Relationship between Growth and Ageing in <Emphasis Type="Italic">Drosophila</Emphasis>

THERE are two principal groups of theories of ageing—those which hold that random cell damage is chiefly responsible for the events characteristic of ageing, which culminate in death and those which hold that ageing and death are genetically controlled. It is too soon to decide between these points of view and in any case Bullough¹ has shown that they are not mutually exclusive. So far experiments to test the random error theories of ageing, involving exposure of organisms to unnaturally large or even small amounts of agents such as X-rays and mutagenic agents (for reviews, see refs. 2 and 3), have been controversial and inconclusive.     

Hard working nurses rather than over-aged nurses permit <Emphasis Type="Italic">Ropalidia marginata</Emphasis> to respond to the loss of young individuals

Summary The primitively eusocial wasp Ropalidia marginata exhibits a remarkably well-developed honey bee like age polyethism. Individuals perform different tasks sequentially as they age, starting with intranidal tasks (nursing and building in that order) and ending with extranidal tasks (foraging for pulp and food in that order). As in the case of honey bees such age polyethism is rather flexible; in the absence of old individuals (in young-cohort colonies), precocious foragers forage at abnormally young ages. Here we demonstrate that the absence of young individuals (in old-cohort colonies) does not result in over-aged nurses nursing at abnormally old ages, as seen in the case of honey bees. Instead it results in hard working nurses who nurse at abnormally high rates. The possible reasons for the absence of over-aged nurses and the presence of hard working nurses are discussed.Received 30 April 2003; revised 18 November 2003; accepted 5 January 2004.     

GENE‐DOSAGE EFFECTS ON FITNESS IN RECENT ADAPTIVE DUPLICATIONS: ace‐1 IN THE MOSQUITO CULEX PIPIENS

Gene duplications have long been advocated to contribute to the evolution of new functions. The role of selection in their early spread is more controversial. Unless duplications are favored for a direct benefit of increased expression, they are likely detrimental. In this article, we investigated the case of duplications favored because they combine already functionally divergent alleles. Their gene‐dosage/fitness relations are poorly known because selection may operate on both overall expression and duplicates relative dosage. Using the well‐documented case of Culex pipiens resistance to insecticides, we compared strains with various ace‐1 allele combinations, including two duplicated alleles carrying both susceptible and resistant copies. The overall protein activity was nearly additive, but, surprisingly, fitness correlated better with the relative proportion of susceptible and resistant copies rather than any absolute measure of activity. Gene dosage is thus crucial, duplications stabilizing a “heterozygote” phenotype. It corroborates the view that these were favored because they fix a permanent heterosis, thereby solving the irreducible trade‐off between resistance and synaptic transmission. Moreover, we showed that the contrasted successes of the two duplicated alleles in natural populations depend on genetic changes unrelated to ace‐1, confirming the probable implication of recessive sublethal mutations linked to structural rearrangements in some duplications.     

A novel chromosomal abnormality t (9;14)(p24;q13) in B-acute lymphoblastic leukemia

Acute lymphoblastic leukemia is a malignant disease of the bone marrow in which early lymphoid precursors proliferate and replace the normal hematopoietic cells of the marrow. We describe the clinical, morphologic, immunophenotypic and cytogenetic findings in the case of a 26-year-old man with B-lymphoblastic leukemia. Surface marker analysis revealed that they are positive for CD markers CD10, CD19, CD13, CD34, CD45 and HLA-DR, but negative for CD20, CD33, CD117 and CD11C markers. Cytogenetic analysis established a novel translocation, t (9;14)(p24;q13). Apart from this, spectral karyotyping revealed an additional translocation, t (6p; 14q). This is the first documented case of B-lymphoblastic leukemia with concurrent occurrence of both abnormalities. Further studies are needed to understand the role of this abnormality in carcinogenesis.     

Testing Equality between Two Diagnostic Procedures in Paired‐Sample Ordinal Data

When a new diagnostic procedure is developed, it is important to assess whether the diagnostic accuracy of the new procedure is different from that of the standard procedure. For paired‐sample ordinal data, this paper develops two test statistics for testing equality of the diagnostic accuracy between two procedures without assuming any parametric models. One is derived on the basis of the probability of correctly identifying the case for a randomly selected pair of a case and a non‐case over all possible cutoff points, and the other is derived on the basis of the sensitivity and specificity directly. To illustrate the practical use of the proposed test procedures, this paper includes an example regarding the use of digitized and plain films for screening breast cancer. This paper also applies Monte Carlo simulation to evaluate the finite sample performance of the two statistics developed here and notes that they can perform well in a variety of situations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hazard ratio estimation for two‐sample case under interval‐censored failure time data

This paper discusses two‐sample comparison in the case of interval‐censored failure time data. For the problem, one common approach is to employ some nonparametric test procedures, which usually give some p‐values but not a direct or exact quantitative measure of the survival or treatment difference of interest. In particular, these procedures cannot provide a hazard ratio estimate, which is commonly used to measure the difference between the two treatments or samples. For interval‐censored data, a few nonparametric test procedures have been developed, but it does not seem to exist as a procedure for hazard ratio estimation. Corresponding to this, we present two procedures for nonparametric estimation of the hazard ratio of the two samples for interval‐censored data situations. They are generalizations of the corresponding procedures for right‐censored failure time data. An extensive simulation study is conducted to evaluate the performance of the two procedures and indicates that they work reasonably well in practice. For illustration, they are applied to a set of interval‐censored data arising from a breast cancer study.     

Migration and Ethnobotanical Practices: The Case of <Emphasis Type="Italic">Tifey</Emphasis> Among Haitian Immigrants in Cuba

Ethnobotanical knowledge and practices are dynamic and they change as they are transferred and appropriated by people who are adapting to new surroundings and changing environments. Using tifey, a multispecies drink, as a case study, we discuss the changes that emigration brought about related to tifey, and the processes that determined these changes. Tifey is a Haitian drink prepared by soaking Artemisia absinthium and other plants in rum or aguardiente. It probably had its origin in the adoption of the absinthe-based liquor used by French settlers and troops during the colonial period. Haitians progressively added culturally relevant flavorings and medicinal plants to this drink, and differentiated its production and use for medicinal, medicinal food, ritual (religious and social), and economic purposes. When Haitians migrated to Cuba, they brought tifey with them, but over the course of the twentieth century its use declined and its composition changed due to sociocultural factors such as the dissolution of Haitian settlements, and to ecological factors such as difficulty in cultivation and/or procurement of A. absinthium in the new environment.     

Éléments d'une analyse sémiologique des gravures rupestres du Haut Atlas (vallée de l'Ourika, Maroc)

The semiological study of a set of rock engravings such as the one in the Haut Atlas would consist in studying the graphic elements within their context to determine their mutual relations, because such relations are meaningful. Some details could be signs to which we could attach a conventional meaning. But, being unable to identify these conventional signs by their meaning, we must look for similarities between the figures themselves. Indeed, the repetition of some relations will provide constitutive elements of the global meaning. Unfortunately, ignoring the relative positions of the figures, I can only give some indications about what such a study should entail. So, I focus on one hand on the attributes of the figures, which are, in any case, identity marks, and on the other hand, on the context of the figures, that is the graphics around the figure, in order to outline the likely semantic field and the actions, actual or symbolic, in which they are involved.     

Stochastic competitive exclusion in the maintenance of the naïve T cell repertoire

Recognition of antigens by the adaptive immune system relies on a highly diverse T cell receptor repertoire. The mechanism that maintains this diversity is based on competition for survival stimuli; these stimuli depend upon weak recognition of self-antigens by the T cell antigen receptor. We study the dynamics of diversity maintenance as a stochastic competition process between a pair of T cell clonotypes that are similar in terms of the self-antigens they recognise. We formulate a bivariate continuous-time Markov process for the numbers of T cells belonging to the two clonotypes. We prove that the ultimate fate of both clonotypes is extinction and provide a bound on mean extinction times. We focus on the case where the two clonotypes exhibit negligible competition with other T cell clonotypes in the repertoire, since this case provides an upper bound on the mean extinction times. As the two clonotypes become more similar in terms of the self-antigens they recognise, one clonotype quickly becomes extinct in a process resembling classical competitive exclusion. We study the limiting probability distribution for the bivariate process, conditioned on non-extinction of both clonotypes. Finally, we derive deterministic equations for the number of cells belonging to each clonotype as well as a linear Fokker-Planck equation for the fluctuations about the deterministic stable steady state.     

Resource‐allocation tradeoffs in caddisflies facing multiple stressors

The replacement of native forests by exotic tree monocultures, such as those of Eucalyptus, decreases the quality of leaf litter inputs to streams and often reduces riparian cover, which can elevate water temperature. The combined effects of these stressors on the survival and performance of detritivores may be important, as detritivore species loss leads to reduced litter breakdown, a key ecosystem process. Potential loss of cased caddisfly larvae is of particular concern because they are the predominant detritivores in many streams, they are sensitive to warming, and they expend energy on building and carrying their cases, which may be an added burden under times of stress. In a microcosm experiment, we tested whether (i) poor‐quality Eucalyptus globulus litter impaired case construction by larvae of Sericostoma pyrenaicum (due to preferential allocation of the scarcer available energy to larval fitness) compared to high‐quality Alnus glutinosa litter; (ii) whether this effect was enhanced by higher temperatures (15 vs. 10°C) resulting in faster metabolism and greater energy expenditure; but (iii) reduced in the presence of chemical cues from a predatory fish (due to greater investment in more protective cases). We found that Eucalyptus had lethal and sublethal effects on larval caddisflies, increasing mortality, reducing growth, and impairing case construction, compared to larvae fed Alnus. Temperature did not reinforce the effects of exotic litter on case construction, but predator chemical cues triggered the construction of more protective cases (i.e., longer and better cemented) despite the lower resource quality, providing evidence for environmentally mediated resource‐allocation tradeoffs.     

Computerized comparison of imaging in scintigraphy; physiopathological applications

The authors describe a method of treating scintigraphic data with which they can correctly compare images of a structure that were obtained in different conditions. This method comprises two steps which are fully computerized. During the first one known as the "registration" step and intended to make a comparison possible they maximise a new similarity criterion by a series of random trials in a five parameter space. During the second, which is the actual comparison, they use an appropriate statistical test to recognise those homologous pixels with a significantly different contents which will be the only ones retained to build up the final image. They give then two examples of what the method brings in the medical field which are the detection of adenomatous parathyroid glands and the follow-up of lung perfusion in case of embolism.     

Stepping beyond Sí Se Puede: Dichos as a Cultural Resource in Mother—Daughter Interaction in a Latino Family

This mother—daughter case study focuses on a key feature of discourse within a Mexican immigrant family that links oral traditions to resilience and motivation. I combine observations from a previous ethnographic study with recent follow-up interviews of a Mexican immigrant student building on a funds of knowledge framework and an ecological perspective. Expanding on current mother—daughter pedagogic theory, I map "dichos" as they are emblematic of cultural funds of knowledge and how they assume a relationship to resistance and academic attainment for a young Mexican immigrant. The findings challenge the notion that working-class Latino families do not care about the educational fortunes of their youth and lack knowledge and resources to guide their children academically.     

Spatio-ecological niche segregation of two sympatric species of<Emphasis Type="Italic">Clidemia (Melastomataceae)</Emphasis> in Western Amazonian non-flooded rainforests

The frequent occurrence of sympatric series of closely related plant species in tropical rainforests has evoked claims for and against the application of the competitive exclusion principle in these ecosystems. Narrow niche limits defined by biotic as well as abiotic specialization have been reported for sympatric species of the same genus or family. In Amazonian lowland rainforests this question deserves renewed attention because: (1) the existence of edaphically defined community types has recently been well established, and (2) spatio-ecological niche segregation of congeneric species may help explain not only the maintenance of the high Amazonian alpha-diversity, but also its origin through sympatric ecological speciation. In this study, the morphology, ecology, and distribution patterns of two species,Clidemia epiphytica andC. longifolia (Melastomataceae), from western Amazonia, were analyzed. The aims were to find out whether they really are two distinct taxonomic species and if so, whether they also can be considered biological species; if the species are sympatric; and if they are ecologically specialized. The results showed that the morphological variation of the species seems continuous, but that they exhibit opposite morphological responses to variation in soil cation concentration, which suggests that they also are separate biological species. Furthermore, the species occur sympatrically but in different habitats. It is suggested that a part of the enigma of sympatric congeners in rainforests may be explainable by spatial segregation stemming from ecological specialization in relation to subtle environmental variation. It is hypothesized that the studied species are a good candidate case of sympatric speciation driven by ecological specialization.     

Les assemblages lithiques des niveaux du Paléolithique moyen de l’Abri des Pêcheurs (Ardèche, Sud-Est de la France): Des occupations néandertaliennes récurrentes dans un « fossé »

The Abri des Pêcheurs has yielded an extraordinary sequence with Middle and Upper Palaeolithic levels. Humans came and stayed in a ditch-cave that has been filled in along time. During Middle Palaeolithic occupations, they used first quartz, and this site is the only case in this area. Assemblages show similar technological behaviour along time. Flint is few employed and arrived as flakes from different areas if we consider its geological variety. Functions of the site are not well established. The base of the sequence has yielded sediments with a mixing of ibex, carnivore bones and artefacts. The study of the lithic assemblages brings information on the processing systems used on quartz and flint during occupations which left few evidence and used local stones while flint is available not far from the site. Hypothesis on short and specialized occupations is discussed.     

Hemangiomas; histologic structure,and treatment

Hemangiomas are considered tumors originating in blood vessels and are classified as ectatic and hyperplastic. Controversy regarding active therapy occurs in the case of strawberry hemangiomas which are hyperplastic capillary hemangiomas. Although they may clear up spontaneously, on rare occasions they may predispose to grave sequelae. Port-wine stain hemangiomas should never be treated with x-ray or radium.     

Richard Meinertzhagen—a case of fraud examined

Museum collections are rich repositories of information. The specimens and the data they bear continue to provide new insights into ornithology and biological processes decades or even centuries after they were collected. The benefits to be gained from museum collections depend implicitly upon the accuracy of the information associated with the specimens and the correct interpretation of those data (Parkes 1989, Knox & Walters 1992). Collectors and dealers have often been suspected of fabricating data for a variety of reasons, but proven cases have been documented only rarely (e.g. Nicholson & Ferguson-Lees 1962). This paper examines one such case.     

A Parametric ROC Model‐Based Approach for Evaluating the Predictiveness of Continuous Markers in Case–Control Studies

Summary The predictiveness curve shows the population distribution of risk endowed by a marker or risk prediction model. It provides a means for assessing the model's capacity for stratifying the population according to risk. Methods for making inference about the predictiveness curve have been developed using cross‐sectional or cohort data. Here we consider inference based on case–control studies, which are far more common in practice. We investigate the relationship between the ROC curve and the predictiveness curve. Insights about their relationship provide alternative ROC interpretations for the predictiveness curve and for a previously proposed summary index of it. Next the relationship motivates ROC based methods for estimating the predictiveness curve. An important advantage of these methods over previously proposed methods is that they are rank invariant. In addition they provide a way of combining information across populations that have similar ROC curves but varying prevalence of the outcome. We apply the methods to prostate‐specific antigen (PSA), a marker for predicting risk of prostate cancer.     

Tumeurs brunes disséminées : à propos d’un cas

We report a case of multiple brown tumours concerning a 46-year-old, operated for a parathyroid adenoma, who is presenting clinical and biological signs of hyperparathyroidism recurrence. Unusual features in this case were the disseminated distribution of brown tumour and the bone scan pseudo-metastatic aspect.     

Variability of cranial characters in acclimatized sable (<Emphasis Type="Italic">Martes zibellina</Emphasis>) populations

Comparative analysis of metric and nonmetric variations of the sable skull in autochthonous and acclimatized populations was performed. In acclimatized sables, the skull is larger than in sables of the same origin from the Baikal region; however, they are smaller than animals of the autochthonous population. In nonmetric cranial characters, in one case, sables acclimatized in the Ob region are similar to autochthonous animals; in the other, they are similar to sables from the Baikal region. During 40 years after introduction, the population groups of acclimatized sables acquired phenotypic differences from both autochthonous sables dwelling in similar conditions and animals from the Baikal region of the same origin as acclimatizants.     

Metazoan evolution–a new model

Within their limits of resolution, different methods to reveal biochemical evolution appear to give reliable results where they can be controlled, as in the case of the Vertebrata. Compounds such as cytochrome c, SS rRNA and globins yield closely comparable results, which further strengthens the reliability. When the methods are applied to biochemical data from as many metazoan phyla as possible, the result is a phylogenetic tree which contrasts in certain respects with phylogenetic trees based on comparative zoology data. Important conclusions seem to include the following: (1) many metazoan phyla appear to have branched off from a shared, very conservative spiralian/protostome ancestral stock through the adoption of basically new feeding and locomotory strategies; (2) this origination makes it almost impossible to use a comparative zoology approach to solve problems of interphylum (in contrast to intraphylum) affinities, as similarities tend to be due only to shared derived Characters and similar life strategies, while dissimilarities are due to different basic life strategies; (3) protostome characters constitute a synapomorphy for triploblastic metazoans, and where absent they are secondarily lost, which means that protostome and deuterostome characters are irregularly distributed and mixed; (4) true deuterostomes form a sister group of the Mollusca, and they are only a top branch of the evolutionary tree.