gene transcripts was carried out by real-time quantitative reverse transcription-polymerase chain
reaction. Bovine blastocysts from four sources were used: 1) in vitro culture in synthetic oviduct fluid (SOF) supplemented
with 3 mg/ml BSA and 10% fetal calf serum (FCS), 2) in vitro culture in SOF + 3 mg/ml BSA in the absence of serum, 3) in vitro
culture in SOF + 16 mg/ml BSA in the absence of serum, and 4) in vivo blastocysts. There was no difference in overall blastocyst
yield at Day 9 between the groups. However, significantly more blastocysts were present by Day 6 in the presence of 10% serum
(20.0%) compared with 3 mg/ml BSA (4.6%, P < 0.001) or 16 mg/ml BSA (11.6%, P < 0.01). By Day 7, however, this difference had disappeared. Following vitrification, there was no difference in survival
between blastocysts produced in the presence of 16 mg/ml BSA or those produced in the presence of 10% FCS; the survival of
both groups was significantly lower than the in vivo controls at all time points and in terms of hatching rate. In contrast,
survival of blastocysts produced in SOF + 3 mg/ml BSA in the absence of serum was intermediate, with no difference remaining
at 72 h when compared with in vivo embryos. Differences in relative mRNA abundance among the two groups of blastocysts analyzed
were found for genes related to apoptosis (Bax), oxidative stress (MnSOD, CuZnSOD, and SOX), communication through gap junctions
(Cx31 and Cx43), maternal recognition of pregnancy (IFN-Ï), and differentiation and implantation (LIF and LR-β). The presence
of serum during the culture period resulted in a significant increase in the level of expression of MnSOD, SOX, Bax, LIF,
and LR-β. The level of expression of Cx31 and Cu/ZnSOD also tended to be increased, although the difference was not significant.
In contrast, the level of expression of Cx43 and IFN-Ï was decreased in the presence of serum. In conclusion, using a combination
of measures of developmental competence (cleavage and blastocyst rates) and qualitative measures such as cryotolerance and
relative mRNA abundance to give a more complete picture of the consequences of modifying medium composition on the embryo,
we have shown that conditions of postfertilization culture, in particular, the presence of serum in the medium, can affect
the speed of embryo development and the quality of the resulting blastocysts. The reduced cryotolerance of blastocysts generated
in the presence of serum is accompanied by deviations in the relative abundance of developmentally important gene transcripts.
Omission of serum during the postfertilization culture period can significantly improve the cryotolerance of the blastocysts
to a level intermediate between serum-generated blastocysts and those derived in vivo. The challenge now is to try and bridge
this gap.
Estimates of the burden of severe acute respiratory syndrome coronavirus 2 reinfections are limited by the scarcity of population-level studies incorporating genomic support. We conducted a ...systematic study of reinfections in Madrid, Spain, supported by genomic viral analysis and host genetic analysis, to cleanse laboratory errors and to discriminate between reinfections and recurrences involving the same strain. Among the 41,195 cases diagnosed (March 2020-March 2021), 93 (0.23%) had 2 positive reverse transcription PCR tests (55-346 days apart). After eliminating cases with specimens not stored, of suboptimal sequence quality, or belonging to different persons, we obtained valid data from 22 cases. Of those, 4 (0.01%) cases were recurrences involving the same strain; case-patients were 39-93 years of age, and 3 were immunosuppressed. Eighteen (0.04%) cases were reinfections; patients were 19-84 years of age, and most had no relevant clinical history. The second episode was more severe in 8 cases.
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