Search for narrow pbar p resonances in the reaction pbar p>pbar p pi+pi-

The reaction pbar p -> pbar p pi+ pi- has been studied with high statistics at CERN-LEAR with incident pbar momenta from 1.65 to 2.0 GeV/c by the JETSET (PS202) experiment. The aim of this paper is to search for narrow resonances decaying to pbar p. No evidence for such structures is found. In particular, an upper limit for the production of a 2.02 GeV state with a width of Gamma = 20 MeV, having been seen in other hadroproduction experiments, is established. Our results restrict the cross section for such a peak to be below 200 nb at the 95% confidence level.Comment: 4 pages, 4 figures, 1 table, LaTe

Differential expression of two different homeobox gene families during mouse tegument morphogenesis

The expression of six genes belonging to two different homeobox gene families was studied during the embryonic and postnatal morphogenesis of head and body regions of the mouse integument. The first family included the Otx1 and Otx2 genes, both related to the orthodenticle Drosophila gene and the second was represented by four members of the Antennapedia class HOX genes: Hoxc8 and three Hoxd genes, d9, d11 and d13. In situ hybridizations with 35S labeled antisense RNA probes were performed on head serial frontonasal sections, as well as entire embryo and postnatal tail longitudinal sections. The expression of these genes shows a differential spatiotemporal pattern along the cephalo-caudal axis. In 12.5-day and 15.5-day embryos, the Otx2 gene expression is restricted to the nasal epithelium and its associated glands, while the Otx1 transcripts are present in both nasal and facial integuments, including nasal glands and hair vibrissa follicles. The Hoxc8 expression first appears in skin at 14.5 days of gestation in the sternal region and is extended at 16.5 days to the thoracic ventral and lumbar dorsal regions. The Hoxd9 and Hoxd11 genes are only expressed in the caudal skin from 14.5 days of gestation. The Hoxd13 transcripts are the last to appear, 2 days after birth, and are limited to the last epidermal cells to differentiate, i.e. those of the hair matrix of the caudal pelage hair follicles. Taken together, these observations strengthen the hypothesis that different homeobox gene families specify the regional identity of the skin in the cephalic and body regions

Improved in situ beta-galactosidase staining for histological analysis of transgenic mice

The present study describes a novel method for the histochemical demonstration of beta-galactosidase activity on tissue sections. We have replaced 5-bromo-4-chloro-3-indolyl-beta-D-galactoside (X-Gal) with 5-bromo-indolyl-beta-o-galactopyranoside (Bluo-Gal) as a chromogenic substrate for the bacterial beta-galactosidase (lacZ). After beta-galactosidic cleavage, Bluo-Gal precipitates in form of fine birefringent crystals, whereas X-gal gives rise to an amorphous precipitate. Upon microscopic examination under polarized light, the crystals emit a strong signal consisting of yellow reflected light. This property of Bluo-Gal results in greatly enhanced sensitivity of the staining method for beta-galactosidase and allows for optimal morphological resolution. To exemplify the applications of this technique, the expression is demonstrated in transgenic mice of beta-galactosidase driven by a fragment of the human tissue-type plasminogen activator promoter