Aluminum distribution and reactive oxygen species accumulation in root tips of two Melaleuca trees differing in aluminum resistance

To elucidate the mechanism of the high aluminum (Al) resistance of a Myrtaceae tree, Melaleuca cajuputi Powell, we investigated the responses of root tips to Al and compared them with those of an Al-sensitive species, M. bracteata F. Muell. Roots of seedlings of both species were treated with a calcium solution (pH 4.0) containing 0 or 1 mM AlCl₃. After 3 h of Al treatment, inhibition of root elongation and deposition of callose and lignin in root tips, typical signs of Al injury, were induced in M. bracteata but not in M. cajuputi, yet Al accumulation in root tips was similar in both species. These results indicate that internal Al tolerance mechanisms, not Al exclusion mechanisms, are responsible for the Al resistance of M. cajuputi. After 3 h of Al treatment, amount of Al tightly bound to root tips, Al remaining after washing with a desorbing solution, was less in M. cajuputi than in M. bracteata. In M. bracteata, 6 h of Al treatment triggered the accumulation of hydrogen peroxide (H₂O₂) in root tips despite the upregulation of antioxidant mechanisms, activity of peroxidase and concentration of reduced glutathione. In M. cajuputi, 6 h of Al treatment did not affect the concentration of H₂O₂, but decreased activity of peroxidase, and increased concentration of reduced glutathione in root tips. These results suggest that the less Al tightly bound to root tips is involved in the suppressing the H₂O₂ accumulation and the internal Al tolerance in M. cajuputi, and that the H₂O₂ accumulation or changes in cellular environment that bring about H₂O₂ accumulation despite the upregulation of antioxidant mechanisms results in Al-induced inhibition of root elongation in M. bracteata.     

Mapping of Calf Death in Japanese Black Cattle

Weak calf syndrome (WCS) is a major cause of calf death in Japanese Black cattle. Among IARS disorders, the isoleucyl-tRNA synthetase c.235G>C mutation has been identified as one of the causes of WCS. However, calf deaths differing from those attributed to IARS disorder has been occurring. To identify other genes potentially responsible for these calf deaths, we constructed three populations of three bulls (Bull-1, -2 and -3) that did not carry the IARS mutation, and dead calves (18, 28, and 31 calves) and healthy cattle (18, 15, and 10 cattle) sired by these bulls. The populations were genotyped using the BovineSNP50 BeadChip, but homozygosity mapping did not detect any associated genomic regions with calf death. Linkage analysis performed using each population as a paternal half-sib family of Bull-1, Bull-2, and Bull-3 revealed that, in the Bull-1 population, calf death was mapped to the 8.94?Mb–14.53?Mb and 29.82?Mb–33.77?Mb regions of BTA29. The findings suggested that the incidence of calf death in calves sired by Bull-1 was a hereditary disease exhibiting a dominant, not recessive, inheritance pattern.     

Molecular and Biochemical Characterization of Three Anthocyanin Synthetic Enzymes from Gentiana triflora

Full length cDNA clones of flavonoid 3',5'-hydroxylase, dihydroflavonol4-reductase and flavonoid 3-glucosyltransferase were clonedfrom petals of Gentiana triflora. Their sequences were homologousto counterparts from other plants. Flavonoid 3',5'-hydroxylaseand flavonoid 3-glucosyltransferase were enzymatically characterizedby expressing cDNAs in heterologous expression systems. (Received May 21, 1996; Accepted June 4, 1996)     

DPP-4 inhibition with linagliptin ameliorates the progression of premature aging in klotho−/− mice

Background

The potential of anti-aging effect of DPP-4 inhibitors is unknown. This study was performed to determine whether linagliptin, a DPP-4 inhibitor, could protect against premature aging in klotho?/? mice.

Methods

Klotho?/? mice exhibit multiple phenotypes resembling human premature aging, including extremely shortened life span, cognitive impairment, hippocampal neurodegeneration, hair loss, muscle atrophy, hypoglycemia, etc. To investigate the effect of linagliptin on these aging-related phenotypes, male klotho?/? mice were divided into two groups: (1) control group fed the standard diet, and (2) linagliptin group fed the standard diet containing linagliptin. Treatment with linagliptin was performed for 4 weeks. The effect of linagliptin on the above mentioned aging-related phenotypes was examined.

Results

Body weight of klotho?/? mice was greater in linagliptin group than in control group (11.1 ± 0.3 vs 9.9 ± 0.3 g; P < 0.01), which was associated with greater gastrocnemius muscle weight (P < 0.01) and greater kidney weight (P < 0.05) in linagliptin group. Thus, linagliptin significantly prevented body weight loss in klotho?/? mice. Survival rate of klotho?/? mice was greater in linagliptin group (93%) compared to control group (67%), although the difference did not reach statistical significance (P = 0.08). None of linagliptin-treated klotho?/? mice had alopecia during the treatment (P < 0.05 vs control klotho?/? mice). Latency of klotho?/? mice in passive avoidance test was larger in linagliptin group than in control group (P < 0.05), indicating the amelioration of cognitive impairment by linagliptin. Cerebral blood flow of klotho?/? mice was larger in linagliptin group than in control group (P < 0.01), being associated with greater cerebral phospho-eNOS levels (P < 0.05) in linagliptin group. Neuronal cell number in hippocampal CA1 region was greater in linagliptin group than in control group (P < 0.05). Linagliptin group had greater cerebral phospho-Akt (P < 0.05) and phospho-CREB (P < 0.05) than control group. Thus, linagliptin ameliorated brain aging in klotho?/? mice. The degree of hypoglycemia in klotho?/? mice was less in linagliptin group than in control group, as estimated by the findings of OGTT.

Conclusions

Out work provided the evidence that DPP-4 inhibition with linagliptin slowed the progression of premature aging in klotho?/? mice, and provided a novel insight into the potential role of DPP-4 in the mechanism of premature aging.

     

Genetic relationships among populations of the Argentine ant Linepithema humile introduced into Japan

Since some colonies of Argentine ant Linepithema humile were discovered in Japan in 1993, populations of this invasive alien ant species have been expanding their distribution. To resolve the number of invasions and the genetic structure in the early stages of introduction, we inferred the genetic structure and relationships among colonies from eight localities, from analyses of eight nuclear microsatellite DNA markers. F _ST analysis, principal component analysis and assignment test showed that at least three highly genetically differentiated groups of Argentine ants are present in Japan. Populations from Hiroshima Bay were grouped together (Hiroshima, Hatsukaichi, Otake, Iwakuni Central and Iwakuni Kuroiso), while those from Kobe and Yanai were both genetically distant from each other and from the Hiroshima Bay group. Hatsukaichi and Kobe are international seaports, suggesting that the by-ship invasion occurred at least twice. The invasion route of the Yanai population is unknown at this moment. The Aichi population was genetically distant from that of the Hiroshima Bay group by the difference in allele frequencies, and it was plausible that the Aichi population was introduced from the Hiroshima Bay group by human-mediated jump dispersal.     

Corticosteroidogenesis in the hypertrophic adrenal gland produced by betamethasone 17, 21-dipropionate in the rat fetus

Betamethasone 17, 21-dipropionate (BMDP), a potent glucocorticoid, produces adrenal hypertrophy in the rat fetus. The present study was performed to investigate the possible alterations of corticosteroidogenesis due to endogeneous substrates or exogenous pregnenolone in the incubation of homogenates of fetal hypertrophic adrenals caused by BMDP given to pregnant rats at day 19 of pregnancy.The corticosteroidal products and those levels per mg homogenate in an incubate of the hypertrophic adrenal homogenate did not differ from those of a normal adrenal. No accumulations of abnormal precursors or intermediates were found in the incubates of the hypertrophic adrenals. It is concluded from these findings that no qualitative alterations in the pathway of corticosteroidogenesis occurred in the hypertrophic adrenal glands caused by BMDP in the rat fetus. When the calculation was done per adrenal gland, the content of corticosterone in the incubate of the homogenate of the hypertrophic adrenal was remarkably higher than that found in a normal gland. This finding was compatible with the significant increase of the plasma corticosterone concentration in the fetuses with the adrenal hypertrophy caused by BMDP.     

Enhancement of Nitrogen Dioxide-Induced Lipid Peroxidation and Dna Strand Breaking by Cysteine and Glutathione

Nitrogen dioxide less than 100 ppm in air induced lipid peroxidation of liposome composed of l-palmitoyl-2-arachidonylphosphatidylcholine as assessed by thiobarbituric acid reactivity. The nitrogen dioxide-induced lipid peroxidation was enhanced by cysteine, glutathione and bovine serum albumin. While the activity of nitrogen dioxide in air to induce single strand breaks of supercoiled plasmid DNA was low, the breaking was remarkably enhanced by cysteine, glutathione and bovine serum albumin. ESR spin trapping using 5,5-dimethyl-1-pyrroline N-oxide showed that certain strong oxidant(s) were generated by interaction of nitrogen dioxide and cysteine. The spin trapping using 3,5-dibromo-4-nitrosobenzene-sulfonate suggested that sulfur-containing radicals were generated by interaction of nitrogen dioxide and cysteine or glutathione. Hence, certain sulfur-containing radicals generated by the interaction which could effectively induce lipid peroxidation and DNA strand breaks.