Dev110775 3517..3528
نویسندگان
چکیده
Legume root nodules are induced by N-fixing rhizobium bacteria that are hosted in an intracellular manner. These nodules are formed by reprogramming differentiated root cells. The model legumeMedicago truncatula forms indeterminate nodules with a meristem at their apex. This organ grows by the activity of the meristem that adds cells to the different nodule tissues. In Medicago sativa it has been shown that the nodule meristem is derived from the root middle cortex. During nodule initiation, inner cortical cells and pericycle cells are also mitotically activated. However, whether and how these cells contribute to the mature nodule has not been studied. Here, we produce a nodule fate map that precisely describes the origin of the different nodule tissues based on sequential longitudinal sections and on the use of marker genes that allow the distinction of cells originating from different root tissues. We show that nodule meristem originates from the third cortical layer, while several cell layers of the base of the nodule are directly formed from cells of the inner cortical layers, root endodermis and pericycle. The latter two differentiate into the uninfected tissues that are located at the base of the mature nodule, whereas the cells derived from the inner cortical cell layers form about eight cell layers of infected cells. This nodule fate map has then been used to re-analyse several mutant nodule phenotypes. This showed, among other things, that intracellular release of rhizobia in primordium cells and meristem daughter cells are regulated in a
منابع مشابه
The Optical/near-ir Colors of Broad Absorption Line Quasars, including the Candidate Radio-loud Bal Quasar J1556+3517
A candidate radio-loud broad absorption line quasar (RLBAL) has been reported by Becker et al. (1997). We present JHK observations of this object and three other radio-detected BALs taken with the new Michigan-Dartmouth-MIT/Ohio State/Aladdin IR Camera (MOSAIC) on the KPNO 4-meter. The candidate RLBAL J1556+3517 has B?K=6.63, redder than all but one or two known z>1 quasars. This strongly sugge...
متن کاملThe Optical / Near - IR Colors of Broad Absorption Line Quasars , Including the Candidate Radio - Loud BAL Quasar 1556 + 3517
A candidate radio-loud broad absorption line quasar (RLBAL) has been reported by Becker et al. (1997). We present JHK observations of this object and three other radiodetected BALs taken with the new Michigan-Dartmouth-MIT/Ohio State/Aladdin IR Camera (MOSAIC) on the KPNO 4-meter. The candidate RLBAL 1556+3517 has B−K=6.63, redder than all but one or two known z>1 quasars. This strongly suggest...
متن کاملA Lightweight and Extensible AspectJ Implementation
Extending AspectJ to experiment with new language features can be cumbersome, even with an extensible implementation. Often, a language designer only needs a rapid prototyping environment, but has to deal with a full compiler infrastructure, and must address low-level implementation issues. This work completes a lightweight extensible implementation of AspectJ with a declarative assimilation la...
متن کاملUrinary Screening for Detection of Renal Abnormalities in Asymptomatic School Children
BACKGROUND Urinary screening tests for early detection of renal diseases in asymptomatic school children and adolescents are important in the detection of silent renal diseases. OBJECTIVES The purpose of the study was to determine the prevalence of occult renal diseases by dipstick test (reagent strips) in asymptomatic Nepalese children. PATIENTS AND METHODS A total of 2,243 school children...
متن کامل