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Equipartitioning by chromosome association and copy number correction by DNA amplification are at the heart of the evolutionary success of the selfish yeast 2-micron plasmid. The present analysis reveals frequent plasmid presence near telomeres ( TEL s) and centromeres ( CEN s) in mitotic cells, with a preference towards the former. Inactivation of Cdc14 causes plasmid missegregation, which is correlated to the non-disjunction of TEL s (and of rDNA) under this condition. Induced missegregation of chromosome XII, one of the largest yeast chromosomes which harbors the rDNA array and is highly dependent on the condensin complex for proper disjunction, increases 2-micron plasmid missegregation. This is not the case when chromosome III, one of the smallest chromosomes, is forced to missegregate. Plasmid stability decreases when the condensin subunit Brn1 is inactivated. Brn1 is recruited to the plasmid partitioning locus ( STB ) with the assistance of the plasmid-coded partitioning proteins Rep1 and Rep2. Furthermore, in a dihybrid assay, Brn1 interacts with Rep1-Rep2. Taken together, these findings support a role for condensin and/or condensed chromatin in 2-micron plasmid propagation. They suggest that condensed chromosome loci are among favored sites utilized by the plasmid for its chromosome-associated segregation. By homing to condensed/quiescent chromosome locales, and not over-perturbing genome homeostasis, the plasmid may minimize fitness conflicts with its host. Analogous persistence strategies may be utilized by other extrachromosomal selfish genomes, for example, episomes of mammalian viruses that hitchhike on host chromosomes for their stable maintenance.

A bstract We present a Majorana scotogenic-like loop framework in which neutrino mass generation and dark matter stability are intrinsically connected to the breaking of the discrete flavor symmetry A 4 . This breaking leads to the emergence of the scoto-seesaw mechanism and a Z 2 symmetry. This naturally explains the solar and atmospheric mass-squared differences, ∆ m sol 2 and ∆ m atm 2 , while simultaneously ensuring dark matter stability. Our model accommodates normal ordering of neutrino masses, with a generalized μ - τ reflection symmetry shaping the structure of leptonic mixing and a lower limit on the lightest neutrino mass. Moreover, the model provides predictions for the octant of θ 23 and a strong correlation between ∆ m sol 2 and ∆ m atm 2 . This correlation puts a lower bound on the fermionic DM mass. In contrast, scalar dark matter remains viable over a broad mass spectrum. A notable feature is that the low mass regime (~ 15 GeV onwards) survives owing to the presence of efficient co-annihilation channels, which are typically absent in the Majorana scotogenic scenario. Additionally, the model aligns with current and future limits from lepton flavor violation experiments.

Halving of the genome during meiosis I is achieved as the homologous chromosomes move to the opposite spindle poles whereas the sister chromatids stay together and move to the same pole. This requires that the sister kinetochores should take a side-by-side orientation in order to connect to the microtubules emanating from the same pole. Factors that constrain sister kinetochores to adopt such orientation are therefore crucial to achieve reductional chromosome segregation in meiosis I. In budding yeast, a protein complex, known as monopolin, is involved in conjoining of the sister kinetochores and thus facilitates their binding to the microtubules from the same pole. In this study, we report Zip1, a synaptonemal complex component, as another factor that might help the sister kinetochores to take the side-by-side orientation and promote their mono-orientation on the meiosis I spindle. From our results, we propose that the localization of Zip1 at the centromere may provide an additional constraining factor that promotes monopolin to cross-link the sister kinetochores enabling them to mono-orient.

Since its discovery in the early 70s, the 2 micron plasmid of Saccharomyces cerevisiae continues to intrigue researchers with its high protein-coding capacity and a selfish nature yet high stability, earning it the title of a ‘miniaturized selfish genetic element’. It codes for four proteins (Rep1, Rep2, Raf1, and Flp) vital for its own survival and recruits several host factors (RSC2, Cohesin, Cse4, Kip1, Bik1, Bim1, and microtubules) for its faithful segregation during cell division. The plasmid maintains a high-copy number with the help of Flp-mediated recombination. The plasmids organize in the form of clusters that hitch-hike the host chromosomes presumably with the help of the plasmid-encoded Rep proteins and host factors such as microtubules, Kip1 motor, and microtubule-associated proteins Bik1 and Bim1. Although there is no known yeast cell phenotype associated with the 2 micron plasmid, excessive copies of the plasmid are lethal for the cells, warranting a tight control over the plasmid copy number. This control is achieved through a combination of feedback loops involving the 2 micron encoded proteins. Thus, faithful segregation and a concomitant tightly controlled plasmid copy number ensure an optimized benign parasitism of the 2 micron plasmid within budding yeast.

We present a Majorana scotogenic-like loop framework in which neutrino mass generation and dark matter stability are intrinsically connected to the breaking of the discrete flavor symmetry \\(A_4\\). This breaking leads to the emergence of the scoto-seesaw mechanism and a \\(Z_2\\) symmetry. This naturally explains the solar and atmospheric mass-squared differences, \\( m_sol^2\\) and \\( m_atm^2\\), while simultaneously ensuring dark matter stability. Our model accommodates normal ordering of neutrino masses, with a generalized \\(\\)-\\(\\) reflection symmetry shaping the structure of leptonic mixing and a lower limit on the lightest neutrino mass. Moreover, the model provides predictions for the octant of \\(_23\\) and a strong correlation between \\( m_sol^2\\) and \\( m_atm^2\\). This correlation puts a lower bound on the fermionic DM mass. In contrast, scalar dark matter remains viable over a broad mass spectrum. A notable feature is that the low mass regime (\\( 15\\) GeV onwards) survives owing to the presence of efficient co-annihilation channels, which are typically absent in the Majorana scotogenic scenario. Additionally, the model aligns with current and future limits from lepton flavor violation experiments.

Model independent phenomenological studies, ranging from neutrino to B-physics, often consider effective interactions involving either purely vector (V), purely axial vector (A), or mixed vector and axial vector (V, A) couplings. While pure vector \\(Z'\\) interactions can naturally emerge in gauged \\(U(1)_X\\) extensions of the Standard Model, such as the \\(B-L\\) model, generating other coupling structures from a UV complete theory is highly nontrivial. To realize such couplings, we propose a new class of flavor specific chiral \\(U(1)_X\\) gauge symmetries. Gauge anomaly cancellation is achieved by introducing three right-handed neutrinos charged under the \\(U(1)_X\\) symmetry. We systematically classify anomaly free charge assignments and analyze viable ultraviolet completions with minimal scalar content, requiring no additional fermions beyond the three necessary for anomaly cancellation. We present several benchmark models illustrating the range of possible charge assignments, under which the quark and lepton flavor structures can differ substantially, leading to distinct phenomenological signatures. In particular, such non universal charge configurations naturally give rise to \\(Z'\\) mediated flavor changing neutral currents in both the quark and lepton sectors. We also demonstrate that, within this framework, the \\(Z'\\) boson can naturally acquire purely axial vector or mixed vector-axial couplings to the SM fermions, both in the heavy and light \\(Z'\\) regimes.

The current generation of Dark Matter Direct Detection Experiments has ruled out a large region of parameter space for dark matter, particularly in the (\\(10 - 1000\\)) GeV mass range. However, due to very low event rates, searching for dark matter in the heavy mass range, \\(O\\)(TeV), is a daunting task requiring even larger volume detectors and long exposure times. We show that for a broad class of dark matter models of the type that these experiments are searching, including some of the most popular candidates, the heavy dark matter mass range can be ruled out in its entirety once we take into account the large corrections to Higgs mass imparted by such heavy dark matter. We show that such a limit is applicable to all types of dark matter i.e. scalar, vector, and fermionic, provided they couple directly with Higgs. By taking some simple and well studied dark matter models we show that the latest LZ limits can completely rule out such a dark matter except in a narrow range around \\(M_h/2\\) mass.

Kinesin motors provide the molecular forces at the kinetochore-microtubule interface and along the spindle to control chromosome segregation. During meiosis with the two rounds of microtubule assembly-disassembly, the roles of motor proteins remain unexplored. We observed that in contrast to mitosis Cin8 (kinesin 5) and Kip3 (kinesin 8) together are indispensable in meiosis. Examining the meiosis in cin8∆ kip3∆ cells, we detected chromosome breakage in the meiosis II cells. The double mutant exhibits delay in the cohesin removal and spindle elongation during anaphase I. Consequently, some cells abrogate meiosis II and form dyads while some, as they progress through meiosis II, cause defect in chromosome integrity. We believe that in the latter cells, an imbalance of spindle mediated force and simultaneous persistent cohesin on the chromosomes cause their breakage. We provide evidence that tension generated by Cin8 and Kip3 through microtubule cross-linking is essential for signaling efficient cohesin removal and maintenance of chromosome integrity during meiosis. Molecular motors generate forces that facilitate chromosome segregation. Unlike mitosis, in meiosis, two times chromosome segregation occur with twice microtubule assembly/disassembly. This work reports that the motor mediated forces are crucial for cohesin removal in meiosis and thus maintain genome integrity.

Equipartitioning by chromosome hitchhiking and copy number correction by DNA amplification are at the heart of the evolutionary success of the selfish yeast 2-micron plasmid. The present analysis reveals plasmid presence near centromeres and telomeres in mitotic cells, with a preference towards the latter. The observed correlation of plasmid missegregation with non-disjunction of rDNA and telomeres under Cdc14 inactivation, higher plasmid missegregation upon induced missegregation of chromosome XII but not chromosome III, requirement of condensin for plasmid stability and the interaction of the condensin subunit Brn1 with the plasmid partitioning system lend functional credence to condensed chromatin being favored for plasmid tethering. By homing to condensed/quiescent chromosome locales, and not over-perturbing genome homeostasis, the plasmid may minimize fitness conflicts with its host. Analogous persistence strategies may be utilized by other extrachromosomal selfish genomes, for example, episomes of mammalian viruses that also hitchhike on host chromosomes for their stable maintenance.

Background The Bundelkhand Craton is significant for preserving the multiphase granitoids magmatism from Paleoarchean to Neoarchean periods. It consists of a variety of granite rocks, including TTGs, sanukitoids, and high-K granitoids. This study presents geochemical characteristics of high-silica (68.97 wt.%–73.99 wt.%), low-silica (58.73 wt.%–69.94 wt.%), and high K 2 O (2.77 wt.%–6.16 wt.%) contents of granitoids. Objective The data on Bundelkhand Craton's granitic magmatism and geodynamics is not sufficiently robust. Geochemical data from this study will be used to further understand the origin, source, and petrogenesis of granitoid rocks and their implications for the evolution of geodynamics. Methodology Twenty-one samples were collected and analyzed for major, trace, and REE elements. Major elements were measured using X-ray fluorescence spectrometry (XRF), and trace and REE elements were analyzed by ICP-MS. Standard procedures from the Geological Survey of India were followed. Results The geochemical analysis presents high-silica (68.97-73.99 wt. %), low-silica (58.73-69.94 wt. %), and high K2O (2.77-6.16 wt. %) contents in granitoids, classified as granite-granodiorite. The rocks are calcic to calcalkalic, magnesian, and range from peraluminous to metaluminous composition. REE patterns showed strong LREE enrichment relative to HREEs, with prominent negative Eu anomalies corresponding to earlier plagioclase fractionation. Multi-element patterns revealed negative anomalies in Nb, Sr, P, and Ti and positive anomalies in Pb. Conclusion The geochemical signatures attributed to the post-collisional magma generation and continental crustal contamination. The studied rocks show A-type and A2-type lineage, suggesting they originated from the melting of continental crust during transitional/post-collisional tectonic activity. The formation of hybrid granitoids in the Bundelkhand Craton is connected to the fractionation of hybrid magmas in shallow-seated magma chambers during these tectonic processes.