Wood, bark and stem anatomy of New World species of Gnetum

Quantitative and qualitative data are presented for 11 collections of six species. The wide range of character states for the species is presented in the form of a key to emphasize their potential systematic correlations. Distinctive among these are phcllem characteristics. Fibre-tracheids are newly reported for lianoid Gnetum species. Cells previously thought to be like companion cells in secondary phloem are shown to be uniseriate rays, counterparts to uniseriate xylem rays. Laticifers are abundant in most of the species, and are newly described for secondary tissues of Gnetum. Presence of tyloses in laticifers of two species is apparently a new report for vascular plants. Tori are present in two New World Gnetum species, adding to the report in African species. Perforation plates are simple except near or in primary xylem, where they are simple or foraminate. Torus presence and foraminate perforation plate presence are features more reminiscent of Ephedra and other gymnosperms than of angiosperms. The bark of Gnetum is also very similar to that of Ephedra.     

Cell surface proteins and malignant transformation

Many of the altered properties of malignant cells are thought to involve alterations in cell surface functions. In order to understand these alterations it is necessary to know more about the molecular structure of the surface. Methods for analyzing surface proteins are discussed and their application to normal and transformed tissue culture cells are reviewed. A number of surface proteins are observed to be altered by transformation. Most of the alterations are reductions in amounts of particular species, although a few proteins do increase. Evidence concerning the reasons for these alterations and the possible functions of some of the molecules is reviewed. Working hypotheses arising from these data are presented and prospects for understanding the physiological changes in terms of molecular effects are discussed. Particular emphasis is placed on the idea that surface molecules are associated in specific-non-covalent complexes which are important for their functions.     

Urban indicators for UK butterflies

Most people live in urban environments and there is a need to produce abundance indices to assist policy and management of urban greenspaces and gardens. While regional indices are produced, with the exception of birds, studies of the differences between urban and rural areas are rare. We explore these differences for UK butterflies, with the intention to describe changes that are relevant to people living in urban areas, in order to better connect people with nature in support of conservation, provide a measure relevant to human well-being, and assess the biodiversity status of the urban environment.Transects walked under the UK Butterfly Monitoring Scheme are classified as urban or rural, using a classification for urban morphological zones. We use models from the Generalised Abundance Index family to produce urban and rural indices of relative abundance for UK butterfly species. Composite indices are constructed for various subsets of species. For univoltine and bivoltine species, where we are able to fit phenomenological models, we estimate measures of phenology and identify urban/rural differences. Trends in relative abundance over the period 1995–2014 are more negative in urban areas compared to rural areas for 25 out of 28 species. For the composite indices, all trends are negative, and they are significantly more negative for urban areas than for rural areas. Analysis of phenological parameters shows butterflies tend to emerge earlier in urban than in rural areas. In addition, some fly longer in urban than in rural areas, whereas in other cases the opposite is the case, and hypotheses are proposed to account for these features.Investigating new urban/rural indicators has revealed national declines that are stronger for urban areas. For continued monitoring, there is a need for an urban butterfly indicator, and for this to be evaluated and reported annually. We explain how this may be interpreted, and the relevance for other monitoring schemes. The results of this paper, including the phenological findings, shed new light on the potentially deleterious effects of urbanisation and climate change, which require suitable monitoring and reporting to support policy and management, for example of urban greenspaces and gardens.     

Enthalpies of transfer for proteins from aqueous to water-alcohol solutions: a test for models of residues exposed to solvent

The enthalpies of transfer of proteins from aqueous solution to alcohol–water solutions are used as probes of solvent-accessible surface for these proteins. Enthalpies of transfer to 10 wt% ethanol solutions are determined calorimetrically for the native proteins ribonuclease A, lysozyme, and ovalbumin. Ribonuclease A and lysozyme are reduced and carboxamidomethylated to produce configurations in which interior residues of the native protein are exposed to the solvent; enthalpies of transfer are determined for these species. These data are then compared with enthalpies of transfer for the constituent amino acids of the proteins. The enthalpies of transfer for the residues are used to generate a maximal enthalpy of transfer that can be compared with the enthalpies of transfer for the reduced, carboxamidomethylated proteins. The residue amino acid enthalpies are coupled with probabilities that each residue is an exterior residue to predict an enthalpy of transfer for the native protein that can be compared with the observed enthalpy. The probabilities developed by Wertz and Scheraga and Lee and Richards, and Chothia are then compared on their ability to predict the native enthalpies of transfer for the protein. The Wertz–Scheraga model gives the better fit of this data in all cases.     

Cell culture from sponges: pluripotency and immortality

Sponges are a source of compounds with potential pharmaceutical applications. In this article, methods of sponge cell culture for production of these bioactive compounds are reviewed, and new approaches for overcoming the problem of metabolite supply are examined. The use of embryos is proposed as a new source of sponge material for cell culture. Stem cells are present in high amounts in embryos and are more versatile and resistant to infections than adult cells. Additionally, genetic engineering and cellular research on apoptotic mechanisms are promising new fields that might help to improve cell survival in sponge-cell lines. We propose that one topic for future research should be how to reduce apoptosis, which appears to be very high in sponge cell cultures.     

The application of SIMS to nutrient tracer studies in plant physiology

Current controversies in root physiology relating to the uptake and translocation of mineral nutrients are presented. The opportunities for a SIMS contribution to resolve these controversies are discussed for each of the stable isotope tracers relevant to plant nutrition. It is concluded that for all major nutrients except phosphorus there are promising stable isotope tracers. At the same time, there are challenges to overcome in each case, with respect to background levels, peak interferences and sometimes sensitivity. Techniques of tissue preparation and handling are discussed in some detail, giving attention to the special requirements of plant tissue preparation and analysis for diffusable ions. It is suggested that adapting a preparation and transfer system, designed for production of bulk frozen-hydrated cryofractured specimens, to a secondary ion mass spectrometer would permit easy, rapid preparation. Additionally, this preparation minimizes several serious technical problems inherent to other preparative methods. Difficulties in quantitation are treated briefly, outlining some difficulties specific to plant tissue analysis. Prospects for future applications in plant mineral nutrition are evaluated, taking into account current instrumental developments.     

Conflict and cooperation among the Vikings: Contingent behavioral decisions

We analyze historical accounts of Viking populations in Scotland and Iceland to show that considerations of kinship play a role in individuals' decisions on whether to engage in and revenge murder, as well as in the formation of alliances. However, willingness to murder a relative or to demand vengeance for the murder of another individual depends on the costs and benefits that accrue from the action, as well as the degree of relatedness. When the potential gains from murder are high, individuals are more willing to murder relatives; when the costs of exacting vengeance for a murder are high, individuals are more likely to settle for blood-money compensation for the murder of a family member. Alliances are more likely to be formed with relatives than between unrelated families; moreover, alliances with related individuals are less likely to involve preconditions and are more likely to be stable in the long term.     

Economics and success factors of flexible manufacturing systems: The conventional explanation revisited

This article analyzes costs and relative benefits of several hundred flexible manufacturing systems (FMSs) in the world. The analyses are based on the computerized data bases, which make it easy to correlate different cost and benefit indicators with each other and to look for regular patterns and tendencies in the applications. Both investment cost distributions and the system complexity distributions are analyzed. The relative benefits and advantages and their relationships are shown. Finally, technical and economic explanations for successful implementation strategies are given. The results show that there are two classes of economically successful systems. The small-scale and technically compact systems are usually used in small-batch production for the replacement of semimanual production. The main benefits are increased capacity and productivity as well as quality improvements. The large-scale and technically complex systems are used in large-volume production for the replacement of fixed automation and transfer lines. The benefits are mainly due to the increased potential for flexibility and capital savings.     

Strategies for computer modeling

Modeling is a ubiquitous and often misunderstood enterprise in which data from diverse disciplines are analyzed by techniques from other diverse disciplines in an attempt to confirm or falsify a set of hypotheses about the real world. Guidelines are offered for designing models to match the goals of modeling biological systems. Techniques for the construction and interpretation of models are discussed. The requirements for credibility of models are detailed, and tests are suggested for their validation.     

Biotope prioritisation in the Central Apennines (Italy): species rarity and cross-taxon congruence

The conservation status of invertebrates is usually lesser known than that of vertebrates, and strategies to identify biotopes to preserve invertebrate diversity are typically based on a single surrogate taxon, or even on the use of vertebrates as surrogates. Aim of this research is to illustrate a method for biotope prioritisation that can be easily adapted to different animal groups and geographical contexts. A two-step protocol for biotope prioritisation is proposed on the basis of a multidimensional characterisation of species vulnerability. Firstly, species vulnerability is estimated from rarity measures which include geographical range, abundance and biotope specialisation. Then, these values of vulnerability are used to rank biotopes. The method was applied here to the tenebrionid beetles, the butterflies, the birds and the mammals of the Central Apennines, a montane area of high conservation concern for South Europe. This study provides evidence for the importance of including insects in conservation decisions, because vertebrates are poor surrogates for insects. Conservation efforts in the reserves included in the study area are mostly focused on vertebrates, for which woodlands are considered particularly important. However high altitude open biotopes are crucial for both tenebrionids and butterflies, and preservation of such kind of biotopes would be beneficial also for vertebrates. The approach applied here demonstrates that (1) vertebrates are poor surrogates for insects, and (2) measures of species rarity, typically used in vertebrate conservation, can be obtained also for insects, for which a veritable amount of data are hidden in specialised literature and museum collections.     

Optimal approximate conversions of odds ratios and hazard ratios to risk ratios

Odds ratios approximate risk ratios when the outcome under consideration is rare but can diverge substantially from risk ratios when the outcome is common. In this paper, we derive optimal analytic conversions of odds ratios and hazard ratios to risk ratios that are minimax for the bias ratio when outcome probabilities are specified to fall in any fixed interval. The results for hazard ratios are derived under a proportional hazard assumption for the exposure. For outcome probabilities specified to lie in symmetric intervals centered around 0.5, it is shown that the square-root transformation of the odds ratio is the optimal minimax conversion for the risk ratio. General results for any nonsymmetric interval are given both for odds ratio and for hazard ratio conversions. The results are principally useful when odds ratios or hazard ratios are reported in papers, and the reader does not have access to the data or to information about the overall outcome prevalence.     

Uptake and Metabolism of Iron Oxide Nanoparticles in Brain Cells

Magnetic iron oxide nanoparticles (IONPs) are used for various applications in biomedicine, for example as contrast agents in magnetic resonance imaging, for cell tracking and for anti-tumor treatment. However, IONPs are also known for their toxic effects on cells and tissues which are at least in part caused by iron-mediated radical formation and oxidative stress. The potential toxicity of IONPs is especially important concerning the use of IONPs for neurobiological applications as alterations in brain iron homeostasis are strongly connected with human neurodegenerative diseases. Since IONPs are able to enter the brain, potential adverse consequences of an exposure of brain cells to IONPs have to be considered. This article describes the pathways that allow IONPs to enter the brain and summarizes the current knowledge on the uptake, the metabolism and the toxicity of IONPs for the different types of brain cells in vitro and in vivo.     

A general approach to the concept of varietal ability for synthetic varieties

Summary Genetic effects for varietal value are defined at the level of the population of k-parent synthetic varieties. A simple expression for the total variance among synthetics arises directly from these definitions. A general expression for the covariance among related synthetics is given. Genetic effects are also defined in a completely general way so as to allow for any system of testing and used to derive an expression for the genetic advance in recurrent selection for varietal value. Covariances between relatives evaluated in the system of testing and in varietal combination are introduced, allowing a direct expression of the genetic advance in varietal development when parents are selected either individually or in groups. Some general implications for plant breeding are outlined.Dedicated to Professor F.W. Schnell on the occasion of his 65th birthday     

Differential and integral W-values for ionization in gaseous water under electron and proton irradiation: consistency of inelastic collision cross sections.

Differential and integral W-values for ionization in gaseous water for electron and proton irradiation have been analyzed from the theoretical point of view for consistency between ionization and total inelastic collision cross sections. For low-energy electrons, which are ubiquitous for all primary radiations, the experimental or compiled cross sections from different sources are sometimes not consistent with one another. A practical, self-consistent procedure is outlined in such cases. The high-energy asymptotic W-values for differential and integral ionization are calculated to be 33.7 and 34.7 eV, respectively, for electron irradiation and 34.6 and 32.5 eV, respectively, for proton irradiation. The computed variations of the W-values with energy are generally in good agreement with experiment. Integral primary W-values due only to the interactions between the incident particle and the water vapor are calculated to be 43.5 and 45.0 eV for electrons and protons, respectively, in the high-energy asymptotic limit.     

Preparation of animals for use in the laboratory: issues and challenges for the Institutional Animal Care and Use Committee (IACUC)

Preparation of animals is important for optimization of animal welfare as well as to minimize interanimal variation, thereby strengthening the quality of data for in vivo studies. These issues are important in the work of institutional animal care and use committees (IACUCs), but they pose many challenges as well. This article provides IACUC members with a resource for use in determining whether and how preparation of animals for research affects the IACUC's responsibilities. The topics addressed are intended to serve as a starting point for consideration and discussion. Questions related to subject selection and acclimation of subjects to experimental housing and procedures are emphasized and should provide IACUC members with a framework for discussion of relevant questions. Guidelines are provided for promoting the acclimation of a number of species to experimental settings. Additional, potentially controversial points are also raised, including the effects on longitudinal data sets of changing subject preparation procedures. The roles of the IACUC in the research endeavor are multifaceted and continuously evolving. As empirical data are produced that affect additional aspects of animal care and use, it is important for these committees to be able to evaluate and, when appropriate, stimulate the implementation of improved procedures and strategies.     

Basic strategies for valid cytometry using image analysis

The present review provides a starting point for setting up an image analysis system for quantitative densitometry and absorbance or fluorescence measurements in cell preparations, tissue sections or gels. Guidelines for instrumental settings that are essential for the valid application of image analysis in cytophotometry and cytofluorometry are described. The general principles of the working mechanism of CCD cameras in combination with general methods to improve the behaviour of the cameras are presented. Optimization of illumination of microscopical and macroscopical objects receives special attention because of its importance for valid cytometry. Sources of errors in quantitative measurements are listed and step-by-step charts for tuning the CCD camera, frame grabber and illumination for the optimal use of the systems are described. Suggestions are given for improvement of image arithmetics in difficult imaging situations, such as low fluorescence signals and high absorbance signals. This revised version was published online in November 2006 with corrections to the Cover Date.     

Stability of complex spike timing-dependent plasticity in cerebellar learning

Dynamics of spike-timing dependent synaptic plasticity are analyzed for excitatory and inhibitory synapses onto cerebellar Purkinje cells. The purpose of this study is to place theoretical constraints on candidate synaptic learning rules that determine the changes in synaptic efficacy due to pairing complex spikes with presynaptic spikes in parallel fibers and inhibitory interneurons. Constraints are derived for the timing between complex spikes and presynaptic spikes, constraints that result from the stability of the learning dynamics of the learning rule. Potential instabilities in the parallel fiber synaptic learning rule are found to be stabilized by synaptic plasticity at inhibitory synapses if the inhibitory learning rules are stable, and conditions for stability of inhibitory plasticity are given. Combining excitatory with inhibitory plasticity provides a mechanism for minimizing the overall synaptic input. Stable learning rules are shown to be able to sculpt simple-spike patterns by regulating the excitability of neurons in the inferior olive that give rise to climbing fibers.     

Microsurgery in the clinic and laboratory

Laboratory animals have been crucial to the development of modern microsurgical techniques which are now routinely used in many clinical departments worldwide. In return, microsurgical techniques are important in biomedical research as they allow many surgical procedures to be performed on rodents instead of dogs, pigs or primates. This has obvious advantages in terms of low cost, the use statistically valid numbers for comparison and the availability of genetically defined animals which are more likely to give valid answers to immunological questions. Microsurgical reconstruction is important in plastic, orthopaedic, urogenital, vascular and peripheral nerve surgery in man and it is likely that it will become part of every surgeon's training in the near future. In this review, the instrumentation essential to any microsurgical enterprise and the sutures available are described. Basic microsurgical techniques for end-to-end and end-to-side anastomosis of small vessels and for joining peripheral nerves, oviducts and other tubular structures are given in outline. Techniques for transplanting kidney, heart, heart and lung, liver, spleen, pancreas, small bowel, stomach, testicle, ovary and whole joint are only outlined but key references are given. Finally, some of the clinical indications for microsurgical reconstruction are reviewed.     

Epidemiological models for heterogeneous populations: proportionate mixing,parameter estimation,and immunization programs

Deterministic models are presented for epidemics which occur quickly and for long-term endemic diseases where births and deaths must be considered. Contact-rate matrices are formulated in terms of activity levels and subpopulation sizes by using a proportionate-mixing assumption. Methods are presented for estimating epidemic and endemic parameters in both homogeneous and heterogeneous populations. Other authors' approaches to contact-rate matrices and spatial heterogeneity are described. Three immunization programs are analyzed for a model of a spatially heterogeneous population and are compared in a “city and villages” example.     

A new method of salt pan formation in intertidal marshes

Summary

Records of fungi occurring in the Hebrides are extended, particularly for Jura and Islay where, respectively, 40 and 47 taxa are recorded for the first time. Twenty taxa are added to the list for Rhum and 89 to that for Colonsay. Additional fungi are also reported for Hirta (St. Kilda) , Bernary, Mingulay, Barra and South Uist in the Outer Hebrides, and Eigg and Canna in the Inner Hebrides.