Adaptive evolution of synchronous egg-hatching in compensation for the loss of parental care.

Interactions among siblings are finely balanced between rivalry and cooperation, but the factors that tip the balance towards cooperation are incompletely understood. Previous observations of insect species suggest that (i) sibling cooperation is more likely when siblings hatch at the same time, and (ii) this is more common when parents provide little to no care. In this paper, we tested these ideas experimentally with the burying beetle, Nicrophorus vespilloides Burying beetles convert the body of a small dead vertebrate into an edible nest for their larvae, and provision and guard their young after hatching. In our first experiment, we simulated synchronous or asynchronous hatching by adding larvae at different intervals to the carrion-breeding resource. We found that 'synchronously' hatched broods survived better than 'asynchronously' hatched broods, probably because 'synchronous hatching' generated larger teams of larvae, that together worked more effectively to penetrate the carrion nest and feed upon it. In our second experiment, we measured the synchronicity of hatching in experimental populations that had evolved for 22 generations without any post-hatching care, and control populations that had evolved in parallel with post-hatching care. We found that larvae were more likely to hatch earlier, and at the same time as their broodmates, in the experimental populations that evolved without post-hatching care. We suggest that synchronous hatching enables offspring to help each other when parents are not present to provide care. However, we also suggest that greater levels of cooperation among siblings cannot compensate fully for the loss of parental care.

The indignities of shielding during the COVID-19 pandemic for people with sickle cell disorders: an interpretative phenomenological analysis.

This article seeks to understand the first-hand experiences of people with sickle cell, a recessively inherited blood disorder, who were identified as clinically extremely vulnerable during the COVID-19 pandemic. Part of a larger sequential mixed-methods study, this article uses a selective sample of eight qualitative semi-structured interviews, which were analysed using interpretative phenomenological analysis (IPA). The first stage of IPA focused on practical concerns participants had correlated to understanding shielding and their feelings about being identified as clinically extremely vulnerable. In a secondary stage of analysis, we examined the emotions that it brought forth and the foundations of those based on discriminations. This article adds to our theoretical understanding of embodiment and temporality with respect to chronicity and early ageing. It explains how people with sickle cell disorders have an embodied ethics of crisis and expertise. It also elucidates how people's experiences during the pandemic cannot be seen in void but illustrates ableism, racism, and ageism in society writ large.

Experimental evolution of a more restrained clutch size when filial cannibalism is prevented in burying beetles Nicrophorus vespilloides.

The overproduction of offspring is commonly associated with high hatching failure and a mechanism for dispensing with surplus young. We used experimental evolution of burying beetle populations Nicrophorus vespilloides to determine causality in these correlations. We asked does eliminating the mechanism for killing "spare" offspring cause the evolution of a more restrained clutch size and consequently select for reduced hatching failure? N. vespilloides typically overproduces eggs but kills 1st instar larvae through partial filial cannibalism during brood care. We established replicate evolving populations that either could practice filial cannibalism (Full Care) or could not, by removing parents before their young hatched (No Care). After 20+ generations of experimental evolution, we measured clutch size and hatching success. We found that No Care females produced fewer eggs than Full Care females when allowed to breed on a small corpse, a finding not explained by differences in female quality. On larger corpses, females from both populations laid similar numbers of eggs. Furthermore, hatching success was greater in the No Care populations on small corpses. Our results suggest that the adaptive overproduction of offspring depends on a mechanism for eliminating surplus young and that killing offspring, in turn, relaxes selection against hatching failure.

Biomaterial composition and stiffness as decisive properties of 3D bioprinted constructs for type II collagen stimulation.

Gelatin methacrylate (GelMA) and hyaluronic acid methacrylate (HAMA) are frequently used biomaterials for 3D bioprinting, with individual well-established material characteristics. To identify an ideal combination of GelMA and HAMA for chondrogenesis, a novel, primary human chondrocyte COL2A1-Gaussia luciferase reporter system (HuCol2gLuc) was developed. With this non-destructive, high-throughput temporal assay, Gaussia luciferase is secreted from the cells and used as a proxy for measuring type II collagen production. GelMA:HAMA ratios were screened using the reporter system before proceeding to 3D bioprinting. This method is efficient, saving on time and materials, resulting in a streamlined process of biomaterial optimization. The screen revealed that the addition of HAMA to GelMA improved chondrogenesis over GelMA (15%) alone. Storage moduli were measured using dynamic mechanical analysis of the same GelMA:HAMA ratios and established an initial threshold for chondrogenesis of ∼30kPa. To determine if biomaterial storage moduli impact cell mobility, human primary chondrocytes transduced with green fluorescent protein (GFP) were 3D bioprinted in either 1:1 or 2:1 ratios with storage moduli of 32kPa and 57.9kPa, respectively. We found that reduced cell mobility, in the stiffer biomaterial, had higher type II collagen expression, than the softer material with more cell mobility. Finally, after 3D bioprinting with HuCol2gLuc cells we successfully identified an optimal combination (2:1) of GelMA:HAMA and photo-crosslinking time (38s) for chondrogenesis. STATEMENT OF SIGNIFICANCE: One challenge of 3D bioprinting is identifying ideal biomaterials that stimulate articular cartilage development. To identify an optimal combination of gelatin methacrylate and hyaluronic acid methacrylate for chondrogenesis we developed a primary human chondrocyte type II collagen Gaussia luciferase reporter cell (HuCol2gLuc). This non-destructive, high-throughput assay uses a secreted Gaussia luciferase as a proxy for temporal type II collagen production. This reporter system streamlines the biomaterial optimization process before 3D bioprinting. We also used it to determine the level of stiffness required for chondrogenesis. And for the first time, we quantified chondrocyte mobility in a 3D bioprinted construct. Together these results indicate that a biomaterial with a higher storage modulus and less cell mobility, improves chondrogenesis.

Black sickle cell patients' lives matter: healthcare, long-term shielding and psychological distress during a racialised pandemic in England - a mixed-methods study.

OBJECTIVE: To understand the psychological and social impact of shielding on people with sickle cell disorders and their carers in the Midlands region of England. This region was badly affected during the pandemic, with the city of Birmingham having some of the highest rates of COVID-19 deaths. DESIGN: A mixed-methods project with a quantitative survey on shielding and adapted SF36 V.2 questionnaire, which was supplemented by qualitative semistructured interviews analysed using interpretive phenomenological analysis (IPA). PARTICIPANTS: Fifty-one participants who were predominantly of Black Caribbean or Black African heritage anonymously took part in the online survey. We supplemented this with eight in-depth semistructured interviews with adults with sickle cell disorders using IPA. RESULTS: The adapted 36-Item Short Form Survey (SF36) version 2 (V. 2) survey indicated worse quality of life and mental health. The open-ended questions from the adapted survey also identified shielding concerns about hospital care, pain management and knowledge of sickle cell by healthcare professionals. From the interviews, it emerged that the racialised element of the pandemic caused significant psychological distress for a population group that had to regularly access hospitals. It was noted that psychological health needs both during a pandemic and outside of it were poorly understood and became invisible in services. The psychological impact of experiences of hospital care as well as growing up with an invisible chronic condition were important to understand psychologically.