Alternate Junctions and Microheterogeneity of Tlr1, a Developmentally Regulated DNA Rearrangement in Tetrahymena thermophila

ABSTRACT. A large number of developmentally regulated DNA rearrangements occur during the development of the macronucleus in Tetrahymena thermophila , Tlr1 is a deletion element which has large inverted repeats near the rearrangement junctions and deletes more than 13 kbp of internal DNA. Previous analysis of caryonidal lines revealed alternate left junctions for the Tlr1 rearrangement in B strain cells. We show here that C2 strain Tetrahymena also use alternate rearrangement junctions. We have mapped and sequenced two additional rearrangement variants and find that both the left and right can vary over a range of approximately 200 bp. We also demonstrate the presence of sequence microheterogeneity in the most commonly found Tlr1 rearrangement product.     

Leaf and twig anatomy of Eriope, a xeromorphic genus of Labiatae

The leaf and twig anatomy of 25 species of the genus Eriope were studied. The twig anatomy is very uniform apart from the level of formation of early layers of cork. Leaf anatomy shows considerable variation between the species, and this is correlated to some extent with the extreme habit range from trees to woody herbs. Characters of the lamina that show variation are: trichome type and frequency, cuticular markings, leaf dorsiventral or isobilateral, presence of adaxial stomata, presence of a hypodermis, number of layers of adaxial palisade mesophyll cells, occurrence of large bundles of phloem fibres at main veins, type of areolation and marginal venation. Petiole vasculature is simple and generally with either four distinct vascular bundles or two vascular arcs. The most xeromorphic species are usually woody herbs or sub-shrubs, and tend to have thick, isobilateral leaves with large bundles of phloem fibres and few hairs, or strongly dorsiventral leaves with a hypodermis and stomata in deep abaxial hair-lined depressions. The correlation of xeromorphic characters with environmental conditions is discussed. Leaf anatomy is of limited value in elucidating relationships within the genus.     

Effects of alternative food on cannibalism and herbivore suppression by carabid larvae

1. Predator and alternative food density are important factors influencing herbivore suppression by generalist predators. Herbivore suppression can be reduced if predators forage preferentially on alternative foods. Cannibalism can increase at high predator densities, further reducing herbivore suppression. However, complex interactions are possible, as alternative food can increase predator abundance and survival restoring top‐down effects on herbivores. 2. In two species of carabid larvae (Poecilus chalcites and Anisodactylus ovularis), we studied how alternative foods (fly pupae and grass seeds) and predator density affect predation of black cutworm larvae and how alternative foods affect cannibalism among carabid larvae. 3. Adding alternative food to microcosms generally reduced total predation of cutworms. However, the strength of this effect was dependent on carabid species, larval density, and food type. 4. Increasing larval density from one to three per microcosm reduced per‐capita predation by both species irrespective of alternative food treatment. 5. Alternative food reduced cannibalism in both carabid species and increased survival of carabid larvae in field plots, such that twice as many were captured in plots subsidised with pupae than plots with no alternative food. 6. These results provide new insight into the complex interactions that influence predator survival and herbivore suppression in resource diverse habitats by demonstrating the primacy of intraguild interactions among carabid larvae.     

HEART DISEASE AND SOCIAL INEQUALITY: ETHICAL ISSUES IN THE AETIOLOGY, PREVENTION AND TREATMENT OF HEART DISEASE

Heart disease is a complex condition that is a leading cause of death worldwide. It is often seen as a disease of affluence, yet is strongly associated with a gradient in socio-economic status. Its highly complex causality means that many different facets of social and economic life are implicated in its aetiology, including factors such as workplace hierarchy and agricultural policy, together with other well-known factors such as what passes for individual 'lifestyle'. The very untangling of causes for heart disease thus inevitably raises social, moral and political issues. These include the proper role of the individual and of larger social forces in its aetiology, prevention and treatment. The construction of risk factors for heart disease likewise is enmeshed with questions of distributive justice in the responsible targeting of those at risk for heart disease, a debate which has received much overt attention in the medical literature, but less attention within the ethical literature. Strategies for addressing a condition of such complex causality can be highly diverse, from pharmaceutical to social interventions, and value issues attach to the choice and presentation of such strategies. For example, prevention strategies may raise complex issues of responsibility and of judgements of what it is to 'live well'. Further ethical debate on this highly political disease would be welcome.     

Determining the effects of habitat management and climate on the population trends of a declining steppe bird

The Little Bustard Tetrax tetrax is one of the most threatened steppe bird species in Europe, due mainly to agricultural intensification. Despite the relative importance of the Iberian population (approximately 50% of the global population) little is known about its dynamics and trends, especially in core distribution areas. This study evaluates the influences of meteorological factors and land management on the oscillations and medium-term trends of two Little Bustard populations in Central Spain. During 2001–2007, surveys of breeding male and female Little Bustards were carried out in two central Spanish locations: Valdetorres, in Special Protection Area (SPA) no. 139 (1600 ha), and Campo Real, in Important Bird Area (IBA) no. 075 (1150 ha). Densities were 3.3–4.0 and 1.1–2.1 males/km² in Campo Real, and 1.8–2.2 and 0.6–1.3 females/km² in Valdetorres. The sex ratio was biased towards males in both cases. Both populations declined during 2001–2007, especially in Valdetorres (60%). Variation in habitat composition did not explain variation in the numbers of males. Both populations were influenced by total precipitation in the preceding October–May period. Results suggest that the Little Bustard may be sensitive to future climate trends in Europe. Finally, different simulated demographic scenarios suggest that low female survival and productivity may be the immediate cause of the decline in Little Bustard populations, which is consistent with their sensitivity to climatic conditions.     

Effectiveness of Scat Detection Dogs for Detecting Forest Carnivores

Abstract: We assessed the detection and accuracy rates of detection dogs trained to locate scats from free-ranging black bears (Ursus americanus), fishers (Martes pennanti), and bobcats (Lynx rufus). During the summers of 2003-2004, 5 detection teams located 1,565 scats (747 putative black bear, 665 putative fisher, and 153 putative bobcat) at 168 survey sites throughout Vermont, USA. Of 347 scats genetically analyzed for species identification, 179 (51.6%) yielded a positive identification, 131 (37.8%) failed to yield DNA information, and 37 (10.7%) yielded DNA but provided no species confirmation. For 70 survey sites where confirmation of a putative target species' scat was not possible, we assessed the probability that ≤1 of the scats collected at the site was deposited by the target species (probability of correct identification; P_ID). Based on species confirmations or P_ID values, we detected bears at 57.1% (96) of sites, fishers at 61.3% (103) of sites, and bobcats at 12.5% (21) of sites. We estimated that the mean probability of detecting the target species (when present) during a single visit to a site was 0.86 for black bears, 0.95 for fishers, and 0.40 for bobcats. The probability of detecting black bears was largely unaffected by site- or visit-specific covariates, but the probability of detecting fishers varied by detection team. We found little or no effect of topographic ruggedness, vegetation density, or local weather (e.g., temp, humidity) on detection probability for fishers or black bears (data were insufficient for bobcat analyses). Detection dogs were highly effective at locating scats from forest carnivores and provided an efficient and accurate method for collecting detection-nondetection data on multiple species.     

Fine-scale microhabitat selection in a bromeliad-dwelling jumping spider (Salticidae)

Although a wide variety of arthropods specialize on a specific host plant, little is known about the evolution of host–plant specialization in spiders. In several regions of South America, the Neotropical jumping spider Psecas chapoda associates with Bromelia balansae , a rosette-shaped plant that does not accumulate rain water in phytotelmata. We conducted experiments using bromeliad species with distinct architectures that were uncommon in the geographic range of P. chapoda to investigate the level of spider specialization in microhabitat structure. We also tested the influence of phytotelmata and foliar spines on host plant selection. B. balansae , Ananas comosus and Aechmea distichantha (tank-bromeliad), which share similar traits (e.g. long and narrow leaves), were colonized in similar frequencies. Aechmea fasciata , a tank-bromeliad that has short and broad leaves, was never colonized by these spiders, and Aechmea blanchetiana , tank-bromeliad with long and broad leaves, was only colonized infrequently. The removal of foliar spines did not affect the number of P. chapoda on B. balansae . Our findings suggest that microhabitat specialization by P. chapoda is based on rosette and leaf architectures. This unusual specialization likely evolved because the bromeliads with such architecture (i.e. B. balansae ) typically dominate the biogeographic area of P. chapoda , and because this microhabitat provides specific benefits to spiders, as shelter, and as foraging and reproductive sites.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 653–662.     

Systematics of Ruscaceae/Convallariaceae: a combined morphological and molecular investigation

This paper discusses the intrafamilial systematics of Ruscaccae sensu lata by means of a combined molecular-morphological analysis. Ruscaceae sensu lata (including former Con-vallariaceae. Dracaenaceae and Nolinaccac, as well as Comospermum and Eriospermum ) represent a well-supported clade in other molecular analyses and are further linked by the absence of phytomclan in the seed coat. Within this clade there is an unusual lack of sequence divergence for such a morphologically varied group of taxa, but the combined morphological-molecular analysis indicates some groupings: (1) Eriospermum , (2) Comospermum , (3) nolinoids (former Nolinaceac) plus Ophiopogon and Liriope (Ophiopogonae, excluding Peliosanthes ), (4) dracaenoids (former Dracaenaceae), (5; Polygonatae and (6) a clade comprising Convallarieac (including Aspidistra ) and the ruscoids (Ruscaccae sensu stricto ) plus Peliosanthes. In the morphological analysis Peliosanthes is embedded in Convallarieae, and in the molecular analysis it is sister to all other Ruscaceae except Eriospermum: in neither case does it fall with Ophiopogon and Liriope (Ophiopogonae), with which it was traditionally placed. Peliosanthes has several characters in common with some Convallarieae, e.g. filaments fused into a column surrounding the gynoecium, and a thick, fleshy corona with the stigma more or less filling the narrow floral opening. On the other hand, there arc also some notable differences, such as in karyotype, leaf anatomy, pollen morphology and nectaries. Since there is a considerable range of morphological variation in the taxon currently designated as Peliosanthes. more taxonomic work is needed to establish the monophyly of this genus before there can be confidence in its relationships within Ruscaccae sensu lata.     

Interannual climatic variation mediates elevated CO2 and O3 effects on forest growth

We analyzed growth data from model aspen (Populus tremuloides Michx.) forest ecosystems grown in elevated atmospheric carbon dioxide ([CO₂]; 518 μL L^?1) and ozone concentrations ([O₃]; 1.5 × background of 30–40 nL L^?1 during daylight hours) for 7 years using free‐air CO₂ enrichment technology to determine how interannual variability in present‐day climate might affect growth responses to either gas. We also tested whether growth effects of those gasses were sustained over time. Elevated [CO₂] increased tree heights, diameters, and main stem volumes by 11%, 16%, and 20%, respectively, whereas elevated ozone [O₃] decreased them by 11%, 8%, and 29%, respectively. Responses similar to these were found for stand volume and basal area. There were no growth responses to the combination of elevated [CO₂+O₃]. The elevated [CO₂] growth stimulation was found to be decreasing, but relative growth rates varied considerably from year to year. Neither the variation in annual relative growth rates nor the apparent decline in CO₂ growth response could be explained in terms of nitrogen or water limitations. Instead, growth responses to elevated [CO₂] and [O₃] interacted strongly with present‐day interannual variability in climatic conditions. The amount of photosynthetically active radiation and temperature during specific times of the year coinciding with growth phenology explained 20–63% of the annual variation in growth response to elevated [CO₂] and [O₃]. Years with higher photosynthetic photon flux (PPF) during the month of July resulted in more positive growth responses to elevated [CO₂] and more negative growth responses to elevated [O₃]. Mean daily temperatures during the month of October affected growth in a similar fashion the following year. These results indicate that a several‐year trend of increasingly cloudy summers and cool autumns were responsible for the decrease in CO₂ growth response.