The 14-3-3 Proteins Bmh1 and Bmh2 Are Key Regulators of Meiotic Commitment

Induction of meiosis requires exogenous signals that activate internal gene regulatory networks. Meiotic commitment ensures the irreversible continuation of meiosis, even upon withdrawal of the meiosis inducing signals. Budding yeast cells have a unique property in that cells enter meiosis when starved, but if given nutrient-rich medium prior to the commitment point, they exit meiosis and enter mitosis. After the meiotic commitment point in prometaphase I, cells remain in meiosis even with addition of nutrients. Despite the importance of meiotic commitment in ensuring the production of gametes, only a few genes involved in the commitment process are known. We performed a genome-scale screen in budding yeast and discovered new regulators of meiotic commitment including Bcy1, which is involved in nutrient sensing, the meiosis-specific kinase Ime2, Polo kinase Cdc5, and the 14-3-3 proteins Bmh1 and Bmh2. Importantly, we found that Bmh1 and Bmh2 are involved in multiple processes throughout meiosis including the maintenance of the middle meiosis transcription factor Ndt80, activation of Cdc5, and interaction with an RNA-binding protein Pes4, which is important for regulating the timing of translation of several mRNAs in meiosis II. This study identifies a meiotic commitment regulatory network with the 14-3-3 proteins functioning as central regulators.

Evolution of a σ–(c-di-GMP)–anti-σ switch

Filamentous actinobacteria of the genus Streptomyces have a complex lifecycle involving the differentiation of reproductive aerial hyphae into spores. We recently showed c-di-GMP controls this transition by arming a unique anti-σ, RsiG, to bind the sporulation-specific σ, WhiG. The Streptomyces venezuelae RsiG–(c-di-GMP)2–WhiG structure revealed that a monomeric RsiG binds c-di-GMP via two E(X)3S(X)2R(X)3Q(X)3D repeat motifs, one on each helix of an antiparallel coiled-coil. Here we show that RsiG homologs are found scattered throughout the Actinobacteria. Strikingly, RsiGs from unicellular bacteria descending from the most basal branch of the Actinobacteria are small proteins containing only one c-di-GMP binding motif, yet still bind their WhiG partners. Our structure of a Rubrobacter radiotolerans (RsiG)2–(c-di-GMP)2–WhiG complex revealed that these single-motif RsiGs are able to form an antiparallel coiled-coil through homodimerization, thereby allowing them to bind c-di-GMP similar to the monomeric twin-motif RsiGs. Further data show that in the unicellular actinobacterium R. radiotolerans, the (RsiG)2–(c-di-GMP)2–WhiG regulatory switch controls type IV pilus expression. Phylogenetic analysis indicates the single-motif RsiGs likely represent the ancestral state and an internal gene-duplication event gave rise to the twin-motif RsiGs inherited elsewhere in the Actinobacteria. Thus, these studies show how the anti-σ RsiG has evolved through an intragenic duplication event from a small protein carrying a single c-di-GMP binding motif, which functions as a homodimer, to a larger protein carrying two c-di-GMP binding motifs, which functions as a monomer. Consistent with this, our structures reveal potential selective advantages of the monomeric twin-motif anti-σ factors.

Reference Genes for Quantitative Real-time Polymerase Chain Reaction (qPCR)) Analyses in Freshly Isolated Monocytes of Septic Patients

Background: Sepsis is a life-threatening organ dysfunction associated with unregulated host response to infection. About 20 million people develop sepsis annually, and up to 50% die. Monocytes and macrophages play a key role in the innate and adaptive immune responses but the fully role of these cells in patients with sepsis still remains to be investigated. One of the limitations for the studies of gene expression in monocytes/macrophages in sepsis is the choice of the reference genes. We determined herein the most stable internal gene (s) to investigate gene expressions in monocytes/macrophages of septic patients.Methods: The expression stability of fifteen commonly used reference genes was analyzed by determining the comparative threshold cycle (Ct) values, using the BestKeeper, GeNorm, and NormFinder algorithms.Results: BestKeeper analysis revealed that the syntaxin 5 (STX5A) and hypoxanthine phosphoribosyltransferase 1 (HPRT1) genes are highly stable. GeNorm pointed out STX5A and phosphoglycerate kinase 1 (PGK1) as the most suitable combination, whereas through NormFinder glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and 14-3-3 zeta/delta protein (YWHAZ) was the most stable combination. All program analyses discarded the use of heterogeneous nuclear ribonucleoprotein A/B (HNRNPAB). GeNorm and NormFinder indicated actin-beta (ACTB) as the minor stable gene.Conclusions: The combined data indicated that STX5A, PGK1, GAPDH, and HPRT1 are highly suitable reference genes for qPCR analysis of septic patient monocytes. In choosing one reference gene, the results point out STX5A (first place by GeNorm and BestKeeper and third place by NormFinder). This study is the first report on reference genes in freshly obtained monocytes/macrophages from septic patients.

G1-like M and PB2 genes are preferentially incorporated into H7N9 progeny virions during genetic reassortment

Background Genotype S H9N2 viruses have become predominant in poultry in China since 2010. These viruses frequently donate their whole internal gene segments to other emerging influenza A subtypes such as the novel H7N9, H5N6, and H10N8 viruses. We recently reported that the PB2 and M genes of the genotype S H9N2 virus, which are derived from the G1-like virus, enhance the fitness of H5Nx and H7N9 avian influenza viruses in chickens and mice. However, whether the G1-like PB2 and M genes are preferentially incorporated into progeny virions during virus reassortment remains unclear; whether the G1-like PB2 and M genes from different subtypes are differentially incorporated into new virion progeny remains unknown. Results We conducted a reassortment experiment with the use of a H7N9 virus as the backbone and found that G1-like M/PB2 genes were preferentially incorporated in progeny virions over F/98-like M/PB2 genes. Importantly, the preference varied among G1-like M/PB2 genes of different subtypes. When competing with F/98-like M/PB2 genes during reassortment, both the M and PB2 genes from the H7N9 virus GD15 showed an advantage, whereas only the PB2 gene from the H9N2 virus CZ73 and the M gene from the H9N2 virus AH320 displayed the advantage. Conclusion Our findings highlight the preferential and variable advantages of H9N2-derived G1-like M and PB2 genes in incorporating them into H7N9 progeny virions over SH14-derived F/98-like M/PB2 genes.

Treponema pallidum tprII subfamily genes internal fragments sequencing

Background. The modern system of molecular typing of the Russian population of T. pallidum makes it possible to obtain results with a significant dominance of the 14d/f type, which determines the need to increase the differentiating ability of the applied methods of molecular typing of T. pallidum. Aim. Identification and analysis of nucleotide sequence variability of internal gene fragments of the tprII family of Russian T. pallidum subsp. pallidum strains. Material and methods. The study of internal variable fragments of genes of the tprII family was carried out among 240 clinical isolates of T. pallidum obtained from the Central (Kaluga Region, Moscow), North Caucasian (Stavropol Territory), Far East (Republic of Sakha), Volga (Chuvash Republic), Southern (Astrakhan Region) and Siberian (Novosibirsk and Omsk Regions, Republic of Tyva) federal districts in 20142020. The sequence of internal variable fragments of genes of the tprII family was determined using capillary sequencialng technology. Results. The primers allowing both direct amplification of the internal variable region of the tprII genes subfamily and correct sequencing of their internal regions have been proposed. It was found one SNP at positions 1340 of tprG gene. The polymorphism differs the reference Nichols strain from globally distributed Street 14 genogroup variants. Conclusion. The variability of tprII subfamily genes nucleotide sequences in modern Russian strains of T. pallidum subsp. pallidum is an additional fund to increase the efficiency of the modern T. pallidum molecular typing system.

Characterization of Four Novel H5N6 Avian Influenza Viruses with the Internal Genes from H5N1 and H9N2 Viruses and Experimental Challenge of Chickens Vaccinated with Current Commercially Available H5 Vaccines

Since 2014, highly pathogenic avian influenza H5N6 viruses have been responsible for outbreaks in poultry. In this study, four H5N6 virus strains were isolated from fecal samples of sick white ducks and dead chickens in Shandong in 2019. These H5N6 viruses were triple-reassortant viruses that have not been previously characterized. Their HA genes were derived from the H5 viruses and were closely related to the vaccine strain Re-11. Their NA genes all fell into the N6-like lineage and the internal gene were derived from H5N1 and H9N2 viruses. They all showed high pathogenicity in mice and caused lethal infection with high rates of transmission in chickens. Moreover, the SPF chickens inoculated with the current used vaccine in China were completely protected from these four H5N6 viruses. Our study indicated the necessity of continued surveillance for H5 IAV and the importance of timely update of vaccine strains in poultry industry.

Phenotypic transitions enacted by simulated microgravity do not alter coherence in gene transcription profile

Cells in simulated microgravity undergo a reversible morphology switch, causing the appearance of two distinct phenotypes. Despite the dramatic splitting into an adherent-fusiform and a floating-spherical population, when looking at the gene-expression phase space, cell transition ends up in a largely invariant gene transcription profile characterized by only mild modifications in the respective Pearson’s correlation coefficients. Functional changes among the different phenotypes emerging in simulated microgravity using random positioning machine are adaptive modifications—as cells promptly recover their native phenotype when placed again into normal gravity—and do not alter the internal gene coherence. However, biophysical constraints are required to drive phenotypic commitment in an appropriate way, compatible with physiological requirements, given that absence of gravity foster cells to oscillate between different attractor states, thus preventing them to acquire a exclusive phenotype. This is a proof-of-concept of the adaptive properties of gene-expression networks supporting very different phenotypes by coordinated ‘profile preserving’ modifications.