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Membraneless organelles are RNA–protein assemblies which have been implicated in post‐transcriptional control. Germ cells form membraneless organelles referred to as germ granules, which contain conserved proteins including Tudor domain‐containing scaffold polypeptides and their partner proteins that interact with Tudor domains. Here, we show that inDrosophila, different germ granule proteins associate with the multi‐domain Tudor protein using different numbers of Tudor domains. Furthermore, these proteins compete for interaction with Tudorin vitroand, surprisingly, partition to distinct and poorly overlapping clusters in germ granulesin vivo. This partition results in minimization of the competition. Our data suggest that Tudor forms structurally different configurations with different partner proteins which dictate different biophysical properties and phase separation parameters within the same granule.

 

The tools and techniques such as imaging and machine learning used in the measurement of many material and microstructural properties are rapidly evolving. In metals, the grain size is routinely measured to estimate the yield strength. This paper describes some of the algorithms used in processing the microstructures to conduct quantitative measurements. The image processing methods provide the possibility to go beyond calculating the ASTM grain size number and calculate the actual surface area of each grain, grain boundary length, and the shape of the grains. The image analysis methods can be very helpful in conducting detailed quantitative analysis with greater accuracy than many labour-intensive manual methods currently in use. The work describes the complexities in applying the imaging methods and approaches in the metallurgical and materials fields. Successful application of such methods can reduce the time and effort required to characterise microstructures and can provide more precise information. 

Qualifying exams and thesis committees are crucial components of a PhD candidate's journey. However, many candidates have trouble navigating these milestones and knowing what to expect. This article provides advice on meeting the requirements of the qualifying exam, understanding its format and components, choosing effective preparation strategies, retaking the qualifying exam, if necessary, and selecting a thesis committee, all while maintaining one's mental health. This comprehensive guide addresses components of the graduate school process that are often neglected.

 

Actuarial senescence (called ‘senescence’ hereafter) often shows broad variation at the intraspecific level. Phenotypic plasticity likely plays a central role in among‐individual heterogeneity in senescence rate (i.e. the rate of increase in mortality with age), although our knowledge on this subject is still very fragmentary. Polyphenism—the unique sub‐type of phenotypic plasticity where several discrete phenotypes are produced by the same genotype—may provide excellent study systems to investigate if and how plasticity affects the rate of senescence in nature.

In this study, we investigated whether facultative paedomorphosis influences the rate of senescence in a salamander,Ambystoma mavortium nebulosum. Facultative paedomorphosis, a unique form of polyphenism found in dozens of urodele species worldwide, leads to the production of two discrete, environmentally induced phenotypes: metamorphic and paedomorphic individuals. We leveraged an extensive set of capture–recapture data (8948 individuals, 24 years of monitoring) that were analysed using multistate capture–recapture models and Bayesian age‐dependent survival models.

Multistate models revealed that paedomorphosis was the most common developmental pathway used by salamanders in our study system. Bayesian age‐dependent survival models then showed that paedomorphs have accelerated senescence in both sexes and shorter adult lifespan (in females only) compared to metamorphs. In paedomorphs, senescence rate and adult lifespan also varied among ponds and individuals. Females with good body condition and high lifetime reproductive success had slower senescence and longer lifespan. Late‐breeding females also lived longer but showed a senescence rate similar to that of early‐breeding females. Moreover, males with good condition had longer lifespan than males with poor body condition, although they had similar senescence rates. In addition, late‐breeding males lived longer but, unexpectedly, had higher senescence than early‐breeding males.

Overall, our work provides one of the few empirical cases suggesting that environmentally cued polyphenism could affect the senescence of a vertebrate in nature, thus providing insights on the ecological and evolutionary consequences of developmental plasticity on ageing.

 

We present a semi-analytic model for the growth, drift, desorption, and fragmentation of millimeter- to meter-sized particles in protoplanetary disks. Fragmentation occurs where particle collision velocities exceed critical fragmentation velocities. Using this criterion, we produce fragmentation regions in disk orbital radius–particle size phase space for particles with a range of material properties, structures, and compositions (including SiO₂, Mg₂SiO₄, H₂O, CO₂, and CO). For reasonable disk conditions, compact aggregate H₂O, CO₂, and CO ice particles do not reach destructive relative velocities and are thus not likely to undergo collisional fragmentation. Uncoated silicate particles are more susceptible to collisional destruction and are expected to fragment in the inner disk, consistent with previous work. We then calculate the growth, drift, and sublimation of small particles, initially located in the outer disk. We find that ice-coated particles can avoid fragmentation as they grow and drift inward under a substantial range of disk conditions, as long as the particles are aggregates composed of 0.1μm-sized monomers. Such particles may undergo runaway growth in disk regions abundant in H₂O or CO₂ice, depending on the assumed disk temperature structure. These results indicate that icy collisional growth to planetesimally relevant sizes may happen efficiently throughout a disk’s lifetime, and is particularly robust at early times when the disk’s dust-to-gas ratio is comparable to that of the interstellar medium.

 

Monitoring soil nitrogen (N) dynamics in agroecosystems is foundational to soil health management and is critical for maximizing crop productivity in contrasting management systems. The newly established soil health indicator, autoclaved‐citrate extractable (ACE) protein, measures an organically bound pool of N. However, the relationship between ACE protein and other N‐related soil health indicators is poorly understood. In this study, ACE protein is investigated in relation to other soil N measures at four timepoints across a single growing season along a 33‐year‐old replicated eight‐system management intensity gradient located in southwest Michigan, USA. On average, polyculture perennial systems that promote soil health had two to four times higher (2–12 g kg⁻¹higher) ACE protein concentrations compared to annual cropping and monoculture perennial systems. In addition, ACE protein fluctuated less than total soil N, NH₄⁺‐N, and NO₃⁻‐N across the growing season, which shows the potential for ACE protein to serve as a reliable indicator of soil health and soil organic N status. Furthermore, ACE protein was positively correlated with total soil N and NH₄⁺‐N and negatively correlated with NO₃⁻‐N at individual sampling timepoints across the management intensity gradient. In addition, ACE protein, measured toward the end of the growing season, showed a consistent and positive trend with yield across different systems. This study highlights the potential for ACE protein as an indicator of sustainable management practices, SOM cycling, and soil health and calls for more studies investigating its relationship with crop productivity.