Leveraging Coupled Solvatofluorochromism and Fluorescence Quenching in Nitrophenyl-Containing Thiazolothiazoles for Efficient Organic Vapor Sensing.

Solvatofluorochromic molecules provide strikingly high fluorescent outputs to monitor a wide range of biological, environmental, or materials-related sensing processes. Here, thiazolo[5,4-d]thiazole (TTz) fluorophores equipped with simple alkylamino and nitrophenyl substituents for solid-state, high-performance chemo-responsive sensing applications are reported. Nitroaromatic substituents are known to strongly quench dye fluorescence, however, the TTz core subtly modulates intramolecular charge transfer (ICT) enabling strong, locally excited-state fluorescence in non-polar conditions.

Opposing kinesin complexes queue at plus tips to ensure microtubule catastrophe at cell ends.

In fission yeast, the lengths of interphase microtubule (iMT) arrays are adapted to cell length to maintain cell polarity and to help centre the nucleus and cell division ring. Here, we show that length regulation of iMTs is dictated by spatially regulated competition between MT-stabilising Tea2/Tip1/Mal3 (Kinesin-7) and MT-destabilising Klp5/Klp6/Mcp1 (Kinesin-8) complexes at iMT plus ends. During MT growth, the Tea2/Tip1/Mal3 complex remains bound to the plus ends of iMT bundles, thereby restricting access to the plus ends by Klp5/Klp6/Mcp1, which accumulate behind it.

Some assembly required: Redefining the mitotic checkpoint.

The spindle assembly checkpoint (also known as the spindle or mitotic checkpoint) is a surveillance system that ensures fidelity of chromosome segregation. Here we suggest, in light of historical and more recent evidence, that this signaling system monitors kinetochore attachment and spindle assembly by two distinct, but functionally overlapping, pathways.

Identification of a Sgo2-Dependent but Mad2-Independent Pathway Controlling Anaphase Onset in Fission Yeast.

The onset of anaphase is triggered by activation of the anaphase-promoting complex/cyclosome (APC/C) following silencing of the spindle assembly checkpoint (SAC). APC/C triggers ubiquitination of Securin and Cyclin B, which leads to loss of sister chromatid cohesion and inactivation of Cyclin B/Cdk1, respectively. This promotes relocalization of Aurora B kinase and other components of the chromosome passenger complex (CPC) from centromeres to the spindle midzone.

Bub3-Bub1 Binding to Spc7/KNL1 Toggles the Spindle Checkpoint Switch by Licensing the Interaction of Bub1 with Mad1-Mad2.

The spindle assembly checkpoint (SAC) ensures that sister chromatids do not separate until all chromosomes are attached to spindle microtubules and bi-oriented. Spindle checkpoint proteins, including Mad1, Mad2, Mad3 (BubR1), Bub1, Bub3, and Mph1 (Mps1), are recruited to unattached and/or tensionless kinetochores. SAC activation catalyzes the conversion of soluble Mad2 (O-Mad2) into a form (C-Mad2) that binds Cdc20, BubR1, and Bub3 to form the mitotic checkpoint complex (MCC), a potent inhibitor of the anaphase-promoting complex (APC/C).

Sharpening the anaphase switch.

The segregation of sister chromatids during mitosis is one of the most easily visualized, yet most remarkable, events during the life cycle of a cell. The accuracy of this process is essential to maintain ploidy during cell duplication. Over the past 20 years, substantial progress has been made in identifying components of both the kinetochore and the mitotic spindle that generate the force to move mitotic chromosomes.

Interplay between mitotic kinesins and the Aurora kinase-PP1 (protein phosphatase 1) axis.

Correct transmission of genetic information from mother to daughter cells is necessary for development and survival. Accurate segregation is achieved by bipolar attachment of sister kinetochores in each chromatid pair to spindle microtubules emanating from opposite spindle poles, a process known as chromosome bi-orientation. Achieving this requires dynamic interplay between kinetochore proteins, kinesin motor proteins and cell cycle regulators.

Meeting report: mitosis and nuclear structure.

The Company of Biologists Workshop entitled 'Mitosis and Nuclear Structure' was held at Wiston House, West Sussex in June 2013. It provided a unique and timely opportunity for leading experts from different fields to discuss not only their own work but also its broader context. Here we present the proceedings of this meeting and several major themes that emerged from the crosstalk between the two, as it turns out, not so disparate fields of mitosis and nuclear structure.

Cell biology: polar expeditions for PP1.

A new study shows that phospho-dependent expulsion of type-1-phosphatase (PP1) from the spindle pole by Fin1 (NIMA) kinase ensures switch-like activation of Cyclin B-Cdk1 at the G2/M transition.

Phosphodependent recruitment of Bub1 and Bub3 to Spc7/KNL1 by Mph1 kinase maintains the spindle checkpoint.

The spindle assembly checkpoint (SAC) is the major surveillance system that ensures that sister chromatids do not separate until all chromosomes are correctly bioriented during mitosis. Components of the checkpoint include Mad1, Mad2, Mad3 (BubR1), Bub3, and the kinases Bub1, Mph1 (Mps1), and Aurora B. Checkpoint proteins are recruited to kinetochores when individual kinetochores are not bound to spindle microtubules or not under tension.

Plo1 phosphorylates Dam1 to promote chromosome bi-orientation in fission yeast.

The fungal-specific heterodecameric outer kinetochore DASH complex facilitates the interaction of kinetochores with spindle microtubules. In budding yeast, where kinetochores bind a single microtubule, the DASH complex is essential, and phosphorylation of Dam1 by the Aurora kinase homologue, Ipl1, causes detachment of kinetochores from spindle microtubules. We demonstrate that in the distantly related fission yeast, where the DASH complex is not essential for viability and kinetochores bind multiple microtubules, Dam1 is instead phosphorylated on serine 143 by the Polo kinase homologue, Plo1, during prometaphase and metaphase.

Nsk1 ensures accurate chromosome segregation by promoting association of kinetochores to spindle poles during anaphase B.

Type 1 phosphatase (PP1) antagonizes Aurora B kinase to stabilize kinetochore-microtubule attachments and to silence the spindle checkpoint. We screened for factors that exacerbate the growth defect of Δdis2 cells, which lack one of two catalytic subunits of PP1 in fission yeast, and identified Nsk1, a novel protein required for accurate chromosome segregation. During interphase, Nsk1 resides in the nucleolus but spreads throughout the nucleoplasm as cells enter mitosis.

Spindle checkpoint silencing requires association of PP1 to both Spc7 and kinesin-8 motors.

The spindle checkpoint is the prime cell-cycle control mechanism that ensures sister chromatids are bioriented before anaphase takes place. Aurora B kinase, the catalytic subunit of the chromosome passenger complex, both destabilizes kinetochore attachments that do not generate tension and simultaneously maintains the spindle checkpoint signal. However, it is unclear how the checkpoint is silenced following chromosome biorientation.

Bub3p facilitates spindle checkpoint silencing in fission yeast.

Although critical for spindle checkpoint signaling, the role kinetochores play in anaphase promoting complex (APC) inhibition remains unclear. Here we show that spindle checkpoint proteins are severely depleted from unattached kinetochores in fission yeast cells lacking Bub3p. Surprisingly, a robust mitotic arrest is maintained in the majority of bub3 Delta cells, yet they die, suggesting that Bub3p is essential for successful checkpoint recovery.

Latrunculin A delays anaphase onset in fission yeast by disrupting an Ase1-independent pathway controlling mitotic spindle stability.

It has been proposed previously that latrunculin A, an inhibitor of actin polymerization, delays the onset of anaphase by causing spindle misorientation in fission yeast. However, we show that Delta mto1 cells, which are defective in nucleation of cytoplasmic microtubules, have profoundly misoriented spindles but are not delayed in the timing of sister chromatid separation, providing compelling evidence that fission yeast does not possess a spindle orientation checkpoint. Instead, we show that latrunculin A delays anaphase onset by disrupting interpolar microtubule stability.

The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast.

In fission yeast centromeres cluster at the nuclear envelope in a region underlying the spindle pole body during interphase, an arrangement known as a Rabl configuration. We have identified a strain in which one pair of sister kinetochores is unclustered from the others and binds the nuclear envelope at a point distal to the spindle pole body. We show that during mitosis unclustered kinetochores are captured by intranuclear spindle microtubules which then pull the kinetochores back to one of the two spindle poles before they are bi-oriented on the mitotic spindle.

The DASH complex and Klp5/Klp6 kinesin coordinate bipolar chromosome attachment in fission yeast.

We identified a truncated allele of dam1 as a multicopy suppressor of the sensitivity of cdc13-117 (cyclin B) and mal3-1 (EB-1) cells to thiabendazole, a microtubule poison. We find that Dam1 binds to the plus end of spindle microtubules and kinetochores as cells enter mitosis and this is dependent on other components of the fission yeast DASH complex, including Ask1, Duo1, Spc34 and Dad1. By contrast, Dad1 remains bound to kinetochores throughout the cell cycle and its association is dependent on the Mis6 and Mal2, but not Mis12, Nuf2 or Cnp1, kinetochore proteins.

Considerations involved with the use of semipermeable membrane devices for monitoring environmental contaminants.

Semipermeable membrane devices (SPMDs) are used with increasing frequency, and throughout the world as samplers of organic contaminants. The devices can be used to detect a variety of lipophilic chemicals in water, sediment/soil, and air. SPMDs are designed to sample nonpolar, hydrophobic chemicals.

Organochlorine Contaminants in Double-Crested Cormorants from Green Bay,Wisconsin: II. Effects of an Extract Derived from Cormorant Eggs onthe Chicken Embryo.

White Leghorn chicken (Gallus domesticus) eggswere injected prior to incubation with one of four concentrations (0.001,0.01, 0.

Effects of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) injected into the yolks of chicken (Gallus domesticus) eggs prior to incubation.

The yolks of White Leghorn chicken (Gallus domesticus) eggs were injected prior to incubation with either 3,3',4,4',5-pentachlorobiphenyl (PCB 126) at doses ranging from 0.1 to 12.8 microg/kg egg or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at doses ranging from 0.

Organochlorine contaminants in double-crested cormorants from Green Bay, WI: I. Large-scale extraction and isolation from eggs using semi-permeable membrane dialysis.

A 41.3-kg sample of double-crested cormorant (Phalacrocorax auritus) egg contents was extracted, yielding over 2 L of egg lipid. The double-crested cormorant (DCC) egg extract, after clean-up and concentration, was intended for use in egg injection studies to determine the embryotoxicity of the organic contaminants found within the eggs.

The in vitro and in vivo effects of isoflurane and nitrous oxide on platelet aggregation.

In view of the possible antiaggregation effects of newer general anesthetics we investigated the in vitro and in vivo effects of isoflurane and nitrous oxide on platelet aggregation. Platelets obtained from 18 healthy volunteers, were exposed in vitro for 30 min in a closed chamber to oxygen-carbon dioxide (90%, 5%) (control), oxygen-carbon dioxide-nitrous oxide (80%), or oxygen-carbon dioxide-isoflurane (1.5%) with or without nitrous oxide (80%).

Private physicians in ambulatory care training in U.S. medical schools.

The contribution of private physicians to medical student education in ambulatory care was determined by a questionnaire directed to departments of family practice, internal medicine, and pediatrics in 124 U.S. medical schools and their branch campuses.