Parasitoid cues modulate Drosophila germline development and stem cell proliferation.

Environmental factors influence an organism's reproductive ability by regulating germline development and physiology. While the reproductive adaptations in response to extrinsic stress cues offer fitness and survival advantages to individuals, the mechanistic understanding of these modifications remains unclear. Here, we find that parasitoid wasps' stress signaling regulates Drosophila melanogaster oogenesis. We show that fruit flies dwelling in the wasp-infested area elevate their fecundity, and the observed reproductive response is specific to Pachycrepoideus sp., a pupal parasitoid wasp. Pachycrepoideus-specific olfactory and visual cues recruit the signaling pathways that promote germline stem cell proliferation and accelerate follicle development, increasing egg production in Drosophila females. Downregulation of signaling engaged in oocyte development by shifting flies to a non-wasp-infested environment increases apoptosis of the developing follicles. Thus, this study establishes host germline responsiveness to parasitoid-specific signals and supports a predator strategy to increase hosts for infection.

Stroke with large vessel occlusion in the posterior circulation: IV thrombolysis plus thrombectomy versus IV thrombolysis alone.

Efficacy and safety of mechanical thrombectomy (MT) for stroke with posterior circulation large vessel occlusion (LVO) is still under debate. We aimed to compare the outcomes of stroke patients with posterior circulation LVO treated with intravenous thrombolysis (IVT) (< 4.5 h after symptom onset) plus MT < 6 h after symptom onset with those treated with IVT alone (< 4.5 h after symptom onset). Patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke (IRETAS) and in the Italian centers included in the SITS-ISTR were analysed. We identified 409 IRETAS patients treated with IVT plus MT and 384 SITS-ISTR patients treated with IVT alone. IVT plus MT was significantly associated with higher rate of sICH (ECASS II) compared with IVT alone (3.1 vs 1.9%; OR 3.984, 95% CI 1.014-15.815), while the two treatments did not differ significantly in 3-month mRS score ≤ 3 (64.3 vs 74.1%; OR 0.829, 95% CI 0.524-1.311). In 389 patients with isolated basilar artery (BA) occlusion, IVT plus MT was significantly associated with higher rate of any ICH compared with IVT alone (9.4 vs 7.4%; OR 4.131, 95% CI 1.215-14.040), while two treatments did not differ significantly in 3-month mRS score ≤ 3 and sICH per ECASS II definition. IVT plus MT was significantly associated with higher rate mRS score ≤ 2 (69.1 vs 52.1%; OR 2.692, 95% CI 1.064-6.811) and lower rate of death (13.8 vs 27.1%; OR 0.299, 95% CI 0.095-0.942) in patients with distal-segment BA occlusion, while two treatments did not differ significantly in 3-month mRS score ≤ 3 and sICH per ECASS II definition. IVT plus MT was significantly associated with lower rate of mRS score ≤ 3 (37.1 vs 53.3%; OR 0.137, 0.009-0.987), mRS score ≤ 1 (22.9 vs 53.3%; OR 0.066, 95% CI 0.006-0.764), mRS score ≤ 2 (34.3 vs 53.3%; OR 0.102, 95% CI 0.011-0.935), and higher rate of death (51.4 vs 40%; OR 16.244, 1.395-89.209) in patients with proximal-segment BA occlusion. Compared with IVT alone, IVT plus MT was significantly associated with higher rate of sICH per ECASS II definition in patients with stroke and posterior circulation LVO, while two treatment groups did not differ significantly in 3-month mRS score ≤ 3. IVT plus MT was associated with lower rate of mRS score ≤ 3 compared with IVT alone in patients with proximal-segment BA occlusion, whereas no significant difference was found between the two treatments in primary endpoints in patients isolated BA occlusion and in the other subgroups based on site occlusion.

Overview of Spontaneous Intracranial Hypotension and Differential Diagnosis with Chiari I Malformation.

Spontaneous intracranial hypotension (SIH) occurs due to a leakage of the cerebrospinal fluid (CSF) lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. As a result of less support provided by CSF pressure, intracranial structures are stretched downward, leading to a constellation of more or less typical MRI findings, including venous congestion, subdural effusions, brainstem sagging and low-lying cerebellar tonsils. Clinic examination and an MRI are usually enough to allow for the diagnosis; however, finding the location of the dural tear is challenging. SIH shares some MRI features with Chiari malformation type I (CM1), especially low-lying cerebellar tonsils. Since SIH is likely underdiagnosed, these findings could be interpreted as signs of CM1, leading to a misdiagnosis and an incorrect treatment pathway. Medical treatment, including steroids, bed rest, hydration caffeine, and a blind epidural blood patch, have been used in this condition with variable success rates. For some years, CSF venous fistulas have been described as the cause of SIH, and a specific diagnostic and therapeutic pathway have been proposed. The current literature on SIH with a focus on diagnosis, treatment, and differential diagnosis with CM1, is reviewed and discussed.

Temporomandibular joint arthrocentesis: a single-center experience and review of the literature.

BACKGROUND: The aim of this paper was to report our experience and to review the literature of arthrocentesis focusing on protocols and results. METHODS: Arthrocentesis with supplemental hyaluronic acid was performed in patients with TMDs between January 2017 and December 2020 at the Division of Maxillofacial Surgery. The maximum interincisal opening (MIO) and pain score were recorded preoperatively (T0), 2 months postoperatively (T1), and 6 months postoperatively (T2). A literature search was performed to analyze the same parameters in patients with TMDs. Patient demographic, characteristics and treatment protocols used were also recorded. RESULTS: This retrospective analysis enrolled 45 patients. Twenty-two patients (20 females, 2 males) with mean age of 37.13 years with internal derangement were included in study group A. Study group B included 23 patients with degenerative joint disease (19 females and 4 males) with mean age of 55.73 years. The outcomes trend of MIO and pain during the follow-up period showed a gradual improvement. Fifty articles meeting the proposed scientific criteria were selected for the literature revision. A range of clinical and procedural variables were analyzed by grouping the studies into two broad categories based on the diagnosis of TMD. CONCLUSIONS: Based on our experience and on the basis of the most accredited scientific studies in the literature, intra-articular injections of HA are beneficial for the improvement of the pain and/or functional symptoms of TMDs.

Parasitoid Wasp Culturing and Assay to Study Parasitoid-induced Reproductive Modifications in Drosophila.

In nature, parasitoid wasp infections are a major cause of insect mortality. Parasitoid wasps attack a vast range of insect species to lay their eggs. As a defense, insects evolved survival strategies to protect themselves from parasitoid infection. While a growing number of studies reported both host defensive tactics and parasitoid counter-offensives, we emphasize that this parasite-host relationship presents a unique ecological and evolutionary relevant model that is often challenging to replicate in a laboratory. Although maintaining parasitoid wasp cultures in the laboratory requires meticulous planning and can be labor intensive, a diverse set of wasp species that target many different insect types can be maintained in similar culture conditions. Here, we describe the protocol for culturing parasitoid wasp species on Drosophila larvae and pupae in laboratory conditions. We also detail an egg-laying assay to assess the reproductive modification of Drosophila females in response to parasitoid wasps. This behavioral study is relatively simple and easily adaptable to study environmental or genetic influences on egg-laying, a readout for female germline development. Neither the parasitoid culture conditions or the behavioral assay require special supplies or equipment, making them a powerful and versatile approach in research or teaching laboratory settings. Graphical abstract.

Embolic Stroke of Undetermined Source: Role of Implantable Loop Recorder in Secondary Prevention.

BACKGROUND AND AIMS: Atrial fibrillation (AF) is the most important cause of embolic stroke of undetermined source (ESUS). Implantable loop recorder (ILR) demonstrated the highest sensitivity for detecting it. This register was created to confirm the high prevalence of AF in patients after ESUS and to verify possible benefits on clinical outcomes such as TIA (Transient Ischaemic Attack)/stroke recurrence and death using ILR. METHODS: A total of 278 patients admitted to "Molinette" Hospital in Stroke Unit department between 2011 and 2016, diagnosed with ESUS, underwent ILR implantation if they had at least one risk factor for AF. A total of 165 patients admitted to other departments in the same center for the same pathology, without ILR, represent the control group. We used propensity score to select 132 patients from each group (matching age, sex, CHADS-VASC, and HAS-BLEED baseline characteristics). RESULTS: The detection rate of AF episodes was significantly higher in the ILR group (p < 0.001). No significant protective role of ILR for clinical endpoints was found on univariate analysis, although a trend towards significance has been pointed for the composite outcome of death and ischemic events recurrence (OR 0.52, CI 0.26-1.04, p = 0.06). A protective role of ILR was found for deaths (OR 0.4, CI 0.17-0.94, p 0.03) and for the composite outcome (OR 0.41, CI 0.19-0.87, p 0.02) on multivariate analysis in the best subsets. CONCLUSION: With our statistical models, we identified a significant clinical benefit from ILR monitoring, evidenced by a trend of less death and TIA/stroke recurrence and relevant ILR protection for prediction of TIA/stroke recurrence.

Host translesion polymerases are required for viral genome integrity.

Human cells encode up to 15 DNA polymerases with specialized functions in chromosomal DNA synthesis and damage repair. In contrast, complex DNA viruses, such as those of the herpesviridae family, encode a single B-family DNA polymerase. This disparity raises the possibility that DNA viruses may rely on host polymerases for synthesis through complex DNA geometries. We tested the importance of error-prone Y-family polymerases involved in translesion synthesis (TLS) to human cytomegalovirus (HCMV) infection. We find most Y-family polymerases involved in the nucleotide insertion and bypass of lesions restrict HCMV genome synthesis and replication. In contrast, other TLS polymerases, such as the polymerase ζ complex, which extends past lesions, was required for optimal genome synthesis and replication. Depletion of either the polζ complex or the suite of insertion polymerases demonstrate that TLS polymerases suppress the frequency of viral genome rearrangements, particularly at GC-rich sites and repeat sequences. Moreover, while distinct from HCMV, replication of the related herpes simplex virus type 1 is impacted by host TLS polymerases, suggesting a broader requirement for host polymerases for DNA virus replication. These findings reveal an unexpected role for host DNA polymerases in ensuring viral genome stability.

CSF-venous leak responsible for spontaneous intracranial hypotension treated by endovascular venous route: First cases in Italy.

Spontaneous intracranial hypotension (SIH) is due to a leakage of CSF lowering the pressure of subarachnoid space, mostly caused by a dural breach or discogenic microspur. Clinical and MRI are usually typical enough to allow diagnosis, while finding the location of the dural breach is challenging. Since some years, CSF venous fistulas have been described as the cause of SIH, and a specific diagnostic and therapeutic path has been proposed. Here we report the first two successfully treated patients in Italy. Both had chronic and non specific symptoms, with severe reduction of quality of life; clinical symptoms improved after endovascular occlusion of the responsible vein.

Internal oligo(dT) priming introduces systematic bias in bulk and single-cell RNA sequencing count data.

Significant advances in RNA sequencing have been recently made possible by using oligo(dT) primers for simultaneous mRNA enrichment and reverse transcription priming. The associated increase in efficiency has enabled more economical bulk RNA sequencing methods and the advent of high-throughput single-cell RNA sequencing, already one of the most widely adopted methods in transcriptomics. However, the effects of off-target oligo(dT) priming on gene expression quantification have not been appreciated. In the present study, we describe the extent, the possible causes, and the consequences of internal oligo(dT) priming across multiple public datasets obtained from various bulk and single-cell RNA sequencing platforms. To explore and address this issue, we developed a computational algorithm for RNA counting methods, which identifies the sequencing read alignments that likely resulted from internal oligo(dT) priming and removes them from the data. Directly comparing filtered datasets to those obtained by an alternative method reveals significant improvements in gene expression measurement. Finally, we infer a list of human genes whose expression quantification is most likely to be affected by internal oligo(dT) priming and predict that when measured using these methods, the expression of most genes may be inflated by at least 10% whereby some genes are affected more than others.

Pten heterozygosity restores neuronal morphology in fragile X syndrome mice.

Genetic studies of hippocampal granule neuron development have been used to elucidate cellular functions of Pten and Fmr1. While mutations in each gene cause neurodevelopmental disorders such as autism and fragile X syndrome, how Pten and Fmr1 function alone or together during normal development is not known. Moreover, Pten mRNA is bound by the fragile X mental retardation protein (FMRP) RNA binding protein, but how this physical interaction impinges on phosphatase and tensin homolog protein (PTEN) expression is not known. To understand the interaction of PTEN and FMRP, we investigated the dentate gyrus granule neuron development in Pten and Fmr1 knockout (KO) mice. Interestingly, heterozygosity of Pten restored Fmr1 KO cellular phenotypes, including dendritic arborization, and spine density, while PTEN protein expression was significantly increased in Fmr1 KO animals. However, complete deletion of both Pten and Fmr1 resulted in a dramatic increase in dendritic length, spine density, and spine length. In addition, overexpression of PTEN in Fmr1 KO Pten heterozygous background reduced dendritic length, arborization, spine density, and spine length including pS6 levels. Our findings suggest that PTEN levels are negatively regulated by FMRP, and some Fmr1 KO phenotypes are caused by dysregulation of PTEN protein. These observations provide evidence for the genetic interaction of PTEN and FMRP and a possible mechanistic basis for the pathogenesis of Fmr1-related fragile X neurodevelopmental disorders.

Magnetic Resonance Imaging for Cerebral Micro-embolizations During Minimally Invasive Mitral Valve Surgery.

The role of aortic clamping techniques on the occurrence of neurological complications after right mini-thoracotomy mitral valve surgery is still debated. Brain injuries can occur also as silent cerebral micro-embolizations (SCM), which have been linked to significant deficits in physical and cognitive functions. Aims of this study are to evaluate the overall rate of SCM and to compare endoaortic clamp (EAC) with trans-thoracic clamp (TTC). Patients enrolled underwent a pre-operative, a post-operative, and a follow-up MRI. Forty-three patients were enrolled; EAC was adopted in 21 patients, TTC in 22 patients. Post-operative SCM were reported in 12 cases (27.9%). No differences between the 2 groups were highlighted (23.8% SCM in the EAC group versus 31.8% in the TTC). MRI analysis showed post-operative SCM in nearly 30% of selected patients after right mini-thoracotomy mitral valve surgery. Subgroup analysis on different types of aortic clamping showed comparable results. CLINICAL RELEVANCE: The rate of SCM reported in the present study on patients undergoing minimally invasive MVS and RAP is consistent with data in the literature on patients undergoing cardiac surgery through median sternotomy and antegrade arterial perfusion. Moreover, no differences were reported between EAC and TTC: both the aortic clamping techniques are safe, and the choice of the surgical setting to adopt can be really done according to the patient's characteristics.

Neuropeptide F signaling regulates parasitoid-specific germline development and egg-laying in Drosophila.

Drosophila larvae and pupae are at high risk of parasitoid infection in nature. To circumvent parasitic stress, fruit flies have developed various survival strategies, including cellular and behavioral defenses. We show that adult Drosophila females exposed to the parasitic wasps, Leptopilina boulardi, decrease their total egg-lay by deploying at least two strategies: Retention of fully developed follicles reduces the number of eggs laid, while induction of caspase-mediated apoptosis eliminates the vitellogenic follicles. These reproductive defense strategies require both visual and olfactory cues, but not the MB247-positive mushroom body neuronal function, suggesting a novel mode of sensory integration mediates reduced egg-laying in the presence of a parasitoid. We further show that neuropeptide F (NPF) signaling is necessary for both retaining matured follicles and activating apoptosis in vitellogenic follicles. Whereas previous studies have found that gut-derived NPF controls germ stem cell proliferation, we show that sensory-induced changes in germ cell development specifically require brain-derived NPF signaling, which recruits a subset of NPFR-expressing cell-types that control follicle development and retention. Importantly, we found that reduced egg-lay behavior is specific to parasitic wasps that infect the developing Drosophila larvae, but not the pupae. Our findings demonstrate that female fruit flies use multimodal sensory integration and neuroendocrine signaling via NPF to engage in parasite-specific cellular and behavioral survival strategies.

Cancer-associated mutations in the condensin II subunit CAPH2 cause genomic instability through telomere dysfunction and anaphase chromosome bridges.

Genome instability in cancer drives tumor heterogeneity, undermines the success of therapies, and leads to metastasis and recurrence. Condensins are conserved chromatin-binding proteins that promote genomic stability, mainly by ensuring proper condensation of chromatin and mitotic chromosome segregation. Condensin mutations are found in human tumors, but it is not known how or even if such mutations promote cancer progression. In this study, we focus on condensin II subunit CAPH2 and specific CAPH2 mutations reported to be enriched in human cancer patients, and we test how CAPH2 cancer-specific mutations may lead to condensin II complex dysfunction and contribute to genome instability. We find that R551P, R551S, and S556F mutations in CAPH2 cause genomic instability by causing DNA damage, anaphase defects, micronuclei, and chromosomal instability. DNA damage and anaphase defects are caused primarily by ataxia telangiectasia and Rad3-related-dependent telomere dysfunction, as anaphase bridges are enriched for telomeric repeat sequences. We also show that these mutations decrease the binding of CAPH2 to the ATPase subunit SMC4 as well as the rest of the condensin II complex, and decrease the amount of CAPH2 protein bound to chromatin. Thus, in vivo the R551P, R551S, and S556F cancer-specific CAPH2 mutant proteins are likely to impair condensin II complex formation, impede condensin II activity during mitosis and interphase, and promote genetic heterogeneity in cell populations that can lead to clonal outgrowth of cancer cells with highly diverse genotypes.

The Photoconvertible Fluorescent Probe, CaMPARI, Labels Active Neurons in Freely-Moving Intact Adult Fruit Flies.

Linking neural circuitry to behavior by mapping active neurons in vivo is a challenge. Both genetically encoded calcium indicators (GECIs) and intermediate early genes (IEGs) have been used to pinpoint active neurons during a stimulus or behavior but have drawbacks such as limiting the movement of the organism, requiring a priori knowledge of the active region or having poor temporal resolution. Calcium-modulated photoactivatable ratiometric integrator (CaMPARI) was engineered to overcome these spatial-temporal challenges. CaMPARI is a photoconvertible protein that only converts from green to red fluorescence in the presence of high calcium concentration and 405 nm light. This allows the experimenter to precisely mark active neurons within defined temporal windows. The photoconversion can then be quantified by taking the ratio of the red fluorescence to the green. CaMPARI promises the ability to trace active neurons during a specific stimulus; however, CaMPARI's uses in adult Drosophila have been limited to photoconversion during fly immobilization. Here, we demonstrate a method that allows photoconversion of multiple freely-moving intact adult flies during a stimulus. Flies were placed in a dish with filter paper wet with acetic acid (pH = 2) or neutralized acetic acid (pH = 7) and exposed to photoconvertible light (60 mW) for 30 min (500 ms on, 200 ms off). Immediately following photoconversion, whole flies were fixed and imaged by confocal microscopy. The red:green ratio was quantified for the DC4 glomerulus, a bundle of neurons expressing Ir64a, an ionotropic receptor that senses acids in the Drosophila antennal lobe. Flies exposed to acetic acid showed 1.3-fold greater photoconversion than flies exposed to neutralized acetic acid. This finding was recapitulated using a more physiological stimulus of apple cider vinegar. These results indicate that CaMPARI can be used to label neurons in intact, freely-moving adult flies and will be useful for identifying the circuitry underlying complex behaviors.

Acute Occlusion of the Distal Internal Carotid Artery : Single Center Experience in 46 Consecutive Cases, review of the literature and proposal of a classification.

PURPOSE: The acute distal intracranial occlusion of the internal carotid artery (ICA) is a very complex heterogeneous pathology, characterized by various patterns. Aim of this work is to identify the different types and propose a classification. METHODS: Among the patients admitted for stroke in the anterior circulation from august 2014 to October 2017, 46 (25%) presented with intracranial distal carotid artery occlusion. The mean age of the patients was 71 (SD 13.7), 65,2% female. The protocol included general and specific neurological examinations, CT, CT-Angiography with multiphase CTA, followed by Angiography. The occlusion was treated by aspiration device alone or associated with stent-retriever. NIHSS at the admission, at discharge and modified ranking Scale (mRS) at four months were examined. RESULTS: The occlusions presented with various patterns. Depending on its site (located at the distal ICA bifurcation or more proximal at the level of the ophthalmic segment of ICA, with or without extent to ICA bifurcation) taking also into account the various involvement of the cerebral vessels and anatomic variations of Circle of Willis, three groups of occlusion types could be identified (T1, T2 and T3). The collateral circulation, and the possibilities of the endovascular revascularization important for the final outcome, were clearly connected with the type of occlusion. NIHSS at admission was 19.1 (Range from 8 to 30, SD 4.4). Good outcome defined as mRS 0-2 at for months was obtained in 17 patients (37%). CONCLUSIONS: The proposed classification reproduces more precisely the complexity and heterogeneity of this pathology, being useful in the diagnosis and treatment of these patients.

Maternal Priming of Offspring Immune System in Drosophila.

Immune priming occurs when a past infection experience leads to a more effective immune response upon a secondary exposure to the infection or pathogen. In some instances, parents are able to transmit immune priming to their offspring, creating a subsequent generation with a superior immune capability, through processes that are not yet fully understood. Using a parasitoid wasp, which infects larval stages of Drosophila melanogaster, we describe an example of an intergenerational inheritance of immune priming. This phenomenon is anticipatory in nature and does not rely on parental infection, but rather, when adult fruit flies are cohabitated with a parasitic wasp, they produce offspring that are more capable of mounting a successful immune response against a parasitic macro-infection. This increase in offspring survival correlates with a more rapid induction of lamellocytes, a specialized immune cell. RNA-sequencing of the female germline identifies several differentially expressed genes following wasp exposure, including the peptiodoglycan recognition protein-LB (PGRP-LB). We find that genetic manipulation of maternal PGRP-LB identifies this gene as a key element in this intergenerational phenotype.

Neural circuitry of social learning in Drosophila requires multiple inputs to facilitate inter-species communication.

Drosophila species communicate the threat of parasitoid wasps to naïve individuals. Communication of the threat between closely related species is efficient, while more distantly related species exhibit a dampened, partial communication. Partial communication between D. melanogaster and D. ananassae about wasp presence is enhanced following a period of cohabitation, suggesting that species-specific natural variations in communication 'dialects' can be learned through socialization. In this study, we identify six regions of the Drosophila brain essential for dialect training. We pinpoint subgroups of neurons in these regions, including motion detecting neurons in the optic lobe, layer 5 of the fan-shaped body, the D glomerulus in the antennal lobe, and the odorant receptor Or69a, where activation of each component is necessary for dialect learning. These results reveal functional neural circuits that underlie complex Drosophila social behaviors, and these circuits are required for integration several cue inputs involving multiple regions of the Drosophila brain.

Transgeneratonal inheritance of ethanol preference is caused by maternal NPF repression.

Rapid or even anticipatory adaptation to environmental conditions can provide a decisive fitness advantage to an organism. The memory of recurring conditions could also benefit future generations; however, neuronally-encoded behavior isn't thought to be inherited across generations. We tested the possibility that environmentally triggered modifications could allow 'memory' of parental experiences to be inherited. In Drosophila melanogaster, exposure to predatory wasps leads to inheritance of a predisposition for ethanol-rich food for five generations. Inhibition of Neuropeptide-F (NPF) activates germline caspases required for transgenerational ethanol preference. Further, inheritance of low NPF expression in specific regions of F1 brains is required for the transmission of this food preference: a maternally derived NPF locus is necessary for this phenomenon, implicating a maternal epigenetic mechanism of NPF-repression. Given the conserved signaling functions of NPF and its mammalian NPY homolog in drug and alcohol disorders, these observations raise the intriguing possibility of NPY-related transgenerational effects in humans.

Condensin II subunit NCAPH2 associates with shelterin protein TRF1 and is required for telomere stability.

Condensin II subunits are known to be expressed and localized to interphase nuclei of eukaryotic cells. Although some studies have shown that condensin II likely exerts axial compaction forces, organizes chromosome territories, and has possible transcriptional modulatory functions, the full range of condensin II interphase activities are not known. In particular, it is not known if condensin II interphase activities are generally genome-wide or if they have additional local activities unique to specific chromosomal structures such as telomeres. Here, we find that NCAPH2 interacts with TRF1 and these two proteins co-localize at telomeres. Depletion of NCAPH2 leads to ATR-dependent accumulation of 53BP1 and γH2AX DNA damage foci, including damage specific to telomeres. Furthermore, depletion of NCAPH2 results in a fragile telomere phenotype and apparent sister-telomere fusions only days after NCAPH2 depletion. Taken together these observations suggest that NCAPH2 promotes telomere stability, possibly through a direct interaction with the TRF1 shelterin component, and prevents telomere dysfunction resulting from impaired DNA replication. Because proper telomere function is essential for chromosome integrity these observations reveal a previously unappreciated function for NCAPH2 in ensuring genome and telomere stability.

Condensin II Counteracts Cohesin and RNA Polymerase II in the Establishment of 3D Chromatin Organization.

Interaction domains in Drosophila chromosomes form by segregation of active and inactive chromatin in the absence of CTCF loops, but the role of transcription versus other architectural proteins in chromatin organization is unclear. Here, we find that positioning of RNAPII via transcription elongation is essential in the formation of gene loops, which in turn interact to form compartmental domains. Inhibition of transcription elongation or depletion of cohesin decreases gene looping and formation of active compartmental domains. In contrast, depletion of condensin II, which also localizes to active chromatin, causes increased gene looping, formation of compartmental domains, and stronger intra-chromosomal compartmental interactions. Condensin II has a similar role in maintaining inter-chromosomal interactions responsible for pairing between homologous chromosomes, whereas inhibition of transcription elongation or cohesin depletion has little effect on homolog pairing. The results suggest distinct roles for cohesin and condensin II in the establishment of 3D nuclear organization in Drosophila.