scholarly journals Wac: a new Augmin subunit required for chromosome alignment but not for acentrosomal microtubule assembly in female meiosis

2009 ◽  
Vol 184 (6) ◽  
pp. 777-784 ◽  
Author(s):  
Ana M. Meireles ◽  
Katherine H. Fisher ◽  
Nathalie Colombié ◽  
James G. Wakefield ◽  
Hiroyuki Ohkura
Keyword(s):  
Cultured Cells ◽  
Coiled Coil ◽  
Experimental Manipulation ◽  
Microtubule Assembly ◽  
Female Meiosis ◽  
Mutant Female ◽  
Chromosome Alignment ◽  
First Time ◽  
Insight Into

The bipolar spindle forms without centrosomes naturally in female meiosis and by experimental manipulation in mitosis. Augmin is a recently discovered protein complex required for centrosome-independent microtubule generation within the spindle in Drosophila melanogaster cultured cells. Five subunits of Augmin have been identified so far, but neither their organization within the complex nor their role in developing organisms is known. In this study, we report a new Augmin subunit, wee Augmin component (Wac). Wac directly interacts with another Augmin subunit, Dgt2, via its coiled-coil domain. Wac depletion in cultured cells, especially without functional centrosomes, causes severe defects in spindle assembly. We found that a wac deletion mutant is viable but female sterile and shows only a mild impact on somatic mitosis. Unexpectedly, mutant female meiosis showed robust microtubule assembly of the acentrosomal spindle but frequent chromosome misalignment. For the first time, this study establishes the role of an Augmin subunit in developing organisms and provides an insight into the architecture of the complex.

scholarly journals Drosophila melanogaster γ-TuRC is dispensable for targeting γ-tubulin to the centrosome and microtubule nucleation

2006 ◽  
Vol 172 (4) ◽  
pp. 517-528 ◽  
Author(s):  
Christel Vérollet ◽  
Nathalie Colombié ◽  
Thomas Daubon ◽  
Henri-Marc Bourbon ◽  
Michel Wright ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Cultured Cells ◽  
Microtubule Assembly ◽  
Microtubule Nucleation ◽  
Mitotic Delay ◽  
Ring Complexes ◽  
Higher Eukaryotes ◽  
First Time

In metazoans, γ-tubulin acts within two main complexes, γ-tubulin small complexes (γ-TuSCs) and γ-tubulin ring complexes (γ-TuRCs). In higher eukaryotes, it is assumed that microtubule nucleation at the centrosome depends on γ-TuRCs, but the role of γ-TuRC components remains undefined. For the first time, we analyzed the function of all four γ-TuRC–specific subunits in Drosophila melanogaster: Dgrip75, Dgrip128, Dgrip163, and Dgp71WD. Grip-motif proteins, but not Dgp71WD, appear to be required for γ-TuRC assembly. Individual depletion of γ-TuRC components, in cultured cells and in vivo, induces mitotic delay and abnormal spindles. Surprisingly, γ-TuSCs are recruited to the centrosomes. These defects are less severe than those resulting from the inhibition of γ-TuSC components and do not appear critical for viability. Simultaneous cosilencing of all γ-TuRC proteins leads to stronger phenotypes and partial recruitment of γ-TuSC. In conclusion, γ-TuRCs are required for assembly of fully functional spindles, but we suggest that γ-TuSC could be targeted to the centrosomes, which is where basic microtubule assembly activities are maintained.

Strategic Relations and Sport Policy Making: The Case of Aerobic Union and School Sports Federation Bulgaria

2001 ◽  
Vol 15 (3) ◽  
pp. 173-194 ◽  
Author(s):  
Vassil Girginov
Keyword(s):  
Policy Making ◽  
Strategic Orientation ◽  
Communist State ◽  
Sport Policy ◽  
School Sports ◽  
Totalitarian Regimes ◽  
First Time ◽  
Insight Into ◽  
Relation Perspective

The dismissal of totalitarian regimes across Eastern Europe challenged the strategic orientation of sport in these countries. A central issue concerning the shaping of the new sport policies and the role of democratic states surprisingly as yet has not generated thorough academic analyses. As a result of transformations, the sport sector is undergoing massive adaptations, innovations, and reconfigurations leading to the emergence of new arrangements and actors pursuing different projects. Studying this process from a Strategic Relation perspective invites an analysis of sports policy, which accounts equally for events, actors, structures, and relations. More specifically, this approach offered a fruitful insight into the state and its strategic relations in sport policy making. One aspect of this study of theoretical interest is that, so far as can be ascertained, it is the first time the Strategic Relations approach has been applied to a Communist state.

scholarly journals Bayogenin 3-O-Cellobioside is a novel non-cultivar specific anti-blast metabolite produced in rice in response to Pyricularia oryzae infection

2019 ◽  
Author(s):  
Justice Norvienyeku ◽  
Lili Lin ◽  
Abdul Waheed ◽  
Xiaomin Chen ◽  
Jiandong Bao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Host Resistance ◽  
Blast Resistance ◽  
Differential Resistance ◽  
Host Immunity ◽  
Cereal Crops ◽  
Rice Cultivars ◽  
First Time ◽  
Insight Into

AbstractRice cultivars from japonica and indica lineage possess differential resistance against blast fungus on an account genetic divergence. Whether different rice cultivars also show distinct metabolomic changes in response to P. oryzae, and their role in host resistance, are poorly understood. Here, we examine the responses of six different rice cultivars from japonica and indica lineage challenged with P. oryzae. Both susceptible and resistant rice cultivars expressed several metabolites exclusively during P. oryzae infection, including the saponin Bayogenin 3-O-cellobioside. Bayogenin 3-O-cellobioside level in infected rice directly correlated with their resistant attributes. These findings reveal, for the first time to our knowledge that besides oat, other grass plants including rice produces protective saponins. Our study provides insight into the role of pathogen-mediated metabolomics-reprogramming in host immunity. The correlation between Bayogenin 3-O-Cellobioside levels and blast resistance suggests that engineering saponin expression in cereal crops represents an attractive and sustainable disease control strategy.

scholarly journals Novel Insight Into the Development and Function of Hypopharyngeal Glands in Honey Bees

2021 ◽  
Vol 11 ◽  
Author(s):  
Saboor Ahmad ◽  
Shahmshad Ahmed Khan ◽  
Khalid Ali Khan ◽  
Jianke Li
Keyword(s):  
Honey Bees ◽  
Future Research ◽  
Factors Affecting ◽  
Hypopharyngeal Glands ◽  
And Function ◽  
First Time ◽  
The Brain ◽  
Insight Into ◽  
Made In

Hypopharyngeal glands (HGs) are the most important organ of hymenopterans which play critical roles for the insect physiology. In honey bees, HGs are paired structures located bilaterally in the head, in front of the brain between compound eyes. Each gland is composed of thousands of secretory units connecting to secretory duct in worker bees. To better understand the recent progress made in understanding the structure and function of these glands, we here review the ontogeny of HGs, and the factors affecting the morphology, physiology, and molecular basis of the functionality of the glands. We also review the morphogenesis of HGs in the pupal and adult stages, and the secretory role of the glands across the ages for the first time. Furthermore, recent transcriptome, proteome, and phosphoproteome analyses have elucidated the potential mechanisms driving the HGs development and functionality. This adds a comprehensive novel knowledge of the development and physiology of HGs in honey bees over time, which may be helpful for future research investigations.

scholarly journals Pseudomonas chlororaphis Produces Two Distinct R-Tailocins That Contribute to Bacterial Competition in Biofilms and on Roots

2017 ◽  
Vol 83 (15) ◽  
Author(s):  
Robert J. Dorosky ◽  
Jun Myoung Yu ◽  
Leland S. Pierson ◽  
Elizabeth A. Pierson
Keyword(s):  
Gene Cluster ◽  
Gene Clusters ◽  
Associated Bacteria ◽  
Content Type ◽  
Bacterial Competition ◽  
Transmission Electron ◽  
Lysis Cassette ◽  
First Time ◽  
Insight Into

ABSTRACT R-type tailocins are high-molecular-weight bacteriocins that resemble bacteriophage tails and are encoded within the genomes of many Pseudomonas species. In this study, analysis of the P. chlororaphis 30-84 R-tailocin gene cluster revealed that it contains the structural components to produce two R-tailocins of different ancestral origins. Two distinct R-tailocin populations differing in length were observed in UV-induced lysates of P. chlororaphis 30-84 via transmission electron microscopy. Mutants defective in the production of one or both R-tailocins demonstrated that the killing spectrum of each tailocin is limited to Pseudomonas species. The spectra of pseudomonads killed by the two R-tailocins differed, although a few Pseudomonas species were either killed by or insusceptible to both tailocins. Tailocin release was disrupted by deletion of the holin gene within the tailocin gene cluster, demonstrating that the lysis cassette is required for the release of both R-tailocins. The loss of functional tailocin production reduced the ability of P. chlororaphis 30-84 to compete with an R-tailocin-sensitive strain within biofilms and rhizosphere communities. Our study demonstrates that Pseudomonas species can produce more than one functional R-tailocin particle sharing the same lysis cassette but differing in their killing spectra. This study provides evidence for the role of R-tailocins as determinants of bacterial competition among plant-associated Pseudomonas in biofilms and the rhizosphere. IMPORTANCE Recent studies have identified R-tailocin gene clusters potentially encoding more than one R-tailocin within the genomes of plant-associated Pseudomonas but have not demonstrated that more than one particle is produced or the ecological significance of the production of multiple R-tailocins. This study demonstrates for the first time that Pseudomonas strains can produce two distinct R-tailocins with different killing spectra, both of which contribute to bacterial competition between rhizosphere-associated bacteria. These results provide new insight into the previously uncharacterized role of R-tailocin production by plant-associated Pseudomonas species in bacterial population dynamics within surface-attached biofilms and on roots.

scholarly journals Design of Conditionally Active STATs: Insights into STAT Activation and Gene Regulatory Function

1999 ◽  
Vol 19 (4) ◽  
pp. 2913-2920 ◽  
Author(s):  
Lawrence H. Milocco ◽  
Jennifer A. Haslam ◽  
Jonathan Rosen ◽  
H. Martin Seidel
Keyword(s):  
Tyrosine Phosphorylation ◽  
Nuclear Translocation ◽  
Regulatory Function ◽  
Nuclear Localization Sequence ◽  
Wild Type ◽  
Localization Sequence ◽  
Gene Regulatory ◽  
First Time ◽  
Insight Into

ABSTRACT The STAT (signal transducer and activator of transcription) signaling pathway is activated by a large number of cytokines and growth factors. We sought to design a conditionally active STAT that could not only provide insight into basic questions about STAT function but also serve as a powerful tool to determine the precise biological role of STATs. To this end, we have developed a conditionally active STAT by fusing STATs with the ligand-binding domain of the estrogen receptor (ER). We have demonstrated that the resulting STAT-ER chimeras are estrogen-inducible transcription factors that retain the functional and biochemical characteristics of the cognate wild-type STATs. In addition, these tools have allowed us to evaluate separately the contribution of tyrosine phosphorylation and dimerization to STAT function. We have for the first time provided experimental data supporting the model that the only apparent role of STAT tyrosine phosphorylation is to drive dimerization, as dimerization alone is sufficient to unmask a latent STAT nuclear localization sequence and induce nuclear translocation, sequence-specific DNA binding, and transcriptional activity.

scholarly journals Contribution of the Ler- and H-NS-Regulated Long Polar Fimbriae of Escherichia coli O157:H7 during Binding to Tissue-Cultured Cells

2008 ◽  
Vol 76 (11) ◽  
pp. 5062-5071 ◽  
Author(s):  
Alfredo G. Torres ◽  
Terry M. Slater ◽  
Shilpa D. Patel ◽  
Vsevolod L. Popov ◽  
Margarita M. P. Arenas-Hernández
Keyword(s):  
Escherichia Coli ◽  
Cultured Cells ◽  
Immunogold Labeling ◽  
Regulatory Sequence ◽  
Escherichia Coli O157 ◽  
Wild Type ◽  
E Coli ◽  
First Time ◽  
Better Than

ABSTRACT The expression of the long polar fimbriae (LPF) of enterohemorrhagic Escherichia coli (EHEC) O157:H7 is controlled by a tightly regulated process, and, therefore, the role of these fimbriae during binding to epithelial cells has been difficult to establish. We recently found that histone-like nucleoid-structuring protein (H-NS) binds to the regulatory sequence of the E. coli O157:H7 lpf1 operon and “silences” its transcription, while Ler inhibits the action of the H-NS protein and allows lpf1 to be expressed. In the present study, we determined how the deregulated expression of LPF affects binding of EHEC O157:H7 to tissue-cultured cells, correlating the adherence phenotype with lpf1 expression. We tested the adherence properties of EHEC hns mutant and found that this strain adhered 2.8-fold better than the wild type. In contrast, the EHEC ler mutant adhered 2.1-fold less than the wild type. The EHEC hns ler mutant constitutively expressed the lpf genes, and, therefore, we observed that the double mutant adhered 5.6-fold times better than the wild type. Disruption of lpfA in the EHEC hns and hns ler mutants or the addition of anti-LpfA serum caused a reduction in adhesion, demonstrating that the increased adherence was due to the expression of LPF. Immunogold-labeling electron microscopy showed that LPF is present on the surface of EHEC lpfA + strains. Furthermore, we showed that EHEC expressing LPF agglutinates red blood cells from different species and that the agglutination was blocked by the addition of anti-LpfA serum. Overall, our data confirmed that expression of LPF is a tightly regulated process and, for the first time, demonstrated that these fimbriae are associated with adherence and hemagglutination phenotypes in EHEC O157:H7.

scholarly journals A stutter in the coiled coil domain of E.coli co-chaperone GrpE connects structure with function

2020 ◽  
Author(s):  
Tulsi Upadhyay ◽  
Vaibhav V Karekar ◽  
Ishu Saraogi
Keyword(s):  
Heat Stress ◽  
Coiled Coil ◽  
Bacterial Survival ◽  
Nucleotide Exchange ◽  
E Coli ◽  
Coiled Coil Domain ◽  
Nucleotide Exchange Factor ◽  
First Time

AbstractIn bacteria, the co-chaperone GrpE acts as a nucleotide exchange factor and plays an important role in controlling the chaperone cycle of DnaK. The functional form of GrpE is an asymmetric dimer, consisting of a long non-ideal coiled-coil. During heat stress, this region partially unfolds and prevents DnaK nucleotide exchange, ultimately ceasing the chaperone cycle. In this study, we elucidate the role of thermal unfolding of the coiled-coil domain of E. coli GrpE in regulating its co-chaperonic activity. The presence of a stutter disrupts the regular heptad arrangement typically found in an ideal coiled coil resulting in structural distortion. Introduction of hydrophobic residues at the stutter altered the structural stability of the coiled-coil. Using an in vitro FRET assay, we show for the first time that the enhanced stability of GrpE resulted in an increased affinity for DnaK. However, the mutants were defective in in vitro functional assays, and were unable to support bacterial growth at heat shock temperature in a grpE-deleted E. coli strain. This work provides valuable insights into the functional role of a stutter in the GrpE coiled-coil, and its role in regulating the DnaK-chaperone cycle for bacterial survival during heat stress. More generally, our findings illustrate how a sequence specific stutter in a coiled-coil domain regulates the structure function trade-off in proteins.

scholarly journals The Inactivation of Arabidopsis UBC22 Results in Abnormal Chromosome Segregation in Female Meiosis, but Not in Male Meiosis

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2418
Author(s):  
Ling Cao ◽  
Sheng Wang ◽  
Lihua Zhao ◽  
Yuan Qin ◽  
Hong Wang ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Female Parent ◽  
Male Meiosis ◽  
Female Meiosis ◽  
Callose Deposition ◽  
Protein Ubiquitination ◽  
Mutant Female ◽  
Ubiquitin Conjugating Enzymes ◽  
Plant Meiosis

Protein ubiquitination is important for the regulation of meiosis in eukaryotes, including plants. However, little is known about the involvement of E2 ubiquitin-conjugating enzymes in plant meiosis. Arabidopsis UBC22 is a unique E2 enzyme, able to catalyze the formation of ubiquitin dimers through lysine 11 (K11). Previous work has shown that ubc22 mutants are defective in megasporogenesis, with most ovules having no or abnormally functioning megaspores; furthermore, some mutant plants show distinct phenotypes in vegetative growth. In this study, we showed that chromosome segregation and callose deposition were abnormal in mutant female meiosis while male meiosis was not affected. The meiotic recombinase DMC1, required for homologous chromosome recombination, showed a dispersed distribution in mutant female meiocytes compared to the presence of strong foci in WT female meiocytes. Based on an analysis of F1 plants produced from crosses using a mutant as the female parent, about 24% of female mutant gametes had an abnormal content of DNA, resulting in frequent aneuploids among the mutant plants. These results show that UBC22 is critical for normal chromosome segregation in female meiosis but not for male meiosis, and they provide important leads for studying the role of UBC22 and K11-linked ubiquitination.

scholarly journals Separation of coiled-coil structures in lamin A/C is required for elongation of the filament

2020 ◽  
Author(s):  
Jinsook Ahn ◽  
Soyeon Jeong ◽  
So-mi Kang ◽  
Inseong Jo ◽  
Bum-Joon Park ◽  
...  
Keyword(s):  
Structural Transition ◽  
Coiled Coil ◽  
Binding Mode ◽  
Coiled Coils ◽  
Lamin A ◽  
Structural Elements ◽  
Mutant Proteins ◽  
Biochemical Effects ◽  
Insight Into

AbstractIntermediate filaments (IFs) commonly have structural elements of a central α-helical coiled-coil domain consisting of coil 1a, coil 1b, coil 2, and their flanking linkers. Recently, crystal structure of a long lamin A/C fragment was determined and showed detailed features of a tetrameric unit. The structure further suggested a new binding mode between tetramers, designated eA22, where a parallel overlap of coil 1a and coil 2 is the key interaction. In this study, we investigated the biochemical effects of genetic mutations causing human diseases, focusing on the eA22 interaction. The mutant proteins exhibited either weakened or augmented interactions between coil 1a and coil 2. The ensuing biochemical results indicated that the interaction requires the separation of the coiled-coils in N-terminal of coil 1a and C-terminal of coil 2, coupled with the structural transition in the central α-helical rod domain. This study provides insight into the role of coil 1a as a molecular regulator in elongation of the IF proteins.

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