Can in vitro biology have farm-level impact for small-scale cassava farmers in Latin America?

Summary Cassava is uniquely suited for food security and economic development in unfavored areas of the tropics. Development research for cassava is an urgent need. In 1998, the Cassava Biotechnology Network (CBN) convened a workshop of cassava stakeholder groups in Latin America. After hearing an opening statement from representatives of small-scale cassava producers and processors, stakeholders formulated a consensus set of research and development (R&D) priorities. An adequate supply of good-quality planting material of desired varieties was clearly the most urgent, followed by R&D on market-value traits; yield losses due to pests, diseases, and drought; and cropping system flexibility. Two new projects are using in vitro techniques to address priorities of small-scale cassava farmers in Latin America. One project in Colombia combines a nongovernmental organization, a local farmers’ association, and the international research center, CIAT, to explore affordable micropropagation. Findings to date show that most culture medium components can be replaced with local products, and a rustic growth room permits good culture growth without electricity or air conditioning. Low-costs system(s) developed will be assessed as a local microenterprise. A second project, in Ecuador, couples local cassava germplasm (with oral histories and an in vitro back-up collection) and elite clones (introduced in vitro) with new concepts in agribusiness development, to restart local farmers’ cooperatives after the disastrous 1998–99 el Ni?o floods. The project was developed through group planning by the cooperatives, the local technical university, the national agricultural research program, and CIAT. Research to improve in vitro tools focuses on safe and stable conservation and exchange of cassava genetic resources, long-term, less expensive conservation, rapid clonal propagation, and ultimately, genetic transformation technologies to add desired traits to useful cassava varieties.     

Molecular evidence for a species complex in the patagonian lizard Liolaemus bibronii and phylogeography of the closely related Liolaemus gracilis (Squamata: Liolaemini)

The lizard genus Liolaemus is endemic to temperate South America and includes 190 species. Liolaemus bibronii has a large geographic distribution and inhabits a great diversity of habitats, including the Monte, Steppe, and high Andean grassland environments. Liolaemus gracilis has a similar body size and shape to L. bibronii; the two are parapatrically distributed, and L. gracilis is also widely distributed. Here we use the mtDNA cytb sequence data of these two species to investigate lizard phylogeographic patterns in southern South America. L. bibronii is paraphyletic with respect to L. gracilis, Liolaemus ramirezae, Liolaemus robertmertensi and Liolaemus saxatilis; it is composed of many genetically different allopatric haploclades, some of which are reciprocally monophyletic. We also found evidence for introgression between L. bibronii and L. gracilis in the same area that introgression was hypothesized in the Liolaemus darwinii complex. We discuss the distribution of the major haploclades with inferences of their population histories, the concordance of these clades' distributions and histories with other lizard complexes studied with the same markers and methods, and taxonomic implications of these results.     

Growth and reproductive characteristics in artificially formed clonal gametophytes ofDryopteris filix-mas (Dryopteridaceae)

Artificially formed clonal gametophytes ofDryopteris filix-mas (L.)Schott were able to grow and reproduce, although growth rates, proportions of hermaphrodites and reproductive efforts were low. Variable density and nutrient levels appeared to affect gametophytic life histories and they continued to influence the viability of the developing sporophyte generation. Differences between populations and sporophytes were discovered in life histories. Hermaphroditic gametophytes were considerably larger and possessed higher viability than did males. Clear differences between clones in the level of phenotypic plasticity in gametophyte size were observed. No neighbor effect on gametophyte sex expression was detected with the densities and nutrient levels used.     

Association of ectomycorrhizal mats with Pacific yew and other understory trees in coniferous forests

This study was designed to determine whether ectomycorrhizal mats (ECM) are more likely to be present in soils at the base of common understory trees than in soils distant from trees and to determine whether occurrence of ECM is related to tree size. Three understory trees were studied: Pacific yew (Taxus brevifolia Nutt.), western hemlock (Tsuga heterophylla (Raf.)Sarg), and vine maple (Acer circinatum Pursh). The 12 sites studied represent a range of climatic conditions and management histories. More than 2,900 plots were surveyed over 18 months. The incidence of ECM was higher at the base of all three species than in control plots. Incidence of mats was also positively correlated with tree size. Saplings consistently had a lower incidence of ECM than did larger trees.Paper 3028 of the Forest Research Laboratory, Oregon State University, Corvallis     

Comparison of two domoic acid-producing diatoms: a review

In the past five years, awareness of domoic acid has increased from localized problems in Canada to outbreaks along both North American coasts. The phycotoxin domoic acid causes Amnesic Shellfish Poisoning (ASP) in humans and can be fatal. The known species of phytoplankton responsible for production of domoic acid include some pennate diatom species of the genus Nitzschia, sensu latu, which form stepped chains typical of the Pseudonitzschia. These diatoms are widely distributed, but their life histories and population dynamics are poorly understood. This review addresses histories of occurrences, morphology, geographical distributions, seasonal patterns, growth requirements, domoic acid production, and trophic interactions, with emphasis on a comparison of Pseudonitzschia pungens f. multiseries (Hasle) Hasle and Pseudonitzschia australis Frenguelli. Through continued research it will become possible to provide guidelines for regulatory agencies that protect both the consumer and the seafood industry.     

Heterosis in crosses between lines of Drosophila melanogaster selected for adaptation to different environments

Summary Experiments were designed to examine whether heterosis would occur in crosses of Drosophila melanogaster populations adapted to 18 °C or 28 °C environments. Crosses were examined in parental environments, an intermediate environment (23 °C) and a mixed environment (alternating 18°/28°C). Parental populations did not show divergence for larval viability, cold shock or high temperature mortalities when tested in a common environment. However, the 28 °C population was less fecund than the 18 °C population, but had higher larval competitive ability and higher adult longevity. Heterosis for viability, cold shock mortality and high temperature mortality occurred in crosses between a population adapted to 18 °C and another adapted to 28 °C, but not in crosses between two populations adapted to the same temperature. The results suggest that, in the absence of drift, heterosis is expected in crosses between lines or populations with different histories of selection but not between lines with the same selection histories.     

Laboratory culture and taxonomy of two species ofDerbesia (Class Chlorophyceae) in Japan

Two species ofDerbesia (Class Chlorophyceae),D. marina andD. tenuissima, have been studied for the purpose of obtaining a better understanding of their morphological details and life histories, using preserved and living specimens as well as laboratory cultures. The life histories of both species were completed in the laboratory, starting from both zoospores and zygotes. Specimens were collected at Asamushi, Aomori-ken, and Shimoda, Shizuoka-ken. Their life history types are fundamentally identical, zoospores giving rise upon germination toa Halicystis-phase, while zygotes grow into aDerbesia-phase. The thallus of theHalicystis-phase which alternates withD. marina is the same as that ofH. ovalis which grows in the northern regions of Japan. On the other hand, the thallus of theHalicystis-phase alternating withD. tenuissima is the same as that ofH. parvula known to occur in the temperate to subtropical regions of Japan. These results coincide with those obtained withD. marina andD. tenuissima in Europe, where the type localities of both species are located. Specimens assignable to these two species were collected at several localities in Japan and, as a result of detailed examination of the morphology, they are believed to be identical with eitherD. marina orD. tenuissima.     

Influences of riparian logging on plants and invertebrates in small,depressional wetlands of Georgia,U.S.A.

We studied 12 small, seasonally flooded, depressional wetlands on the Atlantic Coastal Plain of Georgia, U.S.A. Each wetland was embedded in stands of managed plantation pine. The pine trees surrounding each wetland had been harvested and replanted beginning in 1997 (2 sites), 1995 (2 sites), 1993 (1 site), 1988 (2 sites), 1984 (2 sites) or 1975 (3 sites). Regressions of various environmental variables with harvest histories indicated that those wetlands surrounded by smaller trees had greater light levels, water temperatures, pH, herbaceous plant cover and biomass, terrestrial invertebrate diversities and numbers, and water flea numbers, and lower water electrical conductivities and aquatic oligochaete numbers than those wetlands surrounded by more mature trees. Detected variations in hydroperiod, water depth, dissolved oxygen levels, sediment inputs, macrophyte diversity, periphyton biomass and densities of most aquatic invertebrates were not clearly correlated with past histories of peripheral tree harvest. This study suggests that harvesting trees around small wetlands initiates physical and ecological changes within the embedded habitats and that changes can persist for up to 15 years.     

Aspergillosis in Larus cachinnans micaellis: Survey of Eight Cases

Avian aspergillosis is reported in several avian species, with Aspergillus fumigatus as the main aetiological agent. Predisposing factors such as starvation, thermal stress, migratory stress, primary infectious disease or toxicosis may play a role. Eight cases of disseminated aspergillosis in free ranging seagulls sheltered at C.R.U.M.A. (Centro Recupero Uccelli Marini e Acquatici, Livorno, Italy) with different clinical histories are presented. The infection was demonstrated by cultural and histological methods from lesions of all birds, and the presence of airborne A. fumigatus viable elements ranging from 450 to 525 CFU/m³ inside and outside the shelter by means of a surface air sampler (SAS) Super-90 was also assessed. The role of this fungal species as an opportunistic factor in the captivity of seagulls is considered and some control measures, such as a clean and stress free environment and the use of antifungal drugs are suggested.     

Comparative life histories and microhabitat use in three sympatric sculpins (Cottidae:Cottus) in northeastern California

Synopsis Life histories of three sculpins endemic to the Pit River system, northeastern California, are detailed.Cottus pitensis is widely distributed throughout the drainage. This species is typically found in rapidly flowing, shallow water on coarse substrate. It grows to a large size, >100 mm, and lives to 5 years. Spawning occurs annually, in early spring. Fecundity is relatively low, <320 oocytes.Cottus asperrimus is restricted to a large population in Fall River and smaller concentrations in Hat Creek and Pit River. It is a relatively small fish, <80 mm, and lives to 5 years. It occurs in deep, slow-moving, often spring-fed streams, typically on fine substrates. Spawning lasts from autumn to early spring. Males establish nests on hard substrates and guard several clutches of eggs. Fecundity ranges from 140–580 oocytes.Cottus klamathensis macrops is relatively rare in the drainage. The largest concentration is in the Hat Creek system, smaller populations exist in Fall River and Pit River. This sculpin is found on coarse substrate, often where aquatic vegetation is abundant. It is typically found in slow, relatively shallow water. It grows to >100mm and lives to 5 years. Males guard eggs during the short spawning season beginning in late winter. Fecundity in this species reaches a maximum of 650 oocytes. Life history strategies vary within the genus, yet the life histories of these sculpins are more similar to each other than they are to many of their congeners. This within-group similarity may have resulted from exposure of all three species to similar environmental pressures. This is predicted by life-history theory.     

What makes a species vulnerable to extinction? Comparative life-history traits of two sympatric snakes

Although it is well known that species vary in their vulnerability to extinction, the reasons are poorly understood. Theory predicts that long-lived species with slow life histories (small litters, slow growth, late maturation) should be at greater risk than short-lived species with high potential rates of increase. This hypothesis was tested by comparing life-history traits of two species of sympatric, elapid snakes: the endangered broad-headed snake, Hoplocephalus bungaroides, and common small-eyed snake, Cryptophis nigrescens. From 1992 to 2000 a mark–recapture study of both species was undertaken in Morton National Park, south-eastern Australia, and this information was used to construct transition matrices for each species. The endangered H. bungaroides was found to mature late (6 years of age), had a high juvenile (54.7%) and adult (81.6%) survival rate, and a long generation length (10.4 years). In striking contrast, the common C. nigrescens matured early (within 3 years), had a lower juvenile (30.4%) and adult (74.4%) survival rate (but higher recruitment rate), and a substantially shorter generation length (5.9 years). Elasticity analyses revealed that H. bungaroides was considerably more sensitive to survival past the age of 2 years (68.6%) than C. nigrescens (37.4%). These results provide support for the hypothesis that species with slow life histories are more vulnerable to extinction.     

Alien conifer invasions in South America: short fuse burning?

Alien conifers have been widely planted in the Southern Hemisphere. Australia, New Zealand and South Africa, all with long histories of alien conifer planting, have major problems with invasive conifers (“wildings”). Widespread planting of alien conifers has a much shorter history in South America, and invasions are a recent phenomenon. A workshop was convened in Argentina in May 2007 to discuss the rapid emergence of problems with invasive conifers in South America. Workshop delegates agreed that: the problem is likely to increase substantially and rapidly in many parts of the continent; the problem is not widely recognized; lessons from elsewhere can be transferred; and collaboration can bring benefits. The need was expressed: for an accurate assessment of the dimensions of the problem; to raise awareness of the problem; for a common research agenda; to initiate management interventions. This paper summarizes the key aims, deliberations, and planned outcomes of the workshop. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Use and partition of space and resources by two coexisting Rhyacophila species (Trichoptera) in a high mountain stream

Life history, distribution, drift and food habits of two coexisting Rhyacophila species, Rhyacophila evoluta and Rhyacophila intermedia were studied in a high mountain stream in the Pyrénées.The life histories of both species took two years downstream and three years upstream. Several generations and a large range of larval instars permanently coexisted in the river.Slight temporal segregation of the life histories and differences in size and food habits of the coexisting larvae partially reduced the interspecific competition and allowed an optimal use of space. Instars IV of R. evoluta and V of R. intermedia, which had the most similar biological characteristics had the same microdistribution when they lived alone but used different habitats when they coexisted.     

Comparative phylogeography and population genetics within Buteo lineatus reveals evidence of distinct evolutionary lineages

Traditional subspecies classifications may suggest phylogenetic relationships that are discordant with evolutionary history and mislead evolutionary inference. To more accurately describe evolutionary relationships and inform conservation efforts, we investigated the genetic relationships and demographic histories of Buteo lineatus subspecies in eastern and western North America using 21 nuclear microsatellite loci and 375-base pairs of mitochondrial control region sequence. Frequency based analyses of mitochondrial sequence data support significant population distinction between eastern (B. l. lineatus/alleni/texanus) and western (B. l. elegans) subspecies of B. lineatus. This distinction was further supported by frequency and Bayesian analyses of the microsatellite data. We found evidence of differing demographic histories between regions; among eastern sites, mitochondrial data suggested that rapid population expansion occurred following the end of the last glacial maximum, with B. l. texanus population expansion preceding that of B. l. lineatus/alleni. No evidence of post-glacial population expansion was detected among western samples (B. l. elegans). Rather, microsatellite data suggest that the western population has experienced a recent bottleneck, presumably associated with extensive anthropogenic habitat loss during the 19th and 20th centuries. Our data indicate that eastern and western populations of B. lineatus are genetically distinct lineages, have experienced very different demographic histories, and suggest management as separate conservation units may be warranted.     

Memory Pieces and Footprints: Multivocality and the Meanings of Ancient Times and Ancestral Places among the Zuni and Hopi

The notion of the "contested past" has grown to be an important topic in anthropological research in recent decades, linking such themes as nationalism, identity, museology, tourism, and war. In North America, these discussions have largely centered on archaeology's shifting relationship with native peoples. As scholars give new attention to how research methodologies and representation of cultural histories affect indigenous peoples, it is critical to understand the unique ways in which Native Americans view their past. Contemporary Zuni and Hopi interpretations of ancestral landscapes in the San Pedro Valley of Arizona are used to explore how indigenous worldviews imbue ancient places with deep cultural and individual meanings. This research, based on a three-year collaborative ethnohistory project, argues for resolution to the "contested past" by incorporating a perspective of multivocality, which will enable the creation of alternative histories that do not eschew scientific principles while respecting native values of history.     

The relationship between flat periwinkle life histories and digenean infections

Larval digenean parasites were studied in Littorina obtusata (L.) and L. mariae Sacchi & Rastelli at Sawdern Point in West Wales. Shell parameters, ovipositor and shell colour, penis morphology and sex ratios were scored, and the influence of parasitism studied. A total of 7 species of parasites were found, although the prevalence was very low in L. mariae, especially in the females. The parasitic gigantism that has been described in other species of gastropod was not found in this study. Parasitic castration does occur in some infected male L. obtusata, resulting in severe stunting of the penis. However, this phenomena was never observed in L. mariae. The winkle species are congeneric and inhabit broadly similar niches on the shore; their life histories are however quite different — one being annual and the other perennial. This probably affects exposure to infection, and might explain the differing prevalence of the parasites.     

Different growth responses to temperature and resource limitation in three fly species with similar life histories

Growth responses to temperature and resource limitation in three dipteran species with similar life histories were compared. With respect to current life history theory, two points are raised. First, growth rate in real time increased steeply with temperature in all species, following the standard pattern. However, when expressed in physiological time growth rate increased as temperature decreased in the yellow dung fly Scathophaga stercoraria, remained approximately constant in Sepsis cynipsea, and increased in Drosophila melanogaster. These responses can be understood as adaptations to climate and seasonality. It is concluded that some patterns of adaptation may be more easily interpreted if, and some may even go undetected unless, they are analysed in physiological time. Second, a decrease in body size, development rate and growth rate when resources are limited is believed to be nearly universal and generally predicted by life history models. Despite their similar life histories, the three species investigated showed qualitatively different growth responses to larval food shortage. At unlimited resources, yellow dung flies showed the fastest initial larval body mass gain per unit time, while those of S. cynipsea and D. melanogaster were lower and about equal. The period of no body mass gain at the end of larval development was longest in S. stercoraria and shortest in S. cynipsea. When facing resource limitation, S. stercoraria emerged smaller but earlier (thus nearly maintaining their growth rate), S. cynipsea smaller after the same development period, and D. melanogaster smaller and later (showing reduced and much reduced growth, respectively). It is concluded that whether growth really slows when resources are limited depends on the precise ecological circumstances of the species in question. More refined models, particularly those where mortality costs are independent of time, and more experiments are necessary to account for the variation in growth and size and age at maturity present in nature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Motherless mothers revisited: Rhesus maternal behavior and rearing history

Classic studies have demonstrated that isolation- and peer-rearing in infancy can result in overt deficits in maternal behavior in rhesus monkeys, although nonmother-reared monkeys may become adequate caretakers if allowed experience with infants. Maternal styles in normally-reared mothers have been reported to vary widely. In the present study, the range of maternal proficiency of nonabusive, nonrejecting nonmother-reared mothers was examined. The behavior of mother-reared, peer-reared, and isolate-reared multiparous mothers was observed and compared for the first six months following parturition. Both peer-reared and isolate-reared mothers exhibited differences in maternal behavior from mother-reared mothers. Inasmuch as variations in maternal behavior may impact on the infant, investigators should be aware of the rearing histories of females used as breeders in the laboratory.     

Use of Biochronology to Examine Interactions of Freshwater Drum, Walleye and Yellow Perch in the Red Lakes of Minnesota

Growth histories for freshwater drum, Aplodinotus grunniens, walleye, Stizostedion vitreum, and yellow perch, Perca flavescens, were constructed using calcified structures for the period 1947 through 1996 for the Red Lakes, Minnesota. Increased walleye growth and decreased yellow perch growth were observed over the period from 1983 to 1996, which are attributed to intensive fishing resulting in decreased intraspecific competition in walleye and increased intraspecific competition in yellow perch through release from predation. Strong year-classes of yellow perch were positively correlated with walleye growth (r=0.57, p-value=0.042). There was no evidence for interactions of walleye or yellow perch with freshwater drum. Freshwater drum growth (r=0.680, p-value=0.0001) was more highly correlated with temperature than were walleye (r=0.386, p-value=0.006) and yellow perch growth (r=0.303, p-value=0.036).     

Route design,the foundation of successful chemical development

Route Design is the first step in the strategic development process for manufacture of a new active pharmaceutical ingredient (API). Numerous benefits can be realised for the project and the broader performance of the company. We present an appreciation of some of the potential challenges and describe the principles and practices that have shaped the Route Design culture within AstraZeneca. This is exemplified with case histories and we describe some of the activities that have supported our scientists and the simple messages used to educate the broader organisation.