Our anatomical analysis revealed that a dry maize seed contains four to five embryonic leaves at different developmental stages. Rudimentary kranz structure (KS) is apparent in the first leaf with a substantial density, but its density decreases toward younger leaves. Upon imbibition, leaf expansion occurs rapidly with new KSs initiated from the palisade-like ground meristem cells in the middle of the leaf. In parallel to the anatomical analysis, we obtained the time course transcriptomes for the embryonic leaves in dry and imbibed seeds every 6 h up to hour 72. Over this time course, the embryonic leaves exhibit transcripts of 30,255 genes at a level that can be regarded as "expressed." In dry seeds, ∼25,500 genes are expressed, showing functional enrichment in transcription, RNA processing, protein synthesis, primary metabolic pathways, and calcium transport. During the 72-h time course, ∼13,900 genes, including 590 transcription factor genes, are differentially expressed. Indeed, by 30 h postimbibition, ∼2,200 genes expressed in dry seeds are already down-regulated, and ∼2,000 are upregulated. Moreover, the top 1% expressed genes at 54 h or later are very different from those before 30 h, reflecting important developmental and physiological transitions. Interestingly, clusters of genes involved in hormone metabolism, signaling, and responses are differentially expressed at various time points and TF gene expression is also modular and stage specific. Our dataset provides an opportunity for hypothesizing the timing of regulatory actions, particularly in the context of KS development.plant leaf development | plant hormones | gene expression profiling M aize, a well-studied crop, has been used as a model plant for C4 photosynthesis study, as its leaves possess the kranz structure (KS) for efficient photosynthesis. However, how its leaves develop from seed following imbibition has not been well studied. In particular, it is unclear how KS forms during leaf development. Using the next generation sequencing technology, Li et al. (1) studied the leaf transcriptomes of four regions of 9-dold third maize leaves: the base, the tip, and two middle regions of the leaf, representing different leaf developmental stages, with the base being the youngest. The data revealed a dynamic transcriptome profile, showing different transcripts enriched in different regions and providing a preliminary view of molecular changes during maize leaf development. However, as the leaf base already exhibits distinct KS, it is not early enough to represent the early leaf development when KS begins to form. Indeed, our anatomical study reveals that KS already exists in a rudimentary form in the first two embryonic leaves of maize dry seeds, and the embryonic leaves develop rapidly after seed imbibition (see below). To correlate the transcriptomic dynamics with the KS development during seed germination, we have obtained the time course transcriptomes of embryonic leaves at every 6 h, starting from dry seeds to hour 72 postimbibition. This set o...

Maize is a major crop and a model plant for studying C4 photosynthesis and leaf development. However, a genomewide regulatory network of leaf development is not yet available. This knowledge is useful for developing C3 crops to perform C4 photosynthesis for enhanced yields. Here, using 22 transcriptomes of developing maize leaves from dry seeds to 192 h post imbibition, we studied gene up-and down-regulation and functional transition during leaf development and inferred sets of strongly coexpressed genes. More significantly, we developed a method to predict transcription factor binding sites (TFBSs) and their cognate transcription factors (TFs) using genomic sequence and transcriptomic data. The method requires not only evolutionary conservation of candidate TFBSs and sets of strongly coexpressed genes but also that the genes in a gene set share the same Gene Ontology term so that they are involved in the same biological function. In addition, we developed another method to predict maize TF-TFBS pairs using known TF-TFBS pairs in Arabidopsis or rice. From these efforts, we predicted 1,340 novel TFBSs and 253 new TF-TFBS pairs in the maize genome, far exceeding the 30 TF-TFBS pairs currently known in maize. In most cases studied by both methods, the two methods gave similar predictions. In vitro tests of 12 predicted TF-TFBS interactions showed that our methods perform well. Our study has significantly expanded our knowledge on the regulatory network involved in maize leaf development. maize transcriptomes | coexpressed genes | cis binding site M aize (Zea mays) is a major crop and a model plant for studying C4 photosynthesis and leaf development. However, the regulatory network that controls maize leaf development is still not well understood. In fact, the number of known maize transcription factor (TF)-binding sites (TFBSs) is far smaller than that for Arabidopsis thaliana (1-3).To understand better the regulation of maize leaf development, several recent studies used next-generation sequencing (NGS) technologies to survey transcriptomic differences among maize leaf cell types and developmental stages. The first large-scale study was by Li et al. (7) investigated the transcriptomes of Kranz (i.e., the foliar leaf blade) and non-Kranz (the husk leaf sheath) maize leaves to identify cohorts of genes associated with procambium initiation and vascular patterning. Recently, Wang et al. (8) conducted comparative transcriptomic and metabolomic analyses of developing leaves in maize and rice and identified putative structural and regulatory components important for C4 and C3 photosynthesis. These studies provided insights into the regulatory mechanisms underlying the development of Kranz leaf anatomy in maize.In the present study, we obtained nine transcriptomes of the second leaf from 84-192 h post imbibition at 12-h (6:00 AM and 6:00 PM) or 24-h (6:00 PM only) intervals. Together with the 13 SignificanceMaize is a major crop and a model plant for studying C4 leaf development. However, its regulatory network of leaf ...

Frequent occurrence of low antifactor Xa levels observed in this study demonstrated the inadequacy of standard dosing of enoxaparin for VTE prophylaxis in many patients with acute burns. Enoxaparin dose adjustment was associated with a low incidence of VTE events and no bleeding complications.

Low-dose continuous infusion ketamine in mechanically ventilated adult patients was associated with a significant increase in the rate of opioid dose reduction without adverse effects on hemodynamic stability.