Gonadulin: A newly discovered insulin-like peptide involved in ovulation and oviposition in Rhodnius prolixus, a vector of Chagas disease.

Insulin-like peptides (ILPs) are vital hormones involved in a wide range of physiological processes in all organisms. In insects, insulin signaling has a key role in detecting and interpreting nutrient levels for egg production. Based on publicly available transcriptomes, a new ILP named gonadulin has been reported and suggested to be expressed by the gonads (hence its name). Although the identification of gonadulin establishes its existence, its physiological relevance remains poorly understood. Rhodnius prolixus is an obligate hematophagous insect and a primary vector of Trypanosoma cruzi, the etiological agent of Chagas disease. In this study, we report for the first time the participation of gonadulin in reproductive performance of an hemipteran. By quantitative PCR and fluorescence in situ hybridization (FISH), we find that the R. prolixus gonadulin transcript is highly expressed in the reproductive system, particularly in the calyx, a structure through which eggs move into the lumen of the lateral oviducts during ovulation. The putative gonadulin receptor, a member of the leucine-rich repeat-containing G protein-coupled receptor subfamily (LGR3), is most highly expressed in the central nervous system with lower levels in the reproductive tissue and other tissues. Interestingly, when the gonadulin signaling cascade is impaired using RNA interference (RNAi), eggs are retained primarily in the ovarioles and calyx, indicating that ovulation and oviposition are inhibited. Understanding the physiological processes involved in reproduction in R. prolixus will shed light on potential targets for effective production of biopesticides by translational research, thereby controlling insect populations and transmission of the disease.

Science students' perspectives on how to decrease the stigma of failure.

Failure is hard-wired into the scientific method and yet teaching students to productively engage with failure is not foundational in most biology curricula. To train successful scientists, it is imperative that we teach undergraduate science students to be less fearful of failure and to instead positively accept it as a productive part of the scientific process. In this article, we focus on student perceptions of the stigma of failure and their associated concerns to explore how failure could be better supported within and beyond a university context. Through a survey of first-year biology students, we found that societal and familial pressures to succeed were the greatest contributing factors to students' fear of failure. In student suggestions on how to reduce the stigma of failure within and beyond the university context, the most common theme identified across both contexts was for increased discussion and open communication about experiences of failure. Importantly, student comments in this study bring attention to the role of factors beyond the classroom in shaping student experiences of failure within their biology courses.

Aging effects on contrast sensitivity in visual pathways: A pilot study on flicker adaptation.

Contrast sensitivity is reduced in older adults and is often measured at an overall perceptual level. Recent human psychophysical studies have provided paradigms to measure contrast sensitivity independently in the magnocellular (MC) and parvocellular (PC) visual pathways and have reported desensitization in the MC pathway after flicker adaptation. The current study investigates the influence of aging on contrast sensitivity and on the desensitization effect in the two visual pathways. The steady- and pulsed-pedestal paradigms were used to measure contrast sensitivity under two adaptation conditions in 45 observers. In the non-flicker adaptation condition, observers adapted to a pedestal array of four 1°×1° squares presented with a steady luminance; in the flicker adaptation condition, observers adapted to a square-wave modulated luminance flicker of 7.5 Hz and 50% contrast. Results showed significant age-related contrast sensitivity reductions in the MC and PC pathways, with a significantly larger decrease of contrast sensitivity for individuals older than 50 years of age in the MC pathway but not in the PC pathway. These results are consistent with the hypothesis that sensitivity reduction observed at the overall perceptual level likely comes from both the MC and PC visual pathways, with a more dramatic reduction resulting from the MC pathway for adults >50 years of age. In addition, a similar desensitization effect from flicker adaptation was observed in the MC pathway for all ages, which suggests that aging may not affect the process of visual adaptation to rapid luminance flicker.

Effect of sprouting on antioxidant and inhibitory potential of two varieties of Bengal gram (Cicer arietinum L.) against key enzymes linked to type-2 diabetes.

Type 2 diabetes is a chronic metabolic disease, and the current treatment for type 2 diabetes targets oxidative stress and postprandial hyperglycemia via the inhibition of α-glucosidase and α-amylase, key enzymes linked to type 2 diabetes. In the present study, two varieties of sprouted and non-sprouted Bengal gram (white coated and brown coated) extracts were assayed for total phenolic content, DPPH radical scavenging activity, total antioxidative capability and the inhibition of α-glucosidase and α-amylase activity. Sprouting increased the total phenolic content in both the varieties of Bengal gram and exhibited significant DPPH radical scavenging activity and antioxidant capability compared with that of non-sprouted Bengal gram. Sprouting also increased the inhibitory potential of Bengal gram against α-glucosidase and α-amylase compared with the non-sprouted variety. The overall results suggest that increased antioxidant and inhibitory potential of sprouted Bengal gram against α-glucosidase and α-amylase makes them desirable for dietary management/prevention of diabetes. This finding also provides essential information for the development of sprouted Bengal gram-derived antidiabetic products.