The spatiotemporal development of adipose tissue

Adipose tissue is a structure highly specialized in energy storage. The adipocyte is the parenchymal component of adipose tissue and is known to be mesoderm or neuroectoderm in origin; however, adipocyte development remains poorly understood. Here, we investigated the development of adipose tissue by analyzing postnatal epididymal adipose tissue (EAT) in mouse. EAT was found to be generated from non-adipose structure during the first 14 postnatal days. From postnatal day 1 (P1) to P4, EAT is composed of multipotent progenitor cells that lack adipogenic differentiation capacity in vitro, and can be regarded as being in the 'undetermined' state. However, the progenitor cells isolated from P4 EAT obtain their adipogenic differentiation capacity by physical interaction generated by cell-to-matrix and cell-to-cell contact both in vitro and in vivo. In addition, we show that impaired angiogenesis caused by either VEGFA blockade or macrophage depletion in postnatal mice interferes with adipose tissue development. We conclude that appropriate interaction between the cellular and matrix components along with proper angiogenesis are mandatory for the development of adipose tissue.     

Identification of QTLs for seed germination capability after various storage periods using two RIL populations in rice

Seed germination capability of rice is one of the important traits in the production and storage of seeds. Quantitative trait loci (QTL) associated with seed germination capability in various storage periods was identified using two sets of recombinant inbred lines (RILs) which derived from crosses between Milyang 23 and Tong 88-7 (MT-RILs) and between Dasanbyeo and TR22183 (DT-RILs). A total of five and three main additive effects (QTLs) associated with seed germination capability were identified in MT-RILs and DT-RILs, respectively. Among them, six QTLs were identified repeatedly in various seed storage periods designated as qMT-SGC5.1, qMT-SGC7.2, and qMT-SGC9.1 on chromosomes 5, 7, and 9 in MT-RILs, and qDT-SGC2.1, qDT-SGC3.1, and qDT-SGC9.1 on chromosomes 2, 3, and 9 in DT-RILs, respectively. The QTL on chromosome 9 was identified in both RIL populations under all three storage periods, explaining up to 40% of the phenotypic variation. Eight and eighteen pairs additive × additive epistatic effect (epistatic QTL) were identified in MT-RILs and DT-RILs, respectively. In addition, several near isogenic lines (NILs) were developed to confirm six repeatable QTL effects using controlled deterioration test (CDT). The identified QTLs will be further studied to elucidate the mechanisms controlling seed germination capability, which have important implications for long-term seed storage.     

The genetic effect of copy number variations on the risk of type 2 diabetes in a Korean population

Background

Unlike Caucasian populations, genetic factors contributing to the risk of type 2 diabetes mellitus (T2DM) are not well studied in Asian populations. In light of this, and the fact that copy number variation (CNV) is emerging as a new way to understand human genomic variation, the objective of this study was to identify type 2 diabetes–associated CNV in a Korean cohort.

Methodology/Principal Findings

Using the Illumina HumanHap300 BeadChip (317,503 markers), genome-wide genotyping was performed to obtain signal and allelic intensities from 275 patients with type 2 diabetes mellitus (T2DM) and 496 nondiabetic subjects (Total n = 771). To increase the sensitivity of CNV identification, we incorporated multiple factors using PennCNV, a program that is based on the hidden Markov model (HMM). To assess the genetic effect of CNV on T2DM, a multivariate logistic regression model controlling for age and gender was used. We identified a total of 7,478 CNVs (average of 9.7 CNVs per individual) and 2,554 CNV regions (CNVRs; 164 common CNVRs for frequency>1%) in this study. Although we failed to demonstrate robust associations between CNVs and the risk of T2DM, our results revealed a putative association between several CNVRs including chr15:45994758–45999227 (P = 8.6E-04, P^corr = 0.01) and the risk of T2DM. The identified CNVs in this study were validated using overlapping analysis with the Database of Genomic Variants (DGV; 71.7% overlap), and quantitative PCR (qPCR). The identified variations, which encompassed functional genes, were significantly enriched in the cellular part, in the membrane-bound organelle, in the development process, in cell communication, in signal transduction, and in biological regulation.

Conclusion/Significance

We expect that the methods and findings in this study will contribute in particular to genome studies of Asian populations.     

Chikungunya virus neutralization antigens and direct cell-to-cell transmission are revealed by human antibody-escape mutants

Chikungunya virus (CHIKV) is an alphavirus responsible for numerous epidemics throughout Africa and Asia, causing infectious arthritis and reportedly linked with fatal infections in newborns and elderly. Previous studies in animal models indicate that humoral immunity can protect against CHIKV infection, but despite the potential efficacy of B-cell-driven intervention strategies, there are no virus-specific vaccines or therapies currently available. In addition, CHIKV has been reported to elicit long-lasting virus-specific IgM in humans, and to establish long-term persistence in non-human primates, suggesting that the virus might evade immune defenses to establish chronic infections in man. However, the mechanisms of immune evasion potentially employed by CHIKV remain uncharacterized. We previously described two human monoclonal antibodies that potently neutralize CHIKV infection. In the current report, we have characterized CHIKV mutants that escape antibody-dependent neutralization to identify the CHIKV E2 domain B and fusion loop "groove" as the primary determinants of CHIKV interaction with these antibodies. Furthermore, for the first time, we have also demonstrated direct CHIKV cell-to-cell transmission, as a mechanism that involves the E2 domain A and that is associated with viral resistance to antibody-dependent neutralization. Identification of CHIKV sub-domains that are associated with human protective immunity, will pave the way for the development of CHIKV-specific sub-domain vaccination strategies. Moreover, the clear demonstration of CHIKV cell-to-cell transmission and its possible role in the establishment of CHIKV persistence, will also inform the development of future anti-viral interventions. These data shed new light on CHIKV-host interactions that will help to combat human CHIKV infection and inform future studies of CHIKV pathogenesis.     

Isolation and characterization of a reducing polyketide synthase gene from the lichen-forming fungus Usnea longissima

The reducing polyketide synthases found in filamentous fungi are involved in the biosynthesis of many drugs and toxins. Lichens produce bioactive polyketides, but the roles of reducing polyketide synthases in lichens remain to be clearly elucidated. In this study, a reducing polyketide synthase gene (U1PKS3) was isolated and characterized from a cultured mycobiont of Usnea longissima. Complete sequence information regarding U1PKS3 (6,519 bp) was obtained by screening a fosmid genomic library. A U1PKS3 sequence analysis suggested that it contains features of a reducing fungal type I polyketide synthase with β-ketoacyl synthase (KS), acyltransferase (AT), dehydratase (DH), enoyl reductase (ER), ketoacyl reducatse (KR), and acyl carrier protein (ACP) domains. This domain structure was similar to the structure of ccRadsl, which is known to be involved in resorcylic acid lactone biosynthesis in Chaetomium chiversii. The results of phylogenetic analysis located U1PKS3 in the clade of reducing polyketide synthases. RT-PCR analysis results demonstrated that UIPKS3 had six intervening introns and that UIPKS3 expression was upregulated by glucose, sorbitol, inositol, and mannitol.     

Difference of pine ectomycorrhizal biomass in relation to forest conditions

In this study, two plots in a secondary and another two in planted Pinus densiflora stands were exposed to different forest treatments, and the ectomycorrhizal (EM) biomass and its ergosterol content was measured for a year. The unmanaged plot in the secondary stand had greater EM biomass than those in any other plots. Whereas understory cutting had less effect on EM biomass, litter and humus removal decreased pine EM biomass and its ergosterol content, suggesting that such forest treatment alters EM biomass and its structure.     

Analysis of recombinant DNA clones of the endogenous BALB/c murine leukemia virus WN1802N: variation in long terminal repeat length

We analyzed 15 recombinant DNA clones of the unintegrated closed circular DNA intermediate of the BALB/c endogenous ecotropic murine leukemia virus WN1802N. Thirteen of these clones had an insert which corresponded to the complete murine leukemia virus genome. Of these, six contained a single long terminal repeat (LTR) and seven contained two LTRs. The viral genomes in nine clones had an LTR of 520 base pairs (bp), one had an LTR of 570 bp, three had an LTR of 600 bp, and one had an LTR of 670 bp. Restriction endonuclease analysis demonstrated that the size variability resides in the U3 region. Seven of eight clones which yielded infectious virus by DNA transfection had the 520-bp LTR, and the other had a 600-bp LTR. More detailed examination of plasmid subclones of three isolates with different-sized LTRs revealed that the approximate position which varies in the U3 region corresponds to the 72-bp repeat region of Moloney sarcoma virus. Possible consequences of these variations are discussed.     

Reversal of Fv-1 host range by in vitro restriction endonuclease fragment exchange between molecular clones of N-tropic and B-tropic murine leukemia virus genomes.

We molecularly cloned unintegrated viral DNA of the BALB/c endogenous N-tropic and B-tropic murine leukemia retroviruses and in vitro passaged N-tropic Gross (passage A) murine leukemia retroviruses. Recombinant genomes were constructed in vitro by exchanging homologous restriction enzyme fragments from N- or B-tropic parents and subsequent recloning. Infectious virus was recovered after transfection of these recombinant genomes into NIH-3T3 cells and cocultivation with the Fv-1 nonrestrictive SC-1 cells. XC plaque assays of recombinant virus progeny on Fv-ln and Fv-lb cells indicated that the Fv-l host range was determined by sequences located between the BamHI site in the p30 region of the gag gene (1.6 kilobase pairs from the left end of the map) and the HindIII site located in the pol gene (2.9 kilobase pairs from the left end of the map).     

Tau Proteins and Tauopathies in Alzheimer’s Disease

Alzheimer’s disease (AD) is characterized by progressive memory loss and cognitive function deficits. There are two major pathological hallmarks that contribute to the pathogenesis of AD which are the presence of extracellular amyloid plaques composed of amyloid-β (Aβ) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau. Despite extensive research that has been done on Aβ in the last two decades, therapies targeting Aβ were not very fruitful at treating AD as the efficacy of Aβ therapies observed in animal models is not reflected in human clinical trials. Hence, tau-directed therapies have received tremendous attention as the potential treatments for AD. Tauopathies are closely correlated with dementia and immunotherapy has been effective at reducing tau pathology and improving cognitive deficits in animal models. Thus, in this review article, we discussed the pathological mechanism of tau proteins, the key factors contributing to tauopathies, and therapeutic approaches for tauopathies in AD based on the recent progress in tau-based research.