Creating insect neopolyploid lines to study animal polyploid evolution

Whole-genome duplication (polyploidy) poses many complications but is an important driver for eukaryotic evolution. To experimentally study how many challenges from the cellular (including gene expression) to the life history levels are overcome in polyploid evolution, a system in which polyploidy can be reliably induced and sustained over generations is crucial. Until now, this has not been possible with animals, as polyploidy notoriously causes first-generation lethality. The parasitoid wasp Nasonia vitripennis emerges as a stunningly well-suited model. Polyploidy can be induced in this haplodiploid system through (1) silencing genes in the sex determination cascade and (2) by colchicine injection to induce meiotic segregation failure. Nasonia polyploids produce many generations in a short time, making them a powerful tool for experimental evolution studies. The strong variation observed in Nasonia polyploid phenotypes aids the identification of polyploid mechanisms that are the difference between evolutionary dead ends and successes. Polyploid evolution research benefits from decades of Nasonia research that produced extensive reference—omics data sets, facilitating the advanced studies of polyploid effects on the genome and transcriptome. It is also possible to create both inbred lines (to control for genetic background effects) and outbred lines (to conduct polyploid selection regimes). The option of interspecific crossing further allows to directly contrast autopolyploidy (intraspecific polyploidy) to allopolyploidy (hybrid polyploidy). Nasonia can also be used to investigate the nascent field of using polyploidy in biological control to improve field performance and lower ecological risk. In short, Nasonia polyploids are an exceptional tool for researching various biological paradigms.</p

Systematic study of halide-induced ring opening of 2-substituted aziridinium salts and theoretical rationalization of the reaction pathways

The ring-opening reactions of 2-alkyl-substituted 1,1-bis(arylmethyl)- and 1-methyl-1-(1-phenylethyl)aziridinium salts with fluoride, chloride, bromide and iodide in acetonitrile have been evaluated for the first time in a systematic way. The reactions with fluoride afforded regioisomeric mixtures of primary and secondary fluorides, whereas secondary β-chloro, β-bromo and β-iodo amines were obtained as the sole reaction products from the corresponding halides by regiospecific ring opening at the substituted position. Both experimental and computational results revealed that the reaction outcomes in the cases of chloride, bromide and iodide were dictated by product stability through thermodynamic control involving rearrangement of the initially formed primary halides to the more stable secondary halides. The ring opening of the same aziridinium salts with fluoride, however, was shown to be mediated by steric interactions (kinetic control), with the corresponding primary β-fluoro amines being obtained as the main reaction products. Only for 2-acylaziridinium ions was the reaction outcome shown to be under full substrate control, affording secondary β-fluoro, β-chloro, β-bromo and β-iodo amines through exclusive attack at the activated α-carbonyl carbon atom

A Straighforward Synthesis of 3-Substituted Azetidinic Amino Acids,

info:eu-repo/semantics/publishe

Impact of fluoride on thyroid function and histopathology in cyprinus carpio: Implications for aquatic ecosystems

Fluoride pollution in freshwater bodies is becoming alarming because it interferes with the endocrine system of water-dwelling organisms. In this study, we evaluated the effects of sublethal fluoride levels on thyroid hormone levels and histological alterations in Cyprinus carpio, a popular model fish species used in ecotoxicity experiments. The low, medium, and high fluoride groups received 1, 5, and 10 mg/L fluoride, respectively, and thyroxine plasma levels (T4) and triiodothyronine plasma levels (T3) were assessed at 7, 14, 21, and 35 days. The findings revealed that both T4 and T3 levels significantly decreased with increasing dose and ranged from to 10–41 % lower than controls in the 10 mg/L fluoride group. On day 35, T4 levels were reduced by 42 % and T3 levels were reduced by 50 % in the high fluoride exposure group compared to those in the control group. Changes in the thyroid gland were observed under a light microscope that included, but were not limited to, small follicle size, epithelial hypertrophy, and epithelial hyperplasia, especially in the high-fluoride group. These results suggest that elevated fluoride exposure causes a hormonal imbalance in Cyprinus carpio by affecting thyroid hormone biosynthesis and functionality, which may result in growth and reproductive failure. The eminent dose-response data on fluoride concentration and the degree of thyroid disruption clearly emphasise the severe endocrine-disruptive effects of fluoride at increased concentrations. The results of the present study agree with those of other studies that have described the inhibitory effect of fluoride on thyroid function in different fish species. Therefore, we conclude that fluoride may be a potent endocrine disruptor in the environment. As thyroid hormones play significant roles in metabolic and physiological functions in fish, these findings underscore the importance of improving fluoride standards in freshwater habitats. Research on the molecular pathways that lead to thyroid dysfunction when exposed to fluoride and other effects of this chemical substance on the environment