Biomedical subjects

Tao Zhao

Publications and source records attributed to Tao Zhao.

9 recordsLinked to original sources

PubMed2025

Subgenomic divergence and functional innovation following whole-genome duplication in Maleae species of Rosaceae.

Whole-genome duplication (WGD) drives plant evolution by inducing karyotype rearrangements and gene loss through subgenome fractionation. In this study, we investigate post-WGD evolutionary dynamics in Rosaceae, focusing on Maleae species, which uniquely experienced an additional WGD. Using phylogenetic and synteny analyses, we reveal that chromosomal breakpoints act as hotspots for localized fractionation, contributing to blurred homoeologous origins and influencing gene retention patterns. Here, we reconstruct karyotype evolution across Rosaceae subfamilies, highlighting chromosome reductions and lineage-specific rearrangements in Dryadoideae, Rosoideae, and Amygdaloideae. We also identify a bias for retaining transcription factors and hormone-related genes from older WGDs in subsequent polyploidy events. Transcriptome analysis classifies WGD-derived genes in Maleae species, such as apple and loquat, into three expression groups, with hormone-enriched genes playing roles in lignification and fruit-related innovations. These findings demonstrate the interplay between chromosomal breakpoints, biased retention, and functional divergence, revealing their contributions to genomic and phenotypic evolution in Maleae and their adaptive success within Rosaceae.

Genome, Plant↗

PubMed2006

Regulation of secretory protein expression in mature cells by DIMM, a basic helix-loop-helix neuroendocrine differentiation factor.

During differentiation, neuroendocrine cells acquire highly amplified capacities to synthesize neuropeptides to overcome dilution of these signals in the general circulation. Once mature, the normal functioning of integrated physiological systems requires that neuroendocrine cells remain plastic to dramatically alter neuropeptide expression for long periods in response to hormonal and electrical cues. The mechanisms underlying the long-term regulation of neuroendocrine systems are poorly understood. Here we show that the Drosophila basic helix-loop-helix protein DIMM, a critical regulator of neuroendocrine cell differentiation, controls secretory capacity in mature neurons. DIMM expression began embryonically but persisted in adults. Through spatial and temporal manipulation of transgene expression in vivo, we defined two phases of prosecretory DIMM activity. During an embryonic critical window, DIMM controlled the differentiation of amplified expression of the neuropeptide leucokinin. At the onset of metamorphosis, levels of DIMM decreased in the insulin-producing cells (IPCs) in parallel with a marked reduction in levels of Drosophila insulin-like peptide 2 and a key neuropeptide biosynthetic enzyme peptidylglycine alpha-monooxygenase (PHM). Overexpression of DIMM in the IPCs prevented the decrease in PHM levels at this stage. In addition, transient overexpression of DIMM in adults produced a dramatic increase in PHM levels in numerous neurons located throughout the brain. These findings provide insights into the mechanisms controlling the maintenance of differentiated cell states, and they suggest an effective means for dynamically adjusting the strength of hormonal signals in diverse homeostatic systems.

Aging↗

PubMed2006

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.

Amino Acid Sequence↗

PubMed2006

Camera calibration from video of a walking human.

A self-calibration method to estimate a camera's intrinsic and extrinsic parameters from vertical line segments of the same height is presented. An algorithm to obtain the needed line segments by detecting the head and feet positions of a walking human in his leg-crossing phases is described. Experimental results show that the method is accurate and robust with respect to various viewing angles and subjects.

Algorithms↗

PubMed2005

Isolation and expression analysis of genes encoding DNA methyltransferase in wheat (Triticum aestivum L.).

DNA methylation of cytosine residues, catalyzed by DNA methyltransferases, is suggested to play important roles in regulating gene expression and plant development. In this study, we isolated four wheat cDNA fragments and one cDNA with open reading frame encoding putative DNA methyltransferase and designated TaMET1, TaMET2a, TaMET2b, TaCMT, TaMET3, respectively. BLASTX searches and phylogenetic analysis suggested that five cDNAs belonged to four classes (Dnmt1, Dnmt2, CMT and Dnmt3) of DNA methyltransferase genes. TaMET2a encoded a protein of 376 aa and contained eight of ten conserved motifs characteristic of DNA methyltransferase. Genomic sequence of TaMET2a was obtained and found to contain ten introns and eleven exons. The expression analysis of the five genes revealed that they were expressed in developing seed, during germination and various vegetative tissues, but in quite different abundance. It was interesting to note that TaMET1 and TaMET3 mRNAs were clearly detected in dry seeds. Moreover, the differential expression patterns of five genes were observed between wheat hybrid and its parents in leaf, stem and root of jointing stage, some were up-regulated while some others were down-regulated in the hybrid. We concluded that multiple wheat DNA methyltransferase genes were present and might play important roles in wheat growth and development.

Amino Acid Sequence↗

PubMed2004

Atomic force microscopy imaging and 3-D reconstructions of serial thin sections of a single cell and its interior structures.

The thin sectioning has been widely applied in electron microscopy (EM), and successfully used for an in situ observation of inner ultrastructure of cells. This powerful technique has recently been extended to the research field of atomic force microscopy (AFM). However, there have been no reports describing AFM imaging of serial thin sections and three-dimensional (3-D) reconstruction of cells and their inner structures. In the present study, we used AFM to scan serial thin sections approximately 60 nm thick of a mouse embryonic stem (ES) cell, and to observe the in situ inner ultrastructure including cell membrane, cytoplasm, mitochondria, nucleus membrane, and linear chromatin. The high-magnification AFM imaging of single mitochondria clearly demonstrated the outer membrane, inner boundary membrane and cristal membrane of mitochondria in the cellular compartment. Importantly, AFM imaging on six serial thin sections of a single mouse ES cell showed that mitochondria underwent sequential changes in the number, morphology and distribution. These nanoscale images allowed us to perform 3-D surface reconstruction of interested interior structures in cells. Based on the serial in situ images, 3-D models of morphological characteristics, numbers and distributions of interior structures of the single ES cells were validated and reconstructed. Our results suggest that the combined AFM and serial-thin-section technique is useful for the nanoscale imaging and 3-D reconstruction of single cells and their inner structures. This technique may facilitate studies of proliferating and differentiating stages of stem cells or somatic cells at a nanoscale.

Animals↗

PubMed2004

MRI features of pigmented villonodular synovitis (PVNS).

The aim of this study was to characterize the magnetic resonance imaging (MRI) features of PVNS. The radiographs and MR images of 23 pathologically proven cases of PVNS were retrospectively reviewed, with emphasis on MR images. There were 9 males and 14 females, mean age 36 years. Of 23 cases, 9 occurred in the hip, 8 in the knee, 3 in the ankle, 2 in the elbow and 1 in the wrist. Typical MRI findings included variable extent of nodular synovial proliferation, from mild proliferation to extensive masses, joint effusion in all cases, and multiple bony erosions in 15. Owing to the tight joint space, bone involvement was frequently seen in the hip, ankle, elbow and wrist. Although the knee joint had a loose capsule, bone involvement was rarely seen. Hemosiderin is a magnetic material, its deposit on proliferative synovial tissue resulting in a spotty low signal or extensive low signal area within the proliferative synovial masses on T(1)- (T1WI) and T(2)-weighted (T2WI) images, best seen on fast field echo (FFE) sequence MRI images. Fat-suppressed sequences obscured the deposit. This is diagnostic of PVNS. The MRI features of PVNS include variable extent of synovial proliferation, joint effusion and erosion of bone, and in particular the deposit of hemosiderin within the synovial masses. The deposit of hemosiderin, appearing as a low signal area best seen on FFE sequence, is diagnostic for PVNS.

Adolescent↗

PubMed2004

PromoLign: a database for upstream region analysis and SNPs.

The study of transcriptional regulation at the genomic level has been hindered by the lack of functional annotation in the putative regulatory regions. Phylogenetic footprinting, in which cross-species sequence alignment among orthologous genes is applied to locate conserved sequence blocks, is an effective strategy to attack this problem. Single nucleotide polymorphisms (SNPs) in transcription factor (TF) binding sites contribute to the heterogeneity of TF binding sites and might disrupt or enhance their regulatory activity. The correlation of SNPs with the TF sites will not only help in functional evaluation of SNPs, but will also help in the study of transcription regulation by focusing attention on specific TF sites. PromoLign (http://polly.wustl.edu/promolign/main.html) is an online database application that presents SNPs and TF binding profiles in the context of human-mouse orthologous sequence alignment with a hyperlinked graphical interface. PromoLign could be applied to a variety of SNPs and transcription related studies, including association genetics, population genetics, and pharmacogenetics.

Animals↗

PubMed2004

Tracking multiple humans in complex situations.

Tracking multiple humans in complex situations is challenging. The difficulties are tackled with appropriate knowledge in the form of various models in our approach. Human motion is decomposed into its global motion and limb motion. In the first part, we show how multiple human objects are segmented and their global motions are tracked in 3D using ellipsoid human shape models. Experiments show that it successfully applies to the cases where a small number of people move together, have occlusion, and cast shadow or reflection. In the second part, we estimate the modes (e.g., walking, running, standing) of the locomotion and 3D body postures by making inference in a prior locomotion model. Camera model and ground plane assumptions provide geometric constraints in both parts. Robust results are shown on some difficult sequences.

Algorithms↗