Modulation of the tissue composition of regenerative neuroma by dexamethasone and granulocyte colony-stimulating factor

Aim. To evaluate the change of the content of mesenchymal (vimentin-positive) and reparative Schwann (GFAP-positive) cells in the regenerative neuroma of the rat sciatic nerve, taking into account the activity of local homeostasis regulation (CD73 expression) under the influence of dexamethasone (Dex) and granulocyte colony-stimulating factor (GCSF). Materials and methods. Vimentin-, GFAP-, and CD73-positive cells were detected immunohistochemically in the regenerative neuroma of 168 male Wistar rats, and their presence was quantified using statistical methods. Results. The regenerative neuroma of the sciatic nerve is characterized by a stereotypical cellular composition kinetics. Dexamethasone, during the initial stage of neuroma formation (1–7 days), led to a reduction in inflammatory infiltration and accumulation of vimentin+ mesenchymal cells. It significantly accelerated the accumulation of neural GFAP+ reparative Schwann cells and suppressed the expression of CD73. The granulocyte colony-stimulating factor (1–3 days) in the regenerative neuroma resulted in a slight reduction in inflammatory infiltration and an increase in the number of blood vessels penetrating into it. Under these conditions, the speed and quantity of vimentin+ cell accumulation and CD73 expression noticeably increased, as well as the speed of GFAP+ cell accumulation. The deviations in the expression of vimentin, GFAP, and CD73 in the neuroma under the administration of the mentioned substances gradually decreased and, after 8 weeks of the experiment, did not differ significantly from the control. When combined, dexamethasone and granulocyte colony-stimulating factor potentiated each other’s effects and, in addition, led to long-term maintenance of high CD73 expression. At the same time, the most pronounced approximation of the structure of the newly formed part of the nerve to the structure of the intact nerve trunk was observed. Conclusions. The simultaneous action of Dex and GCSF during the initial stages of regenerative neuroma formation, in contrast to their individual actions, not only alters the dynamics of mesenchymal and neural cell accumulation but also modifies the newly formed part of the nerve, bringing its structure closer to the intact state. This phenomenon is accompanied by increased reactivity of neurolemocytes during the axial cylinder germination stage of neuroma regeneration

Dexamethasone and granulocyte colony-stimulating factor alter the representation of cellular patterns and neurotisation of regenerative neuroma

Aim. To evaluate the changes in the total cellularity (Nuc) of the rat sciatic nerve regenerative neuroma (RegN) and its representation of CD90, CD44, CD146, and CD133 positive cells, as well as its neurotization under the conditions of dexamethasone (Dex) and granulocyte colony-stimulating factor (GCSF). Materials and methods. After injections of dexamethasone and granulocyte colony-stimulating factor in the regenerative neuroma of 168 male Wistar rats, CD90, CD44, CD146 and CD133 positive cells were detected immunohistochemically in the regenerative neuroma. Its total cellularity and neurotization were determined and statistical processing of the obtained data was performed. Results. It was found that dexamethasone and granulocyte colony-stimulating factor change the representation of cellular patterns and neurotization of regenerative neuroma. Conclusions. The amount of neurotization of the regeneration neuroma directly depends on the specific amount of Schwann cells in its composition. Dex and GCSF, despite different mechanisms of action, lead to an increase in the content of neuroleumocytes in RegN

Intraguild Predation and Native Lady Beetle Decline

Coccinellid communities across North America have experienced significant changes in recent decades, with declines in several native species reported. One potential mechanism for these declines is interference competition via intraguild predation; specifically, increased predation of native coccinellid eggs and larvae following the introduction of exotic coccinellids. Our previous studies have shown that agricultural fields in Michigan support a higher diversity and abundance of exotic coccinellids than similar fields in Iowa, and that the landscape surrounding agricultural fields across the north central U.S. influences the abundance and activity of coccinellid species. The goal of this study was to quantify the amount of egg predation experienced by a native coccinellid within Michigan and Iowa soybean fields and explore the influence of local and large-scale landscape structure. Using the native lady beetle Coleomegilla maculata as a model, we found that sentinel egg masses were subject to intense predation within both Michigan and Iowa soybean fields, with 60.7% of egg masses attacked and 43.0% of available eggs consumed within 48 h. In Michigan, the exotic coccinellids Coccinella septempunctata and Harmonia axyridis were the most abundant predators found in soybean fields whereas in Iowa, native species including C. maculata, Hippodamia parenthesis and the soft-winged flower beetle Collops nigriceps dominated the predator community. Predator abundance was greater in soybean fields within diverse landscapes, yet variation in predator numbers did not influence the intensity of egg predation observed. In contrast, the strongest predictor of native coccinellid egg predation was the composition of edge habitats bordering specific fields. Field sites surrounded by semi-natural habitats including forests, restored prairies, old fields, and pasturelands experienced greater egg predation than fields surrounded by other croplands. This study shows that intraguild predation by both native and exotic predators may contribute to native coccinellid decline, and that landscape structure interacts with local predator communities to shape the specific outcomes of predator-predator interactions

A model species for agricultural pest genomics: the genome of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

The Colorado potato beetle is one of the most challenging agricultural pests to manage. It has shown a spectacular ability to adapt to a variety of solanaceaeous plants and variable climates during its global invasion, and, notably, to rapidly evolve insecticide resistance. To examine evidence of rapid evolutionary change, and to understand the genetic basis of herbivory and insecticide resistance, we tested for structural and functional genomic changes relative to other arthropod species using genome sequencing, transcriptomics, and community annotation. Two factors that might facilitate rapid evolutionary change include transposable elements, which comprise at least 17% of the genome and are rapidly evolving compared to other Coleoptera, and high levels of nucleotide diversity in rapidly growing pest populations. Adaptations to plant feeding are evident in gene expansions and differential expression of digestive enzymes in gut tissues, as well as expansions of gustatory receptors for bitter tasting. Surprisingly, the suite of genes involved in insecticide resistance is similar to other beetles. Finally, duplications in the RNAi pathway might explain why Leptinotarsa decemlineata has high sensitivity to dsRNA. The L. decemlineata genome provides opportunities to investigate a broad range of phenotypes and to develop sustainable methods to control this widely successful pest