On the chiroptical properties of racemic crystals

In a recent letter on the “Optical activity from racemates”, discussed at the 16th International Conference on Chiroptical Spectroscopy in Rennes (June 2017), scientists claimed to have measured the circular dichroism of colored, racemic crystals of two transition metal complexes, observations that “serve to correct a clear deficit in our understanding of the optical properties of racemates.” In fact, there is no deficit in our understanding of the optical properties of racemates. Moreover, the measurements presented are unconvincing as evidence of circular dichroism measured in anisotropic crystals and therefore do not inform our understanding of the specific crystals investigated, or racemates generally speaking.     

Effects of sex and dietary phosphorus level on the apparent metabolizable energy and nutrient digestibility in broiler chickens

The influence of sex of broilers and dietary phosphorus (P) level on energy utilization and apparent ileal digestibility of N, P and phytate-P were investigated. The AME_N was determined using 3- and 6-week old broilers, while the apparent ileal digestibility were determined only with 6-week old birds. Sex of broilers had no effect on the AME_N values determined during week 3. During week 6, the AME_N values for male broilers were higher (P?0.01) than those for the females. An interaction (P?0.05) between sex and dietary P level was also observed. AME_N values determined with male broilers were lower in the adequate-P diet compared to those in the low-P diet, whereas no effect of P level was observed in females. Female broilers tended (P?0.10) to have a higher ileal N digestibility than the males, but a significant (P?0.01) sex ×?P level interaction was observed. Males receiving the adequate-P diet had a lower N digestibility than those receiving the low-P diet, whereas the opposite was true in the females. Ileal phytate P degradation in males was higher than in females (0.282 vs. 0.234), but the differences were not significant. Increasing dietary P level increased ileal P digestibility in both the males and females, but the improvements were greater in the females, as indicated by a significant sex × P level interaction.     

Duodenal mucosal risk markers in patients with familial adenomatous polyposis: effects of celecoxib/ursodeoxycholic acid co-treatment and comparison with patient controls

Background

Familial adenomatous polyposis (FAP) is a disease characterized by the development of hundreds to thousands of adenomatous polyps in the colorectum early in life. Virtually all patients with FAP will develop colorectal cancer before the age of 40 to 50 years, unless prophylactic colectomy is performed, which significantly improves their prognosis. The mortality pattern has changed and duodenal cancer now is one of the main cancer-related causes of death in these patients. Practically all patients with FAP develop premalignant duodenal adenomas, which may develop to duodenal cancer in approximately 3-7% of patients. Duodenal cancer in patients with FAP has a poor prognosis. The clinical challenge is to identify patients at high-risk for duodenal carcinoma. Chemoprevention would be desirable to avoid duodenectomy. The main goal of this study is to identify risk markers in normal duodenal mucosa of patients with FAP, that could help identify patients at increased risk for malignant transformation.

Methods

Messenger RNA (mRNA) levels of glutathione S-transferase A1 (GSTA1), glutathione S-transferase P1 (GSTP1), KIAA1199, E-cadherin, peroxisome proliferative activated receptor δ (PPARδ), caspase-3, cyclin D1, β-catenin, and cyclooxygenase-2 (COX-2) were measured in duodenal mucosa, using the QuantiGene 2.0 Plex assay. Levels in normal appearing mucosa of patients with FAP (n?=?37) were compared with levels in non-FAP patient controls (n?=?16). In addition, levels before and after treatment with either celecoxib & ursodeoxycholic acid (UDCA, n?=?14) or celecoxib & placebo (n?=?13) were evaluated in patients with FAP.

Results

mRNA levels of glutathione S-transferase A1 (28.16% vs. 38.24%, p?=?0.008) and caspase-3 (3.30% vs. 5.31%, p?=?0.001) were significantly lower in patients with FAP vs. non-FAP patient controls, respectively. COX-2 mRNA levels in normal duodenal mucosa of patients with FAP were found to be unexpectedly low. None of the potential risk markers was influenced by celecoxib or celecoxib & UDCA.

Conclusions

Protection against toxins and carcinogens (GSTA1) and apoptosis (caspase-3) is low in patients with FAP, which could contribute to increased susceptibility for malignant transformation of duodenal mucosa.

Trial registration

http://ClinicalTrials.gov number NCT00808743

     

The rate of synonymous substitution in enterobacterial genes is inversely related to codon usage bias

Genes sequences from Escherichia coli, Salmonella typhimurium, and other members of the Enterobacteriaceae show a negative correlation between the degree of synonymous-codon usage bias and the rate of nucleotide substitution at synonymous sites. In particular, very highly expressed genes have very biased codon usage and accumulate synonymous substitutions very slowly. In contrast, there is little correlation between the degree of codon bias and the rate of protein evolution. It is concluded that both the rate of synonymous substitution and the degree of codon usage bias largely reflect the intensity of selection at the translational level. Because of the high variability among genes in rates of synonymous substitution, separate molecular clocks of synonymous substitution might be required for different genes.      

Genbank accession #: AJ237597

Plant Molecular Biology -     

Better than CD: Eugénie Cotton (1881-1967)

Aimé Cotton is known for his invention of circular dichroism spectroscopy. In 1913, he married Eugénie Feytis, a scientist who studied physics with Marie Curie. Following the Second World War, Eugénie Cotton was determined to advance the rights and standing of women, sure in the belief that doing so was necessary not only because it was just but also because a world with women in the forefront would be more secure and less susceptible to the catastrophe worldwide military conflict. She was a cofounder of the Women's International Democratic Federation and served as its first president. In 1951, she was awarded the Stalin Peace Prize, and in 1961, the gold medal from the World Peace Council. The extraordinary life of Eugénie Cotton is reconstructed in a new biography by Loukia Efthymiou, Eugénie Cotton (1881-1967) (Éditions Universitaires Européennes, 2019) that is reviewed here. Among the contributions of Eugénie Cotton of particular interest to the Chirality readership is the biography she wrote of her husband, Aimé Cotton, l'optique et magneto-optique (Éditions Seghers, 1967), the most complete source of information on the founder of the science of circular dichroism. This biography is also discussed here, thereby building two reviews of books, one new and one old, one about Eugénie Cotton and one by her, into a single essay.     

Retention of cryptic genes in microbial populations

Cryptic genes are silenced genes that can still be reactivated by mutation. Since they can make no positive contribution to the fitness of their carriers, it is not clear why many cryptic genes in microbial populations have not degenerated into useless DNA sequences. Hall et al. (1983) have suggested that cryptic genes have persisted because of occasional strong environmental selection for reactivated genes. The present mathematical study supports their suggestion. It shows that a cryptic gene can be retained without having any selective advantage over a useless DNA sequence, if selection for the reactivated gene occasionally occurs for a substantially long time.