Plant growth and nitrate uptake were measured for two Great Basin perennial
grasses, Agropyron desertorum and
Pseudoroegneria spicata, in sand-filled pots in either
monoculture or mixed culture (2 plants/pot). All plants were supplied with
the same initial amount of nitrate but delivered in five different pulse
durations ranging from 0.5 to 72 h. The pulse duration was controlled by
flushing the pots with water at different times after applying the nitrate
pulse. The same concentration of nitrate was used in all pulse treatments.
Increasing the pulse duration led to significantly increased plant biomass
production for both species in both mono- and mixed cultures, and to reduced
root/shoot biomass ratio. Biomass and root/shoot ratio were greater
for Agropyron in mixed culture than in monoculture. To
assess root nitrate uptake capacity, a 30-min tracer pulse was applied to all
plants. Plants that had been exposed to longer pulses acquired significantly
more nitrate than those that had been exposed to shorter pulses for both total
plant acquisition and acquisition per unit root length. With greater
root/shoot ratio than Pseudoroegneria, total nitrate
acquisition by Agropyron was significantly greater at
most pulse durations. Root nitrate uptake per unit mass was also greater for
Agropyron than for
Pseudoroegneria, indicating that
Agropyron is more responsive to nitrate pulsing.
Although DNA
5-hydroxymethylcytosine (5hmC)
is recognized as an important epigenetic mark in cancer, its precise role in
lymph node metastasis
remains elusive. In this study, we investigated how 5hmC associates with lymph node metastasis in
breast cancer
. Accompanying with high expression of TET1 and TET2 proteins, large numbers of genes in the metastasis-positive primary tumors exhibit higher 5hmC levels than those in the metastasis-negative primary tumors. In contrast, the TET protein expression and DNA 5hmC decrease significantly within the metastatic lesions in the lymph nodes compared to those in their matched primary tumors. Through genome-wide analysis of 8 sets of primary tumors, we identified 100 high-confidence metastasis-associated 5hmC signatures, and it is found that increased levels of DNA 5hmC and gene expression of
MAP7D1
associate with high risk of lymph node metastasis. Furthermore, we demonstrate that MAP7D1, regulated by TET1, promotes tumor growth and metastasis. In conclusion, the dynamic 5hmC profiles during lymph node metastasis suggest a link between DNA 5hmC and lymph node metastasis. Meanwhile, the role of MAP7D1 in breast cancer progression suggests that the metastasis-associated 5hmC signatures are potential
biomarkers
to predict the risk for lymph node metastasis, which may serve as diagnostic and therapeutic targets for metastatic breast cancer.
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