Lens placode modulates extracellular matrix formation during early eye development.

The role extracellular matrix (ECM) in multiple events of morphogenesis has been well described, little is known about its specific role in early eye development. One of the first morphogenic events in lens development is placodal thickening, which converts the presumptive lens ectoderm from cuboidal to pseudostratified epithelium. This process occurs in the anterior pre-placodal ectoderm when the optic vesicle approaches the cephalic ectoderm and is regulated by transcription factor Pax6 and secreted BMP4. Since cells and ECM have a dynamic relationship of interdependence and modulation, we hypothesized that the ECM evolves with cell shape changes during lens placode formation. This study investigates changes in optic ECM including both protein distribution deposition, extracellular gelatinase activity and gene expression patterns during early optic development using chicken and mouse models. In particular, the expression of Timp2, a metalloprotease inhibitor, corresponds with a decrease in gelatinase activity within the optic ECM. Furthermore, we demonstrate that optic ECM remodeling depends on BMP signaling in the placode. Together, our findings suggest that the lens placode plays an active role in remodeling the optic ECM during early eye development.

Characterization of embryonic surface ectoderm cell protrusions.

BACKGROUND: During embryonic development, complex changes in cell behavior generate the final form of the tissues. Extension of cell protrusions have been described as an important component in this process. Cellular protrusions have been associated with generation of traction, intercellular communication or establishment of signaling gradients. Here, we describe and compare in detail from live imaging data the dynamics of protrusions in the surface ectoderm of chick and mouse embryos. In particular, we explore the differences between cells surrounding the lens placode and other regions of the head. RESULTS: Our results showed that protrusions from the eye region in mouse embryos are longer than those in chick embryos. In addition, protrusions from regions where there are no significant changes in tissue shape are longer and more stable than protrusions that surround the invaginating lens placode. We did not find a clear directionality to the protrusions in any region. Finally, we observed intercellular trafficking of membrane puncta in the protrusions of both embryos in all the regions analyzed. CONCLUSIONS: In summary, the results presented here suggest that the dynamics of these protrusions adapt to their surroundings and possibly contribute to intercellular communication in embryonic cephalic epithelia.

Lens Placode Modulates Extracellular Matrix Formation During Early Eye Development.

The role extracellular matrix (ECM) in multiple events of morphogenesis has been well described, little is known about its specific role in early eye development. One of the first morphogenic events in lens development is placodal thickening, which converts the presumptive lens ectoderm from cuboidal to pseudostratified epithelium. This process occurs in the anterior pre-placodal ectoderm when the optic vesicle approaches the cephalic ectoderm. Since cells and ECM have a dynamic relationship of interdependence and modulation, we hypothesized that the ECM evolves with cell shape changes during lens placode formation. This study investigates changes in optic ECM including both protein distribution deposition, extracellular gelatinase activity and gene expression patterns during early optic development using chicken and mouse models. In particular, the expression of Timp2 , a metalloprotease inhibitor, corresponds with a decrease in gelatinase activity within the optic ECM. Furthermore, we demonstrate that optic ECM remodeling depends on BMP signaling in the placode. Together, our findings suggest that the lens placode plays an active role in remodeling the optic ECM during early eye development.

Morphogenesis of the lens placode.

For over 100 years, the vertebrate eye has been an important model system to understand cell induction, cell shape change, and morphogenesis during development. In the past, most of the studies examined histological changes to detect the presence of induction mechanisms, but the advancement of molecular biology techniques has made exploring the genetic mechanisms behind lens development possible. Despite the particular emphasis given to the induction of the lens placode, there are still many aspects of the cell biology of lens morphogenesis to be explored. Here, we will revisit the classical detailed description of early lens morphological changes, correlating it with the cell biology mechanisms and with the molecules and signaling pathways identified up to now in chick and mouse embryos. A detailed description of lens development stages helps better understand the timeline of the events involved in early lens morphogenesis. We then point to some key questions that are still open.

[Occurrence of Trypanoxyuris (Trypanoxyuris) minutus (Schneider, 1866) (Nematoda, Oxyuridae) in Alouatta guariba clamitans Cabrera, 1940 (Primates, Atelidae) in Minas Gerais, Brazil]. / Ocorrência de Trypanoxyuris (Trypanoxyuris) minutus (Schneider, 1866) (Nematoda, Oxyuridae) em Alouatta guariba clamitans Cabrera, 1940 (Primates, Atelidae) em Minas Gerais, Brasil.

This study aims to register the occurrence of Trypanoxyuris (Trypanoxyuris) minutus in Alouatta guariba clamitans, in Minas Gerais state, Brazil. Two specimens of A. guariba clamitans, died accidentally, have been necropsied for parasitological studies. Only the large intestine and caecum were infected by T. minutus. The parasitism intensity was 6650 parasites and the density was 2.6 parasites/cm3 of large intestine. In the caecum, the mean intensity was 6753 +/- 490.73 parasites, with mean density of 6.23 +/- 5.13 parasites/cm3. The present study supplies information on adult nematodes biometry and this is the first record of T. (T.) minutus in A. guariba clamitans from Minas Gerais State, Brazil.

Gene expression profiling during early acute febrile stage of dengue infection can predict the disease outcome.

BACKGROUND: We report the detailed development of biomarkers to predict the clinical outcome under dengue infection. Transcriptional signatures from purified peripheral blood mononuclear cells were derived from whole-genome gene-expression microarray data, validated by quantitative PCR and tested in independent samples. METHODOLOGY/PRINCIPAL FINDINGS: The study was performed on patients of a well-characterized dengue cohort from Recife, Brazil. The samples analyzed were collected prospectively from acute febrile dengue patients who evolved with different degrees of disease severity: classic dengue fever or dengue hemorrhagic fever (DHF) samples were compared with similar samples from other non-dengue febrile illnesses. The DHF samples were collected 2-3 days before the presentation of the plasma leakage symptoms. Differentially-expressed genes were selected by univariate statistical tests as well as multivariate classification techniques. The results showed that at early stages of dengue infection, the genes involved in effector mechanisms of innate immune response presented a weaker activation on patients who later developed hemorrhagic fever, whereas the genes involved in apoptosis were expressed in higher levels. CONCLUSIONS/SIGNIFICANCE: Some of the gene expression signatures displayed estimated accuracy rates of more than 95%, indicating that expression profiling with these signatures may provide a useful means of DHF prognosis at early stages of infection.

Ocorrência de Trypanoxyuris (Trypanoxyuris) minutus (Schneider, 1866) (Nematoda, Oxyuridae) em Alouatta guariba clamitans Cabrera, 1940 (Primates, Atelidae) em Minas Gerais, Brasil / Occurrence of Trypanoxyuris (Trypanoxyuris) minutus (Schneider, 1866) (Nematoda, Oxyuridae) in Alouatta guariba clamitans Cabrera, 1940 (Primates, Atelidae) in Minas Gerais, Brazil

Este trabalho teve como objetivo registrar a ocorrência de Trypanoxyuris (Trypanoxyuris) minutus em Alouatta guariba clamitans no estado de Minas Gerais, Brasil, e fornecer dados quantitativos sobre as infrapopulações desses nematoides, além de dados morfológicos e biométricos de machos e fêmeas. Dois espécimes de A. guariba clamitans, mortos acidentalmente, foram necropsiados, visando aos estudos parasitológicos. Apenas o intestino grosso e o ceco estavam parasitados por T. (T.) minutus. A intensidade do parasitismo no intestino grosso foi de 6650 parasitos e a densidade de 2,6 parasitos/cm³ de intestino. No ceco, observou-se uma intensidade média de 6.753 ± 490,73 parasitos, com uma densidade média de 6,23 ± 5,13 parasitos/cm³. O presente trabalho fornece informações sobre a biometria dos adultos de T. (T.) minutus nessa espécie de hospedeiro, e se constitui no primeiro registro dessa espécie em A. guariba clamitans em Minas Gerais, Brasil.

This study aims to register the occurrence of Trypanoxyuris (Trypanoxyuris) minutus in Alouatta guariba clamitans, in Minas Gerais state, Brazil. Two specimens of A. guariba clamitans, died accidentally, have been necropsied for parasito-logical studies. Only the large intestine and caecum were infected by T. minutus. The parasitism intensity was 6650 parasites and the density was 2.6 parasites/cm³ of large intestine. In the caecum, the mean intensity was 6753 ± 490.73 parasites, with mean density of 6.23 ± 5.13 parasites/cm³. The present study supplies information on adult nematodes biometry and this is the first record of T. (T.) minutus in A. guariba clamitans from Minas Gerais State, Brazil.