Subregional Structural Alterations in Hippocampus and Nucleus Accumbens Correlate with the Clinical Impairment in Patients with Alzheimer's Disease Clinical Spectrum: Parallel Combining Volume and Vertex-Based Approach.

Deep gray matter structures are associated with memory and other important functions that are impaired in Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, systematic characterization of the subregional atrophy and deformations in these structures in AD and MCI still need more investigations. In this article, we combined complex volumetry- and vertex-based analysis to investigate the pattern of subregional structural alterations in deep gray matter structures and its association with global clinical scores in AD (n = 30) and MCI patients (n = 30), compared to normal controls (NCs, n = 30). Among all seven pairs of structures, the bilateral hippocampi and nucleus accumbens showed significant atrophy in AD compared with NCs (p < 0.05). But only the subregional atrophy in the dorsal-medial part of the left hippocampus, the ventral part of right hippocampus, and the left nucleus accumbens, the posterior part of the right nucleus accumbens correlated with the worse clinical scores of MMSE and MOCA (p < 0.05). Furthermore, the medial-ventral part of right thalamus significantly shrank and correlated with clinical scores without decreasing in its whole volume (p > 0.05). In conclusion, the atrophy of these four subregions in bilateral hippocampi and nucleus accumbens was associated with cognitive impairment of patients, which might be potential target regions of treatment in AD. The surface analysis could provide additional information to volume comparison in finding the early pathological progress in deep gray matter structures.

Gibberellins and heterosis of plant height in wheat (Triticum aestivum L.).

BACKGROUND: Heterosis in internode elongation and plant height are commonly observed in hybrid plants, and higher GAs contents were found to be correlated with the heterosis in plant height. However, the molecular basis for the increased internode elongation in hybrids is unknown. RESULTS: In this study, heterosis in plant height was determined in two wheat hybrids, and it was found that the increased elongation of the uppermost internode contributed mostly to the heterosis in plant height. Higher GA4 level was also observed in a wheat hybrid. By using the uppermost internode tissues of wheat, we examined expression patterns of genes participating in both GA biosynthesis and GA response pathways between a hybrid and its parental inbreds. Our results indicated that among the 18 genes analyzed, genes encoding enzymes that promote synthesis of bioactive GAs, and genes that act as positive components in the GA response pathways were up-regulated in hybrid, whereas genes encoding enzymes that deactivate bioactive GAs, and genes that act as negative components of GA response pathways were down-regulated in hybrid. Moreover, the putative wheat GA receptor gene TaGID1, and two GA responsive genes participating in internode elongation, GIP and XET, were also up-regulated in hybrid. A model for GA and heterosis in wheat plant height was proposed. CONCLUSION: Our results provided molecular evidences not only for the higher GA levels and more active GA biosynthesis in hybrid, but also for the heterosis in plant height of wheat and possibly other cereal crops.

Wheat Dof transcription factor WPBF interacts with TaQM and activates transcription of an alpha-gliadin gene during wheat seed development.

Wheat prolamin-box binding factor (WPBF), a DOF transcription factor previously was isolated from wheat endosperm and suggested to function as an activator of prolamin gene expression during seed development. In this study, we showed that WPBF is expressed in all wheat tissues analyzed, and a protein, TaQM, was identified from a wheat root cDNA library, to interact with the Dof domain of WPBF. The specific interaction between WPBF and TaQM was confirmed by pull-down assay and bimolecular fluorescence complementation (BiFC) experiment. The expression patterns of TaQM gene are similar with that of WPBF. The GST-WPBF expressed in bacteria binds the Prolamin box (PB) 5'-TGTAAAG-3', derived from the promoter region of a native alpha-gliadin gene encoding a storage protein. Transient expression experiments in co-transfected BY-2 protoplast cells demonstrated that WPBF trans-activated transcription from native alpha-gliadin promoter through binding to the intact PB. When WPBF and TaQM are co-transfected together the transcription activity of alpha-gliadin gene was six-fold higher than when WPBF was transfected alone. Furthermore, the promoter activities of WPBF gene were observed in the seeds and the vascular system of transgenic Arabidopsis, which was identical to the expression profiles of WPBF in wheat. Hence, we proposed that WPBF functions not only during wheat seed development but also during other growth and development processes.

Heterosis in root development and differential gene expression between hybrids and their parental inbreds in wheat (Triticum aestivum L.).

In spite of commercial use of heterosis in agriculture, the molecular basis of heterosis is poorly understood. In this study, heterosis was estimated for eight root traits in 20 wheat hybrids derived from a NC Design II mating scheme. Positive mid-parent heterosis was detected in 96 of 160 hybrid-trait combinations, and positive high-parent heterosis was detected in 79 of 160 hybrid-trait combinations. Improved differential display was used to analyze alterations in gene expression between hybrids and their parents in roots at the jointing stage. More than 990 fragments were repeatedly displayed, among which 27.52% were differentially expressed between hybrids and their parents. Four differential expression patterns were observed. Thirty differentially expressed cDNA fragments and three genes with open reading frames were cloned, and their expression patterns were confirmed by reverse-northern blot and semi-quantitative RT-PCR analysis, respectively. We concluded that these differentially expressed genes, though mostly with unknown function, could play important roles for hybrids to demonstrate heterosis in root system traits.

Characterization and expression of 42 MADS-box genes in wheat (Triticum aestivum L.).

MADS-box genes form a large family of transcription factors and play important roles in flower development and organ differentiation in plants. In this study, 42 wheat cDNAs encoding putative MADS-box genes were isolated. BLASTX searches and phylogenetic analysis indicated that the cDNAs represented 12 of the 14 MADS-box gene subfamilies. TaAGL14 and TaAGL15 formed a new subfamily along with a rice gene OsMADS32. RT-PCR analysis revealed that these genes had different exprsssion patterns in different organs of different stages. Expression patterns of TaAGL1 and TaAGL29 were also determined using in situ hybridization. TaAGL1 was abundantly expressed in primary root tips and the whole spikelet with more intense labeling at lodicules, paleas and stamens. TaAGL29 was expressed in both the non-reproductive parts (lemma, palea and glumes), and stamens and pistils. Moreover, differential expression patterns of these genes were also observed between wheat hybrid and its parents in leaf, stem and root of jointing stage, some were up-regulated while others were down-regulated in hybrid as compared to its parents. We concluded that multiple MADS-box genes exist in wheat genome and are expressed in tissue-specific patterns, and might play important roles in wheat growth and development.

Isolation and characterization of TaDof1 transcription factor in wheat (Triticum. aestivum. L).

The Dof (DNA binding with one finger) proteins are plant specific transcription factors. Dof proteins are apparently encoded by a multiple gene family in higher plants. However, only one Dof gene, WPBF, was reported in wheat. In this study, a member of Dof gene family, TaDof1, was cloned from wheat. TaDof1 encode 291 amino acids, with a predicted molecular mass of 30.348 kDa. At its N-terminal end, a 52 amino acid stretch typical of Dof domain and two serine-rich stretches were observed. Sequence alignment indicated that, in Dof domain, TaDof1 share more than 75% identity with other Dof proteins of different species. TaDof1 was expressed highly in leaves and sheaths, but lowly in roots, and constitutively expressed in developing seeds of 2-12 DAP. It was interesting to note that TaDof1 was differentially expressed between hybrids F1 and parents in root, sheath and leaf. The implication of the differential expression patterns of TaDof1 was discussed in related to the up-regulation of C4 pathway related gene in hybrid rice and heterosis.