Rab GTPases are the largest group of the small GTPases family, which play a pivotal role in the secretion of proteins. Arthrobotrys oligospora is a representative nematode-trapping fungus that can produce adhesive networks to capture nematodes. In this study, the roles of two Rab GTPases AoRab-7A and AoRab-2 were characterized by gene knockout in the fungus A. oligospora. The disruption of AoRab-7A hindered the mycelial growth in different media, the conidiation of ΔAoRab-7A transformants was almost abolished, and the transcription of four sporulation-related genes (AbaA, FluG, Hyp1, and VosA) was downregulated compared to the wild-type strain (WT). Furthermore, the tolerance of the ΔAoRab-7A mutants to sodium dodecyl sulfate (SDS) and HO was also significantly reduced compared to the WT, and the transcription of several genes related to environmental resistance, such as genes for catalase and trehalose synthase, was downregulated. Similarly, the extracellular proteolytic activity was decreased. Importantly, the ΔAoRab-7A mutants were unable to produce traps and capture nematodes. However, the disruption of gene AoRab-2 only affected the conidiation slightly but non-significantly, while other phenotypic traits were unaffected. Moreover, the gene AoRab-7A was also involved in the autophagy induced by nitrogen deprivation in A. oligospora. Our results revealed for the first time that the Rab GTPases are involved in the regulation of mycelial growth, conidiation, trap formation, stress resistance, and pathogenicity in the nematode-trapping fungus A. oligospora.
The cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) signalling pathway is evolutionarily conserved in eukaryotes and plays a crucial role in defending against external environmental challenges, which can modulate the cellular response to external stimuli. Arthrobotrys oligospora is a typical nematode-trapping fungus that specializes in adhesive networks to kill nematodes. To elucidate the biological roles of the cAMP-PKA signalling pathway, we characterized the orthologous adenylate cyclase AoAcy, a regulatory subunit (AoPkaR), and two catalytic subunits (AoPkaC1 and AoPkaC2) of PKA in A. oligospora by gene disruption, transcriptome, and metabolome analyses. Deletion of Aoacy significantly reduced the levels of cAMP and arthrobotrisins. Results revealed that Aoacy, AopkaR, and Aop-kaC1 were involved in hyphal growth, trap morphogenesis, sporulation, stress resistance, and autophagy. In addition, Aoacy and AopkaC1 were involved in the regulation of mitochondrial morphology, thereby affecting energy metabolism, whereas AopkaC2 affected sporulation, nuclei, and autophagy. Multi-omics results showed that the cAMP-PKA signalling pathway regulated multiple metabolic and cellular processes. Collectively, these data highlight the indispensable role of cAMP-PKA signalling pathway in the growth, development, and pathogenicity of A. oligospora, and provide insights into the regulatory mechanisms of signalling pathways in sporulation, trap formation, and lifestyle transition.
Background:
Although previous research has shown that internalizing and externalizing
behavior problems often co-occur, the relationship between the developmental trajectories of these
two types of behavior problems is understudied. The co-occurring evolutions of developmental trajectories
of two behaviors has two components: 1) the correlation between the slopes of two behavior
profiles (termed the association of the evolutions); and 2) the marginal correlation of two development
trajectory profiles, which is the development of correlation between internalizing and externalizing
behavior over time (termed the evolution of the association). The association of the evolutions and
the evolution of the association have not been fully explored in the context of the development of internalizing
and externalizing behavior problems among kindergarteners in the United States.
Methods:
The random-effects approach for joint modeling of multivariate longitudinal profiles was
used to evaluate the co-development and its temporal pattern of internalizing and externalizing behavior
problems on a nationally representative sample of 9791 kindergarteners from the Early Childhood
Longitudinal Study-Kindergarten Class of 1998-99 (ECLS-K).
Results:
here was a moderate positive association between the evolutions of the two behavior problems
with correlation coefficient of 0.319. The evolution of association between the two behaviors
was increasing over time with the correlation coefficient from 0.195 at the Fall of kindergarten to
0.291 by the time of fifth grade in general. Race and age groups act differently on the evolution of
association. The associations were getting stronger for the Asian group and older groups than their
peer groups.
Conclusion:
This investigation of the association of evolutions and the evolution of association between
the internalizing and externalizing behaviors show that the two problem behaviors reciprocally
reinforce each other and lead to increases in the other in a moderate strength and the strength is increasing
over time.
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