The cell polarity determinant Dlg1 facilitates epithelial invagination by promoting tissue-scale mechanical coordination.

Epithelial folding mediated by apical constriction serves as a fundamental mechanism to convert flat epithelial sheets into multilayered structures. It remains unknown whether additional mechanical inputs are required for apical constriction-mediated folding. Using Drosophila mesoderm invagination as a model, we identified an important role for the non-constricting, lateral mesodermal cells adjacent to the constriction domain ('flanking cells') in facilitating epithelial folding. We found that depletion of the basolateral determinant Dlg1 disrupts the transition between apical constriction and invagination without affecting the rate of apical constriction. Strikingly, the observed delay in invagination is associated with ineffective apical myosin contractions in the flanking cells that lead to overstretching of their apical domain. The defects in the flanking cells impede ventral-directed movement of the lateral ectoderm, suggesting reduced mechanical coupling between tissues. Specifically disrupting the flanking cells in wild-type embryos by laser ablation or optogenetic depletion of cortical actin is sufficient to delay the apical constriction-to-invagination transition. Our findings indicate that effective mesoderm invagination requires intact flanking cells and suggest a role for tissue-scale mechanical coupling during epithelial folding.

A multi-scale model for hair follicles reveals heterogeneous domains driving rapid spatiotemporal hair growth patterning.

The control principles behind robust cyclic regeneration of hair follicles (HFs) remain unclear. Using multi-scale modeling, we show that coupling inhibitors and activators with physical growth of HFs is sufficient to drive periodicity and excitability of hair regeneration. Model simulations and experimental data reveal that mouse skin behaves as a heterogeneous regenerative field, composed of anatomical domains where HFs have distinct cycling dynamics. Interactions between fast-cycling chin and ventral HFs and slow-cycling dorsal HFs produce bilaterally symmetric patterns. Ear skin behaves as a hyper-refractory domain with HFs in extended rest phase. Such hyper-refractivity relates to high levels of BMP ligands and WNT antagonists, in part expressed by ear-specific cartilage and muscle. Hair growth stops at the boundaries with hyper-refractory ears and anatomically discontinuous eyelids, generating wave-breaking effects. We posit that similar mechanisms for coupled regeneration with dominant activator, hyper-refractory, and wave-breaker regions can operate in other actively renewing organs.

Frecuencia de parasitos intestinales y características epidemiológicas de la población infantil de 1 a 12 años que consulta al ambulatorio urbano tipo II de Cerro Gordo, Barquisimeto, estado Lara: enero-junio 2007 / Frequence of intestinal parasitism and epidemiological characteristics of the 1 to 12 year-old child population treated at the Cerro Gordo type II urban outpatient clinic, Barquisimeto, state Lara: january-june 2007

El objetivo de esta investigación fue determinar la frecuencia de parasitosis intestinales en el área de influencia del Ambulatorio Urbano Tipo II de Cerro Gordo, Barquisimeto, Estado Lara, realizando un estudio descriptivo transversal. Se evaluaron 106 niños entre 1 y 12 años de edad, realizando a cada uno examen de heces directo y concentrado con la técnica de Ritchie, demostrándo se parasitosis intestinal en 42,5%, predominando en escolares (48,9%), sin diferencias según el género. El agente más frecuente fue B. hominis (42,2%), seguido de G. lamblia (37,8%), Complejo Entamoeba histolytica/Entamoeba dispar (13,3%), H. nana (11,1%) y A. lumbricoides (4,4%). Se encontró parasitado 41,7% de niños con estado nutricional normal y 35,7% de malnutridos. La presencia de parasitos intestinales mostró relación con la disposición inadecuada de basura (p=0.048). El lavado inadecuado de las manos se relacionó con prurito anal (p=0.008). La calidad inadecuada del agua se relacionó con Blastocistosis (p= 0,025) y comensales (p= 0,035). No hubo relación entre parasitosis intestinales y síntomas gastrointestinales, estrato social, disposición de excretas, presencia de vectores en el hogar, lavado y conservación de alimentos, frecuencia de recolección de basura, lavado de manos, antecedente de tratamiento antiparasitario y familiar parasitado

A cross-sectional study was conducted to determine intestinal parasitism in children treated at the “Cerro Gordo” Type II Urban Outpatient Clinic in Barquisimeto, Lara. Feces samples were collected from 106 children (1-12 years old) and analyzed using both direct and Ritchie´s technique analyses, demonstrating intestinal parasitism in 42.5% of the children, predominantly of school age (48.9%), but independent of gender. The most frequent agent was Blastocystis hominis (42.2%), followed by Giardia lamblia (37.8%), Entamoeba histolytica/Entamoeba dispar Complex (13.3%), Hymenolepis nana (11.1%) and Ascaris lumbricoides (4.4%). For children with a normal nutritional condition, 41.7% had parasites, while this value was 35.7% for nutritionally undernourished children. The presence of intestinal parasites showed relations to the community’s trash collection management program status (p=0.048). Poor hand washing habits were significantly associated with anal pruritus (p=0.008). Inadequate water quality was related to blastocystosis (p= 0.025) and comensals (p= 0.035). The presence of parasites was not associated with specific gastrointestinal symptoms, socioeconomic status, disposition of excreta, presence of vectors in the home, food washing and storage, frequency of garbage collection, washing of hands, family parasitism history and anti-parasite treatment antecedents