Histological and single-nucleus transcriptome analyses reveal the specialized functions of ligular sclerenchyma cells and key regulators of leaf angle in maize.

Leaf angle (LA) is a crucial factor that affects planting density and yield in maize. However, the regulatory mechanisms underlying LA formation remain largely unknown. In this study, we performed a comparative histological analysis of the ligular region across various maize inbred lines and revealed that LA is significantly influenced by a two-step regulatory process involving initial cell elongation followed by subsequent lignification in the ligular adaxial sclerenchyma cells (SCs). Subsequently, we performed both bulk and single-nucleus RNA sequencing, generated a comprehensive transcriptomic atlas of the ligular region, and identified numerous genes enriched in the hypodermal cells that may influence their specialization into SCs. Furthermore, we functionally characterized two genes encoding atypical basic-helix-loop-helix (bHLH) transcription factors, bHLH30 and its homolog bHLH155, which are highly expressed in the elongated adaxial cells. Genetic analyses revealed that bHLH30 and bHLH155 positively regulate LA expansion, and molecular experiments demonstrated their ability to activate the transcription of genes involved in cell elongation and lignification of SCs. These findings highlight the specialized functions of ligular adaxial SCs in LA regulation by restricting further extension of ligular cells and enhancing mechanical strength. The transcriptomic atlas of the ligular region at single-nucleus resolution not only deepens our understanding of LA regulation but also enables identification of numerous potential targets for optimizing plant architecture in modern maize breeding.

A chromosome-level genome of electric catfish (Malapterurus electricus) provided new insights into order Siluriformes evolution.

The electric catfish (Malapterurus electricus), belonging to the family Malapteruridae, order Siluriformes (Actinopterygii: Ostariophysi), is one of the six branches that has independently evolved electrical organs. We assembled a 796.75 Mb M. electricus genome and anchored 88.72% sequences into 28 chromosomes. Gene family analysis revealed 295 expanded gene families that were enriched on functions related to glutamate receptors. Convergent evolutionary analyses of electric organs among different lineage of electric fishes further revealed that the coding gene of rho guanine nucleotide exchange factor 4-like (arhgef4), which is associated with G-protein coupled receptor (GPCR) signaling pathway, underwent adaptive parallel evolution. Gene identification suggests visual degradation in catfishes, and an important role for taste in environmental adaptation. Our findings fill in the genomic data for a branch of electric fish and provide a relevant genetic basis for the adaptive evolution of Siluriformes. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-023-00197-8.

Enhanced transdermal lymphatic delivery of doxorubicin via hyaluronic acid based transfersomes/microneedle complex for tumor metastasis therapy.

Tumor-draining lymph nodes (TDLN) are major metastatic sites for many solid tumor to support tumor progression and metastasis. Lymphatic delivery is regarded as a desirable route to promote adoptive immune response via vaccination, or to achieve efficient chemotherapy for tumor metastasis. In this study, a novel dissolving microneedle was fabricated using hyaluronic acid, integrated with transfersome (T) to break the limit of transdermal cargo transit. In virtue of the insertion capacity of microneedle and the lymphatic delivering ability of transfersomes, such transfersome/microneedles complex (T/MNs) was expected to enhance lymphatic delivery. The results revealed that the microneedles were able to efficiently insert into rat skin and release the doxorubicin loaded transfersome (DOX-T) in dermis via self-dissolution. DOX-T would maintain their multilayer structure as released from dissolved microneedles. DOX-T/MN could significantly promote accumulation of DOX in lymph nodes compared to epidermal diffusion, and increased its transdermal bioavailability in plasma. The results not only are promising for chemo-therapy of tumor through lymphatic drug delivery, especially for killing the metastasized tumor cells appeared in draining lymph nodes, they also provide an efficient strategy for tumor immune-therapy using transdermal administration.