Fluctuation of Vegetative Storage Proteins in the Seedlings of Swietenia macrophylla, Analogous to the Seasonal Changes of Those in the Shoot of the Adult Tree

In order to Identify appropriate plant materials for studying the gene expression and biological function of vegetative storage proteins （VSPs） in woody plants, the VSPs in the seedlings of Swietenla rnacrophylla King were investigated by using light microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE） and Western.blotting. The seed of S. macrophylla was rich in storage proteins that accumulated In the vacuoles of cotyledon parenchyma cells in appearance of compact spherical grains. The growth and development of S. macrophylla seedlings were characterized by an obvious growth rhythm. The storage proteins In seeds disappeared during seedling growth while VSPs appeared in the stem 2 weeks after seedling leaves matured. Thereafter, the VSPs In the seedling stem almost exhausted during new shoot growth, and when the leaves of new shoot Just matured, both the stem beneath the new shoot of seedlings and the stem of new shoot started to accumulate VSPs. Nitrogen application dramatically Increased the level of VSPs, but had little influence on the dynamics of VSP consumption and accumulation in seedling stem. Together with these data, the fluctuation of VSPs in seedlings was very similar to that in the branches of the adult trees. In addition, seedlings are easy to be treated due to their small size. Our results suggested that S. rnacrophylla seedlings were suitable for Investigating the biological roles of VSPs and the mechanism of nitrogen storage in trees.

A technique for cardiac resynchronization therapy using left bundle branch area and left ventricular pacing

Cardiac resynchronization therapy(CRT)via biventricu-lar pacing(BVP)is known to improve clinical outcomes and decreases all-cause mortality,particularly in patients with left bundle branch block(LBBB)and reduced left ventricular(LV)function.[1]Recently,several groups have shown the feasibility of left bundle branch area pacing(LBBAP)as an alternative choice to His bundle pacing in patients with LBBB by pacing the left bundle branch(LBB)region beyond the block site with a stable threshold and a short QRS duration(QRSd).[2,3]However,it is unknown whether the clinical efficacy of LBBAP with an appropriate atrioventricular(AV)delay would be the same as or better than that of LV epicardial pacing or CRT.