Dynamical modeling of syncytial mitotic cycles in Drosophila embryos

Immediately following fertilization, the fruit fly embryo undergoes 13 rapid, synchronous, syncytial nuclear division cycles driven by maternal genes and proteins. During these mitotic cycles, there are barely detectable oscillations in the total level of B-type cyclins. In this paper, we propose a dynamical model for the molecular events underlying these early nuclear division cycles in Drosophila. The model distinguishes nuclear and cytoplasmic compartments of the embryo and permits exploration of a variety of rules for protein transport between the compartments. Numerical simulations reproduce the main features of wild-type mitotic cycles: patterns of protein accumulation and degradation, lengthening of later cycles, and arrest in interphase 14. The model is consistent with mutations that introduce subtle changes in the number of mitotic cycles before interphase arrest. Bifurcation analysis of the differential equations reveals the dependence of mitotic oscillations on cycle number, and how this dependence is altered by mutations. The model can be used to predict the phenotypes of novel mutations and effective ranges of the unmeasured rate constants and transport coefficients in the proposed mechanism

Weight and metabolic effects of cpap in obstructive sleep apnea patients with obesity

<p>Abstract</p> <p>Background</p> <p>Obstructive sleep apnea (OSA) is associated with obesity, insulin resistance (IR) and diabetes. Continuous positive airway pressure (CPAP) rapidly mitigates OSA in obese subjects but its metabolic effects are not well-characterized. We postulated that CPAP will decrease IR, ghrelin and resistin and increase adiponectin levels in this setting.</p> <p>Methods</p> <p>In a pre- and post-treatment, within-subject design, insulin and appetite-regulating hormones were assayed in 20 obese subjects with OSA before and after 6 months of CPAP use. Primary outcome measures included glucose, insulin, and IR levels. Other measures included ghrelin, leptin, adiponectin and resistin levels. Body weight change were recorded and used to examine the relationship between glucose regulation and appetite-regulating hormones.</p> <p>Results</p> <p>CPAP effectively improved hypoxia. However, subjects had increased insulin and IR. Fasting ghrelin decreased significantly while leptin, adiponectin and resistin remained unchanged. Forty percent of patients gained weight significantly. Changes in body weight directly correlated with changes in insulin and IR. Ghrelin changes inversely correlated with changes in IR but did not change as a function of weight.</p> <p>Conclusions</p> <p>Weight change rather than elimination of hypoxia modulated alterations in IR in obese patients with OSA during the first six months of CPAP therapy.</p

Changes in Seizure Frequency and Test-Retest Scores on the Wechsler Adult Intelligence Scale

Test-retest performance on the Wechsler Adult Intelligence Scale (WAIS) of two groups of adult epilepsy patients are presented and compared. In one group, Seizures Improved (SI) group, seizure frequency had decreased during the test-retest interval, and in the other group, Seizures Unimproved (SU) group, the number of seizures had either increased or stayed the same over the test-retest interval. The SI group showed a significant test-retest improvement on WAIS Verbal IQ, Performance 1Q, and Full Scale IQ, as well as on eight of 11 WAIS subtests. In comparison, the SU group showed significant increases only on the Performance IQ and Object Assembly subtest. Furthermore, differences between the two groups were observed in the pattern of test-retest changes seen on the Performance measures relative to the Verbal measures. The results suggest that change in seizure frequency is one of the factors associated with test-retest changes in the intellectual functioning of epilepsy patients. RÉSUMÉ Les rÉsultats obtenus À I‘Échelle de WAIS (Wechsler Adults Intelligence Scale) a partir d'une passation I (test) et d'une passation II (retest) chez deux groupes d'Épileptiques adultes sont prÉsentÉs et compares: (a) Dans un groupe la frequence des crises a diminue dur-ant I'intervalle “test-retest” (c'est a dire dans I'inter-valle separant la passation I (test) de la passation II (retest): Groupe des crises ameliorees (SI: seizures improved), (b) Dans l'autre groupe le nombre des crises au contraire a augmente ou bien est reste iden-tique au cours de I'intervalle “test-retest”: Groupe des crises non ameliorees (SU: seizures unimproved). Le groupe des “crises ameliorees” montre une amelioration significative tant sur le plan du QIV (quotient de I'echelle verbale), que du QIP (quotient de I'echelle performance) et du QIG (quotient global), ainsi que de 8 des subtests parmi les onze que contien I'echelle. En comparaison le groupe des “crises non ameliorees” ne montre une amelioration significative qu'au niveau du QIP et en particulier sur le subtest d'assemblage d'ob-jets (celui-ci faisant partie de I'echelle performance). De plus, on observe entre les deux groupes des differences du “type” des modifications entrainees par la situation “test-retest”, sur les rÉsultats obtenus a I'echelle performance et ceux obtensus a I'echelle verbale. Ces rÉsultats permettent de suggerer que, dans le fonctionnement intellectuel des sujets epileptiques, les changements dans la frequence des crises sont un des facteurs a mettre en correlation avec les changements observes a partir de la situation “test-retest”. RESUMEN Se compararon dos grupos de adultos con epilepsia por medio del rendimiento en dos tests de WAIS. En un grupo, la frecuencia de los ataques habia disminuido en el intervalo entre el primer test y el segundo [grupo con mejoria (SI)], mientras que en el otro el mimero de crisis no habia variado o habia au-mentado [grupo sin mejoria (SU)]. El grupo SI mostro una mejoria en laescala verbal CI, en la realizacion CI, en la escala total de CI y en los subtests WAIS. En comparacion, el grupo SU solo mostro un aumento significativo en la realizacion CI y en el subtest de Reunion de Objetos. Ademas, se observaron diferen-cias entre los dos grupos en lo que respecta a la prim-era y a la segunda prueba en la realizacion de las medidas verbales. Los resultados sugieren que los cambios en la frecuencia de los ataques juegan un papel en lo que respecta a funciÓn intelectual cuando se compara el primer WAIS con el segundo. ZUSAMMENFASSUNG Test und Retest Ergebnisse im WAIS von 2 Gruppen erwachsener Epileptiker werden dargestellt und ver-glichen. In einer Gruppe hatte die Anfallshaufigkeit wahrend des Test-Retest-Intervalls abgenommen– verbesserte Gruppe (SI)–und in einer anderen Gruppe war die Anfallshaufigkeit entweder gestiegen oder gleich geblieben wahrend des Test-Retest-Intervalls– unveranderte Gruppe (SU). Die SI-Gruppe zeigte signifikante Verbesserung zwischen Test und Retest im Verbal-IQ des WAIS, im Handlungsteil und im Gesamt-IQ ebenso wie in 8 von 11 WAIS Subtests. Im Vergleich hierzu zeigte die SU-Gruppe signifikante Verbesserung nur im Handlungs-IQ und im Objekte-zuordnungs-Subtest. Weiterhin wurden Unterschiede zwischen den beiden Gruppen im Muster der Test-Retest-Veranderungen im Verhaltnis des Handlung-steils zum Verbalteil bemerkt. Die Ergebnisse lassen vermuten, dalJ die Veranderung der Anfallshaufigkeit einer der Faktoren ist, der hinsichtlich der in-tellektuellen Funktion anfallskranker Patienten Bezie-hungen zu den Veranderungen des Test-Retest-Ergeb-nis aufweist.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65457/1/j.1528-1157.1981.tb04334.x.pd

Predictors of Hospitalization for Injection Drug Users Seeking Care for Soft Tissue Infections

BACKGROUND: Soft tissue infections (STIs) from injection drug use are a common cause of Emergency Department visits, hospitalizations, and operating room procedures, yet little is known about factors that may predict the need for these costly medical services. OBJECTIVE: To describe a cohort of injection drug users seeking Emergency Department care for STIs and to identify risk factors associated with hospitalization. We hypothesized that participants who delayed seeking care would be hospitalized more often than those who did not. DESIGN: Cohort study using in-person structured interviews and medical record review. Logistic regression assessed the association between hospital admission and delay in seeking care as well as other demographic, clinical, and psychosocial factors. PARTICIPANTS: Injection drug users who sought Emergency Department care for STIs from May 2001 to March 2002. RESULTS: Of the 136 participants, 55 (40%) were admitted to the hospital. Delay in seeking care was not associated with hospital admission. Participants admitted for their infection were significantly more likely to be living in a shelter (P = .01) and to report being hospitalized 2 or more times in the past year (P < .01). CONCLUSIONS: We identified a subpopulation of injection drug users, mostly living in shelters, who were hospitalized frequently in the past year and who were more likely to be hospitalized for their current infections compared to others. As members of this subpopulation can be easily identified and located, they may benefit from interventions to reduce the health care utilization resulting from these infections

MTSS1 and SCAMP1 cooperate to prevent invasion in breast cancer

Cell–cell adhesions constitute the structural “glue” that retains cells together and contributes to tissue organisation and physiological function. The integrity of these structures is regulated by extracellular and intracellular signals and pathways that act on the functional units of cell adhesion such as the cell adhesion molecules/adhesion receptors, the extracellular matrix (ECM) proteins and the cytoplasmic plaque/peripheral membrane proteins. In advanced cancer, these regulatory pathways are dysregulated and lead to cell–cell adhesion disassembly, increased invasion and metastasis. The Metastasis suppressor protein 1 (MTSS1) plays a key role in the maintenance of cell–cell adhesions and its loss correlates with tumour progression in a variety of cancers. However, the mechanisms that regulate its function are not well-known. Using a system biology approach, we unravelled potential interacting partners of MTSS1. We found that the secretory carrier-associated membrane protein 1 (SCAMP1), a molecule involved in post-Golgi recycling pathways and in endosome cell membrane recycling, enhances Mtss1 anti-invasive function in HER2+/ER−/PR− breast cancer, by promoting its protein trafficking leading to elevated levels of RAC1-GTP and increased cell–cell adhesions. This was clinically tested in HER2 breast cancer tissue and shown that loss of MTSS1 and SCAMP1 correlates with reduced disease-specific survival. In summary, we provide evidence of the cooperative roles of MTSS1 and SCAMP1 in preventing HER2+/ER−/PR− breast cancer invasion and we show that the loss of Mtss1 and Scamp1 results in a more aggressive cancer cell phenotype

Diminished Self-Chaperoning Activity of the ΔF508 Mutant of CFTR Results in Protein Misfolding

The absence of a functional ATP Binding Cassette (ABC) protein called the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) from apical membranes of epithelial cells is responsible for cystic fibrosis (CF). Over 90% of CF patients carry at least one mutant allele with deletion of phenylalanine at position 508 located in the N-terminal nucleotide binding domain (NBD1). Biochemical and cell biological studies show that the ΔF508 mutant exhibits inefficient biosynthetic maturation and susceptibility to degradation probably due to misfolding of NBD1 and the resultant misassembly of other domains. However, little is known about the direct effect of the Phe508 deletion on the NBD1 folding, which is essential for rational design strategies of cystic fibrosis treatment. Here we show that the deletion of Phe508 alters the folding dynamics and kinetics of NBD1, thus possibly affecting the assembly of the complete CFTR. Using molecular dynamics simulations, we find that meta-stable intermediate states appearing on wild type and mutant folding pathways are populated differently and that their kinetic accessibilities are distinct. The structural basis of the increased misfolding propensity of the ΔF508 NBD1 mutant is the perturbation of interactions in residue pairs Q493/P574 and F575/F578 found in loop S7-H6. As a proof-of-principle that the S7-H6 loop conformation can modulate the folding kinetics of NBD1, we virtually design rescue mutations in the identified critical interactions to force the S7-H6 loop into the wild type conformation. Two redesigned NBD1-ΔF508 variants exhibited significantly higher folding probabilities than the original NBD1-ΔF508, thereby partially rescuing folding ability of the NBD1-ΔF508 mutant. We propose that these observed defects in folding kinetics of mutant NBD1 may also be modulated by structures separate from the 508 site. The identified structural determinants of increased misfolding propensity of NBD1-ΔF508 are essential information in correcting this pathogenic mutant

Citizen science in schools: Engaging students in research on urban habitat for pollinators

Citizen science can play an important role in school science education. Citizen science is particularly relevant to addressing current societal environmental sustainability challenges, as it engages the students directly with environmental science and gives students an understanding of the scientific process. In addition, it allows students to observe local representations of global challenges. Here, we report a citizen science programme designed to engage school-age children in real-world scientific research. The programme used standardized methods deployed across multiple schools through scientist–school partnerships to engage students with an important conservation problem: habitat for pollinator insects in urban environments. Citizen science programmes such as the programme presented here can be used to enhance scientific literacy and skills. Provided key challenges to maintain data quality are met, this approach is a powerful way to contribute valuable citizen science data for understudied, but ecologically important study systems, particularly in urban environments across broad geographical areas

A sequence-based genetic linkage map as a reference for Brassica rapa pseudochromosome assembly

<p>Abstract</p> <p>Background</p> <p><it>Brassica rapa </it>is an economically important crop and a model plant for studies concerning polyploidization and the evolution of extreme morphology. The multinational <it>B. rapa </it>Genome Sequencing Project (BrGSP) was launched in 2003. In 2008, next generation sequencing technology was used to sequence the <it>B. rapa </it>genome. Several maps concerning <it>B. rapa </it>pseudochromosome assembly have been published but their coverage of the genome is incomplete, anchoring approximately 73.6% of the scaffolds on to chromosomes. Therefore, a new genetic map to aid pseudochromosome assembly is required.</p> <p>Results</p> <p>This study concerns the construction of a reference genetic linkage map for <it>Brassica rapa</it>, forming the backbone for anchoring sequence scaffolds of the <it>B. rapa </it>genome resulting from recent sequencing efforts. One hundred and nineteen doubled haploid (DH) lines derived from microspore cultures of an F1 cross between a Chinese cabbage (<it>B. rapa </it>ssp. <it>pekinensis</it>) DH line (Z16) and a rapid cycling inbred line (L144) were used to construct the linkage map. PCR-based insertion/deletion (InDel) markers were developed by re-sequencing the two parental lines. The map comprises a total of 507 markers including 415 InDels and 92 SSRs. Alignment and orientation using SSR markers in common with existing <it>B. rapa </it>linkage maps allowed ten linkage groups to be identified, designated A01-A10. The total length of the linkage map was 1234.2 cM, with an average distance of 2.43 cM between adjacent marker loci. The lengths of linkage groups ranged from 71.5 cM to 188.5 cM for A08 and A09, respectively. Using the developed linkage map, 152 scaffolds were anchored on to the chromosomes, encompassing more than 82.9% of the <it>B. rapa </it>genome. Taken together with the previously available linkage maps, 183 scaffolds were anchored on to the chromosomes and the total coverage of the genome was 88.9%.</p> <p>Conclusions</p> <p>The development of this linkage map is vital for the integration of genome sequences and genetic information, and provides a useful resource for the international <it>Brassica </it>research community.</p

Natural Variation in the Thermotolerance of Neural Function and Behavior due to a cGMP-Dependent Protein Kinase

Although it is acknowledged that genetic variation contributes to individual differences in thermotolerance, the specific genes and pathways involved and how they are modulated by the environment remain poorly understood. We link natural variation in the thermotolerance of neural function and behavior in Drosophila melanogaster to the foraging gene (for, which encodes a cGMP-dependent protein kinase (PKG)) as well as to its downstream target, protein phosphatase 2A (PP2A). Genetic and pharmacological manipulations revealed that reduced PKG (or PP2A) activity caused increased thermotolerance of synaptic transmission at the larval neuromuscular junction. Like synaptic transmission, feeding movements were preserved at higher temperatures in larvae with lower PKG levels. In a comparative assay, pharmacological manipulations altering thermotolerance in a central circuit of Locusta migratoria demonstrated conservation of this neuroprotective pathway. In this circuit, either the inhibition of PKG or PP2A induced robust thermotolerance of neural function. We suggest that PKG and therefore the polymorphism associated with the allelic variation in for may provide populations with natural variation in heat stress tolerance. for's function in behavior is conserved across most organisms, including ants, bees, nematodes, and mammals. PKG's role in thermotolerance may also apply to these and other species. Natural variation in thermotolerance arising from genes involved in the PKG pathway could impact the evolution of thermotolerance in natural populations

The emergent rhizosphere: imaging the development of the porous architecture at the root-soil interface

The rhizosphere is the zone of soil infuenced by a plant root and is critical for plant health and nutrient acquisition. All below ground resources must pass through this dynamic zone prior to their capture by plant roots. However, researching the undisturbed rhizosphere has proved very challenging. Here we compare the temporal changes to the intact rhizosphere pore structure during the emergence of a developing root system in diferent soils. High resolution X-ray Computed Tomography (CT) was used to quantify the impact of root development on soil structural change, at scales relevant to individual micro-pores and aggregates (µm). A comparison of micro-scale structural evolution in homogenously packed soils highlighted the impacts of a penetrating root system in changing the surrounding porous architecture and morphology. Results indicate the structural zone of infuence of a root can be more localised than previously reported (µm scale rather than mm scale). With time, growing roots signifcantly alter the soil physical environment in their immediate vicinity through reducing root-soil contact and crucially increasing porosity at the root-soil interface and not the converse as has often been postulated. This ‘rhizosphere pore structure’ and its impact on associated dynamics are discussed