Polarization and cell-fate decision facilitated by the adaptor Ste50 in Saccharomyces cerevisiae

Polarization or directional growth is a major morphological change that occurs in yeast cells during pheromone response to mate with the opposite partner. In the pheromone signaling pathway, the adaptor Ste50 is required to bind MAP3K Ste11 for proper polarization; cells lacking Ste50 are impaired in polarization. Direct involvement of Ste50 in the polarization process has not been explored systematically. Here, we used single-cell fluorescent time-lapse microscopy to characterize Ste50 involvement in the establishment of cell polarity. We found early localization of Ste50 patches on the cell cortex that mark the point of shmoo initiation, these polarity sites move, and patches remain associated with the growing shmoo tip in a pheromone concentration-dependent manner until shmoo maturation. By quantitative analysis we show that polarization corelates with the rising levels of Ste50 enabling rapid individual cell responses to pheromone that corresponds to a critical level of Ste50 at the initial G1 phase. Suggesting Ste50 to be a pheromone responsive gene. We exploited the quantitative differences in the pattern of Ste50 expression to corelate with the cell-cell phenotypic heterogeneity showing Ste50 involvement in the cellular differentiation choices. Taken together, these findings present spatiotemporal localization of Ste50 during yeast polarization, suggesting that Ste50 is a component of the polarisome, and plays a critical role in regulating the polarized growth of shmoo during pheromone response.

Regulation of plant phototropic growth by NPH3/RPT2-like substrate phosphorylation and 14-3-3 binding

Polarity underlies all directional growth responses in plants including growth towards the light (phototropism). The plasma-membrane associated protein, NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) is a key determinant of phototropic growth which is regulated by phototropin (phot) AGC kinases. Here we demonstrate that NPH3 is directly phosphorylated by phot1 within a conserved C-terminal consensus sequence (RxS) that is necessary to promote phototropism and petiole positioning in Arabidopsis. RxS phosphorylation also triggers 14-3-3 binding combined with changes in NPH3 phosphorylation and localisation status. Mutants of NPH3 that are unable to bind or constitutively bind 14-3-3 s show compromised functionality consistent with a model where phototropic curvature is established by signalling outputs arising from a gradient of NPH3 RxS phosphorylation across the stem. Our findings therefore establish that NPH3/RPT2-Like (NRL) proteins are phosphorylation targets for plant AGC kinases. Moreover, RxS phosphorylation is conserved in other members of the NRL family, suggesting a common mechanism of regulating plant growth to the prevailing light environment.

Continuous tracking of gravistimulated roots in a chambered coverslip by confocal microscopy allows first glimpse on mechanoadaptation of cell files during curvature initiation

Plant cell properties are defined by its proteome and metabolome, which depend on the genetic background together with environmental conditions. Mechanical responses of individual cells to plant internal and external stimuli modulate organ movement and ensure thereby plant survival as sessile organism in a constantly changing environment. The root is a complex, three-dimensional object, which continuously modifies its growth path. Autonomous and paratonic root movements are both orchestrated by different signaling pathways, whereby auxin modulated directional growth adaptations, including gravitropic response, were already subject of manifold studies. But we still know very little about how cells adapt upon gravitropic stimulus to initiate curvature establishment, which is required to align root tip growth again along the gravitropic vector. This manuscript shows first insights into cell file movements upon gravitropic stimulus of Arabidopsis thaliana roots that initiate curvature establishment. The roots were grown shaded from light and without exogenous sucrose supplementation, both growth conditions that are known to negatively interfere with directed root growth, which allowed a more uniform tracking of root bending by using a confocal microscope with vertical stage.

Single-Cell Imaging Reveals That Staphylococcus aureus Is Highly Competitive Against Pseudomonas aeruginosa on Surfaces

Pseudomonas aeruginosa and Staphylococcus aureus frequently occur together in polymicrobial infections, and their interactions can complicate disease progression and treatment options. While interactions between P. aeruginosa and S. aureus have been extensively described using planktonic batch cultures, little is known about whether and how individual cells interact with each other on solid substrates. This is important because both species frequently colonize surfaces to form aggregates and biofilms in infections. Here, we performed single-cell time-lapse fluorescence microscopy, combined with automated image analysis, to describe interactions between P. aeruginosa PAO1 with three different S. aureus strains (Cowan I, 6850, JE2) during microcolony growth on agarose surfaces. While P. aeruginosa is usually considered the dominant species, we found that the competitive balance tips in favor of S. aureus on surfaces. We observed that all S. aureus strains accelerated the onset of microcolony growth in competition with P. aeruginosa and significantly compromised P. aeruginosa growth prior to physical contact. Upon direct contact, JE2 was the most competitive S. aureus strain, simply usurping P. aeruginosa microcolonies, while 6850 was the weakest competitor itself suppressed by P. aeruginosa. Moreover, P. aeruginosa reacted to the assault of S. aureus by showing increased directional growth and expedited expression of quorum sensing regulators controlling the synthesis of competitive traits. Altogether, our results reveal that quantitative single-cell live imaging has the potential to uncover microbial behaviors that cannot be predicted from batch culture studies, and thereby contribute to our understanding of interactions between pathogens that co-colonize host-associated surfaces during polymicrobial infections.

The intertwined relationship of shadow banking and commercial banks’ deposit growth: evidence from India

Purpose While traditionally it was believed that shadow banking undercuts business from traditional commercial banks, the time has now arrived to examine the various innovative practices used by various shadow banks and non-banking finance companies (NBFCs) to explore various collaboration and competition possibilities. The parallel existence of the traditional and shadow banking systems creates a market environment where both the entities are inter-dependent for growth and development with their edge of advantages and snags. This study aims to investigate the development and growth of deposits in NBFCs and scheduled commercial banks (SCBs) and, through the adoption of innovative practices, highlights possible growth opportunities for both ahead. Design/methodology/approach This study uses yearly bank deposit data from 1998 to 2019. This study incorporates univariate autoregressive integrated moving average modeling to predict the future deposit growth of SCBs and NBFCs in India. Findings This study concludes that both the entities, i.e. NBFCs and SCBs, will experience deposit growth; however, the proportionate growth of deposits in SCBs will be higher than NBFCs. Research limitations/implications This study concludes that the NBFCs will exhibit higher growth in the future. Thus, a strengthened regulatory framework will boost the growth of the NBFCs, providing a safe environment to the investor. Further, as this study primarily considers only deposit-taking NBFCs and commercial banks and a single variable – “deposit” to predict its future growth, it offers a scope for future research to consider and include other kinds of NBFCs like non-deposit taking NBFCs, housing finance companies, micro-finance Institutions and infrastructure finance companies. Originality/value A competently regulated financial system of an emerging economy confers tremendous growth opportunities to the financial institutions functioning in the system. Deposits are a significant parameter for the performance of the financial institution; thus, by keeping it as the underlying premise, this study forecasts the future growth in deposits for both the commercial banks and NBFCs. This forecasted growth in deposits for both entities, if analyzed and acted upon appropriately, can, apart from other opportunities for investment, be used to point at directional growth of the economy and the gross domestic product, considering that credit growth is a barometer for economic growth. The scope of this study is limited to NBFCs and SCBs of India and considers only a single variable, i.e. deposit for data analysis and growth forecasting.

EARLY STARVATION 1 Is a Functionally Conserved Protein Promoting Gravitropic Responses in Plants by Forming Starch Granules

Starch granules in the endodermis of plant hypocotyls act as statoliths that promote hypocotyl negative gravitropism—the directional growth of hypocotyls against gravity—in the dark. To identify the molecular components that regulate hypocotyl negative gravitropism, we performed a mutagenesis screen and isolated reduced gravitropic 1 (rgv1) mutants that lack starch granules in their hypocotyl endodermis and show reduced hypocotyl negative gravitropism in the dark. Using whole genome sequencing, we identified three different rgv1 mutants that are allelic to the previously reported early starvation 1 mutant, which is rapidly depleted of starch just before the dawn. ESV1 orthologs are present in starch-producing green organisms, suggesting ESV1 is a functionally conserved protein necessary for the formation of starch granules. Consistent with this, we found that liverwort and rice ESV1 can complement the Arabidopsis ESV1 mutant phenotype for both starch granules and hypocotyl negative gravitropism. To further investigate the function of ESV1 in other plants, we isolated rice ESV1 mutants and found that they show reduced levels of starch in their leaves and loosely packed starch granules in their grains. Both Arabidopsis and rice ESV1 mutants also lack starch granules in root columella and show reduced root gravitropism. Together, these results indicate ESV1 is a functionally conserved protein that promotes gravitropic responses in plants via its role in starch granule formation.

Tailored growth of single-crystalline InP tetrapods

Despite the technological importance of colloidal covalent III-V nanocrystals with unique optoelectronic properties, their synthetic process still has challenges originating from the complex energy landscape of the reaction. Here, we present InP tetrapod nanocrystals as a crystalline late intermediate in the synthetic pathway that warrants controlled growth. We isolate tetrapod intermediate species with well-defined surfaces of (110) and ($$\bar{1}\bar{1}\bar{1}$$ 1 ¯ 1 ¯ 1 ¯ ) via the suppression of further growth. An additional precursor supply at low temperature induces $$[\bar{1}\bar{1}\bar{1}]$$ [ 1 ¯ 1 ¯ 1 ¯ ] -specific growth, whereas the [110]-directional growth occurs over the activation barrier of 65.7 kJ/mol at a higher temperature, thus finalizes into the (111)-faceted tetrahedron nanocrystals. We address the use of late intermediates with well-defined facets at the sub-10 nm scale for the tailored growth of covalent III-V nanocrystals and highlight the potential for the directed approach of nanocrystal synthesis.

A minus-end directed kinesin motor directs gravitropism in Physcomitrella patens

Gravity is a critical environmental factor regulating directional growth and morphogenesis in plants, and gravitropism is the process by which plants perceive and respond to the gravity vector. The cytoskeleton is proposed to play important roles in gravitropism, but the underlying mechanisms are obscure. Here we use genetic screening in Physcomitrella patens, to identify a locus GTRC, that when mutated, reverses the direction of protonemal gravitropism. GTRC encodes a processive minus-end-directed KCHb kinesin, and its N-terminal, C-terminal and motor domains are all essential for transducing the gravity signal. Chimeric analysis between GTRC/KCHb and KCHa reveal a unique role for the N-terminus of GTRC in gravitropism. Further study shows that gravity-triggered normal asymmetric distribution of actin filaments in the tip of protonema is dependent on GTRC. Thus, our work identifies a microtubule-based cellular motor that determines the direction of plant gravitropism via mediating the asymmetric distribution of actin filaments.