The trophectoderm (TE) and inner cell mass (ICM) are committed and marked by reciprocal expression of Cdx2 and Oct4 in mouse late blastocysts. We find that the TE is not committed at equivalent ...stages in cattle, and that bovine Cdx2 is required later, for TE maintenance, but does not repress
Oct4 expression. A
mouse Oct4 (
mOct4) reporter, repressed in mouse TE, remained active in the cattle TE;
bovine Oct4 constructs were not repressed in the mouse TE.
mOct4 has acquired Tcfap2 binding sites mediating Cdx2-independent repression—cattle, humans, and rabbits do not contain these sites and maintain high
Oct4 levels in the TE. Our data suggest that the regulatory circuitry determining ICM/TE identity has been rewired in mice, to allow rapid TE differentiation and early blastocyst implantation. These findings thus emphasize ways in which mice may not be representative of the earliest stages of mammalian development and stem cell biology.
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► Late blastocyst cattle trophectoderm (TE) expresses Oct4 and is not yet committed ► Cdx2 is required for cattle TE maintenance but not for Oct4 repression ► The mouse Oct4 locus is also repressed via AP2 binding sites that are not conserved ► TE regulatory circuitry correlates with the timing of TE commitment and implantation
Before Japan was 'opened up' in the 1850s, contact with Russia as well as other western maritime nations was extremely limited. Yet from the early eighteenth century onwards, as a result of their ...expanding commercial interests in East Asia and the North Pacific, Russians had begun to encounter Japanese and were increasingly eager to establish diplomatic and trading relations with Japan. This book presents rare narratives written by Russians, including official envoys, scholars and, later, tourists, who visited Japan between 1792 and 1913. The introduction and notes set these narratives in the context of the history of Russo-Japanese relations and the genre of European travel writing, showing how the Russian writers combined ethnographic interests with the assertion of Russian and European values, simultaneously inscribing power relations and negotiating cultural difference.
Milk from dairy cows contains the protein β-lactoglobulin (BLG), which is not present in human milk. As it is a major milk allergen, we wished to decrease BLG levels in milk by RNAi. In vitro ...screening of 10 microRNAs (miRNAs), either individually or in tandem combinations, identified several that achieved as much as a 98% knockdown of BLG. One tandem construct was expressed in the mammary gland of an ovine BLG-expressing mouse model, resulting in 96% knockdown of ovine BLG in milk. Following this in vivo validation, we produced a transgenic calf, engineered to express these tandem miRNAs. Analysis of hormonally induced milk from this calf demonstrated absence of BLG and a concurrent increase of all casein milk proteins. The findings demonstrate miRNA–mediated depletion of an allergenic milk protein in cattle and validate targeted miRNA expression as an effective strategy to alter milk composition and other livestock traits.
Incomplete epigenetic reprogramming is postulated to contribute to the low developmental success following somatic cell nuclear transfer (SCNT). Here, we describe the epigenetic reprogramming of DNA ...methylation at an alpha satellite I CpG site (αsatI-5) during development of cattle generated either by artificial insemination (AI) or in vitro fertilization (IVF) and SCNT. Quantitative methylation analysis identified that SCNT donor cells were highly methylated at αsatI-5 and resulting SCNT blastocysts showed significantly more methylation than IVF blastocysts. At implantation, no difference in methylation was observed between SCNT and AI in trophoblast tissue at αsatI-5, however, SCNT embryos were significantly hyper-methylated compared to AI controls at this time point. Following implantation, DNA methylation at αsatI-5 decreased in AI but not SCNT placental tissues. In contrast to placenta, the proportion of methylation at αsatI-5 remained high in adrenal, kidney and muscle tissues during development. Differences in the average proportion of methylation were smaller in somatic tissues than placental tissues but, on average, SCNT somatic tissues were hyper-methylated at αsatI-5. Although sperm from all bulls was less methylated than somatic tissues at αsatI-5, on average this site remained hyper-methylated in sperm from cloned bulls compared with control bulls. This developmental time course confirms that epigenetic reprogramming does occur, at least to some extent, following SCNT. However, the elevated methylation levels observed in SCNT blastocysts and cellular derivatives implies that there is either insufficient time or abundance of appropriate reprogramming factors in oocytes to ensure complete reprogramming. Incomplete reprogramming at this CpG site may be a contributing factor to low SCNT success rates, but more likely represents the tip of the iceberg in terms of incompletely reprogramming. Until protocols ensure the epigenetic signature of a differentiated somatic cell is reset to a state resembling totipotency, the efficiency of SCNT is likely to remain low.
On the enigmatic disappearance of Rauber’s layer van Leeuwen, Jessica; Rawson, Pisana; Berg, Debra K. ...
Proceedings of the National Academy of Sciences - PNAS,
07/2020, Volume:
117, Issue:
28
Journal Article
Peer reviewed
Open access
The polar trophoblast overlays the epiblast in eutherian mammals and, depending on the species, has one of two different fates. It either remains a single-layered, thinning epithelium called ...“Rauber’s layer,” which soon disintegrates, or, alternatively, it keeps proliferating, contributing heavily to the population of differentiating, invasive trophoblast cells and, at least in mice, to the induction of gastrulation. While loss of the persistent polar trophoblast in mice leads to reduced induction of gastrulation, we show here that prevention of the loss of the polar trophoblast in cattle results in ectopic domains of the gastrulation marker, BRACHYURY. This phenotype, and increased epiblast proliferation, arose when Rauber’s layer was maintained for a day longer by countering apoptosis through BCL2 overexpression. This suggests that the disappearance of Rauber’s layer is a necessity, presumably to avoid excessive signaling interactions between this layer and the subjacent epiblast. We note that, in all species in which the polar trophoblast persists, including humans and mice, ectopic polar trophoblast signaling is prevented via epiblast cavitation which leads to the (pro)amniotic cavity, whose function is to distance the central epiblast from such signaling interactions.
ABSTRACTBessa, AL, Oliveira, VN, Agostini, GG, Oliveira, RJS, Oliveira, ACS, White, GE, Wells, GD, Teixeira, DNS, and Espindola, FS. Exercise intensity and recoveryBiomarkers of injury, inflammation, ...and oxidative stress. J Strength Cond Res 30(2)311–319, 2016—Biomarkers of inflammation, muscle damage, and oxidative stress after high-intensity exercise have been described previously; however, further understanding of their role in the postexercise recovery period is necessary. Because these markers have been implicated in cell signaling, they may be specifically related to the training adaptations induced by high-intensity exercise. Thus, a clear model showing their responses to exercise may be useful in characterizing the relative recovery status of an athlete. The purpose of this study was twofold(a) to investigate the time course of markers of muscle damage and inflammation in the blood from 3 to 72 hours after combined training exercises and (b) to investigate indicators of oxidative stress and damage associated with increased reactive oxygen species production during high-intensity exercise in elite athletes. Nineteen male athletes performed a combination of high-intensity aerobic and anaerobic training exercises. Samples were acquired immediately before and at 3, 6, 12, 24, 48, and 72 hours after exercise. The appearance and clearance of creatine kinase and lactate dehydrogenase in the blood occurred faster than previous studies have reported. The neutrophil/lymphocyte ratio summarizes the mobilization of 2 leukocyte subpopulations in a single marker and may be used to predict the end of the postexercise recovery period. Further analysis of the immune response using serum cytokines indicated that high-intensity exercise performed by highly trained athletes only generated inflammation that was localized to the skeletal muscle. Biomarkers are not a replacement for performance tests, but when used in conjunction, they may offer a better indication of metabolic recovery status. Therefore, the use of biomarkers can improve a coachʼs ability to assess the recovery period after an exercise session and to establish the intensity of subsequent training sessions.
Understanding trophic relationships within artificial reef communities, especially those of the most numerically abundant fish, provides value to ecologists and managers looking to prioritize healthy ...food webs. Here we elucidate the trophic interactions of three common fish species on high relief (> 5 m) and low relief (< 5 m) artificial reefs in the northwestern Gulf of Mexico. Biomarkers including stable isotopes, (δ
13
C, δ
15
N, and δ
34
S), and essential fatty acids (18:2n-6, 18:3n-3, 18:4n-3, 20:4n-6, 20:5n-3, 22:5n3, and 22:6n-3) were analyzed within muscle and liver tissue. Species-specific comparisons among tomtate (
Haemulon aurolineatum
), pigfish (
Orthopristis chrysoptera
), and red snapper (
Lutjanus campechanus
), revealed differences in biomarkers within muscle tissue (long-term) namely δ
13
C, δ
15
N, δ
34
S, EPA (20:5n-3), and DHA (22:6n-3). However, using liver tissue (short-term) significant differences existed among a fewer number of biomarkers (δ
15
N, δ
34
S, and EPA) among the three species, indicating increasing trophic similarity. Red snapper collected from low relief reefs had higher δ
15
N values than those on high relief reefs which may be due to higher forage trophic level due to the lack of co-occurring congeners. This study highlights the importance of inter-specific food web observations that aid in the interpretation of the complex trophic relationships occurring on artificial reefs.
Genome editing enables the introduction of beneficial sequence variants into the genomes of animals with high genetic merit in a single generation. This can be achieved by introducing variants into ...primary cells followed by producing a live animal from these cells by somatic cell nuclear transfer cloning. The latter step is associated with low efficiencies and developmental problems due to incorrect reprogramming of the donor cells, causing animal welfare concerns. Direct editing of fertilised one-cell embryos could circumvent this issue and might better integrate with genetic improvement strategies implemented by the industry.
In vitro fertilised zygotes were injected with TALEN editors and repair template to introduce a known coat colour dilution mutation in the PMEL gene. Embryo biopsies of injected embryos were screened by polymerase chain reaction and sequencing for intended biallelic edits before transferring verified embryos into recipients for development to term. Calves were genotyped and their coats scanned with visible and hyperspectral cameras to assess thermal energy absorption.
Multiple non-mosaic calves with precision edited genotypes were produced, including calves from high genetic merit parents. Compared to controls, the edited calves showed a strong coat colour dilution which was associated with lower thermal energy absorbance.
Although biopsy screening was not absolutely accurate, non-mosaic, precisely edited calves can be readily produced by embryo-mediated editing. The lighter coat colouring caused by the PMEL mutation can lower radiative heat gain which might help to reduce heat stress.
The study validates putative causative sequence variants to rapidly adapt grazing cattle to changing environmental conditions.
The pioneer transcription factor (TF) PU.1 controls hematopoietic cell fate by decompacting stem cell heterochromatin and allowing nonpioneer TFs to enter otherwise inaccessible genomic sites. PU.1 ...deficiency fatally arrests lymphopoiesis and myelopoiesis in mice, but human congenital PU.1 disorders have not previously been described. We studied six unrelated agammaglobulinemic patients, each harboring a heterozygous mutation (four de novo, two unphased) of SPI1, the gene encoding PU.1. Affected patients lacked circulating B cells and possessed few conventional dendritic cells. Introducing disease-similar SPI1 mutations into human hematopoietic stem and progenitor cells impaired early in vitro B cell and myeloid cell differentiation. Patient SPI1 mutations encoded destabilized PU.1 proteins unable to nuclear localize or bind target DNA. In PU.1-haploinsufficient pro-B cell lines, euchromatin was less accessible to nonpioneer TFs critical for B cell development, and gene expression patterns associated with the pro- to pre-B cell transition were undermined. Our findings molecularly describe a novel form of agammaglobulinemia and underscore PU.1's critical, dose-dependent role as a hematopoietic euchromatin gatekeeper.
Key points
Age‐related hearing loss (ARHL) is a very heterogeneous disease, resulting from cellular senescence, genetic predisposition and environmental factors (e.g. noise exposure).
Currently, we ...know very little about age‐related changes occurring in the auditory sensory cells, including those associated with the outer hair cells (OHCs).
Using different mouse strains, we show that OHCs undergo several morphological and biophysical changes in the ageing cochlea.
Ageing OHCs also exhibited the progressive loss of afferent and efferent synapses.
We also provide evidence that the size of the mechanoelectrical transducer current is reduced in ageing OHCs, highlighting its possible contribution in cochlear ageing.
Outer hair cells (OHCs) are electromotile sensory receptors that provide sound amplification within the mammalian cochlea. Although OHCs appear susceptible to ageing, the progression of the pathophysiological changes in these cells is still poorly understood. By using mouse strains with a different progression of hearing loss (C57BL/6J, C57BL/6NTac, C57BL/6NTacCdh23+, C3H/HeJ), we have identified morphological, physiological and molecular changes in ageing OHCs (9–12 kHz cochlear region). We show that by 6 months of age, OHCs from all strains underwent a reduction in surface area, which was not a sign of degeneration. Although the ageing OHCs retained a normal basolateral membrane protein profile, they showed a reduction in the size of the K+ current and non‐linear capacitance, a readout of prestin‐dependent electromotility. Despite these changes, OHCs have a normal Vm and retain the ability to amplify sound, as distortion product otoacoustic emission thresholds were not affected in aged, good‐hearing mice (C3H/HeJ, C57BL/6NTacCdh23+). The loss of afferent synapses was present in all strains at 15 months. The number of efferent synapses per OHCs, defined as postsynaptic SK2 puncta, was reduced in aged OHCs of all strains apart from C3H mice. Several of the identified changes occurred in aged OHCs from all mouse strains, thus representing a general trait in the pathophysiological progression of age‐related hearing loss, possibly aimed at preserving functionality. We have also shown that the mechanoelectrical transduction (MET) current from OHCs of mice harbouring the Cdh23ahl allele is reduced with age, highlighting the possibility that changes in the MET apparatus could play a role in cochlear ageing.
Key points
Age‐related hearing loss (ARHL) is a very heterogeneous disease, resulting from cellular senescence, genetic predisposition and environmental factors (e.g. noise exposure).
Currently, we know very little about age‐related changes occurring in the auditory sensory cells, including those associated with the outer hair cells (OHCs).
Using different mouse strains, we show that OHCs undergo several morphological and biophysical changes in the ageing cochlea.
Ageing OHCs also exhibited the progressive loss of afferent and efferent synapses.
We also provide evidence that the size of the mechanoelectrical transducer current is reduced in ageing OHCs, highlighting its possible contribution in cochlear ageing.
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