Biology Open最新文献

Disruptions in pancreatic development can lead to health issues such as pancreatic agenesis and congenital diabetes mellitus. Understanding pancreatic organogenesis is critical for elucidating disease mechanisms and developing regenerative therapies. The pancreas consists of endocrine and exocrine cells, both of which are derived from multipotent progenitor cells (MPCs). MPC proliferation and differentiation are tightly controlled by multiple mechanisms, including post-transcriptional regulation by miRNAs. However, these regulatory factors are not fully understood. Here, we profiled miRNA expression in MPCs and identified that mir-302 was highly enriched during the earliest stages of pancreatic development. Loss of mir-302 resulted in reduced pancreatic size without altering the proportions of endocrine and exocrine cells at E17.5, suggesting that mir-302 regulates the number of MPCs rather than their differentiation. Transcriptomic analysis at E10.5 revealed that mir-302 modulates genes associated with the Wnt signaling pathway and cell cycle progression. Notably, loss of mir-302 prolonged the S phase in MPCs, resulting in slower cell proliferation and a smaller MPC pool at E10.5. These findings provide the first comprehensive miRNA profile during early pancreatic development and establish mir-302 as a critical regulator of MPC number and pancreas size.

Melanins are the most common pigments in animals and are known to experience bleaching (molecular degradation) under UV and visible radiations. However, melanin photobleaching effects on the appearance of animals under natural sunlight conditions are unclear. Here, we collected body feathers from developing Spanish imperial eagles Aquila adalberti, mainly pigmented by the orange pheomelanin, and monitored their reflectance properties during a 15-week sunlight exposure regime. Feather brightness significantly increased with exposure time following a power function, resulting in a 1.87-times increase in paleness and an obvious loss of feather integrity. Photobleaching thus explains the gradual increase in plumage paleness exhibited by juvenile imperial eagles, changing from dark orange to yellowish during the first months of age without the course of feather molt. Bleached plumage characterizes eagle immature phenotypes until reaching a contrasting blackish phenotype by progressive molt after 5-6 years, a period during which the feather degradation that accompanies bleaching may limit flight performance. Given the pheomelanin-pigmented plumages commonly observed in juvenile raptors, and in other groups of birds in which color disappears independently of molt (e.g. wheatears, genus Oenanthe), photobleaching arises as a source of phenotypic expression that may also drive life-history strategies such as crypsis and migration.

Cohesinopathies and ciliopathies are congenital disorders affecting overlapping body systems. The extent to which these syndromes may be linked remains largely untested. Recently, reduced expression of a cohesin core subunit, Smc3, was found to result in abnormal otolith development in zebrafish embryos. This finding suggests that Smc3 may contribute to kinociliary development and function, which would represent a novel role for Smc3. Using hair cells found in neuromasts of the posterior lateral line, we found that Smc3 knockdown resulted in reduced kinociliary length. To address the role of Smc3 in kinocilial function, we monitored neomycin resistance of neuromasts (associated with several cilial gene mutants) and FM1-43X uptake in hair cells (associated with mechanotransduction). We found that Smc3 knockdown indeed led to neomycin resistance of the posterior lateral line neuromasts, suggesting impaired kinocilium function. However, neuromast hair cells did not have defects in FM1-43X uptake. We further demonstrated that hair cell number is reduced within neuromasts. This study suggests a significant influence of cohesin subunit Smc3 in ciliary structure and function and provides a preliminary link between cohesinopathy and ciliopathy etiologies.

Optimization of the soil microbiome is a promising strategy to support sustainable crop production. With the goal of developing novel bio-fertilizers for wheat cultivation, we collected fresh soil samples from ten different fields representing wheat production regions in Türkiye. Wheat seedlings (Triticum turgidum ssp. durum) were cultivated in each soil and at the three-leaf stage, DNA was isolated from the rhizospheric soil associated with each plant and the bacterial microbiome composition determined by 16S metabarcoding. Long-read sequencing was used to maximize resolution, and 1269 high-quality operational taxonomic units (OTUs) were identified. Comparisons of wheat and non-wheat rhizospheric soil identified 77 OTUs that were enriched in the wheat rhizosphere, several belonging to taxa that have previously been described as plant growth-promoting rhizobacteria. Furthermore, 209 OTUs were present in all ten wheat fields sampled, indicating that they may be ubiquitous in wheat-growing regions of Türkiye; a subset of these were also reported in wheat rhizospheric soil from other countries. Additional taxa were shown to be enriched based on local soil conditions such as pH and macronutrient content. These findings shed light onto the essential composition of the wheat rhizospheric microbiome, which provides a foundation for the development of locally adapted bio-fertilizers.

Macropinocytosis is an endocytic process that allows cells to respond to changes in their environment by internalizing nutrients and cell surface proteins, as well as modulating cell size. Here, we identify that adenosine triphosphate (ATP) triggers macropinocytosis in murine Neuro2a neuroblastoma cells, driving an increase in cell size, and internalizing the ATP release channel pannexin 1 (PANX1) to macropinosomes. Amiloride treatment and mutation of an extracellular tryptophan (W74) in PANX1 abolished ATP-evoked cell area enlargement, suggesting that PANX1 may itself regulate this form of macropinocytosis. Transient expression of the GTP-hydrolysis resistant ADP-ribosylation factor 6 GTPase (ARF6 Q67L) led to increased cell size, PANX1 internalization and localization to endosomal compartments, consistent with macropinocytosis. Inhibiting macropinocytosis-associated GTPases, phosphoinositide-3 kinase (PI3K), and disrupting actin polymerization abolished ATP-induced PANX1 internalization, supporting a macropinocytic mechanism. Further, these inhibitors disrupted co-distribution of intracellular PANX1 with macropinosomal cargo. Several lipid-PANX1 interactions were identified with relevance to macropinocytic mechanisms. The role of PANX1 in ATP-mediated macropinocytosis could be particularly important for disease states implicating PANX1, such as cancer, where ATP can act as a purinergic regulator of cell growth/metastasis and as a supplementary energy source following internalization.

Down syndrome (DS) is caused by trisomy for human chromosome 21 (Hsa21) and is associated with atypical neurodevelopment that begins prenatally. The developing human fetus receives nutritional support and gas exchange from the placenta, and normal placental function is essential for proper development. Placentas that sustain fetuses with trisomy 21 contain trisomic cells, but little is known about which Hsa21 genes are overexpressed in the placenta or their downstream molecular, cellular, and functional effects. Although access to human placentas is limited, mouse models of DS provide excellent in vivo systems for investigating the prenatal effects of trisomy. This study examined the placental transcriptome in four mouse models of DS: Dp(16)1/Yey, Ts65Dn, Ts66Yah, and Ts1Cje. Placental gene and protein expression analyses showed that trisomy increased the expression of App, Sod1, and Ifnar1 in Dp(16)1/Yey, Ts65Dn, and Ts66Yah; APP and SOD1 in Dp(16)1/Yey and Ts66Yah; and IFNAR1 in Ts66Yah. Despite modest overlap of trisomy-associated gene dysregulation among these four models, altered extracellular matrix pathways in all four models and upregulation of immune system pathways in Dp(16)1/Yey and Ts66Yah were identified. Altered redox homeostasis was observed for all four models, with Ts1Cje showing distinct changes in SOD activity and antioxidant capacity in comparison to the other three models. Immunofluorescence staining revealed region-specific upregulation of APP, SOD1, and IFNAR1 in Ts66Yah trisomic placentas. This work provides a foundation for understanding the effects of trisomy for Hsa21 orthologs on the mouse placenta and on prenatal development.

Increased heat and drought from Anthropogenic climate change will challenge the adaptive capacity of species, underscoring the need to understand thermal ecology - how organisms behaviorally and physiologically respond to temperature. We used noninvasive infrared thermography (IRT) to examine the thermal ecology of threatened narrow-headed gartersnakes (Thamnophis rufipunctatus) in a conservation breeding program at the Arizona Center of Nature Conservation/Phoenix Zoo. From 718 microhabitat and 124 individual measurements, hierarchical models identified extrinsic and intrinsic factors influencing microhabitat usage, body temperature (Tb), and behavior. Gartersnakes exhibited regional heterothermy, with tails cooler than head and trunk segments. The Tb of T. rufipunctatus was shaped by perch temperature, perch-air temperature, and whether snakes were visibly exposed or hidden. We documented microhabitat aggregations (≥2 gartersnakes) in ca. 40% of observations, which was best predicted by Tb. Thamnophis rufipunctatus appeared to favor cavity-bearing microhabitats, consistent with wild populations. This first application of IRT to snakes in semi-natural environments, and for T. rufipunctatus specifically, provides novel insights to guide more effective field surveillance and conservation management, while demonstrating the broader value of IRT and collaborative ex situ studies for wildlife conservation.

Post-translational modifications (PTMs) of microtubules control many aspects of their functionality. Specifically, the C-terminal tails of α- and β-tubulin harbour a complex array of PTMs, including polyglutamylation and the reversible detyrosination/tyrosination. The spatial proximity of these two distinct sets of PTMs suggests the possibility of a functional cross-talk between polyglutamylation and (de)tyrosination. In this study, we employ gene deletion and overexpression of the enzymes tubulin-tyrosine ligase (TTL) and tubulin-tyrosine carboxypeptidase (VASH) to provide a detailed analysis of the effects of (de)tyrosination on the protozoan parasite Trypanosoma brucei. While the deletion of either of the enzymes is not lethal, cells exhibit subtle morphological defects, resulting from both hyper- and hypotyrosination. Additionally, hypertyrosination leads to defects in motility, characterised by an increase in tumbling motion. Using the TTL and VASH deletion cells in conjunction with our previously generated trypanosomes deficient in polyglutamylation, we uncovered a cross-talk between these two PTMs. The process of microtubule detyrosination enhances polyglutamylation, which, in turn, stimulates efficient detyrosination, thus establishing a positive feedback loop between these two PTMs.

Effective methods of anesthesia for octopuses are essential to physiological studies as well as for their welfare in scientific research. However, commonly used forms of general anesthesia using ethanol, magnesium chloride, and similar agents have certain drawbacks. While these methods effectively induce still states in the octopus, they also affect the peripheral body and nervous system and are therefore less than optimal for studying local behavior in octopus arms and suckers. Further, stupefying effects outlast the anesthetized state. We explore an old, rarely used method of octopus 'hypnosis' in which tonic immobility is induced as a complementary and sometime alternative method to general anesthesia, as well as being particularly suited to studies of local arm-sucker coordination. We modify the procedure for better handling, unimpeded respiration, and isolation of arm peripheral nervous system from the central nervous system (CNS). In the still state, an arm can be neurophysiologically isolated from the CNS by local Mg2+ injection, removing need for isolation by amputation. Exemplary studies of arm-sucker coordination and electrode placements are presented. Additionally, an intriguing phenomenon is observed where the induction of tonic immobility is notably diminished in cases of senescence. This modified procedure offers new convenience and directions for octopus neurobehavioral research.

Branching morphogenesis requires dramatic changes in cell polarity, proliferation, migration, and actin dynamics to elaborate tubular networks. However, little is known about how microtubules support these cell behaviors in 3D tissues. Using organotypic cultures, we first examined the organization of the microtubule cytoskeleton. Simple luminal epithelial cells exhibited non-centrosomal, apico-basally oriented microtubule arrays, while stratified luminal cells had centrosomally radiating microtubules. During collective migration, luminal cells adopted an ameboid-like organization with a rear-facing nuclear-centrosomal axis. Multiple staining approaches suggest that cells in the basal-most luminal cell layer had more stable microtubules than cells deeper within the stratified layer. Finally, we tested the requirement for microtubules using pharmacologic inhibitors. Both microtubule stabilization and destabilization prevented bud formation and arrested duct elongation. Cell tracking analysis demonstrated that microtubules coordinated luminal cell migration within elongating buds. Destabilizing microtubules reduced cell directionality, while stabilizing microtubules did not affect directionality but reduced cell motility. Our data reveal that microtubules are essential for collective migration of luminal cells and for mammary branching morphogenesis.