Mesenchymal/epithelial regulation of retinoic acid signaling in the olfactory placode

We asked whether mesenchymal/epithelial (M/E) interactions regulate retinoic acid (RA) signaling in the olfactory placode and whether this regulation is similar to that at other sites of induction, including the limbs, branchial arches, and heart. RA is produced by the mesenchyme at all sites, and subsets of mesenchymal cells express the RA synthetic enzyme RALDH2, independent of M/E interactions. In the placode, RA-producing mesenchyme is further distinguished by its coincidence with a molecularly distinct population of neural crest-associated cells. At all sites, expression of additional RA signaling molecules (RARalpha, RARbeta, RXR, CRABP1) depends on M/E interactions. Of these molecules, RA regulates only RARbeta, and this regulation depends on M/E interaction. Expression of Fgf8, shh, and Bmp4, all of which are thought to influence RA signaling, is also regulated by M/E interactions independent of RA at all sites. Despite these common features, RALDH3 expression is distinct in the placode, as is regulation of RARbeta and RALDH2 by Fgf8. Thus, M/E interactions regulate expression of RA receptors and cofactors in the olfactory placode and other inductive sites. Some aspects of regulation in the placode are distinct, perhaps reflecting unique roles for additional local signals in neuronal differentiation in the developing olfactory pathway.     

Spinocerebellar ataxia 7 (SCA7)

Spinocerebellar ataxia 7 (SCA7) is a progressive autosomal dominant neurodegenerative disorder characterized clinically by cerebellar ataxia associated with progressive macular dystrophy. The disease affects primarily the cerebellum and the retina, but also many other CNS structures as the disease progresses. SCA7 is caused by expansion of an unstable trinucleotide CAG repeat encoding a polyglutamine tract in the corresponding protein, ataxin-7. Normal SCA7 alleles contain 4-35 CAG repeats, whereas pathological alleles contain from 36-306 CAG repeats. SCA7 has a number of features in common with other diseases with polyglutamine expansions: (i) the appearance of clinical symptoms above a threshold number of CAG repeats (>35); (ii) a correlation between the size of the expansion and the rate of progression of the disease: the larger the repeat, the faster the progression; (iii) instability of the repeat sequence (approximately 12 CAG/transmission) that accounts for the marked anticipation of approximately 20 years/generation. The CAG repeat sequence is particularly unstable and de novo mutations can occur during paternal transmissions of intermediate size alleles (28-35 CAG repeats). This can explain the persistence of the disease in spite of the anticipation that should have resulted in its extinction.     

The effects of antioxidants on semen traits and in vitro fertilizing ability of sperm from the flat-headed cat (Prionailurus planiceps)

Since antioxidants can overcome the negative effects of reactive oxygen species (ROS) during sperm cryopreservation, post-thaw sperm quality in flat-headed cats (Prionailurus planiceps), an endangered species, might benefit from the addition of antioxidants to semen extender. The objectives of this study were to: 1) investigate semen traits; and 2) evaluate effects of the vitamin E analogue Trolox (vitamin E) and glutathione peroxidase (GPx) on the quality of frozen sperm from captive flat-headed cats in Thailand. Eight ejaculates were collected by electroejaculation from four flat-headed cats. Each semen sample was divided into three aliquots and re-suspended in a semen extender as follows: 1) without antioxidant supplementation (control); 2) supplemented with 5 mM vitamin E; or 3) supplemented with 10 U/mL GPx. All samples were cryopreserved and thawed. Subjective sperm motility, progressive motility, and the integrity of the sperm membrane, acrosome and DNA were evaluated at semen collection, after 1 h cold storage, and at 0 and 6 h after thawing. Mitochondrial membrane potential, early apoptotic cells, and embryo development by heterologous in vitro fertilization were evaluated after thawing. Captive flat-headed cats were affected by teratozoospermia. After 1 h cold storage, sperm membrane integrity in samples supplemented with GPx was higher than the control group (54.5 ± 13.7 vs 51.3 ± 13.9; P < 0.05; mean ± SD). Sperm frozen in extender with GPx had higher motility at 6 h and greater mitochondrial membrane potential at 0 and 6 h post-thaw incubation than the other groups (P < 0.05). In conclusion, GPx improved the quality of frozen-thawed sperm in flat-headed cats.     

A breed-matched case-control study of potential risk-factors for canine pyometra

The objective was to evaluate plausible risk-factors for pyometra, a common disease affecting almost 25% of all (unspayed) female dogs before 10 years of age. Because of the strong breed-predilection, an age- and breed-matched case-control study was undertaken on 87 pairs (pyometra-cases and healthy controls) from five breeds (Rottweiler (n = 13), Collie (n = 8), Golden retriever (n = 24), Labrador retriever (n = 16) and German shepherd dog (n = 26)). The mean age was 7.9 y (range 0.8-13.8 y). Variables analyzed included pseudopregnancy, age at first oestrus, length of and regularity of the interoestrus interval, hormone treatments, nulliparity, number of parities, age at first whelping, previous urinary tract infections and mammary tumours. Data were modelled multivariably using matched-pair conditional logistic regression. Analysing interactions with breed, previous pregnancy was statistically associated with pyometra. When amalgamated, in three breeds previous pregnancy was protective (Rottweiler, Collie, Labrador retriever) and in one breed statistically intermediate (German shepherd dog) when compared to the baseline (Golden retriever). Previous pregnancy was a statistically significant factor that had a protective effect against pyometra in some breeds but not in the Golden retriever breed. These findings indicate that protective- and risk-factors may vary between different breeds. The obvious problem with low power and limited possibility for extrapolation, using few dogs in few breeds, is acknowledged. However, it is suggested that failure to control for the confounding effect of breed, especially in epidemiological studies on dog diseases, may lead to potentially erroneous conclusions.     

GSTM1 Gene Expression Correlates to Leiomyoma Volume Regression in Response to Mifepristone Treatment

Progesterone receptor modulators, such as mifepristone are useful and well tolerated in reducing leiomyoma volume although with large individual variation. The objective of this study was to investigate the molecular basis for the observed leiomyoma volume reduction, in response to mifepristone treatment and explore a possible molecular marker for the selective usage of mifepristone in leiomyoma patients. Premenopausal women (N = 14) were treated with mifepristone 50 mg, every other day for 12 weeks prior to surgery. Women were arbitrarily sub-grouped as good (N = 4), poor (N = 4) responders to treatment or intermediate respondents (N = 3). Total RNA was extracted from leiomyoma tissue, after surgical removal of the tumour and the differential expression of genes were analysed by microarray. The results were analysed using Ingenuity Pathway Analysis software. The glutathione pathway was the most significantly altered canonical pathway in which the glutathione-s transferase mu 1 (GSTM1) gene was significantly over expressed (+8.03 folds) among the good responders compared to non responders. This was further confirmed by Real time PCR (p = 0.024). Correlation of immunoreactive scores (IRS) for GSTM1 accumulation in leiomyoma tissue was seen with base line volume change of leiomyoma R = −0.8 (p = 0.011). Furthermore the accumulation of protein GSTM1 analysed by Western Blot correlated significantly with the percentual leiomyoma volume change R = −0.82 (p = 0.004). Deletion of the GSTM1 gene in leiomyoma biopsies was found in 50% of the mifepristone treated cases, with lower presence of the GSTM1 protein. The findings support a significant role for GSTM1 in leiomyoma volume reduction induced by mifepristone and explain the observed individual variation in this response. Furthermore the finding could be useful to further explore GSTM1 as a biomarker for tailoring medical treatment of uterine leiomyomas for optimizing the response to treatment.

Clinical Trials identifier

www.clinicaltrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT00579475","term_id":"NCT00579475"}}NCT00579475, Protocol date: November 2004. http://clinicaltrials.gov/ct2/show/{"type":"clinical-trial","attrs":{"text":"NCT00579475","term_id":"NCT00579475"}}NCT00579475     

Paternal inheritance of mitochondria and chloroplasts in Festuca pratensis-Lolium perenne intergeneric hybrids

Organelle inheritance in intergeneric hybrids of Festuca pratensis and Lolium perenne was investigated by restriction enzyme and Southern blot analyses of chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA). All F₁ hybrids exhibited maternal inheritance of both cpDNA and mtDNA. However, examination of backcross hybrids, obtained by backcrossing the intergeneric F₁ hybrids to L. Perenne, indicated that both uniparental maternal organelle inheritance and uniparental paternal organelle inheritance can occur in different backcross hybrids.     

Propionibacteria induce apoptosis of colorectal carcinoma cells via short-chain fatty acids acting on mitochondria

The genus Propionibacterium is composed of dairy and cutaneous bacteria which produce short-chain fatty acids (SCFA), mainly propionate and acetate, by fermentation. Here, we show that P. acidipropionici and freudenreichii, two species which can survive in the human intestine, can kill two human colorectal carcinoma cell lines by apoptosis. Propionate and acetate were identified as the major cytotoxic components secreted by the bacteria. Bacterial culture supernatants as well as pure SCFA induced typical signs of apoptosis including a loss of mitochondrial transmembrane potential, the generation of reactive oxygen species, caspase-3 processing, and nuclear chromatin condensation. The oncoprotein Bcl-2, which is known to prevent apoptosis via mitochondrial effects, and the cytomegalovirus-encoded protein vMIA, which inhibits apoptosis and interacts with the mitochondrial adenine nucleotide translocator (ANT), both inhibited cell death induced by propionibacterial SCFA, suggesting that mitochondria and ANT are involved in the cell death pathway. Accordingly, propionate and acetate induced mitochondrial swelling when added to purified mitochondria in vitro. Moreover, they specifically permeabi-lize proteoliposomes containing ANT, indicating that ANT can be a critical target in SCFA-induced apoptosis. We suggest that propionibacteria could constitute probiotics efficient in digestive cancer prophylaxis via their ability to produce apoptosis-inducing SCFA.     

Electron paramagnetic resonance spectroscopy of site-directed spin labels reveals the structural heterogeneity in the N-terminal domain of apoA-I in solution

Apolipoprotein A-I (apoA-I) is the major protein constituent of high density lipoprotein (HDL) and plays a central role in phospholipid and cholesterol metabolism. This 243-residue long protein is remarkably flexible and assumes numerous lipid-dependent conformations. Consequently, definitive structural determination of lipid-free apoA-I in solution has been difficult. Using electron paramagnetic spectroscopy of site-directed spin labels in the N-terminal domain of apoA-I (residues 1-98) we have mapped a mixture of secondary structural elements, the composition of which is consistent with findings from other in-solution methods. Based on side chain mobility and their accessibility to polar and non-polar spin relaxers, the precise location of secondary elements for amino acids 14-98 was determined for both lipid-free and lipid-bound apoA-I. Based on intermolecular dipolar coupling at positions 26, 44, and 64, these secondary structural elements were arranged into a tertiary fold to generate a structural model for lipid-free apoA-I in solution.