Distribution of heat shock protein 108 mRNA in the chicken central nervous system

Thermal manipulation during broiler chicken embryogenesis: Effect on mRNA expressions of Hsp108, Hsp70, Hsp47 and Hsf-3 during subsequent post-hatch thermal challenge

Effects of thermal manipulation during broiler chicken embryonic days 12-18 on body temperature (T(b)) and mRNA expressions of Hsp108, Hsp70, Hsp47 and Hsf-3 in muscle, heart and brain tissues during subsequent thermal challenge (TC) were investigated. Fertile chicken eggs were divided randomly into four groups (n=375): eggs in the control group were maintained at 37.8°C and 56% (RH). Eggs in TM1 group were subjected to TM at 39°C for 9h during ED 12-18. Eggs in the TM2 and TM3 groups were subjected to the same protocol of TM1 except for increasing the period of exposure to 12h and 18h, respectively. During TC (43°C for 6h) at days 10 and 28, T(b) of TM chicks was significantly lower compared to controls. Furthermore, significant changes in mRNA expressions of Hsp108, Hsp70 and Hsp47 in muscle, heart and brain tissues were observed.

Distribution of heat shock protein 108 mRNA during the development of the chicken brain

The developmental expression of heat shock protein 108 (HSP108) mRNA was mapped in chicken brain using in situ hybridization and reverse transcription-polymerase chain reaction (RT-PCR). RT-PCR showed that HSP108 mRNA increased from embryonic day 5 (E5) to 13 (E13), significantly decreased from E17 to E21 and then increased again at the adult stage. In situ hybridization showed that while intense HSP108 positive (HSP108+) signals were localized in the cerebellum from E7 to E14, the intensities of these signals were significantly decreased at E17. However, at the adult stage, HSP108 expression increased in a cell type dependent manner. A decrease in HSP108 mRNA expression during differentiation was also observed in an in vitro study of brain cells treated with nerve growth factor (NGF).

Systematic screening for signaling molecules expressed during somitogenesis by the signal sequence trap method

We describe a systematic screening to search for molecules that act as an extracellular signal during somitogenesis in vertebrates. Somitogenesis, which gives rise to segmented structures of axial bones and muscles, is a consequence of cooperative morphogenetic movements caused by precisely regulated cell and tissue interactions. We employed a strategy that combined subtractive hybridization to enrich paraxial mesoderm/somite-specific cDNAs and the signal sequence trap method, which selects signal sequence-containing molecules. Ninety-two independent cDNAs found to possess a putative signal sequence or a transmembrane domain are presented with a data base accession number for each. These clones include cDNAs which were previously identified with a function characterized, cDNAs previously identified with an undetermined function, and also cDNAs with no similarity to known sequences. Among them, 16 clones exhibited peculiar patterns of expression in the presomitic mesoderm/somites revealed by whole-mount and section in situ hybridization techniques, with some clones also being expressed in the forming neural tube. This is the first report in which an elaborate strategy combining three different screening steps was employed to identify signaling molecules relevant to a particular morphogenetic process.

Heat shock protein 108 mRNA expression during chicken retina development

In a developmental study on the expression of heat shock protein 108 (HSP108) mRNA in the chicken retina, we found different spatial and temporal expressions of HSP108 mRNA in each retinal layer. While intense HSP108 signals were found in the retina neuroblast layer at embryonic day 5 (E5), the ganglion cell population (GC), inner nuclear layer (IN) and pigment epithelium (PE) showed HSP108 expression at E9. At E14, HSP108 signals were reduced versus the previous stages even though signals were still detected in the GC, the IN, the outer nuclear layer and the PE. HSP108 signals were still detectable at the E21 stage, although each retinal layer showed a much differentiated morphology and diminished signal intensity. These results suggest that HSP108 expression might be developmentally regulated throughout eye organogenesis and that it plays a role in ocular development.

Light irradiation increases embryotoxicity of photodynamic therapy sensitizers (5-aminolevulinic acid and protoporphyrin IX) in chick embryos

Photodynamic therapy (PDT) of malignant processes is based on the ability of a photosensitizer to first, accumulate in malignant (immature) tissue and second, to be destroyed following light irradiation. Because of the similarity between malignant and embryonic immature tissues, we investigated the deleterious effect of the PDT procedure on day 4 chick embryos in ovo. We compared experimentally the photodynamic effect (light-toxic) and the side effect (dark-toxic) of the clinically attractive photosensitizers 5-aminolevulinic acid (ALA) and protoporphyrin IX (PP IX). The dark and light embryotoxicity (i.e. lethality plus teratogenicity) was determined after intra-amniotic injection of one of a range of dose of each compound. Under dark conditions, PP IX exhibited embryotoxicity at a dose of 10 microg/embryo; however ALA did not exhibit embryotoxicity even at the highest dose (300 microg/embryo). Light irradiation of embryos following injection induced strong embryotoxic effects of both substances even at dark-ineffective doses.