Genomic marker assisted identification of genetic loci and genes associated with variation of grain zinc concentration in rice

A study was conducted to examine the genetic divergence and to determine the genetic loci and genes associated with natural variation of grain zinc (Zn) concentration among 28 landraces, improved varieties and advanced breeding lines of rice using candidate gene specific primers. Field evaluation of the experimental material was conducted in randomized block design with three replications and Zn content in unpolished grains of the entries was determined by addition of nitric acid and perchloric acid (1:3) following the procedure ofdiacid digestion method. Statistical analysis revealed the exploitable extent of variability with respect to grain Zn concentration among the entries. Eighteen entries were selected from the two extremes of grain Zn distribution range and subjected to molecular profiling using a panel of 14 candidate genes specific 12 reported and 14 designed primer pairs. Only eight (OsZIP1-1, OsZIP3a, OsZIP4a, OsZIP5-3, OsZIP7-2, OsZIP8b, OsNRAMP7 and OsNAAT1) reported and eight (OsZIP3K, OsZIP4K, OsZIP5K, OsZIP7K, OsNRAMP7K, OsNAAT1K, OsNACK and OsYSL14K) designed primers generated polymorphic amplified products showing sequence length variation due to targeted amplification of candidate genes specific genomic regions. Ample genetic differentiation and divergence were revealed among the entries, which were accommodated into similarity coefficient-based six clusters, remarkably consistent with grain Zn concentrationof the entries. Hierarchical classification pattern of entries was almost completely corroborated by principal co-ordinate analysisbased spatial distribution pattern of their genetic profiles. Molecular analysis based on candidate genes specific primers appeared to be an efficient approach for the elucidation of genetic differentiation and divergence in relation to variation of grain Zn concentration among entries. Hence, these markers can be effectively and efficiently utilized for grain Zn concentration related discrimination of rice genotypes and selection of parental genotypes for grain Zn biofortification. Microsatellites were detected within the candidate genes and amplicons, thereby providing a basis to deduce that the repeat sequence length variation in candidate genes may be a role player in the differential grain Zn accumulation in rice varieties. Single marker analysis established the association of OsNACK, OsZIP1-1, OsNRAMP7 and OsNRAMP7K with grain Zn concentration. Thus, these four markers can be effectively used in marker-assisted selection programme for grainZn biofortification in rice.

The Relationship between Zinc Concentration of Maternal, Umbilical Cord, and Placenta and Birth Weight / 대한지역사회영양학회지

The purpose of this study was to assess the maternal zinc status during pregnancy and to evaluate the relationship between the zinc concentration of maternal, umblical cord blood and placental tissue and pregnancy outcomes. Venous blood samples were drawn from 53 pregnant women just before delivery and the cord blood of their newborn babies was collected immediately after birth. In addition, placental tissues were extracted. We investigated the difference in the concentration of zinc in maternal, umbilical cord blood and placental tissue in two gestational age groups (preterm delivery group [PT] and normal term delivery group [NT]) at 34.7 wk and 39.0 wk of mean gestational age, respectively). We also assessed correlations of the zinc concentration of maternal, umbilical cord blood and placental tissue. Lastly, we studied the correlations between the birth weights and the zinc concentration in the maternal, umbilical cord blood and placental tissue. The concentrations of maternal serum zinc and of umbilical cord serum zinc were significantly higher in the PT group (76.9 +/- 37.4 microgram/dl, 101.3 +/- 41.4 microgram/dl) than in those of the NT group (57.8 +/- 22.4 microgram/dl, 80.7 +/- 27.5 microgram/dl), respectively (p < 0.05). The zinc concentration of the umbilical cord blood was significantly higher than that of the maternal blood in both groups (p < 0.05). There was no significant correlation between the gestational age and the serum zinc concentration in the cord or the maternal serum. Our results showed that there was a negative relationship between the birth weight (r = -0.286) and the maternal serum zinc concentration. Despite there not being a significant difference, there was tendency for the highest concentrations of maternal serum zinc to be associated with the lowest birth weights. These findings support a possible relationship between the maternal zinc status and the pregnancy outcome, and suggest that zinc may play a role in the many biological processes involved in the successful outcome of a pregnancy.

Effect of Hemodialysis on Taste Acuity in Patient with End-Stage Renal Disease / 대한신장학회잡지

In patients with end-stage renal disease, depressed taste acuity may often affect their food intake and causes malnutrition. We measured mean recognition thresholds for the four primary tastes before and after hemodialysis to evaluate the efficacy of hemodialysis on taste acuity and measured serum zinc concentrations to determine the relationship between taste acuity and zinc status in 21 patients undergoing hemodialysis. The results were as follows : 1) Mean taste recognition thresholds of sour(0.0034+/-0.0021 N), sweet(0.027+/-0.012 M), and salty(0.027+/-0.014 M) were significantly higher than those of controls(0.0012+/-0.0007 N, 0.016+/-0.008 M, and 0.015+/-0.008 M, respectively)(P<0.05). 2)After hemodialysis, mean taste recognition thresholds of sour(0.0014+/-0.0011 N), sweet(0.015+/-0.011 M), and salty(0.020+/-0.011 M) were significantly decreased(P<0.05) but were not different from those of controls. 3) The mean recognition threshold for bitter was not improved after hemodialysis and was not different from that of controls. 4) The serum zinc concentration of patients with chronic renal failure was not different from that of controls. Finally, the mean taste recognition thresholds for sour, sweet, and salty were decreased in patients with end-stage renal disease and were improved after hemodialysis. The mean taste recognition threshold for bitter was not improved after hemodialysis and was not different from that of controls.