ABSTRACT
To meet the high calcium (Ca) demand during eggshell biomineralization (2 g of Ca per egg), laying hens develop specific metabolic regulations to maintain Ca homeostasis. The intake of Ca, ...its solubilization, and absorption capacity are enhanced at sexual maturity (SM). A better knowledge of the intestinal Ca transporters involved in their variations at this stage could indicate new nutritional strategies to enhance Ca digestive utilization. Transcellular Ca absorption pathway and its major player calbindin-D 28 K (CALB1) mediate a saturable transport, which has been extensively described in this model. Conversely, a contribution by the paracellular pathway involving non-saturable Ca transport through intercellular tight junction has also been suggested. The aim of the present study was to identify candidate genes of these two pathways and their patterns of expression, in immature pullets (12, 15, and 17 wk old) and mature laying hens (23 wk old) in the duodenum, jejunum, and ileum. Using RT-qPCR, this study identifies 3 new candidate genes for transcellular, and 9 for paracellular Ca transport. A total of 5 candidates of the transcellular pathway, transient receptor potential cation channels subfamily C member 1 (TRPC1) and M member 7 (TRPM7); CALB1 and ATPase plasma membrane Ca2+ transporting 1 (ATP2B1) and ATPase plasma membrane Ca2+ transporting 2 (ATP2B2) were enhanced with age or after SM in the duodenum, the jejunum or all 3 segments. A total of 4 candidates of the paracellular pathway Claudin 2 (CLDN2) and tight junction proteins 1, 2, and 3 (TJP1, TJP2 and TJP3) increased in the small intestine after SM. Additionally, CALB1, ATP2B2, and CLDN2 were overexpressed in the duodenum or the jejunum or both segments after SM. The enhanced expression of candidate genes of the paracellular Ca pathway after SM, supports that the non-saturable transport could be a mechanism of great importance when high concentrations of soluble Ca are observed in the intestinal content during eggshell formation. Both pathways may work cooperatively in the duodenum and jejunum, the main sites of Ca absorption in laying hens.
1. Korat (KR) chicken is a new meat-type chicken breed established with the purpose of developing Small and Micro Community Enterprise Production. This slow-growing chicken has been recognised for ...its good texture and flavour, but its low feed efficiency is associated with high cost of production which can hamper the development of local production. This has highlighted the importance of studying the trade-off between feed efficiency and meat quality in KR chicken.
2. This study investigated the phenotypic correlations between feed efficiency, growth performance, and meat quality in KR chicken. Individual body weight and feed intake were recorded weekly for 75 male KR chickens for the calculation of feed conversion ratio (FCR) and residual feed intake (RFI). The growth curve was modelled by Gompertz function and meat quality evaluated at 10 weeks of age, through the measurement of pH (pH
u
), water-holding capacity (WHC) and drip loss (DL) in breast and thigh muscle.
3. Faster growth rate at young age appeared favourable, regarding feed efficiency, since a moderate negative correlation was found between FCR and initial growth rate. Chickens with a higher initial growth and maturation rates were characterised by lower water-holding capacity in meat. This was not associated with acidic meat, since a higher speed of growth (especially in the first weeks) was positively associated with final pH in breast meat. Relationships between RFI and meat quality traits appeared to be weak. While better FCR could be achieved by increased initial growth rate, this seemed to negatively impact water-holding capacity of the meat.
4. RFI appeared as an interesting alternative as a compromise between FCR and meat quality.
The Shu complex, consisting of Rad51 paralogues, is an important regulator of homologous recombination, an error-free DNA repair pathway. Consequently, when members of this complex are disrupted, ...cells exhibit a mutator phenotype, sensitivity to DNA damage reagents and increased gross chromosomal rearrangements. Previously, we found that the Shu complex plays an important role in ribosomal DNA (rDNA) recombination when the Upstream Activating Factor (UAF) protein Uaf30 is disrupted. UAF30 encodes a protein needed for rDNA transcription and when deleted, rDNA recombination increases and the rDNA expands in a Shu1-dependent manner. Here we find using the uaf30-sensitized background that the central DNA repair protein Rad52, which is normally excluded from the nucleolus, frequently overlaps with the rDNA. This close association of Rad52 with the rDNA is dependent upon Shu1 in a uaf30 mutant. Previously, it was shown that in the absence of Rad52 sumoylation, Rad52 foci mislocalize to the nucleolus. Interestingly, here we find that using the uaf30 sensitized background the ability to regulate Rad52 sumoylation is important for Shu1 dependent rDNA recombination as well as Rad52 close association with rDNA. Our results suggest that in the absence of UAF30, the Shu complex plays a central role in Rad52 rDNA localization as long as Rad52 can be sumoylated. This discrimination is important for rDNA copy number homeostasis.
The Shu complex, consisting of Rad51 paralogues, is an important regulator of homologous recombination, an error-free DNA repair pathway. Consequently, when members of this complex are disrupted, ...cells exhibit a mutator phenotype, sensitivity to DNA damage reagents and increased gross chromosomal rearrangements. Previously, we found that the Shu complex plays an important role in ribosomal DNA (rDNA) recombination when the Upstream Activating Factor (UAF) protein Uaf30 is disrupted.
UAF30
encodes a protein needed for rDNA transcription and when deleted, rDNA recombination increases and the rDNA expands in a Shu1-dependent manner. Here we find using the
uaf30
-sensitized background that the central DNA repair protein Rad52, which is normally excluded from the nucleolus, frequently overlaps with the rDNA. This close association of Rad52 with the rDNA is dependent upon Shu1 in a
uaf30
mutant. Previously, it was shown that in the absence of Rad52 sumoylation, Rad52 foci mislocalize to the nucleolus. Interestingly, here we find that using the
uaf30
sensitized background the ability to regulate Rad52 sumoylation is important for Shu1 dependent rDNA recombination as well as Rad52 close association with rDNA. Our results suggest that in the absence of
UAF30
, the Shu complex plays a central role in Rad52 rDNA localization as long as Rad52 can be sumoylated. This discrimination is important for rDNA copy number homeostasis.
Oogenesis is a complex process requiring the coordinated sequential expression of specific genes and ultimately leading to the release of the female gamete from the ovary. In the present study we ...aimed to investigate the contribution of miRNAs to the regulation of this key biological process in teleosts using a model in which growing oocytes develop simultaneously. Taking advantage of the strong sequence conservation of miRNAs among phylogenetically distant species, we designed a generic microarray displaying most known chordate miRNAs. It allowed us to provide an overview of the ovarian miRNome during oogenesis for the first time in any vertebrate species. We identified 13 differentially expressed miRNAs, and a differential expression of at least one miRNA was observed at each step of oogenesis. A surprisingly high differential expression of several miRNAs was observed at several stages of oogenesis and subsequently confirmed using quantitative PCR. By refining in silico prediction of target genes with gene expression data obtained within the same sample set, we provide strong evidence that miRNAs target major players of oogenesis, including genes involved in rate-limiting steps of steroidogenesis and those involved in gonadotropic control of oocyte development, as well as genes involved in ovulation, oocyte hydration, and acquisition of the ability of the oocyte to support further development once fertilized (i.e., oocyte developmental competence). Together, these observations stress the importance of miRNAs in the regulation and success of female gamete formation during oogenesis.
Background: MicroRNAs (miRNAs) have emerged as important post-transcriptional regulators of gene expression in a wide variety of physiological processes. They can control both temporal and spatial ...gene expression and are believed to regulate 30 to 70 % of the genes. Data are however limited for fish species, with only 9 out of the 30,000 fish species present in miRBase. The aim of the current study was to discover and characterize rainbow trout (Oncorhynchus mykiss) miRNAs in a large number of tissues using next-generation sequencing in order to provide an extensive repertoire of rainbow trout miRNAs. Results: A total of 38 different samples corresponding to 16 different tissues or organs were individually sequenced and analyzed independently in order to identify a large number of miRNAs with high confidence. This led to the identification of 2946 miRNA loci in the rainbow trout genome, including 445 already known miRNAs. Differential expression analysis was performed in order to identify miRNAs exhibiting specific or preferential expression among the 16 analyzed tissues. In most cases, miRNAs exhibit a specific pattern of expression in only a few tissues. The expression data from sRNA sequencing were confirmed by RT-qPCR. In addition, novel miRNAs are described in rainbow trout that had not been previously reported in other species. Conclusion: This study represents the first characterization of rainbow trout miRNA transcriptome from a wide variety of tissue and sets an extensive repertoire of rainbow trout miRNAs. It provides a starting point for future studies aimed at understanding the roles of miRNAs in major physiological process such as growth, reproduction or adaptation to stress. These rainbow trout miRNAs repertoire provide a novel resource to advance genomic research in salmonid species.
Insights into vertebrate whole-genome duplications from the rainbow trout genome Berthelot, Camille; Brunet , Frédéric; Chalopin, Domitille ...
Smbe 2014. Molecular Evolution: From Genome Technology to the History of Life. 2014; 22. Annual Meeting of the Society for Molecular Biology and Evolution (SMBE), Puerto Rico, PRI, 2014-06-08-2014-06-12,
2014
Conference Proceeding
Insights into vertebrate whole-genome duplications from the rainbow trout genome Berthelot, Camille; Brunet , Frédéric; Chalopin, Domitille ...
Smbe 2014. Molecular Evolution: From Genome Technology to the History of Life. 2014; 22. Annual Meeting of the Society for Molecular Biology and Evolution (SMBE), Puerto Rico, PRI, 2014-06-08-2014-06-12,
2014
Conference Proceeding
Vertebrate evolution has been shaped by several rounds of whole-genome duplications (WGDs) that are often suggested to be associated with adaptive radiations and evolutionary innovations. Due to an ...additional round of WGD, the rainbow trout genome offers a unique opportunity to investigate the early evolutionary fate of a duplicated vertebrate genome. Here we show that after 100 million years of evolution the two ancestral subgenomes have remained extremely collinear, despite the loss of half of the duplicated protein-coding genes, mostly through pseudogenization. In striking contrast is the fate of miRNA genes that have almost all been retained as duplicated copies. The slow and stepwise rediploidization process characterized here challenges the current hypothesis that WGD is followed by massive and rapid genomic reorganizations and gene deletions.
Vertebrate evolution has been shaped by several rounds of whole-genome duplications (WGDs) that are often suggested to be associated with adaptive radiations and evolutionary innovations. Due to an ...additional round of WGD, the rainbow trout genome offers a unique opportunity to investigate the early evolutionary fate of a duplicated vertebrate genome. Here we show that after 100 million years of evolution the two ancestral subgenomes have remained extremely collinear, despite the loss of half of the duplicated protein-coding genes, mostly through pseudogenization. In striking contrast is the fate of miRNA genes that have almost all been retained as duplicated copies. The slow and stepwise rediploidization process characterized here challenges the current hypothesis that WGD is followed by massive and rapid genomic reorganizations and gene deletions.
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