Receiving screened donor human milk as part of a community-based lactation support programme reduces parental symptoms of anxiety and depression.

Infant feeding decisions and maternal mental health are closely tied. Donor human milk (DHM) protects premature infant health and development and can reduce hospital stays. Recent qualitative research has highlighted that having the option for an infant to receive DHM can also support parental wellbeing through reducing concerns about infant health and supporting feeding preferences. However, no quantitative study has examined this relationship. In this study, anxiety and depression scores were measured before and after receiving DHM using the Hospital Anxiety and Depression Scale for 80 parents (77 mothers, 3 fathers) who had sought DHM from a community-facing milk bank. Reasons for seeking DHM included maternal cancer, maternal and infant health complications, insufficient glandular tissue, and low milk supply. Open-ended questions explored the experience of receiving milk. Milk bank records were used to match details of milk given (volume, duration, exclusivity, lactation support given) with survey responses. Both anxiety and depression scores significantly reduced after receiving milk. Although greater lactation support and longer duration of milk predicted a greater decrease in scores, in a regression analysis, only volume of milk given remained a significant predictor. Almost all parents agreed that being able to access DHM supported their wellbeing predominantly through reducing anxieties around infant health but also through feeding choices being respected and the support given at difficult times. The findings add important considerations to the literature considering when and for whom DHM should be used and the complex interplay between infant feeding and mental health.

Commentary on "Increased nicotine vaping due to the COVID-19 pandemic among US young adults: Associations with nicotine dependence, vaping frequency, and reasons for use".

This manuscript is a correspondence referencing an article published in Preventive Medicine.

The origin and diversification of a novel protein family in venomous snakes.

The genetic origins of novelty are a central interest of evolutionary biology. Most new proteins evolve from preexisting proteins but the evolutionary path from ancestral gene to novel protein is challenging to trace, and therefore the requirements for and order of coding sequence changes, expression changes, or gene duplication are not clear. Snake venoms are important novel traits that are comprised of toxins derived from several distinct protein families, but the genomic and evolutionary origins of most venom components are not understood. Here, we have traced the origin and diversification of one prominent family, the snake venom metalloproteinases (SVMPs) that play key roles in subduing prey in many vipers. Genomic analyses of several rattlesnake (Crotalus) species revealed the SVMP family massively expanded from a single, deeply conserved adam28 disintegrin and metalloproteinase gene, to as many as 31 tandem genes in the Western Diamondback rattlesnake (Crotalus atrox) through a number of single gene and multigene duplication events. Furthermore, we identified a series of stepwise intragenic deletions that occurred at different times in the course of gene family expansion and gave rise to the three major classes of secreted SVMP toxins by sequential removal of a membrane-tethering domain, the cysteine-rich domain, and a disintegrin domain, respectively. Finally, we show that gene deletion has further shaped the SVMP complex within rattlesnakes, creating both fusion genes and substantially reduced gene complexes. These results indicate that gene duplication and intragenic deletion played essential roles in the origin and diversification of these novel biochemical weapons.

Extremely Divergent Haplotypes in Two Toxin Gene Complexes Encode Alternative Venom Types within Rattlesnake Species.

Natural selection is generally expected to favor one form of a given trait within a population. The presence of multiple functional variants of traits involved in activities such as feeding, reproduction, or the defense against predators is relatively uncommon within animal species. The genetic architecture and evolutionary mechanisms underlying the origin and maintenance of such polymorphisms are of special interest. Among rattlesnakes, several instances of the production of biochemically distinct neurotoxic or hemorrhagic venom types within the same species are known. Here, we investigated the genetic basis of this phenomenon in three species and found that neurotoxic and hemorrhagic individuals of the same species possess markedly different haplotypes at two toxin gene complexes. For example, neurotoxic and hemorrhagic Crotalus scutulatus individuals differ by 5 genes at the phospholipase A2 (PLA2) toxin gene complex and by 11 genes at the metalloproteinase (MP) gene complex. A similar set of extremely divergent haplotypes also underlies alternate venom types within C. helleri and C. horridus. We further show that the MP and PLA2 haplotypes of neurotoxic C. helleri appear to have been acquired through hybridization with C. scutulatus-a rare example of the horizontal transfer of a potentially highly adaptive suite of genes. These large structural variants appear analogous to immunity gene complexes in host-pathogen arms races and may reflect the impact of balancing selection at the PLA2 and MP complexes for predation on different prey.