3D bioprinting of tissue units with mesenchymal stem cells, retaining their proliferative and differentiating potential, in polyphosphate-containing bio-ink

The three-dimensional (3D)-printing processes reach increasing recognition as important fabrication techniques to meet the growing demands in tissue engineering. However, it is imperative to fabricate 3D tissue units, which contain cells that have the property to be regeneratively active. In most bio-inks, a metabolic energy-providing component is missing. Here a formulation of a bio-ink is described, which is enriched with polyphosphate (polyP), a metabolic energy providing physiological polymer. The bio-ink composed of a scaffold (N,O-carboxymethyl chitosan), a hydrogel (alginate) and a cell adhesion matrix (gelatin) as well as polyP substantially increases the viability and the migration propensity of mesenchymal stem cells (MSC). In addition, this ink stimulates not only the growth but also the differentiation of MSC to mineral depositing osteoblasts. Furthermore, the growth/aggregate pattern of MSC changes from isolated cells to globular spheres, if embedded in the polyP bio-ink. The morphogenetic activity of the MSC exposed to polyP in the bio-ink is corroborated by qRT-PCR data, which show a strong induction of the steady-state-expression of alkaline phosphatase, connected with a distinct increase in the expression ratio between RUNX2 and Sox2. We propose that polyP should become an essential component in bio-inks for the printing of cells that retain their regenerative activity.

ASIAN EDUCATION FOR THE WORLD LABOR MARKET: A MALAYSIAN SURVEY OF MIGRATION PROPENSITY

The purpose of the study: This research explores issues related to human mobility trend reflecting an increasing outflow of intellectual talents by surveying the migration propensity of future professional labours in Malaysia using small samples from selected universities having different establishment orientation and student compositions. It also surveys factors of their migration intention decisions. Methodology: A quantitative approach utilizing a questionnaire survey distributed to final year students was adopted. A total of 193 usable responses are used in the analysis covering descriptive and mean differences across five identified dimensions of gender, race, academic performance, university type, and education financing. Main Findings: The results indicate that 51% of the respondents have the intention of leaving the country, the majority of whom are private university students, females, Malays, studies funded by education loans, and those from the average group of academic achievement. The low economic reward was ranked first as the main factor in influencing their migration decision. Surprisingly, the worldwide application of accounting-based knowledge plays little role in students’ decision of migrating abroad, signalling students' inability to appreciate the economic consequence of mastering such knowledge and skills. Implications: The research contributes to the public policy debate with respect to education and human mobility by providing a strong basis for a reality check on the sustainability of Malaysia’s future landscape of its professional labour market. It also feeds critical policy inputs for all stakeholders involved, particularly the employers, in providing future Malaysian professionals with a conducive, meaningful, and rewarding career to attract and retain them.

A poor substitute for the real thing: captive-reared monarch butterflies are weaker, paler and have less elongated wings than wild migrants

For many animals and insects that are experiencing dramatic population declines, the only recourse for conservationists is captive rearing. To ensure success, reared individuals should be biologically indistinct from those in the wild. We tested if this is true with monarch butterflies, Danaus plexippus , which are increasingly being reared for release by citizens and commercial breeders. Since late-summer monarchs should be as migration capable as possible for surviving the arduous long-distance migration, we evaluated four migration-relevant traits across two groups of captive-reared monarchs ( n = 41 and 42) and one group of wild-caught migrants ( n = 41). Monarchs (descendants of wild individuals) were reared from eggs to adulthood either in a warm indoor room next to a window, or in an incubator that mimicked late-summer conditions. Using an apparatus consisting of a perch mounted to an electronic force gauge, we assessed ‘grip strength' of all groups, then used image analysis to measure forewing size, pigmentation and elongation. In three of the four traits, reared monarchs underperformed compared to wild ones, even those reared under conditions that should have produced migration-ready individuals. The average strength of reared monarchs combined was 56% less than the wild group, even when accounting for size. Their orange wing colour was paler (an indicator of poor condition and flight ability) and their forewings were less elongated (elongation is associated with migration propensity) than wild monarchs. The reason(s) behind these effects is unknown but could stem from the frequent disturbance and/or handling of reared monarchs, or the fact that rearing removes the element of natural selection from all stages. Regardless, these results explain prior tagging studies that showed reared monarchs have lower migratory success compared to wild.

Should they stay or should they go? Climate migrants and local conflicts

There is extensive evidence that higher temperatures increase the probability of local conflict. There is also evidence that emigration represents an important margin of adaptation to a warming climate. In this article, we analyse whether migration influences the link between warming and conflicts by either attenuating this connection in countries of origin and/or by exacerbating it in countries of destination. We find that in countries where the propensity to emigrate—as measured by past diaspora—is higher, increases in temperature have smaller effects on the probability of armed conflict, compared to countries with lower migration propensity. This is consistent with emigration functioning as ‘escape valve’ for local tensions. We find no evidence that climate-induced migration increased the probability of conflict in receiving countries.

Relationship of baseline and maximum glucocorticoid concentrations to migration propensity: a field test with wild subadult brown trout (Salmo trutta)

There is considerable variation in glucocorticoid (GC) baseline status and stress responses of individuals, yet the cause and consequence of this variation remains ambiguous. Attempts to relate GC levels to fitness and life-history trade-offs have yielded variable results. In this study, we evaluated whether baseline and poststressor GC hormone concentrations predicted migration strategy (i.e., resident or migrant) and successful seaward migration in a partially migrating population of juvenile brown trout (Salmo trutta Linnaeus, 1758). Baseline (N = 99) or poststressor (N = 102) plasma cortisol concentrations were obtained from brown trout and they were tagged with passive integrated transponder (PIT) and released in a natural Danish stream. Subsequently, fish were tracked with PIT reader systems and the stream was resampled for resident individuals. GC levels were not found to be associated with recapture of resident individuals or migration propensity to our first tracking station (S1), but increased baseline (and not poststressor) GC levels were associated with increased passage from S1 to our second tracking station, which anecdotally was an area of high predation or challenge. Our study found no evidence to suggest that cortisol regulates the migration life history in juvenile brown trout, but intermediate increases in baseline GC (and not poststressor GC) levels may favor migration performance.

Carrying a selfish genetic element predicts increased migration propensity in free-living wild house mice

Life is built on cooperation between genes, which makes it vulnerable to parasitism. Selfish genetic elements that exploit this cooperation can achieve large fitness gains by increasing their transmission relative to the rest of the genome. This leads to counter-adaptations that generate unique selection pressures on the selfish genetic element. This arms race is similar to host–parasite coevolution, as some multi-host parasites alter the host’s behaviour to increase the chance of transmission to the next host. Here, we ask if, similarly to these parasites, a selfish genetic element in house mice, the t haplotype, also manipulates host behaviour, specifically the host’s migration propensity. Variants of the t that manipulate migration propensity could increase in fitness in a meta-population. We show that juvenile mice carrying the t haplotype were more likely to emigrate from and were more often found as migrants within a long-term free-living house mouse population. This result may have applied relevance as the t has been proposed as a basis for artificial gene drive systems for use in population control.

The t haplotype, a selfish genetic element, manipulates migration propensity in free-living wild house mice Mus musculus domesticus

Life is built on cooperation between genes, which makes it vulnerable to parasitism. However, selfish genetic elements that exploit this cooperation can achieve large fitness gains by increasing their transmission unfairly relative to the rest of the genome. This leads to counter-adaptations that generate unique selection pressures on the selfish genetic element. This arms race is similar to host-parasite co-evolution. Some multi-host parasites alter the host’s behaviour to increase the chance of transmission to the next host. Here we ask if, similarly to these parasites, a selfish genetic element in house mice, the t haplotype, also manipulates host behaviour, specifically the host’s migration propensity. Variants of the t that manipulate migration propensity could increase in fitness in a meta-population. We show that juvenile mice carrying the t haplotype were more likely to emigrate from and were more often found as migrants within a long-term free-living house mouse population. This result may have applied relevance as the t has been proposed as a basis for artificial gene drive systems for use in population control.