Independent fusions and recent origins of sex chromosomes in the evolution and diversification of glass knife fishes (Eigenmannia)

The genus Eigenmannia comprises several species groups that display a surprising variety of diploid chromosome numbers and sex-determining systems. In this study, hypotheses regarding phylogenetic relationships and karyotype evolution were investigated using a combination of molecular and cytogenetic methods. Phylogenetic relationships were analyzed for 11 cytotypes based on sequences from five mitochondrial DNA regions. Parsimony-based character mapping of sex chromosomes confirms previous suggestions of multiple origins of sex chromosomes. Molecular cytogenetic analyses involved chromosome painting using probes derived from whole sex chromosomes from two taxa that were hybridized to metaphases of their respective sister cytotypes. These analyses showed that a multiple XY system evolved recently (<7 mya) by fusion. Furthermore, one of the chromosomes that fused to form the neo-Y chromosome is fused independently to another chromosome in the sister cytotype. This may constitute an efficient post-mating barrier and might imply a direct function of sex chromosomes in the speciation processes in Eigenmannia. The other chromosomal sex-determination system investigated is shown to have differentiated by an accumulation of heterochromatin on the X chromosome. This has occurred in the past 0.6 my, and is the most recent chromosomal sex-determining system described to date. These results show that the evolution of sex-determining systems can proceed very rapidly. Heredity (2011) 106, 391-400; doi:10.1038/hdy.2010.82; published online 23 June 2010

Sex ratio and morphological characteristics of Rufous Gnateaters, Conopophaga lineata (Aves, Passeriformes) in Atlantic forest fragments

Unequal sex ratios lead to the loss of genetic variability, decreasing the viability of populations in the long term. Anthropogenic activities often disturb the natural habitats and can cause alterations in sex ratio and morphological characteristics of several species. Forest fragmentation is a major conservation concern, so that understanding its effects in natural populations is essential. In this study, we evaluated the sex ratio and the morphological characteristics of Rufous Gnateaters (Conopophaga lineata (Wied, 1831)) in small and large forest fragments in Minas Gerais, Brazil. Birds (n = 89) were sexed by plumage characteristics and molecular markers. The molecular analysis showed that plumage is not a totally reliable method for sexing Rufous Gnateaters. We observed that sex ratio did not differ between large and small forest fragments, but birds in small fragments had larger wings and tarsus. Wing and tarsus changes may affect the movement ability of individuals within and among forest fragments. In conclusion, Rufous Gnateaters have been able to survive in both small and large Atlantic rain forest fragments without altering their sex ratio, but morphological changes can be prejudicial to their long term survival.

Sexual System, Sex Ratio, and Group Living in the Shrimp Thor amboinensis (De Man): Relevance to Resource-Monopolization and Sex-Allocation Theories

The sexual system of the symbiotic shrimp Thor amboinensis is described, along with observations on sex ratio and host-use pattern of different populations. We used a comprehensive approach to elucidate the previously unknown sexual system of this shrimp. Dissections, scanning electron microscopy, size-frequency distribution analysis, and laboratory observations demonstrated that T amboinensis is a protandric hermaphrodite: shrimp first mature as males and change into females later in life. Thor amboinensis inhabited the large and structurally heterogeneous sea anemone Stichoclactyla helianthus in large groups (up to 11 individuals) more frequently than expected by chance alone. Groups exhibited no particularly complex social structure and showed male-biased sex ratios more frequently than expected by chance alone. The adult sex ratio was male-biased in the four separate populations studied, one of them being thousands of kilometers apart from the others. This study supports predictions central to theories of resource monopolization and sex allocation. Dissections demonstrated that unusually large males were parasitized by an undescribed species of isopod (family Entoniscidae). Infestation rates were similarly low in both sexes (approximate to 11%-12%). The available information suggests that T. amboinensis uses pure search promiscuity as a mating system. This hypothesis needs to be formally tested with mating behavior observations and field measurements on the movement pattern of both sexes of the species. Further detailed studies on the lifestyle and sexual system of all the species within this genus and the development of a molecular phylogeny are necessary to elucidate the evolutionary history of gender expression in the genus Thor.

Do individuals in better condition survive for longer? Field survival estimates according to male alternative reproductive tactics and sex

There is a gap in terms of the supposed survival differences recorded in the field according to individual condition. This is partly due to our inability to assess survival in the wild. Here we applied modern statistical techniques to field-gathered data in two damselfly species whose males practice alternative reproductive tactics (ARTs) and whose indicators of condition in both sexes are known. In Paraphlebia zoe, there are two ART: a larger black-winged (BW) male which defends mating territories and a smaller hyaline-winged (HW) male that usually acts as a satellite. In this species, condition in both morphs is correlated with body size. In Calopteryx haemorrhoidalis, males follow tactics according to their condition with males in better condition practicing a territorial ART. In addition, in this species, condition correlates positively with wing pigmentation in both sexes. Our prediction for both species was that males practicing the territorial tactic will survive less longer than males using a nonterritorial tactic, and larger or more pigmented animals will survive for longer. In P. zoe, BW males survived less than females but did not differ from HW males, and not necessarily larger individuals survived for longer. In fact, size affected survival but only when group identity was analysed, showing a positive relationship in females and a slightly negative relationship in both male morphs. For C. haemorrhoidalis, survival was larger for more pigmented males and females, but size was not a good survival predictor. Our results partially confirm assumptions based on the maintenance of ARTs. Our results also indicate that female pigmentation, correlates with a fitness component - survival - as proposed by recent sexual selection ideas applied to females.

First molecular estimate of sex-ratio of southern right whale calves, Eubalaena australis, for Brazilian waters

The southern right whale (Eubalaena australis) was one of the most intensively hunted whales between the 17th and 20th centuries in the southern hemisphere. Recent estimates indicate that today there are around 7000 whales, representing 5 to 10% Of its original population. On the other hand, recent studies estimated that the population that migrates to the Brazilian coast grew by 14% from 1987 to 2003. However, there is no information about sex-ratio for adults or for calves in this region, which is an important parameter for understanding the biology of the species. We present here the first estimate Of calves` sex-ratio of southern right whales found along the southern Brazilian coast, one of the most important wintering grounds for the species. Sex was molecularly indentified for 21 biopsies collected from calves between 1998 and 2002, along the coast of Rio Grande do Sul and Santa Catarina States, in southern Brazil. The sex-ratio was two females for one male, however, it was not statistically different (chi(2) test, alpha = 0.05; df = 1) from the expected ratio of 1:1. This result is in accordance with the sex-ratio estimated for the species of all ages using external morphology (and behaviour in formation), (is well as for most species of baleen whales.

Extracellular Signal-Regulated Kinase 1/2 Activation, via Downregulation of Mitogen-Activated Protein Kinase Phosphatase 1, Mediates Sex Differences in Desoxycorticosterone Acetate-Salt Hypertension Vascular Reactivity

Extracellular signal-regulated kinase (ERK) 1/2 has been reported to play a role in vascular dysfunction associated with mineralocorticoid hypertension. We hypothesized that, compared with female rats, an upregulation of ERK1/2 signaling in the vasculature of male rats contributes to augmented contractile responses in mineralocorticoid hypertension. Uninephrectomized male and female Sprague-Dawley rats received desoxycorticosterone acetate (DOCA) pellets (200 mg per animal) and saline to drink for 3 weeks. Control uninephrectomized rats received tap water to drink. Blood pressure, measured by telemetry, was significantly higher in male DOCA rats (191 +/- 3 mm Hg) compared with female DOCA rats (172 +/- 7 mm Hg; n=5). DOCA treatment resulted in augmented contractile responses to phenylephrine in aorta (22 +/- 3 mN; n=6) and small mesenteric arteries (13 +/- 2 mN; n=6) from male DOCA rats versus uninephrectomized male rats (16 +/- 3 and 10 +/- 2 mN, respectively; P<0.05) and female DOCA rats (15 +/- 1 and 11 +/- 1 mN, respectively). ERK1/2 inhibition with PD-98059 (10 mu mol/L) abrogated increased contraction to phenylephrine in aorta (14 +/- 2 mN) and small mesenteric arteries (10 +/- 2 mN) from male DOCA rats, without any effects in arteries from male uninephrectomized or female animals. Compared with the other groups, phosphorylated ERK1/2 levels were increased in the aorta from male DOCA rats, whereas mitogen-activated protein kinase phosphatase 1 expression was decreased. Interleukin-10 plasma levels, which positively regulate mitogen-activated protein kinase phosphatase 1 activity, were reduced in male DOCA-salt rats. We speculate that augmented vascular reactivity in male hypertensive rats is mediated via activation of the ERK1/2 pathway. In addition, mitogen-activated protein kinase phosphatase 1 and interleukin 10 play regulatory roles in this process. (Hypertension. 2010; 55: 172-179.)

Differential effects of female sex hormones on cellular recruitment and tracheal reactivity after formaldehyde exposure

Female sex hormones (FSHs) exert profound regulatory effects on the course of lung inflammation due to allergic and non-allergic immune responses. As pollution is one of the pivotal factors to induce lung dysfunction, in this study we investigated the modulatory role of FSHs on lung inflammation after a formaldehyde (FA) exposure. For this purpose, lung and systemic inflammatory responses were evaluated in terms of leukocytes countings in bronchoalveolar lavage (BAL), peripheral blood and bone marrow lavage from 7-day ovariectomized (OVx) and Sham-OVx rats subjected to FA inhalation for 3 consecutive days. The hypothesized link between effects of FSHs on expression of adhesion molecules and mast cells degranulation was also studied. Once exposed to FA, Sham-OVx rats increased the number of total cells recovered in BAL and of leukocytes in peripheral blood, and decreased the counts in bone marrow. By contrast, in OVx rats upon FA exposure there was a reduction of the total cells counts in BAL and of blood leukocytes: lung expressions of ICAM-1 and Mac-1 were depressed, but the number of bone marrow cells did not vary. Estradiol treatment of OVx rats increased the total cells in BAL and decreased the number of blood leukocytes, whereas the number of bone marrow cell remained unaltered. Progesterone treatment, in turn increased the total cells in BAL and blood leukocytes, but decreased the number of bone marrow cells. OVx rats exposed to FA developed tracheal hyperresponsiveness to methacholine (MCh). A similarly altered response was found between the tracheal segments of Sham-OVx rats after FA exposure and that found in tracheae of naive rats. Estradiol treatment prevented FA-induced tracheal hyperresponsiveness to MCh whereas progesterone was ineffective in this regard. In addition, OVx rats upon FA exposure significantly increased both, the ability of mast cell degranulation and serum corticosterone levels. In conclusion, it was found that FSHs act by distinct control mechanisms on FA-induced lung inflammation and tracheal hyperresponsiveness, since at low circulating levels of FSHs (such as those after OVx) there is some resistance to the development of a lung inflammatory response, but the cholinergic tracheal responsiveness is exacerbated. Our data also help to understand the involvement of FSHs on mast cells activity after pollutants exposure and add information regarding the role of FSHs on the mechanisms related to endothelium-leukocyte interactions. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Conservation laws and tachyon potentials in the sliver frame

Conservation laws have provided an elegant and efficient tool to evaluate the open string field theory interaction vertex, they have been originally implemented in the case where the string field is expanded in the Virasoro basis. In this work we derive conservation laws in the case where the string field is expanded in the so-called sliver L(0)-basis. As an application of this new set of conservation laws, we compute the open string field action relevant to the tachyon condensation and in order to present not only an illustration but also an additional information, we evaluate the action without imposing a gauge choice.

ENO adaptive method for solving one-dimensional conservation laws

In this work an efficient third order non-linear finite difference scheme for solving adaptively hyperbolic systems of one-dimensional conservation laws is developed. The method is based oil applying to the solution of the differential equation an interpolating wavelet transform at each time step, generating a multilevel representation for the solution, which is thresholded and a sparse point representation is generated. The numerical fluxes obtained by a Lax-Friedrichs flux splitting are evaluated oil the sparse grid by an essentially non-oscillatory (ENO) approximation, which chooses the locally smoothest stencil among all the possibilities for each point of the sparse grid. The time evolution of the differential operator is done on this sparse representation by a total variation diminishing (TVD) Runge-Kutta method. Four classical examples of initial value problems for the Euler equations of gas dynamics are accurately solved and their sparse solutions are analyzed with respect to the threshold parameters, confirming the efficiency of the wavelet transform as an adaptive grid generation technique. (C) 2008 IMACS. Published by Elsevier B.V. All rights reserved.

Lärares yrkesetiska principer : Fenomenografisk studie kring sex gymnasielärares uppfattningar om principernas syfte, applicerbarhet och diskursaktualitet

Undersökningens syfte är att med hjälp av intervjuer redovisa sex gymnasielärares uppfattningar om deras yrkesetiska principer. Fokus ligger på principernas syfte, diskursaktualitet och applicerbarhet. Resultatet visar att lärarna ser yrkesetiken som ett förhållningssätt samt en del i status- och professionsfrågan. Diskursaktualiteten uppfattas som frånvarande på den aktuella skolan, men intresse för större aktivitet önskas hos några av dem. Yrkesetikens applicerbarhet anses som relativt god, men att problem finns.

Sex pedagogers uppfattningar om och hur de använder lek för barnens lärande och utveckling

De flesta lekforskare är eniga om att barn lär sig när de leker och att lek har betydelse för barns utveckling. Syftet med denna undersökning var att studera vilka uppfattningar pedagoger har om lek och hur de använder lek för barns lärande i undervisningen i sina tre förskoleklasser. I studien intervjuades sex pedagoger, två barnskötare, två förskollärare och två fritidspedagoger. Resultatet visade att pedagogerna uppfattar lek som viktig för barnens lärande och utveckling och att den använder sig av både fria och styrda lekar i undervisningen.

Lek, lärande och utveckling : Sex pedagogers syn på lekens betydelse för förskolebarns utveckling och lärande

Syftet med studien är att undersöka hur pedagoger använder sig av leken i sin verksamhet och vad de har för syn på lekens betydelse för förskolebarns lärande och utveckling. Studien bygger på litteratur om tidigare forskning kring lek samt kvalitativa intervjuer med sex pedagoger verksamma inom förskola och förskoleklass. Resultatet av vår studie visar att både pedagogerna och de forskare vi tagit del av anser att leken är en viktig bit av barns lärande och utveckling. Pedagogerna lyfter fram leken som barnens arbetsredskap och poängterar hur viktigt det är att skapa goda förutsättningar för lek. De använder leken på ett medvetet sätt i sin verksamhet och är eniga om att begreppen lek, lärande och utveckling är sammanhängande och inte går att skilja åt. Studien visar att leken mestadels ses som god och befrämjande men också att leken har en baksida som enligt pedagogerna kan innehålla inslag av maktutövande och förtryck.

Tillträdes- och uteslutningsstrategier i den fria leken : En undersökning gjord i förskolan bland barn i åldrarna tre till sex år

Syftet med det här arbetet har varit att undersöka hur barn i åldrarna tre-sex år skapar, upp-rätthåller och avbryter gemenskaper med varandra i den fria leken på förskolan. Jag har också tittat på det hela ur ett genusperspektiv och har tittat på om pojkar och flickor agerar på olika sätt när det gäller tillträden samt exkluderingar i den fria leken. Som metod har jag använt mig av observationer, jag antecknade och gjorde röstinspelningar för att fånga så mycket som möjligt av det barnen sade och gjorde. Jag genomförde 27 obser-vationer både inomhus och utomhus.Resultatet visade att pojkar och flickor använder sig av många olika strategier för att få tillträ-de till pågående lek och för att utesluta varandra under pågående lek.De vanligaste tillträdesstrategierna som barnen under mina observationer använde sig av var: att fråga om man fick delta i leken, att avbryta eller använda sig av en störande entré för att få tillträde till leken, att leka bredvid några andra som leker och själv leka liknande lek som dem samt att referera till någon vuxens auktoritet. När det kommer till uteslutningsstrategier så var de vanligaste: att etablera en kärngrupp, att ha en roll i leken men ändå bli utestängd, uteslutningar av kamrater inom pågående lek, att skydda interaktionsutrymmet och uteslutning på grund av ålder.Användandet av tillträdes- och uteslutningsstrategier ur genushänseende visade att flickorna oftast frågade om de fick vara med i en pågående lek eller refererade till frasen alla får vara med. Pojkarna använde sig mest av avbrytande och störande entré och till viss del, men inte i lika stor utsträckning som flickorna, av frasen alla får vara med.

Sex, a one mans show : Perceptions and experience of sexuality, contraceptives, unwanted pregnancy and unsafe abortion among young people in Kisumu, Kenya – A qualitative study

This study aimed to explore perceptions and experiences concerning sexuality, contraceptives, unwanted pregnancy and unsafe abortion among young people in Kisumu, Kenya. The design of the study was inductive with a qualitative approach using personal in-depth interviews. Eight participants (four female and four male) were asked to describe their perceptions and experience concerning sexuality, contraceptives, unwanted pregnancies and unsafe abortion. The result showed that culture and norms, misconceptions and gender based power in sexuality are factors that impact Sexual Reproductive Health among young people in Kisumu today. Unwanted pregnancy was described as a shame, a burden and a destroyed life which lead to many unsafely induced abortions. The findings indicate that youth interventions are important, such as engaging young men in unwanted pregnancy and thus unsafe abortions and to empower young women.

Individualisering i moderna språk : En kvalitativ studie om hur sex lärare i moderna språk förhåller sig till individualisering i undervisningen

Syftet med studien är att undersöka hur sex lärare i moderna språk förhåller sig till individualisering i undervisningen. Metoden som använts är kvalitativa forskningsintervjuer med språklärare verksamma inom såväl grundskolan som gymnasiet. Undersökningens resultat åskådliggör en mångfald av tolkningar kring individualiseringsuppdraget hos lärare i moderna språk. Utifrån informanternas svar identifieras tre skilda individualiseringsmodeller. I den första modellen framstår individualiseringen framförallt som en metod baserad på nivåindelning och användande av särskilt material. Individualisering beskrivs i den andra modellen som ett förhållningssätt, att beakta elevernas olikhet, och utformas under en rad olika inslag, från planering till utvärdering. I den tredje modellen nås individualisering i helklassundervisning genom varierande arbetsformer samt lärarens kontakt med eleverna under lektionen. Att läraren snarare ansluter sig till en av dessa tre modeller tycks hänga samman med vilka behov och risker denne förknippar med individualisering.