Identification of significant regions of transcription factor DP-1 (TFDP-1) involved in stability/instability of the protein

We previously reported the identification of DP-1 isoforms (α and β), which are structurally C-terminus-deleted ones, and revealed the low-level expression of these isoforms. It is known that wild-type DP-1 is degraded by the ubiquitin-proteasome system, but few details are known about the domains concerned with the protein stability/instability for the proteolysis of these DP-1 isoforms. Here we identified the domains responsible for the stability/instability of DP-1. Especially, the DP-1 “Stabilon” domain was a C-terminal acidic motif and was quite important for DP-1 stability. Moreover, we propose that this DP-1 Stabilon may be useful for the stability of other nuclear proteins when fused to them.     

Expression level of enzymes related to in situ estrogen synthesis and clinicopathological parameters in breast cancer patients

In order to evaluate the importance of estrogen production in tumor and surrounding tissues, we measured mRNA expression levels of 5 enzymes participating to estrogen synthesis in situ and 4 breast cancer-related proteins in 27 pairs of tumor and non-malignant tissues. Steroid sulfatase (STS) mRNA was more frequently detected in tumor tissues rather than in their non-malignant counterparts. Estrogen sulfotransferase (EST) was constantly expressed with high level not only in tumor tissues but also in their surrounding non-malignant counterparts. In contrast, mRNA expression levels of aromatase, and 17β-hydroxysteroid dehydrogenase type I and II were relatively low and detected only in small proportion of the patients. We also measured the mRNA expression levels of the same nine genes in tumor tissues of 197 breast cancer patients, and analyzed relationship between the mRNA expression level and the clinicopathological parameters. The mRNA expression levels of STS, aromatase and erbB2 in tumor tissues increased as breast cancer progressed. The tumoral mRNA expression levels of STS, estrogen receptor β, and erbB2 in patients with recurrence were higher than those in patients without recurrence. Upregulation of STS expression plays an important role in tumor progression of human breast cancer and is considered to be responsible for estrogen production in tumor and surrounding tissues.     

TRAIL Receptors Serve as Stress-Associated Molecular Patterns to Promote ER-Stress-Induced Inflammation

1. Download : Download high-res image (188KB)
2. Download : Download full-size image

     

Ultrastructural changes in isolated rat hepatocytes exposed to different CCl4 concentrations

Ultrastructural data are presented on time-course changes in isolated rat hepatocyte suspensions exposed either to 1.2 or 1.8 mM CCl4 for up to 1 h. The subcellular changes at the lower concentration, but not the higher, are shown to closely parallel those reported to occur in rat hepatocytes following ingestion of CCl4.     

Immunosuppression by Mutated Calreticulin Released from Malignant Cells

1. Download : Download high-res image (218KB)
2. Download : Download full-size image

     

Inhibition of protein synthesis and induction of helical polysomes in rat liver by N-hydroxy-2-fluorenylacetamide

After a single intraperitoneal injection of the hepatocarcinogen N-hydroxy-2-fluorenylacetamide (OH-FAA), numerous helical polysomes were found in the hepatocytic cytoplasm at 2 and 6 but not 24 h after treatment. Electron microscopy also demonstrated nucleolar segregation, disarray of endoplasmic reticuium (ER), and disaggregation of polyribosomes at the times when helical polysomes were present. Polyribosome disaggregation was confirmed and quantified by determining size distribution of polyribosomes at 2 h after OH-FAA treatment. Protein synthesis was inhibited at the time of helical polysome induction but the degree of inhibition did not noticeably alter the number of helical polysomes found electron microscopically.     

Plasma levels of gonadotropin and 17α,20β-dihydroxy-4-pregnen-3-one in relation to spawning behaviour of rainbow trout, Oncorhynchus mykiss(Walbaum)

Manipulation of the opportunity to spawn was used to investigate the relationship between endocrine events, egg viability and spawning behaviour in female rainbow trout. Females were prevented from spawning by isolating them from males and gravel for up to 21 days after ovula- tion. Blood samples were taken before pairing with a male, at the onset of nesting activity, and at the completion of spawning. Plasma hormone levels of gonadotropin (GtH) and 17α,20β-dihydroxy-4-pregnen-3-one (17,2OP) were measured by specific radioimmunoassays. There were no qualitative or quantitative differences in the spawning behaviour of females paired on the day of ovulation or 7. 14, or 21 days after ovulation. There was a general decrease in the viability of eggs with increasing retention times. In females paired on the day of ovulation, or after 7 or 14 days, GtH levels increased with the onset of nesting behaviour and declined as fish reached the post-spawning condition. By day 21, GtH levels before pairing were significantly higher than prepairing levels in the other three treatment groups, and did not increase at the onset of nesting, or decrease in post-spawning fish. Plasma 17,20P remained high in prepairing and nesting samples of all four groups and declined to low levels in fish in post-spawning condition. In females paired on the day of ovulation there was a significant increase in 17,20P from the prepairing to the nesting stage. These results suggest that 17,20P plays a key role in the synchronization of behavioural and maturational events at the time of spawning.     

The comparison of selected life-history characteristics of Mesembryanthema species occurring on and off Mima-like mounds (heuweltjies) in semi arid southern Africa

Selected life-history characteristics of Mesembryanthema species occurring on and off mima-like mounds (heuweltjies) were compared at Tierberg in the southern Succulent Karoo, South Africa. Seed production, the number of seeds retained in seed capsules and germination behaviour were measured in fourteen species of Mesembryanthema which were representatives of two sub-families: the Ruschioideae and the Mesembryanthemoideae. Species occurring onheuweltjies had low overall germination and high seed retention compared with those species occurring offheuweltjies. A strong negative correlation was found between the degree of seed retention and maximum germination. It was proposed that rapid germination and low seed dormancy in species occurring on the flats would be a viable strategy where competition for safe recruitment sites is strong. Species occurring on the flats are long-lived woody shrubs, thus the resulting high levels of seedling mortality probably do not have a major impact on population dynamics.Heuweltjies are sites of intense disturbance. Plant species that occur onheuweltjies can also occur offheuweltjies in disturbed vegetation. Opportunistic life-history characteristics allow these species to colonise disturbed areas.Heuweltjie species thus act as pioneers in a successional process which results ultimately in the re-colonisation of the long-lived flats species. Phylogenetic factors may also determine the species distributions. Members of the Mesembryanthemoideae did not occur offheuweltjies in undisturbed areas. Most Ruschioideae were found on the flats but the few species that occurred onheuweltjies shared similar characteristics with the Mesembryanthemoideae. The primitive life-history characteristics exhibited by the Mesembryanthemoideae enable them to exploit disturbed conditions.     

Scaleup of spinfilter perfusion bioreactor for mammalian cell retention

A spinning cylindrical filter, known as a spinfilter, permits the mammalian cell bioreactor operation at high perfusion rates leading to very high cell densities (10(7) mL(-1)). Filter screens with openings (25 mum) slightly larger than the average cell size have been used to retain single cells in suspension over a long period of operation without clogging. We have previously shown why it is necessary to optimize the rotational speed of the spinfilter in order to achieve efficient cell retention and avoid potential screen clogging. Effects of bulk mixing and perfusion rate on screen fouling and cell retention were also investigated. Based on this analysis, in this article, we suggest strategies for scaleup of spinfilters. Experimental data from 12- and 175-L (working volume) bioreactors is shown in support of the scaleup analysis. (c) 1994 John Wiley & Sons, Inc.