Normal Vestibular Function in Chicks After Partial Exposure to Microgravity During Development

Sixty-four fertilized chicken eggs, half at developmental Day 2 and half at Day 9, were exposed to micro-gravity for 5 days aboard the shuttle. Postflight examination showed that none of the Day 2 flight embryos had survived, whereas the Day 9 flight group and both groups of synchronous ground control embryos appeared viable. One-half of the Day 9 flight and ground control embryos were dissected and the temporal bones preserved in acetone for morphological examination. The other half was allowed to hatch to examine vestibularly related behavioral changes. Morphology of the lagenar otoconia was evaluated by scanning electron microscopy. Behavioral changes were accessed by a battery of reflex tests and recordings of spontaneous and vestibularly driven head movements. The results from both the morphological and behavioral studies showed no consistent difference between the flight and the control animals. Several hypotheses may account for this negative result. Because all the Day 2 embryos failed to survive, the remaining Day 9 chicks may have passed the critical developmental period of the chick’s vestibular system. Also, the reexposure of the developing chick embryo to earth’s 1-g environment may have masked any adverse behavioral effects that exposure to Microgravity may have caused.

Normal vestibular function in chicks after partial exposure to microgravity during development

Sixty-four fertilized chicken eggs, half at developmental Day 2 and half at Day 9, were exposed to micro-gravity for 5 days aboard the shuttle. Postflight examination showed that none of the Day 2 flight embryos had survived, whereas the Day 9 flight group and both groups of synchronous ground control embryos appeared viable. One-half of the Day 9 flight and ground control embryos were dissected and the temporal bones preserved in acetone for morphological examination. The other half was allowed to hatch to examine vestibularly related behavioral changes. Morphology of the lagenar otoconia was evaluated by scanning electron microscopy. Behavioral changes were accessed by a battery of reflex tests and recordings of spontaneous and vestibularly driven head movements. The results from both the morphological and behavioral studies showed no consistent difference between the flight and the control animals. Several hypotheses may account for this negative result. Because all the Day 2 embryos failed to survive, the remaining Day 9 chicks may have passed the critical developmental period of the chick's vestibular system. Also, the reexposure of the developing chick embryo to earth's 1-g environment may have masked any adverse behavioral effects that exposure to Microgravity may have caused.

Agrobacterium-mediated transformation and regeneration of fertile transgenic plants of chinese cabbage (brassica campestris ssp. pekinensis cv. 'spring flavor')

A procedure for the regeneration of fertile transgenic Chinese cabbage (Brassica campestris ssp. pekinensis cv. 'Spring Flavor') is presented in this report. The protocol is based on infection of cotyledon explants of 5-d-old seedlings with an Agrobacterium tumefaciens strain LBA4404 carrying a disarmed binary vector pTOK/BKS-1. The T-DNA region of this binary vector contains the nopaline synthase/neomycin phosphotransferase II (nptII) chimeric gene for kanamycin resistance and the cauliflower mosaic virus 35S/coat protein gene of tobacco mosaic virus L (TMV-L) chimeric gene. After co-cultivation for 48 h, the cotyledonary petioles were placed on shoot induction media containing 15 mg/L kanamycin sulfate. Shoot induction was continued for 3-4 weeks, then subcultured once and after 2 weeks the shoots were transferred to root induction medium. After 1 week 8 putatively transformed plantlets from 200 cotyledon explants were obtained and transferred to greenhouse. Six of them grew to maturity, produced normal flowers and set seeds. Polymerase chain reaction and Southern blot hybridization analyses confirmed the introduction of the T-DNA into the Chinese cabbage genome. Further, Western blot analysis using polyclonal TMV antiserum showed most of the regenerants (5 out of 6) expressed TMV coat protein gene. Stable inheritance of the inserted clone was investigated in the next generation.

Crystal structure of a paired domain-DNA complex at 2.5 A resolution reveals structural basis for Pax developmental mutations

The 2.5 A resolution structure of a cocrystal containing the paired domain from the Drosophila paired (prd) protein and a 15 bp site shows structurally independent N-terminal and C-terminal subdomains. Each of these domains contains a helical region resembling the homeodomain and the Hin recombinase. The N-terminal domain makes extensive DNA contacts, using a novel beta turn motif that binds in the minor groove and a helix-turn-helix unit with a docking arrangement surprisingly similar to that of the lambda repressor. The C-terminal domain is not essential for prd binding and does not contact the optimized site. All known developmental missense mutations in the paired box of mammalian Pax genes map to the N-terminal subdomain, and most of them are found at the protein-DNA interface.

Sequential flow-injection determination of ionic and total calcium in saliva

In this paper a flow injection manifold for the sequential determination of ionic and total calcium in a small (75 microL) sample of saliva is presented. This setup incorporates two detectors, a tubular potentiometric detector and an atomic absorption spectrophotometer, for determining the ionic and total calcium, respectively. Furthermore, the saliva samples can be injected directly into the manifold without any pre-treatment or loss of carbon dioxide. The results of the analyses of 20 saliva samples were in good agreement with those obtained by the two reference procedures, the direct potentiometry for ionic calcium and atomic absorption spectroscopy for total calcium. The paired Student's t-test showed that there were no statistical differences in the results obtained. The relative standard deviations of ten consecutive measurements of the same salive sample were approximately 3% for ionic calcium and 4% for total calcium. Effects of differences in coexisting ions, ionic strength, and pH between standard solutions and samples were negligible.

Laminin adhesion-selected primary human colon-cancer cells are more tumorigenic than the parenteral and nonadherent cells

Laminin has been shown to promote the malignant phenotype and the level of the 32/67 Kd laminin receptor has been found to correlate with Dukes' staging of colon cancer. A biopsy of a Dukes' stage B2 human colon carcinoma formed a tumor in a nude mouse after coinjection with Matrigel. The parental tumor and the murine tumor appeared identical at the histological level. A cell line LCC-C1 was established from the murine tumor. The cell line appeared moderately differentiated although it did not produce mucin in vitro; however, the xenograft in vivo did produce low levels of mucin. Laminin adherent and non-adherent cell lines were selected. The parental and the laminin-selected cell subclones adhered equally well to plastic and to fibronectin and showed similar growth rates on plastic. When injected subcutaneously into nude mice, the laminin-adherent cells formed relatively undifferentiated tumors that were twice as large as the parental cell tumors whereas the laminin non adherent cells formed very small, but highly differentiated tumors. These data demonstrate that subpopulations of tumor cells which differ in their tumorigenic properties can be selected based on their adhesion to laminin and thus provide models for studying the mechanisms of tumor growth.

Functional and biochemical parameters of peptide antigen presentation

To understand the mechanism by which peptide antigens are processed and presented to T cells, we examined the T-cell response to the 13-amino-acid peptide alpha-melanocyte-stimulating hormone (alpha-MSH). To determine the fine specificity of T-cell recognition, T cells specific for alpha-MSH, and genetically restricted by I-Ab/d, were challenged with different alpha-MSH analogs and homologs. It was found that intact alpha-MSH, including the blocked amino and carboxy termini of the native molecule, was required for T-cell responsiveness. Antigen-presenting cells (APC) could be briefly pulsed with alpha-MSH and then present the alpha-MSH antigenic determinant to T cells, indicating that the relevant antigen was retained by the APC. APC stimulatory capacity was dramatically reduced by aldehyde treatment of the APC, or by pulsing the APC with alpha-MSH at low temperature. Efficient alpha-MSH pulsing was also impaired by treatment of the APC with the carboxylic ionophore, monensin, but not by the lysosomotropic agents chloroquine and methylamine. In addition, isolated APC plasma membranes added to the T cells in the presence of soluble alpha-MSH were not stimulatory. However, plasma membranes isolated from APC that had been previously pulsed with alpha-MSH retained stimulatory activity for T-cell responses. The only detectable alpha-MSH contained in these pulsed APC membranes was in an acid-stable complex of higher molecular weight than native peptide. The amount of alpha-MSH detected in the cellular membrane fraction isolated by density gradient sedimentation was also reduced by treatments that reduced the APC stimulatory capacity, such as pulsing at low temperature or in the presence of monensin. Taken together, these results suggest that processing of alpha-MSH is unlike that heretofore described for other peptide antigens and seems to involve APC handling to form the stimulatory moiety presented on the APC surface.