Evolution of New cis-Regulatory Motifs Required for Cell-Specific Gene Expression in Caenorhabditis

Patterning of C. elegans vulval cell fates relies on inductive signaling. In this induction event, a single cell, the gonadal anchor cell, secretes LIN-3/EGF and induces three out of six competent precursor cells to acquire a vulval fate. We previously showed that this developmental system is robust to a four-fold variation in lin-3/EGF genetic dose. Here using single-molecule FISH, we find that the mean level of expression of lin-3 in the anchor cell is remarkably conserved. No change in lin-3 expression level could be detected among C. elegans wild isolates and only a low level of change-less than 30%-in the Caenorhabditis genus and in Oscheius tipulae. In C. elegans, lin-3 expression in the anchor cell is known to require three transcription factor binding sites, specifically two E-boxes and a nuclear-hormone-receptor (NHR) binding site. Mutation of any of these three elements in C. elegans results in a dramatic decrease in lin-3 expression. Yet only a single E-box is found in the Drosophilae supergroup of Caenorhabditis species, including C. angaria, while the NHR-binding site likely only evolved at the base of the Elegans group. We find that a transgene from C. angaria bearing a single E-box is sufficient for normal expression in C. elegans. Even a short 58 bp cis-regulatory fragment from C. angaria with this single E-box is able to replace the three transcription factor binding sites at the endogenous C. elegans lin-3 locus, resulting in the wild-type expression level. Thus, regulatory evolution occurring in cis within a 58 bp lin-3 fragment, results in a strict requirement for the NHR binding site and a second E-box in C. elegans. This single-cell, single-molecule, quantitative and functional evo-devo study demonstrates that conserved expression levels can hide extensive change in cis-regulatory site requirements and highlights the evolution of new cis-regulatory elements required for cell-specific gene expression

Alternative Sources of Financing and the Sustainability of Cameroonian Start-ups

The objective of the paper is to assess the contribution of alternative sources of financing to the survival of SMIs through an analysis of start-ups in Cameroon. Our study employs a qualitative multisite case study methodology. Data was collected from both documentary and primary sources. For the primary data, we conducted semidirected interviews with five start-ups operating in four fields of activity (agriculture, health, finance and ICTs) to assess in depth the behaviour of various promoters who have received alternative financing at least once. The results of our manual and automated analysis led to two major findings: firstly, it is possible to identify alternative financing in the environment of Cameroonian start-ups in the form of social capital (help from loved ones, support from elites and families, community fundraisers, tontines) on the one hand, and crowdfunding on the other. Secondly, these two means of alternative financing are significant sources of added value for the survival of start-ups not only through the preparation and precreation activities (social capital) but as important levers in improving the organizational strategies of start-ups (fundraising among individuals and the possibility of marketing through platforms)

Unconditional security at a low cost

By simulating four quantum key distribution (QKD) experiments and analyzing one decoy-state QKD experiment, we compare two data post-processing schemes based on security against individual attack by L\"{u}tkenhaus, and unconditional security analysis by Gottesman-Lo-L\"{u}tkenhaus-Preskill. Our results show that these two schemes yield close performances. Since the Holy Grail of QKD is its unconditional security, we conclude that one is better off considering unconditional security, rather than restricting to individual attacks.Comment: Accepted by International Conference on Quantum Foundation and Technology: Frontier and Future 2006 (ICQFT'06

Quand les lettrés chinois rencontrent la civilisation moderne : le monde méditerranéen dans les écrits chinois à la fin de la dynastie des Qing (fin xixe - début xxe siècle)

À la fin de la dynastie des Qing, entre les années 1860 et 1900, les voyageurs chinois ont traversé la Méditerranée à destination de l’Europe pour des missions diplomatiques ou des voyages personnels. Ces lettrés confucéens, soucieux de l’avenir de l’Empire du Milieu en pleine crise, ont découvert la modernité dans le monde méditerranéen et ont commencé par conséquent à réfléchir sur la modernisation chinoise en se référant aux éléments historiques, culturels ou modernes des pays de la région. Leurs récits de voyage en Égypte, en Italie ou encore en Grèce montrent en fait la complexité de leur pensée face aux tensions entre modernité occidentale et tradition chinoise. C’est à partir de ces réflexions qu’ils ont cherché à moderniser la politique chinoise et à construire une identité moderne de la nation.In the late Qing period, between the 1860s and 1900s, Chinese travelers crossed the Mediterranean to Europe for diplomatic missions or personal trips. These Confucian scholars, who were concerned about the future of the Middle Kingdom in crisis, discovered modernity in the Mediterranean world and therefore reflected on the Chinese modernisation by referring to the historical, cultural or modern elements of the countries of this region. In fact, their travel notes in Egypt, Italy and Greece, show the complexity of their thinking about the tensions between Western modernity and Chinese tradition. From these reflections, they sought to modernise Chinese politics and build a modern identity of the nation

Anchor cell signaling and vulval precursor cell positioning establish a reproducible spatial context during C. elegans vulval induction

How cells coordinate their spatial positioning through intercellular signaling events is poorly understood. Here we address this topic using Caenorhabditis elegans vulval patterning during which hypodermal vulval precursor cells (VPCs) adopt distinct cell fates determined by their relative positions to the gonadal anchor cell (AC). LIN-3/EGF signaling by the AC induces the central VPC, P6.p, to adopt a 1° vulval fate. Exact alignment of AC and VPCs is thus critical for correct fate patterning, yet, as we show here, the initial AC-VPC positioning is both highly variable and asymmetric among individuals, with AC and P6.p only becoming aligned at the early L3 stage. Cell ablations and mutant analysis indicate that VPCs, most prominently 1° cells, move towards the AC. We identify AC-released LIN-3/EGF as a major attractive signal, which therefore plays a dual role in vulval patterning (cell alignment and fate induction). Additionally, compromising Wnt pathway components also induces AC-VPC alignment errors, with loss of posterior Wnt signaling increasing stochastic vulval centering on P5.p. Our results illustrate how intercellular signaling reduces initial spatial variability in cell positioning to generate reproducible interactions across tissues

The worm in the world and the world in the worm

Caenorhabditis elegans is a preeminent model organism, but the natural ecology of this nematode has been elusive. A four-year survey of French orchards published in BMC Biology reveals thriving populations of C. elegans (and Caenorhabditis briggsae) in rotting fruit and plant stems. Rather than being simply a 'soil nematode', C. elegans appears to be a 'plant-rot nematode'. These studies signal a growing interest in the integrated genomics and ecology of these tractable animals

Palatosquisis en la especie canina

La palatosquisis o paladar secundario hendido es una de las anomalías congénitas más corrientes que presentan los cachorros alnacimiento. Se describen las técnicas más habituales de corrección y la utilizada por los autores.Paiaiosquisis or secondary cleft palate is one of the most frequent congenital abnormalities shown by newborn pups. Commonly used correction techniques and that used by the authors are described

Displasia de cadera en el perro : estado actual

La displasia de cadera en el perro es una patología que se presenta con relativa frecuencia en la clínica de pequeños animales. Si bien su diagnóstico es sencillo cuando la lesión ya se encuentra en una fase avanzada, en ocasiones no lo es tanto cuando aquélla se encuentra en una fase inicial en la que tanto los signos clínicos como los radiológicos no son demasiado evidentes. La importancia de realizar un diagnóstico precoz, así como la elección de la técnica quirúrgica más adecuada en cada caso, son aspectos fundamentales para poder asegurar el mejor pronóstico. En el presente trabajo se repasan los distintos aspectos de la enfermedad.Canine hip dysplasia is a relatively common problem in small animal practice. Although its diagnosis is easy in an advanced stage, it becomes harder in earlier stages when clinical signs and radiological features are not so evident. The early diagnosis, as well as the most convenient surgical technique selection, are the key points to ensure the best prognosis. This paper reviews the different aspects of hip dysplasia

Hemangiosarcoma pulmonar primario en un Pastor Alemán con neumotórax espontáneo

Se describe un caso clínico de un hemangiosarcoma (HSA) primario pulmonar, en un pastor alemán, evaluado por un cuadro agudo de disnea asociado a un neumotórax espontáneo.

Miositis eosinofílica en el perro : caso clínico

Se presentó en la consulta de la Facultad un perro Pastor Alemán, con una sintomatologia de intensa atrofia muscular que afectaba a los músculos maseteros y temporales, e imposibilidad de apertura de boca. Se realizó un protocolo habitual de diagnóstico, completando la historia clínica. examen delpaciente y la analítica histopatológica y hematológica. Los resultados obtenidos contrastados con la bibliografía disponible, nos hizo llegar finalmente al diagnóstico de Miositis Canina.A German sheperd dog arrived to the Veterinary Hospital of our University with an intensive muscular atrophy of the masticatory muscles. As it is usual, the protocol of diagnostic was made; the anamnesis, clinical history, and animal examination was reviewied, to follow with the haemathologic and histopathologic studies. Finally we obtained a diagnostic of Canine Miositis