Project description:In this study, we attempt to characterize the transcriptomic profile of the Asian seabass brains collected from the male and female sexes. The objective is to identify genes that show sexually dimorphic expression in the brain of this species. For this experiment, Asian seabass were collected from the Marine Aquaculture Center of the Agri-Food & Veterinary Authority of Singapore. There were no treatments carried out in this experiment. Four brains from adult male seabass (5 years old) with M3-type testis and four brains from adult female seabass (5 years old) with F3-type ovaries were used in this experiment. (Gonads were examined by histology and classified according to sexual maturation status as described by Guiguen and colleagues (Guiguen et al. Environmental Biology of Fishes, 1994)).
Project description:The aim of the project was to identify differently expressed genes in eggs of European seabass (Dicentrarchus labrax) characterized by different quality. In this way it was expected to identify genes possibly being a molecular indicator of egg quality in this species, which was never studied to date. For the study microarray analysis of over 26 thousand genes in 16 egg batches was performed. Additionally, for each egg batch biological quality was determined, what allowed to compare the gene expression profile with overall egg quality (divided into two groups representing ‘high’ and ‘low’ egg quality). The analysis allowed to identify 39 differently expressed genes between the two groups representing ‘high’ and ‘low’ egg quality. From those genes, expression level of 7 were verified by real-time qPCR which confirmed significant difference in expression in 5 of them.
Project description:In this study, we attempt to characterize the transcriptomic profile of the Asian seabass brains collected from the male and female sexes. The objective is to identify genes that show sexually dimorphic expression in the brain of this species. For this experiment, Asian seabass were collected from the Marine Aquaculture Center of the Agri-Food & Veterinary Authority of Singapore. There were no treatments carried out in this experiment. Four brains from adult male seabass (5 years old) with M3-type testis and four brains from adult female seabass (5 years old) with F3-type ovaries were used in this experiment. (Gonads were examined by histology and classified according to sexual maturation status as described by Guiguen and colleagues (Guiguen et al. Environmental Biology of Fishes, 1994)). Total 8 samples. Male Brain : 4 Female Brain : 4
Project description:In this study, we attempt to characterize the transcriptomic profile of the Asian seabass gonads at various developmental stages. The protandric Asian seabass or barramundi (Lates calcarifer) typically matures as a male at approximately 2–4 years of age and then changes sex to a female in later years. For this experiment, Asian seabass of several ages were collected from the Marine Aquaculture Center of the Agri-Food & Veterinary Authority of Singapore and from farms around Singapore. There were no treatments carried out in this experiment. The gonads were examined by histology and classified according to sexual maturation status as described by Guiguen and colleagues (Guiguen et al. Environmental Biology of Fishes, 1994). Altogether, we analyzed 22 gonadal samples that could be classified into six different types of gonads.
Project description:Aneuploidy, and especially the presence of unpaired chromosomal axes during meiosis, can cause infertility. However, it is not known if extra, unpaired autosomal chromosome segments acquire characteristic protein modifications and undergo transcriptional silencing (meiotic silencing of unpaired chromatin, or MSUC) similar to the unpaired regions of the X and Y chromosomes during spermatogenesis. We used three mouse models of Down syndrome, involving either an extra chromosome or translocation trisomy, to test requirements and consequences of meiotic protein modification and gene silencing in spermatocytes. These models reveal that copy number alone is not sufficient for up-regulation of genes in the trisomic interval, and that MSUC-promoting modifications are not sufficient for down-regulation of genes that reside in unpaired chromatin during meiosis. The position of a trisomic region relative to a centromere, the pairing status of the centromere, and the physical extent of the unpaired chromosomal region all affected assembly of meiotic protein modifications typical of MSUC. One key determinant to modification of unpaired chromatin and infertility in trisomy male mice appears to be proximity of unpaired chromatin to a centromere. Furthermore, the presence of an extra, unpaired centromere, but not translocation trisomy, causes global misregulation of transcription in spermatocytes. Thus, neither trisomy per se, nor chromatin modifications of unpaired chromosomal segments, have major effects on gene expression or meiotic success, but an intact unpaired chromosome has profoundly negative effects on meiotic gene expression.
Project description:In this study, we attempt to characterize the transcriptomic profile of the Asian seabass gonads at various developmental stages. The protandric Asian seabass or barramundi (Lates calcarifer) typically matures as a male at approximately 2M-bM-^@M-^S4 years of age and then changes sex to a female in later years. For this experiment, Asian seabass of several ages were collected from the Marine Aquaculture Center of the Agri-Food & Veterinary Authority of Singapore and from farms around Singapore. There were no treatments carried out in this experiment. The gonads were examined by histology and classified according to sexual maturation status as described by Guiguen and colleagues (Guiguen et al. Environmental Biology of Fishes, 1994). Altogether, we analyzed 22 gonadal samples that could be classified into six different types of gonads. Total 22 samples: Adult Ovaries (F3-stage; 5 years old fish) : 4 Adult Testes (M3-stage; 5 years old fish) : 4 Early Testes (M3-stage; 8-9 months old fish) : 3 Early Transforming Gonads (>2 years old fish) : 3 Late Transforming Gonads (>2 years old fish) : 4 Undifferentiated Gonads (4.5 months old fish) : 4
Project description:Ray2013 - Meiotic initiation in S. cerevisiae
A mathematical representation of early meiotic events, particularly feedback mechanisms at the system level and phosphorylation of signalling molecules for regulating protein activities, is described here
This model is described in the article:
Dynamic modeling of yeast meiotic initiation.
Ray D, Su Y, Ye P.
BMC Syst Biol. 2013 May 1;7:37
Abstract:
BACKGROUND:
Meiosis is the sexual reproduction process common to eukaryotes. The diploid yeast Saccharomyces cerevisiae undergoes meiosis in sporulation medium to form four haploid spores. Initiation of the process is tightly controlled by intricate networks of positive and negative feedback loops. Intriguingly, expression of early meiotic proteins occurs within a narrow time window. Further, sporulation efficiency is strikingly different for yeast strains with distinct mutations or genetic backgrounds. To investigate signal transduction pathways that regulate transient protein expression and sporulation efficiency, we develop a mathematical model using ordinary differential equations. The model describes early meiotic events, particularly feedback mechanisms at the system level and phosphorylation of signaling molecules for regulating protein activities.
RESULTS:
The mathematical model is capable of simulating the orderly and transient dynamics of meiotic proteins including Ime1, the master regulator of meiotic initiation, and Ime2, a kinase encoded by an early gene. The model is validated by quantitative sporulation phenotypes of single-gene knockouts. Thus, we can use the model to make novel predictions on the cooperation between proteins in the signaling pathway. Virtual perturbations on feedback loops suggest that both positive and negative feedback loops are required to terminate expression of early meiotic proteins. Bifurcation analyses on feedback loops indicate that multiple feedback loops are coordinated to modulate sporulation efficiency. In particular, positive auto-regulation of Ime2 produces a bistable system with a normal meiotic state and a more efficient meiotic state.
CONCLUSIONS:
By systematically scanning through feedback loops in the mathematical model, we demonstrate that, in yeast, the decisions to terminate protein expression and to sporulate at different efficiencies stem from feedback signals toward the master regulator Ime1 and the early meiotic protein Ime2. We argue that the architecture of meiotic initiation pathway generates a robust mechanism that assures a rapid and complete transition into meiosis. This type of systems-level regulation is a commonly used mechanism controlling developmental programs in yeast and other organisms. Our mathematical model uncovers key regulations that can be manipulated to enhance sporulation efficiency, an important first step in the development of new strategies for producing gametes with high quality and quantity.
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Project description:The Spo11-generated double-strand breaks (DSBs) that initiate meiotic recombination are non-randomly distributed across the genome. Here, we use S1Seq mapping to map the distribution of meiotic DSBs in spo11 mutant strains of Saccharomyces cerevisiae.
Project description:In most eukaryotes, the meiotic chromosomal bouquet (comprising clustered chromosome ends) provides an ordered chromosome arrangement that facilitates pairing and recombination between homologous chromosomes. In the protist Tetrahymena thermophila, the meiotic prophase nucleus stretches enormously and chromosomes assume a bouquet-like arrangement in which telomeres and centromeres are attached to opposite poles of the nucleus. We have identified and characterized three meiosis-specific genes (MELG1-3) that control nuclear elongation and centromere and telomere clustering. Hence, to find out potential interactions, we did LC-MS/MS analysis for Melg1, Melg2, Melg3, and Tass1 (a partner of Melg3) immunoprecipitation samples.