Precocious cleavage furrows simultaneously move and ingress when kinetochore microtubules are depolymerized in <Emphasis Type="Italic">Mesostoma ehrenbergii</Emphasis> spermatocytes

A “precocious” cleavage furrow develops and ingresses during early prometaphase in Mesostoma ehrenbergii spermatocytes (Forer and Pickett-Heaps Eur J Cell Biol 89:607-618, 2010). In response to chromosome movements which regularly occur during prometaphase and that alter the balance of chromosomes in the two half-spindles, the precocious furrow shifts its position along the cell, moving 2–3 μm towards the half cell with fewer chromosomes (Ferraro-Gideon et al. Cell Biol Int 37:892-898, 2013). This process continues until proper segregation is achieved and the cell enters anaphase with the cleavage furrow again in the middle of the cell. At anaphase, the furrow recommences ingression. Spindle microtubules (MTs) are implicated in various furrow positioning models, and our experiments studied the responses of the precocious furrows to the absence of spindle MTs. We depolymerized spindle MTs during prometaphase using various concentrations of nocodazole (NOC) and colcemid. The expected result is that the furrow should regress and chromosomes remain in the midzone of the cell (Cassimeris et al. J Cell Sci 96:9-15, 1990). Instead, the furrows commenced ingression and all three bivalent chromosomes moved to one pole while the univalent chromosomes, that usually reside at the two poles, either remained at their poles or moved to the opposite pole along with the bivalents, as described elsewhere (Fegaras and Forer 2018). The microtubules were completely depolymerized by the drugs, as indicated by immunofluorescence staining of treated cells (Fegaras and Forer 2018), and in the absence of microtubules, the furrows often ingressed (in 33/61 cells) at a rate similar to normal anaphase ingression (~?1 μm/min), while often simultaneously moving toward one pole. Thus, these results indicate that in the absence of anaphase and of spindle microtubules, cleavage furrows resume ingression.     

The release of cytochrome c and the regulation of the programmed cell death progress in the endosperm of winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) under waterlogging

It has been shown in mammalian systems that the mitochondria can play a key role in the regulation of apoptosis by releasing intermembrane proteins (such as cytochrome c) into the cytosol. Cytochrome c released from the mitochondria to the cytoplasm activates proteolytic enzyme cascades, leading to specific nuclear DNA degradation and cell death. This pathway is considered to be one of the important regulatory mechanisms of apoptosis. Previous studies have shown that endosperm cell development in wheat undergoes specialized programmed cell death (PCD) and that waterlogging stress accelerates the PCD process; however, little is known regarding the associated molecular mechanism. In this study, changes in mitochondrial structure, the release of cytochrome c, and gene expression were studied in the endosperm cells of the wheat (Triticum aestivum L.) cultivar “huamai 8” during PCD under different waterlogging durations. The results showed that waterlogging aggravated the degradation of mitochondrial structure, increased the mitochondrial permeability transition (MPT), and decreased mitochondrial transmembrane potential (ΔΨm), resulting in the advancement of the endosperm PCD process. In situ localization and western blotting of cytochrome c indicated that with the development of the endosperm cell, cytochrome c was gradually released from the mitochondria to the cytoplasm, and waterlogging stress led to an advancement and increase in the release of cytochrome c. In addition, waterlogging stress resulted in the increased expression of the voltage-dependent anion channel (VDAC) and adenine nucleotide translocator (ANT), suggesting that the mitochondrial permeability transition pore (MPTP) may be involved in endosperm PCD under waterlogging stress. The MPTP inhibitor cyclosporine A effectively suppressed cell death and cytochrome c release during wheat endosperm PCD. Our results indicate that the mitochondria play important roles in the PCD of endosperm cells and that the increase in mitochondrial damage and corresponding release of cytochrome c may be one of the major causes of endosperm PCD advancement under waterlogging.     

Differential expression of salt-responsive genes to salinity stress in salt-tolerant and salt-sensitive rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) at seedling stage

The understanding of physio-biochemical and molecular attributes along with morphological traits contributing to the salinity tolerance is important for developing salt-tolerant rice (Oryza sativa L.) varieties. To explore these facts, rice genotypes CSR10 and MI48 with contrasting salt tolerance were characterized under salt stress (control, 75 and 150 mM NaCl) conditions. CSR10 expressed higher rate of physio-biochemical parameters, maintained lower Na/K ratio in shoots, and restricted Na translocation from roots to shoots than MI48. The higher expression of genes related to the osmotic module (DREB2A and LEA3) and ionic module (HKT2;1 and SOS1) in roots of CSR10 suppresses the stress, enhances electrolyte leakage, promotes the higher compatible solute accumulation, and maintains cellular ionic homeostasis leading to better salt stress tolerance than MI48. This study further adds on the importance of these genes in salt tolerance by comparing their behaviour in contrasting rice genotypes and utilizing specific marker to identify salinity-tolerant accessions/donors among germplasm; overexpression of these genes which accelerate the selection procedure precisely has been shown.     

Long-range interactions of <Emphasis Type="Italic">Chara</Emphasis> chloroplasts are sensitive to plasma-membrane H<Superscript>+</Superscript> flows and comprise separate photo- and dark-operated pathways

Local illumination of the characean internode with a 30-s pulse of white light was found to induce the delayed transient increase of modulated chlorophyll fluorescence in shaded cell parts, provided the analyzed region is located downstream in the cytoplasmic flow at millimeter distances from the light spot. The fluorescence response to photostimulation of a remote cell region indicates that the metabolites produced by source chloroplasts in an illuminated region are carried downstream with the cytoplasmic flow, thus ensuring long-distance communications between anchored plastids in giant internodal cells. The properties of individual stages of metabolite signaling are not yet well known. We show here that the export of assimilates and/or reducing equivalents from the source chloroplasts into the flowing cytoplasm is largely insensitive to the direction of plasma-membrane H⁺ flows, whereas the events in sink regions where these metabolites are delivered to the acceptor chloroplasts under dim light are controlled by H⁺ fluxes across the plasma membrane. The fluorescence response to local illumination of remote cell regions was best pronounced under weak background light and was also observed in a modified form within 1–2 min after the transfer of cell to darkness. The fluorescence transients in darkened cells were suppressed by antimycin A, an inhibitor of electron transfer from ferredoxin to plastoquinone, whereas the fluorescence response under background light was insensitive to this inhibitor. We conclude that the accumulation of reduced metabolites in the stroma leads to the reduction of photosystem II primary quinone acceptor (Q_A) via two separate (photochemical and non-photochemical) pathways.     

Chromosomes selectively detach at one pole and quickly move towards the opposite pole when kinetochore microtubules are depolymerized in <Emphasis Type="Italic">Mesostoma ehrenbergii</Emphasis> spermatocytes

In a typical cell division, chromosomes align at the metaphase plate before anaphase commences. This is not the case in Mesostoma spermatocytes. Throughout prometaphase, the three bivalents persistently oscillate towards and away from either pole, at average speeds of 5–6 μm/min, without ever aligning at a metaphase plate. In our experiments, nocodazole (NOC) was added to prometaphase spermatocytes to depolymerize the microtubules. Traditional theories state that microtubules are the producers of force in the spindle, either by tubulin depolymerizing at the kinetochore (PacMan) or at the pole (Flux). Accordingly, if microtubules are quickly depolymerized, the chromosomes should arrest at the metaphase plate and not move. However, in 57/59 cells, at least one chromosome moved to a pole after NOC treatment, and in 52 of these cells, all three bivalents moved to the same pole. Thus, the movements are not random to one pole or other. After treatment with NOC, chromosome movement followed a consistent pattern. Bivalents stretched out towards both poles, paused, detached at one pole, and then the detached kinetochores quickly moved towards the other pole, reaching initial speeds up to more than 200 μm/min, much greater than anything previously recorded in this cell. As the NOC concentration increased, the average speeds increased and the microtubules disappeared faster. As the kinetochores approached the pole, they slowed down and eventually stopped. Similar results were obtained with colcemid treatment. Confocal immunofluorescence microscopy confirms that microtubules are not associated with moving chromosomes. Thus, these rapid chromosome movements may be due to non-microtubule spindle components such as actin-myosin or the spindle matrix.     

Contribution of native phosphorous-solubilizing bacteria of acid soils on phosphorous acquisition in peanut (<Emphasis Type="Italic">Arachis hypogaea</Emphasis> L.)

The present investigation analyzes the in vitro P solubilization [Ca-P, Al-P, Fe(II)-P, and Fe(III)-P] efficiency of native PSB strains from acid soils of Odisha and exploitation of the same through biofertilization in peanut (Arachis hypogaea L.) growth and P acquisition. One hundred six numbers of soil samples with pH ≤ 5.50 were collected from five districts of Odisha viz., Balasore, Cuttack, Khordha, Keonjhar, and Mayurbhanj. One bacterial isolate from each district were selected and analyzed for their P solubilization efficiency in National Botanical Research Institute Phosphate broths with Ca, Al, and Fe-complexed phosphates. CTC12 and KHD08 transformed more amount of soluble P from Ca-P (CTC12 393.30 mg/L; KHD08 465.25 mg/L), Al-P (CTC12 40.00 mg/L; KHD08 34.50 mg/L), Fe(III)-P (CTC12 175.50 mg/L; KHD08 168.75 mg/L), and Fe(II)-P (CTC12 47.40 mg/L; KHD08 42.00 mg/L) after 8 days of incubation. The bioconversion of P by all the five strains in the broth medium followed the order Ca-P > Fe(III)-P > Fe(II)-P > Al-P. The identified five strains were Bacillus cereus BLS18 (KT582541), Bacillus amyloliquefaciens CTC12 (KT633845), Burkholderia cepacia KHD08 (KT717633), B. cepacia KJR03 (KT717634), and B. cepacia K1 (KM030037) and further studied for biofertilization effects on peanut. CTC12 and KHD08 enhanced the soil available P around 65 and 58% and reduced the amount of each Al³⁺ about 79 and 81%, respectively, over the uninoculated control pots in the peanut rhizosphere. Moreover, all tested PSB strains could be able to successfully mobilize P from inorganic P fractions (non-occluded Al-P and Fe-P). The strains CTC12 and KHD08 increased the pod yield (114 and 113%), shoot P (92 and 94%), and kernel P (100 and 101%), respectively, over the control. However, B. amyloliquefaciens CTC12 and B. cepacia KHD08 proved to be the potent P solubilizers in promoting peanut growth and yield.     

CONSUMERS REPORT PREFERENCES WHEN THEY SHOULD NOT: A CROSS-CULTURAL STUDY

If a chi‐squared analysis were to be performed to determine whether preferences were significant in a paired preference test, the appropriate expected frequencies in the analysis would represent those that would occur should the consumers have no preference. One way of determining these ‘no preference’frequencies, for a particular test situation, would be to note the preference responses obtained when the stimuli were putatively identical. Over 2000 consumers were given paired preference tests in which the stimuli were putatively identical. Response conditions and consumer groups were varied and the proportions of preference and no preference responses were noted. In a preliminary experiment, further research was seen to be justified when for putatively identical stimuli, judges did not exclusively express lack of preference; many expressed a preference for one or other of the stimuli. Further experiments were conducted using a written response condition and putatively identical potato chips (potato crisps) as stimuli. Using a single ‘no preference’option, variation in the placement of this option at either first, second or third place on the response sheet had no significant effect on the response frequencies. The proportion of ‘no preference’responses was approximately 30% in all cases. A previously reported 40‐20‐40 distribution was not always confirmed. The experiment was repeated with Korean consumers; these had fewer ‘no preference’responses. Deriving preferences from hedonic scales, rather than having judges respond to preference options, increased the proportion of ‘no preference’responses, with American judges still having more than Korean judges. Yet there are logical objections to extracting preference data from hedonic scales. Increasing the number of ‘no preference’options to two or three, had the effect of increasing the number of ‘no preference’responses up to as much as approximately 60%. Extending the results to Koreans, using two ‘no preference’options, it was seen that only the judges in an anonymous response condition had significantly fewer ‘no preference’responses than Americans. The use of these response frequencies as expected frequencies in chi squared analyses was illustrated, after adjustments for counterbalancing.     

A quantum chemistry evaluation of the stereochemical activity of the lone pair in Pb<Superscript>II</Superscript> complexes with sequestering ligands

The stereochemical activity of the lone pair on Pb^II complexes is assessed using several theoretical methods, including structural analyses, computations of Fukui functions, natural bond orbitals, electron localization function, investigation of the electron density and of its laplacian. The attention is focused on four octadentate N-carbamoylmethyl-substituted tetraazamacrocycles of various ring sizes ranging from 8 to 14 atoms associated with the Pb^II cation. The theoretical study illustrates the geometrical constraints imposed by the ring structure which limits the spatial development of the lone pair but without fully preventing it. For a given coordination number, the lone pair activity is strongly correlated to the geometry of the ligand and in particular to the size of the cage that the ligand forms around the Pb^II cation. Some limitations of the theoretical tools used are also evidenced, among them the necessity to sample around a critical point instead of just analyzing its nature. In the case of the laplacian of the electron density, a visualization method is introduced to moderate the results based only on the nature of a critical point. These limitations should also be related to the difficulty to extend the lone pair concept for the heaviest atoms of the classification.     

Methylenecyclopropene: local vision of the first <Superscript>1</Superscript>B<Subscript>2</Subscript> excited state

The ¹A₁ ground and the first ¹B₂ excited states of the methylenecyclopropene (triafulvene) are described by localized wave functions, based on 20 structures valence bond structures. The results are compared to CASSCF(4,4) calculations for both the energetics and the dipole moment. Additional calculations with partial electronic delocalization are presented, and it is shown that the dipole moment modification does not correspond to a situation where the antiaromatic situation prevails (with 4n electrons in the cycle). Part of the analysis uses a “trust factor” that helps to decide if a wave function is appropriate to describe a given state. The trust factor compares the VB wave function to the CASSCF’s with their overlap. Finally, the valence bond density is used to produce density maps that illustrate the electron transfer upon excitation.

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Graphical Abstract A projector-based method compares CASSCF wave functions to local wave functions, including Lewis structures as shown in the picture. A “trust factor” (τ) is obtained. Both the ground state and the first excited state of the methylenecyclopropene are discussed