Rare plants at the extremes of distribution: broadly and narrowly distributed rare species

The flora of North America north of Mexico was used to study rare species at the two extremes of geographic distribution: endemic species, those with large local populations but small geographic ranges, and suffusively rare species, those with small local populations but large geographic ranges. The taxonomic distribution, geographic distribution, and life history characteristics of the two groups were compared. Only 2% of North American species are suffusively rare, while 22.6% of species are endemic to one state or province. Suffusively rare species are significantly more likely to be seedless vascular plants and monocots than expected, and are less likely to be eudicots. Conversely, endemic species are more likely to be eudicots, and less likely to be monocots. Suffusively rare species are most abundant in Canada and the northeastern United States, whereas there are few endemic species in those areas. The highest proportions of endemic species are found in California, Florida, and Texas. Wetland habitats support many suffusively rare species, but few endemic species. Neither are common in alpine habitats. Suffusively rare and endemic species also differ in the dominant growth form. Suffusively rare species are most likely to be herbaceous eudicots, and less likely to be shrubs or shrub-herbs. Endemic species are also likely to be herbaceous, but are also frequently shrubs. A high proportion of endemic species exhibit plasticity in growth form, whereas few suffusively rare species have plastic growth forms. While both groups contain rare species, they differ considerably in geographic distribution and life history traits.     

Are non-functional, unfolded proteins ('junk proteins') common in the genome?

It has recently been shown that many proteins are unfolded in their functional state. In addition, a large number of stretches of protein sequences are predicted to be unfolded. It has been argued that the high frequency of occurrence of these predicted unfolded sequences indicates that the majority of these sequences must also be functional. These sequences tend to be of low complexity. It is well established that certain types of low-complexity sequences are genetically unstable, and are prone to expand in the genome. It is possible, therefore, that in addition to these well-characterised functional unfolded proteins, there are a large number of unfolded proteins that are non-functional. Analogous to 'junk DNA' these protein sequences may arise due to physical characteristics of DNA. Their high frequency may reflect, therefore, the high probability of expansion in the genome. Such 'junk proteins' would not be advantageous, and may be mildly deleterious to the cell.     

Oxygen gradients in small and big sparged insect-cell bioreactors

Conclusions It should be clear from the above that the calculations described here are at best rough estimations yielding order-of-magnitude values. Even though, the following general conclusions can be drawn. The gradients in stagnant layers surrounding the particles which are characteristic for animal-cell bioreactors are relatively small as compared to the gradients which can be expected in the bulk-liquid phases of the three bioreactors considered, in particular to the gradients in the stagnant layer surrounding the air bubbles. It can be concluded that under almost all circumstances gradients are likely to exist and can be very steep in larger vessels and in particular at high cell densities. The effects of gradients, however, are largely unknown; therefore research on the effects of gradients on specific and volumetric productivities and product quality seems to be an interesting area.     

Exploring the temporal consequences of chasing the elements in Rosen's relational diagrams

In the work 'Life Itself', Rosen showed that a formal mechanism cannot be 'closed to efficient cause'. Additionally, he claimed that organisms are 'closed to efficient cause' and that, by logical extension, organisms cannot be mechanisms. This paper shows that it is possible for mechanisms to be 'nearly closed to efficient cause', with the requirement that some unentailed efficient-cause agents are placed inside the system. Populations of these 'nearly closed to efficient cause' systems can be defined based on the ability to isolate each component in its own 'reaction chamber'. Diagrams from these populations are drawn from a couple of different perspectives, and comments are made on how these diagrams can be related to the more conventional language of chemistry.     

The potential for biological control of stoats (Mustela erminea)

Abstract

Accelerating the mortality of stoats (Mustela erminea) using biological agents, or reducing their fertility using chemosterilants or biological agents, are increasingly seen as more sustainable and more humane than trapping and poisoning. Obligate delayed implantation in fertilised female stoats of all ages allows 10–11 months for an applied biological agent or chemosterilant to interfere with gestation. Two chemosterilants (cabergoline and mifepristone) disrupt pregnancy in some species and may be effective on stoats, although they are not species‐specific and are probably more expensive than poisoning. For the longer term, more recent fertility control research has explored potentially more species‐specific options for other species based on inducing an immune response to an animal's own reproductive hormones, gametes, or products from embryos. Conception will be difficult to disrupt in stoats because females are sexually mature and are mated in the nest during a short period before they are weaned. A large research effort will be required to determine which of the immunosterilants being developed could be suitable candidates for stoat control. There are fewer options apparent for using biological agents to increase stoat mortality, although species‐specific strains of canine distemper virus may be effective against stoats.

The greatest impediment to controlling stoat fertility will be effective delivery of sterilants. For the foreseeable future, it will probably be necessary to rely on baits, but they are unlikely to put all target stoats at risk, and will be incapable of delivery over larger scales than at present.

Before undertaking expensive field trials and development of anti‐fertility and biological agents, the effects of putative compensatory changes in demographics that may be associated with changes in stoat density should be modelled to see if the sterilisation and mortality rates that are required to achieve a given level of population control are realistic targets. Also, population control should be defined in terms of accrued benefit for wildlife by establishing the relationships between stoat densities and the viability of prey populations.

Biological control of fertility or mortality may never be suitable as stand‐alone control options for stoats, particularly when some native fauna survive only if stoats are reduced to very low densities. Biological control may have greater potential when integrated with conventional control.     

Phenotypic variation with respect to fitness: the basis for rank-order selection*

Having argued that phenotypic variation with respect to the component of fitness involved in withstanding density stress is useful for the persistence of populations through time, the sources of such variation are described. Age differences and differences caused by the accidental encounters of dissimilar microenvironments are non-genetic in origin. Genetic bases for phenotypic variation can either be proximate (each individual having a unique genotype) or ultimate. The latter case is one in which the genotypes of individuals are such that the progeny they produce are phenotypically variable. Selection favouring such genotypes can be shown to be Darwinian; group selection is not required. A means for revealing instances of the ultimate genetic control of phenotypic variation is suggested: measures of what should be error variance prove to be larger than those which should, under normal circumstances, include error variance. The last increment of variation that causes what might otherwise be repetitive structures to differ can be ascribed to decisions that are genetically pre-set within developmental programmes.     

Phylogenetic distributions of British birds of conservation concern

Recent studies suggest that species' life histories and ecology can be used to forecast future extinction risk. Threatened species often share similar traits such that if a trait predisposing a species to decline or extinction is evolutionarily conserved, then close relatives of threatened species are themselves likely to be at risk. The phylogenetic distribution of current threat has been argued to provide insight into the species that could be threatened in the future when trait data are not available. Conservation criteria are typically based on multiple indices that capture different symptoms of threat including population trends and range contraction. However, there is no reason to assume consistent phylogenetic distributions of different symptoms. I construct a molecular phylogeny of 249 species of British birds (more than 93% of the breeding and wintering species) and use this to show that the species that are threatened due to population declines are phylogenetically more closely related than expected by chance alone. However, species that are listed for other reasons, including range contraction, are distributed randomly with respect to phylogeny. I suggest that while phylogeny can be informative with respect to identifying clades that are susceptible to some measures of extinction risk, such patterns are likely to be idiosyncratic with respect to symptom and taxa.     

A critique on the preparation and enzymatic characterization of synaptic and nonsynaptic mitochondria from hippocampus

1. In literature two interesting methods are described to obtain from whole pooled brains or areas three types of mitochondria, namely, those of perikaryal origin and those contained in synaptosomes. 2. However, for many types of studies, such "preparative" preparations are not useful; for example, in pharmacological studies only data from a single n number of animals may be of statistical usefulness and may be correctly analyzed by statistical tests. 3. Thus a method is described by which it was possible to characterize by enzyme activities three populations from single rat brain hippocampus. 4. During preparative "analytical" procedure, it was noted that the 10% Ficoll gradients previously used in the literature were unable to separate purified mitochondria-free mitochondria. This gradient should be 12% Ficoll for single areas. 5. In addition, when results are compared using the more appropriate omega 2t for calculations of gravity forces to be applied instead of the maximum or average g for different rotors, enzymatic characterization differed considerably among the various mitochondrial populations. 6. The above considerations are also true when different pestle clearances and/or pestle rotations speeds are used during omogenizations; also lysis conditions are essential. 7. Results showed that selected experimental conditions are to be used when subcellular fractions are to be analyzed biochemically.     

A review about nothing: Are apolar cavities in proteins really empty?

Cavities within proteins that are strictly apolar typically appear to be empty. It has been suggested, however, that water molecules may be present within such cavities but are too disordered to be seen in conventional crystallographic analyses. In contrast, it is argued here that solvent mobility will be limited by the size of the cavity and for this reason high‐occupancy solvent in cavities of typical volume should be readily detectable using X‐ray crystallography. Recent experimental studies of cavity hydration are reviewed. Such studies are consistent with theoretical predictions that it is energetically unfavorable to have a single water molecule in an apolar cavity. As apolar cavities become larger, a point is reached where it is favorable to have the cavity occupied by a cluster of mutually H‐bonded water molecules. The exact size of such a cavity in a protein is yet to be verified.     

Younger genes are less likely to be essential than older genes, and duplicates are less likely to be essential than singletons of the same age

Recently duplicated genes are believed to often overlap in function and expression. A priori, they are thus less likely to be essential. Although this was indeed observed in yeast, mouse singletons and duplicates were reported to be equally often essential. This contradiction can only partly be explained by experimental biases. We herein show that older genes (i.e., genes with earlier phyletic origin) are more likely to be essential, regardless of their duplication status. At a given phyletic gene age, duplicates are always less likely to be essential compared with singletons. The "paradoxical" high essentiality among mouse gene duplicates is then caused by different age profiles of singletons and duplicates, with the latter tending to be derived from older genes.     

小鼠白内障基因突变方式、分布及基因定位

哺乳动物发育相关的功能基因的鉴定多来源于自发或诱发突变的小鼠。小鼠白内障作为较易鉴定的性状,目前业已明确的突变多达140余个。自发突变的小鼠主要来源于大规模饲养,诱发突变主要通过X射线与ENU处理获得,基因敲除与转基因小鼠亦可获得白内障性状。已知的白内障相关基因分布于小鼠20条染色体,其中以1号染色体最多,并常于小鼠胚胎时期起始表达。小鼠白内障表型多由单基因突变引起,突变的确定主要通过F2代家系全基因组扫描、精细定位、单倍型分型与测序验证等程序。本文从小鼠白内障基因突变来源、基因分布、基因定位与基因表达等角度较为全面的阐述了小鼠先天性白内障的研究进展。     

A vivid model of chiral recognition

Hands can be used to demonstrate the three-point model of chiral recognition. The points of attachment are thumb, forefinger, and middle finger. This vivid model has the advantages of simplicity, perspicuity, and availability at any time, although two persons are necessary. It can be shown that two interactions are not sufficient for chiral recognition but that three attractive or two attractive and one repulsive attraction are needed. It can also be used to explain some possibilities of weakening or elusion of the three-point model.     

A new technique for desorbing substances tightly bound to affinity gels: flat-bed electrophoretic desorption in Sephadex via isoelectric focusing (FEDS-IEF)

In some cases, proteins and other molecules which are tightly bound to affinity gels can be recovered under mild conditions by electrophoresis. We have extended this technique by running electrophoretic desorption in flat-beds of Sephadex in the presence of ampholytes (FEDS-IEF). A number of advantages of this technique are noted: due to the geometry of the apparatus, high voltages can be used which result in short running times; there are no physical barriers to the migration of the protein and no abrupt conductivity drops; desorbed samples are easily located and recovered; and relatively large sample loads can be readily accommodated. Running times are very sensitive to the experimental conditions. Affinity gels should be applied as a narrow zone, distant from the anticipated banding position of the desorbed species. A wide ampholyte interval is generally recommended. The system appears to be gentle and flexible enough to allow investigators to optimize the conditions for desorption of various affinity gel systems.     

Assessing the health of sediment ecosystems: use of chemical measurements

1. This paper outlines the use of chemical measurements as surrogate indicators of the health of sediment ecosystems. 2. For chemical measurements to be used for this purpose, links must be able to be made between adverse biological effects and the chemical composition of sediments. 3. Benchmark sediment quality guidelines allow decisions to be made about whether or not a sediment ecosystem is likely to be impacted. These guidelines are established using an effects database and a weight-of-evidence approach that gives ranges of chemical concentrations associated with known adverse biological effects. 4. If guidelines are exceeded the measured values are compared to concentrations of that contaminant in a comparable background or reference sediment. Exceedance of these concentrations leads to site-specific estimates of contaminant bioavailability. If a potential problem is indicated, laboratory sediment bioassays are used to assess the likelihood that the sediment will harm biota. 5. Trace metals are used as an example of a sediment contaminant.     

Representing biodiversity: Data and procedures for identifying priority areas for conservation

Biodiversity priority areas together should represent the biodiversity of the region they are situated in. To achieve this, biodiversity has to be measured, biodiversity goals have to be set and methods for implementing those goals have to be applied. Each of these steps is discussed. Because it is impossible to measure all of biodiversity, biodiversity surrogates have to be used. Examples are taxa sub-sets, species assemblages and environmental domains. Each of these has different strengths and weaknesses, which are described and evaluated. In real-world priority setting, some combination of these is usually employed. While a desirable goal might be to sample all of biodiversity from genotypes to ecosystems, an achievable goal is to represent, at some agreed level, each of the biodiversity features chosen as surrogates. Explicit systematic procedures for implementing such a goal are described. These procedures use complementarity, a measure of the contribution each area in a region makes to the conservation goal, to estimate irreplaceability and flexibility, measures of the extent to which areas can be substituted for one another in order to take competing land uses into account. Persistence and vulnerability, which also play an important role in the priority setting process, are discussed briefly.     

Moving from QTL experimental results to the utilization of QTL in breeding programmes

Results from quantitative trait loci studies cannot be readily implemented into breeding schemes through marker assisted selection because of uncertainty about whether the quantitative trait loci identified are real and whether the identified quantitative trait loci are segregating in the breeding population. The present paper outlines and discusses strategies to reduce uncertainty in the results from quantitative trait loci studies. One strategy to confirm results from quantitative trait loci studies is to combine P -values from many quantitative trait loci experiments, while another is to establish a confirmation study. The power of a confirmation study must be high to ensure that the postulated quantitative trait loci can be verified. In the calculation of the experimental power, there are many issues that have to be addressed: size of the quantitative trait loci to be detected, significance level required, experimental design and expected heterozygosity for the design. To ensure marker assisted selection can be quickly implemented once quantitative trait loci are confirmed, DNA samples should be retained from daughters, and the sires and dams of elite sires.     

The Preoperative Assessment of Multiple Valve Disease

Representative case histories are used to discuss the difficulties in preoperative assessment of patients with multiple valve disease and the dangers of correcting one lesion when two or more valves are seriously damaged. Errors fall into three broad categories: existing second valve disease (1) may not be suspected, (2) may be considered insignificant or (3) may be considered a consequence of the first.Recommendations are offered to minimize these errors. The four valves should be studied physiologically, no matter how “normal” the other three may appear to be clinically, whenever open-heart surgery is contemplated. In bivalvular disease angiographic methods are preferable to pressure studies, for data so obtained are not dependent on cardiac output. Mitral and tricuspid regurgitation can never be attributed with certainty to a more distal lesion but require direct examination at time of operation for assessment.     

牛背梁自然保护区种子植物多样性研究

对牛背梁自然保护区的种子植物多样性进行了研究。据统计,种子植物950种,隶属105科433属,其中,裸子植物4科8属9种,被子植物101科425属941种;木本植物372种,草本植物578种;珍稀濒危保护植物17种,资源植物丰富,分为药用,观赏,食用等10大类型,生态系统多样,按大的类型可划分为森林,灌丛,草甸,裸岩和农田,其中森林面积15055hm^2,占总面积的91.7%。是生态系统的主体。在此基础上,本文还提出了保护植物多样性应采取的对策。     

Of crazy-ants and Curetinae: are Curetis butterflies tended by ants?

The larvae of the lycaenid subfamily Curetinae have never been reported to be associated with ants. Observations on Curetis regula Evans from Brunei are presented which show that this species may be tended by ants both as larvae and adults. The observations are discussed in relation to a recent review on lycaenid/ant associations, u is suggested that the Curetinae will be found to be associated with ants when more species have been reared, on evidence of the larval tentacle organs and apparent 'pore cupolas', both of which are ant adaptations. More studies are needed on Curetis biology and larval morphology to resolve the relationships of this enigmatic genus within the Lycaenidae.     

Recommendations for the routine sampling of diatoms for water quality assessments in Europe

Many methods for using diatoms for routine monitoring of water quality have been developed in Europe and, in some countries, these are being used to enforce environmental legislation. In order to facilitate their wider use, particularly with respect to European Union legislation, steps are being taken to harmonize methodology. In this paper, the principles and practice of sampling are described in relation to the main habitat types encountered in Europe. Although details of methods and sampling programmes have to be tailored to particular circumstances and the overall objectives of the monitoring, a number of generalizations can be made. Where available, rocks and other hard surfaces are the preferred substrates and methods for sampling these are described. If such substrata are not available, then introduced ('artificial') substrata have many applications. Various types of introduced substrata can be used successfully, so long as some basic precautions are described. Other types of substrata such as macrophytes and macroalgae may also be useful under certain circumstances, although there is less consensus in the literature on the most appropriate methods, and of the validity of comparisons between indices computed from epiphytic and epilithic communities. When designing surveys, it is recommended that as far as possible, extremes of non-water quality factors (e.g. shade, current speed, etc) are avoided, unless these are characteristic of the system under investigation. Detailed guidelines for sampling epilithon are described. Along with the recommendations for sampling other substrata, it is hoped that these provide a framework that can be adapted to most river types in Europe. This revised version was published online in June 2006 with corrections to the Cover Date.