Live imaging of Arabidopsis shoot primordia via a confocal laser scanning microscope.

Live imaging through confocal laser scanning microscopy enables the recording, analysis, and comparison of the dynamics of shapes and gene expression patterns of plant shoot apical meristems (SAMs) or primordia. Here, we provide a protocol to describe the preparation process of imaging Arabidopsis SAMs and primordia using a confocal microscope. We describe steps for dissection, visualization of meristems using dyes and fluorescent proteins, and gain 3D morphology of meristems. We then detail analysis of shoot meristems using time-lapse imaging. For complete details on the use and execution of this protocol, please refer to Peng et al. (2022).1.

Morphogenesis of leaves: from initiation to the production of diverse shapes.

The manner by which plant organs gain their shape is a longstanding question in developmental biology. Leaves, as typical lateral organs, are initiated from the shoot apical meristem that harbors stem cells. Leaf morphogenesis is accompanied by cell proliferation and specification to form the specific 3D shapes, with flattened lamina being the most common. Here, we briefly review the mechanisms controlling leaf initiation and morphogenesis, from periodic initiation in the shoot apex to the formation of conserved thin-blade and divergent leaf shapes. We introduce both regulatory gene patterning and biomechanical regulation involved in leaf morphogenesis. How phenotype is determined by genotype remains largely unanswered. Together, these new insights into leaf morphogenesis resolve molecular chains of events to better aid our understanding.

Differential growth dynamics control aerial organ geometry.

How gene activities and biomechanics together direct organ shapes is poorly understood. Plant leaf and floral organs develop from highly similar initial structures and share similar gene expression patterns, yet they gain drastically different shapes later-flat and bilateral leaf primordia and radially symmetric floral primordia, respectively. We analyzed cellular growth patterns and gene expression in young leaves and flowers of Arabidopsis thaliana and found significant differences in cell growth rates, which correlate with convergence sites of phytohormone auxin that require polar auxin transport. In leaf primordia, the PRESSED-FLOWER-expressing middle domain grows faster than adjacent adaxial domain and coincides with auxin convergence. In contrast, in floral primordia, the LEAFY-expressing domain shows accelerated growth rates and pronounced auxin convergence. This distinct cell growth dynamics between leaf and flower requires changes in levels of cell-wall pectin de-methyl-esterification and mechanical properties of the cell wall. Data-driven computer model simulations at organ and cellular levels demonstrate that growth differences are central to obtaining distinct organ shape, corroborating in planta observations. Together, our study provides a mechanistic basis for the establishment of early aerial organ symmetries through local modulation of differential growth patterns with auxin and biomechanics.

Influence of hemolysis on serum procalcitonin measured by electrochemiluminescence in an emergency room.

BACKGROUND: To investigate the effect of hemolysis on serum procalcitonin (PCT) detected by electrochemiluminescence (ECL) and to explore the possibility of establishment of a correction equation. METHODS: Fifty-one blood samples from 17 patients were collected. Hemolytic samples, of which the final concentrations of hemoglobin (Hb) were 5, 10, 15 and 20 g L-1, were prepared by adding lysed homologous RBCs to serum, and then the PCT levels were detected and compared. RESULTS: with the increasing degree of sample hemolysis, PCT bias elevated from -13.12% to -38.86% as the hemolysis degree increased from 5 g L-1 to 20 g L-1, respectively. There was a linear correlation of PCT levels between the original and hemolytic samples with the same hemolytic degree (r > 0.97). Using the correction equation log10PCTcorr = 0.962(log10PCThemo) +0.251(log10Hb) - 0.126, the corrected PCT values from the hemolytic samples showed acceptable consistency with the original values (p > 0.05). CONCLUSIONS: Hemolysis has a negative interference on PCT values assayed by ECL. The serum PCT level is correlated negatively with the Hb level in the blood sample. The established correction equation could reduce inappropriate antibiotics application and improve the experience of patients in the emergency department.

[Study on the backward extraction of cellulase in rhamnolipid reverse micelles].

This paper studied the backward extraction of cellulase in RL/isooctane/n-hexanol reverse micelles system. Several key parameters influencing the backward extraction efficiency and activity recovery of cellulase were investigated, including stripping aqueous pH, stripping time, salt type and ionic strength, and addition of alcohols. The experiment results indicated that the optimal parameter values as follows: stripping aqueous pH 7.0, stripping time 30 min, 0.15 mol x L(-1) of KCl, dosage of n-butanol 2%. Under above optimum conditions, the backward extraction efficiency and activity recovery were up to 76.22% and 93.39%, respectively. The backward extraction of cellulase using reverse micelles based on biosurfactant RL performs well. Furthermore, RL has many advantages such as high biodegradability, low critical micelle concentration, etc. The application prospects of RL reverse micelles are extensive.