Parental speaking style and child language development
Parentese influences language development in infants. Image courtesy of Pixabay/ReadyElements.
Across cultures, adults often use “parentese,” a speaking style characterized by exaggerated intonation, high pitch, and slow tempo, when interacting with young children. Previous studies have suggested that children who hear more parentese tend to have improved language development, but the effects of coaching parents to use parentese with infants are unclear. Naja Ferjan Ramírez et al. (pp. 3484–3491) used a randomized controlled trial involving 71 US families of 6-month-old infants to determine whether parent–coaching interventions to enhance parentese could influence child language development. Interventions in which parents listened to recordings of themselves interacting with their infants, received linguistic feedback, and discussed activities to promote language development occurred when infants were 6, 10, and 14 months of age. Families with and without the intervention recorded first-person, naturalistic audio in the infants’ home environments when the infants were 6, 10, 14, and 18 months of age. Along with parental assessments, the recordings were used to determine language development. Interventions enhanced the use of parentese and parent–child turn-taking in conversations, which increased language development by the time children were 18 months of age. Socioeconomic status did not affect the observed links. The findings suggest that parentese is a social catalyst for language, according to the authors. — M.S.
Protein production by defective HIV-1 proviruses
The HIV-1 genome can integrate itself into the DNA of an infected individual’s CD4+ T cells and persist as a provirus despite years of combination antiretroviral therapy (cART). However, most detected proviruses have deleterious mutations that leave them unable to encode intact and replication-competent HIV-1 viruses and are thus considered defective. Such defective viruses are thought to be pathologically insignificant. Using single-cell clones from a chronically infected T cell line and single-cell CD4+ T cell clones from an HIV-1 individual on cART, Hiromi Imamichi et al. (pp. 3704–3710) investigated the ability of naturally occurring defective HIV-1 proviruses to produce viral proteins. The authors found translationally competent defective proviruses in cells from tissue culture and from the cART-treated patient that were able to produce the HIV-1 Gag and Nef proteins. Thus, the study provides in vitro and in vivo evidence that cells harboring defective HIV-1 proviruses are indeed capable of producing HIV-1 proteins, indicating that the proviruses are biologically active. The authors suggest that RNA transcripts and viral proteins expressed by defective proviruses may trigger an immune response and could help explain persistent immune activation even when HIV-1 levels are below detection in most assays. Defective proviruses could thus play a role in pathogenesis and have clinical consequences that may make developing a cure for HIV-1 more challenging, according to the authors. — S.R.
Canine detection of crop pathogen
Detector canine scouting citrus orchard for CLas.
Huanglongbing, a severe infectious disease of citrus trees, is caused by the bacterium Candidatus Liberibacter asiaticus (CLas), which can devastate citrus agricultural production. Neither visual inspection nor molecular assays can detect infection sufficiently early to mount an effective response; the latter are also too expensive and time-consuming to deploy on a large scale. Timothy Gottwald et al. (pp. 3492–3501) trained dogs to distinguish CLas-infected from noninfected trees via smell and assessed the dogs’ performance in a model orchard. The dogs detected infections with greater than 99% accuracy. In a longitudinal study, the dogs identified all infected trees within 30 days of inoculation, whereas detection by a molecular assay took months to years. Dogs were also able to accurately distinguish CLas from a variety of citrus pathogens in an international repository. The authors used epidemiological models to simulate the effects of disease control based on canine detection versus commonly used detection methods. Canine detection combined with infected tree removal was economically sustainable over a 10-year period, whereas molecular assays or visual inspection combined with tree removal failed to suppress the spread of infection. According to the authors, the study suggests that dogs can be used as a cost-effective approach to screen for CLas infection in real time. — B.D.
Dams and freshwater habitat fragmentation
A dam near Passau, Germany.
Dams contribute to flood protection, energy supply, and water security, but they also threaten freshwater fish habitats. To uncover the degree to which dams fragment freshwater fish habitats, Valerio Barbarossa et al. (pp. 3648–3655) combined location data for 39,912 extant global dams and 3,681 future hydropower dams larger than 1 MW with the geographical ranges of 9,794 fish species that live either partially or exclusively in flowing freshwater bodies. The authors determined the habitat fragmentation for each species and found that the contribution of extant dams to habitat fragmentation is highest in China, India, South Africa, the United States, and Europe. In contrast, the contribution of future dams to habitat fragmentation was estimated to be highest in the subtropics and tropics, especially for species that inhabit the Amazon, Congo, Niger, Mekong, and Salween river basins. The findings further suggest that future dams may disproportionately affect fish that complete their life cycle in freshwater rather than fish that migrate between oceans and rivers, according to the authors. — M.S.