Distinct cellular responses differentiating alcohol- and hepatitis C virus-induced liver cirrhosis

Background

Herpes simplex virus (HSV) can utilize multiple pathways to enter host cells. The factors that determine which route is taken are not clear. Chinese hamster ovary (CHO) cells that express glycoprotein D (gD)-binding receptors are model cells that support a pH-dependent, endocytic entry pathway for all HSV strains tested to date. Fusion-from-without (FFWO) is the induction of target cell fusion by addition of intact virions to cell monolayers in the absence of viral protein expression. The receptor requirements for HSV-induced FFWO are not known. We used the syncytial HSV-1 strain ANG path as a tool to evaluate the complex interplay between receptor usage, membrane fusion, and selection of entry pathway.

Results

Inhibitors of endocytosis and endosome acidification blocked ANG path entry into CHO cells expressing nectin-1 receptors, but not CHO-nectin-2 cells. Thus, under these conditions, nectin-2 mediates pH-independent entry at the plasma membrane. In addition, CHO-nectin-2 cells supported pH-dependent, endocytic entry of different strains of HSV-1, including rid1 and HFEM. The kinetics of ANG path entry was rapid (t_1/2 of 5–10 min) regardless of entry route. However, HSV-1 ANG path entry by fusion with the CHO-nectin-2 cell plasma membrane was more efficient and resulted in larger syncytia. ANG path virions added to the surface of CHO-nectin-2 cells, but not receptor-negative CHO cells or CHO-nectin-1 cells, induced rapid FFWO.

Conclusion

HSV-1 ANG path can enter CHO cells by either endocytic or non-endocytic pathways depending on whether nectin-1 or nectin-2 is present. In addition to these cellular receptors, one or more viral determinants is important for the selection of entry pathway. HSV-induced FFWO depends on the presence of an appropriate gD-receptor in the target membrane. Nectin-1 and nectin-2 target ANG path to divergent cellular pathways, and these receptors may have different roles in triggering viral membrane fusion.     

The role of long chain omega-3 polyunsaturated fatty acids in reducing lipid peroxidation among elderly patients with mild cognitive impairment: a case-control study

The present work explores the effect of dietary omega-3 polyunsaturated fatty acids (PUFAs) intake on lipid peroxidation among mild cognitive impairment (MCI) patients. The plasma lipid hydroperoxide (LPO) levels in 67 MCI patients were compared to those of 134 healthy elderly controls. Omega-3 PUFA intake was assessed using an interviewer-administered food frequency questionnaire. Apolipoprotein E genotyping was performed using polymerase chain reaction and restriction enzyme digestion. The association between various confounders and lipid peroxidation was evaluated using regression analysis. The influence of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) intake on LPO level was investigated. The results revealed that LPO levels were significantly higher in the MCI group than in the control group. Inverse correlations were found between DHA and EPA intake and LPO level among the MCI group. LPO levels decreased significantly with increasing DHA and EPA intake. In summary, the findings revealed that DHA and EPA can play a role in alleviating oxidative stress and reducing the risk of neurodegenerative diseases.     

A quasi-static three-dimensional, mathematical, three-body segment model of the canine knee

A mathematical, three-dimensional, anatomically accurate model of the canine knee was created to determine the forces in the knee ligaments and the knee joint reaction forces during the stance phase of a slow walk. This quasi-static model considered both the tibio-femoral and patello-femoral articulations. The geometric and morphometric data of the hind limb were obtained from cadaver data. Muscle forces acting on the femur and the hip joint reaction force were determined by numerical optimization. Ligaments were modeled as non-linear-springs. Ligament material properties were obtained from the literature pertaining to the human knee. The model consists of-28 non-linear algebraic equations describing equilibrium of the femur and the patella, and geometric constraints. This system of equations was solved by a non-linear least-squares method. Results are presented for a knee with an intact cranial cruciate ligament (CCL) and for a knee with a ruptured CCL. Forces predicted to occur in the CCL by analysis of the model were found to be very similar to reported results of CCL forces measured in vivo in goats.     

3D model of the Escherichia coli multidrug transporter MdfA reveals an essential membrane-embedded positive charge

MdfA is an Escherichia coli multidrug transporter of the major facilitator superfamily (MFS) of secondary transporters. Although several aspects of multidrug recognition by MdfA have been characterized, better understanding the detailed mechanism of its function requires structural information. Previous studies have modeled the 3D structures of MFS proteins, based on the X-ray structure of LacY and GlpT. However, because of poor sequence homology, between LacY, GlpT, and MdfA additional constraints were required for a reliable homology modeling. Using an algorithm that predicts the angular orientation of each transmembrane helix (TM) (kPROT), we obtained a remarkably similar pattern for the 12 TMs of MdfA and those of GlpT and LacY, suggesting that they all have similar helix packing. Consequently, a 3D model was constructed for MdfA by structural alignment with LacY and GlpT, using the kPROT results as an additional constraint. Further refinement and a preliminary evaluation of the model were achieved by correlated mutation analysis and the available experimental data. Surprisingly, in addition to the previously characterized membrane-embedded glutamate at position 26, the model suggests that Asp34 and Arg112 are located within the membrane, on the same face of the cavity as Glu26. Importantly, Arg112 is evolutionarily conserved in secondary drug transporters, and here we show that a positive charge at this position is absolutely essential for multidrug transport by MdfA.     

Mechanisms that control knox gene expression in the Arabidopsis shoot

Knotted1-like homeobox (knox) genes are expressed in specific patterns within shoot meristems and play an important role in meristem maintenance. Misexpression of the knox genes, KNAT1 or KNAT2, in Arabidopsis produces a variety of phenotypes, including lobed leaves and ectopic stipules and meristems in the sinus, the region between lobes. We sought to determine the mechanisms that control knox gene expression in the shoot by examining recessive mutants that share phenotypic characteristics with 35S::KNAT1 plants. Double mutants of serrate (se) with either asymmetric1 (as1) or asymmetric2 (as2) showed lobed leaves, ectopic stipules in the sinuses and defects in the timely elongation of sepals, petals and stamens, similar to 35S::KNAT1 plants. Ectopic stipules and in rare cases, ectopic meristems, were detected in the sinuses on plants that were mutant for pickle and either as1 or as2. KNAT1 and KNAT2 were misexpressed in the leaves and flowers of single as1 and as2 mutants and in the sinuses of leaves of the different double mutants, but not in se or pickle single mutants. These results suggest that AS1 and AS2 promote leaf differentiation through repression of knox expression in leaves, and that SE and PKL globally restrict the competence to respond to genes that promote morphogenesis.     

Two tightly linked QTLs modify tomato sugar content via different physiological pathways

Congenic lines that differ in a single defined chromosome segment are useful for the study of complex phenotypes, as they allow isolation of the effect of a particular quantitative trait locus (QTL) from those of the entire genome. We conducted high-resolution QTL mapping of a 9-cM introgression, originating from the wild tomato species Lycopersicon pennellii, in two extremely different genetic and physiological backgrounds. In the "indeterminate" glasshouse background we identified only a single QTL ( Brix9-2-5) that affects the total soluble solids of the fruit [mainly sugars, measured in Brix units (B)]. This QTL was previously delimited within the gene for an apoplastic invertase, Lin5, that modulates sugar partitioning to the fruit. Analysis of the effects of the same chromosome segment in "determinate", open-field tomatoes, revealed two QTLs, 0.3 cM apart: the fruit-specific Brix9-2-5 that affects B only, and the shoot-specific PW9-2-5, which accounts for an altered growth habit resulting in increases in plant weight, yield, and B. This study highlights the power of the congenic approach for dissecting developmental pathways leading to complex phenotypes.     

High-resolution linkage analysis and physical characterization of the EIX-responding locus in tomato

An ethylene-inducing xylanase (EIX) from Tricohoderma viride is a potent elicitor of ethylene biosynthesis, localized cell death and other defense responses in specific cultivars of tobacco (Nicotiana tabacum) and tomato (Lycopersicon esculentum). Wild species of tomato, such as Lycopersicon cheesmanii and Lycopersicon pennellii, do not respond to EIX treatment. The F₁ progeny of a L. esculentum×L. cheesmanii and a L. esculentum×L. pennellii cross responded to EIX treatment with an increase in ethylene biosynthesis and the induction of localized cell death. The F₂ progeny of the above mentioned crosses segregated 3:1 (responding:non-responding). We mapped the EIX-responding locus (Eix) to the short arm of chromosome 7 using a population of introgression lines (ILs), containing small RFLP-defined chromosome segments of L. pennellii introgressed into L. esculentum. RFLP analysis of 990 F₂ plants that segregated for the introgressed segment mapped the Eix locus 0.1 cM and 0.9 cM from the flanking markers TG61 and TG131, respectively. Using the marker TG61 we isolated a yeast artificial chromosome (YAC) clone that carries 300-kb DNA segments derived from the Eix region. By mapping the ends of this YAC clone we show that it spans the Eix locus. Thus, positional cloning of the Eix locus appears feasible. Received: 20 March 1999 / Accepted: 30 April 1999     

Effects of long-term heat exposure on the auditory nerve-brainstem evoked responses

1. 1.|The purpose of this study was to determine whether chronic latency changes were induced in the auditory nerve-brainstem potentials (ABR) during long-term heat exposure (acclimation).

2. 2.|Latency prolongations of the ABR were observed during acute (5 days) heat exposure. This was followed by a shortening of latencies and amplitude elevation after long-term (2 months) heat exposure (acclimation).

3. 3.|It was concluded that long-term exposure to heat induces chronic changes in nervous activity.

Ultrahigh-Density Linkage Map for Cultivated Cucumber (Cucumis sativus L.) Using a Single-Nucleotide Polymorphism Genotyping Array

Genotyping arrays are tools for high-throughput genotyping, which is beneficial in constructing saturated genetic maps and therefore high-resolution mapping of complex traits. Since the report of the first cucumber genome draft, genetic maps have been constructed mainly based on simple-sequence repeats (SSRs) or on combinations of SSRs and sequence-related amplified polymorphism (SRAP). In this study, we developed the first cucumber genotyping array consisting of 32,864 single-nucleotide polymorphisms (SNPs). These markers cover the cucumber genome with a median interval of ~2 Kb and have expected genotype calls in parents/F₁ hybridizations as a training set. The training set was validated with Fluidigm technology and showed 96% concordance with the genotype calls in the parents/F₁ hybridizations. Application of the genotyping array was illustrated by constructing a 598.7 cM genetic map based on a ‘9930’ × ‘Gy14’ recombinant inbred line (RIL) population comprised of 11,156 SNPs. Marker collinearity between the genetic map and reference genomes of the two parents was estimated at R² = 0.97. We also used the array-derived genetic map to investigate chromosomal rearrangements, regional recombination rate, and specific regions with segregation distortions. Finally, 82% of the linkage-map bins were polymorphic in other cucumber variants, suggesting that the array can be applied for genotyping in other lines. The genotyping array presented here, together with the genotype calls of the parents/F₁ hybridizations as a training set, should be a powerful tool in future studies with high-throughput cucumber genotyping. An ultrahigh-density linkage map constructed by this genotyping array on RIL population may be invaluable for assembly improvement, and for mapping important cucumber QTLs.