A novel mutation in the mitochondrial tRNAAla gene (m.5636T>C) in a patient with progressive external ophthalmoplegia

We report a heteroplasmic novel mutation m.5636T>C in the mt-tRNA^Ala in a patient with bilateral ptosis and ophthalmoparesis in whom a muscle biopsy showed cytochrome c oxdidase (COX) negative and ragged red fibers. Using laser capture microdissection we have isolated COX negative fibers and COX positive fibers from the muscle of the patient and determined that the mutation load was clearly increased in COX negative muscle fibers. Additionally, the mutated m.5636T nucleotide is conserved in all the mammal and non-mammal species analyzed and might be structurally relevant as it is located in a position involved in the formation of tertiary structure of canonical mitochondrial tRNAs.     

Understory spider diversity in two remnants of tropical montane cloud forest in Chiapas, Mexico

We evaluated the spider diversity of a tropical montane cloud forest understory in two nearby sites with different degree of human disturbance at the Biosphere Reserve Volcán Tacaná, Chiapas, Mexico. The study was conducted over a 24 days period distributed in 6 months in 2009, covering dry and rainy seasons. A total of 8,370 spiders (1,208 adults and 7,162 juveniles) were collected. Determined specimens (7,747) represented 112 species and morphospecies, 71 genera and 22 families. The results showed that human disturbance has an influence on spider communities: species richness was significantly higher in the preserved site as regards to the disturbed site. Despite their proximity, the composition of spider communities showed only a moderate similarity between the two sites. No differences in abundance were found among sites when considering the whole sample, but sites differed clearly when seasons were analyzed separately. The rainy season had a negative effect on the abundance of spiders in the preserved site. Although the spider community structure was very similar between sites, there was a trend towards a greater species evenness in the preserved site for the whole sampling period and for the dry season.     

A Review of the International Atomic Energy Agency (IAEA) International Standards for Tissue Banks

The IAEA International Standards for Tissue Banks published in 2003 were based on the Standards then currently in use in the USA and the European Union, among others, and reflect the best practices associated with the operation of a tissue bank. They cover legal, ethical and regulatory controls as well as requirements and procedures from donor selection and tissue retrieval to processing and distribution of finished tissue for clinical use. The application of these standards allows tissue banks to operate with the current good tissue practice, thereby providing grafts of high quality that satisfy the national and international demand for safe and biologically useful grafts. The objective of this article is to review the IAEA Standards and recommend new topics that could improve the current version.     

Exploration of the valproic acid binding site on histone deacetylase 8 using docking and molecular dynamic simulations

Epigenetic therapy is an important focus of research for drug development in the treatment of cancer. Valproic acid (VPA) is an HDAC inhibitor that has been evaluated in clinical studies. Despite its success in treating cancer, the mechanism of inhibition of VPA in HDAC is unknown. To this end, we have used docking and molecular dynamic simulations to investigate VPA binding to HDAC, employing both native and rebuilt 3-D structures. The results showed that VPA, via its carboxyl group, coordinates the Zn atom and other local residues (H141-142 and Y360) located at the catalytic site (CS) of HDAC. This causes electrostatic and hydrogen bonding interactions while having little interaction with the hydrophobic side chains, resulting in a low affinity. However, after several docking studies on different native HDAC 3-D structures and after using several snapshots from MD simulations, it became apparent that VPA bound with highest affinity at a site located at the acetyl-releasing channel, termed the hydrophobic active site channel (HASC). The affinity of VPA for HASC was due to its highly hydrophobic properties that allow VPA to take part in van der Waals interactions with Y18, I19, Y20, V25, R37, A38, V41, H42, I135 and W137, while VPA's carboxylate group has several hydrogen bonding interactions with the backbones of S138, I19, N136 and W137. MD simulations showed that the HASC door continuously opened and closed, which affected the affinity of VPA to the HASC, but the affinity toward the HASC was consistently higher than that obtained for the CS, suggesting that the HASC could be involved in the mechanism of inhibition.     

Lordosis: Inhibiting effects of progesterone in the female rat

Progesterone has two types of inhibitory effects on female sexual behavior that have been well-documented in the guinea pig. The first occurs when high levels of progesterone are present around the start of the estrogen-priming process (“concurrent inhibition”). The second occurs immediately after the display of an estrogen-progesterone-induced period of estrous behavior (“sequential inhibition”). In the present set of experiments, we show that the rat, like the guinea pig, is capable of exhibiting both of these inhibitory effects of progesterone. However, rats require higher doses of progesterone than guinea pigs, at least for concurrent inhibition to be evident. In addition, we show that the dose of progesterone required in a single injection to produce concurrent inhibition is higher than the dose required to produce sequential inhibition in rats. A theory of how progesterone may be accomplishing its inhibitory effects on female sexual behavior in rodents is presented.     

Inducible α-glucosidase of Mucor rouxii: Effects of dimorphism on the development of the wall-bound activity

Some properties of the inducible α-glucosidase system of Mucor rouxii were investigated. This enzymatic activity was induced after resuspending glucose-grown cells in a maltose-supplemented medium. The wall-bound activity of α-glucosidase was determined by using intact cells in the enzymatic assay; this activity represented from 80 to 90% of the total activity present in the induced cells. The addition of glucose before, or during, the induction period repressed α-glucosidase synthesis. α-Glucosidase induction was tested under aerobic and anaerobic conditions. It was found that the enzyme synthesis and the appearance of wall-bound activity were not affected by changing the gaseous environment. On the other hand, it was observed that anaerobically grown yeast-like cells were much less efficient than aerobic mycelia to develop wall-bound α-glucosidase activity. This could explain earlier observations about the incapacity of M. rouxii to utilize maltose as a substrate for anaerobic growth. This idea was strengthened by the fact that, if an anaerobic culture was induced to develop under a mycelial morphology by adding to the medium the chemical agent EDTA, these cells also acquired the capacity to grow on maltose and concomitantly possessed wall-bound α-glucosidase activity. The relevance of the structure of the cell wall on the capacity of M. rouxii to metabolize maltose is discussed.     

Effects of castration and hormone replacement on male sexual behavior and pattern of expression in the brain of sex-steroid receptors in BALB/c AnN mice

Little is known about the hormonal regulation of sexual behavior and about the pattern of expression in the brain of sex-steroid receptors in the BALB/c AnN strain of mice (Mus musculus). In this study, 8-week old male BALB/c AnN mice were castrated and the temporal course of decline of sexual behavior was studied, as well as the effects of daily treatment with either testosterone propionate (TP), estradiol benzoate (EB), or dihydrotestosterone propionate (PDHT). Castration resulted in rapid decline of sexual behavior, in both control or vehicle-treated mice. TP maintained full sexual behavior of castrated mice, while PDHT or EB did not have this effect. The expression of ER-alpha dropped nearly 50% after castration, and this pattern remained in TP or PDHT-treated mice, while EB increased the ER-alpha mRNA levels to almost the same values as in intact control mice. The same pattern was found when ER-beta mRNA levels were analyzed. The expression of the PR-A/B gene in the different brain regions in intact mice and after castration, or among the differently treated mice, showed significant differences between normal and castrated mice at all times in all brain regions studied, with the exception of the frontal cortex. Castration reduced the expression of AR by 10-fold, as compared to intact control mice, while TP or PDHT treatment returned its expression to the same levels as in intact control mice, in all brain areas studied. The changes are more prominent in POA-HIP than in HYP and CF. These results demonstrated a rapid decline of sexual behavior in this strain of mice after castration, and show that only TP was able to maintain male sexual behavior, with no correlation with the pattern of expression of sex hormone receptors in specific areas of the mouse brain.     

The chronostratigraphic position of the Camping Francas section(Neogene of Tarragona,Spain)

The presence of Cirsotrema (s.s.) pumiceum (BROCCHI) and Chlamys (Manupecten) pesfelis (LINNE) in the section of Camping Francás (Province of Tarragona, Spain) suggests that the age of the deposits be changed from the upper Miocene (Tortonian) to the Pliocene. The change is of particular significance as the site is one of the classic localities of Pectinidae of the Neogene in North East Spain, and is type locality of Pecten (Flabellipecten) constisulcatus ALMERA & BOFILL.