Position dependence of hemiray morphogenesis during tail fin regeneration in Danio rerio.

The fins of actinopterygian can regenerate following amputation. Classical papers have shown that the ray, a structural unit of these fins, might regenerate independent of this appendage. Each fin ray is formed by two apposed contralateral hemirays. A hemiray may autonomously regenerate and segmentate in a position-independent manner. This is observed when heterotopically grafted into an interray space, after amputation following extirpation of the contralateral hemiray or when simply ablated. During this process, a proliferating hemiblastema is formed, as shown by bromodeoxyuridine incorporation, from which the complete structure will regenerate. This hemiblastema shows a patterning of gene expression domain similar to half ray blastema. Interactions between contralateral hemiblastema have been studied by recombinant rays composed of hemirays from different origins on the proximo-distal or dorso-ventral axis of the caudal fin. Dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocianine perchlorate labeling of grafted tissues was used as tissular marker. Our results suggest both that there are contralateral interactions between hemiblastema of each ray, and that hemiblastema may vary its morphogenesis, always differentiating as their host region. These non-autonomous, position-dependent interactions control coordinated bifurcations, segment joints and ray length independently. A morphological study of the developing and regenerating fin of another long fin mutant zebrafish suggests that contralateral hemiblastema interactions are perturbed in this mutant.

Toll-like receptor 4 defective mice carrying point or null mutations do not show increased susceptibility to Candida albicans in a model of hematogenously disseminated infection.

We have studied the role of TLR4 in murine defenses against Candida albicans in two TLR4-defective mouse strains: C3H/HeJ mice which have defective TLR4 signaling, and TLR4-/- knockout mice. Both TLR4-defective mice strains experimentally infected with virulent C. albicans cells showed no significant difference in survival as compared with their respective controls. Recruitment of neutrophils to the peritoneal cavity of i.p. infected mice was not affected in TLR4-/-animals, but significantly enhanced in C3H/HeJ mice, compared with their control mice. In vitro production of TNF-alpha by macrophages from both types of TLR4-defective mice, in response to yeasts and hyphae of C. albicans, was not diminished as compared with production by macrophages from wild-type mice. In vitro production of TNF-alpha by yeast-stimulated splenocytes from mice intravenously infected with the low-virulence C. albicans PCA2 strain was not affected in TLR4-defective mice, but the TNF-alpha production in response to hyphae was higher in TLR4-defective than in control animals; the production of IFN-gamma by these splenocytes was similar to controls, as well as the frequency of IFN-gamma-producing CD4+T lymphocytes, indicating that TLR4-defective mice are capable of mounting a Th1 adaptive immune response. Our data indicate that TLR4 is dispensable for murine immune resistance to C. albicans.

Ray-interray interactions during fin regeneration of Danio rerio.

Teleost fin ray bifurcations are characteristic of each ray in each fin of the fishes. Control of the positioning of such morphological markers is not well understood. We present evidence suggesting that the interray blastema is necessary for a proper bifurcation of each ray during regeneration in Danio rerio (Hamilton-Buchanan) (Cyprinidae, Teleostei). We performed single ray ablations, heterotopical graftings of ray fragments and small holes in lateral rays which do not normally bifurcate, to generate recombinants in which the lateral rays are surrounded with ectopic interrays originating from different positions within the tail fin. These ray-interray recombinants do now bifurcate. Furthermore, we show that the interray tissue and surrounding epidermis can modulate the length of the ray. These results stress the role of the interray in inducing bifurcations of the ray blastema as well as modulating ray morphogenesis in general. In addition, gene expression analysis under these experimental conditions suggests that msxA and msxD expression in the ray and interray epidermis is controlled by the ray blastema and that bmp4 could be a candidate signal involved in these inductions.

[Tuberculous infection in Sagunto: infection indicators and study of tuberculin-positive children contacts]. / Infección tuberculosa en Sagunto: indicadores de infección y estudio de los contactos de los niños tuberculín-positivos.

After having ascertained their relevance, epidemiologic indicators of tuberculosis infection were calculated in the area of coverage of a district hospital. For this purpose, a tuberculinic survey was undertaken among students of 2nd. and 8th. grade (EGB) and among those of 1st. grade during two consecutive courses. A prevalence of 2.08% (+/- 1.08%) in 1st. grade (in 1986-87), of 1.18% (+/- 0.87%) in 1st. grade (in 1987-88), of 1.13% (+/- 0.79%) in 2nd. grade (in 1987-88) and of 2.19% (+/- 1.10%) in 8th grade (in 1987-88). The annual incidence of infection in the studied period was 0. The Annual Risk of Infection (ARI) was lower than 0.12% with an annual reduction of 57%. This is the first time that indicators of infection are obtained in a population of the region of Valencia, and are compared with other populations. We outline the benefits of the investigation of the source of infection and of the family contacts. Fourty-eight Mantoux (+) children were detected, of which 8 had tuberculosis, 1 had residual lesions, and the remaining ones were at the infectious stage. Among the 105 studied adults, 60 were Mantoux (+), of which 6 had tuberculosis, 2 of them were smear (+) and 5 had residual lesions. Chemoprophylaxis was initiated in 14 cases.