Temperature responses of three Fibrocapsa japonica strains (Raphidophyceae) from different climate regions

The harmful bloom alga Fibrocapsa japonica has a worldwide distributionin temperate regions and is occasionally responsible for massmortality of fish. Little is known about requirements for optimalgrowth and survival of this species, especially about temperatureconstraints that define natural distribution. Therefore, westudied thermal traits in three Fibrocapsa strains from differentclimate regions. All strains were eurythermal and viable between4 and 32°C, explaining their presence in temperate regions.Some differences in temperature response among the strains wereobserved, not only for growth rate but also for biovolume andnet production. The implication of the observed responses wasevaluated by translating growth performance of strains in thelaboratory to potential performance in the natural habitats.Only the Japanese strain seemed to be well adapted to its environment,while the New Zealand strain exhibited growth and survival overa much broader temperature range, despite the small temperaturefluctuations in its habitat. Interestingly, the German WaddenSea strain encounters lethal temperatures in winter and musthave a resting stage, able to survive temperatures <4°C,to explain its occurrence in this region. However, in general,the responses of the three F. japonica strains in culture werein good agreement with the observed seasonal occurrence in thefield.     

Progress in understanding the biosynthesis of amylose

The storage of glucose in insoluble granules is a distinctive feature of plant cells. Biosynthesis of amylose, the minor low molecular mass fraction of starch occurs from ADP-glucose. This takes place within the polysaccharide matrix through the action of granule-bound starch synthase, the major protein associated with the granule. Recently, amylose has been successfully synthesized in vitro from purified granules. Two models have been proposed to explain the mechanism of amylose synthesis in plants. The first calls for priming of synthesis through small-size malto-oligosaccharides. The second suggests that glucans are extended by granule-bound starch synthase from a high molecular mass primer present within the granule. This extension is terminated through cleavage to produce amylose. This process is subsequently repeated to give several rounds of amylose synthesis.     

Expression of Measles Virus V Protein Is Associated with Pathogenicity and Control of Viral RNA Synthesis

Nonstructural proteins encoded by measles virus (MV) include the V protein which is translated from an edited P mRNA. V protein is not associated with intracellular or released viral particles and has recently been found to be dispensable for MV propagation in cell culture (H. Schneider, K. Kaelin, and M. A. Billeter, Virology 227:314–322, 1997). Using recombinant MVs (strain Edmonston [ED]) genetically engineered to overexpress V protein (ED-V+) or to be deficient for V protein (ED-V−), we found that in the absence of V both MV-specific proteins and RNAs accumulated to levels higher than those in the parental MV molecular clone (ED-tag), whereas MV-specific gene expression was strongly attenuated in human U-87 glioblastomas cells after infection with ED-V+. The titers of virus released from these cells 48 h after infection with either V mutant virus were lower than those from cells infected with ED-tag. Similarly, significantly reduced titers of infectious virus were reisolated from lung tissue of cotton rats (Sigmodon hispidus) after intranasal infection with both editing mutants compared to titers isolated from ED-tag-infected animals. In cell culture, expression of V protein led to a redistribution of MV N protein in doubly transfected Cos-7 cells, indicating that these proteins form heterologous complexes. This interaction was further confirmed by using a two-hybrid approach with both proteins expressed as Gal4 or VP16 fusion products. Moreover, V protein efficiently competed complexes formed between MV N and P proteins. These findings indicate that V protein acts to balance accumulation of viral gene products in cell culture, and this may be dependent on its interaction with MV N protein. Furthermore, expression of V protein may contribute to viral pathogenicity in vivo.     

The distribution of the Hb Constant Spring gene in Southeast Asian populations

Summary The distribution of the hemoglobin Constant Spring (Hb CS) gene in eight populations in Southeast Asia (including Assam) was determined using oligonucleotide hybridization. Hb CS was absent in two Assamese populations with a high prevalence of Hb E. The Hb CS gene frequency was 0.033 in northern Thailand and near 0.01 in central Thailand and Cambodia. High frequencies, between 0.05 and 0.06, were observed in northeastern Thailand. The present data and a similar study in Laotians suggest that the Lao-speaking populations of the Mekong River basin in northeastern Thailand and Laos have the highest frequencies of the Hb CS gene in Southeast Asia.     

Genetic characterization and molecular mapping of Hessian fly resistance genes derived from Aegilops tauschii in synthetic wheat

Two synthetic hexaploid wheat lines (×Aegilotriticum spp., 2n = 6x = 42, genomes AABBDD), SW8 and SW34, developed from the crosses of the durum wheat cultivar Langdon (Triticum turgidum L. var. durum, 2n = 4x = 28, genomes AABB) with two Aegilops tauschii Cosson accessions (2n = 2x = 14, genome DD), were determined to carry Hessian fly [Mayetiola destructor (Say)] resistance genes derived from the Ae. tauschii parents. SW8 was resistant to the Hessian fly biotype Great Plains (GP) and strain vH13 (virulent to H13). SW34 was resistant to biotype GP, but susceptible to strain vH13. Allelism tests indicated that resistance genes in SW8 and SW34 may be allelic to H26 and H13 or correspond to paralogs at both loci, respectively. H26 and H13 were localized to chromosome 4D and 6D, respectively, in previous studies. Molecular mapping in the present study, however, assigned the H26 locus to chromosome 3D rather than 4D. On the other hand, mapping of the resistance gene in SW34 verified the previous assignment of the H13 locus to chromosome 6D. Linkage analysis and physical mapping positioned the H26 locus to the chromosomal deletion bin 3DL3-0.81–1.00. A linkage map for each of these two resistance genes was constructed using simple sequence repeat (SSR) and target region amplification polymorphism (TRAP) markers.     

A Short Sequence Motif in the 5′ Leader of the HIV-1 Genome Modulates Extended RNA Dimer Formation and Virus Replication

The 5′ leader of the HIV-1 RNA genome encodes signals that control various steps in the replication cycle, including the dimerization initiation signal (DIS) that triggers RNA dimerization. The DIS folds a hairpin structure with a palindromic sequence in the loop that allows RNA dimerization via intermolecular kissing loop (KL) base pairing. The KL dimer can be stabilized by including the DIS stem nucleotides in the intermolecular base pairing, forming an extended dimer (ED). The role of the ED RNA dimer in HIV-1 replication has hardly been addressed because of technical challenges. We analyzed a set of leader mutants with a stabilized DIS hairpin for in vitro RNA dimerization and virus replication in T cells. In agreement with previous observations, DIS hairpin stability modulated KL and ED dimerization. An unexpected previous finding was that mutation of three nucleotides immediately upstream of the DIS hairpin significantly reduced in vitro ED formation. In this study, we tested such mutants in vivo for the importance of the ED in HIV-1 biology. Mutants with a stabilized DIS hairpin replicated less efficiently than WT HIV-1. This defect was most severe when the upstream sequence motif was altered. Virus evolution experiments with the defective mutants yielded fast replicating HIV-1 variants with second site mutations that (partially) restored the WT hairpin stability. Characterization of the mutant and revertant RNA molecules and the corresponding viruses confirmed the correlation between in vitro ED RNA dimer formation and efficient virus replication, thus indicating that the ED structure is important for HIV-1 replication.     

VARIATION IN CHROMATOGRAPHIC PATTERNS IN THE TRAGOPOGON DUBIUS-PRATENSIS-PORRIFOLIUS COMPLEX (COMPOSITAE)

Natural populations of the diploid species, Tragopogon dubius, T. pratensis and T. porrifolius, the F₁ hybrids of these species, and the two amphidiploids, T. mirus and T. miscellus, were obtained from the same localities used for previous morphological and cytological studies of the evolutionary relationships of this complex. Inter- and intra-populational comparisons were made utilizing 2-dimensional chromatograms of these taxa. Members of the complex shared a group of 18 flavonoid-type pattern components, no one of which was completely species specific. Therefore, species patterns were expressed for a population rather than an individual with pattern components being expressed as a frequency. Patterns for F₁ hybrids and amphidiploids, expressed in the same manner, were relatable to the parental species. Diploid species and F₁ hybrid patterns were the most variable in areas of greatest sympatry, indicating considerable genetic interchange between species. The distribution of specific components in certain populations was interpreted as chemical introgression. Evidence was presented for separate origins of T. mirus in two localities. The results confirm previous interpretations of the evolutionary relationships in this complex, and when compared to those obtained for Baptisia, they implicate the different breeding systems as important factors in establishing the kind of variation observed.     

Non-Invasive Separation of Alcoholic and Non-Alcoholic Liver Disease with Predictive Modeling

Background & Objective

Currently, a major clinical challenge is to distinguish between chronic liver disease caused by metabolic syndrome (non-alcoholic fatty liver disease, NAFLD) from that caused by long term or excessive alcohol consumption (ALD). The etiology of severe liver disease affects treatment options and priorities for liver transplantation and organ allocation. Thus we compared physiologically similar NAFLD and ALD patients to detect biochemical differences for improved separation of these mechanistically overlapping etiologies.

Methods

In a cohort of 31 NAFLD patients with BMI below 30 and a cohort of ALD patient with (ALDC n = 51) or without cirrhosis (ALDNC n = 51) serum transaminases, cell death markers and (adipo-)cytokines were assessed. Groups were compared with One-way ANOVA and Tukey''s correction. Predictive models were built by machine learning techniques.

Results

NAFLD, ALDNC or ALDC patients did not differ in demographic parameters. The ratio of alanine aminotransferase/aspartate aminotransferase - common serum parameters for liver damage - was significantly higher in the NAFLD group compared to both ALD groups (each p<0.0001). Adiponectin and tumor necrosis factor(TNF)-alpha were significantly lower in NAFLD than in ALDNC (p<0.05) or ALDC patients (p<0.0001). Significantly higher serum concentrations of cell death markers, hyaluronic acid, adiponectin, and TNF-alpha (each p<0.0001) were found in ALDC compared to ALDNC. Using machine learning techniques we were able to discern NAFLD and ALDNC (up to an AUC of 0.9118±0.0056) or ALDC and ALDNC (up to an AUC of 0.9846±0.0018), respectively.

Conclusions

Machine learning techniques relying on ALT/AST ratio, adipokines and cytokines distinguish NAFLD and ALD. In addition, severity of ALD may be non-invasively diagnosed via serum cytokine concentrations.