Circulating tumour cells: The Good,the Bad and the Ugly

This review is an overview of the current knowledge regarding circulating tumour cells (CTCs), which are potentially the most lethal type of cancer cell, and may be a key component of the metastatic cascade. The clinical utility of CTCs (the "Good"), includes their diagnostic, prognostic, and therapeutic potential. Conversely, their complex biology (the "Bad"), including the existence of CD45+/EpCAM+ CTCs, adds insult to injury regarding their isolation and identification, which in turn hampers their clinical translation. CTCs are capable of forming microemboli composed of both non-discrete phenotypic populations such as mesenchymal CTCs and homotypic and heterotypic clusters which are poised to interact with other cells in the circulation, including immune cells and platelets, which may increase their malignant potential. These microemboli (the "Ugly") represent a prognostically important CTC subset, however, phenotypic EMT/MET gradients bring additional complexities to an already challenging situation.     

Magnetic Compass Orientation in the European Eel

European eel migrate from freshwater or coastal habitats throughout Europe to their spawning grounds in the Sargasso Sea. However, their route (∼ 6000 km) and orientation mechanisms are unknown. Several attempts have been made to prove the existence of magnetoreception in Anguilla sp., but none of these studies have demonstrated magnetic compass orientation in earth-strength magnetic field intensities. We tested eels in four altered magnetic field conditions where magnetic North was set at geographic North, South, East, or West. Eels oriented in a manner that was related to the tank in which they were housed before the test. At lower temperature (under 12°C), their orientation relative to magnetic North corresponded to the direction of their displacement from the holding tank. At higher temperatures (12–17°C), eels showed bimodal orientation along an axis perpendicular to the axis of their displacement. These temperature-related shifts in orientation may be linked to the changes in behavior that occur between the warm season (during which eels are foraging) and the colder fall and winter (during which eels undertake their migrations). These observations support the conclusion that 1. eels have a magnetic compass, and 2. they use this sense to orient in a direction that they have registered moments before they are displaced. The adaptive advantage of having a magnetic compass and learning the direction in which they have been displaced becomes clear when set in the context of the eel’s seaward migration. For example, if their migration is halted or blocked, as it is the case when environmental conditions become unfavorable or when they encounter a barrier, eels would be able to resume their movements along their old bearing when conditions become favorable again or when they pass by the barrier.     

Is the Performance of a Specialist Herbivore Affected by Female Choices and the Adaptability of the Offspring?

The performance of herbivorous insects is related to the locations of defenses and nutrients found in the different plant organs on which they feed. In this context, the females of herbivorous insect species select certain parts of the plant where their offspring can develop well. In addition, their offspring can adapt to plant defenses. A system where these ecological relationships can be studied occurs in the specialist herbivore, Tuta absoluta, on tomato plants. In our experiments we evaluated: (i) the performance of the herbivore T. absoluta in relation to the tomato plant parts on which their offspring had fed, (ii) the spatial distribution of the insect stages on the plant canopy and (iii) the larval resistance to starvation and their walking speed at different instar stages. We found that the T. absoluta females preferred to lay their eggs in the tomato plant parts where their offspring had greater chances of success. We verified that the T. absoluta females laid their eggs on both sides of the leaves to better exploit resources. We also observed that the older larvae (3^rd and 4^th instars) moved to the most nutritious parts of the plant, thus increasing their performance. The T. absoluta females and offspring (larvae) were capable of identifying plant sites where their chances of better performance were higher. Additionally, their offspring (larvae) spread across the plant to better exploit the available plant nutrients. These behavioral strategies of T. absoluta facilitate improvement in their performance after acquiring better resources, which help reduce their mortality by preventing the stimulation of plant defense compounds and the action of natural enemies.     

Chimpanzees spontaneously alter the location of their gestures to match the attentional orientation of others

Chimpanzees, Pan troglodytes, interacted with a familiar human partner across a table that contained a piece of highly desirable food and an undesirable distracter object. We explored how the chimpanzees' deployed their gestures on trials in which the food and object were out of their reach, thus creating a context in which they needed to recruit their partner's assistance in order to obtain the food. The attentional focus of their partner was directed either at the food, at the distracter object, or at a neutral location on the ceiling. Although the location of the food exerted primary control over the location of the chimpanzees' gestures, the results also clearly show that when their partner's focus was on the distracter object, the subjects modified their pattern of gesturing to accommodate the discrepancy between the object they wanted and the object on which their partner was focused. We discuss the results in the context of the evolution of joint and shared attention in humans, chimpanzees and other primates. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Biology of the African clupeid Limnothrissa miodon with reference to its small size in artificial lakes

Summary Limnothrissa miodon is a clupeid from Lake Tanganyika which has been introduced to Lakes Kivu and Kariba and which invaded Lake Cahora Bassa. These lakes differ considerably from one another but the biology of Limnothrissa is similar in many respects in all of them. Similarities include its feeding and breeding biology, whilst its populations fluctuate, on both an annual and a seasonal basis, in relation to environmental changes. The major differences between the lakes concern the size to which Limnothrissa grows. Their average length in the two natural lakes, Lakes Tanganyika and Kivu, is about twice the average length in the two artificial lakes, Lakes Kariba and Cahora Bassa. This in turn affects their age of maturity and they breed during their first year in the reservoirs but during their second in the natural lakes. Their growth rates and performance are comparable up to about 6 months of age and the difference in their size seems to be due to high mortality in the artificial lakes where few Limnothrissa survive for more than a year. Possible explanations for their small size include the genetic composition of the original introduction and the unpredictability of the environment. Neither of these explanations is supported by evidence at present. Deficiencies in the available food and the effects of intense predation are probably the most likely causes. In both natural lakes, Limnothrissa are predatory or cannibalistic from 100 mm in length and 12 months in age, and fish in their diet may enable them to survive into their second year. The fish in Lakes Kariba and Cahora Bassa, in contrast, are neither predatory nor cannibalistic to any degree. There are no predatory fish species in Lake Kivu but there is a diverse community of pelagic piscivores in Lake Tanganyika which tends to contradict the predation hypothesis. However, the position of Limnothrissa in the reservoirs probably resembles that occupied in Lake Tanganyika by Stolothrissa which is also a small, annual species. The significance of this phenomenon is that Limnothrissa can maintain a high biomass and productivity in the face of intense predation. This trait may be of importance to fisheries management because it means that their yield can be greatly increased.     

An alternative hibernation strategy involving sun-exposed 'hotspots', dispersal by flight, and host plant finding by olfaction in an alpine leaf beetle

Oreina cacaliae (Schrank) (Coleoptera: Chrysomelidae) has a 2‐year life cycle that it has to complete within the short warm seasons of the harsh alpine environment. Three years of field observations and experiments revealed that not all beetles overwintered in the soil next to their principal host Adenostyles alliariae (Asteraceae), as was previously assumed, but that many O. cacaliae left their host in autumn and flew to overwintering sites that were extensively sun‐exposed. In spring, these individuals became active 2 months earlier than their conspecifics that had remained in the soil close to the host plant. These early beetles flew from their hibernation sites against the direction of the prevailing wind. After a random landing in snow, they walked to the spring host Petasites paradoxus (Asteraceae) and fed on its floral stalks, the only plant parts present at that time. A few weeks later, they took flight again to locate newly emerging A. alliariae on which they would feed and deposit larvae as did individuals that had overwintered close to A. alliariae. Leaves of A. alliariae contain pyrrolizidine alkaloids (PAs), which the beetles sequester for their own defence. The dominating PA (seneciphylline) was also found to be present in the floral stalks of P. paradoxus. With additional behavioural assays in the field and laboratory, we demonstrated the importance of plant odours in the short‐range host location process. This study reveals a unique hibernation behaviour in which part of the beetle population uses exceptionally warm locations from which they emerge in spring, long before all the snow has melted. This early, but risky emergence allows them to exploit a second, highly suitable host plant, which they locate first by wind‐guided flight and then by odour‐guided walking. The well‐fed beetles then use odour again to move to their principal host plant, on which they reproduce.     

When the refugee status becomes an economic asset: how Malians in a Burkinabé City negotiate the “refugee” category

ABSTRACT

Since early 2016, part of the Malian urban refugees living in Bobo-Dioulasso, Burkina Faso, have to “capitalize” on their refugee status to make ends meet. By examining when, why, and how the refugee status transmutes into an economic asset, this article shows how the possibilities to negotiate with the refugee category vary significantly within this group of forced migrants. Indeed, categories are not only imposed on people, but are negotiated by the actors themselves in their interactions and within their social and political economies. My article shows how the refugees’ ability or possibility to participate in the co-construction of their category is shaped by both the social and political context in which they are, as well as by wider intersectional and structural dynamics in which their lives are situated, such as socio-economic class, gender and race.     

Religious discrimination in Scotland: A rebuttal of Bruce et al.'s claim that sectarianism is a myth

A recent article on sectarianism in Scotland in Ethnic and Racial Studies by Bruce et al. sought to undermine the conclusions of a previous paper of ours, also published in this journal. Bruce et al. contend that sectarianism is a myth, while we have provided new qualitative evidence for personal experience of anti-Catholic discrimination in employment, which clearly contradicts their thesis. To contextualize these papers, we have summarized some of the key points of the evidence, and of the increasing concern about sectarianism in Scotland. In an effort to ridicule this concern, Bruce has attacked us as he has previously attacked a number of others. He and his co-authors accuse us of relying on respondents’ fallible judgements about the actual and appropriate proportions of Catholics in workplaces; then they try to interpret some of our respondents’ statements and their own quantitative evidence as supporting their myth hypothesis. We document here the process of misrepresentation by which they have sought to support their allegations, and we re-affirm the actual argument which led to our conclusions. We suggest a more obvious alternative interpretation of their own quantitative data, while raising misgivings about their use of 2001 census data. Questions about sectarian discrimination in Glasgow in the period 1950–2000 can no longer be baulked.     

Genes involved in resistance to powdery mildew in barley differentially modulate root colonization by the mycorrhizal fungus Glomus mosseae

 Arbuscular mycorrhizal fungi (AMF) and Erysiphe graminis are obligate biotrophic fungi with different outcomes in their interaction with plants, different targeted host tissues, but similar patterns of development and infection processes. These similarities raise the question of whether the two types of biotrophic fungal infections have common features in their regulation. To investigate this question, we compared a number of Ror and Rar barley mutants susceptible to E.graminis f. sp. hordei, as well as their resistant progenitors, for susceptibility to infection by the AMF Glomus mosseae. The two powdery mildew-resistant lines BC Ingrid and Sultan presented a similar reduction in G. mosseae development within roots when compared to the wildtype cultivar Ingrid, indicating a systemic effect of the altered genes in the plant. Ror and Rar mutants, in which susceptibility to powdery mildew is restored, showed increased resistance to AM fungal development in their roots when compared to their progenitors, which suggests that corresponding mutations must have affected genes which differentially modulate symbiotic and pathogenic biotrophic plant-fungus interactions. Accepted: 16 September 1999     

Mechanisms of Genetic Instability in Mollicutes (Mycoplasmas)

Mollicutes are unique microorganisms characterized by a great extent for the reduction in genetic material, which retained the capability of independent division on acellular nutrient media. Phenotypically mycoplasmas differed from other bacteria by their small size and lack of a cell wall (mollis, soft; cutis, skin). High dependence on metabolism components utilized in the cultivation medium and high metabolic plasticity due to the absence of many genome regulatory elements make mycoplasmas perfect parasites for cells of the eukaryotic origin. The ability of these microorganisms to pass through host cells and their assumed participation in AIDS activation facilitate the study of mycoplasma pathogenesis. Another important feature of mycoplasmas, which is expressed during their interaction with a macroorganism, is their ability to escape from the immune response of a host due to surface antigen variation. These adaptation capacities of mycoplasmas ensuring their life in various biological niches, given a limited genome and the direct metabolic dependence on an environment, cannot be adequately explained at present. In this review, we attempted to collect and systematize data that contribute to our understanding of the important feature of mycoplasmas, genetic instability, which may underlie many of their adaptive responses.     

FISH CONSERVATION IN SOUTH AFRICAN ESTUARIES: PRESSURES,PROBLEMS AND PROSPECTS

Summary

A review of the conservation status of fish in the estuarine environment around the South African coastline reveals that some species face serious problems associated either with habitat destruction, and its associated biological, physical and chemical components or exploitation. The 65 species considered fall into three categories; truly estuarine species, which are dependent on estuaries for their entire life; marine species dependent on estuaries during the juvenile phase of their life cycle; and marine species whose juveniles occur mainly in estuaries but are also found at sea. Included in the first two categories are 14 species of fish which are on the South African Red Data list. These comprise one species which is endangered, five which are vulnerable and eight which are rare. All groups are considered in relation to factors in estuaries which are affecting their populations. A conservation strategy is suggested for certain estuarine types or for specific estuaries which could ensure the survival of the entire range of estuarine faunas.     

Membrane-active properties of α-MSH analogs: aggregation and fusion of liposomes triggered by surface-conjugated peptides

Reaction of the melanotropin hormone analogs [Nle⁴,D-Phe⁷]-α-MSH and [Nle⁴,D-Phe⁷]-α-MSH(4-10), which were extended at their N-terminus by a thiol-functionalized spacer arm, with preformed liposomes containing thiol-reactive (phospho)lipid derivatives resulted in the aggregation of the vesicles and in a partial leakage of their inner contents. This aggregation/leakage effect, which was only observed when the peptides were covalently conjugated to the surface of the liposomes, was correlated with the fusion of the vesicles as demonstrated by the observed decrease in resonance energy transfer between probes in a membrane lipid mixing assay. A limited fusion was confirmed by monitoring the mixing of the liposome inner contents (formation of 1-aminonaphthalene-3,6,8-trisulfonic acid/p-xylene bis(pyridinium bromide) complex). The membrane-active properties of the peptides could be correlated with changes in the fluorescence emission spectra of their tryptophan residue, which suggested that after their covalent binding to the outer surface of the liposomes they can partition within the core of the bilayers. A blue shift of 10 nm was observed for [Nle⁴,D-Phe⁷]-α-MSH which was correlated with an increase in fluorescence anisotropy and with changes in the accessibility of the coupled peptide as assessed by the quenching of fluorescence of its tryptophan residue by iodide (Stern-Volmer plots). These results should be related to the previously described capacity of α-MSH, and analogs, to interact with membranes and with the favored conformation of these peptides which, via a β-turn, segregate their central hydrophobic residues into a domain that could insert into membranes and, as shown here, trigger their destabilization.     

Marketplace conversations in Cameroon: How and why popular medical knowledge comes into being

The author argues that buyers and sellers of Western pharmaceuticals at a local marketplace in Cameroon construct their ideas about illness and medicines in reaction to two kinds of situations in which they find themselves. The market situation induces people to adjust their medical beliefs to the economic transaction. Sellers are likely to inflate the efficacy of medicines and customers adjust their medical concepts to fit their limited financial means. In that way they rationalise their inability to buy all the drugs they would have liked to buy. The interview situation leads informants to produce rather specific and assured answers on topics about which they may know very little. Reasons include the inequality between interviewer and informant and the latter's wish to avoid making an ignorant impression on the interviewer. Three conversations held during fieldwork in 1983 are discussed.     

Recessive genetic variants affecting mating activity of males in natural populations ofDrosophila melanogaster

Mating activity of 115 wild males was compared with 88 homozygotes and 42 heterozygotes for their second chromosomes. Wild males, 48–96 hours old, inseminated on the average, 4.4±0.1 females per 24 hours. The hetero- and homozygotes for their second chromosomes (other chromosomes being randomly combined with those from the laboratory strain), inseminated on the average 2.8±0.2 and 2.0±0.2 females/24 h. respectively. There is no correlation between homozygotes and heterozygotes for the second chromosome and their wild ancestors which carried these chromosomes. Wild second chromosomes which in homozygous condition produced total sterility of their carriers, and some others which made for an unusually high activity in homozygous males, had on an average similar effects in wild carriers.This ariicle is warmly dedicated to Professor Theodosius Dobzhansky.     

MetaTM - a consensus method for transmembrane protein topology prediction

Background  

Transmembrane (TM) proteins are proteins that span a biological membrane one or more times. As their 3-D structures are hard to determine, experiments focus on identifying their topology (i. e. which parts of the amino acid sequence are buried in the membrane and which are located on either side of the membrane), but only a few topologies are known. Consequently, various computational TM topology predictors have been developed, but their accuracies are far from perfect. The prediction quality can be improved by applying a consensus approach, which combines results of several predictors to yield a more reliable result.     

The Worldwide Spread,Success, and Impact of Ragweed (Ambrosia spp.)

The Ambrosia species represent one of the most problematic groups of invasive weeds around the world. The ease with which they are introduced and spread in new countries, their generalist ecological requirements, and functional traits facilitate their invasion and subsequent naturalization in new areas. All of these aspects contribute to increasing their global social and economic impact, which is mostly related to pollen allergy. Here we analyze available scientific publications about Ambrosia artemisiifolia, A. psilostachya, A. tenuifolia, and A. trifida, with the aim of defining the current level of knowledge and summarizing important data that are currently scattered throughout the literature. Specifically, we analyzed the following: (1) their current global distribution and current stage of invasion; (2) traits and requirements promoting their introduction, reproductive success, and adaptation to climate and environment in the nonnative range; as well as (3) current knowledge about allergens and elements increasing their impact.     

The nature of centromeric dots in Nigella chromosomes

Derived telocentric chromosomes in Nigella doerfleri have pairs of Giemsa staining dots at their terminal centromeres which appear in size and behaviour to be identical with the centromeric dots of their submetacentric homologue. The telocentric chromosomes are stable and therefore their centromeres are functional and probably complete. That the centromeres also possess centromeric dots indicates that the dots represent essential components of the centromere, a conclusion which supports the contention that they are kinetochores.     

Developmental changes in mother-offspring grooming in Japanese macaques

A cross-sectional analysis was made of developmental changes in mother-offspring grooming in Japanese macaques, Macaca,. fuscata. When offspring were immature, time spent grooming by their mothers decreased with offspring age. Soliciting by offspring increased steadily with age, in contrast to their successful soliciting, which decreased gradually until early adolescence. This is in accord with the hypothesis that grooming is one form of post-weaning maternal investment, which may entail behavioral conflict between mothers and immature offspring. On the other hand, mothers spent much more time for grooming of their adult female offspring than for their adolescent male and female offspring. It is argued that grooming by mothers may shift from a form of maternal investment in their offspring to a benefit to be exchanged reciprocally with them. © 1995 Wiley-Liss, Inc.     

Standing Up: Violin Performance Technique and Ethnic Resurgence in Saraguro,Ecuador

With greater participation in formal education and increased occupational diversity and mobility, young, cosmopolitan Saraguro musicians in the southern highlands of Ecuador are working to reconstitute their Saraguro Quichua ethnicity in a creative and selective process by which they discard, amplify, and reinvent the aspects of what they perceive to be authentic Saraguro musical culture. Young Saraguro violinists use the bodily movement of performance technique as a key resource with which to reconstitute their ethnicity. Through visual analysis of performance technique and theories of ethnic renewal and bodily movement, I argue that, though older Saraguro violinists sit down low to play their violins, these young Saraguro violinists break from tradition and stand up when they play not only to index their aspirations to do something with their lives other than what tradition and stereotypes dictate for them, but also to index their real opportunities to do so as Saraguros.