Peptides in the Hydrozoa: are they transmitters?

A family of peptides with the carboxy-terminus Arg-Phe-amide has been localized to specific subpopulations of neurons in every cnidarian species examined. These neurons are typically sensory in character or are associated with smooth muscle. Although a transmitter role for these peptides has been suggested for anthozoans at neuromuscular synapses, no such evidence is available for hydrozoans. Instead there is evidence that RF-amides can be modulators of neuronal activity which takes the form of a biphasic (inhibitory then excitatory) response in vivo, while in vitro only the inhibitory response is seen. Voltage clamp studies of identified motor neurons showed large, transitory outward currents when Pol-RF-amide peptide was applied.     

How well are protein structures annotated in secondary databases?

We investigated to what extent Protein Data Bank (PDB) entries are annotated with second-party information based on existing cross-references between PDB and 15 other databases. We report 2 interesting findings. First, there is a clear "annotation gap" for structures less than 7 years old for secondary databases that are manually curated. Second, the examined databases overlap with each other quite well, dividing the PDB into 2 well-annotated thirds and one poorly annotated third. Both observations should be taken into account in any study depending on the selection of protein structures by their annotation.     

Protected areas for kiwi in mainland forests of New Zealand: how large should they be?

This paper examines, theoretically, how dispersal affects the viability of brown kiwi populations in protected areas of different size. Brown kiwi are threatened by introduced mammalian predators in mainland forests and are likely to persist only in managed forests where predators are controlled. In each protected area, the kiwi population will function as a net source, with an outflow of juveniles into the adjoining forest and minimal backflow into the reserve. Computer simulations show the minimum area of forest required for population viability increases non-linearly as the mean dispersal distance of juveniles increases. Preliminary measurements of the mean dispersal distance of brown kiwi in the wild suggest kiwi populations are unlikely to be viable in protected areas of less than 10 000 ha. Our estimate of the forest area requirement for viable populations of brown kiwi agrees with those derived by earlier workers using biogeographic techniques.     

Cancer and diet: How are they related?

Extensive research in the past decade has revealed cancer to be a multigenic disease caused by perturbation of multiple cell signalling pathways and dysregulation of numerous gene products, all of which have been linked to inflammation. It is also becoming evident that various lifestyle factors, such as tobacco and alcohol use, diet, environmental pollution, radiation and infections, can cause chronic inflammation and lead to tumourigenesis. Chronic diseases caused by ongoing inflammation therefore require chronic, not acute, treatment. Nutraceuticals, compounds derived from fruits, vegetables, spices and cereals, can be used chronically. This study discusses the molecular targets of some nutraceuticals that happen to be markers of chronic inflammation and how they can prevent or treat cancer. These naturally-occurring agents in the diet have great potential as anti-cancer drugs, thus proving Hippocrates, who proclaimed 25 centuries ago, 'Let food be thy medicine and medicine be thy food'.     

How well are biodiversity drivers reflected in protected areas? A representativeness assessment of the geohistorical gradients that shaped endemic flora in Japan

Protected areas function as a lifeboat that can preserve the origins and maintenance of biodiversity. We assessed the representativeness of biodiversity in existing protected areas in Japan using a distribution dataset and phylogenetic tree for 5565 Japanese vascular plant species. We first examined the overlap of species distribution with the existing protected areas and identified the minimum set representing all plant species. Second, we evaluated the relative importance of environmental variables in explaining the spatial arrangement of protected areas using a random forest model. Finally, we clarified how potential drivers of plant diversity were sufficiently captured within the protected areas network. Although the protected areas captured the majority of species, nearly half of the minimum set areas were selected from outside the existing protected areas. The locations of existing protected areas are mainly associated with geographical and socio-economic factors rather than key biodiversity features (including evolutionary distinctiveness). Moreover, critical biodiversity drivers, which include current climate, paleoclimatic stability, and geographical isolation, were biasedly emulated within the existing protected areas. These findings demonstrate that current conservation planning fails to represent the ecological and evolutionary processes relevant to species sorting, dispersal limitation, and allopatric speciation. In particular, under-representativeness of historically stable habitats that function as evolutionary hotspots or refugia in response to climate changes may pose a threat to the long-term persistence of Japan’s endemic biota. This study provides a fundamental basis for developing prioritization measures to retain species assembly processes and in situ diversification along current climatic and geohistorical gradients.     

Montane speciation patterns in Ithomiola butterflies (Lepidoptera: Riodinidae): are they consistently moving up in the world?

Tropical lowland areas have often been seen as the centres of terrestrial species proliferation, but recent evidence suggests that young species may be more frequent in montane areas. Several montane speciation modes have been proposed, but their relative frequencies and predominant evolutionary sequence remain unclear because so few biogeographic and phylogenetic studies have tested such questions. I use morphological data to generate a phylogenetic hypothesis for all 11 species of the riodinid butterfly genus Ithomiola (Riodininae: Mesosemiini: Napaeina). These species are shown here to be all strictly geographically and elevationally allo- or parapatrically distributed with respect to their closest relatives in lowland and montane regions throughout the Neotropics. The overwhelming pattern in Ithomiola is of repeated upward parapatric speciation across an elevational gradient, and the genus appears to provide the clearest example to date of vertical montane speciation. All of the young derived species are montane and all of the old basal species are confined to the lowlands, supporting the hypothesis of montane regions largely as 'species pumps' and lowland regions as 'museums'. Possible reasons for the post-speciation maintenance of parapatric ranges in Ithomiola are discussed.     

Ranking of invasive spread through urban green areas in the world’s 100 most populous cities

Urban landscapes are highly fragmented (leading to the extinction of native species) as well as transformed and disturbed (creating novel environments). Such conditions provide non-native species with opportunities to establish and spread through “urban green areas” (UGAs). UGAs can serve as stepping stones for many alien species to recruit and may become sources of propagules to launch invasions in adjoining natural ecosystems. There is great diversity in the spatial structures of UGAs worldwide; these are determined by the city’s level of development, human density, urban planning policy, and history. We explore the invasion risks of, and the potential of invasive spread in, UGAs in the world’s 100 most populous cities (in 40 countries). Based on maps of enhanced vegetation index at 250 m resolution over the extent of 25 by 25 km for each city centre, we simulate the invasion and spread of a reference species (a virtual ruderal invasive species) from the city centre into surrounding urban or rural areas. Doing so allowed us to provide an objective baseline for comparing urban susceptibility to such invasions across diverse cultures, histories and societies. We derive the global ranking of invasive spread potential for each city based on the rate of spread of the reference species, and the ranking of 40 countries, based on the average rate of spread in their cities. We explore correlates of spread rates after 100 time steps (years) by examining the roles of climate (mean annual temperature and rainfall), human demography (city population size and growth rate), and socio-economic indicators [human footprint, human development index and gross domestic product (GDP) per capita]. Small city population size and high GDP per capita are the only significant predictors of high potential for invasive spread. Among the G20 countries, Canada, South Korea, South Africa, France, USA and Brazil all feature in the top-10 countries, and Atlanta, Washington, D.C. and Dallas in the USA, Chittagong in Bangladesh, Toronto in Canada and Brasilia in Brazil are listed among the top 10 cities overall. Our results can serve as a global baseline assessment of invasive spread risks through UGAs, and call for improved protocols for monitoring, planning and management of UGAs.     

Non-ecological speciation, niche conservatism and thermal adaptation: how are they connected?

During the last decade, the ecological theory of adaptive radiation, and its corollary ??ecological speciation??, has been a major research theme in evolutionary biology. Briefly, this theory states that speciation is mainly or largely the result of divergent selection, arising from niche differences between populations or incipient species. Reproductive isolation evolves either as a result of direct selection on mate preferences (e.g. reinforcement), or as a correlated response to divergent selection (??by-product speciation??). Although there are now many tentative examples of ecological speciation, I argue that ecology??s role in speciation might have been overemphasised and that non-ecological and non-adaptive alternatives should be considered more seriously. Specifically, populations and species of many organisms often show strong evidence of niche conservatism, yet are often highly reproductively isolated from each other. This challenges niche-based ecological speciation and reveals partial decoupling between ecology and reproductive isolation. Furthermore, reproductive isolation might often evolve in allopatry before ecological differentiation between taxa or possibly through learning and antagonistic sexual interactions, either in allopatry or sympatry. Here I discuss recent theoretical and empirical work in this area, with some emphasis on odonates (dragonflies and damselflies) and suggest some future avenues of research. A main message from this paper is that the ecology of species differences is not the same as ecological speciation, just like the genetics of species differences does not equate to the genetics of speciation.     

Nuclear grooves. How specific are they?

OBJECTIVE: To study the significance of nuclear grooves in thyroid and extrathyroid benign and malignant lesions. STUDY DESIGN: In this retrospective study, 26 cases were selected randomly, consisting of papillary carcinoma of the thyroid (7), papillary adenocarcinoma (9), normal cervical smear (5) and benign bronchioalveolar lavage (BAL) (5). In all cases hematoxylin and eosin- and Papanicolaou-stained smears were studied for nuclear grooves. RESULTS: Except for one case of papillary adenocarcinoma, nuclear grooves were discernible in all cases. The highest number of nuclear grooves was seen in normal cervical smears, followed by papillary carcinoma of the thyroid, papillary adenocarcinoma and BAL smears. CONCLUSION: The number of grooves did not correlate with either benign or malignant conditions. These findings cast serious doubt about the diagnostic significance of nuclear grooves. Probably nuclear grooves are nonspecific findings and should be considered only in association with other diagnostic features.     

How do visual neurons respond in the real world?

Natural visual stimuli have been reported to evoke neural responses with brief, intense firing events. This has important implications for how visual information is encoded. A recent experiment measured the responses of visual neurons in the natural environment, circumventing many limitations of laboratory simulations while still retaining tight experimental control. Under these conditions, neurons fired intensely at precise, discrete times, validating that this firing regime is relevant to natural vision.     

Halocins: are they involved in the competition between halobacteria in saltern ponds?

Many representatives of the family Halobacteriaceae ("halobacteria") excrete halophilic bacteriocins (halocins) that inhibit the growth of other halobacteria. In spite of the fact that halocin production is widespread among the Halobacteriaceae, no information is available on their ecological significance. To test whether halocins may play a role in the interspecies competition between dif-ferent types of halobacteria in saltern crystallizer ponds inhabited by dense communities of these red halophiles, we assayed for halocins active against a variety of halobacteria in salterns from different locations worldwide. Detection of halocin activity was based on the inhibition of growth of indicator organisms on agar plates, the decreased incorporation of radiolabeled substrates, and microscopic examinations. No halocin activity was detected in any of the brines examined, in spite of the fact that halocin production was demonstrated in cultures of most microorganisms isolated from these brines. Thus, the contribution of halocins in the competition between different halobacteria in hypersaline aquatic environments is probably negligible. Received: July 29, 1999 / Accepted: October 18, 1999     

Mitochondria: are they the seat of senescence?

The frequently quoted figure for the fractional univalent reduction of oxygen to superoxide in mitochondria is certainly too high by at least one order of magnitude. This is so because the higher number (2%) was derived from mitochondria whose cytochrome c oxidase was blocked with cyanide. Nevertheless, even the more correct number (0.1%) means that the production of O(2)(-) and H(2)O(2) in mitochondria is large and apt to result in damage to macromolecules in spite of such defensive enzymes as superoxide dismutases and glutathione peroxidase. The data available for nematodes and flies provide a compelling case for the view that the accumulation of oxidative damage to specific mitochondrial proteins leads to the progressive dysfunction that we see as senescence. The data available from work with mammals are much weaker and do not yet allow a strong position to be taken.