Laminin A, B1, and B2 Chain Gene Expression in Transected and Regenerating Nerves: Regulation by Axonal Signals

Abstract: Laminin A, B1, and B2 chain mRNA levels in degenerating and regenerating mouse sciatic nerves were examined using northern blot analysis. In normal intact nerves, B1 and B2 mRNA steady-state levels were high, but when the nerves were crushed, the steady-state levels of B1 and B2 mRNA per milligram wet tissue weight of the distal segments of the nerves increased five- to eightfold over that of control levels as the total RNA and β-actin mRNA levels increased, suggesting that these increases were the consequence of Schwann cell proliferation after axotomy. When the steady-state levels of B1 and B2 mRNA were normalized as the ratio to total RNA or β-actin mRNA levels, however, they drastically decreased to about 20% of the normal nerve levels in the nerve segments distal to both the crush and transaction sites 1 day after injury. In the crushed nerves, B1 and B2 mRNA levels gradually increased as the regenerating nerves arrived at the distal segments and reestablished normal axon–Schwann cell contact, and then returned to normal levels on the 21 st day. In the transected nerves, where Schwann cells continued to be disconnected from axons, both B1 and B2 mRNA levels remained low. Cultured Schwann cells expressed detectable levels of B1 and B2 chain mRNA which significantly increased when the cells were cocultured with sensory neurons. However, mRNA for A chain was not detectable in the normal, axotomized nerves or in cultured Schwann cells. These data indicate that Schwann cells express laminin B1 and B2 chain mRNA that are up-regulated by axonal or neuronal contact, but they do not express A chain mRNA.     

Release of the extracellular matrix from conidia ofBlumeria graminis in relation to germination

The release of extracellular matrix (ECM) and the emergence of germ tubes from conidia ofBlumeria graminis were studied by light microscopy and micromanipulation. More prompt and frequent ECM release was confirmed on an artificial hydrophobic substratum than on an artificial hydrophilic substratum. Conidia initially incubated on the hydrophilic substratum were transferred by micromanipulation to either the hydrophobic or the hydrophilic substrata. Immediately after transfer onto the hydrophobic substratum, 75% of conidia released ECM, whereas only 16% did so upon transfer to the hydrophilic substratum. Conidia transferred onto the hydrophobic substratum produced a primary germ tube (PGT) more promptly and frequently than those transferred to the hydrophilic substratum. Thus, conidia recognize and respond to substratum hydrophobicity perhaps immediately after contact. When inoculated onto either isolated barley cuticle or the hydrophobic artificial substratum, 2/3 of the conidia produced a PGT from their polar regions. By contrast, on the hydrophilic substratum 2/3 of conidia did so from the side region. These results show that substratum hydrophobicity affects the location of PGT emergence from conidia. Furthermore, the study indicates that very rapid recognition of surface hydrophobicity by conidia promotes ECM release and this in turn may influence the location of PGT emergence.     

Protein structure prediction assisted with sparse NMR data in CASP13

CASP13 has investigated the impact of sparse NMR data on the accuracy of protein structure prediction. NOESY and ¹⁵N-¹H residual dipolar coupling data, typical of that obtained for ¹⁵N,¹³C-enriched, perdeuterated proteins up to about 40 kDa, were simulated for 11 CASP13 targets ranging in size from 80 to 326 residues. For several targets, two prediction groups generated models that are more accurate than those produced using baseline methods. Real NMR data collected for a de novo designed protein were also provided to predictors, including one data set in which only backbone resonance assignments were available. Some NMR-assisted prediction groups also did very well with these data. CASP13 also assessed whether incorporation of sparse NMR data improves the accuracy of protein structure prediction relative to nonassisted regular methods. In most cases, incorporation of sparse, noisy NMR data results in models with higher accuracy. The best NMR-assisted models were also compared with the best regular predictions of any CASP13 group for the same target. For six of 13 targets, the most accurate model provided by any NMR-assisted prediction group was more accurate than the most accurate model provided by any regular prediction group; however, for the remaining seven targets, one or more regular prediction method provided a more accurate model than even the best NMR-assisted model. These results suggest a novel approach for protein structure determination, in which advanced prediction methods are first used to generate structural models, and sparse NMR data is then used to validate and/or refine these models.     

Large-sliding contact elements accurately predict levels of bone-implant micromotion relevant to osseointegration

Primary stability is recognised as an important determinant in the aseptic loosening failure process of cementless implants. An accurate evaluation of the bone–implant relative micromotion is becoming important both in pre-clinical and clinical studies. If the biological threshold for micro-movements is in the range 100–200 μm then, in order to be discriminative, any method used to evaluate the primary stability should have an accuracy of 10–20 μm or better. Additionally, such method should also be able to report the relative micromotion at each point of the interface. None of the available experimental methods satisfies both requirements. Aim of the present study is to verify if any of the current finite element modelling techniques is sufficiently accurate in predicting the primary stability of a cementless prosthesis to be used to decide whether the micromotion may or may not jeopardise the implant osseointegration. The primary stability of an anatomic cementless stem, as measured in vitro, was used as a benchmark problem to comparatively evaluate different contact modelling techniques. Frictionless contact, frictional contact and press-fitted frictional contact conditions were modelled using alternatively node-to-node, node-to-face and face-to-face contact elements. The model based on face-to-face contact elements accounting for frictional contact and initial press-fit was able to predict the micromotion measured experimentally with an average (RMS) error of 10 μm and a peak error of 14 μm. All the other models presented errors higher than 20 μm assumed in the present study as an accuracy threshold.     

RFLP maps of potato and their alignment with the homoeologous tomato genome

Summary An RFLP linkage map of the potato is presented which comprises 304 loci derived from 230 DNA probes and one morphological marker (tuber skin color). The self-incompatibility locus of potato was mapped to chromosome I, which is homoeologous to tomato chromosome I. By mapping chromosome-specific tomato RFLP markers in potato and, vice versa, potato markers in tomato, the different potato and tomato RFLP maps were aligned to each other and the similarity of the potato and tomato genome was confirmed. The numbers given to the 12 potato chromosomes are now in accordance with the established tomato nomenclature. Comparisons between potato RFLP maps derived from different genetic backgrounds revealed conservation of marker order but differences in chromosome and total map length. In particular, significant reduction of map length was observed in interspecific compared to intraspecific crosses. The distribution of regions with distorted segregation ratios in the genome was analyzed for four potato parents. The most prominent distortion of recombination was found to be caused by the self-incompatibility locus.     

Description, biology and conservation of a new species of Australian tree frog (Amphibia: Anura: Hylidae: Litoria) and an assessment of the remaining populations of Litoria genimaculata Horst, 1883: systematic and conservation implications of an unusual speciation event

The Australian populations of the green-eyed tree frog Litoria genimaculata consist of a northern and southern genetic lineage that meet in a mosaic contact zone comprising two independent areas of contact: one where the main ranges of the lineages overlap, and the second where a population of the southern lineage is isolated within the range of the northern lineage. A recent study failed to find significant reproductive isolation between the main ranges of the two lineages, despite deep genetic divergence, partial postzygotic isolation, and call differences. The study did, however, demonstrate rapid phenotypic divergence and speciation of the isolated population of the southern lineage from both the parapatric northern lineage and from the allopatric, but genetically similar, main range of the southern lineage. Herein, the isolated population of the southern lineage is described as a distinct species, Litoria myola sp. nov. , whereas the remainder of the southern lineage and the northern lineage are retained as a single, paraphyletic species, Litoria genimaculata . Resolving this unusual systematic situation demonstrates the value of using multiple lines of evidence in delimiting species. Litoria myola sp. nov. has a very small distribution and population size and warrants a Critically Endangered listing (B1, 2) under IUCN criteria. Threats and management recommendations are outlined, and the conservation of hybrid zones as areas of evolutionary novelty is discussed.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 549–563.     

Convergent mechanisms favor fast amyloid formation in two lambda 6a Ig light chain mutants

Extracellular deposition as amyloids of immunoglobulin light chains causes light chain amyloidosis. Among the light chain families, lambda 6a is one of the most frequent in light chain amyloidosis patients. Its germline protein, 6aJL2, and point mutants, R24G and P7S, are good models to study fibrillogenesis, because their stability and fibril formation characteristics have been described. Both mutations make the germline protein unstable and speed up its ability to aggregate. To date, there is no molecular mechanism that explains how these differences in amyloidogenesis can arise from a single mutation. To look into the structural and dynamical differences in the native state of these proteins, we carried out molecular dynamics simulations at room temperature. Despite the structural similarity of the germline protein and the mutants, we found differences in their dynamical signatures that explain the mutants’ increased tendency to form amyloids. The contact network alterations caused by the mutations, though different, converge in affecting two anti‐aggregation motifs present in light chain variable domains, suggesting a different starting point for aggregation in lambda chains compared to kappa chains.     

糙皮侧耳(平菇)疏水蛋白的分离纯化及其界面自组装特性研究

从糙皮侧耳Pleurotus ostreatus Pm039菌丝体中分离纯化到一种疏水蛋白并命名为Po.HYD1,SDS-PAGE显示其分子量约15kDa。Po.HYD1具有高度的表面活性,100μg/mL浓度下能够降低水表面张力至25.5mN/m。在1~100μg/mL浓度范围内存在6μg/mL和24μg/mL两个关键浓度,说明了不同浓度范围内自组装条件的改变。水接触角测定证明了Po.HYD1自组装膜的包被能够逆转固体表面的可湿润性。原子力显微镜分析揭示了Po.HYD1在云母表面形成厚度4.2±0.1nm"小杆层";在高定向热裂解石墨表面形成厚度3.2~3.8nm吸附层;在剧烈振荡诱导下的水溶液中形成形状相似、取向一致但体积大小不等的"耳型"颗粒。     

Spatial and Temporal Analysis of Contact Rates in Female White-Tailed Deer

Abstract: White-tailed deer (Odocoileus virginianus) are important game mammals and potential reservoirs of diseases of domestic livestock; thus, diseases of deer are of great concern to wildlife managers. Contact, either direct or indirect, is necessary for disease transmission, but we know little about the ecological contexts that promote intrasexual contact among deer. Using pair-wise direct contacts estimated from Global Positioning System collar locations and joint utilization distributions (JUDs), we assessed habitats in which contacts occur to test whether direct contact rates among female white-tailed deer in different social groups differs among land-cover types. We also tested whether contact rates differed among seasons, lunar phases, and times of day. We obtained locations from 27 female deer for periods of 0.5–17 months during 2002–2006. We designated any simultaneous pair of locations for 2 deer <25 m apart as a direct contact. For each season, we used compositional analysis to compare land-cover types where 2 deer had contact to available land-cover weighted by their JUD. We used mixed-model logistic regression to test for effects of season, lunar phase, and time of day on contact rates. Contact rates during the gestation season were greater than expected from random use in forest and grassland cover, whereas contact rates during the fawning period were greater in agricultural fields than in other land-cover types. Contact rates were greatest during the rut and lowest in summer. Diel patterns of contact rates varied with season, and contact rates were elevated during full moon compared to other lunar periods. Both spatial and temporal analyses suggest that contact between female deer in different social groups occurs mainly during feeding, which highlights the potential impact of food distribution and habitat on contact rates among deer. By using methods to associate contacts and land-cover, we have created beneficial tools for more elaborate and detailed studies of disease transmission. Our methods can offer information necessary to develop spatially realistic models of disease transmission in deer.     

Synthesis and pharmacological evaluation of some dual-acting amino-alcohol ester derivatives of flurbiprofen and 2-[1,1'-biphenyl-4-yl]acetic acid: a potential approach to reduce local gastrointestinal toxicity

The search for safer non-steroidal anti-inflammatory drugs (NSAIDs) continues with the failure of anticipated 'ideal' anti-inflammatory agents, the coxibs, on long-term usage. Increased gastric motility and acidity due to the free carboxy group are involved in the etiology of gastric toxicity, common to conventional NSAIDs. Keeping this fact in mind, it was planned to modify some of the conventional NSAIDs to amino-alcohol ester derivatives, which satisfied the structural requirements for these compounds to possess anticholinergic activity in the intact form. Besides blocking the acidic carboxylic group, incorporation of anticholinergic acivity in these molecules was expected to reduce the gastric toxicity by decreasing gastric acid secretion and motility. Synthesis and pharmacological evaluation of six different N,N-disubstituted amino-ethyl ester derivatives, structurally resembling the amino-alcohol ester class of anticholinergic agents, each for [1,1'-biphenyl]-4-acetic acid (3) and flurbiprofen (10), have been reported as potential substitutes for these NSAIDs, with improved therapeutic profile. All the ester derivatives were found to have sufficient chemical stability in buffers (pH 2.0 and 7.4), ensuring them to be absorbed as intact moieties from the gastrointestinal tract. A significant reduction in ulcerogenic potency in comparison to the parent drugs with a slightly higher anti-inflammatory potency suggests that the majority of these candidates have an improved therapeutic profile over their parent drugs. Hence, a promising novel approach, different from the conventional prodrug concept, has been successfully worked out to overcome the local gastric toxicity, yielding therapeutically better compounds for long-term oral anti-inflammatory therapy.