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Cadmium (Cd) is a toxic heavy metal affecting the normal growth of plants. Nitrate (NO 3 −) and ammonium (NH 4 +) are the primary forms of inorganic nitrogen (N) absorbed by plants. However, the mechanism of N absorption and regulation under Cd stress remains unclear. This study found that: (1) Cd treatment affected the biomass, root length, and Cd2+ flux in Solanum nigrum seedling roots. Specifically, 50 μM Cd significantly inhibited NO 3 − influx while increased NH 4 + influx compared with 0 and 5 μM Cd treatments measured by non-invasive micro-test technology. (2) qRT-PCR analysis showed that 50 μM Cd inhibited the expressions of nitrate transporter genes, SnNRT2;4 and SnNRT2;4-like , increased the expressions of ammonium transporter genes, SnAMT1;2 and SnAMT1;3 , in the roots. (3) Under NH 4 + supply, 50 μM Cd significantly induced the expressions of the aquaporin genes, SnPIP1;5 , SnPIP2;7 , and SnTIP2;1. Our results showed that 50 μM Cd stress promoted NH 4 + absorption by up-regulating the gene expressions of NH 4 + transporter and aquaporins, suggesting that high Cd stress can affect the preference of N nutrition in S. nigrum. [Display omitted] • 50 μM Cd increased Cd2+ influx of S. nigrum seedlings compared with 5 μM Cd. • 50 μM Cd inhibited NO 3 − influx and NH 4 + efflux in root meristem zone. • NH 4 + influx was promoted by 50 μM Cd in root elongation zone compared with 5 μM Cd. • Cd treatment promoted NH 4 + transporter SnAMT1;3 expression in roots. • 50 μM Cd promoted aquaporin SnTIP2;1 expression in roots. [ABSTRACT FROM AUTHOR]

Abstract: To develop the proper renal targeting carrier for clinical therapy, human serum albumin, as starting material, was firstly cleaved into albumin fragments and Superdex 75 and CM-Sepharose FF were used to separate and purify the degradation products. Consequently, three peptide fragments (PFs) with certain sequence named PF-A1–123, PF-A124–298 and PF-A299–585 were obtained as candidates of renal targeting carrier. Then, cytotoxicity and cellular uptake of three PFs was studied preliminarily. The results showed that three PFs had no adverse effects on the HeLa and MDCK cell even up to 5.00mg/mL and PF-A299–585 exhibited highest affinity to MDCK cells. After that, we found that PFs selectively accumulated in the kidneys, especially in the renal tubules after intravenous injection in mice by optical imaging study. Finally, Tissues distribution in vivo was utilized to verify the renal targeting profiles of PFs. Three PFs exhibited renal accumulation characteristics. In particular, about 40% injected doses of PF-A299–585 were specifically distributed into kidneys for 1h. The mean area under the curve (AUC) of PF-A299–585 in kidneys increased 13 times compared with those of PF-A1–123 and PF-A124–298. Therefore, PFs can be applied as prospective carriers for renal targeting and PF-A299–585 may be the optimal carrier. [Copyright &y& Elsevier]