Molecular Illustration in Research and Education: Past,Present, and Future

Two-dimensional illustration is used extensively to study and disseminate the results of structural molecular biology. Molecular graphics methods have been and continue to be developed to address the growing needs of the structural biology community, and there are currently many effective, turn-key methods for displaying and exploring molecular structure. Building on decades of experience in design, best-practice resources are available to guide creation of illustrations that are effective for research and education communities.     

Diverse reproductive barriers in hybridising crickets suggests extensive variation in the evolution and maintenance of isolation

Reproductive barriers reduce gene flow between populations and maintain species identities. A diversity of barriers exist, acting before, during and after mating. To understand speciation and coexistence, these barriers need to be quantified and their potential interactions revealed. We use the hybridising field crickets Gryllus bimaculatus and G. campestris as a model to understand the full compliment and relative strength of reproductive barriers. We find that males of both species prefer conspecific females, but the effect is probably too weak to represent a barrier. In contrast, prezygotic barriers caused by females being more attracted to conspecific male song and preferentially mounting and mating with conspecifics are strong and asymmetric. Postzygotic barriers vary in direction; reductions in fecundity and egg viability create selection against hybridisation, but hybrids live longer than pure-bred individuals. Hybrid females show a strong preference for G. bimaculatus songs, which together with a complete lack of hybridisation by G. campestris females, suggests that asymmetric gene flow is likely. For comparison, we review reproductive barriers that have been identified between other Gryllids and conclude that multiple barriers are common. Different species pairs are separated by qualitatively different combinations of barriers, suggesting that reproductive isolation and even the process of speciation itself may vary widely even within closely related groups.     

Dopamine Transporter Genotype as a Risk Factor for Obesity in African-American Smokers

Objective: To assess the association between a polymorphism related to dopamine function, dopamine transport (SLC6A3), and obesity in smokers. Research Methods and Procedures: Logistic regression was used to assess the relationship between this genetic polymorphism and obesity (body mass index ≥ 30 kg/m²) from a sample of 510 smokers who smoked at least 10 cigarettes per day and who were participating in a study designed to examine genetic and nongenetic predictors of response to a pharmacological treatment. Results: The likelihood of obesity in African Americans (N = 90) with the 10/10 SLC6A3 genotype was 5.16 times that of African Americans with 9/9 or 9/10 SLC6A3 genotypes (odds ratio = 5.16, confidence interval = 1.60 to 16.65). There was no association of the SLC6A3 genotype with obesity for non-Hispanic whites (N = 420). Discussion: These results suggest that variants of the dopamine transporter gene may be related to obesity in African-American smokers. Possible mechanisms responsible for the association between dopamine transport and obesity in African-American smokers are discussed.     

Histochemistry and composition of the cell walls of styles of Nicotiana alata Link et Otto

The cell walls of styles of Nicotiana alata Link et Otto (ornamental tobacco; Solanaceae) were analysed chemically and examined histochemically. Cell-wall preparations were obtained from whole styles and from isolated transmitting-tissue cells. The style epidermal cells were shown histochemically to have thick, lignified secondary walls. These walls probably constituted a large proportion of the cell-wall preparation from whole styles as analysis of whole-style walls indicated that the major polysaccharides were xylans and cellulose, which are typical of lignified secondary walls of Magnoliopsida (dicotyledons). Lignification of the style epidermal walls was also demonstrated histochemically in 10 other species (5 genera including Nicotiana) of the sub-family Cestroideae of the Solanaceae, but not in 15 species (9 genera) of the sub-family Solanoideae of the Solanaceae, nor in 3 other species of dicotyledons and 2 species of Liliopsida (monocotyledons). Analysis of the cell-wall preparation from isolated transmitting-tissue cells of N. alata indicated that these contained cellulose, xyloglucans, and pectic polysaccharides, which is typical of primary cell walls of dicotyledons. However, the analysis indicated that the walls also contained an unusually high proportion of Type II arabinogalactans. Staining of the transmitting-tissue cell-wall preparation with β-glucosyl Yariv reagent, a histochemical reagent specific for arabinogalactan proteins, confirmed their presence, which may be related to the role of these cells in secreting the stylar extracellular matrix.     

Intranasal vaccination with a lentiviral vector protects against SARS-CoV-2 in preclinical animal models

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Gene flow and natal dispersal in the Siberian flying squirrel based on direct and indirect data

Dispersal is a key determinant of the evolution and ecology of species. For a comprehensive picture of dispersal, a combination of both field observations and indirect genetic measures are required, as both of these have strengths that may mitigate the other’s limitations. Here, we used microsatellite markers and radio-telemetry data to study dispersal and gene flow in Siberian flying squirrels. Genetic data confirmed our empirical results that dispersal is female biased in the flying squirrel. Female bias in dispersal is exceptional among mammals and in flying squirrels is probably explained by competition for food resources and nesting cavities among mothers and daughters. The individual-level genetic pattern was influenced by isolation by distance. Using this information fairly comparable dispersal distances were derived using indirect data as observed directly with radio telemetry. Thus, our results support the recent conclusion that individual-level genetic data can be useful in inferring dispersal distances for species for which direct data are lacking.     

Dendro[C60]fullerene DF-1 provides radioprotection to radiosensitive mammalian cells

In this study, the ability of the C₆₀ fullerene derivative DF-1 to protect radiosensitive cells from the effects of high doses of gamma irradiation was examined. Earlier reports of DF-1’s lack of toxicity in these cells were confirmed, and DF-1 was also observed to protect both human lymphocytes and rat intestinal crypt cells against radiation-induced cell death. We determined that DF-1 protected both cell types against radiation-induced DNA damage, as measured by inhibition of micronucleus formation. DF-1 also reduced the levels of reactive oxygen species in the crypt cells, a unique capability of fullerenes because of their enhanced reactivity toward electron-rich species. The ability of DF-1 to protect against the cytotoxic effects of radiation was comparable to that of amifostine, another ROS-scavenging radioprotector. Interestingly, localization of fluorescently labeled DF-1 in fibroblast was observed throughout the cell. Taken together, these results suggest that DF-1 provides powerful protection against several deleterious cellular consequences of irradiation in mammalian systems including oxidative stress, DNA damage, and cell death.